DE19945559A1 - White, biaxially-oriented film for interior or exterior use, e.g. signs, displays, glazing, roofing and lighting, comprises crystallizable thermoplastic, e.g. polyethylene terephthalate, containing UV stabilizer and white pigment - Google Patents

Abstract

White, biaxially-oriented film with a thickness of 1-500 microns and with a crystallizable thermoplastic as main component also contains UV stabilizer(S) and white pigment(s). An Independent claim is also included for a process for the production of this white film by melt-compounding the crystallizable thermoplastic in an extruder with UV stabilizer(s) (UVS) and white pigment(s) (WP), extruding onto a cooling roller, biaxially orienting, fixing and rolling up.

Description

The invention relates to a white, UV-stabilized film made of a crystallizable Thermoplastic, the thickness of which ranges from 1 to 500 µm. The slide contains at least one pigment and a UV stabilizer as a light stabilizer and draws good stretchability, very good optical and mechanical Properties. The invention further relates to a method for producing this Foil and its use.

White films with a thickness between 1 and 500 microns are well known.

These films contain no UV stabilizers as light stabilizers, so that neither the foils nor the articles made from them are suitable for outdoor use. In outdoor applications, these films show yellowing after a short time and a deterioration in mechanical properties due to a photo oxidative degradation by sunlight.

In EP-A-0 620 245 foils are described with regard to their thermal Stability are improved. These films contain antioxidants which are suitable are to trap radicals formed in the film and to break down the peroxide formed. This document suggests how the UV stability of such films should be improved however not to be inferred.

WO 98/06575 describes a matt, sealable film which at least contains a UV absorber. The UV absorber has the task here, the mechanical Properties of the film do not deteriorate dramatically after weathering. The Sealability is achieved by coextruding the film with a copolyester is. The non-sealable side must be rough and therefore low-gloss and matt be so that the film can be wound and processed, because such copolyesters characterized by strong gluing with the non-sealable side. Through the  high roughness and dosing of pigments reduces the tendency to stick. On The font suggests how a low yellowness index (<55) can be set not to be removed.

The object of the present invention was to provide a white film with a thickness of 1 to Provide 500 microns, in addition to good stretchability, good mechanical as well as optical properties, a low yellow number, especially a high UV Has stability and offers high light protection.

High UV stability means that the films are exposed to sunlight or other UV Radiation are not damaged or only extremely little, so that the foils are suitable for Outdoor applications and / or critical indoor applications are suitable. In particular the films should not yellow when used for several years, no embrittlement or surface cracking and no deterioration of the surface have mechanical properties. High UV stability means that the film absorbs UV light and only lets light through in the visible range.

The good optical properties include, for example, a homogeneous, streak-free coloring, low light transmission (≦ 80%), an acceptable one Surface gloss, as well as almost unchanged compared to the unstabilized film changed yellow number.

The good mechanical properties include a high modulus of elasticity (E _MD <3300 N / mm ² ; E _TD <4800 N / mm ² ) and good tensile strength values (in MD <130 N / mm ² ; in TD <180 N) / mm ² ) and good elongation at break values in the longitudinal and transverse directions (in MD <120%; in TD <70%).

Good stretchability means that the film can be produced both in Can be oriented longitudinally as well as transversely and without tears.  

In addition, the film according to the invention should be recyclable, in particular without Loss of optical and mechanical properties, and possibly flame-retardant, so that they can also be used, for example, in indoor applications Exhibition stand construction can be used.

This task is solved by a white film with a thickness in the range of 1 to 500 µm, which contains a crystallizable thermoplastic as the main component, the is characterized in that the film at least one white pigment and at least one UV stabilizer as a light stabilizer and possibly an optical one Contains brighteners, the UV stabilizer and / or the white pigment and / or the optical brighteners can be metered in directly as masterbatch in film production.

The main component of the white film is a crystallizable thermoplastic. Suitable crystallizable or partially crystalline thermoplastics are, for example Polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, wherein Polyethylene terephthalate is preferred.

According to the invention, crystallizable thermoplastics are understood

• Crystallizable homopolymers,
• - crystallizable copolymers,
• - crystallizable compounds,
• - Crystallizable recyclate and
• - other variations of crystallizable thermoplastics.

The white film can be either single-layer or multi-layer. The white slide can also be coated with various copolyesters or adhesion promoters.

The white film contains at least one UV stabilizer as a light stabilizer expediently via the so-called masterbatch technology directly at the Film production is metered in, the concentration of the UV stabilizer  Film production is metered in, the concentration of the UV stabilizer preferably between 0.01 wt .-% and 5 wt .-%, based on the weight of the crystallizable thermoplastics.

The white film also contains at least one pigment for white coloring, wherein the concentration of the pigment is preferably between 0.3% by weight and 25% by weight, based on the weight of the crystallizable thermoplastic. Preferably also the white pigment via the so-called masterbatch technology directly at the Film production metered.

Light, especially the ultraviolet portion of solar radiation, i.e. H. the wave length range from 280 to 400 nm, initiates degradation processes as thermoplastics Do not just follow the visual appearance due to color change or Yellowing changes, but also the mechanical-physical properties negative to be influenced.

The inhibition of these photooxidative degradation processes is of considerable technical and economic importance, since otherwise the application possibilities of numerous thermoplastics are drastically restricted.

Polyethylene terephthalates, for example, start below 360 nm UV To absorb light, their absorption increases considerably below 320 nm and is very pronounced below 300 nm. The maximum absorption is between 280 and 300 nm.

In the presence of oxygen there are mainly chain cleavages, but none Networking observed. Carbon monoxide, carbon dioxide and carboxylic acids are the quantitatively predominant photo-oxidation products. In addition to the direct Photolysis of the ester groups still need to consider oxidation reactions  that also lead to the formation of carbon dioxide via peroxide radicals to have.

The photooxidation of polyethylene terephthalates can also be carried out using hydrogen cleavage in the α-position of the ester groups to hydroperoxides and their decomposition products as well as the associated chain splits (H. Day, D. M. Wiles: J. Appl. Polym. Sci 16, 1972, page 203).

UV stabilizers or UV absorbers as light stabilizers are chemical compounds gene in the physical and chemical processes of light-induced degradation can intervene. Soot and other pigments can partially protect against light cause. However, these substances are unsuitable for white foils because they are used for Discoloration or color change. For white foils are only organic and organometallic compounds suitable to the thermoplastic to be stabilized no or only an extremely slight color or color change. Suitable UV Stabilizers as light stabilizers are UV stabilizers that contain at least 70%, preferably 80%, particularly preferably 90%, of UV light in the wavelength range absorb from 180 nm to 380 nm, preferably 280 to 350 nm. These are Particularly suitable if they are thermal in the temperature range from 260 to 300 ° C are stable, d. H. do not decompose and do not lead to outgassing. Suitable UV Stabilizers as light stabilizers are, for example, 2-hydroxybenzophenones, 2- Hydroxybenzotriazoles, nickel-organic compounds, salicylic acid esters, Cinnamic acid ester derivatives, resorcinol monobenzoates, oxalic acid anilides, hydroxybenzoe acid esters, sterically hindered amines and triazines, the 2-hydroxybenzotriazoles and the triazines are preferred.

As a further component according to the invention, the film may contain an optical one Brightener. The optical brighteners according to the invention are capable of UV rays absorb in the wavelength range from approx. 360 to 380 nm and as a longer-wave, emit visible blue-violet light again. Suitable optical brighteners are  Bis-benzoxazoles, phenylcoumarins and bis-sterylbiphenyls, especially phenyl cumann, particularly preferably triazine-phenylcumann (Tinopal®, Ciba-Geigy, Basel, Switzerland).

If appropriate, in addition to the optical brightener can also in polyester soluble blue dyes can be added. Blue dyes have been found to be suitable Cobalt blue, ultramarine blue and anthraquinone dyes, especially Sudan blue 2 (BASF, Ludwigshafen, Federal Republic of Germany).

The optical brighteners are used in amounts of 10 ppm to 50,000 ppm, in particular 20 ppm to 30,000 ppm, particularly preferably 50 ppm to 25,000 ppm (based on the weight of the layer to be equipped).

The blue dyes are used in amounts of 10 ppm to 10,000 ppm, in particular 20 ppm to 5,000 ppm, particularly preferably 50 ppm to 1,000 ppm (based on the Weight of the layer to be equipped).

Suitable white pigments are preferably titanium dioxide, barium sulfate, calcium carbonate, kaolin, silicon dioxide, with titanium dioxide and barium sulfate being preferred.

The titanium dioxide particles can consist of anatase or rutile, preferably predominantly made of rutile, which shows a higher opacity compared to anatas. In In a preferred embodiment, the titanium dioxide particles consist of at least 95% by weight. % from rutile. You can by a conventional procedure, e.g. B. after the chloride or the sulfate process. Their amount in the base layer is expediently 0.3-25% by weight, based on the base layer. The middle Particle size is relatively small and is preferably in the range from 0.10 to 0.30 µm.

Titanium dioxide of the type described does not produce any within the polymer matrix Vacuoles during film production.  

The titanium dioxide particles can have a coating of inorganic oxides, as is usually used as a coating for TiO ₂ white pigment in papers or paints to improve the light fastness.

As is well known, TiO ₂ is photoactive. When exposed to UV rays, free radicals form on the surface of the particles. These free radicals can migrate into the polymer matrix, which leads to degradation reactions and yellowing. To avoid this, the TiO ₂ particles can be coated oxidically. The particularly suitable oxides for the coating include the oxides of aluminum, silicon, zinc or magnesium or mixtures of two or more of these compounds. TiO ₂ particles with a coating of several of these compounds are e.g. B. in EP-A-0 044 515 and EP-A-0 078 633. Furthermore, the coating can contain organic compounds with polar and non-polar groups. The organic compounds must be sufficiently thermostable in the production of the film by extrusion of the polymer melt. Polar groups are for example -OH; - OR; -COOX; (X = R; H or Na, R = alkyl with 1-34 C atoms). Preferred organic compounds are alkanols and fatty acids with 8-30 C atoms in the alkyl group, in particular fatty acids and primary n-alkanols with 12-24 C atoms, and polydiorganosiloxanes and / or polyorganohydrogensiloxanes such as, for. B. Polydi methylsiloxane and polymethylhydrogensiloxane.

The coating for the titanium dioxide particles usually consists of 1 to 12, in particular 2 to 6 g of inorganic oxides and / or 0.5 to 3, in particular 0.7 to 1.5 g organic compound, based on 100 g of titanium dioxide particles. The cover will usually applied to the particles in aqueous suspension. The inorganic Oxides can be made from water-soluble compounds, e.g. B. alkali, in particular Sodium nitrate, sodium silicate (water glass) or silica in the aqueous suspension be canceled.  

Among inorganic oxides such as Al ₂ O ₃ or SiO ₂ , the hydroxides or their various dewatering stages such as. B. understand oxide hydrate without knowing its exact composition and structure. On the TiO ₂ pigment after the annealing and grinding in aqueous suspension, the oxide hydrates such. B. of aluminum and / or silicon, the pigments are then washed and dried. This precipitation can thus take place directly in a suspension, as occurs in the manufacturing process after the annealing and the subsequent wet grinding. The oxides and / or oxide hydrates of the respective metals are precipitated from the water-soluble metal salts in the known pH range, for the aluminum, for example, aluminum sulfate in aqueous solution (pH less than 4) is used and in the pH range between by adding aqueous ammonia solution or sodium hydroxide solution 5 and 9, preferably between 7 and 8.5, the oxide hydrate precipitates. If you start with a water glass or alkali aluminate solution, the pH of the TiO ₂ suspension should be in the strongly alkaline range (pH greater than 8). The precipitation then takes place by adding mineral acid such as sulfuric acid in the pH range 5 to 8. After the precipitation of the metal oxides, the suspension is stirred for a further 15 minutes to about 2 hours, the precipitated layers undergoing aging. The coated product is separated from the aqueous dispersion and, after washing, is dried at elevated temperature, in particular at 70 to 100.degree.

It was completely surprising that the use of the above UV stabilizers and if necessary, brighteners in foils led to the desired result. The specialist would have probably first tried to achieve some UV stability through an antioxidant reach, but would have found after weathering that the film quickly turns yellow.

In view of the fact that UV stabilizers which absorb the UV light and thus offer protection, the person skilled in the art would have used commercially available UV stabilizers. He would have noticed that

• - The UV stabilizer has a lack of thermal stability and at Temperatures decomposed or outgassed between 200 ° C and 240 ° C;  
• - He has to incorporate large amounts (approx. 10 to 15% by weight) of UV stabilizer so that the UV light is absorbed and therefore the film is not damaged.

At these high concentrations, he would have found that the film was yellow as soon as it was manufactured, and the yellowness index difference (YID) would be around 25. Furthermore, he would have found that the mechanical properties were adversely affected. He would have had unusual problems with stretching like

• - Demolition due to lack of strength, d. H. E-module
• - Nozzle deposits, which leads to profile fluctuations
• - Roller deposits from the UV stabilizer, which affects the optical properties (adhesive defect, inhomogeneous surface)
• - Deposits in stretching and fixing frames that drip onto the film.

It was therefore more than surprising that even low concentrations of the UV stabilizer according to the invention, if appropriate in combination with the optical brightener and the blue dye, provided excellent UV protection. It was very surprising that this excellent UV protection

• - The yellowness index of the film compared to a non-stabilized film in the frame the measuring accuracy does not change;
• - no outgassing, no nozzle deposits, no frame evaporation set, which gives the film an excellent appearance and an excellent has a nice profile and an excellent plantation .;
• - The UV-stabilized film is characterized by excellent stretchability net, so that they are reliable and stable on high speed film lines up to Speeds of 420 m / min can be produced reliably. This means that the film is also economically viable.

Furthermore, it is very surprising that the regrind can also be used again, without negatively affecting the yellowness index of the film.  

In a particularly preferred embodiment, the white film according to the invention contains, as the main constituent, a crystallizable polyethylene terephthalate and 0.01% by weight to 5.0% by weight of 2- (4,6-diphenyl-1,3,5-triazine-2 -yl) -5- (hexyl) oxy-phenol (structure in Fig. 1a) or 0.01% to 5.0% by weight of 2,2'-methylene-bis (6- (2H-benzotriazole -2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol (structure in FIG. 1b) and 0.3% by weight to 25% by weight of titanium dioxide, advantageously with a particle diameter of 0 , 10 to 0.50 µm, with a rutile-type titanium dioxide being preferred. Instead of titanium dioxide, barium sulfate, preferably with a particle diameter of 0.20 to 1.20 µm, can also be used as the white pigment, the concentration usually being between 1.0 In a preferred embodiment, mixtures of these white pigments or a mixture of one of these white pigments with another can also be used In the embodiment, mixtures of the UV stabilizers mentioned or mixtures of at least one of the preferred UV stabilizers with other UV stabilizers can be used, the total concentration of light stabilizers preferably being between 0.01% by weight and 5.0% by weight, based on the weight of crystallizable polyethylene terephthalate.

The surface gloss, measured according to DIN 67530 (measuring angle 20 °) is greater than 15, preferably greater than 20.

The light transmission (transparency), measured according to ASTM-D 1003, is less than 80%, preferably less than 70%. The coloring is homogeneous and streak-free the barrel length and the film width.

The modulus of elasticity (ISO 527-1-2-) in the longitudinal direction is greater than 3300 N / mm ² , preferably greater than 3600 N / mm ² . The modulus of elasticity (ISO 527-1-2) in the transverse direction is greater than 4800 N / mm ² , preferably greater than 5100 N / mm ²

The standard viscosity SV (DCE) of the polyethylene terephthalate, measured in Dichloroacetic acid according to DIN 53728, is between 600 and 1000, preferably between 700 and 900.

The intrinsic viscosity IV (DCE) is calculated from the standard viscosity SV (DCE) as follows:

IV (DCE) = 6.67. 10 ^-4 SV (DCE) + 0.118

The white polyethylene terephthalate film, which has at least one white pigment and one UV Contains stabilizer and possibly an optical brightener, can be both single-layered also be multi-layered.

In the multilayer embodiment, the film is composed of at least one core layer and built up at least one top layer, in particular a three-layer A-B-A or A-B-C structure is preferred.

For this embodiment it is essential that the polyethylene terephthalate Core layer has a similar standard viscosity as the polyethylene terephthalate the top layer (s) that are adjacent to the core layer.

In a special embodiment, the cover layers can also consist of one Polyethylene naphthalate homopolymers or from a polyethylene terephthalate Polyethylene naphthalate copolymers or a compound exist.

In this embodiment, the thermoplastics of the cover layers also have one Standard viscosity similar to the polyethylene terephthalate of the core layer.

In the multilayer embodiment, the white pigment is preferably in the Core layer included. If necessary, the top layers can also be coated with white pigment be equipped.  

In the multilayer embodiment, the UV stabilizer and optionally the optical one Brightener and possibly the blue dye, preferably in the outer layer or layers contain. However, the core layer with UV stabilizers and if necessary, be equipped with an optical brightener and possibly blue dye.

In contrast to the single-layer embodiment, the concentration relates here of the stabilizer or stabilizers (brightener / blue dye) on the weight of the Thermopla Most in the layer equipped with UV stabilizer (s) (brightener / blue dye).

The film can also be coated on at least one side with a scratch-resistant coating Copolyester or be provided with an adhesion promoter.

Surprisingly, weathering tests according to the test specification ISO 4892 have with the Atlas C165 Weather Ometer demonstrated that in the case of a three layer film it is quite sufficient to cover the 0.5 µm to 2 µm thick top layers with UV Stabilizers, if necessary in combination with an optical brightener and blue dye equip.

As a result, the UV produced with the known coextrusion technology stabilized, multilayer films compared to the completely UV stabilized Monofilms economically interesting because there is significantly less UV stabilizer to achieve comparable UV stability is required.

Weathering tests have shown that the UV-stabilized films according to the invention even after 5 to 7 years (extrapolated from weathering tests) outside application generally no increased yellowing, no embrittlement, none Loss of gloss on the surface, no cracking on the surface and no ver have deterioration in mechanical properties.  

During the production of the film it was found that the UV-stabilized film excellent orientation in the longitudinal and transverse directions without tears. Furthermore there were no outgassings of the UV stabilizer and / or possibly the optical one Whitener and / or the blue dye found in the production process what is essential to the invention, since most UV stabilizers at extrusion temperatures Show annoying and unpleasant outgassing over 260 ° C and are therefore unsuitable.

In addition, measurements showed that the PET film of the invention from one Thickness of 300 microns is flame-retardant and flame-retardant, so that it is suitable for indoor applications and trade fair construction, for example. More surprising already fulfill foils according to the invention in the thickness range from 350 to 500 μm building material class B2. Surprisingly, 350 to 500 µm thick films also meet the fire class S4 according to DIN 5510, smoke development SR2, dripability ST1.

Furthermore, the film according to the invention is without environmental pollution and without loss the mechanical properties can be easily recycled, making them exemplary wise for use as short-lived advertising signs or other promotional items is suitable.

The production of the white, UV-stabilized film according to the invention can for example by an extrusion process in an extrusion line.

According to the invention, the white pigment, the light stabilizer, and optionally the optical one Brightener and possibly the blue dye already at the thermoplastic raw material manufacturer be metered in or metered into the extruder during film production.

It is particularly preferred to add the light stabilizer, the white pigment, if appropriate the optical brightener and / or possibly the blue dye via the masterbatch technology. The above-mentioned light protection active components or the white pig ment are fully dispersed in a solid carrier material. As carrier materials  come the thermoplastic itself, such as. B. the polyethylene terephthalate or other polymers that are sufficiently compatible with the thermoplastic, in question.

It is important that the grain size and bulk density of the masterbatch are similar to that Grain size and the bulk density of the thermoplastic is, so that a homogeneous Distribution and thus a homogeneous UV stabilization and a homogeneous whiteness is achieved.

The polyester films can be made from a polyester raw material by known methods possibly other raw materials as well as the UV stabilizer, the white pigment, possibly the optical brightener, possibly the blue dye and / or other usual Additives in the usual amount of 0.1 to a maximum of 10% by weight both as monofilms and also as multilayer, possibly coextruded films with the same or different trained surfaces are produced, one surface for example pigmented / UV-stable and the other surface is no pigment and / or Contains UV stabilizer. Likewise, one or both surfaces of the film can follow known methods can be provided with a conventional functional coating.

In the preferred extrusion process for producing the polyester film, the melted polyester material is extruded through a slot die and quenched as a largely amorphous pre-film on a cooling roll. This film is then heated again and stretched in the longitudinal and transverse directions or in the transverse and in the longitudinal direction or in the longitudinal, in the transverse and again in the longitudinal direction and / or transverse direction. The stretching temperatures are generally T _g + 10 ° C to T _g + 60 ° C (T _g = glass temperature), the stretching ratio of the longitudinal stretching is usually 2 to 6, in particular 3 to 4.5, that of the transverse stretching is 2 to 5, in particular in the case of 3 to 4.5, and that of the second longitudinal stretching which may be carried out at 1.1 to 3. The first longitudinal stretching can, if appropriate, be carried out simultaneously with the transverse stretching (simultaneous stretching). This is followed by heat setting of the film at oven temperatures of 200 to 260 ° C, especially at 220 to 250 ° C. The film is then cooled and wound up.

Due to the surprising combination of excellent properties, the White, UV-stabilized film according to the invention excellent for a variety various applications, for example for interior trim, for Exhibition stand construction and exhibition items, for displays, for signs, for labels, for protection glazing of machines and vehicles, in the lighting sector, in the shop and Shelf construction, as a promotional item, laminating medium and in food applications.

Because of the good UV stability, the white film according to the invention is suitable also for outdoor applications, such as B. for roofing, external cladding, Covers, applications in the construction sector, illuminated advertising profiles and in the transport sector.

The invention is explained in more detail below on the basis of exemplary embodiments.

The individual properties are measured in accordance with the following standards or procedure.

Measurement methods Surface gloss

The surface gloss is measured at a measuring angle of 20 ° according to DIN 67530.

Light transmission

Below the light transmission is the ratio of the total transmitted light to understand the amount of incident light.

The light transmission is carried out using the "Hazegard plus" measuring device in accordance with ASTM D 1003 measured.  

Surface defects, homogeneous coloring

The surface defects and the homogeneous coloring are determined visually.

Mechanical properties

The modulus of elasticity, the tensile strength and the elongation at break are in longitudinal and Transverse direction measured according to ISO 527-1-2.

SV (DCE), IV (DCE)

The standard viscosity SV (DCE) is based on DIN 53726 in dichloroacetic acid measured.

The intrinsic viscosity (IV) is calculated as follows from the standard viscosity (SV) IV (DCE) = 6.67. 10 ^-4 SV (DCE) + 0.118

Weathering (both sides), UV stability

The UV stability is tested according to the test specification ISO 4892 as follows
Test device: Atlas Ci 65 Weather Ometer
Test conditions: ISO 4892, ie artificial weathering
Irradiation time: 1000 hours (per side)
Irradiation: 0.5 W / m ² , 340 nm
Temperature: 63 ° C
Relative humidity: 50%
Xenon lamp: inner and outer filter made of borosilicate
Irradiation cycles: 102 minutes of UV light, then 18 minutes of UV light with water spraying the samples, then again 102 minutes of UV light, etc.

Yellowness index

The yellowness index G is the deviation from the colorlessness in the "yellow" direction and will measured according to DIN 6167. Yellow value G values of-5 are not visually visible.

The examples and comparative examples below are each single-layer and multilayer white films based on the extrusion described road to be made.

All foils were processed on both sides per 1000 hours per the test specification ISO 4892 Weathered side with the Atlas Ci 65 Weather Ometer from Atlas and then in terms of mechanical properties, discoloration, surface defects, of light transmission and gloss checked.

example 1

A 50 µm thick, white film is produced, the main component of which is polyethylene terephthalate, 7.0% by weight of titanium dioxide and 1.0% by weight of the UV stabilizer 2- (4.6- Diphenyl-1,3,5-triazin-2-yl) -5- (hexyl) oxyphenol (®Tinuvin 1577 from Ciba-Geigy) contains.

The titanium dioxide is of the rutile type, has an average particle diameter of 0.20 μm and is coated with Al ₂ O ₃ .

Tinuvin 1577 has a melting point of 149 ° C and is thermally stable up to approx. 330 ° C.  

For the purpose of homogeneous distribution, 7.0% by weight of titanium dioxide and 1.0% by weight of the UV stabilizer directly from the raw material manufacturer in the polyethylene terephthalate incorporated.

The polyethylene terephthalate from which the white film is made has one Standard viscosity SV (DCE) of 810, indicating an intrinsic viscosity IV (DCE) of Corresponds to 0.658 dl / g. The moisture content is <0.2%.

The white PET film produced has the following property profile:

• - Thickness: 50 µm
• - Surface gloss 1st page: 72 (Measuring angle 20 °) 2nd side: 68
• - Light transmission: 28%
• - Surface defects per m ² : no elastic modulus along 4300 N / mm ²
• - E-module across: 5600 N / mm ²
• Longitudinal tensile strength: 190 N / mm ²
• - Tear strength across: 280 N / mm ²
• - Elongation at break along: 170%
• - Elongation at break across: 85%
• - Yellow number (YID): 48
• - Coloring: homogeneous

After 1000 hours of weathering per side with Atlas Ci 65 Weather Ometer, the PET film shows the following properties:

• - Thickness: 50 µm
• - Surface gloss 1st page: 70 (Measuring angle 20 °) 2nd side: 66  
• - Light transmission: 27%
• - Surface defects: none (Cracks, embrittlement)
• - Yellow number (YID): 49
• - E-module lengthways: 4150 N / mm ²
• - E-module across: 5600 N / mm ²
• Longitudinal tensile strength: 170 N / mm ²
• - transverse tensile strength: 250 N / mm ²
• - Elongation at break: 150%
• - Elongation at break across: 70%
• - Coloring: homogeneous

Example 2

A white film is produced analogously to Example 1, the UV stabilizer being 2- (4.6- Diphenyl-1,3,5-triazin-2-yl) -5- (hexyl) -oxyphenol (®Tinuvin 1577) in the form of a Masterbatches is metered. The masterbatch consists of 5% by weight ®Tinuvin 1577 as active ingredient and 95% by weight of the polyethylene terephthalate from Example 1 together.

Before the extrusion, 90% by weight of the polyethylene tene finished with titanium dioxide rephthalate from Example 1 with 10 wt .-% of the masterbatch dried at 170 ° C. The Extrusion and film production take place analogously to Example 1.

The white PET film produced has the following property profile:

• - Thickness: 50 µm
• - Surface gloss 1st page: 74 (Measuring angle 20 °) 2nd side: 71
• - Light transmission: 27%
• - Surface defects: none  (Specks, orange peel, blisters, etc.)
• - E-module lengthways: 4200 N / mm ²
• - E-module across: 5650 N / mm ²
• Longitudinal tensile strength: 160 N / mm ²
• - transverse tensile strength: 250 N / mm ²
• - Elongation at break along: 160%
• - Elongation at break across: 75%
• - Yellow number: 46
• - Coloring: homogeneous

After 1000 hours of weathering per side with Atlas Ci 65 Weather Ometer, the PET film shows the following properties:

• - Thickness: 50 µm
• - Surface gloss 1st page: 72 (Measuring angle 20 °) 2nd side: 70
• - Light transmission: 25%
• - turbidity: 4.1%
• - Surface defects: none (Cracks, embrittlement)
• - Yellow number (YID): 47
• - E-module lengthways: 4050 N / mm ²
• - E-module across: 5500 N / mm ²
• Longitudinal tensile strength: 151 N / mm ²
• - Tear strength across: 238 N / mm ²
• - Elongation at break: 152%
• - Elongation at break across: 68%

Example 3

Analogously to Example 2, a white 350 μm thick film is produced.  

The PET film produced has the following property profile:

• - Thickness: 350 µm
• - Surface gloss 1st page: 70 (Measuring angle 20 °) 2nd side: 60
• - Light transmission: 10%
• - Surface defects per m ² : none (specks, orange peel, blisters, etc.)
• - Yellow number: 50
• - E-module lengthways: 3600 N / mm ²
• - E-module across: 4200 N / mm ²
• Longitudinal tensile strength: 180 N / mm ²
• - transverse tensile strength: 200 N / mm ²
• - Elongation at break: 220%
• - Elongation at break across: 190%

After 1000 hours of weathering per side with Atlas Ci 65 Weather Ometer, the PET film shows the following properties:

• - Thickness: 350 µm
• - Surface gloss 1st page: 68 (Measuring angle 20 °) 2nd side: 65
• - Light transmission: 9%
• - Surface defects: none (Cracks, embrittlement)
• - Yellow number (YID): 52
• - E-module lengthways: 3500 N / mm ²
• - E-module transverse: 4050 N / mm ²
• Longitudinal tensile strength: 165 N / mm ²
• - Tear resistance across: 185 N / mm ²
• - Elongation at break: 200%
• - Elongation at break across: 170%

Example 4

According to the coextrusion technology, a 50 µm thick multilayer PET film is used Layer order A-B-A, where B is the core layer and A is the deck represent layers. The core layer B is 48 µm thick and the two deck layers that cover the core layer are each 1 µm thick.

The polyethylene terephthalate equipped with titanium dioxide for the core layer B. halate is identical to that from example 2. The polyethylene terephthalate of the deck layers A are identical to the polyethylene terephthalate from Example 2, but contains no titanium dioxide.

Analogously to Example 2, the 5% by weight ®Tinuvin 1577 masterbatch is used, where but only the 1 µm thick cover layers 20% by weight of the masterbatch over the Masterbatch technology can be added.

The white, multilayer PET film produced, which is UV-stabilized in the outer layers, has the following property profile:

• - Layer structure: A-B-A
• - Total thickness: 50 µm
• - Surface gloss 1st page: 124
• - (measuring angle 20 °) 2nd side: 119
• - Light transmission: 30%
• - Surface defects: none (Specks, orange peel, blisters, etc.)
• - E-module lengthways: 4300 N / mm ²
• - E-module transverse: 5720 N / mm ²
• Longitudinal tensile strength: 180 N / mm ²
• - Tear resistance across: 265 N / mm ²
• - Elongation at break: 165%
• - Elongation at break across: 85%
• - Yellow number / YID): 40
• - Coloring: homogeneous

After 1000 hours of weathering per side with Atlas CI 65 Weather Ometer, the multilayer film shows the following properties:

• - Layer structure: A-B-A
• - Total thickness: 50 µm
• - Surface gloss 1st side: 120
• - (measuring angle 20 °) 2nd side: 115
• - Light transmission: 28%
• - Surface defects: none (Specks, orange peel, blisters, etc.)
• - E-module lengthways: 4175 N / mm ²
• - E-module across: 5650 N / mm ²
• Longitudinal tensile strength: 165 N / mm ²
• - transverse tensile strength: 250 N / mm ²
• - Elongation at break: 155%
• - Elongation at break across: 75%
• - Yellow number / YID): 42
• - Coloring: homogeneous

Comparative Example 1

Analogously to Example 1, a 50 µm thick PET monofilm is produced. In contrast to Example 1 contains no UV stabilizer in the film.  

The unstabilized white film produced has the following property profile:

• - thickness 50 µm
• - Surface gloss 1st page: 70
• - (measuring angle 20 °) 2nd side: 67
• - Light transmission: 27%
• - No surface defects (Specks, orange peel, blisters, etc.)
• - E-module lengthways: 4350 N / mm ²
• - E-module across: 5800 N / mm ²
• Longitudinal tensile strength: 185 N / mm ²
• - transverse tensile strength: 270 N / mm ²
• - Elongation at break along: 160%
• - Elongation at break across: 80%
• - Yellow number / YID): 49

After 1000 hours of weathering on each side with the Atlas CI 65 Weather Ometer the film cracks and embrittlement on the surfaces. A precise one The property profile can therefore no longer be measured. The slide also shows a visually visible higher yellowing.

Claims (34)

1. White, biaxially oriented film, with a thickness in the range from 1 to 500 µm, which contains a crystallizable thermoplastic as the main component, characterized in that it contains at least one UV stabilizer and at least one white pigment. 2. Film according to claim 1, characterized in that the concentration of UV stabilizer in the range of 0.01 to 5 wt .-%, based on the weight of the crystallizable thermoplastics. 3. Film according to claim 1 or 2, characterized in that the UV stabilizer is selected from 2-hydroxybenzotriazoles and / or triazines. 4. Film according to claim 3, characterized in that the UV stabilizer 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5- (hexyl) oxyphenol and / or 2,2'-methylene-bis (6- Is (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol. 5. Film according to one of claims 1-4, characterized in that the White pigment is selected from one or more of the white pigments Titanium dioxide, barium sulfate, calcium carbonate, kaolin and silicon dioxide. 6. Film according to claim 5, characterized in that the white pigment Is titanium dioxide. 7. Film according to claim 5 or 6, characterized in that the white pigment is coated. 8. A film according to claim 7, characterized in that the coating is a is oxidic coating.   9. Film according to claim 8, characterized in that the oxidic coating Oxides of aluminum, silicon, zinc, magnesium or mixtures of two or contains several of these oxides. 10. A film according to claim 7, 8 or 9, characterized in that the coating Alkanols, fatty acids, polydiorganosiloxanes and / or polyorganohydrogensiloxa ne contains. 11. Film according to one of claims 1-10, characterized in that the White pigment in an amount of 0.3-25 wt .-%, based on the weight of the Polymer layer in which the white pigment is contained is present. 12. Film according to one of claims 1-11, characterized in that the White pigment has an average particle size of 0.10-0.30 µm. 13. A film according to any one of claims 1-12, characterized in that the Surface gloss, measured according to DIN 67530 (measuring angle 20 °), is greater than 15. 14. Film according to one of claims 1-13, characterized in that the Light transmission, measured according to ASTM D 1003, is less than 80%. 15. Film according to one of claims 1-14, characterized in that the modulus of elasticity, measured according to ISO 527-1-2, is greater than 3300 N / mm ² in the longitudinal direction and greater than 4800 N / mm ² in the transverse direction. 16. A film according to any one of claims 1-15, characterized in that the crystallizable thermoplastic has a crystallinity ranging from 5 to 65% lies. 17. Film according to one of claims 1-16, characterized in that the crystallizable thermoplastic is selected from polyethylene terephthalate,  Polybutylene terephthalate, polyethylene naphthalate and mixtures of one or several of these thermoplastics. 18. A film according to claim 17, characterized in that as crystallizable Thermoplastic polyethylene terephthalate is used. 19. Film according to claim 18, characterized in that the polyethylene terephthalate halate contains polyethylene terephthalate recyclate. 20. Film according to one of claims 1-19, characterized in that it has a has a single-layer structure. 21. Film according to one of claims 1-19, characterized in that the film a multilayer structure with at least one top layer and at least has a core layer. 22. A film according to claim 21, characterized in that the multilayer Structure two cover layers and one between the cover layers Has core layer. 23. A film according to claim 21 or 22, characterized in that at least one UV stabilizer is contained in the top layers. 24. Film according to one of claims 21-23, characterized in that at least a white pigment is contained in the top layer (s). 25. Film according to one of claims 1-24, characterized in that the film has an adhesion promoter at least on one side. 26. Film according to one of claims 1-25, characterized in that the film on has at least one surface a copolyester.   27. Film according to one of claims 1-26, characterized in that the film on has a scratch-resistant coating on at least one surface. 28. Film according to one of claims 18 or 19, characterized in that the polyethylene terephthalate used has a standard viscosity SV (DCE), measured in dichloroacetic acid according to DIN 53728, which in the range of 600 to 1000 lies. 29. Film according to one of claims 21-23, characterized in that the Cover layers contain polyethylene terephthalate. 30. Film according to one of claims 21-24, characterized in that the Cover layers contain polyethylene naphthalate. 31. Film according to one of claims 21-24, characterized in that the Copers or compounds made of polyethylene terephthalate and Contain polyethylene naphthalate. 32. A method for producing a white film according to any one of claims 1-31, characterized in that the crystallizable thermoplastic in Extruder together with at least one UV stabilizer and at least one melts a white pigment, extruded onto a chill roll, biaxially oriented, fixed and rolled up. 33. The method according to claim 32, characterized in that the crystallizable Thermoplastic is dried in the extruder before melting. 34. The method according to any one of claims 32 or 33, characterized in that that the addition of the UV stabilizer and / or white pigment over the Masterbatch technology is carried out.