Note: Descriptions are shown in the official language in which they were submitted.
CA 02259500 1999-02-08
PROCESS FOR MAKING ISOCYANATE-BASED RIGID FOAM
FIELD OF THE IINVENTION
The present invention relates generally to a process for making isocyanate-
based rigid foams
from stable polyester polyol compositions comprising a;phthalic anhydride-
initiated polyester polyol, a C4-
CB hydrocarbon blowing agent, and a compatibilizing agent having an HLB of
from about 7 to 12. The
compatibilizing agent is a fatty acid or fatty alcohol ethoxylate. The blowing
agent is soluble in the polyol
composition. The process comprises reacting an organic polyisocyanate wirth
the polyol composition in the
presence of the blowing agent and other optional components. The process
results in a rigid
polyurethane/polyisocyanurate foam which has improved dimensional stability
and thermal insutation
properties including improved K factors.
BACKGROUND OF TIiE INVENTION
Hydrocarbons are gaining wider acceptance as viable altemative blowing agents
in the
manufacture of rigid polyurethane foams. Due to the non-polar hydrophobic
characteristic of
hydrocarbons, they are only partially soluble, if not completely insoluble, in
many polyols used to
manufacture rigid polyurethane foams. The insolubility or poor shelf life of
hydrocarbon-polyol mixtures
has, to date, limited the ability of storing batches of the mixtures for use
at a later time. Due to the poor
solubility of hydrocarbons blowing agents in polyols, the blowing agent must
be added to the polyol
composition under constant agitation immediately before dispensing the foaming
ingredients through a
mixhead. The poor solubility of hydrocarbons also tends to lead to larger,
coarser, or uneven cell
structures in a resultant polyurethane foam. As is well known, the thermal
conductivity of a foam generally
increases with a poor cell structure. Therefore, it is criticeil that
hydrocarbon be uniformly dispersed under
constant agitation throughout the polyol mixture immediately prior to foaming
in order to obtain a rigid
polyurethane foam having the desired thermal insulation values.
In U.S. Patent No. 5,391,317, Smits sought to manufacture a foam having both
good dimensional
stability and thermal insulation using hydrocarbons as blowing agents. This
reference taught the use of a
particular mixture of C5.8 alicyclic alkanes, isopentane arid n-pentane
blowing agents in particular molar
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CA 02259500 1999-02-08
percents, in combination with a polyol mixture made up of an aromatic
initiated polyether polyol, an
aromatic polyester polyol, and a different amine-inii:iated polyether polyol.
As the aromatic-initiated
polyether polyol, Smits suggested using an alkylene oxide adduct of a
phenolformaldehyde resin. The
particular mixture of alicyclic and isomeric aliphatic alkane blowing agents
is taught by Smits as producing
a foam having good thermal insulation values.
The problem of obtaining a closed cell rigid polyurethane foam having both
good dimensional
stability and thermal insulation at low densities was also discussed in "An
Insight Into The Characteristics
of a Nucleation Catalyst I HCFC-Free Rigid Foam System" by Yoshimura et al.
This publication reported
the results of evaluations on a host of catalysts used in a standard
polyurethane formulation to test the
effects of each catalyst on the thermal insulation and dimensional stability
of the foam. The standard
formulation used contained 40 parts by weight of a sucrose-based polyether
polyol, 30 parts by weight of
an aromatic amine-initiated polyether polyol, and 30 parts by weight of an
aliphatic amine-initiated
polyether polyol, in a 1:1 weight ratio of aromatic to aliplhatic amine-
initiated polyols. This formulation was
selected based upon the findings that sucrose and aron~iatic amine-based
polyether polyols exhibited poor
solubilities with cyclopentane, while aliphatic amine-based polyether polyols
provided the best solubility
for cyclopentane. As a result, 30 parts by weight of the aliphatic amine-
initiated polyether polyol was used
in the standard formulation.
Others have also tried to modify the polyol components in a polyol composition
in an attempt to
solubilize a hydrocarbon blowing agent in the polyol composition. In U.S.
Patent 5,547,998 (White et al),
the level of aliphatic amine-initiated polyether polyols in a polyol
composition is limited to solubilize
cyclopentane in the polyol composition. When reacted with an organic
isocyanate, the polyol composition,
comprising an aromatic amine-initiated polyoxyalkylene polyether polyol and an
aliphatic amine-initiated
polyoxyalkylene polyether polyol in an amount of 10 weight percent or less by
weight of the polyol
composition produces a dimensionally stable rigid closed cell polyurethane
foam having good thermal
insulation properties.
In U.S. Patent 5,648,019 (White et al), the level of aromatic polyester
polyols in a polyol
composition is preferably limited to 18 weight percent or less to improve the
solubility of blowing agent in
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the polyol composition. The polyol composition is preferably reacted with an
organic isocyanate to produce a rigid closed cell foam having good thermal
insulation and dimensional stability.
Thus, it would be desirable to provide a polyester polyol composition
which has a hydrocarbon blowing agent solubilized therein which can be used to
produce dimensionally stable rigid polyurethane foam having good thermal
insulation properties.
SUMMARY OF THE INVENTION
According to the present invention a stable polyester polyol composition
is provided, comprising a phthalic anhydride-initiated polyester polyol, a
blowing
agent selected from the group consisting of C4-C6 hydrocarbons and mixtures
thereof, and a compatibilizing agent having an HLB of from about 7 to 12. The
compatibilizing agent is selected from the group consisting of oxyethylated
fatty
acids having a general formula of RnCO0(EO)x-H, wherein Rn is a C14 to a
C26 alkyl chain, EO represents an ethylene oxide unit and x is from 5 to 12.
In
the present invention, the blowing agent is soluble in the polyol composition
for
at least 5 days.
In one embodiment, the compatibilizing agent comprises a C18-C20
fatty acid-initiated oxyethylate having an average of about 8 ethylene oxide
units
per molecule. Preferably, the compatibilizing agent is present in an amount of
from about 1.0 to about 25.0, more preferably 5.0 to about 15.0, most
preferably
7.0 to about 10.0, parts by weight based on 100 parts by weight of the
polyester
polyol.
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The blowing agents employed when used in association with the polyol
compositions of the present invention have been found to offer lower
densities,
improved K factors, improved thermal insulation properties and improved
dimensional stabilities over foams produced using other polyol systems. The
compatibilizing agent preferably facilitates solubilizing the blowing agent in
the
polyol composition without sacrificing, and advantageously improving, the
thermal insulation and dimensional stability of the resulting polyurethane
foam.
The blowing agent is preferably selected from the group of C5 hydrocarbons,
including isopentane, normal pentane, neopentane, cyclopentane and mixtures
thereof. A preferred blowing agent mixture comprises a blend of isopentane
and/or normal pentane and cyclopentane. In another embodiment of the present
invention, the blowing agent comprises a blend of cyclopentane and isopentane,
preferably in a weight ratio of about 70:30 to about 40:60. The amount of
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blowing agent present in the polyol composition is preferably at least 5.0
parts
by weight based on 100 parts by weight of the polyester polyol. In preferred
embodiments of the invention, the amount of blowing agent in the polyol
composition is from about 7 to about 30, more preferably from about 20 to
about
30, most preferably from about 24 to about 27 parts by weight, based on 100
parts by weight of the polyester polyol.
There is also provided a polyisocyanate based rigid closed cell foam
made by reacting an organic isocyanate with a polyol composition in the
presence of a blowing agent, wherein the polyol composition comprises:
a) a phthalic anhybride-initiated polester polyol, preferably having a
hydroxyl number of 200 meq. polyol/g KOH or more, preferably in
an amount of at least 50.0 percent by weight based on the weight
of all polyol components in the polyol composition;
b) a blowing agent; and
c) an oxyethylated fatty acid or fatty alcohol compatibilizing agent.
Again, the blowing agent comprises a C4-C6 hydrocarbon and is
present in an amount of at least about 5.0 parts by weight, based on 100 parts
by weight of the polyester polyol. By employing these constituents in the
polyol
composition, the blowing agent is soluble in the polyol composition. There is
also provided a polyurethane foam comprising the reaction product of an
organic
isocyanate and a polyol composition containing the aforementioned blowing
agent.
More particularly, the present invention as claimed thus provides an
isocyanate-based rigid foam obtained from the reaction product comprising an
organic and/or modified organic polyisocyanate and a polyol composition. The
polyol composition comprises at least 75% by weight of a phthalic anhydride-
initiated polyester polyol, a compatibilizing agent having an HLB of from
about 7
to about 12 and selected from the group consisting of oxyethylated fatty acids
have a general formula of Rn-COO(EO)X-H, wherein Rn is a C14 to a C26 alkyl
chain, EO represents ethylene oxide units and x is from 5 to 12. The polyol
composition also comprises a blowing agent selected from the group consisting
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CA 02259500 2007-07-17
of C4-C6 hydrocarbons and mixtures thereof, and, optionally, a relatively low
molecular weight chain extender or crosslinker, a surfactant, a catalyst and
further auxiliaries and/or additives, wherein said blowing agent is soluble in
the
polyol composition for at least 5 days.
There is also provided a method of making a polyisocyanate based rigid
closed cell foam comprising reacting an organic isocyanate with a phthlic
anhybride initiated polyester polyol composition into which is incorporated a
hydrocarbon blowing agent preferably in an amount of at least 5.0 parts by
weight, based on 100 parts by weight of the polyester polyol. Preferably the
polyester polyol has hydroxyl number of 200 meq. polyol/g KOH or more. In
another aspect of the invention, the polyester polyol is preferably present in
the
polyol composition in an amount at least 50.0 percent by weight, preferably at
least 60.0 percent by weight, most preferably at least 75.0 percent by weight,
based on the weight of all polyol components in the polyol composition. An
oxyethylated fatty acid or fatty alcohol compatibilizing agent is preferably
incorporated into the polyol composition.
More particularly, the invention as claimed thus concerns a process for
producing an isocyanate-based rigid foam which comprises a reaction between
an organic and/or modified organic polyisocyanate and a polyol composition.
The polyol composition comprises at least 75% by weight of a phthalic
anhydride-initiated polyester polyol, a compatibilizing agent having an HLB of
from about 7 to about 12 and selected from the group consisting of
oxyethylated
fatty acids having a general formula of Rn-COO(EO)x-H, wherein Rn is a C14 to
a C26 alkyl chain, EO represents ethylene oxide units and x is from 5 to 12,
and
a blowing agent selected from the group consisting of C4-C6 hydrocarbons and
mixtures thereof, and, optionally, a relatively low molecular weight chain
extender or crosslinker, a surfactant, a catalyst and further auxiliaries
and/or
additives, wherein said blowing agent is soluble in the polyol composition for
at
least 5 days.
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CA 02259500 1999-02-08
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
There Is provided a storage stable polyol composition comprising a polyester
polyol, a
hydrocarbon blowing agent and a compatibilizing agent. A polyol composition is
deemed "storage stable"
or "soluble" when the polyol composition has the capacity of retaining the
blowing agent in solution or in a
dissolved state for a period of at least 5 days. The determination of whether
or not the blowing agent is In
solution or dissolved or soluble is measured by mixing the blowing agent with
the polyol composition
ingredients in a clear glass jar, capping the jar, vigorously agitating the
contents in the jar and letting the
contents remain still for 5 days at room temperature without agitation. If
upon visual inspection there is no
phase separation such that two discrete layers are forrned, the blowing agent
is deemed soluble in the
polyol composition, and the polyol composition is deemed storage stable.
This test which iasts at least five days is only for purposes of measuring
whether a particular
polyol composition formulation is adequate to soiubilizE: the blowing agent.
As discussed further below,
the blowing agent may be added to the polyol composition weeks prior to
foaming, seconds prior to
foaming, or right at the mix head. The scope of the invention includes each of
these embodiments. By
stating that the blowing agent is soluble in the polyol composition, it is
meant that the polyol composition
employed must be capable of maintaining a single phase product by visual
inspection. In some cases, this
may mean that a particular blowing agent forms a micro-emulsion with the
polyol and other components.
An important criteria is the uniform dispersal of the blowing agent during the
foaming process as
described herein.
Where it is said that the polyol compositlon "coritains" a blowing agent or
that the blowing agent Is
"dissolved in", "solubilized" or "in solution" with the! polyol composition,
this would Include those
embodiments where the blowing agent is mixed with the other polyol composition
ingredients for a period
of time sufficient to uniformly dissolve the blowing agent in the polyol
composition prior to introducing the
poiyoi composition into the mix head for reaction with an organic isocyanate
compound, and would not
include those embodiments where blowing agent is metered as a separate stream
into a dispensing head
for reaction with an organic isocyanate.
The polyol composltion of the present inventioln contains a phthalic anhydride-
initiated polyester
5
CA 02259500 2005-05-25
polyol, a C4-C6 hydrocarbon blowing agent and a oxyethylated fatty acid or
fatty
alcohol compatibilizing agent having an HLB of from about 7 to about 12. Other
ingredients that may be included in the polyol composition are other polyols,
catalysts, surfactants, other blowing agents, flame retardants, fillers,
stabilizers
and other additives.
The polyester polyols useful in accordance with the teaching of the
present invention include phthalic anhydride-initiated polyester polyols.
Preferably, this polyester polyol has a hydroxyl number of at least 200 meq.
polyol/g KOH. These polyester polyols provide improved dimensional stability
to
a rigid foam of the present invention. These phthalic anhydride-initiated
polyester polyols are generally described in U.S. Pat. Nos. 4,644,048;
4,644,047; 4,644,027; 4,615,822; 4,608,432; 4,595,711; 4,529,744; and
4,521,611.
Particularly preferred polyester polyols of the present invention include
STEPANPOL PS2352, a phthalic anhydride-initiated polyester polyol
commercially available from Stepan Chemical Company (Northfield, IL.).
The overall amount of phthalic anhydride-initiated polyester polyol is
preferably at least 50.0 weight percent, more preferably 60.0 weight percent,
most preferably 75.0 weight percent based on the overall weight of all polyol
components in the polyol composition. In one embodiment, the phthalic
anhydride-initiated polyester polyol is the sole polyol component in the
polyol
composition. The polyol composition of the present invention may contain
polyols other than the phthalic anhydride-initiated polyester polyol described
above, e.g., other polyester polyols and polyether polyols including aromatic
amine-initiated polyols and aliphatic amine-initiated polyols, for example.
The amount of additional polyols relative to the polyester polyol is not
intended to be limited so long as the desired objective of manufacturing a
dimensionally stable foam having good thermal insulation values, and
optionally,
but preferably solubilizing the blowing agent in the polyol composition can be
achieved. In this regard, it should be understood that the predominant factors
in
formulating a stable polyol composition according to the present invention
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include the limited ability of the phthalic anhydride initiated polyester
polyol to
solubilize blowing agents and the limited ability of specific hydrocarbon
blowing
agents or blends thereof to blend into polyester polyols, particularly the
phthalic
anhydride-
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CA 02259500 1999-02-08
initiated polyester polyol. At the same time, one skilled in the art will
appreciate that certain hydrocarbon'
blowing agents will provide distinct physical characteristics to an isocyanate-
based foam, which
characteristics must be taken into account when developing a polyester polyol
composition or rigid foam.
Under a preferred embodiment of the present invention the amount of additional
polyols, including
aromatic or aliphatic amine-initiated polyoxyalkylene polyether polyols and
other polyester polyols,
present in the polyol composition is less than about 20.0, more preferably
less than about 15.0, most
preferably less than about 10.0 percent by weight base:d on the weight of all
polyot components in the
polyol composition.
Suitable additional polyester polyols include ttiose obtained, for example,
from polycarboxylic
acids and polyhydric alcohols. A suitable polycarboxylie acid may be used such
as oxalic acid, malonic
acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid,
azefaic acid, sebacic acid.
brassylic acid, thapsic acid, maleic acid, fumaric acid, glutaconic acid, a-
hydromuconic acid, 13-
hydromuconic acid, a-butyl-a-ethyl-glutaric acid, a,fl-diethylsuceinic acid,
isophthalic acid, terephthalic
acid, phtalic acid, hemimellitic acid, and 1,4-cyclohexanedicarboxylic acid. A
suitable polyhydric alcohol
may be used such as ethylene 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-trimethyfofethane, pentaerythritol, 1,2,6-
hexanetriol, a-methyl glucoside,
sucrose, and sorbitol. Also included within the term "polyhydric alcohol" are
compounds derived from
phenol such 2,2-bis(4-hydroxyphenol)-propane, commonly known as Bisphenol A.
Preferred additional
polyester polyols are aromatic polyester polyols.
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 polycarboxylic
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 componentr; being a diamine
such as ethylene diamine.
Another puitable polyester polyol useful as an additional polyester polyol Is
an alpha-
methyigiucoside initiated polyester polyol derived from polyethylene
terephthalate. This polyol has a
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CA 02259500 1999-02-08
molecular weight of approximately 358, a hydroxyl number of about 360 meq
polyol/g KOH and a nominal
average functionality of 2.3.
As alluded to above, each of the polyols, incluciing the polyester polyol,
preferably have hydroxyl
numbers of 200 or more meq polyol/g KOH. At hydroxyl numbers of less than 200,
the dimensional
stability of the foam may begin to deteriorate. The optimum nominal
functionality of aromatic polyester
polyol appears to be 2 or more, with an average hydroxyl numbers of 350 or
more. Likewise, the optimum
nominal functionality of each amine-initiated polyol appears to be 4 or more,
with hydroxyl numbers of 400
or more.
Other polyols besides the polyester polyols described herein can be added to
the polyol
3.0 composition provided the desired objectives discussed above can be
achieved. Such polyols would
include polyoxyalkylene polyether polyols, polythioether polyols, polyester
amides and polyacetals
containing hydroxyl groups, aliphatic polycarbonates containing hydroxyl
groups, amine terminated
polyoxyalkylene polyethers, polyester polyols, other polyoxyalkylene polyether
polyols, and graft
dispersion polyols. In addition, mixtures of at least two of the aforesaid
polyols can be used. The
preferable additional polyols are polyoxyalkylene polyether polyols; however,
the total amount of
additional polyols employed will preferably not exceed 20.0 weight percent
based on the total weight of all
polyol components in the polyol composition.
Included among polyoxyalkylene polyether polyols are polyoxyethylene polyols,
polyoxypropylene
polyols, polyoxybutylene polyols, polytetramethylerie polyols, and block
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
polyoxyalkylene polyether polyols may
be prepared by any known process such as, for example, the process disclosed
by Wurtz in 1859 and
Encyclopedia of Chemical Technology, Vol. 7, pp. 257-262, published by
Interscience Publishers, Inc.
(1951) or in U.S. Pat. No. 1,922,459. The alkylene oxides may be added to the
Initiator, Individually,
sequentially one after the other to form blocks, or in mixture to form a
heteric polyether. The
polyoxyalkylene polyether polyols may have either primary or secondary
hydroxyl groups.
8
CA 02259500 1999-02-08
The polyoxyalkylene polyether polyol may he,ve aromatic amine-initiated or
aiiphatic amine-,
initiated polyoxyalkylene polyether poiyois. It is preferred that at least one
of the amine-initiated polyols
are polyether polyols terminated with a secondary hydroxyl group through
addition of, for example,
propylene oxide as the terminal block. It is preferred that the amine-
initiated polyols contain 50 weight
percent or more, and up to 100 weight percent, of secondary hydroxyl group
forming alkylene oxides,
such as polyoxypropylene groups, based on the weiglit of all oxyalkylene
groups. This amount can be
measured by adding 50 weight percent or more of the secondary hydroxyl group
forming alkylene oxides
to the initiator molecule in the course of manufacturing the polyol.
Suitable initiator molecules for the polyoxyalkylene polyether compounds are
primary or
secondary amines. These would include, for the aromiatic amine-initiated
polyether polyol, the 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-aminoaniline, 1,5-
diaminonaphthalene,
methylene dianiline, the various condensation products of aniline and
formaldehyde, and the isomeric
diaminotoluenes, with preference given to vicinal tolueriediamines.
For the aliphatic amine-initiated polyol, any aliphatic amine, whether
branched or unbranched,
substituted or unsubstituted, saturated or unsaturated., may be used. These
would include, as examples,
mono-, di, and trialkanolamines, such as monoethanolamine, methylamine,
triisopropanolamine; and
polyamines such as ethylene diamine, propylene diamine, diethylenetriamine; or
1,3-diaminopropane, 1,3-
diaminobutane, and 1,4diaminobutane. Preferable aliphatic amines include any
of the diamines and
triamines, most preferably, the diamines.
Preferably, the additional polyols have nurnber average molecular weights of
200-750 and
nominal functionalities of 3 or more. By a nominal furictionality, it is meant
that the functionaliry expected
is based upon .the functionality of the initiator molecule, rather than the
actual functionality of the final
polyether after manufacture.
The polyoxyalkylene polyether polyols are polyoxyalkylene polyether polyols.
These polyots may
generally be prepared by polymerizing alkylene oxides with polyhydric amines.
Any suitable alkylene
oxide may be used such as ethylene oxide, propylene oxide, butylene oxide,
amyiene oxide, and mixtures
9
CA 02259500 1999-02-08
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.
Other polyoxyalkylene polyether polyols may include those initiated with
polyhydroxyl
compounds. Examples of such initiators are trimethylolpropane, glycerine,
sucrose, sorbitol, propylene
glycol, dipropylene glycol, pentaerythritol, and 2,2-bis(4-hydroxyphenyl)-
propane and blends thereof. The
preferred polyols are initiated with polyhydroxyl compounds having at least 4
sites reactive with alkylene
oxides, and further may be oxyalkylated solely with propylene oxide. In a more
preferred embodiment, the
additional polyol is a polyoxyalkylene polyether polyo'I having a nominal
functionality of 5 or more, that
may be initiated with a polyhydroxyl compound. The high functionality serves
to increase the crosslink
density to provide a dimensionally stable foam.
Suitable polyhydric polythioethers which may be condensed with alkylene oxides
include the
condensation product of thiodiglycol or the reaction product of a dicarboxyiic
acid such as is disclosed
above for the preparation of the hydroxyl-containing polyesters with any other
suitable thioether polyol.
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 dihiydric alcohol or an
alkylene oxide such as those
disclosed above.
Suitable aliphatic thiols which may be condensed with alkylene oxides include
alkanethiols
containing at least two -SH groups such as 1,2-ethane:dithiol, 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 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,
CA 02259500 2005-05-25
preferably acrylonitrile and styrene, in 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. Pat. No. 3,652,639; in columns 1-6 and the
Examples of U.S. Pat. No. 3,823,201; particularly in columns 2-8 and the
Examples of U.S. Pat. No. 4,690,956; and in U.S. Pat. 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. Pat. Nos. 4,293,470;
4,296,213; and 4,374,209; dispersions of polyisocyanurates containing pendant
urea groups as taught by U.S. Pat. No. 4,386,167; and polyisocyanurate
dispersions also containing biuret linkages as taught by U.S. Pat. No.
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 mm, preferably less than 10
mm.
The average hydroxyl number of the polyols in the polyol composition
should preferably be 200 meq polyol/g KOH or more and, more preferably 350
meq polyol/g KOH or more. Individual polyols may be used which fall below the
lower limit, but the average should be within this range. Polyol compositions
whose polyols are on average within this range make good dimensionally stable
foams.
In addition to the foregoing, the polyester polyol composition of the
present invention also includes a blowing agent selected from the group
consisting of C4-C6 hydrocarbons and mixtures thereof. The blowing agent may
be added and solubilized in the polyol composition for storage and later use
in a
foaming apparatus or may be added to a preblend tank in the foaming apparatus
and preferably solubilized in the polyol composition immediately prior to
pumping or metering the foaming ingredients to the mix head. Alternatively,
the
blowing agent may be added to the foaming ingredients in the mix head as a
separate stream, although full solubility might be limited due to the short
amount
of time the blowing agent is exposed to the polyol composition in the mix
head.
The advantage of the polyol composition of the invention is that the poiyol
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composition provides the flexibility of storing stable polyol compositions
containing the desired blowing agent, or solubilizing the blowing agent with
the
polyol composition in the preblend tank, or adding it at the mix head, to
manufacture a foam of the desired quality. The polyol composition of the
invention is specially adapted to enable a variety of blowing agents to be
employed to produce rigid closed cell polyisocyanate based foams meeting the
desired objectives.
The amount of blowing agent used is preferably 5.0 parts by weight or
more based on 100 parts by weight of the polyester polyol in the polyol
composition. The particular amount of blowing agent will depend in large part
upon the desired density of the foam product. For most applications,
polyurethane free rise densities for thermal insulation applications range
from
free rise densities of 0.5 to 10 pcf, preferably from 1.2 to 2.5 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 2.5 pcf, more
preferably from 1.3 to 2.0 pcf. The amount by weight of all blowing agents is
generally, based on the weight of the polyol composition, from about 5.0 parts
by weight to 40.0 parts by weight, and more preferably, 7.0 parts by weight to
30.0 parts by weight, most preferably from about 20.0 to about 30.0 parts by
weight, based on 100 parts by weight of the polyester polyol. In one
embodiment
herein, the blowing agent is present in an amount of from about 24.0 to about
27.0 parts by weight, based on 100 parts by weight of the polyester polyol.
The blowing agents useful in the polyol composition of the present
invention are selected from the group consisting C4-C6 hydrocarbons and
mixtures thereof. The hydrocarbons are preferably the sole blowing agent,
optionally with water. Thus, such blowing agents include butanes, pentanes,
hexanes, and mixtures thereof. Such blowing agents may be linear, unbranched
or cyclic in chemical structure. Preferred blowing agents are the pentanes,
i.e.,
isopentane, normal pentane, cyclopentane and neopentane. The pentanes may
be incorporated into the polyol composition of the present invention alone or
as
12
CA 02259500 2006-06-20
a blend of two or more thereof. In one embodiment of the present invention,
the
blowing agent comprises a mixture of cyclopentane and isopentane, which
preferably has a weight ratio of between about 70:30 and 40:60. Furthermore,
mixtures of normal pentane with isopentane and/or cyclopentane are also
preferred. Blowing agents comprising isopentane and cyclopentane provide
excellent dimensional stability and insulation properties to a rigid foam of
the
present invention. Generally, the selection of the blowing agent utilized will
depend on the desired physical characteristics of the polyurethane foam. Those
skilled in the art are familiar with the effects provided by the blowing
agents of
the present invention.
The hydrocarbon blowing agents of the present invention are generally
available from
12a
CA 02259500 1999-02-08
manufacturers of fractional distillation products from petroleum, including
Phillips Petroleum and Exxon
Corporation. One known method of producing a high purity cyclopentane blowing
agent is disclosed in
U.S. Patent 5,578,652 (Blanpied et al).
The above hydrocarbons may be used as the sole blowing agent in the present
invention.
However, additional limited amounts of auxiliary blowing agents may be used,
including HFC's and
HCFC's. Suitable hydrofluorocarbons, perfluorinated hydrocarbons, and
fluorinated ethers (collectively
referred to herein as HFC's) which are useful as additional blowing agents
include difluoromethane (HFC-
32); 1,1,1,2-tetrafluoroethane (HFC-134a); 1,1,2,2-tetrafluoroethane (HFC-
134); 1,1-difluoroethane (HFC-
152a); 1,2-difluoroethane (HFC-142), trifluoromethane;; heptafluoropropane;
1,1,1-tr"rfluoroethane; 1,1,2-
trifluoroethane; 1,1,1,2,2-pentafluoropropane; 1,1,1,:3,3-pentafluoropropane
(HFC 245fa); 1,1,1.3-
tetrafluoropropane; 1,1,2,3,3-pentafluoropropane; 1,1,1,3,3-pentafluoro-n-
butane; 1,1,1,2,3,3,3-
heptafluoropropane (HFC 227ea); hexafluorocyclopropane (C-216);
octafluorocyclobutane (C-318);
perfluorotetrahydrofuran; perfluoroalkyl tetrahydrofuraiis; pertluorofuran;
perfluoro-propane, -butane, -
cyclobutane, -pentane, -cyclopentane, and -hexane, -cyclohexane, -heptane, and
-octane; perfluorodiethyl
ether; perfluorodipropyl ether, and perfluoroethyl propyl ether. Preferred
among the HFC blowing agents
are HFC 134a and HFC 236ea, respectively.
Suitable hydrochlorofluorocarbon blowing agenits which may also be used as
additional blowing
agents are 1-chloro-1,2-difluoroethane; 1-chloro-2,2-clifluoroethane (142a); 1-
chloro-1,1-difluoroethane
(142b); 1,1-dichloro-l-fluoroethane (141b); 1-chloro-1,1,2-trifluoroethane; 1-
chloro-1,2,2-trifluoroethane;
1,1-diochloro-1,2-difluoroethane; 1-chloro-1,1,2,2-te-trafluoroethane (124a);
1-chloro-1,2,2,2-
tetrafluoroethane (124); 1,1-dichloro-1,2,2-trifluoroethane; 1,1-dichloro-
2,2,2-trifluoroethane (123); and
1,2-dichloro-1,1,2-trifluoroethane (123a); monochlorodifluoromethane (HCFC-
22); 1-chloro-2,2,2-
trifluoroethane (HCFC-133a); gem-chlorofluoroethylerie (R-1131 a);
chloroheptafluoropropane (HCFC-
217); chlorodifluoroethylene (HCFC-1122); and trans-chlorofluoroethylene (HCFC-
1131). Preferred
among hydroohlorofluorocarbon blowing agents is 1,1-dichloro-l-fluoroethane
(HCFC-141b)-
Other blowing agents which can be used in addition to the blowing agents
listed above may be
divided into the chemically active blowing agents which chemically react with
the isocyanate or with other
13
CA 02259500 1999-02-08
formulation ingredients to release a gas for foaming, and the physically
active blowing agents which are
gaseous at the exotherrnic foaming temperatures or less without the necessity
for chemically reacting with
the foam ingredients to provide a blowing gas. Included within the meaning of
physically active blowing
agents are those gases which are thermally unstable and decompose at elevated
temperatures.
Examples of chemically active blowing agents are preferentially those which
react with the
isocyanate to liberate gas, such as CO2. Suitable chEamically active blowing
agents include, but are not
limited to, water, mono- and polycarboxylic acids having a molecular weight of
from 46 to 300, salts of
these acids, and tertiary alcohols.
Water is preferentially used as a blowing agent. Water reacts with the organic
isocyanate to
liberate CO2 gas which is the actual blowing agent. However, since water
consumes isocyanate groups,
an equivalent molar excess of isocyanate must be used to make up for the
consumed isocyanates. Water
is typically found in minor quantities in the polyols as a byproduct and may
be sufficient to provide the
desired blowing from a chemically active substance. Preferably, however, water
is additionally introduced
into the polyol composition in amounts of from about 0.02 to 5 weight percent,
preferably from 0.05 to 4
parts by weight, based on 100 parts by weight of the polyester polyol.
The organic carboxylic acids used are advantageously aliphatic mono- and
polycarboxylic acids,
e.g. dicarboxylic acids. However, other organic mono== and polycarboxylic
acids are also suitable. The
organic carboxylic acids may, if desired, also contairi substituents which are
inert under the reaction
conditions of the polyisocyanate polyaddition or arE: reactive with
isocyanate, and/or may contain
olefinically unsaturated groups. Specific examples of chemically inert
substituents are halogen atoms,
such as fluorine and/or chlorine, and alkyl, e.g. methyl or ethyl. The
substituted organic carboxylic acids
expediently contain at least one further group which is reactive toward
isocyanates, e.g. a mercapto
group, a primary and/or secondary amino group, or prefierably a primary and/or
secondary hydroxyl group.
Suitable carboxylic acids are thus substituted or unsubstituted monocarboxylic
acids, e.g. formic
acid, acetic acid, propionic acid, 2-chloropropionic acid, 3-chloropropionic
acid, 2,2-dichloropropionic acid,
hexanoic acid, 2-ethyl-hexanoic acid, cyclohexanecarboxylic acid, dodecanoic
acid, palmitic acid, stearic
acid, oleic acid, 3-mercapto-propionic acid, glycolic acid, 3-hydroxypropionic
acid, lactic acid, ricinoleic
14
CA 02259500 1999-02-08
acid, 2-aminopropionic acid, benzoic acid, 4-rnethylbenzoic acid, salicylic
acid and anthranilic acid, and
unsubstituted or substituted polycarboxylic acids, preferably dicarboxylic
acids, e.g. oxalic acid, malonic
acid, succinic acid, fumaric acid, maleic acid, glutaric acid, adipic acid,
sebacic acid, dodecanedoic acid,
tartaric acid, phthalic acid, isophthalic acid and citric acid. Preferable
acids are formic acid, propionic acid,
acetic acid, and 2-ethylhexanoic acid, particularly formic acid.
The amine salts are usually formed using tertiary amines, e.g. triethylamine,
dimethylbenzylamine, diethylbenzylamine, triethylenediamine, or hydrazine.
Tertiary amine salts of formic
acid may be employed as chemically active blowing agents which will react with
the organic isocyanate.
The salts may be added as such or formed in situ by reaction between any
tertiary amine (catalyst or
polyol) and formic acid contained in the polyol composition.
Combinations of any of the aforementioned chemically active blowing agents may
be employed,
such as formic acid, salts of formic acid, and/or water.
Decomposition type physically active blowing agents that release a gas through
thermal
decomposition include pecan flour, amine%arbon dioxide complexes, and alkyl
alkanoate compounds
especially methyl and ethyl formates.
Generally, the blowing agents of the present invention pose particular
problems in incorporation
into polyester polyol compositions, particularly phthalic-anhydride-initiated
polyester polyols of the present
invention. It is preferred to have the hydrocarbon blowing agent solubilized
or dissolved in the polyol
composition to avoid problems of separation of the hydrocarbon and polyol
component and accumulation
of the hydrocarbon blowing agent in the head space. There is particular concem
with the hydrocarbon
blowing agents conceming an explosion hazard.
Thus, the polyol composition of the present invention further comprises an
oxyethylated fatty acid
or fatty alcohol compatibilizing agent which has an HLB of from about 7 to 12
preferably from,about 8 to
about 11, most preferably from about 8 to about 10.5. This compatibilizing
agent facilitates the
incorporation of the hydrocarbon blowing agents irito the polyol composition
by solubilizing this blowing
agent Into the polyol composition. The compatibilizing agent appears to reduce
the percentage of gas loss
during the foaming process when the hydrocarbori blowing agents of the present
invention are utilized.
CA 02259500 1999-02-08
Suitable compatibilizing agents include the oxyethylated fatty alcohols having
an HLB of from about 7 to
12, preferably from about 8 to about 12, most preferjbly from about 8 to about
11.5. Such oxyethylated
fatty alcohols preferably have an alkyl chain portion having from about 10 to
about 20 carbons. One such
oxyethylated fatty alcohol is ICONOL DA-4 commercially available from BASF
Corporation (Mt. Olive,
New Jersey), which has an average C,o alkyl chain portion, on average four EO
units per molecule and
has an HLB of 10.5. Another such oxyethylated fatty alcohol is ICONOL TDA-3
commercially available
from BASF Corporation, which has an average C13 alcohol chain portion, an
average three EO units per
molecule, and has an HLB of about 8.
Other suitable compatibilizing agents include oxyethlyated fatty acids of the
general formula R,-
COO(EO)xH, including mixtures thereof, wherein Rõ iis a branched or unbranched
aikyl chain, n being the
number of carbon atoms in the alkyl chain which is from about 14 to about 26,
EQ represents an ethylene
oxide unit, and x is from about 5 to about 12. In a preferred embodiment, on
average Rõ is from about a
C16 to about C20 alkyl chain, and x is from about 6 to about 10. Most
preferably the compatibilizing agent
comprises a C18-C20 fatty acid-initiated oxyethylate having an average of
about 8 ethylene oxide units per
molecule. Such compatibilizing agents are commercially available from BASF
Corporation (Mt. Olive, NJ)
as INDUSTROL TFA-8 or MAPEG 400 MOT. BASF Corporation's MAPEG 300 MOT is
also a
suitable compatibilizing agent.
Other suitable compatibilizing agents include the fatty alcohol ethoxylates
having a limited portion
of propylene oxide incorporated into the chemical s4ructure as a heteric
portion with the ethylene oxide in
the compatibilizing agent structure, such as a C1z.15(EOs7PO.,,,1) which is
commercially available as
PLURAFAC 825-5 from BASF Corporation. The amount of propylene oxide should be
limited to the
extent that the above-described HLB values are met, the desired objective of
manufacturing and
dimensionally stable foam having good thermal ins.ulation values, and
optionally, solubilizing the blowing
agent in the polyol composition can be achieved.
Although not intending to be bound by cheory, it is believed that the
predominant factors in
influencing the effectiveness of the compatibilizirig agent to facilitate the
incorporation of the blowing
agent into the polyester polyol composition inrAude the chain length of the
alkyl portion of the
16
CA 02259500 1999-02-08
compatibilizing agent and the HLB of this component. Generally, longer fatty
alkyl chain portions in the
compatibilizing agent provided better capacity to solubilize the hydrocarbon
blowing agent into the
polyester polyol. The content of ethylene oxide in the chemical structure of
the compatibilizing agent is
generally proportional to its ability to solubilize the hydrocarbon blowing
agent.
The amount of a compatibilizing agent required in the polyol composition of
the present invention
will depend largely on the components in the polyol composition particularly
the polyester polyol
component and the blowing agent utilized. The amount of the compatibilizing
agent can be easily
determined by one skilled in the art. Generally, though, a composition
containing cyclopentane as the
blowing agent will require less compatibilizing agent than compositions
containing isopentane or normal
pentane. Preferably, the compatibilizing agent is present in compositions
containing cyclopentane as the
blowing agent in an amount of from about I to about 25, more preferably from
about 5 to about 15, most
preferably from about 7 to about 10 parts by weight, based on 100 parts by
weight of the polyester polyol
in the polyol composition. In compositions containing isopentane or normal
pentane as the blowing agent,
the compatibilizing agent is preferably present in amount of from about 10 to
25, more preferably from 12
to about 22, most preferably from about 15 to about 20 parts by weight, based
on 100 parts by weight of
the polyester polyol in the polyol composition. In cornpositions containing
50/50 blends of cyclopentane
and isopentane or normal pentane as the blowing agent, the compatibilizing
agent will preferably be
present in an amount of from about 5 to 20, more preferably from 5 to about
15, most preferably from
about 8 to about 12 parts by weight, based on 100 parts by weight of the
polyester polyol in the polyol
composition.
At all effective levels of compatibilizing agent, preferably containing from
about I to about 25 parts
by weight of compatibilizing agent based on 100 parts by weight of the
polyester polyol in the polyol
composition, compositions of the present invention experience an improvement
in the percentage of gas
loss during the foaming process as compared to compositions containing no
compatibilizing agent.
Catalysts may be employed which greatly accelerate the reaction of the
compounds containing
hydroxyl groups and with the modified or unmodified ;polyisocyanates. Examples
of suitable compounds
are cure catalysts which also function to shorten tach: time, promote green
strength, and prevent foam
17
CA 02259500 1999-02-08
shrinkage. Suitable cure catalysts are organometailic 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 organometailic: catalysts, exemplified here
by tin as the metal, are
represented by the formula: RnSn[X-Rl-Y]2, wherein R is a C1-Cg alkyl or aryl
group, R1 is a CO-C18
methylene group optionally substituted or branched with a C1-C4 alkyl group, Y
is hydrogen or a hydroxyl
group, preferably hydrogen, X is methylene, an -S-, an -SR2COO-, -SOOC-, an -
03S-, or an -OOC- group
wherein R2 is a C1-C4 alkyl, n is 0 or 2, provided that R1 is CO only when X
is a methylene group.
Specific examples are tin (ll) acetate, tin (li) 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-BC) tin (IV) salts of inorganic compounds
such as butyltin trichloride,
dimethyl- and diethyl- and dibutyl- and dioctyl- and diphenyl- 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. A suitable catalyst in
compositions of the present
invention is K Hex Cem 977 which is a potassium octoate catalyst in a glycol
(DPG) carrier commercially
available from M & T Chemicals.
Tertiary amines also promote urethane 9inkage formation, and include
triethylamine, 3-
methoxypropyidimethylamine, triethylenediamine, tributylamine,
dimethylbenzylamine, N-methyl-, N-ethyl-
and N-cyclohexylmorpholine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-
tetramethylbutanediamine
or -hexanediamine, N,N,N'-trimethyl isopropyl propylenediamine,
pentamethyldiethylenetriamine,
tetramethyidiaminoethyl ether, bis(dimethyiaminopropyl)urea,
dimethylpiperazine, 1-methyl-4-
dimethylaminoethylpiperazine, 1,2-dimethylimidazole, 1-azabicylo[3.3.0]octane
and preferably 1,4-
diazabicylo[2.2.2]octane, and alkanolamine compounds, such as triethanolamine,
trilsopropanolamine, N-
methyl- and N-ethyldiethanolamine and dimethylethanolamine.
18
CA 02259500 2005-05-25
To prepare the polyisocyanurate (PIR) and PUR-PIR foams by the
process according to the invention, a polyisocyanurate catalyst is employed.
Suitable polyisocyanurate catalysts are alkali salts, for example, sodium
salts,
preferably potassium salts and ammonium salts, of organic carboxylic acids,
expediently having from I to 8 carbon atoms, preferably 1 or 2 carbon atoms,
for
example, the salts of formic acid, acetic acid, propionic acid, or octanoic
acid,
and tris(dialkylaminoethyl)-, tris(dimethylaminopropyl)-,
tris(dimethylaminobutyl)-
and the corresponding tris(diethylaminoalkyl)-s-hexahydrotriazines. However,
(trirnethyl-2-hydroxypropyl)ammonium formate, (trimethyl-2-hydroxypropyl)
ammonium octanoate, potassium acetate, potassium octoate potassium formate
and tris(dimethylaminopropyl)-s-hexahydrotriazine are polyisocyanurate
catalysts which are generally used. The suitable polyisocyanurate catalyst is
usually used in an amount of from I to 10 parts by weight, preferably from 1.5
to
8 parts by weight, based on 100 parts by weight of the total amount of
polyols.
Urethane-containing foams may be prepared with or without the use of
chain extenders and/or crosslinking agents, which are not necessary in this
invention to achieve the desired mechanical hardness and dimensional
stability.
The chain extenders and/or crosslinking agents used have a relatively low
molecular weight corresponding to a number average molecular weight of less
than 400, preferably from 60 to 300; or if the chain extenders have
polyoxyalkylene groups, then having a relatively low molecular weight
corresponding to a number average molecular weight of less than 200.
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.
Polyurethane foams can also be prepared by using secondary aromatic
diamines, primary aromatic diamines, 3,3'-di- and/or 3,3'-, 5,5'-tetraalkyl-
19
CA 02259500 2005-05-25
substituted diaminodiphenylmethanes as chain extenders or crosslinking agents
instead of or mixed with the above-mentioned diols and/or triols.
The amount of chain extender, crosslinking agent or mixture thereof
used, if any, is expediently from 2 to 20 percent by weight, preferably from I
to
15 percent by weight, based on the weight of the polyol composition. However,
as previously alluded to, it is preferred that no chain extender/crosslinker
is
19a
CA 02259500 1999-02-08
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 can be incorporated into the reaction
mixture for the
production of the cellular plastics by the polyisocyariate polyaddition
process. Specific examples include
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 regulate the
cell structure of the
plastics by helping to control the cell size in the foarri and reduce the
surface tension during foaming via
reaction of the polyol composition with an organic isocyanate as described
herein.
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
afkyl-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, and
dimethylpolysiloxanes. Preferred
surfactants include the silicone-containing surfactarit polymers. 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. A suitable
surfactant in compositions of the present invention comprises Tegostab B-8462
silicone surfactant
commercially available from Goldschmidt Company.
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, hornblerids, amphiboles,
chrysotile, and talc; metal oxides,
such as kaolin, aluminum oxides, titanium oxides and iron oxides; metal salts,
such as chalk, barite and
inorganic pigments, such as cadmium sulfide, zinc sulfide and glass, inter
alia; kaolin (china clay),
aluminum silicate and co-precipitates of barium sulfate and aluminum silicate,
and natural and synthetic
fibrous minerpls, 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
CA 02259500 2005-05-25
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 polyol composition 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. A suitable flame retardant in compositions of the
present invention comprises FYROL PCF, which is a tris(chloro
propyl)phosphate commercially available from Albright & Wilson.
In addition to the above-mentioned halogen-substituted phosphates, it is
also possible to use inorganic or 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 5 to 25 parts by weight, of said flameproofing agents may be
used per 100 parts by weight of the polyol composition.
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, 1 st and 2nd Editions, 1966 and 1983.
Suitable organic polyisocyanates, defined as having 2 or more
isocyanate functionalities, are conventional aliphatic, cycloaliphatic,
araliphatic
21
CA 02259500 2005-05-25
and preferably aromatic isocyanates. Specific examples include: alkylene
diisocyanates with 4 to 12 carbons in the alkylene radical such as 1,12-
dodecane
!
f
21a
CA 02259500 1999-02-08
diisocyanate, 2-ethyl-1,4-tetramethylene diisocyanate, 2-methyl-1,5-
pentamethylene diisocyanate, 1,4-
tetramethylene diisocyanate and preferably 1,6-hexarriethylene dilsocyanate;
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-isocyanatomethylcyclohexane (isophorone diisocyanate), 2,4-
and 2.6-hexahydrotoluene
diisocyanate as well as the corresponding isomeric mixtures, 4,4'- 2,2'-, and
2,4'-dicyclohexylmethane
diisocyanate as well as the corresponding isomeric rriixtures and preferably
aromatic diisocyanates and
poiyisocyanates 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 polyisocyanates
can be used individually or in the form of mixtures. Particularly preferred
for the production of rigid foams
is crude MDI containing about 50 to 70 weight percent polyphenyl-polymethylene
polyisocyanate and from
30 to 50 weight percent diphenylmethane diisocyanate, based on the weight of
all polyisocyanates used.
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'-
22
CA 02259500 1999-02-08
diphenylmethane diisocyanate, 2,4,- and/or 2,6-toluene diisocyanates or
polymeric MDI are also suitable.
Furthermore, liquid polyisocyanates containing carbodiimide groups having 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 MDI, 2,4'- and/or
2,6-toluene diisocyanate.
The organic isocyanates used in the invention preferably have an average
functionality of greater
than 2, most preferably 2.5 or more. This provides for a greater crosslinking
density in the resulting foam,
which improves the dimensional stability of the foam.
To produce the rigid closed cell polyurethane foams of the present invention,
the organic
polyisocyanate and the isocyanate reactive compounds are reacted in such
amounts that the isocyanate
index, defined as the number of equivalents of NCO groups divided by the total
number of isocyanate
reactive hydrogen atom equivalents multiplied by 100, ranges from about 80 to
less than about 150,
preferably from about 90 to 110. The polyol composition of the invention
provides flexibility in the
processing window in that the solubility of the polyol composition and the
dimensional stability and
thermal insulation of the resulting foam are substantially unaffected
throughout a wide range of isocyanate
indices. If the rigid foams contain, at least in part, bonded isocyanurate
groups, an isocyanate index of
150 to 6000, preferably from 200 to 800, is usually used.
In a method of the Invention, there is provided the reaction of an organic
isocyanate with a
polyester polyol composition wherein the polyol composition comprises:
a) a phthalic anhydride polyester polyol preferably having a hydroxyl number
of
200 meq. polyol/g KOH or more.
b) a blowing agent selected from the group consisting C4-C6 hydrocarbons and
mixtures thereof; and
c) an oxyethyfated fatty acid or fatty alcohol compatibilizing agent having an
HLB qf from about 7
to about 12.
23
CA 02259500 1999-02-08
Optionally, but preferably, the hydrocarbon based blowing agent is dissolved
in the polyol
composition. In one embodiment, the polyol composition contains the blowing
agent in solution prior to
reaction with the organic isocyanate. Preferably, the organic isocyanate and
the polyol composition are
reacted at isocyanate indices ranging from 80 to 350. All throughout this
range the K-factors of the foam
are substantially constant and the foams are dimensionally stable. A
substantially constant K-factor value
means that the variance in values is tl0 percent or less between the lowest
and highest values within the
range. Throughout the range, the foam also remains dimensionally stable as
defined below. The
measurements for the K-factor are taken from core samples as described below
in the definition of a
dimensionally stable foam and are the initial K-factors.
The rigid foams made from polyisocyanate polyaddition products are
advantageously produced
by the one-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 become a part
of the finished artide. In a
preferred embodiment, rigid foams may be made in a continuous laminate
process, which process is well
know in the industry.
The starting components may be mixed at from 15 C to 90 C, preferably from 20
C to 35 C, and
introduced into the open or Gosed mold, if desired under super-atmospheric
pressure. The mixing of the
isocyanate with the polyol composition containing dissolved blowing agent 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 temperature is expediently from 2:0 C to 110 C, preferably
from 30 C to 60 C, in
particular from 45 C to 50 C.
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
automotive, aircraft, and ship building
industries-- and in the fumiture and sports goods industries. They are
particularly suitable in the
construction and refrigeration sectors as thermal insulators, for example, as
intermediate layers for
laminate board or for foam-filling refrigerators, freezer housings, and picnic
coolers.
For pour-in-place applications, the rigid foani may be poured or injected to
form a sandwich
24
CA 02259500 1999-02-08
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 formed sheet metal such as used in the case of
refrigeration cabinets;
wood, including composite wood; acrylonitrile-butadiene-styrene (ABS) triblock
of rubber, optionally
modified with styrene-butadiene diblock, sryrene-ethylene/butylene-styrene
triblock, optionally
functionalized with maleic anhydride and/or maleic acid, polyethylene
terephthalate, polycarbonate,
polyacetals, rubber modified high impact polystyrene (HIPS). blends of HIPS
with polyphenylene oxide,
copolymers of ethylene and vinyl acetate, ethylene 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 aluminum, tin, ABS, HIPS,
polyethylene, and high density
polyethylene.
The polyurethane foam may be contiguous to and bonded to the inner surfaces of
the first and
l 5 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 foamAayer 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 substrate of choice.
When a synthetic plastic material such as polyethylene having few or no
bonding or adh8sion
sites is chosen as the first and/or second substrate as an altemative 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
CA 02259500 1999-02-08
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 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 refrigeration unit or a cooler container, such as
a picnic cooler, a
thermoformed inner liner material is inserted into the outer shell of cooler
or the refrigeration cabinet, 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 poiyurethane cellular products of the invention are rigid, meaning that
the ratio of tensile
strength to compressive strength is high, on the order of 0.5:1 or greater,
and having less than 10 percent
elongation. The foams are also dosed cell, meaning that the number of open
cells is 20% or less, or
conversely the number of closed celis is 80% or greater, the measurement being
taken on a molded foam
packed at 10% over the theoretical amount required to fill the mold with foam.
The rigid polyurethane cellular products of the invention are dimensionally
stable, exhibiting little
or no shrinkage, even at free rise densities of 2.0 pcf 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 2.0 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 28
days of exposure: at 100
F/100 percent RH, i.e., relative humidity, no more than 5 percent, more
preferably no more than t 3
percent; at 158 F/100 percent RH no more than 16 percent, most preferably less
than * 4 percent; at 158
F, dry no more than 8 percent, preferably no more than 6 percent; at 200
F, dry no more than 5,
preferably no more than 3 percent; and at -20 F after 7 days exposure no more
than 5 percent,
preferably no more than t 3 percent.
The thermal insulation values of the rigid Gosed cell foams according to the
preferred
embodiments of the invention are 0.160 BTU-in./hr.-ft2-F or less initial, more
preferably 0.150 or less
initial, measured from the core of a 10% overpacked sample. It has been found
that foams made with the
phthalic-anhydride-initiated polyester polyols exhibit relatively low k-
factors.
26
CA 02259500 1999-02-08
In a preferred embodiment, the rigid polyurethane foams are also
advantageously not friable at
their surface in spite of their low density and the pre:sence of polyols
having a high hydroxyl number and
lowrequivalent weight. These foams typically exhibit a surface friability of
less than 5 percent when tested
according to ASTM C 421, at core densities of 2.0 pcf or less, even at core
densities of 1.5 pcf or less.
The low surface friability enables the foam to adhere well to substrates.
The term polyisocyanate based foam as used herein is meant to include
polyurethane-polyurea,
polyurethane-polyisocyanurate, polyurethane, and polyisocyanurate foams.
The following examples illustrate the nature of the invention with regard to
the formation of stable
polyester polyol compositions and the resulting isocyanate-based rigid foam
prepared therefrom. The
examples presented herein are intended to demons-itrate the objects of the
invention but should not be
considered as limitations thereto. Unless otherwise indicated, all parts are
expressed in parts by weight.
EXAMPLES
Isocyanate A is a polymethylene polyphenylene polyisocyanate having a free NCO
content of about 31
percent, a nominal functionality of about 3 and a viscosity of 700 cP at 25 C.
Polyester Polyol is a phthalic anhydride-initiated polyester polyol having a
nominal functionality of about 2
and hydroxyl number of about 240.
Flame Retardant is a tris(chloro propyl)phosphate.
Surfactant is a silicone surfactant polymer.
Catalyst is a potassium octoate catalyst in a dipropylerie glycol carrier.
Compatibilizer is a long chain fatty acid initiated oxyethylate having on
average about 8 ethylene oxide
units per molecule and an HLB of about 10.
Commercial cyclopentane is a product containing between about 80 and 85%
cyclopentane isomer which
is commercially available from Phillips 66 Company.
Pure cyclopentane is a high purity reagant grade cyclopentane product
commercially available from
Exxon Corporation containing greater than about 90% cyclopentane Isomer.
Procedure for Resin Blend: The amount of polyester polyol is weighed and
placed into a glass bottle. The
desired quantity of surfactant, catalyst, compatiblizer and flame retardant
are added into the glass botUe
27
CA 02259500 1999-02-08
container. Generally, the components may be added iin any order. The desired
amount of hydrocarbon
blowing agent is dispensed into the glass container. The contents are sealed
by tightening the cap on the
bottle. The contents are then mixed by vigorously shakiing the bottle. The
contents are allowed to remain
at rest for 5 days at room temperature without agitation. If upon visual
inspection there is no phase
separation (clear resin blend) such that two discrete iiayers are formed, the
blowing agent is deemed
soluble in the polyol composition, and the polyol composition is deemed
storage stable.
Procedure forproduction of Polyurethane Foam: The polyol composition is then
reacted with an amount of
lsocyanate A at a foam index ratio of 300 such that the calculated ratio of
NCO groups in the isocyanate is
three times the number of hydroxyl groups in the resin c:omponents. The
isocyanate is mixed and reacted
with the resin blend at about room temperature using a high speed propeller
mixer. Gas loss for these
handmixes is determined according to the following procedure.
Procedure for gas loss determination: Supplies required; polypropylene tubs
(approximately 8" in diameter
and 10" in height) with Y~" drain tubes located about %z below the open rim of
the tub; laboratory balance;
barometer; thermometer; water, and foam mixing equipment (high speed propeller
mixer). Place a
polypropylene tub on the laboratory balance and tare 'the balance. Fiii the
polypropylene tub with water
above the drain tube and allow it to drain until draining stops. Record the
water weight needed to fill the
tub. Record the water temperature. Repeat at least tc:n times and calculate
the average water weight
needed to fill the tub. Empty the water from the tub and dry it out. Coat the
inside of the tub with a release
agent, such as paste wax to ease removal of foam. Place the tub on the balance
and tare the balance.
Mix a foam handmix using normal laboratory technique. Pour approximately 200
grams of mixed foam into
a polypropylene tub and immediately record the weight of the foam before it
starts to rise. Note: Exact
weights are not critical in this operation, speed is. Dump the foam quickly
into the tub and read the weight
of the liquid on the balance as quickly as possible. Allow the foam to rise in
the tub. Note: The foam
should not rise above the level of the drain tube. After several minutes, the
foam weight will stabilize,
Record this value. Tare the balance to zero. Fill the tub with water above the
drain tube and allow it to
drain until it stops. Record the weight of the water in the tub. Record the
water temperature. Remove foam
from the tub. Measure and record the barometric pressure, the ambient air
temperature and the wet bulb
28
w
CA 02259500 1999-02-08
0 0 0 q
oi LLI
N pO' 0 N N
r r v;
N
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p o ni cV =- '
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r o p N N N r 1
'~ ~ ~ N N ~ N O E
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u7 '
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W G~ p0 O N N Ej =~- ? d CV
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ul) E
a N
p 0 O N N .f'f õ-; --,~ N O~ m
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M
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~ N M ~ N Z C to ~ X
r r 2
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= o o .f, o vi v
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y 0
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0 p O '~i O . y~ M z a (6
~ 0 O ~y ~1 O N Y 1 ' LL
r E ~ ~ s
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y ~ K I ,
p r GV N O N
cn $
N o o N N vi N 0
e '-' v II
Ln
= o .rf 9
~ } a W tL
h o Q W 0
z W~~'' 0
2 Z ~ N
~ a
~ o a N ~ ~ Z z 0. Z w W Q ~
c~ ~ w
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CA 02259500 1999-02-08
temperature. Calculate the gas loss for each foam using the equations
appearing below Table 1.
Results: Samples 2; and 4; and 6-9; and 11-14; and 16-17; and 19-20 exhibit an
improvement in
percentage of gas loss during the process of producing a polyurethane foam
over Samples 1; and 3;
and 5; and 10; and 15; and 18, respectively. Further, Table 1 demonstrates the
approximate level of
compatibilizing agent required for the compositions displayed using different
blowing agents to
provide a storage stable polyester poiyol composition in accordance with the
present invention.
