U.S. patent application number 13/623546 was filed with the patent office on 2013-04-25 for use of an aqueous dispersion of biodegradable polyesters.
This patent application is currently assigned to BASF SE. The applicant listed for this patent is Gimmy Alex Fernandez Ramirez, Liqun Ren, Hermann Seyffer, Gabriel Skupin. Invention is credited to Gimmy Alex Fernandez Ramirez, Liqun Ren, Hermann Seyffer, Gabriel Skupin.
Application Number | 20130101865 13/623546 |
Document ID | / |
Family ID | 48136222 |
Filed Date | 2013-04-25 |
United States Patent
Application |
20130101865 |
Kind Code |
A1 |
Ren; Liqun ; et al. |
April 25, 2013 |
USE OF AN AQUEOUS DISPERSION OF BIODEGRADABLE POLYESTERS
Abstract
The present invention relates to the use of an aqueous
dispersion of at least one biodegradable polyester in the form of a
coating for improving the barrier properties of packaging materials
made of paper or paperboard, in particular of packaging materials
made of recycled paper or paperboard, with respect to mineral oils.
The present invention also relates to a process for producing
barrier coatings on paper or paperboard, in particular on recycled
paper or paperboard.
Inventors: |
Ren; Liqun; (Mannheim,
DE) ; Fernandez Ramirez; Gimmy Alex; (Ludwigshafen,
DE) ; Seyffer; Hermann; (Heidelberg, DE) ;
Skupin; Gabriel; (Speyer, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ren; Liqun
Fernandez Ramirez; Gimmy Alex
Seyffer; Hermann
Skupin; Gabriel |
Mannheim
Ludwigshafen
Heidelberg
Speyer |
|
DE
DE
DE
DE |
|
|
Assignee: |
BASF SE
Ludwigshafen
DE
|
Family ID: |
48136222 |
Appl. No.: |
13/623546 |
Filed: |
September 20, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61538210 |
Sep 23, 2011 |
|
|
|
Current U.S.
Class: |
428/481 ;
427/411 |
Current CPC
Class: |
Y02A 40/90 20180101;
D21H 21/16 20130101; Y10T 428/3179 20150401; D21H 27/10 20130101;
D21H 19/82 20130101; D21H 19/824 20130101; Y02A 40/961 20180101;
D21H 19/28 20130101 |
Class at
Publication: |
428/481 ;
427/411 |
International
Class: |
D21H 19/82 20060101
D21H019/82 |
Claims
1.-20. (canceled)
21. The use of an aqueous dispersion of at least one biodegradable
polyester in the form of a coating for improving the barrier
properties of packaging material made of paper or paperboard with
respect to mineral oils.
22. The use according to claim 21, where the packaging material has
been produced at least to some extent from mineral-oil-contaminated
recycling paper.
23. The use according to claim 21, where the packaging material is
intended for the packaging of food or drink.
24. The use according to claim 21, where the weight per unit area
of the coating is from 2 to 50 g/m.sup.2.
25. The use according to claim 21, where the coating has at least
two layers arranged on top of one another.
26. The use according to claim 25, where the coating weight per
unit area of each of the layers is from 1 to 30 g/m.sup.2.
27. The use according to claim 21, where the content of
biodegradable polyester, based on the total solids content of the
polyester dispersion, accounts for at least 30% by weight.
28. The use according to claim 21, where the biodegradable
polyester is selected from the group of the aliphatic polyesters,
aliphatic copolyesters, aliphatic-aromatic copolyesters, and
mixtures of these.
29. The use according to claim 21, where the polyester consists
essentially of: a) at least one dicarboxylic acid component A,
which is composed of a1) at least one aliphatic or cycloaliphatic
dicarboxylic acid or ester-forming derivatives of these, or a
mixture thereof, and a2) optionally one or more aromatic
dicarboxylic acids which have no sulfonic acid group, or
ester-forming derivatives of these, or a mixture thereof, a3)
optionally one or more aromatic dicarboxylic acids which have at
least one sulfonic acid group, or ester-forming derivatives of
these, or a mixture thereof; b) at least one diol component B
selected from aliphatic and cycloaliphatic diols and mixtures of
these; c) optionally one or more other bifunctional compounds C
which react to form bonds with carboxylic acid groups or with
hydroxy groups; and d) optionally one or more compounds D which
have at least three functionalities which react to form bonds with
carboxylic acid groups or with hydroxy groups; where the molar
ratio of component A to component B is in the range from 0.4:1 to
1:1, and components A and B account for at least 80% by weight of
the polyester.
30. The use according to claim 29, where the polyester consists
essentially of: a) at least one dicarboxylic acid component A which
is composed of a1) from 35 to 90 mol % of at least one aliphatic or
cycloaliphatic dicarboxylic acid, or ester-forming derivatives of
these, or a mixture thereof, and a2) from 10 to 65 mol % of one or
more aromatic dicarboxylic acids or ester-forming derivatives of
these, or a mixture thereof; a3) from 0 to 5 mol % of one or more
aromatic dicarboxylic acids which have at least one sulfonic acid
group, or ester-forming derivatives of these, or a mixture thereof,
where the mol % data for components a1), a2), and a3) give a total
of 100 mol %; b) from 98 to 102 mol %, based on the total amount of
components a1) and a2), of at least one diol component B selected
from aliphatic and cycloaliphatic diols and mixtures of these; c)
from 0 to 2% by weight, based on the total weight of the polyester,
of one or more other bifunctional compounds C which react to form
bonds with carboxylic acid groups or with hydroxy groups; and d)
from 0 to 2% by weight, based on the total weight of the polyester,
of one or more compounds D which have at least 3 functionalities
which react to form bonds with carboxylic acid groups or with
hydroxy groups.
31. The use according to claim 21, where the number-average
molecular weight of the polymer is in the range from 5000 to 1 000
000 daltons.
32. The use according to claim 21, where the weight-average
molecular weight of the polymer is in the range from 10 000 to 5
000 000 daltons.
33. A process for producing a barrier coating on paper or
paperboard via application of at least one aqueous dispersion of at
least one biodegradable polyester as defined in claim 21, to at
least one surface of the paper or paperboard, where a first layer
is produced in a first step via application of the aqueous
dispersion to a surface of the paper or paperboard, and then at
least one further layer, arranged on the first layer, is produced
in at least one further step via application of the aqueous
dispersion to the first layer obtained in the first step.
34. The process according to claim 33, where the amount of the
polyester dispersion applied in each step is such that the
resultant weight per unit area of the coating is in the range from
1 to 30 g/m.sup.2 per layer.
35. The process according to claim 33, where the amount of the
polyester dispersions applied in the steps is such that the
resultant total weight per unit area of the coating is in the range
from 2 to 50 g/m.sup.2.
36. The process according to claim 33, where the content of
biodegradable polyester, based on the total solids content of the
polyester dispersion, accounts for at least 30% by weight.
37. The process according to claim 33, where the biodegradable
polyester is a polyester according to claim 28.
38. The process according to claim 33, where the paper or the
paperboard has been produced at least to some extent from
mineral-oil-contaminated recycling paper.
39. The process according to claim 33, where the coated paper or
the coated paperboard is intended to be packaging material for the
packaging of food or drink.
40. A coated paper or paperboard, obtainable according to claim 33.
Description
[0001] The present invention relates to the use of an aqueous
dispersion of at least one biodegradable polyester in the form of a
coating for improving the barrier properties of packaging materials
made of paper or paperboard, in particular of packaging materials
made of recycled paper or paperboard, with respect to mineral oils.
The present invention also relates to a process for producing
barrier coatings on paper or paperboard, in particular on recycled
paper or paperboard.
[0002] Paper packaging and paperboard packaging are often produced
from recycled paper. When printed paper is used, in particular
newspaper, the recycled paper can comprise mineral oil residues,
e.g. from the printing inks usually used for the printing of
newspapers. Even at room temperature, volatile content vaporizes
from said residues and in the case of packaging for food or drink
this is deposited on the food or drink packaged in the box, for
example pasta, semolina, rice, or cornflakes. Most of the inner
bags used nowadays and made of polymer foils also provide no
adequate protection from this effect. Studies by the Cantonal
Laboratory of Zurich demonstrated the presence of considerable
amounts of mineral oil residues in food or drink packaged in
packaging made of recycled paper. The volatile constituents of
mineral oil mainly involve aromatic hydrocarbons, in particular
those having from 15 to 25 carbon atoms, and paraffinic and
naphthenic hydrocarbons, these being hazardous to health.
[0003] There is therefore a need to reduce the risk of
contamination of food or drink with mineral oil residues. One
possibility would be to avoid recycling of newspaper in the
production of cartons for the packaging of food or drink. This is
undesirable for environmental reasons and impractical because the
available amounts of fresh pulp are inadequate. Another solution
would be to avoid mineral oils in the printing inks used for
printing newspapers. However, there are technological obstacles to
that solution, especially in relation to the resistance of the
print to wiping from the surface of the paper.
[0004] Packaging materials made of paper or paperboard are often
equipped with a barrier coating in order to reduce penetration of
the vegetable or animal fats or oils comprised within foods.
[0005] By way of example, WO 2006/053849 describes coatings based
on water-based (meth)acrylate polymer dispersions, e.g.
styrene-acrylate polymer dispersions, for paper and paperboard. The
polymers exhibit good barrier properties with respect to liquid
oils and fats. However, it has been found that good barrier action
with respect to liquid oils and fats is not necessarily also
attended by good barrier action with respect to volatile mineral
oils, in particular with respect to mineral oils which penetrate in
the form of gas, e.g. paraffinic and naphthenic hydrocarbons which
are hazardous to health, and aromatic hydrocarbons, in particular
those having from 15 to 25 carbon atoms, since the transport
mechanisms involved for the penetrating substances differ. In the
case of liquid fats and oils, the transport takes place by way of
the fibers, relevant factors being capillary forces and surface
wetting. When problems arise with substances penetrating in the
form of gas, capillary action and wetting play no part, but instead
sorption, diffusion, and porosity are relevant. Fats and oils
moreover differ from hydrocarbons, i.e. from mineral oil
constituents, in their polarity, and hence in their behavior in
diffusion through barrier layers.
[0006] The patent application PCT/EP2011/054471, with priority date
before that of the present application, discloses aqueous polyester
dispersions of biodegradable polyesters. The polyester dispersions
are used inter alia for the coating of paper. Coatings thus
produced exhibit good barrier action with respect to vegetable oils
and fatty acids. No mention is made of any barrier action with
respect to mineral oils, in particular volatile substances.
[0007] Surprisingly, it has now been found that good barrier action
with respect to mineral oils, in particular to mineral oils
penetrating in the form of gas, can be achieved via coating of
paper or paperboard with aqueous polyester dispersions. In
particular, barrier action can be improved at the same weight per
unit area of coating by applying the polyester dispersion in at
least two layers to the paper or the paperboard. Since the
polyesters comprised in the dispersions are biodegradable, better
compostability of the coated packaging materials is moreover
achieved.
[0008] Accordingly, the present invention provides the use of
aqueous dispersions of at least one biodegradable polyester, as
defined here and hereinafter, in the form of a coating for
improving the barrier properties of packaging material made of
paper or paperboard with respect to mineral oils, in particular
with respect to volatile mineral oils, in particular with respect
to mineral oils that penetrate in the form of gas, specifically
those having from 15 to 25 carbon atoms, e.g. paraffinic and
naphthenic hydrocarbons which are hazardous to health, and aromatic
hydrocarbons.
[0009] Because the aqueous dispersions of the at least one
biodegradable polyester have a high level of barrier action with
respect to the abovementioned mineral oils, they are particularly
suitable for producing barrier coatings on paper or paperboard
which have been produced from recycled paper and which therefore
comprise mineral oil residues, in particular volatile mineral oil
residues, specifically those having from 15 to 25 carbon atoms,
e.g. paraffinic and naphthenic hydrocarbons which are hazardous to
health, and aromatic hydrocarbons.
[0010] Accordingly, one preferred embodiment of the invention
provides the use of aqueous dispersions of at least one
biodegradable polyester, as defined here and hereinafter, in the
form of a coating for improving the barrier properties of packaging
material made of paper or paperboard with respect to mineral oils,
where the packaging material has been produced at least to some
extent, generally to an extent of at least 30% by weight (% by
weight, based on total fiber mass), in particular to an extent of
at least 50% by weight, or completely, from
mineral-oil-contaminated recycling paper.
[0011] Accordingly, one preferred embodiment of the invention
provides the use of aqueous dispersions of at least one
biodegradable polyester, as defined here and hereinafter, in the
form of a coating for improving the barrier properties of paper or
paperboard, or of packaging material made of paper or paperboard,
with respect to mineral oils, where the paper or the paperboard, or
the packaging material, has been produced at least to some extent,
generally to an extent of at least 30% by weight (% by weight,
based on total fiber mass), in particular to an extent of at least
50% by weight, or completely, from mineral-oil-contaminated
recycling paper, in particular a packaging material of this type
which is intended for the packaging of food or drink. Among these
materials are sales packaging, such as cartons or paper products,
and also consumer packaging, for example disposable tableware, e.g.
plates, cups, or beakers made of paperboard.
[0012] The coating of the invention is found on at least one of the
paper surfaces or paperboard surfaces, or on at least one surface
of the packaging material. It can also form at least one, e.g. at
least one or in particular two, of a plurality of layers of a
multilayer coating of the paper, or of the paperboard, or of the
packaging material. The coating of the invention can have been
arranged directly on a surface of the sheet-like backing material
(paper or paperboard). Between the backing material and the coating
of the invention there can also, however, be other layers, e.g.
primer layers, further barrier layers, or colored or
black-and-white layers of printing inks. It is preferable that the
coating of the invention is found on the inner side of the
packaging material: the side facing toward the contents of the
package.
[0013] Adequate barrier action is generally achieved when the
weight per unit area of the coating is at least 1 g/m.sup.2, often
at least 2 g/m.sup.2, in particular at least 3 g/m.sup.2, and
specifically at least 5 g/m.sup.2, calculated as solids per m.sup.2
of the coated surface. The weight per unit area of the coating is
preferably in the range from 2 to 50 g/m.sup.2, in particular from
3 to 40 g/m.sup.2, specifically from 5 to 30 g/m.sup.2, calculated
as solids per m.sup.2 of the coated surface. The thickness of the
coating is accordingly on average at least 1 .mu.m, often at least
2 .mu.m, in particular at least 3 .mu.m, and specifically at least
5 .mu.m, e.g. in the range from 2 to 50 .mu.m, in particular from 3
to 40 .mu.m, specifically from 5 to 30 .mu.m.
[0014] One specific embodiment of the invention relates to the use
for the coating of paperboard, in particular paperboard which has
been produced at least to some extent, generally to an extent of at
least 30% by weight (% by weight, based on total fiber mass), in
particular to an extent of at least 50% by weight, or completely,
from mineral-oil-contaminated recycling paper. The weight per unit
area of the coating here is generally at least 2 g/m.sup.2, often
at least 3 g/m.sup.2, in particular at least 4 g/m.sup.2, and
specifically at least 5 g/m.sup.2, calculated as solids per m.sup.2
of the coated paperboard surface. It is preferable that the weight
per unit area of the coating is in the range from 3 to 50
g/m.sup.2, in particular from 4 to 40 g/m.sup.2, specifically from
5 to 30 g/m.sup.2, calculated as solids per m.sup.2 of the coated
paperboard surface. The thickness of the coating is accordingly on
average at least 2 .mu.m, often at least 3 .mu.m, in particular at
least 4 .mu.m, and specifically at least 5 .mu.m, e.g. in the range
from 2 to 50 .mu.m, in particular from 3 to 40 .mu.m, specifically
from 5 to 30 .mu.m.
[0015] Another embodiment of the invention relates to the use for
the coating of paper, in particular paper which has been produced
at least to some extent, generally to an extent of at least 30% by
weight (% by weight, based on total fiber mass), in particular to
an extent of at least 50% by weight, or completely, from
mineral-oil-contaminated recycling paper. The weight per unit area
of the coating here is generally at least 1 g/m.sup.2, often at
least 2 g/m.sup.2, in particular at least 3 g/m.sup.2, calculated
as solids per m.sup.2 of the coated paper surface. It is preferable
that the weight per unit area of the coating is in the range from 1
to 30 .mu./m.sup.2, in particular from 2 to 25 g/m.sup.2,
specifically from 3 to 20 g/m.sup.2, calculated as solids per
m.sup.2 of the coated paper surface. The thickness of the coating
is accordingly on average at least 1 .mu.m, often at least 2 .mu.m,
in particular at least 3 .mu.m, e.g. in the range from 12 to 30
.mu.m, in particular from 2 to 25 .mu.m, specifically from 3 to 20
.mu.m.
[0016] The coating of the invention can have one layer, or
preferably more than one layer, e.g. two, three, four, or five
layers arranged on one another, where these have been produced with
use of the aqueous polyester dispersion. The weight per unit area
of the individual layers of the coating will generally amount to at
least 0.5 g/m.sup.2, often at least 1 g/m.sup.2, in particular at
least 2 g/m.sup.2, specifically at least 3 g/m.sup.2, and is
typically in the range from 1 to 30 g/m.sup.2, in particular from 1
to 25 g/m.sup.2, specifically from 2 to 20 g/m.sup.2, or from 2 to
12 g/m.sup.2, calculated as solids per m.sup.2 of the coated
surface. It is preferable that the coating of the invention has at
least two, in particular two, three, four, or five, and
specifically two or three, layers arranged on one another, where
these have been produced with use of the aqueous polyester
dispersion. As far as the weight per unit area of the entire
coating is concerned, the statements made above are applicable.
[0017] Aqueous dispersions of biodegradable polyesters are known
from patent application PCT/EP2011/054471, the priority date of
which is before that of the present application, and from the prior
art cited therein, or can be produced by analogy with the method
described therein, the entire content of which is hereby
incorporated herein by way of reference.
[0018] Biodegradability generally means that the polyesters
decompose within an appropriate and demonstrable period of time.
The degradation generally takes place hydrolytically, and is
predominantly brought about via exposure to microorganisms, such as
bacteria, yeasts, fungi, and algae, or via the hydrolases comprised
therein. In one example of a method for determining
biodegradability, polyester is mixed with compost and stored for a
defined time. In ASTM D5338, ASTM D6400 and DIN V 54900,
CO.sub.2-free air is by way of example passed through ripened
compost during the composting process, and the compost is subjected
to a defined temperature profile. Biodegradability is defined here
as a percentage degree of biodegradation by taking the ratio of the
net amount of CO.sub.2 released from the specimen (after
subtraction of the amount of CO.sub.2 released by the compost
without specimen) to the maximum amount of CO.sub.2 that can be
released from the specimen (calculated from the carbon content of
the specimen). Biodegradable polyesters generally exhibit marked
signs of degradation after just a few days of composting, examples
being fungal growth, cracking, and perforation. Polyesters of this
type are known to the person skilled in the art and are available
commercially.
[0019] The polyesters comprised in the aqueous dispersions are
typically insoluble in water and are therefore present in the form
of particles in the dispersion used in the invention. The
weight-average diameter of the polymer particles (weight average
determined via light scattering) in said dispersions will not
generally exceed a value of 10 .mu.m, often 5 .mu.m, in particular
2000 nm, specifically 1500 nm, and is typically in the range from
50 nm to 10 .mu.m, often in the range from 100 nm to 5 .mu.m, in
particular in the range from 150 to 2000 nm, specifically in the
range from 200 to 1500 nm. It is preferable that less than 90% by
weight of the polymer particles do not exceed a diameter of 10
.mu.m, in particular 5 .mu.m, and specifically 2 .mu.m. Particle
size is determined in a manner known per se via light scattering on
dilute dispersions (from 0.01 to 1% by weight).
[0020] Biodegradable polyesters are by way of example the
polyesters from the groups of the aliphatic polyesters, aliphatic
copolyesters, and aliphatic-aromatic copolyesters. Other suitable
materials are blends of the abovementioned biodegradable polyesters
with one another, or blends with other biodegradable polymers which
are preferably insoluble in water, e.g. starch or polyalkylene
carbonates. Examples of these blends are blends made of at least
one aliphatic copolyester with at least one polymer from the group
of starch, polyalkylene carbonates, and aliphatic polyesters, e.g.
polylactic acid or polyhydroxyalkanoates, and also blends made of
at least one aliphatic-aromatic copolyester with at least one
polymer from the group of starch, polyalkylene carbonates, and
aliphatic polyesters, e.g. polylactic acid or
polyhydroxyalkanoates. The proportion of the biodegradable
polyester will generally amount to at least 30% by weight, in
particular at least 40% by weight, based on total solids content of
the dispersion.
[0021] In one preferred embodiment, dispersions are used in which
the polyester is sole polymer constituent insoluble in water, i.e.
sole dispersed polymer constituent, or the proportion of the
biodegradable polyester is at least 80% by weight, in particular at
least 90% by weight, based on total solids content of the
dispersion. In another embodiment, dispersions are used which
comprise, alongside the biodegradable polyester, at least one other
polymer constituent insoluble in water, i.e. dispersed polymer
constituent, where this is preferably likewise biodegradable. The
content of the biodegradable polyester will then generally be from
30 to 90% by weight, in particular from 40 to 80% by weight, based
on total solids content of the dispersion. The content of the
dispersed polymer constituent that is not the polyester is then
generally from 10 to 70% by weight, in particular from 20 to 60% by
weight, based on the total amount of the polymers dispersed in the
dispersion. Suitable other dispersed polymer constituents which can
be comprised, together with the polyester, in the dispersion are
preferably likewise biodegradable and by way of example selected
from starch and polyalkylene carbonates.
[0022] The number-average molecular weight MN of the polyesters
comprised in the dispersions used in the invention is typically in
the range from 5000 to 1 000 000 daltons, in particular in the
range from 8000 to 800 000 daltons, and specifically in the range
from 10 000 to 500 000 daltons. The weight-average molecular weight
Mw of the polymer is generally in the range from 20 000 to 5 000
000 daltons, often in the range from 30 000 daltons to 4 000 000
daltons, and in particular in the range from 40 000 to 2 500 000
daltons. The polydispersity index Mw/MN is generally at least 2,
and is often in the range from 3 to 20, in particular in the range
from 5 to 15. Molecular weight and polydispersity index can be
determined by way of example via gel permeation chromatography
(GPC) to DIN 55672-1.
[0023] The intrinsic viscosity of the polyesters is an indirect
measure of molecular weight and is typically in the range from 50
to 500 ml/g, often in the range from 80 to 300 ml/g, and in
particular in the range from 100 to 250 ml/g (determined to EN ISO
1628-1 at 25.degree. C. on a 0.5% by weight solution of the polymer
in o-dichlorobenzene/phenol (1:1 w/w)).
[0024] The polyesters comprised in the dispersions used in the
invention can be amorphous or semicrystalline.
[0025] In one preferred embodiment of the invention, the polyester
comprised in the dispersion is in essence unbranched, i.e. the
value of the degree of branching is generally <0.005 mol/kg, in
particular <0.001 mol/kg, and specifically <0.0005 mol/kg. In
another embodiment of the invention, the polyester is branched,
where the value of the degree of branching preferably does not
exceed 1 mol/kg, in particular 0.5 mol/kg, and specifically 0.3
mol/kg. The degree of branching is the number of monomer units
condensed into the molecule and having more than two, e.g. three,
four, five, or six, functional groups which are suitable for the
condensation process and which react to form bonds with carboxylic
acid groups or with hydroxy groups, an example being carboxylate,
OH, isocyanate (NCO), or NH.sub.2 groups (or ester- or
amide-forming derivatives thereof). The degree of branching of this
embodiment of the polyester is generally from 0.0005 to 1 mol/kg,
preferably from 0.001 to 0.5 mol/kg, and in particular from 0.005
to 0.3 mol/kg.
[0026] The biodegradable polyester is in particular one selected
from the group of the aliphatic polyesters, aliphatic copolyesters,
aliphatic-aromatic copolyesters, and mixtures of these.
[0027] An aliphatic polyester is a polyester composed exclusively
of aliphatic monomers. An aliphatic copolyester is a polyester
composed exclusively of at least two, in particular at least three,
aliphatic monomers, where the acid component and/or the alcohol
component preferably comprises at least two different monomers. An
aliphatic-aromatic copolyester is a polyester composed not only of
aliphatic monomers but also of aromatic monomers, where the acid
component preferably comprises at least one aliphatic acid and at
least one aromatic acid.
[0028] The aliphatic polyesters and copolyesters are in particular
polylactides (polylactic acid), polycaprolactone, block copolymers
of polylactide with poly-C.sub.2-C.sub.4-alkylene glycol, block
copolymers of polycaprolactone with poly-C.sub.2-C.sub.4-alkylene
glycol, or else the copolyesters defined hereinafter which are
composed of at least one aliphatic or cycloaliphatic dicarboxylic
acid or one ester-forming derivative thereof and of at least one
aliphatic or cycloaliphatic diol component, and also optionally
other components.
[0029] The term "polylactides" denotes polycondensates of lactic
acid. Suitable polylactides are described in WO 97/41836, WO
96/18591, WO 94/05484, U.S. Pat. No. 5,310,865, U.S. Pat. No.
5,428,126, U.S. Pat. No. 5,440,008, U.S. Pat. No. 5,142,023, U.S.
Pat. No. 5,247,058, U.S. Pat. No. 5,247,059, U.S. Pat. No.
5,484,881, WO 98/09613, U.S. Pat. No. 4,045,418, U.S. Pat. No.
4,057,537, and also in Adv. Mater. 2000, 12, 1841-1846. These
products are polymers based on lactide acid lactone (A), which is
converted via ring-opening polymerization to polylactide acid
polymers (B):
##STR00001##
[0030] The degree of polymerization n in formula (B) is in the
range from 1000 to 4000, preferably from 1500 to 3500, and
particularly preferably from 1500 to 2000 (number average). The
average molar masses (number average) of these products are, in
accordance with the degree of polymerization, in the range from
71000 to 284000 g/mol. Suitable polylactides are obtainable by way
of example from Cargill Dow LLC (e.g. PLA Polymer 404ID, PLA
Polymer 4040D, PLA Polymer 4031D, PLA Polymer 2000D, or PLA Polymer
1100) or from Mitsui Chemicals (Lactea). Other suitable materials
are diblock and triblock copolymers of polylactides with
poly-C.sub.2-C.sub.4-alkylene glycol, in particular with
polyethylene glycol). These block copolymers are marketed by way of
example by Aldrich (e.g. product number 659649). These are polymers
that have polylactide blocks and poly-C.sub.2-C.sub.4-alkylene
oxide blocks. These block copolymers are obtainable by way of
example via condensation of lactic acid or via ring-opening
polymerization of lactide acid lactone(A) in the presence of
poly-C.sub.2-C.sub.4-alkylene glycols.
[0031] Other biodegradable polyesters suitable in the invention are
polycaprolactones. The person skilled in the art understands these
to be polymers described by the formula D indicated below, where n
is the number of repeat units in the polymer, i.e. the degree of
polymerization.
##STR00002##
[0032] The degree of polymerization n in formula (D) is in the
range from 100 to 1000, preferably from 500 to 1000 (number
average). The number-average molar masses of these products are, in
accordance with the degree of polymerization, in the range from 10
000 g/mol to 100 000 g/mol. Particularly preferred polymers of the
formula (D) have average molar masses (number average) of 50 000
g/mol (CAPA 6500), 80 000 g/mol (CAPA 6800), and 100 000 g/mol
(CAPA FB 100). Polycaprolactones are generally produced via
ring-opening polymerization of .epsilon.-caprolactone (compound C)
in the presence of a catalyst. Polycaprolactones are obtainable
commercially from Solvay as CAPA polymers, e.g. CAPA 6100, 6250,
6500 or CAPA FB 100. Other suitable polymers are diblock and
triblock copolymers of polycaprolactone with
poly-C.sub.2-C.sub.4-alkylene glycols, in particular with
polyethylene glycols (=polyethylene oxides), i.e. polymers which
have at least one polycaprolactone block of the formula D and at
least one polyalkylene glycol block. These polymers can by way of
example be produced via polymerization of caprolactone in the
presence of polyalkylene glycols, for example by analogy with the
processes described in Macromolecules 2003, 36, pp 8825-8829.
[0033] Particular biodegradable polyesters suitable in the
invention are copolyesters composed of at least one aliphatic or
cycloaliphatic dicarboxylic acid or of one ester-forming derivative
thereof and of at least one aliphatic or cycloaliphatic diol
component, and also optionally of other components.
[0034] The polymer to be dispersed in the invention in particular
involves an aliphatic or aliphatic-aromatic copolyester consisting
essentially of: [0035] a) at least one dicarboxylic acid component
A, which is composed of [0036] a1) at least one aliphatic or
cycloaliphatic dicarboxylic acid or ester-forming derivatives of
these, or a mixture thereof (component a1), and [0037] a2)
optionally one or more aromatic dicarboxylic acids which have no
sulfonic acid group, or ester-forming derivatives of these, or a
mixture thereof (component a2), [0038] a3) optionally one or more
aromatic dicarboxylic acids which have at least one sulfonic acid
group, or ester-forming derivatives of these, or a mixture thereof
(component a3); [0039] b) at least one diol component B selected
from aliphatic and cycloaliphatic diols and mixtures of these;
[0040] c) optionally one or more other bifunctional compounds C
which react to form bonds with carboxylic acid groups or with
hydroxy groups; and [0041] d) optionally one or more compounds D
which have at least three, e.g. three, four, or five,
functionalities which react to form bonds with carboxylic acid
groups or with hydroxy groups; where the molar ratio of component A
to component B is generally in the range from 0.4:1 to 1:1, in
particular in the range from 0.6:1 to 0.99:1, and components A and
B generally account for at least 80% by weight, in particular at
least 90% by weight, and specifically at least 96% by weight, of
all of the ester-forming constituents of the polyester, or of the
total weight of the polyester.
[0042] The term "aliphatic copolyesters" here and hereinafter means
copolyesters which comprise, as component A, exclusively component
al). The term "aliphatic-aromatic copolyesters" here and
hereinafter means copolyesters which comprise, as component A,
condensed into the molecule not only component a1) but also
component a) and optionally a3).
[0043] The data in % by weight based on the ester-forming
constituents are based here and hereinafter on the constituents of
components A, B, C, and D in the form condensed into the molecule,
and therefore on the total mass of the polyester, and not on the
amounts used to produce the polyester, unless otherwise stated.
[0044] Acid component A in said copolyesters preferably comprises
[0045] a1) from 30 to 100 mol %, in particular from 35 to 90 mol %,
or from 40 to 90 mol %, of at least one aliphatic or at least one
cycloaliphatic dicarboxylic acid or ester-forming derivatives of
these, or a mixture thereof, [0046] a2) from 0 to 70 mol %, in
particular from 10 to 65 mol %, or from 10 to 60 mol %, of at least
one aromatic dicarboxylic acid or ester-forming derivative of
these, or a mixture thereof, [0047] a3) from 0 to 5 mol %, in
particular from 0 to 3 mol %, or from 0 to 2 mol %, of one or more
aromatic dicarboxylic acids which have at least one sulfonic acid
group, or ester-forming derivatives of these, or a mixture thereof,
where the molar percentages of components a1), a2), and a3) give a
total of 100%.
[0048] In preferred embodiments of the invention, aqueous
dispersions of copolyesters are used where acid component A of
these comprises the following constituents: [0049] a1) from 35 to
90 mol %, or from 40 to 90 mol %, and specifically from 60 to 90
mol %, of at least one aliphatic or at least one cycloaliphatic
dicarboxylic acid or ester-forming derivatives of these, or a
mixture thereof, [0050] a2) from 10 to 65 mol %, or from 10 to 60
mol %, and specifically from 10 to 40 mol %, of at least one
aromatic dicarboxylic acid or ester-forming derivative of these, or
a mixture thereof, [0051] a3) from 0 to 5 mol %, in particular from
0 to 3 mol %, or from 0 to 2 mol %, of one or more aromatic
dicarboxylic acids which have at least one sulfonic acid group, or
ester-forming derivatives of these, or a mixture thereof, where the
molar percentages of components a1), a2), and a3) give a total of
100%.
[0052] Acid component A can comprise, condensed into the molecule,
small amounts of a sulfonated aromatic dicarboxylic acid, e.g.
sulfoisophthalic acid, or a salt thereof, where the content of the
sulfonated carboxylic acid generally amounts to no more than 5 mol
%, often no more than 3 mol %, in particular no more than 2 mol %,
being by way of example in the range from 0.1 to 5 mol %, or from
0.1 to 3 mol %, or from 0.2 to 2 mol %, based on the total amount
of compounds of component A. In one embodiment of the invention,
the amount of sulfonated carboxylic acids is less than 1 mol %, in
particular less than 0.5 mol %, based on component A. In another
embodiment of the invention, these copolyesters comprise from 0.01
to 0.2 mmol/g, in particular from 0.05 to 0.15 mmol/g, of sulfonic
acid groups. In another embodiment of the invention, these
copolyesters comprise less than 0.05 mmol/g, in particular less
than 0.01 mmol/g, of sulfonic acid groups.
[0053] Among the preferred copolyesters, particular preference is
given to those in which the content of diol component B is from 98
to 102 mol %, in particular from 99 to 101 mol %, based on the
total amount of components a1), a2), and optionally a3).
[0054] Among the particularly preferred copolyesters, particular
preference is given to those in which the polyester-forming
constituents comprise no more than 2% by weight, in particular no
more than 1% by weight, based on the total weight of the polyester,
of one or more other bifunctional compounds C which react to form
bonds with carboxylic acid groups or with hydroxy groups.
[0055] Among the particularly preferred copolyesters, particular
preference is given to those in which the polyester-forming
constituents comprise no more than 2% by weight, in particular no
more than 1% by weight, based on the total weight of the polyester,
of one or more compounds D which have at least three, e.g. three,
four, or five, functionalities which react to form bonds with
carboxylic acid groups or with hydroxy groups.
[0056] In the preferred copolyesters, components a1), a2), a3), and
b) in particular account for from 96 to 100% by weight, in
particular from 98 to 100% by weight, of these copolyesters.
[0057] One specific embodiment of the invention involves aqueous
dispersions of semiaromatic or aliphatic-aromatic copolyesters
characterized via the following constitution: [0058] a1) from 60 to
80 mol %, often from 65 to 80 mol %, in particular from 66 to 75
mol %, based on the total amount of components al) and a2), of at
least one aliphatic dicarboxylic acid, or ester-forming derivative
of this, or a mixture thereof, and [0059] a2) from 20 to 40 mol %,
often from 20 to 35 mol %, in particular from 25 to 34 mol %, based
on the total amount of components a1) and a2), of terephthalic acid
or ester-forming derivatives of this, or a mixture thereof; [0060]
b) from 98 to 102 mol % of at least one diol component b) selected
from 1,3-propanediol and 1,4-butanediol and mixtures of these;
[0061] d) from 0.1 to 2% by weight, often from 0.2 to 2% by weight,
in particular from 0.3 to 1.8% by weight, and specifically from 0.4
to 1.5% by weight, based on the total amount of components a1) and
a2), respectively calculated as dicarboxylic acids, and b), of one
or more compounds D which have at least three functionalities which
react to form bonds with carboxylic acid groups or with hydroxy
groups; where components a1), a2), and b) account for from 80 to
99.8% by weight, in particular from 90 to 99.7% by weight, and
specifically from 95 to 99.6% by weight, of the polyester.
[0062] Aliphatic dicarboxylic acids al) which are suitable in the
invention generally have from 2 to 10 carbon atoms, preferably from
4 to 8 carbon atoms, and in particular 6 carbon atoms. They can be
either linear or branched acids. The cycloaliphatic dicarboxylic
acids that can be used for the purposes of the present invention
are generally those having from 7 to 10 carbon atoms and in
particular those having 8 carbon atoms. However, it is also
possible in principle to use dicarboxylic acids having a greater
number of carbon atoms, for example up to 30 carbon atoms. Examples
that may be mentioned are: malonic acid, succinic acid, glutaric
acid, 2-methylglutaric acid, 3-methylglutaric acid, adipic acid,
pimelic acid, azelaic acid, sebacic acid, fumaric acid,
2,2-dimethylglutaric acid, suberic acid,
1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic
acid, 1,3-cyclohexanedicarboxylic acid, diglycolic acid, itaconic
acid, maleic acid, and 2,5-norbornanedicarboxylic acid.
Ester-forming derivatives of the abovementioned aliphatic or
cycloaliphatic dicarboxylic acids which can equally be used and
which may be mentioned are in particular the
di-C.sub.1-C.sub.6-alkyl esters, e.g. dimethyl, diethyl,
di-n-propyl, diisopropyl, di-n-butyl, diisobutyl, di-t-butyl,
di-n-pentyl, diisopentyl, or di-n-hexyl ester. It is equally
possible to use anhydrides of the dicarboxylic acids. Preferred
dicarboxylic acids are succinic acid, adipic acid, sebacic acid,
azelaic acid, and brassylic acid, and also the respective
ester-forming derivatives of these, and mixtures thereof.
Particular preference is given to adipic acid, sebacic acid, or
succinic acid, and also to the respective ester-forming derivatives
of these, and mixtures thereof.
[0063] Aromatic dicarboxylic acids a2 that may be mentioned are
generally those having from 8 to 12 carbon atoms and preferably
those having 8 carbon atoms. Examples that may be mentioned are
terephthalic acid, isophthalic acid, 2,6-naphthoic acid, and
1,5-naphthoic acid, and also ester-forming derivatives thereof.
Particular mention may be made here of the di-C.sub.1-C.sub.6-alkyl
esters, e.g. dimethyl, diethyl, diethyl, di-n-propyl, diisopropyl,
di-n-butyl, diisobutyl, di-t-butyl, di-n-pentyl, diisopentyl, or
di-n-hexyl ester. The anhydrides of the dicarboxylic acids a2 are
equally suitable ester-forming derivatives. However, it is also in
principle possible to use aromatic dicarboxylic acids a2 having a
greater number of carbon atoms, for example up to 20 carbon atoms.
The aromatic dicarboxylic acids or ester-forming derivatives
thereof a2 can be used individually or in the form of mixture made
of two or more thereof. It is particularly preferable to use
terephthalic acid or ester-forming derivatives of this acid, e.g.
dimethyl terephthalate.
[0064] The sulfonated aromatic dicarboxylic acids and ester-forming
derivatives of these are typically those derived from the
abovementioned nonsulfonated aromatic dicarboxylic acids, and bear
one or two sulfonic acid groups. An example that may be mentioned
is sulfoisophthalic acid or a salt thereof, e.g. the sodium salt
(Nasip).
[0065] The diols B are generally selected from branched or linear
alkanediols having from 2 to 12 carbon atoms, preferably from 4 to
8 carbon atoms, or in particular 6 carbon atoms, or from
cycloalkanediols having from 5 to 10 carbon atoms.
[0066] Examples of suitable alkanediols are ethylene glycol,
1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,4-butanediol,
1,5-pentanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol,
2,2-dimethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol,
2-ethyl-2-isobutyl-1,3-propanediol, 2,2,4-trimethyl-1,6-hexanediol,
in particular ethylene glycol, 1,3-propanediol, 1,4-butanediol or
2,2-dimethyl-1,3-propanediol (neopentyl glycol); cyclopentanediol,
1,4-cyclohexanediol, 1,2-cyclohexanedimethanol,
1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, or
2,2,4,4-tetramethyl-1,3-cyclobutanediol. It is also possible to use
mixtures of various alkanediols. Diol component B in said
copolyesters is preferably selected from C.sub.2-C.sub.12
alkanediols and mixtures thereof. Preference is given to
1,3-propanediol and in particular to 1,4-butanediol.
[0067] If an excess of OH end groups is desired, an excess of
component B can be used. In one preferred embodiment, the molar
ratio of components used A:B can be in the range from 0.4:1 to
1.1:1, preferably in the range from 0.6:1 to 1.05:1, and in
particular in the range from 0.7:1 to 1.02:1. The molar ratio of
component A incorporated into the polymer to component B
incorporated into the polymer is preferably in the range from 0.8:1
to 1.01:1, with preference from 0.9:1 to 1:1, and in particular in
the range from 0.99:1 to 1:1.
[0068] The polyesters can comprise, condensed into the molecule,
not only components A and B but also further bifunctional
components C. Said bifunctional compounds have two functional
groups which react to form bonds with carboxylic acid groups or
preferably hydroxy groups. Examples of functional groups which
react with OH groups are in particular isocyanate groups, epoxy
groups, oxazoline groups, carboxy groups in free or esterified
form, and amide groups. Particular functional groups which react
with carboxy groups are hydroxy groups and primary amino groups.
These materials are particularly those known as bifunctional chain
extenders, in particular the compounds of groups c3) to c7). Among
components C are: [0069] c1) dihydroxy compounds of the formula
I
[0069] HO-[(A)-O].sub.m--H (I) in which A is a
C.sub.2-C.sub.4-alkylene unit, such as 1,2-ethanediyl,
1,2-propanediyl, 1,3-propanediyl, or 1,4-butanediyl, and m is an
integer from 2 to 250; [0070] c2) hydroxycarboxylic acids of the
formula IIa or IIb
[0070] ##STR00003## in which p is an integer from 1 to 1500 and r
is an integer from 1 to 4, and G is a radical selected from the
group consisting of phenylene, --(CH.sub.2).sub.q--, where q is an
integer from 1 to 5, --C(R)H--, and --C(R)HCH.sub.2, where R is
methyl or ethyl; [0071] c3) amino-C.sub.2-C.sub.12 alkanols,
amino-C.sub.5-C.sub.10 cycloalkanols, and mixtures thereof; [0072]
c4) diamino-C.sub.1-C.sub.8 alkanes; [0073] c5) 2,2'-bisoxazolines
of the general formula Ill
[0073] ##STR00004## where R.sub.1 is a single bond, a
(CH.sub.2).sub.z,-alkylene group, where z=2, 3, or 4, or a
phenylene group; [0074] c6) aminocarboxylic acids which by way of
example are selected from naturally occurring amino acids,
polyamides with a molar mass of at most 18000 g/mol, obtainable via
polycondensation of a dicarboxylic acid having from 4 to 6 carbon
atoms and of a diamine having from 4 to 10 carbon atoms, compounds
of the formulae IVa and IVb
[0074] ##STR00005## in which s is an integer from 1 to 1500 and t
is an integer from 1 to 4, and T is a radical selected from the
group consisting of phenylene, --(CH.sub.2).sub.u--, where u is an
integer from 1 to 12, --C(R.sup.2)H--, and --C(R.sup.2)HCH.sub.2,
where R.sup.2 is methyl or ethyl, and polyoxazolines having the
repeat unit V
##STR00006## in which R.sup.3 is hydrogen, C.sub.1-C.sub.6-alkyl,
C.sub.5-C.sub.8-cycloalkyl, unsubstituted phenyl or phenyl
substituted up to three times with C.sub.1-C.sub.4-alkyl groups, or
is tetrahydrofuryl; and [0075] c7) diisocyanates.
[0076] Examples of component c1 are diethylene glycol, triethylene
glycol, polyethylene glycol, polypropylene glycol, and
polytetrahydrofuran (polyTHF), particularly preferably diethylene
glycol, triethylene glycol, and polyethylene glycol, and it is also
possible here to use mixtures thereof, or compounds which have
different alkylene units A (see formula I), e.g. polyethylene
glycol which comprises propylene units (A=1,2- or 1,3-propanediyl).
The latter are obtainable by way of example via polymerization of
first ethylene oxide and then propylene oxide, by methods known per
se. Particular preference is given to copolymers based on
polyalkylene glycols having various variables A, where units formed
from ethylene oxide (A=1,2-ethanediyl) predominate. The molar mass
(number average M.sub.n) of the polyethylene glycol is generally
selected to be in the range from 250 to 8000 g/mol, preferably from
600 to 3000 g/mol.
[0077] In one of the embodiments it is possible by way of example
to use, for the production of the copolyesters, from 80 to 99.8 mol
%, preferably from 90 to 99.5 mol %, of the diols B, and from 0.2
to 20 mol %, preferably from 0.5 to 10 mol %, of the dihydroxy
compounds c1, based on the molar amount of B and c1.
[0078] Examples of preferred components c2 are glycolic acid, D-,
L-, or D,L-lactic acid, 6-hydroxyhexanoic acid, cyclic derivatives
thereof, e.g. glycolide (1,4-dioxane-2,5-dione), D- or L-dilactide
(3,6-dimethyl-1,4-dioxane-2,5-dione), p-hydroxybenzoic acid, and
also oligomers thereof, and polymers, such as 3-polyhydroxybutyric
acid, polyhydroxyvaleric acid, polylactide (obtainable by way of
example in the form of EcoPLA.RTM. (Cargill)), or else a mixture of
3-polyhydroxybutyric acid and polyhydroxyvaleric acid (the latter
being obtainable as Biopol.RTM. from Zeneca). The
low-molecular-weight and cyclic derivatives thereof are
particularly preferred for producing copolyesters. Examples of
amounts that can be used of the hydroxycarboxylic acids or their
oligomers and/or polymers are from 0.01 to 20% by weight,
preferably from 0.1 to 10% by weight, based on the amount of A and
B.
[0079] Preferred components c3 are amino-C.sub.2-C.sub.6 alkanols,
such as 2-aminoethanol, 3-aminopropanol, 4-aminobutanol,
5-aminopentanol, 6-aminohexanol, and also amino-C.sub.5-C.sub.6
cycloalkanols, such as aminocyclopentanol and aminocyclohexanol, or
a mixture thereof.
[0080] Preferred components c4) are diamino-C.sub.4-C.sub.6
alkanes, such as 1,4-diaminobutane, 1,5-diaminopentane, and
1,6-diaminohexane.
[0081] In one preferred embodiment, the amounts used for producing
the copolyesters are from 0.5 to 20 mol %, preferably from 0.5 to
10 mol %, of c3, based on the molar amount of B, and from 0 to 15
mol %, preferably from 0 to 10 mol %, of c4, based on the molar
amount of B.
[0082] Preferred bisoxazolines III of component c5) are those in
which R.sup.1 is a single bond, a (CH2).sub.z-alkylene group, where
z 32 2, 3, or 4, e.g. methylene, ethane-1,2-diyl, propane-1,3-diyl,
propane-1,2-diyl, or a phenylene group. Particularly preferred
bisoxazolines that may be mentioned are 2,2'-bis(2-oxazoline),
bis(2-oxazolinyl)methane, 1,2-bis(2-oxazolinyl)ethane,
1,3-bis(2-oxazolinyl)propane, or 1,4-bis(2-oxazolinyl)butane,
1,4-bis(2-oxazolinyl)benzene, 1,2-bis(2-oxazolinyl)benzene, or
1,3-bis(2-oxazolinyl)benzene. Bisoxazolines of the general formula
III are generally obtainable via the process of Angew. Chem. Int.
Edit., Vol. 11 (1972), pp. 287-288.
[0083] Examples of amounts that can be used for producing the
polyesters are from 80 to 98 mol % of B, up to 20 mol % of c3, e.g.
from 0.5 to 20 mol % of c3, up to 20 mol % of c4, e.g. from 0.5 to
20 mol %, and up to 20 mol % of c5, e.g. from 0.5 to 20 mol %,
based in each case on the total of the molar amounts of components
B, c3, c4, and c5. In another preferred embodiment it is possible
to use from 0.1 to 5% by weight of c5, preferably from 0.2 to 4% by
weight, based on the total weight of A and B.
[0084] Component c6 used can comprise naturally occurring
aminocarboxylic acids. Among these are valine, leucine, isoleucine,
threonine, methionine, phenylalanine, tryptophan, lysine, alanine,
arginine, aspartamic acid, cysteine, glutamic acid, glycine,
histidine, proline, serine, tryosine, asparagine, and
glutamine.
[0085] Preferred aminocarboxylic acids of the general formulae IVa
and IVb are those in which s is an integer from 1 to 1000 and t is
an integer from 1 to 4, preferably 1 or 2, and T is selected from
the group of phenylene and --(CH.sub.2).sub.u--, where u is 1, 5,
or 12.
[0086] c6 can also moreover be a polyoxazoline of the general
formula V. However, component c6 can also be a mixture of various
aminocarboxylic acids and/or polyoxazolines.
[0087] Amounts of c6 that can be used in one preferred embodiment
are from 0.01 to 20% by weight, preferably from 0.1 to 10% by
weight, based on the total amount of components A and B.
[0088] Component c7 used can comprise aromatic or aliphatic
diisocyanates. However, it is also possible to use isocyanates of
higher functionality. Examples of aromatic diisocyanates are
tolylene 2,4-diisocyanate, tolylene 2,6-diisocyanate,
diphenylmethane 2,2'-diisocyanate, diphenylmethane
2,4'-diisocyanate, diphenylmethane 4,4'-diisocyanate, naphthylene
1,5-diisocyanate, and xylylene diisocyanate. Examples of aliphatic
diisocyanates are especially linear or branched alkylene
diisocyanates or cycloalkylene diisocyanates having from 2 to 20
carbon atoms, preferably having from 3 to 12 carbon atoms, e.g.
hexamethylene 1,6-diisocyanate, isophorone diisocyanate, or
methylenebis(4-isocyanatocyclohexane). Other components c7 that can
be used are tri(4-isocyanatophenyl)methane, and also the
cyanurates, uretdiones, and biurets of the abovementioned
diisocyanates.
[0089] Amounts generally used of component c7, if desired, are from
0.01 to 5 mol %, preferably from 0.05 to 4 mol %, particularly
preferably from 0.1 to 4 mol %, based on the total of the molar
amounts of A and B.
[0090] Among other components which can optionally be used for
producing the polyesters are compounds D which comprise at least
three groups/functionalities which react with carboxylic acid
groups or with hydroxy groups, to form bonds. Particular examples
of functional groups which react with OH groups are isocyanate
groups, epoxy groups, oxazoline groups, carboxy groups in free or
esterified form, and amide groups. Particular functional groups
which react with carboxy groups are hydroxy groups and primary
amino groups. Compounds of this type are also termed crosslinking
agents. By using the compound D, it is possible to construct
biodegradable copolyesters which are pseudoplastic. The rheology of
the melts improves; the biodegradable copolyesters are easier to
process, for example easier to draw by melt-solidification
processes to give foils. The compounds D have a shear-thinning
effect, i.e. viscosity decreases under load. The compounds D
preferably comprise from 3 to 10, e.g. 3, 4, 5, or 6, functional
groups capable of forming ester bonds. Particularly preferred
compounds D have from three to six functional groups of this type
in the molecule, in particular from three to six hydroxy groups
and/or carboxy groups. Examples that may be mentioned are:
polycarboxylic acids and hydroxycarboxylic acids, e.g. tartaric
acid, citric acid, malic acid; trimesic acid; trimellitic acid,
trimellitic anhydride; pyromellitic acid, pyromellitic dianhydride,
and hydroxyisophthalic acid, and also polyols, such as
trimethylolpropane and trimethylolethane; pentaerythritol,
polyethertriols, and glycerol. Preferred compounds D are polyols,
preferably trimethylolpropane, pentaerythritol, and in particular
glycerol. The amounts used of the compounds D, insofar as these are
desired, are generally from 0.0005 to 1 mol/kg, preferably from
0.001 to 0.5 mol/kg, and in particular from 0.005 to 0.3 mol/kg,
based on total amount of components A, B, C, and D, or on the total
weight of the polyester. The amounts used of the compounds D,
insofar as these are desired, are preferably from 0.01 to 5% by
weight, in particular from 0.05 to 3% by weight, and in particular
from 0.1 to 2% by weight, and specifically from 0.2 to 2% by
weight, based on the total amount of components A, B, C, and D, or
on the total weight of the polyester.
[0091] It is generally advisable to add the crosslinking (at least
trifunctional) compounds D at a relatively early juncture in the
polycondensation process.
[0092] Production of the copolyesters preferred in the invention
can also use, alongside the abovementioned components A, B, and
optionally C, and optionally D, bi- or polyfunctional epoxides
(component E). Particularly suitable bi- or polyfunctional epoxides
are copolymers which contain epoxy groups and which are based on
styrene, acrylate, and/or methacrylate. The units bearing epoxy
groups are preferably glycidyl (meth)acrylates. Copolymers which
have proven successful are those having a proportion of greater
than 20% by weight, particularly preferably greater than 30% by
weight, and with particular preference greater than 50% by weight,
of glycidyl methacrylate, based on the copolymer. The epoxy
equivalent weight (EEW) in said polymers is preferably from 150 to
3000 g/equivalent and with particular preference from 200 to 500
g/equivalent. The average molecular weight (weight average) M.sub.W
of the polymers is preferably from 2000 to 25 000, in particular
from 3000 to 8000. The average molecular weight (number average)
M.sub.n of the polymers is preferably from 400 to 6000, in
particular from 1000 to 4000. Polydispersity (Q) is generally from
1.5 to 5. Copolymers of the abovementioned type, containing epoxy
groups, are marketed by way of example by BASF Resins B.V. with
trademark Joncryl.RTM. ADR. Joncryl.RTM. ADR 4368 is particularly
suitable as component E. Component E is usually used as chain
extender. In relation to the amount, the information given above
for component E, and in particular for components c2), c3), c4),
c5), and c6), is applicable.
[0093] Some of the copolyesters are known, e.g. from EP-A 488 617,
WO96/15173, and WO 04/67632, or can be produced by methods known
per se. It is particularly preferable to produce the copolyesters
by the continuous process described in EP application No.
08154541.0.
[0094] In one first embodiment, the copolyesters described are
synthesized in a two-stage reaction cascade. The general method
begins by reacting the dicarboxylic acids or their derivatives A
together with component B and optionally D in the presence of an
esterification catalyst (or if the carboxylic acids A are used in
the form of their esters, in the presence of a transesterification
catalyst) to give a prepolyester. The intrinsic viscosity (IV) of
said prepolyester is generally from 50 to 100 mL/g, preferably from
60 to 90 mL/g. The catalysts used generally comprise zinc
catalysts, aluminum catalysts, and in particular titanium
catalysts. An advantage of titanium catalysts, such as
tetra(isopropyl) orthotitanate and in particular tetrabutyl
orthotitanate (TBOT), over the tin catalysts, antimony catalysts,
cobalt catalysts, and lead catalysts often used in the literature,
an example being tin dioctanoate, is that if any residual amounts
of the catalyst or of downstream products of the catalyst remain
within the product, they are less toxic. This is a particularly
important factor for the biodegradable polyesters, since they pass
directly into the environment, by way of example in the form of
composting bags or mulch films. The polyesters of the invention are
then optionally chain-extended by the processes described in WO
96/15173 and EP-A 488 617. The prepolyester is, by way of example,
reacted with chain extenders C), e.g. with diisocyanates, or with
epoxy-containing polymethacrylates, in a chain-extension reaction
to give a polyester with IV of from 60 to 450 mL/g, preferably from
80 to 250 mL/g.
[0095] In another method, component A is first condensed in the
presence of an excess of component B and optionally D, together
with the catalyst. The melt of the resultant prepolyester is then
condensed, usually at an internal temperature of from 200 to
250.degree. C., while diol liberated is removed by distillation,
until the desired viscosity has been reached, the intrinsic
viscosity (IV) being from 60 to 450 mL/g, and preferably from 80 to
250 mL/g. Said condensation reaction generally takes place within a
period of from 3 to 6 hours at reduced pressure. A reaction with
the chain extender of component D then optionally follows.
[0096] It is particularly preferable to produce the copolyesters by
the continuous process described in EP application No. 08154541.0.
Here, by way of example, a mixture made of components A and B and
optionally of further comonomers is mixed to give a paste, without
addition of any catalyst, or as an alternative the liquid esters of
component A and component B and optionally further comonomers are
fed to the reactor, without addition of any catalyst, and [0097] 1.
in a first stage, said mixture is continuously esterified or,
respectively, transesterified together with the entire amount or a
portion of the catalyst; [0098] 2. in a second stage, optionally
with the remaining amount of catalyst, the transesterification or
esterification product obtained in 1.) is continuously
precondensed--preferably in a tower reactor, where the product
stream is conducted cocurrently by way of a falling-film cascade,
and the reaction vapors are removed in situ from the reaction
mixture--until an intrinsic viscosity of from 20 to 60 mL/g to DIN
53728 is reached; [0099] 3. in a third stage, the product
obtainable from 2.) is continuously polycondensed--preferably in a
cage reactor--until an intrinsic viscosity of from 70 to 130 mL/g
to DIN 53728 is reached and optionally [0100] 4. in a fourth stage,
the product obtainable from 3.) is continuously reacted in a
polyaddition reaction with a chain extender in an extruder, List
reactor, or static mixer, until an intrinsic viscosity of from 80
to 250 mL/g to DIN 53728 is reached.
[0101] The abovementioned intrinsic viscosity ranges serve merely
as guides to preferred process variants, and are not intended to
have any restricting effect on the subject matter of the present
application.
[0102] The copolyesters of the invention can be produced not only
by the continuous process described above but also in a batch
process. For this, components A, B, and optionally D are mixed in
any desired feed sequence and condensed to give a prepolyester. A
polyester with the desired intrinsic viscosity can be obtained with
the optional aid of component D.
[0103] The number-average molecular weight M.sub.N of the preferred
copolyesters is generally in the range from 5000 to 1 000 000
daltons, in particular in the range from 8000 to 800 000 daltons,
and specifically in the range from 10 000 to 500 000 daltons. The
weight-average molecular weight Mw of the copolyesters preferred in
the invention is generally in the range from 20 000 to 5 000 000
daltons, often in the range from 30 000 daltons to 4 000 000
daltons, and in particular in the range from 40 000 to 2 500 000
daltons. The polydispersity index M.sub.W/M.sub.N is generally at
least 2, and is often in the range from 3 to 25, in particular in
the range from 5 to 20. The copolyesters are preferably
semicrystalline and preferably have a melting point or melting
range in the range from 80 to 170.degree. C., in particular in the
range from 90 to 150.degree. C. The intrinsic viscosity of the
copolyesters is typically in the range from 50 to 500 ml/g, often
in the range from 80 to 300 ml/g, and in particular in the range
from 100 to 250 ml/g (determined to EN ISO 1628-1 at 25.degree. C.
on a 0.5% strength by weight solution of the polymer in
o-dichlorobenzene/phenol (1:1 w/w)). The preferred copolyesters are
characterized firstly via high melt viscosity .eta..sub.0, which at
180.degree. C. is generally at least 60 Pas, often at least 80 Pas,
in particular at least 100 Pas, e.g. from 60 to 20 000 Pas, in
particular from 80 to 15 000 Pas, and specifically from 100 to 10
000 Pas, and via a low acid number, which is less than 5 mg KOH/g
of polymer, in particular at most 3 mg KOH/g of polymer, and
specifically at most 1 mg KOH/g of polymer.
[0104] The copolyesters moreover preferably have in essence no
functional groups which make the polymers soluble in water.
Accordingly, the number of sulfonic acid groups in the copolyester
is generally less than 0.1 mmol/g of polymer, in particular less
than 0.05 mmol/g of polymer, or less than 0.01 mmol/g of
polymer.
[0105] The solids content of the aqueous dispersions of the
copolyester is generally in the range from 10 to 60% by weight, in
particular in the range from 20 to 55% by weight, and specifically
in the range from 30 to 50% by weight.
[0106] The viscosity of the dispersions used in the invention,
determined by the Brookfield method at 20.degree. C., is preferably
at most 5 Pas, often at most 2 Pas, e.g. in the range from 10 to
5000 mPas, in particular in the range from 50 to 2000 mPas
(measured by a Brookfield viscosimeter at 20.degree. C. and 20 rpm
with spindle 4).
[0107] The aqueous dispersion generally comprises, alongside the
dispersed polymers, at least one surfactant substance to stabilize
the polymer particles dispersed in the dispersion. The content of
surfactant substances will generally not exceed 20% by weight,
based on total solids content, being typically in the range from
0.1 to 20% by weight and often in the range from 0.2 to 10% by
weight, based on total solids content. Among the suitable
surfactant substances are polymeric surfactant substances with
molecular weights above 2000 daltons (number average), e.g. from
2200 to 10.sup.6 daltons, these generally being termed protective
colloids, and also low-molecular-weight surfactant substances with
molecular weights up to 2000 daltons, often up to 1500 daltons
(number average), these generally being termed emulsifiers. The
surfactant substances can be cationic, anionic, or neutral.
[0108] In one preferred embodiment of the invention, the aqueous
dispersion medium comprises at least one protective colloid, for
example one neutral, anionic, or cationic protective colloid,
optionally in combination with one or more emulsifiers.
[0109] Examples of protective colloids are water-soluble polymers,
e.g. [0110] neutral protective colloids: e.g. polysaccharides, for
example water-soluble starches, starch derivatives, and cellulose
derivatives, such as methylcellulose, hydroxypropylcellulose,
hydroxyethylcellulose, hydroxypropylmethylcellulose, and also
polyvinyl alcohols, inclusive of partially hydrolyzed polyvinyl
acetate with a degree of hydrolysis which is preferably at least
40%, in particular at least 60%, polyacrylamide,
polyvinylpyrrolidone, polyethylene glycols, graft polymers of vinyl
acetate and/or vinyl propionate onto polyethylene glycols, and
polyethylene glycols mono- or bilaterally end-group-capped with
alkyl, carboxy, or amino groups; [0111] anionic water-soluble
polymers, the main polymer chain of which has a plurality of
carboxy groups, sulfonic acid groups or, sulfonate groups, and/or
phosphonic acid groups or phosphonate groups, e.g.
carboxymethylcellulose, homo- and copolymers of ethylenically
unsaturated monomers which comprise at least 20% by weight, based
on the total amount of the monomers, of at least one ethylenically
unsaturated monomer which comprises at least one carboxy group,
sulfonic acid group, and/or phosphonic acid group incorporated
within the polymer, and salts of these, in particular the alkali
metal salts and ammonium salts. When the abovementioned anionic
water-soluble polymers are in an aqueous medium, the sulfonic acid
groups bonded to the main polymer chain are generally in the salt
form, i.e. in the form of sulfonate groups, the phosphonic acid
groups correspondingly being in the form of phosphonate groups. The
counterions are then typically alkali metal ions and alkaline earth
metal ions, examples being sodium ions, and calcium ions, and
ammonium ions (NH.sub.4.sup.+); [0112] cationic polymers, e.g.
polydiallyldimethylammonium salts, e.g. the chlorides; [0113]
anionically or cationically modified starches. Examples of
anionically modified starches are carboxymethylated starches and
n-octenylsuccinyl-modified starch, examples of these being
obtainable in the form of products from Cargill
(CEmCap/CEmTex/CDeliTex n-octenylsuccinylated starches). Examples
of cationically modified starches are starches modified with
2-hydroxy-3-(trimethylammonium)propyl groups, examples being
starches which are obtainable by reacting conventional starches
with N-(3-chloro-2-hydroxypropyl)trimethylammonium chloride
(CHPTAC), and which preferably have a degree of substitution of
from 0.02 to 0.1. The products Hi-Cat 21370 from Roquette and
Perlcore 134P from Lyckeby are examples of these.
[0114] Examples of the anionic water-soluble polymers of which the
main chain has a plurality of carboxy groups, sulfonic acid groups
or sulfonate groups, and/or phosphonic acid groups or phosphonate
groups, are: [0115] homo- and copolymers of monoethylenically
unsaturated monocarboxylic acids having from 3 to 6 carbon atoms
(hereinafter monoethylenically unsaturated C.sub.3-C.sub.6
monocarboxylic acids), examples being acrylic acid and methacrylic
acid, and salts thereof, in particular the alkali metal salts and
ammonium salts; [0116] copolymers of monoethylenically unsaturated
C.sub.3-C.sub.6 monocarboxylic acids with neutral monomers, e.g.
vinylaromatics, such as styrene, C.sub.1-C.sub.10-alkyl esters of
monoethylenically unsaturated C.sub.3-C.sub.6 monocarboxylic acids,
and/or C.sub.4-C.sub.6 dicarboxylic acids, examples being methyl
acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate,
propyl acrylate, propyl methacrylate, n-butyl acrylate, n-butyl
methacrylate, tert-butyl acrylate, tert-butyl methacrylate, n-hexyl
acrylate, n-hexyl methacrylate, hydroxyethyl esters, and in
particular hydroxyethyl and hydroxypropyl esters of the
abovementioned monoethylenically unsaturated C.sub.3-C.sub.6
monocarboxylic acids and/or C.sub.4-C.sub.6 dicarboxylic acids,
examples being hydroxyethyl acrylate, hydroxyethyl methacrylate,
hydroxypropyl acrylate and hydroxypropyl methacrylate, and also
vinyl esters of aliphatic carboxylic acids, examples being vinyl
acetate and vinyl propionate; [0117] homo- and copolymers of
monoethylenically unsaturated sulfonic acids, e.g. vinylsulfonic
acid, styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic
acid, 2-acryloxyethanesulfonic acid, 2-acryloxypropanesulfonic
acid, etc., and also copolymers thereof with the abovementioned
neutral monomers, and also the salts of the abovementioned homo-
and copolymers, in particular the alkali metal salts and ammonium
salts; [0118] homo- and copolymers of monoethylenically unsaturated
phosphonic acids, e.g. vinylphosphonic acid,
2-acrylamido-2-methylpropanephosphonic acid,
2-acryloxyethanephosphonic acid, 2-acryloxypropanephosphonic acid,
etc., and also copolymers thereof with the abovementioned neutral
monomers, and also the salts of the abovementioned homo- and
copolymers, in particular the alkali metal salts and ammonium
salts; where the proportion of the neutral comonomers in the
abovementioned copolymers generally does not exceed a proportion of
80% by weight, in particular 70% by weight, based on the total
amount of the monomers constituting the copolymer.
[0119] Particular anionic water-soluble polymers, the main chain of
which has a plurality of sulfonate groups, are also [0120]
water-soluble copolyesters which have an amount of from 0.3 to 1.5
mmol/g of polyester, in particular from 0.5 to 1.0 mmol/g of
polyester, of aromatically bonded sulfonic acid groups and,
respectively, sulfonate groups, and salts of these, in particular
the alkali metal salts and ammonium salts thereof, where the
water-soluble copolyesters are preferably composed of: [0121] i)
from 6 to 30 mol %, based on the total amount of components i),
ii), and iii), of at least one aromatic dicarboxylic acid which has
at least one sulfonate group and which is preferably selected from
5-sulfoisophthalic acid or from salts thereof, in particular the
sodium salt of sulfoisophthalic acid, or ester-forming derivatives
thereof; [0122] ii) optionally one or more aromatic dicarboxylic
acids which have no sulfonyl groups and which are preferably
selected from terephthalic acid and isophthalic acid and mixtures
thereof, or ester-forming derivatives thereof; [0123] iii)
optionally one or more aliphatic or cycloaliphatic dicarboxylic
acids, or ester-forming derivatives thereof; [0124] iv) from 95 to
105 mol %, based on the total amount of components i), ii), and
iii), of one or more aliphatic diols, e.g. ethylene glycol,
1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,4-butanediol,
1,5-pentanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol,
2,2-dimethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol,
2-ethyl-2-isobutyl-1,3-propanediol, 2,2,4-trimethyl-1,6-hexanediol,
in particular ethylene glycol, 1,3-propanediol, 1,4-butanediol or
2,2-dimethyl-1,3-propanediol (neopentyl glycol), [0125] where the
total amount of components ii) and iii) makes up from 70 to 94 mol
%, based on the total amount of components i), ii) and iii), where
components i), ii), iii), and iv) generally make up at least 99% by
weight of all of the ester-forming constituents of the polyester
(based on the components comprised within the polyester).
Water-soluble copolyesters of this type are known by way of example
from U.S. Pat. No. 6,521,679, the disclosure of which is hereby in
its entirety incorporated herein by way of reference.
[0126] Examples of familiar nonionic emulsifiers are
C.sub.2-C.sub.3-alkoxylated, in particular ethoxylated, mono-, di-,
and trialkylphenols (degree of ethoxylation from 3 to 50, alkyl
radical: C.sub.4 to C.sub.12), and also
C.sub.2-C.sub.3-alkoxylated, in particular ethoxylated, fatty
alcohols (degree of ethoxylation from 3 to 80; alkyl radical:
C.sub.8 to C.sub.36). Examples of these are the Lutensol.RTM. A
grades (C.sub.12 to C.sub.14 fatty alcohol ethoxylates, degree of
ethoxylation from 3 to 8), Lutensol.RTM. AO grades (C.sub.13 to
C.sub.15 oxo alcohol ethoxylates, degree of ethoxylation from 3 to
30), Lutensol.RTM. AT grades (C.sub.16 to C.sub.18 fatty alcohol
ethoxylates, degree of ethoxylation from 11 to 80), Lutensol.RTM.
ON grades (C10 oxo alcohol ethoxylates, degree of ethoxylation from
3 to 11), and the Lutensol.RTM. TO grades (C13 oxo alcohol
ethoxylates, degree of ethoxylation from 3 to 20), from BASF
SE.
[0127] Conventional anionic emulsifiers are the salts of
amphiphilic substances which have an anionic functional group, such
as a sulfonate, phosphonate, sulfate, or phosphate group. Examples
of these are the salts, in particular the alkali metal salts and
ammonium salts, of alkyl sulfates (alkyl radical: C.sub.8 to
C.sub.12), the salts, in particular the alkali metal salts and
ammonium salts, of amphiphilic compounds which have a sulfated or
phosphated oligo-C.sub.2-C.sub.3-alkylene oxide group, in
particular a sulfated or phosphated oligoethylene oxide group,
examples being the salts, in particular the alkali metal salts and
ammonium salts, of sulfuric acid hemiesters of ethoxylated alkanols
(degree of ethoxylation from 2 to 50, in particular from 4 to 30,
alkyl radical: C.sub.10 to C.sub.30, in particular C.sub.12 to
C.sub.18), the salts, in particular the alkali metal salts and
ammonium salts, of sulfuric acid hemiesters of ethoxylated
alkylphenols (degree of ethoxylation from 2 to 50, alkyl radical:
C.sub.4 to C.sub.12), the salts, in particular the alkali metal
salts and ammonium salts, of phosphoric acid hemiesters of
ethoxylated alkanols (degree of ethoxylation from 2 to 50, in
particular from 4 to 30, alkyl radical: C.sub.10 to C.sub.30, in
particular C.sub.12 to C.sub.18), the salts, in particular the
alkali metal salts and ammonium salts, of phosphoric acid
hemiesters of ethoxylated alkylphenols (degree of ethoxylation from
2 to 50, alkyl radical: C.sub.4 to C.sub.12), the salts, in
particular the alkali metal salts and ammonium salts, of
alkylsulfonic acids (alkyl radical: C.sub.12 to C.sub.18), the
salts, in particular the alkali metal salts and ammonium salts, of
alkylarylsulfonic acids (alkyl radical: C.sub.9 to C.sub.18), and
also the salts, in particular the alkali metal salts and ammonium
salts, of alkylbiphenyl ether sulfonic acids (alkyl radical:
C.sub.6 to C.sub.18), an example being the product marketed as
Dowfax.RTM. 2A1.
[0128] Suitable cationic emulsifiers are generally cationic salts
having a C.sub.6-C.sub.18-alkyl, C.sub.1-C.sub.10-alkylaryl, or
heterocyclic radical, examples being primary, secondary, tertiary,
and quaternary ammonium salts, alkanolammonium salts, pyridinium
salts, imidazolinium salts, oxazolinium salts, morpholinium salts,
thiazolinium salts, and also salts of amine oxides, quinolinium
salts, isoquinolinium salts, tropylium salts, sulfonium salts, and
phosphonium salts, in particular the appropriate sulfates,
methosulfates, acetates, chlorides, bromides, phosphates, and
hexafluorophosphates, and the like. Examples that may be mentioned
are dodecylammonium acetate or the corresponding sulfate, the
sulfates or acetates of the various paraffinic esters which involve
the 2-(N,N,N-trimethylammonium)ethyl radical, N-cetylpyridinium
sulfate, N-laurylpyridinium sulfate, and also
N-cetyl-N,N,N-trimethylammonium sulfate,
N-dodecyl-N,N,N-trimethylammonium sulfate,
N-octyl-N,N,N-trimethylammonium sulfate,
N,N-distearyl-trimethylammonium N,N-dimethylammonium sulfate, and
also the Gemini surfactant N,N'-(lauryldimethyl)ethylenediamine
disulfate, ethoxylated tallow fatty alkyl-N-methylammonium sulfate,
and ethoxylated oleylamine (for example Uniperol.RTM. AC from BASF
SE, about 12 ethylene oxide units).
[0129] In one preferred embodiment of the invention, the aqueous
dispersion comprises at least one neutral protective colloid, in
particular one neutral, protective colloid bearing OH groups,
optionally in combination with one or more emulsifiers, preferably
anionic or nonionic emulsifiers, in particular anionic emulsifiers
which bear a sulfate or sulfonate group. Examples of neutral
protective colloids bearing OH groups are polysaccharides, e.g.
water-soluble starches, starch derivatives, and cellulose
derivatives, such as methylcellulose, hydroxypropylcellulose,
hydroxyethylcellulose, hydroxypropylmethylcellulose,
carboxymethylcellulose, and also polyvinyl alcohols, inclusive of
partially hydrolyzed polyvinyl acetate having a degree of
hydrolysis which is preferably at least 40%, in particular at least
60%. In particular, the neutral protective colloid bearing OH
groups has been selected from polyvinyl alcohols, inclusive of
partially hydrolyzed polyvinyl acetates having a degree of
hydrolysis which is preferably at least 40%, in particular at least
60%.
[0130] The dispersions of biodegradable polyesters can be produced
by analogy with the method in the patent application
PCT/EP2011/054471, the priority date of which is previous to that
of the present application. Here, a composition which comprises the
polyester and which is generally composed of at least 99% by weight
of the polyester, or of a blend of the polyester with a different
polymer, and optionally of one or more surfactant substances, is
introduced, at a temperature above the melting point or softening
point of the polyester or of the blend, into an aqueous dispersion
medium which generally comprises at least one surfactant substance,
and the resultant aqueous emulsion is quenched. The introduction of
the composition of the polymer into the aqueous dispersion medium
generally takes place in a mixing apparatus which has at least one
rotor-stator mixer.
[0131] In this process, the temperature at which the thermoplastic
polyester is introduced into the aqueous dispersion medium is, in
the case of an amorphous polyester, a temperature above the
softening point of the polyester, and in the case of a crystalline
or semicrystalline polyester it is above the melting point of the
polyester. The term "softening point" of amorphous polyesters means
the temperature corresponding to the glass transition temperature
as can be determined by way of example by means of dynamic
differential calorimetry (DSC) to ASTM D3418 or preferably to DIN
53765, or via dynamic mechanical analysis (DMA). The term "melting
point" is the temperature which leads to melting or softening of
the polyester and which can be determined in a manner known per se
by means of dynamic differential calorimetry (DSC) to DIN 53765 or
differential thermoanalysis (DTA).
[0132] The term "amorphous polyester" means a polyester which
comprises less than 1% by weight of crystalline regions. The term
"crystalline" or "semicrystalline" polyester means a polyester
which comprises more than 1% by weight, in particular at least 5%
by weight, of crystalline regions. The degree of crystallinity of a
polyester can be determined in a manner known per se via X-ray
diffractometry or via thermochemical methods, such as DTA or DSC,
in a manner known per se.
[0133] The rotor-stator mixers used to produce the aqueous
dispersion of the biodegradable polyester are familiar to the
person skilled in the art and in principle comprise all of the
types of dynamic mixer in which a high-speed, preferably
rotationally symmetrical, rotor interacts with a stator to form one
or more operating regions which in essence have the shape of an
annular gap. Within said operating regions, the material to be
mixed is subjected to severe shear stresses, and high levels of
turbulence often prevail in these annular gaps, and likewise
promote the mixing process. The rotor-stator apparatus is operated
at a relatively high rotation rate, generally from 1000 to 20000
rpm. This gives high peripheral velocities and a high shear rate,
thus subjecting the emulsion to severe shear stresses, which lead
to effective communition of the melt and thus to very effective
emulsification. Among the rotor-stator mixers are by way of example
toothed-ring dispersers, annular-gap mills, and colloidal
mills.
[0134] Preference is given to those rotor-stator mixers which have
means of generating cavitation forces. Means of this type can be
elevations arranged on the rotor side and/or on the stator side,
where these protrude into the mixing chamber and which have at
least one area where the normal has a tangential fraction, examples
being pins, teeth, or knives or coaxial rings with radially
arranged slots. The rotor-stator mixer preferably has, on the side
of the rotor, at least one toothed ring arranged so as to be
rotationally symmetrical, and/or at least one ring which has radial
slots (tooth gaps) arranged so as to be rotationally symmetrical.
Apparatuses of this type are also termed toothed-ring dispersers or
toothed-ring dispersing machines. In particular, the rotor-stator
mixer has, on the side of the rotor and also on the side of the
stator, at least one toothed ring arranged so as to be rotationally
symmetrical, and/or at least one ring with radial slots (tooth
gaps), where the (toothed) rings on the side of the rotor and on
the side of the stator are arranged coaxially and undergo mutual
intermeshing to form an annular gap.
[0135] In one particularly preferred embodiment, the rotor-stator
mixer is a toothed-ring dispersing machine which has a conical
stator with a concentric frustoconical recess, and which has a
likewise concentric conical rotor, where the rotor protrudes into
the frustoconical operating chamber of the stator in such a way as
to form an annular operating chamber, into which teeth protrude on
the side of the rotor and of the stator, and these are respectively
arranged on the rotor and the stator in such a way as to take the
form of one or more, e.g. two, three, or four coaxial toothed rings
on the side of the rotor and of one or more, e.g. one, two, three,
or four coaxial toothed rings on the side of the stator, and in
such a way that the toothed rings undergo mutual offset
intermeshing. Apparatuses of this type are known to the person
skilled in the art by way of example from DE 10024813 A1 and US
2002/076639, and are supplied by way of example by Cavitron
Verfahrenstechnik v. Hagen & Funke GmbH, Sprockhovel,
Germany.
[0136] The composition of the polyester is generally mixed with the
aqueous dispersion medium at a temperature above the softening
point of the polymer. To this end, the composition of the polyester
is usually heated to a temperature above the softening point and
introduced, preferably continuously, into the mixing apparatus. The
required amount of aqueous dispersion medium is similarly,
preferably continuously, introduced into the mixing apparatus. The
amount of dispersion medium here is generally selected in such a
way as to give the desired solids content of the dispersion.
However, it is also possible to use a larger amount of the
dispersion medium and then to concentrate the resultant dispersion.
It is equally possible to begin by producing a relatively
concentrated dispersion and to dilute this with further dispersion
medium and/or water. The mass ratio of polymer introduced to the
total amount of aqueous dispersion medium is typically in the range
from 1:20 to 1.2:1, often in the range from 1:10 to 1:1.1, and in
particular in the range from 1:3 to 1:1. In the case of continuous
addition of polymer and of aqueous dispersion medium, the mass
ratio of the streams of materials introduced is within the
abovementioned ranges. In the case of multistage addition of
dispersion medium, the mass ratio of polymer introduced to the
total amount of aqueous dispersion medium introduced in the first
to the penultimate stage can also be up to 4:1 or up to 2.3:1. It
is preferable that polymer and aqueous dispersion medium are
introduced at a constant addition rate, i.e. that the mass ratio of
thermoplastic polymer to dispersion medium is constant during the
process, or does not deviate by more than 10% from the preselected
mass ratio.
[0137] The temperature at which the composition of the polyester is
introduced into the aqueous dispersion medium is typically a
temperature which is at least 5 K, often at least 10 K, and in
particular at least 20 K, e.g. from 5 to 150 K, often from 10 to
100 K, and in particular from 20 to 80 K, above the melting point
or softening point of the composition. This temperature is also
termed mixing temperature hereinafter. The temperature at which the
composition is introduced into the aqueous dispersion medium is
generally a temperature of at most 300.degree. C., e.g. from 50 to
300.degree. C., often from 60 to 250.degree. C., and in particular
from 100 to 200.degree. C.
[0138] Because the mixing temperature is comparatively high, the
pressure at which the composition is introduced into the aqueous
dispersion medium is usually above atmospheric pressure, generally
being a pressure in the range from 1 to 50 bar, often from 1.1 to
40 bar, in particular in the range from 1.5 to 20 bar.
[0139] The mixing procedure can be carried out in one or more, e.g.
two, three, four, or five, stages, where at least one stage is
carried out in a rotor-stator mixer. In the case of a multistage
process, it is preferable to carry out all of the stages in
rotor-stator mixers.
[0140] In one first embodiment of the invention, the mixing takes
place in one stage, i.e. the mixing apparatus comprises a
rotor-stator mixer. In this process, the amounts of composition and
dispersion medium required to produce the dispersion are generally
introduced into the rotor-stator mixer. A method that has proven
successful for this heats the dispersion medium, prior to
introduction, to the desired mixing temperature or a temperature of
at least 20 K below the mixing temperature, and preferably to a
temperature in the range mixing temperature +/-20 K.
[0141] In a second, preferred embodiment of the invention, the
mixing takes place in a plurality of stages, i.e. in a mixing
apparatus which has a plurality of, e.g. two, three, four, or five,
in particular three or four, rotor-stator mixers connected to one
another in series. In a method which has proven successful here,
the composition of the polyester and a portion of the dispersion
medium are added to the first stage, i.e. to the first rotor-stator
mixer, where they are mixed at a temperature above the melting or
softening point of the composition, using the portion of the
aqueous dispersion medium. The portion of the dispersion medium
added to the first stage here is usually from 10 to 60% by weight,
in particular from 15 to 40% by weight, based on the total amount
of the dispersion medium introduced into the mixing apparatus. The
introduction of the composition into the portion of the aqueous
dispersion medium typically takes place here at a temperature which
is at least 5 K, often at least 10 K, and in particular at least 20
K, e.g. in the range from 5 to 150 K, often in the range from 10 to
100 K, and in particular in the range from 20 to 80 K, above the
melting or softening point of the composition. The mixing
temperature in the first rotor-stator mixer is generally at most
300.degree. C., being by way of example in the range from 50 to
300.degree. C., often from 80 to 250.degree. C., and in particular
from 100 to 200.degree. C. In a method which has proven successful
for this, the portion of dispersion medium introduced into the
first rotor-stator mixer is heated, prior to introduction, to the
desired mixing temperature or to a temperature which is at least 20
K below the mixing temperature, preferably to a temperature in the
range mixing temperature +/31 20 K. The aqueous dispersion produced
in the first rotor-stator mixer is then transferred to a further
rotor-stator mixer, where it is mixed with a further portion, or
with the remaining portion, of the dispersion medium. There can be,
for example, 1 or 2 further rotor-stator mixers following the
second rotor-stator mixer, and the dispersion produced in the
second rotor-stator mixer is mixed in the optional further
rotor-stator mixer(s), e.g. in the third rotor-stator mixer, with
the remaining amount, or with a further portion, of the aqueous
dispersion medium. The temperature at which the dispersion produced
in the first rotor-stator mixer is mixed with further dispersion
medium in the second rotor-stator mixer can be the same as the
temperature in the first rotor-stator mixer, or higher or lower. It
is preferably below the temperature in the first rotor-stator
mixer. In a method which has proven particularly successful, the
mixing temperature in the first of the rotor-stator mixers
connected to one another in series is at least 20 K, preferably at
least 30 K, e.g. from 20 to 200 K, in particular from 30 to 120 K,
above the temperature in the last of the rotor-stator mixers
connected to one another in series. In particular, the temperature
in the last of the rotor-stator mixers connected to one another in
series is at least 5 K, in particular at least 10 K, e.g. from 5 to
200 K, in particular from 10 to 150 K, below the melting or
softening point of the composition.
[0142] In one preferred embodiment of the invention, the
composition of the polyester and the aqueous dispersion medium are
simultaneously introduced, preferably continuously, and in
particular at a constant rate by volume, into the rotor-stator
mixer(s), and the dispersion is removed in similar fashion.
[0143] However, it is also possible, in a preceding step, to mix
the composition of the polyester with the aqueous dispersion
medium, thus obtaining a primary emulsion, at a temperature above
the melting or softening point of the composition of the polyester,
and to introduce this mixture to the rotor-stator mixer. Said
preceding step is preferably carried out in a kneader or extruder.
The resultant pre-emulsion is then introduced into the rotor-stator
mixer(s). It is preferable that the pre-emulsion is kept at a
temperature above the melting or softening point of the composition
of the polyester.
[0144] The aqueous emulsion which is initially obtained and which
is produced in the mixing apparatus, and which comprises the
polymer in the aqueous dispersion medium, is then, i.e. after
discharge from the mixing apparatus, quenched, i.e. rapidly cooled
to a temperature below the softening point of the composition of
the polyester, in order to avoid agglomeration of the polymer
particles in the emulsion. The quenching process can be undertaken
in a manner which is conventional per se, for example by using
suitable cooling apparatuses and/or via dilution with cooled
dispersion medium. The residence time of the emulsion at
temperatures above the melting or softening point of the polymer,
after discharge from the mixing apparatus, should preferably be no
longer than 20 s, in particular no longer than 10 s. In the case of
a mixing apparatus which has a plurality of rotor-stator mixers
connected to one another in series, the quenching process can also
take place in the second and the optional further rotor-stator
mixers.
[0145] The dispersions suitable for use in the invention can be
composed solely of water, optionally of surfactant substance, and
of the polymers dispersed in water. However, the dispersion can
also comprise further additives, e.g. fillers, antiblocking agents,
dyes, leveling agents, thickeners for adjusting rheology, or
wetting aids. These additions will generally account for no more
than 50% by weight, based on total solids content of the
dispersion. Said additions are generally added after the dispersion
of the polymer(s) of the dispersion. In one embodiment of the
invention, the aqueous dispersion of the polyester comprises up to
50% by weight, based on total solids content of the dispersion, of
one or more lamellar pigments. Examples of lamellar pigments are
talc powder, clay, and mica. Talc powder is preferred. Preferred
shape factors (length to thickness ratio) are greater than 10.
[0146] The present invention also provides a process for producing
a barrier coating on paper or paperboard, comprising application of
at least one aqueous dispersion of at least one biodegradable
polyester, as defined here, to at least one surface of the paper or
paperboard.
[0147] The aqueous dispersion(s) of the at least one biodegradable
polyester (hereinafter polymer dispersion) can be applied in a
manner known per se. By way of example, the polymer dispersion can
be applied by using suitable coating machinery to apply the polymer
dispersion to the backing material, i.e. paper or paperboard. To
the extent that materials in the form of webs are used, the polymer
dispersion is usually applied from a trough by way of an applicator
roll and leveled with the aid of an airbrush. Other successful
methods of applying the polymer dispersion use, for example, the
reverse gravure process, spray processes, or a doctor roller, or
other coating methods known to the person skilled in the art. At
least one side of the backing substrate here is provided with a
coating, i.e. single- or double-sided coating of the substrate is
possible. Preferred application processes for paper and paperboard
are curtain coating, airbrush coating, bar coating, and doctor
coating. Once the aqueous polymer dispersion has been applied to
the backing substrates, volatile constituents, especially water,
are vaporized. An example of a method for this, in continuous
operation, passes the material through a drying tunnel, which can
have been equipped with an infrared irradiation apparatus. The
coated and dried packaging material is then usually passed over a
cooling roll, and finally reeled.
[0148] The amount of the polymer dispersion generally applied to
the backing substrate is at least 1 g/m.sup.2, often at least 2
g/m.sup.2, in particular at least 3 g/m.sup.2, and specifically at
least 5 g/m.sup.2, calculated as solid per m.sup.2 of the coated
surface. The amount of the polymer dispersion applied to the
backing substrate is preferably from 2 to 50 g/m.sup.2, in
particular from 3 to 40 g/m.sup.2, specifically from 5 to 30
g/m.sup.2, calculated as solid per m.sup.2 of the coated surface.
The resultant thickness of the coating is accordingly on average at
least 1 .mu.m, often at least 2 .mu.m, in particular at least 3
.mu.m, and specifically at least 5 .mu.m, e.g. in the range from 2
to 50 .mu.m, in particular from 3 to 40 .mu.m, specifically from 5
to 30 .mu.m.
[0149] One specific embodiment of the invention provides a process
for the coating of paperboard, in particular paperboard which has
been produced at least to some extent, generally to an extent of at
least 30% by weight (% by weight, based on total fiber mass), in
particular to an extent of at least 50% by weight, or completely,
from mineral-oil-contaminated recycling paper. The total amount of
the polymer dispersion (based on the total amount of the layers)
applied here to the surface of the paperboard to be coated is
generally at least 2 g/m.sup.2, often at least 3 g/m.sup.2, in
particular at least 4 g/m.sup.2, and specifically at least 5
g/m.sup.2, calculated as solid per m.sup.2. It is preferable that
the total amount of the dispersion applied to the paperboard
surface to be coated is in the range from 3 to 50 g/m.sup.2, in
particular from 4 to 40 g/m.sup.2, specifically from 5 to 30
g/m.sup.2, calculated as solid per m.sup.2. The thickness of the
coating is accordingly on average at least 2 .mu.m, often at least
3 .mu.m, in particular at least 4 .mu.m, and specifically at least
5 .mu.m, e.g. in the range from 2 to 50 .mu.m, in particular from 3
to 40 .mu.m, specifically from 5 to 30 .mu.m.
[0150] Another embodiment of the invention provides a process for
the coating of paper, in particular paper which has been produced
at least to some extent, generally to an extent of at least 30% by
weight (% by weight, based on total fiber mass), in particular to
an extent of at least 50% by weight, or completely, from
mineral-oil-contaminated recycling paper. The total amount of the
polymer dispersion (based on the total amount of the layers)
applied here to the surface of the paper to be coated is generally
at least 1 g/m.sup.2, often at least 2 g/m.sup.2, in particular at
least 3 g/m.sup.2, calculated as solid per m.sup.2. It is
preferable that the total amount of the dispersion applied to the
paper surface to be coated is in the range from 1 to 30 g/m.sup.2,
in particular from 2 to 25 g/m.sup.2, specifically from 3 to 20
g/m.sup.2, calculated as solid per m.sup.2. The thickness of the
coating is accordingly on average at least 1 .mu.m, often at least
2 .mu.m, in particular at least 3 .mu.m, e.g. in the range from 12
to 30 .mu.m, in particular from 2 to 25 pm, specifically from 3 to
20 .mu.m.
[0151] In a method that has proven advantageous here, a first layer
is produced in a first step via application of the aqueous
dispersion to a surface of the paper or paperboard, and preferably
then in at least one further step, e.g. in one, two, three, or four
further steps, in particular in one or two further steps, at least
one further layer arranged on the first layer is produced via
application of the aqueous dispersion to the first layer obtained
in the first step. Drying steps can be implemented between the
individual steps. However, the individual coatings can also be
applied wet-on-wet, i.e. no separate drying steps are carried
out.
[0152] In a general procedure for this, in a first step, the
polymer dispersion is applied in the manner described above to the
substrate, i.e. to at least one surface of the paper or of the
paperboard, the material is optionally dried, and then the polymer
dispersion is again applied in the manner described above to the
resultant coated surface of the substrate. This procedure can be
repeated one or more times, until the desired weight per unit area
of coating has been achieved. The statements made above are
applicable here. The amount applied of the polymer dispersion is
generally selected here in such a way that the amount applied in
the individual steps is at least 0.5 g/m.sup.2, often at least 1
g/m.sup.2, in particular at least 2 g/m.sup.2, specifically at
least 3 g/m.sup.2, typically being in the range from 1 to 30
g/m.sup.2, in particular from 2 to 25 g/m.sup.2, specifically from
2 to 20 g/m.sup.2, or from 3 to 20 g/m.sup.2, very specifically
from 2 to 12 g/m.sup.2, or from 3 to 12 g/m.sup.2, calculated as
solid per m.sup.2 of the coated surface. This method gives a
coating composed of a number of layers arranged on one another,
where the resultant weight per unit area of coating per layer
corresponds to the amount of solid applied. The number of layers,
and the amount applied per layer, is naturally selected in such a
way that the total amount of solid applied, and therefore the
resultant weight per unit area of the coating, is preferably in the
range from 2 to 50 g/m.sup.2, in particular from 3 to 40 g/m.sup.2,
specifically from 5 to 30 g/m.sup.2. In the case of paperboard, the
number of layers, and the amount applied per layer, is often
selected in such a way that the total amount of solid applied, and
therefore the resultant weight per unit area of the coating, is
preferably in the range from 3 to 50 g/m.sup.2, in particular from
4 to 40 g/m.sup.2, specifically from 5 to 30 g/m.sup.2, calculated
as solid per m.sup.2. In the case of paper, the number of layers,
and the amount applied per layer, is often selected in such a way
that the total amount of solid applied, and therefore the resultant
weight per unit area of the coating, is preferably in the range
from 1 to 30 g/m.sup.2, in particular from 2 to 25 g/m.sup.2,
specifically from 3 to 20 g/m.sup.2, calculated as solid per
m.sup.2.
[0153] In relation to the composition of the aqueous dispersion of
the at least one polyester, and also in relation to preferred
polyesters, and to the substrates, the statements made above are
applicable.
[0154] Another preferred embodiment of the present invention
provides a process for producing a barrier coating on paper or
paperboard in the manner described above, where the paper or the
paperboard has been produced at least to some extent, generally to
an extent of at least 30% by weight (% by weight, based on total
fiber mass), in particular to an extent of at least 50% by weight,
or completely, from mineral-oil-contaminated recycling paper. In
particular, the invention provides a process of this type in which
the paper or the paperboard is intended for the packaging of food
or drink. Among these materials are sales packaging, such as
cartons or paper products, and also consumer packaging, for example
disposable tableware, e.g. plates, cups, or beakers made of
paperboard.
[0155] The present invention equally provides coated paper or
paperboard which is obtainable via the process of the invention. It
features not only good barrier action both with respect to
nonvolatile vegetable oils, vegetable fats, and animal fats or
oils, but also good barrier action with respect to mineral oils, in
particular with respect to volatile mineral oils, i.e. with respect
to mineral oils which permeate in the form of gas, specifically
those having from 15 to 25 carbon atoms, e.g. paraffinic and
naphthenic hydrocarbons hazardous to health, and aromatic
hydrocarbons. Good blocking resistance values are moreover
achieved, and papers coated in the invention can be reeled without
sticking.
[0156] The invention is illustrated by examples hereinafter.
I. Analysis
[0157] To determine zero-shear viscosity .eta..sub.0, dynamic
viscosity measurement was used on the polymer melts at 180.degree.
C., using oscillatory low-amplitude shear, at shear rates in the
range from 0.01 to 500 s.sup.-1 with a shear amplitude of 100 Pa,
to determine viscosity curves, and zero-shear viscosity .eta..sub.0
was determined from these via extrapolation to shear rate 0
s.sup.-1. The viscosity curves were determined by using a "Dynamic
Stress Rheometer (DSR)" from Rheometrics with plate-on-plate
geometry (diameter 25 mm, gap 1 mm).
[0158] Shear viscosity of the polymer melt under the dispersing
conditions was determined by means of dynamic viscosity measurement
on the polymer melts with a rotary rheometer (SR5) from Rheometrics
at the temperature stated in the examples.
[0159] The viscosity of the dispersion medium under dispersing
conditions was determined by the Brookfield method, using an MCR301
rotary rheometer from Anton Paar GmbH at the temperature stated in
the examples, where the measurement was carried out up to a shear
rate of 1000/s, and viscosity under dispersing conditions was
determined via extrapolation to the shear rate corresponding to the
example.
[0160] Intrinsic viscosity was determined to EN ISO 1628-1 at
25.degree. C. on a 0.5% by weight solution of the polymer in
o-dichlorobenzene/phenol (1:1 w/w).
[0161] Molecular weights were determined via gel permeation
chromatography (GPC) to DIN 55672-1.
[0162] Particle size distribution was determined on a 1% by weight
dilution of the dispersion, via light scattering at 25.degree.
C.
[0163] Brookfield viscosity of the dispersions was determined at
20.degree. C. to DIN EN ISO 2555 by using a Physika MCR rotary
viscometer with CC 27 Couette geometry.
II. Polyesters Used
[0164] Polyester 1: Aliphatic-Aromatic Copolyester
[0165] Polybutylene terephthalate adipate produced as follows:
1095.2 g of terephthalate (47 mol %), 700 g of 1,4-butanediol (65
mol %), and 1 ml of glycerol (0.05% by weight, based on the
polymer) were first mixed together with 1.1 ml of tetrabutyl
orthotitanate (TBOT), and the mixture was heated to 160.degree. C.
The resultant methanol was removed by distillation within 1 h. The
tank was then cooled to about 140.degree. C. 929.5 g of adipic acid
(53 mol %), 700 g of 1,4-butanediol (65 mol %) and 1 ml of glycerol
(0.05% by weight, based on the polymer), together with 1.04 ml of
tetrabutyl orthotitanate (TBOT), were then added to the mixture.
The reaction mixture was heated to a temperature of 190.degree. C.,
and the resultant water was removed by distillation at this
temperature over a period of 1 h. The temperature was then
increased to 240.degree. C., and the system was evacuated stepwise.
Excess 1,4-butanediol was removed by distillation in vacuo (<1
mbar) over a period of 1 h.
[0166] The number-average molar mass of the resultant copolyester
was 21000 g/mol, and the weight-average molar mass was 59000 g/mol.
Intrinsic viscosity IV was 106. Zero-shear viscosity .eta..sub.0 at
180.degree. C. was 136 Pas. Acid number was less than 1 mg
KOH/g.
[0167] Polyester 2: Aliphatic-Aromatic Copolyester
[0168] Polybutylene terephthalate adipate produced as follows:
1388.5 g of terephthalate (55 mol %), 1000 g of 1,4-butanediol (85
mol %), and 1 ml of glycerol (0.05% by weight, based on the
polymer) were first mixed together with 1.1 ml of tetrabutyl
orthotitanate (TBOT), and the mixture was heated to 160.degree. C.
The resultant methanol was removed by distillation within 1 h. The
tank was then cooled to about 140.degree. C. 854.9 g of adipic acid
(45 mol %), 523 g of 1,4-butanediol (45 mol %), and 1 ml of
glycerol (0.05% by weight, based on the polymer) were then added to
the mixture, together with 1.04 ml of tetrabutyl orthotitanate
(TBOT). The reaction mixture was heated to a temperature of
190.degree. C., and the resultant water was removed by distillation
at this temperature over a period of 1 h. The temperature was then
increased to 240.degree. C. and the system was evacuated stepwise.
Excess 1,4-butanediol was removed by distillation in vacuo (<1
mbar) over a period of 1 h.
[0169] Intrinsic viscosity IV was 91. Acid number was less than 1
mg KOH/g.
[0170] Polyester 3: Aliphatic Copolyester
[0171] Polybutylene succinate sebacate produced as follows: 6.8 kg
of sebacic acid (5 mol %), 75.7 kg of succinic acid (95 mol %),
79.1 kg of 1,4-butanediol (130 mol %), and 298 g of glycerol (0.25%
by weight, based on the polymer) were mixed and heated to
120.degree. C. 11 g of tetrabutyl orthotitanate (TBOT) were then
mixed with the mixture, which was heated to 200.degree. C. The
resultant water was removed by distillation within 1 h. The tank
was then cooled to about 140.degree. C. 22 g of tetrabutyl
orthotitanate (TBOT) were then added to the mixture. The
temperature was then increased to 250.degree. C., and the system
was evacuated stepwise. Excess 1,4-butanediol was removed by
distillation in vacuo (<5 mbar) over a period of 1 h.
[0172] Intrinsic viscosity IV was 153. Zero-shear viscosity
.eta..sub.0 at 180.degree. C. was 271 Pas. Acid number was less
than 1 mg KOH/g.
III. Production of Polyester Dispersion
[0173] Dispersion Example 1:
[0174] A 12-stage inline disperser equipped with shear elements of
toothed-ring type served as rotor-stator mixer.
[0175] An amount of 1.2 kg/h of polyester 1 was drawn continuously
by way of the feed hopper into the single-screw extruder (Tech-line
E 16 T from Dr. Collin GmbH), where it was melted at 155.degree. C.
The polymer melt was fed into the first stage disperser (4000 rpm).
Shear rate was 12566 s.sup.-1. The viscosity of the polymer at this
shear rate was 35 Pa s. At the same time, a 7% by weight aqueous
solution of a partially hydrolyzed polyvinyl alcohol (Kuraray Poval
224E) which comprised 1% by weight of an anionic surfactant
(Emulphor FAS 30 from BASF SE) with solution viscosity 0.038 Pa s
was fed into the inline disperser in such a way as to give solids
contents of 55% by weight and, respectively, 45% by weight in the
first and the fourth stage. Solids content in the tenth stage was
adjusted to 43% by weight. The temperature in the first ten stages
was 155.degree. C.; the temperature in the eleventh and twelfth
stages was 130.degree. C. Total residence time was 1.2 min. Once
the dispersion had left the final stage, a cooling bath was used
for quenching to 20.degree. C. The solids content of the dispersion
was 43% by weight and its average particle diameter d.sub.32 was
1.6 .mu.m.
[0176] Dispersion Example 2:
[0177] A 12-stage inline disperser equipped with shear elements of
toothed-ring type served as rotor-stator mixer.
[0178] An amount of 1.2 kg/h of the copolyester from polymer
production example 1 (.eta..sub.0=136 Pas) was drawn continuously
by way of the feed hopper into the single-screw extruder (Tech-line
E 16 T from Dr. Collin GmbH), where it was melted at 155.degree. C.
The polymer melt was fed into the first stage disperser (4000 rpm).
Shear rate was 12 566 s.sup.-1. The viscosity of the polymer at
this shear rate was 36 Pa s, measured by a Gottfert-Rheograph 2003
capillary rheometer. At the same time, a 7% by weight aqueous
solution of a partially hydrolyzed polyvinyl alcohol (Kuraray Poval
224E) which comprised 1% by weight of an anionic surfactant
(Emulphor FAS30 from BASF SE) with solution viscosity 0.038 Pa s
was fed into the inline disperser in such a way as to give solids
contents of 60% by weight and, respectively, 50% by weight in the
first and the fourth stage. Solids content in the tenth stage was
adjusted to 46% by weight. The temperature in the first ten stages
was 155.degree. C.; the temperature in the eleventh and twelfth
stages was 130.degree. C. Total residence time was 1.8 min. Once
the dispersion had left the final stage, a cooling bath was used
for quenching to 30.degree. C. The solids content of the dispersion
was 46% by weight and its average particle diameter d.sub.32 was
1.6 .mu.m.
IV. Production of Coated Paper:
[0179] The following experiments were carried out on a miniplant
spreading machine from Bachofen & Meier. The specification of
the machine was as follows: operating width: 330 mm; machine speed:
from 10 to 150 m/min; unwound: max. 600 mm diameter; core diameter:
70, 76, and 150 mm; application system: roll; drying: 6 dryer
hoods: air heater, 47 kW, radiant heater, 14 kW; with metering
system: doctor roller or doctor bar.
Example 1
Single Coating on Untreated Paperboard
[0180] The miniplant spreading machine was used to apply the
dispersion of dispersion example 1 to the untreated paperboard (300
g/m.sup.2 Smurfit Kappa Gernsbach) in a single pass, using a doctor
roller. Machine speed was 50 m/min, amount applied: 10 g/m.sup.2
(solid).
Example 2
Double Coating on Untreated Paperboard
[0181] The miniplant spreading machine was used to apply the
dispersion of dispersion example 1 to the untreated paperboard (300
g/m.sup.2 Smurfit Kappa Gernsbach) in two passes, using a doctor
roller. Machine speed was 50 m/min, amount applied per pass: 5
g/m.sup.2 (solid).
Example 3
Single Coating on Untreated Stora-Enso Paper
[0182] The miniplant spreading machine was used to apply the
dispersion of dispersion example 1 to untreated paper (Stora-Enso
Kabel 37 g/m.sup.2 LWC) in a single pass using a doctor bar.
Machine speed was 50 m/min, amount applied: 10 g/m.sup.2
(solid).
Example 4
Single Coating on Untreated Magnostar Paper
[0183] The miniplant spreading machine was used to apply the
dispersion of dispersion example 1 to untreated paper (untreated
Magnostar paper, 58 g/m.sup.2) in a single pass using a doctor bar.
Machine speed was 50 m/min, amount applied: 10 g/m.sup.2
(solid).
Example 5
Double Coating on Untreated Magnostar Paper
[0184] The miniplant spreading machine was used to apply the
dispersion of dispersion example 1 to untreated paper (untreated
Magnostar paper, 58 g/m.sup.2) in two passes using a doctor bar.
Machine speed was 50 m/min, amount applied in the pass 5 g/m.sup.2
(solid), and in the second pass 4 g/m.sup.2 (solid).
V Testing of Barrier Properties
[0185] (1) Barrier test with respect to gaseous mineral oil
constituents (test method 1) 9 ml of hexane are placed in a vessel
with a sponge, and the system is sealed with a lid which has an
aperture and a sealing ring (internal diameter 63 mm). The aperture
has been securely sealed with the barrier material to be tested,
and this barrier material does not come into contact with the
hexane-saturated sponge. The weight loss from the vessel is
measured at various junctures. The weight loss is a measure of the
amount of hexane escaping by way of the gas phase through the
barrier material and is therefore a measure of the quality of the
barrier action with respect to gaseous mineral oil constituents.
The weight loss in grams is recalculated to represent 1 m.sup.2 of
paper area and is then stated as g/m.sup.2 d (per day). Table 1
below collates the results.
TABLE-US-00001 [0185] Untreated paperboard Hexane migration 300
g/m.sup.2 Smurfit [g/m.sup.2 d] Kappa Gernsbach 1 h 4 h Without
coating 7768 7063 Example 1 4576 4760 Example 2 96 81
[0186] Barrier test with respect to edible oil/oleic acid (test
example 2)
[0187] The "Oil Penetration Test" was used to study the barrier
properties of the uncoated papers/paperboards and of the
papers/paperboards coated with the polyester dispersions. To this
end, 2 ml of oleic acid was used to wet the coated paper side. The
paper was then stored for a defined time at 60.degree. C. The
reverse side of the coated paper was then assessed visually at
various junctures to determine the extent of staining. 100% means
complete penetration, and 0% means no penetration.
TABLE-US-00002 Test paper or Extent of staining test paperboard
After 30 min After 1 h After 4 h After 7 h Untreated paperboard
100% 100% 100% 100% 00 g/m.sup.2 Smurfit Kappa Gernsbach without
coating Stora-Enso Kabel 100% 100% 100% 100% 37 g/m.sup.2 LWC
without coating Magnostar 58 g/m.sup.2 100% 100% 100% 100% without
coating Example 1 5% 6% 8% 10% Example 2 0% 0% 0% 0% Example 3 15%
40% 100% 100% Example 4 15% 40% 100% 100% Example 5 0% 0% 1% n.d.
n.d. = not determined
* * * * *