Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Producing rigid polyurethane foams
Description
The present invention relates to a process for producing rigid polyurethane
foams. The
present invention also relates to the thus obtainable rigid foams themselves
and also to
their use for production of sandwich elements having rigid or flexible outer
layers. The
present invention further relates to the polyol component used for producing
the rigid
polyurethane foams.
Producing rigid polyurethane foams by reacting organic or modified organic di-
or
polyisocyanates with relatively high molecular weight compounds having at
least two
reactive hydrogen atoms, especially with polyether polyols from alkylene oxide
polymerization or polyester polyols from condensation polymerization of
alcohols with
dicarboxylic acids in the presence of polyurethane catalysts, chain-extending
and/or
crosslinking agents, blowing agents and further auxiliary and addition agents
is known and
is described in numerous patent and literature publications. WO 2007/025888
for example
describes producing rigid polyurethane foams.
Rigid polyurethane foams frequently display a high degree of brittleness on
cutting to size
with severe evolution of dust and high sensitivity on the part of the foams.
This can lead to
cracking in the foam on sawing, especially in composite elements with metallic
outer layers
and a core of polyisocyanurate foam. At higher mixing ratios, the brittleness
of
polyisocyanu rate (PIR) foams and hence the cracking tendency increase.
A further disadvantage of polyester polyols based on aromatic carboxylic acids
or aromatic
carboxylic acid derivatives such as terephthalic acid or phthalic anhydride is
often their
high viscosity, since it makes the mixing with the isocyanate component
distinctly more
difficult.
In addition, problems with unsatisfactory dimensional stability, i.e., the
foam product
distorts significantly after removal from the mold or after the pressure
section when
processed by the double belt process, can occur in certain systems for
producing rigid PU
foams, for example when using glycerol as relatively high-functionality
alcoholic polyester
component.
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The problem of the behavior of rigid PU foams in the event of a fire has
hitherto also not
been satisfactorily solved for all systems. For example, a toxic compound can
form in the
event of a fire when using trimethylolpropane (TMP) as relatively high-
functionality
alcoholic polyester component.
A general problem in the production of rigid foams is the formation of surface
defects,
particularly at the interface with metallic outer layers. These foam surface
defects cause
formation of an uneven metal surface in sandwich elements and thus often lead
to visual
unacceptability of the product. An improvement in the foam surface reduces the
frequency
of the occurrence of such surface defects and thus leads to a visual
improvement in the
surface of sandwich elements.
It is further generally desirable to provide systems having a very high self-
reactivity in
order that the use of catalysts may be minimized.
The invention has for its object to provide a polyol component that has a high
self-
reactivity. The present invention further has for its object to provide rigid
PU foams of low
brittleness which are not prone to cracking when composite elements are sawn.
In
addition, the rigid PU foams shall display improved curing characteristics.
The components used and the blends produced therefrom shall further be of low
viscosity
in order to be readily meterable and mixable in the production of rigid PU
foams.
Furthermore, the solubility of blowing agents, as for example the solubility
of pentane in
the polyol component, shall be very good.
The invention further has for its object to improve the dimensional stability
of rigid PU
foams. The formation of toxic compounds in the event of fire shall be very
low.
Furthermore, the formation of surface defects shall be reduced.
We have found that this object is achieved by a process for producing rigid
polyurethane
foams by reaction of
A) one or more organic polyisocyanates,
B) one or more polyester polyols,
C) optionally one or more polyether polyols,
D) a flame-retardant mixture,
E) further auxiliaries or addition agents,
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F) one or more blowing agents, and also
G) catalysts,
wherein said flame-retardant mixture D) comprises
dl) 10 to 90 wt%, based on the amount of flame-retardant mixture, of a
flame retardant
having a boiling point of not more than 220 C, and
d2) 10 to 90 wt%, based on the amount of flame-retardant mixture, of a
phosphorus-
containing flame retardant having a boiling point of above 220 C,
wherein said components dl) and d2) total 100 wt%.
The present invention also provides a polyol component comprising the
aforementioned
components B) to G). In general, the mass ratio of polyester polyol component
B) to
polyether polyol component C) is at least 1.
The present invention further provides rigid polyurethane foams obtainable by
the process
of the present invention and also their use for production of sandwich
elements having
rigid or flexible outer layers. Rigid polyurethane foams also subsume rigid
polyisocyanurate foams. These are specific forms of rigid polyurethane foams.
The invention will now be more particularly elucidated.
Component B
In the context of the present disclosure, the terms "polyester polyol" and
"polyesterol" are
interchangeable, as are the terms "polyether polyol" and "polyetherol".
Useful polyester polyols B) are obtainable for example from dicarboxylic acids
having 2 to
12 carbon atoms, preferably aromatic dicarboxylic acids or mixtures of
aromatic and
aliphatic dicarboxylic acids and polyhydric alcohols, preferably diols, having
2 to 12 carbon
atoms, preferably 2 to 6 carbon atoms.
Possible dicarboxylic acids are in particular: succinic acid, glutaric acid,
adipic acid,
suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, maleic
acid, fumaric acid,
phthalic acid, isophthalic acid and terephthalic acid. The dicarboxylic acids
can be used
either individually or in admixture with one another. It is also possible to
use the derivatives
of these dicarboxylic acids, such as for example dimethyl terephthalate. It is
also possible
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to use the corresponding dicarboxylic acid derivatives, e.g. dicarboxylic
esters of alcohols
having from 1 to 4 carbon atoms or dicarboxylic anhydrides, in place of the
free
dicarboxylic acids. As aromatic dicarboxylic acids, preference is given to
using phthalic
acid, phthalic anhydride, terephthalic acid and/or isophthalic acid as a
mixture or alone. As
aliphatic dicarboxylic acids, preference is given to using dicarboxylic acid
mixtures of
succinic, glutaric and adipic acid in weight ratios of, for example, 20-35:35-
50:20-32 parts
by weight and in particular adipic acid. Examples of dihydric and polyhydric
alcohols, in
particular dials, are: ethanediol, diethylene glycol, 1,2- or 1,3-propanediol,
dipropylene
glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,10-decanediol,
glycerol,
trimethylolpropane and pentaerythritol. Preference is given to using
ethanediol, diethylene
glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol or mixtures of at
least two of the
dials mentioned, in particular mixtures of 1,4-butanediol, 1,5-pentanediol and
1,6-hexanediol. It is also possible to use polyester polyols derived from
lactones, e.g.
c-caprolactone, or hydroxycarboxylic acids, e.g. w-hydroxycaproic acid.
To prepare the further polyester polyols B), bio-based starting materials
and/or derivatives
thereof are also suitable, for example, castor oil, polyhydroxy fatty acids,
ricinoleic acid,
hydroxyl-modified oils, grapeseed oil, black cumin oil, pumpkin kernel oil,
borage seed oil,
soybean oil, wheat germ oil, rapeseed oil, sunflower oil, peanut oil, apricot
kernel oil,
pistachio oil, almond oil, olive oil, macadamia nut oil, avocado oil, sea
buckthorn oil,
sesame oil, hemp oil, hazelnut oil, primula oil, wild rose oil, safflower oil;
walnut oil, fatty
acids, hydroxyl-modified fatty acids and fatty acid esters based on
myristoleic acid,
palmitoleic acid, oleic acid, vaccenic acid, petroselic acid, gadoleic acid,
erucic acid,
nervonic acid, linoleic acid, a- and y-linolenic acid, stearidonic acid,
arachidonic acid,
timnodonic acid, clupanodonic acid and cervonic acid.
Preferably, the polyester component B) comprises at least one polyetherester
polyol
comprising the esterification product of
b1) 10 to 70 mol% of a dicarboxylic acid composition comprising
b11) 50 to 100 mol%, based on the dicarboxylic acid composition, of one or
more
aromatic dicarboxylic acids or derivatives thereof,
b12) 0 to 50 mol%, based on said dicarboxylic acid composition b1), of one or
more
aliphatic dicarboxylic acids or derivatives thereof,
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b2) 2 to 30 mol% of one or more fatty acids and/or fatty acid derivatives,
b3) 10 to 70 mol% of one or more aliphatic or cycloaliphatic dials having 2
to 18 carbon
atoms or alkoxylates thereof,
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b4) 2 to 50 mol% of a polyether polyol having a functionality of not less than
2, prepared
by alkoxylating a polyol having a functionality of not less than 2,
all based on the total amount of components b1) to b4), wherein said
components b1) to
b4) sum to 100 mol%.
Preferably, the component b11) comprises at least one compound selected from
the group
consisting of terephthalic acid, dimethyl terephthalate (DMT), polyethylene
terephthalate
(PET), phthalic acid, phthalic anhydride (PA) and isophthalic acid. More
preferably, the
component b11) comprises at least one compound from the group consisting of
terephthalic acid, dimethyl terephthalate (DMT), polyethylene terephthalate
(PET) and
phthalic anhydride (PA). Even more preferably, the component b11) comprises
phthalic
anhydride, dimethyl terephthalate, terephthalic acid or mixtures thereof. The
aromatic
dicarboxylic acids or their derivatives of component b11) are more preferably
selected
from the aforementioned aromatic dicarboxylic acids, and dicarboxylic acid
derivatives,
respectively, and specifically from terephthalic acid and/or dimethyl
terephthalate (DMT).
Terephthalic acid and/or DMT in component b11) leads to polyetherester polyols
B) having
particularly good fire protection properties.
The proportion in which aliphatic dicarboxylic acids or dicarboxylic acid
derivatives
(component b12)) are comprised in the dicarboxylic acid composition b1) is
generally in
the range from 0 to 30 mol% and preferably in the range from 0 to 10 mol%. It
is
particularly preferable for the dicarboxylic acid composition b1) to comprise
no aliphatic
dicarboxylic acids or derivatives thereof and thus to consist to an extent of
100 mol% of
one or more aromatic dicarboxylic acids or their derivatives, in which case
the
aforementioned ones are preferred. Useful derivatives are generally the
esters, preferably
C1.6-alkyl esters, especially the methyl esters of the dicarboxylic acids.
The amounts in which component b2) is used are preferably in the range from 3
to
.. 20 mol% and more preferably in the range from 5 to 18 mol%.
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The amounts in which component b3) is used are preferably in the range from 20
to
60 mol%, more preferably in the range from 25 to 55 mol% and even more
preferably in
the range from 30 to 45 mol%.
The amounts in which component b4) is used are preferably in the range from 2
to
40 mol%, more preferably in the range from 8 to 35 mol% and even more
preferably in the
range from 15 to 25 mol%.
In one preferred embodiment of the present invention, the amine catalyst for
producing the
component b4) is selected from the group comprising dimethylethanolamine
(DMEOA),
imidazole and imidazole derivatives and also mixtures thereof, more preferably
imidazole.
In one embodiment of the invention, the fatty acid or fatty acid derivative
b2) consists of a
fatty acid or fatty acid mixture, one or more glycerol esters of fatty acids
or, respectively, of
fatty acid mixtures and/or one and more fatty acid monoesters, for example
biodiesel or
methyl esters of fatty acids, and it is particularly preferable for component
b2) to consist of
a fatty acid or fatty acid mixture and/or one or more fatty acid monoesters
and it is more
preferable for the component b2) to consist of a fatty acid or fatty acid
mixture and/or
biodiesel, and it is most preferable for the component b2) to consist of a
fatty acid or fatty
acid mixture.
In one preferred embodiment of the invention, the fatty acid or fatty acid
derivative b2) is
selected from the group consisting of castor oil, polyhydroxy fatty acids,
ricinoleic acid,
hydroxyl-modified oils, grapeseed oil, black cumin oil, pumpkin kernel oil,
borage seed oil,
soybean oil, wheat germ oil, rapeseed oil, sunflower oil, peanut oil, apricot
kernel oil,
pistachio oil, almond oil, olive oil, macadamia nut oil, avocado oil, sea
buckthorn oil,
sesame oil, hemp oil, hazelnut oil, primula oil, wild rose oil, safflower oil,
walnut oil, animal-
based tallow, for example beef tallow, fatty acids, hydroxyl-modified fatty
acids and fatty
acid esters based on myristoleic acid, palmitoleic acid, oleic acid, vaccenic
acid, petroselic
acid, gadoleic acid, erucic acid, nervonic acid, linoleic acid, a- and y-
linolenic acid,
stearidonic acid, arachidonic acid, timnodonic acid, clupanodonic acid and
cervonic acid.
In a further preferred embodiment of the present invention, the fatty acid or
fatty acid
derivative b2) is oleic acid, biodiesel, soybean oil, rapeseed oil or tallow,
more preferably
oleic acid, soybean oil, rapeseed or beef tallow and specifically oleic acid.
The fatty acid or
fatty acid derivative serves to improve inter alia the blowing agent
solubility in the
production of polyurethane foams. It is very particularly preferable for
component b2) not
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to comprise any triglyceride, especially no oil or fat. The glycerol released
from the
triglyceride by the esterification/transesterification has a detrimental
effect on rigid foam
dimensional stability, as mentioned above. Preferred fatty acids and fatty
acid derivatives
in the context of component b2) are therefore the fatty acids themselves and
also alkyl
monoesters of fatty acids or alkyl monoesters of fatty acid mixtures,
especially the fatty
acids themselves and/or biodiesel.
Preferably the aliphatic or cycloaliphatic diol b3) is selected from the group
consisting of
ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 1,4-
butanediol,
1,5-pentanediol, 1,6-hexanediol, 2-methyl-1,3-propanediol and 3-methyl-1,5-
pentanediol
and alkoxylates thereof. It is particularly preferable for the aliphatic dial
b3) to be
monoethylene glycol or diethylene glycol, especially diethylene glycol.
Preferably, a polyether polyol b4) is used having a functionality above 2,
which was
prepared by alkoxylating a polyol having a functionality of not less than 3.
In general, the polyether polyol b4) has a functionality greater than 2. It
preferably has a
functionality of not less than 2.7 and especially of not less than 2.9. In
general, it has a
functionality of not more than 6, preferably not more than 5 and more
preferably not more
than 4.
In one embodiment of the present invention, the polyether polyol b4) is
obtainable by
reacting a polyol having a functionality of greater than 2 with ethylene oxide
and/or
propylene oxide, preferably with ethylene oxide.
In a further preferable embodiment, the polyether polyol b4) is obtainable by
alkoxylating,
preferably ethoxylating, a polyol selected from the group consisting of
sorbitol,
pentaerythritol, trimethylolpropane, glycerol, polyglycerol and mixtures
thereof, more
preferably a polyol selected from the group consisting of trimethylolpropane
and glycerol.
In one particularly preferable embodiment, the polyether polyol b4) is
obtainable by
alkoxylation with ethylene oxide, leading to rigid polyurethane foams having
improved fire
protection properties.
In one particularly preferred embodiment of the present invention, the
component b4) is
prepared by anionic polymerization of propylene oxide or ethylene oxide,
preferably
ethylene oxide, in the presence of alkoxylation catalysts, such as alkali
metal hydroxides,
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such as sodium hydroxide or potassium hydroxide, or alkali metal alkoxides,
such as
sodium methoxide, sodium ethoxide, potassium ethoxide or potassium
isopropoxide, or
aminic alkoxylation catalysts, such as dimethylethanolamine (DMEOA), imidazole
and
imidazole derivatives and also mixtures thereof by using at least one starter
molecule.
KOH and aminic alkoxylation catalysts are preferred alkoxylation catalysts.
Since the
polyether first has to be neutralized when KOH is used as alkoxylation
catalyst and the
potassium salt produced has to be removed before the polyether can be used in
the
esterification as component b4), the use of aminic alkoxylation catalysts is
preferred.
Preferred aminic alkoxylation catalysts are selected from the group comprising
dimethylethanolamine (DMEOA), imidazole and imidazole derivatives and also
mixtures
thereof, more preferably imidazole.
In one advantageous embodiment of the invention, the polyether polyol b4)
consists of the
reaction product of glycerol with ethylene oxide and/or propylene oxide,
preferably with
ethylene oxide. As a result, the storage stability of component B) is
particularly high.
In a further advantageous embodiment of the invention, the polyether polyol
b4) consists
of the reaction product of trimethylolpropane with ethylene oxide and/or
propylene oxide,
preferably with ethylene oxide. Again the result is a particularly high
improved storage
stability for component B).
Preferably, the polyether polyol b4) has an OH number in the range from 150 to
1250 mg
KOH/g, preferably in the range from 300 to 950 mg KOH/g and more preferably in
the
range from 500 to 800 mg KOH/g.
In a further preferred embodiment, at least 200 mmol, preferably at least 400
mmol, more
preferably at least 600 mmol, even more preferably at least 800 mmol and most
preferably
at least 1000 mmol of component b4) are used per kg of component B).
In a particularly preferred embodiment of the invention, the polyether polyol
b4) consists of
the reaction product of trimethylolpropane or glycerol, preferably glycerol,
with ethylene
oxide, wherein the OH number of the polyether polyol b4) is in the range from
500 to 800
mg KOH/g, preferably 500 to 650 mg KOH/g, and imidazole is used as
alkoxylation
catalyst.
In an especially preferred embodiment of the invention, the polyether polyol
b4) consists of
the reaction product of trimethylolpropane or glycerol, preferably glycerol,
with ethylene
oxide, wherein the OH number of the polyether polyol b4) is in the range from
500 to 800
mg KOH/g, preferably 500 to 650 mg KOH/g, imidazole is used as alkoxylation
catalyst,
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and the aliphatic or cycloaliphatic diol b3) is diethylene glycol, and the
fatty acid or the fatty
acid derivative b2) is oleic acid.
Preferably, the polyetherester polyol B) has a number-weighted average
functionality of
not less than 2, preferably of greater than 2, more preferably greater than
2.2 and
especially greater than 2.3, leading to a higher crosslink density on the part
of the
polyurethane prepared therewith and hence to better mechanical properties on
the part of
the polyurethane foam.
To prepare the polyetherester polyols B), the aliphatic and aromatic
polycarboxylic acids
and/or derivatives and polyhydric alcohols can be polycondensed in the absence
of
catalysts or preferably in the presence of esterification catalysts,
advantageously in an
atmosphere of inert gas, e.g. nitrogen, in the melt at temperatures of from
150 to 280 C,
preferably from 180 to 260 C, optionally under reduced pressure, to the
desired acid
number which is advantageously less than 10, preferably less than 2. In a
preferred
embodiment, the esterification mixture is polycondensed at the abovementioned
temperatures to an acid number of from 80 to 20, preferably from 40 to 20,
under
atmospheric pressure and subsequently under a pressure of less than 500 mbar,
preferably from 40 to 400 mbar. Possible esterification catalysts are, for
example, iron,
cadmium, cobalt, lead, zinc, antimony, magnesium, titanium and tin catalysts
in the form of
metals, metal oxides or metal salts. However, the polycondensation can also be
carried
out in the liquid phase in the presence of diluents and/or entrainers such as
benzene,
toluene, xylene or chlorobenzene in order to distill off the water of
condensation as an
azeotrope.
To produce the polyetherester polyols, the organic polycarboxylic acids and/or
derivatives
and polyhydric alcohols are advantageously polycondensed in a molar ratio of
1:1-2.2,
preferably 1:1.05-2.1 and particularly preferably 1:1.1-2Ø
The polyetherester polyols obtained generally have a number average molecular
weight in
the range from 300 to 3000, preferably in the range from 400 to 1000 and
especially in the
range from 450 to 800.
The proportion of polyester polyols B) is generally at least 10 wt%,
preferably at least 20
wt% and more preferably at least 40 wt% and especially preferably at least 50
wt%, based
on total components B) to G).
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Producing rigid polyurethane foams by the process of the present invention, in
addition to
the specific polyester polyols (polyetherester polyols) described above,
utilizes the
conventional construction components, about which the following details may be
provided.
5 In addition to the polyetherester polyols, further polyester polyols may
be present. In
general, the mass ratio of polyetherester polyols to the further polyester
polyols is at least
0.1, preferably at least 0.25, more preferably at least 0.5 and especially at
least 0.8. In a
particularly preferred embodiment, it is exclusively polyetherester polyols
from components
b1) to b4) which are used as component B).
Component A
Polyisocyanate for the purposes of the present invention is to be understood
to be
referring to an organic compound comprising at least two reactive isocyanate
groups per
molecule, i.e., the functionality is at least 2. When the polyisocyanates used
or a mixture of
two or more polyisocyanates do not have a unitary functionality, the number-
weighted
average functionality of component A) used is at least 2.
The aliphatic, cycloaliphatic, araliphatic polyfunctional isocyanates known
per se and
preferably the aromatic polyfunctional isocyanates come into consideration for
use as
polyisocyanates A). Polyfunctional isocyanates of this type are known per se
or are
obtainable by methods known per se. Polyfunctional isocyanates may more
particularly
also be used as mixtures, in which case component A) will accordingly comprise
various
polyfunctional isocyanates. Polyfunctional isocyanates that come into
consideration for use
as polyisocyanate have two (hereinafter called diisocyanates) or more than two
isocyanate
groups per molecule.
Specific examples are: alkylene diisocyanates having from 4 to 12 carbon atoms
in the
alkylene radical, e.g. dodecane 1,12-diisocyanate, 2-ethyltetramethylene 1,4-
diisocyanate,
2-methylpentamethylene 1,5-diisocyanate, tetramethylene 1,4-diisocyanate, and
preferably hexamethylene 1,6-diisocyanate: cycloaliphatic diisocyanates such
as
cyclohexane 1,3- and 1,4-diisocyanate and also any mixtures of these isomers,
1-
isocyanato-3,3,5-trimethy1-5-isocyanatomethylcyclohexane (IPD1),
hexahydrotolylene 2,4-
and 2,6-diisocyanate and also the corresponding isomer mixtures,
dicyclohexylmethane
4,4'-, 2,2'- and 2,4'-diisocyanate and also the corresponding isomer mixtures
and
preferably aromatic polyisocyanates such as tolylene 2,4- and 2,6-diisocyanate
and the
corresponding isomer mixtures, diphenylmethane 4,4'-, 2,4'- and 2,2'-
diisocyanate and the
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corresponding isomer mixtures, mixtures of diphenylmethane 4,4'- and 2,2'-
diisocyanates,
polyphenylpolymethylene polyisocyanates, mixtures of diphenylmethane 4,4'-,
2,4'- and
2,2'-diisocyanates and polyphenylpolymethylene polyisocyanates (crude MDI) and
mixtures of crude MDI and tolylene diisocyanates.
Of particular suitability are 2,2`-, 2,4`- and/or 4,4'-diphenylmethane
diisocyanate (MDI), 1,5-
naphthylene diisocyanate (NDI), 2,4- and/or 2,6-tolylene diisocyanate (TDI),
3,3'-
dimethylbiphenyl diisocyanate, 1,2-diphenylethane diisocyanate and/or p-
phenylene
diisocyanate (PPDI), tri-, tetra-, penta-, hexa-, hepta- and/or octamethylene
diisocyanate,
2-methylpentamethylene 1,5-diisocyanate, 2-ethylbutylene 1,4-diisocyanate,
pentamethylene 1,5-diisocyanate, butylene 1,4-diisocyanate, 1-isocyanato-3,3,5-
trimethy1-
5-isocyanatomethylcyclohexane (isophorone diisocyanate, I PDI), 1,4- and/or
1,3-
bis(isocyanatomethyl)cyclohexane (HXD1), 1,4-cyclohexane diisocyanate, 1-
methyl-2 4-
and/or -2,6-cyclohexane diisocyanate and 4,4'-, 2,4'- and/or 2,2'-
dicyclohexylmethane
diisocyanate.
Modified polyisocyanates are also frequently used, i.e., products which are
obtained by
chemical reaction of organic polyisocyanates and which have at least two
reactive
isocyanate groups per molecule. Polyisocyanates comprising ester, urea,
biuret,
allophanate, carbodiimide, isocyanurate, uretdione, carbamate and/or urethane
groups
may be mentioned in particular.
The following embodiments are particularly preferable for use as
polyisocyanates of
component A):
i) Polyfunctional isocyanates based on tolylene diisocyanate (TDI),
especially 2,4-TDI
or 2,6-TDI or mixtures of 2,4- and 2,6-TDI;
ii) Polyfunctional isocyanates based on diphenylmethane diisocyanate (MDI),
especially 2,2`-MDI or 2,4'-MDI or 4,4'-MDI or oligomeric MDI, which is also
known
as polyphenyl polymethylene isocyanate, or mixtures of two or three of the
aforementioned diphenylmethane diisocyanates, or crude MDI, which is generated
in
the production of MDI, or mixtures of at least one oligomer of MDI and at
least one of
the aforementioned low molecular weight MDI derivatives;
iii) Mixtures of at least one aromatic isocyanate of embodiment i) and at
least one
aromatic isocyanate of embodiment ii).
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12
Polymeric diphenylmethane diisocyanate is very particularly preferred for use
as
polyisocyanate. Polymeric diphenylmethane diisocyanate (hereinafter called
polymeric
MDI) is a mixture of two-nuclear MDI and oligomeric condensation products and
thus
derivatives of diphenylmethane diisocyanate (MDI). The polyisocyanates may
preferably
also be constructed from mixtures of monomeric aromatic diisocyanates and
polymeric
MDI.
Polymeric MDI in addition to two-nuclear MDI comprises one or more polynuclear
condensation products of MDI with a functionality of more than 2, especially 3
or 4 or 5.
Polymeric MDI is known and is frequently referred to as polyphenyl
polymethylene
isocyanate or else as oligomeric MDI. Polymeric MDI is typically constructed
from a
mixture of MDI-based isocyanates of differing functionality. Polymeric MDI is
typically used
in admixture with monomeric MDI.
The (average) functionality of a polyisocyanate comprising polymeric MDI can
vary in the
range from about 2.2 to about 5, more particularly from 2.3 to 4, more
particularly from 2.4
to 3.5. Such a mixture of MDI-based polyfunctional isocyanates having
different
functionalities is especially the crude MDI obtained as intermediate in the
production of
MDI.
Polyfunctional isocyanates or mixtures of two or more polyfunctional
isocyanates based on
MDI are known and are for example marketed by BASF Polyurethanes GmbH under
the
name of Lupranata.
The functionality of component A) is preferably at least two, more preferably
at least 2.2
and especially at least 2.4. The functionality of component A) is preferably
in the range
from 2.2 to 4 and more preferably in the range from 2.4 to 3.
The content of isocyanate groups in component A) is preferably in the range
from 5 to
10 mmol/g, more preferybly in the range from 6 to 9 mmol/g, and especially in
the range
from 7 to 8.5 mmol/g. A person skilled in the art knows that the content of
isocyanate
groups in mmol/g and the so-called equivalence weight in g/equivalent are
reciprocal to
each other. The content of isocyanate groups in mmol/g follows from the
content in wt% to
ASTM D-5155-96 A.
In a particularly preferred embodiment, component A) consists of at least one
polyfunctional isocyanate selected from 4,4'-diphenylmethane diisocyanate,
2,4'-
CA 02875176 2014-11-28
13
diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate and oligomeric
diphenylmethane diisocyanate. In the context of this preferred embodiment,
component
(al) comprises oligomeric diphenylmethane diisocyanate, so-called "polymer-
MDI", with
particular preference and has a functionality of at least 2.4.
The viscosity of component A) used can vary within wide limits. The viscosity
of
component A) is preferably in the range from 100 to 3000 mPa.s and more
preferably in
the range from 200 to 2500 mPa's.
Component C
It is also possible to co-use polyether polyols C) which are obtainable by
known
processes, for example by anionic polymerization of one or more alkylene
oxides having 2
to 4 carbon atoms with alkali metal hydroxides, such as sodium hydroxide or
potassium
hydroxide, alkali metal alkoxides, such as sodium methoxide, sodium ethoxide,
potassium
ethoxide or potassium isopropoxide, or aminic alkoxylation catalysts such as
dimethylethanolamine (DMEOA), imidazole and/or imidazole derivatives by using
at least
one starter molecule comprising from 2 to 8 and preferably from 2 to 6
reactive hydrogen
atoms in bonded form, or by cationic polymerization with Lewis acids, such as
antimony
pentachloride, boron fluoride etherate or bleaching earth.
Suitable alkylene oxides are, for example, tetrahydrofuran, 1,3-propylene
oxide, 1,2- or
2,3-butylene oxide, styrene oxide and preferably ethylene oxide and 1,2-
propylene oxide.
The alkylene oxides can be used individually, alternately in succession or as
mixtures.
Preferred alkylene oxides are propylene oxide and ethylene oxide, and ethylene
oxide is
particularly preferred.
Possible starter molecules are, for example: water, organic dicarboxylic
acids, such as
succinic acid, adipic acid, phthalic acid and terephthalic acid, aliphatic and
aromatic,
optionally N-monoalkyl-, N,N-dialkyl- and N,N'-dialkyl-substituted diamines
having from 1
to 4 carbon atoms in the alkyl radical, e.g. optionally monoalkyl- and dialkyl-
substituted
ethylenediamine, diethylenetriamine, triethylenetetramine, 1,3-
propylenediamine, 1,3- or
1,4-butylenediamine, 1,2-, 1,3-, 1,4-, 1,5- and 1,6-hexamethylenediamine,
phenylenediamines, 2,3-, 2,4- and 2,6-tolylenediamine and 4,4'-, 2,4'- and
2,2'-
diaminodiphenylmethane. Particular preference is given to the recited
diprimary amines,
for example ethylenediamine.
CA 02875176 2014-11-28
14
Further possible starter molecules are: alkanolamines such as ethanolamine,
N-methylethanolamine and N-ethylethanolamine, dialkanolamines, such as
diethanolamine, N-methyldiethanolamine and N-ethyldiethanolamine and
trialkanolamines,
such as triethanolamine, and ammonia.
Preference is given to using dihydric or polyhydric alcohols, such as
ethanediol, 1,2- and
1,3-propanediol, diethylene glycol (DEG), dipropylene glycol, 1,4-butanediol,
1,6-
hexanediol, glycerol, trimethylolpropane, pentaerythritol, sorbitol and
sucrose.
The polyether polyols C), preferably polyoxypropylene polyols and
polyoxyethylene
polyols, more preferably polyoxyethylene polyols, have a functionality of
preferably 2 to 6,
more preferably of 2 to 4, especially of 2 to 3 and specifically 2 and number
average
molecular weights of 150 to 3000 g/mol, preferably 200 to 2000 g/mol and
especially 250
to 1000 g/mol.
One preferred embodiment of the invention utilizes an alkoxylated dial,
preferably an
ethoxylated dial, for example ethoxylated ethylene glycol, as polyether polyol
C);
polyethylene glycol is preferably concerned.
In one advantageous embodiment of the invention, the polyetherol component C)
consists
exclusively of polyethylene glycol, preferably having a number average
molecular weight
of 250 to 1000 g/mol.
The proportion of polyether polyols C) is generally in the range from 0 to 11
wt%,
preferably in the range from 2 to 9 wt% and more preferably in the range from
4 to 8 wt%,
based on total components B) to G).
The mass ratio of component B) to component C), if present, is generally at
least 1,
preferably 3, more preferably 4, especially 5 and specifically 7.
The mass ratio of component B to component C), if present, is generally less
than 80,
preferably less than 40, more preferably less than 30, even more preferably
less than 20,
yet even more preferably less than 16 and specifically less than 13.
Component D
CA 02875176 2014-11-28
Component D) is a flame-retardant mixture which is characterized by the fact
that it
consists dl) to an extent of at least 10 wt% and at most 90 wt%, based on the
amount of
flame-retardant mixture, of a flame retardant having a boiling point of not
more than 220 C,
and d2) to an extent of at least 10 wt% and at most 90 wt% of one or more
phosphorus-
5 containing flame retardants having a boiling point of greater than 220 C.
Useful flame retardants dl) include phosphates or phosphonates, for example
diethyl
ethanephosphonate (DEEP), triethyl phosphate (TEP) and dimethyl
propylphosphonate
(DMPP).
Useful flame retardants d2) include for example brominated esters, brominated
ethers
(Ixol) or brominated alcohols such as dibromoneopentyl alcohol,
tribromoneopentyl
alcohol, tetrabromophthalate diol (DP 54) and PHT-4-diol, and also chlorinated
phosphates such as tris(2-chloroethyl) phosphate, tris(2-chloropropyl)
phosphate (TCPP),
tris(1,3-dichloropropyl) phosphate, tricresyl phosphate, diphenyl cresyl
phosphate (DPK),
tris(2,3-dibromopropyl) phosphate, tetrakis(2-chloroethyl)
ethylenediphosphate, dimethyl
methanephosphonate, diethyl diethanolaminomethylphosphonate and also
commercially
available halogenated flame-retardant polyols.
Useful flame retardants dl) having a boiling point below 220 C have no
isocyanate-
reactive groups. The are preferably phosphorus-containing, more preferably
halogen-free
and more particularly selected from the group consisting of diethyl
ethylphosphonate
(DEEP) and triethyl phosphate (TEP) and dimethyl propylphosphonate (DMPP) and
also
mixtures thereof.
Preferred flame retardants d2), boiling above 220 C, have no isocyanate-
reactive groups.
The flame retardants are preferably liquid at room temperature, particulary
preferred
phosphorus-containing flame retardants are selected from the group consisting
of tris(2-
chloropropyl) phosphate (TCPP), diphenylcresyl phosphate (DPC); triphenyl
phosphate
(TPP) and also mixtures thereof. Halogen-free flame retardants are
particularly preferable.
Preferably, component D) consists to an extent of from 10 to 70 wt% of one or
more flame
retardants dl) having a boiling point of not more than 220 C and to an extent
of from 30 to
90 wt% of one or more phosphorus-containing flame retardants d2) having a
boiling point
of greater than 220 C.
CA 02875176 2014-11-28
16
The proportion of flame-retardant mixture D) is generally in the range from 2
to 50 wt%,
preferably in the range from 9 to 45 wt%, more preferably in the range from 15
to 36 wt%
and even more preferably in the range from 20 to 30 wt%, based on total
components E)
to G).
Component E
Further auxiliaries and/or addition agents E) can optionally be added to the
reaction
mixture for producing the rigid polyurethane foams. Mention may be made of,
for example,
surface-active substances, foam stabilizers, cell regulators, fillers, dyes,
pigments,
hydrolysis inhibitors, fungistatic and bacteriostatic substances.
Possible surface-active substances are, for example, compounds which serve to
aid
homogenization of the starting materials and may also be suitable for
regulating the cell
structure of the polymers. Mention may be made of, for example, emulsifiers
such as the
sodium salts of castor oil sulfates or of fatty acids and also salts of fatty
acids with amines,
e.g. diethylamine oleate, diethanolamine stearate, diethanolamine ricinoleate,
salts of
sulfonic acids, e.g. alkali metal or ammonium salts of dodecylbenzenesulfonic
or
dinaphthylmethanedisulfonic acid and ricinoleic acid; foam stabilizers such as
siloxane-
oxyalkylene copolymers and other organopolysiloxanes, ethoxylated
alkylphenols,
ethoxylated fatty alcohols, paraffin oils, castor oil esters or ricinoleic
esters, Turkey red oil
and peanut oil, and cell regulators such as paraffins, fatty alcohols and
dimethylpolysiloxanes. The above-described oligomeric acrylates having
polyoxyalkylene
and fluoroalkane radicals as side groups are also suitable for improving the
emulsifying
action, the cell structure and/or for stabilizing the foam. The surface-active
substances are
typically employed in amounts of 0.01 to 10 parts by weight, based (i.e.,
reckoned) on 100
parts by weight of component B).
For the purposes of the present invention, fillers, in particular reinforcing
fillers, are the
customary organic and inorganic fillers, reinforcing materials, weighting
agents, agents for
improving the abrasion behavior in paints, coating compositions, etc., which
are known per
se. Specific examples are: inorganic fillers such as siliceous minerals, for
example sheet
silicates such as antigorite, serpentine, hornblendes, amphiboles, chrisotile
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 and zinc
sulfide and also
glass, etc. Preference is given to using kaolin (china clay), aluminum
silicate and
coprecipitates of barium sulfate and aluminum silicate and also natural and
synthetic
17
fibrous minerals such as wollastonite, metal fibers and in particular glass
fibers of various lengths,
which may be coated with a size. Possible organic fillers are, for example:
carbon, melamine, rosin,
cyclopentadienyl resins and graft polymers and also cellulose fibers,
polyamide, polyacrylonitrile,
polyurethane, polyester fibers based on aromatic and/or aliphatic dicarboxylic
esters and in
particular carbon fibers.
The inorganic and organic fillers can be used individually or as mixtures and
are advantageously
added to the reaction mixture in amounts of from 0.5 to 50 wt%, preferably
from 1 to 40 wt%, based
on the weight of the components A) to G), although the content of mats,
nonwovens and woven
fabrics of natural and synthetic fibers can reach values of up to 80 wt%,
based on the weight of
components A) to G).
Further information regarding the abovementioned other customary auxiliary and
addition agents
may be found in the technical literature, for example the monograph by J.H.
Saunders and K.C.
Frisch "High Polymers" Volume XVI, Polyurethanes, Parts 1 and 2, Interscience
Publishers 1962
and 1964, or Kunststoff-Handbuch (translation: Plastics Handbook),
Polyurethane, Volume VII,
Hanser-Verlag, Munich, Vienna, 1st and 2nd Editions, 1966 and 1983.
Component F
Blowing agents F) which are used for producing the rigid polyurethane foams
include preferably
water, formic acid and mixtures thereof. These react with isocyanate groups to
form carbon dioxide
and in the case of formic acid to form carbon dioxide and carbon monoxide.
Since these blowing
agents release the gas through a chemical reaction with the isocyanate groups,
they are referred
to as chemical blowing agents. In addition, physical blowing agents such as
low-boiling
hydrocarbons can be used. Suitable physical blowing agents are in particular
liquids which are inert
towards the polyisocyanates A) and have boiling points below 100 C, preferably
below 50 C, at
atmospheric pressure, so that they vaporize under the conditions of the
exothermic polyaddition
reaction. Examples of such liquids which are preferably used are alkanes such
as heptane, hexane,
n-pentane and isopentane, preferably industrial mixtures of n-pentane and
isopentane, n-butane
and isobutane and propane, cycloalkanes such as cyclopentane and/or
cyclohexane, ethers such
as furan, dimethyl ether and diethyl ether, ketones such as acetone and methyl
ethyl ketone, alkyl
carboxylates such as methyl formate, dimethyl oxalate and ethyl acetate and
halogenated
hydrocarbons such as methylene chloride, dichloromonofluoromethane,
difluoromethane,
trifluoromethane, difluoroethane, tetrafluoroethane, chlorodifluoroethanes,
1,1-dichloro-2,2,2-
trifluoroethane, 2,2-dichloro-2-fluoroethane and
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18
heptafluoropropane. Mixtures of these low-boiling liquids with one another
and/or with
other substituted or unsubstituted hydrocarbons can also be used. Organic
carboxylic
acids such as formic acid, acetic acid, oxalic acid, ricinoleic acid and
carboxyl-containing
compounds are also suitable.
It is preferable not to use any halogenated hydrocarbons as blowing agents.
Water, formic
acid-water mixtures or formic acid are preferably used as chemical blowing
agents with
formic acid-water mixtures or formic acid being particularly preferred
chemical blowing
agents. It is preferable to use pentane isomers, or mixtures of pentane
isomers, as
physical blowing agents.
The chemical blowing agents can be used alone, i.e., without addition of
physical blowing
agents, or together with physical blowing agents. The chemical blowing agents
are
preferably used together with physical blowing agents, in which case the use
of formic
acid-water mixtures or pure formic acid together with pentane isomers or
mixtures of
pentane isomers is preferred.
The blowing agents are either wholly or partly dissolved in the polyol
component (i.e.
B+C+D+E+F+G) or are introduced via a static mixer immediately before foaming
of the
polyol component. It is usual for water, formic acid-water mixtures or formic
acid to be fully
or partially dissolved in the polyol component and the physical blowing agent
(for example
pentane) and any remainder of the chemical blowing agent to be introduced "on-
line".
The polyol component is admixed in situ with pentane, possibly some of the
chemical
blowing agent and also with all or some of the catalyst. Auxiliary and
addition agents as
well as flame retardants are already comprised in the polyol blend.
The amount of blowing agent or blowing agent mixture used is in the range from
1 to
45 wt%, preferably in the range from 1 to 30 wt% and more preferably in the
range from
1.5 to 20 wt%, all based on total components B) to G).
When water, formic acid or a formic acid-water mixture is used as blowing
agent, it is
preferably added to the polyol component (B+C+D+E+F+G) in an amount of 0.2 to
10 wt%, based on component B). The addition of water, formic acid or formic
acid-water
mixture can take place in combination with the use of other blowing agents
described.
Preference is given to using formic acid or a formic acid-water mixture in
combination with
pentane.
CA 02875176 2014-11-28
19
Component G
Catalysts G) used for preparing the rigid polyurethane foams are particularly
compounds
which substantially speed the reaction of the components' B) to G) compounds
comprising
reactive hydrogen atoms, especially hydroxyl groups, with the polyisocyanates
A).
It is advantageous to use basic polyurethane catalysts, for example tertiary
amines such
as triethylamine, tributylamine, dimethylbenzylamine, dicyclohexylmethylamine,
dimethylcyclohexylamine, N, N,N',N'-tetramethyldiaminodiethyl
ether,
bis(dimethylaminopropyl)urea, N-methylmorpholine or N-
ethylmorpholine, N-
cyclohexylmorpholine, N, N,N',N'-tetramethylethylenediamine,
N,N,N,N-
tetramethylbutanediamine,
N,N,N,N-tetramethylhexane-1,6-diamine,
pentamethyldiethylenetriamine, bis(2-dimethylaminoethyl) ether,
dimethylpiperazine, N-
dimethylaminoethylpiperidine, 1,2-dimethylimidazole, 1-azabicyclo-
[2.2.0]octane, 1,4-
diazabicyclo[2.2.2]octane (Dabco) and alkanolamine compounds, such as
triethanolamine,
triisopropanolamine, N-methyldiethanolamine and N-
ethyldiethanolamine,
dimethylaminoethanol, 2-
(N, N-dimethylaminoethoxy)ethanol,
N,N',N"-tris(dialkylaminoalkyl)hexahydrotriazines, e.g. N,N',N"-
tris(dimethylaminopropy1)-s-
hexahydrotriazine, and triethylenediamine. However, metal salts such as
iron(11) chloride,
zinc chloride, lead octoate and preferably tin salts such as tin dioctoate,
tin diethylhexoate
and dibutyltin dilaurate and also, in particular, mixtures of tertiary amines
and organic tin
salts are also suitable.
Further possible catalysts are: amidines such as 2,3-dimethy1-3,4,5,6-
tetrahydropyrimidine,
tetraalkylammonium hydroxides such as tetramethylammonium hydroxide, alkali
metal
hydroxides such as sodium hydroxide and alkali metal alkoxides such as sodium
methoxide and potassium isopropoxide, alkali metal carboxylates and also
alkali metal
salts of long-chain fatty acids having from 10 to 20 carbon atoms and
optionally lateral OH
groups. Preference is given to using from 0.001 to 10 parts by weight of
catalyst or catalyst
combination, based (i.e., reckoned) on 100 parts by weight of component B). It
is also
possible to allow the reactions to proceed without catalysis. In this case,
the catalytic
activity of amine-initiated polyols is exploited.
When, during foaming, a relatively large polyisocyanate excess is used,
further suitable
catalysts for the trimerization reaction of the excess NCO groups with one
another are:
catalysts which form isocyanurate groups, for example ammonium ion salts or
alkali metal
=
salts, specifically ammonium or alkali metal carboxylates, alone or in
combination with tertiary
amines. Isocyanurate formation leads to flame-resistant PIR foams which are
preferably used in
industrial rigid foam, for example in building and construction as insulation
boards or sandwich
elements.
5
Further information regarding the abovementioned and further starting
materials may be found in
the technical literature, for example Kunststoffhandbuch (translation:
Plastics Handbook), Volume
VII, Polyurethane, Carl Hanser Verlag Munich, Vienna, 1st, 2nd and 3rd
Editions 1966, 1983 and
1993.
The present invention also provides a polyol component for producing rigid
polyurethane foams
comprising the components B) to G) as described above. The mass ratio of
component B) to
component C) is preferably at least 1.
It is preferable for the polyol component to comprise
10 to 90 wt% of polyester polyols B),
0 to 11 wt% of polyether polyols C),
2 to 50 wt% of flame retardants D),
0.5 to 20 wt% of further auxiliary and addition agents E),
1 to 45 wt% of blowing agents F), and
0.5 to 10 wt% of catalysts G),
each as defined above and each based on the total weight of components B) to
G), wherein
components B) to G) total 100 wt%, and wherein the mass ratio of component B)
to component
C) is at least 4.
It is particularly preferable for the polyol component to comprise
40 to 90 wt% of polyester polyols B),
2 to 9 wt% of polyether polyols C),
9 to 45 wt% of flame retardants D),
0,5 to 20 wt% of further auxiliary and addition agents E),
1 to 30 wt% of blowing agents F),
0.5 to 10 wt% of catalysts G), and
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CA 02875176 2014-11-28
21
each as defined above and each based on the total weight of components B) to
G),
wherein components B) to G) total 100 wt%, and wherein the mass ratio of
component B)
to component C) is at least 5.
The mass ratio of component B) to component C) in the polyol components of the
present
invention that is in accordance with the present invention is preferably less
than 80, more
preferably less than 40, even more preferably less than 30, yet even more
preferably less
than 20, yet still even more preferably less than 16 and specifically less
than 13.
The mass ratio of the present invention for component A to the sum total B) to
E) is further
not less than 1.3, preferably not less than 1.5, more preferably not less than
1.7, even
more preferably not less than 1.8, yet even more preferably not less than 2.0
and
specifically not less than 2.5.
To produce the rigid polyurethane foams of the present invention, the
optionally modified
organic polyisocyanates A), the polyester polyols B), optionally the
polyetherols C) and the
further components D) to G) are mixed in such amounts that the equivalence
ratio of NCO
groups on polyisocyanates A) to total reactive hydrogen atoms on components B)
and also
D) to G) is in the range from 1 to 6:1, preferably in the range from 1.6 to
5:1 and especially
in the range from 2.5 to 3.5:1.
The invention also provides the rigid polyurethane foams themselves and also
their use for
production of sandwich elements having rigid or flexible outer layers. These
sandwich
elements can be produced in a batch or continuous process with a continuous
process
being preferred.
The examples which follow illustrate the invention.
Examples
The following polyester polyols (polyesterol 1, polyesterol 2) were used:
Polyesterol 1:
Esterification product of phthalic anhydride (25 mol%), oleic acid (15 mol%),
diethylene
glycol (37 mol%) and a polyether (23 mol%) based on trimethylolpropane and
ethylene
oxide with an OH functionality of 3 and a hydroxyl number of 610 mg KOH/g,
prepared in
CA 02875176 2014-11-28
22
the presence of imidazole as alkoxylation catalyst and using the polyether
without workup.
The polyesterol has a hydroxyl functionality of 2.2, a hydroxyl number of 244
mg KOH/g
and an oleic acid content of 24 wt% in the polyesterol.
Polyesterol 2:
Esterification product of phthalic anhydride (30 mol%), oleic acid (12 mol%),
diethylene
glycol (40 mol%) and trimethylolpropane (18 mol%) with a hydroxyl
functionality of 2.2, a
hydroxyl number of 249 mg KOH/g and an oleic acid content of 25 wt% in the
polyesterol.
The following were used as flame retardants:
trischloroisopropyl phosphate (TCPP) with a boiling point of 244 C, and
triethyl phosphate (TEP) with a boiling point of 215 C.
Determination of curing and brittleness of rigid polyurethane foam
Curing was determined using the bolt test. For this, at 2.5, 3, 4 and 5
minutes after mixing
the components of the polyurethane foam in a polystyrene beaker, a steel bolt
with
spherical cap 10 mm in radius was pressed by tensile/compressive tester 10 mm
deep into
the mushroom-shaped foam formed. The maximum force in N required for this is a
measure of the curing of the foam.
Brittleness was determined for the rigid polyisocyanurate foam directly after
foaming in a
subjective manner by compressing the foam and graded on a scale from 1 to 7,
where 1
denotes a scarcely brittle foam and 7 denotes a foam of high brittleness.
Brittleness was
further classified by determining the time at which the surface of the rigid
foam displayed
visible zones of breakage in the bolt test.
Determining the self-reactivity of polyurethane systems
The polyurethane systems described hereinbelow were adjusted to a unitary
fiber time by
varying the polyurethane catalyst concentration. When a system needed a lower
-- concentration of catalyst, this was taken to mean that the system had
higher self-reactivity.
Comparative examples 1 and 2 and inventive examples 1 and 2
CA 02875176 2014-11-28
23
Production of rigid polyurethane foams
The isocyanates and the isocyanate-reactive components were foamed up together
with
the blowing agents, catalysts and all further addition agents at a constant
mixing ratio of
100 : 250 for polyol component to isocyanate.
Comparative example 1:
Starting from
43.9 parts by weight of polyesterol 2 with a hydroxyl number of 249 mg KOH/g,
based on
the esterification product of phthalic anhydride, oleic acid, diethylene
glycol,
trimethylolpropane,
8 parts by weight of a polyetherol from ethoxylated ethylene glycol with a
hydroxyl
functionality of 2 and a hydroxyl number of 190 mg KOH/g,
43 parts by weight of trischloroisopropyl phosphate (TCPP) flame retardant,
and
3.1 parts by weight of an 85% formic acid solution with water, and
2 parts by weight of silicone-containing foam stabilizer (Tegostab B8467 from
Evonik)
a polyol component was produced by mixing.
The polyol component was reacted with 250 parts by weight of polymer MDI
having an
NCO content of 31.5 wt% (Lupranat M50 from BASF SE, viscosity about 500 mPas
at
C) in the presence of n-pentane (16 parts by weight), a 70% bis-2-
dimethylaminoethyl
ether solution in dipropylene glycol (Niax Al from Momentive/designated
catalyst 1 in
25 table 1) and 2.6 wt% of a 36% potassium formate solution in monoethylene
glycol. The
components were intensively mixed using a laboratory stirrer. The amount of
70% bis-2-
dimethylaminoethyl ether solution in dipropylene glycol (Niax Al from
Momentive) was
chosen such that the fiber time was 51 seconds. The resulting foam had a
density of
33 kg/m3.
Comparative example 2:
Starting from
43.9 parts by weight of polyesterol 1 with a hydroxyl number of 244 mg KOH/g,
based on
the esterification product of phthalic anhydride, oleic acid, diethylene
glycol and a
polyether based on trimethylolpropane and ethylene oxide,
CA 02875176 2014-11-28
24
phthalic anhydride, oleic acid, diethylene glycol trimethylolpropane
8 parts by weight of a polyetherol from ethoxylated ethylene glycol with a
hydroxyl
functionality of 2 and a hydroxyl number of 190 mg KOH/g,
43 parts by weight of trischloroisopropyl phosphate (TCPP) flame retardant,
and
3.1 parts by weight of an 85% formic acid solution with water, and
2 parts by weight of silicone-containing foam stabilizer (Tegostab0 B8467 from
Evonik)
a polyol component was produced by mixing.
The polyol component was reacted with 250 parts by weight of polymer MDI
having an
NCO content of 31.5 wt% (Lupranat M50 from BASF SE, viscosity about 500 mPas
at
25 C) in the presence of n-pentane (16 parts by weight), a 70% bis-2-
dimethylaminoethyl
ether solution in dipropylene glycol (Niax0 Al from Momentive/designated
catalyst 1 in
table 1) and 2.6 wt% of a 36% potassium formate solution in monoethylene
glycol. The
components were intensively mixed using a laboratory stirrer. The amount of
70% bis-2-
dimethylaminoethyl ether solution in dipropylene glycol (Niax0 Al from
Momentive) was
chosen such that the fiber time was 51 seconds. The resulting foam had a
density of
33 kg/m3.
Inventive example 1:
Starting from
43.9 parts by weight of polyesterol 2 with a hydroxyl number of 249 mg KOH/g,
based on
the esterification product of phthalic anhydride, oleic acid, diethylene
glycol and
trimethylolpropane,
8 parts by weight of a polyetherol from ethoxylated ethylene glycol with a
hydroxyl
functionality of 2 and a hydroxyl number of 190 mg KOH/g,
25 parts by weight of trischloroisopropyl phosphate (TCPP) flame retardant,
and
18 parts by weight of triethyl phosphate (TEP) flame retardant, and
3.1 parts by weight of an 85% formic acid solution with water, and
2 parts by weight of silicone-containing foam stabilizer (Tegostab B8467 from
Evonik)
a polyol component was produced by mixing.
The polyol component was reacted with 250 parts by weight of polymer MDI
having an
NCO content of 31.5 wt% (Lupranat M50 from BASF SE, viscosity about 500 mPas
at
25 C) in the presence of n-pentane (16 parts by weight), a 70% bis-2-
dimethylaminoethyl
-- ether solution in dipropylene glycol (Niax0 Al from Momentive/designated
catalyst 1 in
table 1) and 2.6 wt% of a 36% potassium formate solution in monoethylene
glycol. The
components were intensively mixed using a laboratory stirrer. The amount of
70% bis-2-
CA 02875176 2014-11-28
dimethylaminoethyl ether solution in dipropylene glycol (Niax Al from
Momentive) was
chosen such that the fiber time was 51 seconds. The resulting foam had a
density of
33 kg/m'.
5
Inventive example 2:
Starting from
43.9 parts by weight of polyesterol 1 with a hydroxyl number of 244 mg KOH/g,
based on
10 the esterification product of phthalic anhydride, oleic acid, diethylene
glycol and a
polyether based on trimethylolpropane and ethylene oxide,
8 parts by weight of a polyetherol from ethoxylated ethylene glycol with a
hydroxyl
functionality of 2 and a hydroxyl number of 190 mg KOH/g,
25 parts by weight of trischloroisopropyl phosphate (TCPP) flame retardant,
and
15 18 parts by weight of triethyl phosphate (TEP) flame retardant, and
3.1 parts by weight of an 85% formic acid solution with water, and
2 parts by weight of silicone-containing foam stabilizer (Tegostab B8467 from
Evonik)
a polyol component was produced by mixing.
20 The polyol component was reacted with 250 parts by weight of polymer MDI
having an
NCO content of 31.5 wt% (Lupranat M50 from BASF SE, viscosity about 500 mPas
at
25 C) in the presence of n-pentane (16 parts by weight), a 70% bis-2-
dimethylaminoethyl
ether solution in dipropylene glycol (Niax0 Al from Momentive/designated
catalyst 1 in
table 1) and 2.6 wt% of a 36 wt% potassium formate solution in monoethylene
glycol. The
25 components were intensively mixed using a laboratory stirrer. The amount
of 70% bis-2-
dimethylaminoethyl ether solution in dipropylene glycol (Niax0 Al from
Momentive) was
chosen such that the fiber time was 51 seconds. The resulting foam had a
density of
33 kg/m3.
Test Report
Polyesterol 1 was used.
Polyesterol 1:
Esterification product of phthalic anhydride (25 mol%), oleic acid (15 mol%),
diethylene
glycol (37 mol%) and a polyether (23 mol%) based on trimethylolpropane and
ethylene
CA 02875176 2014-11-28
26
oxide with an OH functionality of 3 and a hydroxyl number of 610 mg KOH/g,
prepared in
the presence of imidazole as alkoxylation catalyst and using the polyether
without workup.
The polyesterol has a hydroxyl functionality of 2.2, a hydroxyl number of 244
mg KOH/g
and an oleic acid content of 24 wt% in the polyesterol.
Production of rigid polyurethane foams
The isocyanates and the isocyanate-reactive components were foamed up together
with
the blowing agents, catalysts and all further addition agents at a constant
mixing ratio of
100 : 250 for polyol component to isocyanate.
Inventive example 3:
Starting from
43.9 parts by weight of polyesterol 1 with a hydroxyl number of 244 mg KOH/g,
based on
the esterification product of phthalic anhydride, oleic acid, diethylene
glycol and a
polyether based on trimethylolpropane and ethylene oxide,
8 parts by weight of a polyetherol from ethoxylated ethylene glycol with a
hydroxyl
functionality of 2 and a hydroxyl number of 190 mg KOH/g,
25 parts by weight of diphenyl cresyl phosphate (Disflamoll DPK) flame
retardant, and
18 parts by weight of dimethyl propane phosphonate (Levagard DMPP)
flame retardant; and
3.1 parts by weight of an 85% formic acid solution with water, and
2 parts by weight of silicone-containing foam stabilizer (Tegostab B8467 from
Evonik)
a polyol component was produced by mixing.
The polyol component was reacted with 250 parts by weight of polymer MDI
having an
NCO content of 31.5 wt% (Lupranat M50 from BASF SE, viscosity about 500 mPas
at
25 C) in the presence of n-pentane (16 parts by weight), a 70% bis-2-
dimethylaminoethyl
ether solution in dipropylene glycol (Niax Al from Momentive/designated
catalyst 1 in
table 1) and 2.6 wt% of a 36 wt% potassium formate solution in monoethylene
glycol. The
components were intensively mixed using a laboratory stirrer. The amount of
70% bis-2-
dimethylaminoethyl ether solution in dipropylene glycol (Niax Al from
Momentive) was
chosen such that the fiber time was 51 seconds. The resulting foam had a
density of
33 kg/m'.
The results are summarized in table 1.
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27
Table 1:
Comparativ Comparativ Inventive Inventive Inventive
e example 1 e example 2 example 1 example 2 Example 3
curing [NJ
2.5 min 47 50 52 62 44
3 min 54 58 63 73 64
4 min 71 70 80 85 77
min 75 65 89 86 88
total (2.5, 3, 4 and 5 247 243 284 306 273
min)
subjective 7 7 6 3 4
brittleness
breakage in bolt test 4 4 4 6 5
catalyst 1 2.6 2.1 1.4 1.0 1.0
viscosity of polyol 618 297 182 106 100
component at
T = 20 C
5
It is clearly apparent that the inventive polyol components increase the self-
reactivity of the
system. Inventive examples 2 and 3 only need 1.0 part by weight of catalyst 1
respectively
compared with 2.1 and 2.6 parts by weight respectively in comparative examples
1 and 2.
The inventive polyol components also lead to improved curing of the foam. The
sum total
for the measurements at 2.5 min, 3 min, 4 min and 5 min is 306 N or,
respectively, 273 N
(examples 2 and 3) and hence is distinctly above the results of the
comparative examples,
which have values of 247 N and 243 N respectively.
The invention further serves to reduce the viscosity of the polyol components
from 618 and
297 mPas at 20 C to 106 and 100 mPas (examples 2 and 3) at 20 C respectively.
This
leads to better miscibility of the polyol component with the isocyanate. This
reduces the
frequency of surface defects and results in an improved foam surface.
The inventive polyol components also reduced the brittleness of the insulant
and hence
the dusting and cracking tendency on sawing composite elements having a
CA 02875176 2014-11-28
28
polyisocyanurate foam core. Brittleness decreases both measured subjectively
using
finger pressure on the foam after foaming and measured in terms of breakage
time in the
curing measurement.
Moreover the rigid PU foams of the present invention which are based on
polyetherester
polyols (examples 2 and 3) bear the advantage that in the event of fire no
toxic
compounds are formed, unlike rigid PU foams in which trimethylolpropane is
used as
higher functional polyester component (example 1 and comparative example 1).
