A monomeric alkoxymethylated aminoplast crosslinking agent derived from a m-TMI/melamine 1:1 adduct and a process for its preparation is provided. The process comprises contacting melamine with M-TMI, contacting the adduct formed with formaldehyde, and contacting the hydroxymethylated adduct with an alcohol such as butanol. A curable composition comprising the monomeric aminoplast crosslinker and a polyfunctional active hydrogen-containing material is also provided. An improved method of coating using the curable composition to produce cured films or objects is also provided.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to the preparation and use of a novel class of 
substantially monomeric aminoplasts as crosslinking agents. The 
crosslinkers are prepared from 2,4,6-triamino-1,3,5-triazine, hereinafter 
"melamine", and isopropenyl-alpha, alpha-dimethylbenzyl isocyanate, 
hereinafter "TMI", by a monoaddition reaction followed by methylolation 
and etherification. 
2. Description of the Related Art 
To effectively crosslink with a variety of widely available difunctional 
materials such as diols, dicarboxylic acids, dimercaptans, and diamides, a 
monomeric crosslinking agent is required to have a functionality effective 
for crosslinking of at least two. In many cases, however, even 
trifunctional aminoplast crosslinking agents do not give rise to 
sufficient crosslinking density in cured films or objects due to 
incomplete reaction of the functional groups, and as a result, cured films 
with inferior physical and resistance properties are obtained. 
The problem of insufficient crosslinking density may be overcome by using a 
higher functional aminoplast crosslinker such as hexamethoxymethyl 
melamine. In these cases, however, the films obtained sometimes have low 
flexibility due to the somewhat rigid network produced in the films upon 
cure. 
The above-identified problems of insufficient crosslinking of the low 
functionality crosslinkers and the low flexibility of the highly 
functional crosslinkers are both overcome by using typically 
tetrafunctional guanamine-derived aminoplast crosslinking agents. However, 
guanamine-derived crosslinkers are more difficult and more costly to 
prepare than melamine-derived crosslinkers. Furthermore, some guanamine 
crosslinkers such as N,N,N',N'-tetraalkoxymethylbenzoguanamines have 
insufficient resistance properties and have inferior stability towards the 
degradative action of ultraviolet light. 
It is the object of this invention to obtain melamine-derived, 
substantially monomeric aminoplast crosslinking agents having olefinic 
functionality which are capable of producing, upon cure, films which have 
good acid resistance properties, environmental etch resistance, and a good 
balance of hardness and flexibility. 
SUMMARY OF THE INVENTION 
This invention relates to a novel, highly functional substantially 
monomeric aminoplast crosslinking agent and an intermediate used in the 
production thereof. 
This invention also relates to a process for preparing said crosslinking 
agent. 
This invention also relates to a curable composition containing said highly 
functional substantially monomeric aminoplast crosslinking agent. 
This invention also relates to an improved method of coating using the 
curable composition of the invention. 
Finally, this invention relates to a cured film or object prepared by the 
improved method of the invention.

DETAILED DESCRIPTION 
This invention relates to meta-, para-, or a mixture of meta- and 
para-isopropenyl-alpha, alpha-dimethylbenzyl isocyanate adducts 
represented by the formula: 
##STR1## 
wherein each of R.sup.1, R.sup.2, R.sup.3, and R.sup.4 is independently 
selected from the group consisting of hydrogen, hydroxymethyl, an 
alkoxymethyl, an aminoplast-containing group derived from condensation 
thereof, and mixtures of any of the preceding groups. 
The preferred isomer of the aminoplast is the metaisomer having at least 
one of the R.sup.1, R.sup.2, R.sup.3, and R.sup.4 groups selected 
independently from the group consisting of hydroxymethyl, alkoxymethyl of 
1 to 6 carbon atoms, and mixtures thereof. 
The most preferred aminoplasts are compositions of matter represented by 
the formula: 
##STR2## 
wherein each of R.sup.5, R.sup.6, R.sup.7, and R.sup.8 is independently 
selected from the group consisting of hydrogen, methyl, ethyl, 1-propyl, 
2-propyl, 1-butyl, 2-butyl, iso-butyl, 1-pentyl, 1-hexyl and cyclohexyl 
groups, and mixtures thereof. 
An example of the aminoplasts containing mixed alkoxy crosslinkably 
reactive groups is the particularly preferred composition of matter 
represented by the formula: 
##STR3## 
wherein the ratio of normal butyl to methyl groups is 3:1. 
Preparation Of The Crosslinkers 
The novel, substantially monomeric aminoplast crosslinking agents of the 
invention are prepared by a process in which a 1:1 adduct of melamine with 
an isocyanate is chemically modified to contain hydroxymethyl, 
alkoxymethyl or both groups. The isocyanate which forms the adduct is 
meta-isopropenyl alpha, alpha-dimethylbenzyl isocyanate (hereinafter 
m-TMI), available as TMI.RTM. (meta) Unsaturated Aliphatic Isocyanate, a 
product of American Cyanamid Company, Wayne, N.J., or 
para-isopropenyl-alpha, alpha-dimethyl-benzyl isocyanate (hereinafter 
p-TMI), or a mixture of the meta- and para- isomers. The para-isomer may 
be prepared by procedures described in U.S. Pat. Nos. 3,290,350; 
4,130,577; 4,377,530; or 4,439,616. 
The reaction steps for preparing the novel tetrafunctional crosslinkers are 
illustrated below for the meta-isomer: 
##STR4## 
The novel process for preparing the aminoplast of the invention comprises: 
(a) contacting melamine with isopropenyl-alpha, alpha-dimethylbenzyl 
isocyanate in a solvent characterized by a high dielectric constant, at a 
temperature and for a length of time sufficient to produce a 1:1 adduct, 
(b) contacting said 1:1 adduct of step (a) with 2 to 20 moles of 
formaldehyde per mole of adduct to produce a hydroxymethylated adduct, and 
(c) contacting said hydroxymethylated adduct of step (b) with 2 to 30 moles 
of an alcohol per mole of hydroxy-methylated adduct at an acidic pH to 
produce an alkoxymethylated aminoplast. 
In step (a), the monoadduct of TMI and melamine is prepared using a 1:1 
molar ratio of TMI to melamine, normally preferred on the basis of 
reaction stoicheometry. However, the adduct-forming reaction may be 
carried out at any ratio. For example, if a TMI to melamine molar ratio of 
0.5:1 is used, there will remain a large excess of unreacted melamine 
which may be separated from the product, which product is necessarily a 
1:1 adduct. If, on the other hand, excess quantities of TMI such as a 5:1 
molar excess are used, only the monoaddition product is obtained under the 
process conditions of this invention. The unreacted TMI in this case may 
be easily removed by precipitation of the product. 
The preferred solvents in step (a) are aprotic solvents having relatively 
high boiling points, high dipole moments and high dielectric constants for 
facilitating the dissolution of the sparingly soluble melamine at the 
reaction temperature and for allowing the product to crystallize at 
ambient temperatures. The preferred solvent is dimethylsulfoxide, however, 
aprotic solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, 
N-methyl pyrrolidone, sulfolane, hexamethylphosphorus triamide (HMPT), 
hexamethylphosphoramide (HMPA), and mixtures thereof may also be used. 
Any solvent to reactant ratio may be used to carry out step (a) of the 
process of the invention. The preferred range of the solvent to reactant 
ratio is from about 0.33:1 to about 10:1. Most preferably, the ratio is 
2:1. 
The preferred temperature for carrying out the monoaddition reaction of 
step (a) is in the range of from about 80.degree. C. to about 150.degree. 
C. At temperatures lower than 80.degree. C., the reaction proceeds at a 
very slow rate. At temperatures higher than 150.degree. C., side 
reactions, including decomposition of the solvent and TMI reactant, may 
become significant. A temperature in the range of 100.degree. C. to 
120.degree. C. is most convenient to prepare the 1:1 adduct. 
The preferred time for carrying out the monoaddition reaction of step (a) 
is in the range of from about 12 minutes to about 28 hours. 
After the monoaddition reaction of step (a), the 1:1 adduct is isolated by 
cooling the reaction mixture and filtering the precipitated product. The 
product may be further purified by washing with an organic solvent capable 
of dissolving the solvent used in the process of the invention. An example 
of a solvent usable for this purpose is tetrahydrofuran. 
In step (b) of the process, the adduct is hydroxymethylated (or 
methylolated) with 1 to 20 moles of formaldehyde per mole of the adduct, 
typically in water or an alcohol, or in a mixture of water and an alcohol 
such as normal butanol (n-butanol). 
In step (c), the hydroxy groups in the methylolated 1:1 adduct are 
etherified with an alcohol under acidic conditions, typically at a pH 
range from 0.5 to 6.0, and preferably from about 2 to 4. The alcohol used 
to etherify the methylolated 1:1 adduct is usually used in a large excess 
to ensure a high degree of etherification and to prevent self-crosslinking 
of the product. Therefore, the alcohol used for etherification typically 
is the reaction solvent. 
When mixed alkoxymethylated aminoplasts are desirable, a mixture of 
alcohols may be used both as reactant and as solvent. 
Curable Composition 
The novel aminoplasts of the invention may be used as crosslinking agents 
in curable compositions to produce, upon curing, crosslinked films or 
objects useful in coatings, adhesives, conventional moldings, reactive 
injection moldings, composites, laminates, binders, and others. 
The curable composition comprises: 
(i) an aminoplast crosslinking agent represented by the formula: 
##STR5## 
wherein the point of attachment of the isopropenyl group is meta-, or 
para-, or a mixture thereof, and wherein each of R.sup.1, R.sup.2, 
R.sup.3, and R.sup.4 is independently selected from the group consisting 
of hydrogen, hydroxymethyl, an alkoxymethyl of 1 to 6 carbon atoms, an 
aminoplast-containing group derived from condensation thereof, and 
mixtures of any of the preceding groups with the proviso that at least one 
of the R.sup.1, R.sup.2, R.sup.3, and R.sup.3 groups are independently 
selected from the group consisting of hydroxymethyl, an alkoxymethyl of 1 
to 6 carbon atoms, and mixtures thereof; and 
(ii) a polyfunctional active hydrogen-containing material. 
Aminoplast Crosslinking Agents 
The aminoplast crosslinking agents usable in the curable compositions are 
the novel aminoplasts of the invention having at least two crosslinkably 
reactive functions at least one of which is selected from the group 
consisting of hydroxymethyl, alkoxymethyl, and a mixture thereof. 
Polyfunctional Materials 
The polyfunctional materials usable in the invention are polyfunctional 
active hydrogen-containing materials. 
Suitable polyfunctional materials may be polymercaptans, polycarboxylic 
acids, polyamides, epoxy or urethane prepolymers, alkyds, and polyols such 
as acrylic resins containing pendant or terminal hydroxyl functionalities, 
polyester resins with pendant or terminal hydroxyl functionalities and 
polyhydric alcohols. These are described in greater detail below. 
The polyfunctional materials and resins used in the compositions of the 
invention preferably have a molecular weight of from about 60 to about 
50,000 and comprise at least one class of an active hydrogen functionality 
selected from the group consisting of hydroxy, carboxy, amido, mercapto, 
and a group convertible thereto. 
The hydroxyfunctional polyfunctional materials used in formulating the 
curable compositions of this invention preferably are resins that have 
molecular weights in the range of from about 500 to about 50,000, and 
hydroxyl group equivalent weights of from about 200 to about 4,000. 
An example of a suitable polyfunctional polyester resin usable in the 
curable compositions of this invention is OXYESTER.RTM. Z 1439 Branched 
Polyester Resin, a product of Chemische Werke Huls AG, Germany having the 
following physical and chemical properties: 
______________________________________ 
Hydroxyl Content (% by weight) 
2 
Hydroxyl Number 65 
Equivalent Weight 863 
Solids Content (% by weight) 
50 
______________________________________ 
Another example of a suitable polyfunctional polyester resin particularly 
suited for use in coil coatings is CYPLEX.RTM. 1531 modified Polyester 
Resin, a product of American Cyanamid Company, Wayne, N.J., having the 
following physical and chemical properties: 
______________________________________ 
Solids 
(Weight %) 60 
(Volume %) 52.9 
Color (Gardner 1963) 6 (max.) 
Viscosity (Gardner-Holt, 25.degree. C.) 
Y-Z.sub.2 
Hydroxyl Number (solids) 30 
Equivalent Weight (solids) 
1,870 
Molecular Weight, approximate 
4,000 
Acid number (solids) 10 (max.) 
Solvesso 150 Aromatic Hydrocarbon 
40 
Solvent (%) (a product of 
Humble Oil and Refining Company) 
______________________________________ 
Another example of a suitable polyfunctional resin for coil coating is 
CYPLEX.RTM. 1538 Modified Polyester Resin, a product of American Cyanamid 
Company, Wayne, N.J., having the following properties: 
______________________________________ 
Solids 
(Weight %) 65 
(Volume) 58 
Color (Gardner 1963) 6 (max.) 
Viscosity (Gardner-Holt, 25.degree. C.) 
Z.sub.1 -Z.sub.3 
Hydroxyl Number (Solids) 40 
Equivalent Weight (Solids) 
1400 
Molecular Weight, approximate 
2800 
Acid Number (Solids) 10 (max.) 
Solvesso 150 Aromatic 35 
Hydrocarbon Solvent (%) 
______________________________________ 
Another example of a suitable polyfunctional resin particularly suited to 
coil coatings is CYPLEX.RTM. 1546 Oil-Free Polyester Resin, a product of 
American Cyanamid Company, Wayne, N.J., having the following properties: 
______________________________________ 
Non-Volatiles (Weight %) 
70 .+-. 2 
Color (Gardner 1963, max.) 
4 
Viscosity (Gardner-Holt, 25.degree. C.) 
Z.sub.1 -Z.sub.3 
Acid Number (resin solids, max) 
10 
Hydroxyl Number (resin solids) 
35-40 
Equivalent weight 1,400-1,600 
______________________________________ 
An example of a suitable acrylic resin for non-coil coating applications is 
JONCRYL.RTM. 500 Acrylic Resin, a product of S.C. Johnson and Son, Inc., 
Racine, Wis., having the following properties: 
______________________________________ 
Solids Content (Weight %) 80 
Viscosity at Room Temperature 
4,000 
(Centipoise) 
Hydroxyl Number 140 
(based on solids) 
Equivalent Weight 400 
(based on solids) 
Molecular Weight (Mn)* 1,300 
Polydispersity (Mw/Mn)** 1.7 
______________________________________ 
*Mn = Number Average Molecular Weight 
**Mw = Weight Average Molecular Weight 
ARAKOTE.RTM. 3109 Hydroxy-Terminated Polyester Resin, a product of 
Ciba-Geigy Corporation, Hawthorne, N.Y., is an example of a solid 
polyester resin particularly suitable to powder coating, and has the 
following physical and chemical properties: 
______________________________________ 
Hydroxyl Number 27-32 
Equivalent Weight 1,900 
Tg (Glass Transition, .degree.C.) 
66 
ICI Viscosity at 200.degree. C. (Poise) 
40 
Appearance Colorless 
Solid 
______________________________________ 
JONCRYL.RTM. SCX-800 A Acrylic Resin and JONCRYLO SCX-800 B Acrylic Resin, 
products of S.C. Johnson and Son, Inc., examples of solid acrylic resins, 
also are suitable for powder coatings, and have the following physical and 
chemical properties: 
______________________________________ 
SCX-800A 
SCX-800B 
______________________________________ 
Non-Volatiles (Weight %) 
98 97 
Hydroxyl Number 43 40 
Equivalent Weight 1300 1402 
Acid Value (mg KOH/g) 
15 15-20 
Tg (Glass Transition, .degree.C.) 
43 43 
Softening Point (.degree.C.) 
100 107 
ICI Viscosity at 200.degree. C.(Poise) 
25 45-50 
______________________________________ 
In addition to the examples cited above, a variety of commercial polyester 
resins may be used as the polyfunctional ingredient of the invention, 
provided such resins have suitable chemical and physical properties 
similar to those set forth above for ingredient (ii). 
Optionally, the curable compositions of the invention may further comprise 
a cure catalyst to accelerate the curing process at a given temperature or 
to reduce the cure temperature at a given cure time. 
The catalyst, if present, is typically an acid selected from the group 
consisting of sulfonic, carboxylic, phosphoric, sulfuric, and nitric 
acids. The preferred acid catalysts are sulfonic acids, including 
benzenesulfonic acid, para-toluenesulfonic acid, naphthalenesulfonic acid, 
dinonylnaphthalenesulfonic acid, dodecylbenzenesulfonic acid, 
methanesulfonic acid, and mixtures thereof. 
Other Ingredients 
The curable compositions of the invention may optionally contain a liquid 
medium, which liquid medium may be used to aid the uniform application and 
transport of the curable composition. Any or all of the ingredients of the 
composition may be contacted with the liquid medium. Moreover, the liquid 
medium may permit formation of a dispersion, suspension, emulsion, invert 
emulsion, or solution of the curable composition ingredients, including 
other optional ingredients. 
Particularly preferred is a liquid medium which is a solvent or a diluent 
for the curable composition ingredients (i) and (ii). The preferred 
solvent or diluent is selected from the group consisting of water, 
alcohols, ketones, ethers, esters, aliphatic hydrocarbons, aromatic 
hydrocarbons, halogenated hydrocarbons, and mixtures thereof. 
Other optional ingredients include fillers, pigments, flow control agents, 
anticratering additives, antioxidants, stabilizing alcohols, ultraviolet 
light stabilizers, plasticizers, pigment wetting additives, levelling 
additives, mar-proofers, mold release agents, and corrosion inhibitors. 
Ratio Of The Ingredients 
The weight ratio of the crosslinker (i) to polyfunctional material (ii) is 
from about 3:1 to about 1:40 and preferably 1:1 to 1:5. The weight percent 
of the crosslinker (i) in the curable composition is from about 2.5 to 
about 75. 
The weight ratio of the catalyst, when present, to the crosslinker (i) in 
the curable composition is from about 1:4 to about 1:1,000 and the weight 
percent of catalyst in the curable composition is from about 0.01 to about 
5. 
The weight percent of the optional liquid medium ranges from zero to about 
80 and the weight ratio of the liquid medium to the total weight of the 
ingredients (i) and (ii) of the composition ranges from about 0.001 to 
about 4. 
Improved Method Of Coating 
The curable compositions may be used in the improved method of the 
invention to prepare coatings such as solution coatings, emulsion 
coatings, powder coatings, coil coatings, electrodeposition coatings, and 
the like. They may also be used as laminating resins, adhesives or molding 
compounds. 
This invention, therefore, is an improved method for coating of the type 
having the steps of (I) contacting a substrate with a curable composition 
containing a crosslinking agent and a polyfunctional active 
hydrogen-containing material, and (II) thereafter curing, wherein the 
improvement comprises: 
(A) contacting said substrate with a curable composition comprising: 
(i) an aminoplast crosslinking agent represented by the formula: 
##STR6## 
wherein the point of attachment of the isopropenyl group is meta- or 
para-, or a mixture thereof, and wherein each of R.sup.1, R.sup.2, 
R.sup.3, and R.sup.4 is independently selected from the group consisting 
of hydrogen, hydroxymethyl, an alkoxymethyl of 1 to 6 carbon atoms, an 
aminoplast-containing group derived from condensation thereof, and 
mixtures of any of the preceding groups, with the proviso that at least 
one of the R.sup.1, R.sup.2, R.sup.3, and R.sup.4 groups are independently 
selected from the group consisting of hydroxymethyl, alkoxymethyl of 1 to 
6 carbon atoms, and mixtures thereof, and 
(ii) a polyfunctional active hydrogen-containing material, and 
(B) thereafter heat-curing said curable composition. 
The curable compositions usable in the improved method are the novel 
curable compositions of the invention described hereinabove containing the 
novel aminoplast crosslinking agents of the invention having at least two 
crosslinkable reactive functions at least one of which is selected from 
the group consisting of hydroxymethyl, alkoxymethyl, and mixtures thereof. 
The curable composition may be applied onto a substrate by spraying, 
padding, brushing, roller-coating, curtaincoating, flowcoating, 
electrocoating, dipping, or electrostatic spraying. The applied curable 
composition is thereafter cured, typically, at a temperature in the range 
of from about 80.degree. C. to about 160.degree. C. within a period of, 
typically, 5 minutes to 1 hour to produce crosslinked films or objects. 
EXAMPLE 1 
PREATION OF M-TMI/MELAMINE 1:1 ADDUCT 
In a 2 liter three neck glass reactor equipped with agitator, thermometer, 
reflux condenser, nitrogen inlet and dropping funnel, 252 g (2 moles) of 
melamine was dispersed in 800 ml of DMSO (Dimethylsulfoxide) under 
vigorous agitation. A solution of 423 g (2.1 moles) of M-TMI in 200 ml 
DMSO was added to the slurry at 110.degree.-113.degree. C. in 3.5 hours. 
The reaction temperature was maintained for an additional hour. To 
maintain efficient agitation, the thickening slurry was diluted several 
times during the reaction with a total of 150 ml of DMSO. After cooling to 
ambient temperature, the reaction mixture was filtered, the white solid 
was rinsed on a filter with THF (tetrahydrofuran) and reslurried in 800 ml 
of THF. After agitation at 64.degree. C. for 80 minutes, the product was 
filtered, rinsed on the filter with THF and dried first in a hot air 
circulation oven at 60.degree. C. overnight (16 hours), then in a vacuum 
oven (full pump vacuum) at 90.degree.- 100.degree. C. for 4 hours. The 
yield of the white solid product was 665 g. From the first filtrate 85 g 
and from the second (wash) 73 g of white solids were recovered. Infrared 
(IR) and Thermal Gravimetric Analysis (TGA) indicated that these products 
still contained 15-20% of DMSO. 
The main product was characterized by NMR (Nuclear Magnetic Resonance), IR 
and thermal analysis. It is practically insoluble in most organic 
solvents, sparingly soluble in aprotic solvents such as DMSO, 
N-methyl-pyrrolidone, DMF (dimethylformamide), etc. Both carbon and proton 
NMR, as well as the IR spectra were consistent with a 1:1 adduct 
structure. TGA indicated about a 20% weight loss in the range of 
100.degree.-125.degree. C. (DMSO). Major weight loss is observed above 
245.degree. C. Major thermal event by DSC (differential scanning 
calorimetry) is an endotherm occurring in the temperature range in which 
the major weight loss is observed by TGA (extras. onset: 223.degree. C.). 
Liquidification is observed by TM (Thermal Microscopy) in the same range 
(onset 232.degree. C.) and "boiling" started at 248.degree. C. 
EXAMPLE 2 
PREATION OF MIXED ALKOXYMETHYLATED MONOMERIC AMINOPLAST CROSSLINKING 
AGENT 
A suitable reactor equipped with stirrer, reflux condenser and thermometer 
was charged with 120 g of butyl formcel. (Butyl formcel comprises 
formaldehyde (40%), normal butanol (53%), and water (7%) by weight.) and 
the pH adjusted with 20% caustic solution to 10.1. Then 80 g of the 
product of Example 1 was added and the temperature of the slurry raised to 
85.degree. C.; after eight minutes a clear solution was formed. The 
temperature was maintained at 85.degree.-90.degree. C. for an additional 
30 minutes, then 84 g of n-butanol was added. At 65.degree. C., the pH was 
adjusted to 2.5 by addition of 0.5 ml of 70% nitric acid and the 
temperature was maintained for 20 minutes. During the following 35 
minutes, 55 ml of distillate was removed at 65.degree.-68.degree. C. and 
200 Mm Hg (about 27 kilo Pascals). The distillate was replaced by adding 
portionwise to the reactor the same amount of n-butanol. The reaction 
mixture was cooled to 35.degree. C. and 1.25 ml 20% caustic was added to 
adjust the pH to 9.6. The volatiles were stripped to 96.degree. C./100 Mm 
Hg (about 13 kilo pascals) and 115 g of distillate was collected. At 
55.degree. C.P 96 g of methanol was charged followed by 0.5 ml of 70% 
nitric acid at 40.degree. C. (PH=2.1), and the temperature was maintained 
at 40.degree.-43.degree. C. for 40 minutes. After adjusting the pH to 9.5 
with 1.2 ml of 20% caustic solution, 112 g distillate was removed at 90 mm 
Hg (12 kilo pascals) up to 95.degree. C. The 120 g of the colorless, 
moderately viscous resin obtained was diluted with 17 g of toluene and 
filtered at 80.degree. C. under approximately 2,000 mm Hg pressure of 
nitrogen gas (about 276 kilo pascals), to give a clear, colorless resin, 
the novel crosslinking agent of the invention, having the following 
characteristics: 
______________________________________ 
HPSEC: 81.7% Monomer (High 
Performance 
Size Exclusion 
Chromatogra- 
phy Areas) 
14.8% Dimer (Areas) 
3.5% Trimer (Areas) 
NMR: CH.sub.3 /CH.sub.2 = 
0.22 (ratio) 
nBu/CH.sub.2 = 0.67 (ratio) 
CH.sub.2 /Adduct = 
3.3 (ratio) 
FREE CH.sub.2 O: 
0.55% (by weight) 
METHYLOL: 2.48% (by weight) 
SOLIDS: Pan = 89.2% (by weight) 
Foil = 95.2% (by weight) 
CH.sub.2 O/ADDUCT: 
3.12 (Based on bound 
formaldehyde and 
nitrogen analysis) 
______________________________________ 
EXAMPLE 3 
The procedure of Example 2 was repeated with the exception that methyl 
formcel (methyl formcel comprises formaldehyde (55%), methanol (35%) and 
water (10%) by weight) was used instead of butyl formcel, and the 
n-butanol was replaced with methanol. The product was a methoxymethylated 
analog of the product of Example 2. The methoxymethylated product is 
another example of the crosslinking agents of the invention and has the 
following characteristics: 
______________________________________ 
NMR: CH.sub.3 /CH.sub.2 = 
0.96 (ratio) 
CH.sub.2 O/Adduct = 
1.7 
FREE CH.sub.2 O = 0.97% (by weight) 
CH.sub.2 OH = 
1.93% (by weight) 
RESIDUAL DMSO = 3% (by weight) 
HPSEC: 73.3% Monomer (High 
Performance Size 
Exclusion Chroma- 
tography Areas) 
16.3% Dimer (Areas) 
2.9% Trimer (Areas) 
6.9% Higher Oligomers 
(Areas) 
FOIL SOLIDS: 84.5% (by weight, 
the balance being 
ethanol) 
SOLUBILITY: Soluble in xylene at 
70.degree. C. and in nor- 
mal butanol at 
60.degree. C. A precipitate 
forms from the 
n-butanol solution at 
room temperature 
on standing. 
______________________________________ 
EXAMPLE 4 
The crosslinking agents of Example 2 and Example 3 and JONCRYL.RTM. 500 
resin, a product of S. C. Johnson and Son, Inc., Racine, Wis., were cured. 
The physical properties of the cured films were compared with cured films 
obtained by using CYMEL.RTM. 303 and CYMEL.RTM. 1168 crosslinking agents, 
both products of American Cyanamid Company, Wayne, N.J. CYMEL.RTM. 303 
crosslinker is a substantially fully methoxymethylated melamine. 
CYMEL.RTM. 1168 crosslinker is a substantially fully mixed 
methoxymethylated and isobutoxymethylated melamine. The film properties 
are summarized in Table 1. The formulations were as follows: 
Weight ratio of JONCRYL.RTM. 500 Resin/CROSSLINKER: 65/35 
Weight percent of para-toluenesulfonic acid (on binder solids): 0.3 
Substrate: Electrocoated cold roll steel Film Thickness: 1.6-1.8 mils 
(0.041-0.046 mm) 
TABLE 1 
__________________________________________________________________________ 
FILM PROPERTIES OF COATINGS PREED FROM THE NOVEL 
AMINOPLAST CROSSLINKING AGENTS OF EXAMPLE 2 AND EXAMPLE 3 
WITH JONCRYL .RTM. 500 RESIN IN CLEAR COATS: 
A COMISON WITH CYMEL .RTM. 300 AND CYMEL .RTM. 1168 
CROSSLINKING AGENTS USED TO PREE THE CLEAR COAT 
CYMEL .RTM. 303 
CYMEL .RTM. 1168 
EXAMPLE 2 
EXAMPLE 3 
__________________________________________________________________________ 
121.degree. C./30 MIN. CURE 
TUKON HARDNESS 
10.1 7.4 9.6 10.9 
(ASTM D-1474-85) 
MEK DOUBLE RUBS 
TO MAR 200+ 200+ 200+ 10 
TO REMOVE 200+ 200+ 200+ 200* 
149.degree. C./30 MIN. CURE 
TUKON HARDNESS 
11.5 8.9 10.9 12.4 
(ASTM D-1474-85) 
MEK DOUBLE RUBS 
TO MAR 200+ 200+ 200+ 50 
TO REMOVE 200+ 200+ 200+ 200+ 
__________________________________________________________________________ 
*Film easily scratches off after 200 MEK double rubs. 
EXAMPLE 5 
The procedure of Example 4 was used to prepare four additional cured films 
(clear coats) with the exception that both cure catalyst concentration and 
the JONCRYL.RTM. 500 to crosslinker ratios were modified as shown in Table 
2. After curing, environmental etch and acid spot tests were carried out. 
In the acid spot tests, the cured films are contacted with an acid. After 
exposure to 38% sulfuric acid at room temperature overnight, no evidence 
of an acid spot could be detected on films prepared from JONCRYL.RTM. 500 
and the crosslinker of the invention (Example 2), whereas the film 
prepared using CYMEL.RTM. 1168 had a notable, but slight, haze. 
The results of the environmental etch test are summarized in Table 2. 
TABLE 2 
__________________________________________________________________________ 
RESISTANCE PROPERTIES OF THE NOVEL AMINOPLAST CROSSLINKING 
AGENTS OF EXAMPLE 2 WITH JONCRYL .RTM. 500 RESIN IN CLEAR COATS: 
A COMISON WITH CYMEL .RTM. 1168 CROSSLINKERS 
CURE CATALYST 
(para- 
JONCRYL*500/ 
Toluenesulfonic 
ATTACK RATING* 
CROSSLINKER 
Acid) H.sub.2 SO.sub.4 
HNO.sub.3 
H.sub.2 SO.sub.4 + HNO.sub.3 
CROSSLINKERS 
(RATIO) (WT. %) (50 ppm) 
(15 ppm) 
(20 + 20 ppm) 
__________________________________________________________________________ 
Example 2 65/35 0.3 5 3 3 
Example 2 50/50 0.3 5 1 2 
Example 2 50/50 1.0 5 0 1 
CYMEL*1168 
65/35 0.3 5 3 3 
__________________________________________________________________________ 
*Attach rating on a scale of 0 to 5. 
5 = Greatest Attack 
0 = No Visible Attack 
EXAMPLE 6 
The procedure of Example 2 is again followed except that 200.0 g of butyl 
formcel are employed such as to react all the NH sites of the metanine 
moiety. Coatings produced from the resultant aminoplast show excellent 
properties. 
Although the present invention has been described with reference to certain 
preferred embodiments, it is apparent that modifications and variations 
thereof may be made by those skilled in the art without departing from the 
scope of this invention as defined by the appended claims.