ISOCYANATE-FUNCTIONAL POLYMERS CONTAINING A TERMINAL THIOALKYL GROUP

POLYMERES A GROUPE FONCTIONNEL ISOCYANATE, CONTENANT UN GROUPEMENT THIOALKYL TERMINAL

English Abstract

ABSTRACT OF THE DISCLOSURE
Low molecular weight isocyanate-functional acrylic
polymers are provided, which contain at least 10% by weight
of copolymerized isocyanatoalkyl (meth)acrylate, are substan-
tially free of toxic monomeric isocyantes, and have the
following general structure:
<IMG> where R is alkyl or aryl,
R1 is hydrogen or methyl;
X is COO-A-NCO or a mixture
of COO-A-NCO and at least
one of phenyl, COOR2,
<IMG>, Cl, H;
where A is an alkylene
group having
2-6 carbon atoms,
and
R2 is an alkyl group
having 1-18 carbon
atoms;
and n is 2-400.
These polymers can be crosslinked and are useful in
a variety of applications such as finishes, pigment surface
treatments and dispersants, and theology control agents.

Claims

WHAT IS CLAIMED IS:
1. An isocyanate-functional polymer containing at
least 10%, by weight of the polymer, of copolymerized
isocyanatoalkyl acrylate or isocyanatoalkyl methacrylate,
wherein at least 10% by number of the polymer molecules have
the following structure:
<IMG> where R is alkyl or aryl,
R1 is hydrogen or methyl
X is COO-A-NCO or a mixture
of COO-A-NCO and at least
one of phenyl, COOR2,
<IMG>, Cl, H;
where A is an alkylene
group having
2-6 carbon atoms,
and
R2 is an alkyl group
having 1-18 carbon
atoms;
and n is 2-400 so that the polymer
has a number average molecular
weight, determined by gel
permeation chromatography,
utilizing polystyrene standards
of polydispersity less than 1.1,
of 500-10,000.
- 26 -

2. The polymer of claim 1 wherein the isocyanatoalkyl
methacrylate is isocyanatoethyl methacrylate.
3. The polymer of claim 1 wherein said R group is
selected from the group consisting of C4- C12 alkyl, phenyl,
and benzyl.
4. The polymer of claim 1 containing 15-50% of copolymer-
ized isocyanatoalkyl acrylate or isocyanatoalkyl methacrylate.
5. The polymer of claim 1 wherein X is COO-A-NCO.
6. The polymer of claim 1 wherein 25-40% by number
of the polymer molecules contain a terminal RS- group.
7. A moisture-curing coating composition consisting
essentially of an isocyanate-functional polymer containing at
least 10%, by weight of the polymer, of copolymerized
isocyanatoalkyl acrylate or isocyanatoalkyl methacrylate,
wherein at least 10% by number of the polymer molecules have
the following structure:
<IMG> where R is alkyl or aryl,
R1 is hydrogen or methyl;
X is COO-A-NCO or a mixture
of COO-A-NCO and at least
one of phenyl, COOR2,
<IMG>, Cl, H;
where A is an alkylene
group having
2-6 carbon atoms,
and
- 27 -

R2 is an alkyl group
having 1-18 carbon
atoms;
and n is 2-400 so that the polymer
has a number average molecular
weight, determined by gel
permeation chromatography,
utilizing polystyrene standards
of polydispersity less than
1.1 of 500-10,000; and a
catalyst.
8. A coating composition of claim 7 consisting
essentially of
(A) a polymer containing functional group complementary to
an isocyanate functionality selected from the group con-
sisting of hydroxyl, amino, and carboxyl; and
(B) a crosslinking agent which is an isocyanate-functional
polymer containing at least 10%, by weight of the polymer,
of copolymerized isocyanatoalkyl acrylate or isocyanatoalkyl
methacrylate, wherein at least 10% by number of the polymer
molecules have the following structure:
<IMG> where R is alkyl or aryl,
R1 is hydrogen or methyl;
X is COO-A-NCO or a mixture
of COO-A-NCO and at least
one of phenyl, COOR2,
<IMG> , -Cl, H;
-28-

where A is an alkylene
group having
2-6 carbon atoms,
and
R2 is an alkyl group
having 1-18 carbon
atoms;
and n is 2-400 so that the polymer
has a number average molecular
weight, determined by gel
permeation chromatography,
utilizing polystyrene standards
of polydispersity less than 1.1,
of 500-10,000.
9. A graft polymer obtained by contacting
(A) an isocyanate-functional polymer containing at
least 10%, by weight of the polymer, of copolymerized
isocyanatoalkyl acrylate or isocyanatoalkyl methacrylate,
wherein at least 10% by number of the polymer molecules have
the following structure:
<IMG> where R is alkyl or aryl,
R1 is hydrogen or methyl;
X is COO-A-NCO or a mixture
of COO-A-NCO and at least
one of phenyl, COOR2,
<IMG>, Cl, H;
where A is an alkylene
group having
2-6 carbon atoms,
-29-

and
R2 is an alkyl group
having 1-18 carbon
atoms;
and n is 2-400 so that the polymer
has a number average molecular
weight, determined by gel
permeation chromatography,
utilizing polystryene standards
of polydispersity less than 1.1,
of 500-10,000; and
(B) a substantially mono-functional polymer whose functional
group is selected from the group consisting of OH, COOH, NH2,
and NHR3, where R3 is alkyl group having 1-4 carbon atoms.
10. A coating composition of claim 7 consisting
essentially of
(A) a polymer which is the copolymer of styrene, methyl
methacrylate, and the esterification product of hydroxyethyl
acrylate, phthalic anhydride, and a glycidyl ester of the
formula
<IMG> , where R4 is a
tertiary aliphatic hydrocarbon group
containing 8-10 carbon atoms;
in the weight ratio of approximately 30:15:55; and
- 30 -

(B) an isocyanate-functional polymer containing at least 10%,
by weight of the polymer, of copolymerized isocyanatoethyl
methacrylate wherein at least 10% by number of the polymer
molecules have the following structure:
<IMG> where R is alkyl;
R1 is hydrogen, methyl or
mixtures thereof;
X is a mixture of
COO-CH2CH2-NCO and at least
one of phenyl, COOR2, <IMG>,
Cl, and H,
where R2 is an alkyl group
having 1-18 carbon
atoms; and
n is 2-400 so that the polymer
has a number average molecular
weight, determined by gel
permeation chromatography,
utilizing polystyrene standards
of polydispersity less than 1.1,
of 500-10,000.
-31-

11. A coating composition consisting essentially
of
(A) a polymeric or a low molecular weight
polyfunctional material containing a functional group
complementary to an isocyanate functionality selected
from the group consisting of hydroxyl, amino, and
carboxyl; and
(B) a crosslinking agent which is an isocyanate-
functional polymer containing at least 10%, by weight
of the polymer, of copolylmerized isocyanatoalkyl
acrylate or isocyanatoalkyl methacrylate, wherein
at least 10% by number of the polymer molecules have
the following structure:
<IMG> where
R is alkyl or aryl;
R1 is hydrogen or methyl;
X is a COO-A-NCO or a mixture
of COO-A-NCO and at least
one of phenyl, COOR2, <IMG>
Cl, H;
where A is an alkylene
group having 2-6 carbon
atoms, and
R2 is an alkyl
group having 1-18 carbon
atoms;
-32-

and n is 2-400 so that the polymer
has a number average molecular
weight, determined by gel
permeation chromatography,
utilizlng polystyrene stan-
dards of polydispersity less
than 1.1, of 500-10,000.
12. A coating composition of claim 11
consisting essentially of (A) a polyol and (B) a polymer
of butyl acrylate, isocyanatoethyl methacrylate and lauryl
mercaptan.
13. A coating composition of claim 11
consisting essentially of (A) 2-ethyl-1,3-hexanediol and
(B) a polymer of butyl acrylate, isocyanatoethyl methacry-
late and lauryl mercaptan.
14 . A coating composition of claim 11
consisting essentially of (A) a diamine and (B) a polymer
of butyl acrylate, isocyanatoethyl methacrylate and lauryl
mercaptan.
15. A self-supporting film formed from a
coating composition of claim 13.
16. A self-supporting film formed from a
coating composition of claim 14.
17. A coating oomposition of claim 11 which is
air-curable and wherein (A) is a drying oil alcohol.
-33-

18. A coating composition of claim 11 wherein
(A) is a low molecular weight polyfunctional material
selected from the group consisting of ethylene glycol,
polyethylene glycol, propylene glycol, polypropylene glycol,
butylene glycols, 1,12-dodecanediol, 2,2,4-trimethylpentane-
1,3-diol, 2-ethyl-1,3-hexanediol, trimethylol propane and
pentaerythritol.
19. A coating composition of claim 11 wherein
(A) is a low molecular weight polyfunctional material
selected from the group consisting of 2,2,6,6-tetramethyl-
piperazine and bis(2,2,6,6-tetramethyl-4-piperidyl)
sebacate.
-34-

Description

~3~2~2
BACKGROUND OF THE INVENTION
Field of Invention:
This invention relates isocyanate-containing
acrylic polymers and more particularly to low molecular
weight polymers ha~ing a terminal thioalkyl group and low
toxicity.
Prior Art:
Acrylic polymers containing pendent isocyanate groups
are known.
United States Patent 2,718,516, issued September 20,
1955 to N. M. Bortnick, describes high molecular weight polymers,
containing a plurality of isocyanate groups, based on (meth~
acrylic ester isocyanates. The polymers obtainable by the
described method are often intractable when the polymerization is
carried to completion or when high levels of the isocyanate
monomers are used during the polymerization.
Other types of organic polyisocyanates useful as
crosslinking agents are also well known.
.
United States Patent 3,124,605, issued March 10, 1964,
to K. Wagner, describes low molecular organic polyisocyanates
having the following biuret structure:
OCN-R-N-C-NX R-NCO
C=O
NX
R
NCO
- 1 -

%~2
where R is an aliphatic, hydroaromatic, araliphatic,
including aralkyl, or an aromatic radical, which may or
may not be substituted; and X is hydrogen or -CO-NX-R-NCO.
A commercially available example of such an isocyanate,
where R is ( CH2 )6 and X is hydrogen, has recently been found
to contain, upon aging, excessive levels of a residual mono-
meric diisocyanatef thereby increasing the toxicity.
SUMMARY OF THE INVENTION
According to the present invention there is provided
an acrylic polymer, prepared in a substantially non-aqueous
medium, and containing at least 10%, by weight of the polymer,
of copolymerlzed isocyanatoalkyl acrylate or isocyanatoalkyl
methacrylate, having the following general structure:
,Rl
- RS ~CH2 - C ~ E where R is al~yl or aryl,
X Rl is hydrogen or methyl;
X is COO-A-NC3 or a mixture
of COO-A-NCO and at least
one of phenyl, COOR2,
OCR2, Cl, E;
O
where A is an alkylene
group having
2-6 carbon atoms,
and
R~ is an alkyl group
having 1-18
carbon atoms;

113~
, .
and n is 2-400 so that the polymer
has a number average molecular
weight, determined by gel permeation
chromatography, utilizing polystyrene
standards of polydispersity less
than 1.1, of 500-10,000;
said polymer, in turn, comprising at least 10~ by number of the
acrylic polymer molecules resulting from a polymerization process
initiated by conventional initiators and mercaptan chain transfer
agents.
There are further provided crosslinkable coating
compositions based on ~he isocyanate-functional acrylic polymers
and crosslinking agents containing complementary functional groups,
such as hydroxyl, carboxyl or amino.
When used in this application, "consisting essentially
of" is intended to have its customary meaning: namely, that aLl
specified ma~erials and conditions are very important in practicing
the invention but that unspecified materials and conditions are not
excluded so long as they do not prevent the benefits of the inven-
tion from being realized.
DESCRIPTION OF THE INVENTION
The isocyanate-functional acrylic polymers of this
invention can be homopolymers or copolymers of isocyanatoalkyl
acrylates or isocyanatoalkyl methacrylates and contain at least
one terminal thioalkyl group for every ten polymer molecules.
Among the isocyanato monomers are isocyana~oethyl
acrylate, isocyanatoethyl methacrylate (ICEMA), isocyanatobutyl
acrylate, isocyanatobutyl methacrylate, isocyanatohexyl acrylate,
and isocyanatohexyl methacrylate. ICEMA is a preferred monomer
from the standpoint of ease of copolymerization and availability.

The acrylic polymers contain at least 10% by
weight of the polymer of the isocyanate monomer, preferably
15-50% and most preferably 25%. For certain applications,
no additional monomer is necessary and the homopolymer can
be used.
Among other monomers which can be used to
copolymerize with the isocyanate monomer, l.e., to provide
polymers where not all X in the formula below is -COO-A-NCO,
are the following: alkyl acrylates having 2-12 carbon atoms
in the alkyl group, such as ethyl acrylate, butyl acrylate,
2-ethylhexyl acrylate, alkyl methacrylates having 1-12 carbon
atoms in the alkyl group, such as methyl methacrylate, the
isomeric butyl methacrylates, hexyl methacrylate, 2-ethylhexyl
methacrylate; styrene, ethylene; vinyl estars such as vinyl
- acetate; vinyl chloride or mixtures of any of the foregoing.
These monomers can be present at levels not exceeding
90% by weight of the polymer or can be absent. Preferably, these
monomers comprise 85 to lO~ by weight of the polymer, and most
preferably 50 to 75~.
The polymers of this invention have low molecular
weights, the numher average molecular ~eight ranglng from 500
to 10,000 and preferably from 1,000 to 5,000. To obtain these
molecular weight ranges it is conventional technique to utiliz~
either high levels of initiators or chain transfer agents.
It has been found unexpectedly, that in spite of the
general reactivity of isocyanate groups with compounds containing
groups having acti~e hydrogens, the polymers of this invention can
be prepared using ~ercaptans as chain transfer agents. During the
- 4 -

~3~2~%
polymerization reaction, su~stantially no isocyanate groups
in the isocyanate containing monomers are consumed by the -SH
functionality of the mercaptan chain transfer agent and
polymers having the following general formula result:
Rl
RS ~CH2 - C~- H where R is alkyl or aryl,
X Rl is hydrogen or methyl;
X is COO-A-NCO or a mixture
of COO-A-NCO and at least
one of phenyl, COOR2,
OCR2, Cl, H;
O
where A is an alkylene
group having
2-6 carbon atoms,
and
R2 is an alkyl group
having 1 18 carbon.
atoms;
and n is 2-400 so that the polymer
has a number average molecular
weight, determined by gel
permeation chromatography,
utilizing polystyrene standard-
of polydispersity less than l.l,
of 500-10,000.

1~3~L24~
In gel permeation chromatography, a solution of the
material under investigation is passed through a series of
columns containing porous beads, each column being packed with
beads of a given porosity. As the solution passes through the
columns, the various components diffuse into the beads and out
again insofar as molecular volume and pore size are compatible.
Since the smaller molecules can diffuse into more pores, they
take longer to elute and are separated from the larger molecules
which elute quickly.
For the polymeric systems of this invention, samples
are dissolved in tetrohydrofuran to obtain an approximately 0.5
solution weight~volume and are passed through a system of
Styragel~ columns having porosities of 104, 103, and 60 A at
a flow rate of 1 ml./min. at room temperature. The location
(molecular weight) and amount of material eluting are indicated
by a differential refractome~er. The system is calibrated by
measurements on polystyrene standards having a polydispersity
o~ less than 1.1.
Molecular weights are computer calculated on the basis
of the polystyrene calibrations from data digitized and recorded
on tape for reading into a PDP-10 computer using a program modifying
the procedure of Pickett, Cantow, and Johnson, J. Applied Polymer
Sci., 10, 917-924 (1966) and J. Polymer Science (C), (21), 67-81
(1968). This gives an accurate comparison of the molecular weights-
and molecular weight distributions of similar resins. The absolute
accuracy of the molecular weights depends on how closely the
molecular weight/molecular volume relationship of the polymer
corresponds to the molecular wsight/molecular volume relationship
of the polystyrene standard.
- 6 -

~3~42
The resulting polymer contains as many thioalkyl
groups per polymer molecule as are dictated by the equivalent
ratio of chain transfer agent to initiator. For the purposes of
this invention, this ratio cannot be less than 1:10, yielding
a polymer wherein at least 10% by number of the acrylic polymer
molecules contain molecules of the structure indicated above.
Preferably, 25-40~ of the resulting polymer molecules will have
the indicated structure.
The amount of chain transfer agent used can be
determined by a number of factors, among others: desired
molecular weight o~ the polymer and the desired ratio of
number of polymer molecules having terminal thioalkyl groups
to other, initiator related, terminal groups. Chain transfer
agent can be present from 1-20% by weight of the polymer,preferably
3 to 15% and most preferably 5-9%.
The polymers are generally prepared in solution
in a substantially non-aqueous medium.
Among useful solvents for the preparation of the
isocyanate functional acrylic polymers are the following:
toluene, xylene, e~hyl acetate, butyl acetate, cyclohexar.e,
heptane, methyl isobu-tyl ketone, ether esters, N-methyl
pyrrolidone, and the li~e.
Various polymerization initiators can be used to
catalyze the polymerization of the isocyanate~monomers alone
or in combination with other monomers, for example, azobis-
isobutyronitrile, tert-bu~yl peroctoate, tert-butyl perbenzoate,
benzoyl peroxide.

1~L3~2~'~
Among the mercaptan chain transfer agents, the
ollowing are suitable: octyl mercaptan, lauryl mercaptan,
butyl mercaptan, tert-dodecyl mercaptan, benzyl mercaptan,
benzene thiol, cyclohexyl mercaptan, with lauryl mercaptan
and tert-dodecyl mercaptan being the preferred ones.
Other chain transfer agents can also be utilized
including, in addition to some of the traditional chain transfer
agents, disulfides and terminal olefins.
Depending on the type and amount of initiator, type
and amount of chain transfer agent, and their ratio to each
other, the molecular weight and polydispersity of the final
polymer can be regulated as necessary. The number average
molecular weight range of the polymer of this inv~ntion is
500-10,000 with a polydispersity not exceeding 4.
In order to achieve the non-toxic final polymers,
substantially free of toxic monomeric isocyanates, it is
preferred that the polymerization itself be carried out by
feeding monomer to the polymerization vessel in a
predetermined manner. The relative feed rates of various
monomers can be calculated from the reactivity ratios of
the monomers to be copolymerized.
The absence of residual monomeric isocyanate from the
polymeric product leads to a level of safety unknown in moisture
curing finishes based on oligomers and adducts made from difunc-
~ional isocyanates such as hexamethylene diisocyanate,bis-cyclo-
hexyl methanediisocyan te,isophorone diisocyanate, and 2,4-toluene
diisocyanate. Isocyanatoethyl methacrylate is at least 10 times

~312~;~
less toxic by inhalation than khese diisocyanates and can
be readily copolymerized to a free isocyanate level 10 to
1000 times lower than is usually found in conventional
diisocyanate-based polyisocyanates.
The isocyanate-functional polymers of this
invention can be utilized as crosslinking agents. Owing
to their relatively low molecular weight and low toxicity,
such polymers can be substituted for conventional organic
polyisocyanates in a variety of coatings applications.
Polymers containing complementary fllnctional groups
such as hydroxyl, amino or carboxyl, when cured with the iso-
cyanate-functional polymers, afford coatings of excellent
flexibility and du~ability. Polymercaptans can also be used
when in the presence of tertiary amine catalysts.
A wide variety o~ ethylenically unsaturated monomers
can be used to prepare the backbone of the hydroxyl containing
polymer used to forrn the coatin~ composition of this invention.
Typical monomers that can be used for the backbone are, for
example, vinyl chloride, vinylidene chloride; olefins, such as
ethylene, propylene and the like; vinyl acetate; conju~ated
dienes having 4 to lO carbon atoms, such as butadiene; aroma-
tic hydrocarbons having vinylene groups, such as styrene, alkyl
substituted styrene, such as a-methyl styrene; alkyl maleates,
such as dibutyl maleate; vinyl pyrrolidone; methacrylonitrile,
acrylonitrile, esters of methacrylic acid and acrylic acid,
preferably alkyl esters having 1-12 carbon atoms in the alkyl
group, such as methyl methacrylate, ethyl methacrylate, propyl
methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethyl-
hexyl methacrylate, lauryl r.lethacrylate and the like, methyl
acrylate, ethyl acrylate, propyl acrylate, butyl acrylate,
hexyl acrylate, lauryl acrylate and the lilce or mi~tures of
these monomers. Small amounts of ethylenically unsaturated

carboxylic acids can also be used in the backbone, such as
acrylic acid, methacrylic acid, crotonic acid, itaconlc acid,
maleic acid, and the like.
Particularly useful monomers or combinationS of
monomers which form the backbone of high quality polymers used
to form the coating composition of this in~ention are, for
example, s~yrene, methyl methacrylate, butyl methacrylate,
ethyl acrylate, acrylonitrile,and vinyl pyrrolidone.
Preferred hydroxyalkyl monomers used for ~orming the
polymer used in this invention are, ~or e~ample, hydroxyethyl
methacrylate, hydroxypropylemethacrylate, hydroxybutyl meth-
acrylate, hydroxyoctyl methacrylate, hydroxyethyl acrylate,
hydro~ypropyl acrylate, hydroxybutyl acrylate, hydroxyoctyl
acrylate and the like. Preferred are hydroxyalkyl meth-
acrylates or acrylates in which the alkyl groups contain 2-4
carbon atoms.
Carboxyl group containing polymers suitable for cross-
linking with the isocyanate-functional polymers include poly-
esters and addition polymers which contain copolymeriæed mono-
meric acids, such as acrylic acid, methacrylic acid, itaconicacid, maleic acid, and the like.
Suitable amine-functional polymers can be prepared
e.g., by copolymerizing ethylenically unsaturated monomers wi~h
~uch monomers as, for example, N-tertiary-butylaminoethyl methacrylate.
The isocyanate-functional polymers can also function
as the polymers to be crosslinked with low molecular weight poly-
functional materials containing complementary functional groups.
Among these functional groups are hydroxyl, amino, and carboxyl
groups.
-- 10 --

~3~L2
Examples of such low molecular weight poly-
functional materials are monomaric diols, triols and
tetraols such as ethylene glycol, diethylene glycol,
1,12-dodecanediol, 2,2,4-trimethylpentane-1,3-diol,
the butylene glycols, trimethylol propane, glycerol,
pentaerythrytol; polymeric polyols such as polyethylene
glycol, polypropylene glycol, and diol and triol polyesters,
monomeric dicarboxylic acids and polyesters containing, on the
average, at least two carboxyl groups per molecule; and di-
and poly-amines such as 2,2,6,6-tetramethylpiperazine and
bis(2,2,6,~-tetramethyl-4-piperidyl)sebacate.
The isocyanate-functional polymers of this invention
can also serve as backbone poiymers for grafting reactions,
utilizing the -NCO groups as the graft sites. Some or all of
these can be reacted with polymers containing only one comple-
mentary group, such as -OH, -NH2 or -NHR3 and -COOH, per
polymer molecule, to obtain graft polymers having the original
isocyanate-functionaI polymer as its backbone and the original
mono-functional polymers as the grafted side-chains. Preparing
graft polymers in this manner is advantageous over the more common
graft polymerization techniques which utilize free radical initiated
grafting to sites having active hydrogen atoms. The present method
affords control over the extent of grafting, from substantially
complete, i.e., approximately 95~ or higher, reaction of the
available -NCO groups, through gradations of 80%, 50~, 20~,etc.
of the number of isocyanate groups utilized.
Another way in which these isocyanate-functional
polymers can be used in grafting reactions is by first reacting
some or substantially all of the -NCO groups present in the
polymer with polymerizable monomers containing functional groups
which are ractlve with the -NCO groups. These functional group-
containing monomers are exemplified by hydroxyethyl acrylate,
-- 11 --
.,~

~3~Z4Z
hydroxypropyl methacrylate, acrylic acid, methacrylic acid,
and N-tertiaryl-butylaminoe~hyl methacrylate. In the second
step, the polymers so obtained now containing pendent poly-
merizable double bonds, can be graft copolymerized with any
of the conventional monomers. Such monomers are listed above.
The polymers containing pendent polymerizable double
bonds, based on the isocyanate-functional polymers of this
invention, canalso be utilized for purposes other than to serve
as the backbone polymers for further graft copolymerization.
These polymers can be cured through the use of conventional free
radical catalysts, ultraviolet radiation or electron-beam
radiation to yield hard coatings.
The isocyanate functional polymers of this invention
can also be reacted with difunctional compounds having groups
of differential reactivity to provide reactive sites on the
polymers which are removed farther from the polymer backbone
than is commonly possible. For example, if the polymers are
reacted with an amino-alcohol the product will be a polymer
having hydroxyl groups removed from the chain by several carbon
atoms. Some or substantially all o~ the isocyanate groups can
be so reacted. An example of such amino alcohol is 12-amino-
dodecane-l-ol.
Utilizing a drying oil alcohol in reacting with the
isocyanate functional poly~ers, the resulting product is a
system which can be cured in air at room temperature.
Th~ reaction of these isocyanate-functional polymers
with di-functional acids or amines or amino-acids, where the
acid can be carboxylic or sulfonic acid, affords a product which,
after neutralization with a suitable base, is a water dispersible
or water soluble system.
- 12 -

1~3~Z~%
The isocyanate-functional polymers of this invention
are also useful in coatings which can be cured when exposed
to atmospheric moisture. As an example, polymers having a
number average molecular weight not exceeding 3,000, can be
spray applied at greater than 60 volume ~ solids. One polymer,
containing approximately 40-60% ICE-~, 4-15~ lauryl mercaptan, and
the balance butyl acrylate, is particularly useful. It can cure
by absorbing moisture from the ambient atmosphere to produce a
crosslinked ~ilm with the evolution o~ small quantities of carbon
dioxide. This process can be facilitated by the presence of
organometallic dryers such as dibutyltin dilaurate without
compromising the one-package stability of the coating composition.
Small amounts of antioxidants and W screening chemicals can also
be added for extreme exposure conditions. Such additives, however,
are not usually necessary because of the inherent stability of
the crosslinked network to oxidation, hydrolysis, and light.
The property balance that can be achieved makes the
moisture cured isocyanate-functional pol~mers suitable for
coating bo~h rigid and flexible substrates. They are particularly
useful in exterior ambient temperature curing or lo~ bake finishes
for automobiles, trucks, aircraft, and railroad equipment.
A variety of substrates can be coated with coating
compositions based on the isocyanate-containing polymers of
this invention; the substrate~ can be rubbery, semi-rigid,
and metallic. Examples of suitable substrates are flexible
hydrocarbon rubbers such as EPDM (terpolymers of ethylene,
propylene, and diene), butyl rubber, styrene-butadiene rubber,
polybutadiene rubber or polyisoprene rubber; urethane and
Hytrel~ tregistered trademark of E. I. du Pont de Nemours and
Company) polyester rubber; injection molded polyester ure~hane;
elastoplastic microcellular urethane foam; ABS (terpolymers or
acrylonitrile, butadiene, and styrene); steel; aluminum.
- 13 -

~3~24æ
These coating compositions can be applied by any of
the standard application methods such as spray or roller coating
and brushing. When the coa-ting is applied by spraying it is
possible to utilize spray solids hlgher than has been customary
with many commercially useful prior art coatings. Solids contents
up to 100% can be obtained with low molecular weight diol cross-
linking agents. The coating thickness can be from 0.002 milli-
meter to 0.3 millimeter, the preferred thickness being approxi-
mately 0.05 millimeter.
The coatings based on the isocyanate-containing
polymers can be cured by moisture at room temperature or the
crosslinking process can be carried out at room temperature or
at elevated temperatures depending on the complementary functional
materials and catalyst, if any, to be utilized. Curing
temperatures of up to about 150C, at times of up to about 30
minutes~are often used.
The catalyst selection can depend on the complementary
functional groups present, to facilitate their reaction with
the -~CO groups. Among the useful catalysts are: dibutyl tin
dilaurate, stannous octoate, dimethylbenzylamine, triethylene-
diamine, dibutyl tin oxide.
Coating compositions based~on the isocyanate-
containing polymers of this lnvention can be pigmented. Typical
pigments which can be used are metallic oxides, preferably
titanium dioxide, zinc oxide, iron oxide, and the like, metallic
flakes such as aluminum flake, metallic powders, metallic
hydroxides, "Aflair"~ Flake pigments (a registered trademark
of E. I. du Pont de Nemours and Company), i.e.,mica coated with
titanium dioxide sulfates, carbonates, carbon black, silica,
talc, china clay, and other pigments, organic dyes, and lakes.
The amount o~ pigment utilized can depend on the type of final
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113~Z~2
application of these coatings. Pigment/binder ratios bet~een
3/100 and lO0/lO0 can be utilized with the preferred P/B range
being 3/100-50/100 for automotive applications and near the
maximum P/B ratio of 100/lO0 for other industrial coatings.
The following examples illustrate the invention.
All quantities are on a weigh~ basis unless o~herwise indicated.
EXAMPLE 1
An isocyanate-containing polymer is prepared
as follows:
Portion 1 Parts by Weight
isocyanatoethyl methacrylate 143.6
methyl methacrylate 47.8
butyl methacrylate 40.5
ethyl acetate 134.0
Portion_2
lauryl mercaptan 43.2
Portion 3
isocyanatoethyl methacrylate 95.7
methyl methacrylate 71.7
butyl methacrylate 60.6
azobisisobutyronitrile 3.25
Portion 4
lauryl mercaptan 18.5
ethyl acetate 44.6
Portion S
azobisisobutyronitrile 0.75
ethyl acetate 25.0
-- 15 --

The 2-isocyanatoetnyl methacrylate contains
27.1% NC0 (theory = 27.1). It is 99.9~ pure by gas
chromatography. It contains 0.03~ total chlorine and
0.009~ hydrolyzahle chlorine.
The polymerization vessel is a one-liter four-
necked round bottomed flask fitted with a stirrer, pot
thermometer and two Y tubes each carrying a reflux condenser
and dropping funnel. The reaction is nitrogen blanketed.
Portion 1 is charged to the flask and heated to
reflux at about 95C over 25 minutes. Portion 2 is then
added in about 10 seconds. Portions 3 and 4 are charged
to separate dropping funnels and added to the refluxing
solution (temperature approximately 90C) over 120 minutes
at a constant rate of addition. After 5 additional minutes
at approximately 90C, Portion 5 is added over 1 hour. The
temperatuxe drops to 85C and is held there for an additional
hour.
The resulting polymer has a composition of
isocyanatoethyl methacrylate/methyl methacrylate/butyl
methacrylate/lauryl mercaptan (in the form of a thioalkyl group)//
45.9/22.9/19.4/11.8 (by weight), a Gardner-Holdt viscosity of
S, and a solids content of 71.7% by weight. The polymer is clear,
colorless, free of gel particLes, and does not change in viscosity
or appearance over a period of four weeks.
The gel permeation cnromatographically determined
molecular weight is Mw = 5,300 and Mn = 1,800.
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ll3~æ~2
Based on the total weight of the polymer solution,
the residual monomer content (weight %) is, for the monomers
as listed above, 0.15, 0.22, 0.21, and 0.27, respectively.
Twenty grams of the po]ymer solution catalyzed with
0.1 milliliter of a 10% (in cellosolve acetate) solution of
dibutyl tin dilaurate, when cast onto glass, cures with
atmospheric moisture to afford a clear, colorless film having
a Knoop hardness (after 1 week at 50% relative humidity) of
10 and which is impervious to ethyl acetate.
Example 2
(A)
A polymer solution is formed by reacting the follow-
ing ingredients:
Parts By
Portion 1 Weight
Exylene 415.39
Hydroxyethyl acrylate 218.50
Phthalic anhydride 269.50
Cardura* E ester - (a mixed ester des-
cribed in U.5. Patent3,275,583, issued
September 27, 1966 and is a glycidyl
ester of a synthetic teritiary carboxylic
acid of the formula
0\ O
CH2 CH - CH - 0 - C - R
where R is a tertiary aliphatic hy~ro-
; carbon group of 8-10 carbon atoms) 481.25
Portion 2
Xylene 621.15
*denotes trade mark
- 17 -
~;:
d
.,

~3~ 2
Portion 3
Sytrene 567.88
Methyl methacrylate 288.74
Hydroxethyl acrylate 99.13
Tertiary butyl peroxide 17.33
Portion 4
Xylene 363.13
Cellosolve* acetate _ 58.00
Total 3500.00
Portion 1 is charged into a reactor equipped with a
reflux condenser and is heated to a reflux temperature and is
held at this temperature for about 1 hour. Portion 2 is then
added and the mixture is heated to its reflux temperature.
Portion 3 is premixed and slowly added over a 3-hour period
while maintaining the reflux condition and then the reaction
mixture is held at the reflux temperature for an additional
3 hours. The heat is removed from the reaction vessel and
Portion 4 is added.
The resulting polymer solution has a solids content
of about 55~ and a Gardner-Holdt viscosity of about ~ and the
polymer has an acid number less than 10. The polymer is the
copolymerization and esterification product of the following
reactants:
Parts by
Weight_
Styrene 29.5
Methyl methacrylate 15.0
Hydroxyethyl acrylate 16.5
Phthalic anhydride 14.0
"Cardura" E ester 25.0
Total 100.0
*denotes trade mark
,~ - 18 -
,;'~! ' ~,

~3~
.
(B)
An isocyanate-containing polymer is prepared as
followq:
Parts By
Weight
Portion 1
Styrene 390-4
2-isocyanatoethyl methacrylate387.1
Ethyl acetate 250.0
Port
Lauryl Mercaptan 17.9
Portion 3
. .
Azobisisobutyronitrile 17.5
Ethyl acetate 100.0
Styrene 90.8
2-isocyanatoethyl methacrylate131.7
Lauryl mercaptan 104.0
The 2-isocyanatoethyl methacrylate contains 27.1~ NCO
(theory = 27.1). It is 99.9% pure by gas chromatography. It
contains 0.03~ total chlorine and 0.009% hydrolyzable chlorine.
The polymerization vessel is a 3-liter four-necked flask
equipped as described in Example l.
Portion 1 is charged to the flask and heated to reflux
at 111C. Portion 2 is then added. Reflux is maintained by
heating as necessary as Portion 3 is added over 90 minu~es. The
mixture is allowed to reflux at 93C over an additional 270 minutes.
-- 19 --

~L3~
The resulting clear, colorless solution has a solids
content of 76.5% by weight and a calculated monomer composition,
hy weight ~, of styrene, 42.6; isocyanatoethyl methacrylate,
~5.9; lauryl mercaptan, 10.7; fragments from azobisisobutyro-
nitrile, 0.8, based on the assumption that l/2 of the initiator
weight becomes combined with the polymer.
The gel permeation chromatographically determined
molecular weight is Mw = 3,000 and Mn = 790
(C)
A coating composition is prepared by combining:
Parts By
Weight
Polyol as prepared in (A) above 15.2
Toluene 1.5
Cellosolve acetate 6.2
Ethyl acetate 4.1
Dibutyltin dilaurate ~0.001
Polymer as prepared in (B) above 5.6
Tensile test data obtained on a cured film,
approximately 0.05 millimeter thic~, obtained by drawing down
this composition on glass (at 10% minimum test rate), indicate
: the suitability of the coating for use on rigid substrates:
elongation, 4.9; tensile strength, 5000 PSI;
initial modulus, 187,000 PSI.
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~3l~æ
EXAMPLE 3
~A)
An isocyanate-containing polymer is prepared as
follows:
Parts By
Weight
Portion 1
2-isocyanatoethyl methacrylate 736
n-butyl acrylate 1040
Ethyl acetate 825
Portion 2
Lauryl mercaptan 193
Portion 3
A~obisisobutyronitrile 4.4
Ethyl acetate 75
: 2-isocyanatoe hyl methacrylate 682
n-butyl acrylate 258
Lauryl mercaptan 206
The polymerization vessel is a 5-liter ~our-necked
2~ flask equipped as descri~ed in Example 1.
:~
Portion 1 is charged to the flask and heated to reflux.
Portion 2 is then added. Reflux is maintained by heating as
necessary as Por~ion 3 is added over 90 minutes. Reflux is
continued for an additional 210 minutes. The final polymer has
a solids content of 75.0% and a viscosity of 60 centipoises.

2~
The gel permeation chromatographically determined
molecular weight is Mw = 5,600 and Mn = 1,900 and the polymer
has the following composition, by weight: butyl acrylate, 41.6;
ICEMA, 45.5; lauryl mercaptan, 12.8; fragments from azobisisobutyro-
nitrile, 0.07.
(B)
A coating composition is prepared as follows:
Parts By
Weight
Polyol as prepared in Example 2(A) 28.13
Toluene 2.8
Cellosolve acetate 11.5
Ethyl acetate 7.5
Dibutyl tin dilaurate 0.002
Polymer from (A) above 11.5
The film has the following tensile properties after 28
days of air drying:
elongation, 37~; tensile strength, 3500 psi; initial modulus,
118,000 psi.
20 This composition is suitable for use on flexible substrates.
EXAMPLE 4
An isocyanate-containing polymer is prepared as follows:
Parts By
Weight
Portion 1
Isocyanatoethyl methacrylate 21.9
Butyl acrylate 45.0
Ethyl acetate 44.2
Lauryl mercaptan 6.8
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, .. ~

gi~3~ 2
Portion 2
.
Azobisisobutyronitrile 0.01
Ethyl acetate 2.0
Portion 3
Isocyanatoethyl methacrylate 52.2
Butyl acrylate 36.3
Lauryl mercaptan 15.4
Azobisisobutyronitrile 0.9
Toluene 36.0
Portion 4
Butyl acrylate 68.0
Isocyanatoethyl methacrylate 76.3
Toluene 37.8
Ethyl acetate 21.0
Azobisisobutyronitrile 13.5
Portion 5
Azobisisobutyronitrile 0.1
Ethyl Acetate 4.0
The polymerization vessel is a l-liter, four-necked
flask, equipped as described in Example 1.
Portion 1 is charged to the flask and brought to reflux
over 15 minutes. Portion 2 is then added. Reflux is maintained
by heating as necessary as Portion 3 is added over 40 minutes.
Reflux is maintained by heating as Portion 4 is added over 80

~.31%4%
minutes. After an additional 20 minutes at reflux, Portion
5 is added and, after an additional 30 minutes at reflux, the
polymerization is substantially complete. The product has a
solids content of 68.2~ and a viscosity of 70 centipoises.
The gel permeation chromatographically determined molecular
weight is ~ = 6,500 and Mn = 2,100 and has the following
composition by weight: isocyanatoethyl methacrylate, 45.7;
butyl acrylate, 45.4; lauryl mercaptan, 6.7; initiator residue,
2.2.
This po'ymer is self-crosslinking when exposed to
ambient (50% RH) air for one week using the following mixture:
10 grams of polymer solution and 0.05 milliliter of a 10%
dibutyltin dilaurate solution in cellosolve acetate.
This 68~ solids solution has a viscosity of 70
centipoises and thus can be categorized as a high solids coating.
It is coated on glass using a 6 mil blade to form, after a one-
week cure at 25C (50% RH), a 0.07-millimeter thick, clear,
colorless, film with a 6.1 Knoop hardness, having the following
tensile properties:
elongation to break, 20%; tensile s~rength, 3000 psi;
initial modulus, 71,000 psi.
EX~MPLE 5
A 10.0-gram portion o the polymer of Example 4 is
mixed with 0.98 gram of 2-ethyl-1, 3-hexanediol and 0.05 milli-
liter of a 10% solution of dibutyltin dilaura~e in cellosolve
acetate.
- 24 -

~3~
This solution has a 70.9% non-volatile content
and a viscosity of 65 centipoises. It has a useful working
life of about two hours at 25C.
When cast on glass and cured for one week at 25C
and 50% RH, a clear, colorless film, approximately 0.06 milli-
meter thick, is produced. It has a Knoop hardness of 2.9.
Its tensile properties are:
elongation to break, 29%; tensile strength, 1700 psi; and
initial modulus, 35,000 psi.
EXAMPLE 6
.
A 40.0-gram portion of the polymer of Example 4 is
mixed with 13.3 grams of a diamine, having the following
structure:
C~ C}I
3 ' 3 CH CH~
~ O O ~
~-O C- (CH2) g C~O~~rqH
CH3 CH3 CH3 3
dissolved in 48.0 grams of ethyl acetate.
After casting on glass, an approximately 0.07
millimeter dry film results. After a l-week curing period
at 25C at 50% relative humidity, the Knoop hardnesc value
of the film is 7.2, its elongation to break is 60~, its
tensile strength is 2,800 psi, and its initial modulus is
53,000 psi.
- 25 -