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Claims  |
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What is claimed is:
1. A method for preparation of rigid polyurethane foam, comprising mixing
at least two components to form a reaction mixture comprising:
(a) isocyanate,
(b) from about 1% to about 20% by weight CHClF.sub.2,
(c) up to about 2% by weight of water, and
(d) a combination of polyols having an average OH number of from about 300
to about 500 and comprising olyalkoxylated glycerin having an OH number of
from about 200 to about 300 and in which the alkoxy groups each have from
two to about three carbon atoms.
2. A method as set forth in claim 1 wherein said combination of polyols
comprises a first polyol constituent, which comprises a polyalkoxylated
amine having an average OH number of from about 500 to about 700 and in
which the alkoxy groups each have from two to three carbon atoms, a second
polyol constituent, which comprises a sucrose-based polyol having an
average OH number of from about 300 to about 400 and an average
functionality of at least about 3, and a third polyol constituent, which
comprises polyalkoxylated glycerin having an average OH number of from
about 200 to about 300 and in which the alkoxy groups each have from two
to about three carbon atoms.
3. A method as set forth in claim 2 wherein said polyalkoxylated amine is a
polyalkoxylated monoamine and the second constituent of the combination of
polyols of component B further comprises an additional polyol selected
from the group consisting of ethylene glycol based polyols and glycerin
based polyols.
4. A method as set forth in claim 2 wherein said polyalkoxylated amine is a
polyalkoxylated monoamine and said combination of polyols comprises from
about 4% by weight to about 15% by weight of said first constituent, from
about 35% by weight to about 65% by weight of said second constituent, and
from about 25% by weight to about 45% by weight of said third constituent.
5. A method as set forth in claim 1 wherein said isocyanate and said
combination of polyols are present in said mixture in a relative
proportion such that the ratio of NCO groups to OH groups is from about
1:1 to about 1.8:1.
6. A method as set forth in claim 1 wherein said foam is an isocyanurate
foam and said isocyanate and said combination of polyols are present in
said mixture in a relative proportion such that the ratio of NCO groups to
OH groups is from about 2:1 to about 3:1.
7. A method as set forth in claim 2 wherein said polyalkoxylated amine is a
polyalkoxylated monoamine and said mixture further comprises a surfactant.
8. A method as set forth in claim 1 wherein said mixing of at least two
components to form a reaction mixture is carried out by mixing a component
A with a component B, component A comprising isocyanate, and component B
comprising
(a) from about 65% by weight to about 95% by weight, based on total
component B, of a combination of polyols having an average OH number of
from about 300 to about 500 and comprising polyalkoxylated glycerin having
an average OH number of from about 200 to about 300 and in which the
alkoxy groups each have from two to about three carbon atoms;
(b) from about 0.5% by weight to about 3% by weight of water, based on
total component B;
(c) up to about 5% by weight of water/isocyanate reaction catalyst, based
on total component B; and
(d) from about 5% by weight to about 15% by weight of CHClF.sub.2, based on
total component B.
9. A method as set forth in claim 1 wherein said mixing of at least two
components to form a reaction mixture is carried out by mixing a component
A with a component B, component A comprising isocyanate, from about 0.5%
by weight to about 12% by weight CHClF.sub.2, based on total component A,
and a surfactant, and component B comprising
(a) from about 65% by weight to about 95% by weight, based on total
component B, of a combination of polyols having an average OH number of
from about 300 to about 500 and comprising polyalkoxylated glycerin having
an average OH number of from about 200 to about 300 and in which the
alkoxy groups each have from two to about three carbon atoms;
(b) from about 0.5% by weight to about 3% by weight of water, based on
total component B;
(c) up to about 5% by weight of water/isocyanate reaction catalyst, based
on total component B; and
(d) from about 1% by weight to about 15% by weight of CHClF.sub.2, based on
total component B.
10. A method as set forth in claim 1 wherein said mixing of at least two
components to form a reaction mixture is carried out by mixing a component
A with CHClF.sub.2 and with a component B, component A comprising
isocyanate, component B comprising
(a) at least about 90% by weight, based on total component B, of a
combination of polyols having an average OH number of from about 300 to
about 500 and comprising polyalkoxylated glycerin having an average OH
number of from about 200 to about 300 and in which the alkoxy groups each
have from two to about three carbon atoms, and
(b) from about 0.5% by weight to about 3% by weight of water, based on
total component B.
11. A method as set forth in claim 2 wherein said polyalkoxylated amine is
a polyalkoxylated trifunctional amine.
12. A method for preparation of rigid foam, comprising mixing a component A
with a component B, component A comprising isocyanate, from about 0.5% by
weight to about 12% by weight CHClF.sub.2 based on total component A, and
a surfactant, and component B comprising
(a) from about 65% by weight to about 95% by weight, based on total
component B, of a combination of polyols comprising a first polyol
constituent, which comprises a polyalkoxylated amine having an average OH
number of from about 500 to about 700 and in which the alkoxy groups each
have from two to three carbon atoms, a second polyol constituent, which
comprises a sucrose-based polyol having an average OH number of from about
300 to about 400 and an average functionality of at least about 3, and a
third polyol constituent, which comprises polyalkoxylated glycerin having
an average OH number of from about 200 to about 300 and in which the
alkoxy groups each have from two to three carbon atoms;
(b) from about 0.5% by weight to about 3% by weight of water, based on
total component B;
(c) up to about 5% by weight of water/isocyanate reaction catalyst, based
on total component B; and
(d) from about 1% by weight to about 15% by weight of CHClF.sub.2, based on
total component B.
13. A method as set forth in claim 12 wherein said polyalkoxylated amine is
a polyalkoxylated monoamine and component A comprises from about 1% by
weight to about 7% by weight CHClF.sub.2 based on total component A.
14. A method as set forth in claim 12 wherein said polyalkoxylated amine is
a polyalkoxylated monoamine and component A further comprises up to about
5 parts by weight of an acid formation inhibitor per 1000 parts by weight
of CHClF.sub.2 in component A.
15. A method as set forth in claim 12 wherein said polyalkoxylated amine is
a polyalkoxylated monoamine and the second constituent of the combination
of polyols of component B further comprises an additional polyol selected
from the group consisting of ethylene glycol based polyols and glycerin
based polyols.
16. A method as set forth in claim 12 wherein said polyalkoxylated amine is
a polyalkoxylated monoamine and component A and component B are mixed in a
relative proportion such that the ratio of NCO groups to OH groups is from
about 1:1 to about 1.8:1.
17. A method as set forth in claim 12 wherein said polyalkoxylated amine is
a polyalkoxylated monoamine and combination of polyols comprises from
about 4% by weight to about 15% by weight of said first constituent, from
about 35% by weight to about 65% by weight of said second constituent, and
from about 25% by weight to about 45% by weight of said third constituent.
18. A method as set forth in claim 12 wherein said said polyalkoxylated
amine is a polyalkoxylated monoamine and component B further comprises up
to about 1% by weight based on total component B of an organometallic
catalyst and up to about 1.5% by weight based on total component B of a
trimerization catalyst.
19. A method as set forth in claim 12 wherein said polyalkoxylated amine is
a polyalkoxylated trifunctional amine.
20. A rigid foam produced by mixing a component A with a component B,
component A comprising isocyanate, from about 0.5% by weight to about 12%
by weight CHClF.sub.2 based on total component A, and a surfactant, and
component B comprising
(a) from about 65% by weight to about 95% by weight based on total
component B of a combination of polyols comprising a first polyol
constituent, which comprises a polyalkoxylated amine having an average OH
number of from about 500 to about 700 and in which the alkoxy groups each
have from two to three carbon atoms, a second polyol constituent, which
comprises a sucrose-based polyol having an average OH number of from about
300 to about 400 and an average functionality of at least about 3, and a
third polyol constituent, which comprises polyalkoxylated glycerin having
an average OH number of from about 200 to about 300 and in which the
alkoxy groups each have from two to three carbon atoms;
(b) from about 0.5% by weight to about 3% by weight of water, based on
total component B;
(c) up to about 5% by weight of water/isocyanate reaction catalyst, based
on total component B; and
(d) from about 1% by weight to about 15% by weight of CHClF.sub.2, based on
total component B.
21. A rigid foam as set forth in claim 20 having a closed cell content of
at least about 95%.
22. A rigid foam as set forth in claim 21 having a density in the range of
from about 1 lb/ft..sup.3 to about 4 lb/ft..sup.3.
23. A rigid foam as set forth in claim 22 having a density in the range of
from about 1 lb/ft..sup.3 to about 1.5 lb./ft..sup.3.
24. A rigid foam as set forth in claim 22 having a density in the range of
from about 1.5 lb/ft..sup.3 to about 2.5 lb/ft..sup.3.
25. A rigid foam as set forth in claim 22 having a density in the range of
from about 2.5 lb/ft..sup.3 to about 4 lb/ft..sup.3.
26. A method as set forth in claim 20 wherein said polyalkoxylated amine is
a polyalkoxylated trifunctional amine.
27. A method as set forth in claim 20 wherein said polyalkoxylated amine is
a polyalkoxylated monoamine.
28. A rigid foam produced by mixing at least two components to form a
reaction mixture comprising:
(a) isocyanate,
(b) from about 2% by weight to about 10% by weight CHClF.sub.2,
(c) from about 0.25% by weight to about 2% by weight of water, and
(d) a combination of polyols having an average OH number of from about 300
to about 500 and comprising polyalkoxylated glycerin having an average OH
number of from about 200 to about 300 and in which the alkoxy groups each
have from two to about three carbon atoms.
29. A rigid foam comprising cells of gaseous CHClF.sub.2, having a closed
cell content of at least 85% and exhibiting less than 5% volume change
when cooled from room temperature to -200.degree. F.
30. A rigid foam as set forth in claim 29 which exhibits less than 5%
volume change when cooled from room temperature to -200.degree. F. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to rigid foams, and more particularly to the
preparation of such foams utilizing fluorocarbon blowing agents.
2. Description of the Prior Art
Rigid foams conventionally have been prepared by a two-component or
three-component process. One component, generally referred to as component
A, comprises isocyanate. The second component, known generally as
component B, comprises any of various polyols, particularly polyester or
polyether polyols. Component B may also comprise a surfactant, a catalyst
package and a blowing agent, any of which may be introduced to the
reaction mixture as a third stream. If an excess of isocyanate is
employed, foams may be formed that are modified polyisocyanate foams. The
foams produced by these standard methods commonly have a density in the
range of of from about 1 lb./ft..sup.3 to about 4 lb./ft..sup.3, have a
closed cell content on the order of about 94% and have low friability
characteristics.
Ordinarily, the polyol is mono- or di-functional. That is, the polyol
molecule has one or two branches which provide linking sites for
cross-polymerization. Typically, the blowing agent is Freon-11 or Freon-12
(trade designations of E. I. du Pont de Nemours & Co.) or a mixture
thereof, often in combination with water.
Recently, however, such processes for preparation of rigid polyurethane
foam have been the subject of environmental concern in view of the
deleterious effects Freon-11 and Freon-12 have been reported to have on
the earth's ozone layer. As a result, the availability of Freon-11 and
Freon-12 for such use is seriously threatened and the total phasing out of
the use of Freon-11 and Freon-12 in the manufacture of rigid foam is
desirable. Freon-22 (a trade designation of E. I. du Pont de Nemours & Co.
for monochlorodifluoromethane or CHClF.sub.2) has been considered as a
blowing agent in rigid foams (see, for example, U.S. Pat. Nos. 4,205,136
and 4,636,529), usually in combination with other freon blowing agents.
However, Freon-22 generally has been considered and found to have a vapor
pressure so high that the use of significant quantities of it as a blowing
agent in standard formulations results in a closed cell content too low to
be acceptable for typical rigid foam applications.
Other problems have also been encountered with rigid foams based on, for
example, Freon-11. In particular, foam based on Freon-11 and having a
density in the range of 1.8 to 2.5 lb./ft..sup.3 and prepared without use
of aromatic polyethers tend to shrink at low temperatures. In fact, at
temperatures of, say, -75.degree. F. or lower, conventional Freon-11 foam
has been found to have poor dimensional properties.
Accordingly, methods for preparation of rigid polyurethane foam are needed
that do not utilize Freon-11 or Freon-12, but which are economically
competitve with foams made with Freon-11 or Freon-12 and produce a foam
that has a density equivalent to that of conventional foams, a closed cell
content at least as high as that of conventional foams and low friability
characteristics. It it also desirable that the foam resist shrinkage at
low temperatures.
SUMMARY OF THE INVENTION
Briefly, therefore, the present invention is directed to a novel method for
preparation of rigid foam. The method comprises mixing at least two
components to form a reaction mixture. The mixture comprises isocyanate,
up to 20% Freon-22, up to to about 2% by weight of water, and a
combination of polyols having an average OH number of from about 300 to
about 500 and comprising polyalkoxylated glycerin having an OH number of
from about 200 to about 300 and in which the alkoxy groups each have from
two to about three carbon atoms.
The present invention is also directed to a novel method for preparation of
rigid foam. The method comprises mixing a component A with a component B.
Component A comprises isocyanate, from about 0.5% by weight to about 12%
by weight Freon-22 based on total component A, and a surfactant. Component
B comprises from about 65% by weight to about 95% by weight, based on
total component B, of a combination of polyols, from about 0.5% by weight
to about 3% by weight of water, based on total component B, up to about 5%
by weight of amine catalyst, based on total component B, and from about 1%
by weight to about 25% by weight of Freon-22, based on total component B.
The combination of polyols comprises a first polyol constituent, which
comprises a polyalkoxylated amine having an average OH number of from
about 500 to about 700 and in which the alkoxy groups each have from two
to three carbon atoms, a second polyol constituent, which comprises a
sucrose-based polyol having an average OH number of from about 300 to
about 400 and an average functionality of at least about 3, and a third
polyol constituent, which comprises polyalkoxylated glycerin having an
average OH number of from about 200 to about 300 and in which the alkoxy
groups each have from two to three carbon atoms.
The present invention is also directed to a novel blend suitable for use as
a component in a two-component method for preparation of rigid foam. The
blend comprises isocyanate, from about 0.5% by weight to about 12% by
weight Freon-22 based on the total weight of the blend, and a surfactant.
The present invention is further directed to a novel blend suitable for use
as a component in a two-component method for preparation of rigid foam.
The blend comprises from about 65% by weight to about 95% by weight, based
on total blend, of a polyol mixture, from about 0.5% by weight to about 3%
by weight of water, based on total blend, up to about 5% by weight of
amine catalyst, based on total blend, and from about 1% by weight to about
25% by weight of Freon-22, based on total blend. The combination of
polyols comprises several polyol constituents. A first polyol constituent,
which comprises a polyalkoxylated amine having an average OH number of
from about 500 to about 700 and in which the alkoxy groups each have from
two to three carbon atoms. A second polyol constituent, which comprises a
sucrose-based polyol having an average OH number of from about 300 to
about 400 and an average functionality of at least about 3. A third polyol
constituent, which comprises polyalkoxylated glycerin having an average OH
number of from about 200 to about 300 and in which the alkoxy groups each
have from two to three carbon atoms.
The present invention is also directed to a novel rigid foam produced by
mixing a component A as described above with a component B as described
above.
The present invention is further directed to a novel rigid foam produced by
mixing at least two components to form a reaction mixture. The mixture
comprises isocyanate, from about 2% by weight to about 10% by weight
Freon-22, from about 0.25% by weight to about 2% by weight of water, and a
combination of polyols having an average OH number of from about 300 to
about 500 and comprising polyalkoxylated glycerin having an average OH
number of from about 200 to about 300 and in which the alkoxy groups each
have from two to about three carbon atoms.
The present invention is also directed to a novel rigid foam comprising
cells of gaseous CHClF.sub.2, having a closed cell content of at least 85%
and exhibiting less than 5% volume change when cooled from room
temperature to -200.degree. F.
Among the several advantages found to be achieved by the present invention,
therefore, may be noted the provision of a method for preparation of rigid
foam in which Freon-11 or Freon-12 is not needed; the provision of such
method that is economically competitve with foams made with Freon-11 or
Freon-12; the provision of such method that produces a foam that has a
density equivalent or lower than that of conventional foams; the provision
of such method that produces a foam having a closed cell content at least
as high as that of conventional foams; the provision of such method that
produces a foam having low friability characteristics; the provision of
such method that produces a foam that resists shrinkage at low
temperatures; the provision of blends useful in such method; the provision
of a rigid foam produced by such method; and the provision of rigid
polyurethane foams having the characteristics of foams produced by such
method.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In accordance with the present invention, it has been discovered that by
using Freon-22 as a blowing agent and including a polyalkoxylated glycerin
having an average OH number of from about 200 to about 300, and in which
the alkoxy groups each have from two to three carbon atoms, as a polyol in
the preparation of a rigid foam, a rigid foam of superior qualities may be
produced without the use of Freon-11 or Freon-12. This method may be used
to produce all types of rigid foams derived from isocyanate, including
rigid polyurethane, polyisocyanurate, and modified polyisocyanate foams.
Although the cost of Freon-22 historically had been significantly higher
than the costs of Freon-11 and Freon-12, recent increases in the cost of
Freon-11 and Freon-12 resulting from attempts to decrease usage of such
environmentally disfavored fluorocarbons have made Freon-22 not only
economically competitive, but less expensive than Freon-11 and Freon-22.
Nevertheless, Freon-22 still has not been adopted for use by the rigid
foam industry because of the concerns of storage and the low closed cell
content generally associated with Freon-22 and its high vapor pressure.
Accordingly, the rigid foam industry has not yet abandoned the use of
Freon-11 and Freon-12. However, it now has been discovered that by
including an elastomer commonly used in items such as bowling balls but
not commonly recognized as a polyol for use in preparation of rigid foams,
that is, a polyalkoxylated gycerin polyol, in component B, surprisingly,
rigid foams of appropriate density and very high closed cell content, in
fact, closed cell contents even somewhat higher than that of commercial
foams prepared by techniques utilizing Freon-11 or Freon-12, can be
produced.
Moreover, it has been found that by including Freon-22 in component A as
well as component B, lower pressures may be employed for storage of the
components than would be required for storage of undissolved Freon-22, and
the components can be blended more easily and thoroughly than they can
without the dissolved Freon-22. Not only that, but the foams produced by
the method of this invention have low friability characteristics, an
insulation value similar to foams produced in the conventional manner and,
perhaps even more surprisingly, have been found to have no detectable
volume change, i.e., less than 5% volume change, generally less than 1%
shrinkage, at temperatures below -200.degree. F.
The two-component method of this invention comprises mixing together a
component A and a component B. Component A comprises isocyanate, a
surfactant and Freon-22. The isocyanate may be any of the isocyanates
conventionally use in the production of rigid foams. Thus, any of the
polyfunctional isocyanates, such as diphenylmethane-4,4'-diisocyanate,
xylylene diisocyanates, polymethylenepolyphenylisocyanate,
3,3'-diphenyldimethylmethane-4,4'-diisocyanate, 2,4-tolylenediisocyanate
dimer, m-phenylenediisocyanate, tolylene diisocyanates or mixtures
thereof, may be used.
The surfactant aids in retaining the Freon-22 in solution. Silicones, such
as V8407 sold by Goldschmidt Chemical Corp., non-reactive polymers and
tris(2-chloropropyl) phosphates have been found to be particularly
suitable.
If desired, other compositions may also be included in the component A to
inhibit acid formation. Alpha-methylstyrene is a particularly effective
acid formation inhibitor.
The materials of component A may be blended in any standard manner, except
that introduction of the Freon-22 should be under pressure, such as from
about 50 p.s.i.a. to about 200 p.s.i.a. In order to minimize the duration
of high pressure application, the Freon-22 should be the final ingredient
blended into the mixture to form component A. Other than that
consideration, the order of blending is not particularly significant.
Nevertheless, a convenient order of mixing is to add surfactant to
isocyanate in a stirred vat, and then to add the acid inhibitor, if any.
Finally, the Freon-22 is added under pressure as noted above.
The relative proportions of ingredients should be such that the
concentration of Freon-22 in component A is from about 0.5% by weight to
about 12% by weight, preferably about 1% by weight to about 7% by weight.
Inclusion of the Freon-22 in component A has been found to lower the
viscosity of component A, thereby permitting a more thorough mixing with
component B. In addition, the employment of Freon-22 in component A has
been found to result in a final rigid foam product of lower density, such
that foams having a density of about 1 to about 1.4 lb./ft..sup.3 as
opposed to a density of about 2 lb./ft..sup.3 may be produced.
The surfactant makes up less than about 1% by weight, preferably about
0.75% by weight, of component A. If an acid inhibitor is desired, it may
be included in a concentration of up to about 0.5% by weight, based on the
weight of Freon-22 in component A. That is, up to about 5 parts by weight
of the acid formation inhibitor is add to component A per 1000 parts by
weight of Freon-22 in component A. The balance of component A comprises
the isocyanate.
Alternatively, component A may contain solely isocyanate and the Freon-22
may be injected into the reaction mixture as a separate stream or the
Freon-22 may reside solely in the component B. In such cases, a surfactant
need not be included in component A. However, although this technique has
been found to be useful to some extent for spray foams, generally it has
been found that if the Freon-22 is not added to component A, component A
and component B do not mix as thoroughly under standard mixing conditions
as desired. This is especially true for froth foams. Therefore, it is
highly preferred to include Freon-22 and a surfactant in component A.
Component A should be stored under pressure great enough to retain the
Freon-22 in the mixture of component A. Because the pressure required to
retain the Freon-22 in the mixture of component A is less than the vapor
pressure of Freon-22, lower pressure than that required for storage of
Freon-22 alone, or for mixing of Freon-22 into the mixture for preparation
of component A, is needed. In addition, maintaining component A at lower
temperatures allows the use of lower pressure. Thus, it is preferred that
component A be maintained at about 60.degree. F. or less.
Component B comprises from about 65% by weight to about 95% by weight,
preferably about 86% by weight to about 92% by weight, based on total
component B, of a combination of polyols. The combination of polyols
comprises at least three polyol constituents. The first polyol constituent
comprises a polyalkoxylated amine having an average hydroxyl number (i.e.,
an average OH number) of from about 500 to about 700, preferably from
about 550 to about 650, most preferably about 580 to about 620, and in
which the alkoxy groups each have from two to three carbon atoms. Thus,
propoxylated or ethoxylated or propoxylated and ethoxylated mono-, dior
triethanolamines are particularly desirable; however, any of the standard
polyether amines known in the art for use in preparation of rigid foams
are believed to be suitable. It is preferred that the polyalkoxylated
amine be a monoamine to avoid an overly viscous composition and that it
have three alkoxylated branches for maximum functionality. Nevertheless,
even this trifunctionality is not sufficient and the amine is too
autocatalytic to utilize the polyalkoxylated amine as the sole polyol.
Accordingly, while use of the first polyol constituent imparts to component
B a viscosity low enough for sufficient mixing with component A by
standard techniques, the second polyol substituent is included to increase
functionality. The second polyol constituent comprises a polyoxyalkylated
sucrose-based polyol having an average OH number of from about 300 to
about 400, preferably about 350 to about 380, and an average functionality
of at least about 3, preferably from about 3 to about 8, usually about 3
to about 5. Any of the conventional polyols for this purpose may be
employed. The sucrose-based polyol may be ethoxylated or propoxylated or
both. Generally, this constituent has a viscosity as high as 4,000 c.p.s.,
possibly as high as 8,000 c.p.s.
Preferably, the second constituent further comprises ethylene glycol-based
polyols or glycerin-based polyols. If desired, the polyols of the second
constituent may be prepared by polyoxyalkylating from a mixture of sucrose
and either ethylene glycol or glycerin, or both with ethylene oxide,
propylene oxide or both. Such polyols are known in the art and currently
are used in component B in standard rigid foam preparation techniques.
Especially suitable polyols are Vornal-360 as sold by Dow Chemical Co. and
Poly-G 74-376 as sold by Olin Corp.
The third polyol constituent comprises polyalkoxylated glycerin having an
average OH number of from about 200 to about 300, preferably about 260 to
about 300, and in which the alkoxy groups each have from two to three
carbon atoms. The viscosity of such polyethers, which may be propoxylated
or ethoxylated or propoxylated and ethoxylated glycerin, have a viscosity
of less than about 600 c.p.s., and most desirably less than 200 c.p.s.
These polyethers are known generally for their use as elastomers in
articles such as bowling balls, and are not ordinarily considered for use
in preparation of rigid foams. A particularly effective polyalkoxylated
glycerin is sold by Olin Corp. under the trade designation Poly-G 30-280.
However, it has now been found that such polyethers not only aid in the
reduction of the high viscosity imparted to the component B mixture by the
second polyol constituent, but also, because the glycerin-based polyol is
not autocatalytic, the reaction profile may be controlled, and perhaps due
in part to their trifunctionality, provide molecules that seem to retain
or help retain the Freon-22 in the foam being formed, thereby resulting in
a Freon-22-containing foam of extremely high closed cell content. In fact
Freon-22 seems to be held in this foam to an even greater extent than is
Freon-12 in commercial foams, resulting in an even higher closed cell
content than achieved with conventional foams.
The following weight proportions of the constituents of the combination of
polyols have been found to be desirable. The first constituent should
constitute from about 4% to about 15%, preferably about 6%, of the
combination of polyols. The second constituent should constitute from
about 35% to about 65%, preferably about 55%, of the combination of
polyols. The third constituent should constitute the remainder of the
combination of polyols--from about 25% to about 45%, preferably about 40%,
especially about 39%, of the combination of polyols.
It should be understood that the polyols in the combination need not form a
separate composition package to be added as a single ingredient to form
component B. Thus, it is not necessary to mix the three constituents of
the mixture together to form a premix and then to form component B by
admixing the premix with the remaining ingredients of component B,
although that is an option. The ingredients of component B may be mixed in
any order, and the three constituents of the combination of polyols may be
added separately from each other as separate ingredients to form component
B.
In addition to the polyols, component B further comprises from about 0.5%
by weight to about 3% by weight, preferably from about 1% by weight to
about 2% by weight, most preferably about 1.5% by weight water. The water
is understood to serve not only as a blowing agent but to add rigidity to
the resulting foam.
Component B further comprises Freon-22 and a water/isocyanate reaction
catalyst. Preferably, the catalyst is an amine catalyst, especially a
tertiary amine catalyst, and serves to promote the reaction between water
of component B and the isocyanate of component A when the two components
are blended. Freon-22 makes up about 1% by weight to about 25% by weight,
preferably about 3% by weight to about 10% by weight, of component B.
Generally, component B should comprise less than about 5% by weight,
preferably about 1% by weight to about 2% by weight, of the
water/isocyanate reaction catalyst.
As with component A, component B may, alternatively, contain no Freon-22 or
only a small amou | | |
