Note: Descriptions are shown in the official language in which they were submitted.
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LeA 28866-U~
PROCESS FOR THE PREPAR~TION OF MQLDED ~RO~DUCTS
BACKG~OUND OF THE INVENTIQN
The invention relates to a novel process for the
preparation of molded products based on polyurethanes
containing urea groups via the reaction injection molding
technique. The process uses selected starting materials which
are distinguished by their excellent potential for reuse in the
compression molding process while retaining their mechanical
properties.
The potential for reuse of used plastics is increasingly
becoming a precondition in plastics applications of any kind.
It is already known that molded products prepared via the
reaction injection molding technique from polyurethanes
containing urea groups, optionally following granulation, may
be deformed bycompressionmolding and thus directed and adapted
to a new field of application. However, the processes wh;ch
have previously been disclosed (e.g. German Offenlegungs-
schrift 2,733,755 or German Offenlegungsschrift 3,802,427) have
the disadvantage that the molded products deformed via
com~ ion molding exhibit mechanical values which are
considerably inferior than those of the primary plastics.
Therefore, it was the objective of the invention to
discover a novel process for the preparation of molded products
based on polyurethanes containing urea groups using the
reaction injection molding technique, wherein the process, as a
result of the selection of specific starting materials used,
yields plastics which may be deformed via thecompressionmolding
method without any appreciable loss of mechanical properties.
This would enable the preparation of secondary plastics by
compression molding from either the corresponding primary
plastics, or the waste products resulting from the preparation
of primary plastics. These secondary plastics have mechanical
LeA 28 866-US
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properties which are comparable to those of the primary
plastics.
The term primary plastics in this context is understood to
mean the plastics prepared from the monomer starting materials
via the reaction injection molding technique in closed molds.
Secondary plastics are those obtained from primary plastics or
from waste products resulting from the preparation of the
primary plastics, by compressionmolding~ i.e. by thermal
deformation under pressure.
o DESCRIPTION OF THE INVENTION
The subject of the invention relates to a process for the
preparation of molded products of polyurethanes containing urea
groups having a density of from 0.8 to 1.4 g/cm3, via the
one-stage or two-stage reaction injection molding technique.
The process comprises reacting
a) a polyisocyanate component comprising a
polyisocyanate or polyisocyanate blend of the
diphenylmethane series, having an average NCO
functionality of from 2.0 to 2.2, and having a NCO
content of from 8 to 32% by weight, preferably from
18 to 26% by weight;
b) a polyol component comprising at least one polyether
polyol having an average hydroxyl functionality of
from 2.5 to 3.5, and an average hydroxyl number of
from 35 to 50 mg KOH/g, wherein each polyether polyol
contains from 5 to 19% by weight, calculated on the
weight of the polyether polyol, of ethylene oxide
blocks grafted in the end position;
c) from 5 to 100% by weight, calculated on the weight of
component b), of a diamine component comprising
1-methyl-3,5-diethyl-2,4-diaminobenzene, or
industrial mixtures thereof, with 1-methyl-3,5-
diethyl-2,6-diaminobenzene;
d) catalysts which ar~ capable of catalyzing the NCO/OH
addition reaction; and
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e) a total of frorn 0.1 to 10% by weight, calculated on
the weight of component b), of addit;ves compr;s;ng
el) aliphatic polyether amines havi~g molecular
weights of from 200 to 800,
e2) ethylenediamine propoxylation products having a
hydroxyl number of from 200 to 1200 mg KOH/g,
e3) esterification products of 1,6-hexanediol with
ricinoleic acid, or
e4~ mixtures thereof;
in a closed mold, while maintaining an NCO index of from
70 to 140.
The polyisocyanate component a) to be used in the process
acsording to the invention comprises polyisocyanates or
polyisocyanate blends of the diphenylmethane series which have
a NCO content of from 8 to 32% by weight, preferably from 18 to
26% by weight, and an average NCO functionality of from 2.0 to
2.2. In particularS 4,4'-diisocyanatodiphenylmethane, liquid
blends thereof with 2,4'-diisocyanatodiphenylmethane, and,
optionally, 2,2'-diisocyanatodiphenylmethane, and/or with
higher homologues thereof containing more than one isocyanate
group, and derivatives as obtained by the chemical modification
of such polyisocyanates and containing isocyanate groups are
considered suitable. Chemical modifications which are
particularly suitable are partial carbodiimidization of the
isocyanate groups of the polyisocyanates or polyisocyanate
blends, and partial urethanization sf the isocyanate groups of
the polyisocyanates or polyisocyanate blends. Partial
carbodiimidization is described, for example, in U.S. Patent
3,152,162, incorporated herein by reference, and partial
3o urethanization is described, for example, in German
Offenlegungsschrift 1,618,380, incorporated herein by
reference. Di;socyanates which have been prepared by the
reaction with polypropylene glycols having a molecular weight
of up to 700 while maintaininy a NCO/OH equivalent ratio of
from 3:1 to 10:1 are particularly preferred. Polyisocyanates
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or polyisocyanate blends of the diphenylmethane series which
are liquid at room temperature are preferably used ;n the
process according to the invention. It is also possible to use
polyisocyanates of the diphenylmethane series which are solid
at room temperature, especially solid 4,4'-diisocyanato-
diphenylmethane. Howev~r, prepolymers of the polyisocyanate
must be used in the process if polyisocyanates of the
diphenylmethane series which are solid at room temperature are
used.
The polyether polyol component b~ has an average hydroxyl
functionality of from 2.5 to ~.5, and an average hydroxyl
number of from 35 to 50 mg KOH~g. Component b~ comprises
exclusively polyether polyols which contain from 5 to l9~/o by
weight, calculated on the total weight of the polyether
polyols, of ethylene oxide blocks grafted in the end position.
It is also possible to use polyether polyols which meet this
condition and also contain fillers (e.g polymers or
polyaddition products) in dispersed form. Suitable polyether
polyols b) are described, for example, in U.S. Patent
4,218,543, incorporated herein by reference.
Aromatic diamines of the type described above are
considered suitable as component c). These diamines are
present in a quantity of from 5 to 100% by weight, preferably
from 10 to 35% by weight, calculated on the weight of
component b).
Component d) comprises catalysts which are known per se in
polyurethane chemistry. The known tin catalysts are especially
suitable. Suitable catalysts are described, for example, in
U.S. Patent 4,218,543, incorporated herein by reference. The
catalysts are generally used in quantities of from 0.01 to 10%
by weight, preferably from 0.05 to 1% by weight, calculated on
the weight of component b).
Additives e) which are particularly suitable are those of
the type previously described. It is essential that at least
one of the additives, el), e2), or e3), as described herein, be
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used in the process according tG the invention. Mixtures or
combinations of these additives may, of course, be used. The
total quantity of these additives is from 0.1 to 10% by weight,
calculated on the weight of component b).
In particular, the aliphatic polyether amines, component
el), are aminated polypropylene glycols with;n the molecular
weight range of from 200 to 800. These are ava;lable, for
example, from Texaco under the trade name Jeffamine.
The propoxylation products of ethylene diamine, component
e2), are, in particular, those compounds produced by the
addition of from 3 to 6 moles of propylene oxide to 1 mole of
ethylene diamine.
The reaction products of 1,6-hexanediol and ricinoleic
acid containing ester groups, component e3), are, in
particular, those which have an acid number of less than 5 and
a hydroxyl number of from 12.5 to 125. These compounds are
prepared and used as internal mold release agents according to
German Offenlegungsschrift 3,436,163, herein incorporated by
reference.
In addition, other auxiliary substances and additives e)
may also be used in addition to the aforementioned additives
el), e2), and e3), in the process according to the invention.
Suitable optional additives include, for example, milled glass
fiber or glass flakes. Quantities of up to 3Q% by weight7
preferably from 10 to 25% by weight, calculated on the total
weight of all starting materials a) through e)t of milled glass
fiber or glass flakes may be used as fillers or reinforcing
agents in the process according to the invention.
The process may, optionally, contain additional auxiliary
substances and addit;ves ;nclud;ng, for example, internal mold
release agents in quantities of up to 5% by weight, calculated
on the weight of component b). One example of a suitable
internal mold release agent is zinc stearate.
The process according to the invention is carried out in
accordance with the known principles of reaction injection
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molding while maintainin~ a NC0 index of from 70 to 140,
preferably from 90 to 125. The NC0 index is the quotient of the
number of NC0 groups present in the reaction mixture divided by
the number of groups capable of reacting with NC0 groups
present ;n the reaction mixture, multiplied by 100. Also, it
;s poss;ble to use either the one-shot process or the two-shot
process (;.e. semi-prepolymer principle).
When the one-shot process is used, components b) to e) are
combined to form a polyol component, which is then reacted with
the polyisocyanate component a) via the reaction injection
mold;ng process, ;n accordance w;th the teaching of U.S. Patent
4,218,543.
When the two-shot process is used, at least some of
component b) (e.g. 50, 90 or 100 % by weight of component b)),
the polyol, is reacted with all of component a), the
poly;socyanate, to form a NC0 semi-prepolymer. This NC0
semi-prepolymer is then processed with a mixture of the
remaining starting materials and additives in accordance with
the principle of reaction injection molding. This two-shot
method ;s described ;n princ;ple, for example, in German
Patentschrift 3,827,595.
The molded products obtained by the process according to
the invention are distinguished from those of the prior art in
that they largely retain their excellent mechanical properties
after they have undergone further processing or further
deformat;on by the extrusion molding method.
All quantitative data in the Examples which follow relate
respectively to % by weight and parts by weight.
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EXAMPLES
Example 1
Preparation of a polyurethane urea component of the prior
art (i.e. Comparative Example, not according to the invention).
lA: polvol comDonent
70.12 pàrts of a polyether polyol hav;ng an OH number of 28,
and prepared by the propoxylation of trimethylol-propane,
followed by the ethoxylation of the propoxylation product
(weight ratio of PO:EO = 86.5:13.5),
23.7 parts of a blend of 65% by weight of 2,4-diamino-3,5-
diethylbenzene and 35% by weight of 2,6-diamino-3,5-
diethylbenzene,
2 parts of a reaction product of ricinoleic acid and
1,6-hexanediol, having an OH number of 35 and containing
ester groups,
1 part of triethylenediamine,
0.18 parts of dimethyl tin dilaurate,
0.2 parts of dibutyl tin dilaurate,
0.9 parts of N,N-(bis-3-dimethylamino-propyl) amine, and
1.8 parts of zinc stearate.
lB: isocvanate component (NCO index 110)
60 parts of a semi-prepolymer having an NCO content of 24.5%
by weight, and a viscosity of 500 +/- 100 mPa.s (23C),
and prepared by reacting a blend of 90% by weight of
4,4'-diisocyanatodiphenylmethane and 10% by weight of
2,4'-diisocyanatodiphenylmethane, with polypropyleneglycol
having an OH number of 515.
Preparation of the RIM components (l-I)
The polyol component lA was heated to 45C, the isocyanate
component lB was heated to 40C, and both were injected via the
reaction injection molding (RIM) process into a tool tempered
to 65C having the internal walls coated with an external mold
release agent. The plate mold dimensions were380 x 200 x 3 mm.
The specific tool used was a 12 l Rimdomat, manufactured by
Hennecke, Birlinghoven. The setting time in the mold was 30
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sec, and the pieces were tempered at 120C for 45 min. After
storing the molded products (1-I) for 14 days at 20C, the
mechanical properties were determined (see Table 1).
Preparation of_the compression molded comp~nents (1-11)
The tempered molded components (l-I) were comminuted in a
commercially available rotary cutter to form a granulate having
particles in which the maximum diameter s ke is 4 mm. ~his
granulate was heated for 15 min. in a drying cabinet with air
at 180C, and then introduced into a steel she~edge
mold which was preheated to 185C, and mounted in a hydraulic
press manufactured by Schwabenthan, D-1000 Berlin, model number
300 S.
After charging, the mold was closed and
subjected to a load of approx. 300 bar mold pressure (i.e.
specific internal mold pressure) at a continuous molding
temperature of 185C. After a pressing time of 3 min., the
mold was opened, and the compressedcomponentw~demoldedwhile
hot, and then cooled outside the press. After cooling the
extrusion molded components (1-II) to 20C, the mechanical
properties were determined (see Table 1).
Example 2
Preparation of a polyurethane urea component (i.e.
according to the invention)
2A: Polyol component
70.12 parts of a polyether polyol having an OH number of 44
which was prepared by the propoxylation of trimethylol-
propane, followed by the ethoxylation of the propoxylation
product (weight rat;o of PO:EO - 86.5:13.5),
23.7 parts of a blend of 65% by weight of 2,4-diamino-3,5-
diethylbenzene, and 35% by weight of 2~6-diamino-3,5-
diethylbenzene,
2 parts of the reaction product of ricinoleic acid and
1,6-hexanediol, having an OH number of 35 and containing
ester groups,
1 part of triethylenediamine,
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g
0.18 parts of dimethyl tin dilaurate,
0.2 parts of dibutyl tin dilaurate,
0.9 parts of N,N-(bis-3-dimethylamino-propyl) amine, and
1.8 parts of zinc stearate.
2B: isocYanate component (NCO index 110)
63.6 parts of a semi-prepolymer having an NCO content of 24.5%,
and a viscosity SOO +/- 100 mPa.s (23C~, which was
prepared by the reaction of a blend of 90% by weight of
4,4'-diisocyanatodiphenylmethane and 10% by weight of
2,4'-diisocyanatodiphenylmethane, with polypropylene-
glycol having an OH number of 515.
Preparation of the RIM components (2-I)
The polyol component 2A was heated to 45C, the isocyanate
component 2B was heated to 40C, and both were injected via the
reaction injection molding (RIM) process into a tool tempered
to 65C having the internal walls coated with an external mold
release agent. The plate mold dimensions were 380 x 200 x 3 mm.
~he specific tool used was a 12 l Rimdomat, manufactured by
Hennecke, Birlinghoven. The setting time in the mold was 30
sec, and the pieces were tempered at 120~C for 45 min. After
storing the molded products (2-I) for 14 days at 20C, the
mechanical properties were determined (see Table 1).
Preparation of the compression molded components (2-II)
The tempered molded components (2-I) were comminuted in a
commercially available rotary cutter to form a granulate having
particles in which the maximum diameter si~e is 4 mm. This
granulate was heated for 15 min. in a drying cabinet with air
at 180C, and then introduced into a steel she~edge
mold which was preheated to 185C, and mounted in a hydraulic
press manufactured by Schwabenthan, D-1000 Berlin, model number
300 S.
After charging, the mold was closed and
subjected to a load of approx. 300 bar mold pressure (i.e.
specific internal mold pressure) at a continuous molding
3~ temperature of 185C. After a pressing time of 3 min., the
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mold was opened, and the compressed cornponent w~ demolded w~le
hot, and then cooled outside the press. After cooling the
compressionmolded components (2-II) to 20C, the mechanical
properties were determined (see Table 1).
Example 3
Preparation of a polyurethane urea component (i.e.
according to the invention)
This Example demonstrates that it is also possible to use
smaller quantities of catalyst.
3A: polvol com~onent
69.9 parts of a polyether polyol having an OH number of 44,
which is prepared by propoxylating trimethylolpropane,
followed by ethoxylation of the propoxylation product
(weight ratio of PO:EO = 86.5:13.5),
23.7 parts of a blend of 65% by weight of 2,4-diamino-3,5-
diethylbenzene, and 35% by weight of 2,6-diamino-3,5-
diethylbenzene,
2 parts of the reaction product of ricinoleic acid and
1,6-hexanediol, having an OH number of 35 and containing
ester groups,
0.7 parts of triethylenediamine,
Q.l parts of dimethyl tin dilaurate,
1.8 parts of N,N-(Bis-3-dimethylamino-propyl) amine, and
1.8 parts of zinc stearate.
3B: isocvanate component (NCO index 110)
63.9 parts of a semi-prepolymer having an NCO content of 24.5%
and a viscosity of 500 +/- 100 mPa.s (23C), which was
prepared by the reaction of a blend of 90% by weight of
4,4'-diisocyanatodiphenylmethane and 10% by weight of
2,4'-diisocyanatodiphenylmethane, with polypropyleneglycol
having an OH number of 515.
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Preparation of the RIM components (3-Il
The polyol component 3A was heated to 45C, the isocyanate
component 3B was heated to 40C, and both were injected via the
reaction injection molding (RIM) process into a tool tempered
to 65C having the internal walls coated with an external mold
release agent. The plate mold dimensions were 380 x 200 x 3 mm.
The specific tool used was a 12 l Rimdomat, manufactured by
Hennecke, Birlinghoven. The setting time in the mold was 30
sec, and the pieces were tempered at 120C for 45 min. After
lo storing the molded products (3-I~ for 14 days at 20C, the
mechanical properties were determined (see Table 1).
Preparation_of the compression molded components (3-II)
The tempered molded components (3-I) were comminuted in a
commercially available rotary cutter to form a granulate having
particl~s in which the maximum diameter size is 4 mm. This
granulate was heated for 15 min. in a drying cabinet with air
at 180C, and then introduced into a steel shearedge
mold which was preheated to 185C, and mounted in a hydraulic
press manufactured by Schwabenthan, D-1000 Berlin, model number
300 S.
After charging, the mold was closed and
subjected to a load of approx. 300 bar mold pressure (i.e.
specific internal mold pressure) at a continuous molding
temperature of 185C. After a pressing time of 3 min., the
mold was opened, and the compressedcomponenlwasdemoldedw~le
hot, and then cooled outside the press. After cooling the
compressionmoldedcomponents (3-II) to 20C, the mechanical
properties were determined (see Table 1).
3o
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~able I shows that although both the RIM and the Compression
molded components were prepared using the same processing
conditions in all three (3) Examples, the RIM materials
prepared according to the present invention (i.e. Examples 2
and 3) retain their mechanical properties substantially better
following granulation and compression molding than a prior art
polyurethane urea material (i.e. Example 1).
Mo3848
