BIODEGRADABLE POLYESTERAMIDES WITH ALIPHATIC-AROMATIC STRUCTURES

POLYESTERAMIDES BIODEGRADABLES A STRUCTURES AROMATIQUES ALIPHATIQUES

English Abstract

Statistically structured biodegradable aliphatic-aromatic polyesteramides,
comprising the following monomers: aliphatic dialcohols such as ethylene
glycol, diethylene glycol, 1-4-butandiol, 1,3-propandiol, 1,6-hexandiol or
cycloaliphatic diols such as cyclohexandimethanol and/or aliphatic
dicarboxylic acid such as oxalic acid, succinic acid, adipic acid, etc. also
in the form of the corresponding esters (methyl, ethyl, etc.) and/or aromatic
dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid,
etc. also in the form of the corresponding esters (methy, ethyl, etc.) and/or
hydroxycarboxylic acids and lactone such as caprolactone, etc. and/or amino
alcohols such as ethanolamine, propanolamine, etc. and/or cyclic lactam such
as .epsilon.-caprolactam or laurine lactam, etc. and/or .omega.-
aminocarboxylic acids such as aminocaproic acid etc. and/or mixtures (1:1
salts) of dicarboxylic acids such as adipic acid, succinic acid, terephthalic
acid, etc. and diamines such as hexamethylene diamine, diamino butane, etc.,
wherein said polyesteramides contain up to 70 mol % aromatic dicarboxylic
acids (in relation to the amount of acids).

French Abstract

L'invention concerne des polyesteramides aromatiques aliphatiques biodégradables statistiques, constitués des monomères suivants: dialcools aliphatiques tels que éthylèneglycol, diéthylèneglycol, 1,4-butanediol, 1,3-propanediol, 1,6-hexanediol ou diols cyclo-aliphatiques tels que cyclohexane-diméthanol; acides dicarboxyliques aliphatiques tels que acide oxalique, acide succinique, acide adipique, etc., également sous forme de leur ester respectif (méthylique, éthylique, etc.); acides dicarboxyliques aromatiques tels que acide téréphtalique, acide isophtalique, acide phtalique, etc., également sous forme de leur ester respectif (méthylique, éthylique, etc.); acides hydroxycarboxyliques et lactones tels que caprolactone, etc.; amino-alcools tels que éthanolamine, propanolamine, etc.; lactames cycliques tels que .epsilon.-caprolactame ou laurine-lactame, etc.; acides .omega.-aminocarboxyliques tels que acide aminocaproïque, etc.; et/ou mélanges (sels 1:1) d'acides dicarboxyliques tels que acide adipique, acide succinique, acide téréphtalique, etc., et de diamines telles que hexaméthylènediamine, diaminobutane, etc. Les polyesteramides selon l'invention contiennent jusqu'à 70 mole % (par rapport à la partie acide) d'acides dicarboxyliques aromatiques.

Claims

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Claims
1. Statistically synthesised aliphatic-aromatic polyesteramides which are
synthesised from the following monomers:
- aliphatic dialcohols, cycloaliphatic diols and/or
- aliphatic dicarboxylic acid, also in the form of its respective esters
and/or
- aromatic dicarboxylic acids, also in the form of their respective esters
and/or
- hydroxycarboxylic acids and/or lactones and/or
- aminoalcohols and/or
- cyclic lactams and/or
- .omega.-aminocarboxylic acids and/or
- mixtures (1:1 salts) of dicarboxylic acids and diamines,
the content of aromatic dicarboxylic acids (based on the acid content) being
up to 70 mol%.
2. Polyesteramides according to claim 1, which are synthesised from the
following monomers:
- aliphatic dialcohols having 2 to 12 carbon atoms and/or
- aliphatic dicarboxylic acid having 2 to 12 carbon atoms in the alkyl
and/or

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- terephthalic acid, isophthalic acid, phthalic acid or mixtures thereof
as aromatic dicarboxylic acids, aaad/or
- hydroxycarboxylic acids and/or lactones having 2 to 12 C atoms in
the alkyl and/or
- aminoalcohols having 2 to 12 C atoms in the alkyl and/or
- cyclic lactams and/or
- .omega.-aminocarboxylic acids having 2 to 12 C atoms in the alkyl and/or
- mixtures (1:1 salts) of dicarboxylic acids having 2 to 12 C atoms in
the alkyl or 6 to 10 C atoms in the aromatic ring and alkyldiamines
having 1 to 12 C atoms.
3. Use of the polyesteramides according to claims 1 and 2 for the production
of
films, sheets, injection-moulded articles, nonwoven fabrics, fibres and foams.
4. Films, sheets, injection-moulded articles, nonwoven fabrics, fibres, foams,
produced from polyesteramides according to claims 1 to 3.

Description

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Biodegradable polyesteramides having aliphatic-aromatic structures
Compostable aliphatic polyesteramides are known (for example, EP-A 545 203 and
641 817). Compostable aliphatic-aromatic polyesteramides have also been
described
(WO 92/21689, WO 96/21690, WO 96/21691 and WO 96/21692).
The compounds described are polyesteramides of adipic acid, terephthalic acid,
diols, aminoalcohols, aminocarboxylic acids and hydroxycarboxylic acids, which
still have to be fiuther cross-linked in order to atl;ain adequate mechanical
properties.
This further cross-linking is carried out with diisocyanates, divinyl ethers
or
bisoxazolines.
This reaction is however very expensive and is controlled only with great
difficulty.
There is invariably the risk of uncontrolled cro;>s-linking, which in the
subsequent
processing can lead to gel structures or the like. 'These gel structures are
undesirable
above all in the production of sheets but, being highly cross-linked
components, they
also interfere with biodegradation.
The object of the present invention is to provide aliphatic-aromatic
polyesteramides,
which are statistically synthesised and do not have the disadvantage mentioned
above.
This invention accordingly provides statistically synthesised aliphatic-
aromatic
polyesteramides which are synthesised from the fbllowing monomers:
- aliphatic dialcohols, preferably having 2 to 12 carbon atoms, in particular
ethylene glycol, diethylene glycol, 1,4-butanediol, 1,3-propanediol, 1,6-
hexanediol or cycloaliphatic diols, preferably having 5 or 6 C atoms in the
cycloaliphatic ring, in particular cyclohexanedimethanol, and/or
A 32 1~~~

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- aliphatic dicarboxylic acid, preferably having 2 to 12 carbon atoms in the
alkyl, in particular oxalic acid, succinic acid, adipic acid and others, also
in
the form of their respective esters (methyl, ethyl etc.), and/or
- aromatic dicarboxylic acids, by way of f;xample and preferably terephthalic
acid, isophthalic acid, phthalic acid and others, also in the form of their
respective esters (methyl, ethyl etc.), and/or
- hydroxycarboxylic acids and lactones, preferably having 2 to 12 C atoms in
the alkyl group, in particular hydroxybutyTic acid, hydroxyvaleric acid,
lactic
acid, caprolactone, dilactide and others, and/or
- aminoalcohols, preferably having 2 to 1i.2 C atoms, in particular ethanol-
amine, propanolamine etc., and/or
- cyclic lactams, for example and preferably E-caprolactam or lauryl lactam
etc., and/or
- w-aminocarboxylic acids, preferably having 2 to 12 C atoms in the alkyl, for
example and in particular aminocaproic acid etc., and/or
- mixtures ( 1:1 salts) of dicarboxylic acids, preferably having 2 to 12 C
atoms
in the alkyl chain or 6 to 10 C atoms in the aromatic ring, in particular
adipic
acid, succinic acid, terephthalic acid etc. and diamines, preferably having 2
to
12 C atoms in the alkyl, in particular hexamethylenediamine, diaminobutane
etc.,
the content of aromatic dicarboxylic acids (based on the acid content) being
up to 70
mol%.
JO
The monomers are so selected that they lead to the; synthesis of the
polyesteramide.

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The proportion of aromatic dicarboxylic acids constituting the total acid
content is
up to 70 mol%.
The polyesteramides contain preferably from 0.5 to 65 mol% aromatic
dicarboxylic
acids.
The ester content is between 20 wt.% and 85 wt.%.
The invention also provides the use of the polyamides mentioned here for the
production of films, sheets, injection-moulded articles, nonwoven fabrics,
fibres and
foams as well as the films, sheets, injection-moulded articles, nonwoven
fabrics,
fibres and foams produced.
Hydroxy-terminated or acid-terminated polyesters consisting of the above-
1 S mentioned monomers, having molecular weights between 300 and 10,000, can
equally be used as ester-forming components.
Likewise, amino-terminated or acid-terminated 1>olyamides consisting of the
above-
mentioned monomers, having molecular weights between 200 and 10,000, can also
be used as amide-forming components.
The synthesis can be carried out both by the "polyamide method", involving
mixing
together stoichiometric proportions of the starting components optionally with
addition of water and subsequent removal of watf;r from the reaction mixture,
and by
the "polyester method", involving addition of an excess of diol with
esterification of
the acidic groups and subsequent transesterification or transamidation of
these esters.
In this second case, besides water the excess glycol is also removed again by
distillation.
Preferably caprolactam or hexamethylenediamine salt of adipic acid or mixtures
thereof with butanediol and diethylene glycol and a mixture of terephthalic
acid and
adipic acid are used for the synthesis.

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The polyesteramides thus prepared are completely biodegradable according to
DIN
54 900 and have very good mechanical properties, so that they require no
further
cross-linking.
The capacity of a polymer to be decomposed by enzymes is termed enzymic
degradability. Here, the bonds by which the structural units of the polymer
are
linked together are broken. The resulting breakdown products are the monomers
of
the polymer and its oligomers. The enzymic degradation of the polymer leads to
a
decrease in its molecular weight. Enzymic degradation differs from
biodegradation
in that it does not as a rule lead to naturally-occurring metabolic products.
In principle, all enzymes which are capable of breaking the bonds present in
the
polymer can be used as enzymes which degrade the biodegradable polymers. In
selecting the enzymes, care is to be taken to ensure that these are capable of
rapidly
and completely degrading the polymer. The degradation is carried out in an
aqueous
solution, which can be buffered. The pH value can be between 3 and 11, is
preferably between 5 and 9 and particularly preferably between 6 and 8. The
temperature at which the enzymic degradation is carried out can be between
5°C and
95°C, is preferably between 20°C and 70°C and
particularly preferably between
30°C and 50°C.
The following are examples of buffers which can be used according to the
invention:
citrate, acetate, phosphate, formate, carbonate,
tris(hydroxymethyl)aminomethate,
triethanolamine, imidazole, oxalate, tartrate, fumarate, maleate, phthalate,
succinate,
ethylenediamine, as well as mixtures of several of these. Preferably acetate,
phosphate and citrate are used as buffers.
The procedure is to add the enzyme and polymer to the aqueous solution. The
biodegradable polymer can be added in the form of film, sheet or granules.
Mouldings can be added as an intact whole or can be comminuted. Coated or
bonded
materials, or materials in the case of which coatings have been applied or
bonds

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produced using biodegradable polymers, such as, for example, paper or
cardboard,
as well as coated paper or coated cardboard, ca~1 be added either as an intact
whole
or in comminuted form to the enzyme-containing solution.
S The aqueous enzyme-containing solution can also be applied or sprayed on by
spraying onto the coating to be degraded or onto the moulding to be degraded.
The enzymes used can be lipolytic and/or proteolytic enzymes.
For the purpose of this invention, lipases, cutinases, esterases,
phospholipases and
lysophospholipases are referred to as lipolytic; enzymes. The lipolytic
enzymes
originate preferably from microorganisms. They originate in particular from
bacteria, fungi or yeasts. The lipolytic enzymes may also be of vegetable or
animal
origin.
For the purpose of this invention, proteases are referred to as proteolytic
enzymes.
These originate preferably from bacteria of the genus Bacillus; proteases of
the
organisms Bacillus alcolophilus and Bacillr.~s licheniformis are particularly
preferred. They may also originate from fungi or from plants.
The joint use of lipolytic and proteolytic enzymes as well as of lipolytic
enzymes of
varying specificity, which can lead to synergistic effects, is according to
the
invention. The addition of metal ions such as, for example, sodium ions or
calcium
ions, which accelerate the enzymic degradability., is also according to the
invention.
The addition of auxiliary substances such as anionic or nonionic surfactants
such as,
for example, sec. alcoholethoxylates, is also according to the invention.
Compostability is the capacity of a polymeric rn. aterial to be biodegraded
during a
composting process. For the polymeric material to be regarded as compostable,
it
has to be proved by means of standard methods that it can be biodegraded in a
composting system and that compost of flawless quality can be produced
(according
to DIN 54 900).

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The biodegradation of a material is a process which is caused by biological
activity
and leads to naturally-occurring metabolic end products, with alteration of
the
chemical structure of the material (according to DIN 54 900).
A polymeric material is biodegradable if all organic constituents are subject
to a
complete biological degradation, which is determined by standard processes
(according to DIN 54 900).
In the preparation of the polyesteramides, suitable catalysts can be used to
catalyse
the esterification reaction or the amidation reaction. These catalysts
include, for
example, titanium compounds for the esterifications and phosphorus compounds
for
the amidation reactions. These catalysts are in accordance with prior art.
They must
not, however, subsequently restrict the use of the degradable polymer in the
compost
and they must not interfere with the biodegradability. For this reason
catalysts based
on heavy metals such as antimony or lead, for example, are completely
dispensed
with.
The mixtures according to the invention may contain in addition from 0 to 80
wt.%
of conventional additives, for example, inorganic fillers and reinforcing
materials,
preferably fibrous (glass fibres, carbon fibres) reinforcing materials and
mineral
fillers (for example, talc, mica, chalk, kaolin, wollastonite, gypsum, quartz,
dolomite
and others), UV stabilisers, antioxidants, pigments, dyes, nucleating agents,
accelerators of crystallisation and inhibitors, flow-promoting agents,
lubricants,
mould release agents, flameproofing agents.
The polyesteramides according to the invention may further contain from 0.05
to 5
wt.%, preferably from 0.1 to 1 wt.%, of branching agents. These branching
agents
can be, for example, trifunctional alcohols, such as trimethylolpropane or
glycerol,
tetrafunctional alcohols such as pentaerythritol, trifixnctional carboxylic
acids such
as citric acid or even tri- or tetrafunctional hydroxycarboxylic acids.

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Examples
Example 1
S 1,233.8 g (2.066 mol) caprolactam, 58.1 g (0.397 mol) adipic acid, 89.4 g
(0.992
mol) butanediol and 65.99 g (0.397 mol) terephthalic acid are heated together
to
250°C under nitrogen. After 1 hour a water jet vacuum pump is applied
and after 2.5
hours an oil vacuum pump, and water and butanediol are distilled off. After a
polycondensation time of 7 hours, a colourless polymer having a melting point
of
136°C is obtained.
The material is completely compostable according to DIN 54 900.
Example 2
2,185.8 g (0.709 mol) hexamethylenediamine sall: of adipic acid, 156.9 g
(1.074 mol)
adipic acid, 24.7 g (0.274 mol) butanediol, 95.9 l; (0.904 mol) diethylene
glycol and
9.39 g (0.057 mol) terephthalic acid are heated together to 250°C under
nitrogen.
After 1 hour a water jet vacuum pump is applied and after 2.5 hours an oil
vacuum
pump, and water and butanediol are distilled off. After a polycondensation
time of 7
hours, a colourless polymer having a melting point of 175°C is
obtained.
The material is completely compostable according; to DIN 54 900.