Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
2Q~ 9
PROCESS FOR THE PREPARATION OF MOLDED ARTICLES=-
HAVING A COMPRESSED PERIPHERAL ZONE AND A
CELLULAR CORE, PREFERABLY SHOE SOLES
Background of the Invention
I. Field of the Invention
The present invention relates to a process for the
preparation of urethane group-containing molded articles, most
preferably shoe soles, having a compressed peripheral zone and
a cellular core, the so-called integral skin foams, from
conventional starting materials, but using low boiling point
aliphatic and/or cycloaliphatic hydrocarbons having 4 to 8
carbon atoms in the molecule as a blowing agent.
II. Description of the Related Art
The preparation of molded articles having a cellular
core and a compressed peripheral zone has been known for some
time and, for example, is disclosed in Federal Republic of
Germany, 16 94 138 (Great Britain 1 209 243), Federal Republic
of Germany 19 55 891 (Great Britain 1 321 679) and Federal
Republic of Germany 17 69 886 (United States Patent 3 824
199). Such products are generally prepared by reacting organic
polyisocyanates, higher molecular weight compounds having at
least two reactive hydrogen atoms and optionally chain sxtend-
ing agents in the presence of blowing agents, more preferably
20~ 019
physically active blowing agents, catalysts, auxiliaries and/or
additives in a closed, optionally heated, mold using compres-
sion.
Also known is the preparation and use of urethane
group-containing shoe soles prepared by the polyisocyanate
addition polymerization process in the shoe industry. Direct
shoe soling and the preparation of polyurethane finished soles
are primary areas of application for polyurethanes in the shoe
industry. Such polyurethane shoe soles can be manufactured
using low pressure or high pressure technology (RIM) (Schuh-
Technik + abc, 10/1980, pages 822 ff).
A comprehensive overview of polyurethane integral
skin foams has been published, for example, in Integral Skin
Foams by H. Piechota and H. Rohr, Carl-Hanser Publishers,
Munich, Vienna, 1975, and in the Plastics Handbook, Volume 7,
Polyurethanes, by G. Oertel, Carl-Hanser Publishers, Munich,
Vienna, 2nd Ed., 1983, pages 333 ff. The latter reference
describes (pages 362-366) using integral skin foams in the shoe
industry.
Essentially two types of blowing agents are used in
the preparation of cellular plastics employing the polyisocya-
nate addition polymerization process:
Low boiling point inert liquids which evaporate under
the influence of the exothermic addition polymerization
2C~ 019
reaction; for example, alkanes, like butane, pentane, etc. or
preferably halogenated hydrocarbons, like methylene chloride,
di-chloromonofluoromethane, trichlorofluoromethane, etc.; and
chemical compounds which form propellants through a chemical
reaction or by thermal decomposition. Examples of the latter
are the reaction of water with isocyanates to form amines and
carbon dioxide which occurs in synchronization with poly-
urethane formation, and the cleavage of thermally labile
compounds, such as, for example, azoisobutyric acid nitrile
which along with nitrogen as a cleavage product forms the toxic
tetramethylsuccinic acid dinitrile, or azodicarbonamide whose
use as a component in a blowing agent combination is disclosed
in European Patent Application 0 092 740 (Canadian Patent 1 208
912). While the latter method in which thermally labile
compounds, such as azo-compounds, hydrazides, semicarbazides,
N-nitroso compounds, benzoxazines, etc. (Kunstsoffe 66 (1976),
10, pages 698-701) are generally incorporated into a prefabri-
cated polymer, or rolled into plastic granules following which
the compound is foamed by extrusion has remained of little
industrial importance, the physically active low boiling point
liquids, particularly chlorofluoroalkanes (CFC), are used
through~ut the world on a large scale to produce polyurethane
foams and polyisocyanurate foams.
ZO(~Ol9
A disadvantage of propellants is the problem-~f
environmental pollution. When propellants are formed by
th~rmal cleavage or a chemical reaction, cleavage products
and/or reactive byproducts are formed and become incorporated
into the addition polymerization product or are chemically
bound and thus can lead to an unwanted change in the mechanical
properties of the plastic. In the case of formation of carbon
dioxide from water and diisocyanate, urea groups are formed in
the addition polymerization product and, depending on their
quantity, can lead to either an improvement in compressive
strength or to embrittlement of the polyurethane.
Although aliphatic hydrocarbons such as pentane,
hexane and heptane are inexpensive and non-hazardous to health,
in the prior art they are only used for foaming thermo-
plastics. Pentane and its isomers are, for example, used in
the preparation of expanded polystyrene (Kunststoffe 62 (1972),
pages 206-208) and also in phenolic resin foams (Kunststoffe,
60 (1970), pages 548-549).
Federal Republic of Germany 1 155 234 (Great Britain
904 003) discloses the preparation of polyurethane foams from
an isocyanate group containing prepolymer while using a blowing
agent mixture comprising water and a soluble insert gas which
is-liquid under pressure. Cited as typical inert gases, are,
for example, gaseous hydrocarbons, halogenated hydrocarbons,
z~n~ols
ethylene oxide, nitric oxides, sulfur dioxide and more ~refer-
ably, carbon dioxide. According to Great Britain 876 977,
sat-urated or unsaturated hydrocarbons, saturated or unsaturated
dialkylethers and fluorine containing halogenated hydrocarbons
can be used, for example, as blowing agents in the preparation
of polyurethane rigid foams.
The high flamability, and accordingly the expensive
safety measures required to use gaseous alkanes in production,
is why alkanes have not been used in the prior art as blowing
agents for foaming polyisocyanate addition polymerization
products. Heretofore, there have been no teachings dealing
with using alkanes for the preparation of integral skin
foams. The object of the present invention was to completely,
or at least partially, replace the conventional CFC's used as
blowing agents in the preparation of polyurethane integral skin
foams by other environmentally compatible blowing agents.
This object was suprisingly met by using aliphatic or
cycloaliphatic hydrocarbons as blowing agents.
Accordingly, the subject of the invention is a
process for the preparation of molded articles having a
compressed peripheral zone and a cellular core, comprising
reacting:
a) organic and/or modified organic polyisocyanates
with:
2(~ 9
b) at-least one higher molecular weight compound
having at least two reactive hydrogen atoms; and with or
without
c) lower molecular weight chain extending agents
and/or crosslinking agents;
in the presence of
d) blowing agents;
e) catalysts; and with or without
f) auxiliaries and/or additives;
in a closed, optionally heated mold under compres-
sion, wherein low boiling point aliphatic or cycloaliphatic
alkanes having 4 to 8 carbon atoms in the molecule or mixtures
thereof are used as the blowing agent (d).
The process is particularly suited for the prepara-
tion of flexible elastic shoe soles, having a total density of
from 0.4 to 1.0 g/cm3, yet the starting components are effi-
caciously reacted using a one shot process with the help of
high pressure technology (RIM).
Description of the Preferred Embodiments
It was unexpectedly found that the alkanes used as
blowing agents provided polyurethane integral skin foams having
good mechanical properties which are comparable at least with
products prepared while using trichlorofluoromethane. Since
the gas yields, i.e. the foam volume obtained per mole of
2~(30~9
blowing agent, with the (cyclo)aliphatic alkanes are suhstan-
tially greater then those of the previously used CFC's having a
comparable boiling point, the lower molecular weight allows a
substantial reduction in the required quantity of blowing
agent. Thus, with alkane contents of from 35 to 40 weight
percent based on the required CFC quantity, polyurethane
integral skin foams having the same total density were
obtained. In spite of the reduced blowing agent quantity, the
compressed peripheral zone on the surface is smooth and
essentially pore-free. Because of the low required amount of
blowing agent which for the most part, following curing of the
integral skin foam, dissolves in the peripheral zone or remains
in the cells of the core, the amount of alkane released during
foaming is also low and thus no serious safety problems occur
when processing.
The following should be noted with respect to typical
starting components (a) through (f) for the preparation of
molded articles such as shoe soles, more preferably urethane,
or urethane and urea group-containing cellular elastomer molded
articles and most preferably integral skin foams:
The organic polyisocyanates (a) may include all
essentially known aliphatic, cycloaliphatic, araliphatic and
preferably aromatic multivalent isocyanates.
2C~ 0~9
Specific examples include: alkylene diisocyanates
with 4 to 12 carbons in the alkylene radical such as 1,12-
dodecane diisocyanate, 2-ethyl-1,4-tetramethylene diisocyanate,
2-methyl-1,5-pentamethylene diisocyanate, 1,4-tetramethylene
diisocyanate, and preferably 1,6-hexamethylene diisocyanate;
cycloaliphatic diisocyanates such as 1,3- and 1,4-cyclohexane
diisocyanate as well as any mixtures of these isomers, 1-
isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane
(isophorone diisocyanate), 2,4- and 2,6-hexahydrotoluene
diisocyanate as well as the corresponding isomeric mixtures,
4,4'-, 2,2'-, and 2,4'-dicyclohexylmethane diisocyanate as well
as the corresponding isomeric mixtures; and preferably aromatic
diisocyanates and polyisocyanates such as 2,4- and 2,6-toluene
diisocyanate and the corresponding isomeric mixtures, 4,4'-,
2,4'-, and 2,2'-diphenylmethane diisocyanate and the cor-
responding isomeric mixtures, mixtures of 4,4'- and 2,4'-
diphenylmethane diisocyanates and polyphenylpolymethylene
polyisocyanates (polymeric MDI~ as well as mixtures of poly-
meric MDI and toluene diisocyanates. The organic di- and
polyisocyanates can be used individually or in the form of
mixtures.
Frequently, so-called modified multivalent iso-
cyanates, i.e., products obtained by chemical reaction of
organic diisocyanates and/or polyisocyanates, are used.
--8--
2C~ 019
Examples-include diisocyanates and/or polyisocyanates cQntain-
ing ester groups, urea groups, biuret groups, allophanate
groups, carbodiimide groups, isocyanurate groups, uretdione
groups and/or urethane groups. Specific examples include
organic, preferably aromatic, polyisocyanates containing
urethane groups and having an NCO content of 33.6 to 15 weight
percent, preferably 31 to 21 weight percent, based on the total
weight, e.g., with low molecular weight diols, triols,
dialkylene glycols, trialkylene glycols or polyoxyalkylene
glycols with a molecular weight of up to 800: modified 4,4'-
diphenylmethane diisocyanate or 2,4- and 2,6-toluene diisocya-
nate, where examples of di- and polyoxyalkylene glycols that
may be used individually or as mixtures include diethylene
glycol, dipropylene glycol, polyoxyethylene glycol, polyoxy-
propylene glycol and polyoxypropylene polyoxyethylene glycol.
Prepolymers containing NCO groups with an NCO content of 25 to
3.5 weight percent, preferably 21 to 14 weight percent, based
on the total weight and produced from polyester polyols and/or
preferably the polyether polyols described below; 4,4'-
diphenylmethane diisocyanate, mixtures of 2,4'- and 4,4'-
diphenylmethane diisocyanate, 2,4- and/or 2,6-toluene diiso-
cyanates or polymeric MDI are also suitable. Furthermore,
liquid polyisocyanates containing carbodiimide groups and/or
isocyanurate rings and having an NCO content of 33.6 to 15
019
weight percent, preferably 31 to 21 weight percent, bas~d on
the total weight, have also proved suitable, e.g., based on .
4,4'- and 2,4'- and/or 2,2'-diphenylmethane diisocyanate and/or
2,4- and/or 2,6-toluene diisocyanate.
The modified polyisocyanates may optionally be mixed
together or mixed with unmodified organic polyisocyanates such
as 2,4'- and 4,4'-diphenylmethane diisocyanate, polymeric MDI,
2,4- and/or 2,6-toluene diisocyanate.
The following have proven especially successful as
organic polyisocyanates and are preferred for use in the
preparation of cellular elastomers: prepolymers containing NCO
groups and having an NCO content of 25 to 9 weight percent,
especially those based on polyether polyols or polyester
polyols and one or more diphenylmethane diisocyanate isomers,
preferably 4,4'-diphenylmethane diisocyanate; and/or modified
organic polyisocyanates containing urethane groups and having
an NCO content of 33.6 to 15 weight percent, especially those
based on 4,4'-diphenylmethane diisocyanate or diphenylmethane
diisocyanate isomeric mixtures; for preparation of flexible
polyurethane foams: mixtures of 2,4- and 2,6-toluene diiso-
cyanates, mixtures of toluene diisocyanates and polymeric MDI
or especially mixtures of the aforementioned prepolymers based
on diphenylmethane diisocyanate isomers and polymeric MDI; and
for the preparation of polyurethane rigid foams or poly-
urethane-polyisocyanurate rigid foams, polymeric MDI.
--10--
2Q(~019
If molded articles having a lightfast surfacet such
as for example, automobile steering wheels or instrument
panels, are required for specific applications, then in their
preparation one preferably uses aliphatic or cycloaliphatic
polyisocyanates, most preferably, modified polyisocyanates
based on 1,6-hexamethylene diisocyanate or isophorone diiso-
cyanate or mixtures of the above-mentioned diisocyanates
optionally with diphenylmethane diisocyanate and/or toluene
diisocyanate isomers.
Preferred higher molecular weight compounds (b)
having at least two reactive hydrogens include those with a
functionality of 2 to 8, preferably 2 to 4, and a molecular
weight of 400 to 8000, preferably 1200 to 6000. For example,
polyether polyamines and/or preferably polyols selected from
the group consisting of polyether polyols, polyester polyols,
polythioether polyols, polyester amides, polyacetals containing
hydroxyl groups, aliphatic polycarbonates containing hydroxyl
groups, and mixtures of at least two of the aforementioned
polyols have proven suitable. Polyester polyols and/or
polyether polyols are preferred.
Suitable polyester polyols can be produced, for
example, from organic dicarboxylic acids with 2 to 12 carbons,
preferably aliphatic dicarboxylic acids with 4 to 6 carbons,
and multivalent alcohols, preferably diols, with 2 to 12
--11--
2Q(3(~ L9
carbons, preferably 2 to 6 carbons. Examples of dicarb~xylic
acids include succinic acid, glutaric acid, adipic aci-d,
suberic acid, azelaic acid, sebacic acid, decanedicarboxylic
acid, maleic acid, fumaric acid, phthalic acid, isophthalic
acid and terephthalic acid. The dicarboxylic acids can be used
individually or in mixtures. Instead of the free dicarboxylic
acids, the corresponding dicarboxylic acid derivatives may also
be used such as dicarboxylic acid esters of alcohols with 1 to
4 carbons or dicarboxylic acid anhydrides. Dicarboxylic acid
mixtures of succinic acid, glutaric acid and adipic acid in
quantity ratios of 20-35:35-50:20-32 parts by weight are
preferred, especially adipic acid. Examples of divalent and
multivalent alcohols, especially diols, include ethanediol,
diethylene glycol, 1,2- and 1,3-propanediol, dipropylene
glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,10-
decanediol, glycerol and trimethylolpropane. Ethanediol,
diethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-
hexanediol, or mixtures of at least two of these diols are
preferred, especially mixtures of 1,4-butanediol, 1,5-pentane-
diol and 1,6-hexanediol. Furthermore, polyester polyols of
lactones, e.g., ~-caprolactone or hydroxycarboxylic acids,
e.g., ~-hydroxycaproic acid, may also be used.
The polyester polyols can be produced by polyconden-
sation of organic polycarboxylic acids, e.g., aromatic or
-12-
2Q~(~0~9
preferably aliphatic polycarboxylic acids and/or deriva~ives
thereof and multivalent alcohols in the absence of catalysts or
preferably in the presence of esterification catalysts,
preferably in an atmosphere of inert gases, e.g., nitrogen,
carbon monoxide, helium, argon, etc., in the melt at tempera-
tures of 150 to 250~C, preferably 180 to 220~C, optionally
under reduced pressure, up to the desired acid value, which is
preferably less than 10, especially less than 2. In a prefer-
red embodiment, the esterification mixture is subjected to
polycondensation at the temperatures mentioned above up to an
acid value of 80 to 30, preferably 40 to 30, under normal
pressure and then under a pressure of less than 500 mbar,
preferably 50 to 150 mbar. Examples of suitable esterification
catalysts include iron, cadmium, cobalt, lead, zinc, antimony,
magnesium, titanium and tin catalysts in the form of metals,
metal oxides or metal salts. However, polycondensation may
also be performed in liquid phase in the presence of solvents
and/or entraining agents such as benzene, toluene, xylene or
chlorobenzene for azeotropic distillation of the water of
condensation.
To produce the polyester polyols, the organic
polycarboxylic acids and/or derivatives thereof and multivalènt
alcohols are preferably polycondensed in a mole ratio o~ 1:1-
1.8, preferably 1:1.05-1.2. The resulting polyester polyols
2C~(~G0~9
preferably have a functionality of 2 to 4, especially 2-to 3,
an~ a molecular weight of 480 to 3000, preferably 1200 to 30P0
and especially 18~0 to 2500.
However, polyether polyols, which can be obtained by
known methods, are especially preferred for use as the
polyols. For example, polyether polyols can be produced by
anionic polymerization with alkali hydroxides such as sodium
hydroxide or potassium hydroxide or alkali alcoholates, such as
sodium methylate, sodium ethylate or potassium ethylate or
potassium isopropylate as catalysts and with the addition of at
least one initiator molecule containing 2 to 8, preferably 2 to
4, reactive hydrogens or by cationic polymerization with Lewis
acids such as antimony pentachloride, boron trifluoride
etherate, etc., or bleaching earth as catalysts from one or
more alkylene oxides with 2 to 4 carbons in the alkylene group.
Suitable alkylene oxides include, for example,
tetrahydrofuran, 1,3-propylene oxide, 1,2- and 2,3-butylene
oxide, styrene oxide and preferably ethylene oxide and 1,2-
propylene oxide. The alkylene oxides may be used individually,
in alternation, one after the other or as a mixture. Examples
of suitable initiator molecules include water, organic dicarbo-
xylic acids such as succinic acid, adipic acid, phthalic acid
and terephthalic acid, aliphatic and aromatic, optionally N-
mono- N,N-, and N,N'-dialkyl substituted diamines with 1 to 4
2~ )19
carbons in the alkyl group such as optionally mono- and
dialkyl-substituted ethylenediamine, diethylenetriamine,
triethylenetetramine, 1,3-propylenediamine, 1,3- and 1,4-
butylenediamine, 1,2-, 1,3-, 1,4-, 1,5- and 1,6-hexamethylene-
diamine, phenylenediamines, 2,3-, 2,4- and 2,6-toluenediamine
and 4,4'-, 2,4'- and 2,2'-diaminodiphenylmethane.
Suitable initiator molecules also include alkanol-
amines such as ethanolamine, diethanolamine, N-methyl- and N-
ethylethanolamine, N-methyl- and N-ethyldiethanolamine and
triethanolamine plus ammonia. Multivalent alcohols, especially
divalent and/or trivalent alcohols are preferred such as
ethanediol, 1,2-propanediol and 1,3-propanediol, diethylene
glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol,
glycerol, trimethylolpropane, pentaerythritol, sorbitol and
sucrose.
The polyether polyols, preferably polyoxypropylene
polyols and polyoxypropylene-polyoxyethylene-polyols have a
functionality of preferably 2 to 6 and especially 2 to 4 and
have a molecular weight of 400 to 8000, preferably 1200 to 6000
and especially 1800 to 4000. Suitable polyoxytetramethylene
glycols have a molecular weight up to about 3500, more prefer-
ably 400 to 2200.
Suitable polyether polyols also include polymer
modified polyether polyols, preferably graft polyether polyols,
2~ 019
especially those based on styrene and/or acrylonitrile, which
are produced by in situ polymerization of acrylonitrile,
styrene or preferably mixtures of styrene and acrylonitrile,
e.g., in a weight ratio of 90:10 to 10:90, preferably 70:30 to
30:70, preferably in the aforementioned polyether polyols
according to the procedures described in Federal Republic of
Germany Patents 1,111,394, 1,222,669 (U.S. Patents 3,304,273,
3,383,351, 3,523,093~, 1,152,536 (British Patent 1,040,452) and
1,152,537 (British Patent 987,618), as well as polyether polyol
dispersions containing as the disperse phase, usually in the
amount of 1 to 50 weight percent, preferably 2 to 25 weight
percent: e.g., polyureas, polyhydrazides, polyurethanes
containing tertiary amino groups and/or melamine, which are
described, for example, in European Patent 11,752 (U.S. Patent
4,304,708), U.S. Patent 4,374,209 and Federal Republic of
Germany Patent 3,231,497.
Like the polyester polyols, the polyether polyols may
be used either individually or in the form of mixtures.
Furthermore, they can be mixed with the graft polyether polyols
or polyester polyols as well as the polyester amides containing
hydroxyl groups, the polyacetals, polycarbonates and/or
polyether polyamines.
Examples of hydroxyl group-containing polyacetals
that can be used include, for example, the compounds that can
-16-
2(~ 0~9
be produced from glycols such as diethylene glycol, triethylene
glycol, 4,4'-dihydroxyethoxydiphenyldimethylmethane, hexanediol
and formaldehyde. Suitable polyacetals can also be produced by
polymerization of cyclic acetals.
Suitable hydroxyl group-containing polycarbonates
include those of the known type such as those obtained by
reaction of diols, e.g., 1,3-propanediol, 1,4-butanediol and/or
1,6-hexanediol, diethylene glycol, triethylene glycol or
tetraethylene glycol and diaryl carbonates, e.g., diphenyl
carbonate, or phosgene.
The polyester amides include the mainly linear
condensates obtained from multivalent saturated and/or unsatu-
rated carboxylic acids and their anhydrides and multivalent
saturated and/or unsaturated amino alcohols or mixtures of
multivalent alcohols and amino alcohols and/or polyamines.
Suitable polyether polyamines can be produced from
the polyether polyols mentioned above by known methods.
Examples include cyanoalkylation of polyoxyalkylene polyols and
subsequent hydrogenation of the nitrile thus formed (U.S.
Patent 3,267,050) or partial or complete amination of polyoxy-
alkylene polyols with amines or ammonia in the presence of
hydrogen and catalysts (Federal Republic of Germany Patent
1,215,373).
ZQ~ )19
The molded articles having a compressed peripheral
zone and a cellular core and preferably urethane or urethane
and urea group-containing molded articles can be prepared with
or without using chain extending agents and/or crosslinking
agents. To modify the mechanical properties, e.g., hardness,
however, it has proven advantageous to add (c) chain extenders,
crosslinking agents or mixtures thereof. Suitable chain
extenders and/or crosslinking agents include diols and/or
triols with molecular weights of less than 400, preferably 60
to 300. Examples include aliphatic, cycloaliphatic and/or
araliphatic diols with 2 to 14 carbons, preferably 4 to 10
carbons, such as ethylene glycol, 1,3-propanediol, 1,10-
decanediol, 1,2-, 1,3-, and 1,4-dihydroxycyclohexane,
diethylene glycol, dipropylene glycol and preferably 1,4-
butanediol, 1,6-hexanediol and bis(2-hydroxyethyl)hydroquinone;
triols such as 1,2,4- and 1,3,5-trihydroxycyclohexane, glycerol
and trimethylolpropane and low molecular weight hydroxyl group-
containing polyalkylene oxides based on ethylene oxide and/or
1,2-propylene oxide and the aforementioned diols and/or triols
as initiator molecules.
In addition to the aforementioned diols and/or
triols, or in admixture with them as chain extenders or
-crosslinking agents to prepare the cellular elastomer molded
articles and integral skin foams, most preferably shoe soles
-18-
20~3~0~9
according to this invention, it is also possible to use-
secondary aromatic diamines, primary aromatic diamines, 3,3'
di- and/or 3,3'-, 5,5'-tetraalkyl-substituted diaminodiphenyl-
methanes.
Examples of secondary aromatic diamines include N,N'-
dialkyl-substituted aromatic diamines, which may optionally be
substituted on the aromatic ring by alkyl groups, where there
are 1 to 20, preferably 1 to 4 carbons in the N-alkyl group
such as N,N'-diethyl-, N,N'-di-sec-pentyl-, N,N'-di-sec-hexyl-,
N,N'-di-sec-decyl-, N,N'-dicyclohexyl-p- or -m-phenylene-
diamine; N,N'-dimethyl-, N,N'-diethyl-, N,N'-diisopropyl-,
N,N'-di-sec-butyl-, N,N'-dicyclohexyl-4,4',-diaminodiphenyl-
methane and N,N'-di-sec-butylbenzidine.
The preferred aromatic diamines are those having at
least one alkyl substituent in ortho position to the amino
groups and they are liquid at room temperature and are miscible
with component (b), especially the polyether polyols. Further-
more, alkyl-substituted meta-phenylenediamines of the following
formulas have also proven successful:
R2 NH2 R2 NH2
2 ~ R and/or ~ R
R3 R3 NH2
--19--
2~ 019
where R3 and R2 may be the same or different and denote a
methyl group, a propyl group, and an isopropyl group, and Rl is
a linear or branched alkyl group with 1 to 10 carbons,
preferably 4 to 6 carbons.
Alkyl groups Rl in which the branching site is on the
cl carbon are especially suitable. Examples of Rl groups
include methyl, ethyl, isopropyl, l-methyloctyl, 2-ethyloctyl,
l-methylhexyl, l,l-dimethylpentyl, 1,3,3-trimethylhexyl, 1-
ethylpentyl, 2-ethylpentyl and preferably cyclohexyl, l-methyl-
n-propyl, tert.-butyl, l-ethyl-n-propyl, l-methyl-n-butyl, and
l,l-dimethyl-n-propyl.
Examples of alkyl-substituted m-phenylenediamines
include especially: 2,4-dimethyl-6-cyclohexyl-1,3-phenylene-
diamine, 2-cyclohexyl-4,5-diethyl-1,3-phenylenediamine, 2-
cyclohexyl-2,6-isopropyl-1,3-phenylenediamine, 2,4-dimethyl-6-
(l-ethyl-n-propyl)-1,3-phenylenediamine, 2,4-dimethyl-6-(1,1,-
dimethyl-n-propyl)-1,3-phenylenediamine and 2-(1-methyl-n-
butyl)-4,6-dimethyl-1,3-phenylenediamine. Preferred examples
include l-methyl-3,5-diethyl-2,4- and 2,6-phenylenediamines,
2,4-dimethyl-6-tert-butyl-1,3-phenylenediamine, 2,4-dimethyl-6-
isooctyl-1,3-phenylenediamine and 2,4-dimethyl-6-cyclohexyl-
1,3-phenylenediamine.
-20-
Z0(~(~019
Suitable 3,3'-di- and 3,3',5,5'-tetra-n-alkyl-
substituted 4,4'-diaminodiphenylmethanes include, for examplç,
3,3'-dimethyl-3,3',5,5'-tetramethyl, 3,3'-diethyl-, 3,3',5,5'-
tetraethyl-, 3,3'-di-n-propyl and 3,3',5,5'-tetra-n-propyl-
4,4'-diaminodiphenylmethane.
Diaminodiphenylmethanes of the following formula are
preferred:
R5 R6
H2N~ CH2--~NH2
where R4, R5, R6 and R7 may be the same or different and denote
a methyl group, an ethyl group, a propyl group, an isopropyl
group, a sec-butyl group and a tert.-butyl group, but at least
one of the groups must be an isopropyl group or a sec-butyl
group. The 4,4'-diaminodiphenylmethanes may also be used in
mixture with isomers of the formulas
2~G0~9
H2N R5 R6 2 R5
R4~H2 ~NH2 and/or R4--~--CH ~R6
where R4, R5, R6 and R7 have the meanings given above.
The preferred diaminodiphenylmethanes are 3,5-
dimethyl-3',5'-diisopropyl-4,4'-diaminodiphenylmethane and
3,3',5,5'-tetraisopropyl-4,4'-diaminodiphenylmethane. The
diaminodiphenylmethanes may be used individually or in the form
of mixtures.
These chain extenders and/or crosslinking agents (c)
may be used individually or as mixtures of the same or dif-
ferent types of compounds.
If chain extenders, crosslinking agents or mixtures
thereof are used, they are preferably used in amounts of 2 to
60 weight percent preferably 8 to 50 weight percent and
especially 10 to 40 weight percent, based on the weight of
components (b) and (c).
In the preparation of the flexible elastic shoe
soles, one preferably uses as said higher molecular weight
compounds (b), polyester polyols or polyether polyols having a
functionality of from 2 to 4, more preferably 2 and a molecular
-22-
zoo~o~9
weight of 1200 to 6000 and as said chain extending agent or
cross linking agent (c), primary aromatic diamines which in the
ortho position relative to each amino group have at least one
alkyl radical having 1 to 3 carbon atoms in bonded form, or
mixtures of such aromatic alkyl substituted diamines, and diols
and/or triols.
Blowing agents (d) that can be used according to this
invention include low boiling point cycloalkanes having 4 to 8
carbon atoms, more preferably 5 to 6 carbon atoms in the
molecule and most preferably linear or branched alkanes having
4 to 8 carbon atoms, more preferably 5 to 7 carbon atoms in the
molecule. Typical cycloaliphatic hydrocarbons are, for
example: cyclobutane, cyclopentane, cycloheptane, cyclooctane,
and more preferably cyclohexane. Most preferably used are
aliphatic hydrocarbons, such as for example: butane, n- and
isopentane, n- and isohexane, n- and isoheptane, and n- and
isooctane. Having been successfully proven and therefore most
preferably used are isopentane, more particularly n-pentane and
mixtures of pentanes.
The (cyclo)aliphatic alkanes used in the present
invention are employed individually or in the form of mixtures
of two or more blowing agents. Efficaciously, the (cyclo)ali-
phatic alkanes are used in a quantity of from 0.5 to 10 weight
percent, more preferably 1 to 7 weight percent based on the
-23-
2QQ~019
weight of components (a), (b) and optionally (c), whereby in
the preparation of cellular elastomers quantities of from 1 to
4 weight percent based on (a) through (c) result in products
having satisfactory mechanical properties.
In addition to the blowing agents (d) used according
to the invention, water is also suitable as a blowing agent
which reacts with the organic, optionally modified, polyiso-
cyanates (a) to form carbon dioxide and urea groups and
accordingly the compressive strength of the finished products
are influenced. Since the water normally contained in poly-
ester and polyether polyols as a byproduct is generally
sufficient, often no additional water is necessary. However,
if additional water must be incorporated into the polyurethane
formulation, then conventionally one uses from 0.05 to 2 weight
percent, more preferably 0.1 to 1 weight percent based on the
total of starting components (a) through (c).
Suitable catalysts (e) for producing the molded
articles having a compressed peripheral zone and a cellular
core include especially compounds that greatly accelerate the
reaction of the hydroxyl group containing compounds of com-
ponent (b) and optionally (c) with the organic optionally
modified polyisocyanates (a). Examples include organic metal
compounds, preferably organic tin compounds such as tin(II)
salts of organic carboxylic acids, e.g., tin(II) acetate,
-24-
ZQ~(~Ol9
tin(II) dioctoate, tin(II) ethylhexoate and tin(II) laurate, as
well as the dialkyltin(IV) salts of organic carboxylic acids
e.g., dibutyltin diacetate. The organic metal compounds are
used alone or preferably in combination with strong basic
amines. Examples include amines such as 2,3-dimethyl-3,4,5,6-
tetrahydropyrimidine, tertiary amines such as triethylamine,
tributylamine, dimethylbenzylamine, N-methylmorpholine, N-
ethylmorpholine, N-cyclohexylmorpholine, N,N,N',N'-tetra-
methylethylenediamine, N,N,N',N'-tetramethylbutanediamine,
pentamethyldiethylenetriamine, tetramethyldiaminoethyl ester,
bis~dimethylaminopropyl) urea, dimethylpiperazine, 1,2-di-
methylimidazole, l-aza-bicyclo-[3.3.0]octane and preferably
1,4-diaza-bicyclo[2.2.2]octane and alkanolamine compounds such
as triethanolamine, triisopropanolamine, N-methyl- and N-
ethyldiethanolamine and dimethylethanolamine.
Suitable catalysts when using a large polyisocyanate
excess also include tris(dialkylamino)-s-hexahydrotriazines,
especially tris(N,N-dimethylaminopropyl)-s-hexahydrotriazine,
tetraalkylammonium hydroxides such as tetramethylammonium
hydroxide, alkali hydroxides such as sodium hydroxide and
alkali alcoholates such as sodium methylate and potassium
isopropylate as well as alkali salts of long-chain fatty acids
with 10 to 20 carbons and optionally OH pendent groups. 0.001
to 5 weight percent, especially 0.05 to 2 weight percent, of
-25-
- - -
o~9
catalyst or catalyst combination based on the weight of
component (b) is preferred.
Optionally other additives and/or auxiliaries (f) may
be incorporated into the reaction mixture to produce the molded
articles. Examples include surface active substances, foam
stabilizers, cell regulators, fillers, dyes, pigments, flame
retardants, hydrolysis preventing agents, fungistatic and
bacteriostatic agents.
Examples of surface active substances include
compounds that support the homogenization of the starting
materials and are optionally also suitable for regulating cell
structure. Examples include emulsifiers such as the sodium
salts of castor oil sulfates or of fatty acids as well as salts
of fatty acids with amines, e.g., diethanolamine oleate,
diethanolamine stearate, diethanolamine ricinoleate, salts of
sulfonic acids, e.g., alkali or ammonium salts of dodecyl-
benzenesulfonic acid or dinaphthylmethanedisulfonic acid and
ricinoleic acid; foam stabilizers such as siloxane-oxyalkylene
copolymers and other organopolysiloxanes, ethoxylated alkyl-
phenols, ethoxylated fatty alcohols, paraffin oils, castor oil
and ricinoleic acid esters, Turkey red oil and peanut oil as
well as cell regulators such as paraffins, fatty alcohols and
dimethyl-polysiloxanes. Furthermor-e, the oligomeric acrylates
with polyoxyalkylene and fluoroalkane side groups are also
-26-
2 ~
suitable for improving the emulsifying effect, the cell
structure and/or for stabilizing the foam. These surface-
active substances are generally used in amounts of 0.01 to 5
parts by weight based on 100 parts by weight of component (b).
Typical release agents are for example: reaction
products of fatty acid esters with polyisocyanates, salts from
amino group containing polysiloxanes and fatty acids, salts of
unsaturated or saturated ~cyclo)aliphatic carboxylic acids
having at least 8 carbon atoms and tertiary amines as well as
most preferably internal release agents, such as for example,
carboxylic acid esters and/or amides prepared by the esterifi-
cation or amination of a mixture of montanic acid and at least
one aliphatic carboxylic acid having at least 10 carbon atoms
with at least difunctional alkanolamines, polyols and/or
polyamines having molecular weights of from 60 to 400 (European
Patent 153 639), or mixtures of organic amines, metal salts of
a steric acid and organic mono- and/or dicarboxylic acids or
their anhydrides (Federal Republic of Germany 36 07 447).
Fillers, especially reinforcing fillers, are under-
stood to refer to the known conventional organic and inorganic
fillers, reinforcing agents, weighting agents, agents to
improve abrasion properties in paints, coatings agents, etc.
Specific examples include inorganic fillers, such as silicate
minerals, such as layer silicates; e.g. antigorite, serpentine,
-27-
2¢;~019
hornblendes, amphiboles, chrysotile, talc; metal oxides such as
kaolin, aluminum oxides, aluminum silicate, titanium oxides and
iron oxides, metal salts such as chalk, heavy spar; and
inorganic pigments such as cadmium sulfide, zinc sulfide as
well as glass, etc. Examples of organic fillers include carbon
black, melamine, colophony, cyclopentadienyl resins and graft
polymers.
The organic and inorganic fillers may be used
individually or as mixtures and are advantageously incorporated
into the reaction mixture in amounts of 0.5 to 50 weight
percent, preferably 1 to 40 weight percent, based on the weight
of components (a) to (c).
Suitable flame retardants include, for example,
tricresyl phosphate, tris-2-chloroethyl phosphate, tris-
chloropropyl phosphate, tris-2,3-dibromopropyl phosphate,
tris(l,3-dichloropropyl)phosphate and tetrakis-(2-chloroethyl)-
ethylene diphosphate.
In addition to the aforementioned halogen substituted
phosphates, inorganic flame retardants may also be used such as
red phosphorus, aluminum oxide hydrate, antimony trioxide,
arsenic oxide, aluminum polyphosphate and calcium sulfate.or
cyanuric acid derivatives such as melamine or mixtures of at
least two flame retardants, such as for example, ammonium
polyphosphates and melamine, plus optionally cornstarch for
-28-
2Q~C~0~9
making the polymerization polyaddition products flame resist-
ant. In general, it has proven expedient to use 5 to 50 parts
by weight, preferably 5 to 25 parts by weight, of the afore-
mentioned flame retardants for each 100 parts by weight of
components (a~ through (c).
Details regarding the aforementioned other conven-
tional additives and auxiliaries can be obtained from the
technical literature, e.g., the monograph by J.D. Sauders and
K.C. Frisch "High Polymers," volume XVI, Polyurethanes, parts 1
and 2, Interscience Publishers, 1962 and 1964, or Plastics
Handbook, Polyurethanes, volume VII, Carl Hanser Publishers,
Munich, Vienna, 1st and 2nd editions, 1966 and 1983.
To produce the molded articles the organic poly-
isocyanates (a), higher molecular weight compounds with at
least two reactive hydrogens (b) and optional chain extenders
and/or crosslinking agents (c) are reacted in amounts such that
the equivalent ratio of NCO groups of polyisocyanates la) to
the total reactive hydrogens of component (b) and optionally
(c) amounts to 1:0.85-1.25, preferably 1:0.95-1.15. If the
molded articles contain at least some isocyanurate groups in
bonded form then conventionally a ratio of NCO groups of
polyisocyanates (a) to the total reactive hydrogens of com-
ponent (b) and optionally (c) will be from 1.5-60:1, preferably
1.5-8:1.
-29-
2C(~G019
Molded articles, especially flexible elastic integral
skin foams and cellular elastomer molded articles are prepared
employing a prepolymer process or preferably a one shot process
with the help of low pressure technology or more preferably
high pressure reaction injection molding technology in closed,
efficaciously heated molds, for example, metal molds made from
aluminum, cast iron or steel, or molds made of fiber reinforced
polyester compositions or epoxied compositions. Examples of
these process variations are described by Piechota and Rohr in
Integral Skin Foams, Carl-Hanser Publishers, Munich, Vienna,
1975; D.J. Prepelka and J.L. Wharton in Journal of Cellular
Plastics, March/April, 1975, pages 87-98; U. Knipp in Journal
of Cellular Plastics, March/April, 1973, pages 76-84; and in
the Plastics Handbook, volume 7, Polyurethanes, 2nd ed., 1983,
pages 333 ff.
It is proven to be most beneficial to work according
to a two component process and to incorporate starting com-
ponents (b), (d), (e) and optionally (c) and (f) into component
(A) and to use organic polyisocyanates, modified polyiso-
cyanates (a) or mixtures of the aforesaid polyisocyanates as
the ~B) component optionally including blowing agent (d).
The starting components are mixed together at a
temperature of from 15 to 90~C, more preferably 20 to 35~C and
injected into the closed mold optionally under increased
-30-
z~ 9
pressure. Mixing can be done mechanically using a stirrer or
using a stirrer screw or even under an elevated pressure in a
so-called countercurrent injection process. The mold tempera-
ture is normally 20 to 90~C, more preferably 30 to 60~C and
most preferably 45 to 50~C.
The preparation of the out-, mid-, or comfort shoe
soles, for example, employs a one shot process with the help of
high pressure technology. The preparation of dual density shoe
soles is described for example, in Schuh-Technik + abc 10
(1980), pages 822 ff. In the preparation of the aforesaid,
first the reaction mixture is injected into the mold to form
the urethane and urea group containing out-soles. Following a
mold residency time of from 10 to 120 seconds, more preferably
20 to 90 seconds the out-sole can be demolded, or when using a
shoe mold having a swiveling double last stand adapter this may
be rotated by 180~ to prepare the mid- or comfort sole follow-
ing which the mold is reclosed. The reaction mixture for
preparing the mid- or comfort sole is then injected while the
out-sole has sufficient green strength but before it is
completely cured. Generally, the injection is done at 20 to
100 seconds, more preferably 30 to 90 seconds after completion
of the injection process for forming the out-sole. Normally
one can dispense with the additional use of adhesives for
bonding the out-, mid-, or comfort soles.
-31-
2QO(~9
The quantity of reaction mixture injected into the
mold is measured so that the resulting integral skin foam
molded article has a density of 0.08 to 1.2 g/cm3, whereby
micro-cellular elastomer molded articles preferably have a
density of 0.7 to 1.2 g/cm3, more preferably 0.8 to 1.0 g/cm3;
the rigid and semi-rigid integral skin molded articles prefer-
ably have a density of 0.2 to 0.8 g/cm3, most preferably 0.35
to 0.8 g/cm3; the flexible elastic integral skin foam molded
articles have a density of from 0.08 to 0.7 g/cm3, more
preferably 0.12 to 0.6 g/cm3; and the shoe soles have a density
of from 0.4 to 1.0 g/cm3, whereby the out-soles preferably have
a density of 0.8 to 1.0 g/cm3, or higher; and the mid- or
comfort soles most preferably have a density of from 0.45 to
0.65 g/cm3. The degree of compression in the preparation of
molded articles having a compressed peripheral zone and a
cellular core lies in a range of from 1.1 to 8.5, more prefer-
ably 2 to 7 whereby for elastic flexible integral skin foams
and mid, or comfort soles the degree of compression is from 2.4
to 4.5 and for rigid integral skin foams and out-soles the
degree of compression is preferably from 3 to 7.
If the molded articles prepared according to the
present invention are not used as shoe soles then the micro-
cellular elastomer molded articles may be suited for use in the
automobile industry, for example, as bumper coverings, impact
-32-
20~ 9
protection moldings and body parts such as, drip moldings,
fenders, spoilers and wheel extensions, as well as engineering
housing components and rollers. The integral skin foams are
used for example, as arm rests, head rests, safety coverings in
the interior of automobiles and as motorcycle and bicycle
saddles and finally as coverings for composite foams.
The parts cited in the following examples refer to
parts by weight.
Example 1
A Component:
A mixture comprising:
70 parts by weight of a polyoxypropylene (75 weight
percent) polyoxyethylene (25 weight
percent) glycol having a hydroxyl
number of 23 prepared while using
ethylene glycol as an initiator
molecule;
18 parts by weight of a polyoxypropylene (75 weight
percent) polyoxyethylene (25 weight
percent) triol having a hydroxyl number
of 35 prepared while using glycerin as
an initiator molecule;
10.5 parts by weight of 1,4-butanediol;
1.0 parts by weight of a foam stabilizer based on a
silicone (DC 193 from Dow Corning);
0.5 parts by weight of triethylene diamine;
0.02 parts by weight of dibutyltin dilaurate; and
1.95 parts by weight n-pentane.
-33-
~Q~3~0~9
B Component:
A urethane group-containing polyisocyanate mixture
having a NCO content of 23 weight percent prepared by reacting
89 parts by weight of 4,4'-diphenylmethane diisocyanate with 11
parts by weight of dipropylene glycol.
100 parts by weight of the A component and 52 parts
by weight of B component were intensively mixed together at
23~C and then the reaction mixture was placed in a plaque
shaped aluminum mold heated to 50~C having the dimensions 20 cm
x 20 cm x 1 cm in such a quantity so that following foaming and
curing in the closed mold the integral skin foam plaque had a
total density of 0.6 g/cm3.
Obtained was a molded plaque having a pronounced
peripheral zone and a smooth surface which had the following
mechanical properties:
Tensile strength according to DIN 53 504 lN/mm2]: 5.5
Percentage elongation at break according to DIN 53 504 [%]: 450
Hardness according to DIN 53 505 [Shore A~: 70
Abrasion according to DIN 53 516 [mg]: 140
Comparison Example I:
The same procedure ùsed in example 1 was followed,
however, in place of the 1.95 parts by weight of n-pentane 5.5
parts by weight of trichlorofluoromethane was used.
-34-
20~(~0~9
The resulting molded plaque had a smooth surface and
the following mechanical properties:
Tensile strength according to DIN 53 504 [N/mm21: 5.3
Percentage elongation at break according to DIN 53 504 [%~: 440
Hardness according to DIN 53 505 [Shore A]: 72
Abrasion according to DIN 53 516 [mg]: 135
Example 2
A component
A mixture comprising:
42 parts by weight of a polyoxypropylene (75 weight
percent) polyoxyethylene ~25 weight
percent) glycol having a hydroxyl
number of 23 prepared while using
ethylene glycol as an initiator
molecule;
40 parts by weight of a polyoxypropylene (75 weight
percent) polyoxyethylene (25 weight
percent) triol having a hydroxyl number
of 35 prepared while using glycerin as
an initiator molecule;
5 parts by weight of ethylene glycol;
0.3 parts by weight of triethylene diamine; and
7.0 parts by weight n-pentane.
B Component:
A urethane group-containing polyisocyanate mixture
having an NCO content of 28 weight percent prepared by par-
tially reacting a mixture of diphenylmethane diisocyanates and
;~Q(~(~Ol9
polyphenyl polymethylene polyisocyanates with dipropylene
glycol.
100 parts by weight of the A component and 30 parts
by weight of the B component were intensively mixed together at
23~C and then the reaction mixture was placed in an aluminum
mold heated to 50~C having the shape of an automobile head rest
in such a quantity so that after foaming and curing the
reaction mixture in the closed mold the integral skin headrest
had a total density of 0.3 g/cm3.
Comparison Example II
15 parts by weight of trichlorofluoromethane had to
be used in place of 7 parts by weight of n-pentane to obtain a
head rest having an equal density and essentially the same
mechanical properties while utilizing the starting materials
described in example 2.
Example 3
Two high pressure units of the type Desma PSA 74 were
used to prepare dual density shoe soles. The shoe mold heated
to 50~C was equipped with a swiveling double last stand
adapter. The mold volume for the out-sole was 80 cm3 and that
of the mid-sole was 200 cm3. Using the first Desma PSA 74 high
pressure unit the first reaction mixture was injected to
-36-
2~ )19
prepare the out-sole. Following 60 and/or 90 seconds the mold
was opened by grasping the double last stand adapter which was
then rotated by 180~ so that the second last came to rest over
the mold. The second last was then lowered onto the mold, and
the mold was closed from above. The reaction mixture for
preparing the mid-sole was injected in such a quantity so that
its density was 0.45 g/cm3. The dual density shoe sole was
demolded after a total of 2 minutes. After several days of
storage at room temperature the bond strength of the shoe sole
bond was determined by a tensile test. Here the boundary
surface between the out-sole and mid-sole were cut and then
both soles were torn apart from one another. An adhesion break
occurred when separating the out-sole and mid-sole at their
boundary surface. In the cohesion break cracking occurred in
the polyurethane, polyurea-elastomer.
A component
A mixture comprising:
~2.95 parts by weight of a polyoxypropylene-polyoxyethylene
glycol having a hydroxyl number of 29
prepared by the addition polymerization
of 1,2-propylene oxide and subsequently
ethyleneoxide on propylene glycol;
6.0 parts by weight 2,4-dimethyl-6-t-butylphenylene-1,3-
diamine;
1.0 parts by weight of a 33 weight percent solution of
diazabicyclooctane in dipropylene
glycol; and
2C~ 9
0.05 parts by weight of dibutyltin dilaurate; and
B Component:
A urethane group-containing polyisocyanate mixture
having an NCO content of 23 weight percent prepared by par-
tially reacting 4,4'-diphenylmethane diisocyanate with dipro-
pylene glycol.
100 parts by weight of the A component and 23.1 parts
by weight of the B component (corresponding to an NCO index of
1.05) were reacted at 30~C employing a RIM process on a high
pressure machine of the type Desma PSA 74 into a non-cellular
out-sole having a density of 1.1 g/cm3.
After 60 seconds the out-sole was partially demolded
by elevating the out-sole mold of the double last, swiveling
the double last stand adapter by 180~ and then reclosing the
mold with the mid-sole mold. After another 15 seconds the
reaction mixture for preparing the mid-sole was injected. It
(the A component) was a mixture comprising:
~3.55 parts by weight of the aforesaid polyoxypropylene-
polyoxyethylene glycol having a
hydroxyl number of 29 prepared by the
addition polymerization 1,2-propylene
oxide and subsequently ethylene oxide
on propylene glycol;
~.0 parts by weight of 2,4-dimethyl-6-t-butyl-phenylene-
1,3-diamine;
-38-
z~ 9
1.0 parts by weight of a 33 weight percent solution of
diazabicyclooctane in dipropylene
glycol;
U.05 parts by weight of dibutyltin dilaurate;
.1 part by weight of a silicone oil (DC 193 from Dow
Corning);
0.3 parts by weight of water;
2.0 parts by weight of a mixture of n-pentane and isopen-
tane in a weight ratio of 50:50; and
30.4 parts by weight of a urethane group-containing polymer-
ization mixture having an NCO content
of 23 weight percent (B component),
prepared by partially reacting 4,4'-
diphenylmethane with dipropylene
glycol.
The reaction mixture (isocyanate index was 1.05) was
injected at a temperature of 30~C into the mold in such a
quantity so that the mid-sole had a density of 0.45 g/cm3. The
dual density shoe sole prepared in this fashion was demolded
after two minutes.
After several days of storage the adhesion of the
bond was measured using 2 cm wide strips with the help of a
tensile testing machine. In all of the samples the propagation
of the tearing occurred in the polyurethane polyurea elastomer
(cohesion break) and not at the surface of the out-sole and
mid-sole. The maximum tear propagation strength values were at
5.4 N/mm.
-39-
2~Q019
Example 4
A Component
A mixture comprising:
55 parts by weight of a polyoxypropylene triol initiated
with trimethylolpropane having a
hydroxyl number of 550;
5 parts by weight of a polyoxypropylenepolyol initiated
with sucrose having a hydroxyl number
of 400;
15 parts by weight of a polyoxypropylene (75 weight
percent) polyoxyethylene (25 weight
percent) triol having a hydroxyl number
of 35 prepared while using glycerin as
an initiator molecule;
9 parts by weight of glycerin;
~.8 parts by weight of a foam stabilizer based on a
silicone (Tegostab~ T 8418 from
Goldschmidt AG, Essen, Federal Republic
of Germany);
2.0 parts by weight of N,N-dimethylcyclohexylamine;
0.25 parts by weight of water; and
5.5 parts by weight of tri-(2-chloromethyl)phosphate.
B Component:
A mixture of diphenylmethane diisocyanates and
polyphenylpolymethylene polyisocyanates having an NCO content
of 31 weight percent.
3.2 parts by weight of n-pentane were first incorpo-
rated into 93.5 parts by weight of the A component and then 130
parts by weight of the B component was intensively added to the
resulting mixture.
-40-
2C~ )19
The reaction mixture was filled into an open mold and
allowed to foam there. A polyurethane rigid foam was obtained
having a density (free rise foam) of 110 9/1.
In addition the reaction mixture was placed in an
aluminum mold heated to 50~C whose internal dimensions were 20
cm x 20 cm x 1 cm in such a quantity so that after foaming in
the closed mold and curing a molded plaque resulted having a
density of 600 9/l.
A molded plaque made of polyurethane rigid integral
skin foam was obtained having a very well pronounced external
skin.
Comparison III
The procedure of example 4 was followed, however, 6.5
parts by weight of trichlorofluoromethane were used as a
blowing agent in place of the 3.2 parts by weight of n-pentane.
Here we obtained: a polyurethane rigid foam having a
density (free rise foam) of 110 g/l and a polyurethane rigid
integral skin foam molded plaque having a density of 600 9/1
which likewise had a very well defined external skin.
-41-
