Amine crosslinked methacrolein copolymers for coatings, binders and adhesives

Aqueous, solution or emulsion, and solvent based compositions comprising a crosslinked vinyl addition polymer having methacrylaldimine crosslinking groups are useful as coatings, binders and adhesives. The polymers are prepared from a crosslinkable composition comprising (A) a vinyl addition homopolymer or copolymer of methacrolein and (B) a compound having at least two amine-function groups selected from primary amine and primary amine-generating groups. A method of use is described in which crosslinking is at ambient temperatures.

BACKGROUND OF THE INVENTION 
This invention relates to polymers crosslinked by means of 
methacrylaldimine linkages or crosslinking groups. The methacrylaldimine 
crosslinking groups are produced by reaction of vinyl addition 
homopolymers or copolymers of methacrolein and compounds having at least 
two primary amine or primary amine-generating, such as aldimine or 
ketimine, groups. The crosslinking occurs, preferably at ambient 
temperatures or at elevated temperatures, to produce a crosslinked 
polymer. 
Neher et al, U.S. Pat. No. 2,416,536, teaches the copolymerization of 
acrolein and methacrolein with acrylic compounds, such as the acid, 
esters, nitrile, and amides. Neher further teaches that the copolymers 
containing 10% or more of acrolein or methacrolein are vulcanizable with 
sulfur. Larsson et al, U.S. Pat. Nos. 3,896,085 and 4,016,127, teach the 
treatment of leather with copolymers containing acrolein and the curing of 
these with a poly-primary amine. 
The new methacrylaldimine crosslinked polymers are surprisingly superior to 
acrylaldimine crosslinked polymers in several properties, such as 
resistance to thermal degradation, resistance to water and aqueous 
solutions and color stability. Formulations of methacrolein polymers with 
poly-primary amines have much longer, and thus more useful, pot lives than 
do the corresponding acrolein polymer formulations. 
SUMMARY OF THE INVENTION 
The present invention is concerned with a crosslinked vinyl addition 
polymer comprising methacrylaldimine crosslinking groups, and the 
preparation and use of the polymer. Generally, the crosslinked polymer is 
widely useful in applications such as in coating, binder, and adhesive 
formulations. The preferred way of making the crosslinked polymer is to 
mix a composition comprising (A) a vinyl addition homopolymer or copolymer 
of methacrolein and (B) a compound having at least two amine functional 
groups selected from primary amine and primary amine-generating groups. 
The composition is cured, preferably at ambient temperature, to form the 
crosslinked polymer. The primary amine-generating groups referred to are 
groups which, under ambient conditions and in the composition, will 
generate primary amine groups for reaction with the aldehyde groups of the 
methacrolein units to produce the methacrylaldimine crosslink or, 
alternatively, will produce said crosslink by reaction with the aldehyde 
groups without necessarily going through a stage involving free primary 
amine groups being present in the reacting composition. Examples of 
primary amine-generating groups are aldimine and ketimine groups, those 
based on volatile aldehydes and volatile ketones are preferred. 
Component (B) is frequently referred to hereinafter, for the sake of 
simplicity, as a polyamine containing molecule, but it is to be understood 
that such passages are intended to embrace component (B) molecules 
containing imine groups, i.e. aldimine and ketimine groups, or the salts 
of the amine or imine groups with acids, except where the context is 
clearly and completely inconsistent with such broader construction. 
Component (B) may be in the form of a simple small molecule with the 
required two or more amine groups or it may be polymeric in nature. 
Component (A) of the composition is a vinyl addition homopolymer or 
copolymer of methacrolein. In a copolymer, the methacrolein is 
copolymerized with other vinyl monomers such as ethylenically unsaturated 
carboxylic acids, ethylenically unsaturated hydrocarbons, vinyl esters of 
aliphatic acids, preferably C.sub.1 to C.sub.11 acids, and acrylates and 
methacrylates including the amides, nitriles and esters, preferably 
C.sub.1 to C.sub.8 alkyl esters. Preferably, the component (A) polymer is 
polymerized from about 2 to 50% methacrolein, about 2 to 20% of the 
carboxylic acid or a mixture thereof, about 40 to 95% ethylenically 
unsaturated aromatic hydrocarbons, acrylate esters, methacrylate esters or 
a mixture thereof, and about 0 to 15% of acrylate or methacrylate amides 
or nitriles or a mixture thereof. Desirably the acrylate is a C.sub.1 to 
C.sub.8 alkyl ester, the methacrylate is a C.sub.1 to C.sub.4 alkyl ester 
and the hydrocarbon is styrene or vinyl toluene. 
In formulating the composition, consideration is given to the possibility 
that not all of the aldehyde functions in the methacrolein-containing 
polymer are available for reaction with the amine. A suitable test for 
available aldehyde functionality is used and the ratio of (A) to (B) is 
preferably such as to contain about 1:1 available aldehyde functions to 
amine functions. The ratios varying somewhat from the 1:1 ratio are also 
useful, but usually lie within the limits 3:2 and 2:3, and are preferably 
between 0.9:1 and 1:0.9. 
DETAILED DESCRIPTION 
The crosslinked vinyl addition polymer of the instant invention comprises 
methacrylaldimine crosslinking groups of the formula 
##STR1## 
wherein 
n is an integer greater than 1 and 
R is an organic radical with the functionality n derived from an 
n-functional primary amine or polyamine. 
The multi-functional R group is part of the crosslinking group. R is bonded 
to imine nitrogen atoms of the crosslinking group which are bonded via the 
adjacent imine carbon atoms, to the methacryl group in the backbone or 
main chain of the vinyl addition polymer molecules so crosslinked. 
Preferably, the crosslinked polymer is made from a composition comprising 
(A) a vinyl addition homopolymer or copolymer of methacrolein and (B) a 
compound having at least two amine function groups selected from primary 
amine and primary amine-generating groups. The methacrolein polymer has 
the mer units 
##STR2## 
in the vinyl addition polymer chain and the amine has the formula 
EQU R(NH.sub.2).sub.n (III) 
wherein n is an integer greater than 1. 
The homopolymer or copolymer of methacrolein is frequently referred to 
hereinafter, for the sake of simplicity, as the aldehyde-containing 
polymer. The aldehyde-containing polymer, component (A), is an 
uncrosslinked linear vinyl addition polymer, or mixture of such polymers, 
having a weight average molecular weight (Mw) from about 600 to 3,000,000 
or higher. The term "linear" hereinabove being construed to include 
branched as well as straight chain linkages. For many purposes, the 
aldehyde-containing polymer is preferably one having a low molecular 
weight e.g. up to 30,000 Mw. In some cases it is desirable that the 
aldehyde-containing polymer have sufficient hydrophilic groups, e.g. 
--NHR'(R' being lower alkyl), --OH, --COOH, or depending on pH, the 
carboxyl may be in the form of a salt of an organic amine, other than 
primary amine, or an alkali metal, to render this component 
water-dispersible or even water-soluble. The preferred aldehyde-containing 
polymers are solution polymers of intermediate weight average molecular 
weight (Mw), i.e. 10,000 to 100,000, preferably 10,000 to 50,000. Also 
useful are emulsion polymers with Mw above 50,000, preferably 300,000 to 2 
million. Some embodiments are preferably water-soluble, others organic 
solvent soluble, and others are soluble in both water and organic 
solvents. 
The addition polymers constituting component (A) are made by any of the 
known procedures for vinyl addition polymerization such as bulk 
polymerization, solution polymerization, suspension polymerization and 
emulsion polymerization; solution and emulsion polymerization being 
preferred. Any addition copolymerizable ethylenically unsaturated monomer 
having a group H.sub.2 C.dbd.C&lt; or &gt;C.dbd.C&lt; may be used for 
copolymerization except those comprising primary amine groups or groups 
which generate primary amines under the polymerization conditions. 
Certain preferred polymers of component (A) are copolymers of ethylenically 
unsaturated acids generally in the range of about 2 to 20%, preferably 5 
to 10%, by weight. To obtain water dispersible copolymers about 2% to 10% 
acid is usually employed depending on the hydrophilic nature of the other 
monomers. When water solubility of the copolymer is desired about 5% to 
15% or even more acid monomer is used in the copolymer, the higher levels 
being needed when the remaining monomers are relatively hydrophobic. 
Examples of the .alpha.,.beta.-ethylenically unsaturated carboxylic acids 
which are used in forming copolymers of the present invention, include 
acrylic, methacrylic, itaconic, aconitic, crotonic, citraconic, 
methacryloxypropionic, maleic, fumaric, cinnamic, mesaconic, 
.alpha.-chloroacrylic and the like acids. Mixtures of these acids can also 
be used. 
The unsaturated hydrocarbon monomers which can be used in forming the 
copolymers of the present invention, include ethylene, propylene, 
isobutene, butylene, amylene, hexylene, butadiene, isoprene and 
particularly the vinyl aromatic monomers such as styrene, vinyl toluene 
and other alkyl and dialkylstyrenes. Mixtures of these hydrocarbons can 
also be used. In some preferred embodiments of the invention, the 
copolymers contain from about 10% to about 20% by weight of unsaturated 
hydrocarbon monomer. 
Examples of the acrylic acid esters which can be used in forming the 
copolymers of the present invention include the esters of C.sub.1 
-C.sub.18 alcohols such as benzyl, cyclohexyl, isobornyl, methyl, ethyl, 
propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, and the 
several amyl, hexyl, octyl (including 2-ethylhexyl), decyl, dodecyl and 
octadecyl isomers and the like. Acrylic acid esters of alcohols having 
other functionality, in addition to the alcohol functionality used in 
forming the ester, can be used in forming the copolymers of this 
invention, such as hydroxyethyl, hydroxypropyl, methoxyethoxyethyl, 
ethoxyethoxyethyl, methoxyethyl, ethoxyethyl, and the like acrylates. 
Mixtures of these esters can also be used. Preferably, lower alkyl, i.e. 
(C.sub.1-C.sub.8) esters of acrylic acid and more desirably (C.sub.1 
-C.sub.4) esters of acrylic acid are employed. In some preferred 
compositions, the copolymers contain from about 10 to about 40% by weight 
of an acrylic acid ester. 
The methacrylic acid esters which can be used as a monomer in forming the 
copolymers of the present invention, include methyl, ethyl, propyl, 
isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, amyl, isoamyl, hexyl, 
cyclohexyl, 2-ethylbutyl, 2-ethylhexyl, octyl, decyl, lauryl, myristyl, 
cetyl, stearyl, dicyclopentenyl and the like methacrylates. Methacrylic 
acid esters of alcohols having other functionality, in addition to the 
alcohol functionality used in forming the ester, can be used in forming 
the copolymers of this invention, such as hydroxyethyl, hydroxypropyl, 
methoxyethoxyethyl, ethoxyethoxyethyl, methoxyethyl, ethoxyethyl, and the 
like methacrylates. Mixtures of these esters can also be used. Preferably 
lower alkyl, i.e. (C.sub.1 -C.sub.8), and more desirably (C.sub.1 
-C.sub.4), esters of methacrylic acid are employed. In some preferred 
compositions, the copolymers of the invention contain from about 20 to 
about 60% or even 80% by weight of a methacrylic acid ester. Compositions 
consisting essentially of methacrolein and methacrylate ester mer units 
are very useful, particularly where outdoor stability is desired. 
Other ethylenically unsaturated monomers can be used in forming the 
copolymers of the instant invention, such as the esters of vinyl alcohol 
(including the formic, acetic, propionic, butyric and versatic acid 
esters; the acetic ester being preferred), acrylonitrile, 
methacrylonitrile, ethacrylonitrile, phenylacrylonitrile, acrylamide, 
methacrylamide, ethacrylamide, N-methylol acrylamide, N-monoalkyl and 
N-dialkyl acrylamides and methacrylamides (including N-monomethyl, -ethyl, 
-propyl, -butyl, and N-dimethyl, -ethyl, -propyl, -butyl, and the like), 
the corresponding aromatic amides (such as N-monophenyl- and -diphenyl- 
acrylamides and methacrylamides), vinyl ethers (such as butyl vinyl 
ether), N-vinyl lactams (such as N-vinyl pyrrolidone), halogenated vinyl 
compounds (such as vinylidene fluoride, vinyl chloride, and vinylidene 
chloride), itaconic monoesters and diesters of the alcohols used in 
forming the acrylic acid esters, supra, allyl and methallyl esters of 
saturated monocarboxylic acids (such as those used to form esters of vinyl 
alcohol, supra), vinyl thiophene, vinyl pyridine, vinyl pyrrole, and 
ethylenically unsaturated monomers containing a quaternary ammonium group 
(such as methacryloxyethyl trimethyl ammonium chloide and acryloxyethyl 
trimethyl ammonium chloride). 
The copolymers of the present invention are preferably prepared by 
conventional solution or aqueous emulsion polymerization techniques, 
however, bulk, suspension or other polymerization methods can be used. 
In coating applications it is preferred to have an aldehyde content ranging 
from about 5.0 to about 25% by weight. Less preferred formulations and 
other uses employ up to 35% or even 50% or as little as 2% methacrolein. 
Of the many monomers that can be used to copolymerize the methacrolein, 
those especially preferred include styrene (S), ethyl acrylate (EA), 
n-butyl acrylate (BA), n-butyl methacrylate (BMA), methyl methacrylate 
(MMA), acrylonitrile (AN), acrylic acid (AA), and methacrylic acid (MAA). 
The solution polymerization may be effected by free radicals obtained from 
the thermal decomposition of peresters, such as t-butyl peroxypivalate and 
t-butyl peroctoate. However, any of the conventional free radical 
initiators can be used, including azonitriles, peroxycarbonates and 
peroxides. The amount of initiator generally used is ca. 1% to 4% by 
weight, based on the monomers to be polymerized. However, this amount can 
be over a broader range, e.g., from about 0.1 to about 10% by weight. 
Among the useful initiators are the azonitriles such as 2,2'-azobis 
(isobutyronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile) and 
1,1'-azobis (cyclohexanecarbonitrile), the peroxycarbonates such as 
di(n-propyl) peroxydicarbonate, diisopropyl peroxydicarbonate, 
dicyclohexyl peroxydicarbonate and di(2-ethylhexyl) peroxydicarbonate, and 
the peroxides, such as hydrogen peroxide, t-butyl hydroperoxide, benzoyl 
peroxide, t-butyl peracetate and t-butyl perbenzoate. 
As in emulsion polymerization, infra, chain transfer agents can be used to 
moderate the molecular weight of the copolymer. The same transfer agents 
and amounts are generally effective. 
In the preparation of water soluble or water reducible methacrolein 
copolymers, the monomers can be polymerized in a water miscible solvent 
such as butoxy ethanol, ethoxyethyl acetate, isopropanol or isobutanol, 
and subsequently the acidic groups are neutralized and the system diluted 
with water. The organic solvent can either be retained as part of the 
solvent or removed under reduced pressure at a slightly elevated 
temperature, preferably less than 100.degree. C. The neutralization of the 
carboxyl functionality, when present in the polymers, can be accomplished 
with inorganic bases, e.g., sodium or potassium hydroxides, or organic 
bases not having primary amine functionality, e.g., secondary or tertiary 
amines, and, amino alcohols and other common bases. The neutralization 
should be stoichiometric or less to avoid reaction with the aldehyde 
functionality. The preferred bases for neutralization are tertiary amines 
such as dimethylamino ethanol, N-methyldiethanol amine, triethyl amine and 
N-methyl morpholine. 
In the preparation of the present copolymers by emulsion polymerization 
techniques, the emulsifiers or dispersing agents employed and general 
emulsion polymerization techniques are taught in "Emulsion Polymerization" 
by F. A. Bovey et al, Interscience Publishers, 1965, and "Emulsion 
Polymerization" by D. C. Blackley, John Wiley & Sons, publishers, 1975. 
The polymerizable monomer emulsions can be prepared at a temperature in 
the range of from about 0.degree. C. to about 100.degree. C. and, if a 
pressurized reactor is used, even higher, but intermediate temperatures 
are generally preferred. Although other free radical initiators are 
useful, peroxide free-radical catalysts, particularly catalytic systems of 
the redox type, are recommended. Such systems, as is well known, are 
combinations of oxidizing agents and reducing agents such as a combination 
of potassium persulfate and sodium metabisulfate. Suitable peroxidic 
agents include the "persalts" such as the alkali metal and ammonium 
persulfates and perborates, hydrogen peroxide, organic hydroperoxides, 
such as tert-butyl hydroperoxide and cumene hydroperoxide, and esters such 
as tert-butyl perbenzoate. Reducing agents include water-soluble 
thiosulfates, hydrosulfites, tertiary amines, such as triethanolamine and 
the like, thiourea and salts of metals such as the sulfate salts of metals 
capable of existing in more than one valence state such as cobalt, iron, 
nickel, and copper. 
A convenient method of preparing the copolymer latex comprises agitating an 
aqueous suspension or emulsion of the mixture of copolymerizable monomers 
and redox catalytic combination at room temperature without the 
application of external heat. The amount of catalyst can vary but the 
usual range is from 0.01 to 3.0% of the peroxidic agent and the same or 
lower proportions of the reducing agent based on the weight of the 
monomer. In this way, it is possible to prepare latices which contain as 
little as 1% and as much as 60% or even more of the resinous copolymers on 
a weight basis. It is more practical and preferred to produce latices 
which contain from about 30 to about 50% resin solids. 
If desired, a chain-transfer agent is used to moderate the molecular weight 
of the copolymer obtained by the emulsion copolymerization procedure. the 
art-known chain-transfer agents may be used, such as: long-chain alkyl 
mercaptans, such as tert-dodecyl mercaptan; alcohols, such as isopropanol, 
isobutanol, lauryl alcohol, and tertoctyl alcohol; halogenated 
hydrocarbons, such as carbon tetrachloride, tetrachloroethylene and 
trichlorobromomethane. Generally, from about 0 to 3%, by weight, based on 
the weight of the monomer charge, of the chain-transfer agent is used. 
The available aldehyde functionality, i.e., reactive sites in the 
methacrolein copolymers can be determined by oxime formation as described 
by W. M. D. Bryant and D. M. Smith, Journal of the American Chemical 
Society, Vol. 57, p. 57 or by nuclear magnetic resonance spectroscopy. The 
oxime formation method is preferred for it is regarded as a better index 
of the curing reaction of the invention. The aldehyde availability 
(expressed as the percentage of the aldehyde charged in the 
polymerization) is generally 60-75% for methacrolein polymers. The 
determined available aldehyde is used as a guideline for formulation with 
the polyfunctional amine crosslinking agent which reacts to give a cured 
coating material according to the present invention. The preferred 
coatings are obtained from stoichiometric blends of a polyamine and 
aldehyde copolymer; the stoichiometry being based on available aldehyde. 
The polyfunctional amines which can be used in curing the copolymers, 
particularly for curing at room temperature, include ethylenediamine, the 
poly(ethyleneamine) compounds such as diethylenetriamine, 
triethylenetetramine and tetraethylenepentamine, 1,2-propylene diamine, 
1,3-propylene diamine, the butane diamines, the pentane diamines, methane 
diamine, the other poly-(methylene)amines such as hexamethylene diamine, 
dihexamethylenetriamine, 2,5-dimethyl-2,5-diaminohexane, isophorone 
diamine, bis-4,4'-diaminocyclohexylmethane, 1,2-diaminocyclohexane, 
2,4-bis(p-aminobenzyl)analine, polyoxyalkyleneamines such as H.sub.2 
NCH(CH.sub.3)CH.sub.2 [OCH.sub.2 CH(CH.sub.3)].sub.x NH.sub.2, preferably 
wherein x is from about 2 to about 35 and 
##STR3## 
wherein y may have different values in the three amine terminated groups, 
the sum of the y values for one molecule being preferably between about 3 
and about 15, including the commercial material Jeffamine.RTM. T-403 
(Jefferson Chemical Co.) wherein the sum of the values is believed to be 
5.3, and the poly(propyleneamine) compounds such as dipropylenetriamine 
and tripropylenetetramine. Of these Jeffamine T-403 and methane diamine 
are preferred. 
Other amines used as curing agents include polyfunctional amine oligomers 
and polymers such as the aldimine, ketimine and primary amine polymers 
disclosed in U.S. Pat. No. 3,037,969. The polymers include homopolymers 
and copolymers of imines having the formulas 
##STR4## 
where 
m is 4 or 5, 
n is 1 or 2, 
A is a (C.sub.2 -C.sub.12) alkylene group, 
R.sup.1 is a (C.sub.1 -C.sub.12)alkyl or a cycloalkyl group, 
R.sup.2 is a (C.sub.1 -C.sub.12)alkyl or a cycloalkyl group, and 
R.sup.3 is selected from the group consisting of phenyl, halo phenyl, and 
alkoxyphenyl in which the alkoxy group has one to four carbon atoms. 
Also the primary amines corresponding to the hydrolysates of these polymers 
whether or not prepared by a procedure involving the hydrolysis of the 
imine polymers. That is, the polymers may be made directly from the 
following primary amine monomer 
##STR5## 
In the same way the polymers disclosed in U.S. Pat. No. 3,497,485 are also 
useful as curing agents or crosslinkers in the instant invention. These 
polymers are homopolymers and copolymers of ketimines, aldimines or 
primary amines having structure 
##STR6## 
wherein: 
Q is selected from the group consisting of H.sub.2, 
##STR7## 
E is H or it may be methyl in one CHE unit, 
n, m, R.sup.1, R.sup.2 and R.sup.3 are defined above. 
A', B, and D are the same or different oxyalkylene groups having the 
formula 
##STR8## 
R.degree. being individually selected from the group consisting of H and 
alkyl radicals having 1 to 2 carbon atoms, 
n.degree. is an integer having a value of 1 to 200, 
n' is an integer having a value of 1 to 200, and 
n" is an integer having a value of 1 to 200, the sum of n.degree.-1, n'-1, 
and n"-1 having a value of 2 to 200. 
Preferred compounds are those of the Formula VIII in which the sum of 
n.degree.-1, n'-1, and n"-1 has a value of 2 to 10. 
U.S. Pat. No. 3,037,969 and 3,497,485 are incorporated herein by reference. 
In formula VIII Q may represent two hydrogen atoms each bonded to the 
nitrogen atom, the structure being a primary amine in this instance. A 
further class of polymeric products having primary amines useful as the 
crosslinking amine in this invention are those of the oligomeric 
amino-containing aminolysis products of polymethacrylates or polyacrylates 
disclosed in U.S. Pat. No. 4,120,839, incorporated herein by reference, 
comprising multiple primary amine functions. 
The "pot-life", i.e. reaction time, of the aldehyde polymer/amine 
crosslinking system can be controlled by the choice of the polyamine or 
polyamine-generating crosslinker, available aldehyde and backbone 
composition of the aldehyde polymer. The reactivity of primary amines is 
dependent on the nature of the carbon adjacent to the amine. Generally, an 
amine attached to a primary carbon reacts faster than one attached to a 
secondary which reacts faster than one attached to a tertiary; i.e. in 
rate of reaction R--(CH.sub.2 NH.sub.2).sub.x exceeds R--(CHR.sup.1 
NH.sub.2).sub.x which exceeds R--(CR.sup.1 R.sup.2 NH.sub.2).sub.x where 
R, R.sup.1 and R.sup.2 are alkyl groups and x is an integer greater than 
1. Copolymerizing methacrolein with bulky monomers, e.g., butyl acrylate, 
butyl methacrylate or styrene tends to slow the rate of reaction with 
amines. 
The reactivity of the amines with the methacrolein containing polymers can 
generally be slowed by masking the amines with single mono-aldehydes and 
-ketones to form ketimines or aldimines as described in U.S. Pat. Nos. 
3,037,969, to Hankins et al., and 3,497,485, to Emmons, supra. The 
reaction is illustrated below: 
##STR9## 
where R, R.sup.1, R.sup.2 are alkyl groups and x is an integer greater 
than 1. 
The equilibrium of the above reaction is driven to the right by removal of 
water and to the left by the addition of water and removal of 
mono-aldehyde or -ketone. Indeed a rapid reversal to the amine and ketone 
or aldehyde occurs in the presence of water. Hence, the pot-life of the 
aldehyde-containing polymer/crosslinker imine formulation is extended 
since the free amine is not available until water is admitted into the 
system. In practice, a film is formed, by brushing, casting, rolling, 
spraying, dipping or other coating or forming means, then atmospheric 
moisture frees or activates the amine and promotes the crosslinking of the 
copolymer. The carbonyl compounds which may be employed to mask the amines 
include those disclosed in U.S. Pat. Nos. 3,037,969 and 3,497,485, 
preferably, benzaldehyde, halobenzaldehyde, p-chloro-benzaldehyde, 
m-methoxy benzaldehyde, cyclo-pentanone, cyclo-hexanone, acetone, methyl 
ethyl ketone, methyl propyl ketone, methyl isobutyl ketone, methyl 
isopropyl ketone and diisobutyl ketone. 
The compositions comprising the amine-containing compound (B) and the 
polymer of methacrolein (A) have room temperature pot stability falling in 
the range of about 15 minutes to several days depending on the particular 
amine-functional compound used for component (B) and the particular 
methacrolein polymer used therein. An imine-containing compound as 
component (B) produces considerably longer stability. The stability of 
both amine and imine group-containing compositions can be enhanced by 
storage at temperatures below normal ambient temperatures, such as about 
10.degree. C. to less than -10.degree. C. Similarly, the stability is 
generally extended in duration at any given temperature when an 
appreciable amount of a reaction retardant, such as a volatile (C.sub.3 to 
C.sub.10)ketone or aldehyde, e.g. acetone or butyraldehyde, is added. The 
composition is also diluted in effect by the addition of various materials 
needed to provide modifications of luster, color, and the like, such as 
fillers and pigments. 
The volatile stabilizer that retards the reaction may be used in various 
amounts of about 0.5 to 80% by weight, based on the total weight of the 
two reactive components (A) and (B). However, the stabilizer may also 
serve as a part, or in some instances, as the entire solvent medium for 
the coating compositions. Thus, acetone, cyclohexanone, methyl ethyl 
ketone, methyl butyl ketone, diethyl ketone, meethyl hexyl ketone, 
benzaldehyde, or isobutyraldehyde, may be used in low quantities or 
proportions of about 0.5 to 3% by weight or even in larger quantities to 
serve as a component of the vehicle or as the entire solvent component of 
the vehicle. 
Using the methods of formulating given above, the compositions of the 
present invention may be applied to form clear, protective, and decorative 
coating and/or impregnate films. However, they may also contain various 
additives other than those which react to form the cross-linked binder, 
body, or matrix of the film. Such additives may be plasticizers, such as 
dioctyl phthalate, pigments and inorganic fillers, such as glass, titanium 
dioxide, silica, barite, and calcium carbonate, coloring matter, such as 
dyestuffs, anticorrosive agents, and water-proofing or water-repellents, 
such as paraffin waxes. 
The compositions may be formulated by mixing component (A) with component 
(B) and suitable solvents, dispersing agents, fillers, pigments and the 
like and storing the composition, if necessary, at low temperature, such 
as from about -10.degree. C. to +10.degree. C. until it is used at ambient 
temperatures. If however, it is not to be used within a period of one to 
three days, it is more practical to make up the composition as a 
two-package system, one package containing component (A) and the other 
component (B). Suitable solvents may be present in either or both 
packages. Pigments, fillers, and the like may be included in one or the 
other of the packages or even part in one, and part in the other. 
After mixing the two packages in proper proportions, the resulting 
composition may be used for coating numerous substrates, such as those of 
metals, wood, glass, and plastics to produce thereon upon ambient curing, 
with or without acceleration thereof by heating, protective and/or 
decorative coating films. The films have an outstanding combination of 
properties, chemical resistance, rust-resistance, durability to 
weathering, i.e. exposure to UV light, rain, etc., and hardness, 
toughness, flexibility, and other mechanical properties, including 
lubricity, frictional effects, etc. Also, the factors of low cost and 
toxicity involved in manufacture and use taken in conjunction with the 
properties obtainable on cure provide a versatility obtainable from the 
compositions of the present invention such that in many instances they may 
beneficially be used in place of other ambient curing systems heretofore 
used. The compositions may also be used as binders for fibrous webs to 
form bonded non-woven fabrics by impregnation of the webs and curing. 
Since the compositions of the present invention do not depend on 
air-curing, they are quite useful as adhesives to join sheets or panels of 
various materials, e.g. glass, metals, wood and plastics, such as those of 
polyester (Mylar.RTM.), poly(methyl methacrylate), (Plexiglas.RTM.), 
cellophane, and the like. 
The following examples are illustrative of the invention, the parts and 
percentages are by weight and the temperatures in degrees Celcius, unless 
otherwise specified. Test methods and preparation steps are as follows, 
unless specified otherwise in the given example: 
Preparation and Testing: 
Sand Grind 
The components of the sand grind are 
200 g TiO.sub.2 (pigment) 
50 g Resin (methacrolein polymer at 54.4% solids) 
100 g Solvent (xylene) 
350 g Sand 
This mixture is ground with a 3" impeller in a drill press at 2400 RPM for 
20 minutes. To remove the sand the mixture is filtered through a paint 
laboratory fine filter cone. The grind is let down with resin, solvent, 
and amine crosslinker to yield a 40% solids mixture at a 30/70 pigment to 
binder ratio on a weight basis. 
Film Preparation 
The paint, prepared as above, is cast on 24 gauge Bonderite.RTM. 40 panels 
by means of a 7 mil opening drawdown U-caster; dry film thickness is 
1.5.+-.0.1/mils. Paints are air dried for 7 days at room temperature or at 
140.degree. F. 
Pot-Life or Gel time 
Pot life is the time, after mixing the methacrolein polymer and amine 
crosslinker, required for the system to gel as determined by periodic 
manual stirring of the mixture with a stirring rod. 
Hardness 
Film hardness is determined on a Tukon Hardness Tester and is reported as 
Knoop Hardness Number (KHN). 
Print Resistance 
Pieces of painted Bonderite panels are covered with 2" square cheesecloth 
squares, a leather disc is placed, smooth side down, on the cheesecloth 
and appropriate weights placed on the leather disc to product a 2 lbs. per 
square inch load on the cheesecloth. This sandwich is placed in a 
preheated 82.degree. C. oven for 2 hours. The print rating is determined 
by the amount of indentation left by the cheesecloth in the paint as 
compared to a standard. 
Set Time 
Set time is the time from casting the film until the film is cured enough 
so that gently brushing the surface with a paper tissue produces no 
observable drag on the tissue. 
Yellowing 
Yellowing is determined by means of a Hunterlab Colorimeter Model 
D25A-4utilizing the Yellowness Index procedure ASTM D 1925. 
Mandrel Blend 
The Mandrel Bend Test determines the flexibility of a coating. Samples of 
the coated metal are bent over a series of mandrels, 1/8", 1/4" and 1/2" 
in diameter, by hand so as to form a U shaped cross section. The film is 
observed for cracking both by visual observation and through a 30 
magnification power microscope. No signs of cracks in the film is rated 
zero and the scale increases with the severity of cracking to a rating of 
10 for a severely cracked film exhibiting complete delamination from the 
substrate. 
QCT Test 
In a closed Cleveland Condensing Cabinet panels are supported at a 
45.degree. angle, coated face down, above water in a trough or open 
reservoir. The water is at 60.degree. C. or other temperature if so 
specified. Water evaporates from the trough, condenses on the panel and 
drips back into the trough. This test simulates hot, humid environmental 
exposure. Coatings are inspected for whitening and blistering.

EXAMPLE 1 
Preparation of Butyl Acrylate/Methyl Methacrylate/Styrene/Methacrolein 
Copolymer 
Into a reactor equipped with a stirrer, condenser, nitrogen inlet, addition 
funnels and a thermometer there is charged 135 grams of 2-butoxyethanol. 
The reactor is then flushed with nitrogen and after the solvent is heated 
to about 105.degree. C., a monomer mixture consisting of 50 grams or butyl 
acrylate, 275 grams of methyl methacrylate, 100 grams of styrene and 27.7 
grams of t-butyl peroctoate (50%) is fed into the reactor over a period of 
2 hours. Starting at the same time, over a period of 2.25 hours there is 
fed a second monomer mixture of 25 grams of 2-butoxyethanol and 75 grams 
of methacrolein while the temperature of the reactor mixture is maintained 
at about 105.degree. C. Immediately after the completion of the feeding of 
the first monomer mixture, a mixture of 10 grams of 2-butoxyethanol and 
2.3 grams of t-butyl peroctoate (50%) is fed into the reactor over a 
period of 0.25 hours so that the feed is completed at the same time as 
that of the second monomer mixture. The temperature of the reaction 
mixture is then held at a temperature of about 105.degree. C. for a period 
of 0.5 hours. Then, another mixture consisting of 10 grams of 
2-butoxyethanol and 4.8 grams of t-butyl peroctoate is fed over a period 
of 0.25 hours. After this, the reaction mixture is held at about 
105.degree. C. for 1 hour, cooled and the product filtered through a 20 
micron cartridge filter. The resulting copolymer is at 72% solids, 
represents 94% conversion and the available aldehyde is 63% of charged 
aldehyde. The weight average molecular weight (Mw) is about 17,000. 
The resulting copolymer consists of (weight percent) 10% butyl acrylate, 
55% methyl methacrylate, 20% styrene and 15% methacrolein (as charged). 
The polymer solution is diluted to 55% solids with 220 g 2-butoxy ethanol. 
EXAMPLE 2 
Preparation of Other Methacrolein Copolymers 
Following the procedure of Example 1, above, a variety of methacrolein 
copolymers are prepared. In addition to methacrolein (MAC), the monomers 
used include methyl methacrylate (MMA), butyl acrylate (BA), styrene (S), 
butyl methacrylate (BMA) and methacrylic acid (MAA). 
In Table I, below, there is provided copolymer composition, polymerization 
solvent, percent conversion of monomers, percent of available aldehyde and 
polymerization temperature. 
TABLE I 
__________________________________________________________________________ 
Composition* (wt. %) % Avail. 
P'lym'n 
Copolymer 
MMA BA BMA St 
MAC MAA Solvent 
Conv. 
Ald.% 
T.degree.C. 
__________________________________________________________________________ 
2a 0 0 63 20 
15 2 B.C..sup.1 
95 52 105 
2b 30 40 0 0 
20 10 B.C. 98 51 105 
2c 0 15 50 20 
15 0 B.C. 97 64 105 
2d 0 15 60 20 
5 0 B.C. 97 84 105 
2e 65 0 0 20 
15 0 iProH.sup.2 /B.C. 
95 76 105 
2f 20 0 45 20 
15 0 B.C. 97 62 105 
2g 0 0 63 20 
15 2 B.C. 95 56 105 
2h 0 0 63 20 
15 2 B.C. 96 69 75 
2i 0 0 63 20 
15 2 B.C. 96 68 75 
__________________________________________________________________________ 
*As charged on a monomer basis. 
.sup.1 B.C. is 2butoxyethanol 
.sup.2 iProH is isopropanol; used in the ratio 19 iProH/81 B.C. in 
preparing 2e 
EXAMPLE 3 
Methacrolein-Containing Polymer Crosslinked By Amines 
For the purpose of evaluating clear films of methacrolein-containing 
polymers crosslinked by amines, a methacrolein (MAC) copolymer is 
crosslinked with four different amines. The components are mixed as in the 
preparation of a sand grind given above but the TiO.sub.2 pigment and the 
sand are omitted so the mixture is 28% solids. The film is prepared in the 
same way as the pigmented film. Some film samples are cured at ambient 
temperatures and others at 82.degree. F. for a period of 30 minutes. The 
polymers and amines are blended at (available) stoichiometric amounts and 
the ratio of amine function to available aldehyde function is about 
1.0:1.0 for each of the polymer/amine blends. The methacrolein 
(MAC)-containing polymer used in the tests is: 
Polymer-P-6--24.7% BA/32.4% MMA/19% S/23.9% MAC made by the procedure of 
Example 1; available aldehyde is 64% of charged aldehyde, Mw is about 
33,000. 
The amine crosslinking agents included: 
(MDA)--1,8-methane diamine; 
(BACHM)--bis-(4-aminocyclohexyl) methane; 
(DIBKHMDA)--bis-(diisobutyl ketimine) of hexamethylene diamine; and 
(HMDA)--hexamethylene diamine. 
In Table II, below, the curing conditions and properties of the cured 
methacrolein-containing copolymers in clear films are summarized. In the 
results listed, the hardness is measured on a Tukon Hardness Indenter, and 
the print resistance, of the film containing the cured copolymers, is 
determined at a pressure of 2 psi. over a 2 hour period at about 
82.degree. C. For comparison, polymer P6 without crosslinker has an 
immeasurably long pot life and a film shows a very heavy print after seven 
days air dry. 
Example 3e uses acrolein (AC)-containing Polymer P5 --26% BA/34% MMA/20% 
S/20% AC, made by a procedure similar to that of Example 1. The pot life 
of the blend with MDA is seen to be much shorter than the methacrolein 
polymer blend despite the lower blend solids of the acrolein polymer 
blend. For coatings a longer pot life is required for the usual methods of 
application. Blended with the other amines the acrolein polymer has a 
still shorter pot life and thus even less feasible for use in these 
coatings. Under stringent conditions, a 30 minute bake at 150.degree. C., 
the print resistance of the acrolein polymer based coating is considerably 
degraded whereas no comparable degradation occurs in the corresponding 
methacrolein polymer based coating. The hardness developed in 7 days by 
the acrolein polymer blend (3e) is considerably less than that of the 
comparable methacrolein polymer blend (3a). The large difference in 
hardness, over 50% for each cure condition, is surprising. Hardness is, of 
course, a very important property of these coatings. 
TABLE II 
__________________________________________________________________________ 
Clear Film Properties of Methacrolein-Containing Polymers Crosslinked 
With Amines 
Polymer Blend 
Pot Cure Hardness 
Print 
Example 
Blend Solids 
Life Schedule 
1 Day 
7 Days 
7 Days 
__________________________________________________________________________ 
3a (P6)/MDA 
51 2 hr 18 min 
Ambient 3.5 17.2 
mod. 
180.degree. F./30 min 
12.7 
20.2 
light 
3b (P6)/ 49 18 min 
Ambient 9.2 17.9 
light 
BACHM 180.degree. F./30 min 
11.5 
18.3 
light 
3c (P6)/ 50 4 min 
Ambient 3.7 16.5 
light 
HMDA 180.degree. F./30 min 
9.6 19.3 
light 
3d (P6)/ 54 1 hr 12 min 
Ambient 5.1 16.1 
V. light 
DIBKHMDA 180.degree. F./30 min 
10.5 
19.5 
V. light 
3e (P5)/MDA 
40 14 min 
Ambient 7.2 11.4 
light 
180.degree. F./30 min 
12.3 
12.7 
light 
__________________________________________________________________________ 
EXAMPLE 4 
Methacrolein Polymers Crosslinked by a Trifunctional Primary Amine 
The methacrolein copolymer of Example 1 is crosslinked by a trifunctional 
primary amine, Jeffamine .RTM.T-403 (Jefferson Chemical Company) having 
the structure 
##STR10## 
wherein x+y+z=5.3. 
Properties of the formulation and the films formed are in Table III. The 
column headed equivalent ratio is the ratio of available methacrolein 
units in the blend to primary amine units in the blend. The examples with 
1/0 ratios are amine-free controls. The pigmented films are prepared as 
follows: 
Sand Grind: 
100 g rutile TiO.sub.2 (R-960.RTM., DuPont) 
100 g 15% Methacrolein copolymer at 54.4% in 2 butoxyethanol 
50 g Xylene 
200 g Sand 
Enamel: 
25 g of above grind filtered 
24.4 g of MAC copolymers (54.4%) 
4.7 g of Jeffamine T403 
Blend on a high speed mixer for approximately 5 minutes before casting. The 
blend constants are: pigment to binder ratio 30/70, methacrolein 
copolymers/amine ratio 80/20 (75% of stochiometry based on charged 
methacrolein), 62% solids. 
TABLE III 
__________________________________________________________________________ 
Clear and Pigmented Film Properties of Methacrolein Polymer/Amine 
Coatings 
Clear 
or Pig- 
Equiv. 
Blend 
Pot Set Cure Hardness 
Print 
mented 
Ratio 
Solids 
Life 
Time 
Schedule 
1 Day 
7 Days 
7 Days 
__________________________________________________________________________ 
Clear 1/0.6 
45 1.5 hrs. 
1.25 hrs. 
Ambient 4.8 8.7 V. light 
180.degree. F./30 min 
9.4 9.8 V. light 
Clear 1/0.75 
45 2.25 
1.25 
Ambient 3.9 8.8 light 
180.degree. F./30 min 
8.7 10.5 
V. light 
Clear 1/0.9 
45 3.0 1.5 Ambient 1.5 6.4 V. light 
180.degree. F./30 min 
7.8 13.1 
V. light 
Clear 1/1 45 3.0 1.5 Ambient 1.8 7.1 V. light 
180.degree. F./30 min 
6.4 13.8 
light 
Clear 1/0 45 (no cure found) 
Ambient 1.9 5.4 V. heavy 
180.degree. F./30 min 
6.6 9.5 V. heavy 
Pigmented 
1/0.6 
45 1.5 1.0 Ambient 3.4 9.2 light 
180.degree. F./30 min 
12.5 
14.4 
V. light 
Pigmented 
1/0.75 
45 1.5 1.0 Ambient 2.5 9.1 light 
180.degree. F./30 min 
10.4 
12.7 
V. light 
Pigmented 
1/0 45 (no cure found) 
Ambient 9.2 -- V. heavy 
180.degree. F./30 min 
13.1 
-- V. heavy 
__________________________________________________________________________ 
EXAMPLE 5 
Yellowing of Amine Crosslinked Copolymers 
Methacrolein and acrolein copolymers are intercompared for stability to 
aging by observing the discoloration of samples heated at 140.degree. F. 
for seven days, using the ASTM D 1925 determination. 
The results in table IV show that discoloration develops far more slowly in 
the methacrolein copolymer than in that made from acrolein. Both the 
discoloration and the degradation of print resistance noted above may be 
due to the poor resistance to oxidation of acrylamide units in the 
polymer. 
TABLE IV 
______________________________________ 
Yellowing Comparison of Methacrolein (P4) vs. Acrolein 
(P5) Copolymers at 60.degree. C./7 Days on Bonderite 1000 
Sample K-initial K-final 
______________________________________ 
P4/JT-403 7.8 8.1 
P4 alone 7.4 7.9 
P4/MDA 8.0 10.1 
P5/MDA 25.2 80.9 
P5 alone 12.4 14.8 
P5/JT-403 20.0 70.6 
______________________________________ 
Polymer P4 30% BA/35% MMA/30% S/15% MAC is prepared by following the 
general procedure of Example 1 except that xylene is used as the solvent. 
EXAMPLE 6 
Room Temperature Versus Elevated Temperature Curing 
Room temperature and elevated temperature cures are compared. The elevated 
temperature cure, 140.degree. F. for seven days, represents an 
approximation of the ultimate cure condition of the films. The polymers 
used are Polymer P2--10% BA/55% MMA/20% S/15% MAC and Polymer P3--20% 
BA/40% MMA/20% S/15% MAC//5% acrylonitrile. The method of Example 1 is 
used in the preparation of these polymers except for a change in the 
solvent system to a 1:1 ratio of 2-butoxyethanol and 2-ethoxyethyl acetate 
at 54.4% solids. The amines used are Jeffamine T 403 (JT 403) described in 
Example 4, and MIBKHMDA, the bis(diisobutyl ketimine) of hexamethylene 
diamine. 
The data obtained are in Table V. Results of the QCT. test show the good 
water resistance of these films, no rusting, no whitening and no 
blistering at all being found in some of the coatings. 
TABLE V 
__________________________________________________________________________ 
Clear Films: Room Temperature vs. 60.degree. C. Cures 
Polymer Equiv. Mandrel Bend 
Blend Ratio 
Cure Hardness 
Print 
1/8" 
1/4" 
1/2" 
QCT 
__________________________________________________________________________ 
P2/JT403 1/0.75 
RT-1 day 
2.0 light to 
-- -- -- -- 
moderate 
RT-7 days 
9.3 light 
0 0 0 d # 8 
60.degree. C. 7 days 
14.5 v. light 
10 10 10 pass 
P3/JT403 1/0.75 
RT-1 day 
1.1 light 
-- -- -- -- 
RT-7 days 
8.6 v. light 
0 0 0 d # 8 
60.degree. C. 7 days 
12.0 trace 
0 0 0 pass 
P3/MIBKHMDA 
1/0.75 
RT-1 day 
2.0 light 
-- -- -- -- 
RT-7 days 
8.2 light 
0 0 0 whitening 
d # 8 
60.degree. C. 7 days 
18.1 light 
0 0 0 tr. 
whitening 
__________________________________________________________________________ 
Notes: 
Films were cast on Bonderite 40 (TM Parker Test Panels, Oxy Metal Ind. 
Corp. Parker Div., Detroit, Mich. 48220). 
Film thickness is 1.5 mils 
Mandrel bend 0 = no cracks in film, 10 = severe cracks and delamination o 
film. 
QCT test d # 8 dense blisters, about 8 per 2.5 cm. square. 
EXAMPLE 7 
Homopolymer of Methacrolein 
A methacrolein homopolymer is prepared as follows: 
To a reactor, equipped with a mechanical stirrer, a condensor and a 
thermometer, is added two hundred parts of distilled water, fifty parts of 
ethanol and thirty-three parts of methacrolein. These are mixed at 
20.degree. C. and there is added twenty parts of 0.50 N sodium hydroxide. 
After ca. five minutes the system is permitted to warm to a maximum 
temperature of 35.degree. C. under control by an ice water bath. When the 
evolution of heat subsides the reaction is complete. The product is 
transferred to a separating funnel and extracted two times with two 
hundred parts of diethyl ether each time. Finally the product is stripped 
on a rotary evaporator to yield concentrated oligomeric methacrolein. 
The product is a viscous, yellow liquid. Gel permeation chromatography 
indicates a Mw of 400-800. 
The above polymer is crosslinked by formulation with Jeffamine T403 amine 
at a ratio of one available aldehyde to 0.75 amine group, pigmented and 
mixed as described above under "Sand Grind". The paint so made cured in 16 
hours to a tough coating. The high solids of this system is particularly 
advantageous in locations where low solvent emissions are required.