Note: Descriptions are shown in the official language in which they were submitted.
2~2,~
Mo-3464
LeA 27,266
A PROCESS FOR THE PREPARATION OF MOLDED POLYURETHANE
FOAMS AND THE MOLDED FOAMS OBTAINED BY THIS PROCESS
BACKGROUND OF THE INVENTION
This invention relates to a new process for the
preparation of molded polyurethane foams having a compact skin,
in which salts of (i) organic carboxylic acids and (ii)
nitrogen bases containing at least one NH bond are used as
blowing agents, and to the moldings obtained by the process.
~he preparation of molded polyurethane foams having a
o compact skin by foam molding is known. For example, German
Auslegeschrift 1,196,864. It is carried out by the in-mold
foaming of a reactive and foamable mixture of organic poly-
isocyanates, compounds containing isocyanate-reactive groups,
and the usual auxiliaries and additives. The reacted mixture
iS introduced into the mold in a larger quantity than would be
necessary to fill the interior of the mold by free foaming. By
suitable choice of the starting components, particularly with
respect to molecular weight and functionality, it is possible
to produce both flexible, semi-rigid, and rigid moldings. The
compact outer skin is obtained by introducing a foamable
mixture into the mold in a larger quantity than would be
necessary to fill the interior of the mold by free foaming and
by using blowing agents (such as fluorochlorocarbons), which
condense on the inner walls of the mold under the prevailing
temperature and pressure conditions, so that the blowing
reaction stops at the inner wall of the mold and a compact
outer skin is formed.
In addition to physical blowing agents mentioned
aboYe, water (which forms carbon dioxide by reaction with
isocyanates) is also used as a chemical blowing agent in
industrial polyurethane chemistry. Although free-foamed
35052RH0477
2 ~ 2, ~
polyurethane foams of excellent quality can be prepared with
this chemical blowing agent, it is not possible to prepare
high-quality foam moldings having a compact skin (integral
foams) because carbon dioxide dces not condense on the inner
wall of the mold under the usual conditions. Consequently, the
blowing effect is not stopped at the surface area. The same
basic problem arises with other chemical or physical blowing
agents, such as nitrogen-generating blowing agents such as
azodicarbonamide and azo-bis(isobutyronitrile); blowing agents
which eliminate carbon dioxide such as pyrocarbonic acid esters
and anhydrides (U.S. Patent 4,070,310); and blowing agents such
as air which are dissolved in the reaction components,
particularly the component containing isocyanate-reactive
groups. These other chemical blowing agents are, therefore,
also unsuitable for the preparation of high-quality integral
foams.
It has now surprisingly been found, however, that
high quality molded polyurethane foams having a compact skin
can be prepared from the usual starting materials using salts
of (i) organic carboxylic acids and (ii) nitrogen bases
containing at least one NH bond. The blowing effect of these
materials is also based essentially on the release of carbon
dioxide.
Although, according to German Offenlegungsschrift
3,041,58g, special mixed carboxylic/carbamic anhydrides of the
type formed from carboxylic acids and aliphatic isocyanates are
used as blowing agents for the preparation of polyurethane
foams (particularly integral foams), this process is unsuitable
for industrial application for the following reasons. Mixed
anhydrides are often said to be stable in storage at
temperatures of up to about 60-C even in solution, while, on
the other hand, to develop the blowing effect with release of
carbon dioxide at temperatures as low as about 80C.
Accordingly, the useful temperature range in which carbon
dioxide is eliminated is very narrow. In addition, only
Mo-3464
~Q~ ~7i3
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aliphatic isocyanates can be used for the preparation of mixed
anhydrides. In contrast, the aromatic polyisocyanates
typically used as polyisocyanate component are unsuitable for
the preparation of the special blowing agents. To carry out
s the process, the mixed anhydrides must first be prepared and
isolated in a separate reaction and then carefully mixed with
the polyol mixture. These additional process steps make the
use of these compounds even more expensive and complicated.
Ready-to-use polyols containing the blowing agents mentioned
above cannot be stored and transported safely because the
danger of a dangerous pressure build-up cannot always be
avoided in case of overheating which can occasionally occur
despite careful handling.
According to German Patent Application P 3,840,~17.1
(believed to correspond to U.S. Patent Application Serial No.
07/440,6273, the free acids upon which the salts used acsording
to the present invention are based, as described below, can be
used as blowing agents. The present invention is not concerned
with the use of the corresponding free acids as blowing agents.
SUMMARY OF THE INYENTION
The present invention relates to a process for the
preparation of molded polyurethane foams having a compact skin
and having a density of at least 250 kg/m3 comprising in-mold
fsaming at an isocyanate index of about 75 to about 1500 a
reaction mixture of
(a) a polyisocyanate component comprising at least one
aromatic polyisocyanate,
(b) an isocyanate-reactive component comprising at least one
organic polyhydroxyl compound,
(C) a blowing agent comprising a salt of
(i) an organic carboxylic acid and
(ii) a nitrogen base containing at least one N-H bond,
and, optionally,
(d) other auxiliaries and additives,
Mo-3464
~2 i67~
with the proviso that the blowing agent (c) cannot be a
compound formed in situ in component (b) by interac~on of organic
carboxylic acid with a difunctional or polyfunctional amine.
The present invention also relates to molded
polyurethane foams obta;ned by this process.
DETAILED DES~RIPTION OF THE INVENTION
Polyisocyanate component (a) may be any aromatic
polyisocyanate having an NCO content of at least 20% by weight.
Examples of suitable aromatic polyisocyanates include 2,4-di-
o isocyanatotoluene or technical mixtures thereof with 2,6-di-
isocyanatotoluene or, preferably, known polyisocyanates or
polyisocyanate mixtures of the diphenylmethane series of the
type obtainable by phosgenation of aniline-formaldehyde
condensates and, optionally, purification of the phosgenation
products by distillation. These polyisocyanates or
polyisocyanate mixtures, which are particularly suitable for
the process according to the invention, generally contain from
50 to 100% by weight diisocyanatodiphenylmethane isomers, with
the remainder being essentially higher homologs of thPse
20 diisocyanates. The preferred diisocyanates present in these
mixtures consist essentially of 4,4'-diisocyanatodiphenyl-
methane in admixture with up to 60% by weight, based on the
total quantity of diisocyanates, of 2,4'-diisocyanatodiphenyl-
methane and, optionally, small quantities of 2,2'-diisocyanato-
25 diphenylmethane. Urethane-, carbodiimide-, or allophanate-
modified derivatives of these polyisocyanates may also be used
as the polyisocyanate component (a).
Isocyanate-reactive component (b) comprises at least
one organic compound containing at least two isocyanate-
30 reactive hydroxyl groups and generally consists of mixtures ofseveral such compounds. Isocyanate-reactive component (b) is
Mo-3464
2 ~ ~ f ~ 7 ~
-5-
preferably an organic polyhydroxyl compound known from
polyurethane chemistry.
Particularly suitable isocyanate-reactive compounds
~b) include known polyhydroxy polyethers having a molecular
weight in the range from 400 to about 10,000 (preferably in the
range from 1500 to 6000) and containing at least two
(preferably two to six) hydroxyl groups per molecule. Such
polyhydroxy polyethers can be obtained in known manner by
alkoxylation of suitable starter molecules. Suitable starter
o molecules include water, propylene glycol, glycerol,
trimethylolpropane, sorbitol, cane sugar, amino alcohols such
as ethanolamine or diethanolamine, aliphatic amines such as
hexylamine or 1,5-diaminohexane, or mixtures of such starter
molecules. Preferred alkoxylating agents include propylene
oxide and, optionally, ethylene oxide, which may be used in
admixture with propylene oxide or even separately in separate
reaction steps during the alkoxylation reaction.
Other suitable isocyanate-reactive compounds (b)
include known modification products of such polyether polyols,
that is, known graft polyethers based on the simple polyether
polyols mentioned above and known polyether polyols containing
polyaddition products as fillers, such as polyether polyols
containing polyhydrazocarbonamides as disperse fillers.
Also suitable as isocyanate-reactive compounds (b~ or
as a part of component (b) are polyester polyols having a
molecular weight in the range from 400 to about 10,~00
(preferably in the range from 1500 to 4000) and containing at
least two (preferably two to six) hydroxyl groups per molecule.
Suitable polyester polyols include the known reaction products
of excess quantities of polyhydric alcohols of the type
mentioned above as starter molecules with polybasic acids such
as succinic acid, adipic acid, phthalic acid, tetrahydro-
phthalic acid, or mixtures of such acids.
Low molecular weight polyhydroxyl compounds, that is,
those having a molecular weight in the range from 62 to 399,
Mo-3464
~ ~ 2 '~
are also suitable as component (b) or as a part of component
(b). Suitable low molecular weight polyhydroxyl compounds
include low molecular weight chain-extending agents or
crosslinking agents containing hydroxyl groups known from
polyurethane chemistry. Examples include alkane polyols of the
type mentioned above as starter molecules, as well as low
molecular weight polyether polyols of the type obtainable by
alkoxylation of such starter molecules.
As mentioned above, component (b) preferably contains
organic polyhydroxyl compounds or mixtures of organic
polyhydroxyl compounds of the type mentioned above. Component
(b) can be a mixture of the relatively high molecular weight
polyhydroxyl compounds mentioned above with the low molecular
weight polyhydroxyl compounds mentioned above or component (b)
can be a low molecular weight polyhydroxyl compound of the type
mentioned above used alone.
Salts of (i) organic carboxylic acids and (ii)
nitrogen bases containing at least one N-H bond are used as the
blowing agents (c) of the invention, optionally together with
other known chemical or physical blowing agents.
Suitable carboxylic acids (i) for the preparation of
the salts (c) include, preferably, aliphatic carboxylic acids
having a molecular weight in the range from about 46 to about
~00 (preferably in the range from 60 to 300). For the purposes
of the invention, cycloaliphatic compounds are regarded as
aliphatic compounds. Particularly preferred carboxylic acids
are those which contain, in addition to the carboxyl group
always present in a carboxylic acid, additional carboxyl groups
and/or at least one isocyanate-reactive group selected from the
group consisting of primary alcoholic hydroxyl groups,
secondary alcoholic hydroxyl groups, mercapto groups, primary
amino groups, and secondary amino groups. Accordingly,
suitable carboxylic acids can be simple monocarboxylic acids,
such as acetic acid, propionic acid, pivalic acid, cyclohexane
carboxylic acid, dodecanoic acid, stearic acid, oleic acid, or
Mo-34~4
2~2~a
-7-
mixtures of such acids, but are preferably aliphatic carboxylic
acids which contain, in addition to the carboxyl group, other
reactive groups of the type described above. Preferred
aliphatic carboxylic acids containing other reactive groups
include lactic acid (i.e., 2-hydroxypropanoic acid), glycolic
acidS tartaric acid, 2-mercaptoacetic acid, 3-mercaptopropionic
acid, hydroxypivalic acid, 6-aminohexanoic acid, 6-methyl-
aminohexanoic acid, succinic acid, adipic acid, or hexahydro-
phthalic acid. Lactic aid is a particularly preferred organic
o carboxylic acid.
Suitable but less preferred organic carboxylic acids
(i) include aromatic carboxylic acids, such as benzoic acid,
4-methylbenzoic acid, or phthalic acid.
Suitable nitrogen bases (ii) for the preparation of
the salts (c) of the invention include basic nitrogen-
containing compounds that contain at least one NH bond per
molecule and that are capable of forming salts with the acids.
Particularly preferred nitrogen bases include amines
corresponding to the formula
H
Rl N - R2
wherein
Rl represents hydrogen, a Cl 18 (preferably Cl 4) aliphatic
hydrocarbon group, a Cl 1~ (preferably Cl 4) aliphatic
hydrocarbon group containing further nitrogen atoms, a
C2 4 hydroxyalkyl group, or a group of the formula -NHR
(wherein R is hydrogen or Cl 4 alkyl), and
30 R represents hydrogen, a Cl 18 (preferably Cl 4) aliphatic
hydrocarbon group, a C2 4 hydroxyalkyl group, a C6 15
aromatic hydrocarbon group, a C6 15 aromatic hydroc~rbon
group containing further amino groups, or the residue left
by formal removal of an amino group from a polyamino
poly~ther containing 2 to 4 primary aliphatic amino groups
Mo-3464
~2 ~&7~
and having a molecular weight in the range from 400 to
about 12,000, with the proviso that Rl is hydrogen when R2
is the residue of said polyamino ether; or
Rl and R2 together with the nitrogen atom form a preferably
saturated heterocyclic 5- or 6-membered ring optionally
containing further ring heteroatoms (preferably nitrogen,
oxygen, or sulfur).
Examples of suitable amines for the preparation of
the salts (c) of the invention include methylamine, propyl-
amine, 2-ethylhexylamine, ethanolamine, oleylamine, dimethyl-
amine, dibutylamine, diethanolamine, diisopropanolamine,
1,2-diaminoethane, 1,2- and 1,3-diaminopropane, 1,6-diamino-
hexane, N,N-dimethyl ethylenediamine, piperazine, N-methyl-
ethylenediamine, N-butyl-1,3-propylenediamine, diethylenetri-
amine, triethylene tetraamine, aniline, 2,4- and ~,6-diamino-
toluene, 2,4'- and 4,4'-diaminodiphenylmethane, ammonia,
hydrazine, hydroxylamine, and N-methylhydrazine. Also suitable
are amino polyethers containing aromatically or, preferably,
aliphatically bound primary amino groups having a molecular
weight in the range from 400 to about 12,000 (preferably in the
range from 2000 to 8000). Amines containing tertiary amino
groups and, in addition to the tertiary amino group, at least
one primary or secondary amino group, such as N,N-dimethyl-
1,3-propylene diamine, are also suitable.
The salts (c) are prepared by reaction of the
carboxylic acids with the nitrogen bases using known methods.
~o prepare the preferred organic ammonium lactates, for
example, it is possible initially to introduce the nitrogen
base and gradually to add the calculated quant;ty of lactic
acid, preferably at temperatures kept below 50C. When
preparing the lactate salts, an aqueous solution of about 80 to
about 99YO by wei~ht lactic acid and about 20 to about 1% by
weight water (preferably commercial 90% aqueous lactic acid) is
generally used. After the addition is completed, the ~ixture
iS then heated at 80C for about 30 minutes to convert any
Mo-3464
7 ~
condensation products of the lactic acid into the monomeric
form. In the reaction with ammonia, the calculated quantity of
ammonia can be introduced, for example, into 90% lactic acid
through a gas inlet pipe at temperatures below 50C, with the
resultant mixture then being stirred for about 30 minutes at
80C. It is, or course, possible to prepare salts of other
carboxylic acids of the invention in like manner.
~hen using nitrogen bases that are not organic
diamines or polyamines, it is even possible to prepare the salt
in situ in the polyol component (b) by a simple mixing of the
monofunctional amine and the carboxylic acid in the polyol
component (b). The two salt components can be added in any
order or even at the same time. The in-situ preparation of
salts of difunctional and polyfunctional amines, on the other
hand, falls within the scope of German Patent Application
P 3,840,817.1 and is not the subject of the present invention.
When the salts are p~epared in situ in the component (b), or even when separately
prepared, equivalent quantities of amine and carboxylic acid
are generally used. The amine component, however, may also be
used in an excess quantity, for example, in an equivalent ratio
of amino groups (in the context of the invention, amino groups
always include all amino groups neutralizable with the acids)
to carboxyl groups of up to 4:1. It is also possible, although
even less preferred, to use an excess of acid, for example, in
an equivalent ratio of carboxyl groups to amino groups of up to
4:1. When an excess of either component is used, catalysis of
the system must be adapted according to the particular excess.
The equivalent ratio of carboxyl groups to amino groups
neutralizable with the carboxyl groups is from about 0.5:1 to
about 2:1 (preferably 1:1).
In the practical application of the process according
to the invention, the salts (c) of the invention discussed
above may even be used in combination with small quantities of
other known chemical or physical blowing agents, including
water, gases physically dissolved in the starting components
Mo-3464
2~67~
-10-
(such as air, carbon dioxide, or nitrogen), pyrocarbonic acid
esters, nitrogen-generating compounds, volatile hydrocarbons,
or halogenated hydrocarbons. Apart from the often unavoidable
presence of stirred-in water and air, however, the use of these
other blowing agents is not preferred. In general, such other
blowing agents, if present at all, make up no more than 50% by
weight (preferably no more than 25% by weight) of the total
amount of blowing agents present in the reaction mixture.
~he use of water as an additional blowing agent often
cannot be avoided because the starting components, particularly
polyol component (b), often contain traces of water. Some of
the carboxylic acids are commercially available as mixtures
with water and are used as such. In general, the total
quantity of water present in the reaction mixture is no more
than 3 mole and generally no more than 1.5 mole of water per
mole of carboxylate groups present in the salts. When lactic
acid, the preferred acid component, is used, it is often used
as an 80 to 99% by weight aqueous solution.
The total quantity of blowing agent (c) does, oF
course, depend on the particular density required for the
molded products. In general, the weight of the acid component
present in component (c) makes up from about 0.1 to about 10%
by weight (preferably from 0.4 to 4% by weight) of the reaction
mixture of components (a), (b), (c~, and (d). The
isocyanate-reactive groups of component (c) are included in the
calculation of the isocyanate index.
The optionally used other auxiliaries and additives
(d) include known catalysts that accelerate the isocyanate
polyaddition reaction. Suitable catalysts include tertiary
amines, such as triethylenediamine, N,N-d;methylbenzylamine,
and N,N-dimethylcyclohexylamine, or organometallic compounds,
particularly tin compounds such as tin(II) octoate or dibutyl
tin dilaurate. I~ polyurethane foams containing isocyanurate
groups are to be prepared by the process of the invention, it
also possible to use trimerization catalysts, including alkali
Mo-3464
~ ~ 2 ~ ~ 7 ~
-11-
acetates such as sodium or potassium acetate, alkali phenolates
such as sodium phenolate or sodium trichlorophenolate, or
2,4,6-tris(dimethylaminomethyl)phenol, or even lead
naphthenate, lead benzoate, and lead octoate.
Other optional auxiliaries and additives (d) include
known foam stabilizers, for example, those based on
polyether-modified polysiloxanes. Other auxiliaries and
additives (d) which may optionally be used include internal
mold release agents, for example, those described in European
o Patent Application 81,701; U.S. Patents 3,726,952, 4,098,731,
4,058,4g2, 4,033,912 4,024,090, and 4,098,731; British Patent
1,365,215; and German Offenlegungsschriften 2,319,648 and
2,427,273.
The process of the invention is generally carried out
15 by first mixing starting components (b), (c), and (d~ together
and then combining the resulting mixture with polyisocy~nate
component (a). Mixing is carried out, for example, using
stirrer-type mixers or, preferably, using high-pressure mixing
units of the type typically used in the preparation of
20 polyurethane foams. Immediately after preparation, the
reaction mixture is introduced into the mold in a quantity
adapted to the desired density of the molded product. In
addition to this single-stage process, the process according to
the invention may also be carried out on the semi-prepolymer
25 principle. In the semi-prepolymer method, the total quantity
of polyisocyanate component (a~ is reacted with part of
component (b), preferably while maintaining an NCO:OH
equivalent ratio of at least 3:1 (preferably at least 8:1), to
form an NCO semi-prepolymer which is then reacted with a
30 mixture of the remaining components (b~, (c), and (d). Poly-
hydroxyl compounds (b) that are different from the polyhydroxyl
compounds (b) subsequently mixed with the NCO semi-prepolymers
may, of course, be used for the preparation of the NCO
semi-prepolymers.
Mo-3464
2 ~
In all variants of the process of the invention, the
quantities in which the individual components are used are
selected so that the isocyanate index is from 75 to 1500,
preferably from 80 to 150. By "isocyanate index" is meant the
5 quotient, multiplied by 100, of the number of isocyanate groups
and the number of isocyanate-reactive groups. Isocyanate
indexes far above 100 are appropriate when it is desired to
prepare isocyanurate-modified polyurethane foams using
trimer;~ation catalysts.
The molded products of the invention have densities
of at least 250 (preferably from 4U0 to 800) kg/m3.
In ~eneral, the temperature of the molds used is at
least 30C, preferably at least 50C. If necessary, the inner
walls of the molds may be coated before filling with known
15 external mold release agents.
The salts used as blowing agents according to the
invention may replace the fluorochlorocarbon blowing agents
previously used in all of the usual formulations for the
preparation of polyurethane foam moldings without any need for
20 significant changes in the catalysts used. The quantity of
polyisocyanate must simply be adapted to the NC0-reactive
components (i.e., carboxylic acid, nitrogen base, and,
optionally, water) introduced along with the salts.
Accordingly, the process of the invention provides a
25 method for preparing high-quality polyurethane foam moldings
having a compact, bubble-free skin without any need for the
fluorocarbon blowing agents that have previously always been
used. The process according to the invention is particularly
suitable for the preparation of semi-rigid to rigid integral
30 foams having a compact skin of the type widely used in the
automotive industry and furniture industry.
The following examples further illustrate details for
the process of this invention. The invention, which is set
forth in the foregoing disclosure, is not to be limited either
35 in spirit or scope by these examples. Those skilled in the art
Mo-3464
~276~
will readily understand that known variations of the conditions
of the following procedures can be used. Unless otherwise
noted, all temperatures are degrees Celsius and all parts and
percentages are parts by weight and percentages by weight.
EXAMPLES
Examples 1 to 7
The formulations used in Examples 1-7 were prepared
using the following starting materials according to the
proportions (in parts by weight) shown in Table 1.
Startin~ materials:
Polvisocvanate com~onent (al): Polyisocyanate mixture of the
diphenylmethane series having an NCO content of 31% by weight
and a content of isomeric diisocyanatodiphenylmethanes of 60%
by weight (of which 55% by weight consists of 4,4'-diiso-
cyanatodiphenylmethane and approximately 5% by weight of
2,4'-diisocyanatodiphenylmethane)
PolYol component (bl): Propoxylation product (OH value 860) of
trimethylolpropane
Polvol component (b2!: Propoxylation product (OH value 42) of
trimethylolpropane
Blowinq aqent (cl): Salt of 2-hydroxypropanoic acid and
diethanolamine (equivalence ratio of 1:1)
Blowinq aqent (c2): Salt of 2-hydroxypropanoic acid and
ammonia (equivalence ratio of 1:1)
Blowinq aqent (c3): Salt of 2-hydroxypropanoic acid and
ethylene diamine (equivalence ratio of ~
Blowinq aqent (c4): Salt of propanoic acid and diethanolamine
~equivalence ratio of 1:1)
Blowing aqent ~c5): Salt of oleic acid and diethanolamine
~equivalence ratio of 1:1)
Additive (dl~ (stabili2erl: Commercial polyetner siloxane
(TE60STAB ~OS 50, a product of Goldschmidt AGs 4300 Essen 1,
West Germany)
Additive (d2) (Catalvst): ~,N-dimethylcyclohexylamine
Mo-3464
202i~G~
Examples 1-5 are examples according to the invention.
Example 6 is Comparison Example using water as C02-forming
blowing agent. Example 7 is a Comparison Example using
monofluorotrichloromethane ("R 11") as blowing agent
(conventional integral foam of high rigidity).
Mo-3464
2 ~ 2 6' 3 3 7 i~
--15--
0~ o
~D 1-0' ' I ' I I C`~O I ~_
. ~ ~oo
U~ ~f) ~ I I I I _ ~ ~ O I ~ _:
~ ~ ~ SDO
EX et ~ o~ _ _I
L~l
~> u~ ~ I I e~ I I ~ ~ C~ I ~
C~J ~ ~o
r- c~ r~ a u~ _
I
n
_ C~ ~ ~D O C-
E ~ ~ _ _ ~
L~ ~c)
~ ~ o
E
. l E o
l _ ~ ~ ~ U~ O ~ 4_
_ o
__~
I ~.~ .) al
l CCCCC~ ~ _
LL ~ ~ ~> c ~
C~ O ~ _
~ ~ ~ a ~ nl ~;1 ~ q~ ~ :~ X ~
_ ~) ~ l ~ o o~ C
C ~ r- C C C C C ~ ~ r~ v~ C
o o o~ 4 ~
~_ Cl. ~ 2 3 2 3 2 ~ tl~ ~ O :~
E ~-- r ~ ~ ns o -- ~
t-- ~ c~ > ~ 3 ~ C~ Z c~:
Mo-3464
7 ~
--16--
General_Observations on the Examples
Sheet-form foam moldings having a density of 500
kg/m3 (see Table 2) were prepared using the formulations shown
in Table 1. The mold used was a sheet mold measuring 10 x 200
X 200 mm, the inner walls of which had been coated with a
commercial external wax-based mold release agent (ACMOSIL~ 180,
a product of Acmos, D-2800 Bremen 1, West GermanyJ. Before
processing, the polyol mixtures were charged with 10% by volume
(based on atmospheric pressure) of finely dispersed air by
brief stirring at high speed (5 minutes at 1000 r.p.m using a
propeller stirrer).
The reaction mixtures were prepared from the polyol
mixtures and the polyisocyanate component (a) using a typical
stirrer-type mixer. The densities of the particular moldings
were determined by the quantity of reaction mixture introduced
into the mold. Table 2 shows the Shore D surface hardness of
the individual foam moldings.
Table 2 - ~hore D surface hardness
Density Examples
(kg/~3)
1 2 3 4 5 6 7
500 66 66 66 66 64 57 69
The surface hardness of each of Examples 1 to 5
according to the invention is distinctly greater than that of
Comparison Example 6 at this density and only slightly below
30 the surface hardness of the integral foam produced without
water using R 11 as blowing agent (Comparison Example 7).
Examples 8 to ll - Preparation of semi-rigid molded foams
having a compact skin
Mo- 3464
~ ~r~
-17-
The formulations used in Examples 8-11 were prepared
using the following starting materials according to the
proportions (in parts by weight) shown in Table 3.
Starting materials:
PolYisocYanate (a2): Urethane-modified polyisocyanate mixture
ha~ing an average NCO functionality of 2.2 and an NCO content
of 28.5% by weight prepared by reaction of polypropylene glycol
having an average molecular weight of 218 with a polyisocyanate
mixture of the diphenylmethane series consisting of 75 parts by
weight 4,4'-diisocyanatodiphenyl~ethane, 4 parts by weight
2,4'-diisocyanatodiphenylmethane, and 21 parts by weight of
more highly nuclear polyisocyanates of the diphenyl methane
series
PolYol (b3): Polyether polyol (OH value 28) prepared by
propoxylation of trimethylolpropane and subsequent ethoxylation
of the propoxylation product (ratio by weight PO:E0 of 80:20)
Polvol (b4): Polyether polyol (OH value 470) prepared by
ethoxylation of N-ethyldiethanolamine
Blowing aaent (c6~: Reaction product of 1 mole of ethylene
diamine and 1 mole of aqueous 90% lactic acid
Blowinq agent (c7): Reaction product of 1 mole of
diethanolamine and 1 mole of aqueous 90% lactic acid
CatalYst (d3): 30% Solution of triethylene diamine in
dipropylene glycol
Catalyst (d4): Dibutyltin dilaurate
Stabilizer (d3): Commercial polyether polysiloxane stabilizer
(Stabilizer DC 193, a product of Dow Corning)
Sheet-form semi-rigid foam moldings having a density
of 600 kg/m3 were prepared using the formulations shown in
Table 3. The mold used was an aluminum sheet mold measuring 20
x 30 x 1 cm, the inner walls of which had been coated with a
commercial external mold release agent (FLUORICON~ 36-134, a
product of Acmos, D-2800 Bremen 1, West Germany). The mold
temperature was kept at 45~C for each example.
Mo-3464
2 ~ 2 ~ ~ 7 1~
--18--
I~ lD u~
~o)~o~ c~J o~
r-~ O N N N O I I I O I O
r~
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u~ l O
O O N C~l N O I I Lr~ O I C > el ~
-
E
X ~ ~ r~ N
1~ o~ I N
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Mo- 3464
7 ~
--19--
General Observat;ons on the Examples:
In Example 11, only water was used as blowing agent.
After demolding, the sheet expanded and had a higher surface
hardness than the sheets of Examples 8 and 9.
