Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2002-08-27
2004-04-27
Sanders, Kriellion A. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S047000, C524S078000, C524S277000
Reexamination Certificate
active
06727298
ABSTRACT:
The present invention relates to a process for reducing the water-vapor permeability of films or coatings made from polymer compositions (Q) comprising beeswax or comprising montan ester wax or comprising mixtures of these. The present invention further relates to films or coatings made from polymer compositions (Q) comprising beeswax or comprising montan ester wax or comprising mixtures of these. The present invention further relates to compositions which comprise Z
1
) from 40 to 98.5% by weight of at least one partly aromatic polyester, Z
2
) from 0.5 to 20% by weight of starch, cellulose or mixtures of these, Z
3
) from 1 to 20% by weight of beeswax or montan ester wax or mixtures of these, and Z
4
) from 0 to 20% by weight of at least one additive, and also to the use of these as premixes and for reducing water-vapor permeability.
Polymer compositions for producing films or coatings are known per se. Many films or coatings are not sufficiently impermeable to water-vapor for many purposes, such as use in the food and drink sector. It is also known that straight polymer compositions do not generally comply with all of the technological requirements. They become economically and technologically useful only when additives have been added. Since the amounts of additives needed in the polymer compositions are mostly only small, and the incorporation and homogeneous distribution of such small amounts of additives is often technically difficult, the form in which the additives are mostly added to the polymer compositions is that of a premix, known as a masterbatch, in which they are present at relatively high concentration.
If lubricants, such as waxes, are used as additives, a problem in practice is that the lubricants are often difficult to mix into the polymer matrix, but agglomerate in the matrix and remain at its surface. This leads firstly to deposits of lubricant on the walls of the mixing unit used, e.g. of the extruder. Secondly, because of the external lubrication it then becomes difficult to mix in any additives which are to be added subsequently. This behavior of the lubricants causes particular problems during the preparation of masterbatches, since the premixes are difficult to prepare with the necessary high wax and additive concentrations.
Compositions based on biodegradable polymers, starch or cellulose and on waxes are known (DE-A1 44 40 858).
For example, WO 98/14326 discloses compositions which may comprise polyesters, such as polyhydroxyalkanoates, and from 2 to 30 parts by weight of wax as additive, based on 100 parts by weight of the composition. It is also generally disclosed that the compositions may also comprise fibrous or lamellar fillers or reinforcing materials.
There are also known biodegradable laminates which comprise a waxy layer which has been built up from a wax as principal component and from a polymer, such as polyvinyl alcohol, or from an acetate or acrylate. This waxy layer may also comprise thickeners, e.g. starch, methylcellulose or hydroxymethylcellulose (EP-B1 616 569).
WO 98/20073 concerns starch-containing compositions based on biodegradable polymers, for example on aliphatic-aromatic copolyesters. These comprise, as compatibilizers between the polymeric matrix and the filler dispersed therein, esterified polyols, i.e. fats or oils in amounts of from 0.5 to 20% by weight. Examples of the amounts of starch are from 20 to 95% by weight, preferably from 30 to 75% by weight. Waxes are mentioned as additives.
WO 94/3543 discloses biodegradable compositions in which the flow improvers present may comprise, inter alia, 5 to 70% by weight of polyolefin waxes, based on the total weight of the respective composition. According to this publication, the flow improvers are particularly valuable for preparing compositions with high filler contents. Compositions whose mechanical properties are studied by way of example are based on polyethylene-vinyl alcohol, polyethylene-acrylic acid, 40 or 25% of wood flour and 7 or, respectively, 5% of polyethylene wax.
It is an object of the present invention to find a process for reducing the water-vapor permeability of films or coatings. In particular, the process provided should give films or coatings which are environmentally compatible. A further object is to find films or coatings which have reduced water-vapor permeability and can be used in the food and drink sector. Finally, the films or coatings provided should have a good surface.
We have found that this object is achieved by using beeswax or montan ester wax or mixtures of these in polymer compositions to reduce the water-vapor permeability of coatings or films produced therefrom. Surprisingly, it has also been found that starches or celluloses are suitable as compatibilizers for binding beeswax or montan ester wax, or a mixture of these, into a polymer matrix, and the object set is therefore achieved by means of a process for reducing the water-vapor permeability of films or coatings made from polymer compositions (Q) comprising beeswax or comprising montan ester wax or comprising mixtures of these, by in a first step preparing a composition (Z) comprising Z
1
) from 40 to 98.5% by weight of at least one polymer compatible with the polymers (Q1) which are the basis of Q, Z
2
) from 0.5 to 20% by weight of starch or cellulose or a mixture of these as compatibilizer, Z
3
) from 1 to 20% by weight of beeswax or montan ester wax or a mixture of these, and Z
4
) from 0 to 20% by weight of at least one additive, where the percentages by weight are based on the total weight of Z, and in a second step combining the composition Z with the polymer Q1 which is the basis of Q.
Preferred compositions Z which may be used according to the invention as premixes comprise from 60 to 97% by weight of Z
1
, from 1 to 15% by weight of Z
2
, from 2 to 15% by weight of Z
3
, and from 0 to 10% by weight of Z
4
. In another preferred embodiment, the compositions Z comprise from 70 to 95.9% by weight of Z
1
, from 1 to 10% by weight of Z
2
, from 3 to 10% by weight of Z
3
and from 0.1 to 10% by weight of Z
4
.
There is no restriction in principle on the polymers Z
1
, but thermoplastically processable polymers are preferred. The preferred polymers include biodegradable polymers. These include polymers of very different structures, and also mixtures of different biodegradable polymers.
Polymeric reaction products of lactic acid may be used as biodegradable polymers in the novel process. These are known per se or may be prepared by processes known per se. Besides polylactide, use may also be made of those copolymers or block copolymers based on lactic acid with other monomers. Linear polylactides are mostly used. However, branched lactic acid polymers may also be used. Examples of branching agents are polyfunctional acids or alcohols. Polylactides which may be mentioned as an example are those obtainable essentially from lactic acid or from its C
1
-C
4
-alkyl esters or mixtures of these, with at least one aliphatic C
4
-C
10
dicarboxylic acid and with at least one C
3
-C
10
alkanol having from three to five hydroxyl groups.
Other examples of biodegradable polymers are aliphatic polyesters. These include homopolymers of aliphatic hydroxycarboxylic acids or lactones, and also copolymers or block copolymers of different hydroxycarboxylic acids or lactones or mixtures of these. These aliphatic polyesters may also contain units of diols and/or of isocyanates. The aliphatic polyesters may also contain units which derive from tri- or polyfunctional compounds, for example from epoxides, from acids or from triols. The aliphatic polyesters may contain the latter units as individual units, or a number of these, possibly together with the diols and/or isocyanates.
Processes for preparing aliphatic polyesters are known to the skilled worker. The aliphatic polyesters generally have molar asses (number-average) of from 10,000 to 100,000 g/mol.
Particularly preferred aliphatic polyesters include polycaprolactone.
Particularly preferred aliphatic polyesters are poly-3-hydroxybutanoates an
Skupin Gabriel
Witt Uwe
BASF - Aktiengesellschaft
Keil & Weinkauf
Sanders Kriellion A.
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