DE10023623A1 - White thermally formable film useful as a display,in illumination technology, for e.g. coatings, comprises a crystallizable thermoplastic, a white pigment, a UV stabilizer, and a fire retardant - Google Patents

Abstract

A white heat formable film of thickness 1-350 microns containing a crystallizable thermoplastic as a main constituent, a white pigment, a UV stabilizer, and a fire retardant soluble in the thermoplastic, which is metered in directly during film preparation using master batch technology, while the master batch is subjected to gradual heating under reduced pressure with stirring is new. An Independent claim is included for preparation of the film which involves melting of the thermoplastic in at least one extruder, passage of the polymer mixture obtained, depending on the composition of the film, to a nozzle, or depending on the composition of the top and basic layer, to a multilayer nozzle, extrusion of the mixture on a cooled roller, biaxial stretching and heat fixing of the pre-film obtained, where the polymer melt for the basic layer and top layer contains at least one fire retardant and white pigment, and the polymer melt for the top layer contains at least one UV stabilizer.

Description

The invention relates to a white, flame-retardant, UV-stable, thermoformable, oriented film of a crystallizable thermoplastic whose thickness is in the range from 10 μm to 350 μm. The film contains at least one white pigment and a Flame retardant and a UV absorber and is characterized by good Stretchability and thermoformability, by very good optical and mechanical Properties and through an economical production. The invention relates a process for the preparation of this film and its use.

White, oriented films of crystallizable thermoplastics with a thickness of 10 to 350 microns are well known.

These films contain no UV absorber as a light stabilizer and no Flame retardant, so that neither the films nor the articles made from them for outdoor applications where fire protection or flame retardancy is required, suitable. The films do not meet the fire tests according to DIN 4102 Part 2 and Part 1 and UL Test 94. The films are insufficient thermoformable.

In outdoor applications, these films show a yellowing after a short time and a deterioration of mechanical properties due to a photooxidative degradation by sunlight.

EP-A-0 620 245 describes films which, with regard to their thermal properties, are suitable for use in the production of films Stability are improved. These films contain antioxidants which are suitable are to trap radicals formed in the film and to decompose formed peroxide.  

A suggestion on how to improve the UV stability of such films is this document but not to be seen.

In DE-A 23 46 787 a flame retardant raw material is described. Next to the Raw material is also the use of the raw material to films and fibers claimed.

The production of films from this phospholane-modified raw material showed the following deficiencies:
The raw material is very susceptible to hydrolysis and must be very well pre-dried. When drying the raw material with dryers, which correspond to the prior art, the raw material sticks, so that a film can be produced only under the most difficult conditions.

The films produced under extreme and uneconomic conditions embrittle at temperature loads, d. H. the mechanical properties go due to the regular embrittlement strongly back, so that the film is useless. Already after 48 hours of temperature stress, this embrittlement occurs.

The object of the present invention was to provide a white, flame-retardant, UV-stable, thermoformable, oriented film with a thickness of 10-350 μm to provide, in addition to an economic production, a good Stretchability and good mechanical and optical properties, especially a flame retardant effect, no embrittlement after exposure to temperature, Thermoformability and high UV stability.

A flame retardant effect means that the white film in a so-called Fire test the conditions according to DIN 4102 Part 2 and in particular the Conditions according to DIN 4102 Part 1 fulfilled and into the building material class B2 and in particular B1 of the flame-retardant substances can be classified.  

Furthermore, the film is to pass the UL test 94 "Vertical Burning Test for Flammability of Plastic material "so that it can be classified in the class 94 VTM-0. This means that the film does not work 10 seconds after removing the Bunsen burner more burns, after 30 seconds no glow is observed and no dripping is detected.

High UV stability means that the films can be exposed to sunlight or other UV rays. Radiation is not or only extremely little damage, so that the films for Outdoor and / or critical indoor applications are suitable. In particular the foils should not yellow during outdoor use for several years, none Show embrittlement or cracking of the surface and none Have deterioration of mechanical properties. High UV stability means, therefore, that the film absorbs the UV light and light only in the visible Lets through the area.

Thermoformability means that the film is based on commercial Thermoforming machines without unprofitable predrying to complex and deep-drawing or thermoforming large-area moldings.

Good optical properties include, for example, a homogeneous one Coloring, high surface gloss (<15), low light transmission (<70%) as well as unchanged compared to the flame retardant and UV-treated film Yellowness.

Among the good mechanical properties are high modulus of elasticity (E _MD <3200 N / mm ² , E _TD <3500 N / mm ² ) and good tensile strength values (in MD <100 N / mm ² , in TD <130 N / mm ² ).

Among the good drawability is that the film in its manufacture both in Longitudinal as well as I transverse direction can be oriented perfectly and without breaks.  

For the economic production counts that the raw materials or the Raw material components needed to make the flame retardant film be dried with industrial dryers that meet the standard of technology can be. It is essential that the raw materials do not stick together and not thermally be reduced. These state-of-the-art industrial dryers include Vacuum dryer, fluidized bed dryer, fluid bed dryer, fixed bed dryer (Tower dryer). These dryers work at temperatures between 100 and 170 ° C, where the flame-retardant raw materials stick together and mined must be removed, so that no film production is possible.

The raw material goes through one of the most gently drying vacuum dryers Temperature range from about 30 ° C to 130 ° C at a vacuum of 50 mbar. After that is a so-called. Post-drying in a hopper at temperatures of 100-130 ° C and a residence time of 3 to 6 hours required. Even here, this raw material sticks extreme.

No embrittlement at short temperature load means that the film or the molding after 100 hours annealing at 100 ° C in a convection oven has no embrittlement and no poor mechanical properties.

This object is achieved by a white, thermoformable film having a thickness in the 10-350 microns, the main component of a crystallizable thermoplastic and characterized in that the film comprises at least one white pigment, contains at least one UV absorber and at least one flame retardant, wherein the UV absorber expediently and the flame retardant according to the invention as masterbatch are added directly during film production.

The white, flame retardant, UV-stable, thermoformable, oriented film contains as main component a crystallizable thermoplastic. Suitable crystallizable or semicrystalline thermoplastics are, for example, polyethylene terephthalate,  Polybutylene terephthalate, polyethylene naphthalate, polyethylene terephthalate is preferred.

According to the invention is understood crystallizable under crystallizable thermoplastics Homopolymers, crystallizable copolymers, crystallizable compounds (Mixtures), crystallizable recyclate and other variations of crystallizable Thermoplastics.

The white film can be both single-layered and multi-layered. The foil can also be coated with various copolyesters or adhesion promoters.

The white film contains according to the invention a UV absorber and a Flame retardants. The UV absorber is expediently via the so-called Masterbatch technology dosed directly in the film production, the Concentration of the UV stabilizer preferably between 0.01% by weight and 5% by weight based on the weight of the layer of crystallizable thermoplastic.

The film according to the invention contains at least one flame retardant, over the so-called masterbatch technology is added directly to the film production, wherein the concentration of the flame retardant ranges from 0.5 to 30.0% by weight, preferably from 1.0 to 20.0% by weight, based on the weight of the layer of crystallizable thermoplastics, lies. In the production of the masterbatch is in the In general, a ratio of flame retardant to thermoplastic in the range of 60 to 40 wt .-% to 10 to 90 wt .-% complied with.

The typical flame retardants include bromine compounds, chlorinated paraffins and other chlorine compounds, antimony trioxide, aluminum trihydrate, wherein the Halogen compounds due to the resulting halogen-containing by-products are disadvantageous. Furthermore, the low light resistance is one with it  finished film in addition to the development of hydrogen halides in case of fire extremely disadvantageous.

Suitable flame retardants which are used according to the invention are for example, organic phosphorus compounds such as carboxyphosphinic acids, their Anhydrides and dimethyl methylphosphonate. Essential to the invention is that the organic phosphorus compound in the thermoplastic is soluble, otherwise the required optical properties are not met.

Since the flame retardants in general a certain susceptibility to hydrolysis have, the additional use of a hydrolysis stabilizer may be useful.

As a hydrolysis stabilizer, phenolic stabilizers, alkali metal / Alkaline earth stearates and / or alkali metal / alkaline earth metal carbonates in amounts of from 0.01 to 1.0% by weight used. Phenolic stabilizers are used in an amount of 0.05 to 0.6% by weight, in particular 0.15 to 0.3 wt .-% and with a molecular weight of more than 500 g / mol prefers. Pentaerythrityl tetrakis-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate or 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene especially advantageous.

The white pigment is preferably added via masterbatch technology, but can also be incorporated directly at the raw material manufacturer. The concentration of White pigment is between 0.2% by weight and 40% by weight, preferably between 0.5% by weight. and 25% by weight, based on the weight of the crystallisable Thermoplastics.

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

The titanium dioxide particles may consist of anatase or rutile, preferably predominantly of rutile, which shows a higher opacity compared to anatase.

In a preferred embodiment, the titanium dioxide particles consist of at least 95% by weight. made of rutile. You can by a conventional method, for. B. after the chloride or the sulfate process. Their amount in the base layer is 0.3-25% by weight, based on the base layer, the average particle size is relatively small and is preferably in the range of 0.10 to 0.30 μm.

Titanium dioxide of the type described does not give rise to any formation within the polymer matrix Vacuoles during film production.

The titanium dioxide particles may have a coating of inorganic oxides commonly used as a coating for TiO ₂ white pigment in papers or paints to improve light fastness.

TiO ₂ is known to be photoactive. When exposed to UV rays, free radicals form on the surface of the particles. These free radicals can migrate to the film-forming polymers, resulting in degradation reactions and yellowing. Particularly suitable oxides 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 z. In EP-A-0 044 515 and EP-A-0 078 633. Furthermore, the coating may 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 of 1-34 C atoms). Preferred organic compounds are alkanols and fatty acids having 8-30 carbon atoms in the alkyl group, in particular fatty acids and primary n-alkanols having 12-24 carbon atoms, and polydiorganosiloxanes and / or polyorganohydrosiloxanes such. B. polydimethylsiloxane and polymethylhydrogensiloxane.

The coating of titanium dioxide particles usually consists of 1 to 12, in particular 2 to 6 g of inorganic oxides and 0.5 to 3, in particular 0.7 to 1.5 g of organic Compounds based on 100 g of titanium dioxide particles. The coating will be on the Particles applied in aqueous suspension. The inorganic oxides are made water-soluble compounds, e.g. As alkali, especially sodium nitrate, sodium silicate (Water glass) or silica precipitated in the aqueous suspension.

Under inorganic oxides such as Al ₂ O ₃ or SiO ₂ , the hydroxides or their various dewatering stages such. As oxide hydrate to understand without their exact composition and structure recognizes. On the TiO ₂ pigment, after the annealing and milling in aqueous suspension, the oxide hydrates z. As the aluminum and / or silicon, the pigments are then washed and dried. This precipitation can thus be done directly in a suspension, as obtained in the manufacturing process after the annealing and the subsequent wet grinding. The precipitation of the oxides and / or oxide hydrates of the respective metals is carried out from the water-soluble metal salts in the known pH range, for aluminum, for example, aluminum sulfate in aqueous solution (pH less than 4) is used and by addition of aqueous ammonia solution or sodium hydroxide in the pH range between 5 and 9, preferably between 7 and 8.5, the oxide hydrate like. Assuming a waterglass or alkali aluminate solution, the pH of the TiO ₂ suspension submitted should be in the strongly alkaline range (pH greater than 8). The precipitation is then carried out by addition of 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, wherein the precipitated layers undergo aging. The coated product is separated from the aqueous dispersion and after washing at elevated temperature, in particular at 70 to 100 ° C, dried.

Light, in particular the ultraviolet portion of solar radiation, d. H. the Wavelength range of 280 to 400 nm, induces degradation of thermoplastics, as a result, not only the visual appearance due to color change or yellowing changes, but also the mechanical-physical properties be negatively influenced.

The inhibition of these photooxidative degradation processes is of considerable technical and economic importance, otherwise the possible applications of numerous thermoplastics are drastically limited.

For example, polyethylene terephthalates begin below 360 nm UV light their absorption increases considerably below 320 nm and is below 300 nm very pronounced. The maximum absorption is between 280 and 300 nm.

In the presence of oxygen, chain scissions become major, but none Crosslinks observed. Carbon monoxide, carbon dioxide and carboxylic acids represent the quantitatively predominant Photooxidationsprodukte. In addition to the direct Photolysis of the ester groups still needs to be considered oxidation reactions The peroxide radicals also result in the formation of carbon dioxide to have.

The photooxidation of polyethylene terephthalates can also over Hydrogen cleavage in α-position of the ester groups to hydroperoxides and their Decomposition products as well as associated chain cleavages (H. Day, D.M. Wiles: J. Appl. Polym. Sci 16, 1972, 203).

UV stabilizers or UV absorbers as light stabilizers are chemical Compounds involved in the physical and chemical processes of light-induced Intervene degradation. Soot and other pigments can partially  Cause light protection. However, these substances are for transparent films unsuitable because they lead to discoloration or color change. For transparent, matt Foils are suitable only organic and organometallic compounds that the stabilizing thermoplastics no or only an extremely small color or Give color change, d. H. which are soluble in the thermoplastic.

In the context of the present invention suitable UV stabilizers as light stabilizers are UV stabilizers which are at least 70%, preferably 80%, particularly preferred 90%, of the UV light in the wavelength range from 180 nm to 380 nm, preferably Absorb 280 to 350 nm. These are particularly suitable if they are in Temperature range of 260 to 300 ° C are thermally 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, organo-nickel Compounds, salicylic acid esters, cinnamic acid ester derivatives, resorcinol monobenzoates, Oxalic anilides, hydroxybenzoic acid esters, hindered amines and triazines, wherein the 2-hydroxybenzotriazoles and the triazines are preferred.

The UV stabilizer (s) are preferably contained in the topcoat (s). If necessary, the core layer can be equipped with UV stabilizer

It was completely surprising that the use of the above UV stabilizers in slides led to the desired result. The expert would probably have initially trying to achieve some UV stability via an antioxidant would have However, when weathered, the film quickly turns yellow.

In light of the fact that UV stabilizers absorb the UV light and thus provide protection, the skilled person would have used commercially available stabilizers. He would have found that

• - The UV stabilizer has a lack of thermal stability and at Temperatures between 200 ° C and 240 ° C decomposed and outgassed;  
• - He must incorporate large amounts (about 10 to 15 wt .-%) UV stabilizer, so the UV light is absorbed and thus the film is not damaged.

At these high concentrations, he would have found that the film is yellow after production and around 25 for yellowness differences (YID). He also found that the mechanical properties were adversely affected. When stretching, he would have unusual problems like

• - breaks due to lack of strength, d. H. Modulus too low;
• - nozzle deposits, which leads to profile fluctuations;
• - Roller deposits from the UV stabilizer, resulting in impairments the optical properties (adhesive defects, inhomogeneous surface) leads;
• - Deposits in stretching, fixing frames, which drip on the film.

Therefore, it was more than surprising that even with low concentrations of UV stabilizer excellent UV protection was achieved. Very surprising was that with this excellent UV protection

• The yellowness of the film compared to an unstabilized film in the frame the measurement accuracy does not change;
• - no outgassing, no nozzle deposits, no Set frame evaporations, whereby the film has an excellent appearance and has an excellent profile and excellent flatness;
• - The UV-stabilized film by an excellent stretchability excels so that they are procedurally safe and stable on high speed film lines Produced to production speeds of 420 m / min can.

It was more than surprising that by means of masterbatch technology, a suitable predrying and / or pre-crystallization and optionally use of small amounts of a hydrolysis stabilizer a flame retardant and  Thermoformable film with the required property profile economical and without Bonding in the dryer is producible and that the film after temperature load not embrittled and does not break when bent.

It was very surprising that with this excellent result and the required flame retardancy, the thermoformability and the high UV stability

• The yellowness of the film compared to a non - finished film in the The measuring accuracy is not adversely affected;
• - No outgassing, no nozzle deposits, no frame evaporations occur, whereby the film has an excellent appearance and a has excellent profile and excellent flatness;
• - The flame-retardant, UV-stable film by an excellent Delineatibility distinguishes, making them safe to process and stable on high speed film lines up to speeds of 420 m / min production-safe can be produced.

Thus, a film is also economically viable.

It was also surprising that the films were compared to the Standard thermoplastics have higher diethylene glycol content and / or Polyethylene glycol content and / or IPA content economically to commercially available Thermoforming thermoforming systems and delivering excellent detail reproduction.

Furthermore, it is very surprising that even from the slides or the Regenerat produced moldings is reusable, without the yellowness of the film to influence negatively.

In a preferred embodiment, the invention, white, heavy flammable film as main component a crystallisable polyethylene terephthalate, with a diethylene glycol content of ≧ 1.0% by weight, preferably ≧ 1.2% by weight,  in particular ≧ 1.3% by weight and / or a polyethylene glycol content (PEG content) of ≧ 1.0% by weight, preferably ≧ 1.2 wt .-%, in particular ≧ 1.3 wt .-%, 1 wt .-% to 20 wt .-% an organic soluble in polyethylene terephthalate organic Phosphorus compound (dimethyl methylphosphonate) as flame retardant, 0.01% by weight up to 5.0% by weight of a PET-soluble UV absorber from the group of Hydroxybenzotriazole or the triazines and 0.5 wt .-% to 25 wt .-% titanium dioxide with a particle diameter of preferably 0.10 to 0.50 μm, wherein a titanium dioxide of the rutile type is preferred. Instead of titanium dioxide can also be barium sulfate a particle diameter of 0.20 to 1.20 microns are used as white pigment, the concentration being between 1.0% and 25% by weight. In a Preferred embodiments may also be mixtures of these white pigments or a mixture of one of these white pigments can be used with another.

In a very particularly preferred embodiment, the film according to the invention contains 0.01% by weight to 5.0% by weight of 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5- ( hexyl) oxy phenol of the formula

or 0.01% to 5.0% by weight of 2,2'-methylenebis (6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol of the formula

In a preferred embodiment, mixtures of these two UV Stabilizers or mixtures of at least one of these two UV stabilizers be used with other UV stabilizers, the total concentration of Light stabilizer preferably between 0.01 wt .-% and 5.0 wt .-%, based on the weight of crystallizable polyethylene terephthalate.

Essential for the thermoformability of the invention is that the crystallizable Thermoplastic a diethylene glycol content (DEG content) of ≧ 1.0 wt .-%, preferably ≧ 1.2 wt .-%, in particular ≧ 1.3 wt .-% and / or a polyethylene glycol content (PEG- Content) of ≧ 1.0% by weight, preferably ≧ 1.2% by weight, in particular ≧ 1.3% by weight and / or an isophthalic acid content (IPA) of 3 wt .-% to 10 wt .-%.

The white, UV-stabilized, thermoformable, flame-retardant film has the following property profile:
The surface gloss, measured according to DIN 67530 (measurement angle 20 °), is greater than 15, preferably greater than 20, the light transmission L, measured according to ASTM D 1003 is less than 70%, preferably less than 60% measured according to ASTM S 1003, which is surprisingly good for the UV stability achieved in combination with the low flammability.

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 white polyethylene terephthalate film containing at least one organic white pigment, contains a UV stabilizer and a flame retardant, can be both single-layered as also be multilayered.

In the multilayer embodiment, the film is at least one core layer and at least one cover layer, wherein in particular a three-layered A-B-A or A-B-C structure is preferred.

For this embodiment, it is essential that the polyethylene terephthalate of the Core layer a similar standard viscosity and a similar DEG content and / or PEG content, such as the polyethylene terephthalate of the top layer (s), which adjoins (adjoins) the core layer.

In a particular embodiment, the cover layers can also be made of a Polyethylene naphthalate homopolymers or from a polyethylene terephthalate Polyethylene naphthalate copolymers or a compound.

In this embodiment, the thermoplastics of the cover layers also have one similar standard viscosity and a similar DEG content and / or PEG content as the polyethylene terephthalate of the core layer.

In the multilayer embodiment, the UV absorber is preferably in the Cover layers included. If necessary, the core layer with UV absorber be equipped.  

In the multilayered embodiment, the white pigment and the Flame retardant preferably contained in the core layer. However, at Also needs the outer layers with white pigment and / or flame retardants be equipped.

In another embodiment, white pigment, flame retardants and UV absorbers may be included in the topcoats. If necessary and high fire protection Requirements, the core layer additively called a "basic equipment" Flame retardants included.

Unlike in the single-layered embodiment, the concentration here refers to of the white pigment, flame retardant and UV stabilizer on the weight in the equipped layer.

Quite surprisingly, weathering tests according to the test specification ISO 4892 have with the Atlas CI65 Weather Ometer shown that in the case of a three-layered Film is sufficient, the 0.5 μm to 2 μm thick outer layers with UV To equip stabilizers for improved UV stability.

Fire tests according to DIN 4102 Part 1 and Part 2 as well as the UL-Test 94 have as well Surprisingly, it has been shown that the film according to the invention is already in the thickness range of 5-300 μm meet the requirements.

As a result, those produced by the known coextrusion technology flame retardant, UV stabilized, thermoformable, multi-layer films in the Compared to completely UV-stabilized and flame-finished monofilms economically extremely interesting, since significantly fewer additives for a comparable Flame resistance and UV stability are needed.  

The film can also be at least one-sided with a scratch-resistant coating, with a Copolyester or be provided with a coupling agent.

Weathering tests have shown that the flame retardant, UV-stabilized films even after 5 to 7 years (from the weathering tests extrapolated) outdoor use generally no increased yellowing, none Embrittlement, no loss of gloss of the surface, no cracking on the surface and have no deterioration in mechanical properties.

Measurements showed that the film according to the invention or the molding at Temperature loads of 100 ° C over a longer period of time not embrittled. This result is due to the synergistic effect of suitable precrystallization, Pre-drying, masterbatch technology and UV stabilizer equipment due.

The film can be thermoformed without predrying, so that complex moldings can be made from it.

The thermoforming process usually involves the steps of predrying, heating, Shaping, cooling, demolding, tempering. The thermoforming process has been found that the films according to the invention without prior predrying surprisingly deep-draw. This advantage compared to thermoformable Polycarbonate or polymethacrylate films in which predrying times of 10-15 Hours, depending on thickness at temperatures of 100 ° C to 120 ° C are required, drastically reduces the cost of the forming process.

The following process parameters were found for thermoforming:

step Inventive film Pre-drying not mandatory Temperature of the mold ° C 100 to 160 Heating time <5 sec per 10 μm film thickness Film temperature when deforming ° C 160 to 220 Possible draw factor 1.5 to 2.0 Detail reproduction Well Shrinkage (shrinkage)% <1.5

Furthermore, the film according to the invention or the molded article produced therefrom without environmental impact and without loss of mechanical properties easily recyclable, making them suitable, for example, for use as short-lived Advertising signs for trade fair construction and other promotional items, where fire protection and Thermoformability is desired suitable.

The preparation of the white, flame-retardant, Thermoformable UV-stable film can, for example, by the extrusion process done in an extrusion line.

According to the invention, the flame retardant via the masterbatch technology added. The flame retardant is fully dispersed in a carrier material. When Carrier material come of the thermoplastic itself, such as. B. the polyethylene terephthalate or other polymers that are compatible with the thermoplastic in question.

According to the invention, the UV stabilizer and the white pigment already in Thermoplastic raw material manufacturers are dosed or in the film production in the Dosing extruder.

The DEG content and / or PEG content of the polyethylene terephthalate are in Raw material manufacturer set during the polycondensation process.  

Particularly preferred is the addition of the white pigment and the UV stabilizer over the masterbatch technology. The UV stabilizer or the white pigment is in a solid support material fully dispersed. As support materials come the thermoplastic itself, such as As the polyethylene terephthalate or other polymers, with the Thermoplastics are sufficiently compatible, in question.

Important in the masterbatch technology is that the grain size and the Bulk density of the masterbatch similar to the particle size and the bulk density of the Is thermoplastic, so that a homogeneous distribution and thus a homogeneous UV Stabilization can take place.

The polyester films can be prepared by known methods from a polyester raw material with other raw materials, the flame retardant, the white pigment, the UV Absorber and / or other conventional additives in the usual amount of 1.0 to max. 30% by weight both as a monofilm and as a multilayer, possibly coextruded films with identical or differently shaped surfaces are produced, wherein For example, one surface is pigmented and the other surface is not a pigment contains. Likewise, one or both surfaces of the film according to known Procedures are provided with a conventional functional coating.

It is essential to the invention that the masterbatch containing the flame retardant and optionally containing the hydrolysis stabilizer, pre-crystallized or predried becomes. This predrying involves a gradual heating of the masterbatch below reduced pressure (20 to 80 mbar, preferably 30 to 60 mbar, in particular 40 to 50 mbar) and with stirring and optionally drying at constant, elevated temperature also under reduced pressure. The masterbatch will preferably at room temperature from a dosing in the desired Blending together with the polymers of the base and / or outer layers and if necessary, other raw material components in batches in a vacuum dryer, the During the drying or residence time, a temperature range of 10 ° C to 160 ° C,  preferably 20 ° C to 150 ° C, in particular 30 ° C to 130 ° C, filled. During the approximately 6 hours, preferably 5 hours, especially 4 hours Residence time, the raw material mixture at 10 to 70 rpm, preferably 15 to 65 rpm, in particular stirred at 20 to 60 rpm. The thus pre-crystallized or predried Raw material mixture is in a downstream also evacuated container at 90 to 180 ° C, preferably 100 ° C to 170 ° C, in particular 110 ° C to 160 ° C for 2 to 8 hours, preferably 3 to 7 hours, especially 4 to 6 hours dried.

In the preferred extrusion process for producing the polyester film, the molten polyester material is extruded through a slot die and quenched as a largely amorphous prefilm on a chill roll. This film is then reheated and stretched in the longitudinal and transverse direction or in the transverse and longitudinal direction or in the longitudinal, in the transverse and again and 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 transition temperature), the draw ratio of the longitudinal stretching is usually from 2 to 6, in particular from 3 to 4.5, which is the transverse extent 2 to 5, in particular at 3 to 4.5 and that of the optionally performed second longitudinal or transverse extension is 1.1 to 5. The first longitudinal stretching may optionally be carried out simultaneously with the transverse extension (simultaneous stretching). This is followed by the heat-setting of the film at oven temperatures of 180 to 260 ° C, in particular 220 to 250 ° C. Subsequently, the film is cooled and wound.

Due to the surprising combination of excellent properties is the Inventive film excellent for a variety of applications, For example, for interior trim, for trade fair construction and trade show products, as Displays, for signs, for protective glazing of machines and vehicles, in Lighting sector, in shop and shelf construction, as promotional items, laminating medium, for Greenhouses, canopies, external cladding, covers, applications in the construction sector and illuminated advertising profiles, shadow mats, electrical applications.  

Due to the thermoformability, the film according to the invention is suitable for Thermoforming of any shaped body for indoor and outdoor applications.

The invention will be explained in more detail below with reference to exemplary embodiments.

The measurements of the individual properties are carried out according to the following Standards or procedures.

measurement methods DEG content / PEG content / IPA content

The DEG / PEG / IPA content is determined by gas chromatography after solution of the thermoplastic Raw material in cresol determined.

surface gloss

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

light transmission

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

The light transmission is measured with the measuring device "®HAZEGARD plus" according to ASTM D 1003 measured.

cloudiness

Turbidity is the percentage of transmitted light emitted by the incident light beam deviates on average by more than 2.5 °. The focus will be determined at an angle smaller than 2.5 °.

The turbidity is measured with the "HAZEGARD plus" measuring instrument according to ASTM D 1003.  

surface defects

The surface defects are determined visually.

Mechanical properties

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

SV (DCE), IV (DVE)

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

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

IV (DCE) = 6.67.10 ^-4 SV (DCE) +0.118

fire behavior

The fire behavior is in accordance with DIN 4102 Part 2, building material class B2 and DIN 4102 Part 1, building material class B1 and according to the UL test 94 determined.

Weathering (two-sided), UV stability

The UV stability is tested according to the test specification ISO 4892 as follows:
Test equipment: Atlas Ci 65 Weather Ometer
Test conditions: ISO 4892, ie artificial weathering
Irradiation time: 1000 hours (per page)
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 of samples, then again 102 minutes of UV light, etc.

yellowness

The (YID) is the deviation from the colorlessness in the direction of "yellow" and is according to DIN 6167 measured. Yellow values (YID) of <5 are not visually visible.

In the following examples and comparative examples are each white films of different thickness on the described extrusion line getting produced.

All films were tested according to the test specification ISO 4892 on both sides per 1000 hours per Page with the Atlas Ci 65 Weather Ometer of the company Atlas weathered and then in terms of mechanical properties, the yellowness index (YID), the Surface defects, light transmission and gloss tested.

On all films were fire tests according to DIN 4102, Part 2 and Part 1 and UL test 94 performed.

Examples example 1

It is made a 50 m thick white film, the main ingredient Polyethylene terephthalate, 7.0 wt .-% titanium dioxide and 1.0 wt .-% of the UV stabilizer 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5- (hexyl) -oxyphenol (®Tinuvin 1577 from Ciba) Geigy) and 2.0 wt .-% flame retardant.

The titanium dioxide is of the rutile type, has a mean 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 thermal up to 330 ° C stable.

For homogeneous distribution, the titanium dioxide and the UV absorber directly at Raw material manufacturer incorporated into the PET.

The flame retardant is the PET soluble organic Phosphorus compound Amgard P1045 from Albright & Wilson.

The flame retardant is added in the form of a masterbatch. The masterbatch is composed of 10% by weight of flame retardant and 80% by weight of PET and has a bulk density of 750 kg / m ³ .

The PET from which the film is made, and the PET that is used to make it Masterbatch production has a standard viscosity of SV (DCE) of 810, which corresponds to an intrinsic viscosity IV (DCE) of 0.658 dl / g. The DEG Content and the PEG content are 1.6 wt .-%.

50% by weight of the polyethylene terephthalate, 30% by weight of polyethylene terephthalate Recyclate and 20% by weight of the masterbatch are released at room temperature filled separate dosing containers in a vacuum dryer, the of the Filling time until the end of the residence time a temperature range of 25 ° C to Goes through 130 ° C. During the approximately 4-hour residence time, the raw material mixture stirred at 61 rpm.

The pre-crystallized or predried raw material mixture is in the downstream, also under vacuum hopper at 140 ° C for 4 hours dried. Subsequently, with the described extrusion process, the 50- μm monofilm.  

The individual process steps were:
longitudinal stretching
Temperature: 85-135 ° C
Longitudinal stretch ratio: 4.0: 1
transverse stretching
Temperature: 85-135 ° C
Transverse stretch ratio: 4.0: 1
fixation
Temperature: 230 ° C

The produced white PET film has the following property profile:
Thickness: 50 μm
Surface gloss 1st page: 72
(Measuring angle 20 °) 2nd page: 68
Light transmission: 28%
Surface defects per m ² : none
E-module longitudinal: 3700 N / mm ²
E-module transverse: 4800 N / mm ²
Longitudinal tear strength: 130 N / mm ²
Tear resistance transverse: 205 N / mm ²
Yellow value (YID): 48
Coloring: homogeneous

According to DIN 4102 Part 2 and Part 1, the foil complies with building material classes B2 and B1. The Foil passes the UL test 94.

After 200 hours annealing at 100 ° C in a circulating air dryer cabinet are the mechanical properties unchanged. The slide shows no Embrittlement.  

After every 1000 hours of weathering per side with the Atlas CI 65 Weather Ometer, the PET film has the following properties:
Thickness: 50 μm
Surface gloss 1st page: 65
(Measuring angle 20 °) 2nd page: 60
Light transmission: 35%
Surface defects per m ² : none
E-module longitudinal: 3550 N / mm ²
Modulus transverse: 4650 N / mm ²
Longitudinal tear strength: 118 N / mm ²
Tear resistance transverse: 190 N / mm ²
Yellow value (YID): 49

Example 2

After coextrusion technology is a 17 micron thick multilayer PET film with layer sequence A-B-A, where B is the core layer and A is the Cover layers represent. The core layer is 15 μm thick and the two Cover layers covering the core layer are each 1 μm thick.

The polyethylene terephthalate used for the core layer B is identical to that of Example 1, but contains no UV absorber.

The core layer also contains 2% by weight of flame retardant, the Flame retardant is added in the form of a masterbatch. The masterbatch sets composed of 10% by weight of flame retardant and 90% by weight of PET.

The PET of the outer layers has a standard viscosity SV (DCE) of 810 and is with 1 wt .-% Tinuvin 1577 and 0.3 wt .-% Sylobloc equipped. The cover layers contain no titanium dioxide and no flame retardant.  

For the core layer, 50% by weight of polyethylene terephthalate, 30% by weight Polyethylene terephthalate recyclate and 20% by weight of the masterbatch, respectively Example 1 pre-crystallized, predried and post-dried.

The top layer raw material undergoes no special drying. Coextrusion technology produces a 17 μm thick film with the layer sequence ABA, which exhibits the following properties:
Layer structure: ABA
Total thickness: 17 μm
Surface gloss 1st page: 131
(Measuring angle 20 °) 2nd page: 126
Light transmission: 49%
Surface defects: none (specks, orange peel, blisters ...).
E-module longitudinal: 3550 N / mm ²
E-module transverse: 4130 N / mm ²
Longitudinal tear strength: 120 N / mm ²
Tear resistance transverse: 155 N / mm ²
Yellow value (YID): 13.3
Coloring: homogeneous

After 200 hours annealing at 100 ° C in a circulating air dryer cabinet are the mechanical properties unchanged. The slide shows no Embrittlement.

According to DIN 4102 Part 2 and Part 1, the foil complies with building material class B2 and B1. The foil passes the UL test 94.  

After every 1000 hours of weathering per side with the Atlas CI 65 Weather Ometer, the PET film has the following properties:

Layer structure: ABA
Total thickness: 17 μm
Surface gloss 1st page: 125
(Measuring angle 20 °) 2nd page: 116
Light transmission: 45%
Surface defects: none (specks, orange peel, blisters ...).
E-module lengthwise: 3460 N / mm ²
E-module transverse: 4050 N / mm ²
Longitudinal tear strength: 110 N / mm ²
Tear resistance transverse: 145 N / mm ²
Yellow value (YID): 15.1
Coloring: homogeneous

Example 3

According to Example 2, a 20 microns A-B-A film is produced, wherein the core layer B 16 microns and the outer layers A are each 2 microns thick.

The core layer B contains only 5% by weight of the flameproofing masterbatch from Example Second

The cover layers are identical to those of Example 2, but contain 20 wt .-% of the flame retardant masterbatch, which in Example 2 only for the core layer was used.

The raw materials and the masterbatch for the core layer and the top layers become pre-crystallized according to Example 1, predried and subsequently dried.  

The coextruded, multi-layer 20 μm film has the following property profile:
Layer structure: ABA
Total thickness: 20 μm
Surface gloss 1st page: 136
(Measuring angle 20 °) 2nd page: 128
Light transmission: 41%
Surface defects: none (specks, orange peel, blisters ...).
E-module lengthwise: 3400 N / mm ²
E-module transverse: 4100 N / mm ²
Longitudinal tear strength: 120 N / mm ²
Tear resistance transverse: 160 N / mm ²
Yellow value (YID): 13.1

After 200 hours annealing at 100 ° C in a circulating air dryer cabinet are the mechanical properties unchanged. The slide shows no Embrittlement.

According to DIN 4102 Part 2 and Part 1, the foil complies with building material classes B2 and B1. The Foil passes the UL test 94.

After every 1000 hours of weathering per side with the Atlas CI 65 Weather Ometer, the PET film has the following properties:
Layer structure: ABA
Total thickness: 20 μm
Surface gloss 1st page: 124
(Measuring angle 20 °) 2nd page: 117
Light transmission: 38%
Surface defects: none (specks, orange peel, blisters ...).
E-module longitudinal: 3350 N / mm ²
E-module transverse: 4000 N / mm ²
Longitudinal tear strength: 105 N / mm ²
Tensile strength transverse: 140 N / mm ²
Yellow value (YID): 15.8

thermoformability

The films of Examples 1 to 3 can be commercially available Thermoforming machines, z. B. Fa. Illig, without predrying to form bodies thermoforming. The detail reproduction of the shaped bodies is homogeneous Surface excellent.

Comparative Example 1

Example 2 is repeated. The film is not with UV absorbers and not with Flame retardant masterbatch equipped. The DEG content is commercially available 0.7%, there is no PEG included.

The produced white film has the following property profile:
Layer structure: ABA
Total thickness: 17 μm
Surface gloss 1st page: 139
(Measuring angle 20 °) 2nd page: 130
Light transmission: 50%
Surface defects: none (specks, orange peel, blisters ...).
E-module longitudinal: 4250 N / mm ²
E-module transverse: 4700 N / mm ²
Longitudinal tear strength: 180 N / mm ²
Tear resistance transverse: 215 N / mm ²
Yellow value (YID): 12.0
Coloring: homogeneous

The unexposed foil fulfills the tests according to DIN 4102 part 1 and part 2 as well as the UL test 94 not.

The film is insufficiently thermoformable.

After 1000 hours of weathering per page with the Atlas CI Weather Ometer, the Foil on the surfaces cracks and embrittlement phenomena. A precise Property profile - especially the mechanical properties - therefore can not be measured more. In addition, the film shows a visual visible yellowing.

Claims (27)

1. White, thermoformable film having a thickness in the range of 1 to 350 .mu.m, which contains as its main component a crystallizable thermoplastic, characterized in that it contains at least one white pigment, at least one UV stabilizer and at least one flame retardant which is soluble in the thermoplastic and is added via the masterbatch technology directly in the film production and wherein the masterbatch was pretreated by gradual heating under reduced pressure and with stirring. 2. A film according to claim 1, characterized in that directly to the Gradial heating under reduced pressure and with stirring a post-drying at constant, elevated temperature also under reduced pressure followed. 3. A film according to claim 1 or 2, characterized in that the concentration of the UV stabilizer in the range of 0.01 to 5 wt .-%, based on the Weight of crystallizable thermoplastic, lies. 4. A film according to claim 1 or 2, characterized in that the UV Stabilizer is selected from 2-hydroxybenzotriazoles and / or triazines. 5. A film according to claim 4, 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- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) -phenol.   6. A film according to any one of claims 1 to 5, characterized in that the Flame retardant is selected from one or more organic Phosphorus compounds, preferably dimethyl methylphosphonate. 7. A film according to any one of claims 1 to 6, characterized in that the film Contains 0.5 to 30.0 wt .-% flame retardant. 8. A film according to any one of claims 1-7, characterized in that the White pigment is selected from one or more of the white pigments Titanium dioxide, barium sulfate, calcium carbonate, kaolin and silica. 9. A film according to claim 8, characterized in that the white pigment Titanium dioxide is. 10. A film according to any one of claims 1 to 9, characterized in that the White pigment is coated. 11. A film according to any one of claims 1-10, characterized in that the White pigment in an amount of 0.2-40 wt .-%, based on the weight of Polymer layer containing the white pigment is present. 12. A film according to any one of claims 1-11, characterized in that the White pigment has an average particle size of 0.10-0.30 microns. 13. A film according to any one of claims 1-12, characterized in that the Surface gloss, measured to DIN 67530 (measuring angle 20 °), greater than 15 is. 14. A film according to any one of claims 1-13, characterized in that the Light transmission, measured according to ASTM D 1003, is less than 70%.   15. A film according to any one of claims 1-14, characterized in that the modulus of elasticity, measured according to ISO 527-1-2, in the longitudinal direction greater than 3200 N / mm ² and in the transverse direction is greater than 3500 N / mm ² . 16. A film according to any one of claims 1-15, characterized in that the crystallizable thermoplastic is selected from polyethylene terephthalate, Polybutylene terephthalate, polyethylene naphthalate and mixtures of one or several of these thermoplastics. 17. A film according to claim 16, characterized in that as crystallizable Thermoplastic polyethylene terephthalate is used. 18. A film according to claim 17, characterized in that the film is recyclate contains. 19. A film according to any one of claims 1-18, characterized in that it has a has a single-layer structure. 20. A film according to any one of claims 1-18, characterized in that the film a multi-layered structure with at least one cover layer and at least having a core layer. 21. A film according to claim 20, characterized in that the multilayer Structure two cover layers and one lying between the cover layers Core layer has. 22. A film according to claim 20 or 21, characterized in that at least one UV stabilizer is contained in the / the outer layers.   23. A film according to any one of claims 20-22, characterized in that at least one white pigment is contained in the base layer. 24. A film according to any one of claims 20-23, characterized in that at least one flame retardant is contained in the base layer. 25. A process for producing a thermoplastic film according to claim 1, at a crystallizable thermoplastic in at least one extruder is melted and the resulting polymer melt according to the Composition of the film layer of a nozzle or the obtained Polymer melts according to the compositions of the cover and Base layers are fed to a multi-layer nozzle, from the nozzle to a Cooling roll are extruded and the resulting prefilm then biaxially stretched and heat set, wherein the polymer melt (s) for the Base layer and / or for the cover layer (s) at least one Flame retardant and / or white pigment and the polymer melt for the top layer (s) contain at least one UV stabilizer. 26. The method according to claim 25, characterized in that the addition of the Flame retardant and / or UV stabilizer and / or white pigments on the Masterbatch technology is done. 27. Use of a film according to claim 1 as interior trim, as a display, for signs, for protective glazing, in the lighting sector, in shops and shops Shelving, as promotional items, laminating medium, for greenhouses, Roofing, external cladding, covers, in the construction sector, as Illuminated profile, shadow mat or in electrical applications.