EP1763437A1

EP1763437A1 - Film containing transparent metal oxide, method for the production thereof, and use thereof

Info

Publication number: EP1763437A1
Application number: EP05767880A
Authority: EP
Inventors: Holger Kliesch; Bodo Kuhmann; Thorsten Kiehne; Franz Hora
Original assignee: Mitsubishi Polyester Film GmbH
Current assignee: Mitsubishi Polyester Film GmbH
Priority date: 2004-06-24
Filing date: 2005-06-15
Publication date: 2007-03-21
Also published as: US20070248803A1; WO2006000326A1; DE102004030455A1

Abstract

The invention relates to a single-layer or multilayer, oriented film made of a thermoplastic polymer which contains at least one nanoparticulate metal oxide as an IR active component that is used for IR shielding, said metal oxide being largely transparent in the visible range. Also disclosed are a method for producing said film and the use thereof as an insulating material, e.g. in window applications and as a shield for all sorts of electrical components. The invention further relates to a method for producing the raw material containing the nanoparticulate transparent metal oxide.

Description

Film containing transparent metal oxide, process for its preparation and its use

The invention relates to a monolayer or multilayer, oriented film of a thermoplastic polymer containing at least one nanoparticulate, in the visible region substantially transparent metal oxide as an IR-active component which serves for IR shielding, a method for producing the film and their use as insulation material, eg in window applications and as a shielding of electrical components of all kinds. The invention further relates to a process for the preparation of the raw material, which contains the nanoparticulate transparent metal oxide.

Polyester films for shielding IR radiation (radiation with more than 800 nm wavelength to about 1 mm wavelength) are in many ways of great economic interest. On the one hand, they can reduce both the unwanted heating of rooms and objects in the case of IR radiation (solar radiation or other natural and artificial IR sources) and, on the other hand, the heat loss due to IR radiation.

One example is the window area, where in the summer IR protective films reduce unwanted heating of the interior and in winter the heat loss through the pane, thereby reducing energy costs in both cases.

Further applications are in the area of protective clothing in very hot or cold areas and for protection against heating of electrical components during the "surface mounting" soldering process.

In industrial practice, metals or metallized films are often used for IR shielding. However, this is only possible if no transparency in the visible range (400 to 800 nm) is necessary, as in the case of windows. Other disadvantages of metalizations include electrical conductivity, which can easily lead to short circuits or other undesired contacts in electrical components. In addition, low-cost metallizations with aluminum have limited oxidation resistance. stable, which leads in particular in humid environment or in the presence of acids and bases to a rapid loss of shielding effect.

Another method for reducing the IR radiation is the mixing of dyes that absorb and / or reflect in the IR range. Disadvantages here are either the mostly quite clear and unwanted color in the visible range or the low durability of such dyes.

To remedy this, transparent metal oxides, e.g. Based on mixed tin oxides such as indium tin oxide (ITO) or antimony tin oxide (ATO), which have a good IR reflection or absorption effect and at the same time show little or no interaction with light in the visible wavelength range.

Coatings with such materials are known (JP 2000-188432 (TDK Corp./JP) and JP 2001-099924 (Sekisui Chem. Corp. / JP)). Disadvantages of such coatings include the necessary additional coating step and the thermal stress of the layer. The last point is of particular importance, since mixed tin oxides not only reflect the IR radiation, but also absorb it to a considerable extent. If the mixed tin oxide is then present in an externally applied layer, then it heats up more strongly than the film below or above it and, as a rule, warping occurs in this layer and finally the layer spalling off.

Object of the present invention was to provide a film which does not have the disadvantages of the prior art and can be produced process-safe.

This object is achieved by a single-layer or multi-layered, at least uniaxially stretched thermoplastic polymer film with a thickness of 3 to 500 μm, preferably 8 to 100 μm and particularly preferably 12 to 50 μm, which contains 0.1 to 25.0% by weight. , preferably 0.5 to 10.0 wt .-% and particularly preferably 1, 0 to 4.0 wt .-%, based on the film contains particles of at least one transparent metal oxide. These particles have an average particle size d ₅₀ of <350 nm, preferably in the range of ≥ 7.0 to ≦ 150 nm, more preferably of ≥ 7.0 to <50 nm. In this case, a film is obtained which has a high transparency in the visible range and at the same time a low transmission in the IR range.

The transparent, nanoparticulate metal oxides are generally antimony tin oxide (ATO) and indium tin oxide (ITO), preferably indium tin oxide (ITO). However, other transparent metal oxides and mixtures of ITO and / or ATO with these other transparent metal oxides may be used, but mixtures of ITO and ATO are preferred. ATO or ITO / ATO mixtures can preferably be used if the price of the resultant film is more important than color neutrality.

The content of In ₂ O ₃ and SnO ₂ in the ITO particles of the present invention is given by the following formula: a In ₂ O ₃ + (100-a) SnO ₂ Formula 1 wherein a = 20.0 to 99.7. Preferably, a ≥ 85.0, and more preferably ≥ 90.5.

It has proved to be advantageous if the proportion of the transparent metal oxide (in percent by weight), depending on the film thickness, follows the following equation:

G% = x * Fd <-> _{FormΘ | 2}

G% = proportion of transparent metal oxide in weight percent Fd = film thickness in μm, where x (in% by weight / μm) is in the range from ≥ 10 to ≦ 250 and preferably from ≥ 40 to <100.

The film also has a high transmission in the visible wavelength range. This is in the preferred embodiment for windowpanes or car windshields at least 65%, preferably ≥ 75% and especially preferably at ≥ 80% at 650 nm. The transmission at 2000 nm, however, is <80%, preferably <60% and particularly preferably ≦ 40%.

The haze of the film generally has a value of <5.0, preferably <2.0 and in a particular embodiment for "high performance" applications such as car front glazing preferably of ≤ 1.5.

Since the film can heat locally greatly by IR-absorption, it has proved to be favorable if the film at 150 ⁰ C in any film direction has a shrinkage of about 2.5%. The shrinkage in each film direction is preferably less than 1.5%. It has also proved to be favorable when the shrinkage difference between the longitudinal and transverse directions is not greater than 1, 0%.

The good mechanical properties include, inter alia, a high modulus of elasticity in at least one film direction (longitudinal direction (MD) and / or transverse direction (TD)) or preferably in both film directions of ≥ 500 N / mm ² , preferably ≥ 2000 N / mm ² and more preferably ≥ 4000 N / mm ² .

The film according to the invention contains as main polymer constituent (i.e., at 55 to 100 wt.%, Preferably 70 to 100 wt.% And more preferably 90 to 100 wt.%) A thermoplastic polymer, generally a polyester.

According to the invention, a thermoplastic polymer is understood to mean homopolyesters, copolyesters, blends of various polyesters, these being able to be used both as pure raw materials and as polymer materials containing recycled material.

The thermoplastic polymer contains repeating units derived from dicarboxylic acids (100 mol%) and diols (also 100 mol%). The polyesters according to the invention are preferably based on terephthalic acid or 2,6-naphthalenedi carboxylic acid as the dicarboxylic acid and ethylene glycol as the diol. In a less preferred embodiment, the main diol component may also be 1,4-butanediol.

In particular, the polyesters according to the invention contain 10 to 100 mol% of terephthalate or 10 to 100 mol% of 2,6-naphthalate as dicarboxylic acid components (the total amount of dicarboxylic acid components being 100 mol%). As other dicarboxylic acid components, the polyester may be 0 to 50 mol% of 2,6-naphthalate (when terephthalate is used as the main component), 0 to 50 mol% of terephthalate (if naphthalate is used as the main component), 0 to 20 mol% of isophthalate ( preferably from 0.5 to 4 mol%) and from 10 to 60 mol% of 4,4'-diphenyldicarboxylate. For other dicarboxylic acid components, such as 1,5-naphthalenedicarboxylate, it is favorable if their proportion does not exceed 30 mol%, preferably 10 mol%, particularly preferably 2 mol%.

As the diol component, the polyester according to the invention contains 10 to 100 mol% ethylene glycol (EG) (the total amount of diol components being 100 mol%). It is favorable if the proportion of diethylene glycol does not exceed 10 mol%, it is ideally between 0.5 and 5 mol%. Other diol components such as cyclohexanedimethanol, 1,3-propanediol, 1,4-butanediol should not exceed a proportion of 50 mol% (exception being the less preferred variant with 1,4-butanediol as main diol component, ie 50 to 100 mol%) , They are preferably in a proportion of less than 30 mol%, more preferably less than 10 mol%.

In addition to the main polymer constituents mentioned, in further embodiments the film may contain up to 45% by weight, preferably up to 30% by weight, more preferably up to 20% by weight, based on the mass of the film, of other polymers such as polyetherimides (e.g. . B. Ultem ^® 1000 from GE Plastics Europe / NL), polycarbonate (such as Makrolon ^® from Bayer / DE) or polyamides (Ultramid ^® from BASF / DE) and others included.

In general, the polyesters are prepared by literature methods from said diols and dicarboxylic acid or dicarboxylic acid esters. The preparation of the polyesters can be carried out both by the transesterification process and the conventional catalyst. Toren, such as Zn, Ca, Li and Mn salts or after the direct esterification process. In order to achieve the high transparency according to the invention, it is favorable that the content of transesterification catalyst, based on the metal used, does not exceed 200 ppm. It is preferably less than 100 ppm, particularly preferably less than 50 ppm. Preferred polycondensation catalysts are antimony or germanium compounds. However, titanium compounds are particularly preferred. If antimony compounds are used, the content of antimony in a preferred embodiment is less than 210 ppm and more preferably less than 70 ppm. Antimony triacetate (eg antimony catalyst S21 from Atofina / FR) is preferably used.

Particularly preferred titanium-based catalysts are used as VERTEC ^® AC420 from Johnson Matthey or titanium catalyst C94 from Acordis. The content of titanium is preferably below 60 ppm and more preferably below 20 ppm. Furthermore, it has proved to be advantageous if all components of the catalyst system such as transesterification catalysts (eg manganese salts) and phosphorus stabilizers (eg polyphosphoric acid, phosphorous acid, phosphoric acid esters such as ethyl phosphate, diethyl phosphate, phenyl phosphate, etc.) and polycondensation catalysts such as titanium compounds together have a content of 200 ppm, preferably 100 ppm and more preferably 75 ppm.

It has also proved to be advantageous if in the polycondensation stabilizers (radical scavengers) such as Irganox ^® 1010, 1425 or 1222 (Ciba / CH) are added in concentrations between 100 and 5000 ppm, as this significantly reduces the formation of gel particles.

The preparation of the polymer raw materials which contain the transparent metal oxide is preferably carried out by one of the following two methods.

Process 1 - Production of Polyester Raw Materials (Masterbatches) in a Batch Process A dispersion of the nanoscale metal oxides in ethylene glycol is during the Polycondensation added directly to the reaction reactor. The addition can take place already at the beginning of the polycondensation (however, in the case of the transesterification process, it always takes place after completion of the transesterification), but it is preferred to add about the middle of the customary polycondensation time since this makes it possible to keep the content of color-changing by-products low At the same time, however, the viscosity of the raw material is still low enough to guarantee a rapid distribution of the nanoparticles in the raw material and thus to avoid undesirable agglomeration. In order to avoid a strong foaming of the reaction melt, the reduced pressure used in this case can be reduced by supplying dried nitrogen shortly before the addition of the nanoparticle dispersion.

Method 2 - Preparation of nanoparticle-containing masterbatches by adding the nanoparticle dispersion in a twin-screw extruder A dispersion of the nanoscale metal oxides in ethylene glycol or preferably in methyl ethyl ketone is introduced into the twin-screw extruder via a liquid metering. The preferred addition site is directly in front of or in the degassing zone. In this method, high-dose dispersions must be used, since otherwise too much solvent must be removed, that is, the content of metal oxide is more than 10 wt .-%, preferably more than 20 wt .-% and particularly preferably more than 25 wt .-%.

If twin-screw extruders are used on the film production machines, in a modification of Method 2, the dispersion can also be added directly into these extruders.

In both mentioned methods, it has proved to be advantageous if the resulting polymer melt is filtered before granulation via melt filter with a pore size for which the manufacturers a retention of at least 50% for 7 microns particles and preferably at least 50% for 5 microns Specify particles. Both commercially available sintered filter materials and fleece filters are suitable. The ITO or ATO nanoparticles are preferably used in the form of their dispersions in glycol or other organic solvents. Particularly suitable are ITO dispersions from Nanogate (Saarbrücken) have proven (preferably those used in the examples with more than 94% indium oxide in ITO).

The film according to the invention is either one or more layers. The multi-layered films consist of a base layer B, at least one cover layer A or C and optionally further intermediate layers, in particular a three-layer A-B-A or A-B-C construction being preferred. For this embodiment, it is advantageous if the polymer of the base layer B has a melt viscosity similar to that of the cover layer (s) adjacent to the base layer.

The thickness of the cover layer / s is selected independently of the other layers and is preferably in the range from 0.1 to 10.0 μm, in particular 0.2 to 5.0 μm, preferably 1.0 to 3.0 μm, wherein both sides applied cover layers may be the same or different in thickness and composition. The thickness of the base layer results accordingly from the difference between the total thickness of the film and the thickness of the applied cover and Zwischenschicht / s and therefore can vary within wide limits analogous to the total thickness.

The transparent IR-absorbing metal oxides may be contained in all layers of the film. It has proven advantageous in multilayer constructions if at least two successive layers contain these particles. It is particularly advantageous if all layers contain at least 5% of the amount of such particles, based on the amount in% of metal oxide in the layer with the highest particle amount, since so much different heating of the layers are reduced, which can otherwise lead to Delaminationsproblemen ,

In window applications in which a strong heat source (eg the sun) irradiates on one side, it has proved favorable if the layer of the film facing the light source is at least 10%, preferably at least 20% less transparent IR-absorbing metal oxide contains as the subsequent layer. For transparencies with more than two layers, these differences apply to each layer.

A special case as a preferred embodiment is the lamination with PVB (polyvinyl butyral) films. In this case, it is preferable that the layer or layers in contact with the PVB amounts to at most 10% of the amount of IR-absorbing metal oxides, based on the amount in% of metal oxide in the highest particulate layer , contain.

In addition to the transparent metal oxides, the film according to the invention may contain in one or more layers further particulate additives such as fillers and antiblocking agents. Typical fillers and antiblocking agents are inorganic and / or organic particles, for example silicon dioxide (natural, precipitated or pyrogenic), calcium carbonate, magnesium carbonate, barium carbonate, calcium aluminosilicate, barium sulfate, lithium phosphate, calcium phosphate, magnesium phosphate, titanium dioxide (rutile or anatase), kaolin ( hydrated or calcined), alumina, aluminum silicates, lithium fluoride, calcium, barium, zinc or manganese salts of the dicarboxylic acids or crosslinked polymer particles, eg Polystyrene or polymethyl methacrylate particles.

It is also possible to choose mixtures of two or more of the abovementioned particle systems or mixtures of particle systems having the same chemical composition but different particle size. The particles are added to the polyester advantageously before melting.

If further particulate additives are present in one layer of the film, the total concentration of these particles is generally less than 10% by weight, based on the total mass of the finished layer, preferably less than 5% by weight and more preferably less than 1% by weight. -%. The particulate additives have a mean size (d ₅₀ value) of 0.01 to 3.5 .mu.m, preferably 0.03 to 3.0 microns and more preferably 0.05 to 2.8 microns. In a preferred embodiment, the proportion of particles having a d ₅₀ value of ≥ 3 μm is <500 ppm, preferably at <300 ppm and more preferably at <100 ppm.

In a preferred embodiment, the film contains 0.1 to 2.0 wt .-% and preferably 0.15 to 1, 0 wt .-% silica particles having a d ₅₀ <1 micron and 0 to 500 ppm of silica particles with a d ₅₀ ≥ 1 μm and <3 μm. These particles are preferably added to one or both outer layers. The measurement of the average diameter d _so of these particles is carried out by conventional methods.

Since the films according to the invention can heat locally as a result of their IR absorption, they are subject to greater hydrolytic degradation than polyester films without transparent IR-absorbing metal oxides; it may be useful to additionally use a hydrolysis stabilizer. Suitable hydrolysis stabilizers are beispiels¬, polymeric carbodiimides such as Stabaxol ^® P from. Rhein Chemie / Germany. These are preferably used in an amount of 0.1 to 1, 0 wt .-%, based on the mass of the film.

In a further preferred embodiment, the transparent film contains at least one UV stabilizer as light stabilizer, which is expediently added by the so-called masterbatch technology directly in the film production, wherein the concentration of the UV stabilizer preferably between 0.01 and 5.0 wt. -%, based on the weight of the layer of crystallizable Thermo¬ plastic is.

Suitable UV stabilizers as light stabilizers are UV stabilizers which absorb at least 70%, preferably 80%, particularly preferably 90%, of the UV light in the wavelength range from 180 to 380 nm, preferably 280 to 350 nm. These are particularly suitable if they are thermally stable in the temperature range of 260 to 300 ⁰ C, ie do not decompose and do not lead to outgassing. Examples of suitable UV stabilizers as light stabilizers are 2-hydroxybenzophenones, 2-hydroxybenzotriazoles, organo-nickel compounds, salicylic acid esters, cinnamic acid ester derivatives, resorcinol monobenzoates, oxalic anilides, hydroxybenzoic acid esters, sterically hindered amines and triazines, where the 2-hydroxybenzotriazoles and the triazines are preferred.

In a particularly preferred embodiment, the transparent film contains 0.01 to 5.0% by weight of 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5- (hexyl) oxy-phenol or 0.01 to 5.0% by weight of 2,2'-methylenebis (6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol.

In a further preferred embodiment, it is also possible to use mixtures of these two UV stabilizers or mixtures of at least one of these two UV stabilizers with other UV stabilizers, the total concentration of light stabilizer generally being in the range from 0.01 to 5.0 Wt .-%, based on the weight of polymer. Particularly suitable light stabilizers from the company. Ciba have proven from the Tinuvin ^® series. In a preferred UV-stabilized embodiment, the transmission at 390 nm is below 70% and preferably below 60%. The transmission at 360 nm is less than 50% and preferably less than 25%.

It has also proven to be beneficial if the film contains an optical brightener in addition to the UV stabilizer. Especially suitable for this purpose is the product OB-One from Ciba. In a multilayer structure, it has also proven to be beneficial if the optical brightener is located in the layer of the film facing the light source.

Likewise, the film can be coated to adjust other properties. Typical coatings are in particular adhesion-promoting, antistatic, slip-improving or dehesive-acting layers. It is advisable to apply these additional layers via in-line coating by means of aqueous dispersions after the longitudinal and before the transverse extension of the film.

In a particular embodiment, the film has a silicone coating on at least one side, as described, for example, in US Pat. No. 5,728,339. This embodiment has the advantage that this film surface can be cleaned more easily, which is required, for example, when this layer of the film can be touched from the outside. Since the film is laminated in a preferred embodiment with a PVB film, it has proven to be expedient if the film is coated on one or both sides with an aqueous solution / dispersion of a hydrolyzed Aminosilanverbindung. The coating is preferably applied in-line, ie during the film production process, expediently before the transverse stretching. Particularly preferred is the application of the coating by means of the "reverse gravure roll coating" method, in which the coating can be applied extremely homogeneously. Likewise preferred is the application of the coating by the "Meyer-Rod" method, with which larger coating thicknesses can be achieved. The coating is applied to the film as a dilute aqueous solution / dispersion and then the solvent / dispersant is volatilized. If the coating is applied in-line before the transverse stretching, usually the temperature treatment in the transverse direction is sufficient to volatilize the solvent / dispersant and to dry the coating.

In the unhydrolysed state, aminosilane compounds which are suitable according to the invention have the general formula (R ¹ ) aSi (R ² ) b (R ³ ) c

in the R ^{1 is} a functional group having at least one primary amino group, R ^{2 is} a hydrolyzable group selected from the group consisting of a lower alkoxy group having 1 to 8 carbon atoms, an acetoxy group and a halide group, and R ^{3 is} an unreactive, not hydrolyzable group selected from the group consisting of a lower alkyl group having 1 to 8 carbon atoms and a phenyl group. The coefficient a is> 1, the coefficient b is also ≥ 1, the coefficient c is ≥ 0 and a + b + c = 4.

As the aminosilane compound is N- (2-aminoethyl) -3-aminopropyltrimethoxysilane of the formula

prefers. This compound is commercially available from Dow Corning / DE under the designation Z-6020.

The coating described above is described in detail in EP-B-0 359 017, to which reference is expressly made at this point (see in particular pages 3 to 5). This document also provides information about other suitable aminosilane compounds, their reproduction is omitted here, but are expressly included by the invention.

It has been found that a film containing the dried residue of a hydrolyzed aminosilane compound in an amount of 0.5 to 100 mg / m ² , preferably 2 to 50 mg / m ² and particularly preferably 10 to 25 mg / m ² , coated, already shows a significantly improved adhesion of PET film to PVB.

Any additives, such as the optional further fillers and other additives, can be incorporated into the polymer by means of a commercially available twin-screw extruder (e.g., Coperion), except for the transparent IR-active metal oxides whose incorporation has already been described above. In this case, an inventive polyester granules is introduced together with the particles / additives in the extruder and extruded, then quenched in a water bath and then granulated.

However, in a preferred process for preparing the thermoplastic resins of the present invention, the additives are added directly to the polymer preparation. Usually, in the case of the DMT process, the additives are added after the transesterification or directly before the polycondensation, for example via the transport line between transesterification and polycondensation boilers, as a glycolic dispersion. The addition can also be done before the transesterification. In the case of the TPA process, the addition is preferably carried out at the beginning of the polycondensation. However, a later addition is also possible. It has proven advantageous in this method, the glycolic dispersions are filtered prior to the addition of a PROGAF PGF ^® 57 (Hayward Ind./US) filter. The present invention also provides a process for producing the film. In general, the production takes place by an extrusion process, for example on an extrusion line. It has proven particularly advantageous to add the additives in the form of predried or precrystallized masterbatches prior to extrusion.

Preferred in the case of masterbatch technology is that the particle size and the bulk density of the masterbatches are similar to the particle size and the bulk density of the polymer raw material used, so that a homogeneous distribution is obtained from which homogeneous properties result.

The films can be prepared by known methods from a polymer raw material and optionally further raw materials, at least one raw material (masterbatch) with transparent IR-active metal oxide, and optionally further additives as single or multilayer films.

The raw materials are preferably pre-dried. The predrying involves a gradual heating of the masterbatches under reduced pressure (20 to 80 mbar, preferably 30 to 60 mbar, particularly preferably 40 to 50 mbar) and stirring and, if appropriate, subsequent drying at a constant, elevated temperature (also under reduced pressure). The masterbatches are preferably at room temperature from a dosing in the desired mixture together with the Polymerroh¬ material and optionally other raw material components batchwise in a vacuum dryer, in the course of the drying or residence a temperature range of 10 to 160 ⁰ C, preferably 20 to 150 ^0th C, particularly preferably 30 to 130 ⁰ C passes through, filled. During about 6 hours, preferably 5 hours, more preferably 4 hours, residence time, the raw material mixture with 10 to 70 rpm, preferably 15 to 65 rpm, particularly preferably 20 to 60 rpm, stirred. The thus precrystallized or predried raw material mixture is in a downstream, also evacuated container at 90 to 180 ⁰ C, preferably 100 to 170 ⁰ C, more preferably 110 to 160 ⁰ C, for 2 to 8 hours, preferably 3 to 7 hours, particularly preferred 4 to 6 hours, after-dried. However, the masterbatches and the other raw materials can also be extruded directly without using pre-drying when using twin-screw and multi-screw extruders.

In the preferred extrusion or coextrusion process for producing the film, the procedure is such that the melts corresponding to the individual layers of the film are extruded or coextruded through a flat die and quenched on a chill roll as a largely amorphous prefilm. In the monolayer film according to the invention, only one melt is extruded through the die. It has proved to be advantageous if the polymer melt (s) are / are filtered prior to entering the nozzle via melt filter with a pore size for which the manufacturers a retention of at least 50% for 7 .mu.m particles and preferably at least 50% for 5 microns Indicates particle. Both commercially available sintered filter materials and fleece filters are suitable.

This film is subsequently heated again and stretched ("oriented") in the longitudinal and transverse direction or in the transverse and longitudinal direction or in the longitudinal, transverse and even longitudinal direction and / or transverse direction 60 ⁰ C above the glass transition temperature T _{g of} the polyester used, the draw ratio of the longitudinal stretching is usually from 2.0 to 6.0, in particular 3.0 to 4.5, that of the transverse extension at 2.0 to 5.0, in particular at 3.0 to 4.5, and that of the optionally performed second longitudinal and transverse extension at 1, 1 to 5.0 The first longitudinal stretching can also be carried out simultaneously with the transverse extension (simultaneous stretching) Film at oven temperatures of 180 to 260 ⁰ C, in particular from 220 to 250 ⁰ C. Subsequently, the film is cooled and wound.

In a preferred embodiment, the heat-setting takes place between 220 and 250 ^° C. and the film is relaxed at this temperature by at least 1%, preferably at least 2% and particularly preferably at least 4%, in the transverse direction. In a further preferred embodiment, the heat-setting takes place between 220 and 250 ^° C. and the film is relaxed at this temperature by at least 1%, preferably at least 2%, in the transverse direction and then again at temperatures between 180 and 150 ^° C. in the cooling phase again at least 1%, preferably at least 2%, relaxed in the transverse direction.

In a further preferred embodiment, the film is stretched at least by a factor of 3 in the MD and TD directions, the stretching taking place in a simultaneous frame. The heat-setting takes place between 220 and 250 ^° C. and the film is relaxed at this temperature by at least 2.0% in the transverse direction and preferably also by 0.5 to 5.0% in the longitudinal direction.

In particular, when using IR radiators for heating the film before and during the spreading and heat setting, it may come to overheating of the film by the IR absorption of the metal oxides used. This manifests itself mostly in a sagging or strong fluttering of the film web, with the result of breaks. In these cases, the intensity of the radiator or the temperature of the respective zones in the stretching or fixing frame must be reduced to the extent that the film is stretched again in the frame.

Particular care should also be taken to ensure that the differential speeds of successive rolls outside of the drawing areas are chosen as small as possible, so that sliding of the film over the roll and the formation of scratches are avoided

The monolayer or multilayer films according to the invention have the required good mechanical properties. Thus, the modulus of elasticity in at least one film direction (longitudinal direction (MD) and / or transverse direction (TD)) is at least 500 N / mm ² , preferably at least 2000 N / mm ² and particularly preferably at least 4000 N / mm ² .

In a preferred application, the film, which preferably already has an in-line applied aminosilane coating as described above, is provided on this side again off-line with aminosilane coating and on this page with PVB laminated. The other side is provided with a hardcoat known from the literature and the PVB side is laminated against glass. The individual steps for producing such a composite are described, for example, in EPA-0319911.

In a further preferred application, the film is coated on one side with an industrially customary adhesive having adhesion to glass, generally based on silane coupling agents. On the adhesive coating a siliconized polyester film is applied as a "release liner". The other side of the film is preferably provided with a hardcoat known from the literature, but may also be uncoated or have a different type of coating or be laminated with further layers of film.

Use the film according to the invention as insulation material, e.g. in window applications and as a shielding of electrical components of all kinds.

The measurement of the individual properties of the films is carried out according to the following standards or procedures.

measurement methods

Mechanical properties The modulus of elasticity, ultimate tensile strength, elongation at break and _F5 value are measured in the longitudinal and transverse directions according to ISO 527-1-2 with the aid of a tensile-strain gauge (Zwick, type 010, Ulm / DE).

Transmission The transmission is measured using a ^Lambda® 9 spectrometer from Perkin Elmer / US. The measurement is carried out in transmitted light and it is measured from 2500 to 320 nm at a speed of 120 nm per minute.

Shrinking Derthermal shrinkage was determined on square film samples with an edge length of 10 cm. The samples are measured accurately before the test (edge analysis). length L ₀ ) and 15 minutes at 150 ⁰ C in a convection oven. The samples are taken and also exactly measured at room temperature (edge length L). The shrinkage results from the equation

Shrink [%] = 100 * (L ₀ - L) / L ₀

Production, shape and number of samples From the film to be examined, 5 samples (for measurements in the MD and TD directions) with a size of 100 x 100 mm are cut out. The longitudinal and transverse directions are marked on the edge, since the measurements are made in both machine directions.

Measurement of Haze The measurement is carried out 211 XL-Fa on the Hazegard hazemeter ^®. BYK Gardner (see Figure 1). The meter should be turned on 30 minutes before the measurement. It is important to ensure that the light beam passes through the ball centric to the outlet opening.

Measurement of turbidity (see Figure 1) Press switch 1 "OPEN" Set switch 2 to "X10" and use the "Zero" button to calibrate the digital display to 0.00 Switching switch 1 to "Reference" and switch 2 to "X1" With press the "Calibrate" button to bring the digital display to 100. Load sample lengthwise Read the display value for transparency Calibrate the digital display to 100 using the "Calibrate" button Set switch 1 to "OPEN" Read the haze reading in the longitudinal direction Turn the sample in the transverse direction Read the haze reading in the transverse direction

Evaluation The turbidity is obtained by averaging the respective 5 individual values (longitudinal and transverse).

Film Production Polyester chips were mixed according to the ratios given in the examples and melted without predrying in each case in an extruder, in monofilm in a single-screw extruder and in coextruded film in twin-screw extruders in each case. The / melted / n polymer strand / strands / n was extruded through a die (co-extrusion was carried out at the merger of the polymer strands into a coextrusion die) and a take-off roll (roll temperature 20 ⁰ C) subtracted. The film was stretched by a factor of 3.5 in the machine direction at 116 ^° C. (film temperature in the drawing gap) and, in a frame at 110 ^° C., a transverse extension of a factor of 3.6. Subsequently, the film was heat set at 236 ⁰ C and relaxed in the transverse direction by 3.0% at temperatures of 236-200 ⁰ C and a second time to 1, 0% at temperatures from 180 to 150 ⁰ C. The production speed (final film speed) is 250 m / min.

Examples The following raw materials are used in the examples.

R1 masterbatch with 4% by weight ITO (Nano-ITO from Nanogate / Saarbrücken) in PET Preparation: Ethylene glycol and dimethyl terephthalate were transesterified with 40 ppm manganese acetate as transesterification catalyst. After completion of the transesterification was heated to 240 ⁰ C and after reaching the temperature of phosphorous acid (15 ppm phosphorus) added as a stabilizer. Thereafter, the reaction Mixture pumped into the polycondensation boiler. The polycondensation catalyst used was 15 ppm of Titanium titanium catalyst C94 from Acordis. A dispersion of 20% nano-ITO in glycol (primary particle size 10 to 20 nm, 95 In ₂ O ₃ + 5 SnO ₂ ) from Nanogate was introduced into the polycondensation vessel 15 minutes after pumping the transesterification mixture. The vacuum was broken by adding dry nitrogen and then re-evacuated.

R2 Masterbatch with 2% by weight ITO (Nano-ITO from Nanogate / Saarbrücken) and 2% ATO (Advanced Nano Products Co., Ltd. / KR) in PET Preparation: Ethylene glycol and dimethyl terephthalate were reacted with 40 ppm manganese acetate as the transesterification catalyst esterified. After completion of the transesterification is heated to 240 ⁰ C and after reaching the temperature of phosphorous acid (15 ppm phosphorus) was added as a stabilizer. A dispersion of 20 wt .-% nano-ITO in glycol (primary particle size 10 to 20 nm, 95 In ₂ O ₃ + 5 SnO ₂ ) from. Nanogate and a dispersion of 20 wt .-% ATO in glycol (80% of Particles smaller than 100 nm) was introduced into the polycondensation vessel directly after pumping the transesterification mixture. As the polycondensation catalyst, 10 ppm of titanium of titanium catalyst C94 was used.

R3 masterbatch with 3% by weight of ITO (Nano-ITO from Nanogate / Saarbrücken) in PEN Preparation: Ethylene glycol and dimethylnaphthalate were transesterified with 30 ppm of manganese acetate as transesterification catalyst. After completion of the transesterification was - heated to 240 ⁰ C and after reaching the temperature of phosphorous acid (11 ppm phosphorus) added as a stabilizer. Thereafter, the Reaktions¬ mixture was pumped into the polycondensation boiler. As Polykondensationskata¬ lysator 15 ppm of titanium titanium catalyst C94 were used. A dispersion of 20% nano-ITO in glycol (primary particle size 10 to 20 nm, 95 In ₂ O ₃ + 5 SnO ₂ ) from Nanogate was introduced into the polycondensation vessel directly after pumping the transesterification mixture. R4 masterbatch with 4% by weight ITO (Nano-ITO from Nanogate / Saarbrücken) in PET Preparation: Ethylene glycol and dimethyl terephthalate were transesterified with 40 ppm manganese acetate as transesterification catalyst. After completion of the transesterification is heated to 240 ⁰ C and after reaching the temperature of phosphorous acid (15 ppm phosphorus) is added as a stabilizer. A dispersion of 20% by weight of nano-ITO in glycol (primary particle size 10 to 20 nm, 95 in ₂ O ₃ + 5 SnO ₂ ) from Nanogate was introduced into the polycondensation vessel directly after pumping the transesterification mixture. As the polycondensation catalyst, 10 ppm titanium of titanium catalyst C94 was used.

R5 MB4 contains 20% by weight of the UV stabilizer 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5- (hexyl) oxyphenol (Tinuvin 1577) (Ciba Geigy / CH ). Preparation: The UV stabilizer was after polyester production to a polyester (catalyst / stabilizer system are 20 ppm Ti from titanium catalyst C94, 50 ppm Mn from Mn (Ac) ₂ and 20 ppm P from phosphoric acid) added in a twin-screw extruder.

R6 hydrolysis stabilizer Masterbatch P100 from Rheinchemie / DE

R7 100% by weight of polyethylene terephthalate RT49 from Kosa / DE

R8 100% by weight of polyethylene naphthalate P100 from Kosa / DE

Examples Monofilms and three-layer films were produced as described above. The raw material composition and properties of the films can be taken from the table. table

<jθ

n / A. = not applicable VB = Comparative Example

Claims

claims

1. single or multi-layered, at least uniaxially stretched thermoplastic polymer film having a thickness of 3 to 500 microns, characterized in that it contains 0.1 to 25.0 wt .-% of particles of at least one transparent metal oxide - based on the film - and these particles have an average particle size d ₅₀ of <350 nm.

2. A film according to claim 1, characterized in that it preferably contains 0.5 to 10.0 wt .-% and particularly preferably 1, 0 to 4.0 wt .-% transparent metal oxide particles.

3. A film according to claim 1 or 2, characterized in that the transparent metal oxide particles preferably have an average particle size d ₅₀ in the range of ≥ 7.0 to ≤ 150 nm.

4. A film according to one or more of claims 1 to 3, characterized gekenn¬ characterized in that it has a thickness of preferably 8 to 100 microns and more preferably 12 to 50 microns.

5. The film as claimed in one or more of claims 1 to 4, characterized in that the proportion of the transparent metal oxide (in percent by weight), as a function of the film thickness, follows the equation G% = x * Fd ⁽ - ° ' ⁹⁸⁸²⁾ , where G % = Proportion of transparent metal oxide in weight percent and Fd = film thickness in μm, where x (in% by weight / μm) is in the range of> 10 to <250 and preferably of ≥ 40 to <100.

6. The film as claimed in one or more of claims 1 to 5, characterized in that the film has a transmission of at least 65% at 650 nm and of <80% at 2000 nm.

7. A film according to one or more of claims 1 to 6, characterized gekenn¬ characterized in that are used as transparent, nanoparticulate metal oxides antimony tin oxide (ATO), indium tin oxide (ITO) and other transparent metal oxides alone or in mixtures, but preferably ITO and ATO.

8. The film according to one or more of claims 1 to 7, characterized gekenn¬ characterized in that the film at 150 ⁰ C in any direction of the film has a shrinkage of about 2.5% and preferably in each film direction is less than 1, 5%.

9. A film according to one or more of claims 1 to 8, characterized gekenn¬ characterized in that the thermoplastic polymer is a homopolyester, copolyester or blends of different polyesters.

10. The film as claimed in one or more of claims 1 to 9, characterized in that the multilayer films consist of a base layer B, at least one cover layer A or C and optionally further intermediate layers, a three-layered ABA or ABC structure being preferred ,

11. The film as claimed in one or more of claims 1 to 10, characterized in that the thickness of the cover layer (s) is in the range from 0.1 to 10.0 μm, preferably 0.2 to 5.0 μm and particularly preferably 1 , 0 to 3.0 microns.

12. The film according to one or more of claims 1 to 11, characterized gekenn¬ characterized in that the film contains further particulate additives in the form of fillers and antiblocking agents, and at least one UV stabilizer.

13. A film according to one or more of claims 1 to 12, characterized gekenn¬ characterized in that the film is coated.

14. A film according to one or more of claims 1 to 13, characterized gekenn¬ characterized in that the film contains recyclate.

15. A process for producing a film according to claims 1 to 14, characterized in that in an extrusion or coextrusion process, the respective layers of the film corresponding melts are extruded through a flat die or coextruded and quenched as a largely amorphous prefilm on a chill roll , the film is then reheated and stretched in the longitudinal and transverse direction or in the transverse and longitudinal direction or in the longitudinal, in transverse and again in the longitudinal direction and / or transverse direction ("oriented") and then at temperatures of 180 to 260 ⁰ C heat-set, cooled and wound up.

16. Use of the film according to claims 1 to 14 as insulation material in window applications and as a shielding of electrical components of all kinds.