MXPA99001183A - Multilayered crystallizable thermoplastic plate, process for its production and use thereof - Google Patents

Abstract

A multilayered transparent amorphous thermoplastic plate with at least one central layer and at least one outer layer which are mainly composed of crystallizable thermoplastic. The thermoplastic of the central layer has a higher standard viscosity than the outer layer. The invention also relates to a method of manufacture for the above-mentioned plate as well as to its use. According to the invention the plate can also contain at least one additive such as ultra violet stabilizers, antioxidant agents and/or one anti-scratch coating on at least one side.

Description

MULTI-LAYER LAYER OF A CRYSTALLIZABLE THERMOPLASTIC, A PROCEDURE FOR ITS PRODUCTION AND ITS USE DESCRIPTIVE MEMORY The invention relates to a transparent, amorphous multilayer film of a crystallizable thermoplastic whose thickness is in the range of 1 to 20 mm.

In addition, the invention relates to a process for the production of this sheet and its use. Multilayer sheets of plastic materials are known as such. Such branched polycarbonate sheets are described in EP-A-0 247 480, EP-A-320 632 and US-A 5,108,835. UV-stabilized shaped polycarbonate articles, which are constructed from polydiorganosiloxane polycarbonate block copolymers, are known from DE-A-34 14 116 and US-A-4,600,632. Multilayer sheets of plastics with layers of polydiorganosiloxane polycarbonate block copolymers, which comprise UV absorbers are known from US-A-5,137,949. Branched polycarbonates from specific diphenols, stabilized for UV, are known from EP-A-0 416 404. It is mentioned that such polycarbonates can be used for the production of interwoven sheets or multiple sheets.

All these sheets are made of polycarbonate, an amorphous thermoplastic that can not be crystallized. Polycarbonate sheets have the disadvantage that they often lead to blooming in the form of white spots and deposits on the surface, especially in the UV stabilized form (cf EP-A-0 649 724). According to EP-A-0 649 724, for example, the evaporation of the UV absorber is highly bound to the average molecular weight. In addition, these PC boards are easily flammable and therefore require the addition of fire retardant agents so that they can be used for certain purposes, such as their application indoors. Tedious pre-drying times are required, as well as relatively long processing times for the subsequent processing of these sheets to be molded. In addition, devolatilizing extruders should be used during the production of the sheets for the purpose of extracting moisture, which means that the additives added to the raw materials can also be removed at the same time, especially if they are of low molecular weight and are easily volatile additives. . They have been described above, single-layer transparent amorphous sheets, having a thickness in the range of 1 to 20 mm which comprise, as the main constituent, a crystallizable thermoplastic, such as, for example, polyethylene terephthalate, by the applicant (German patent applications Nos. 19519579-5, 19522118.4 and 195288336.8). These sheets can have a standard viscosity of 800 to 6000 and / or include a UV stabilizer. EP-A-0 471 528 describes a method for configuring an object from a sheet of polyethylene terephthalate (PET). The PET sheet is heat treated on both sides in a thermoformer mold in a temperature range between the glass transition temperature and the melting temperature. The already formed PET foil is removed from the mold when the degree of crystallization of the already formed PET foil is in the range of 25 to 50%. The PET sheets indicated in EP-A-0 471 528 have a thickness of 1 to 10 mm, since the thermoformed shaped article produced from this PET sheet is partially crystalline, and therefore not transparent, and since the surface properties of the shaped article are determined by the thermoforming process and the temperature and shapes given by it, the optical properties (for example, brightness, turbidity and light transmission) of the PET sheets used are not important . As a rule, the optical properties of these sheets are poor and need optimization. These sheets of polyethylene terephthalate also have a single layer construction. US-A 3 496 143 describes the vacuum thermoforming of a 3 mm thick PET film, whose crystallization should be in the range that goes from 5 to 25%. The crystallinity of the thermoformed shaped article is greater than 25%. Furthermore, on these PET sheets, no requirements are imposed on the optical properties. Since the crystallinity of these used films is between 5% and 25%, these films are turbid and non-transparent. These partially crystalline PET sheets are also single layer. Austrian Patent Specification No. 304 086 describes a process for the production of transparent shaped articles by the thermoforming process, a PET film or film having a degree of crystallinity of less than 5% is used as the starting material . The sheet or film used as the starting material has been produced from PET having a crystallization temperature of at least 160 ° C. From that relatively high temperature of crystallization it follows that the PET here is not a PET homopolymer but a PET modified with glycol, called PET-G for brevity, which is a PET copolymer. Unlike pure PET, PET-G shows an extremely low tendency towards crystallization and is generally present in the amorphous state, due to the additionally incorporated glycol units. The object of the present invention is to provide a transparent, amorphous, multilayer sheet having a thickness of 1 mm to 20 mm, which is distinguished by good mechanical and optical properties. Good optical properties include, for example, high light transmission, high surface brightness, extremely low haze, and high image definition (clarity). The good mechanical properties include, inter alia, a high impact force and a high force towards the fracture. Furthermore, the sheet according to the invention must be recyclable, in particular without loss of its mechanical properties, and poorly combustible, so that, for example, it can be used for interior applications and in exhibition construction. This objective is achieved by an amorphous, transparent, multilayer sheet having a thickness of 1 to 20 mm which includes a crystallizable thermoplastic as the main constituent, wherein the sheet has at least one core layer and at least one layer of cover, and where the viscosity of the crystallizable thermoplastic of the core layer is higher than the standard viscosity of the crystallizable thermoplastic layer of the shell. The amorphous sheet in the context of the present invention is understood as those sheets that are not crystalline, although the crystallizable thermoplastic used preferably has a crystallinity of between 5 and 65%. Non-crystalline, this is essentially amorphous, means that the degree of crystallinity is generally below 5%, preferably below 2%, and particularly preferable is 0%, and that the sheet essentially shows no orientation. According to the invention, the following is understood as crystallizable thermoplastic - crystallizable homopolymers, - crystallizable copolymers, - crystallizable compounds, - recyclable crystallizable material and - other variations of thermoplastics.

Examples of suitable thermoplastics are polyalkylene terephthalates with an alkylene radical of Cl to C12, such as polyethylene terephthalate and polybutylene terephthalate, polyalkylene naphthalate with an alkylene radical of Cl to C12, such as polyethylene naphthalate and polybutylene naphthalate, and crystallizable cycloolefin polymers and cycloolefin copolymers, it being possible for the thermoplastic or thermoplastics for the core layer or layers and the thermoplastic for the layers or cover layer to be identical or different. Polyolefins have also proven to be appropriate for cover layers. Thermoplastics having a melting point of Tm glass, measured by differential scanning calorimetry (DSC), with a heating rate of 10 ° C / minute, from 220 ° C to 260 ° C, preferably from 230 ° C to 250 ° C ° C, a temperature range of crystallization Tc between 75 ° C and 260 ° C, a glass transition temperature Tg between 65 ° C and 90 ° C and a density, measured in accordance with DIN 53479, of 1.30 a 1.45 g / cm3 and a crystallinity of between 5% and 65% are preferred for the core layers and the cover layers as starting materials for the production of the sheet. A thermoplastic having a cold crystallization temperature Tcc of 120 to 158 ° C, in particular 130 to 158 ° C, is particularly preferred for the purposes according to the invention. The bulk density, measured in accordance with DIN 53466, is preferably between 0.75 kg / dm and 1.0 kg / dm, and particularly preferably between 0.80 kg / dm3 and 0.90 kg / dm. The polydispersity Mw / Mn of the thermoplastic, measured by means of GPC, is preferably between 1.5 and 6.0, and particularly preferably between 2.0 and 5.0. A particularly preferred crystallizable thermoplastic for the core layer or layers and the cover layer or layers is polyethylene terephthalate. The polyethylene terephthalate preferably used according to the invention essentially comprises monomer units of the following formula it is essential to the invention that the thermoplastic or thermoplastics of the core layer or layers have or have a standard viscosity greater than that of the thermoplastic or thermoplastics of the cover layer or layers. The standard viscosities of several core layers and / or multilayer sheet cover may differ. The standard viscosity SV (DCA) of the crystallizable thermoplastic of the central layer, measured in dichloroacetic acid according to DIN 53728, is preferably between 800 and 5000, and particularly preferably between 1000 and 4500. The SV standard viscosity (DCA) of the crystallizable thermoplastic of the cover layer, measured in dichloroacetic acid according to DIN 53728, is preferably between 500 and 4500, and particularly preferable between 700 and 4000. The intrinsic viscosity IV (DCA) can be calculated from the standard viscosity SV (DCA) as follows: IV (DCA) = 6.67 X 10"SV (DCA) + 0.118 The crystallizable thermoplastics used according to the invention can be obtained by the usual methods known to the expert, in general, thermoplastics, such as those used according to the invention, they can be obtained by polycondensation in the melted materials or by a two-stage polycondensation. executed to a moderate molecular weight, which corresponds to a moderate intrinsic viscosity IV of about 0.5 to 0.7 in the molten materials, and the subsequent condensation is carried out by means of solid condensation. The polycondensation is generally carried out in the presence of known polycondensation catalysts or catalytic systems. In solid condensation, pieces of the thermoplastic are heated to temperatures in the range of 180 to 320 ° C under reduced pressure or under an inert gas until the desired molecular weight is achieved. For example, the preparation of polyethylene terphthalate, which is particularly preferred according to the invention, is described in detail in a large number of patent applications, such as in JP-A-60-139 717, DE-C-2-429 087, DE-A- 27 07 491, DE-A-23 19 089, DE-A-16 94 461, JP-63-41 528, JP-62-39 621, DE-A-41 17 825, DE-A-42 26 737, JP-60-141 715, DE-A-27 21 501 and US-A-5-296 586. Polyethylene terephthalates having a particularly high molecular weight can be prepared, for example, by polycondensation of acid diols precondensates. dicarboxylic (oligomers), at elevated temperatures in a liquid heat transfer medium in the presence of the customary polycondensation catalysts and, if appropriate, by co-condensable modifying agents, if the liquid heat transfer medium is inert and free of charge. aromatic structural groups and has a boiling point in the range of 200 to 320 ° C, the weight ratio of the dicarboxylic acid diols precondensate (ol igomers) used for the liquid heat transfer medium is in the range of 20:80 to 80:20, and the polycondensation is carried out in a boiling reaction mixture in the presence of a dispersion stabilizer. In addition, the transparent, multi-layered, amorphous sheet according to the invention can be treated with appropriate additives, if desired. These additives may be added, as required, to one or more layers of the sheet individually or as a mixture. Examples of suitable additives are the ultraviolet stabilizers and antioxidants, such as those described in German patent application No. 195 221 18.4 and the same applicant application, filed at the same time, entitled "Stability Polyethylene Terephthalate Sheet improved towards hydrolysis ". As a reference, these applications are valid as a constituent of the presentment of the content of the present application. As mentioned above, the transparent, multi-layered, amorphous sheet may additionally include at least one ultraviolet stabilizer as a light stabilizer in the layer s of the cover layers and / or in the core layer or layers. Light, in particular the ultra violet portion of solar radiation, that is, the wavelength range from 280 to 400 nm, initiates the degradation processes in thermoplastics, as a result of which not only the visual appearance changes, due to a change in color or yellowing, but also the physical-mechanical properties are adversely influenced. The inhibition of these photo-oxidative degradation processes are of considerable industrial and economic importance, since otherwise the possible uses of various thermoplastics are drastically limited. A high stability to UV light means that the sheet is not damaged, or if it does occur to a very low degree, by sunlight or other UV radiation, so the sheet is suitable for exterior applications and / or critical interior applications, and shows little or no yellowing to one after several years of external use. Polyethylene terephthalates, for example, begin to absorb UV light below 360 nm, and 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, chain breaking reactions are observed mainly, not cross-linking reactions. Carbon monoxide, carbon dioxide and carboxylic acids are the predominant photooxidation products in terms of quantity, in addition to the direct photolysis of the ester groups, the oxidation reactions that probably result in the formation of carbon dioxide through of peroxide radicals should also be taken into consideration. The photooxidation of polyethylene terephthalates can also lead, by means of the separation of hydrogen in the alpha position of the ester groups, to hydroperoxides and decomposition products and to the associated chain breaking reactions (H. Day, D. M. iles: J. Appl. Polym, Sci 16, 1972, page 203). UV stabilizers, also called light stabilizers or UV absorbers, are chemical compounds that intervene in the physical and chemical processes of light-induced degradation. Certain pigments, such as, for example, carbon black, can partially also have the effect of light stabilization. However, these substances are unsuitable for the transparent sheets according to the invention, since they lead to discoloration to a change in color. Only those UV stabilizers, for example, coming from the class of organic and organometallic compounds which contribute very little, or with no color or change of color in the thermoplastic to be stabilized, are conveniently used for the amorphous sheets in accordance with the invention Examples of UV stabilizers, which are suitable for the present invention, are 2-hydroxybenzophenones, 2-hydroxybenzotriazoles, organo-nickel compounds, salicylic acid esters, cinnamic acid ester derivatives, resorcinol monobenzoate, oxalic acid anilines, esters of sterically hindered hydroxybenzoic acid, amines and triazines, and 2-hydroxybenzotriazoles, with triazines being preferred. Mixtures of various UV stabilizers can also be used. The UV stabilizer is conveniently present in a cover layer in a concentration of 0.01% by weight to 8.0% by weight, based on the weight of the thermoplastic in the cover layer treated with the stabilizer. However, the UV stabilizer can also be added to a central layer. In this case, a concentration of 0.01% by weight to 1%, based on the weight of the thermoplastic in the central layer treated with the stabilizer, is sufficient. According to the invention, several layers can be treated simultaneously with the UV stabilizer. In general, however, it is sufficient to treat the layer on which the UV radiation strikes. The central layer or layers can be treated to prevent radiation damage to the central layer in the event of possible damage to the cover layers.

In a particularly preferred embodiment, the transparent, amorphous sheet according to the invention includes, as the main constituent, a crystallizable polyethylene terephthalate for the core layer and the cover layer and 0.01% by weight to 8% by weight of 2 - (4,6-diphenyl-1,3,5-triazin-2-yl) -5- (hexyl) oxyphenol or 0.01% by weight at 8.0% by weight of 2,2'-methylenebis (6- (2H- benzotriazol-2-yl) -4- (1,1,3, 3-tetra-methyl-butyl) phenol in the cover layer A mixture of these compounds and a mixture of at least one of these compounds with some other stabilizer UV can be used The sheet according to the invention can also be treated with at least one antioxidant.Antioxidants are chemical compounds that retard oxidation and the phenomena of hydrolysis and the resulting aging.Antioxidants that may be suitable for the sheet according to the invention they can be classified as follows: Mixtures of primary and secondary antioxidants and / or mixtures of secondary and / or primary antioxidants with UV stabilizers can also be used. It has been found, surprisingly, that such mixtures show a synergistic effect. In a preferred embodiment, the amorphous sheet according to the invention includes a phosphite and / or a phosphonite and / or a carbodiimide as a stabilizer for hydrolysis and oxidation. Examples of antioxidants used according to the invention are 2- [(2, 4, 8, 10-tetrakis (2, 1-dimethylethyl) -dibenzo- [d, f] [1, 3, 2] -dioxoafosfepin-6- il] oxy) -ethyl] ethanamine and tris (2,4-di-tert-butylphenyl) phosphite. The antioxidant is usually present in a concentration of 0.01 to 6% by weight, based on the weight of the thermoplastic of the layer treated with this antioxidant. The thickness of the multilayer sheet, according to the invention, varies between 1 mm and 20 mm, it being possible for the thickness of the cover layer to be between 10 μm and 1 mm, depending on the thickness of the sheet. Preferably, each of the cover layers have a thickness between 400 and 500 μm. As indicated above, the sheet, according to the invention, can have several central and cover layers which are placed one on top of the other as a sandwich. However, the sheet may also consist of only one cover layer and one core layer. A structure having two cover layers and a central layer placed between the cover layers is particularly preferred according to the invention. The individual center and cover layers may include different crystallizable or identical thermoplastics as the main constituents, as long as the thermoplastic of a core layer has a higher standard viscosity than the thermoplastic of the cover layers directly adjacent to this core layer. If desired, the multi-layer, amorphous, transparent sheet according to the invention, which optionally includes one or more additives, may be provided with a scratch-resistant surface on one side or on several sides. The possible systems and coating materials for the scrap resistant (coating) surface are all systems and materials known to the expert. Suitable coating systems and materials are described, in particular, in the applicant's German patent application No. 196 255 34.1, to which content in total is referred to in this invention. From the large number of possible coating systems and materials, some are mentioned as examples. (1) US-A-4822828 discloses aqueous and radiation curable coating compositions which include, in each case based on the weight of the dispersion, (A) from 50 to 85% of a silane having vinyl groups, (B) ) from 15 to 50% of a multifunctional acrylate and, if appropriate, (C) 1 to 3% of a photoinitiator. (2) Inorganic / organic polymers are also known, called ormocers (organically modified ceramics), which combine the properties of ceramic materials and polymers. The ormocers are used on polymethyl methacrylate (PMMA) and polycarbonate (PC), in particular, as hard and / or scratch resistant coatings. The hard coatings are bonded on the basis of AI2O3, r? 2, IO2 or SiO2 as matrix formers and with epoxide or methacrylate groups with Si-C compounds. (3) Coating mixtures for acrylic and polycarbonate plastic resins based on silicone resins in aqueous organic solution, which has a high storage stability are described, for example, in EP-A-0 073 362 and EP-A-0 073 911. This technique uses the condensation products of partially hydrolyzed organosilicon compounds as final coating mixtures for glass, and in particular for acrylic resin and PC plastics. (4) Acrylic-containing coatings are also known, such as, for example, Uvecril coatings of the UCB chemicals. An example is Uvecril 29203, which is cured with UV light. This material includes a mixture of urethane acrylate oligomers with monomers and additives. The constituents are about 81% acrylate oligomers and 19% hexanediol diacrylate. These coatings are also described for PC and PMMA. (5) CVD or PVD coating technologies with the help of polymerizing plasma and diamond-like coatings are also described in the literature (Dünnschichttechnologie [thin-layer technology], edited by Dr. Hartmut Frey and Dr. Gerhard Kienel, VDI Verlag , Dusseldorf, 1987). These technologies are used here in particular for metals, PC and PMMA. Other commercially available coatings are, for example, Peerguard from Peerless, Clearlite and Filtalite from Charvo, types of coating such as, for example, the UVHC series of GE Silicones, Vuegard such as the 900 Series of Electrical Components TEC, OG Highlink series of the French Society Hoechst, PPZ products sold by Siber Hegner (produced by Idemitsu) and resin coating materials Vianova, Toagoshi, Toshiba or Mitsubishi. These coatings are also described for PC and PMMA. The coating processes known from the literature are, for example, offset printing, pouring on, submerging processes, waterlogging processes, spraying or atomization processes, knife coating or winding. The coatings applied by the processes described herein are cured, for example by means of UV radiation and / or heat. For the coating processes, it may be advantageous to treat the surface to be covered with a scrim layer, for example based on acrylate or acrylic latex, before applying the coating. Other known processes are, for example: CVD processes and vacuum plasma processes, such as, for example, plasma polymerization under vacuum, PVD process, such as vapor spray coating, vaporizer sources heated with resistance or coating by conventional procedures under a high vacuum, such as in the case of conventional metallization. The literature on CVD and PVD is, for example: Moderne Beschichtungsverfahren by H.D.Steffens and. Brandi DGM informationsgesellschaft Verlag Oberursel. Other coatings literature: Thin Film Technology by L. Maissel, R.

Glang, McGraw-Hill, New York (1983). Coating systems that are particularly suitable for the purpose of this invention are systems (1), (2), (4) and (5), with the coating system (4) being particularly preferred. Suitable coating methods are, for example, in addition to pouring, spraying, atomising, submerging and tracing, the spraying process being preferred for the coating system 4. For the coating of the amorphous sheets, Curing with UV radiation and / or at temperatures preferably not exceeding 80 ° C can be carried out, with UV curing being preferred. The coating according to the system (4) has the advantage that there is no crystallization which could cause the clouding to occur. In addition, the coating exhibits excellent adhesion, excellent optical properties and very good resistance to chemicals and does not cause deterioration of the intrinsic color. The scratch-resistant coating thickness is generally between 1 and 50 micrometers. The amorphous sheet, according to the invention, which includes a crystallizable thermoplastic, such as, for example, PET, as the main constituent, has excellent optical and mechanical properties. In this way, when the impact force in accordance with Charpi, (measured in accordance with ISO 179 / lD), is measured on the sheet, no fractures are preferably present. In addition, the impact force aj, according to slot Izod (measured according to ISO 180 / 1A) of the plate is preferably in the range 2.0 to 8.0 kj / m, particularly preferably in the range of 4.0 to 6.0 kj / m. The image distinction of the sheet, which is also called clarity and is determined at an angle of less than 2.5 ° (ASTM D 1003), is preferably more than 95% and particularly preferable more than 96%. The brightness of the surface, measured in accordance with DIN 67530 (measurement angle 20 °), is greater than 110, preferably greater than 120; the transmission of light, measured in accordance with ASTM D 1003, is more than 80%, preferably more than 84%; and the clouding of the sheet, measured in accordance with ASTM D 1003 is less than 15%, preferably less than 11%. Tests of environmental resistance have shown that even afterwards it was shown that even after the UV stabilized sheets, according to the invention, they show that there is no visible yellowing and there is no loss of apparent brightness, as well as no surface defects visible. In addition, the sheet, according to the invention, is very non-flammable and produces non-incendive drops with very little evolution of smoke, so that it is also particularly suitable for interior applications and in the exhibition construction. Furthermore, the sheet according to the invention can be recycled without problems, without contamination of the environment and without loss in mechanical properties, which means that it is suitable, for example, for the production of short-life commercials or some other Advertising articles.

In addition, economic and outstanding thermoforming properties (the properties of vacuum formation and heat formation) were unexpectedly found. Surprisingly, in contrast to the polycarbonate sheets, it is not necessary to pre-dry the sheet, according to the invention, before thermoforming it. For example, polycarbonate sheets must be pre-dried at approximately 125 ° C for 3 to 50 hours before being thermoformed, depending on the thickness of the sheets. Furthermore, the sheet, according to the invention, can be obtained with very low times in the thermoforming cycles and at low temperatures during thermoforming. On the basis of these properties, the shaped articles can be produced economically and with a high sheet productivity, according to the invention, on thermoforming machines of common use. The production of the amorphous sheets, transparent, in multiple layers, according to the invention, which have been treated with one or more additives if appropriate, can be carried out, for example, by means of the already known method of coextrusion in a line of extrusion. In this case, an extruder for plasticizing and producing the core layer and an additional extruder for the cover layer are each connected to an adapter co-extruder. The adapter is constructed in such a way that the melted products which form the cover layers, stabilized for UV, are applied as thin layers adhesively to the molten products forming the core layer. The multilayer fused yarn thus produced is then formed in the lower die and given its size, polished and cooled in the polishing pile, before the sheet is cut to size. The process for the production of these sheets, according to the invention, is described generally below. If necessary, the thermoplastic polymer can be dried before co-extrusion. The drying can conveniently be carried out at temperatures in the range of 110 to 190 ° C for a period of 1 to 7 hours. The main dryer is associated with the main extruder, and, for each layer of cover, there is a dryer associated with a co-extruder. Therefore, the thermoplastics for the core layer or layers and the upper layer or layers are melted in the main extruder and co-extruders. The temperature of the molten material is preferably in the range of 230 to 330 ° C, it being then possible to set the temperature of the molten products essentially as a function of both the temperature of the extruder and the residence time of the molten material in the extruder. If polyethylene terephthalate, which is preferred according to the invention as the thermoplastic, is used, the drying is usually carried out at 160 ° C or up to 180 ° C for 4 to 6 hours and the temperature of the molten product is established in the range of 250 to 320 ° C. If an additive is used, such as a UV stabilizer and / or an antioxidant, it can be introduced initially by the raw material manufacturer or can be introduced to the extruder during the production of the sheet. The addition of additives by means of master batch technology is particularly preferred. In this case, the additives are completely dispersed in a solid carrier material. The possible carrier materials are certain resins, the thermoplastic itself or any other polymer or polymers which are sufficiently compatible with the thermoplastic. It is important that the particle size and the bulk density of the masterbatch are similar to the particle size and bulk density of the thermoplastic, so that the homogeneous distribution and therefore a homogeneous effect of the additives can be obtained, such as for example , UV stabilization and hydrolysis. As mentioned above, the main extruder for production of the core layer and the co-extruder or co-extruders are connected to an adapter co-extruder in such a way that the melted products forming the cover layers are applied as thin layers adhesively to the molten product that goes to form the central layer. The melted multilayer yarn already at this time thus produced is configured in a die connected to the line. This die is preferably a slot die. The multilayer fused wire formed by a slot die is then brought to size by polishing calendar rolls, that is, it is intensively cooled and polished. The rollers used can be accommodated, for example, in a form of I, F, L or S. The material can then be post-cooled on a roller band, brought to the size by cutting on the sides, and cut to the length that is want and stored. The thickness of the resulting sheet is essentially determined by the output, which is positioned at the end of the cooling zone, by the cooling rolls coupled to them in terms of speed, and by the speed of the extruder band or the output speed rather of the extruder on one side and the distance between the rollers by the other. Both single screw extruders or twin screw extruders and the extruder can be used to produce the sheet. The slot die preferably comprises the removable die body, the lips and the restrictor bar for flow regulation across the width. For this, the restrictor bar can be bent by screws that stress and press at the same time. The thickness is determined by adjusting the lips. It is important to ensure that the melted yarn multiple layers and the lip have a uniform temperature, since otherwise the melted yarn flows in different thicknesses through different flow paths. The dimensioning die, that is, the polishing calender roll, gives the melted yarn the shape and the dimensions. This is effected by freezing below the transition temperature of the glass by cooling and polishing. The configuration should not be done any more in this state since otherwise surface defects would be formed due to the cooling that has taken place. For this reason, the calibrator rolls are preferably driven together. The temperature of the calender roll should be lower than the melting temperature of the crystallite in order to prevent the molten material from becoming sticky. The wire preferably leaves the slot die at a temperature of 240 to 300 ° C. The first cooling and polishing roller has a temperature between 50 ° C and 80 ° C, depending on the exit and thickness of the sheet. The second roller a little colder, cools to the second surface or some other surface. To obtain a uniform thickness of range from 1 to 20 mm, with good optical properties, it is essential that the temperature of the first polishing calender roll is between 50 and 80 ° C. While the device for sizing freezes the surfaces of the sheet as smoothly as possible and cools the profiles to the extent that it is dimensionally stable, the post-cooling device reduces the temperature of the sheet to virtually the ambient temperature. The post-cooling can take place on a roller board. The output speed must be precisely coordinated with the speed of the calender rolls properly to avoid defects and variations in thickness. As additional devices, the extrusion line for production of the sheets according to the invention may comprise a separate saw as a device for cutting the sheet to the desired length, the machine equalizing the sides, the packaging unit and a control station . The bent margin equalizer is advantageous, since under certain circumstances the thickness in the region of the margin may be non-uniform. The thickness and visual properties of the sheet are measured at the control station. As a result of the surprisingly large number of surplus properties, the transparent, amorphous sheet according to the invention is suitably appropriately for a large number of diverse uses, for example for interior coating, for display construction and display items, such as counters , for advertisements, in the lighting sector, in the construction of shelves and assortment and arrangement of stores, as advertising items, as menu posts, as basketball tables, as room dividers, as aquariums, as information boards or information boards, such as newspaper stands and brochures, and also for external applications, such as, for example, greenhouses, roof construction, exterior cladding, coatings in general, for applications in the construction sector, for illuminated advertising profiles, for covering balconies and as skylights. The invention is illustrated in more detail in the following with the aid of modeling examples, without being limited by them. The measurement of the individual properties is carried out here according to the following methods or standards or standards.

Measurement methods Surface brightness: The brightness of the surface is determined at a measurement angle of 20 ° according to DIN 67530. The reflector value is measured as the optical parameter for the surface of a sheet. According to the standards ASTM-D 523-78 and ISO 2813 the angle of incidence was placed at 20 ° C under the angle of incidence a radius of light hits the surface to flat test and is reflected or scattered by this, the rays of incident light on the photoelectronic receiver, are indicated as a proportional electrical value. The measurement value has no dimensions and must be indicated next to the angle of incidence.

Transmission of light: The meaning of transmission of light should be understood as the ratio of the total light that is allowed to pass with respect to the amount of incident light. The transmission of light is measured with a "Hazegard plus" measuring instrument in accordance with ASTM D 1003.

Turbidity and clarity: Turbidity is the percentage of the light content, which is allowed to pass through the sheet, which deviates from the incident light beam, on average, more than 2.5 °. The distinction of the image is determined at an angle of less than 2. 5 . Turbidity and clarity are measured with the "Hazegard plus" measuring instrument in accordance with ASTM D 1003.

Surface defects: Defects on the surface are determined visually.

Impact force Charpy an: This value is determined in accordance with ISO 179 / 1D.

Impact force Izo a: The impact force Izo with groove, or resistance towards notching a ^, is measured in accordance with ISO 180 / 1A.

Density: The density is determined in accordance with DIN 53479.

SV (DCA), IV (DCA): Standard viscosity SV (DCA) is measured in dichloroacetic acid according to DIN 53728. Intrinsic viscosity (IV) is calculated as follows from standard viscosity (SV) IV (DCA) ) = 6.67 x 104 SV (DCA) + 0.118 Thermal properties: The thermal properties, such as the melting point of crystallite Tm, the temperature range of crystallization Tc, post-cooling crystallization temperature T ^ c and the glass transition temperature Tg are measured by differential scanning calorimetry (DSC) at a heating rate of 10 ° C / minute.

Polydispersity and molecular weight: The molecular weights Mw and Mn and the resulting polydispersity Mw / Mn are measured by gel permeation chromatography (GPC).

UV stability and external weather on both sides: UV stability is tested as follows according to ISO 4892 test specifications Test apparatus Atlas Ci 65 eather Ometer ISO 4892 test conditions, this is to simulate simulating external weather Irradiation time 1000 hours (per side) Irradiation 0.5 W / m2, 340 nm Temperature 63 ° C Relative atmospheric humidity 50% Lamp Xenon external and internal borosilicate filters are used. Irradiation cycles: 102 minutes with ultraviolet light, then 18 minutes with UV light with water spray in the specimens, then 102 minutes of UV light again and so on.

Change in color: The change in the color of the specimens after they are subjected to simulated climate is measured with a spectrophotometer, according to DIN 5033. The symbols have the following meanings: AL: Difference in clarity. + AL: The specimen is lighter than the standard -AL: The specimen is darker than the standard AA: Difference in the red-green interval + AA: The specimen is redder than the standard -AA: The specimen is greener than the standard AB: Difference in the blue-yellow interval + AB: The specimen is more yellow than the standard -AB: The specimen is more blue than the standard AE: Total change in colorís AE = (AL2 + AA2 + AB2) 1/2 The larger the numerical deviation from the standard, the larger the difference in color will be. Numerical values equal to or less than 0.3 are negligible and means that there is no significant change in color.

Yellow color value: The value of the yellow color Y is the deviation of the lack of color in the yellow direction and is measured according to DIN 6167. Yellow color values AND less than or equal to 5 are not visually detectable. In the following examples and comparison examples, the sheets are in each case transparent sheets of different thickness produced in the extrusion line described.

EXAMPLE 1 A transparent amorphous polyethylene terephthalate sheet, 4 mm thick multiple layers having the sequence of layers A-B-A, is produced by the described coextrusion process, where B represents the core layer and A the cover layer. The central layer B is 3.5 mm thick and the two cover layers, which cover the central layer, are each 250 μm thick. The polyethylene terephthalate used for the base of layer B has the following properties: SV (DCA): 1100 IV (DCA): 0.85 dl / g Density: 1.38 g / cm3 Crystallinity: 44% Cristallite melting point: 245 ° C Crystallization temperature range: 82 ° C to 245 ° C Crystallization temperature after cooling Tfjrj: 152 ° C Polydispersity Mw / Mn: 2.02 Glass transition temperature: 82 ° C The cover layers A comprise polyethylene terephthalate, as the main constituent, and 3% by weight of the UV stabilizer 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-hexyloxyphenol ( RTinuvin 1577 of Ciba-Geigy). Tinuvin 1577 has a melting point of 140 ° C and is stable to heating up to 330 ° C. To ensure a homogeneous distribution, 3% by weight of the UV stabilizer is incorporated into the polyethylene terephthalate directly by the raw material manufacturer. The polyethylene terephthalate from which the cover layers are produced has a standard viscosity SV (DCA) of 1010, which corresponds to an intrinsic viscosity IV (DCA) of 0.79 dl / g. The moisture content is less than 0.2% and the density (DIN 53479) is 1.41 g / cm3. The crystallinity is 59%, the melting point of crystallite according to the measurements of differential scanning calorimetry is 259 ° C. The crystallization temperature range Tc is between 83 ° C and 258 ° C, the post-crystallization temperature (in addition the cold crystallization temperature) ^ c is 144 ° C. The polydispersity Mw / Mn of polyethylene terephthalate is 2.14. The glass transition temperature is 83 ° C. Prior to coextrusion, the polyethylene terephthalate for the core layer and the UV-stabilized polyethylene terephthalate for the cover layers are each dried in a drying oven at 170 ° C for 5 hours and then co-extruded through a slotted to a polishing calendrador, whose rollers are arranged in an S-shape, and polished to form a sheet of three layers of 4 mm thick. The extrusion temperature of the main extruder for the central layer is 282 ° C, the extrusion temperatures of the two co-extruders for the coating layers are 294 ° C, the first heating roller has a temperature of 65 ° C and each one of the subsequent rollers has a temperature of 58 ° C. The output speed is 4.2 m / minute. After post-cooling, the transparent three-layer sheet is matched on the edges with separate closures, and cut to the desired length and stowed. The three-layer, amorphous, transparent, obtained PET film has the following group of properties - sequence of the layers: ABA - total thickness: 4 mm - thickness of the central layer: 3.5 mm thickness of the cover layer: 0.25 mm surface brightness of the first side: 185 surface brightness of the second side 183 with measurement angle at 20 °: light transmission: 93.6% clarity: 100% turbidity: 0.7% surface defect per m: none (orange peel spots, bubbles and similar) impact force Charpy an: no fracture Izod impact strength for good , no clearing a ^: defects crystallinity: 0% density: 1.33 g / cm3After being submitted for 1000 hours per side, with the Atlas Ci 65 eather Ometer, the PET sheet has the following properties: total thickness: 4 mm surface brightness of first side: 166 surface brightness of second side, measured at an angle of 20 °: 164 - light transmission: 91.1% - clarity: 100% - turbidity: 1.2% - total discoloration AE: 0.22 - discoloration to black AL: -0.18 - discoloration red-green AA: -0.08 - discoloration blue-yellow AB: 0.10 - surface defects: none - (cracks or fractures) - yellow Y value: 4 EXAMPLE 2 A transparent three-layer PET film of 4 mm thickness is prepared analogously to Example 1. The core layer B is composed of 50% polyethylene terephthalate of Example 1 and 50% recycled sheet of example 1. The sheet transparent PET obtained has the following properties profile: - total thickness: 4 mm - first side surface brightness: 172 - second side surface brightness measured at 20 ° at an angle of 20 °: 170 light transmission: 92.1% clarity: 99.8% turbidity: 2.0% defect surface by m: none (orange peel spots, bubbles and similar) Impact force Charpy an: no fracture Izod impact strength for a ^ desalting: defects cold forming properties: good, no defects crystallinity: 0% density: 133 g / cm3 After being submitted for 1000 hours with the Atlas Ci 65 Weather Ometer, the PET sheet has the following properties: - total thickness: 4 mm - first side surface brightness: 158 - second side surface brightness measured at 20 ° at an angle of 20 °: 154 - light transmission: 91.1% - clarity: 99.4% - turbidity: 2.9% - total discoloration AE: 0. 24 - discoloration, to black AL: - (3.19 - red-green discoloration AA: - 0.08 - blue-yellow discoloration AB: 0.12 - surface defects: none - yellow Y value: 4 EXAMPLE 3 A transparent, three-layer, 6-mm thick, amorphous sheet is produced analogously to Example 1. The cover layers comprise 3.5% by weight of the UV stabilizer 2, 2"-methylene-bis- (6- (2H-benzotriazole-2 -il) -4- (1, 1, 3, 3-tetramethyl-butyl) phenol (Tinuvin 360 Ciba-Geigy), based on the thermoplastic weight of the cover layers Tinuvin 360 has a melting point of 195 ° C and is stable to heat up to about 250 ° C. As in example 1, 3.5% by weight of the UV stabilizer is directly incorporated into the polyethylene terephthalate by the raw material manufacturer. 59 ° C and the subsequent rollers have a temperature of 51 ° C. The exit velocity is 2.5 m / minute.The transparent PET sheet obtained has the following properties profile: - sequence of the layers: ABA - thickness of the cover layers: 4 mm - thickness of the central layer: 5.2 mm - total thickness: 6 mm - surface brightness of the first side: 165 - surface brightness of the second side: 163 with angle measuring at 20 °: - transmission of light: 89.1% - clarity: 99.6 - turbidity: 2.4; - surface defects per m: none - (orange peel spots, bubbles and similar) - impact strength Charpy an: no fracture - Izod impact force of 4.9 kJ / m2 ranuura aj ^: - cold forming properties: good, without defect - crystallinity: 0% - density: 1.33 g / cm After subjecting the climate for 1000 hours per side with the Atlas Ci 65 Weather Ometer, the PET film has the following properties: - thickness 6 mm brightness of first side surface; 151 second side surface brightness measured at 20 ° at an angle of 20 °: 150 light transmission: 88.3% clarity: 99.5% turbidity: 3. V. Total discoloration AE: 0.56 discoloration to black AL: -0.21 red-green discoloration AA: -0.11 discoloration blue-yellow AB.- +0.51 surface defects: none (fractures and cracks) yellow Y value: EXAMPLE 4 A transparent three-layer PET film is produced analogously to example 1. As in example 3, the cover layers comprise 3.5% by weight of Tínuvin 360 as a UV stabilizer, based on the weight of the thermoplastic of the cover layer , which has been incorporated directly by the manufacturer of the raw material. The polyethylene terephthalate used for the central layer has the following properties: - SV (DCA): 3173 - IV (DCA): 2.23 DL / G - density: 1.34 g / cm - crystallinity: 112% - melting point of crystallinity Tm : 240 ° C - crystallization temperature range Tc: 82 ° C to 240 ° C - cold crystallization temperature after cooling Tcc: 156 ° C - Polydispersity Mw / Mw: 3.66 - glass transition temperature: 82 ° C - Mw: 204 660 g / min - Mn: 55 952 g / mol The polyethylene terephthalate for the cover layers is the same as in example 1. The extrusion temperature is 274 ° C. The first heating roller has a temperature of 50 ° C and the subsequent rollers have a temperature of 45 ° C. The speed of exit and of the calendrical rolls is of 2.4 m / minute. The sheet produced has the following profile of properties: sequence of the layers: ABA thickness of the covering layers: 0.4 mm thickness of the central layer: 5.2 mm total thickness: 6 mm surface brightness of the first side: 162 surface brightness of the second side : 159 with measurement angle at 20 °: light transmission: 89.3% clarity: 99.3 turbidity: 2.2; or surface defects by m: none (orange peel spots, bubbles and the like) impact force Charpy an: no fracture Izod impact force of 5.1 kJ / m2 groove aj: cold forming properties: good, without defect crystallinity: density: 1.33 g / cm3 After being submitted to the climate for 1000 hours with the Atlas Ci 65 Weather Ometer, the PET sheet has the following properties: - thickness 6 mm - surface brightness of first side: 150 surface gloss of second side measured at 20 ° to an angle of 20 °: 149 light transmission: 86.2% clarity: 99.1% turbidity: 3.2; total discolouration AE: 0.47 discoloration to black AL: -0.18 discoloration red-green AA: -0.09 discoloration blue-yellow AB: +0.42 surface defects: none (fractures and cracks) yellow Y value: EXAMPLE OF COMPARISON An amorphous, transparent sheet is produced analogously to Example 1. In contrast to Example 1, the sheet does not use UV stabilizer. The polyethylene terephthalate used, the extrusion parameters, the process parameters, and the temperatures are chosen as in example 1. The transparent, amorphous three-layer sheet produced has the following group of properties: Sequence of the layers: ABA Thickness of the base layer: 3.5 mm Thickness of the cover layers: 0.25 mm Total thickness: 4 mm Surface gloss of the first side: 189 Surface gloss on the second side: 185 measured at an angle of 20 ° Transmission of light: 93.8% Clarity: 100% Turbidity: 0.8S or Surface defects per m: none (spots, orange peel, bubbles and similar) Impact force Charpy an: no fracture Izod impact force with groove 4.6 kJ / m2 cold forming properties: good without defects Crystallinity: 0% Density: 1.33 g / cm3 After submitting the sheet to the climate for 1000 hours per side in the Atlas Ci 65 Weather Ometer, the PET sheet has the following properties: - Total thickness: 4 mm - First side surface brightness: 98 - Surface brightness of the second side: 95 measured at an angle of 20 ° - Light transmission: 79.5% - Clarity: 81.2% - Turbidity: 7.41 - Total discoloration / \ E: 3.41 - Discoloration to black AL: -0.29 - Red-green discoloration / \ A: -0.87 - Blue-yellow discoloration / \ B: +3.29 - Surface defects: fragility (fractures, or fragility) - Y yellow value: 17

Claims (35)

NOVELTY OF THE INVENTION CLAIMS

1. - An amorphous, transparent, multiple layer sheet having a thickness in the range of 1 to 20 mm, which uses a crystallizable thermoplastic as the main constituent, wherein the sheet has a multiple layer construction of at least one core layer and at least one cover layer, the standard viscosity of the thermoplastic contained in the core layer being higher than the standard viscosity of the thermoplastic contained in the cover layer.

2. The sheet according to claim 1, further characterized in that the standard viscosity of the thermoplastic of the core layer, which uses at least one, is in the range of 800 to 5000 and that of the thermoplastic of the cover layer, which comprises at least one, is in the range of 500 to 4500.

3. The sheet according to claim 1 or 2, further characterized in that the sheet has two cover layers and a central layer that is between the layers of the sheet. cover.

4. - The sheet according to any of the preceding claims, further characterized in that at least one or some of the central layers and / or cover is treated with at least one UV stabilizer.

5. - The sheet according to claim 4, further characterized in that the concentration of the UV stabilizer in one layer is 0.01 to 8% by weight, based on the weight of the thermoplastic of the layer using the UV stabilizer.

6. - The sheet in accordance with the claims 4 or 5, further characterized in that the concentration of the UV stabilizer in the central layer, which comprises at least one, is 0.01 to 1% by weight, based on the weight of the thermoplastic of the core layer using the UV stabilizer.

7. - The sheet according to one of claims 4 to 6, further characterized in that the UV stabilizer is chosen from 2-hydroxybenzotriazoles, triazines and mixtures thereof.

8. - The sheet according to claim 7, further characterized in that the UV stabilizer is chosen from 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5- (hexyl) ) oxyphenol and 2,2'-methylenebis (6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethyl-butyl) phenol

9. - The film according to one of the previous claims, further characterized in that at least one of the cover and / or central layers is treated with at least one antioxidant

10. The sheet according to claim 9, further characterized in that the antioxidant is present in a concentration of 0.1% to 6% by weight, based on the weight of the thermoplastic of the layer treated with this antioxidant

11. The sheet according to claims 9 or 10, further characterized in that the antioxidant, of which at least one is used, is selected from sterically hindered phenols, secondary aromatic amines, phosphites, phosphonites, thioethers, carbodiimides and zinc utildithiocarbamate.

12. - The sheet according to claim 11, further characterized in that the antioxidant is 2- [2,4,8,10-tetrakis (1,1-dimethylethyl) dibenzo [d, f] [1,3,2] dioxa-phosphepin-6-yl] oxy) -ethyl] ethanamine and / or tris (2,4-tert-butylphenyl) phosphite.

13. - The sheet according to one of the preceding claims, further characterized in that the crystallizable thermoplastic is chosen from polyalkene terephthalate with an alkylene radical Cl to C12, a polyalkylene naphthalate with an alkylene radical Cl to C12, a polymer of cycloolefin and a cycloolefin copolymer.

14. The sheet according to claim 13, wherein the alkylene radical is ethylene or butylene.

15. The sheet in accordance with the claim 13, where the thermoplastic is polyethylene terephthalate.

16. The sheet according to any of claims 13 to 15, wherein the thermoplastic material is recycled from the thermoplastic.

17. The sheet according to one of the preceding claims, further characterized in that the thermoplastic has a crystallite melting point, as measured by differential scanning calorimetry with a heating rate of 10 ° C / minute, in the range of 220 to 280 ° C.

18. The sheet of conformity in one of the preceding claims, further characterized in that the thermoplastic has a crystallization temperature, measured by differential scanning calorimetry with a heating rate of 10 ° C / minute, in the range of 75 to 280. ° C.

19. The sheet according to one of the preceding claims, further characterized in that the thermoplastic used has a crystallinity which is in the range of 5 to 65.

20. The sheet according to one of the preceding claims, wherein the The thermoplastic used has a temperature of cold crystallization or post-cooling T ^ c in a range of 120 to 158 ° C.

21. The sheet according to one of the preceding claims, further characterized in that the sheet has a surface brightness, measured in accordance with DIN 67530 (with a measurement angle of 20 °), greater than 110.

22. - The Sheet according to one of the preceding claims, further characterized in that the sheet has a light transmission, measured according to ASTM D 1003, of more than 80%.

23. The sheet according to one of the preceding claims, further characterized in that the turbidity of the sheet, measured according to ASTM D 1003, is less than 15%.

24. - The sheet according to one of the preceding claims, further characterized in that no fracture occurs during measurements of the Charpy an impact force, measured in accordance with ISO 179 / lD. 25.- The sheet according to one of the preceding claims, further characterized in that the sheet has an Izod impact force with slot a ^ -, measured in accordance with ISO 150 / lA, in the range of 2.0 to 8.0 kJ / m2. 26. The sheet according to one of the preceding claims, further characterized in that the sheet has an image distinction which, measured according to ASTM D 1003 at an angle of less than 2.5%, is greater than 95%. 27. The sheet according to one of the preceding claims, further characterized in that the sheet has a scratch-resistant coating on at least one side. 28. The sheet according to claim 27, further characterized in that the scratch-resistant coating uses silicone and / or acrylic. 29. A process for the production of an amorphous sheet, transparent, multiple layers according to one of the preceding claims, further characterized in that the thermoplastic for the central layer, which is used at least one, is a main extruder, and the thermoplastic for the cover layer of which at least one is comprised, are cast in a coextruder, the melted products are layered one on top of the other and the layers put together are formed through a die and then brought to the size, polished and cooled in a polishing shelf having at least two rollers, the temperature of the first roller of the polishing shelf being in the range of 50 to 80 ° C. 30. The process according to claim 29, further characterized in that at least one additive is melted together with the thermoplastic of the layer to be treated with the additive. 31. The process according to claim 29 or 30, further characterized in that the thermoplastic is a polyalkylene terephthalate or a polyalkylene naphthalate. 32. The process according to claim 31, further characterized in that the polyalkylene terephthalate or the polyalkylene naphthalate is dried at 160 or 180 ° C for 4 to 6 hours before extrusion. 33. The process according to either claim 31 and 32, further characterized in that the melting temperature of the polyalkylene terephthalate or polyalkylene naphthalate is in the range of 250 to 320 ° C. 34.- The method according to one of claims 29 to 33, further characterized in that the additive, of which at least one is present, is added via masterbatch technology. 35.- The use of an amorphous sheet, transparent, multiple layers, according to one of the preceding claims for the exterior and interior sector.