DE102006059888A1 - Biaxially oriented mono or multilayered polyester film stabilized against ultraviolet light comprises substituted triazine compounds - Google Patents

Abstract

Biaxially oriented mono or multilayered polyester film comprises at least one substituted [1,3,5]triazine compounds as ultraviolet light stabilizer. Biaxially oriented mono or multilayered polyester film (A1) comprises at least one substituted [1,3,5]triazine compounds of formula (I) as ultraviolet light (UV) stabilizer. R 1H, 1-12C alkyl, aryl, S-1-12C alkyl, O-R 9 or O-1-5C alkylene-C(O)O-R 9; R 9aryl or 1-12C alkyl; R 3 and R 4phenyl (substituted by R 8 and at 4th position by R 7);and R 2, and R 5-R 8H, 1-12C alkyl, O-1-12C alkyl, aryl or O-aryl. The alkyl radicals with more than two C-atoms and alkylene radicals with more than one C-atom can be linear or branched. An independent claim is included for manufacturing the polyester film (A1) involving compressing and plastifying a polymer or a polymer mixture for a layer, or in case of multilayer films for the individual layers, in an extruder(s); forming the compressed and plastified polymer through a single or multilayer nozzle into a flat plastified film; pressing the flat plastified film through a slit die; drawing off the pressed film via a chill roll and at least one take-up rolls; biaxially stretching, heat setting and winding up the drawn-off film, where at least one layer of the film comprises the UV stabilizer (I). [Image].

Description

The The invention relates to a stabilized against UV light, on or multilayer polyester film. The invention further relates a method of making the film and its use.

UV stabilizers for polymers are known and originate essentially from the substance groups triazines, benzotriazoles, benzophenones, sterically hindered amines (Hals = hindered amine light stabilizer) and many others. A list can be found z. In DE-A-101 35 795 , UV-stabilized, oriented polyester films are also known, and the particular effectiveness of stabilizers from the class of triazines for oriented films is also described (see, for example, US Pat. WO 98/06575 ).

In WO 98/06575 Reference is also made to the different suitability within the class of triazines and the commercially available Tinuvin 1577 (= 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5- (hexyl) oxyphenol, Manufacturer Ciba SC, CH) has been found to be particularly suitable.

Also the DE-A-101 35 795 teaches that there are differences within the group of triazines, and proposes a number of new and known triazines for use in films. Although polyester films are mentioned in this document, only polyolefin films are exemplified. Triazines with bisphenyl units (examples of compounds a / b / c / d / e / f / g) are mentioned as suitable, but the commercially available Tinuvin 1577 (compound j) is also mentioned as being particularly suitable. There are also combinations with other UV stabilizers, including compounds from the HALS group. Overall, the potential stabilizers mentioned in the formulas add up to several thousand because of the large number of possible variations. Polyolefins (especially aromatic polyesters) do not appear to be transferable since the UV absorptions and the processing conditions clearly differ and the stabilizers correspondingly differ Have to have properties.

Both the DE-A-101 35 795 as well as the WO 98/06575 call Tinuvin 1577 a particularly suitable, preferred stabilizer.

In spite of however, Tinuvin 1577 still has considerable advantages Disadvantages, especially when processing in oriented polyester films. For example, Tinuvin 1577 has other non-polymeric UV stabilizers as well in the melt no appreciable viscosity of the total viscosity of the melt. Since it is metered in concentrations of 1 to 5 wt .-% must be in order to commercially usable UV stabilities (at least usually 5 years life span under outdoor weather conditions under Central European climatic conditions or 2 years Floridatest), it comes in the film production to a significant viscosity drop. This is undesirable and leads to tears, streaks and other production disruptions. It continues when using triazine compounds to develop an odor, many of them as annoying is felt. Furthermore Triazine compounds such as Tinuvin 1577 have a residual absorption in the visible light spectrum, which leads to a yellowing of the film.

task It was the object of the present invention to overcome the above-mentioned disadvantages to overcome and polyester films available which are at least as good as their UV stability like those equipped with Tinuvin in 1577; preferably should she re this property even polyester films, which with Tinuvin 1577 equipped are, superior be. think is called thereby, that at lower application concentration an equal length or longer stability across from UV rays results. A lower use concentration has thereby in addition to the obvious economic benefits also considerable technical advantages.

wobei
R₁ -H, C1-C12-Alkyl, -Aryl, -S-(C1-C12)-Alkyl oder -O-R₉ oder -O-(C1-C5)-Alkylen-C(O)O-R₉ bedeutet, wobei
R₉ -Aryl oder C1-C12-Alkyl bedeutet,

R₂, R₅, R₆, R₇ und R₈ unabhängig voneinander (C1-C12)-Alkyl, -O-(C1-C12)-Alkyl, -Aryl und -O-Aryl bedeuten,
wobei die genannten Alkylreste mit mehr als zwei C-Atomen und die Alkylenreste mit mehr als einem C-Atom linear oder verzweigt sein können.This object is achieved by the use of UV stabilizers of the following structural formula (I):

in which
R _{1 is} -H, C 1 -C 12 -alkyl, -aryl, -S- (C 1 -C 12) -alkyl or -OR ₉ or -O- (C 1 -C 5) -alkylene-C (O) OR ₉ , where
R _{9 is} aryl or C 1 -C 12 -alkyl,

R ₂ , R ₅ , R ₆ , R ₇ and R ₈ independently of one another are (C 1 -C 12) -alkyl, -O- (C 1 -C 12) -alkyl, -aryl and -O-aryl,
wherein said alkyl radicals having more than two carbon atoms and the alkylene radicals having more than one carbon atom may be linear or branched.

Preference is given to compounds of the formula I in which
R _{1 is} -OR ₉ or -O-CH (CH ₃ ) -C (O) OR ₉ , with
R ₉ is hexyl, heptyl or octyl and
R ₂ , R ₅ , R ₆ , R ₇ and R ₈ -H
mean.

Particular preference is given to compounds of the formula I in which
R _{1 is} -O-CH (CH ₃ ) -C (O) OR ₉ , with
R ₉ is octyl and
R ₂ , R ₅ , R ₆ , R ₇ and R ₈ -H
mean.

Aryl is unsubstituted or substituted by OH, Cl, Br, J, NO ₂ , NH ₂ , SO ₃ H, COOH, C 1 -C 4 -alkyl or C 1 -C 4 -alkyloxy mono- or polysubstituted phenyl, pyridyl, naphthyl, indanyl or indenyl , preferably phenyl, more preferably unsubstituted phenyl.

Especially preferred is the 2- (2-hydroxy-4- [1-octyloxycarbonylethoxy] phenyl) -4,6-bis (4-phenylphenyl) -1,3,5-triazine available as Tinuvin 479 from Ciba SC (CH).

The UV stabilizers mentioned in concentrations of 0.1 to 10 wt.%, Preferably 0.25 to 4 wt.% And particularly preferably of 0.4 to 2.5 wt.% Used.

at Use of the particularly preferred Tinuvin 479 can be with half Tinuvin 1577 concentration achieve the same UV stability.

The in the following indicated weight percentages refer to - if nothing else is stated - always on the mass of that layer in which the substance in question is set.

The Polymer of the base layer B and the remaining layers of the film (without consideration the UV stabilizer and the other additives mentioned below) preferably consists of at least 80 wt .-% of a thermoplastic Polyester. Therefore Polyesters of ethylene glycol and terephthalic acid (= polyethylene terephthalate, PET), ethylene glycol and naphthalene-2,6-dicarboxylic acid (= polyethylene-2,6-naphthalate, PEN), 1,4-bis-hydroxymethylcyclohexane and terephthalic acid [= poly (1,4-cyclohexanedimethylene terephthalate, PCDT) and ethylene glycol, naphthalene-2,6-dicarboxylic acid and Biphenyl-4,4'-dicarboxylic acid (= polyethylene-2,6-naphthalate bibenzoate, PENBB) and polyesters of isophthalic acid and ethylene glycol as well from any mixtures of said carboxylic acids and diols. Especially preferred are polyesters which are at least 90 mol%, preferably at least 95 mol%, from ethylene glycol and terephthalic acid units or from ethylene glycol and naphthalene-2,6-dicarboxylic acid units consist. The remaining monomer units are derived from other aliphatic, cycloaliphatic or aromatic diols or dicarboxylic acids.

Suitable other aliphatic diols are, for example, diethylene glycol, triethylene glycol, aliphatic glycols of the general formula HO- (CH ₂ ) _n -OH, where n is 1 to preferably less than 10.

in the Polymer for the foil can further up to 20 wt .-% other polymers such. B. polyolefins (eg cycloolefin copolymers, polypropylene etc.), polyamides or Be contained polyetherimides. Preferably, however, this proportion is less than 10% by weight, and more preferably the polymer to 100 wt .-% of the aforementioned polyester.

The Foil may additionally contain usual additives such as stabilizers and / or antiblocking agents. Antiblocking agents are preferably used in the outer layers (layers A and C) of a multilayer film (ABC, B = base layer) used. As stabilizers, for example, phosphorus compounds such phosphoric acid or phosphoric acid ester used. Other additives are z. B. radical scavengers / thermal stabilizers (z. Irganox, Irganox 1010 preferred).

Typical antiblocking agents are inorganic and / or organic particles, for example calcium carbonate, crystalline or amorphous silica (SiO ₂ ), talc, magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, lithium phosphate, calcium phosphate, magnesium phosphate, aluminum oxide, aluminum silicates, lithium fluoride, calcium, barium, Zinc or manganese salts of the dicarboxylic acids used, titanium dioxide, kaolin or crosslinked polystyrene, PMMA or acrylate particles.

As an antiblocking agent it is also possible to choose mixtures of two or more different antiblocking agents or mixtures of antiblocking agents of the same composition but different particle size. The antiblocking agents can the individual layers of the film in the respective advantageous concentrations, for. B. be added as a glycolic dispersion during the polycondensation or masterbatches in the extrusion. The concentrations of the antiblocking agents are usually not more than 5% by weight, preferably not more than 1% by weight, and that of the white pigments, such as TiO _2, not more than 20% by weight.

In addition to the UV stabilizers according to the invention, if appropriate, other UV stabilizers (for example other triazines, benzophenones etc.) can be used (for a selection cf. DE-A-101 35 795 , Page 8, point 2), the concentration of which is preferably less than 2% by weight and more preferably less than 0.5% by weight. Unfavorable compounds from the HALS group (hindered amine light stabilizers, hindered amines, s. DE-A-101 35 795 ). On the one hand could - in contrast to the example in Example 7 of the DE-A-101 35 795 extended life for a PP film - when using HALS stabilizers in polyester films, no appreciable life extension under UV irradiation is measured; In addition, it came during the weathering to a beginning already after 500 hours yellowing and also to a clear yellowing when the film was regenerated for reuse.

In the most preferred embodiment The invention, in addition to the invention no further UV stabilizers used.

In a preferred embodiment of the invention, from 0.01 to 1% by weight, preferably from 0.01 to 0.1% by weight, of radical scavengers (antioxidants) are added to one or more layers of the film. For a selection of radical scavengers (antioxidants) s. DE-A-101 35 795 , Page 7, item 1. Irganox 1010 (CAS No. 6683-19-8) or the stabilizer with CAS no. 065140-91-2 from Ciba SC (CH).

In a further preferred embodiment the invention, the film is flame-resistant. As flame stabilizers are preferably used organic phosphorus compounds in the polyester soluble are. Particularly preferred are phosphorus compounds, which in the Polyester chain are incorporated, and again preferred those, in which the / the phosphorus atoms not in the main, but in a side chain are installed. An example of such a connection, the can be incorporated into the polyester chain, the ester with the CAS-No. 63562-34-5. The flame retardant is generally used in added to such a concentration that the phosphorus content the flame retardant is 0.1 to 2 wt.%.

The Total thickness of the polyester film according to the invention is 1 to 500 μm, in particular 10 to 50 μm, preferably 12 to 30 microns.

The Foil is either single or multi-layered, with all mentioned Feed materials independently can be distributed in the layers. With multilayer film, it has proved to be advantageous when the light-facing cover layer (or bilateral Exposure and at least three-layer films both cover layers) contains more UV stabilizer as the inner layer (s).

Economically and technically particularly favorable are embodiments, in which in more than two-layer films more than 25% and preferably more than 30%, and more preferably more than 35%, of the UV stabilizer in the outer layer (s) are located, and more preferably are in an outer layer more than 25% and preferably more than 30% and more preferably more than 35% of the stabilizer.

It has been doing well proven when no layer more than 7 wt .-% and preferably no layer contains more than 5 wt .-% UV stabilizer, as by the stretching process increase in crystallinity causes the solubility of the UV stabilizer reduced in the polyester matrix and it to exude the stabilizer can come. Here, Tinuvin 479 has proven to be particularly favorable since this apparently reacts with the polyester matrix and covalent Bindings and thus has a particularly low migration.

In multi-layered embodiments, it has proved to be advantageous if at least the first two layers facing the incident light contain UV stabilizer. The proportion of UV stabilizer should preferably not be less than 0.1% by weight in any of these two layers. It has become transparent Embodiments (transparency> 50%) proved to be favorable when all layers of the film contain at least 0.1 wt .-% UV stabilizer.

If the light-facing layer of the film contains less than 4% by weight of a white pigment (eg, TiO ₂ , BaSO ₄ , CaCO _3, etc.) having an average particle size d ₅₀ greater than 200 nm, it has proven favorable when the outer layer contains at least 0.75 wt .-% UV stabilizer and more preferably at least 1.0 wt .-% UV stabilizer.

In a preferred embodiment has the film according to the invention at 200 ° C a shrinkage in longitudinal and transverse direction of less than 10%, preferably less than 6% and especially preferably below 4%, on. The film also has an extension at 100 ° C of less than 3%, preferably less than 1%, and more preferably less than 0.3%, up. This dimensional stability can, for example, by suitable relaxation of the film can be obtained before winding (see process description).

In a preferred embodiment, the film also has an E-modulus in both film directions of greater than 3000 N / mm ² and preferably greater than 3500 N / mm ² and particularly preferably> 4100 N / mm ² in the longitudinal and transverse directions. The F5 values (force at 5% elongation) are preferably in the longitudinal and transverse directions at more than 80 N / mm ² and preferably above 90 N / mm ² . These mechanical properties can be obtained, for example, by suitable biaxial stretching of the film (see process description).

The shrinking and mechanical values mentioned cause the durability the film on aging by UV irradiation and other weather conditions such as Heat and water favorable being affected.

In a further preferred embodiment the film is at least one-sided with a bonding agent for printing inks coated. Suitable coatings are, for example, acrylates or copolyesters having sulfoisophthalic acid contents> 0.2% by weight.

method

The Polyester matrix polymers of the individual layers are produced by polycondensation produced, either starting from dicarboxylic acids and ethylene glycol (so-called "PTA process") or starting of the esters of dicarboxylic acids, Preferably, the dimethyl ester, and ethylene glycol (so-called "DMT method"). Usable polyethylene terephthalates preferably have SV values in the range of 600 to 900 and polyethylene-2,6-naphthalates from about 500 to 800.

The Particles - provided available - can already be added in the preparation of the polyester. To do this the particles dispersed in ethylene glycol, optionally ground, decanted, etc. and the reactor either in the (re) esterification or Polycondensation added. Preferably, alternatively, a concentrated particle-containing or additive-containing polyester masterbatch be prepared with a twin-screw extruder and in the film extrusion be diluted with particle-free polyester. One more way consists of particles and additives directly during film extrusion in a twin-screw extruder.

Not Cross-linked organic particles are either in a twin-screw extruder processed into a masterbatch or directly during the film extrusion added.

The UV stabilizers can the slide over the masterbatch technology will be added. This is a polyester raw material melted in a twin-screw extruder and the UV stabilizer added. The mixture is then extruded through a hole die and quenched in a water bath and granulated. It has as cheap proved when the levels of UV stabilizer in the masterbatch at From 1 to 33% by weight, preferably from 5 to 25% by weight, and more preferably at 10 to 20 wt .-%, are. Lower levels are rather uneconomic, and from about 25 wt .-% leads to an insufficient involvement of the UV stabilizer into the polyester matrix, which leads to visible "sweating" above 33% by weight.

The UV stabilizers can also be added directly in the film production. For this purpose, the Stabilizer in the appropriate amounts directly into the extruder dosed. this leads to but only when using multi-screw extruders (at least two) to really good distribution results.

It has also proven to be advantageous if the extruder intake with a protective gas flow over is coated (for example, nitrogen or argon), since the UV stabilizers according to the invention are sensitive to oxidative stress due to the high extrusion temperatures both in the direct extrusion on the film unit and in the masterbatch.

If Single screw extruder can be used, then it has to be advantageous proved to dry the polyester beforehand. When using a Twin-screw extruder with degassing zone can be on the drying step be waived.

First, will the polymer or the polymer mixture of the layer or in multilayer films of the individual layers in extruders compressed and liquefied. Then melt / melt in a single or multi-layer die to shallow Melting films formed, pressed through a slot die and on a chill roll and one or more take-off rolls, cooling and to solidify.

The inventive film is biaxially oriented, d. H. stretched biaxially. The biaxial stretching the slide becomes the most common performed sequentially. In this case, preferably in the longitudinal direction (ie in the machine direction = MD direction) and then in the transverse direction (i.e., perpendicular to the machine direction = TD direction) stretched. The stretching in the longitudinal direction let yourself with the help of two different according to the desired stretch ratio perform fast rolling. For cross-stretching is generally used a corresponding Tenter frame.

Instead of The sequential stretching is also a simultaneous stretching of the Foil possible, but not necessary.

The Temperature at which the stretching is carried out can be done in a relative huge Range vary and depends on the desired properties of the film. In general, the stretching becomes longitudinal in a temperature range from 80 to 130 ° C (Heating temperatures 80 to 130 ° C) and in the transverse direction in a temperature range of 90 ° C (Beg the stretch) to 140 ° C (End of stretching). The longitudinal stretching ratio is in the range of 2.0: 1 to 5.5: 1, preferably from 2.2: 1 to 5.0: 1. The transverse stretch ratio is generally in the range of from 2.4: 1 to 5.0: 1, preferably from 2.6: 1 to 4.5: 1.

To the Achieve the desired Film properties, it has proved to be advantageous if the stretching temperature (in the MD and TD directions) is below 125 ° C and preferably below 118 ° C.

In front the transverse extent can one or both surface (s) the film according to the known methods in-line coated become. For example, the in-line coating can be improved Adhesion between a metal layer or a printing ink and the Foil and to improve the antistatic behavior or the processing behavior of the film lead. When the outer coextruded layers no inorganic particles to improve the slip and winding characteristics contained, so may at this point a particle-containing coating be applied.

at the subsequent heat setting is the film over a Duration of about 0.1 to 10 s under tension at a temperature from 150 to 250 ° C and to achieve the preferred shrinkage values by at least 1%, preferably at least 3% and more preferably at least 4% relaxed in the transverse direction. This relaxation is preferred in a temperature range of 150 to 190 ° C instead. Preferably, <25% and> 5% of the total relaxation find within the first 25% of the relaxation time. Subsequently, will the foil in usual Wrapped up way.

at The production of the film is guaranteed that the regenerate in a concentration of 20 to 60 wt .-%, based on the total weight the film, the extrusion can be fed again without while the physical and optical properties of the film worth mentioning be negatively influenced.

The inventive film is characterized by a very good UV resistance, a low intrinsic color and one opposite Tinuvin 1577 reduced UV stabilizer content at the same UV stability and decreased odor in the film production. In addition, it has been shown that due the new stabilizers reduce the pressure fluctuations in film production with back and forth conversions between UV-stabilized and unstabilized types could be reduced and so less Outlines in the area of these changes occurred.

to Characterization of the raw materials and the films were the following Measurement methods used:

Measurement of the mean particle diameter d ₅₀

The determination of the mean diameter d ₅₀ is carried out by means of laser on a Horiba LA 500 by means of laser diffraction (other measuring devices are for example Malvern Master Sizer or Sympathec Helos, which use the same measuring principle). The samples are then placed in a cuvette with water and then placed in the meter. The dispersion is scanned by laser and the particle size distribution is determined from the signal by comparison with a calibration curve. The particle size distribution is characterized by two parameters, the median value d ₅₀ (= positional measure for the mean value) and the scattering ratio, the so-called SPAN98 (= measure of the scattering of the particle diameter). The measuring process is automatic and includes the mathematical determination of the d ₅₀ value. By definition, the d ₅₀ value is determined from the (relative) cumulative curve of the particle size distribution: the point of intersection of the 50% ordinate value with the cumulative curve gives the desired d ₅₀ value on the abscissa axis.

Primary grain size of nanoparticles (z. B. Aerosil ^® and Nyacol ^®)

The Determination of the mean size of the primary particles takes place on transmission electron microscopic (TEM) images of the product to be examined. If the sample as a foil or plastic granules present, the TEM examination should be performed on microtome sections.

transparency

The Transparency is measured according to ASTM-D 1033-77.

SV value (standard viscosity)

The standard viscosity SV (DCE) is measured, based on DIN 53 726, at a concentration of 1% by weight in dichloroacetic acid. From the relative viscosity (η _rel ), the dimensionless SV value is determined as follows: SV = (η rel - 1) × 1000

The intrinsic viscosity (N) correlates with the standard viscosity as follows IV [η] = 6.907 x 10 -4 SV (DCE) + 0.063096 [dl / g]

Mechanical properties

The mechanical properties are based on tensile testing to DIN EN ISO 572-1 and -3 at 100 mm × 15 mm large Film strips determined. The change in length will over measured a Traversenwegaufnehmer. The modulus of elasticity is at a Tensile speed of 10% / min as a slope between 0.2 and 0.3 Elongation determined. The σ5 value (Force at 5% elongation) is measured at a pulling speed of 100% / min.

shrink

The thermal shrinkage is determined on square film samples with an edge length of 10 cm. The samples are measured accurately (edge length L ₀ ), annealed for 15 min at 200 ° C in a convection oven and then measured accurately at room temperature (edge length L). The shrinkage results from the equation Shrinkage [%] = 100 (L 0 - L) / L 0

UV stability

The UV stability is like in DE-A-697 31 750 (DE equivalent of WO 98/06575 ) and the UTS value in% from the initial value. At the weathering time s. following examples.

Odor nuisance in production

• 1 Kein gegenüber "normaler" Polyesterfolienproduktion wahrnehmbarer zusätzlicher Geruch
• 2 Leichter zusätzlicher Geruch wahrnehmbar (nicht störend)
• 3 Deutlich wahrnehmbarer Geruch (störend)
• 4 Starker zusätzlicher Geruch (sehr störend/unangenehm)

As odor nuisance is a subjective factor, 10 employees are interviewed independently of each other after 30 min of production time for the perception of odor. Each employee rated the odor on a scale of 1-4 (see below). The assigned scale values are summed up and divided by the number of employees and output as the mean value. Scale value:

• 1 No additional odor noticeable over "normal" polyester film production
• 2 Slight additional smell perceptible (not disturbing)
• 3 clearly noticeable smell (disturbing)
• 4 Strong additional smell (very disturbing / unpleasant)

Examples

Comparative Example 1

Example 1 from DE-A-697 31 750 (DE equivalent of WO 98/06575 ) was adjusted with the following differences:
In the absence of a raw material with 6 μm silicon dioxide particles, 1.1% by weight of the Silysia 440 silicon dioxide type (from Fuji Silysia, JP, with d ₅₀ about 4.4 μm) was used. The polyethylene terephthalate raw material for the non-sealable layer (IPA content 0.05% by weight, diethylene glycol 0.7% by weight) contained 1% by weight of Tinuvin 1577 (Ciba SC, Switzerland). The Tinuvin was introduced via a masterbatch with 10 wt .-% Tinuvin 1577 in PET.

The heat stabilization (fixation) was carried out as follows: fixation temperature 225-150 ° C duration 2 s Relaxation in TD direction at 200 to 150 ° C 3 %

Of the Odor was rated 2.5.

at The conversion to this type were slight pressure fluctuations in the nozzle observed.

Of the Tensile strength value (UTS) was 69% after 1000 hours of weathering of the initial value.

example 1

As Comparative Example 1, but 0.5 wt% Tinuvin 479 (Ciba SC, CH).

Of the Odor was rated 1.4.

at the changeover to this type were no pressure fluctuations in the nozzle observed.

Of the Tensile strength value (UTS) was 74% after 1000 hours of weathering of the initial value.

Example 2

As Example 1, but 1.0 wt% Tinuvin 479 (Ciba SC, CH).

at The conversion to this type were slight pressure fluctuations in the nozzle observed.

Of the Odor was rated 1.8.

Of the Tensile strength value (UTS) was 89% after 1000 hours of weathering of the initial value.

Example 3

It a three-layered film with a thickness of 20 μm was produced.

The polymer blends were combined in an adapter and electrostatically applied through a slot die to a chill roll maintained at 60 ° C. Subsequently, the film was stretched longitudinally and then transversely under the following conditions: longitudinal stretching heating temperature 75-115 ° C stretching temperature 115 ° C Longitudinal stretching ratio 3.7 transverse stretching heating temperature 100 ° C stretching temperature 110 ° C Transverse stretching ratio 4.0 fixation temperature 237-150 ° C duration 2 s Relaxation in TD at 200-150 ° C 7 %

• 1. 70 Gew.% Polyethylenterephthalat mit einem SV-Wert von 800 mit 0,1 Gew.-% SiO₂ Silysia 340 (Fuji Silysia, JP) und 30 Gew.% eines Polyethylenterephthalatmasterbatches mit einem SV-Wert von 700 und einem Tinuvin 479-Gehalt von 20 Gew.% → Schicht A
• 2. 98 Gew.% Polyethylenterephthalat mit einem SV-Wert von 800 und 2 Gew.% eines Polyethylenterephthalatmasterbatches mit einem SV-Wert von 700 und einem Tinuvin 479-Gehalt von 20 Gew.% → Schicht B
• 3. 99 Gew.% Polyethylenterephthalat mit einem SV-Wert von 800 mit 0,1 Gew.-% SiO₂ Silysia 340 (Fuji Silysia, JP) und 1 Gew.% eines Polyethylenterephthalatmasterbatches mit einem SV-Wert von 700 und einem Tinuvin 479-Gehalt von 20 Gew.% → C-Schicht Tinuvin 479 wurde in fertiges PET-Polymer mittels eines Zweischneckenextruders eingebracht. Die SiO₂-Partikel wurden bereits bei der Polykondensation hinzugegeben. Der IPA(=Isophalsäure)-Gehalt der Polyester lag bei 0,1 Gew.-% und der DEG(Dieethylenglykol)-Gehalt bei 1 Gew.-%.

3 polymer blends were melted in 3 twin-screw extruders at 290 ° C:

• 1. 70 wt.% Polyethylene terephthalate having an SV value of 800 with 0.1 wt.% SiO ₂ Silysia 340 (Fuji Silysia, JP) and 30 wt.% Of a polyethylene terephthalate masterbatch having an SV value of 700 and a Tinuvin 479 Content of 20% by weight → layer A
• 2. 98% by weight of polyethylene terephthalate having an SV value of 800 and 2% by weight of a polyethylene terephthalate masterbatch having an SV value of 700 and a Tinuvin 479 content of 20% by weight → layer B
• 3. 99 wt.% Polyethylene terephthalate having an SV value of 800 with 0.1 wt.% SiO ₂ Silysia 340 (Fuji Silysia, JP) and 1 wt.% Of a polyethylene terephthalate masterbatch having an SV value of 700 and a Tinuvin 479 Content of 20% by weight → C layer Tinuvin 479 was introduced into finished PET polymer by means of a twin-screw extruder. The SiO ₂ particles were already added during the polycondensation. The IPA (= isophalic acid) content of the polyesters was 0.1% by weight and the DEG (diethylene glycol) content was 1% by weight.

The polymer blends were combined in an adapter and electrostatically applied through a slot die to a chill roll maintained at 60 ° C. Subsequently, the film was stretched longitudinally and then transversely under the following conditions: longitudinal stretching heating temperature 75-115 ° C stretching temperature 115 ° C Longitudinal stretching ratio 3.7 transverse stretching heating temperature 100 ° C stretching temperature 110 ° C Transverse stretching ratio 4.0 fixation temperature 237-150 ° C duration 2 s Relaxation in TD at 200-150 ° C 7 %

The film thus obtained had a total thickness of 20 microns, and the cover layer A was 5 microns and the cover layer C was 2 microns thick. The transparency was 88%, the modulus of elasticity in MD direction 4920 N / mm ² and in TD direction 5105 N / mm ² . The F5 value was 100 N / mm ² in the MD direction and 102 N / mm ² in the TD direction. Shrinkage in MD direction at 200 ° C was 2.7% and 0.1% in TD direction.

at The conversion to this type were no pressure fluctuations in the Extruder of the base layer B observed in the nozzle. Slight fluctuations in the extruder layer A had due to the thicker stable Base layer B has no influence on the running safety of the film system.

Of the Odor was rated 1.8.

The tensile strength value (UTS) was 1000 hours weathering (light incidence through layer A 91% of the initial value and after 3000 h 67% of the initial value.

Claims (17)

Biaxially oriented, single or multilayer polyester film, characterized in that it contains at least one UV stabilizer of structural formula (I):

where R _{1 is} -H, C 1 -C 12 -alkyl, -aryl, -S- (C 1 -C 12) -alkyl or -OR ₉ or -O- (C 1 -C 5) -alkylene-C (O) OR ₉ , where R _{9 is} aryl or C 1 -C 12 -alkyl,

R ₂ , R ₅ , R ₆ , R ₇ and R _{8 are} independently (C 1 -C 12) -alkyl, -O- (C 1 -C 12) -alkyl, -aryl and -O-aryl, said alkyl radicals having more than two carbon atoms and the alkylene radicals having more than one carbon atom can be linear or branched. Polyester film according to claim 1, characterized in that it contains at least one UV stabilizer of structural formula (I) in which R _{1 is} -OR ₉ or -O-CH (CH ₃ ) -C (O) OR ₉ , with R ₉ is hexyl, heptyl or octyl and R ₂ , R ₅ , R ₆ , R ₇ and R _{8 are} -H. Polyester film according to claim 1 or 2, characterized in that it contains at least one UV stabilizer of structural formula (I) in which R _{1 is} -O-CH (CH ₃ ) -C (O) OR ₉ , with R ₉ being octyl and R ₂ , R ₅ , R ₆ , R ₇ and R _{8 are} -H. Polyester film according to one of claims 1 to 3, characterized in that it is single-layered. Polyester film according to one of claims 1 to 3, characterized in that it is multi-layered. Polyester film according to one of claims 1 to 5, characterized in that it contains one or more UV stabilizers of the formula I in a concentration of 0.1 to 10 wt.% Contains (based on the mass of the layer containing the UV stabilizer is). Polyester film according to one of claims 1 to 6, characterized in that it contains one or more stabilizers and / or antiblocking agent. Polyester film according to one of claims 1 to 7, characterized in that it comprises a radical scavenger contains. Polyester film according to one of claims 1 to 8, characterized in that it contains a flame retardant. Polyester film according to one of claims 5 to 9, characterized in that it is more than two layers and more than 25% of the UV stabilizer in one or both outer layer (s) are located. Polyester film according to one of claims 5 to 10, characterized in that it is more than two layers and in an outer layer more than 25% of the UV stabilizer are. Polyester film according to one of claims 5 to 11, characterized in that no layer more than 7 wt .-% Contains UV stabilizer (based on the mass of the layer in which the UV stabilizer is contained). Polyester film according to one of claims 1 to 12, characterized in that at 200 ° C, a shrinkage in longitudinal and Transverse direction of less than 10%. Polyester film according to one of claims 1 to 13, characterized in that at 100 ° C, an extension of less than 3%. Polyester film according to one of claims 1 to 14, characterized in that it has an E-modulus of greater than 3000 N / mm ² in the longitudinal and transverse directions. Polyester film according to one of claims 1 to 15, characterized in that it has a F5 value (force at 5% elongation) in the longitudinal and transverse direction of more than 80 N / mm ² . Process for producing a polyester film according to Claim 1, wherein the polymer or the polymer mixture of the layer or in multilayer films of the individual layers in extruders compressed and liquefied is then in a single or multi-layer die to flat melt films molded, pressed through a slot die and on a chill roll and one or more take-off rolls, then stretched biaxially, heat-set and then rolled up, characterized that the polymer for at least one layer of the film is a UV stabilizer of the formula Contains (I).