Note: Descriptions are shown in the official language in which they were submitted.
= CA 02865728 2014-08-27
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PRODUCING RIGID POLYMER FOAMS
Description
The present invention relates to a process for producing a rigid polymer foam,
to the rigid
polymer foam thus obtainable and to its use.
Polymer foams, such as polyurethane and polyurethane-polyurea foams based on
di- or
polyisocyanates are well known. Rigid polyurethane phases have a distinctly
lower melting
temperature compared with a rigid polyamide phase which has a decisive
influence on using
the materials at high temperatures.
It is further known to react carboxylic acids with isocyanates to form mixed
carbamic an
hydrides with partial further reaction to form amides. The reaction and the
reaction
mechanism are described for example by R. W. Hoffman in Synthesis 2001, No. 2,
243 - 246
and I. Scott in Tetrahedron Letters, Vol. 27, No. 11, pp 1251 - 1254, 1986.
Oligomeric compounds that use a reaction between a diisocyanate and a
dicarboxylic acid
are described by K. Onder in Rubber Chemistry and Technology, Vol. 59, pages
615 - 622
and by T. 0. Ahn in Polymer Vol. 39, No. 2, pp. 459 - 456, 1998.
EP 0 527 613 A2 describes the production of foams comprising amide groups.
These are
produced using organic polyisocyanates and polyfunctional organic acids. The
foams are
produced using an addition reaction by reacting an organic polyisocyanate with
the reaction
product of a polyoxyalkylene and of an organic polycarboxylic acid component.
The two
isocyanate groups react with a compound which generates carbon dioxide. This
compound is
the reaction product of a polyoxyalkylene polyamine or of a polyol component
with an organic
polycarboxylic acid component. The polyoxyalkylenepolyamine or polyol
component has an
average molecular weight of 200 to 5000 g/mol. The starting temperature for
the reaction is
at least 150 C, while the reaction time is in a range from half an hour to
twelve hours.
DE 42 02 758 Al describes a foam comprising urethane and amide groups which is
obtainable by using polyhydroxycarboxylic acids having a chain length of 8 to
200 carbon
atoms. These polyhydroxycarboxylic acids are conveniently produced by ring-
opening
epoxidized unsaturated fatty acids with hydroxyl-containing compounds, such as
water,
alcohol or hydroxycarboxylic acids. Foam densities range from 33 to 190 kg/m3.
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JP 2006-137870 A describes a process for producing a polyamide foam and the
use of this
polyamide foam. A polyisocyanate component and a polyester polycarboxylic acid
component are made to react with each other using a phosphine oxide as
catalyst. The
reaction mixture is heated to 170 C at least.
The known polyurethane-polyamide foams are disadvantageous because the
starting
materials either only react at comparatively high temperatures or do not react
to completion,
and their density is not in line with standard polyurethane recipes.
The present invention has for its object to provide rigid polymer foams that
are dimensionally
stable even at high temperatures in the presence of moisture and/or at high
pressures, so
that they can even be used in the engine, transmission or exhaust environment,
and their
methods of making. The rigid polymer foams shall further have advantageous
properties with
respect to sustained elasticity, abrasion resistance, tensile strength, tongue
tear strength and
compressive stresses. The present invention further has for its object to
provide a rigid
polymer foam comprising polyamide groups obtainable by reaction of
diisocyanate
components with dicarboxylic acid components within a short time and
preferably without the
need for additional blowing agents.
These objects are achieved, in accordance with the present invention, by a
process for
producing a rigid polymer foam comprising reacting components A to C in the
presence of
component D or an isocyanate-functional prepolymer of components A and B with
component C in the presence of component D, the total amount of which is 100
wt%,
(A) 35 to 65 wt%, preferably 40 to 62 wt% and especially 42 to 55 wt% of at
least one
polyisocyanate component A,
(B) 5 to 50 wt%, preferably 10 to 40 wt% and especially 15 to 30 wt% of at
least one polyol
component B,
(C) 1 to 59 wt%, preferably 2 to 50 wt% and especially 5 to 45 wt% of at
least one
polycarboxylic acid component C, and
(D) 0.01 to 3 wt%, preferably 0.02 to 2 wt% and especially 0.05 to 1 wt% of
at least one
Lewis base component D,
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wherein the reaction takes place with release of carbon dioxide. Further
ingredients may be
included in the reaction mixture in addition to components A to D.
The process of the present invention involves the reaction of a carboxylic
acid group with an
isocyanate group to form a mixed carbamic anhydride which reacts further to
form an amide.
CO2 elimination from the carbamic anhydrides using Lewis bases as catalysts
provides the
polymer foams at a similar rate to, for example, polymer foams based on
polyurethane. Since
this reaction releases the blowing gas from the components themselves, it can
be carried out
in the absence of water and blowing agent.
A rigid polymer foam can be understood as meaning in the context of the
present invention
that, in the course of the production of the rigid polymer foam, the reaction
mixture
undergoes a volume change until the reaction has finally ended, even after the
main reaction
has ended, since the foam matrix is still viscous and the gas can continue to
expand within
the foam. It is advantageously possible for the polymer foam to include
cells/cavities within
the polymer foam and also on the surface of the polymer foam.
The rigid polymer foams of the present invention have a compressive stress at
10% relative
deformation of not less than 80 kPa, preferably not less than 150 kPa and more
preferably
not less than 180 kPa. The rigid polymer foam further has a DIN ISO 4590
closed-cell
content of not less than 70% and preferably above 85%. Further details
concerning rigid
polymer foams of the present invention appear in "Kunststoffhandbuch, Band 7,
Polyurethane", Carl Hanser Verlag, 3rd edition 1993, chapter 6. DIN 7726 can
also be
referenced for polyurethane foams.
The present invention utilizes the Lewis base component as an accelerant or
catalyst in the
reaction, making it possible for the polyaddition and the polycondensation to
be carried out
uniformly and at a high rate to ensure that not only the molecular weight
buildup and the
gelling of the resulting polymer but also the expansive foaming, especially
due to the
released carbon dioxide, take place simultaneously so as to form a stable
uniform foam
which then solidifies. The inventors found that the use of one Lewis base
component for both
the elementary reactions is sufficient and that the reactions coordinate with
each other such
that gas production and foam formation are simultaneously accompanied by a
viscosity
increase which leads to a uniform foam being produced. Once the viscosity has
increased
too much, foam formation can be impaired. If, during foam formation, the
viscosity increase is
insufficient and/or no gelling whatsoever has ensued, the produced gas is able
to rise
through the liquid polymer and escape therefrom and/or accumulate at the
surface,
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preventing the formation of a uniform foam structure. These problems are
overcome in the
process of the present invention, resulting in a rigid polymer foam having a
uniform cellular
distribution throughout the entire cross section of the rigid polymer foam.
The present inventors further found that when the components are used in the
amounts of
the present invention, carbon dioxide formation is sufficient to produce a
suitable rigid
polymer foam, eliminating the need to add external blowing agents. When a foam
of lower
density is desired, however, external blowing agents can also be additionally
used. It is
preferable to dispense with the addition of external blowing agents.
Similarly, in accordance
with the present invention, any addition of water to the reaction mixture or
the presence of
water in the reaction mixture is avoided. The reaction is preferably carried
out waterlessly,
i.e., in the absence of water. There is preferably no water in the reaction
mixture.
The individual components used according to the present invention will now be
more
particularly elucidated.
For the purposes of the present invention, at least one polyisocyanate
component, herein
also referred to as component A, comprises polyfunctional aromatic and/or
aliphatic
isocyanates, for example diisocyanates.
It may be advantageous for the polyisocyanate component to have an isocyanate
group
functionality in the range from 1.8 to 5.0, more preferably in the range from
1.9 to 3.5 and
most preferably in the range from 2.0 to 3Ø
It is preferable for the suitable polyfunctional isocyanates to comprise on
average from 2 to
not more than 4 NCO groups. Examples of suitable isocyanates are 1,5-
naphthylene
diisocyanate, xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate
(TMXDI),
diphenyldimethylmethane diisocyanate derivatives, di- and
tetraalkyldiphenylmethane
diisocyanate, 4,4-dibenzyl diisocyanate, 1,3-phenylene diisocyanate, 1,4-
phenylene
diisocyanate, the isomers of tolylene diisocyanate (TDI), optionally in
admixture, 1-methyl-
2,4-diisocyanatocyclohexane, 1,6-diisocyanato-2,2,4-trimethylhexane, 1,6-
diisocyanato-
2,4,4-trimethylhexane, 1-isocyanatomethy1-3-isocyanato-1,5,5-
trimethylcyclohexane (1PD1),
chlorinated and brominated diisocyanates, phosphorus-containing diisocyanates,
4,4-
diisocyanatophenylperfluorethane, tetramethoxybutane 1,4-diisocyanate, butane
1,4-
diisocyanate, hexane 1,6-diisocyanate (HD!), dicyclohexylmethane diisocyanate,
cyclohexane 1,4-diisocyanate, ethylene diisocyanate, bisisocyanatoethyl
phthalate, also
CA 02865728 2014-08-27
polyisocyanates with reactive halogen atoms, such as 1-chloromethylphenyl 2,4-
diisocyanate, 1-bromomethylphenyl 2,6-diisocyanate, 3,3-bischloromethyl ether
4,4-diphenyl
diisocyanate.
5 Further important diisocyanates are trimethylhexamethylene diisocyanate,
1,12-
diisocyanatododecane and dimer fatty acid diisocyanate.
4,4-Diphenylmethane diisocyanate (MDI), hydrogenated MDI (1-i12MDI) and
polymeric
methylene diphenyl diisocyanate are particularly suitable and the polymeric
methylene
diphenyl diisocyanate advantageously has a functionality of not less than 2.2.
The process of the present invention involves the reaction of 35 - 65 wt% of
at least one
polyisocyanate component, preferably of 40 - 60 wt% of at least one
polyisocyanate
component and more preferably of 42 - 55 wt% of at least one polyisocyanate
component.
More particularly, component A can be contacted with the particular components
B, C and D
together, in succession or with each one first. For example, components A and
B can be
reacted to produce an isocyanate-functional prepolymer. This prepolymer in
turn has an
isocyanate functionality of preferably 2.5 to 3.
In a further embodiment of the process according to the present invention,
component A has
an average molecular weight in the range from 100 g/mol to 750 g/mol,
advantageously in
the range from 130 g/mol to 500 g/mol and especially in the range from 250
g/mol to
450 g/mol. This polyisocyanate component can ideally provide a high density of
amide bonds
per polymer unit which is produced in the process of the present invention.
This makes it
possible to generate a rigid phase having advantageous properties. Amides have
higher
melting points and higher decomposition temperatures than urethanes. Rigid
polymer foams
having a higher proportion of amide bonds therefore likewise have a higher
melting point and
a higher decomposition temperature and hence are particularly suitable for
high-temperature
applications, for example as insulating material in the engine compartment of
a motor
vehicle.
For the purposes of the present invention, at least one polyol component B,
herein also
referred to as component B, comprises organic compounds having two or more
free hydroxyl
groups. These compounds are preferably free of other functional groups or
reactive groups,
such as acid groups. Preferably, polyol component B is a polyether polyol or a
polyester
CA 02865728 2014-08-27
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polyol. Examples thereof are a polyoxyalkylene, a polyoxyalkenyl, a polyester
diol, a
polyesterol, a polyether glycol, especially a polypropylene glycol, a
polyethylene glycol, a
polypropylene glycol, a polypropylene ethylene glycol, or mixtures thereof. A
mixture can be
understood as meaning for example a copolymer, but also a mixture of polymers.
The
polyglycol component preferably has an average molecular weight in the range
from
200 g/mol to 6000 g/mol, especially in the range from 250 g/mol to 3000 g/mol
and more
preferably in the range from 300 g/mol to 800 g/mol.
In a further embodiment of the process according to the present invention,
component B has
an OH number of 10 mg KOH/g to 1000 mg KOH/g. More particularly, component B
can
have an OH number of 30 mg KOH/g to 500 mg KOH/g.
Components A and (B + C) may be used in a molar ratio of isocyanate groups on
component
A to isocyanate-reactive groups, such as hydroxyl or carboxylic acid groups on
components
B and C in the range of preferably 10:1 to 1:2, more preferably from 5:1 to
1:1.5 and
especially from 3:1 to 1:1.
For the purposes of the present invention, at least one polycarboxylic acid
compound,
preferably dicarboxylic acid component, herein also referred to as component
C, comprises
an organic compound having at least or exactly two carboxyl groups, -COON, or
an acid
anhydride thereof. The carboxyl groups can be bonded to alkyl or cycloalkyl
moieties or to
aromatic moieties. Aliphatic, aromatic, araliphatic or alkylaromatic
polycarboxylic acids may
be concerned, which may also contain heteroatoms, especially nitrogen atoms
and other
functional groups, e.g., hydroxyl groups or keto groups. The poly- or
dicarboxylic acid
component can be used in the processes of the present invention at from 1 to
59 wt%,
advantageously at from 2 to 50 wt% and more preferably at from 5 to 45 wt% in
the reaction.
Preferably, component C does not contain any hydroxyl groups in addition to
the carboxyl
groups. Hence polyhydroxy carboxylic acids are preferably not concerned. It
may be
particularly advantageous to use poly- or dicarboxylic acids which exclusively
have carboxyl
groups and/or anhydrides thereof as functional groups. It may similarly be
possible to use for
example, in a further variant, salts or esters of component C, for example the
salt formed by
the carboxylate and the ion of an alkaline earth metal. Preferably, free acid
groups are
present in the reaction. Examples of suitable polycarboxylic acids are
C3-12alkanepolycarboxylic acids or -dicarboxylic acids, for example malonic
acid, succinic
acid, glutaric acid, adipic acid or higher dicarboxylic acids, which may also
be C1_3alkyl
substituted. Examples of suitable aromatic poly- or dicarboxylic acids are
phthalic acid,
isophthalic acid, terephthalic acid. Further possibilities include aliphatic
unsaturated poly- or
CA 02865728 2014-08-27
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dicarboxylic acid, such as fumaric acid or maleic acid and keto-containing
dicarboxylic acids,
such as oxaloacetic acid.
It is preferable for component C to be used in the reaction as an at least
partial, preferably
complete solute in component B. Even polycarboxylic acids which are solid at
the reaction
temperature are thus simple to introduce into the reaction or to be more
precise the reaction
mixture.
For the purposes of the present invention, at least one Lewis base component,
herein also
referred to as component D, may be understood as meaning a compound capable of
providing electron pairs, for example in accordance with the meaning of the
term "Lewis
base" in chemistry. Preferably, the free electron pair is in an compound, but
can also be
bound to a metal or to an organometallic compound.
The Lewis base is preferably used in an amount of from 0.02 to 2 wt% and more
preferably
0.05 to 1 wt%.
The total amounts of components A to D sum to 100 wt%. This means that the
reaction
mixture can but need not contain further components other than A to D. The
quantitative
recitations of components A to D are standardized with regard to their sum
total.
In a preferred embodiment of the process according to the present invention,
the Lewis base
component is selected from the group consisting of N-methylimidazole,
melamine, guanidine,
cyanuric acid, dicyandiamide or their derivatives. Ideally, the Lewis base is
able to generate
the formation of a carboxylate from the carboxylic acid, so that this
carboxylate can quickly
react with the diisocyanate component. The Lewis base likewise functions as a
catalyst for
the detachment of CO2 in the reaction of the diisocyanate component with the
dicarboxylic
acid component. A synergistic effect may particularly advantageously result
from the
formation of the carboxylate and the detachment of CO2 using the Lewis base,
and so only
one catalyst or accelerant is needed.
The process for producing a rigid polymer foam can be carried out at a
starting temperature
in the range from at least 15 C to at most 100 C, more preferably from at
least preferably
15 C to at most 80 C, especially at a starting temperature from at least 25 C
to at most 75 C
and more preferably at a starting temperature from at least 30 C to at most 70
C. The
reaction of the abovementioned components can take place at atmospheric
pressure. This
reduces for example the energy requirements of producing the rigid polymer
foam. It is
CA 02865728 2014-08-27
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similarly possible to circumvent the disadvantageous effect of a higher
temperature on the
formation of a scorched core, and gas production/foam formation and viscosity
increase are
well matched to each other, as described above.
The reactor and the reaction mixture are controlled to the temperature at
which the reaction
is started. The temperature can rise in the course of the reaction. Typically,
the receptacle in
which the reaction takes place is not separately heated or cooled, and so the
heat of reaction
is removed to the environment via the receptacle walls or the air. Since the
reaction is
accelerated by the Lewis base component used in the process of the present
invention in
that the Lewis base acts as a catalyst, the process of the present invention
provides
complete and rapid further reaction between diisocyanate components and
dicarboxylic acid
components to form an amide component. But advantageously the reaction need
not be
carried out under the conditions of an elevated temperature, as described in
EP 0 527 613
A2 for example.
In a further embodiment of the process according to the present invention, the
reaction can
be carried out with short-chain dicarboxylic acids and di- or polyisocyanates.
This can make
it possible to produce block copolymers for example.
In a preferred embodiment of the process according to the invention, the
reaction to form the
thermoplastic polymer foam starts after at least 3 to 90 seconds, especially
after 5 to 70
seconds and most preferably after 5 to 40 seconds. The reaction starting is to
be understood
as meaning that components A, B, C and D react to form the corresponding
product(s) after
they have been brought into contact with one another. Advantageously,
externally heated
components or reactors are not needed.
In a further embodiment of the process according to the present invention, the
density of the
rigid polymer foam is preferably in the range from 10 g/I to 200 g/I, more
preferably in the
range from 12 g/I to 80 g/I and especially in the range from 15 g/l to 50
g/I.This makes it
advantageously possible to obtain a foam density which is very difficult to
obtain with
polyurethanes. But ideally diisocyanate components and thus likewise similar
conditions in
the production can be used.
In a further embodiment of the process according to the present invention, the
reaction takes
place with a foam stabilizer and the stabilizer preferably comprises a
siloxane copolymer.
This polysiloxane copolymer is preferably selected from the group comprising
polyether-
polysiloxane copolymers, such as polyether-polydimethylsiloxane copolymers.
CA 02865728 2014-08-27
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The present invention further provides a rigid polymer foam deriving from
polyisocyanates,
polyols or an isocyanate-functional prepolymer thereof and also polycarboxylic
acids as
monomers, comprising urethane and amide groups in the polymer main chain and
having a
foam density of 10 g/I to 200 g/I, and also the use of said rigid polymer foam
for thermal
insulation or as core foam.
The present invention further provides a polyol mixture comprising components
B, C and D
as defined above, wherein component C may be a solute in component B and
wherein the
above quantitative recitations for components B, C and D, the sum total of
which is in the
range from 35 to 65 wt%, preferably from 38 to 60 wt% and especially from 45
to 58 wt%,
only indicate the quantitative ratios between components B, C and D.
For the purposes of the present invention, a polyaddition product is a
chemical reaction
product where the reactants react with each or one another without the
formation of low
molecular weight by-products, as for example water or CO2 in urethane
formation for
example. For the purposes of the present invention, a polycondensation product
can be
understood as meaning a product which, in the reaction of two reactants,
provides at least
one low molecular by-product, for example carbon dioxide in amide formation.
Accordingly, a
polyglycol component can combine with a diisocyanate component to form a
polyaddition
product and a dicarboxylic acid component with the diisocyanate component to
form a
carbamic anhydride with further reaction to form an amide compound, by CO2
formation, in a
polycondensation reaction.
The present invention further provides for the use of the rigid polymer foam
of the present
invention for thermal insulation or as engineering material.
For thermal insulation, the use preferably takes the form of being for
production of
refrigerating or freezing appliances, appliances for hot water preparation or
storage or parts
thereof, or for thermal insulation of buildings, vehicles or appliances.
In the above applications especially, the rigid polymer foam of the present
invention is used
to form the thermal insulating layer in the devices or appliances, buildings
or vehicles. The
rigid polymer foam of the present invention can also be used to form the
entire housing or
outer shells of appliances, buildings or vehicles.
CA 02865728 2014-08-27
As an engineering material, the rigid polymer foam of the present invention is
preferably used
as core foam for producing sandwich composites. Sandwich composites of this
type typically
have a core of a rigid polymer foam and are paneled or sheathed with a
fiberglass-reinforced
plastic. This sheathing or paneling plastic is freely choosable. Epoxy or
polyester resins are
5 frequently concerned.
Sandwich composites of this type are preferentially used in the automotive,
shipbuilding,
building construction or wind power industry.
10 For the purposes of the present invention, vehicles are air, land or
water vehicles, especially
airplanes, automobiles or ships.
A person skilled in the art will be aware of further uses for the rigid
polymer foams of the
present invention.
The examples which follow will further elucidate the invention:
Examples:
The examples hereinbelow demonstrate the production and properties of rigid
polymer
foams. The materials of the present invention were produced in the lab using a
blender.
Unless otherwise stated, the reaction was carried out at ambient temperature
(22 C) as
starting temperature, i.e., the components were reacted at ambient temperature
in a non-
temperature-controlled reactor or receptacle, and the heat of reaction was
moved to the
environment.
The following rigid polymer foams were produced in the lab in accordance with
table 1. The
room temperature solid dicarboxylic acid components were first melted and
dissolved in the
polyol component. The diol-dicarboxylic acid mixture was then reacted with a
polyisocyanate.
Foam cubes having a volume of 201 were produced and subsequently subjected to
mechanical testing. The composition of the starting substances and also the
results of the
testing are reported in table 1.
In addition to the inventive rigid polymer foams of examples 1, 2 and 3, two
hitherto
customary rigid polymer foams were produced from known compositions as
comparative
CA 02865728 2014-08-27
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examples 1 and 2. This required the use of mixtures of multiple polyols and
mixtures of
multiple catalysts to arrive at usable rigid polymer foams.
Such a multiplicity of polyol and catalyst components are no longer needed in
the process of
the present invention. Rigid polymer foams having outstanding properties we're
obtained with
just a single polyol component and with just a single catalyst, as is apparent
from the tables
hereinbelow.
=
Table 1
Ex. 1 Ex. 2 Ex. 3 Comp. 1 Comp. 2
acid 1 9.8
acid 2 13.5
acid 3 34.9
acid 4 0.6
polyol 1 28.7 31.5 17.1 7.5
polyol 2 18.3
polyol 3 5.7
polyol 4 3
polyol 5 22.9
polyol 6 2.2
polyol 7 6.7
iso 1 61 54 46.8 58.3
iso 2 57.6
stabilizer 1 0.4 0.8 0.8
stabilizer 2 0.8
stabilizer 3 0.2
stabilizer 4 0.5
cat 1 0.1 0.2 0.4 0.1
cat 2 0.9
cat 3 0.5
cat 4 0.2
blowing agent 1 3.0
blowing agent 2 1.5
additive 9.5
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The meanings are:
acid 1: pentanedioic acid M=132 g/mol
acid 2: methylenesuccinic acid M=130 g/mol
acid 3: dicarboxylic acid mixture with average molecular weight 800 g/mol
acid 4: 85 parts of methanoic acid in 15 parts of water
polyol 1: polypropylene glycol with average molecular weight (MW) 420
g/mol
polyol 2: polyester diol (phthalic acid-oleic acid polyester diol) with
average molar mass
600 g/I
polyol 3: polyesterol (phthalic acid-oleic acid polyester diol) with
average molar mass 510
g/I and average functionality 2.2
polyol 4: polyethylene glycol with average molecular weight (MW) 600 g/mol
polyol 5: polypropylene glycol with average molecular weight (MW) 500
g/mol
polyol 6: polypropylene glycol with average molecular weight (MW) 1040
g/mol
polyol 7: polypropylene glycol with average molecular weight (MW) 1070
g/mol
additive: tri-2-chloroisopropyl phosphate
blowing agent 1: n-pentane
blowing agent 2: water
iso 1: polymeric methylenediphenylene diisocyanate having an average
molar mass of
337 g/mol and a functionality of 2.7
iso 2: polymeric methylenediphenylene diisocyanate having an average
molar mass of
362 g/mol and a functionality of 2.8
stabilizer 1: polyether-polysiloxane copolymer
stabilizer 2: polyether-polydimethylsiloxane
stabilizer 3: silicone-glycol copolymer
stabilizer 4: polyether-polydimethylsiloxane copolymer
cat 1: 1-methylimidazole
cat 2: 30 parts of a bis(2-dimethylaminoethyl) ether in dipropylene
glycol
cat 3: 40 parts of potassium formate, 6 parts of water, 54 parts of
monoethylene glycol
cat 4: N,N-dimethylcyclohexylamine
Example 1 (inventive)
53 parts of pentanedioic acid and 159 parts of polypropylene glycol having an
MW of
420 g/mol were heated together at above 100 C in a heating cabinet until all
the
CA 02865728 2014-08-27
13
pentanedioic acid had melted. This acid-polyol mixture was then homogenized
and cooled
down to room temperature before it was admixed with 2.1 parts of polyether-
polysiloxane
copolymer and 0.7 part of 1-methylimidazole. Addition of 337 parts of
polymeric
methylenediphenylene diisocyanate is followed by vigorous commixing with the
lab stirrer for
10 s. Directly thereafter, the system was poured into a cube mold, where it
underwent
expansive foaming. Test specimens were taken from the polyamide-polyurethane
foam thus
produced and subjected to mechanical/thermal tests.
Example 2 (inventive)
75 parts of methylenesuccinic acid and 175 parts of polypropylene glycol
having an MW of
420 g/mol were heated together to 170 C in a heating cabinet until all the
methylenesuccinic
acid had melted. This acid-polyol mixture was then homogenized and cooled down
to 35 C
before it was admixed with 4 parts of polyether-polysiloxane copolymer and 1.2
part of 1-
methylimidazole. Vigorous commixing with 300 parts of polymeric
methylenediphenylene
diisocyanate is effected with the lab stirrer for 10 s. The test specimens
were produced and
tested as described in example 1.
Example 3 (inventive)
234.5 parts of dicarboxylic acid mixture having an average molar mass of 850
g/I and 115
parts of polypropylene glycol having an MW of 420 g/mol were heated together
to 40 C in a
heating cabinet. This acid-polyol mixture was mixed with 5.4 parts of
polyether-polysiloxone
copolymer and 2.7 parts of 1-methylimidazole. Then, 315 parts of polymeric
methylenediphenylene diisocyanate were weighed in, followed by commixing with
the lab
stirrer. The test specimens were produced and tested as described in example
1.
Comparator to example 1
The components as per table 1 in the Comp. 1 column with the exception of iso
2 were
weighed in together pro rata for an overall batch size of 350 parts and then
homogenized.
This mixture was vigorously admixed with 490 parts of iso 2 using a lab
stirrer and then
poured into the cube mold. The rigid foam rose in the mold and was left
therein until fully
cured.
CA 02865728 2014-08-27
14
Comparator to example 2
The components as per table 1 in the Comp. 2 column with the exception of iso
1 were
weighed in together pro rata for an overall batch size of 400 parts and then
homogenized.
This mixture was vigorously admixed with 680 parts of iso 1 using a lab
stirrer and then
poured into the cube mold. The rigid foam rose in the mold and was left
therein until fully
cured.
Properties of products obtained
Table 2
Ex. 1 Ex. 2 Comp.1
density 44 34 48
compressive strength 0.25 0.25 0.12
relative deformation 5.1 8.7 10
density: core density [kg/m3]
compressive strength in N/mm2 to DIN 53421 / DIN EN ISO 604
relative deformation [%] to DIN 53421 / DIN EN ISO 604
Table 2 reveals that the inventive examples featuring rigid foams in the same
density range
have a higher compressive strength. The relative deformation values are
likewise better for
the inventive foams.
Table 3
Ex. 1 Ex. 2 Comp. 2
density 44 34 39
thermal conductivity 23.7 23.2 32
CCC 91 86 92
density: core density [kg/m3]
thermal cond.: thermal conductivity [mW/m*K] Hesto A50 (mean temp. 23 C)
CCC: closed-cell content [%] to DIN ISO 4590
CA 02865728 2014-08-27
Table 3 shows that the inventive rigid foams have a lower thermal conductivity
than rigid
foams in the same density range and with comparable closed-cell content.
5 Table 4
Ex. 1 Ex. 2 Ex. 3 Comp. 1
density 44 34 46 48
CCC 91 86 80 92
TGA 265 285 270 214
density: core density [kg/m3]
CCC: closed-cell content [%] to DIN ISO 4590
10 TGA: thermogravimetric analysis [ C] to DIN EN ISO 11358, evaluated on
absolute value
basis at 95% of starting sample mass
The inventive foams prove thermally more stable in thermogravimetric analysis
than rigid
foams of comparable density and closed-cell content.
