CA2261716A1

CA2261716A1 - Multilayered, transparent coloured plate made of a crystallising thermoplastic material, process for producing the same and its use

Info

Publication number: CA2261716A1
Application number: CA002261716A
Authority: CA
Inventors: Ursula Murschall; Rainer Brunow
Original assignee: Individual
Current assignee: Aventis Research and Technologies GmbH and Co KG
Priority date: 1996-07-31
Filing date: 1997-07-18
Publication date: 1998-02-12
Also published as: WO1998005498A1; AU3768197A; EP0915757A1; DE19630598A1

Abstract

A multilayered, transparent coloured amorphous plate with 1 to 20 mm thickness contains a crystallising thermoplastic material as its main component and a dye which is soluble in the thermoplastic material. The plate consists of at least one covering layer and at least one core layer, the standard viscosity of the thermoplastic material of which the core layer is made being higher than that of the thermoplastic material of the adjacent covering layer(s).

Description

WO 98/05498 ~ ~ PCT/EP97/03854 Multilayered, transparently colored sheet of a crystallizable thermoplastic, a process for its production and its use The invention relates to an amorphous, transparently colored multilayered sheet of a crystallizable thermoplastic, the thickness of which is in the range from 1 to 20 mm. The invention furthermore relates to a process for 10 the production of this sheet and its use.

Multilayered sheets of plastics materials are known per se.

Such sheets of branched polycarbonates are described in EP-A-0 247 480, EP-A-320 632 and US-PS 5,108,835.

UV-stabilized polycarbonate shaped articles which are built up from polydiorganosiloxane-polycarbonate block copolymers are known from DE-A-34 14 116 and US-A 4,600,632.
Multilayered sheets of plastic with layers of polydiorganosiloxane-polycarbonate block copolymers which comprise UV absorbers are known from US-A 5,137,949. UV-stabilized, branched polycarbonates from specific diphenols are known from EP-A-0 416 404. It is mentioned that 25 such polycarbonates can be employed for the production of sheets or webbed multiple sheets.

All these sheets are made of polycarbonate, an amorphous thermoplastic which cannot be crystallized. Polycarbonate sheets have the disadvantage 30 that they often lead to blooming in the form of white specks and surface deposits, especially in the UV-stabilized embodiment (cf. EP-A-0 649 724).
According to EP-A-0 649 724, for example, evaporating out of the UV
absorber is linked to a high degree to the average molecular weight.

35 These PC plates furthermore are readily flammable and therefore require the addition of flameproofing agents so that they can be employed for certain purposes, such as for interior applications. Tedious predrying times and relatively long processing times at high temperatures are necessary for further processing of these sheets to moldings. Devolatilizing extruders 5 must furthermore be used during sheet production for the purpose of withdrawing moisture, which means that the additives added to the raw material can also be removed at the same time, especially if low molecular weight, relatively volatile additives are employed.

10 Single-layered, transparently colored amorphous sheets having a thickness in the range from 1 to 20 mm which comprise a crystallizable thermoplastic, such as, for example, polyethylene terephthalate, as the main constituent, and at least one dyestuff which is soluble in this thermoplastic have already been described by the Applicant (German Patent Applications Nos.19519578.7,19522120.6 and 19528334.1 ~
WO 96/38498). These sheets can have a standard viscosity of 800-6000 and comprise a UV stabilizer. It goes without saying that the sheets, starting substances, additives and processes described there can in principle also be employed for the present invention, so that by citation, 20 these Applications belong to the disclosure content of the present Application.
EP-A-0 471 528 describes a process for shaping an object from a polyethylene terephthalate (PET) sheet. The PET sheet is heat-treated on both sides in a thermoforming mold in a temperature range between the 25 glass transition temperature and the melting temperature. The shaped PET
sheet is removed from the mold when the extent of crystallization of the shaped PET sheet is in the range from 25 to 50%. The PET sheets disclosed 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 partly 30 crystalline and therefore no longer transparent and the surface properties of the shaped article are determined by the thermoforming process and the temperatures and shapes given by this, the optical properties (for example AMENDED SHEET

.

2a gloss, clouding and light transmission) of the PET sheets employed are unimportant. As a rule, AMENDED SHEET

2b lh'e addl~tion of ~l~r~ r~,ofin~ aqents so that they can ho~-~llployed for ~
certain purposes, such as for interior applications. Tedious predryingJ~mes and relatively long processing times at high temperatures are nece~sary for further processing of these sheets to moldings. Devolatilizing ex~Gders 5 must furthermore be used during sheet production for the pur~6se of withdrawing moisture, which means that the additives addest~o the raw material can also be removed at the same time, especialJ~if low molecular weight, relatively volatile additives are employed.

10 Single-layered, transparently colored amorphous 7(eets having a thickness in the range from 1 to 20 mm which comprise a~fystallizable thermoplastic, such as, for example, polyethyl~he terephthalate, as the main constituent, and at least one dyestuff ~ich is soluble in this thermoplastic have already been describe,~by the Applicant (German Patent Applications Nos.19519578.7,1,~522120.6 and 19528334.1).
These sheets can have a standard vis,~'osity of 800-6000 and comprise a UV stabilizer. It goes without sayingJ~at the sheets, starting substances, additives and processes described~here can in principle also be employed for the present invention, so that~y citation, these Applications belong to 20 the disclosure content of the ps~sent Application.

EP-A-0 471 528 describes~2~ process for shaping an object from a polyethylene terephthala~ (PET) sheet. The PET sheet is heat-treated on both sides in a thermoffZlrrming mold in a temperature range between the 25 glass transition temp~!rature and the melting temperature. The shaped PET
sheet is removed f,~6m the mold when the extent of crystallization of the shaped PET shett is in the range from 25 to 50%. The PET sheets disclosed in EJ~A-0 471 528 have a thickness of 1 to 10 mm. Since the thermoform~/d shaped article produced from this PET sheet is partly 30 crystallin~and therefore no longer transparent and the surface properties of the ~aped article are determined by the thermoforming process and the temp~ratures and shapes given by this, the optical properties (for example gl~s, clouding and light transmission) of the PET sheets employed are ~'nirnport~nt. As Q rulo, phe optical properties of these sheets are poor and in need of optimization. These polyethylene terephthalate sheets also have a single-layer construction and are not colored.

US-A-3 496 143 describes vacuum thermoforming a 3 mm thick PET
5 sheet, the crystallization of which should be in the range from 5 to 25%.
The crystallinity of the thermoformed shaped article is greater than 25%.
On these PET sheets also, no requirements are imposed in respect of optical properties. Since the crystallinity of the sheets employed is already between 5% and 25%, these sheets are cloudy and nontransparent. These 10 partly crystalline PET sheets are also single-layered.

Austrian Patent Specification No. 304 086 describes a process for the production of transparent shaped articles by the thermoforming process, a PET sheet or film having a degree of crystallinity of less than 5% being 15 employed as the starting material.
The sheet or film used as the starting material has been produced from a PET having a crystallization temperature of at least 1 60~C. From this relatively high crystallization temperature it follows that the PET here is not a PET homopolymer but a glycol-modified PET, called PET-G for short, 20 which is a PET copolymer.
In contrast to pure PET, PET-G shows an extremely low tendency toward crystallization and is usually present in the amorphous state because of the glycol units additionally incorporated.

25 The object of the present invention is to provide a multilayered, amorphous, transparently colored sheet having a thickness of 1 to 20 mm which is distinguished by good mechanical and optical properties.

Good optical properties include, for example, a high light transmission, a 30 high surface gloss, an extremely low clouding and a high image sharpness (clarity).

Tl,o ~ m~~hG"j~;al properties in~u~, int~r ~ hig~ impact 3trcny.h ~n-l ~ high fr~cturc ~t~ ylh.

3 c~

30 The good mechanical properties include, inter alia, a high impact strength and a high fracture strength.

AMENDED SHEET

- Furthermore, the sheet according to the invention should be recyclable, in particular without loss of the mechanical properties, and poorly combustible, so that, for example, it can also be used for interior applications and in exhibition construction.

This object is achieved by a multilayered, transparently colored amorphous sheet having a thickness of 1 to 20 mm, which comprises a crystallizable thermoplastic as the main constituent, wherein the sheet has at least one core layer and at least one covering layer, wherein the standard viscosity, measured in dichloroacetic acid according to DIN 53728, of the crystallizable thermoplastic of the core layer is higher than the standard viscosity of the thermoplastic of the covering layer, and wherein at least one layer of the sheet comprises at least one dyestuff which is soluble in the thermoplastic of this layer.
15 Amorphous sheet in the context of the present invention is understood as meaning those sheets which are noncrystalline, although the crystallizable thermoplastic employed has a crystallinity of between 5 and 65%.
Noncrystalline, i.e. essentially amorphous, means that the degree of crystallinity is in general below 5%, preferably below 2%, and particularly 20 preferably is 0%, and that the sheet essentially shows no orientation.
According to the invention, crystallizable thermoplastic is understood as meaning - crystallizable homopolymers, - crystallizable copolymers, 25 - crystallizable compounds, - crystallizable recycled material and - other variations of crystallizable thermoplastics.

Examples of suitable thermoplastics are polyalkylene terephthalates with a 30 C1 to C12-alkylene radical, such as polyethylene terephthalate and polybutylene terephthalate, AMENDED SHEET

4C~
~Fu~ ml~re, Ihe sheet according to tF~e invention s~ourd be~r~ecy'c~a~le~h particular without loss of the mechanical properties, and poorly combustible, so that, for example, it can also be used for interior~
applications and in exhibition construction.
This object is achieved by a multilayered, transparently cf~iored amorphous sheet having a thickness of 1 to 20 mm, which compr7~s a crystallizable thermoplastic as the main constituent, wherein the~eet has at least one core layer and at least one covering layer, wherej~the standard viscosity 10 of the crystallizable thermoplastic of the core ~Çer is higher than the standard viscosity of the thermoplastic of th~fcovering layer, and wherein at least one layer of the sheet comprises~least one dyestuff which is soluble in the thermoplastic of this laye~

15 Amorphous sheet in the context of ~Fe present invention is understood as meaning those sheets which are,~Foncrystalline, although the crystallizable thermoplastic employed has astFystallinity of between 5 and 65%.
Noncrystalline, i.e. essentiall~amorphous, means that the degree of c~stallinity is in general be~bw 5%, preferably below 2%, and particularly 20 preferably is 0%, and tha~)~the sheet essentially shows no orientation.

According to the inv7~tion, crystallizable thermoplastic is understood as meanlng ~,~
- crystalliza,p~e homopolymers, 25 - crystalli,7fable copolymers, - cryst~Çzable compounds, - cry~(allizable recycled material and - ~er variations of crystallizable thermoplastics.
/

30 Ex~ples of suitable thermoplastics are polyalkylene terephthalates with a C~( to C1 2-alkylene radical, such as polyethylene terephthalate and /polyhutylenP tPrP~r~hthal~ts,¦polyalkylene naphthalate with a C1 to C12-alkylene radical, and crystallizable cycloolefin polymers and cycloolefin copolymers, it being possible for the thermoplastic or thermoplastics for the core layer(s) and the thermoplastic or thermoplastics for the covering layer(s) to be identical or different.

It has been found that a polyolefin is also suitable for the covering layer.

Thermoplastics having a crystallite melting point T", measured by DSC
(differential scanning calorimetry) with a heating-up rate of 10~C/minute, of 220~C to 260~C, preferably 230~C to 250~C, a crystallization temperature range Tc of between 75~C and 260~C, a glass transition temperature Tg of between 65~C and 90~C and a density, measured in accordance with DIN
53479, of 1.30 to 1.45 g/cm3 and a crystallinity of between 5% and 65%
are preferred polymers for the core layer and the covering layer as starting materials for production of the sheet.
A thermoplastic having a cold (after-)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/dm3 and 1.0 kg/dm3, and particularly preferably between 0.80 kg/dm3 and 0.90 kg/dm3.

The polydispersity M,r/Mn of the thermoplastic, measured by means of GPC, is preferably between 1.5 and 6.0, and particularly preferably between 2.0 and 5Ø
A particularly preferred crystallizable thermoplastic for the core layer(s) and the covering layer(s) is polyethylene terephthalate. The polyethylene terephthalate preferably used according to the invention essentially comprises monomer units of the following formula O O
EC H2 - C H2 - O C ~ C O 3 CA 0226l7l6 l999-0l-29 It is essential to the invention that the thermoplastic or thermoplastics of the core layer(s) has or have a higher standard viscosity than the thermoplastic or thermoplastics of the covering layer(s). The standard viscosities of the thermoplastics of various core and/or covering layers of a 5 multilayered sheet can differ.
The standard viscosity SV (DCA) of the crystallizable thermoplastic of the core layer, measured in dichloroacetic acid in accordance with DIN 53728, is preferably between 800 and 5000, and particularly preferably between 1000 and 4500.
The standard viscosity SV (DCA) of the crystallizable thermoplastic of the covering layer, measured in dichloroacetic acid in accordance with DIN
53728, is preferably between 500 and 4500, and particularly preferably 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 10-4 SV (DCA) + 0.118 The crystallizable thermoplastics used according to the invention can be obtained by customary processes known to the expert. In general, thermoplastics such as are used according to the invention can be obtained by polycondensation in the melt or by a two-stage 25 polycondensation. The first step here is carried out up to a moderate molecular weight - corresponding to a moderate intrinsic viscosity IV of about 0.5 to 0.7 - in the melt, and the further condensation is carried out by means of solid condensation. The polycondensation is usually carried out in the presence of known polycondensation catalysts or catalyst systems.
30 In the solid condensation, chips of the thermoplastic are heated at temperatures in the range from 180 to 320~C under reduced pressure or under an inert gas until the desired molecular weight is reached.

AMENDED SHEET

For example, the preparation of polyethylene terephthalate, 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 particularly high molecular weights can be prepared, for example, by polycondensation of dicarboxylic acid-diol 10 precondensates (oligomers) at elevated temperature in a liquid heat transfer medium in the presence of customary polycondensation catalysts and, if appropriate, cocondensable modifying agents, if the liquid heat transfer medium is inert and free from aromatic structural groups and has a boiling point in the range from 200 to 320~C, the weight ratio of the 15 dicarboxylic acid-diol precondensate (oligomer) employed to the liquid heat transfer medium is in the range from 20:80 to 80:20, and the polycondensation is carried out in a boiling reaction mixture in the presence of a dispersion stabilizer.

20 It is essential to the invention that the amorphous, multilayered sheet comprises at least one dyestuff which is soluble in the thermoplastic in at least one of the layers. The concentration of the soluble dyestuff is preferably in the range from 0.001 % by weight to 20% by weight, based on the weight of the thermoplastic of the layer treated with this.
Soluble dyestuffs are understood as meaning substances which are dissolved in the molecular state in the polymer (DIN 55949).

The change in color as a consequence of the coloration of the amorphous 30 sheet is based on the wavelength-dependent absorption and/or scattering of the light. Dyestuffs can only absorb and not scatter light, since the physical prerequisite for scattering is a certain minimum particle size.

Coloration with dyestuffs is a solution process. As a result of this solution process, the dyestuff is dissolved in the molecular state, for example in the PET polymer. Such colorations are described as transparent or diaphanous or translucent or opal.

Of the various classes of soluble dyestuffs, the dyestuffs which are soluble in fats and aromatic substances are particularly preferred. These are, for example, azo and anthraquinone dyestuffs. They are particularly suitable for coloring PET, since the migration of the dyestuff is limited due to the high glass transition temperature of PET.
10 (Literature J. Koerner: Losliche Farbstoffe in der Kunststoffindustrie [Soluble dyestuffs in the plastics industry] in VDI-Gesellschaft Kunststofftechnik: Einfarben von Kunststoffen [Coloring of plastics], VDI-Verlag, Dusseldorf 1975).

15 Suitable soluble dyestuffs are, for example: Solvent Yellow 93, a pyrazolone derivative, Solvent Yellow 16, a fat-soluble azo dyestuff, Fluorol Green Gold, a fluorescent polycyclic dyestuff, Solvent Red 1, an azo dyesfuff, azo dyestuffs such as Thermoplastic Red BS, Sudan Red BB and Solvent Red 138, an anthraquinone derivative, fluorescent benzopyran 20 dyestuffs, such as Fluorol Red GK and Fluorol Orange GK, Solvent Blue 35, an anthraquinone dyestuff, Solvent Blue, a phthalocyanine dyestuff, and many others.
Mixtures of two or more of these soluble dyestuffs are also suitable.
The multilayered, transparently colored, amorphous sheet according to the 25 invention can furthermore be treated with further suitable additives, if desired. These additives can be added individually or as a mixture to one or more layers of the sheet, as required. These additives can also be admixed to the layer(s) with the dyestuff. Examples of such additives are UV stabilizers and antioxidants, such as are described in German Patent 30 Application No. 195 221 20.6 (WO 96/38498) and the Application by the same Applicant, pending at the same time, entitled 'Polyethylene terephthalate sheet of improved stability to hydrolysis'. By citation, these AMENDED SHEET

., app ca~ ons are va d i /

AMENDED SHEET

9~
~iJ-tio." t"csc Q~ ;cahull~ dlt~ vdh~ ~S a constituent of the disclosure content of the present Application.

As stated above, the multilayered, transparently colored, amorphous 5 sheets can additionally comprise at least one UV stabilizer as a light stabilizer in the covering layer(s) and/or the core layer(s).

Light, in particular the ultraviolet portion of solar radiation, i.e. the wavelength range from 280 to 400 nm, initiates degradation processes in 10 thermoplastics, as a consequence of which not only does the visual appearance change, owing to a change in color or yellowing, but also the mechanical-physical properties are adversely influenced.

Inhibition of these photooxidative degradation processes is of considerable 15 industrial and economic importance, since otherwise the possible uses of numerous thermoplastics are limited drastically.

A high UV stability means that the sheet is not damaged or is damaged only extremely little by sunlight or other UV radiation, so that the sheet is 20 suitable for exterior applications and/or critical interior applications, and shows little or no yellowing even after several years of external use.

Polyethylene terephthalates, for example, already start to absorb UV light below 360 nm, and their absorption increases considerably below 320 nm 25 and is very pronounced below 300 nm. The maximum absorption is between 280 and 300 nm.

In the presence of oxygen, chiefly chain splitting reactions but no crosslinking reactions are observed here. Carbon monoxide, carbon 30 dioxide and carboxylic acids are the predominant photooxidation products in terms of amount. In addition to direct photolysis of the ester groups, oxidation reactions which likewise result in the formation of carbon dioxide via peroxide radicals must also be taken into consideration.
The photooxidation of polyethylene terephthalates can also lead, via elimination of hydrogen in the a-position of the ester groups, to hydroperoxides and decomposition products thereof and to associated chain scission reactions (H. Day, D. M. Wiles: J. Appl. Polym. Sci 16, 1972, page 203).

UV stabilizers, also called light stabilizers or UV absorbers, are chemical compounds which can intervene in the physical and chemical processes of light-induced degradation.

10 Certain pigments, such as, for example, carbon black, can also partly have the effect of light protection. However, these substances are unsuitable for the transparently colored sheets according to the invention, since they lead to discoloration or a change in color. Only those UV stabilizers, for example, from the class of organic and organometallic compounds which 15 cause very little or no color or change in color in the thermoplastic to be stabilized are expediently used for amorphous sheets.

Examples of UV stabilizers which are suitable for the present invention are 2-hydroxybenzophenones, 2-hydroxybenzotriazoles, organonickel 20 compounds, salicylic acid esters, cinnamic acid ester derivatives, resorcinol monobenzoates, oxalic acid anilides, hydroxybenzoic acid esters, sterically hindered amines and triazines, 2-hydroxybenzotriazoles and triazines being preferred.
Mixtures of several UV stabilizers can also be employed.
The UV stabilizer is expediently present in a layer in a concentration of 0.01% by weight to 8% by weight based on the weight of the thermoplastic in the layer treated with the stabilizer.

30 However, if the UV stabilizer is added to a core layer, a concentration of 0.01% by weight to 1% by weight, based on the weight of the thermoplastic in the core layer treated with the stabilizer, is in general sufficient.
According to the invention, several layers can be treated simultaneously with UV stabilizer. In general, however, it is sufficient for the layer on which the UV radiation impinges to be treated.

The core layer(s) can be treated in order to prevent UV radiation impairing the underlying core layer in the event of possible damage to the covering 5 layer.

In a particularly preferred embodiment, the transparently colored, amorphous sheet according to the invention comprises, as the main constituent, a crystallizable polyethylene terephthalate for the core layer and covering layer and 0.01% by weight to 8.0% by weight of 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-(hexyl)oxyphenol or 0.01% by weight to 8.0%
by weight of 2,2'-methylenebis(6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol in the covering layer.

15 The sheet according to the invention can also be treated with at least one antioxidant.
Antioxidants are chemical compounds which can delay the oxidation and hydrolysis phenomena and the resulting aging.

20 Antioxidants which are suitable for the sheet according to the invention can be classified as follows:

Additive group Substance class primary antioxidants sterically hindered phenols and/or secondary aromatic amines secondary antioxidants phosphites and phosphonites, thioethers, carbodiimides, zinc dibutyl-dithiocarbamate In a preferred embodiment, the amorphous sheet according to the invention comprises a phosphite and/or a phosphonite and/or a carbodiimide as a hydrolysis and oxidation stabilizer.
Examples of antioxidants used according to the invention are 2-[(2,4,8,10-tetrakis(1 ,1 -dimethylethyl)dibenzo[d,f][1 ,3,2]dioxaphosphepin-6-yl]oxy)-ethyl]ethanamine and tris(2,4-di-tert-butylphenyl) phosphite.

The antioxidant is usually present in a concentration of 0.01 to 6% by5 weight, based on the weight of the thermoplastic of the layer treated with this.

Mixtures of primary and secondary antioxidants and/or mixtures of secondary and/or primary antioxidants with UV stabilizers can furthermore 10 be used. It has been found, surprisingly, that such mixtures show a synergistic effect.

The thickness of the multilayered sheet according to the invention varies between 1 mm and 20 mm, it being possible for the thickness of the 15 covering layer(s) to be between 10 ,um and 1 mm, depending on the sheet thickness. The covering layers preferably each have a thickness of between 400 and 500 ,um.

As already stated, the sheet according to the invention can have several 20 core and covering layers which are laid one on top of the other like a sandwich. However, the sheet can also consist of only one covering layer and one core layer.

A structure having two covering layers and a core layer Iying between the 25 covering layers is particularly preferred according to the invention.

The individual covering and core layers can comprise different or identical crystallizable thermoplastics as the main constituents, as long as the thermoplastic of a core layer has a higher standard viscosity than the 30 thermoplastic of the covering layers directly adjacent to this core layer.

If desired, the transparently colored, amorphous, multilayered sheet according to the invention can be provided with a scratch-resistant surface on one or more sides.

Possible coating systems and materials for the scratch-resistant surface (coating) are all the systems and materials known to the expert.
Suitable coating systems and materials are described, in particular, in German Patent Application No.196 255 34.1 of the Applicant, to the full 5 content of which reference is made for the present invention.

From the large number of possible coating systems and materials, some are mentioned as examples below.

(1) US-A-4822828 discloses aqueous, radiation-curable coating compositions which comprise, 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, so-called ormocers (organically modified ceramics), which comblne the properties of ceramic materials and polymers, are also known. Ormocers are employed, in particular, as hard and/or scratch-resistant coatings on polymethyl methacrylate (PMMA) and 20 polycarbonate (PC). The hard coatings are bonded on the basis of Al2O3, ZrO2, TiO2 or SiO2 as network formers and epoxide or methacrylate groups with Si by -Si-C-- compounds.

(3) Coating compositions for acrylic resin plastics and polycarbonate 25 based on silicone resins in aqueous-organic solution which have a particularly 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 coating compositions, above all for glass, and in particular for acrylic resin plastics and PC.

(4) Acrylic-containing coatings are also known, such as, for example, the Uvecryl coatings from UCB Chemicals. One example is Uvecryl 29203, which is cured with UV light. This material comprises a mixture of urethane acrylate oligomers with monomers and additives. Constituents are about 81% of acrylate oligomer and 19% of hexanediol diacrylate. These coatings are likewise described for PC and PMMA.

(5) CVD or PVD coating technologies with the aid of a polymerizing 5 plasma and diamond-like coatings are also described in the literature (Dunnschichttechnologie [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.

10 Other commercially obtainable coatings are, for example, Peeraguard from Peerless, Clearlite and Filtalite from Charvo, coating types such as, for example, the UVHC series from GE Silicones, Vuegard such as the 900 series from TEC Electrical Components, Highlink OG series from Société
Francaise Hoechst, PPZ~ products marketed by Siber Hegner (produced 15 by Idemitsu) and coating materials from Vianova Resins, Toagoshi, Toshiba or Mitsubishi. These coatings are also described for PC and PMMA.

Coating processes known from the literature are, for example, offset 20 printing, casting, dipping processes, flow coating processes, spray processes or atomizing processes, knife-coating or rolling.

Coatings applied by the processes supplied are then cured, for example by means of UV radiation and/or heat. For the coating processes, it may be 25 advantageous to treat the surface to be coated with a primer, for example based on acrylate or an acrylic latex, before application of the coating.

Other known processes are, for example:
CVD processes and vacuum plasma processes, such as, for example, 30 vacuum plasma polymerization, PVD processes, such as coating with electron beam vaporization, resistance-heated vaporizer sources or coating by conventional processes under a high vacuum, such as in the case of a conventional metallization.

Literature on CVD and PVD is, for example: Moderne Beschichtungsverfahren [Modern coating processes] by H.-D. Steffens and W. Brandl. DGM Informationsgesellschaft Verlag Oberursel. Other literature on coatings: Thin Film Technology by L. Maissel, R. Glang, 5 McG raw-Hill, New York ( 1 983) .

Coating systems which are particularly suitable for the purposes of the present invention are systems (1), (2), (4) and (5), coating system (4) being particularly preferred.
Suitable coating processes are, for example, also the casting, the spraying, the atomizing, the dipping and the offset process, the atomizing process being preferred for coating system (4).

15 For coating the amorphous, crystallizable sheets, curing with UV radiation and/or at temperatures which preferably do not exceed 80~C can be carried out, UV curing being preferred.

The coating according to system (4) has the advantage that no 20 crystallization which could cause clouding occurs. Furthermore, the coating shows an outstanding adhesion, outstanding optical properties and a very good resistance to chemicals and causes no impairment of the intrinsic color.

25 The thickness of the scratch-resistant coating is in general between 1 and 50 lum.

The amorphous sheet according to the invention, which comprises a crystallizable thermoplastic, such as, for example, PET, as the main 30 constituent, has outstanding mechanical and optical properties. Thus, when the impact strength an according to Charpy (measured in accordance with ISO 179/1 D) is measured on the sheet, preferably no fracture occurs.
Furthermore, the notched impact strength ak according to Izod (measured in accordance with ISO 180/1 A) of the sheet is preferably in the range from 2.0 to 8.0 kJ/m2, particularly preferably in the range from 4.0 to 6.0 kJ/m2.

The image sharpness of the sheet, which is also called clarity and is determined under an angle of less than 2.5~ (ASTM D 1003), is preferably 5 more than 83%, and particularly preferably more than 84%.

The surface gloss, measured in accordance with DIN 67530 (measurement angle 20~), is greater than 100, preferably greater than 110, the light transmission, measured in accordance with ASTM D 1003, is in general between 5 and 90%, preferably between 10 and 80%, and the clouding of the sheet, measured in accordance with ASTM D 1003, is in the range from 2 to 50, preferably 10 - 35%.

Weathering tests have shown that, even after 5 to 7 years of exterior use, 15 the UV-stabilized sheet according to the invention shows no visible yellowing and no visible loss of gloss, as well as no visible surface defects.

Furthermore, the sheet according to the invention is poorly flammable and produces non-burning drips with very little evolution of smoke, so that it is 20 also particularly suitable for interior applications and in exhibition construction.

The sheet according to the invention furthermore can recycled without problems, without pollution of the environment and without loss in the 25 mechanical properties, which means that it is suitable, for example, for the production of short-lived advertising signs or other advertising articles.

Outstanding and economical thermoforming properties (heat forming and vacuum forming properties) have in addition completely unexpectedly been 30 found. Surprisingly, in contrast to polycarbonate sheets, it is not necessaryto predry the sheet according to the invention before thermoforming. For example, polycarbonate sheets must be predried at about 125~C for 3 to 50 hours before thermoforming, depending on the sheet thickness.

Furthermore, the sheet according to the invention can be obtained with very low thermoforming cycle times and at low temperatures during the thermoforming. On the basis of these properties, shaped articles can be produced economically and with a high productivity from the sheet 5 according to the invention on customary thermoforming machines.

The production of the multilayered, transparently colored, amorphous sheets according to the invention can be carried out, for example, by the coextrusion process known per se in an extrusion line.
Coextrusion as such is known from the literature (cf., for example, EP-110 221 and EP-110 238).

In this case, an extruder for plasticizing and producing the core layer and a 15 further extruder per covering layer are each connected to a coextruder adapter. The adapter is constructed such that the melts which form the covering layers are applied as thin layers adhesively to the melt of the core layer. The multilayered melt strand thus produced is then shaped in the downstream die and sized, polished and cooled in the polishing stack, 20 before the sheet is cut to size.

The process for the production of the sheets according to the invention is described generally below.

25 If necessary, the thermoplastic polymer can be dried before the coextrusion.
Drying can expediently be carried out at temperatures in the range from 110 to 1 90~C over a period of 1 to 7 hours. The main drier is connected to the main extruder, and, per covering layer, one drier is connected to a 30 coextruder.

Thereafter, the thermoplastic or the thermoplastics for the core layer(s) and the covering layer(s) are melted in the main extruder and in the coextruders. The temperature of the melt is preferably in the range from 230 to 330~C, it then being possible for the temperature of the melt to be established essentially both by the temperature of the extruder and by the residence time of the melt in the extruder.

If polyethylene terephthalate, which is preferred according to the invention as the thermoplastic, is used, drying is usually carried out at 160 to 1 80~C
for 4 to 6 hours and the temperature of the melt is established in the range from 250 to 320~C.

10 The dyestuff and, if appropriate, the additives, such as a UV stabilizer and/or an antioxidant, can already be metered in by the manufacturer of the raw material, or can be metered into the extruder during sheet production. Addition of the dyestuff and, if appropriate, the additives via masterbatch technology is particularly preferred. In this case, the dyestuff and, if appropriate, the additives are dispersed completely in a solid carrier material. Possible carrier materials are certain resins, the thermoplastic itself or also other polymers which are sufficiently compatible with the tnermoplastic.

20 It is important that the particle size and bulk density of the masterbatch are similar to the particle size and bulk density of the thermoplastic, so that homogeneous distribution and thus a homogeneous effect of the dyestuff and additives, such as, for example, homogeneous coloration and stabilization to UV and hydrolysis, can be achieved.
As already stated, the main extruder for production of the core layer and the coextruder or coextruders are connected to a coextruder adapter such that the melts forming the covering layers are applied as thin layers adhesively to the melt of the core layer. The multilayered melt strand thus produced is shaped in a die connected to the line. This die is preferably a slot die.

The multilayered melt strand shaped by a slot die is then sized by polishing calender rolls, i.e. cooled intensively and polished. The calender rolls used can be arranged, for example, in an 1-, F-, L- or S-shape.

The material can then be after-cooled on a roller conveyor, trimmed to size at the edges, cut to length and stacked.

The thickness of the resulting sheet is essentially determined by the take-off, which is positioned at the end of the cooling zone, by the cooling (polishing) rolls coupled to this in terms of speed, and by the conveying speed of the extruder on the one hand and the distance between the rolls on the other hand.

Both single-screw and twin-screw extruders can be employed as the extruder.

The slot die preferably comprises the dismountable die body, the lips and the restrictor bar for flow regulation via the width. For this, the restrictor bar can be bent by tension and pressure screws. The thickness is set by adjusting the lips. It is important to ensure that the multilayered melt strand and the lip have a uniform temperature, since otherwise the melt strand flows out in different thicknesses as a result of the different flow paths.

The sizing die, i.e. the polishing calender, gives the melt strand its shape and dimensions. This is effected by freezing to below the glass transition temperature by means of cooling and polishing. Shaping should no longer take place in this state, since otherwise surface defects would form because of the cooling which has taken place. For this reason, the calender rolls are preferably driven jointly. The temperature of the calender rolls must be lower than the crystallite melting temperature in order to avoid sticking of the melt strand. The melt strand preferably leaves the slot die with a temperature of 240 to 300~C. The first polishing/cooling roll has a temperature between 50~C and 80~C, depending on the output and sheet thickness. The second, somewhat cooler roll cools the second or other surface.

To obtain a uniform thickness in the range from 1 to 20 mm, with good optical properties, it is essential for the temperature of the first polishing roll to be 50 to 80~C.

5 While the sizing device freezes the surfaces of the sheet as smoothly as possible and cools the profile to the extent that it is dimensionally stable, the after-cooling device lowers the temperature of the sheet to virtually room temperature. After-cooling can take place on a roller board.

10 The speed of the take-off should be coordinated precisely with the speed of the calender rolls in order to avoid defects and variations in thickness.

As additional devices, the extrusion line for production of the sheets according to the invention can comprise a separating saw as a device for 15 cutting to length, the edge trimmer, the stacking unit and a control station. The edge or margin trimmer is advantageous, since under certain circumstances the thickness in the margin region may be nonuniform. The thickness and visual properties of the sheet are measured at the control station.
As a result of the surprisingly large number of excellent properties, the transparently colored, amorphous sheet according to the invention is outstandingly suitable for a large number of various uses, for example for interior paneling, for exhibition construction and exhibition articles, as 25 displays, for signs, in the illumination sector, in shopfitting and shelf construction, as advertising articles, as menu stands, as basketball backboards, as room dividers, as aquaria, as information boards, as brochure and magazine stands, and also for extemal applications, such as, for example, greenhouses, roofing, exterior paneling, coverings, for 30 applications in the building sector, illuminated advertising profiles, balcony paneling and skylights.

The invention is illustrated in more detail in the following with the aid of embodiment examples, without being limited by these.

Measurement of the individual properties is carried out here in accordance with the following standards or methods.

Measurement methods Surface gloss:
The surface gloss is determined at a measurement angle of 20~ in accordance with DIN 67 530. The reflector value is measured as the optical parameter for the surface of a sheet. In accordance with the standards ASTM-D 523-78 and ISO 2813 the angle of incidence was set at 20~. Under the angle of incidence set, a ray of light strikes the flat test surface and is reflected or scattered by it. The rays of light incident on the photoelectronic receiver are indicated as a proportional electrical value.
The measurement value is dimensionless and must be stated together with 15 the angle of incidence.

Light transmission:
Light transmission is to be understood as meaning the ratio of the total light allowed through to the amount of incident light.
The light transmission is measured with the ~Hazegard plus" measuring instrument in accordance with ASTM D 1003.

Clouding and Clarity:
25 Clouding is the percentage content of the light allowed through which deviates from the incident light bundle on average by more than 2.5~. The image sharpness is determined under an angle of less than 2.5~.

The clouding and the clarity are measured with the "Hazegard plus"
30 measuring instrument in accordance with ASTM D 1003.

Surface defects:
The surface defects are determined visually.

CA 0226l7l6 l999-0l-29 -Charpy impact strength an:
This value is detemmined in accordance with ISO 179/1.

Izod notched impact strength ak:
5 The Izod notched impact strength or resistance ak is measured in accordance with ISO 180/1A.

Density:
The density is determined in accordance with DIN 53479.
SV (DCA), IV (DCA):
The standard viscosity SV (DCA) is measured in dichloroacetic acid in accordance with DIN 53728.

15 The intrinsic viscosity (IV) is calculated as follows from the standard viscosity (SV) IV (DCA) = 6.67 x 104 SV (DCA) + 0.118 20 Thermal properties:
The thermal properties, such as crystallite melting point Tm~ crystallization temperature range Tc, after-(cold)crystallization temperature TCC and glass transition temperature Tg are measured by means of differential scanning calorimetry (DSC) at a heating-up rate of 1 0~C/minute.
Molecular weight, polydispersity:
The molecular weights Mw and Mn and the resulting polydispersity MW/Mn are measured by means of gel pemmeation chromatography (GPC).

~,~1:
A 4 m~ayered, transparently colored, amorphous polyethylene terephthalate sheetl;3~er sequence A-B-A is produced by the coextrusion process described, B rep~ r.tinq the base layer and A the c~rin~ l~y~r Thr- hA~ y~ C ic 3.~ ~nm thi~k ~ ~ ~ rovoring 22 C~

Example 1:
A 4 mm thick, multilayered, transparently colored, amorphous polyethylene 30 terephthalate sheet having the layer sequence A-B-A is produced by the coextrusion process described, B representing the base layer and A the covering layer. The base layer B is 3.5 mm thick and the two covering AMENDED SHEET

layers, which coat the base layer, are each 250 ,um thick.

The polyethylene terephthalate employed for the base layer B has the following properties:

SV (DCA) : 1100 IV (DCA) : 0.85 dl/g Density : 1.38 g/cm3 Crystallinity : 44 %
Crystallite melting point Tm : 245~C
Crystallization temperature range Tc : 82 to 245~C
After-(cold)crystallization temperature range TCC : 152~C
Polydispersity M~JMn : 2.02 Glass transition temperature : 82~C
The base layer comprises the polyethylene terephthalate described, as the main constituent, and 2% by weight of the soluble dyestuff Solvent Red 138, an anthraquinone derivative from BASF ((É)Thermoplast G).
The soluble dyestuff Solvent Red 138 is added in the form of a masterbatch. The masterbatch is composed of 20% by weight of the dyestuff Solvent Red 138, as the active compound component, and 80%
by weight of the polyethylene terephthalate polymer described above, as the carrier material.
The polyethylene terephthalate from which the covering layers are produced has a standard viscosity SV (DCA) of 1007.5, which corresponds to an intrinsic viscosity IV (DCA) of 0.79 dl/g. The moisture content is < 0.2% and the density (DIN 53479) is 1.41 g/cm3. The crystallinity is 59%, the AMENDED SHEET

- 23O_ - ~'ayers; whlch ~at the base~layer, a~r~ e~r~h 250 ~m thi6k. ~?

The polyethylene terephthalate employed for the base layer ~ as the following properties:
SV (DCA) / 1100 IV (DCA) / : 0.85 dl/g Density ~ : 1.38 g/cm3 Crystallinity ~ : 44 %
Crystallite melting point Tm ~ 245~C
Crystallization temperature range Tc ~ : 82 to 245~C
After-(cold)crystallization temperatu~range TCC : 152~C
Polydispersity M~Mn ~ : 2.02 Glass transition temperature ~ : 82~C
The base layer comprises~e polyethylene terephthalate described, as the main constituent, and 2~ by weight of the soluble dyestuff Solvent Red 138, an anthraquino~derivative from BASF ((~)Thermoplast G).
/

20 The soluble dye~uff Solvent Red 138 is added in the form of a masterbatch. ;~e masterbatch is composed of 20% by weight of the dyestuff So~yent Red 138, as the active compound component, and 80%
by weightf5f the polyethylene terephthalate polymer described above, as the car?~r material.
The/polyethylene terephthalate from which the covering layers are p~duced has a standard viscosity SV (DCA) which corresponds to an jhtrinsic viscosity IV (DCA) of 0.79 dl/g. The moisture content is < 0.2% and JthF! ~lPnc~ ~4/~ l~ l.q1 ~cm3. Tl~ y~ nlly ;~ ~tO~the 30 crystallite melting point, according to DSC measurements, being 258~C.
The crystallization temperature range Tc is between 83~C and 258~C, the after-crystallization temperature (also the cold crystallization temperature) TCC being 144~C. The polydispersity M~JMn of the polyethylene terephthalate polymer is 2.14.

- The glass transition temperature is 83~C.

Before the coextrusion, 90% by weight of the polyethylene terephthalate for the base layer and 10% by weight of the masterbatch are mixed and 5 the mixture is dried at 170~C for 5 hours in the main dryer, which is connected to the main extruder.

The polyethylene terephthalate for the covering layer is likewise dried at 1 70~C for 5 hours in two smaller dryers which are connected to the two 1 0 coextruders.

The polyethylene terephthalate for the base or core layer and the masterbatch are melted in the main extruder and the polyethylene terephthalate for the covering layers are melted in the coextruders. The 15 extrusion temperature of the main extruder for the core layer is 281 ~C.

The extrusion temperatures of the two coextruders for the covering layers are 294~C. The main extruder and the two coextruders are connected to a coextruder adapter, which is constructed such that the melts which form 20 the covering layers are applied as thin layers adhesively to the melt of the core layer. The multilayered melt strand thus produced is shaped in the slot die, connected to the line, and polished on a polishing calender, the rolls of which are arranged in an S-shape, to a three-layered sheet 4 mm thick.
The first calender roll has a temperature of 65~C and the subsequent rolls each have a temperature of 58~C. The speed of the take-off is 4.2 m/minute.

30 After the after-cooling, the three-layered transparent sheet is trimmed at the edges with separating saws, cut to length and stacked.

The transparently colored, amorphous, three-layered PET sheet produced has the following properties - Layer construction : A-B-A
- Totalthickness : 4 mm - Thickness ofthe base layer : 3.5 mm - Thickness of the covering layers : 0.25 mm each - Color : red-transparent - Surface gloss 1st side : 160 (measurement angle 20~) 2nd side : 153 - Light transmission : 36.9%
- Clarity : 99.0%
- Clouding : 3.8%
- Surface defects per m2 : none (specks, orange peel, bubbles and the like) - Charpy impact strength an : no fracture - Izod notched impact strength ak : 4.9 kJ/m2 - Cold forming properties : good, no defects - Crystallinity : o%
- Density : 1.33 g/cm3 - Calender roll deposits after 2 hours of production : none Example 2:
A three-layered, red-transparently colored, amorphous sheet is produced analogously to Example 1.

25 The polyethylene terephthalate employed for the base or core layer B has the following properties:

- SV (DCA) 3173 - IV (DCA) : 2.23 dl/g - Density : 1.34 g/cm3 - Crystallinity : 12%
- Crystallite melting pointTm : 240~C
- Crystallization temperature range Tc : 82~C to 240~C
- Cold crystallization temperature TCC : 156~C

- Polydispersity M~JMn : 3.66 - Glass transition temperature : 82~C
Mw : 204,660 g/mol - Mn : 55,952 g/mol As in Example 1, the soluble dyestuff Solvent Red 138 is added via masterbatch technology. The base layer comprises only 1.0% by weight of the dyestuff Solvent Red 138, i.e. only 5% by weight of the masterbatch is metered into the polyethylene terephthalate of the base layer.
The extrusion temperature is 274~C. The first calender roll has a temperature of 50~C and the subsequent rolls have a temperature of 45~C.
The speed of the take-off and of the calender rolls is 2.4 m/minute.

15 The sheet produced has the following properties:

- Layer construction : A-B-A
- Thickness of the covering layers : 0.4 mm each - Thickness of the base layers : 5.2 mm - Total thickness : 6 mm - Color : red-transparent - Surface gloss 1 st side : 162 (measurement angle 20~) 2nd side : 159 - Light transmission : 68.4%
- Clarity : 99.1 %
- Clouding : 3.2%
- Surface defects per m2 : none (specks, orange peel, bubbles and the like) - Charpy impact strength an : no fracture - Izod notched impact strength ak : 5.1 kJ/m2 - Cold forming properties : good, no defects - Crystallinity : o%
- Density : 1.33g/cm3 - Calender roll deposits after 2 hours : none Example 3 A transparently colored, three-layered, amorphous sheet is produced 5 analogously to Example 1. The base layer of the sheet comprises 4% by weight of the soluble dyestuff Solvent Blue 35, a fat-soluble anthraquinone dyestuff from BASF (t~Sudanblau 2).
The 4% by weight of the dyestuff Solvent Blue 35 is likewise added in the form of a masterbatch, the masterbatch being composed of 20% by weight 10 of the dyestuff Solvent Blue 35 and 80% of the polyethylene terephthalate polymer of the base layer from Example 1. 80% by weight of the polyethylene terephthalate polymer of the base layer from Example 1 is employed with 20% by weight of the masterbatch.

15 The blue-transparently colored sheet produced has the following properties profile:

- Layer construction : A-B-A
- Total thickness : 4 mm - Thickness of the base layer : 3.5 mm - Thickness of the covering layers : 0.25 mm each - Color : blue-transparent - Surface gloss 1st side : 163 (measurement angle 20~) 2nd side : 158 - Light transmission : 30.6%
- Clarity 99.0%
- Clouding 4.7%
- Surface defects per m2 : none (specks, orange peel, bubbles and the like) - Charpy impact strength an : no fracture- Izod notched impact strength ak : 4.9 kJ/m2 - Coldforming properties : good, no defects - Crystallinity o%
- Density : 1.33 g/cm3 - Calender roll deposits after 2 hours : none Comparison Example 1:
5 A transparently colored sheet is produced analogously to Example 1. The covering layers are analogous to the covering layers from Example 1. The polyethylene terephthalate employed in the base layer has a standard viscosity SV (DCA) of 760, which corresponds to an intrinsic viscosity IV
(DCA) of 0.62 dl/g. The other properties are identical to the properties of 10 the polyethylene terephthalate from Example 1 in the context of measurement accuracy. The masterbatch employed is identical to the masterbatch from Example 1. The process parameters and the temperature were chosen as in Example 1. As a result of the low viscosity of the base layer, no sheet production is possible. The three-layered melt 15 strand shows a number of flow disturbances. The stability of the melt is inadequate.

Comparison Example 2:
A transparently colored, translucent sheet is produced analogously to 20 Example 2, the polyethylene terephthalate and masterbatch from Example 2 also being employed. The first calender roll has a temperature of 93~C
and the subsequent rolls each have a temperature of 87~C.

The sheet produced is extremely red-cloudy and almost nontransparent.
25 The light transmission, the clarity and the gloss are significantly reduced.
The sheet shows surface defects, such as bubbles, orange peel or speckled structures. The optical properties are unacceptable for a transparent colored application.

30 The sheet produced has the following properties profile:

- Thickness : 6 mm - Surface gloss 1st side : inhomogeneously 70 to (measurement angle 20~) 2nd side : inhomogeneously 70 to - Lighttransmission : about8%to 10%
- Clarity : not measurable - Clouding : not measurable - Surface defects per m2 : bubbles, orange peel, specks (Specks, orange peel, bubbles and the like) - Charpy impact strength an : no fracture - Izod notched impact strength ak : 3.2 kJ/m2 - Cold forming properties : good - Crystallinity : about 8% to 10%
- Density : 1.34g/cm3

Claims

claims

1. A multilayered, transparently colored, amorphous sheet having a thickness in the range from 1 to 20 mm which comprises a crystallizable thermoplastic as the main constituent, which has a multilayered construction of at least one core layer and at least one covering layer, the standard viscosity of the thermoplastic contained in the core layer, measured in dichloroacetic acid according to DIN 53728, being greater than the standard viscosity of the thermoplastic contained in the covering layer and at least one layer having at least one dyestuff which is soluble in the thermoplastic of the layer.

2. The sheet as claimed in claim 1, wherein the standard viscosity of the thermoplastic of the core layer, of which it comprises at least one, is in the range from 800 to 5000 and that of the thermoplastic of the covering layer, of which it comprises at least one, is in the range from 500 to 4500.

3. The sheet as claimed in claim 1 or 2, wherein the sheet has two covering layers and a core layer lying between the covering layers.

4. The sheet as claimed in claim 1, wherein the concentration of the soluble dyestuff is in the range from 0.001 to 20% by weight, based on the weight of the crystallizable thermoplastic of the layer treated with the dyestuff.

5. The sheet as claimed in one of the preceding claims, wherein the soluble dyestuff is an azo or anthraquinone dyestuff which is soluble in fats or aromatic substances.

6. The sheet as claimed in one of the preceding claims, wherein at least one of the core and/or covering layer(s) is treated with at least one UV stabilizer.

7. The sheet as claimed in claim 6, wherein the concentration of the UV stabilizer in the layer, of which it comprises at least one, is 0.01 to 8%
by weight, based on the weight of the thermoplastic of the layer comprising the UV stabilizer.

8. The sheet as claimed in claim 6 or 7, wherein the concentration of the UV stabilizer in the core layer, of which it comprises at least one, is 0.01 to 1% by weight, based on the weight of the thermoplastic of the core layer comprising the UV stabilizer.

9. The sheet as claimed in one of claims 6 to 8, wherein the UV
stabilizer is chosen from 2-hydroxybenzotriazoles, triazines and mixtures thereof.

10. The sheet as claimed in claim 9, wherein 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.

11. The sheet as claimed in one of the preceding claims, wherein at least one of the core and/or covering layers is treated with at least one antioxidant.

12. The sheet as claimed in claim 11, wherein 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.

13. The sheet as claimed in claim 11 or 12, wherein the antioxidant, of which it comprises at least one, is chosen from sterically hindered phenols, secondary aromatic amines, phosphites, phosphonites, thioethers, carbodiimides and zinc dibutyldithiocarbamate.

14. The sheet as claimed in claim 13, wherein the antioxidant is 2-[2,4,8,10-tetrakis(1,1-dimethylethyl)dibenzo[d,f][1,3,2]dioxaphosphepin-6-yl]oxy)-ethyl]ethanamine and/or tris(2,4-di-tert.-butylphenyl)phosphite.

15. The sheet as claimed in one of the preceding claims, wherein the crystallizable thermoplastic is chosen from a polyalkylene terephthalate with a C1 to C12-alkylene radical, a polyalkylenenaphthalate with a C1 to C12-alkylene radical, a cycloolefin polymer and a cycloolefin copolymer.

16. The sheet as claimed in claim 15, wherein the alkylene radical is ethylene or butylene.

17. The sheet as claimed in claim 15, wherein the thermoplastic is polyethylene terephthalate.

18. The sheet as claimed in one of claims 15 to 17, wherein the thermoplastic is recycled material of the thermoplastic.

19. The sheet as claimed in one of the preceding claims, wherein the or each thermoplastic has a crystallite melting point, measured by DSC with a heating-up rate of 10°C/minute, in the range from 220 to 280°C.

20. The sheet as claimed in one of the preceding claims, wherein the or each thermoplastic has a crystallization temperature, measured by DSC
with a heating-up rate of 10 °C/minute, in the range from 75 to 280°C.

21. The sheet as claimed in one of the preceding claims, wherein the or each thermoplastic employed has a crystallinity which is in the range from 5 to 65%.

22. The sheet as claimed in one of the preceding claims, wherein the or each thermoplastic employed has a cold (after-)crystallization temperature T CC in a range from 120 to 158°C.

23. The sheet as claimed in one of the preceding claims, wherein the sheet has a surface gloss, measured in accordance with DIN 67530 (measurement angle 20°), of greater than 100.

24. The sheet as claimed in one of the preceding claims, wherein the sheet has a light transmission, measured in accordance with ASTM D
1003, in the range from 5 to 90%.

25. The sheet as claimed in one of the preceding claims, wherein the clouding, measured in accordance with ASTM D 1003, is in the range from 2 to 50%.

26. The sheet as claimed in one of the preceding claims, wherein no fracture occurs during measurement of the Charpy impact strength a n, measured in accordance with ISO 179/1 D.

27. The sheet as claimed in one of the preceding claims, wherein the sheet has an Izod notched impact strength a k, measured in accordance with ISO 180/1A, in the range from 2.0 to 8.0 kJ/m2.

28. The sheet as claimed in one of the preceding claims, wherein the sheet has an distinctness of image which, measured in accordance with ASTM D 1003 under an angle of less than 2.5°, is more than 83%.

29. The sheet as claimed in one of the preceding claims, wherein the sheet has a scratch-resistant coating on at least one side.

30. The sheet as claimed in claim 29, wherein the scratch-resistant coating comprises silicon and/or acrylic.

31. A process for the production of a multilayered, transparent, amorphous sheet as claimed in one of the preceding claims, wherein the thermoplastic for the core layer, of which it comprises at least one, in a main extruder, and the thermoplastic for the covering layer, of which it comprises at least one, are melted in a coextruder, the melts are layered one on top of the other and the layers brought together are shaped by a die and then sized, polished and cooled in a polishing stack having at least two rolls, the temperature of the first roll of the polishing stack being in a range of 50 - 80°C, and the soluble dyestuff, of which it comprises at least one, is melted together with the thermoplastic of the layer(s) treated with this.

32. The process as claimed in claim 31, wherein at least one additive is melted together with the thermoplastic of the layer to be treated with the additive.

33. The process as claimed in claim 31 or 32, wherein the thermoplastic is a polyalkylene terephthalate or polyalkylene naphthalate.

34. The process as claimed in claim 33, wherein the polyalkylene terephthalate or polyalkylene naphthalate is dried at 160 to 180°C for 4 to 6 hours before the extrusion.

35. The process as claimed in one of Claims 33 or 34, wherein the temperature of the polyalkylene terephthalate or polyalkylene naphthalate melt is in the range from 250 to 320°C.

36. The process as claimed in one of claims 31 to 35, wherein the dyestuff and if appropriate the additive, of which at least one is present, are added via masterbatch technology.

37. The use of a multilayered, transparent, amorphous sheet as claimed in one of the preceding claims 1 to 30 for the exterior and interior sector.