Note: Descriptions are shown in the official language in which they were submitted.
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Preparing rigid polyurethane foams
Description
The present invention relates to a process for preparing rigid polyurethane
foams or rigid
polyisocyanurate foams by using certain polyetherester polyols B) based on
aromatic
dicarboxylic acids, optionally further polyester polyols C), which differ from
those of
component B), and polyether polyols D), wherein the mass ratio of total
components B) and
optionally C) to component D) is less than 1.6. The present invention also
relates to the rigid
foams thus obtainable and to their use for producing sandwich elements having
rigid or
flexible outer layers. The present invention further relates to the underlying
polyol
components.
The production of rigid polyurethane foams by reacting polyisocyanates with
relatively high
molecular weight compounds having at least two reactive hydrogen atoms, in
particular with
polyether polyols from alkylene oxide polymerization or polyester polyols from
the
polycondensation of alcohols with dicarboxylic acids, in the presence of
polyurethane
catalysts, chain extenders and/or crosslinkers, blowing agents and further
auxiliary and
addition agents is known and is described in numerous patent and literature
publications.
It is known more particularly from the prior art to use polyester polyols
which are obtained as
polycondensates from aromatic and/or aliphatic dicarboxylic acids and
alkanediols and/or
-triols, or ether diols. WO 2010/115532 Al describes the preparation of
polyester polyols
from terephthalic acid and oligoalkylene oxides, which is said to provide
products having
improved flame resistance. Fatty acids or fatty acid derivatives are not used
in this reference.
Low-functional alcohols are used as starters.
When the polyester polyols based on aromatic carboxylic acids or derivatives
thereof (e.g.
terephthalic acid or phthalic anhydride) are used to produce rigid
polyurethane (PU) foams,
the high viscosity of the polyester polyols often has a noticeably adverse
effect since, as a
consequence, the viscosity of the blends with the polyesters increases and as
a result mixing
of the polyol components with the isocyanate is made significantly 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
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double belt process, can occur in certain systems for producing rigid PU
foams, for example
when using glycerol as relatively high-functionality alcohol component.
The problem of the behavior of rigid PU foams in the event of fire has also
not yet been
satisfactorily solved for all systems. For example, a toxic compound can form
in the event of
fire when using trimethylolpropane (TMP) as relatively high-functionality
polyester
component.
A general problem in the production of rigid PU 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.
Rigid PU foams frequently display high brittleness on cutting with severe
evolution of dust
and high sensitivity on the part of the foam, and also on sawing where
particularly the sawing
of composite elements with metallic outer layers and a core of polyurethane or
polyisocyanurate foam can lead to crack formation in the foam.
It is further generally desirable to provide systems having a very high self-
reactivity in order
that the use of catalysts may be minimized.
Prior art rigid PU foams and/or their (constructal) components are
unsatisfactory in some
aspects concerning their profile in respect of the aforementioned properties.
The present
invention has for its object to improve the profile in respect of the
aforementioned properties.
The invention has more particularly for its object to provide rigid PU foams
of low brittleness.
The invention further has for its object to provide a polyol component which
has a high self-
reactivity.
In addition, the viscosity of the compounds used and of the blends prepared
therefrom shall
be low in order to provide good nneterability and mixability in the
preparation of rigid PU
foams. Furthermore, the solubility of blowing agents, for example the
solubility of pentane in
the polyol component, should also be very good.
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A further object is to improve the dimensional stability of the 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.
As far as the choice of (constructal) components is concerned, the feedstocks
used shall be
obtainable at very low cost and inconvenience (i.e., inter alia with a minimum
of workup and
purification steps).
We have found that this object is achieved by a process for preparing rigid
polyurethane
foams or rigid polyisocyanurate foams comprising the reaction of
A) at least one polyisocyanate,
B) at least one polyetherester polyol obtainable by esterification 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,
b2) 2 to 30 mol% of one or more fatty acids or fatty acid derivatives,
b3) 10 to 70 mol% of one or more aliphatic or cycloaliphatic diols having 2
to 18
carbon atoms or alkoxylates thereof,
b4) 2 to 50 mol% of a polyether polyol having a functionality of
not less than 2,
prepared by alkoxylation of a polyol having a functionality of above 2,
all based on the total amount of components b1) to b4), wherein said
components b1)
to b4) sum to 100 mol%,
C) optionally further polyester polyols other than those of component
B),
D) polyether polyols,
E) optionally flame retardants,
F) one or more blowing agents,
G) catalysts, and
H) optionally further auxiliaries or addition agents,
wherein the mass ratio of total components B) and optionally C) to component
D) is less than
1.6.
The present invention also provides a polyol component comprising the
aforementioned
components B) to H), wherein the mass ratio of total components B) and
optionally C) to
component D) is below 1.6.
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The present invention further provides rigid polyurethane foams and rigid
polyisocyanurate
foams obtainable by the process of the present invention and also for their
use for preparing
sandwich elements having rigid or flexible outer layers.
The invention will now be more particularly elucidated. Combinations of
preferred
embodiments are not outside the scope of the present invention. This holds
particularly for
those embodiments of individual components A) to H) of the present invention
which are
characterized as preferred. The embodiments recited hereinbelow in the context
of
component B) to H) apply not only to the process of the present invention and
to the rigid
foams thus obtainable but also to the polyol components of the present
invention.
Component B
In the context of the present disclosure, the terms "polyester polyol" and
"polyesterol" are
synonymous as are the terms "polyether polyol" and "polyetherol".
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 (DMT), terephthalic acid or mixtures thereof. The aromatic
dicarboxylic acids or
their derivatives in 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 polyetheresters B) having particularly good fire
protection
properties. Terephthalic acid is very particularly preferable since, in
contrast to DMT, the
formation of disruptive elimination products can be avoided.
The proportion in which aliphatic dicarboxylic acids or aliphatic dicarboxylic
acid derivatives
(component b12)) are comprised in 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) not to contain any
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.
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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%.
5 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 2 to 35 mol% and even more preferably in the
range from
to 25 mol%.
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 of fatty acid
15 mixtures, and/or one or more fatty acid monoesters, for example
biodiesel or methyl esters of
fatty acids; component b2) more preferably consists of a fatty acid or fatty
acid mixture
and/or one or more fatty acid monoesters; component b2) even more preferably
consists of a
fatty acid or fatty acid mixture and/or biodiesel; and component b2) yet even
more preferably
consists of a fatty acid or fatty acid mixture.
In a 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,
stearic 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
tallow, such as beef tallow, fatty acids, hydroxyl-modified fatty acids,
biodiesel, methyl esters
of 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, and also mixed fatty acids.
In a particularly 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 biodiesel, soybean oil, rapeseed oil or beef tallow, even more
preferably oleic acid
or biodiesel and yet even more preferably oleic acid. The fatty acid or the
fatty acid derivative
generally serves to improve the blowing agent solubility in the production of
rigid
polyurethane foams.
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It is very particularly preferable for component b2) not to comprise any
triglyceride, especially
no oil or fat. The glycerol released from the triglyceride by the
esterification/transesterification
has, as mentioned above, a deleterious effect on the dimensional stability of
rigid foam.
Preferred fatty acids and fatty acid derivatives in the context of component
b2) are hence the
fatty acids themselves and also alkyl monoesters of fatty acids and 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 diol b3)
to be monoethylene
glycol or diethylene glycol, especially diethylene glycol.
Preferably, such 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.
According to the invention, 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 a
polyol selected from the group consisting of sorbitol, pentaerythritol,
trimethylolpropane,
glycerol, polyglycerol and mixtures thereof.
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 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, such as
sodium
hydroxide or potassium hydroxide, or alkali metal alkoxides, such as sodium
methoxide,
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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 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 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 particularly preferred embodiment of the invention, the polyether polyol
b4) consists of
the reaction product of trimethylolpropane or glycerol, preferably glycerol,
with ethylene
oxide, the OH number of the polyether polyol b4) is in the range from 500 to
650 mg KOH/g,
and KOH or imidazole, preferably 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, the OH number of the polyether polyol b4) is in the range from 500 to
650 mg KOH/g,
imidazole is used as alkoxylation catalyst, and the aliphatic or
cycloaliphatic diol b3) is
diethylene glycol, and the fatty acid or the fatty acid derivative is oleic
acid.
The amount of component b4) used per kg of polyetherester polyol B) is
preferably not less
than 200 mmol, more preferably not less than 400 mmol, even more preferably
not less than
600 mmol, yet even more preferably not less than 800 mmol and most preferably
not less
than 1000 mmol.
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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, 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 prepare 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 polyester 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 polyetherester polyols B) according to the present invention
is generally at
least 10 wt%, preferably at least 20 wt% and more preferably at least 25 wt%,
based on total
components B) to H).
To produce the rigid polyurethane foams by the process of the invention, use
is made of, in
addition to the above-described specific polyester polyols, the constructal
components which
are known per se, about which the following details may be provided.
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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 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 carban 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 (1PD1), 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 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-
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isocyanatomethylcyclohexane (isophorone diisocyanate, IPD1), 1,4- and/or 1,3-
bis(isocyanatomethyl)cyclohexane (HXDI), 1,4-cyclohexane diisocyanate, 1-
methy1-2,4-
and/or -2,6-cyclohexane diisocyanate and 4,4'-, 2,4'- and/or 2,2'-
dicyclohexylmethane
diisocyanate.
5
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
10 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).
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.
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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 LupranatC:).
The functionality of component A) is preferably at least two, especially at
least 2.2 and more
preferably 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, especially in the range from 6 to 9 mmol/g, and more preferably 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'-
diphenylmethane
diisocyanate, 2,2'-diphenylmethane diisocyanate and oligomeric diphenylmethane
diisocyanate. In the context of this preferred embodiment, component (al)
comprises
oligomeric diphenylmethane diisocyanate 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.
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Component C
Suitable polyester polyols C), which differ from the polyester polyols B), are
obtainable from
organic dicarboxylic acids having 2 to 12 carbon atoms, preferably aromatic
ones, 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
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 and in particular adipic acid.
Examples of dihydric
and polyhydric alcohols, in particular diols, 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 diols 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.
E-caprolactone, or hydroxycarboxylic acids, e.g. w-hydroxycaproic acid.
To prepare the further polyester polyols C), 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 7-linolenic acid, stearidonic acid, arachidonic acid, timnodonic
acid,
clupanodonic acid and cervonic acid.
CA 02861351 2014-07-16
13
In general, the mass ratio of polyetherester polyols B) to polester polyols C)
is at least 0.1,
preferably at least 0.25, more preferably at least 0.5 and especially at least
0.8. Preferably,
the proportion of total polyester polyols B) and C) which is attributable to
polyetherester
polyols B) is generally at least 25 wt%, preferably at least 50 wt%, more
preferably at least
75 wt% and especially 100 wt%. It is particularly preferable when no further
polyester polyols
C) are reacted.
Component D
According to the present invention, polyether polyols D) are used for
preparing rigid PU
foams. The polyether polyols D) 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
or
imidazole derivatives by using at least one starter molecule or starter
molecule mixture
comprising on average 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.
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.
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.
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Preference is given to using dihydric or polyhydric alcohols (also called
"starters") 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.
Particular preference is given to the use of a starter mixture of sucrose and
DEG or sucrose
and glycerol, specifically sucrose and glycerol.
The polyether polyols D), preferably polyoxypropylene polyols and
polyoxyethylene polyols,
have a functionality of preferably from 2 to 6 and in particular from 2 to 5
and number
average molecular weights of from 150 to 3000, preferably from 200 to 2000 and
in particular
from 250 to 1000.
One preferable embodiment of the invention utilizes an alkoxylated diol,
preferably an
ethoxylated diol, for example polyethylene glycol, as one part of polyether
polyol D).
In a preferred embodiment of the invention, said polyetherol component D)
consists of a
polyetherol mixture in which some of polyetherol component D) was prepared on
the basis of
propylene oxide (polyetherol component D1) and the remainder of polyetherol
component D)
was prepared on the basis of ethylene oxide (polyetherol component D2).
In a preferred embodiment of the invention, said polyetherol component D1) has
an average
OH functionality of above 3, preferably above 3.5 and more preferably above 4
and an OH
number above 300 mg KOH/g preferably above 350 mg KOH/g, more preferably above
400 mg KOH/g and specifically above 450 mg KOH/g.
In a preferred embodiment of the invention, said polyetherol component D1) has
an average
OH functionality of below 6, preferably below 5.5 and more preferably below 5
and an OH
number below 600 mg KOH/g preferably below 550 mg KOH/g and more preferably
below
500 mg KOH/g.
In a preferred embodiment of the invention, the proportion of the total amount
of polyetherol
component (D) which is attributable to the polyetherol component D1) is above
65 wt%,
preferably above 70 wt%, more preferably above 75 wt%, especially above 80 wt%
and
specifically above 85 wt%.
In a preferred embodiment of the invention, the polyetherol component D1) is
not based on
sorbitol.
CA 02861351 2014-07-16
In a preferred embodiment of the invention, the polyetherol component D1) is
based on a
polyether prepared from propylene oxide and a starter mixture of sucrose and
glycerol or
sucrose and DEG, preferably sucrose and glycerol.
5 In a preferred embodiment of the invention, the polyetherol component D2)
is based on a
polyetherol based on ethylene oxide having an average OH functionality of not
more than 3,
preferably the functionality of polyetherol component D2) is equal to 2 and
the OH number of
polyetherol component D2) is below 400 mg KOH/g, preferably below 300 mg KOH/g
and
more preferably below 200 mg KOH/g.
In a particularly preferred embodiment of the invention, the polyetherol
component D)
consists of two polyethers, a polyether (polyetherol component D1) based on
propylene
oxide and a starter mixture of sucrose and glycerol having an average OH
functionality of
above 4 and below 5 and an OH number of above 450 mg KOH/g and below 500 mg
KOH/g
and also a polyethylene glycol having an OH number below 200 mg KOH/g
(polyetherol
component D2).
The proportion of polyether polyols D) is generally in the range from 25 to 55
wt%, preferably
in the range from 29 to 45 wt%, more preferably in the range from 31 to 43
wt%, more
specifically in the range from 33 to 42 wt% and especially in the range from
35 to 40 wt%,
based on total components B) to H).
According to the present invention, the mass ratio of total components B) and
C) to
component D) is less than 1.6, especially below 1.5 or 1.4, preferably less
than 1.3, more
preferably less than 1.2, especially preferably less than 1.1, specifically
preferably less than
1 and most preferably less than 0.8.
Furthermore, the mass ratio according to the present invention for total
components B) and
C) to component D) is greater than 0.1, especially greater than 0.2,
preferably greater than
0.4, more preferably greater than 0.5 and most preferably greater than 0.6.
Component E
As flame retardants E), it is generally possible to use the flame retardants
known from the
prior art. Suitable flame retardants are, for example, brominated esters,
brominated ethers
(Ixol) or brominated alcohols such as dibromoneopentyl alcohol,
tribromoneopentyl alcohol
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,
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tris(2,3-dibromopropyl) phosphate, tetrakis(2-chloroethyl)
ethylenediphosphate, dimethyl
methanephosphonate, diethyl diethanolaminomethylphosphonate and also
commercial
halogen-comprising flame retardant polyols. By way of further phosphates or
phosphonates it
is possible to use diethyl ethanephosphonate (DEEP), triethyl phosphate (TEP),
dimethyl
propylphosphonate (DMPP), diphenyl cresyl phosphate (DPK) as liquid flame
retardants.
Apart from the abovementioned flame retardants, it is also possible to use
inorganic or
organic flame retardants such as red phosphorus, preparations comprising red
phosphorus,
aluminum oxide hydrate, antimony trioxide, arsenic oxide, ammonium
polyphosphate and
calcium sulfate, expandable graphite or cyanuric acid derivatives such as
melamine, or
mixtures of at least two flame retardants, e.g. ammonium polyphosphates and
melamine and
optionally maize starch or ammonium polyphosphate, melamine, expandable
graphite and
optionally aromatic polyesters for making the rigid polyurethane foams flame
resistant.
Preferred flame retardants have no isocyanate-reactive groups. The flame
retardants are
preferably liquid at room temperature. Particular preference is given to TCPP,
DEEP, TEP,
DMPP and DPK, especially TCPP.
The proportion of flame retardant E) is generally in the range from 10 to 40
wt%, preferably in
the range from 15 to 30 wt% and more preferably in the range from 20 to 25
wt%, based on
components B) to H).
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 carbon dioxide and carbon
monoxide. In
addition, physical blowing agents such as low-boiling hydrocarbons can be
used. Suitable
physical blowing agents are 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 can preferably be 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,
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1,1-dichloro-2,2,2-trifluoroethane, 2,2-dichloro-2-fluoroethane and
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 formic acid or any halogenated hydrocarbons as
blowing agent. It is
preferable to use water, any pentane isomer and also mixtures of water and
pentane
isomers.
The blowing agents are either wholly or partly dissolved in the polyol
component (i.e.
B+C+D+E+F+G+H) or are introduced via a static mixer immediately before foaming
of the
polyol component. It is usual for water 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 30 wt%,
preferably in the range from 3 to 15 wt% and more preferably in the range from
5 to 10 wt%,
all based on total components B) to H).
When water is used as blowing agent, it is preferably added to the polyol
component
(B+C+D+E+F+G+H) in an amount of 0.2 to 10 wt%, based on component B). The
addition of
water can take place in combination with the use of other blowing agents
described.
Preference is given to using water combined with pentane.
Component G
Catalysts G) used for preparing the rigid polyurethane foams are particularly
compounds
which substantially speed the reaction of the components B) to H) 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(dimethylamino-
propyl)urea, N-methylmorpholine or N-ethylmorpholine, N-cyclohexylmorpholine,
N,N,N',N'-
CA 02861351 2014-07-16
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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(II) 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% by weight of catalyst or
catalyst combination,
based (i.e., reckoned) on 100 parts by weight of the 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 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, either 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.
In a preferred embodiment of the invention, one part of component G) consists
of a
carboxylate salt, specifically an alkali metal carboxylate.
Further information regarding the abovementioned and further starting
materials may be
found in the technical literature, for example Kunststoffhandbuch, Volume VII,
Polyurethane,
Carl Hanser Verlag Munich, Vienna, 1st, 2nd and 3rd Editions 1966, 1983 and
1993.
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Component H
Further auxiliaries and/or addition agents H) 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 fibrous
minerals such as wollastonite, metal fibers and in particular glass fibers of
various length,
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.
CA 02861351 2014-07-16
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 H), although the
content of
mats, nonwovens and woven fabrics of natural and synthetic fibers can reach
values of up to
5 80 wt%, based on the weight of components A) to H).
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
10 Publishers 1962 and 1964, or Kunststoff-Handbuch, Polyurethane, Volume
VII, Hanser-
Verlag, Munich, Vienna, 1st and 2nd Editions, 1966 and 1983.
The present invention further provides a polyol component comprising
10 to 50 wt% of polyetherester polyols B),
15 0 to 30 wt% of further polyester poylols C),
to 55 wt% of polyether polyols D),
10 to 40 wt% of flame retardants E),
1 to 30 wt% of blowing agents F),
0.5 to 10 wt% of catalysts G), and
20 0 to 20 wt%, especially 0.5 to 20 wt%, of further auxiliary and addition
agents H),
each as defined above and each based on the total weight of components B) to
H), wherein
the wt% add up to 100 wt%, and wherein the mass ratio of total components B)
and C) to
component D) is less than 1.6.
25 It is particularly preferable for the polyol component to comprise
25 to 40 wt% of polyetherester polyols B),
0 wt% of further polyester poylols C),
29 to 45 wt% of polyether polyols D),
15 to 30 wt% of flame retardants E),
3 to 15 wt% of blowing agents F),
0.5 to 10 wt% of catalysts G),
0.5 to 5 wt% of further auxiliary and addition agents H),
each as defined above and each based on the total weight of components B) to
H), wherein
the wt% add up to 100 wt%, and wherein the mass ratio of total components B)
and C) to
component D) is less than 1.3.
The mass ratio of total components B) and C) to component D) in the polyol
components of
the present invention is preferably greater than 0.1, more particularly
greater than 0.2, more
CA 02861351 2014-07-16
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preferably greater than 0.4, even more preferably greater than 0.5 and most
preferably
greater than 0.6.
To produce the rigid polyurethane foams of the present invention, the
polyisocyanates A), the
specific polyester polyols B) of the present invention, optionally the further
polyester polyol
C), the polyetherols D) and the further components E) to H) are mixed in such
amounts that,
in the reaction, the equivalence ratio of NCO groups on polyisocyanates A) to
total reactive
hydrogen atoms on component B), optionally C) and also D) to H), is in the
range from 1 to
3.5:1, preferably in the range from 1 to 2.5:1, more preferably in the range
from 1.1 to 2.1:1,
even more preferably in the range from 1.2 to 2.0:1, especially in the range
from 1.3 to 1.9:1,
more specifically in the range from 1.4 to 1.8:1 and advantageously in the
range from 1.4 to
1.7:1.
The molar ratio of NCO groups on polyisocyanates A) to total reactive hydrogen
atoms on
components B), optionally C), and D) to H) is preferably greater than 1.0:1,
preferably above
1.1:1, more preferably above 1.2:1, especially above 1.3:1 and specifically
above 1.4:1.
The examples which follow illustrate the invention.
Examples
The following polyester polyols (polyesterol 1, polyesterol 3 and polyesterol
5) and
polyetherester polyols (polyesterol 2, polyesterol 4, polyesterol 6 and
polyesterol 7) were
used:
Polyesterol 1 (comparator): esterification product of terephthalic acid (34
mol%), oleic acid
(9 mol%), diethylene glycol (40 mol%) and glycerol (17 mol%) having a hydroxyl
functionality
of 2.3, a hydroxyl number of 244 mg KOH/g and an oleic acid content in the
polyesterol of
20% by weight.
Polyesterol 2 (invention): esterification product of terephthalic acid (31
mol%), oleic acid
(8 mol%), diethylene glycol (43 mol%) and a polyether (18 mol%) based on
glycerol and
ethylene oxide having an OH functionality of 3 and a hydroxyl number of 546 mg
KOH/g,
prepared in the presence of imidazole as alkoxylation catalyst. This polyether
was not
worked up before being used in the subsequent esterification. The polyesterol
has a hydroxyl
functionality of 2.3, a hydroxyl number of 239 mg KOH/g and an oleic acid
content in the
polyesterol of 15% by weight.
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Polyesterol 3 (comparator): esterification product of phthalic anhydride (30
mol%), oleic acid
(12 mol%), diethylene glycol (40 mol%) and trimethylolpropane (18 mol%) having
a hydroxyl
functionality of 2.2, a hydroxyl number of 249 mg KOH/g and an oleic acid
content in the
polyesterol of 25% by weight.
Polyesterol 4 (invention): 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 having an OH functionality of 3 and a
hydroxyl
number of 610 mg KOH/g, prepared in the presence of KOH as alkoxylation
catalyst with
subsequent neutralization and removal of the potassium salt formed. The
polyesterol has a
hydroxyl functionality of 2.2, a hydroxyl number of 244 mg KOH/g and an oleic
acid content
in the polyesterol of 24% by weight.
Polyesterol 5 (comparator): esterification product of terephthalic acid (35
mol%), oleic acid
(7 mol%), diethylene glycol (40 mol%) and glycerol (18 mol%) having a hydroxyl
functionality
of 2.5, a hydroxyl number of 256 mg KOH/g and an oleic acid content in the
polyesterol of
16% by weight.
Polyesterol 6 (invention): esterification product of terephthalic acid (29
mol%), oleic acid
(10 mol%), diethylene glycol (36 mol%) and a polyether (25 mol%) based on
glycerol and
ethylene oxide having an OH functionality of 3 and a hydroxyl number of 535 mg
KOH/g,
prepared in the presence of KOH as alkoxylation catalyst with subsequent
neutralization and
removal of the potassium salt formed. The polyesterol has a hydroxyl
functionality of 2.5, a
hydroxyl number of 245 mg KOH/g and an oleic acid content in the polyesterol
of 15% by
weight.
Polyesterol 7 (invention): esterification product of terephthalic acid (29
mol%), oleic acid
(10 mol%), diethylene glycol (36 mol%) and a polyether (25 mol%) based on
glycerol and
ethylene oxide having an OH functionality of 3 and a hydroxyl number of 540 mg
KOH/g,
prepared in the presence of imidazole as alkoxylation catalyst. This polyether
was not
worked up before being used in the subsequent esterification. The polyesterol
has a hydroxyl
functionality of 2.5, a hydroxyl number of 246 mg KOH/g and an oleic acid
content in the
polyesterol of 15% by weight.
Determination of curing and brittleness of rigid polyurethane foam
Curing was determined using the bolt test. For this, at 2.5, 3, 4, 5, 6 and 7
minutes after
mixing the components of the polyurethane foam in a polystyrene beaker, a
steel bolt with a
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spherical cap 10 mm in radius was pressed by a tensile/compressive tester 10
mm deep into
the mushroom-shaped foam formed. The maximum force in N required here is a
measure of
the curing of the foam.
Brittleness was determined for the rigid polyisocyanurate foam by determining
the time at
which the surface of the rigid foam displayed visible zones of breakage in the
bolt test.
Brittleness was further determined subjectively directly after foaming by
compressing the
foam and graded on a scale from 1 to 6, where 1 denotes a scarcely brittle
foam and 6 a
foam of high brittleness.
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.
Determination of dimensional stability
Dimensional stability is determined by determining element thickness after
foaming. For this,
a sandwich element with a 0.05 mm thick aluminum foil as outer layer material
is produced in
the double belt process and element thickness is determined in the center of
the element 5
minutes after production. The closer the element thickness thus determined is
to the spec
element thickness (170 mm in the present case), the better the dimensional
stability.
Inventive examples 1 and 2 and comparative examples 1 and 2
Production of rigid polyurethane foams (variant 1):
The isocyanates and the components which are reactive toward isocyanate were
foamed
together with the blowing agents, catalysts and all further addition agents at
a constant
mixing ratio of polyol component to isocyanate of 100:180.
Polyol component:
30 parts by weight of polyesterol as per inventive or comparative examples;
36.5 parts by weight of polyetherol having an OH number of 490 mg KOH/g
prepared by
polyaddition of propylene oxide onto a sucrose/glycerol mixture as starter
molecule and an
average functionality of 4.3;
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6 parts by weight of polyetherol from ethoxylated ethylene glycol having an
hydroxyl
functionality of 2 and a hydroxyl number of 190 mg KOH/g;
25 parts by weight of trischloroisopropyl phosphate (TCPP) as flame retardant;
and
2.5 parts by weight of Niax Silicone L6635 stabilizer from Momentive, and also
Addition agents in the polyol component:
5.5 parts by weight of S 80:20 pentane (consisting of 80 wt% n-pentane and 20
wt%
isopentane);
about 2.2 parts by weight of water; and
1.0 part by weight of potassium acetate solution (47 wt% in ethylene glycol).
Furthermore dimethylcyclohexylamine (DMCHA) to adjust the fiber times,
hereinafter also
referred to as catalyst 1.
lsocyanate component:
180 parts by weight of Lupranat M50 (polymeric methylene(diphenyl
diisocyanate) (PMDI),
having a viscosity of about 500 mPa*s at 25 C from BASF SE)
The components were intensively mixed using a laboratory stirrer. Foam density
was
adjusted to 41 +/- 1 g/L by varying the water content while keeping the
pentane content
constant at 5.5 parts. Fiber time was further adjusted to 45 +/- 1 s by
varying the proportion
of dimethylcyclohexylamine (DMCHA) (catalyst 1).
The results are summarized in table 1.
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Table 1:
Polyesterol 1 Polyesterol 2 Polyesterol 3
Polyesterol 4
(comparator) (comparator)
curing
2.5 min 45 47 44 47
3 min 59 58 57 59
4 min 84 83 80 81
sum (2.5; 3 and 4 min) 188 188 181 187
brittleness (subjective) 4.5 3 3.5 3
breakage in bolt test 6 min no breakage 7 min no
breakage
catalyst 1 1.6 1.4 1.6 1.5
It is clearly apparent that inventive polyester polyols 2 and 4 reduce the
brittleness of the
5 insulant and increase the self-reactivity of the systems without having
any adverse effect on
foam curing.
Inventive examples 3 and 4 and comparative example 3
10 Production of rigid polyurethane foams (variant 2)
The isocyanates and also the isocyanate-reactive components were foamed
together with
the blowing agents, catalysts and all further addition agents at a constant
mixing ratio of
polyol component to isocyanate of 100:160.
Polyol component:
30 parts by weight of polyesterol as per inventive or comparative examples;
37 parts by weight of polyetherol having an OH number of 490 mg KOH/g prepared
by
polyaddition of propylene oxide onto a sucrose/glycerol mixture as starter
molecule and an
average functionality of 4.3;
6 parts by weight of polyetherol from ethoxylated ethylene glycol having a
hydroxyl
functionality of 2 and a hydroxyl number of 190 mg KOH/g;
parts by weight of trischloroisopropyl phosphate (TCPP) as flame retardant;
and
25 2 parts by weight of Niax Silicone L6635 stabilizer from Momentive, and
also
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Addition agents in the polyol component:
5.5 parts by weight of S 80:20 pentane;
about 1.8 parts by weight of water; and
1.2 parts by weight of potassium acetate solution (47 wt% in ethylene glycol).
Furthermore, about 0.9 part by weight of dimethylcyclohexylamine (DMCHA) to
adjust the
fiber time.
Isocyanate component:
160 parts by weight of Lupranat M50
Sandwich elements 170 mm in thickness were produced by the double belt
process. Foam
density was adjusted to 38 +/- 1 g/L by varying the water content while
keeping the pentane
content constant at 5.5 parts. Fiber time was further adjusted to 35 +/- 1 s
by varying the
proportion of dimethylcyclohexylamine.
The results are summarized in table 2.
Table 2: Results of tests to produce 170 mm thick sandwich elements by double
belt process
Polyester polyol: Polyesterol 5 Polyesterol 6 Polyesterol 7
(comparator)
element thickness 186 mm 180 mm 180 mm
after foaming
It is clearly apparent that inventive polyester polyols 6 and 7 improve the
dimensional stability
of rigid polyurethane foam.
