Note: Descriptions are shown in the official language in which they were submitted.
104 ~ g392
This invention rel~tes to the field of capro-
lactone polyols and coating composltions, particularly
urethane coatings, derived therefrom.
BACKGROUND OF THE INVENTION
It is known that caprolactone polyols are
suitably employed in forming urethane coatings and that
they offer a number of advantages over conventional poly-
ester polyols. One of these advantages is that reaction
of caprolactone polyols with polyisocyanates generally
provides urethane coatings having better weathering
characteristics. Clear coatings for exterior application
are obtained from caprolactone polyols and aromatic poly-
isocyanates such as tolylene diisocyanates but such coatings
tend to yellow due to the known light instability associated
with aromatic diisocyanates.
It is also known that light stable urethane
coatings are provided by reaction of caprolactone polyols
with aliphatic diisocyanates. However, polyisocyanates of
the latter type such as~ in particular, 4,4'-methylene-
bis(cyclohexylisocyanate), either provide toxic coatingsdue to significant amounts of unreacted isocyanate, or
otherwise tend to provide soft coatings not suitable for
many high performance applications. One such end-use is
the coating of exterior aircraft surfaces. The require-
ments of such coatings are particularly severe for, in
addition to exterior durability characteristics such as
high hardness, good impact resistance, adhesion, stain
2.
104~1~4 9392
resistance and low temperature flexibility, the coatLng
must possess considerable chemical resistance to potential
attack by aircraft hydraulic fluids.
It is, therefore, a primary object of this
invention to provide particular caprolactone-based polyols
which are especially useful in the formation of high
performance coatings.
Another object is to provide such polyols which
are used with particular advantage in forming light stable,
urethane coatings having good hardness, weatherability and
substantial chemical resistance to hydraulic 1uids.
A further object is to provide improved urethane
coatings for application to external aircraft surfaces.
Various other objects and advantages of this
invention will become apparent to those skilled in the
art from the accompanying description and disclosure.
SUMMARY _F THE INVENTION
In accordance with one aspect of the teachings
of this invention, highly functional caprolactone polyols
useful in forming coating compositions, are provided as
the products formed by the reaction of a caprolactone
polyol having an average hydroxyl functionality of at
least three with a polyepoxide having an epoxy function-
ality of at least two. It has been discovere!d that the
polyepoxide-caprolactone polyol adducts provided by the
present invention are especially adapted to forming high
performance urethane coating compositions having the '!
,
, ' '' ' '
9392
1 0~ 4
aforementioned desirable characteristics of e~terior
durability and chemical resistance. In accordance with
another aspect of the teachings of this invention, two-
package urethane coating compositions are.provided which
comprise the (l) polyepoxide-caprolactone polyol adducts
described herein, and (2) an organic polyisocyanate.
DETAILED DESCRIPTION OF THE INVENTION
AND PREFERRED EMBODIMENTS
The parent caprolactone polyol which is reacted
with a polyepoxide as described herein is provided by the
reaction of an epsilon-caprolactone in the presence of a
polyhydric initiator having at least three reactive hydrogen
atoms present as hydroxyl. The epsilon-caprolactone monomers
have the general formula,
R'
H-C- ~ C'O
O
where R~ is hydrogen or lower alkyl, that is, a linear or
branched alkyl group having from 1 to 4 carbon atoms such
as methyl, ethyl, propyl, isopropyl, butyl and t-butyl.
Usually at least six of the R~ groups are hydrogen and the
remaining three are hydrogen, methyl or any combination
thereof. The caprolactone polyol, which is reacted with
a polyepoxide as described herein, has a hydroxyl function-
ality corresponding to that of the polyhydric initiator and
contains at least one oxycaproyl unit, that is,
4.
104~4 939Z
o
-O-CH(Rl)-(cR~2)4-c-
Usually, the average number of such units is no more than
about 10. More specifically, the caprolactone polyol
reactants are prepared by the reaction of the aforesaid
epsilon-caprolactone monomers with a y-functional poly-
hydric initiator where y has a value of at least three and
is usually no more than six, employing a monOmer to initiator
mole ratio of from 1:1 to about 10:1. The preparation of
the parent caprolactone polyols is illustrated by the
following equation which is specific to the preferred
monomer, epsilon-caprolactone:
R ~~~OH)y + x CH2-(CH2)4-C5
o J
(1)
o
R"~O~C-CH2CH2CH2CH2CH2-O~H]y
where R" denotes the residue of a polyhydric alcohol after
substracting y number of -OH groups, y being as aforesaid,
and x has a value of from 1 to about 10. It is to be under-
stood that when x has a value of one, for example, theoxycaproyl unit is terminated by one hydroxyl group and
y-l hydroxyl groups remain bonded to R" of the polyhydric
initiator.
Illustrative of suitable polyhydric initiators
encompassed by R'l~~~OH)y are the following: glycerol,
trimethylolethane, trimethylolpropane, 1,2,4-butanetriol,
5.
.
.:~
~04'~1~4 9392
l,2,6-hexanetriol, pentaerythritol, dlpentaerythritol,
oxyethylated and/or oxypropylated adducts of such compounds
such as, for example, ethylene oxide adducts of trimethylol-
propane, and mixtures of any of the aforesaid initiators.
It is evident, therefore, that R" is a saturated, aliphatic
radical having at least three carbon atoms and consists of
carbon and hydrogen, or carbon, hydrogen and oxygen where
oxygen is present solely as ether oxygen as in dipentaeryth-
ritol or the aforementioned oxyalkylated adducts. The more
commonly employed initiators have no more than 10 carbon atoms.
The generally preferred class of caprolactone
polyols for use in preparing the novel po~yepoxide reaction
products thereof, are the epsilon-caprolactone triols having
an average molecular weight from about 300 to about 1300, or
corresponding hydroxyl numbers from about 560 to about 130.
Most preferred are the triols having an average molecular
weight DO higher than about 900 and a hydroxyl number no
less than about 185.
The parent caprolactone polyols which are reacted
with polyepoxides as described herein are prepared by methods
known to the art such as those described in United States
Patent No. 3,169,945, the teachings of which are incorporated
herein by reference thereto. It is generally preferred that
the reaction between the polyhydric initiator and monomer be
effected at a temperature between about 130C. and about
200C. in the presence of a catalyst such as stannous octoate
or the other catalysts disclosed in said patent.
6.
104~4 9392
The polyepoxides used in preparing the novel
polyol composltions of the present invention comprise those
organic materials which have at least two vicinal epoxy
groups having the structure,
-CH CH-
which may be in a linear position or the carbon atoms thereof
may be common to a saturated, five-, six- or seven-membered
carbocyclic ring. When present in a linear position, the
epoxy groups may be terminal, that is,
-CH CH2
groups, or they may be internal, that is,
/o\
-C-CH CH-C-
groups. Usually, the polyepoxide reactants contain no more
than four of any one or combination of the aforesaid types
of vicinal epoxy groups. The polyepoxide reactants are
essentially free of ethylenic or acetylenic sites of
unsaturation, that is, they are free of unsaturation of
the non benzenoid type. It is to be understood, however,
that they may comprise one or a plurality of aromatically
unsaturated carbocyclic nuclei. Usually, no more than two
of such aromatic nuclei are present. In addition to non
7.
-' -
~,
,
10~'~134 9392
benzenoid unsaturation, the polyepoxide re~ctants ~re
essentially free of functional groups other than epoxy.
The polyepoxides, therefore, consist of the elements
carbon, hydrogen and oxygen with the following provisos: ¦
(1) when the molecule contains oxygen in addition to
oxygen of the epoxy groups, such additional oxygen is
present either as ether oxygen, that is, -C-0-C, or as
the carbonyloxy group of carboxylic acid ester (or carboxylate)
groups, that is, -C-C(0)0-C-; and (2) when sromatic nuclei
are present in the molecule, the ring carbon atoms thereof
may be substituted with bromine or chlorine. Usually, the
polyepoxides employed in the practice of this invention
contain from 8 to 30 carbon atoms per molecule, although
certain polyepoxides derived from naturally occurring oils
may contain a greater number of carbon atoms.
From the standpoint of providing reaction products
which are useful in forming urethane coatings for exterior
application, it is preferred to react the base caprolactone
polyol with a cycloaliphatic diepoxide. As used herein,
the expression "cycloaliphatic diepoxide" is intended to
include compounds in which the respective carbon atoms of
both epoxy groups are either common to a saturated carbo-
cyclic nucleus or linear thereto, as well as compounds in
which the carbon atoms of one epoxy group are common to the
carbocyclic nucleus and the second epoxy group is linear
thereto. Such cycloaliphatic diepoxides include compounds
having two 3,4-epoxycyclohexyl groups that are linked by an
8.
9392
10~ 34
ester-containing organic moiety. Suitable compounds of
this type include diepoxides having the general formula:
R2 0 O R2
CH2-0-C _ - RC-O-CH2- ~ o (I)
R ~ R2 R2 ~ R
R2 R2
wherein R represents hydrogen or lower alkyl radicals, that
is, alkyls having from 1 to 4 carbon atoms, R is a valence
bond or a divalent hydrocarbon radical having from 1 to 9
carbon atoms and is free of non benzenoid unsaturation, and
a has a value of zero or one. It is to be understood that
the R groups may be the same as or different from one
another. Preferred compounds encompassed by Formula I are
those wherein R is hydrogen or methyl and no more than two
of the nine R groups bonded to each ring are methyl.
When a of Formula I is zero, the diepoxides are
3,4-epoxycyclohexylmethyl 3~4-epoxycyclohexanecarboxylates
having the formula,
R2 R2
HZ-O-~
R2 R2
Among specific compounds falling within the scope of
Formula I-l are the following:
'
9392
1C~ 3 4
3,4-epoxycyclohexylmethyl 3,4-epoxycyclohex~necarboxylate;
3,4-epoxy-1-methylcyclohexylmethyl 3,4-epoxy-1-methy1cyclo-
hexanecarboxylate;
3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclo-
hexanecarboxylate;
3,4-epoxy-3-methylcyclohexylmethyl 3,4-epoxy-3-methylcyclo-
hexanecarboxylate; and
3,4-epoxy-5-methylcyclohexylmethyl 3,4-epoxy-5-methylcyclo-
hexanecarboxylate.
Other suitable compounds within Formula I-l are described
in U.S. Patent No. 2,890,194 to B. Phillips et al., issued
June 9, l9S9.
When a of Formula I has a value of one, the
compounds are diepoxides of cycloaliphatic esters of
dicarboxylic acids having the formula,
R2 R2
~ CH20-C-R~-C-OCH2 ~ ~I-2)
R2 R2
where R and R are as previously defined. Preferably, R
is a bivalent alkylene radical of the series, -CmH2m-, where
m has a value from 2 to 6 such as ethylene (-CH2CH2-), tetra-
methylene, pentamethylene and hexamethylene. Among specific
diepoxides encompassed by Formula I-2 are the following:
bis~3,4-epoxycyclohexylmethyl)oxalate;
bis(3,4-epoxy-6-methylcyclohexylmethyl)succinate;
10.
~ 04 ~ 9392
bis(3J4-epoxycyclohexylmethyl~adipate;
bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate; snd
bis(3J4-epoxycyclohexylmethyl)pimelate.
Other suitable compounds within Formula I-2 are described
in U.S. Patent No. 2,750,395, to B. Phillips et al., issued
June 12, 1956.
Another class of cycloaliphatic diepoxides of
the cyclohexene oxide type which are suitably reacted with
caprolactone polyols as described herein, are those wherein
the two 3J4-epoxycyclohexylmethyl rings shown in Formula I-2
are linked through an oxy (-O-) group, in place of the
dicarboxylate bridge. Illustrative of such compounds is
bis(3,4-epoxycyclohexylmethyl)ether.
Other suitable cycloaliphatic diepoxides in which
the respective carbon atoms of each epoxy group are common
to a saturated carbocyclic ring are the following:
2,2-bis(3,4-epoxycyclohexyl)propane which has the formula,
CH3
~}' <~
CH3
bis(2,3-epoxycyclopentyl)ether which has the formula,
. ~ P\
}0~
dicyclopentadiene dioxide (that is, l,2:5,6-diepoxyhexahydro-
4,7-methanoindan) which has the formula,
- 11.
.
~O 4'~ ~ ~ 4 9392
~0
It i8 to be understood that, in addition to the above-
described cycloaliphatic diepoxides wherein the carbon atoms
of both epoxy groups sre common to a carbocyclic ring, only
one need be so positioned and the second epoxy group may be
linear thereto. Illustrative of this type of compound for
reaction with caprolactone polyols as described herein, i6
4-(1,2-epoxyethyl)-1,2-epoxycyclohexane which has the formula,
~ CH CH2
6 ~
Other suitable cycloaliphatic diepoxide reactants are those
in which both epoxy groups are linear to the carbocylic
nucleus as in 2,2-bis[4-(2,3-epoxypropoxy)-cyclohexyl]propane
which has the formula,
/ O\ CH3 / o
CH2-CH-S:H2 O{>--C ~O-CH2-CH-cH2
CH3
Illustrative of suitable aromatic polyepoxides
for reaction with caprolactone polyols as described herein
are those in which the aromatic cyclic nucleus is substituted
with a 2,3-epoxypropoxy group, that i8, CH2-CH-CH2-0-.
1 0~ 4 9392
This class of reactants are exemplified by the following
compounds:
1,3-bis(2,3-epoxypropoxy)benzene;
2,2-bislp-(2,3-epoxypropoxy)phenyl]propane which has the
formula~
CH2-CH-CH2-0 ~ CH3 0-CH2-CH-CH2; and
CH3
2,2-bis[4-(2,3-epoxypropoxy)-3,5-dibromophenyl]propane.
Another class of polyepoxides comprising a cyclic
nucleus that is contemplated for use in preparing the novel
polyol compositions of this invention are glycidyl esters of
aromatic and saturated cycloaliphatic dicarboxylic acids
such as, for example, diglycidyl phthalate which has the
formula,
/0\ O O /0\
CH2-CH-CH2-0-C-C6H4-C-O-CH2-CH-CH2
Although the above-described diepoxides containing
a carbocyclic nucleus are the generally preferred classes
of polyepoxides for use in preparing the novel polyols of
the present invention, acyclic polyepoxides are also con-
templated. Illustrative of such reactants are: 1,2,3-
tris(2,3-epoxypropoxy)propane; 1,4-bis(2,3-epoxypropoxy)butane;
and epoxidized soybean oil.
. 13.
. '
.
. .
1 0~ 4 9392
The above-described caprolactone polyols end
polyepoxides are reacted in relative proportions such
that sufficient hydroxyl groups are present in the system
to react substantially all of the epoxy groups. The
reaction is effected at a temperature between about 100C.
and about 190C., usually between about 130C. and about
175C., and proceeds satisfactorily at substantially
atmospheric pressure. The reaction is carried out for a
sufficient period of time to obtain substantially complete
reaction of the epoxy groups, that is, until the oxirane
content is less than about 0.5 weight percent. This con-
dition is readily determined by periodic sampling of the
reaction mixture and analyzing for oxirane content by
standard procedures.
In accordance with a preferred embodiment for
producing the polyol compositions of the invention,
substantially about z moles of caprolactone polyol per mole
of the polyepoxide are employed where z is the epoxy
functionality of the polyepoxide which, as previously
defined, is at least two and usually no more than four.
By "substantially about" in this context is meant no less
than 10 percent below and no more than 25 percent above any
given value of z. Otherwise stated, the preferred mole
ratio of caprolactone polyol to polyepoxide is from about
(z minus 0.1z):1 to about (z ~ 0.25z):1, where z has a
value from 2 to 4. Thus, the preferred mole ratio of
caprolactone polyol to polyepoxide is from about 1.8:1
14.
10~ 4 9392
to about 5:1, the partlcular mole ratio employed depending
upon the epoxy functionality (that i8, the value of z) of
a given polyepoxide reactant. For example, when a diepoxide
is used, the preferred mole ratio of caprolactone polyol to
diepoxide is from about 1.8:1 to about 2.5:1. From the
standpoint of providing polyol products having a maximum
hydroxyl functionality, it is most preferred to employ
about z moles of caprolactone polyol reactant per mole of
polyepoxide. For this purpose, therefore, the most
preferred mole ratio of polyol reactant to polyepoxide
reactant is from about 2:1 to about 4:1, depending upon
the functionality of the particular polyepoxide employed.
It iB to be understood that, provided the reaction system
contains sufficient free -OH to effect substantially com-
plete reaction of the epoxy groups, mole ratios encompassing
limits outside of the said preferred and most preferred
ranges may be employed without departing from the scope of
this invention. Thus, the reactants may be employed in
equimolar amounts up to an amount usually no greater than
about (z ~ 0.5z) moles of caprolactone polyol per mole of
polyepoxide.
While not wishing to be held to any particular
theory or reaction mechanism, it is believed that during
the reaction of the caprolactone polyol and polyepoxide,
at least a major portion of the epoxy groups are mono-
functional when reacted with hydroxyl of the caprolactone
polyol such that the equivalent of one hydroxyl group of
15.
~ '~
~ o~ 4 9392
the polyol reacts with a single epoxy group to open the
oxirane ring to form a hydroxyl ~roup on one of the oxirsne
carbon atoms, and an ether linkage with the second oxirane
carbon atom and a carbon atom of the polyol. ~y way of
illustration, reference is had to the following equations
(2) and (3) wherein equation (2) illustrates the formation
of a caprolactone triol, designated as "A", which is then
reacted in equation (3) with one of the above-described
cycloaliphatic diepoxides of the cyclohexene oxide type
in a stoichiometric mole ratio of 2:1, respectively.
Equation 2:
CH20H
CH3CH2-C-CH20H + X Cl H2- (CH2)4-cl =O >
CH20H O
CH2 [O-C(O) - (CH2)5 ]a~OH
CH3CH2-c-cH2[o-c(o)-(cH2)5]b OH
CH2[~C()~(CH2)5]c~OH
A
Equation 3:
_ _
2A + O ~ [-X-]
_ _ 2
HO
CH2[O-C(O)^(CH2)5]a OH ~
CH3CH2-C-cH2[O-c(o)-(cH2)5]b ~ [-X-]
CH2[~C()~(CH2)5]c-OH
_ _ 2
16.
lC~4 ~ 1 ~ 4 9392
In the above equations, ~ b and c csn be zero or a
positive number provided the sum a+b+c has the value of
_ which, as above defined, is from 1 to sbout 10, and X
is any of the above-defined bivalent groups that links
the two 3,4-epoxycyclohexyl nuclei such as -CH2-0-C(0)-,
-CH2-0-C(O)-R-C(O)-O~CH2-, -O- or -C(CH3)2-. It is to
be understood that the structure of the product shown in
equation (3) is illustrative only and that any of the three
hydroxyl groups of the caprolactone polyol reactant (A) may
react to open the oxirane groups of the diepoxide reactant.
It is desirable that the hydroxyl functionality
of the novel polyol products of the invention be sub6tan-
tially greater than that of the parent polyol reactant.
To this end, it is recommended practice to employ the
reactants within the above-discussed preferred and most
preferred mole ratios. For example, when the polyols of
the invention are prepared employing about z moles of
parent caprolactone polyol per mole of polyepoxide, as a
general rule the functionality of the polyol product is at
a maximum and is about z times that of the parent polyol
where 3J as previously defined, is the epoxy functionality
of the particular polyepoxide employed. For example, in
accordance with the mechanism on which the reaction of
equation (3) is based, the triol-diepoxide adduct has a
maximum hydroxyl functionality of six, that is, twice that
of the parent caprolactone triol reactant.
~. . , . , . is ~ .
104~4 9392
It is to be understood that the structure of the
products shown in equation (3) may be oversimplified and
that the reaction products may comprise additional compounds
formedJ for example, by reaction of the -OH group formed
upon opening of the oxirane ring with an epoxy group of
another molecule. The polyol product may also comprise
species formed by a mechanism involving the reaction of
the hydroxyl group of the polyol with ester functionslity
in the bisepoxides encompassed by above Formula I-2. It
is to be understood, therefore, that although it is believed
that the polyol compositions of this invention are pre-
dominantly adducts formed by the mechanism discussed w~th
reference to equation (3), they may also comprise structures
of a different or more complex nature.
The novel polyols of the invention comprising the
products formed by reaction of the above-described capro-
lactone polyols and polyepoxides have hydroxyl numbers from
about 560 to about 50, and an average molecular weight from
about 600 to about 6700. Hydroxyl number is determined by
and is defined as the number of milligrams of potassium
hydroxide required for the complete neutralization of the
hydrolysis product of the fully acetylated derivative
prepared from one gram of polyol or mixture of polyols.
The hydroxyl number iB also defined by the following equation
which reflects its relationship with the functionality and
molecular weight of the polyol:
. ' ~
104'~4 9392
OH - 56.1 x 1000 x f
M. W.
wherein OH - hydroxyl number of the polyol;
f - average functionality, that i9, average
number of hydroxyl groups per molecule
of polyol; and
M. W. e average molecular weight of the polyol.
The reaction of the caprolactone polyol and poly-
epoxide may be effected in the absence or presence of a
catalyst, and is usually effected in the presence of a
catalyst. Metal catalysts, particularly organic derivatives
of tin including stannous and stannic compounds, are especially
suitable. Illustrative of this type of catalyst are the
following which may be employed individually or in combi-
nation: stannous salts of carboxylic acids such as stannous
octoate, stannous oleate, stannous acetate and stannous
laurate; dialkyltin dicarboxylates such as dibutyltin
dilaurate, dibutyltin diacetate, dilauryltin diacetate,
dibutyltin ti(2-ethylhexanoate) and other such tin salts
as well as dialkyltin oxides, trialkyltin oxides, tin
mercaptides such as, for example, di-n-octyl tin mercaptide,
and the like. The catalyst is used in a catalytically
effective amount which is usually between about 0.001 and
about 0.1 weight percent of the combined total weight of
the caprolactone polyol and polyepoxide reactants.
If desired, the reaction may be carried out in
the presence of a solvent or diluent that will not interfere
with the desired formation of the caprolactone polyol-poly-
19 .
- ~ . . - . - .
: . , , : ' ,
.. , . - : : -
.
,: ' ' ' ' - '
104'~4 9392
epoxide adducts described herein. Such diluents are well
known and include ethers, hydrocarbons and ketones such as
diethyl ether, p-dioxane, dibutyl ether, tetrahydrofuran,
diisopropyl ether, methyl ethyl ketone, methyl n-propyl
ketone, hexane, toluene, xylene, benzene, and the like.
The polyol products of the invention are generally
normally liquid, including very viscous, materials. They
are recovered by conventional techniques, depending upon
the physical nature of the particular reaction product.
For example, the more viscous products are recovered as
the residue products remaining after any volatile material
such as diluent is separated.
The novel polyol products of the invention are
useful in forming polyurethane products, particularly poly-
urethane coatings, by reaction with polyisocyanates. From
the standpoint of providing relatively hard coatings for
application to rigid surfaces such as metals, those polyols
having hydroxyl numbers from about 560 to about 300 are
generally preferred. When the polyol products of the
invention are to be used to form softer polyurethane coatings
for application to a more flexible substrate such as cloth,
leather, vinyl or magnetic tape, the products having hydroxyl
numbers from about 300 to about 50 are usually selected.
The polyisocyanates reacted with the novel capro-
lactone polyol-polyepoxide adducts of the present invention
are known to the art and any such reactants containing free-
NC0 groups are suitably employed. Among such suitable
20.
~04'~1~4 9392
reactants are aliphatic, cycloallphatic, araliphstlc nd
aromatic polyisocyanates, and biuret-contsinlng polylso-
cyanates. Usually, the aromatic polyisocyanates are u~ed
in applications not requiring light stable coatings.
Illustrative of suitable polyisocyanates for reaction with
the novel polyol compositions of the present invention are:
1,4-hexamethylene diisocyanate; 1,6-hexamethylene diisocyanatej
4,4'-methylene-bis(cyclohexyl i8 ocyanate), also sometimes
named 4,4'-dicyclohexylmethane dlisocyanate; bis-(2-iso-
cyanatoethyl)fumaratej 2,4-tolylene diisocyanate, 2,6-
tolylene diisocyanate and mixtures of these isomers; crude
tolylene diisocyanates; 4,4'-diphenylmethane-diisocyanatej
6-isopropyl-1,3-phenylene-diisocyanate; durylene diisocyanate;
4,4~-diphenylpropane d ii8 ocyanate; 3,5,5-trimethyl-3-iso-
cyanato-methyl-cyclohexane-isocyanate-(l), commonly referred
to as "isophorone-diisocyanate"; biuret-containing polyiso-
cyanates such as those prepared by reaction of any of the
above diisocyanates with water at a molar ratio of at least
3:1 to about 6:1, as described in United States Patents
3,706,678 and 3,201,372, and N,N',N"-tris-(isocyanatohexyl)-
biuret; triphenylmethane-4,4',4"-triisocyanate; and any of
the other organic polyisocysnates well known to the poly-
urethane art. For example, other useful polyisocyanates
for reaction with the novel polyols of this invention are:
the polyphenylmethylene polyisocyanates produced by
phosgenation of the polyamine obtained by acid-catalyzed
condensation of aniline with formaldehyde. Polyphenyl-
21.
.
'
1~'~134 9392
methylene polyisocyanates of this type are available com-
mercially under such tradenames AS PAPI, NLAX Isocyanate
AFPI, Mondur MR, Isonate 390P, NCO-120, Thanate P-220, NCO-10
and NCO-20. These products are low viscosity (50-500 centi-
poises at 25C.) liquids having average isocyanato function-
alities in the range of about 2.25 to about 3.2 or higher,
and free -NCO contents of from about 25 to about 35 weight
per cent, depending upon the specific aniline-to-formaldehyde
molar ratio used in the polyamine preparation.
The novel polyol compositions of the present invention
are reacted with the organic polyisocyanate reactant in an
amount sufficient to provide an -NCO/-OH equivalent ratio of
from about 0.8:1 to about 1.4:1, preferably from about 1:1
to about 1.2:1.
The reaction between the polyisocyanate and the capro-
lactone polyol-polyepoxide adducts provided by the invention
may be carried out in the presence or absence of a catalyst.
Usually, a catalyst is used. Such catalysts are known to the
polyurethane art and include any of the above-described organic
derivatives of tin such as, in particular, tin salts of organic
acids and organotin compounds. Of these, dibutyltin dilaurate
is especially preferred. It is to be understood, however,
that any other tin catalyst can be used such as stannous
octoate, as well as other metal catalysts such as lead octoate.
When used, the catalyst for promoting the -NCO/-OH reaction is
present in the formulation in amounts from about O.001 to about
0.05 weight percent, based on the polyurethane-forming reactants.
22.
~04~1~4 9392
Other components which may be present in minor
amounts in the coating formulation are organosilicones which
function as surface coating leveling aids. Such organo-
silicones are known to the art and include polydimethyl-
siloxane oils and polydimethylsiloxane-polyoxyalkylene
copolymers of relatively low molecular weight. ~ther
conventional additives such as pigments, colors, diluents
or solvents, fillers, plasticizers and grinding aids may
be added, depending upon the end-use application of the
coating formulation.
In the ordinary practice of this invention, the
novel polyols of the invention are packaged separately from
the polyisocyanate reactant. These separate components are
admixed and applied to the substrate to be coated while in
the fluid state. The coating can be applied to any acceptable
substrate such as metal, wood, glass, fabrics, leather, glass
reinforced polyester and other plastics. The caprolactone
triol/cycloaliphatic diepoxide adducts are especially useful
in providing urethane top-coatings for aircraft, tank cars,
tank trucks, storage tanks, appliances and boats. The
urethane coating formulations of the invention are applied
to the substrate in conventional manner such as by spraying,
brushing, dipping, roll-coating, or other techniques known
to the art.
As desired, viscosity of the coating formulation
can be reduced by the addition of inert diluents or solvents
conventionally employed for this purpose. Suitable solvents
23.
.
~ 0~ 3 4 9392
include: esters such as ethyl acetate, butyl acetate, and
2-ethoxyethyl acetate (Cellosolve acetate); ketones such as
methyl ethyl ketone and methyl isobutyl ketone; aromatic
hydrocarbons such as benzene, toluene, xylene, mineral
spirits and other aromatic petroleum distillates. Mixtures
or blends of such diluents are also suitably employed. The
coatings may be cured at room temperature or by the appli-
cation of heat up to about 150C., for example, in order to
accelerate the rate of curing and drying, that is, removal
of solvent when used.
The caprolactone-polyepoxide adducts of the
invention are also useful in coatings other than urethane
coatings. For example, they can be cured with melamine
resins such as those available under the tradenames Cymel 300,
supplied by American Cyanamid Company, and Resamine X745,
supplied by ~onsanto Company to yield hard, chemically
resistant coatings. Flexibility of such coatings can be
enhanced by the addition of relatively small amounts such
as from about 2 to about 20 weight percent, of a caprolactone
triol and an aliphatic polyisocyanate.
The following examples are offered as illustrative
of the present invention and are not to be construed as
unduly limiting.
For the sake of brevity, designations are used in
the data which follow to denote the materials identified in
the following Table I.
24.
104'~34 9392
TA BLE
Desi~nation ComPosition
Polyol A ..... This is a caprolsctone triol having a
Hydroxyl No. of 560 and an average molecular
weight of 300 (equivalent weight - 100).
It is prepared by the reaction of tri-
methylolpropane as initiator with epsilon-
caprolactone monomer in the presence of
stannous octoate catalyst (0.002 weight
percent, based on weight of total charge),
at a temperature of approximately l90DC.
and a mole ratio of monomer to initiator
of about 1.45:1.
Polyol B ..... This is a decafunctional polyester polyol
prepared from phthalic anhydride and tri-
methylolpropane. This polyol has a Hydroxyl
No. of 230-270 and an average equivalent
weight of 225, and is supplied by Bayer
Aktiengesellschaft under the tradename
Desmophen 650A.
Polyisocyanate A..This is a biuret of 1,6-hexamethylene diiso-
cyanate having a free-NC0 content of 17.12
weight percent and an equivalent weight of
245.3. It is supplied by Bayer Aktien-
gesellschaft under the tradename Desmodur N.
lOA'~4 9392
TABLE I - Continued
Desl~nation ComPositlon
Sllicone A ...... Thls ls a polyslloxane-polyoxyalkylene
block copolymer havlng the average formula,
Me3SlO(Me2Sl0)7 lBuo(c3H6o)l2c3H6siMeo]3siMe3
where Me and Bu represent methyl and butyl,
respectively.
Formulation A ... This ls a commercial alrcraft coating
supplled by U.S. Palnt Lacquer and
Chemical Company as Alumigrlp Alrcraft
Coating System. It is a plgmented, fully
formulated two-package urethane coatlng
based on Polylsocyanate A and modified
Polyol B.
EXAMPLE 1
PreParation of Polvol I
The reaction of this example was carried out in
a four-necked round bottom flask equipped with a mechanical
stirrer, heating mantle, nitrogen sparge tube and condenser.
The reactor was charged with:
(a) 3,4-epoxycyclohexylmethyl (3,4-epoxycyclo-
hexane)carboxylate in an amount of 320.8 grams (based on
purity, 1.13 moles);
(b) Polyol A in an amount of 679.2 grams (2.26
moles); and
26.
,
..
104~1~4 9392
(c) Stannous octoate catalyst in an smount of
0.5 grams, corresponding to 0.05 weight percent of the
combined weight of (a) and (b).
Samples were taken at intervals and analyzed for percent
oxirane content. The reaction mixture was heated at 160C.
for a total reaction time of about 12-13 hours after which
period the oxirane content was nil indicating essentially
complete reaction of the epoxy groups. The product was
discharged from the reactor as a very viscous liquid and,
upon analysis, was found to have a Hydroxyl No. of 362.9 mg.
KOH/gram. The acid number was nil. ~n the basis of its
hydroxyl number and a hydroxyl functionality of six, the
product has a molecular weight of 927.5 or an equivalent
weight of 154.5 (theoretical equivalent weight = 142.0).
The reaction product of this example is referred to herein
as Polyol I.
EXAMPLE 2
PreDaration of PolYol II
Following substantially the same procedure described
under Example 1, the reactor was charged with: Polyol A in
an amount of 2716.7 grams (9.05 moles)j 3,4-epoxycyclo-
hexylmethyl (3,4-epoxycyclohexane)carboxylate in an amount
of 1283.24 grams (based on purity, 4.52 moles); and stannous
octoate catalyst in an amount of 1.0 gram (0.025 weip t
percent, based on total charge). The reaction mixture was
heated to 100C., an additional 1.0 gram of stannous octoate
was added, and the temperature was raised to 160C. After
27.
~ ~ - . - . ~ . - . - .
9392
104;~ 4
allowing to react at 160C. for 13 hours, the reaction
product was cooled, discharged from the reactor and
analyzed. The viscous llquid product had a Hydroxyl No.
of 330 mg.KOH/gram. The acid number of the product was
nil and its color rating (Gardner) was 1Ø Based on
the said hydroxyl number and the presence of six hydroxyl
groups per molecule, the product has an average molecular
weight of 1020 and equivalent weight of 170. In the use
of this polyol product in preparing the urethane coatings
of Examples 7, 8 and 9 below it was assumed that one
hydroxyl group would be sterically hindered and sluggish
to react. Thus, for the purpose of calculating the amount
of this polyol to be reacted with polyisocyanate, the
product was assumed to have five reactive hydroxyl groups,
that is, its equivalent weight was taken as 204 rather
than 170. The product of this example is referred to
herein as Polyol II.
In the examples which follow, the performance of
the above-described Polyols I and II in forming clear and
pigmented urethane coatings on metal substrates was
evaluated. In each example, the polyisocyanate component
of the two-package urethane coating was Polyisocyanate A
identified in Table I above.
The physical properties of the various coatings
include the following and were determined using the
indicated standard procedures:
28.
,
. . -
.
1 0~ 4 9392
Property Test Procedure
Hardness, Sward Sward Hardness Testor
Hardness, Pencil The "leads" of pencils containing
"lead" of different hardnesses
are ground flat, perpendicular
to the axis. The coating is
then scratched with the edge of
the "lead." The hardest pencil
(e.g., H, 2H) which does not
scratch the coating is designated
as the pencil hardness of the
coating.
ImPact Resistance Gardner Impact Testor
Stain Resistance The respective samples are
exposed to iodine and mustard
for 24 hours. The ratings are
visual and on a comparative basis
as follows:
Ratin~ of Stain Resistance
1 - loss of coating 6 ~ color dark
2 ~ loss of adhesion 7 - definite color
3 - color dark, coating 8 - slight color
softened and some
adhesion loss
4 e color d~rk and coating 9 ~ very slight color
softened
5 ~ color very dark lO - virtually no change
29.
~ 4 9392
Adhc~ion Cro~s-h-tch (10 x 10 ~m.)
dhesion u~$ng 3M Company No.
610 Hitsck Tape; 100 - no 1088
of athe~ion to BOND~RITE 37
steel 8ub~ trate.
Abrasion Resistance Taber Abragion (1000 gram weight,
1000 cycles CS-10 wheel); indicate~
weight (mg.) lost during given test.
EXAMPLE 3
Polyol I produced in accordance with Example 1
and Polyisocyanate A identified in Table I were mixed at
an -NC0/-OH equivalent ratio of 1.2/1.0, followed by the
addition of Silicone A in an amount of 0.1 wei8ht percent,
based on the weight of total resin ~olids. The coating
formulation was reduced to spray visco~ity ~20-25 seconds,
No. 2 Zahn cup) with dry CELLOSOLVE acetate. A film having
a thickness of 1-2 mil (dry) was cast with a doctor knife
on BONDERITE 37 steel ~ubstrate. The co~ting, which was
not catal~zed, was cured for 5 minutes at 150C. As a
control, a coating wss prepared in the same manner except
that Polyol A, identified in Table I above, was u~ed in
place of Polyol I. The relative amounts of polyol and
isocyanate reactant~ required to obtain the ^NC0/-OH ratio
of 1.2/1.0, ~8 well a8 physical propertie~ of the re8pective
coatings, are given in Table II whlch follows.
30.
~.
1 0~ 4 9392
TABLE II - Cle-r Coatlnes Cured 5 Mlnut-- at 150-C.
Example No. 3 ~~
Control No. -- K-l
eactants
Polyol I /1/ A /2/
grams 24.16 15.72
Polyisocyanate A, grams 50.0 50.0
ProDertie6 of Coatin~
Hardness, Sward 54 --
Hardness, Pencil 2H 2H
Impact Resistance
~ront, in./lb. 140 100
Reverse, in./lb. 160 120
Stain Resi~tance
Iodine 8
Mustard 9 6
~dhesion 100 lO0
/1/ me 2/l caprolactone triol/diepoxide adduct
of Example l.
/2/ The caprolactone triol identified in Table I.
me data of Table II show that Polyol I of the
invention provided a ureth~ne coating having an overall
combination of propertie6 at least as good as the coating
provided by control Polyol A and that this result was
capable of being achieved employing a considerably lower
ratio of polyisocyanate to polyol than required for Polyol A.
E8~MPLE 4
In ccord~nce wlth th$s example, a coating was
pplied to BONDERITE 37 steel employing Polyol I of
E~-mple I nd Polyi oc~nat ~ ~t an -NC0/-OH equivalent
. . ~
~ 4 9392
ratio of 1.2/1Ø In additlon to Slllcone ~ (0.1 welght
percent, based on total re6in ~olld6), the coatlng formu-
latlon also contained dlbutyltin dllaurate cstaly~t ln an
amount of 0.022 weight percent, based on the weight of
Polyisocyanate A. As a further component and in order to
insure a working pot-life (that is, time to gelation),
acetic acid was added in an amount of one weight percent,
based on Polyisocyanate A. The coating was reduced to
spray viscosity (20-25 seconds, No. 2 Zahn cup) using dry
CELLOSOLVE acetate. A 1-2 mil (dry) film was cast with a
doctor knife onto the steel substrate and was allowed to
cure at room temperature for 19 days. As a control, a
coating was prepared in the same manner (Control Run K-2)
employing Polyol A in place of Polyol I. For the purpose
of comparison, a coating (Comparative Run C-l) was prepared
also employing the procedure and formulation of this example
except that Polyol B, identified in Table I above, was used
in place of Polyol I. The relative proportion of reactants
and physical properties of the re~pective coatings are given
in Table III which follows.
32.
.
. ~
1 04 ~ 93~2
TABLE III - Catalvzed Clear Coatin~s
Example No. 4
Control No. - K-2
Comparative Run No. - - C-l
Reactants
Polyol I /1/ ~ /2/ B /3/
Grams 24.16 15.72 43.6
Polyisocyanate A, gms. 50.0 50.0 50.0
Pot Life, hours 6.33 7.5 ~6
~rying Time, hours 1.33 1.5 1.0
Physical ProPerties
Hardness, Sward 58 44 52
Impact Resistance
Front, in./lb. >160 >160 80
Reverse, in./lb. >160 >160 90
Stain Resistance
Iodine 9 9 9
Mustard 7 8 8
Adhesion 100 100 100
/1/ The 2/1 caprolactone triol/diepoxide adduct
of Example 1.
/2/ The caprolactone triol identified in Table I.
/3/ The polyester polyol identitied in Table I.
The results of Table III further demonstrate that
Polyol I of the invention provides a urethane coating having
an excellent combination of hardness, impact resistance and
stain resistance.
9392
EXAMPLE 5
This example i~ intended to illustrate the per-
formance of the polyols of this invention in providing
pigmented urethane coatings. For this purpose, titanium
dioxide (TiO2, rutilel in the form supplied by E. I. duPont
and Company as R-960) was used as the pigment at 15 percent
pi~ment volume concentration (PVC). Polyol I of Ex~mple 1
W85 combined with the pigment by ball milling in ~ufficient
CELLOSOLVE acetate to afford a suitable grinding rate. The
pigmented polyol and Polyisocyanate A, identified in Table I,
were then mixed at an -NCO/-QH equivalent ratio of 1.2/1Ø
The formulation of thic example al80 contained Silicone A,
dibutyltin dilaurate catalyst and acetic ecid in the re~pective
amounts indicated under Example 4, and was reduced to spray
viscosity (20-25 seconds, No. 2 Zahn cup) using CELLOSOLVE
acetate. The coating was applied to BONDERITE 37 steel
with a doctor knife and cured at room temperature for 14 days.
As a control, a pigmented coating was prepared (Ru~ K-3)
emplcying the formulation and procedure of ehis example
except that Polyol A was employed in place of Polyol I.
For the purpose of comparison, another pigmented coating
wss prepared (Run C-2) folluwing the procedure and using
the formulation of this example except that Polyol B,
identified in Table I, was u~ed in place of Polyol I. As
8 further measure of the efficacy of the polyols of this
invention in forming pigmented urethane coatings, a further
coating wa6 prepared (Comparative Run C-3) using the pig-
34.
1 0 4'~ 9392
mented commercial aircraft coating formulation, identified
in Table I as Formulation A. The physical properties of
these various coatings are given in T~ble IV which follows.
TABLE IV - Pi~mented Coatin~s
Example No. 5
Control Run No. - K-3 - -
Comparative Run No. - - C-2 C-3
Reactants
Formulation - - - A /2/
Polyol I /1/ A /2/ B /2/ --
Polyisocyanate ........ A /2/.......... --
Pot Life, hours 4.9 4.5 ~ 7 ~~
Drying Time, hours 2.6 2.0 1.2 --
Phvsical Properties
Hardness, Sward 30 30 30 54
Impact Resistance
Front, in./lb. 65 130 100 40
Reverse, in./lb. 45 120 80 18
Stain Resistance
Iodine 8 8 7 7
Mustard 8 7 9 9
Adhesion 100 100 100 100
Abrasion Resistance, mg. 44.9 28.4 48.2 48.4
/1/ The caprolactone triol/diepoxide adduct of Example 1.
/2/ Identified in Table I.
1 O~ 43~2
The results of Table IV indlcate that Polyol I
of the invention allows for the formation of pigmented
urethane coatings having an acceptable overall combination
of properties.
EXAMPLE 6
The purpose of this example is to demonstrate the
usefulness of the polyols of this invention in preparing
urethane top coatings for application to external aircraft
surfaces which come into contact with hydraulic fluids.
For this purpose, the pigmented formulation described under
Example 5 was applied to aluminum as the test substrate
instead of steel. Thus, in addition to Polyol I and
Polyisocyanate A ~-NCO/-OH ratio - 1.2/1.0) and the titanium
dioxide pigment, the formulation contained Silicone A (0.1
weight percent, based on the total resin solids), dibutyltin
dilaurate catalyst (0.022 weight percent) and acetic acid
(1.0 weight percent), the latter percentages being based
on the weight of Polyisocyanate A. A control coating
(Run K-4) and a comparative coating (Run C-4) were also
prepared containing the same formulation components except
that Polyol A and Polyol B, respectively, were used in
place of Polyol I. For the purpose of measuring chemical
resistance to hydraulic fluids against that of a coating
applied to aircraft surfaces in commercial practice, a
further comparative coating was prepared based on pigmented
Formulation A (Run C-5) identified in Table I. The respective
coatings were applied to standard aluminum test panels
36.
9392
(Aluminum Alclsd 7075T-6, 2-9/16" x 9") which had been
thoroughly cleaned, wash primed nd prlmed. In e-ch
preparetion, the top coat was reduced to a spray vi6cosity
of 18-20 ~econd6 (No. 2 Zahn Cup) with CELLOSOLVE acetate/
xylene (50/50 weight ratio) and was then spray applied in
a wet cross coat application to 3.0 mils wet (or 1.5-1.7
mil6 dry). The coatings were allowed to cure for 14 days
at room temperature. In addition to water immersion and
cold flexibility te6t6 which each of the costed panels
10 passed, their resistance to the hydraulic fluid SKYDROL 500-B
was evaluated. This hydraulic fluid, which is used in the
aircraft industry, i6 diphenyl 2-ethylhexyl phosphate and
i6 available from Mon6anto Company. The conditions under
which the coatings were 6ub~ected to thi6 hydraulic fluid
are given in Table V as Conditions I, II, III and IV. After
- each condition, the respective psnels were rated visually
for coating changes such as gloss, softening, 1088 of
adhesion and blistering. The results are also given in
Table V which follaws.
37.
'3 ~3 9 i~
o
h ~ O
:~ bn00 ~ O
~_1 OO O ~ ~'
g ~ ~~ 3 ~ ~
~,~ ~o
C ~ ~~ '~,~
O a) ~ Q~
3 33
Q)
~ t
.~ I ,n.n
~~q~ c
c~ ~ 0
_l ~
~d E-l ~bD~ ~0 ~ n3
~q ~ ~ o
o p:;~o 3 ~ ~ o ~ ~
E~~ ~
~q0! ~:) ~ V
~ Q ~ ~ 5 ~ ~ ~ O ~ ~d
U~ ~ o ~
O t ~ V ~ ~
O
~J I c~ o a~
0 ~ ~ '~
,, 5 H c~ o 0~ n3 o E~ ~ E~
o ~ u~ ,~o~ O
O I V L~C~,bO o ~q ~
Q) I ~ ~ n3 o
~ I o O
C~ ~ ~ 'V J~ ~
~rl I ,r,~~J .D J- i~ C O ~ ~ ~
I ~ ~C ~ .''i U~~rl C ~J h 0 ~ '~)
I ~ rl C ~:) V ~d
0 u) _~
~ I ~ c ~ ~ 8 ~ N O O O
~ I H C ~ U ~ j C ~
P. I ~' ~ O-rl VJ V~ ;~ o p, 5 O O
E~ I rl ~ ~ O ~ . a~ 3 ~ J~
v a~ a c~ ~ C ~ C
~ æ ~~ ~ 00 O~ ~ C C ~
O ~ VJ~ ~ o-C C
P. a~ ~ o
O ~ ~ h g g ~0 0
1_1H
H H H H ~1~i b b
C C C C ~ ~ ~
o o o o
o ~ ~ ~ ~ V ~ ~ ~ C C
Z ~Y ~ ~ ~ ~ ~ JJ ~ V
o g g C og g Co~ o~
oo~ ~ U')
38.
1 0~ 4 9392
The result~ of Table V demon~tr-te that Polyol I
of the inv~ntion provideu a urcthane coatlng h4ving xcel-
lent Skydrol reslst-nce.
EXAMPLES 7. 8 and 9
In accordance with these examples, clear and
pigmented two-package urethane coetings were prepared
based on Polyol II of Example 2. The coatings were
reduced to spray viscosity (20-25 seconts, No. 2 Zahn cup)
using CELLOSOLVE acetate, and were applied to rigid metal
substrate6. The components of the respective formulation6
and the curing conditions are given in Table VI below which
also set~-forth physical property data, chemical re6i6tance
and low temperature flexibility of the re6pective coating6.
All tests are ba6ed on coated BONDERITE 37 steel except
for the tests to determine re6i6tance of the coatings to
the hydraulic fluid, SKYDROL 500-B. For the latter purpose,
the coating6 were spray applied to the standard te~t aluminum
panels described under Example 6 following 6ubstantially the
same procedure. The coating6 on the steel sub6trate were
spray applied over unpr~med BONDERITE 37 steel.
39.
9392
lV~ 4
~00 ~ oo , . .
~, j, .
t t
.
o , , .
! ,
. .. . ..
. .
U~OO~ ~ oo oo
0 ~ O
" . . o
C~ ,, j j CU ~
2,~o o ~ ~ ~ 8 ~0 ~ a
~ ~ ~ O
~ 8
~H~j
D ~I c0~ a ~ b P
Q ~ u~a j~b ~ 3~I2~
40.
1 0~ 9392
The results of Table VI 6how that the clear
coatings of Exsmples 7 and 8 exhibited high hardne~s,
good impact resi6tance and excellent adhesion, chem~cal
resistance and low temperature flexibility. Although
the incorporation of pigment (15% PVC) provided a ~ofter
coating (Example 9) of lower impact resi6tance which are
nevertheless of satisfactory value6, the pigmented coating
exhibited the SKYDROL resi6tance and low temperature
flexibility required of commercial sircraft coatings.
Pigmented urethane coatings employing the formu-
lation of Example 9 of Table VI were also subjected to
weatherability test6 in a standard weatherometer ("Atlas
Weather-ometer" Single-Arc Enclosed Carbons). In the6e
tests, the 6ub6trate was BONDERITE 37 steel. After 1000
hours exposure, no discoloration, fading, chalking or
bli6tering was ob6erved. The only change observed during
this period of expo6ure in the Weather-Ometer wa6 a moderate
1066 of glos6. Such coating6 were also subjected to the
following exposures: 100 percent relative humidity at
120F. for 350 hours; water immersion at 100F. for 350
hours; and a 5 percent salt fog at 95F. for 350 hours.
After the indicated period6 of time no effect on the
coating6 wa6 observed.
41.
9392
3 4
EXAMPLE 10
In accordance with this example, 3,4-epoxycyclo-
hexylmethyl (3,4-epoxycyclohexane)carboxylate was rescted
with a trimethylolpropane-initiated poly(eps~lon-caprolactone)
triol having an average Hydroxyl No. of 310 and an average
molecular weight of about 540. The said diepoxide was used
in an amount of 139.2 grams (based on purityJ 0.5 mole) and
the polycaprolactone triol was used in an amount of 525.9
grams (1 mole). The reaction was effected in the presence
of stannous octoa~e catalyst (0.33 grams, 0.05 weight percent
of reaction mixture)J at a temperature of 160C. for 8.5 hOUr6J
following substantially the procedure described under Example 1.
After this period of timeJ the e~oxide content was nil. The
product was a very viscous material (Acid No. e nil) having a
Hydroxyl No. of 243 (theor. e 258)J and an equivalent weight
of 230.9 (theor. ~ 217)J based on an -OH functionality of six.
Reaction of the product of this example with organic polyiso-
cyanates such asJ for exampleJ Polyisocyanate AJ as described
in the foregoing Examples 3~9 also provides polyurethanes
20 which are suitably applied as coatings on flexible or metal
substrates.
It is evident that the caprolactone polyol-poly-
epoxide reaction products of the present invention provide
urethane coatings, both clear and pigmented, having perform-
ance properties exhibiting suitable hardnes~, good weather-
ability and chemical resistance which are particularly
desirable in top coatings for aircraft.
42.
