Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Biodegradable Moulding Compositions with High Sgecific Density
The present invention relates to materials with a high specific density and
areas of
application in which lead is widely used on account of its high specific
density and
ductility. Of particular importance in this connection is the replacement of
conventional lead shot and angling weights, which contribute to a considerable
extent to contamination of the ground and water with poisonous lead compounds.
In many practical applications it is necessary to use materials having a high
specific
density. Lead or its alloys are normally used in such applications, which
include for
example projectiles, weighting fillers for bullets, shot and angling weights,
in
particular for deep sea fishing. Lead has for a long time been the medium of
choice
in the aforementioned applications on account of its high density, cheap
availability
and simple processability. The considerable disadvantage of lasting
environmental
contamination and damage was ignored or disregarded on account of the lack of
ecologically and economically viable alternatives.
There have therefore been no lack of attempts in the past to develop
ecologically
practicable variants, as a result of which although it was indeed possible to
reduce
emissions - in particular to reduce lead emissions - this was offset by an
increase in
the proportion of non-degradable residues in the environment.
A series of applications (JP 07018170, JP 09105021, JP 08158161) describes the
production of conventional thermoplastics filled with metals (e.g. stainless
steel) or
with minerals (e.g. barium sulfate, magnetite, titanium dioxide) with
densities of 1.2
to 2 g/cm3 and their use in the extrusion and co-extrusion of monofilaments
and
multifilaments. Densities of this order of magnitude are however not
sufficient for
applications such as e.g. shot or angling weights. Materials of higher density
are
described in Japanese Application No. 54025950 (2.7 g/cm3) and in US Patent
Specification 5,665,808 (> 7 g/cm3); however, in this case too lead is again
used in a
mould encapsulated by a non-degradable matrix (polyester); provided the
composite
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arrangement is maintained the surrounding matrix should reduce corrosion by
lead
and contamination of the environment with poisonous lead compounds. This
solution is however only an apparent solution since contamination by poisonous
lead
compounds persists over a very long period and is not suppressed. The aim of
replacing lead is described in JP 02185540, where a density of 4.68 g/cm' is
achieved with a mixture of iron powder and plasticiser powders in polyamide-6.
EP-
A 0641836 describes materials with densities of 8-12 g/cm3, which are said to
be
achieved by filling a non-biodegradable two-component matrix consisting of
thermoplastics and an elastomer, with tungsten powder. However, the mixtures
disclosed in the examples have, with a degree of filling with tungsten of 67.5
wt.%,
densities of only ca. 3 g/cm' and not 9.5 g/cm3 as stated. The disadvantage of
these
compounds is also that they do not degrade under normal environmental
conditions
and thus constitute a long-term contamination of the environment. In WO
9508653
lead-free formulations are described that substantially consist of two metal
components and one polymer component, the polymer component being a non-
biodegradable phenol formaldehyde resin or a polymethyl methacrylate. The
materials described in WO 9508653 are processed into moulded parts only by
compacting and sintering of powders and powder mixtures and cannot be obtained
or injection moulded via a conventional extrusion process.
The claimed moulding compositions according to the invention are
characterised, in
contrast to the aforedescribed materials, by complete biodegradability of the
matrix
that is used.
It has also surprisingly been found that the injection moulding process
described as
having disadvantages in US-A 5665808 on account of the toughness qualities and
good flow properties of the matrices that are used provides in a trouble-free
manner
completely filled void-free moulded parts even at pin gate sizes of < 1 mm,
which
parts can also be removed from the mould without any difficulty and without
using
further aids that might have to be applied directly to the tool. Also, in the
production of granules suitable for the injection moulding, instead of the
multi-stage
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process described in US-A 5665808 for producing granules or a powder suitable
for
the compacting, only a one-stage compounding process without any pretreatment
of
the fillers is required.
The moulding compositions according to the invention thus permit a trouble-
free
incorporation process and a likewise problem-free processing in conventional
injection moulding machines without having to use significant amounts of
processing aids. As a result of the permanent passivation of the surfaces of
the filler
particles that are exposed to environmental influences after the
biodegradation of the
matrix (for example when using tungsten) or as a result of a complete
breakdown to
naturally occurring, non-toxic compounds (for example when using iron), the
metallic fillers or their mineral, high-density compounds that are used no
longer
represent a potential environmental threat.
1 S The present invention accordingly provides biodegradable moulding
compositions
containing
A) 1- 55 wt.% of at least one biodegradable polymer, and
B) 45 - 99 wt.% of at least one metallic and/or mineral filler.
The thermoplastic moulding compositions preferably have a density > 2 g/cm3,
measured according to ISO 1183. Particularly preferred is a density of 2 -16
g/cm3,
especially a density of S -15 g/cm3. Further preferred density ranges are 5 -
7 g/cm'
and 12 - 14 g/cm3.
Component A
Suitable biodegradable and compostable polymers that can be used as matrix for
the
high-density moulding compositions according to the invention are aliphatic or
partially aromatic polyesters, thermoplastic aliphatic or partially aromatic
polyester
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urethanes, aliphatic or aliphatic-aromatic polyester carbonates, and aliphatic
or
partially aromatic polyester amides.
The following polymers are preferred:
S
aliphatic or partially aromatic polyesters of
A) aliphatic bifunctional alcohols, preferably linear CZ to C,a dihydric
alcohols
such as for example ethanediol, butanediol, hexanediol or, particularly
preferably, butanediol, and/or optionally cycloaliphatic bifunctional
alcohols,
preferably with 5 or 6 C atoms in the cycloaliphatic ring, such as for example
cyclohexanedimethanol, and/or partially or completely, instead of the diols,
monomeric or oligomeric polyols based on ethylene glycol, propylene
glycol, tetrahydrofuran or copolymers thereof with molecular weights of up
to 4000, preferably up to 1000, and/or optionally minor amounts of branched
bifunctional alcohols, preferably C,-C,Z alkyl diols, such as for example
neopentyl glycol, and in addition optionally minor amounts of higher
functional alcohols such as for example 1,2,3-propanetriol or
trimethylolpropane, as well as minor amounts of aliphatic bifunctional acids,
preferably CZ-C,z alkyldicarboxylic acids, such as for example and preferably
succinic acid, adipic acid and/or optionally aromatic bifunctional acids such
as for example terephthalic acid, isophthalic acid, naphthalenedicarboxylic
acid and in addition optionally minor amounts of higher functional acids
such as for example trimellitic acid, or of
B) acid-functionalised and alcohol-functionalised building blocks, preferably
with 2 to 12 C atoms in the alkyl chain, for example hydroxybutyric acid,
hydroxyvaleric acid, lactic acid, or their derivatives, for example E-
caprolactone or dilactide,
or a mixture and/or a copolymer formed from A and B,
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wherein the proportion of the aromatic acids is not more than 50 wt.% referred
to all
acids.
S Aliphatic or partially aromatic polyester urethanes of
C) aliphatic bifunctional alcohols, preferably linear CZ to C,°
dihydric alcohols
such as for example ethanediol, butanediol, hexanediol, particularly
preferably butanediol, and/or optionally cycloaliphatic bifunctional alcohols,
preferably with a CS or C6 cycloaliphatic ring, such as for example
cyclohexanedimethanol, and/or partially or completely, instead of the diols,
monomeric or oligomeric polyols based on ethylene glycol, propylene
glycol, tetrahydrofuran or copolymers thereof with molecular weights up to
4000, preferably up to 1000, and/or optionally minor amounts of branched
1 S bifunctional alcohols, preferably C3-C,2 alkyl diols, such as for example
neopentyl glycol, and in addition optionally minor amounts of higher
functional alcohols, preferably C3 C,2 alkylpolyols, such as for example
1,2,3-propanetriol or trimethylolpropane, as well as of aliphatic bifunctional
acids, preferably CZ-C,2 alkyldicarboxylic acids, such as for example and
preferably succinic acid, adipic acid, and/or optionally aromatic bifunctional
acids, such as for example terephthalic acid, isophthalic acid,
naphthalenedicarboxylic acid and in addition optionally minor amounts of
higher functional acids such as for example trimellitic acid, or of
D) acid-functionalised and alcohol-functionalised building blocks, preferably
with 2 to 12 C atoms, for example hydroxybutyric acid, hydroxyvaleric acid,
lactic acid, or their derivatives, for example E-caprolactone or dilactide,
or a mixture and/or a copolymer of C and D,
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wherein the proportion of the aromatic acids is not more than 50 wt.% referred
to all
acids;
E) of the reaction product of C and/or D with aliphatic and/or cycloaliphatic
bifunctional and in addition optionally higher functional isocyanates,
preferably with 1 to 12 C atoms or 5 to 8 C atoms in the case of
cycloaliphatic isocyanates, for example tetramethylene diisocyanate,
hexamethylene diisocyanate, isophorone diisocyanate, optionally in addition
with linear and/or branched and/or cycloaliphatic bifunctional and/or higher
functional alcohols, preferably C3-C,2 alkyl diols or alkyl polyols, or with 5
to 8 C atoms in the case of cycloaliphatic alcohols, for example ethanediol,
hexanediol, butanediol, cyclohexanedimethanol, and/or optionally in addition
with linear and/or branched and/or cycloaliphatic bifunctional and/or higher
functional amines and/or aminoalcohols with preferably 2 to 12 C atoms in
the alkyl chain, for example ethylenediamine or amino ethanol, and/or
optionally further modified amines or alcohols, such as for example
ethylenediaminoethanesulfonic acid, as free acid or as a salt,
wherein the proportion of the ester C) and/or D) is at least 75 wt.% referred
to the
sum of C), D) and E).
Aliphatic or aliphatic-aromatic polyester carbonates of
F) aliphatic bifunctional alcohols, preferably linear CZ to C,°
dihydric alcohols
such as for example ethanediol, butanediol, hexanediol or, particularly
preferably, butanediol, and/or optionally cycloaliphatic bifunctional
alcohols,
preferably with 5 to 8 C atoms in the cycloaliphatic ring, such as for example
cyclohexanedimethanol, and/or partially or completely, instead of the diols,
monomeric or oligomeric polyols based on ethylene glycol, propylene
glycol, tetrahydrofuran or copolymers thereof with molecular weights of up
to 4000, preferably up to 1000, and/or optionally minor amounts of branched
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bifunctional alcohols, preferably with C2-C,Z alkyldicarboxylic acids, such as
for example neopentyl glycol, and in addition optionally minor amounts of
higher functional alcohols such as for example 1,2,3-propanetriol,
trimethylolpropane, as well as of aliphatic bifunctional acids such as for
example and preferably succinic acid, adipic acid and/or optionally aromatic
bifunctional acids such as for example terephthalic acid, isophthalic acid,
naphthalenedicarboxylic acid and in addition optionally minor amounts of
higher functional acids such as for example trimellitic acid, or of
G) acid-functionalised and alcohol-functionalised building blocks, preferably
with 2 to 12 C atoms in the alkyl chain, for example hydroxybutyric acid,
hydroxyvaleric acid, lactic acid, or their derivatives, for example E-
caprolactone or dilactide,
1 S or a mixture and/or a copolymer of F and G,
wherein the proportion of the aromatic acids is not more than 50 wt.% referred
to all
acids,
H) a carbonate fraction that is formed from aromatic bifunctional phenols,
preferably bisphenol A, and carbonate donors, for example phosgene,
or
a carbonate fraction that is formed from aliphatic carbonic acid esters or
their
derivatives such as for example chlorocarbonic acid esters, or aliphatic
carboxylic acids or their derivatives such as for example salts and carbonate
donors, for example phosgene, wherein
the ester fraction F) and/or G) is at least 70 wt.%, referred to the sum of
F), G) and
H);
aliphatic or partially aromatic polyester amides of
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I) aliphatic bifunctional alcohols, preferably linear CZ to C,°
dihydric alcohols,
for example ethanediol, butanediol, hexanediol, particularly preferably
butanediol, and/or optionally cycloaliphatic bifunctional alcohols, preferably
with 5 to 8 C atoms, such as for example cyclohexaaedimethanol, and/or
partially or completely, instead of the diols, monomeric or oligomeric
polyols based on ethylene glycol, propylene glycol, tetrahydrofuran or
copolymers thereof with molecular weights of up to 4000, preferably up to
1000, and/or optionally minor amounts of branched bifunctional alcohols,
preferably C; C,2 alkyl diols, such as for example neopentyl glycol, and in
addition optionally minor amounts of higher functional alcohols, preferably
C,-C,z alkylpolyols, such as for example 1,2,3-propanetriol,
trimethylolpropane, as well as of aliphatic bifunctional acids, preferably
with
2 to 12 C atoms in the allryl chain, such as for example and preferably
succinic acid, adipic acid and/or optionally aromatic bifunctional acids such
as for example terephthalic acid, isophthalic acid, naphthalenedicarboxylic
acid and in addition optionally minor amounts of higher functional acids
such as for example trimellitic acid, or of
K) acid-functionalised and alcohol-functionalised building blocks, preferably
with 2 to 12 C atoms in the carbon chain, for example hydroxybutyric acid,
hydroxyvaleric acid, lactic acid, or their derivatives, for example E-
caprolactone or dilactide,
or a mixture and/or a copolymer of I) and K),
wherein the proportion of the aromatic acids is not more than 50 wt.% referred
to all
acids,
L) an amide fraction of aliphatic and/or cycloaliphatic bifunctional and/or
optionally minor amounts of branched bifunctional amines, preferably linear
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aliphatic CZ-C,° diamines, and in addition optionally minor amounts of
higher functional amines, preferably hexamethylenediamine, isophorone
diamine and particularly preferably hexamethylenediamine, as well as of
linear and/or cycloaliphadc bifunctional acids, preferably with 2 to 12 C
atoms in the alkyl chain or a CS- or C6 ring in the case of cycloaliphatic
acids, preferably adipic acid and/or optionally minor amounts of branched
bifunctional and/or optionally aromatic bifunctional acids such as for
example terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid and
in addition optionally minor amounts of higher functional acids, preferably
with 2 to 10 C atoms, or of
lVl~ an amide fraction formed from acid-functionalised and amine-
functionalised
building blocks, preferably with 4 to 20 C atoms in the cycloaliphatic chain,
preferably w-laurinlactam, E-caprolactam, particularly preferably E
caprolactam,
or a mixture of L) and IVj] as amide fraction, wherein
the ester fraction >) and/or K) is at least 30 wt.% referred to the sum of )~,
K), L), and
1V>7, and preferably the weight proportion of the ester structures is 30 to 70
wt.%, and
the proportion of the amide structures is 70 to 30 wt.%.
All acids may also be used in the form of derivatives such as for example acid
chlorides or esters, the latter being in the form of both monomeric and
oligomeric
esters.
The polyester amides and the further polymers are particularly preferably
built up
from the aforementioned, preferred and particularly preferred aliphatic acid
building
blocks and amine blocks and/or cycloaliphatic acid-functionalised and alcohol-
functionalised and/or acid-functionalised and amine-functionalised building
blocks.
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Particularly preferred are polyester amides containing as alcohol component,
ethanediol, butanediol, diethylene glycol or hexanediol, or a mixture thereof
with at
least two of the components and optionally with polyethylene glycol, and as
acid
component, succinic acid and/or adipic acid, and s-caprolactam and/or adipic
hexamethylenediamine.
Glycerol, trimethylolpropane or pentaerythritol may preferably be used as
branching
agent.
The synthesis of the biodegradable polyester amides according to the invention
may
be carried out according to the "polyamide method" by stoichiometric mixing of
the
starting components, optionally with the addition of water followed by the
removal
of water from the reaction mixture, as well as by the "polyester method" by
stoichiometric mixing of the starting components as well as the addition of an
excess
of diol with esterification of the acid groups and subsequent
transesterification or
transamidation of these esters. In the latter case water as well as the excess
of diol is
distilled off. The synthesis is preferably carried out according to the
aforedescribed
"polyester method".
The polycondensation may furthermore be accelerated by using known catalysts.
It
is possible to use the known phosphorus compounds that accelerate the
polyamide
synthesis, as well as acidic or organometallic catalysts for the
esterification, or also
combinations of the two, in order to accelerate the polycondensation.
Care should be taken to ensure that the catalysts do not have an adverse
effect on
either the biodegradability, compostability or the quality of the resulting
compost.
In addition the polycondensation to form polyester amides can be influenced by
using lysine, lysine derivatives or other amidically-branching products such
as for
example aminoethylaminoethanol, which both accelerate the condensation and
also
lead to branched products (see for example DE 3831709).
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The production of polyesters, polyester carbonates and polyester urethanes is
generally known and is carried out in an analogous manner by known processes
(see
for example EP-A 304 787, WO 95/12629, WO 93/13154, EP-A 682 054, EP-A 593
975).
The polyesters, polyester urethanes, polyester carbonates or polyester amides
according to the invention may in addition contain 0.1 to 5 wt.%, preferably
0.1 to 1
wt.%, of branching agents (see also the description of the polymers). These
branching agents may for example be trifunctional alcohols such as
trimethylolpropane or glycerol, tetrafunctional alcohols such as
pentaerythritol, or
trifimctional carboxylic acids such as citric acid. The branching agents
increase the
melt viscosity of the polyester amides according to the invention to such an
extent
that extrusion blow moulding with these polymers is possible. The
biodegradability
of these materials is not thereby affected.
The biodegradable/compostable polyester urethanes, polyesters, polyester
carbonates
and polyester amides as a rule have a molecular weight of at least 10,000
g/mole and
generally have a statistical distribution of the starting substances in the
polymer. In
the case of a polyurethane-type polymer structure, possibly formed from C) and
D)
as well as from E), a completely statistical distribution of the monomer
building
blocks cannot always be expected.
Component B
As high-density fillers there may for example be used iron powder, iron
oxides, iron
alloys (e.g. ferrotitanium, ferromolybdenum, ferromanganese) tungsten,
tungsten
carbide, ferrotungsten, molybdenum, manganese, cobalt, copper, zinc, tin or
bismuth, or combinations thereof.
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Combinations of powders with particle size ratios of 1 : > 6 permit for
example
higher volume filling levels to be achieved than in the case of a cubic
closest
packing with only one type of particle, while retaining the flowability.
The combination of various particle sizes and powders of different metals
moreover
permits the mechanical properties of the resultant moulded articles to be
suitably
adapted. In particular the brittleness of bullet cores and shot can be matched
to the
property profile of lead as regards inelastic deformation and brittle cracking
on
impact on game, or on the target in shooting ranges and rifle ranges.
The biodegradable/completely compostable polyester urethanes, polyesters,
polyester carbonates and polyester amides according to the invention may
contain
conventional additives. Thus, modifying agents and/or fillers and reinforcing
agents
and/or processing aids such as for example nucleating agents, plasticisers,
mould
release agents, flame retardants, impact modifiers, colouring agents,
stabilisers or
other conventional additives used in the thermoplastics sector may be
employed, in
which connection it should be ensured that the complete compostability is not
adversely affected or the remaining substances, for example mineral auxiliary
substances, in the compost are harmless. In general up to 5 wt.%, preferably
up to 3
wt.% (referred to A and B) of additives may be added.
Suitable fillers and reinforcing agents according to the invention may be
minerals
such as for example kaolin, chalk, gypsum, limestone or talcum, or natural
materials
such as for example starch or modified starch, cellulose or cellulose
derivatives or
cellulose products, sawdust, or natural fibres such as for example hemp, flax,
sisal,
rape or ramie.
The biodegradable/completely compostable polyester urethanes, polyesters,
polyester carbonates and polyester amides according to the invention may also
be
blended with further blending partners, for example thermoplastic starch, in
which
connection it should be ensured that the complete compostability is not
adversely
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affected or the remaining substances, for example mineral auxiliary
substances, in
the compost are harmless.
The invention furthermore provides a process for producing the moulding
compositions according to the invention, wherein the components of the
moulding
compositions according to the invention are added to an extruder, kneader or
mixer
in a conventional manner via a hopper and/or ancillary screw device, the
matrix is
melted by applying shear forces and thermal energy and is thoroughly mixed
with
the fillers, and the mouldable compounding granules are thus obtained in only
one
extrusion or mixing step. A sinking of the fillers in the melt, which are
specifically
very much denser compared to the matrix, is not observed.
The invention furthermore provides for the use of the moulding compositions to
produce moulded bodies, sheets, fibres, extrudates and constituents of
ballistic
projectiles, angling weights, angling hooks and constituents thereof, sound
insulating materials, thermally conducting components for electronic
equipment,
structural parts and housing constituents for electromagnetic shielding of
electrical
equipment, electrically conducting moulded parts of arbitrary shapes, as well
as
magnetic moulded parts of free shape and design as well as the objects
produced
themselves.
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Examples
Ezample 1
A compound consisting of 19.6 wt.% of polyester amide (produced from 617 g of
adipic acid, 487 g of adipic hexamethylenediamine, 226 g of diethylene glycol,
181 g of butanediol together with titanium tetraisopropylate as catalyst,
rire, of a 1
wt.% solution in m-cresol at 20°C is 2.7), 80 wt.% of tungsten powder
(technical
batch W4676 from H.C. Starck GmbH & Co. KG, Goslar, Germany) and 0.4 wt.%
of Loxiol EP 728 (Henkel KGaA, Diisseldorf, Germany) is produced in a ZSK 32
double-screw extruder from Wemer & Pfleiderer and processed as granules by
injection moulding. The compound has a density of 4.58 g/cm', a modulus of
elasticity of 700 MPa measured in the tensile test according to ISO 527, and
an
elongation at break of 90%. In the Izod impact test (ISO 180/1C) the test body
does
not break at room temperature.
Example 2
A compound consisting of 49.6 wt.% of polyester amide according to Example 1,
50 wt.% of copper powder FFL-2 (Norddtsch. Refinery) and 0.4% of Loxiol EP 728
is produced like the compound in Example 1 and processed by injection
moulding.
The material has a density of 2.04 g/cm3, a modulus of elasticity of 680 MPa
and an
elongation at break of 49%. In the Izod impact test the test body does not
break at
room temperature.
Ezample 3
A compound consisting of 9 wt.% of polyester amide according to Example 1 and
91 wt.% of iron powder MPD 2002 (Mannesmann Demag AG) is produced and
processed as described in Examples 1 and 2.
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The material has a density of 5.08 g/cm', a modulus of elasticity of 2870 MPa,
an
elongation at break of 1.4%, and an impact strength of 16 kJ/mz.
Ezample 4
A density of 12.9 g/cm' is achieved with a compound consisting of 3 wt.% of
polyester amide according to Example 1 and 97 wt.% of tungsten powder
(technical
batch W4676 from H.C. Starck GmbH & Co. KG, Goslar, Germany). The material
has a modulus of elasticity of 2730 MPa, an elongation at break of 3.8%, and
an
impact strength of 17 kJ/m2.
