Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02212145 2001-03-20
A BLOWING AGENT CONTAINING CATALYST PRECURSOR FOR THE
PREPARATION OF A POLYOL COMPOSITION HAVING GOOD FLOW AND A
RIGID POLYURETHANE FOAM MADE THEREBY HAVING GOOD
DIMENSIONAL STABILITY.
The present application is a division of patent N°
2,132,597 filed on September 21, 1994.
The present invention relates to a blowing agent
containing catalyst precursor for use in a polyol composition
comprised of polyols having certain equivalent weights,
functionalities, and viscosities, a time delayed blow
catalyst, and a time delayed gel catalyst.
In a move to reduce or eliminate ozone-depleting
blowing agents from the manufacture of polyurethane foams,
much effort has gone into investigating the use of water as
a chemically active blowing agent. In situations where one
desires a reaction mixture of the isocyanate and polyol
composition to flow across a mold surface or throughout a
cavity before the onset of a hard gel, using water as a
blowing agent has been found problematic. The isocyanate
reaction with water rapidly develops a high exothermic heat
which causes the isocyanate-polyol reaction to quickly form
polyurethane linkages, with the attendant disadvantage that
the reaction mixture prematurely gels before it can flow
throughout the mold. As a result, water-blown rigid
polyurethane foams made in a mold or a pour behind application
generally exhibit voids and bubbles where the reaction mixture
could not flow.
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CA 02212145 1997-06-OS
This problem is further exacerbated when one desires to make a low density
rigid foam
because more water must be added to lower the foam density, thereby further
increasing the
heat of the exotherm.
Low density rigid foams have an increased tendency toward shrinkage. To avoid
this
problem, crosslinking agents and/or highly functional low molecular weight
polyols are
added to increase the crosslinking density, thereby improving the foam
strength and reducing
shrinkage. By adding crosslinking agents and/or highly functionalized low
molecular weight
polyols to a polyol composition, the flow characteristics of the reaction
mixture suffer
because the viscosity of the system is increased and more active hydrogen
sites are available
for reaction with the isocyanate to form a stiffer gel even more quickly.
Polyol compositions generally have fast acting catalysts to speed up the
isocyanate-
polyol reaction. In an all water-blown system, however, the fast acting
catalysts also
contribute to the poor flow of the reaction mixture by hastening the formation
of a gel.
Using merely a slower acting polyurethane promoting catalyst in an all water-
blown system
does not alleviate the formation of voids because the isocyanate-water
reaction by itself is
hot enough to form a gel front and inhibit the flow of the unreacted reaction
mixture behind
the gel front.
It is known that formic acid can be employed in mixture with water as a
blowing
agent in the manufacture of polyurethane foams with the attendant advantage of
lowering
the foam exotherm to reduce the risk of scorch and fire, as described in
Liessem U.S. Patent
No. 4,417,002. The rigid foams disclosed in this reference, however, are made
with a
catalyst having an active hydrogen or only with gelation catalysts, made with
a polyol known
2
CA 02212145 1997-06-OS
,
', to be of high viscosity, the foams are high density, and/or
only one polyol is suggested for use which, according to the
present invention, is not capable of simultaneously satisfying
all the criteria necessary for good flow while retaining
dimensional stability at low densities.
Other publications, such as JP 04126732 and
JP 71007118-B, also disclose that formic acid may be used as
a blowing agent, but none teach an advantageous combination
of polyols to enhance flow and provide the requisite
dimensional stability; nor do any disclose a catalyst
combination or the type of combinations needed to ensure
proper flow of the reaction mixture. Likewise, JP 03064312
discloses using formic acid as a blowing agent along with a
polyol or polyols satisfying certain criteria to solve
different problems associated with the initial reactivity of
the reaction mixture while maintaining insulation properties.
However, the polyol combination required in the instant
invention as a means to improve flow and maintain dimensional
stability is not addressed or disclosed, nor is the catalyst
combination, designed to work with the polyol component of the
instant invention, taught by this reference.
It is an object of the invention disclosed in the
copending application N° CA 2,132,597 to make a liquid
polyurethane foaming system which exhibits enhanced flow. It
is a further object of the invention to make a rigid
polyurethane foam which is dimensionally stable at low
densities.
It has been found that the flow characteristics of
a liquid polyurethane foaming system for the manufacture of
rigid polyurethane foams are vastly improved when a specific
polyol component is employed to react with an organic aromatic
polyisocyanate in the presence of blowing agents.
The invention as claimed herein is directed to a
3
CA 02212145 1997-06-OS
blowing agent containing catalyst precursor consisting
essentially of:
a) a blowing agent comprising formic acid, or a
mixture of formic acid and water;
b) a tertiary amine blowing catalyst fully
blocked with an organic carboxylic acid; and
c) a tertiary amine gel catalyst fully blocked by
an organic carboxylic acid;
wherein the total number of carboxylic acid group equi
l0 valent including the carboxylic acid groups blocking in
the - C - ~- form, is greater than 1.0 per amino group.
It has been found that the specific polyol component
. . . . , , _ _ _ _ _ __ _ -. . ....... ,-..,~ ,.""_, ~ ; ~. +- i n rr n f
3a
CA 02212145 1997-06-OS
formic acid or a mixture of formic acid and water and of
certain catalysts, further improves the flow characteristics
of the foaming polyurethane system. This polyol component,
along with the formic acid containing blowing agent and
certain catalysts, advantageously permits one to control the
reaction profile such that prior to the onset of a high
exotherm and a firm gel, the liquid polyurethane foamable
system maintains a sufficiently low viscosity enabling, with
the aid of the blowing action of at least one of the blowing
agents present, to exhibit enhanced flow characteristics. An
unexpected advantage of the polyol composition/blowing agent
package is that the rigid foams produced therefrom possess
excellent dimensional stability at low densities. Further
advantages of the invention include more efficient blowing
action which, in turn, reduces the amount of isocyanate and
blowing agent needed to produce a foam of equivalent density
to an all water-blown or a physically active blown
polyurethane foam.
Fsr~e' Descr~Dt~on of the Drawino
Figure 1 is a graphical comparison of the heat
generated by an all water-blown polyurethane reaction with the
heat generated by a formic acid/water blown polyurethane
reaction.
Detailed Description of the Invention
In one inventive feature, a polyol composition has
been developed which exhibits good flow characteristics in a
reaction with an organic isocyanate and in the presence of
blowing agents. The polyol composition comprises a poly9ol
component. In the polyol component there must be present:
4
CA 02212145 1997-06-OS
a) a polyoxyalkylene polyether polyol having a low equivalent weight at or
below
130, a average functionality of 3.1 or greater, and an OH number of 400 or
above to
crosslink the polyurethane chains and promote dimensional stability;
b) a polyoxyalkylene polyether polyol having an average functionality in the
range
from 1.5 to less than 3.1 and a viscosity at or below 800 cP at 25° C
to reduce the
viscosity of the composition and reduce the friability of the foam; and,
c) a polyoxyalkylene polyether polyol having an average functionality greater
than 3.1 and an equivalent weight of greater than 130.
The first criterion (a) requires the use of a polyol having an equivalent
weight
of 130 or less, preferably 120 or less, most preferably 115 or less, with OH
numbers of 400
or higher, preferably 450 or more, most preferably 480 or more, and an average
functionality
of greater than 3.1, preferably 4 or more, most preferably 4.5 or more.
Employing a polyol
having an OH and an equivalent weight within these ranges is necessary to
impart structural
integrity to the foam through crosslinking and to prevent foam collapse. A
polyol having
an equivalent Weight greater than 130 will polymerize with isocyanate to form
a chain
segment tending to be too flexible, and a polyol having an OH number less than
400
possesses insufficient reactive sites relative to the molecular weight of the
polyol to promote
a suitable crosslinking density. The structural strength of the foam becomes a
major
consideration in the manufacture of low density foams which tend to collapse
or shrink
under aging conditions.
Many polyols satisfying criterion (a) possess high viscosities due to their
high hydroxyl
numbers and low equivalent weights. A polyol composition with high viscosities
will have
S
CA 02212145 1997-06-OS
great difficulty flowing throughout a mold before the polyol-isocyanate
reaction mixture gels.
Once the urethane gels to form a hard matrix, the reaction mixture behind the
gel front
proceeds forward only with great difficulty or is substantially prevented from
flowing across
the gel front to fill the remaining portions of the mold. As the blowing agent
gases are
released from the reaction mixture trapped behind the hard gel, a localized
pressure build-
up forms in this area creating large, uneven cell structures or voids in the
foam.
The flow characteristics of the reaction mixture in this invention are
improved
through a physical modification to the viscosity of the polyol component; and
further
improved through formulating the composition to contain certain blowing agents
and
catalysts, which is chemical modification to the polyol composition. The
physical
modification to the viscosity of the polyol component is accomplished by
adding a
polyoxyalkylene polyether polyol having a viscosity of 800 cP or less,
preferably 550 cP or
less, at 25°C to the polyol component, thereby improving the flow of
the polyol component,
the polyol composition, and the reaction mixuture of the polyol composition
and the
isocyanate. 5uc~ a polyol preferably has a low functionality ranging from 1.8
to less than
3.1, but preferably ranges from 1.9 to 2.1. These low functional polyols of
low viscosity also
greatly contribute toward reducing the surface friability of the low density
foam. The
equivalent weight of such a polyol is not limited so long as the viscosity of
the polyol is 800
cP or less. In general, the low viscosity polyols used in the invention have
equivalent
weights ranging from about 80 to 1500, with preferred ranges from greater than
130 to 750.
The polyol satisfying criterion (c) is a bulk polyol suitable in the
manufacture of rigid
polyurethane foams having an average functionality greater than 3.1 for
strength through
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CA 02212145 1997-06-OS
crosslinking, preferably 3.5 or greater, most preferably 3.9 or greater. This
polyol also has
an equivalent weight of greater than 130, preferably 140 or more so that while
it contributes
to the strength of the foam through crosslinking, it is believed, without
being bound to a
theory, that the longer molecular chains per functional group provide a proper
balance
between the number of hard and soft segments formed in the polymer matrix and
prevent
the foam from becoming too tight. While not critical, it is desired that the
polyol used has
a viscosity of about 10,000 cP or less, preferably about 5000 cP or less, most
preferably
about 3000 cP or less, at 25° C to further assist in reducing the
viscosity of the polyol
composition.
One of the features of the invention lies in a polyol composition having a low
viscosity to promote good flow of the reaction mixture, acheived in large
through use of the
polyol component described above. We have acheived polyol composition
viscosities of
2,000 cPs or less, with 1500 cPs or less being more preferred, and 1000 cPs or
less being
most preferred; at 25 C.
Optimal amounts of polyols used in the polyol component are determined by a
polyol
reaction mixture exhibiting good flow through use of a low viscosity
polyol(s), along with
sufficient crosslinker polyol(s) to render the low density foam stable, and
balanced with bulk
polyol(s) to prevent the foam from becoming friable through an otherwise
excessive amount
of the crosslinker polyol while maintaining structural integrity. In one non-
limiting
embodiment of the invention, the amount of bulk polyol c) ranges from 20
weight percent
to 75 weight percent, preferably 20 weight percent to 40 weight percent, the
amount of
crosslinking polyol a) ranges from 10 weight percent to 50 weight percent,
preferably 20
7
CA 02212145 1997-06-OS
weight percent to 40 weight percent, and the amount of low viscosity polyol
ranges from 20
weight percent to 60 weight percent, preferably 25 weight percent to 45 weight
percent,
based on tile weight of all polyols used in the polyol component. Furthermore,
it is also
preferred that the total amount by weight of low viscosity polyol(s) (b) is
greater than or
equal to the total amount by weight of crosslinking polyol(s) (a) as it is
believed that
optimal flow characteristics and foam stablility can be attained by this
ratio.
Suitable polyols used in the polyol component are the polyoxyalkylene
polyether
polyols, which is meant herein to include conventional polyoxyalkylene
polyether polyols,
~ well as tile polymer modified polyoxyalkylene polyether polyols. Polyester
polyols and
polyether polyester polyols may advantageously be admixed with the polyether
polyols to
promote improved adhesion of the foam to substrates, so long as the criteria
a) - c) with
respect to the polyoxyalkylene polyether polyols are satisfied. Since one of
the advantages
of the polyol composition of the invention lies in its low viscosity, it is
preferred that the
amount of polyester based polyols admixed not raise the viscosity of the
polyol composition
beyond about 2,000 cPs at 25 C.
Suitable polyester polyols include those obtained, for example, from
polycarboxylic
acids and polyhydric alcohols. A suitable polycarboxylic acid may be used such
as oxalic
acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid,
suberic acid, azelaic
acid, sebacic acid, brassylic acid, thapsic acid, malefic acid, fumaric acid,
glutaconic acid, a-
hydromuconic acid, B-hydromuconic acid, a-butyl-a-ethyl-glutaric acid, a,a-
diethylsuccinic
acid, isophthalic acid, therphthalic acid, phthalic acid, hemimellitic acid,
and 1,4-
cyclohexanedicarboxylic acid. A suitable polyhydric alcohol may be used such
as ethylene
8
CA 02212145 1997-06-OS
glycol, propylene glycol, dipropylene glycol, trimethylene glycol, 1,2-
butanediol, 1,5-
pentanediol, 1,6-hexanediol, 1,7-heptanediol, hydroquinone, resorcinol
glycerol, glycerine,
1,1,1-trimethylol-propane, 1,1,1-trimethylolethane, pentaerythritol, 1,2,6-
hexanetriol, a-methyl
glucoside, sucrose, and sorbitol. Also included within the term "polyhydric
alcohol" are
compounds derived from phenol such as 2,2-bis(4-hydroxyphenyl)-propane,
commonly known
as Bisphenol A.
Those which satisfy criteria (a)-(c) are polyoxyalkylene polyether polyols
which are
the polymerization products of alkylene oxides with polyhydric alcohols. Any
suitable
alkylene oxide may be used such as ethylene oxide, propylene oxide, butylene
oxide, amylene
oxide, and mixtures of these oxides. The polyoxyalkylene polyether polyols may
be prepared
from other starting materials such as tetrahydrofuran and alkylene oxide-
tetrahydrofuran
mixtures; epihalohydrins such as epichlorohydrin; as well as aralkylene oxides
such as styrene
oxide.
The alkylene oxides may be added to the initiator, individually, sequentially
one after
the other to fo;m blocks, or in mixture to form a heteric polyether. The
polyalkylene
of ether of lols ma have either rims or seconds h dro rou s. It is referred
that
P Y P Y Y P ry ry Y xYg P P
at least one of the polyols, more preferably all of the polyols which satisfy
criteria a) - c) are
polyether polyols terminated with a secondary hydroxyl group through addition
of, for
example, propylene oxide, and moste preferably containing solely
polyoxypropylene groups.
Suitable polyols also include, however, those terminated with ethylene oxide
in the amount
from 1 to 30 weight percent. Included among the polyether polyols are
polyoxyethylene
glycol, polyoxypropylene glycol, polyoxybutylene glycol, polytetramethylene
glycol, block
9
CA 02212145 1997-06-OS
copolymers, for example combinations of polyoxypropylene and polyoxyethylene
poly-1,2-
oxybutylene and polyoxyethylene polyols, poly-1,4-tetramethylene and
polyoxyethylene
polyols, and copolymer polyols prepared from blends or sequential addition of
two or more
alkylene oxides. The polyalkylene polyether polyols may be prepared by any
known process
such as, for example, the process disclosed by Wurtz in 1859 and ~ncvclo~edia
of Chemical
Technolo~y, Vol. 7, pp. 257-262, published by Interscience Publishers, Inc.
(1951) or in U.S.
Pat. No. 1,922,459.
Suitable initiator molecules include those disclosed above for the preparation
of the
polyester polyols. Other initiators include aromatic amines such as aniline, N-
alkylphenylene-diamines, 2,4'-, 2,2'-, and 4,4'-methylenedianiline, 2,6- or
2,4-toluenediamine,
vicinal toluenediamines, o-chloro-aniline, p-aminoani(ine, 1,5-
diaminonaphthalene,
methylene dianiline, the various condensation products of aniline and
formaldehyde, and the
isomeric diaminotoluenes; and aliphatic amines such as mono-, di, and
trialkanolamines,
ethylene diamine, propylene diamine, diethylenetriamine, methylamine,
triisopropanolamine,
1,3-diaminopro~ane, 1,3-diaminobutane, and 1,4-diaminobutane. Preferable
amines include
monoethanolamine, vicinal toluenediamines, ethylenediamines, and
propylenediamine.
Preferable polyhydric alcohols include trimethylolpropane, glycerine, sucrose,
sorbitol,
propylene glycol, dipropylene glycol, pentaerythritol, and 2,2-bis(4-
hydroxyphenyl)-propane
and blends thereof. The polyols satisfying component b) are preferably
initiated with
dihydric alcohols, and further oxyalkylated solely with propylene oxide.
Suitable polyhydric polythioethers which may be condensed with alkylene oxides
include the condensation product of thiodiglycol or the reaction product of a
dicarboxylic
CA 02212145 1997-06-OS
acid such as is disclosed above for the preparation of the hydroxyl-containing
polyesters with
any other suitable thioether polyol.
The hydroxyl-containing polyester may also be a polyester amide such as is
obtained
by including some amine or amino alcohol in the reactants for the preparation
of the
polyesters. Thus, polyester amides may be obtained by condensing an amino
alcohol such
as ethanolamine with the polycarboirylic acids set forth above or they may be
made using
the same components that make up the hydroxyl-containing polyester with only a
portion
of the components being a diamine such as ethylene diamine.
polyhydroxyl-containing phosphorus compounds which may be used include those
compounds disclosed in U.S. Pat. No. 3,639,542. Preferred polyhydroxyl-
containing
phosphorus compounds are prepared from alkylene oxides and acids of phosphorus
having
a P205 equivalency of from about 72 percent to about 95 percent.
Suitable polyacetals which may be condensed with alkylene oxides include the
reaction produce of formaldehyde or other suitable aldehyde with a dihydric
alcohol or an
alkylene oxide such as those disclosed above.
I
Suitable aliphatic thiols which may be condensed with alkylene oxides include
alkanethiols containing at least two -SH groups such as 1,2-ethanedithiol, 1,2-
propanedithiol,
1,2-propanedithiol, and 1,6-hexanedithiol; alkene thiols such as 2-butane-1,4-
dithiol; and
alkene thiols such as 3-hexene-1,6-dithiol.
Also suitable as the polyols (a)-(c) are polymer modified polyols, in
particular, the
so-called graft polyols. Graft polyols are well known to the art and are
prepared by the in
situ polymerization of one or more vinyl monomers, preferably acrylonitrile
and styrene, in
11
CA 02212145 1997-06-OS
the presence of a polyether polyol, particularly polyols containing a minor
amount of natural
or induced unsaturation. Methods of preparing such graft polyols may be found
in columns
1-5 and in the Examples of U.S. Patent No. 3,652,639; in columns 1-6 and the
Examples of
U.S. Patent No. 3,823,201; particularly in columns 2-8 and the Examples of
U.S. Patent No.
4,690,956; and in U.S. Patent No. 4,524,157.
Non-graft polymer modified polyols are also suitable, for example, as those
prepared
by the reaction of a polyisocyanate with an alkanolamine in the presence of a
polyether
polyol as taught by U.S. Patent 4,293,470; 4,296,213; and 4,374;209;
dispersions of
polyisocyanurates containing pendant urea groups as taught by U.S. Patent
4,386,167; and
polyisocyanurate dispersions also containing biuret linkages as taught by U.S.
Patent
4,359,541. Other polymer modified polyols may be prepared by the in situ size
reduction
of polymers until the particle size is less than 20~m, preferably less than
10~m.
The polyol composition further comprises a blowing agent comprising formic
acid or
a mixture of formic acid and water.
The blowing agent employed in the manufacture of the low density rigid
polyurethane
foams herein comprises at least formic acid. Formic acid upon contact with an
isocyanate
group reacts to initially liberate carbon monoxide and further decomposes to
form an amine
with a release of carbon dioxide. Aside from its zero ozone depletion
potential, a further
advantage of using formic acid is that two moles of gas are released for every
mole of
formic acid present, whereas a water-isocyanate reaction results in the
release of only one
mole of gas per mole of water. In both water-isocyanate and formic acid-
isocyanate
12
CA 02212145 1997-06-OS
reactions, the isocyanate is consumed and one must add a proportionate excess
of isocyanate
to compensate for the loss. However, since formic acid is a more efficient
blowing agent
than water, the moles of formic acid necessary to produce the same moles of
gas as a water-
isocyanate reaction is greatly reduced, thereby reducing the amount of excess
isocyanate and
leading to a substantial economic advantage. The amount of isocyanate needed
to make
an equivalent density foam is 5 to 30 weight percent less when one employs
formic acid or
mixtures thereof over an all water-blown formulation.
A further advantage of using formic acid in the polyol composition of the
invention
is its contribution of the improved flowability of the reaction mixture.
Without being bound
to a theory, it is believed that the formic acid-isocyanate reaction proceeds
in the following
two-step reaction:
R-N =C + HO-C -H -= R-N -C ~
0
~' C
0
H O -CO2
--' R-NH2
I
H
13
CA 02212145 1997-06-OS
It is believed that liberation of carbon monoxide and subsequently carbon
dioxide in
the above reaction proceeds at a slower rate than the release of carbon
dioxide in a water-
isocyanate reaction for two reasons: a) the anhydride is more stable than the
carbamic acid
formed in a water-isocyanate reaction and, therefore, requires more thermal
energy to
decompose, and b) the above reaction is a two step reaction rather than a one
step reaction
present in a water-isocyanate reaction. We have observed that the reaction
exotherm in a
polyol composition containing formic acid proceeds in a more controlled manner
than in an
all water blown reaction. A comparison of the curves in FIGURE 1 corresponding
to Series
1 and 2 (formulations are set forth in working Example III) containing formic
acid and
water with Series 3 containing only water as the blowing agent indicates that
the peak heat
of reaction in a formic acid-isocyanate reaction is less than that of an all
water blown
reaction; and further that the heat of reaction at any given point in time is
less heat of
reaction at the same point in time in an all water blown reaction. The lower
reaction
temperatures at any give point in time in the formic acid containing polyol
composition of
the invention eo~firms that formic acid leads to a more controlled exotherm.
Measurements taken during the foaming reaction indicates that the gel time and
tack
free time in the formic acid containing polyol composition of the invention is
longer than
the gel and tack free time in an all water blown system. Lower exotherms,
especially at the
onset of the reaction, are significant because the energy driving the reaction
between the
isocyanate and polyols is lowered, thereby enhancing flow and avoiding a rapid
gel front
buildup. In an all water blown system, the reaction between the isocyanate and
water
proceeds quickly and raises the exotherm earlier, thereby promoting a quicker
urethane
14
CA 02212145 1997-06-OS
matrix formation as evidenced by the faster gel time. By contrast, the
polyurethane matrix
formation from the cream to the gel time in the formic acid containing polyol
composition
of the invention does not proceed as quickly due to the lower exotherm at an
equivalent
point in time. The lower exotherm and longer gel times are another factor in
the invention
which allow the reactive mixture to flow further without encountering the fast
setting
urethane matrix in the hotter all water systems.
The formic acid/formate ions in the polyol composition may be supplied by
addition
of formic acid or a mixture of formic acid and soluble salts of formic acid.
Suitable salts
of formic acid include the amine or ammonium salts of weakly base mono, di, or
trialkylamines, including hydrazine, triethylamine, dimethylbenzylamine, and
triethylenediamine. Many of these tertiary amine salts of formic acid act in a
dual capacity
as a source of formate ions for gas production and as a catalyst for the
reaction between
isocyanate and compounds having isocyanate reactive hydrogens. Therefore, it
is possible
to add solely tertiary amine salts of formic acid or any other catalytically
active salt of
formic acid as, the sole source of blowing agent. In this situation, however,
the amount of
tertiary amine salts of formic acid added to the polyol composition is limited
by the
maximum amount of catalyst the system can bear, meaning that if one is relying
solely upon
the formate ions present in the tertiary amine salt of formic acid as the
source of blowing
agent, only a high density foam can be made as between 2 to 20 pcf. If the
tertiary amine
salts of formic acid are added in quantities necessary to provide the sole
source of gas for
the manufacture of a low density foam under 2 pcf while having the improved
flow
characteristics described herein, the corresponding tertiary amine cations
acting as catalysts
CA 02212145 1997-06-OS
in the solution would also be present in such large quantities that the
reaction mixture
would be over catalyzed. Since many of the advantageous features of the
invention lie in
overcoming the problems associated with low density foams, it is preferred
that the formate
ions present in the polyol composition are supplied by the addition of formic
acid or a
mixture of formic acid and a salt of formic acid, rather than solely as
catalytically active
tertiary amine salt; and it is further preferred that the number of formate
ion equivalents
present in the polyol composition from formic acid or a mixture of formic acid
and salts of
formic acid exceed the combined number of catalytically active cationic salt
equivalents and,
if present, other catalytically active tertiary amine equivalents including
fully substituted
amine initiated polyoxyalkylene polyether polyols which can react in situ with
formic acid.
Formic acid does not corrode injection or mixing equipment. The reason for the
lack
of corrosion is not clear, but it is believed that such factors as the fact
that formic acid is
strong reducing agent, the presence of bases such a KOH catalysts used in the
manufacture
of polyols acting as buffers, and the possibility of the formatiori of a
passivation film each
individually or din combination contribute towards preventing corrosion.
Suitable
concentrations'of formic acid are any commercially available, ranging from
about 90% pure
to 100% pure, with the major impurities being water and in some cases acetic
acid
depending upon the source.
To the polyol composition may be added formic acid or a mixture of formic acid
and
salts of formic acid as the sole blowing agent, or one may add a combination
of blowing
agents comprising formic acid (and mixture thereof with its salts) and a
reactive and/or
physically active blowing agent. Examples of reactive blowing agents used in
the formic acid
16
CA 02212145 1997-06-OS
containing polyol composition are water, tertiary alcohols, other 2 to 20
carbon atom mono
or poly carboxylic acids having molecular weights from 70 to 600 and their
amine or
ammonium salts. Preferably, water is used as the additional blowing agent in
the polyol
composition.
Physically active blowing agents contemplated as suitable additives in the
polyol
composition comprise alkanes having 4 to 12 carbon atoms, preferable S or 6
carbon atoms,
such as n-pentane, isopentane, or n-hexane; cycloalkanes having 4 to 6 carbon
atoms
preferable 5 or 6 carbon atoms, such as cyclopentane; linear or cyclic,
saturate or olefinically
unsaturated ethers having 2 to 5 carbon atoms, such as dimethylether,
diethylether,
methylethylether, vinyl methyl or ethyl ether, divinyl ether, and THF;
aliphatic carboxylic
acid esters having a maximum boiling point of 142°C., preferably below
80°C., such as 1-4
carbon acetates and methyl or ethyl formate; aliphatic and/or cycloaliphatic
ketones having
3 to 5 carbon atoms, such as acetone, methyl ethyl ketone, and cyclopentane;
partially
halogenated chlorofluorocarbons having 1 or 2 carbon atoms, such as R22, 8123,
R141b;
perfluorinateds~ l~near or cyclic ethers having 4 to 12 carbon atoms,
preferably 4 to 6 carbon
atoms, such as perfluorodineopyl or ether or perfluoroethyl propyl ether; and
preferably
fluorinated or perfluorinated, advantageously aliphatic or cycloaliphatic
hydrocarbons having
3 to 8 carbon atoms, preference being given to aliphatic or cycloaliphatic,
fluorinated
hydrocarbons having 3 to 6 carbon atoms which are liquid at room temperature
and contain
at least one bonded hydrogen atom and aliphatic or cycloaliphatic,
perfluorinated
hydrocarbons having 4 to 7 carbon atoms.
17
CA 02212145 1997-06-OS
It is preferred, however, that solely chemically active blowing agents are
used in the
polyol compositions, and more preferable is a combination of formic acid and
water,
although formic acid may also be employed as the sole blowing agent.
The amount of blowing agent used is dependent upon the desired density of the
rigid
polyurethane foam. The foam densities may range from 1.0 p.c.f. to 4.0 p.c.f.
taken from
the core of either a free rise rigid polyurethane foam or a packed (molded)
rigid
polyurethane foam. However, a noteworthy advantage of the polyol composition
containing
formic acid is the ability to make low density rigid polyurethane foams which
are
dimensionally stable, whether open celled or closed celled. Therefore, the
preferred core
foam densities range from 1.0 p.c.f. to 1.8 p.c.f., more preferably from 1.1
to 1.6 pcf, most
preferably from 1.1 to 1.5 pcf. The preferred overall densities of foams
packed to 10% by
weight, meaning the percentage by weight of foam ingredients above the
theoretical amount
needed to fill the volume of the mold upon foaming, are from about 1.2 to
about 2.0 pcf,
more preferrably from 1.3 to 1.6 pcf, with the core densities of these 10% by
weight packed
foams advantage4usly being lower than the overall densities by 10% or less,
more preferably
about 8% or less, most preferably about 6% or less. The closer the value
between the
overall density and the core density of a foam packed in a mold, the more
uniform is the
flow of the reaction mixture throughout the mold.
To achieve these densities, suitable amounts of formic acid added in the
polyol
composition , which by this statement includes the weight of formate ions in
salt form if any
are added, range from 3.0 to 15.0 parts by weight (p.b.w.) more greater than
5.0 p.b.w. to
10.0 p.b.w., most preferably from 6 p.b.w. to 8 p.b.w., based on 100 p.b.w. of
the polyol
18
CA 02212145 1997-06-OS
component. Other blowing agents may also be present, and preferably water is
present, but
in any event, the amount of formic acid added as such or in mixture with other
blowing
agents is within the above stated range. The total amount of blowing agent
mixtures is
limited so long as the above stated amounts of formic acid is added and the
foam retains
its dimensional stability and flowability.
As stated above, in a more preferable embodiment, the blowing agent comprises
a
mixture of water and formic acid. By adjusting the ratio of formic acid to
water, one may
advantageously control the open cell content of the rigid foam. Formic acid
tends to close
the cells of the foam, while water tends to open up the foams cells. Formic
acid to water
weight ratios of 1: 0.2 - 0.5 have been found effective in the manufacture of
both open and
closed celled rigid polyurethane foams having free rise core densities within
the range as low
as 1.1 to 1.3 p.c.f., with a weight ratio of 1: 0.4-0.45 being most effective.
The phrase "open
celled" is construed herein as a foam having an open cell content of greater
than 20%, or
conversely, a closed celled content of less than 80%, while a "closed celled"
foam is one in
which the number of open cells, is 20% or less, or conversely the number of
closed cells is
80% or greater, the measurement being taken from a molded foam packed at 10%
over the
theoretical amount required to fill the mold with foam. Suitable amounts of
water in a
mixture of water and formic acid ranges from 0.5 to 5 pbw based on the weight
of the polyol
component, preferably from 2 to 4 pbw. When water is present in an amount of 3
p.b.w.
or more based on 100 p.b.w. of the polyols, the foam is open celled.
Formic acid is readily soluble in water, alcohols, and ethers, including
polyether
polyols. It may be added directly to the polyol to form a polyol composition
along with
19
CA 02212145 1997-06-OS
catalysts and surfactants, or it may be added at the mixhead of impingement
mixing or
rotary mixing polyurethane machines.
The polyol composition may be commercially offered as a mixture of the polyol
component, blowing agent comprising formic acid or a mixture of formic acid
and water, the
catalysts discussed below. Alternately, a supplier may offer the polyol
component along with
a formulation to a molder/producer of foams who may then blend the polyol
component
with a precursor containing blowing agents and catalysts described below. In
another
embodiment of the invention, there is provided the combination of the polyol
component
With a blowing agent comprising formic acid, and more preferably a mixture of
formic acid
and water, as a package to which the molder/producer may blend the catalysts
described
below. Other suitable packages which may be made commercially available are a
polyols-
catalyst combination, polyols-catalyst-surfactant combination, and catalyst-
blowing agent
combination.
The types of catalyst and their combinations were designed for the preparation
of
polyurethane foarps using the polyols meeting criteria (a)-(c) and formic acid
as a blowing
a ent and preferably a formic acid/water mixture as the blowing agent. As
mentioned
g
above, the exotherm developing between a formic acid-isocyanate reaction is
not as high as
a water-isocyanate reaction. Without the rapid increase in temperature, the
polyurethane
matrix does not develop and solidify as quick, and consequently, the reaction
mixture flows
with greater ease than would an all water-isocyanate reaction. Therefore, the
catalysts used
in the invention advantageously employ a time delay feature and comprise a
delayed action
blow catalyst and a delayed action gel catalyst. Blow and gel catalysts are
desirable to
CA 02212145 1997-06-OS
decrease demolding time by accelerating the rate of reaction between the
blowing agent
(formic acid or a mixture of water and formic acid) and the isocyanate in the
case of a blow
catalyst and accelerating the reaction between the polyols and isocyanate in
the case of the
gel catalyst. Using a delayed action feature for the blow catalyst and the gel
catalyst allows
the reaction mixture to flow across the mold surface with greater ease prior
to the onset of
the bulk of catalytic activity.
It is not necessary to provide immediate blowing action with the aid of a blow
catalyst since the formic acid and isocyanate react sufficiently fast out of
the mix-head to
l0 propel the liquid reaction mixture along the mold surface. A non-delayed,
quick-acting blow
catalyst generates a much faster release of gas, which may allow the gases to
escape before
gelation sets in to trap the gases. This would result in a rapid increase in
gas pressure
causing damage to the foam cell structure and decreasing adhesion of the foam
to a
substrate in pour in place applications. It is also not desirable to use a
quick acting gel
catalyst for the reason that a prematurely formed hard gel front hinders the
flow of the
liquid system~~b~hind the front. By employing the delayed action catalysts,
much of the
blowing action and gelation occur after the reaction mixture has flowed a
great distance,
thereby providing a foam having greater uniformity of cell structure, enhanced
adhesion, and
dimensional stability.
To provide a time delay feature to the catalysts empolyed in the invention,
some of
the catalysts may be blocked with an organic carboxylic acid. By a "blocked"
catalyst
compound or tertiary amine compound is meant that the compound may be blocked
with
an organic carboxylic acid prior to admixture with the polyol component or the
compound
21
CA 02212145 1997-06-OS
may be blocked within the polyol component by virtue of mixing an initially
unblocked
compound with the polyol component along with formic acid effectively
resulting in a formic
acid blocked compound. By an "unblocked" catalyst or tertiary amine is meant
that prior
to adding the catalyst compound to the polyol component, it is not blocked
with a carboxylic
acid because its molecular structure provides the time delay required without
the necessity
for blocking with an organic carboxylic acid, although it is possible and even
probable that
blocking to some extent will occur once the unblocked catalyst is added to the
polyol
composition containing formic acid. In those cases where an organic carboxylic
acid is
necessary to impart a time delay feature to the catalyst, commercial
considerations would
lead one to add an unblocked catalyst to the polyol composition containing
formic acid since
the unblocked catalysts are generally not as expensive.
The delayed action blowing catalysts used in the invention are carboxylic acid
blocked
tertiary amines, preferably carboxylic acid blocked tertiary amine ethers.
These delayed
action blowing catalysts are generally thermally activated by the heat of the
exotherm.
Tertiary amine portions of the delayed action blow catalyst have the general
formula:
R1 R
~ \ R a -y-- (R )b -N~ ~ (R5)d
(R2)c~ ~N- ( ?) 8 ~R~
R3 6
22
CA 02212145 1997-06-OS
wherein R1, R3, R4, and R6 are each independently branched or preferably
unbranched Cl - CS alkyl radicals when the corresponding c or d equals zero,
preferably
methyl or ethyl radicals, and R~, R3, R4, and R6 are each independently a
methylene group
when the corresponding c or d is greater than zero;
R2 and RS are branched or preferably unbranched methylene
groups, optimally containing an ether R7 and RB are each
independently branched or unbranched methylene roups;
- N- ~ - (CH2)e
Y is oxygen, or ~ ,or f
R9 R10
preferably oxygen,
R9 and Rlo are each independently a C~ - CS radical; preferably
a methyl or an ethyl radical;
a and b are each independently an integer from 1 to 6,
,preferably 1 to 2;
c and d are each independently an integer from 0 to 6,
preferably 0;
a is an integer from 2 to 4; and
f is an integer from 1 to 3.
Specific examples of tertiary amine blowing catalysts include one or more of
N,N,N,N"-tetramethyl-2,2'-diaminodiethyl ether; N,N,N,'N",N" pentamethyl
diethyl triamine;
N,N,N',N",N"',N"",N"" hydromethyl tetraethyl pentamine; N,N,N',N",N"
pentamethyl
23
CA 02212145 1997-06-OS
dipropylene triamine, 2 dimethyaminoethyl-1,3-dimethylaminopropyl ether; and
N,N-
dimorpholinoethyl ether.
Suitable organic carboxylic acids used to block the tertiary amine blowing
catalyst and
delayed action gel catalysts include mono- or dicarboxylic acids having 1-20
carbon atoms,
such as formic, acetic, propionic, butyric, caproic, 2-ethyl-hexanoic,
caprylic, cyanoacetic,
pyruvic, benzoic, oxalic, malonic, succinic, and malefic acids, with formic
acid being
preferred. The organic acid blocked tertiary amine blowing catalysts are
usually dissolved
in water or organic solvents to avoid separation of the salt as crystals and
the resultant
phase separation. Preferable organic solvents include polyols having 2 to 4
hydroxyl groups
in the molecule, such as ethylene glycol, diethylene glycol, propylene glycol,
dipropylene
glycol, butanediols, 2,6-hexanediol and glycerine. Among the cited compounds
most
frequently used are ethylene glycol, diethylene glycol, propylene glycol,
dipropylene glycol
and 1,4-butanediol.
The tertiary amine blowing catalysts are blocked completely or partially with
an
organic carboxylic acid to yield a respective, fully blocked tertiary amine
salt of the organic
carboxylic acid or a partial salt of the organic carboxylic acid. The amount
of organic
carboxylic acid reacted with the tertiary amine blowing catalyst depends upon
the degree to
which one desires to delay the tertiary amine catalytic activity. However,
since formic acid
blowing agent added to the polyol composition reacts with amine bases, in most
cases the
tertiary amine blowing catalyst will become fully blocked in the polyol
composition even if
initially added to the polyol composition as a partially blocked catalyst.
Nevertheless, the
amount of formic acid added as a blowing agent to the polyol composition may
be
24
CA 02212145 1997-06-OS
sufficiently small that the formic acid forms salts with the amine initiated
polyols, if present,
and may therefore not be available to react with all the tertiary amine
catalyst added. In
this case, if the tertiary amine is only partially blocked it may remain
partially blocked in
the polyol composition. It is contemplated, however, that the tertiary amine
blowing catalyst
will generally be fully blocked within the polyol composition.
The second catalyst provided in the polyol composition or precursor is a
delayed
action gel catalyst designed to increase the reaction rate between the polyols
and isocyanate
and promote dimensional stability. Unlike the delayed action blow catalyst
which must be
blocked with a carboxylic acid to provide its time delay properties, the
delayed action gel
catalyst may, depending upon the structure, be blocked or unblocked and still
provide time
delay. In the blowing agent-catalyst precursor, however, both the blow
catalyst and the gel
catalyst will be fully blocked with an organic acid no matter what the
structure of the gel
catalyst is since the number of carboxylic acid equivalents present in the
precursor mll be
greater than the number of amine equivalents and there are no other basic
entities present
such as amineviriitiated polyether polyols present to ionically bond with the
carboxylic acid.
Suitable delayed action gel catalysts are any tertiary amine catalysts known
in the
polyurethane art to have time delay properties, including alicyclic tertiary
amines and
aliphatic tertiary amines. Unblocked aliphatic tertiary amines with the
following general
formula are well adapted for use in the invention as a delayed action gel
catalyst:
CA 02212145 1997-06-OS
R.3
R~1 \ N I N/ R~5
R~ / ~ R,
2 6
R'
4
n
wherein R~', R2', RS', and R6' are each independently a C~ - CS branched or
unbranched
alkyl radical, preferably methyl or ethyl radical, optionally substituted with
a hydroxyl group.
R3' and R4' are each independently hydrogen or C, - C3 alkyl radicals,
preferably hydrogen;
and n is an integer from 4 to 10, preferably 6 to 8.
Examples of unblocked aliphatic gel catalyst are N,N,N',N' tetramethyl
hexamethylene diamine and N,N' dimethyl - N,N'-diisopropyl
hexamethylenediamine, the
former being preferred.
Other tertiary amine gel catalysts which are useful in the invention are the
organic
acid blocked aliphatic, alicyclic or heterocyclic tertiary amine catalysts
known in the art to
catalyze the isocyanate-polyol reaction. Some of these tertiary amines having
the general
formulas:
26
CA 02212145 1997-06-OS
R'
-~ N R -X
X-R7 ~ ~ t0
R~9
OR
R'
_ ~ -~ p
X R7
R'9
wherein RT and Rlo' are each independently a branched or unbranched C1 to Coo
methylene groups, preferably Cl - C3 methylene groups, or wherein RT and Rlo'
may be
connected to each other to form a closed ring having 2 to 6 carbon atoms
between the
nitrogens; and RB' and R9' are each independently a branched or unbranched C~
to C6
methylene gr~u~s; the bonds across the N or O atoms and the R8' or R9' groups
are single
R" - N-
or double, preferably single; X is hydrogen or
2 0 R",
wherein R" and R"' are each independently a branched or unbranched Cl to Cb
alkyl
radical, preferably a methyl or ethyl radical, and wherein R' and R" may be
optionally
connected to each other through an oxygen or a substituted tertiary nitrogen
to form a
closed ring having 2 to 6 carbon atoms.
Suitable organic acid blocked amine gel catalysts are the acid blocked amines
of
triethylenediamine, N-ethyl or methyl morpholine, N,N dimethylaminoethyl
morpholine, N-
27
CA 02212145 1997-06-OS
butylmorpholine, N,N' dimethylpiperazine, bis- (dimethylamino-alkyl)-
piperazines, 1,2
dimethyl imidazole. Suitable tertiary amines within the invention which must
be blocked
with an organic acid are dimethyl benzylamine, tetramethylethylenediamine, and
dimethyl
cyclohexylamine.
The gel catalyst may be blocked partially or completely preferably completely
with
the same organic carboxylic acids as the blowing catalyst referred to above,
preferably
blocked with formic acid. Further, the gel catalyst may be dissolved in the
same solvents
as used to dissolve the blowing catalyst.
The total amount of blowing catalyst and gel catalyst in the polyol
composition is that
amount by weight effective to accelerate the reaction between the blowing
agent(s)-polyols
and the isocyanate. Generally, the total amount of blowing and gel catalysts
range from 0.1
to 6.0 pbw, preferably 2.0 to 4.0 pbw, based on 100 pbw or the polyol
component.
A cure catalyst is generally employed to shorten tack time and promote green
strength, and the use of such a catalyst is prefered and advisable to assist
in the prevention
of foam shrink~gb. Suitable cure catalysts are organometallic catalysts,
preferably organotin
catalysts, although it is possible to employ metals such as lead, titanium,
copper, mercury,
cobalt, nickel, iron, vanadium, antimony, and manganese. Suitable
organometallic catalysts,
exemplified here by tin as the metal, are represented by the formula: R"Sn[X-
R'-Y]2,
wherein R is a CI-C8 alkyl or aryl group, R' is a Co Cl8 methylene group
optionally
substituted or branched with a Cl-C4 alkyl group, Y is hydrogen or an hydroxyl
group,
preferably hydrogen, X is methylene, an -S-, an -SR2C00-, -SOOC-, an -03S-, or
an -OOC-
group wherein R2 is a C~-C4 alkyl, n is 0 or 2, provided that R' is Co only
when X is a
28
CA 02212145 1997-06-OS
methylene group. Specific examples are tin (I1) acetate, tin (II) octanoate,
tin (II)
ethylhexanoate and tin (II) laurate; and dialkyl (1-8C) tin (IV) salts of
organic carboxylic
acids having 1-32 carbon atoms, preferably 1-20 carbon atoms, e.g., diethyltin
diacetate,
dibutyltin diacetate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin
maleate, dihexyltin
diacetate, and dioctyltin diacetate. Other suitable organotin catalysts are
organotin
alkoxides and mono or polyalkyl (1-8C) tin (IV) salts of inorganic compounds
such as
butyltin trichloride, dimethyl- and diethyl- and dibutyl- and dioctyl- and
Biphenyl- tin oxide,
dibutyltin dibutoxide, di(2-ethylhexyl) tin oxide, dibutyltin dichloride, and
dioctyltin dioxide.
preferred, however, are tin catalysts with tin-sulfur bonds which are
resistant to hydrolysis,
such as dialkyl (1-20C) tin dimercaptides, including dimethyl-, dibutyl-, and
dioctyl- tin
dimercaptides.
Suitable amounts of cure catalyst range from 0.01 to 3.0 pbw, preferably from
about
0.01 to 1.5 pbw based on 100 pbw of the polyol component, with about 1.0 pbw
being all
that is needed to provide a dimensionally stable foam.In one embodiment of the
invention,
there is provided a blowing agent-catalyst precursor which may be
commercialized as a
concentrate, comprising a tertiary amine blowing catalyst fully blocked with
an organic acid,
a tertiary amine gel catalyst fully blocked with an organic acid, and a
blowing agent
comprising formic acid or a mixture thereof wherein the total number of
carboxylic acid
0
group equivalents present in the precursor, including the carboxylic acid
groups in ( ~ .
-c-o
form is greater than 1 per amino group, preferably ranging from 1.25, more
preferably from 1.5, and most preferably from 2 to 20 carboxylic acid
equivalents per amino
group. It is preferred that greater than 90 weight percent, more preferably
greater than 95
29
CA 02212145 1997-06-OS
weight percent, most preferably 100 weight percent, of the organic acid in the
precursor is
formic acid.
The fully blocked blowing and gel catalysts may be blocked with any of the
aforementioned organic carboxylic acids or mixtures thereof, but are
preferably blocked with
formic acid. The precursor may then be proportionately added to the
aforementioned
polyols to form a polyol composition suitable for reaction with an isocyanate
for the
manufacture of low density rigid polyurethane foams having good dimensional
stability. As
mentioned above, it is possible to use as the only source of formic acid the
formic acid
blocking the tertiary amine blowing and gel catalyst, however, this would
require high levels
of catalyst yielding only small amounts by weight of formic acid which would
adversely
impact on the flow characteristics of the foam. Therefore, it is desired that
the blowing
agent containing catalyst precursor contain an excess of organic acid
equivalents per amino
group, and preferably in the proportions and levels desired for use in the
polyol
composition, along with water if a mixture is desired, to avoid further
blending.
In another' embodiment of the invention, there is also provided a formic acid
free
polyol composition comprising the aforementioned polyols along with an
unblocked tertiary
amine blowing catalyst, an unblocked tertiary amine gel catalyst, and other
desired additives
such as water and a surfactant but devoid of formic acid. Formic acid acting
as a blowing
agent may then be added to the formic acid free polyol composition at a later
time in the
desired amounts to form a polyol composition ready for foam preparation. The
added
formic acid will react in situ with any amines present in the polyol
composition, including
CA 02212145 1997-06-OS
the tertiary amine blowing and gel catalysts to form formic acid fully or
partially, preferably
fully blocked tertiary amine blowing and gel catalysts in the polyol
composition.
Other suitable catalysts may optionally be employed in addition to the blocked
blowing and gel tertiary amine catalysts mentioned above. For example, tin
catalysts may
be used to shorten tack time and promote green strength. Suitable organotin
tin catalysts
are tin (II) salts of organic carboxylic acids, e.g., tin (II) acetate, tin
(II) octanoate, tin (I1)
ethylhexanoate and tin (II) laurate, and dialkyltin (IV) salts of organic
carboxylic acids, e.g.,
dibutyltin diacetate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin
maleate, and
l0 dioctyltin diacetate. Preferred, however, are tin catalysts with tin-sulfur
bonds which are
resistant to hydrolysis, such as dialkyltin dimercaptides, including dimethyl-
, dibutyl-, and
dioctyl- tin dimercaptides.
Urethane-containing foams may be prepared with or without the use of chain
extenders and/or crosslinking agents (c), which are not necessary in this
invention to achieve
the desired mechanical hardness and dimensional stability. The chain extenders
and/or
crosslinking ag~rlts used are diols and/or triols having a molecular weight of
less than 400,
preferably from 60 to 300. Examples are dialkylene glycols and aliphatic,
cycloaliphatic
and/or araliphatic diols having from 2 to 14 carbon atoms, preferably from 4
to 10 carbon
atoms, e.g., ethylene glycol, 1,3-propanediol, 1,10-decanediol, o-, m-, and p-
dihydroxycyclohexane, diethylene glycol, dipropylene glycol, and preferably
1,4-butanediol,
1,6-hexanediol, bis(2-hydroxyethyl)hydroquinone, triols such as 1,2,4- and
1,3,5-
trihydroxycyclohexane, glycerol, and trimethylolpropane.
31
CA 02212145 1997-06-OS
Polyurethane foams can also be prepared by using secondary aromatic diamines,
primary aromatic diamines, 3,3'-di- and/or 3,3'-, 5,5'-tetraalkyl-substituted
diaminodiphenylmethanes as chain extenders or crosslinking agents instead of
or mixed with
the above-mentioned diols and/or triols. By the term polyurethane foam as used
herein is
also meant to include polyurethane-polyurea or polyisocyanurate foams.
Examples of secondary aromatic diamines are N,N'-dialkyl-substituted aromatic
diamines, which are unsubstituted or substituted on the aromatic radical by
alkyl radicals,
having 1 to 20, preferably 1 to 4, carbon atoms in the N-alkyl radical, e.g.,
N,N'-diethyl-,
N~N'-di-sec-pentyl-, N,N'-di-sec-hexyl-, N,N'-di-sec-decyl-, and N,N'-
dicyclohexyl-p- and m-
phenylenediamine, N,N'-dimethyl-, N,N'-diethyl-, N,N'-diisopropyl-, N,N'-disec-
butyl- and
N,N'-dicyclohexyl-4,4'-diaminodiphenylmethane and N,N'-di-sec-butylbenzidine.
If aromatic diamines are used, it is best to use those which have at least one
alkyl
substituent in the orthoposition to the amino groups, are liquid at room
temperature, and
are miscible with the polyether polyols. Furthermore, alkyl-substituted meta-
phenylenediami,n~s of the formulae:
Rz NHZ Rz NHz
H2N O R1 and/or O R1
R3 R3 NH2
where R3 and R2 are identical or different and are methyl, ethyl, propyl, or
isopropyl, and
R1 is linear or branched alkyl having 1 to 10 carbon atoms, preferably 4 to 6
carbon atoms,
are useful.
32
CA 02212145 1997-06-OS
Also useful are those alkyl radicals R~ in which the branching point is on the
C1
carbon atom. Specific examples of radicals RI are methyl, ethyl, isopropyl, 1-
methyloctyl,
2-ethyloctyl, 1-methylhexyl, 1,1-dimethylpentyl, 1,3,3-trimethylhexyl, 1-
ethylpentyl, 2-
ethylpentyl, and preferably cyclohexyl, 1-methyl-n-propyl, tert-butyl, 1-ethyl-
n-propyl, 1-
methyl-n-butyl and l,l-dimethyl-n-propyl.
Specific examples of radicals R~ are methyl, ethyl, isopropyl, 1-methyloctyl,
2
ethyloctyl, l-methylhexyl, l,l-dimethylpentyl,1,3,3-trimethylhexyl, l-
ethylpentyl,2-ethylpentyl
and preferably cyclohexyl, 1-methyl-n-propyl, tert-butyl, 1-ethyl-n-propyl, 1-
methyl-n-butyl,
and 1,1-dimethyl-n-propyl.
Examples of suitable alkyl-substituted m-phenylenediamines are 2,4-dimethyl-6-
cyclohexyl-, 2-cyclohexyl-4,6-diethyl-, 2-cyclohexyl-2,36-isopropyl-, 2,4-
dimethyl-6-(1-ethyl-n-
propyl)-, 2,4-dimethyl-6-(1,1-dimethyl-n-propyl)- and 2-(1-methyl-n-butyl)-4,6-
dimethyl-1,3-
phenylenediamine. Preference is given to 1-methyl-3,5-diethyl-2,4- and -2,6-
phenylenediamines, 2,4-dimethyl-6-tert-butyl- , 2,4-dimethyl-6-isooctyl- and
2,4-dimethyl-6-
cyclohexyl-1,3-ph~nylenediamine.
Examples of suitable 3,3'-di- and 3,3',5,5'-tetra-n- alkyl-substituted 4,4'-
diaminodiphenylmethanes are 3,3'-di-, 3,3',5,5'-tetramethyl', 3,3'-di-,
3,3',5,5'-tetraethyl-, 3,3'-
di- and 3,3',5,5'-tetra-n-propyl-4,4'-diaminodiphenylmethane.
Preference is given to diaminodiphenylmethanes of the formula:
R5 RB
HzN O CHI O NHZ
R4 R7
33
CA 02212145 1997-06-OS
where R4, R5, R6, and R7 are identical or different and are methyl, ethyl,
propyl, isopropyl,
sec-butyl or tert-butyl, but where at least one of the radicals must be
isopropyl or secu-butyl.
The 4,4'-diaminodiphenylmethanes may also be used in a mixture with isomers of
the
formulae:
HzN R5 R8
R4 O CH2 O NHS
R7
and/or
H2N R5
R4 ~ -CH2 O R8
R7 ~NH2
where R4, Rs, R6, and R~ are as defined above.
Preference is given to 3,4-dimethyl-3', S'-diisopropyl- and 3,3',5,5'-
tetraisopropyl-4,4'-
diaminodiphenylc~ethane. The diaminodiphenylmethanes can be employed
individually or
in the form of mixtures.
Said chain extenders/crosslinking agents can be used individually or as
mixtures of
identical or different types of compounds.
The amount of chain extender, crosslinking agent or mixture thereof used, if
any, is
expediently from 2 to 20 percent by weight, preferably from 1 to 15 percent by
weight, based
on the weight of the polyols. However, it is preferred that no chain
extender/crosslinker
34
CA 02212145 1997-06-OS
is used for the preparation of rigid foams since the polyether polyols
described above are
sufficient to provide the desired mechanical properties.
If desired, assistants and/or additives (f7 can be incorporated into the
reaction
mixture for the production of the cellular plastics by the polyisocyanate
polyaddition process.
Specific examples are surfactants, foam stabilizers, cell regulators, fillers,
dyes, pigments,
flame-proofing agents, hydrolysis-protection agents, and fungistatic and
bacteriostatic
substances.
Examples of suitable surfactants are compounds which serve to support
homogenization of the starting materials and may also regulate the cell
structure of the
plastics. Specific examples are salts of sulfonic acids, e.g., alkali metal
salts or ammonium
salts of dodecylbenzene- or dinaphthylmethanedisulfonic acid and ricinoleic
acid; foam
stabilizers, such as siloxane-oxyalkylene copolymers and other
organopolysiloxanes,
oxyethylated alkyl-phenols, oxyethylated fatty alcohols, paraffin oils, castor
oil esters,
ricinoleic acid esters, Turkey red oil and groundnut oil, and cell regulators,
such as paraffins,
fatty alcohols~~a~d dimethylpolysiloxanes. The surfactants are usually used in
amounts of
0.01 to 5 parts by weight, based on 100 parts by weight of the polyol
component.
For the purposes of the invention, fillers are conventional organic and
inorganic
fillers and reinforcing agents. Specific examples are inorganic fillers, such
as silicate
minerals, for example, phyllosilicates such as antigorite, serpentine,
hornblendes,
amphiboles, chrysotile, and talc; metal oxides, such as kaolin, aluminum
oxides, titanium
oxides and iron oxides; metal salts, such as chalk, baryte and inorganic
pigments, such as
cadmium sulfide, zinc sulfide and glass, inter alias kaolin (china clay),
aluminum silicate and
CA 02212145 1997-06-OS
coprecipitates of barium sulfate and aluminum silicate, and natural and
synthetic fibrous
minerals, such as wollastonite, metal, and glass fibers of various lengths.
Examples of
suitable organic fillers are carbon black, melamine, colophony,
cyclopentadienyl resins,
cellulose fibers, polyamide fibers, polyacrylonitrile fibers, polyurethane
fibers, and polyester
fibers based on aromatic and/or aliphatic dicarboxylic acid esters, and in
particular, carbon
fibers.
The inorganic and organic fillers may be used individually or as mixtures and
may
be introduced into the polyol composition or isocyanate side in amounts of
from 0.5 to 40
percent by weight, based on the weight of components (the polyols and the
isocyanate); but
the content of mats, nonwovens and wovens made from natural and synthetic
fibers may
reach values of up to 80 percent by weight.
Examples of suitable flameproofing agents are tricresyl phosphate, tris(2-
chloroethyl)
phosphate, tris(2-chloropropyl) phosphate, and tris(2,3-dibromopropyl)
phosphate.
In addition to the above-mentioned halogen-substituted phosphates, it is also
possible
to use inorganic br organic flameproofing agents, such as red phosphorus,
aluminum oxide
hydrate, antimony trioxide, arsenic oxide, ammonium polyphosphate (Exolit~)
and calcium
sulfate, expandable graphite or cyanuric acid derivatives, e.g., melamine, or
mixtures of two
or more flameproofing agents, e.g., ammonium polyphosphates and melamine, and,
if
desired, corn starch, or ammonium polyphosphate, melamine, and expandable
graphite
and/or, if desired, aromatic polyesters, in order to flameproof the
polyisocyanate
polyaddition products. In general, from 2 to 50 parts by weight, preferably
from S to 25
36
CA 02212145 1997-06-OS
parts by weight, of said flameproofing agents may be used per 100 parts by
weight of the
polyols.
Further details on the other conventional assistants and additives mentioned
above
can be obtained from the specialist literature, for example, from the
monograph by J.H.
Saunders and K.C. Frisch, High Polymers, Volume XVI, Polyurethanes, Parts 1
and 2,
Interscience Publishers 1962 and 1964, respectively, or Kunststoff-Handbuch,
Polyurethane,
Volume VII, Carl-Hanser-Verlag, Munich, Vienna, 1st and 2nd Editions, 1966 and
1983.
Suitable organic polyisocyanates (a), defined as having 2 or more isocyanate
~nctionalities, are conventional aliphatic, cycloaliphatic, araliphatic and
preferably aromatic
isocyanates. Specific examples include: alkylene diisocyanates with 4 to 12
carbons in the
alkylene radical such as 1,12-dodecane diisocyanate, 2-ethyl-1,4-
tetramethylene diisocyanate,
2-methyl-1,5-pentamethylene diisocyanate, 1,4-tetramethylene diisocyanate and
preferably
1,6-hexamethylene diisocyanate; cycloaliphatic diisocyanates such as 1,3- and
1,4-cyclohexane
diisocyanate as well as any mixtures of these isomers, 1-isocyanato-3,3,5-
trimethyl-5
isocyanatometh~lcyclohexane (isophorone diisocyanate), 2,4- and 2,6-
hexahydrotoluene
diisocyanate las well as the corresponding isomeric mixtures, 4,4'- 2,2'-, and
2,4'
dicyclohexylmethane diisocyanate as well as the corresponding isomeric
mixtures and
preferably aromatic diisocyanates and polyisocyanates such as 2,4- and 2,6-
toluene
diisocyanate and the corresponding isomeric mixtures 4,4'-, 2,4'-, and 2,2'-
diphenylmethane
diisocyanate and the corresponding isomeric mixtures, mixtures of 4,4'-, 2,4'-
, and 2,2-
diphenylmethane diisocyanates and polyphenylenepolymethylene polyisocyanates
(crude
MDI), as well as mixtures of crude MDI and toluene diisocyanates. The organic
di- and
37
CA 02212145 1997-06-OS
polyisocyanates can be used individually or in the form of mixtures.
Particularly preferred
for the production of rigid foams is crude MD1 containing about 50 to 70
weight percent
polyphenyl-polymethylene polyisocyanate and from 30 to 50 weight percent
diphenylmethane
diisocyanate.
Frequently, so-called modified multivalent isocyanates, i.e., products
obtained by the
partial chemical reaction of organic diisocyanates and/or polyisocyanates are
used.
Examples include diisocyanates and/or polyisocyanates containing ester groups,
urea groups,
biuret groups, allophanate groups, carbodiimide groups, isocyanurate groups,
and/or
urethane groups. Specific examples include organic, preferably aromatic,
polyisocyanates
containing urethane groups and having an NCO content of 33.6 to 15 weight
percent,
preferably 31 to 21 weight percent, based on the total weight, e.g., with low
molecular
weight diols, triols, dialkylene glycols, trialkylene glycols, or
polyoxyalkylene glycols with a
molecular weight of up to 6000; modified 4,4'-diphenylmethane diisocyanate or
2,4- and 2,6-
toluene diisocyanate, where examples of di- and polyoxyalkylene glycols that
may be used
individually or~as mixtures include diethylene glycol, dipropylene glycol,
polyoxyethylene
glycol, polyoxypropylene glycol, polyoxyethylene glycol, polyoxypropylene
glycol, and
polyoxypropylene polyoxyethylene glycols or -triols. Prepolymers containing
NCO groups
with an NCO content of 29 to 3.5 weight percent, preferably 21 to 14 weight
percent, based
on the total weight and produced from the polyester polyols and/or preferably
polyether
polyols described below; 4,4'-diphenylmethane diisocyanate, mixtures of 2,4'-
and 4,4'-
diphenylmethane diisocyanate, 2,4,- and/or 2,6-toluene diisocyanates or
polymeric MDI are
also suitable. Furthermore, liquid polyisocyanates containing carbodiimide
groups having
38
CA 02212145 1997-06-OS
an NCO content of 33.6 to 15 weight percent, preferably 31 to 21 weight
percent, based on
the total weight, have also proven suitable, e.g., based on 4,4'- and 2,4'-
and/or 2,2'-
diphenylmethane diisocyanate and/or 2,4'- and/or 2,6-toluene diisocyanate. The
modified
polyisocyanates may optionally be mixed together or mixed with unmodified
organic
polyisocyanates such as 2,4'- and 4,4'-diphenylmethane diisocyanate, polymeric
MD1, 2,4'-
and/or 2,6-toluene diisocyanate.
To produce the cellular urethane-containing plastics, the organic
polyisocyanate, the
polyols, and, if used, the chain extender and/or crosslinking agents are
reacted in such
amounts that the ratio between the number of equivalents of NCO groups in the
polyisocyanate and the total number of reactive hydrogen atoms in the polyols
and, if used,
the chain extenders/crosslinkers, is from 1:0.85 to 1.25, preferably from
1:0.95 to 1.15. If
the rigid foams, at least in part, contain bonded isocyanurate groups, a ratio
of from 1.4 to
60:1, preferably from 1.5 to 8:1, is usually used.
The rigid foams made from polyisocyanate polyaddition products are
advantageously
produced by the bne-shot process, for example, using reaction injection
moldings or the high
pressure or low pressure method, in an open or closed mold, for example, in a
metallic
mold, or in a pour-in-place application where the surfaces contacting the
reaction mixture
are a part of the finished article.
The starting components may be mixed at from 15° to 90° C,
preferably at from 20°
to 35°C, and introduced into the open or closed mold, if desired under
super-atmospheric
pressure. The mixing, as stated above, can be carried out mechanically by
means of a stirrer
or a stirring screw or under high pressure by the impingement injection
method. The mold
39
CA 02212145 1997-06-OS
temperature is expediently from 20° to 110° C, preferably from
30° to 60° C, in particular
from 45° to 50°C.
The foams of the invention are also suitable in the manufacture of cellular
elastomers. Moldings made from cellular elastomers of this type are used in
the automotive
industry, for example, as headrests, external parts, e.g., rear spoilers and
bumpers, and
internal panelling, and as shoe soles.
The rigid foams produced by the process according to the invention and the
corresponding structural foams are used, for example, in the vehicle industry--
the
l0 automotive, aircraft, and shipbuilding industries-- and in the furniture
and sports goods
industries. They are particularly suitable in the construction and
refrigeration sectors, for
example, as intermediate layers for sandwich elements or for foam-filling
refrigerators,
freezer housings, and picnic coolers.
For pour-in-place applications, the rigid foam may be poured or injected to
form a
sandwich structure of a first substrate/foam/second substrate or may be
laminated over a
substrate to form a substrate foam structure. The first and second substrate
may each be
independently made of the same material or of different materials, depending
upon the end
use. Suitable substrate materials comprise metal such as aluminum, tin, or
sheet metal;
wood, including composite wood; acrylonitrile-butadiene-styrene (ABS) triblock
of rubber,
optionally modified with styrene-butadiene diblock, styrene-ethylene/butylene-
styrene
triblock, optionally functionalized with malefic anhydride and/or malefic
acid, polyethylene
terephthalate, polycarbonate, polyacetals, rubber modified high impact
polystyrene (HIPS),
blends of HIPS with polyphenylene oxide, copolymers of ethylene and vinyl
acetate, ethylene
CA 02212145 1997-06-OS
and acrylic acid, ethylene and vinyl alcohol, homopolymers or copolymers of
ethylene and
propylene such as polypropylene, high density polyethylene, high molecular
weight high
density polyethylene, polyvinyl chloride, nylon 66, or amorphous thermoplastic
polyesters.
Preferred are ABS, HIPS, polyethylene, and high density polyethylene.
The polyurethane foam may be contiguous to and bonded to the inner surfaces of
the
first and second substrates, or the polyurethane foam may be contiguous to a
layer or lamina
of synthetic material interposed between the substrates. Thus, the sequence of
layers in the
composite may also comprise a first substrate/polyurethane foam/layer or
lamina/second
substrate or first substrate/layer or lamina/polyurethane foam/layer or
lamina/second
substrate.
The layer or lamina of layers additionally interposed into the composite may
comprise any one of the above-mentioned synthetic resins which have good
elongation such
as low density polyethylene or low density linear polyethylene as a stress
relief layer or a
material which promotes adhesion between the polyurethane foam and the first
and/or
second substrateiof choice.
When alsynthetic plastic material such as polyethylene having few or no
bonding or
adhesion sites is chosen as the first and/or second substrate as an
alternative to an
adhesion-promoting layer, it is useful to first modify the substrate surface
with a corona
discharge or with a flame treatment to improve adhesion to the polyurethane
foam.
During the foam-in-place operation, the substrates are fixed apart in a spaced
relationship to define a cavity between the first substrate and second
substrate, and
optionally the inner surface of at least one substrate, preferably both,
treated to promote
41
CA 02212145 1997-06-OS
adhesion. This cavity is then filled with a liquid polyurethane system which
reacts and
foams in situ, bonding to the inner surfaces of the first and second
substrates. In the case
of a cooler container, such as a picnic cooler, a thermoformed inner liner
material is
inserted into the outer shell of the cooler, optionally also thermoformed, in
a nested spaced
relationship to define a cavity, which cavity is then filled with a foamed-in-
place
polyurethane foam. In many cases, it is only the polyurethane foam which holds
together
the outer shell and inner liner, underscoring the need for foam dimensional
stability.
The polyurethane cellular products of the invention are rigid, meaning that
the ratio
l0 of tensile strength to compressive strength is high, on the order of 0.5:1
or greater and has
less than 10 percent elongation. The rigid polyurethane cellular products of
the invention
are dimensionally stable, exhibiting little or no shrinkage, even at free rise
core densities of
1.6 or less. In a preferred embodiment, the rigid polyurethane cellular
products of the
invention tested according to ASTM D 2126-87 using core samples of density 1.8
pcf or less
with dimensions of 3" X 3" X 1" and taken from a 10% packed boxes measuring 4"
X 10"
X 10" advantageously have the following dimensional changes at seven (7) days
of exposure:
at 158°F/100 percent RH no more than t 10 percent, more preferably no
more than t 8
percent, most preferably less than t S percent; at 200° F/0.0 percent
RI-i no more than t
7 percent, more preferably no more than t 5 percent, most preferably less than
~ 4 percent;
at -20° F no more than t 10 percent, more preferably no more than t 8
percent, most
preferably no more than t 3 percent.
The flow characteristics of the reaction mixture comprised of the isocyanate
and the
polyol composition are improved over all water-blown reaction mixture.
Preferably, the
42
CA 02212145 1997-06-OS
d
reaction mixture of the invention flows at least 15 percent farther, more
preferably at least
20 percent farther, most preferably at least 25 percent farther than an all
water blown
formulation which differs from the invention with respect to polyol component,
the catalyst
package, or both. The reaction mixture using the polyol composition of the
invention even
exhibits improved flow compared to a formic acid/water co-blown polyol
compositions
reacted with isocyanates which differ with respect to the polyol component or
the catalyst
package, by at least 5% or more, in spite of the fact that formic acid greatly
lowers the
viscosity of polyol compositions in which it appears. When one considers that
dimensionally
stable low density foams (overall density of 1.6 pcf or less) are also hereby
attained, the
results are surprising since reduced viscosity systems do not usually yield
dimensionally
stable foams at low densities.
The rigid polyurethane foams are also advantageously not friable at their
surface in
spite of their low density and the presence of polyols having a high hydroxyl
number and low
equivalent weight. The foams exhibit a surface friability of less than 5
percent when tested
according to A$'f'M C 421, at densities of 2.0 pcf or less, even at densities
of 1.5 pcf or less.
The low surface friability enables the foam to adhere well to substrates.
The following non-limiting experiments were performed to illustrate some of
the
embodiments of the invention. All amounts are in parts by weight unless
otherwise stated.
Polyol A is a sucrose/propylene glycol mixed initiated polyoxypropylene
polyether polyol having an equivalent weight of less than 115,
a nominal OH number of about 570, and a viscosity of about
43
CA 02212145 1997-06-OS
~ l
1,430,000 cP at 25°C, commercially available from BASF
Corporation as Pluracol~ Polyol 240.
Polyol B is a 35/65 weight percent mixture of dipropylene glycol/sucrose
initiated polyoxypropylene polyether polyols having an average
functionality of greater than 3.9, an eqivalent weight of greater
than 140, and a viscosity of about 2100 at 25 C, commercially
available from BASF Corporation as Pluracol~ Polyol 1174.
Polyol C is a vicinal toluenediamine initiated polyoxyethylene
of o ro lene of ether of of havin a functionalit of
P Y xYP PY P Y P Y g Y
greater than 3.5, an equivalent weight of greater than 130
commercially available from BASF Corporation as Pluracol~
Polyol 824.
Polyol D is a propylene glycol initiated polyoxypropylene polyether polyol
having a functionality of about 2, and a viscosity of about 73 at
,, ~ 25° C.
Polyol E is a propylene glycol initiated polyoxypropylene polyether polyol
having a functionality of about 2 and a viscosity of about 150 cP
at 25° C.
Polyol F is a sorbitol initiated polyoxypropylene polyether polyol having
an OH number of 490, a functionality of about 5.4, an
equivalent weight of about 115, and a viscosity of about 4,500
44
CA 02212145 1997-06-OS
,
cP at 25°C, commercially available from Rhone Poulenc as
ALKAPOL SOR-490.
Polyol G is a monoethanolamine initiated propylene oxide ethylene oxide
adduct and having a viscosity of about 500 cP at 25 C, an
equivalent weight of less than 130, and a nominal OH of about
500 commercially available from BASF Corporation as
Pluracolm Polyol 1016.
Iso A is a solvent-free polymethylene polyphenylene polyisocyanate
l0 with a functionality of about 2.7, commercially available from
BASF Corporation as LUPRANATE~ M20S Iso.
Catalyst A is DABCO BL-17, commercially available from Air Products
and Chemical Co., and is a formic acid blocked N,N,N',N'-
tetramethyl-2,2'-diaminodiethyl ether acting as a delayed action
blowing catalyst.
Catalyst B ~~ ~ is N,N,N',N'-tetramethyl-n-hexyl diamine acting as a delayed
action gel catalyst, commercially available from BASF
Corporation or Allied Signal.
Catalyst C is dibutyltin dimercaptide, commercially available from Witco
Corp. as Fomrez UL-1.
Catalyst D is 100 percent bis(N,N-dimethylaminoethyl)ether, the same as
Catalyst A, except that it is not formic acid blocked and is pure,
commercially available from Air Products and Chemical Co.
CA 02212145 1997-06-OS
Catalyst E is pentamethyl-diethylene triamine marketed as Polycat 5
available from Air Products and Chemical Co.
Surfactant A is L-6900, a silicone surfactant commercially available from
Union Carbide.
EXAMPLE 1
Polyols A, B, C, D, and E, Surfactant A, Catalysts A, B, and C were all
thoroughly
mixed together, along with formic acid and water, in the proportions stated
below in Table
1 to form a polyol composition. The Iso A and the polyol composition were
loaded into
to tanks kept at room temperature and attached to a high pressure impingement
mixing
machine. The machine was pressurized to about 2,000 p.s.i. on the resin and
iso sides with
shot times of 2.8 seconds for samples 1-3 and 2.7 seconds for samples 4-6. The
polyurethane
mixture for each sample was poured once into a # 10 Lily cup, a 4" X 10" X 10"
cake box,
and a 4" X 10" X 10" cake box overpacked by a theoretical amount of ten (10)
percent, to
determine the free rise densities of the former two and the overall and core
densities of the
packed box. Other physical properties, including dimensional stability, of
each packed box
sampled in Tables I were tested according to the following ASTM standards and
reported
in Table II.
20 ~ ASTM
Compressive StrengthD 1621
Thermal ConductivityC S 18
Friability C 421
Porosity D 2856
Dimensional StabilityD 2126
46
CA 02212145 1997-06-OS
TAB LE 1
3 4
1 2
SAMPLES
10 10 10 ___
POLYOL A ___ ._.
10 10 10 .._
POLYOL B 30 30 30
50 50 50
POLYOL C 20 20
15 15 15 20
POLYOL D 20 20 20
15 15 15
POLYOL E 30 30
._. 30
POLYOL F
1 1.5 1.5
5
5 1.5 1.5 .
1
CATALYST A . 1 1
1 1 1
CATALYST B 1 1 0.1
0
1 0.1 0.1 0.1 .
0
CATALYST C . 5 1.5 1.5
1
5 1.5 1.5 .
1
SURFACTANT . 7 7
A
(8) 7 7 b
FORMIC AC1D 2 3
2 3 3 2
WATER 1 113.1 114.1
112
113.1 114.1 115.1 .
TOTAL 109 109 109
109 109 109
INDEX
REACTIVITY
IN X10
LILY CUP
7 2.7 2.7
2
FREE RISE SHOT2.8 2.8 2.8 . 6
(s) 2
2.2
1 2.3 2.2 .
2
CREAM 2.0 . 24 26
22 25
25 23
GEL 59 56 b3
68
45 59
RISE 40 36 44
43 40 38
TACK FREE 28 1.23 1.20
1
1.30 1.22 1.16 .
P.C.F. 0 2.8 2.8
3
BOX, FREE RISE3.0 3.0 3.0 .
SHOT
( s ) '. 10'~ 10'.
10"
10.. 10'~ 10
HT. 152.9 143.4 142.9
n 3
136
150.1 140.7 .
WT. 45 1.36 1.36
1
1.43 1.34 1.30 .
P.C.F. NONE NONE NONE
NONE NONE NONE
SHRINKAGE
NONE NONE NONE
SURFACE FRIABIL11YNONE NONE NONE NONE
NONE NONE NONE NONE
CARDBOARD FRIABILITYNONE
GOOD GOOD GOOD GOOD
ADHESION 6000 GOOD GOOD
FAIR GOOD GOOD
NIXING FAIR
10X PACKED
PANELS 35 2.21 2.22
2
3 2.29 2.24 .
2
SHOT (s) . 4 159.0 157.5
168
165.0 156.0 152.5 .
WT (9) 60 1.51 1.50
1
ACTUAL PCF 1.57 1.48 1.45 . 37
(overall) 1
34 1.53 1.44 .
1
ACTUAL PCF 1.44 1.42 . 50
(core) 1
47 1.43 1.60 1.50 .
1
PCF OVERALL 1.57 .
(theor.)
47
CA 02212145 1997-06-OS
TABLE 2
SAMPLES 1 2 3 4 5 b
DENSI1Y ACTUAL
OVERALL 1.57 1.48 1.45 1.b0 1.51 1.50
CORE 1.44 1.42 1.34 1.53 1.44 1.37
COMPRESSIVE STRENGTH
YIELD PT.-PARR. 16.4 17.2 15.9 1T.2 15.6 17.5
X DEFL. tiYfELD 5.1 ~ 11.2 9.0 5.6 5.3 8.9
10X DEFLECTION 16.0 17.2 15.9 17.7 16.1 17.4
MODULUS 411 406 371 414 393 423
_
10X DEFLECTION 3.8 7.3 6.8 6.9 b.7 b.7
MODULUS 41 95 95 124 106 105
K-FACTOR
185 .209 .224 0.187 0.222 0.214
iNlTlAI . ___ -.. 0.217 0.225 0.219
TEN (10) DAYS -'-
FRIABILITY 1.92 1.28 2.88 1.3 0.7 0.T
-- __- 94.2 87.8 69.5
POROSITY --
DIMENS. STABILITY
SSC
150F/100X RH
ONE (1) DAY -12.9 0.0 -0.2 -16.7 5.2 3.2
6 0.2 0.1 -21.2 5.0 3.3
-13
TNO (2) DAYS . 1.4 1.9 -17.4 7.3 4.3
SEVEN (7) DAYS -14.7
200F/OX RN
4
0
ONE (1) DAY -2.8 -0.9 -0.2 -23.3 -8.3 .
TblO (2) DAYS -T.0 -1.4 -0.5 -24.1 -8.3 0.8
SEVEN (7) DAYS ~ -0.0 1.2 -18.1 3.3 1.4
-4.b
-20F
ONE (1) DAY -8.3 0.5 -0.3 -12.7 -8.0 -0.8
Tblo (2) DAYS -9.1 0.8 -0.4 -12.5 -9.0 -1.1
SEVEN (7) DAYS
-7.5 2.4 1.5 -11.2 -7.0 -1.5
48
CA 02212145 1997-06-OS
' t
The results in Table 2 indicate that rigid polyurethane foams having overall
packed
densities of about 1.6 or below, whether open or closed celled, possess good
dimensional
stability at low overall packed densities of 1.6 pcf or less, especially the
rigid foams of
samples 2-3 and 5-6. It is not known why the foams of samples 1 and 4 did not
exhibit
dimensional stabilities as good as the other samples. The numerical proximity
between the
overall and core densities is an indicator of good flow.
EXAMPLE II
The foam ingredients for comparative samples 7-8 listed on Table 3 below were
machine mixed at the stated calibrations, and shot initially to determine
their reactivities.
I
49
CA 02212145 1997-06-OS
T/IHLt
7 8
SAI1PLE
25 25
POLYOL G
75
POLYOL C
1.5 1.5
SURFACTANT A
2.5 2.5
CATALYST E
.__
7.0
FORMIC ACID
7.0 3.0
WATER
111.0 114.0
TOTAL
INDEX
220.30 201.97
ISO A
REACTIVITY
3.0 3.0
SHOT TINE
5.5 3.2
CREAK
28 23
GEL
37
3T
RISE
58 47
TACK FREE
1.57 1.29
X10 LILY CUP PCF
CALIBRATION
63.1 72'1
RESIN
129.0 126.8
ISO 494
438
RPl1 RESIN
~0 750
RPN 1S0
2100 2000
PRESSURE RESIN ~
2000 2000
PRESSURE ISO.
49 0.57
0
RATtO RESIN/100 1 ACTUAL .
50 0.56
0
RAT10 RESIN/100 1 THEORETICAL .
1850 CPS A24.8 3110 CPS A24.8C
VISCOSITY, CPS.
CA 02212145 1997-06-OS
One day after standing in the # 10 Lily cup, the foams in each comparative
sample
pulled away from the sides of the cup after sitting overnight at ambient
conditions,
indicating that the foams would experience extreme shrinkages under humid,
hot, or cold
conditions. The foams were also extremely friable as indicated by their
crunchiness and
inability to stick to the sides of the cardboard cup.
l0 Example III
The foam formulations of samples 1-6 were tested for flowability and compared
against comparative foam formulations which either had no formic acid present
and/or
contained the wrong catalyst/polyol component. The flow of samples 1-8 were
tested by
pouring the machine mixed reaction mixture ingredients into a tube at the
stated shot times
and shot weights in TABLE 4 below and at machine pressures of about 2000
p.s.i. on the
I
resin and iso~~ sides. The length of the resulting foam in the tube was
measured in
centimeters.
51
CA 02212145 1997-06-OS
TABLE 4
SAMPLE 1 2 3 4 S 6 7 8
SHOT 1.25 1.28 1.3 1.28 1.28 1.32 1.35 1.3
TIME (s)
SHOT 101.5 98.6 98.5 102.8 101.7 100.4 95.5 96.2
WEIGHT
'~ (g)
FOAM 180 182 190 187 195 187 140 163
LENGTH
(cm)
The flow results of samples 1-6 show a marked improvement in flow over the all
water blown sample 7, by at least 22% to about 28%. The all water blown sample
7 is a
typical water blown system and does not contain either the catalyst or the
polyol component
as described above, nor does it contain formic acid. Formic acid will help the
flow of the
reaction mixture as shown by sample 8 which flowed 23 more centimeters for a
14%
improvement. However, without the proper polyol component and catalyst, the
flow of
reaction mixture sample 8 even with formic acid was at least 11% less than
samples 1-6.
Thus, the flowability of the above formulations 1-6 made according to the
invention herein
are significantly improved over other formulations which differ in polyols,
catalysts, or
blowing agent.
EXAMPLE IV
The following experiment was conducted to ascertain the exotherm generated by
different foam samples over time. Series 1 and 2 contained different amounts
of formic acid
in the same proportion to water. Series 3 is an all water-blown formulation.
The polyol
52
CA 02212145 1997-06-OS
composition and the isocyanate were added together in a # 10 Lily cup and
stirred for 3
seconds at 1720 rpm using a Jiffy mix blade. A Wahl Heat-Probe thermometer,
Platinum
360X Serial No. P8198 probe was inserted through the cup at about the
midsection to
measure the heat generated during the foaming reaction. The formulatians are
reported
in Table 5, and the results are graphed in Figure 1.
TABLE
SERIES 1 2 3
POLYOL C 30 30 30
POLYOL D 20 20 20
POLYOL E 20 20 20
POLYOL F 30 30 30
CATALYST A 1.5 1.5 ---
CATALYST B 1.0 1.0 0.6
CATALYST C 0.1 0.1 0.1
CATALYST D --- --- 0.6
SURFACTANT A 1.5 1.5 1.5
FORMIC ACI~~e~ 7.0 5.6 ---
WATER 3.0 1.6 7.0
TOTAL 114.10 113.3 109.8
ISO A 184.03 151.82 201.77
INDEX 1.1 1.1 1.1
A discussion on the lower exotherm produced in a formic acid formulation
appears
above. The formulations abouve also indicate that adding formic acid to the
polyol
composition reduces the amount of isocyanate required to achieve an index
equivalent to
53
CA 02212145 1997-06-OS
an all water-blown formulation. The amount of isocyanate required to react
with the polyol
composition of the invention containing formic acid is advantageously 5
percent to 30
percent, more preferably 7 percent to 25 percent less than the amount of
isocyanate
required to react with polyol compositions containing solely water as the
blowing agent at
an equivalent index for the manufacture of rigid polyurethane foams having
free rise
densities of less than 1.6.
54
