EP1322709A1

EP1322709A1 - Polyester film

Info

Publication number: EP1322709A1
Application number: EP01980384A
Authority: EP
Inventors: Motonori Yamamoto; Gabriel Skupin
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2000-09-18
Filing date: 2001-09-14
Publication date: 2003-07-02
Also published as: WO2002022736A1; JP2004509204A; US20040014883A1

Abstract

The invention relates to polyester films containing the following: i) 70 to 99.9 wt. % of at least one polyester with a molecular weight Mn of between 8000 and 100000 g/mol and ii) 0.1 to 30 wt. % of one or more compounds selected from the following: ii1) at least one tenside and ii2) polyesters with a molecular weight Mn of between 1000 and 7000 g/mol or mixtures of one or more compounds ii1) and ii2), the weight percentages of the components i) to ii) together totalling 100 %. The invention also relates to the use of these films as packaging film and to the use of ii) for increasing the transparency or adhesion or the anti-fogging properties of polyester films or as a nucleation agent for polyesters.

Description

polyester film

Description 5

The present invention relates to polyester films containing

i) 70 to 99.9% by weight of at least one polyester with a molecular weight M _n in the range from 8000 to 100000 g / mol and 10 ii) 0.1 to 30% by weight of one or more compounds selected from

iil) at least one surfactant and 15 ii2) polyesters with a molecular weight M _n in the range from 1000 to 7000 g / mol

or mixtures of one or more compounds iil) and 20 112),

where the weight percentages of components i) to ii) together add up to 100%.

The present invention further relates to the use of polyester films as packaging film and the use of iil) at least one surfactant or ii2) polyesters with a molecular weight M _n in the range from 1000 to 7000 g / mol or mixtures of one or more compounds iil) and ii2 ) to increase

30 the transparency or adhesion or the anti-fogging properties of polyester films or as a nucleating agent for polyester.

The most commonly used film materials so far, for example for packaging biodegradable products such as food,

35 are based on polyethylene, polypropylene or vinyl chloride homo- and copolymers. These materials have the disadvantage that they are naturally not biodegradable. Proper disposal of these film materials is therefore complex and therefore expensive.

40

Biodegradable polyester films that do not have this disadvantage are known (see e.g. WO 96/15173). JP-A2 026626/00 and JP-A2 026623/00 describe biodegradable polyester films containing aliphatic polyesters based on hydroxycarboxylic acid.

45 ren and liquid additives of certain viscosity. Compared to the non-biodegradable films based on polyethylene, polypropylene or vinyl chloride homo- and copolymers, polyester Films, in particular biodegradable polyester films, but less transparent, have less adhesion to other materials such as cardboard or food, as well as to the same material, and poorer anti-fog properties.

The present invention is therefore based on the object of providing polyester films which have increased transparency, increased adhesion, improved anti-fogging properties or several of these properties.

This task is fulfilled by the polyester films defined at the outset, which are described in more detail below.

In principle come for the manufacture of the invention

Polyester films as component i) are all polyesters which have a molecular weight M _n in the range from 8000 to 100000 g / mol, preferably 9000 to 75000 g / mol, particularly preferably 10000 to 50,000 g / mol. Examples of such polyesters are polyethylene terephthalate or polybutylene terephthalate. Mixtures or blends of these polyesters are also suitable.

The determination method for the molecular weights M _{n of} these and the polymers mentioned below is reproduced below under the point "Examples" in the description of the application measurements.

The polyester films of the invention are preferably biodegradable.

The term "biodegradable polyester film" is intended to include all polyester films which come under the definition of biodegradability given in DIN V 54900, in particular compostable polyester films.

In general, biodegradability means that the polyester films disintegrate in a reasonable and demonstrable period of time. The breakdown can take place hydrolytically and / or oxidatively and can be mainly caused by the action of microorganisms such as bacteria, yeasts, fungi and algae. Biodegradability can be determined, for example, by mixing foils with compost and storing them for a certain time. According to ASTM D 5338, ASTM D 6400 and DIN V 54900, C0 ₂ -free air is allowed to flow, for example, through mature compost during composting and this is subjected to a defined temperature program. The biodegradability is determined by the ratio of the net C0 release of the sample (after deduction of the C0 release by the compost without sample) for the maximum C0 release of the sample (calculated from the carbon content of the sample) defined as biodegradability. The polyester films according to the invention, which are biodegradable, generally show clear signs of degradation, such as fungal growth, cracking and hole formation, after only a few days of composting.

In principle, all biodegradable polyesters which have a molecular weight M _n in the range from 8000 to 100000 g / mol, preferably 9000 to 75000 g / mol, particularly preferably 10,000 to, are suitable as component i) for the production of the biodegradable polyester films according to the invention 50000 g / mol. Examples of biodegradable polyesters are cellulose derivatives such as cellulose esters, for example cellulose acetate, cellulose acetate butyrate, starch esters and polyesters, in particular aliphatic homo- and copolyesters and partially aromatic copolyesters. Mixtures or blends of the aforementioned biodegradable polyesters are of course also suitable.

The biodegradable polyesters i) mentioned can contain other biodegradable polymers of natural or synthetic origin as blend or blend components. Polymers of natural origin are e.g. Shellac, starch or cellulose. These can be modified with physical and / or chemical methods. The preferred polymers of natural origin include starch, thermoplastically processable starch or starch compounds such as starch ether. In general, the weight ratio of biodegradable polyesters i) to other biodegradable blend or blend components, e.g. Starch can be freely selected in a wide range, for example in the range from 1.2: 1 to 0.8: 1.2.

Polymeric reaction products of lactic acid can be used as biodegradable polyesters i) for producing the biodegradable polyester films according to the invention. These are known per se or can be produced by processes known per se. In addition to polylactide, copolymers or block copolymers based on lactic acid and other monomers can also be used. Linear polylactides are mostly used. However, branched lactic acid polymers can also be used. For example, multifunctional acids or alcohols can serve as branching agents. Examples include polylactides which essentially consist of lactic acid or its C 1 -C ₄ -alkyl esters or mixtures thereof and at least one aliphatic C ₄ - to Cirj-dicarboxylic acid and at least one C ₃ - to Cio-alkanol with three to five hydroxy groups are available.

Examples of biodegradable polyester i) ^'from which the biodegradable polyester films are commercially available, are aliphatic polyesters. These include homopolymers of aliphatic hydroxycarboxylic acids or lactones, but also copolymers or block copolymers of different hydroxycarboxylic acids or lactones or mixtures thereof. These aliphatic polyesters can also contain diols and / or isocyanates as building blocks. In addition, the aliphatic polyesters can also contain building blocks which are derived from trifunctional or multifunctional compounds such as epoxides, acids or triols. The latter building blocks can be contained individually or several of them or together with the diols and / or isocyanants in the aliphatic polyesters.

Methods for producing aliphatic polyesters are known to the person skilled in the art. The aliphatic polyesters generally have molecular weights M _n in the range from 8,000 to 100,000 g / mol.

Polycaprolactone is one of the particularly preferred aliphatic polyesters.

Poly-3-hydroxybutanoic acid esters and copolymers of 3-hydroxybutanoic acid or mixtures thereof with 4-hydroxybutanoic acid and 3-hydroxyvaleric acid, in particular up to 30% by weight, preferably up to 20% by weight, of the latter acid are particularly preferred aliphatic Polyester. Suitable polymers of this type also include those with an R-stereospecific configuration as known from WO 96/09402. Polyhydroxybutanoic acid esters or their copolymers can be produced microbially. Methods for the production from various bacteria and fungi are e.g. Chem Tech. Lab. 39, 1112-1124 (1991), a method for producing sterospecific polymers is known from WO 96/09402.

Furthermore, block copolymers of the hydroxycarboxylic acids or lactones mentioned, their mixtures, oligomers or polymers can also be used.

Further aliphatic polyesters are those which are composed of aliphatic or cycloaliphatic dicarboxylic acids or their mixtures and aliphatic or cycloaliphatic diols or their mixtures. According to the invention, both statistical and block copolymers can be used. The aliphatic dicarboxylic acids suitable according to the invention generally have 2 to 10 carbon atoms, preferably 4 to 6 carbon atoms. They can be both linear and branched. The cycloaliphatic dicarboxylic acids which can be used in the context of the present invention are generally those having 7 to 10 carbon atoms and in particular those having 8 carbon atoms. In principle, however, dicarboxylic acids with a larger number of carbon atoms, for example with up to 30 carbon atoms, can also be used.

10

Examples include: malonic acid, succinic acid, glutaric acid, 2-methylglutaric acid, 3-methylglutaric acid, adipic acid, pimelic acid, acelic acid, sebacic acid, fumaric acid, 2, 2-dimethylglutaric acid, suberic acid, 1, 3-cyclopentanedicarboxylic acid, 1,4 -Cy-

15 clohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, diglycolic acid, itaconic acid, maleic acid and 2,5-norbornanedicarboxylic acid, among which adipic acid is preferred.

The ester-forming derivatives of the above-mentioned aliphatic 20 or cycloaliphatic dicarboxylic acids which can also be used are, in particular, the di-Cχ- to Cβ-alkyl esters, such as dimethyl, diethyl, di-n-propyl, di-isopropyl, di- N-butyl, di-isobutyl, di-t-butyl, di-n-pentyl, di-iso-pentyl or di-n-hexyl ester may be mentioned. Anhydrides of the dicarboxylic acids can also be used.

The dicarboxylic acids or their ester-forming derivatives can be used individually or as a mixture of two or more thereof.

30

Examples of the aliphatic polyesters considered are aliphatic copolyesters as described in WO 94/14870, in particular aliphatic copolyesters from succinic acid, its diesters or their mixtures with other aliphatic ones

35 acids or diesters such as glutaric acid and butanediol or mixtures of this diol with ethylene glycol, propanediol or hexanediol or mixtures thereof.

Aliphatic polyesters of this type generally have molecular weights M _n in the range from 8000 to 100000 g / mol.

The aliphatic polyesters can likewise be random or block copolyesters which contain further monomers. The proportion of the other monomers is usually up to 45 10% by weight. Preferred comonomers are hydroxcarboxylic acids or lactones or mixtures thereof. Mixtures of two or more comonomers and / or further building blocks, such as epoxides or polyfunctional aliphatic or aromatic acids or polyfunctional alcohols, can of course also be used to prepare the aliphatic polyesters.

Furthermore, the biodegradable polyester films according to the invention can be based on partially aromatic polyesters as component i). According to the invention, this should also include polyester derivatives such as polyether esters, polyester amides or poly ether ester amides. Suitable biodegradable partially aromatic polyesters include linear non-chain extended polyesters (WO 92/09654). Chain-extended and / or branched partially aromatic polyesters are preferred. The latter are known from the documents mentioned at the outset, WO 96/15173 to 15176, 21689 to 21692, 25446, 25448 or WO 98/12242, to which reference is expressly made. Mixtures of different partially aromatic polyesters are also possible, as are blends of partially aromatic polyesters with starch or modified starch, cellulose esters or polylactide.

The particularly preferred partially aromatic polyesters include polyesters, which are essential components

A) an acid component

al) 30 to 95 mol% of at least one aliphatic or at least one cycloaliphatic dicarboxylic acid or its ester-forming derivatives or mixtures thereof

a2) 5 to 70 mol% of at least one aromatic dicarboxylic acid or its ester-forming derivative or mixtures thereof and

a3) 0 to 5 mol% of a compound containing sulfonate groups,

B) a diol component selected from at least one C to C alkanediol and at least one C ₅ to Cio cycloalkanediol or mixtures thereof

and, if desired, furthermore one or more components selected from

C) a component selected from cl) at least one dihydroxy compound of the formula I containing ether functions

HO - [(CH ₂ ) _n -0] _m -H (I)

where n is 2, 3 or 4 and m is an integer from 2 to 250

c2) at least one hydroxycarboxylic acid or formula Ila or Ilb

HO— [C (O) G 0—] _p H -C (O) G 0—]

(Ha) (Ilb) in which p is an integer from 1 to 1500 and r is an integer from 1 to 4, and G represents a radical which is selected from the group consisting of phenylene, - (CH) _q - , where q is an integer from 1 to 5, -C (R) H- and -C (R) HCH ₂ , where R is methyl or ethyl

c3) at least one amino-C - to -CC alkanol or at least one amino-Cs to Cio-cycloalkanol or mixtures thereof

c4) at least one diamino-Ci to C ₈ alkane

c5) at least one 2, 2 'bisoxazoline of the general formula III

where R ^{1 is} a single bond, a (CH) _Z alkylene group, with z = 2, 3 or 4, or a phenylene group

c6) at least one aminocarboxylic acid selected from the

Group consisting of the natural amino acids, polyamides with a molecular weight of at most 18000 g / mol, obtainable by polycondensation of a dicarboxylic acid with 4 to 6 carbon atoms and a diamine with 4 up to 10 carbon atoms, compounds of the formulas IV a and IVb

HO- [-C (O) -TN (H) -] _S H [-C (O) -TN (H) -] _fc _1 (IVa) (IVb)

in which s is an integer from 1 to 1500 and t is an integer from 1 to 4, and T is a radical which is selected from the group consisting of phenylene, - (CH) _n -, where n is an integer Number from 1 to 12 denotes -C (R ² ) H- and -C (R ² ) HCH ₂ , where R ^{2 represents} methyl or ethyl,

15 and polyoxazolines with the repeating unit V

in which R ^{3 represents} hydrogen, C ₁ -C ₆ -alkyl, C ₅ -C ₈ cycloalkyl, "unsubstituted or with C 1 -C 4 -alkyl groups up to triply substituted phenyl or tetrahydrofuryl,

or mixtures of cl to c6

30 and

D) a component selected from

"dl) at least one compound with at least three groups capable of ester formation,

d2) at least one isocyanate

40 d3) at least one divinyl ether

or mixtures of dl) to d3).

45 The acid component A of the preferred partially aromatic polyesters contains from 30 to 70, in particular from 40 to 60, mol% al and from 30 to 70, in particular from 40 to 60 mol% a2.

The aliphatic or cycloaliphatic acids and the corresponding derivatives al are those mentioned above. Adipic acid or sebacic acid or their respective ester-forming derivatives or mixtures thereof are particularly preferably used. Adipic acid or its ester-forming derivatives, such as its alkyl ester or mixtures thereof, are particularly preferably used.

Aromatic dicarboxylic acid a2 generally includes those with 8 to 12 carbon atoms and preferably those with 8 carbon atoms. Examples include terephthalic acid, isophthalic acid, 2, 6-naphthoic acid and 1, 5-naphthoic acid and ester-forming derivatives thereof. In particular, the di-CC _ö alkyl esters, for example dimethyl, diethyl, di-n-propyl, di-iso-propyl, di-n-butyl, di-iso-butyl, di-t-butyl, To name di-n-pentyl, di-iso-pentyl or di-n-hexyl ester. The anhydrides of dicarboxylic acids a2 are also suitable ester-forming derivatives.

In principle, however, aromatic dicarboxylic acids a2 with a larger number of carbon atoms, for example up to 20 carbon atoms, can also be used.

The aromatic dicarboxylic acids or their ester-forming derivatives a2 can be used individually or as a mixture of two or more thereof. Terephthalic acid or its ester-forming derivatives such as dimethyl terephthalate are particularly preferably used.

The compound containing sulfonate groups is usually an alkali metal or alkaline earth metal salt of a sulfonate group-containing dicarboxylic acid or its ester-forming derivatives, preferably alkali metal salts of 5-sulphoisophthalic acid or mixtures thereof, particularly preferably the sodium salt.

According to one of the preferred embodiments, the acid component A contains from 40 to 60 mol% a1, from 40 to 60 mol% a2 and from 0 to 2 mol% a3. According to a further preferred embodiment, the acid component A contains from 40 to 59.9 mol% of al, from 40 to 59.9 mol% of a2 and from 0.1 to 1 mol% of a3, in particular from 40 to 59.8 mol -% al, from 40 to 59.8 mol% a2 and from 0.2 to 0.5 mol% a3. In general, the diols B are selected from branched or linear alkane diols having 2 to 12 carbon atoms, preferably 4 to 6 carbon atoms, or cycloalkane diols having 5 to 10 carbon atoms.

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 and 2,2-dimethyl-1,3-propanediol (neopentyl glycol); Cyclopentanediol, 1,4-cyclohexane diol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol or 2,2,4,4-tetramethyl-1,3-cyclobutanediol. Mixtures of different alkanediols can also be used.

Depending on whether an excess of acid or OH end groups is desired, either component A or component B can be used in excess. According to a preferred embodiment, the molar ratio of the components A to B used can be in the range from 0.4: 1 to 1.5: 1, preferably in the range from 0.6: 1 to 1.1: 1.

In addition to components A and B, the polyesters on which the biodegradable polyester films according to the invention are based can contain further components.

The dihydroxy compounds cl used are preferably diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol and polytetrahydrofuran (poly-THF), particularly preferably diethylene glycol, triethylene glycol and polyethylene glycol, mixtures of these or compounds having different variables n also being used (see formula I ), for example polyethylene glycol, which contains propylene units (n = 3), for example obtainable by polymerization according to known methods of first ethylene oxide and then with propylene oxide, particularly preferably a polymer based on polyethylene glycol, with different variables n, units formed from ethyleneo - outweigh xid. The molecular weight (M _n ) of the polyethylene glycol is generally chosen in the range from 250 to 8000, preferably from 600 to 3000 g / mol.

According to one of the preferred embodiments, for example from 15 to 98, preferably 60 to 99.5 mol% of the diols B and 0.2 to 85, preferably 0.5 to 30 mol% of the dihydroxy compounds cl, based on the molar amount of B and cl, can be used for the production of the partially aromatic polyesters.

In a preferred embodiment, the following is used as hydroxycarbonic acid c2): glycolic acid, D-, L-, D, L-lactic acid, 6-hydroxyhexanoic acid, their cyclic derivatives such as glycolide (1,4-dioxane-2, 5-dione), D-, L-dilactide (3, 6-dimethyl-l, 4-dio-xan-2, 5-dione), p-hydroxybenzoic acid and their oligomers and polymers such as 3-polyhydroxybutyric acid, polyhydroxyvaleric acid, polylactide ( available for example as EcoPLA ^® (from Cargill)) and a mixture of 3-polyhydroxybutyric acid and polyhydroxyvaleric acid (the latter is available under the name Biopol ^® from Zeneca), particularly preferably for the production of partially aromatic polyester the low molecular weight and cyclic derivatives thereof.

The hydroxycarboxylic acids can be used, for example, in amounts of from 0.01 to 50, preferably from 0.1 to 40,% by weight, based on the amount of A and B.

Amino-C ₂ -C ₂ -alkanol or amino-Cs-Cio-cycloalkanol (component c3), which should also include 4-aminomethylcyclohexane-methanol, are preferably amino-C ₂ -C ₆ -alkanols such as 2-aminoethanol, 3 -Aminopropanol, 4-aminobutanol, 5-aminopentanol, 6-aminohexanol and amino-Cs-C _δ -cycloalkanols such as aminocyclopentanol and aminocyclohexanol or mixtures thereof.

The diamino-C ₈ -alkane (component c4) is preferably a diamino-CC ₆ -alkane such as 1,4-diminobutane, 1,5-diaminopentane and 1,6-diaminohexane (hexamethylenediamine, "HMD") ,

According to a preferred embodiment, from 0.5 to 99.5, preferably from 70 to 98.0 mol% of the diol component B, 0.5 to 99.5, preferably 0.5 to 50 mol% c3 and from 0 to 50, preferably from 0 to 35 mol% c4, based on the molar amount of B, c3 and c4, can be used for the preparation of the partially aromatic polyesters.

The 2, 2'-bisoxazolines c5 of the general formula III are generally obtainable by the process from Angew. Chem. Int. Edit., Vol. 11 (1972), pp. 287-288. Particularly preferred bisoxazolines are those in which R ^{1 is} a single bond, a (CH ₂ ) _q -alkylene group with q = 2, 3 or 4, such as methylene, ethane-1,2-diyl, propane-1,3-diyl , Propane-1, 2-diyl, or a phenylene group. Particularly preferred bisoxazolines 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-bisJ2-oxazolinyl) butane, in particular special 1, -bis (2-oxazolinyl) benzene, 1, 2-bis (2-oxazolinyl) benzene or 1, 3-bis (2-oxazolinyl) benzene.

For the preparation of the partially aromatic polyesters, for example from 70 to 98 mol% B1 to 30 mol% c3 and 0.5 to 30 mol% c4 and 0.5 to 30 mol% c5, in each case based on the sum of the molar amounts of the components B1 , c3, c4 and c5 can be used. According to another preferred embodiment, it is possible to use from 0.1 to 5, preferably 0.2 to 4% by weight of c5, based on the total weight of A and B.

Natural aminocarboxylic acids can be used as component c6. These include valine, leucine, isoleucine, threonine, methionine, phenylalanine, tryptophan, lysine, alanine, arginine, aspartic acid, cysteine, glutamic acid, glycine, histidine, proline, serine, tryosine, asparagine or glutamine.

Preferred aminocarboxylic acids of the general formulas 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 consisting of phenylene and - (CH ₂ ) _n -, where n is 1, 5 or 12.

Furthermore, c6 can also be a polyoxazoline of the general formula V. C6 can also be a mixture of different aminocarboxylic acids and / or polyoxazolines.

According to a preferred embodiment, c6 can be used in amounts of 0.01 to 50, preferably 0.1 to 40,% by weight, based on the total amount of components A and B.

Other components that can optionally be used to prepare the partially aromatic polyesters include compounds dl which contain at least three groups capable of ester formation.

The compounds dl preferably contain three to ten functional groups which are capable of forming ester bonds. Particularly preferred compounds dl have three to six functional groups of this type in the molecule, in particular three to six hydroxyl groups and / or carboxyl groups. Examples include:

Tartaric acid, citric acid, malic acid; Trimethylolpropane, trimethylolethane; pentaerythritol; polyether triols; glycerol; trimesic; Trimellitic acid, anhydride; Pyromellitic acid, dianhydride and hydroxyisophthalic acid.

The compounds dl are generally used in amounts of 0.01 to 15, preferably 0.05 to 10, particularly preferably 0.1 to 4 mol%, based on component A.

One or a mixture of different isocyanates is used as component d2. For example, aromatic or aliphatic diisocyanates can be used. However, higher functional isocyanates can also be used.

In the context of the present invention, an aromatic diisocyanate d2 is primarily

Toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, naphthylene-1, 5-diisocyanate or xylylene - understood diisocyanate.

Among them, 2,2'-, 2,4'- and 4,4'-diphenylmethane diisocyanate are particularly preferred as component d2. In general, the latter diisocyanates are used as a mixture.

Tri (4-isocyanophenyl) methane can also be used as the trinuclear isocyanate d2. The multinuclear aromatic diisocyanates are obtained, for example, in the production of mononuclear or dinuclear diisocyanates.

In minor quantities, e.g. Up to 5% by weight, based on the total weight of component d2, component d2 can also contain ureothione groups, for example for capping the isocyanate groups.

In the context of the present invention, an aliphatic diisocyanate d2 is primarily linear or branched alkylene diisocyanates or cycloalkylene diisocyanates having 2 to 20 carbon atoms, preferably 3 to 12 carbon atoms, for example 1,6-hexamethylene diisocyanate, isophorone diisocyanate or methylene bis (4- isocyanatocyclohexane), understood. Particularly preferred aliphatic diisocyanates d2 are 1,6-hexamethylene diisocyanate and isophorone diisocyanate. The preferred isocyanurates include the aliphatic isocyanates, which are derived from alkylene diisocyanates or cycloalkylene diisocyanates having 2 to 20 carbon atoms, preferably 3 to 12 carbon atoms, for example isophorone diisocyanate or methylene bis (4-isocyanatocyclohexane). The alkylene diisocyanates can be linear or branched. Isocyanurates based on n-hexamethylene diisocyanate, for example cyclic trimers, pentamers or higher oligomers of n-hexamethylene diisocyanate, are particularly preferred.

In general, component d2 is used in amounts of 0.01 to 5, preferably 0.05 to 4 mol%, particularly preferably 0.1 to 4 mol%, based on the sum of the molar amounts of A and B.

In general, all customary and commercially available divinyl ethers can be used as the divinyl ether d3. 1,4-butanediol divinyl ether, 1,6-hexanediol divinyl ether or 1,4-cyclohexanedimethanol divinyl ether or mixtures thereof are preferably used.

The divinyl ethers are preferably used in amounts of from 0.01 to 5, in particular from 0.2 to 4,% by weight, based on the total weight of A and B.

Examples of preferred partially aromatic polyesters are based on the following components

A, B, dl

A, B, d2 A, B, dl, d2

A, B, d3

A, B, cl

A, B, cl, d3

A, B, c3, c4 A, B, c3, c4, c5

A, B, dl, c3, c5

A, B, c3, d3

A, B, c3, dl

A, B, cl, c3, d3 A, B, c2

These include partially aromatic polyesters based on A, B, dl or A,

B, d2 or on A, B, dl, d2 are particularly preferably based. According to another preferred embodiment, the partially aromatic polyesters are based on A, B, c3, c4, c5 or A, B, dl, c3, c5. The production of the partially aromatic polyesters is known per se or can be carried out according to methods known per se.

The preferred partially aromatic polyesters are characterized by a molecular weight (Mn) in the range from 8000 to

100,000, in particular in the range from 9,000 to 75,000 g / mol, preferably in the range from 10,000 to 50,000 g / mol and a melting point in the range from 60 to 170, preferably in the range from 80 to 150 ° C.

The aliphatic and / or partially aromatic polyesters mentioned can have hydroxyl and / or carboxyl end groups in any ratio. The aliphatic and / or partially aromatic polyesters mentioned can also be end group-modified. For example, OH end groups can be acid-modified by reaction with phthalic acid, phthalic anhydride, trimellitic acid, trimellitic anhydride, pyromellitic acid or pyromellitic anhydride.

Component ii) of the polyester film is one or more compounds selected from iil) a surfactant or surfactant mixture, for example an anionic, cationic, amphoteric or nonionic surfactant, and ii2) polyesters with a molecular weight M _n in the range from 1000 to 7000 g / mol , in particular 1200 to 6000 g / mol, preferably 1400 to 5000 g / mol, very particularly preferably 1600 to 4000 g / mol.

Only one or more compounds iil) or exclusively one or more compounds ii2) or mixtures of in each case one or more compounds iil) and ii2) can be used as component ii).

Compounds solid at room temperature are preferably suitable as component ii).

Cationic and anionic surfactants are described, for example, in "Encyclopedia of Polymer Science and Technology", J. iley & Sons (1966), Volume 5, pages 816 to 818, and in "Emulsion Polymerization and Emulsion Polymers", editors P. Lovell and M. El-Asser, Verlag Wiley & Sons (1997), pages 224-226. Examples of anionic surfactants are alkali metal salts of organic carboxylic acids with chain lengths of 8-30 carbon atoms, preferably 12-18 carbon atoms. These are commonly referred to as soaps. They are usually used as sodium, potassium or ammonium salts. In addition, alkyl sulfates and alkyl or Alkylarylsulfonates with 8-30 C atoms, preferably 12-18 C atoms, can be used as anionic surfactants. Particularly suitable compounds are alkalidodecyl sulfates, for example sodium dodecyl sulfate or potassium dodecyl sulfate, and alkali metal salts of C ₂ -C ₆ -paraffin sulfonic acids. Sodium dodecylbenzenesulfonate and sodium dioctylsulfone succinate are also suitable.

Examples of suitable cationic surfactants are salts of amines or diamines, quaternary ammonium salts, e.g. Hexadecyltrimethylammonium bromide and salts of long-chain substituted cyclic amines, such as pyridine, morpholine, piperidine. In particular, quaternary ammonium salts, e.g. Hexadecyltrimethylammonium bromide used by trialkylamines. The alkyl radicals preferably have 1 to 20 carbon atoms.

In particular, nonionic surfactants can be used as component iil) according to the invention. Nonionic surfactants are described, for example, in CD Rompp Chemie Lexikon - Version 1.0, Stuttgart / New York: Georg Thieme Verlag 1995, keyword "nonionic surfactants".

Suitable nonionic surfactants are, for example, polyethylene oxide or polypropylene oxide-based substances such as Pluronic® or Tetronic® from BASF Aktiengesellschaft. Polyalkylene glycols suitable as nonionic surfactants iil) generally have a molecular weight M _n in the range from 1000 to 15000 g / mol, preferably 2000 to 13000 g / mol, particularly preferably 4000 to 11000 g / mol. Component ii) is preferred polyethylene glycol.

The polyalkylene glycols are known per se or can be used as catalysts and according to known methods, for example by anionic polymerization with alkali metal hydroxides, such as sodium or potassium hydroxide or alkali metal alcoholates, such as sodium methylate, sodium or potassium methylate or potassium isopropylate, with the addition of at least one Starter molecule which contains 2 to 8, preferably 2 to 6, reactive hydrogen atoms bound, or by cationic polymerization with Lewis acids, such as antimony pentachloride, boron fluoride etherate or bleaching earth, as catalysts composed of one or more alkylene oxides having 2 to 4 carbon atoms in the Alkylene radical can be produced.

Suitable alkylene oxides are, for example, tetrahydrofuran, 1,2- or 2,3-butylene oxide, styrene oxide and preferably ethylene oxide and / or 1,2-propylene oxide. The alkylene oxides can be used individually, alternately in succession or as mixtures. Examples of suitable starter molecules are: water, organic dicarboxylic acids, such as succinic acid, adipic acid, Phthalic acid or terephthalic acid, aliphatic or aromatic, optionally N-mono-, N, N- or N, N'-dialkyl-substituted diamines having 1 to 4 carbon atoms in the alkyl radical, such as optionally mono- and dialkyl-substituted ethylenediamine, diethylenetriamine, triethylenetetramine, 1.3 -Propylene diamine, 1,3- or

1,4-butylenediamine, 1,2-, 1,3-, 1,4-, 1,5- or 1,6-hexamethylene diamine.

Other suitable starter molecules are: alkanolamines, e.g. Ethanolamine, N-methyl and N-ethylethanolamine, dialkanolamines, e.g. Diethanolamine, N-methyl and N-ethyl-diethanolamine, and trialkanolamines, e.g. Triethanolamine, and ammonia. Polyhydric, in particular di-, tri-or higher alcohols, such as ethanediol, 1,2-propanediol and 1,3, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, glycerol, trimethylolpropane, are preferably used. Pentaerythritol, and sucrose, sorbitol and sorbitol.

Also suitable as component iil) are esterified polyalkylene glycols, for example the mono-, di-, tri- or polyesters of the polyalkylene glycols mentioned, which have already been described by reaction of the terminal OH groups of the polyalkylene glycols mentioned with those as components al) or a2) Acids, preferably adipic acid or terephthalic acid, can be prepared in a manner known per se. Polyethylene glycol adipate or polyethylene glycol terephthalate is preferred as component iil).

Particularly suitable nonionic surfactants are substances produced by alkoxylation of compounds with active hydrogen atoms, for example adducts of ethylene oxide with fatty alcohols, oxo alcohols or alkylphenols. Ethylene oxide or 1,2-propylene oxide are preferably used for the alkoxylation.

Further preferred nonionic surfactants are alkoxylated or non-alkoxylated sugar esters or sugar ethers.

Sugar ethers are alkyl glycosides obtained by reacting fatty alcohols with sugars, sugar esters are obtained by reacting sugars with fatty acids. The sugar, fatty alcohols and fatty acids necessary for the production of the substances mentioned are known to the person skilled in the art.

Suitable sugars are described, for example, in Beyer / Walter, Textbook of Organic Chemistry, S. Hirzel Verlag Stuttgart, 19th Edition, 1981, pp. 392 to 425. Particularly suitable sugars are D-sorbitol and the sorbitans obtained by dehydrating D-sorbitol.

Suitable fatty acids are saturated or mono- or polyunsaturated, unbranched or branched carboxylic acids with 6 to 26, preferably 8 to 22, particularly preferably 10 to 20 C atoms, such as, for example, in CD Rompp Chemie Lexikon - Version 1.0, Stuttgart / New York: Georg Thieme Verlag 1995, keyword "fatty acids". Preferred fatty acids are lauric acid, palmitic acid, stearic acid and oleic acid.

Suitable fatty alcohols have the same carbon skeleton as the compounds described as suitable fatty acids.

Sugar ethers, sugar esters and the processes for their preparation are known to the person skilled in the art. Preferred sugar ethers are prepared by known processes by reacting the sugars mentioned with the fatty alcohols mentioned. Preferred sugar esters are prepared by known processes by reacting the sugars mentioned with the fatty acids mentioned. Preferred sugar esters are mono-, di- and triesters of sorbitans with fatty acids, in particular sorbitan monolaurate, sorbitan dilaurate, sorbitan trilauate, sorbitan monooleate, sorbitan dioleate, sorbitan trioleate, sorbitan monopalmitate, sorbitan undipalmitate, sorbitan tritanalostearate, sorbitan sorbitol, mixture and sorbitan Diesters of oleic acid.

Very particularly suitable components iil) are alkoxylated sugar ethers and sugar esters, which are obtained by alkoxylation of the sugar ethers and sugar esters mentioned. Preferred alkoxylating agents are ethylene oxide and 1,2-propylene oxide. The degree of alkoxylation is generally between 1 and 20, preferably 2 and 10, particularly preferably 2 and 6. Particularly preferred alkoxylated sugar esters are polysorbates which pass through

Ethoxylation of the sorbitan esters described above can be obtained, for example described in CD Rompp Chemie Lexikon - Version 1.0, Stuttgart / New York: Georg Thieme Verlag 1995, keyword "Polysorbate". Particularly preferred polysorbates are polyethoxy sorbitan laurate, stearate, palmitate, tri-stearate, oleate, -trio- leat, in particular polyethoxysorbitan, which is available for example as Tween ^® 60 of ICI America Inc. (described for example in CD Römpp Chemie Lexikon - Version 1.0, Stuttgart / New York: Georg Thieme Verlag 1995, keyword "Tween ^® "). Suitable polyesters ii2) are the same as those mentioned in the description of the polyester i), with the exception that the molecular weight M _{n of} the polyester ii2) in the range from 1000 to 7000 g / mol, in particular 1200 to 6000 g / mol, is preferred 1400 to 5 5000 g / mol, very particularly preferably 1600 to 4000 g / mol.

Of course, the compounds ii2) can be used independently of the compounds i).

10 Since the molecular weights M _n of ii2) and i) are average values of a distribution function, it is entirely possible that, for example, individual polymer molecules of ii2) have a higher molecular weight than individual polymer molecules of i). It is essential to the invention, however, that the polymer molecules of i) on average

15 have a higher molecular weight than that of ii2).

Particularly suitable polyesters ii2) are aliphatic or partially aromatic, in particular biodegradable, aliphatic or partially aromatic polyesters.

20

Biodegradable partially aromatic polyesters ii2) are preferred. Biodegradable, partially aromatic branched polyesters, the OH end groups of which are acid-modified, are particularly preferred, for example by reaction with phthalic acid, phthalic acid,

25 reanhydride, trimellitic acid, trimellitic anhydride, pyromellitic acid or pyromellitic anhydride.

In a further particularly preferred embodiment, aliphatic polyesters composed of adipic acid 30 and 1,2-propylene glycol are suitable as component ii2), for example Palamoll® 636 from BASF Aktiengesellschaft, a polyester with a molecular weight M _n of 2400 g / mol.

The polyester films according to the invention usually contain from 35 70 to 99.9% by weight, preferably from 85 to 99.9% by weight, particularly preferably from 90 to 99.8% by weight, in particular from 95 to 99.7% by weight % Component i), and from 0.1 to 30.0% by weight, preferably from 0.1 to 15.0% by weight, particularly preferably from 0.2 to 10% by weight, in particular from 0.3 to 5% by weight of component ii), the 40% by weight of components i) to ii) totaling 100%.

If only compounds of component iil) are used as component ii), the polyester films according to the invention usually contain from 95 to 99.9% by weight, preferably 45 from 97 to 99.9% by weight, particularly preferably from 98 to 99, 8% by weight, component i), and from 0.1 to 5% by weight, preferably from 0.1 to 3% by weight, particularly preferably from 0.2 to 2% by weight, component ii), the weight percent of components i) to ii) together giving 100%.

The compounds of component ii) can act in polyesters i) on the one hand as so-called nucleating agents, i.e. when a corresponding polyester melt is cooled, they lead to increased nucleation and a shorter crystallization time compared to polyesters without component ii).

The presence of component ii) in the polyester films according to the invention can furthermore lead to a higher transparency, to an increased adhesion, i.e. to an increased tendency to stick to both other materials and to the material of the polyester films according to the invention itself or to improved anti-fogging properties, i.e. reduced precipitation in the form of small drops due to condensing water vapor on the polyester film (instead, an anti-fog additive leads to the formation of larger flat drops or to the formation of water films, as a result of which the transparency, for example of a film, is less reduced), or lead to an improvement in several of these properties.

Can quietly one stage or subsequently, for example in a melt of the polyester or, together with the incorporation of component ii), incorporated - The polyester films and / or the polyester i) may contain additives, which can during the polymerization process in ir ^'. Stabilizers, neutralizing agents, lubricants and release agents, antiblocking agents, other nucleating agents, dyes or fillers not falling under the definition of ii) are mentioned as examples.

Based on the polyester i), from 0 to 80% by weight of additives can be added. Suitable additives are, for example, fillers, stabilizers, nucleating agents not falling under the definition of ii), such as e.g. Talc, or lubricant and mold release agent. Such additives are e.g. described in detail in Kuns Stoff-Handbuch, Vol. 3/1, Carl Hanser Verlag, Munich, 1992, pp. 24 to 28.

Examples of fillers are particulate substances such as calcium carbonate, clay minerals, calcium sulfate, barium sulfate, titanium dioxide, carbon black, lignin powder, iron oxide, which can also act as coloring constituents, and fiber materials, for example cellulose fibers, sisal and hemp fibers. The proportion of fillers is generally not more than 40% by weight, based on the total weight of the film material, in particular not more than 20% by weight.

Stabilizers are e.g. Tocopherol (vitamin E), organic phosphorus compounds, mono-, di- and polyphenols, hydroquinones, diarylamines, thioethers, melamine or urea. Antiblocking agents e.g. Talc, chalk, mica or silicon oxides into consideration. Lubricants and mold release agents are generally substances based on hydrocarbons, fatty alcohols, higher carboxylic acids, metal salts of higher carboxylic acids such as calcium or zinc stearate, fatty acid amides such as erucic acid amide and wax types, e.g. Paraffin waxes, beeswax, montan waxes and the like. Preferred release agents are erucic acid amide and / or wax types and particularly preferably combinations of these two types of release agent. Preferred wax types are beeswaxes and ester waxes, in particular glycerol monostearate. The polyesters i) used to produce the polyester films according to the invention are particularly preferably equipped with 0.05 to 2.0% by weight erucic acid amide or 0.1 to 2.0% by weight wax types, in each case based on the plastic content of the polyester films. The polyesters i) used for producing the polyester films according to the invention with 0.05 to 0.5% by weight of erucic acid amide and 0.1 to 1.0% by weight of wax types, in particular glycerol monostearate, are in each case based on the plastic content of polyester films.

Component ii) can be introduced into the polyester i) by known processes and with the aid of known mixing devices (see, for example, Saechtling, Kunststoff-Taschenbuch, Hanser Verlag, Munich, Vienna, edition 26, 1995, pages 191J to 246). For example, component ii), for example with the aid of a screw machine, e.g. an extruder, in a separate process step before the actual film production or else directly into the melt from which the film is to be produced, either in pure form or as a so-called "master batch", in component i).

In general, these masterbatches are special molding compositions in which the required additives or additives, for example component ii), are embedded in a matrix of, for example, thermoplastic polymer, for example component i), but the additive content in comparison to conventional additive molding compositions is significantly higher, for example in the range from 10 to 70% by weight. By adding appropriate amounts of a masterbatch to one, for example Non-additive thermoplastics can then be made into molding compositions with the usual additive contents.

The polyester films according to the invention can be produced in an analogous manner to the production of the known polymer films. As a rule, one of the aforementioned polyester i), which is generally thermoplastic, will be processed into a film by known processes. Processing to films in thermoplastic polyesters is usually carried out by extrusion or coextrusion, in particular tubular films or

Chill-roll extrusion, or extrusion or coextrusion coating.

The respective thickness of the film depends on the intended use or on the type of polyester film. It is usually in the range from 8 to 1000 μm and in particular in the range from 10 to 100 μm. Cling film for e.g. Foodstuffs preferably have a thickness of 10 to 30 μm, in particular 10 to 22 μm.

The film material according to the invention can also be combined with stiff carrier materials, e.g. with paper / cardboard, films made of polylactides, polyester amides or nonwovens made of biodegradable materials in order to give the polyester film according to the invention increased rigidity. Of course, the polyester films of the invention can be colored, e.g. by incorporating appropriate dyes or pigments into the plastic matrix or by printing with suitable colorants.

The polyester films of the invention can be stretched during or after their manufacture. The stretching process can e.g. biodegradable polyester films with increased service life, i.e. low tendency to decay when in use, with the same biodegradability. The polyester films according to the invention can be stretched both monoaxially and biaxially. In general, the stretching ratio in the longitudinal direction is at least 1: 2.0. Usually it is not above 1:10. The stretch ratio is preferably in the range from 1: 3 to 1: 6. The stretch ratio in the transverse direction is also generally from 1: 2.5 to 1:10, preferably from 1: 3 to 1: 6.

Methods for stretching films are known to the person skilled in the art (see, for example, US Pat. No. 3,456,044). As a rule, the polyester films of the invention are stretched above the glass transition temperature or below their crystallite melting temperatures of the polymers on which they are based. In a preferred embodiment, temperatures in the range from 0 to 100, in particular stretched from 20 to 60 ° C. The stretching process can be carried out in one or more steps.

This can be achieved, for example, by guiding solidified polyester films according to the invention over rollers at different speeds of rotation. In the case of biaxially oriented polyester films according to the invention, the width of the polyester film can be stretched simultaneously or in two steps by means of laterally attached devices, so-called clip chains. In the case of tubular films, the biaxial stretching usually takes place simultaneously during the extrusion over the air enclosed in the bladder. The inflation ratio provides information about the orientation of the film in the circumferential direction under otherwise constant boundary conditions. The ratio of the take-off speeds of the last to the first pair of rollers indicates the degree of longitudinal orientation. The degree of orientation of the film can be influenced via the cooling air temperature and the cooling air duct. In general, the degree of orientation increases with falling cooling air temperature if a sufficiently high cooling air flow and an adequate cooling air flow can be realized.

In the case of biaxially oriented tubular films, for example, a pressure of 1 to 3 bar is introduced into the tube, the pressure being dependent on the desired dimensions of expansion of the film.

In order to achieve good stretchability and reproducible caliber accuracy (thickness accuracy) with biaxially oriented polyester films, it is advantageous, however, after the molten discharge from the extruder nozzle in a first stage on chilli roll rollers with a non-stick coating (eg polyterafluoroethylene PTFE, titanium nitrite) to cool to temperatures from 0 to 25 ° C, preferably 3 to 10 ° C and then heat in a second stage to temperatures of 30 to 95 ° C, preferably 50 to 80 ° C and then stretch ,

After stretching the polyester films, they can be heat set with heated rollers or with hot air (approx. 75 to 150 ° C, preferably 100 to 120 ° C). For this purpose, the polyester films are passed, for example, on rollers through a closed container with a temperature-controlled air flow or steam flow. The residence time is usually 1 to 20 s, preferably 2 to 5 s. In particular for the production of cling film, the polyester films according to the invention can be wound with contact winders suitable for elastic thin films to form smooth, evenly cylindrical film rolls.

The polyester film according to the invention is particularly well suited for all applications in which increased transparency, improved adhesion to other materials as well as to the material of the polyester film according to the invention and / or improved anti-fogging properties are of particular importance.

This is the case, for example, when used as packaging film or cling film, in particular for packaging foods such as meat, fish, seafood, dairy products, egg products, vegetables, salads, fruits, nuts, berries, mushrooms.

The polyester films according to the invention may be the sole packaging material or, together with other materials, for example paper, cardboard and / or documents, from foamed so-called "trays" of e.g. Polystyrene, starch, starch blends or pulp can be used. If the polyester films according to the invention are used together with other materials, these other materials are preferably biodegradable.

The polyester film of the invention provides films which have increased transparency, increased adhesion and / or improved anti-fogging properties.

Examples:

Application measurements:

The molecular weight M _{n of} the polymers was determined as follows: 15 mg of the polymers were dissolved in 10 ml of hexaloisoisopropanol (HFIP). 125μl of this solution were analyzed by gel permeation chromatography (GPC). The measurements were carried out at room temperature. HFIP + 0.05% by weight trifluoroacetic acid Ka salt was used for the elution. The elution rate was 0.5 ml / min. The following column combination was used (all columns manufactured by Showa Denko Ltd., Japan): Shodex ^® HFIP-800P (diameter 8 mm, length 5 cm), Shodex ^® HFIP-803 (diameter 8 mm, length 30 cm), Shodex ^® HFIP-803 (diameter 8mm, length 30 cm). The polymers were detected using an RI detector (differential refractometry). The calibration was carried out with narrowly distributed polymethyl methacrylate standards. dards with molecular weights from M _n = 505 to M _n = 2,740,000. Elution areas outside this interval were determined by extrapolation.

The thickness of the polyester films was determined using a Digitrix 2 device from Helios Meßtechnik GmbH u. Co. KG measured.

The DSC measurements were carried out using an Exstet DSC 6200R from Seiko as follows: 6 to 10 mg of the respective samples were heated from -70 ° C. to 220 ° C. at a heating rate of 20 ° C./min. The melting point of the sample is the onset temperature of the respective melting peak. An empty sample pan was used as a reference.

6 to 10 mg of the respective polymer samples were heated from -70 ° C to 220 ° C at a heating rate of 20 ° C / min and then immediately cooled back to -70 ° C at a cooling rate of 20 ° C / min. In this cooling process, the start and end temperatures of the crystallization process were measured (corresponding to the start and end of the crystallization peak). The crystallization time results from this temperature difference and the cooling rate. An empty sample pan was used as a reference.

The adhesive properties of the polyester films were determined as follows:

The films were compared on the basis of the subjective impression of the adhesive effect (adhesion) when folding and unfolding the films. On the basis of this assessment, each was classified into one of the categories

+: moderate adhesive effect, ++: strong adhesive effect or +++: very strong adhesive effect.

The transparency of the polyester films (determination of the haze value in%) was determined in accordance with ASTM D1003-92. The respective films had a thickness of 20 μm.

The anti-fogging properties of the polyester films were determined as follows:

In a laboratory tempered to 23 ° C and 50% relative humidity, foil samples with a thickness of 20 μm each were stretched with the help of a rubber band over transparent drinking cups filled with approx. 0.1 l cold tap water with a volume of 0.5 l. The cups are stored in a refrigerator which is constantly set at 2 ° C. and removed for observation after 5, 15, 60 and 240 min.

The respective condensate formation when the 23 ° C warm air was cooled to the refrigerator temperature was checked. A film equipped with an effective anti-fogging agent is also transparent after the condensate formation, since the condensate forms, for example, a coherent, transparent film. Without an effective anti-fogging agent, the formation of a fine droplet mist on the film surface leads to a reduced transparency of the film; in the worst case, the contents packed with the film are no longer visible.

The respective form of condensate is assessed as follows:

This method of determining the anti-fogging properties of a film is based on the method described in the brochure "Atmer - Antifog agents for agricultural and food packaging films", Ciba Specialty Chemicals Inc. CH / Basel, September 1998, and simulates, for example the formation of condensate on the packaging film after the packaging of fresh products (fresh meat, cheese, vegetables, mushrooms, fruit) in the cold store or sales counter.

Starting Materials:

Component il)

Pi-1: To produce the biodegradable polyester Pi-1, 87.3 kg of dimethyl terephthalate, 80.3 kg of adipic acid, 117 kg of ι, 4-butanediol and 0.2 kg of glycerol were mixed together with 0.028 kg of tetrabutyl orthotitanate (TBOT) , wherein the molar ratio between the alcohol component and the acid component was 1.30. The reaction mixture was heated to a temperature of 180 ° C. and reacted at this temperature for 6 hours. The temperature was then increased to 240 ° C. and the excess dihydroxy compound distilled off under vacuum over a period of 3 h. 0.9 kg of hexamethylene diisocyanate were then slowly metered in at 240.degree.

The polyester Pi-1 thus obtained had a melting point of 108 ° C. and a molecular weight (M _n ) of 23000 g / mol.

Components iil:

As component iil) was reacted: P-iil-1: A polyethylene glycol having an average molecular weight of 9000 g / mol and a melting point of about 65 ° C (Pluriol E 9000 ^® from BASF Aktiengesellschaf)

P-iil-2: A polyethylene glycol with an average molecular weight of 8000 g / mol and a melting point of approx. 63 ° C (Pluriol ^® E 8005 from BASF Aktiengesellschaft)

P-iil-3: An esterified polyethylene glycol with an average molecular weight of 4000 g / mol and a melting point of approx. 60 ° C (Sokalan ^® SR 100 from BASF Aktiengesellschaft). P-iil-4: polyethoxysorbitan (Tween ^® 60 of ICI America Inc.)

P-iil-5: Polyethoxysorbitanmonooleat (Tween ^® 80 of ICI America Inc.)

For comparison, the following was used:

V-iil-1: A liquid polyethylene glycol with an average molecular weight of 600 g / mol and a melting point of approx. 20 ° C (Pluriol ^® E 600 from BASF Aktiengesellschaft).

Components ii2:

P-Ü2-1: To prepare the biodegradable semi-aromatic polyester P-Ü2-1, 87.3 kg of dimethyl terephthalate, 80.3 kg of adipic acid and 117 kg of 1,4-butanediol were mixed together with 0.028 kg of tetrabutyl orthotitanate (TBOT), the Molar ratio between alcohol components and acid components was 1.30. The reaction mixture was heated to a temperature of 180 ° C. and reacted at this temperature for 6 hours. The temperature was then raised to 240 ° C. and the excess dihydroxy compound was distilled off under vacuum over a period of 3 hours. 6.9 kg of 1,4-butanediol were then added at 220 ° C. and the mixture was reacted at this temperature for 2 h. 18.7 kg of pyromellitic dianhydride were then added at 150 ° C. and the reaction was carried out at this temperature. The polyester P-Ü2-1 thus obtained had a molecular weight (M _n ) of 2500 g / mol.

Production of polyester films:

To produce the polyester films, the starting materials listed in Table 1 were mixed in a twin-screw extruder; Component iil) was added as a batch of 20% by weight iil) and 80% by weight i). The molding compositions obtained in this way were processed at a melt temperature of 150 ° C. and an inflation ratio of 2.5: 1 on a film blowing system. Films with a thickness of approximately 20 μm were produced.

Table 1:

Properties of the polyester films:

Table 2 summarizes the properties of the polyester films. Table 2

1: For the definition of the respective classification (+ to +++, A to E) see the previous method description under the point "Application measurements".

2: n.b. = not determined

The values shown in Table 2 demonstrate the improved properties of the polyester films according to the invention.

Table 3 summarizes the DSC measurements and crystallization times of the polyester films.

Table 3:

1: T _B = start of crystallization temperature 2: T _E = end of crystallization temperature 3: T _κ = _{duration of} crystallization

The values shown in Table 3 demonstrate the suitability of component ii) as a nucleating agent in polyesters.

Claims

claims

1. Containing polyester film

i) 70 to 99.9% by weight of at least one polyester with a molecular weight M _n in the range from 8000 to 100000 g / mol and

ii) 0.1 to 30% by weight of one or more compounds selected from

iil) at least one surfactant

ii2) polyesters with a molecular weight M _n in the range from 1000 to 7000 g / mol,

or mixtures of one or more compounds iil) and Ü2),

where the weight percentages of components i) to ii) together add up to 100%.

2. Polyester film according to claim 1, wherein the polyester i) or ii2) or both polyesters i) and ii2) are constructed independently of one another from:

A) an acid component

a3) 0 to 5 mol% of a compound containing sulfonate groups,

where the molar percentages of components a1 to a3) together give 100% and

B) a diol component of at least one C ₂ to Cι ₂ -Al- kandiol or a C ₅ - to CiRj-cycloalkanediol or micro made of it

and, if desired, furthermore one or more components selected from

C) a component selected from

cl) at least one dihydroxy compound of the formula I containing ether functions

HO - [(CH ₂ ) _n -0] _m -H (I)

in which n is 2, 3 or 4 and m is an integer from 2 to 250,

c2) at least one hydroxycarboxylic acid of the formula Ila or Ilb

HO— [C (O) G 0—] _D pH ¹ [-C (O) GO—]

(Ila) (Ilb) in which p is an integer from 1 to 1500 and r is an integer from 1 to 4, and G represents a radical which is selected from the group consisting of phenylene, - (CH ₂ ) _g -, where q is an integer from 1 to 5, -C (R) H- and -C (R) HCH ₂ , where R is methyl or ethyl

c3) at least one amino-C ₂ - to -CC alkanol or at least one amino-Cs to Cio-cycloalkanol or mixtures thereof

c4) at least one diamino Ci to C ₈ alkane

c5) at least one 2, 2 'bisoxazoline of the general formula III

where R ^{1 is} a single bond, a (CH) _Z alkylene group, with z = 2, 3 or 4, or a phenylene group c6) at least one aminocarboxylic acid selected from the group consisting of the natural amino acids, polyamides with a molecular weight of at most 18000 g / mol, obtainable by polycondensation of a dicarboxylic acid with 4 to 6 C atoms and a diamine with 4 to 10 C atoms, compounds of the formulas IV a and IVb

HO- [-C (O) -TN (H) -] _S H [-C (O) -TN (H) -] _fc _1

(IVa) (IVb)

in which s is an integer from 1 to 1500 and t is an integer from 1 to 4, and T is a radical which is selected from the group consisting of phenylene, - (CH) _n -, where n is an integer from 1 to 12 means -C (R ² ) H- and -C (R ² ) HCH ₂ , where R ^{2 is} methyl or ethyl,

and polyoxazolines with the repeating unit V

in which R ^{3 represents} hydrogen, C ₁ -C ₆ -alkyl, C ₅ -C ₈ cycloalkyl, unsubstituted or with C 1 -C 4 -alkyl groups up to triple-substituted phenyl or tetrahydrofuryl,

or mixtures of cl) to c6]

and

a component selected from

dl) at least one compound with at least three groups capable of ester formation,

d2) at least one isocyanate

d3) at least one divinyl ether or mixtures of dl) to d3).

3. Polyester film according to claims 1 to 2, wherein component iil) is at least one nonionic surfactant.

5

4. Polyester film according to claims 1 to 3, wherein component iil) is at least one alkoxylated or non-alkoxylated sugar ester or sugar ether.

5. Polyester film according to claims 1 to 4, wherein component iil) is at least one polysorbate.

6. Polyester film according to claims 1 to 3, wherein component iil) at least one polyalkylene glycol or polyalkylene glycol

15 ester with a molecular weight M _n in the range of 1000 to 15000 g / mol.

7. Polyester film according to claims 1 to 3, wherein component iil) is polyethylene glycol or polyethylene glycol ester.

20

8. Polyester film according to claims 1 to 7, wherein component ii2) is an aliphatic polyester composed of adipic acid and 1, 2-propylene glycol.

25 9. Polyester film according to claims 1 to 8, containing as component ii) a mixture of one or more compounds iil) and ii2).

10. Use of the polyester film according to claims 1 to 9 30 as packaging film.

11. Use of the polyester film according to claims 1 to 9 as a cling film.

35 12. Use of compounds selected from iil) or ii2) or mixtures of one or more compounds iil) and ii2), according to claims 1 to 9, to increase the transparency of polyester films.

40 13. Use of compounds selected from iil) or ii2) or mixtures of one or more compounds iil) and ii2), according to claims 1 to 9, as nucleating agents for polyesters.

45

14. Use of compounds selected from iil) or ii2) or mixtures of one or more compounds iil) and ii2), according to claims 1 to 9, to increase the adhesion of polyester films.

15. Use of compounds selected from iil) or ii2) or mixtures of one or more compounds iil) and ii2), according to claims 1 to 9, as anti-fogging agents for polyester films.