Note: Descriptions are shown in the official language in which they were submitted.
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Washable viscoelastic flexible polyurethane foams
Description
The present invention relates to a process for producing viscoelastic flexible
polyurethane foams
having an air flow value of at least 1 dm3/s, which comprises (a)
polyisocyanate being mixed with
(b) polymeric compounds having isocyanate-reactive groups, (c) optionally
chain-extending and/or
crosslinking agents, (d) optionally compounds having one isocyanate-reactive
group with a hydroxyl
number of 100 to 500 mg KOH/g, (e) catalyst, (f) blowing agent, and also
optionally (g) addition
agents to form a reaction mixture and convert it into flexible polyurethane
foam, wherein the
polymeric compounds having isocyanate-reactive groups (b) comprise (b1) 10 to
40 wt% of at least
one polyalkylene oxide having a hydroxyl number of 90 to 300 mg KOH/g, based
on a 3 to 6-
functional starter molecule and a propylene oxide fraction, based on the
alkylene oxide content, of
80 to 100 wt%, (b2) 5 to 20 wt% of at least one polyalkylene oxide having a
hydroxyl number of 10
to 60 mg KOH/g, based on a 2 to 4-functional starter molecule and a propylene
oxide fraction,
based on the alkylene oxide content, of 80 to 100 wt%, (b3) 10 to 50 wt% of at
least one
polyalkylene oxide having a hydroxyl number of 10 to 55 mg KOH/g, based on a 2
to 4-functional
starter molecule and an ethylene oxide fraction, based on the alkylene oxide
content, of 70 to
100 wt%, and (b4) 0 to 20 wt% of at least one polyalkylene oxide having a
hydroxyl number of 50 to
200 mg KOH/g, based on a 2-functional starter molecule and an ethylene oxide
fraction, based on
the alkylene oxide content, of 80 to 100 wt%, and wherein the fraction of
compounds b1) to b4),
based on the total weight of polymeric compounds having isocyanate-reactive
groups (b), is at least
80 wt%. The present invention further relates to a viscoelastic polyurethane
foam having an air flow
value of at least 1 dm3/s, which is obtainable by such a process, and to the
use of such a
polyurethane foam for mattresses and cushions.
Viscoelastic flexible polyurethane foams have attained ever greater importance
in recent years.
They are used in particular for producing upholstery, pillows, mattresses or
for vibration damping,
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for example in carpet backfoaming or in-place cavity foaming. Viscoelastic
foams are notable for
their slow recovery after compression.
Currently there are two different groups of viscoelastic foams, which differ
in cell structure and the
mechanism of viscoelasticity.
So-called pneumatically (physically) viscoelastic foams (pVEs) are closed-cell
flexible PU foams
with perforate cellular membrane, the air flow value of which is very low. On
compression, the air is
squeezed out of the cells of the foam. On decompression, the air flow value
limits the rate at which
the foam can relax back into its original shape. Recovery time is therefore
dependent on the degree
of perforation/open-cell content of the flexible PU foam, inter alia. The
higher the closed-cell content
of the flexible PU foam, the slower the recovery.
Examples of polyurethane foams with pneumatic viscoelasticity have already
been extensively
described in the literature and patent documents. As far back as 1989,
DE3942330 described a
process for producing flexible polyurethane foams having viscoelastic,
structureborne sound-
damping properties and the polyoxyalkylene-polyol mixtures used therefor.
Viscoelastic properties can be achieved in different ways. US6391935, EP
908478 and
WO 2005/003206 respectively describe the use of monools; of cyclic and
heterocyclic components;
and of certain chain extenders.
Where the patent documents do not differ is that the dominating proportion of
polyetherol mixtures
is constructed from very hydrophilic building blocks, especially polyethylene
oxide units.
Furthermore, the cells of the polyurethane foam are overwhelmingly closed-cell
with perforation,
and so the viscoelastic effect is predominantly due to the low air flow value
of the cellular
membranes.
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The pneumatically viscoelastic polyurethane foams described in the references
cited have the
disadvantage that the high closed-cell content greatly limits air interchange.
Without air
interchange, there can be no removal of heat for example from the human body,
leading to
increased sweating, nor of moist air for example from human perspiration or
from washing.
.. Furthermore, the high proportion of hydrophilic polyols means that the foam
is very hydrophilic,
tends to imbibe water and is only slow to release it again, and therefore
tends to swell up. A further
disadvantage of these viscoelastic polyurethane foams is their low mechanical
strength, as
reflected more particularly by low values of tensile strength in particular,
which are even worse in
the wet state.
Furthermore, the high hydrophilicity of the foams leads to high water
imbibition, for example in the
form of sweat or on attempting to launder the foam. The water can pass into
perforate cells as well
as into the hydrophilic matrix of the foam, causing substantial swelling up of
the foam. These foams
cannot be dried nondestructively owing to their low air flow value.
An attempt to dry these wet foams will frequently cause the cellular membranes
to burst or rupture,
which leads to the viscoelastic behavior being lost and the foam's scaffolding
being destroyed.
So-called structurally or chemically viscoelastic flexible polyurethane foams
(cVEs) are notable for
.. their glass transition temperature being in the vicinity of room
temperature. Such cVE foams can be
open-cell and yet viscoelastic.
Recovery time here is controlled by using a specific polyether polyol
composition as well as a more
or less freely choosable isocyanate component. An open-cell foam is of
advantage for the special
.. comfort expected of mattresses and pillows in particular, since it enables
air interchange and
provides an improved microclimate.
Examples of open-cell structurally viscoelastic flexible foams (cVEs) have
already been extensively
described in patent documents and the literature. US7022746 describes an open-
cell viscoelastic
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foam having an ASTM3574G-95 air flow value of up to 3.9 dm3/s coupled with a
maximum value of
the loss modulus tan delta at 10-12 C. This reference, which includes improved
mechanical
properties amongst its objects, further describes viscoelastic polyurethane
foams having a tensile
strength of 37 to 60 kPa. Two main polyols are used in this reference, each
with a weight fraction of
30-70 wt%, one polyol consisting of ethylene oxide building blocks to an
extent of 70-100 wt% while
the second polyol consists of propylene oxide building blocks to an extent of
70-100%. As a result,
this foam is minimally more hydrophobic than the foams obtained with
exclusively ethylene oxide-
based polyols, but especially the swellability in water as well as the tensile
strength of these foams
is in need of further improvement.
DE102997061883 describes a slabstock foam system which is said to be open-
cell, although it first
has to be flexed after manufacture. The polyol used is essentially a polyol
constructed nearly half
and half of PO and E0 building blocks.
The foam of DE 102997061883 is closed-cell in the as-produced state, it is
only after mechanical
flexing that the cellular membranes will burst open to some extent. The patent
document does not
recite any measured DIN air flow value, but does state that an in-house
measurement found an air
resistance of 350 mm water column, suggesting a very low air flow. Moreover,
foams according to
DE102997061883 display a very low tensile strength of 36 kPa.
These disadvantages are said to be compensated by using specific polyols.
W02008002435
describes the use of polyetherols initiated on bisphenol A, which should give
increased tensile
strength, yet the foams obtained display only tensile strengths of up to 65
kPa.
EP1960452 describes recipes comprising a distinctly reduced fraction of
hydrophilic polyol. A
person skilled in the art would expect this to result in a distinctly lower
water imbibition and lower
swelling of the foams. The flexible foams mentioned in the patent document do
indeed display
reduced swelling in water of just 4-7%. It is likewise stated that the
hydrophilic flexible foams
mentioned in the prior art are unsuitable owing to their swellability of about
40% in moist media.
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The foams recited in the patent document again display only low tensile
strengths of up to 63 kPa
and therefore are not fit for high mechanical loads despite the low water
imbibition.
DE10352100 concerns the swelling behavior of viscoelastic foams in water and
describes
5 pneumatic viscoelastic foams having improved hydrolysis and aging
properties. Also described are
foams where there are viscoelastic properties over a wide temperature range.
This is achieved
through the use of 10-60 wt% of acrylate polyols. Swellability in water is 4%
and the tan delta curve
promises viscoelastic behavior over a wide temperature range. Tensile
strengths are not reported.
Disadvantages with using acrylate polyols are the high price and especially
the high emissions of
acrylates, which become unpleasantly noticeable by odor. These foams further
also display a high
closed-cell content with the recited disadvantages.
W02007/144272 describes hydrophobic viscoelastic open-cell slabstock foams
comprising TDI as
isocyanate component. Polyol components comprising a high proportion of
polymeric polyetherols
(graft polyethers) are used. Disadvantages are the low tensile strength,
reported as 40-60 kPa, and
the low air flow value of just 30-60 L/min.
The use of chemically modified or unmodified polyetherols or monools based on
renewable raw
materials is currently a frequent topic in newly filed applications. These so-
called bio-polyols find
use in the sector of viscoelastic open-cell foams in EP1981926, W02009/106240
but also
W02009/032894. Low tensile strength is again a disadvantage in that 70 kPa is
the maximum
reported in any of the cited patent documents.
The present invention has for its object to provide a viscoelastic flexible
polyurethane foam having
an outstanding air flow value and a high tensile strength by using essentially
customary polyols.
The present invention further has for its object to provide a polyurethane
foam which can be
washed nondestructively, especially in a commercial washing machine using a
customary washing
powder at temperatures up to 60 C, and subsequently dried without the
viscoelastic properties
being lost by the washing and drying.
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We have found that this object is achieved, surprisingly, by a process for
producing viscoelastic
flexible polyurethane foams having an air flow value of at least 1 dm3/s,
which comprises
(a) polyisocyanate being mixed with (b) polymeric compounds having isocyanate-
reactive groups,
(c) optionally chain-extending and/or crosslinking agents, (d) optionally
compounds having one
isocyanate-reactive group with a hydroxyl number of 100 to 500 mg KOH/g, (e)
catalyst, (f) blowing
agent, and also optionally (g) addition agents to form a reaction mixture and
convert it into flexible
polyurethane foam, wherein the polymeric compounds having isocyanate-reactive
groups (b)
comprise (b1) 10 to 40 wt% of at least one polyalkylene oxide having a
hydroxyl number of 90 to
300 mg KOH/g, based on a 3 to 6-functional starter molecule and a propylene
oxide fraction, based
on the alkylene oxide content, of 80 to 100 wt%, (b2) 5 to 20 wt% of at least
one polyalkylene oxide
having a hydroxyl number of 10 to 60 mg KOH/g, based on a 2 to 4-functional
starter molecule and
a propylene oxide fraction, based on the alkylene oxide content, of 80 to 100
wt%, (b3) 10 to 50
wt% of at least one polyalkylene oxide having a hydroxyl number of 10 to 55 mg
KOH/g, based on
a 2 to 4-functional starter molecule and an ethylene oxide fraction, based on
the alkylene oxide
content, of 70 to 100 wt%, and (b4) 0 to 20 wt% of at least one polyalkylene
oxide having a
hydroxyl number of 50 to 200 mg KOH/g, based on a 2-functional starter
molecule and an ethylene
oxide fraction, based on the alkylene oxide content, of 80 to 100 wt%, and
wherein the fraction of
compounds b1) to b4), based on the total weight of polymeric compounds having
isocyanate-
reactive groups (b), is at least 80 wt%.
The open-cell viscoelastic flexible polyurethane foams of the present
invention are characterized by
an absolute maximum value for the loss modulus tan delta in the temperature
range from -10 to
40 C, preferably in the range from 0 to 35 C, more preferably in the range
from 10 to 35 C and
especially in the range from 15 to 30 C. The absolute maximum value of the
loss modulus tan delta
corresponds to the ASTM D 4065-99 glass transition temperature. The
viscoelastic polyurethane
foams of the present invention further have a DIN EN ISO 8307 resilience of
below 20% and also a
high damping behavior, which is reflected by a tan delta value at 20 C of at
least 0.2, preferably at
least 0.4 and more preferably at least 0.5. The tan delta is determined using
dynamic mechanical
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analysis (DMA) at a frequency of 1 Hz and a temperature range of -80 to +200 C
at a deformation
of 0.3% in line with DIN EN ISO 6721-1, DIN EN ISO 6721-2, DIN EN ISO 6721-7.
The temperature
program is run in 5 C steps.
The viscoelastic polyurethane foams of the present invention also display a
DIN EN ISO 8307 air
flow value of at least 1.0 dm3/s, preferably at least 1.2 dm3/s, more
preferably at least 1.4 dm3/s and
especially at least 1.5 dm3/s. The density of flexible polyurethane foams
according to the present
invention is less than 150 WI, preferably in the range from 20 to 100 g/I,
more preferably in the
range from 30 to 80 g/I and especially in the range from 40 to 60 g/I.
Useful polyisocyanates a) include in principle any known compounds having two
or more
isocyanate groups in the molecule, alone or in combination. Diisocyanates are
preferable. The
process of the present invention preferably utilizes diphenylmethane
diisocyanate (MDI), tolylene
diisocyanate (TDI), or MDI-TDI mixtures.
The diphenylmethane diisocyanate used can be monomeric diphenyl diisocyanate
selected from
the group consisting of 2,2'-diphenylmethane diisocyanate, 2,4'-
diphenylmethane diisocyanate or
4,4'-diphenylmethane diisocyanate, or mixtures of two or all three isomers,
and also mixtures of
one or more monomeric diphenylmethane diisocyanates with higher-nuclear
homologs of
diphenylmethane diisocyanate. The viscosity of diphenylmethane diisocyanate
(al) at 20 C is
preferably less than 200 mPas, more preferably less than 150 mPas and more
preferably less than
100 mPas. It is particularly preferable for the proportion of 2,2'-
diphenylmethane diisocyanate to be
less than 5 wt%, based on the total weight of polyisocyanates (a).
When TDI is used, it will usually be mixtures of the 2,4- and the 2,6-isomer
which are used.
Commercially available mixtures with 80% 2,4 and 60% 2,6 TDI and 35% 2,4 and
35% 2,6 TDI are
particularly preferable.
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In place of pure isocyanates or blended with these, so-called modified
isocyanates are frequently
used. These modified isocyanates may be formed for example through
incorporation of groups into
the polyisocyanates. Examples of such groups are urethane, allophanate,
carbodiimide,
uretoneimine, isocyanurate, urea and biuret groups.
Particular preference is given to polyisocyanates modified with urethane
groups, these
polyisocyanates being typically prepared by reacting the isocyanates with a
deficiency of
compounds having two or more isocyanate-reactive hydrogen atoms. Compounds
formed
therefrom are frequently referred to as NCO prepolymers. The compounds used
and having two or
more isocyanate-reactive hydrogen atoms are preferably polymeric compounds
having isocyanate-
reactive groups (b) and/or chain-extending and/or crosslinking agents (c).
Particular preference is likewise given to carbodiimide- or uretoneimine-
containing polyisocyanates,
which are formed by specific catalyzed reaction of isocyanates with
themselves. Mixtures of TDI
and MDI can also be used.
Polymeric compounds having isocyanate-reactive groups (b) have a number
average molecular
weight of at least 450 g/mol and more preferably in the range from 460 to 12
000 g/mol and have
two or more isocyanate-reactive hydrogen atoms per molecule. Polymeric
compounds having
isocyanate-reactive groups (b) preferably include polyester alcohols and/or
polyether alcohols
having a functionality of 2 to 8, especially of 2 to 6 and preferably 2 to 4
and an average equivalent
molecular weight in the range from 400 to 3000 g/mol and preferably in the
range from 1000 to
2500 g/mol. Polyether alcohols are used in particular.
Polyether alcohols are obtainable by known methods, usually via catalytic
addition of alkylene
oxides, especially ethylene oxide and/or propylene oxide, onto H-functional
starter substances, or
via condensation of tetrahydrofuran. When alkylene oxides are used, the
products are also known
as polyalkylene oxide polyols. Useful H-functional starter substances include
especially
polyfunctional alcohols and/or amines. Preference is given to using water,
dihydric alcohols, for
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example ethylene glycol, propylene glycol, or butane diols, trihydric
alcohols, for example glycerol
or trimethylolpropane, and also more highly hydric alcohols, such as
pentaerythritol, sugar alcohols,
for example sucrose, glucose or sorbitol. Preferable amines are aliphatic
amines having up to 10
carbon atoms, for example ethylenediamine, diethylenetriamine,
propylenediamine, and also amino
alcohols, such as ethanolamine or diethanolamine. The alkylene oxides used are
preferably
ethylene oxide and/or propylene oxide, while polyether alcohols used for
preparing flexible
polyurethane foams frequently have an ethylene oxide block added at the chain
end. Useful
catalysts for the addition reaction of alkylene oxides include especially
basic compounds in that
potassium hydroxide is industrially the most important one. When the level of
unsaturated
constituents in the polyether alcohols is to be low, di- or multi metal
cyanide compounds, so-called
DMC catalysts, can also be used as catalysts. Viscoelastic flexible
polyurethane foams are
produced using especially two- and/or three-functional polyalkylene oxide
polyols.
Useful compounds having two or more active hydrogen atoms further include
polyester polyols
obtainable for example from organic dicarboxylic acids having 2 to 12 carbon
atoms, preferably
aliphatic dicarboxylic acids having 8 to 12 carbon atoms, and polyhydric
alcohols, preferably diols,
having 2 to 12 carbon atoms and preferably 2 to 6 carbon atoms. Useful
dicarboxylic acids include
for example succinic acid, glutaric acid, adipic acid, suberic acid, azelaic
acid, sebacic acid,
decanedicarboxylic acid, maleic acid, fumaric acid, phthalic acid, isophthalic
acid, terephthalic acid
and the isomeric naphthalene dicarboxylic acids. Use of adipic acid is
preferable. The dicarboxylic
acids can be used not only individually but also mixed with one another.
Instead of the free
dicarboxylic acids it is also possible to use the corresponding dicarboxylic
acid derivatives, for
example dicarboxylic esters of alcohols having 1 to 4 carbon atoms or
dicarboxylic anhydrides.
Examples of alcohols having two or more hydroxyl groups and especially diols
are: ethanediol,
diethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, 1,4-
butanediol, 1,5-
pentanediol, 1,6-hexanediol, 1,10-decanediol, glycerol and trimethylolpropane.
Preference is given
to using ethanediol, diethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-
hexanediol or mixtures
of two or more thereof, especially mixtures of 1,4-butanediol, 1,5-pentanediol
and 1,6-hexanediol. It
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is further possible to use polyester polyols formed from lactones, e.g., E-
caprolactone, or hydroxy
carboxylic acids, e.g., 0)-hydroxycaproic acid and hydroxybenzoic acids. The
use of dipropylene
glycol is preferred.
5 The polymeric compounds having isocyanate-reactive groups (b) comprise
(b1) 10 to 40 wt% of at
least one polyalkylene oxide having a hydroxyl number of 90 to 300 mg KOH/g,
based on a 3 to 6-
functional starter molecule and a propylene oxide fraction, based on the
alkylene oxide content, of
80 to 100 wt%, (b2) 5 to 20 wt% of at least one polyalkylene oxide having a
hydroxyl number of 10
to 60 mg KOH/g, based on a 2 to 4-functional starter molecule and a propylene
oxide fraction,
10 based on the alkylene oxide content, of 80 to 100 wt%, (b3) 10 to 50 wt%
of at least one
polyalkylene oxide having a hydroxyl number of 10 to 55 mg KOH/g, based on a 2
to 4-functional
starter molecule and an ethylene oxide fraction, based on the alkylene oxide
content, of 70 to
100 wt%, and (b4) 0 to 20 wt%, preferably 1-20 wt% of at least one
polyalkylene oxide having a
hydroxyl number of 50 to 200 mg KOH/g, preferably 56-200 mg KOH/g, based on a
2-functional
starter molecule and an ethylene oxide fraction, based on the alkylene oxide
content, of 80 to
100 wt%, all based on the total weight of polymeric compounds having
isocyanate-reactive groups
(b).
It is preferable to use exclusively polyether polyols as polymeric compounds
having isocyanate-
reactive groups (b). It is essential here for the purposes of the present
invention that the polymeric
compounds having isocyanate-reactive groups (b) comprise the polyetherols (b1)
to (b4) at not less
than 80 wt%, preferably not less than 85 wt%, more preferably not less than 90
wt% and especially
not less than 95 wt%, all based on the total weight of the polymer compounds
having isocyanate-
reactive groups (b). In an especially preferred embodiment of the present
invention, the polymeric
compounds having isocyanate-reactive groups (b), in addition to the
polyetherols (b1) to (b4) do not
contain any further polymeric compounds having isocyanate-reactive groups.
It is particularly preferable for the polyetherols of the present invention,
aside from the starter, to
include essentially exclusively ethylene oxide and propylene oxide units. Here
"essentially" is to be
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understood as meaning that small amounts of other alkylene oxide units are not
disadvantageous.
The fraction of alkylene oxide units other than ethylene oxide or propylene
oxide units is preferably
less than 5 wt%, more preferably less than 1 wt% and especially 0 wt%, all
based on the total
weight of alkylene oxide units.
The chain-extending agents and/or crosslinking agents (c) used are substances
having a molecular
weight of below 400 g/mol and preferably in the range from 60 to 350 g/mol,
chain extenders
having 2 isocyanate-reactive hydrogen atoms and crosslinkers having 3 or more
isocyanate-
reactive hydrogen atoms. These can be used individually or in the form of
mixtures. Preference is
given to using diols and/or triols having molecular weights less than 400,
more preferably in the
range from 60 to 300 and especially in the range from 60 to 150. Possibilities
are for example,
aliphatic, cycloaliphatic and/or aromatic diols, and also diols having
aromatic structures, with 2 to
14 and preferably 2 to 10 carbon atoms, such as ethylene glycol, 1,3-
propanediol, 1,10-decanediol,
o-dihydroxycyclohexane, m-dihydroxycyclohexane, p-dihydroxycyclohexane,
diethylene glycol,
dipropylene glycol and preferably 1,4-butanediol, 1,6-hexanediol and bis(2-
hydroxyethyl)hydroquinone, triols, such as 1,2,4-trihydroxycyclohexane, 1,3,5-
trihydroxycyclohexane, glycerol and trimethylolpropane, and low molecular
weight hydroxyl-
containing polyalkylene oxides based on ethylene oxide and/or 1,2-propylene
oxide and the
aforementioned diols and/or triols as starter molecules. Particular preference
for use as chain
extenders (d) is given to monoethylene glycol, 1,4-butanediol and/or glycerol.
When chain-extending agents, crosslinking agents or mixtures thereof are used,
the amounts in
which they are used are advantageously in the range from 0.1 to 20 wt%,
preferably in the range
from 0.5 to 10 wt% and especially in the range from 0.8 to 5 wt%, based on the
weight of
components (b) and (c).
In addition to polymeric compounds having isocyanate-reactive groups, it is
optionally also possible
to use one or more compounds having just one isocyanate-reactive group (d).
These compounds
are for example monoamines, monothiols and/or monoalcohols, for example based
on polyethers,
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12
polyesters or polyether-polyesters. Monoalcohols used for example are more
preferably polyether
monools obtained on the basis of monofunctional starter molecules, for example
ethylene glycol
monomethyl ether. These are obtainable similarly to the polyetherols described
above via
polymerization of alkylene oxide onto the starter molecule. Polyether monools
preferably have a
high proportion of primary OH groups. It is particularly preferable to prepare
polyether monools
using ethylene oxide as sole alkylene oxide. Preferable monools further
include compounds having
an aromatic group. The number average molecular weight of compounds having one
isocyanate-
reactive group is preferably in the range from 50 to 1000 g/mol, more
preferably in the range from
80 to 300 g/mol and especially in the range from 100 to 200 g/mol. When
compounds having one
isocyanate-reactive group (d) are used, they are preferably used in a
proportion of 0.1 to 5 wt% and
more preferably 0.5 to 4.5 wt%, based on the total weight of polymeric
compounds having
isocyanate-reactive groups (b) and compounds having just one isocyanate-
reactive group (d).
Useful catalysts (e) for preparing the viscoelastic polyurethane foams are
preferably compounds
which greatly speed the reaction of the hydroxyl-containing compounds of
components (b), (c) and
optionally (d) with the polyisocyanates (a) and/or the reaction of isocyanates
with water. Examples
are amidines, such as 2,3-dimethy1-3,4,5,6-tetrahydropyrimidine, tertiary
amines, such as
triethylamine, tributylamine, dimethylbenzylamine, N-methylmorpholine, N-
ethylmorpholine, N-
cyclohexylmorpholine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-
tetramethylbutanediamine,
N,N,N',N'-tetramethylhexanediamine, pentamethyldiethylenetriamine,
tetramethyldiaminoethyl
ether, bis(dimethylaminopropyl)urea, dimethylpiperazine, 1,2-
dimethylimidazole, 1-azabicyclo-
(3,3,0)-octane and preferably 1,4-diazabicyclo-(2,2,2)-octane and alkanolamine
compounds, such
as triethanolamine, triisopropanolamine, N-methyldiethanolamine, N-
ethyldiethanolamine and
dimethylethanolamine. Similarly suitable are organic metal compounds,
preferably organic tin
compounds, such as tin(II) salts of organic carboxylic acids, e.g., tin(II)
acetate, tin(II) octoate, tin(II)
ethylhexanoate and tin(II) laurate, and the dialkyltin(IV) salts of organic
carboxylic acids, for
example dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate and
dioctyltin diacetate, and
also bismuth carboxylates, such as bismuth(111) neodecanoate, bismuth 2-
ethylhexanoate and
bismuth octanoate, or mixtures thereof. The organic metal compounds can be
used alone or
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13
preferably in combination with strong basic amines. When component (b) is an
ester, it is preferable
to use exclusively amine catalysts.
Preference is given to using from 0.001 to 5 wt% and especially from 0.05 to 2
wt% of catalyst or
catalyst combination, based on the weight of component (b).
Polyurethane foams are further produced in the presence of one or more blowing
agents (f). By
way of blowing agents (f) it is possible to use chemically acting blowing
agent and/or physically
acting compounds. Chemical blowing agents are compounds which react with
isocyanate to form
gaseous products, for example water or formic acid. Physical blowing agents
are compounds that
have been dissolved or emulsified in the reactants of polyurethane synthesis
and vaporize under
the conditions of polyurethane formation. Examples are hydrocarbons,
halogenated hydrocarbons
and other compounds, for example perfluorinated alkanes, such as
perfluorohexane,
chlorofluorocarbons, and ethers, esters, ketones and/or acetals, for example
(cyclo)aliphatic
hydrocarbons having 4 to 8 carbon atoms, hydrofluorocarbons, such as Solkanes
365 mfc, or
gases, such as carbon dioxide. In one preferable embodiment, the blowing agent
used is a mixture
of these blowing agents, comprising water and more preferably exclusively
water.
The level of physical blowing agents (f), if present, in a preferable
embodiment is in the range
between 1 and 20 wt% and especially 5 and 20 wt%, the amount of water is
preferably in the range
between 0.5 and 8 wt% and more preferably between 0.8 and 6 wt% and especially
between 1 and
5 wt%, all based on the total weight of components (a) to (g).
Useful auxiliaries and/or addition agents (g) include for example surface-
active substances, foam
stabilizers, cell regulators, external and internal release agents, fillers,
pigments, dyes, flame
retardants, antistats, hydrolysis control agents and also fungistats and
bacteriostats.
CA 02857609 2014-05-30
14
Further particulars about the starting materials used appear for example in
Kunststoffhandbuch,
volume 7, Polyurethanes, edited by Gunter Oertel, Carl-Hanser-Verlag, Munich,
3rd edition 1993,
chapter 5, Flexible polyurethane foams.
having isocyanate-reactive groups (b), the optionally used chain-extending
and/or crosslinking
agents (c), the optionally used compounds having just one isocyanate-reactive
group with a
hydroxyl number of 100 to 500 mg KOH/g (d), the catalysts (e), the blowing
agents (f), and also the
optionally used auxiliaries and/or addition agents (g) are typically mixed to
form a so-called polyol
To produce the viscoelastic polyurethane foams of the present invention, the
polyisocyanate
prepolymers are reacted with the polymeric compounds having isocyanate-
reactive groups in the
presence of the recited blowing agents, catalysts and auxiliary and/or
addition agents (polyol
The polyurethane foams of the present invention are preferably produced by the
one-shot process,
for example using the high-pressure or low-pressure technique. The foams are
obtainable in open
or closed metallic molds or via the continuous application of the reaction
mixture to belt lines or in
troughs to produce foam blocks.
It is particularly advantageous to proceed via the so-called two-component
process wherein, as
mentioned above, a polyol component is produced and foamed with polyisocyanate
a). The
components are preferably mixed at a temperature in the range between 15 and
120 C and
CA 02857609 2014-05-30
=
preferably 20 to 80 C and introduced into the mold or onto the belt line. The
temperature in the
mold is usually in the range between 15 and 120 C and preferably between 30
and 80 C.
The density of the viscoelastic flexible polyurethane foam of the present
invention is less than
5 150 g/I, preferably in the range from 20 to 100 WI, more preferably in
the range from 30 to 80 g/I
and especially in the range from 40 to 60 g/I.
Flexible polyurethane foams of the present invention are preferably used for
insulating and
damping elements, especially in vehicle building, for example as carpetback
coating, for
10 upholstered, sitting or lying furniture, for mattresses or cushions, for
example in the orthopedic
and/or medical sector, or for shoe inlay soles. A further field of use is that
of automotive safety
parts, supporting areas, armrests and similar parts in the furniture sector
and in automotive
engineering. Viscoelastic components are further used for acoustical
insulation and absorption. It is
particularly preferably to use the flexible polyurethane foams of the present
invention for mattresses
15 and cushions.
The viscoelastic polyurethane foams of the present invention are characterized
by excellent
mechanical properties, especially outstanding values for tensile strength and
elongation at break.
The viscoelastic polyurethane foams of the present invention at the same time
have outstanding air
flow values of above 1 dm3/s. The viscoelastic polyurethane foams of the
present invention are
washable and can be washed and dried in commercial domestic washing machines
using
customary washing powders at temperatures up to 60 C without destruction and
without significant
impairment, especially of viscoelastic properties and mechanical properties,
such as tensile
strength and elongation at break.
The examples which follow illustrate the invention.
Examples 1 and 2
CA 02857609 2014-05-30
16
The polyols, catalysts and addition agents reported in table 1 were mixed
together to form a polyol
component, the reported amounts being parts by weight. The polyol component
was mixed with an
MDI isocyanate mixture (diphenylmethane diisocyanate mixture) at the reported
index in a Puromat
equipped with MKA 10-2/16 mixing head at about 150 bar, and the mixture was
introduced into a
closeable metal mold having the dimensions 40x40x10 cm, where it cured to the
flexible foam in
the closed mold. The metal mold has a temperature of 60 C, the demolding time
was 6 minutes.
The mechanical properties of the foams are reported in the tables.
polyol 1 polyether alcohol based on trimethylolpropane and propylene
oxide, hydroxyl
number 160 mg KOH/g
polyol 2 polyether alcohol based on glycerol, propylene oxide and
ethylene oxide, hydroxyl
number 170 mg KOH/g and a proportion of propylene oxide, based on the total
weight of ethylene oxide and propylene oxide, of about 95 wt%
polyol 3 polyether alcohol based on glycerol and propylene oxide,
hydroxyl number
42 mg KOH/g
polyol 4 polyether alcohol based on glycerol, ethylene oxide and
propylene oxide, hydroxyl
number 42 mg KOH/g and a proportion of ethylene oxide, based on the total
weight
of ethylene oxide and propylene oxide, of about 74 wt%
polyol 5 polyether alcohol based on ethylene glycol as starter and
ethylene oxide, hydroxyl
number 188 mg KOH/g
monool monool, hydroxyl number 406 mg KOH/g
crosslinker glycerol, hydroxyl number 1825 mg KOH/g
stabilizer 1 DabcoO DC 198 Air Products
catalyst 2 JeffcatO ZF10 ¨ incorporable amine catalyst from Huntsman
catalyst 3 VP9357 ¨ incorporable amine catalyst from BASF SE
catalyst 4 Dabco NE 1070 ¨ incorporable amine catalyst from Air Products
Is 1 MDI mixture from BASF SE, NCO content 32.8%, comprising 2,4'-
MDI, 4,4'-MDI and
higher-nuclear homologs of MDI
detergent: commercially available Persil laundry detergent from Henkel
CA 02857609 2014-05-30
17
Table 1
Example 1 2
polyol 1 34.3
polyol 2 28
polyol 3 15 15.3
polyol 4 40 31
polyol 5 20
monool 4
crosslinker 1
stabilizer 1 1.0 1.5
catalyst 2 0.2 0.2
catalyst 3 2 1
catalyst 4 1
water 1.5 3.0
!so 1 100 100
index 100 80
CA 02857609 2014-05-30
,
18
Table 2
Example 1 2
tan delta (max) at C 20 25
tan delta at 20 C 0.68 0.61
overall density kg/m3 78 48
compressive strength 40% 3.3 1.0
[kPa]
tensile strength [kPa] 190 136
elongation at break [%] 173 201
CS (22h/70 C/50%) [%] 2.3 4.6
CS (22h/70 C/90%) [%] 3.2 7.7
hysteresis [%] 41 57
resilience [%] 6 11
air flow value [dm3/s] 1.7 2.0
CA 02857609 2014-05-30
=
19
Table 3
Example 1 lb 1 c ld
washed at C - 40, once 60, once
washed at C + Persil - 60,
once
overall density kg/m3 78 76 78 78
compressive strength 40% 3.3 3.0 3.4 3.5
[kPa]
tensile strength [kPa] 190 177 171 192
elongation at break [%] 173 181 186 188
CS (22h/70 C/50%) [%] 2.3 2.2 1.9 1.9
CS (22h/70 C/90%) [%] 3.2 3.3 7.6 8.5
hysteresis [%] 41 42 46 45
resilience [%] 6 5 4 6
air flow value [dm3/s] 1.7 1.7 1.4 1.5
= CA 02857609 2014-05-30
Table 4
Example 2 2b 2c 2d 2e
washed at C - 40, once 60, once
washed at C + Persil - 60, once 40, five
x
overall density kg/m3 48 45 44 44 45
compressive strength 40% 1.0 1.2 1.3 1.4 1.5
[kPa]
tensile strength [kPa] 136 160 170 163 146
elongation at break [%] 201 187 187 186 174
CS (22h/70 C/50%) [%] 4.6 4.8 4.7 4.9 5.4
CS (22h/70 C/90%) [%] 7.7 7.0 6.4 9.3 5.1
hysteresis [%1 57 62 63 65 66
resilience [%] 11 12 12 12 12
air flow value [dm3/s] 2.0 2.4 2.3 2.2 2.3
Overall density was determined according to DIN EN ISO 845, compressive
strength and
hysteresis according to DIN EN ISO 3386, tensile strength according to DIN EN
ISO 1798,
5 elongation at break according to DIN EN ISO 1798, compression set (CS)
according to
DIN EN ISO 1856, resilience according to DIN EN ISO 8307 and air flow value
according to
DIN EN ISO 7231.
In a washing test, a pillow was weighed and measured out beforehand and washed
inside a pillow
10 casing in a commercially available washing machine (Bomann 9110) in the
heavy duty cycle at
40 C or 60 C.
Depending on the test, Persil from Henkel was included in the wash (1 cup).
The program
includes a spin at 1000 rpm. The still residually moist pillow was then
weighed and measured and
15 thereafter dried either at room temperature or at 60 C in a circulating
air oven to constant weight
and then tested. In test 2e, the pillow was washed altogether five times and
dried again.
CA 02857609 2014-05-30
21
The pillows as dried are visually impeccable, have an intact skin structure
and no cracks or visible
defects.
Table 5: Swelling behavior and water imbibition using test 2d as an example:
Before washing After spinning After drying
length 100% 108% 99%
width 100% 109% 100%
height 100% 109% 98%
weight 100% 165% 97%
visual assessment impeccable impeccable impeccable
The weight increase of 65% shows that the foam is hydrophilic. Nonetheless, it
only swells by about
9% and is readily dryable. After drying the foam has the same geometry and the
same mechanical
and especially viscoelastic properties.
