Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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POLYUR~THAN13 MOT nTr7~ COMPOSITIONS
This invention relates to soft thermoplastic poly-
urethane elastomer compositions with distinctly improved
demolding behavior based on thermoplastic polyurethanes
(TPU's), inorganic fillers and at least one special
plasticizer.
In EP 0 134 455, it is shown that TPU's with a
hardness of 60 to 80 Shore A can be obtained by using
phthalic acid dimethoxy ethyl ester, tricresyl phosphate
and/or diphenyl cresyl phosphate.
The present invention relates to very soft rubber-
like elastic and thermoplastically processable molding
compositions with distinctly improved demolding behavior
which contain
A) 15 to 90 parts by weight of a thermoplastic polyure-
thane produced from
1) organic diisocyanate,
2) mixtures of polypropylene oxide or polypropy-
lene/ethylene oxide with polyesters of alipha-
tic dicarboxylic acids with C2_6 diols with a
molecular weight of 500 to 5,000,
3) a chain-extending diol with a molecular weight
of 60 to 400,
B) 5 to 50 parts by weight of inorganic fillers and
C) 5 to 35 parts by weight of alkyl sulfonic acid
esters of phenol (DIN 7723: ASE) and/or benzyl butyl
phthalate (DIN 7723: BBP).
Component A) of the molding composition according to
the invention is a special thermoplastic polyurethane
elastomer known in principle. Thermoplastic polyurethane
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elastomers, generally referred to in short as TPU's, are
synthesized from polyols, i.e. polyethers or polyesters
of relatively high molecular weight, organic diisocyanate
and short-chain diols as chain-extending agent. Various
S production processes are known and are operated on an
industrial scale.
The TPU's used in accordance with the invention are
based on aliphatic, cycloaliphatic, araliphatic, hetero-
cyclic or aromatic diisocyanates of the type described,
for example, in Justus Liebigs Annalen der Chemie, 562,
pages 75-136. Examples of such diisocyanates are alipha-
tic diisocyanates, such as hexamethylene diisocyanate;
cycloaliphatic diisocyanates, such as isophorone diiso-
cyanate, l,4-cyclohexane diisocyanate, 1-methyl-2,4- and
lS -2,6-cyclohexane diisocyanate and the corresponding
isomer mixtures, 4,4'-, 2,4'- and 2,2'-dicyclohexyl
methane diisocyanate and the corresponding isomer mix-
tures; and aromatic diisocyanates, such as 2,4-tolylene
diisocyanate, mixtures of 2,4- and 2,6-tolylene diisocya-
nate, 4,4'-, 2,2'- and 2,2'-diphenyl methane diisocya-
nate, mixtures of 2,4'- and 4,4'-diphenyl methane diiso-
cyanate, urethane-modified liquid 4,4'- and/or 2,4'-
diphenyl methane diisocyanates, 4,4'-diisocyanatodiphenyl
ethane-(1,2)- and 1,5-naphthylene diisocyanate. 1,6-
Hexamethylene diisocyanate, isophorone diisocyanate,
dicyclohexyl methane diisocyanate, diphenyl methane
diisocyanate isomer mixtures containing more than 96% by
weight of 4,4'-diphenyl methane diisocyanate are prefer-
ably used, 4,4'-diphenyl methane diisocyanate and 1,5-
naphthylene diisocyanate being particularly preferred.
The diisocyanates mentioned may be used together
with a polyisocyanate in a quantity of up to 15% (based
on diisocyanate) but at most in such a quantity that an
uncrosslinked product is formed. Examples are triphenyl
methane-4,4,4"-diisocyanate and polyphenyl polymethylene
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polyisocyanates.
The TPU's according to the invention are based on
mixtures of polypropylene oxide or polypropylene/ethylene
oxide with polyesters of aliphatic dicarboxylic acids and
SC2_6 diols, more particularly butane-1,4-diol, with a
molecular weight of 500 to 5,000 as relatively long-chain
polyols.
The polyether polyols also have molecular weights of
500 to 5,000. Adipates are preferably used as the poly-
10esters.
Preferred chain-extending agents with molecular
weights of 60 to 400 are aliphatic diols cont~;n;ng 2 to
14 carbon atoms, such as for example ethanediol, hexane-
1,6-diol, diethylene glycol, dipropylene glycol and, more
15particularly, butane-1,4-diol. However, diesters of
terephthalic acid with glycols containing 2 to 4 carbon
atoms, such as for example terephthalic acid bis-ethylene
glycol or butane-1,4-diol, hydroxyalkylene ethers of
hydroquinone, such as l,4-di-(~-hydroxyethyl)-hydro-
20quinone for example, (cyclo)aliphatic diamines, such as
for example isophorone diamine, ethylene diamine, 1,2-
and 1,3-propylene diamine, N-methyl-1,3-propylene di-
amine, N,N'-dimethyl ethylene diamine, and aromatic
diamines, such as for example 2,4- and 2,6-tolylene
25diamine, 3,5-diethyl-2,4- and/or -2,6-tolylene diamine,
and primary ortho-di-, tri- and/or tetra-alkyl substitu-
ted 4,4'-diaminodiphenyl methanes. Mixtures of the
chain-extending agents mentioned above may also be used.
To produce the TPU's, the synthesis components may
30be reacted, optionally in the presence of catalysts,
auxiliaries and/or additives, in such quantities that the
equivalence ratio of NCO groups to the sum of the NCO-
reactive groups, particularly the OH groups, of the low
molecular weight diols and the polyols is 0.9:1 to 1.2:1
35and preferably 0.95:1 to 1.1:1.
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The production of TPU's is known per se and is
described, for example, in DE-A 2 302 564 or in GB
1,057,018.
Inorganic fillers B are, for example, calcium
carbonate, barium sulfate, silicon oxide, magnesium
oxide, antimony oxide or mixtures thereof. Particularly
preferred fillers B are calcium carbonate and barium
sulfate, optionally in conjunction with silicon dioxide,
for example in the form of silicas, a mixture of 15 to 35
parts by weight of calcium carbonate with 1 to 10 parts
by weight of silicon dioxide being particularly suitable.
Suitable plasticizers C are alkyl sulfonic acid
esters of phenol (ASE) and benzyl butyl phthalates (BBP)
and mixtures thereof.
Particularly suitable alkyl sulfonic acid esters of
phenol contain alkyl groups with 10 to 20 carbon atoms,
in many cases mixtures of different alkyl groups contain-
ing on average 10 to 14 carbon atoms.
The molding compositions according to the invention
may be produced by premixing the components in known
manner (A+B+C, for example in a high-speed mixer) and
compounding the resulting mixture in known units (knead-
ers, extruders).
The use of silicon dioxide as a filler in the
production of the compositions represents a particular
embodiment of the invention. A dry and meterable compo-
sition is obtained through the silicon dioxide, more
particularly in the form of silica.
In order continuously to produce the molding com-
positions, the individual components may be directly
introduced, i.e. without premixing, into the units
(extruders) mentioned above through suitable metering
units, the plasticizer preferably being introduced into
the already melted TPU or TPU/filler mixture.
The filler and the plasticizer may also be intro-
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duced during the production of the TPU, i.e. into the not
yet fully reacted reaction mixture.
The molding compositions according to the invention
are very soft (Shore A hardness 55 to 85) and, even with
a TPU content of only 50%, show mechanical properties
comparable with many soft PVC compounds and other thermo-
plastic elastomer compounds. By virtue of the excellent
crystallization capacity from compounding in the melt,
the virtual absence of tackiness in the mold and the low
shrinkage values of the moldings, articles produced from
the molding compositions according to the invention show
distinctly improved demolding behavior during thermoplas-
tic processing. Accordingly, they are particularly
suitable as alternative products to soft PVC compounds.
Accordingly, they are particularly suitable for the
production of flexible injection-molded articles and also
for blow-molded articles and extrudates.
Exam;~les
The following substances were used in the following
Examples:
TPU 1 = Polyether/ester urethane elastomer based on
50 parts by weight of polypropylene oxide
ether, MW approx. 2,000
50 parts by weight of polybutanediol adipate,
MW approx. 2,000
10.5 parts by weight of butane-1,4-diol
42 parts by weight of diphenyl methane diiso-
cyanate
TPU 2 = Polyester urethane elastomer based on
100 parts by weight of polybutanediol adipate,
MW approx. 2,000
10.5 parts by weight of butane-1,4-diol
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40 parts by weight of diphenyl methane diiso-
cyanate
TPU 3 = Polyether urethane elastomer based on
100 parts by weight of polytetramethylene oxide
ether, MW approx, 1,000
10 parts by weight of butane-1,4-diol
50 parts by weight of diphenyl methane
diisocyanate
Omyacarb 10 BG = Calcium carbonate of Omya
Aerosil 200 V = Silicon dioxide of Degussa AG
Mesamoll 2 = Alkyl sulfonic acid ester of phenol of
Bayer AG (DIN 7723: ASE)
Disflamoll TKP = Tricresyl phosphate of Bayer AG (DIN
7723: TCF)5 Vestinol AH = Dioctyl phthalate of Huls (DIN 7723:
DOP)
Unimoll BB = Benzyl butyl phthalate of Bayer AG (DIN
7723: BBP).
The crystallization capacity of the products is
determined by differential scanning calorimeter (DSC)
measurements.
The DSC measurements were carried out with a Perkin
Elmer DSC-7 as follows: the product is heated in nitrogen
from -70C to 260C at a rate of 20C/minute and then
cooled to -70C at a rate of 40C/minute.
The crystallization temperature in the cooling phase
(exothermic peak) is directly proportional to the crys-
tallization capacity.
Exam~les 1 to 7 according to the invention
The TPU component was mixed for 5 minutes at room
temperature in a commercial high-speed mixer with filler
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1 and filler 2 and the plasticizer in the quantities
shown in Table 1 below. The dry meterable mixture
obtained was then compounded in a twin-screw extruder,
the strands obtained were cooled in a water bath and then
granulated.
The dried granules were injection-molded to test
specimens at 195C. After heating for 15 h at 80C, the
properties listed in Table 2 were observed.
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Table 2 æ
Properties of the Examples according to the invention ~
o
Example Hardness Tensile Breaking Shrinkage Crystallization Remarks
No. Shore A strength elongation after temperature C
DIN 53505 (MPa) (%) heating from DSC
DIN 53504 (DIN 53504) (%)
1 69 9.9 602 1.2 92 Readily demoldable
2 71 7.5 580 0.8 95 Readily demoldable
3 64 9.1 713 1.4 95 Readily demoldable
4 73 8.4 452 1.2 87 Readily demoldable
82 6.4 522 0.8 84 Readily demoldable
6 67 8.1 602 1.6 87 Readily demoldable
7 70 5.7 495 1.2 81 Readily demoldable
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C rA~ison ExAm~les 8 to 15
Example 8
Pure TPU 1 is used in this Example. The data
determined are set out in Table 4.
Examples 9 to 11
The TPU components were mixed for around 24 hours at
room temperature in a tumble mixer with the plasticizer
component in the quantities and compositions shown in
Table 3. The granules thus plasticized were then proces-
sed as in the Examples according to the invention. The
characteristic data are shown in Table 4. During injec-
tion molding to test specimens, sticking of the test
specimens in the injection mold was observed.
Exam~les 12 to 15
The TPU component was mixed for about 5 minutes at
room temperature in a commercial high-speed mixer with
filler 1 and filler 2 and the plasticizer in the quanti-
ties and composition shown in Table 3. Compounding and
further processing to test specimens was carried out as
in Examples 1 to 7. The data determined are set out in
Table 4.
Table 3
~ ~ison Examples - composition O
~D
Example Parts TPU Parts Filler 1 Parts Filler 2 Parts PlaticizerNo.
8 100
9 75 1 25 Mesamoll 2
2 25 Disflamoll TKP
11 75 3 25 Disflamoll TKP
12 50 3 20 Omyacarb 10 BG 5 Aerosil 200 V 25 Mesamoll 2
13 50 2 20 Omyacarb 10 BG 5 Aerosil 200 V 25 Mesamoll 2 '~
14 50 1 20 Omyacarb 10 BG 5 Aerosil 200 V 25 Disflamoll TKP cn
1 20 Omyacarb 10 BG 5 Aerosil 200 V 25 Vestinol AH C~
C~
Table 4
comp~rison Examples - propQrties
r~
Example Hardness Tensile Breaking Shrinkage Crystallization Remarks
No. Shore A strength elongation after temperature C
DIN 53505 (MPa) (%) heating from DSC
DIN 53504 (DIN 53504) (%)
8 80 32.5 599 3.6 74
9 65 15 800 2.8 97 Sticks in mold
27.2 602 2.4 55 Sticks in mold
11 72 25.6 602 1.6 70 Sticks in mold
12 82 6.4 522 2.4 80
13 74 17.3 599 1.2 77 Plast.exudes heavily
14 72 5.2 483 0.8 72 Plast.exudes slightly
69 4.7 369 2.0 74 Plast.exudes heavily ~
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Comparison of the properties of Examples 1 to 7
according to the invention with those of Comparison
Examples 8 to 15 known from the literature clearly shows
that the property combination (soft with adequate
mechanical properties and very good demolding behavior)
is only achieved in the Examples according to the inven-
tion.
In the Comparison Examples, either
the shrinkage values are too high (Examples 8,9,10,12,
15),
the crystallization temperatures are too low (Examples
8,10,11,13,14,15,) or
the plasticizers exude and cause sticking (Examples
9,10,11,13,14,15).
