Note: Descriptions are shown in the official language in which they were submitted.
~4~
The present invention relates to heat curable
polyurethane resin compositions comprising a polyurethane
prepolym~r having blocked isocyanate groups and a curing
agent, to sealants made from such compositions in
combination with one or more fillers, and to methods for
using of such sealants.
Polyurethanes have heretofore been used in the art
for compounding sealants or adhesives for sealing seams or
bonding different substrates. The polyurethanes used were
either two package or one pot systems. In addition to the
need for scphisticated metering and mixing equipment for the
two package systems, the isocyanate containing component
must be kept and stored under anhydrous conditions to avoid
the reaction of atmospheric moisture with the isocyanate
groups, resulting in an unusable product.
A one pot or one package polyurethane system
having the advantage of easy handling is highly desirable in
the sealant industry, and one pot moisture curable
polyurethares having terminal isocyanate groups have been
taught in the art. On exposure to atmospheric moisture,
some of the isocyanate groups react with water to form amino
groups with the evolution of carbon dioxide. The amino
groups further react with other isocyanate groups and lead
to a cure of the polymer.
To protect the isocyana~e containing polyurethane
polymers from moisture, it has been proposed to react the
isocyanate groups with a blocking agent having a single
active hydrogen group which reacts with an equivalent amount
of isocyanate groups. This linkage will be stable at low
temperatures but will disassociate at elevated temperatures
liberating the isocyanate groups. In the deblocked state at
an elevated temperature, this product remains in equilibrium
~.2~
with the blocking agent and is reactive with crosslinking
compounds that it comes in contact with.
The temperature at which the blocked isocyanate
groups will form and will deblock primarily depends upon the
nature of the blocking agent, although other aspects of the
curing reaction also depend on the nature of the crosslinker
available to react with the deblocked isocyanate groups at
deblocking temperatures.
It is the object of the present invention to
develop a one package polyurethane system that is stable at
room temperature and cures by heating at a moderately
elevated temperature. A feature of the present invention is
such a system comprising a polyurethane prepolymer having
oxime-blocked isocyanate groups together with a curing
agent. The polymer system so developed has been compounded
into a sealing compound which is of particular utility for
filling the seams on auto body assemblies. More in
particular, seams filled with such a sealing compound can be
painted over with the high solids acrylic enamel paints now
widely used in the automotive industry and can be cured at
the temperatures used for drying and curing such enamels.
It has been taught in the art and widely described
in the literature that phenol and phenol derivatives can be
used to block the isocyanate groups of polyurethane
prepolymers to eliminate their sensitivity towards reaction
with atmospheric moisture. Single package curable
polyurethane resin compositions containing a polyisocyanate
prepolymer having phenol blocked isocyanate groups are
taught in Bolger U.S. patent 3,886,228, for instance.
Blocking reactions between isocyanates and such phenolic
compounds require heating the reactants at temperatures
ranging from 80CC to 150C. Consequently, these
-- 2 --
~Z~ Z
blocked polyurethane systems need still higher temperature
to deblock and liberate free isocyanate groups available for
crosslinking.
According to the present invention, a branched
liquid polyurethane prepolymer containing terminal
isocyanate groups is reacted withan o~ime so that one -
equivalent of the oxime blocking agent is reacted with one
isocyanate equivalent of the polyurethane material. The
reaction is conveniently carried out with continuous
agitation at room temperature, rather than at an elevated
temperature as is required with phenol blockers, until the
reaction mixture shows no isocyanate groups present on
testing with infrared analysis.
The resulting-reaction product is insensitive to
atmospheric moisture contamination and is not reactive
towards isocyanate-reactive crosslinkers or curing agents at
ambient temperatures. Hence, heat curable compositions
stable at room temperature can now be compounded by adding a
curing agent having at least two active hydrogen groups per
molecule to such a blocked product. Finally, sealants can
be compounded from such a mixture by adding conventional
fillers and other additives to achieve desirable flow
properties and thixotropy.
uch heat curable compositions and sealants can be
cured by heating at temperatures as low as ~5~F for about
30 minutes, or at higher temperatures for shorter times,
because of the deblocking properties of the oxime-blocked
isocyanate prepolymer. curing" in the present
specification and claims refers to the development of a
Shore no hardncss of at least 60-65 it the times and
temperatures indicated.
-- 3 --
8~2
It is a further object of the present invention to
develop sealants comprising such blocked polyurethane pre-
polymers wherein the polymers are branched so that when they
are deblocked by heat they react with the available curing
agent to form a crosslinked thermoset polyurethane network.
Such curing agents can be polyols, polyamines, or polyamines
blocked by reaction with an anhydride. Such blocked poly-
amine products have been widely used as latent hardeners for
epoxy resins. The preparation and use of such blocked poly-
amines is disclosed in U.S. patent 3,639,657 to Moran et al.
The use of such a blocked amine curing agent permits
the incorporation of an epoxy resin into the resin or sealant
composition without affecting the shelf stability of the
epoxy resin. On heating such a mixture of blocked poly-
urethane, epoxy, and blocked amine, the deblocked amine
reacts simultaneously with the deblocked isocyanate groups
as well as with the available epoxy resin to form an inter-
penetrating polyurethane-epoxy copolymer of a kind discussed
by Frisch et al. in Modern Plastics, May, 1977, p. 8~.
The isocyanate terminated polyurethane polymers
of the invention are prepared by the reaction of an organic
polyisocyanate with a polyhydroxy compound. If part or all
of the polyhydroxy compound has a hydroxy functionality or
more than two hydroxy groups per molecule, the polyurethane
reaction product is not linear but branched. When later
crosslinked, such a branched polymer develops a thermoset
polyurethane (elastomeric) character.
In this reaction, the polyisocyanate is employed
in excess so that the resultant polymers have isocyanate
terminals.
The polyols that may be used are the same as those
commonly employed in the prior art for preparing polyurethane
- 4 -
~.2~-~r~
resins, e.g. polyester polyols and, particularly, polyether
polyols. The polyester polyols include lactone polyols
prepared by the polymerization of lactones, compounds such
as castor oil, and polyester polyols formed by the reaction
of an alkylene glycol with a dicarboxylic acid, for example.
Polyether polyols may be prepared by forming alkylene oxide
adducts of the polyester polyols and lactone polyols discussed
above, or by the reaction of alkylene oxides with materials
such as castor oil. However, the preferred polyether polyols
are polyoxyalkylene polyols, e.g. polyoxyalkylene diols pre-
pared, for example, by the homopolymerization or copolymeriza-
tion of materials such as ethylene oxide and propylene oxide.
Polyoxyalkylene triols, for example linear compounds having
pendant hydroxy groups or having branched polyether chains,
may also be employed as starting compounds in admixture with
diols.
Further suitable polyols are polyhydroxy polysulfide
polymers of the formula
HO-X-SS(Y-SS)n-X-OH,
wherein X and Y are each divalent aliphatic groups and n has
a value between 1 and 100.
In one embodiment according to the present invention,
some of the polyol compound or mixture of polyols may be re-
placed with water. The water, on reaction with isocyanate,
releases carbon dioxide and forms an amino group. The latter
in -turn reacts with further isocyanate groups to form urea
groups. In this embodiment, up to 25 percent of the equiva-
lents of isocyanate-reactive OH groups contributed by the
polyol may be replaced by an equal number of equivalents of
water. Preferably, the polyol employed in this embodiment
- 5 -
8~
is an aliphatic polyol such as a polyoxyalkylene polyol.
Another embodiment according to the present
invention involves the replacement of some of the polyol
compound with a polyol containing diglycidyl ether groups.
It has heen reported in the literature, e.g. the 25th Annual
Technical Conference, 1970, Reinforced Plastics/Composites
Division, The Society of Plastics Industry Inc., Sec. 3-A,
Page 1, by C.G. Schwarzer, that the reactivity of the
diglycidyl ether of bisphenol A may be increased tenfold by
placing a methylol group in the ortho position adjacent to
the glycidyl ether group. An example of such compound is
dimethylol derivative of Bisphenol A diglycidyl ether group
of the formula
H2C--C~ - CH20~ C~H2 - CH_ OH
The incorporation of such a polyol into the urethane
chain will yield a urethane chain having pendant epoxy groups
which can be crosslinked later with a blocked amine curative.
Such a crosslinked system will comprise a urethane-epoxy
copolymer with the toughness and abrasion resistance pro-
perties of polyurethane elastomers coupled with the properties
of rigidity and strength of crosslinked polyepoxides and their
heat, electrical, and chemical resistance.
The organic polyisocyanates which are reacted in
excess with such polyols for formation of the isocyanate-
terminated polyurethane prepolymers of the present invention
are those taught, for example, in Brode et al. U.S. patent
3,632,577. That is, they are aliphatic, cycloaliphatic,
araliphatic, or aromatic polyisocyanates, suitably di-
- 6 -
~.2~34~
and/or tri-isocyanates. Particularly preferred materials
for use according to the present invention are diphenyl-
methane-4,4'-diisocyanate having aromatic characteristics,
the cycloaliphatic diisocyanate 3-isocyanatomethyl-3,
5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate),
and dicyclohexyl-4,4'-methane diisocyanate. Mixtures of two
or more of these preferred materials are also preferred for
use in the present invention.
As known in the art, the polyols and polyisocyanates
are suitably reacted at a temperature between 0C and 120C,
preferably between 25C and 90C. The reactions are carried
out under an inert atmosphere such as a nitrogen blanket and
under anhydrous conditions. The reaction may suitably be
carried out in the presence of a catalyst. The stannous
salts of carboxylic acid, such as stannous octoate, stannous
oleate, stannous acetate and stannous laurate are known as
catalysts for the formation of urethanes. Also, dialkyltin
dicarboxylates such as dibutyltin dilaurate and dibutyltin
diacetate are known in the ar-t as urethane catalysts, as are
tertiary amines with tin mercaptides. The amount of catalyst
employed is generally between 0.005 and 5% by weight of the
mixture catalyzed, depending on the nature of the isocyanate.
~3~ - 7 -
The polyols employed in this reaction, having two
or more hydroxyl groups, generally have a molecular weight
between about 500 and 6000 and have hydroxy equivalent
weights between 50 and 2000. The preferred polyoxyalkylene
polyols, such as polyoxypropylene, have hydroxy equivalent
weights between 200 and 2000. These materials are reacted
with excess isocyanate until the isocyanate content in the
prepolymer is close to the theoretical value, as determined
hy titrating the free isocyanate groups in a sample of the
prepolymer with dibutylamine. The resulting prepolymers
having terminal isocyanate groups have molecular weights
between about 3000 and about 10000. The preferred
prepolymers have a molecular weight between abo'ut 3000 and
6000 and have a moderate viscosity which facilitates their
further reaction with an oxime blocking agent to produce the
polymer mixtures of zero isocyanate content according to the
present invention.
The oxime blocking agents for the free isocyanate
groups contain an active hydrogen atom which react with the
isocyanate groups at room temperature in an equilibrium
reaction which can be represented as
OCN-R-NCO 2 O = NOH I,___
R"
C = NOCNH~R-NHCON = ¢
R" O o R"
where R is a polyurethane chain and R' and R" taken alone
are hydrogen, aliphatic or aromatic groups, or, taken
together with the carbon atom to which they are attached,
are part of 5- or 6-membered aliphatic or aromatic ring.
At moderately elevated temperatures the reaction
proceeds from right to left generating free isocyanate
groups which react with the curing agent present in the
system.
Oximes useful as blocking agents according to the
invention include acetophenone oxime, -C - CH3; acetone
oxime, CH3-C = NOH; methyl ethyl ketoxime, CH3-f = N-OH;
CH3 C2H5
and cyclohexanone oxime,
OH.
Other oximes which can be used as blocking agents are propyl
aldehyde oxime, formaldoxime, butyl aldehyde oxime,
cyclopentanone oxime, benzophenone oxime, and methyl
isobutyl ketone oxime.
Methyl ethyl ketoxime and cyclohexanone oxime are
preferred for use in the present invention because of the
low deblocking temperature of the blocked compound formed
with these oximes.
In the heat curable compositions and sealants of
the present invention, such blocked polyurethane prepolymers
are combined with an amount of a crosslinking agent such
that there are substantially equivalent numbers of (blocked)
isocyanate groups and active (but possibly blocked) hydrogen
atoms present in the mixtures.
The polyol curing agents which can be used as
crosslinkers for the isocyanates when deblocked by heat are
the same kinds of compounds as are used to manufacture the
polyurethane prepolymer~ These include polyester polyols
and polye~her polyols like those already disclosed earlier
herein as useful for the synthesis of the isocyanate termina-
ted polyurethane prepolymer.
The polyamine crosslinking agents which are mixed
with the blocked prepolymer can be a polyamine or mixture of
polyamines having the active amino hydrogen atoms needed to
crosslink the isocyanate groups after the latter are deblocked
by heat. Examples of such polyamines are 4,4'-methylene bis
(orthochloroaniline), methylene dianiline, methylene bis-2-
methoxyaniline, 2,3,5-trichloro-4,4'-methylene dianiline,
o-phenylene-diamine, m-phenylene diamine, p-phenylene diamine,
2,6-dichloro-p~phenylene diamine, tolylene-2,4-diamine,
tolidine, dianisidine, diphenylether-4,4'-diamine, 4,4'-
diphenyl diamino sulfone, 3,3'-diphenyl diamino sulfone,
naphthalene-1,5-diamine, 2,4-diamino cumene, m-tolylene
diamine, p-chloro-phenylene diamine, o-chloro-p-phenylene
diamine, m-xylylendiamine, 2,4-bis(p-aminobenzyl) aniline,
and aromatic diamines represented by the formula
H2N CR 2
RO= C~-OR
b o
wherein s 3~ C2Hs, C3 9~ C6 13~ 8 17'
-CH(CH3)-(CH2)3-CH3, or -CH2-CH(CH3)2 and R' is -H, -CH3,
-C4Hg or -C6H13- Other suitable amines are the aromatic
diamines represented by the formula:
~2
U
~2
... .. . . . . . . . .
- 10 -
wherein R is -CH3, -C2H5, C3H7, nC4 9, 4 9 2 2
3 2 3~2' C18H37~ or -CH2-cH(c2H5)-(cH -CH
and R~ is -CH3, -C2H5, -C3H7, or iC4 9
amines are aliphatic polyamines such as hydrazine, ethylene
diamine, rimethylene tetramine, diethylene triamine, hexa-
methylene-1,6-diamine, and propylene diamine, and cyclo-
aliphatic polyamines such as 1,3-bis (aminoethyl)
cyclohexane, bis(p-aminocyclohexyl) methane, and
3-aminomethyl-3,5,5,-trimethylcyclohexyl amine (isophorone
diamine).
A further group of amine curing agents are the
blocked polyamines obtained by the reaction of approximately
equimolecular amounts of an anhydride selected from the
group consisting of phthalic anhydride, hexahydrophthalic
anhydride, tetrahydrophthalic anhydxide, methyltetrahydro-
phthalic anhydride, polyazelaic anhydride, succinic
anhydride, and dodecenylsuccinic anhydride with a polyamine
selected from the group consisting of ethylene diamine,
diethylene triamine, triethylene tetramine, l,3-diamino-
propane, 1,6-diaminohexane, imino bis(propylamine) and
methyl imino bis(propylamine) at a temperature from about
50~C to about 160C in a non-aqueous medium as described
in Moran et al. U.S. Patent 3,639,657.
The blocked polyamine curing agent preferred for
use in he present invention is the reaction product of
phthalic anhydride and diethylene triamine.
For formulating seam sealant compositions t the
mixtures of polymer and curing agent of the invention are
combined with fillers and additives known in the prior art
for use in elastomeric composit.ions. By the addition of
such materials, physical properties such as viscosity, flow
8~
rate, sag, and the like can be modified. However, to
prevent premature reaction of the moisture sensitive
isocyanate groups of the polymer after deblocking, the
filler used should not contain an excessive amount of
moisture. Exemplary filler materials and additives include
materials such as carbon black, titanium dioxide, clays,
calcium carbonate, surface treated silicas, ultraviolet
stabilizers, antioxidants, and the like. This list,
however, is not comprehensive and is given merely as
illustrative.
A better understanding of the present invention
and of its many advantages will be had by referring to the
following specific examples, given by way of illustration.
EXAMPLE 1
A ketoxime blocked branched polyether urethane
prepolymer was synthesized by blending 642.3g (1.23 eq.) of
a polyoxypropvlene diol commercially available under the
trademark "Pluracol P-1010" average molecular weight about
1,050), 328.3g (2.63 eq.) of 4,4'-diphenyl methane
diisocyanate, and 0.04 g of dibutyltin dilaurate as a
catalyst in a reaction vessel. The mixed ingredients were
heated at 75C for three hours. Then a mixture of 278.3g of
diisodecylphthalate and 5~.3g (0.35 eq.) ox a
polyoxypropylene triol commercially available under the
trademark "Pluracol TP-440" (average molecular weight about
425) were added to the reaction vessel. The whole mixture
was brought to 55C and reacted for 45 minutes. At this
point, the isocyanate content of this reaction mixture was
determined to be 3.4% by weight.
- 12 -
84~
Finally, 92.3g (1.06 eq.) of me+hyl ethyl ketoxime
were introduced and mixing was continued without heating for
about 30 minutes until NCO could not be detected by infrared
analysis. The prepolymer was emptied into a metal
container, degassed, flushed with nitrogen, and stored.
EXAMPLE 2
An epoxy containing polyether urethane prepolymer
blocked with a ketoxime was prepared by thoroughly mixing
196.6g (0.375 eq.) of polyether diol of Example 1, 30.4g
(0.042 eq.) of a diglycidylether containing methylol groups
cor~ercially available under the trademark "Apogen 107"
(weight per epoxide group = 190-205; hydroxy equivalent
weight = 710), 105.0g (0.83 eq.) of 4,4'- diphenylmethane
diisocyanate, 66.0g of butyrolactone, and 0.02g of
dibutyltin dilaurate and heating at 50C until the NCO
content reached 4.1~ by weight.
After the mixture had cooled to room temperature,
37.2g (0.43 eq.) of methylethyl ketoxime were added and
stirring was continued without heating for 30 minutes until
isocyanate groups could no longer be detected by infrared
analysis. The prepoly~er was placed in a metal can,
degassed, flushed with nitrogen, and stored for further
compounding.
EXAMPLE 3
A ketoxime blocked branched polyether urethane prepolymer
was synthesized by blending 642.3g (1.23 eq.) of the
polyether polyol mentioned in Example 1, 126.5g of
butyxolactone, 0.06g of dibutyltin dilaurate, and 349.8g
- 13 -
8~
. .
(2.63 eq.) of a polymeric 4,4'-diphenylmethane diisocyanate
commercially available under the trademark ~PAPI-901" (NCO
equivalent weight = 133) in a reaction vessel and then
heating at 75C for three hours. 50.3g (0.35 eq.) of the
TM
polyether triol 7'Pluracol TP-440" also mentioned in Example
1 were added end the resulting mixture was reacted at 55C
for three hours. The isocyanate content at this point was
determined to be 3.6% by weight.
After cooling to room temperature, a mixture of
95.7g (1.1 eq.) of methyl ethyl ketoxime and 158.lg of
butyrolactone was introduced into the reaction vessel and
stirring was continued at room temperature for 30 minutes
until no isocyanate groups could be detected by infrared
analysis. The resulting ketoxime blocked polyurethane
prepolymer was kept in a metal container under anhydrous
conditions.
EX~IPLE 4
An epoxy containing polyether urethane prepolymer
blocked with a ketoxime was synthesized by combining 943.7g
(1.80 eq.) of the polyetherdiol mentioned in Example 1,
70.4g (0.1 eq.) of the epoxy compound used in Example 2, and
431.4g of butyrolactone with O.lg of dibutyltin dilaurate as
a catalyst and 530.4g ~3.9 eq.) of a polymeric
4,4'-diphenyl-methane diisocyanate commercially available
under the trademark "PAPI-901" (NCO equivalent weight = 133)
and then heating the mixture at 50C for one hour. At this
stage, the NCO content of the mixture in the reaction vessel
was found to ye 3.8% by weight.
178.4g ~2~05 eq.3 of methylethyl ketoxime were
then added to the reaction mixture after cooling to room
- 14 -
8~Z
.
temperature. Stirring was continued for 30 minutes at room
temperature until no isocyanate groups could be detected by
infrared analysis. The blocked polyurethane prepolymer was
stored in a metal can under anhydrous conditions.
EXAMPLE 5
An epoxy containing polyether urethane prepolymer
blocked with a ketoxime was prepared by mixing 1796.8g (1.8
eq.) of a polyoxypropylene diol commercially available under
the trademark "Pluracol P-2010" (average molecular weight
about 2,000), 140.8g (0.02 eq.) of the epoxy compound
mentioned in Example 2, 662.0g of butyrolactone, 532.0g (4.0
eq.) of the polymeric diisocyanate described in Example 3,
and 0.14g of dibutyltin dilaurate as a catalyst.
The mixed ingredients were heated at 50C for 1
hour, cooled to room temperature, and then blocked with
178.4g (2.05 eq.) of methylethyl ketoxime by simply mixing
at room temperature for 30 minutes until isocyanate could no
longer be detected by infrared analysis. This blocked
prepolvmer was filled into a metal can, degassed, flushed
with nitrogen, and sealed.
EXAMPLE 6
A ketoxime blocked branched polyether urethane
prepolymer was synthesized my mixing thoroughly in a
reaction vessel lOOO.Og (1.0 eq.) of the polyoxypropvlene-
diol mentioned in Example 5, 194.4g of butyrolactone, 369.7g
(2.7~ eq.) of the polymeric diisocyanate also mentioned in
Example 5, and 0.08g of dibutyltin dilaurate as a catalyst
and heating at 75~C for 3 hours. The NCO content of the
- 15 -
~2~
reacted mixture was determined to be 4.8% by weight. Then
64.7g (0.45 eq.) of the polyoxypropylene triol of Example 1
TM
("Pluracol TP-440") were introduced into the reaction vessel
and the whole mixture was reacted at 55C for 2 hours until
the isocyanate content of this reaction mixture was 3.4~ by
weight.
The mixture was cooled to room temperature and the
product was then blocked by adding a mixture of 194.4g of
butyrolactone and 120.9g (1.39 eq.) of methyl ethyl ketoxime
and stirring at room temperature. This prepolymer was trans-
ferred into a metal container, degassed, flushed with nitro-
gen, and stored for further compounding.
EXAMPLE 7
106.9g (0.85 eq.) of diphenylmethane 4,4'-
diisocyanate, preheated to a temperature of about 49C, were
introduced into a jacketed reactor under nitrogen. 415.7g
(0.42 eq.) of a polyoxypropylene ether diol (average molecular
weight about 2,000) were added. The mixture was heated to
ahout 82C until it was substantially free of hydroxy groups
but contained about 3.5 percent by weight of unreacted
isocyanate groups, based on the total weight of the reaction
product. The mixture was then cooled to 49C and 189.9g
(0.13 eq.) of a polyoxypropylene ether triol (average
molecular weight about 4,400) were added. Also, 285.0g
of an alkylnaphthalene plasticizer, commercially available
under the trademark "Kenplast G", were also added. Finally
0.06g of stannous octoate as a catalyst was admixed.
The temperature of the mixture was brought to 60C
and the mixture was reacted until the free isocyanate
content of the resulting material was 1.5 percent by weight.
- 16 -
~;~
8~:
The reaction time is generally about 2-3 hours. The
prepolymer was then emptied into a metal container,
degassed, flushed with nitrogen, and stored.
EXAMPLES 8-9
-
400.0g (0.15 eq.) samples of the prepolymer of
Example 7 were respectively reacted with 13.7g (0.157 eq.)
of methyl ethyl ketoxime at room temperature for 30 minutes
(Example 8), and with 17.7g (0.157 eq.) of cyclohexanone oxime
at room temperature for 2.5 hours (Example 9~. The blocked
prepolymers were examined by infrared analysis to make sure
that all isocyanate was fully reacted with the blocking
agents.
EXP~PLE 10
22.5g of an alkylnaphthalene plasticizer,
commercially available under the trademark "Kenplast G",
427.4g of a dialkyl phthalate with mixed C7, Cg, and Cll
linear alkyl groups, and 1125.6g (0.56 eq.) of a polyoxy-
propylene ether triol (average molecular weight about 6,000)
were mixed and heated to 50C in a reaction vessel. 190.4g
(1.4 eq.) of a liquid 4,4' diphenyl methane diisocyanate
(NCO equivalent weight = 135.6) and 0.12 g of dibutyl tin
dilaurate were added and the mixture was stirred. When the
temperature of the mixture reached 60C, 33.7g of diethyl
malonate were introduced. The well mixed mixture was then
cooled to room temperature.
Finally, the cooled reaction mixture was blocked
with 78.3g (0.9 eq.) of methyl ethyl ketoxime at room
temperature for 30 minutes until no isocyanate groups could
be detected by infrared analysis. This reaction product was
packed in a metal container under anhydrous conditions.
EXAMPLE 11
A polyether urethane containing epoxy was prepared
by reacting 874.3g (1.71 eq.) of a polyoxypropylene ether
diol laverage molecular weight about 1,000), 68g (0.095 eq.) of
diglycidyl ether contairling methylol groups commercially avail-
able under the trademark "Apogen 107" (weight per-epoxide =
190-205; hydroxy equivalent weight - 710), and 435.7g of a
dialkyl phthalate plasticizer containing mixed C7, Cg, and
C11 linear alkyl groups with 365.1g (2.67 eq.) of a liquid
polymeric 4,4'- diphenyl metha,ne diisocyanate (NCO eq. wt.
about 136.9) commercially available under the trademark
"PAPI-901" at 50C for 3 hours. The NCO content dropped to
2.1~ by weight.
This reaction mixture was cooled to room
temperature and combined with lOl.9g (0.90 eq.) of
cyclohexanone oxime without heating. Stirring was continued
for 3 hours until no isocyanate groups could be detected by
infrared analysis. The reaction product was placed in a
metal can under anhydrous conditions.
EXAMPEE 12
A ketoxime blocked polyurethane prepolymer having
a polyester structure was synthesized by mixing thoroughly
315.0g (0.32 equivalent) of a polyester diol preheated to
45~C, 88.2g 10.70 equivalent) of molten diphenylmethane-
4,4'-diisocyanate, and 0.02g of stannous octoate as a
- 18 -
8~%
catalyst in a reactor. (The polyester diol is a
condensation product of ethylene glycol with a mixture of
glutaric, adipic, and succinic acids, has an average
molecular weight of about 2,000 and is commercially
available under the trademark "Polyesterol EG 2000".) The
temperature of the mixture was brought to 75C and reacted
for 2-3 hours until the free isocyanate content of the
resulting materials was 3.9~ by weight.
Then 34.7g (0.40 eq.) of methylethyl ketoxime were
added and mixing was continued with heating (to maintain a
low viscosity condition) for 30 minutes until no isocyanate
group could be detected by infrared analysis. The
prepolymer was stored under anhydrous conditions.
EXA:`~P~.E 13
A ketoxime blocked branched polyether urethane
repolymer was prepared by thoroughly mixing 77.2g (0.076
TM
eq.) of the "Pluracol 2010" polyoxypropylene ether
diolmentioned in Example 5, 115.2g (0.076 eq.) of a
polyoxypropylene ether triol (average molecular weight about
4,400), 3.8g of an alkylnaphthalene plasticizer,
ccr~ercially available under the trademark "Kenplast G", and
72.2g of a dialkyl phthalate plasticizer containing mixed
C7, Cg and Cll linear alkyl groups in a reactor and heating
the mixture to about 45C. 42.9g (0.34 eq.) of molten
diphenyl methane-4,4'-diisocyanate and 0.04g of stannous
octoate were introduced. The whole mixture was reacted at
75C for three hours (NCO = 2.56~, cooled to room
temperature, and combined with 17.3g (0.2 eq.~ of methyl
ethyl ketoxime. Stirring was continued for 30 minutes
-- 19 --
without heating until no isocyanate groups could be detected
bv infrared analysis. The blocked prepolymer was stored in
a metal can under anhydrous conditions.
EXAMPLE 14
A ketoxime blocked branched polyether prepolymer
was prepared by thoroughly mixing 273.8 ~0.532 eq.) of
the polyoxypropylene ether diol described in Example 1,
811.0y (0.532 eq.) of a polyoxypropylene ether triol
(average molecular weight about 4,400), and 573.7g of
2-ethylhexyl-diphenyl phosphate plasticizer in a reactor and
heating the batch to about 45C. 268.4g (2.13 eq.) of
molten diphenyl methane-4,4'- diisocyanate and 0.07g of
stannous octoate were then introduced. The whole mixture
was reacted at 75C for 3 hours (at this point, NCO =
2.32). 161.5g (1.19 eq.) of a liauid polymethylene
polyphenyl isocyanate (average NCO equivalent weight =
135.5) and then 200.5g (2.26 eq.) of methyl ethyl ketoxime
were added to this mixture. Mixing was continued for 30
minutes with cooling until no isocyanate could be detected
by infrared analysis. This blocked prepolymer was finally
stored in a metal container under anhydrous condition.
EXAMPLE 15
50.0g of the blocked prepolymer of Example 1 were
mixed with 2.8g of bis(p-aminocyclohexyl)methane and 0.02g
of an antifoaming agent. The mixture could be cured at
250F in 30 minutes to form a smooth film.
- 20 -
EX~IPLE 16
lOO.Og of the prepolymer of Example 4 were mixed
with 19.2g of diocytyl phthalate, 0.04g of an antifoaming
agent, and 11.6g of a diethylene triamine-phthalic anhydride
adduct (a blocXed amine hereinafter indentified as "hardener
A") as described in Example 1 of U.S. patent Jo. 3,~88,742.
The degassed mixture could be cured at 250F in 30 minutes
into a smooth film.
EX~lPLE 17
_ _ _ _
A one package mixture was prepared by blending
lOO.Og of the blocked prepolymer of Example 2, 35.6g of
dioctyl phthalate, and 42.0g of a 41/59 mixture of "Hardener
A" with a liquid epichlorohydrin bisphenol epoxy resin
weight per epoxide = 185-196). this mixture will
hereinafter be identified as "Hardener B".) The mixture was
degassed and applied to a piece of "Bonderite 40" steel
plate. Under curing conditions of 250F for 30 minutes, a
tack-free film was obtained with good adhesion to the
"Bonderite 40" substrate. This mixture was stable after
aging at 130~F for 3 days.
EXAMPLE 18
. = . . _.
A one package mixture was prepared by blending
lOO.Og of the blocked prepolymer of Example 3, 26O4g of
dioctyl phthalate, and 28.4g of blocked amine hardener A.
The degassed mixture gave a tack-free film after baking at
- 21 -
250F for 30 minutes, which film adhered to a "Bonderite 40"
substrate. The liquid mixture remained stable after aging
at 130 F for 3 days.
EXAMPLE 19
Another one package mixture was prepared by mixing
100.0g of the blocked epoxy containing polyether urethane
prepolymer of Example 5, 26.2g of dioctyl phthalate, 27.8g
of blocked amine "Hardener A" and 0.04g of antifoaming agent.
The degassed mixture gave a tack-free film on baking at 250F
for 30 minutes.
EXAMPLE 20
A blocked polyether urethane prepolymer is cross-
linked with a molecule of hydroxy functionality more than
two by mixing 100.0g of the prepolymer of Example 6, 16.4g
of dioctyl phthalate, 0.08g of an antifoaming agent, 0.4g
of dibutyltin dilaurate, and 5.0g of NrN,N',N'-tetrakis
(2-hydroxy propyl)ethylenediamine (hydroxyl equivalent
weight = 73.0). On baking at 250F for 30 minutes, the
degassed mixture produced a smooth tack-free film. This
mixture survived thermal aging at 130F for 3 days.
EXAMPLE 21
100.0g of the prepolymer of Example 8, 15.8g of a
dialkyl phthalate plasticizer, 0.04g of an antifoaming
agent, and 3.0g of isophorone diamine (average molecular
weight = 170.0) were combined. The clear mixture could be
cured into a smooth film by baking at 250F for 30 minutes.
- 22 -
EXAMPLE 22
lOO~Og of the cyclohexane oxime blocked polyetherurethane prepolymer of Example 9 were mixed with 2.2g of m-
xylene diamine. The clear mixture could be cured at 250F
in 30 minutes. It also passed the thermal stability test,
i.e. aging at 130F for 3 days.
EXAMPLE 23
lOO.Og of the blocked prepolymer of Example 10
were mixed with 1904g of the blocked amine/epoxy mixture of
Example 17 Hardener B") along with 0.04g of an antifoaming
agent. The clear mixture survived aging at 130F for 3 days
and cured at 250F in 30 minutes giving a tack-free film.
EXAMPLE 24
.
A sealant was compounded by mixing lOO.Og of the
blocked prepolymer of Example 11 with 20.0g of the "Hardener
8" mixture, 20.0g of a dialkyl phthalate plasticizer (linear
alkyl = C7, Cg and Cll), 4.5g of molecular sieve powder,
98.5g of dried clay, and 0.2g of an antifoaming agent. This
mixture could be cured at 250F in 30 minutes to give a
sealant of 75-80 Shore A hardness.
EXAMPLE 25
A one component mixture was prepared by mixing
50.0g of the methyl ethyl ketoxime hlocked prepolymer of
Example 12 with 5.3g of 2,4-bis(p-aminobenzyl)aniline and
0.04g of an antifoaming agent. the mixture could be cured
a 250F in 30 minutes.
- 23
EX~PLES 26 and 27
Two polyether polyols were used as curing agents
for the methylethyl ketoxime blocked prepolymer of Example
13. They are, respectively, a polyether polyol having a
molecular weight of 590 and an hydroxy functionality of 5.0,
commercially available under the trademark "Niax Polyether
Polyol LA-475" and a polyether polyol having a molecular
weight of 750 and an hydroxy functionality of 5.3,
commercially available under the trademark "Niax Polyether
Polyol ~DE-400". lOO.Og of the prepolymer in Example 13
were mixed with 5.9g of "Niax Polyether Polyol LA-475"
(example 26) or with 7.1g of "Niax Polyether Polyol BDE-400"
(Example 27) in combination with lOO.Og of dried clay and
10.8g of dimethyltin dilaurate catalyst. Each mixture could
be cured completely at 250F in 30 minutes and passed the
storage stability test on agint at 130F for 3 days.
EX~lPLE 28
lOO.Og of the prepolymer of Example 13 or 14 were
blended with lOO.Og of dried clay, 10.8g of dimethyltin
dialaurate, and 9.8g of an adduct prepared from three moles
of diphenyl methane-4,4'-diisocyanate and seven moles of a
polycaprolactone triol of molecular weight 300/ commercially
available under the trademark "Niax Polyol PCP-301". The
mixture could be cured at 250F in 30 minutes and was stable
at 130F for more than 3 days.
This application is a division of Application No.
474,146, filed on February lZ, 1985.
- 24
