WO1997000284A1

WO1997000284A1 - Amorphous, transparent, uv-stabilised plate made of thermoplastic capable of crystallising

Info

Publication number: WO1997000284A1
Application number: PCT/EP1996/002514
Authority: WO
Inventors: Ursula Murschall; Wolfgang Gawrisch; Rainer Brunow
Original assignee: Hoechst Aktiengesellschaft
Priority date: 1995-06-19
Filing date: 1996-06-10
Publication date: 1997-01-03
Also published as: NO975870D0; EP0833858A1; DE19522118C1; OA10552A; KR19990028207A; JPH11507965A; BR9609412A; PL324207A1; TW355717B; RU2169158C2; CA2225173A1; BG102073A; MX9710294A; NO975870L; HUP9803029A2; AU6125896A; CZ414297A3

Abstract

A transparent, amorphous plate with a thickness in a range from 1 to 20 mm that contains as main component a thermoplastic material capable of crystallising is characterised in that it contains at least one UV stabiliser as light protective agent. Also disclosed is a process for producing the same and its use.

Description

Amorphous, transparent, UV-stabilized plate made of a crystallizable thermoplastic

The invention relates to an amorphous, transparent, UV-stabilized plate made of a crystallizable thermoplastic, the thickness of which is in the range from 1 to 20 mm. The plate contains at least one UV stabilizer as a light stabilizer and is characterized by very good optical and mechanical properties. The invention further relates to a method for producing this plate and its use.

Amorphous, transparent plates with a thickness between 1 and 20 mm are well known. These flat structures consist of amorphous, non-crystallizable thermoplastics. Typical examples of such thermoplastics, which are processed into sheets, are, for. B. polyvinyl chloride (PVC), polycarbonate (PC) and polymethyl methacrylate (PMMA). These semi-finished products are manufactured on so-called extrusion lines (cf. Polymer Werkstoffe, Volume II, Technologie 1, p. 136, Georg Thieme Verlag, Stuttgart, 1984). The powdered or granular raw material is melted in an extruder. After extrusion, the amorphous thermoplastics can be easily reshaped using smoothing units or other shaping tools due to the steadily increasing viscosity as the temperature decreases. After molding, amorphous thermoplastics then have sufficient stability, ie a high viscosity, in order to "stand on their own" in the calibration tool. But they are still soft enough to be shaped by the tool. The melt viscosity and inherent stiffness of amorphous thermoplastics is so high in the calibration tool that the semi-finished product does not collapse in the calibration tool before it cools down. With easily decomposable materials such. B. PVC are special processing aids for extrusion, such as B. Processing stabilizers against decomposition and lubricants against excessive internal friction and thus uncontrollable heating necessary. External lubricants are required to prevent snagging on walls and rollers.

When processing PMMA z. B. used a degassing extruder for dehumidification.

In the production of transparent plates made of amorphous thermoplastics z. T. costly additives are required, which can migrate and lead to production problems due to evaporation and surface coatings on the semi-finished product. PVC sheets are heavy or can only be recycled using special neutralization or electrolysis processes. PC and PMMA boards are also poor and can only be recycled if the mechanical properties are lost or extremely deteriorated.

In addition to these disadvantages, PMMA sheets also have extremely poor impact strength and shatter when broken or subjected to mechanical stress. In addition, PMMA panels are highly flammable, so that they must not be used, for example, for indoor applications or in exhibition stand construction.

PMMA and PC sheets are also not cold-formable. During cold forming, PMMA sheets break into dangerous fragments. When cold-forming PC sheets, hairline cracks and whitening occur.

DE-A-3 531 878 describes plastic films made of thermoplastic polyester which contain a UV stabilizer and have a thickness of 0.5-0.03 mm. These foils are obtained by extrusion blow molding and are therefore partially crystalline. Consequently, the method described in this document cannot be used to obtain an amorphous film with a thickness of 1 mm or more.

JP-A-5 320 528 describes a thermoplastic resin composition containing an epoxylated polyester. According to a preferred embodiment, this composition contains PVC as the main component. The plates obtained from this by kneading are transparent and 1 mm thick.

EP-A-0 471 528 describes a method for molding an article from a polyethylene terephthalate (PET) plate. The PET plate is heat-treated in a deep-drawing mold on both sides in a temperature range between the glass transition temperature and the melting temperature. The molded PET sheet is taken out of the mold when the degree of crystallization of the molded PET sheet is in the range of 25 to 50%. The PET sheets disclosed in EP-A-0 471 528 have a thickness of 1 to 10 mm. Since the deep-drawn molded article made from this PET sheet is partially crystalline and therefore no longer transparent and the surface properties of the molded article are determined by the deep-drawing process, the temperatures and shapes given, it is immaterial which optical properties (e.g. gloss, Turbidity and light transmission) have the PET plates used. As a rule, the optical properties of these plates are poor and need to be optimized.

In addition, these plates do not contain any UV stabilizers as light stabilizers, so that neither the plates nor the moldings made from them are suitable for outdoor use. In outdoor applications, these plates or molded articles show yellowing and deterioration of the mechanical properties due to photooxidative degradation by sunlight after a short time. US Pat. No. 3,496,143 describes the vacuum deep drawing of a 3 mm thick PET sheet, the crystallization of which is said to be in the range from 5 to 25%. The crystallinity of the deep-drawn molded body is greater than 25%. No demands are made on the optical properties of these PET sheets either. Since the crystallinity of the plates used is already between 5 and 25%, these plates are cloudy and opaque. These plates also do not contain any light stabilizers and are therefore not suitable for outdoor use.

With the previously known methods, amorphous plates, which contain a crystallizable thermoplastic as the main component, with a thickness of 1 mm or more could not be produced in sufficient quality.

The object of the present invention was to provide an amorphous, transparent plate with a thickness of 1 to 20 mm which, in addition to good mechanical and optical properties, above all has high UV stability.

A high UV stability means that the plates are not or only slightly damaged by sunlight or other UV radiation, so that the plates are suitable for outdoor applications and / or critical indoor applications. In particular, the panels should not yellow over several years of outdoor use, should not show embrittlement or cracking of the surface, and should not show any deterioration in the mechanical properties.

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

The good mechanical properties include high impact strength and high breaking strength. In addition, the plate according to the invention should be recyclable, in particular without loss of the mechanical properties, and also flame-retardant, so that it can also be used, for example, for interior applications and in exhibition construction.

This object is achieved by a transparent, amorphous plate with a thickness in the range from 1 to 20 mm, which contains a crystallizable thermoplastic as the main component, which is characterized in that the plate contains at least one UV stabilizer as light stabilizer.

The main component of the transparent, amorphous plate is a crystallizable thermoplastic. Suitable crystallizable or partially crystalline thermoplastics are, for example, polyethylene terephthalate,

Polybutylene terephthalate, cycloolefin polymers and cycloolefin copolymers, with polyethylene terephthalate being preferred.

According to the invention, crystallizable thermoplastics are understood to mean crystallizable homopolymers, crystallizable copolymers, crystallizable compounds, crystallizable recyclate and other variations of crystallizable thermoplastics.

For the purposes of the present invention, amorphous plate is understood to mean those plates which, although the crystallizable thermoplastic used preferably has a crystallinity of between 5 and 65%, particularly preferably between 25 and 65%, are not crystalline. Non-crystalline or amorphous means that the degree of crystallinity is generally below 5%, preferably below 2% and particularly preferably 0%. The amorphous plate according to the invention is essentially unoriented. The transparent, amorphous plate further contains at least one UV stabilizer as light stabilizer, the concentration of the UV stabilizer preferably being between 0.01% by weight and 5% by weight, based on the weight of the crystallizable thermoplastic.

Light, especially the ultraviolet portion of solar radiation, i.e. H. the wavelength range from 280 to 400 nm initiates degradation processes in thermoplastics, as a result of which not only the visual appearance changes as a result of color change or yellowing, but also the mechanical-physical properties are adversely affected.

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

Polyethylene terephthalates, for example, begin to absorb UV light below 360 nm, 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, mainly chain cleavages are observed, but no cross-links. Carbon monoxide, carbon dioxide and carboxylic acids are the predominant quantities

In addition to the direct photolysis of the ester groups, oxidation reactions must also be considered, which also result in the formation of carbon dioxide via peroxide radicals. The photooxidation of polyethylene terephthalates can also lead to hydroperoxides and their decomposition products and to associated chain cleavages via hydrogen cleavage in the α-position of the ester groups (H. Day, DM Wiles: J. Appl. Polym. Be 1 6, 1 972, page 203).

UV stabilizers or UV absorbers as light stabilizers are chemical compounds that can intervene in the physical and chemical processes of light-induced degradation. Soot and other pigments can partially protect against light. However, these substances are unsuitable for transparent plates because they lead to discoloration or color change. For transparent, amorphous plates, only organic and organometallic compounds are suitable, which give the thermoplastic to be stabilized no or only an extremely small color or color change.

Suitable UV stabilizers as light stabilizers are, for example, 2-hydroxybenzophenones, 2-hydroxybenzotriazoles, organo-nickel compounds, salicylic acid esters, cinnamic acid ester derivatives, resorcinol monobenzoates, oxalic acid anilides, hydroxybenzoic acid esters, sterically hindered amines and triazines, the 2-hydroxybenzotriazoles being preferred.

In a particularly preferred embodiment, the transparent, amorphous plate according to the invention contains, as the main constituent, a crystallizable polyethylene terephthalate and 0.01% by weight to 5.0% by weight of 2- (4,6-diphenyl-1,3,5-triazine -2-yl) -5- (hexyl) oxy-phenol (structure in Fig. 1 a) or 0.01 wt% to 5.0 wt% 2,2'-methylene-bis (6- ( 2H-benzotriazol-2-yl) -4- (1, 1, 3,3-tetramethylbutyD-phenol (structure in Fig. 1 b). In a preferred embodiment, mixtures of these two UV stabilizers or mixtures of at least one of these can also be used two UV stabilizers can be used with other UV stabilizers, the total concentration of light stabilizers is preferably between 0.01% and 5.0% by weight, based on the weight of crystallizable polyethylene terephthalate.

The surface gloss, measured according to DIN 67530 (measuring angle 20 °), is greater than 1 20, preferably greater than 140, the light transmission, measured according to ASTM D 1003, is more than 84%, preferably more than 86%, and the cloudiness of the plate, measured according to ASTM D 1003, is less than 15%, preferably less than 11%.

The image sharpness of the plate, which is also called Clarity and is determined at an angle of less than 2.5 ^c (ASTM D 1003), is preferably above 96% and particularly preferably above 97%.

In the case of polyethylene terephthalate in the measurement of impact strength a (1 79/1 D measured according to ISO) delivers _n Charpy to the plate preferably does not fracture. In addition, the notched impact strength a _k according to Izod (measured according to ISO 180/1 A) of the plate is in the range from 2.0 to 8.0 kJ / m ² , preferably in the range from 3.0 to 8.0 kJ / m ² and particularly preferably in the range from 4.0 to 6.0 kJ / m ² .

Polyethylene terephthalates with a crystallite melting point T _m , measured with DSC (differential scanning calorimetry) with a heating rate of 10 ° C / min, from 220 ° C to 280 ° C, preferably from 250 ° C to 270 ° C, with a crystallization temperature range T _c between 75 ° C and 280 ° C, preferably 75 ° C to 260 ° C, a glass transition temperature T _g between 65 ° C and 90 ° C and with a density, measured according to DIN 53479, of 1.30 to 1.45 g / cm ³ and a crystallinity between 5% and 65%, preferably between 25% and 65%, are preferred polymers as starting materials for the production of the plate according to the invention. The standard viscosity SV (DCE) of the polyethylene terephthalate, measured in dichloroacetic acid according to DIN 53728, is between 800 and 1,800, preferably between 950 and 1,250 and particularly preferably between 1000 and 1200.

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

IV (DCE) = 6.67 ^• 10 ^"4 SV (DCE) + 0, 1 1 8

The bulk density, measured according to DIN 53466, is preferably between 0.75 kg / dm ³ and 1.0 kg / dm ³ , and particularly preferably between 0.80 kg / dm ³ and 0.90 kg / dm ³ .

The polydispersity M _w / M _{n of} the polyethylene terephthalate measured by means of gel permeation chromatography is preferably between 1.5 and 6.0 and particularly preferably between 2.0 and 3.5.

Weathering tests have shown that even after 5 to 7 years of outdoor use, the UV-stabilized plates according to the invention generally have no yellowing, no embrittlement, no loss of gloss on the surface, no cracking on the surface and no deterioration in the mechanical properties.

In addition to excellent UV stability, good cold-formability without breakage, without hairline cracks and / or without white breakage was found completely unexpectedly, so that the plate according to the invention can be deformed and bent without the effect of temperature.

In addition, measurements have shown that the PET panel according to the invention is flame-retardant and flame-retardant, so that it is suitable, for example, for indoor applications and in exhibition stand construction. Furthermore, the plate according to the invention can be easily recycled without environmental pollution and without loss of the mechanical properties, which makes it suitable, for example, for use as short-lived advertising signs or other promotional items.

The transparent, amorphous, UV-stabilized plate according to the invention can be produced, for example, by an extrusion process in an extrusion line.

Such an extrusion line is shown schematically in FIG. 2. It essentially comprises an extruder (1) as a plasticizing system, a slot die (2) as a tool for shaping, a smoothing unit / calender (3) as a calibration tool, a cooling bed (4) and / or a roller conveyor (5) for after-cooling, a roller take-off (6), a separating saw (7), a side cutting device (9), and optionally a stacking device (8).

The process for producing the plate according to the invention is described in detail below using the example of polyethylene terephthalate as a thermoplastic.

The process is characterized in that the crystallizable thermoplastic (for example polyethylene terephthalate) is optionally dried, then melted in the extruder, preferably together with the UV stabilizer, the melt is molded through a nozzle and then calibrated, smoothed and cooled in the calender before being brings the plate to size. It is essential for the process according to the invention that the first roller of the smoothing unit has a temperature which is in the range from 50 ° C. to 80 ° C., since it would otherwise be difficult to produce an amorphous transparent plate with a crystallizable thermoplastic in a thickness of 1 mm and more.

According to the invention, the light stabilizer can be metered in at the thermoplastic raw material manufacturer or can be metered into the extruder during plate production.

The addition of the light stabilizer via masterbatch technology is particularly preferred. The light stabilizer is fully dispersed in a solid carrier material. As carrier materials come certain resins, the thermoplastic itself, such as. B. the polyethylene terephthalate or other polymers that are sufficiently compatible with the thermoplastic, in question.

It is important that the grain size and bulk density of the masterbatch is similar to the grain size and bulk density of the thermoplastic, so that a homogeneous distribution and thus homogeneous UV stabilization can take place.

The drying of the polyethylene terephthalate before the extrusion is preferably carried out for 4 to 6 hours at 160 to 180 ° C.

The polyethylene terephthalate is then melted in the extruder. The temperature of the PET melt is preferably in the range from 250 to 320 ° C., the temperature of the melt being able to be set essentially both by the temperature of the extruder and by the residence time of the melt in the extruder. The melt then leaves the extruder through a nozzle. This nozzle is preferably a slot die.

The PET melted by the extruder and shaped by a slot die is calibrated by smoothing calender rolls, i.e. H. intensely chilled and smoothed. The calender rolls can, for example, be arranged in an I, F, L or S shape (FIG. 3).

The PET material can then be cooled on a roller conveyor, cut to the side, cut to length and finally stacked.

The thickness of the PET plate is essentially determined by the take-off, which is arranged at the end of the cooling zone, the cooling (smoothing) rolls coupled with it in terms of speed and 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 used as extruders.

The slot die preferably consists of the separable tool body, the lips and the dust bar for flow regulation across the width. For this purpose, the dust bar can be bent by tension and pressure screws. The thickness is adjusted by adjusting the lips. It is important to ensure that the temperature of the PET and the lip is even, otherwise the PET melt will flow out to different thicknesses due to the different flow paths.

The calibration tool, d. H. the smoothing calender gives the PET melt the shape and dimensions. This is done by freezing below the glass transition temperature by means of cooling and smoothing. Deformation is no longer allowed in this state, otherwise it will be in this cooled state Surface defects would arise. For this reason, the calender rolls are preferably driven together. The temperature of the calender rolls must be lower than the crystallite melting temperature in order to avoid sticking of the PET melt. The PET melt leaves the slot die at a temperature of 240 to 300 ° C. The first smoothing-cooling roller has a temperature between 50 ° C and 80 ° C depending on the output and plate thickness. The second, somewhat cooler roller cools the second or other surface.

While the calibration device freezes the PET surfaces as smoothly as possible and cools the profile to such an extent that it is dimensionally stable, the after-cooling device lowers the temperature of the PET plate to almost room temperature. After-cooling can be done on a roller board. The speed of the take-off should be exactly matched to the speed of the calender rolls in order to avoid defects and thickness fluctuations.

A separating saw as a cutting device, the side trimming, the stacking system and a control point can be located in the extrusion line for the production of PET sheets as additional devices. The side or edge trimming is advantageous because the thickness in the edge area can be uneven under certain circumstances. The thickness and appearance of the plate are measured at the control point.

Due to the surprising number of excellent properties, the transparent and amorphous plate according to the invention is excellently suitable for a large number of different uses, for example for interior cladding, for trade fair construction and trade fair articles, as displays, for signs, for protective glazing of machines and vehicles, in the lighting sector, in the store. and shelf construction, as promotional items, as menu card stands, as basketball goal boards, as room dividers, for aquariums, as Information boards and as brochure and newspaper stands.

Due to the good UV stability, the transparent, amorphous plate according to the invention is also suitable for outdoor applications, such as for greenhouses, roofing, glazing, safety glasses, external cladding, covers, applications in the construction sector, illuminated advertising profiles, balcony cladding, roof hatches and caravan windows.

The invention is explained in more detail below on the basis of exemplary embodiments, without being restricted thereby.

The individual properties are measured in accordance with the following standards and procedures.

Measurement methods

Surface gloss:

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

Light transmission:

Under the light transmission is the ratio of the total let through

To understand light to the incident amount of light.

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

Turbidity and Clarity:

Haze is the percentage of the transmitted light that deviates by more than 2.5 ° on average from the incident light beam. The image sharpness is determined at an angle of less than 2.5 °. The haze and clarity are measured using the "Hazegard plus" measuring device in accordance with ASTM D 1003.

Surface defects:

The surface defects are determined visually.

Charpy impact strength a _n:

This size is determined according to ISO 1 79/1 D.

Notched impact strength a _k according to Izod:

The notched impact strength or strength a _k according to Izod is measured according to ISO 1 80/1 A.

Density:

The density is determined according to DIN 53479.

SV (DCE), IV (DCE):

The standard viscosity SV (DCE) is based on DIN 53726 in

Dichloroacetic acid measured.

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

IV (DCE) = 6.67 ^■ 10 ^'4 SV (DCE) + 0, 1 18

Thermal properties:

The thermal properties such as crystallite melting point T _m , crystallization temperature range T _c , post- (cold) crystallization temperature T _CN and glass transition temperature T are measured by means of differential scanning calorimetry (DSC) at a heating rate of 10 ° C / min. Molecular weight, polydispersity:

The molecular weights M _w and M _n and the resulting polydispersity M _w / M _n are measured by means of gel permeation chromatography (GPC).

Weathering (both sides), UV stability:

The UV stability is tested according to the test specification ISO 4892 as follows

Atlas Ci 65 Weather Ometer test device

Test conditions ISO 4892, i.e. H. artificial weathering

Irradiation time 1000 hours (per side)

Irradiation 0.5 W / m ² , 340 nm

Temperature 63 ° C

Relative humidity 50%

Xenon lamp inner and outer filter made of borosilicate

Irradiation cycles 102 minutes of UV light, then 1 8 minutes of UV light with water spraying the samples, then again 102 minutes of UV light, etc.

Color change:

The color change of the samples after artificial weathering is measured with a spectrophotometer according to DIN 5033.

The following applies:

ΔL: difference in brightness

+ ΔL: The sample is lighter than the standard

-ΔL: The sample is darker than the standard

ΔA: difference in the red-green area

+ ΔA: The sample is redder than the standard

-ΔA: The sample is greener than the standard ΔB: difference in the blue-yellow range

+ ΔB: The sample is yellower than the standard -ΔB: The sample is bluer than the standard

ΔE: total color change

ΔE = V ΔL ² + ΔA ² + ΔB ²

The greater the numerical deviation from the standard, the greater the

Color difference.

Numerical values of <0.3 are negligible and mean that there is no significant change in color.

Yellowness index:

The yellowness index G is the deviation from the colorlessness in the "yellow" direction and is measured in accordance with DIN 61 67. Yellow value G values of <5 are not visually visible.

The examples and comparative examples below each relate to single-layer, transparent plates of different thicknesses which are produced on the extrusion line described.

All panels were weathered on both sides with the Atlas Ci 65 Weather Ometer from Atlas according to the test specification ISO 4892 on both sides and then tested for mechanical properties, discoloration, surface defects, haze and gloss.

Example 1 :

A 3 mm thick, transparent, amorphous plate is produced, the main constituent being polyethylene terephthalate and 1.0% by weight of the UV stabilizer 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5- (hexyl) oxyphenol (Tinuvin 1 577 from the company Ciba-Geigy) contains.

Tinuvin 1 577 has a melting point of 149 ^C C and is thermally stable up to approx. 330 ° C.

For the purpose of homogeneous distribution, 1.0% by weight of the UV stabilizer is incorporated directly into the polyethylene terephthalate at the raw material manufacturer. The polyethylene terephthalate from which the transparent plate is made has a standard viscosity SV (DCE) of 1010, which corresponds to an intrinsic viscosity IV (DCE) of 0.79 dl / g. The moisture content is <0.2% and the density (DIN 53479) is 1.41 g / cm ³ . The crystallinity is 59%, the crystallite melting point according to DSC measurements being 258 ° C. The crystallization temperature range T _c is between 83 ° C and 258 ° C, the post-crystallization temperature (also cold crystallization temperature) T _CN at 144 ° C. The polydispersity M _w / M _{n of} the polyethylene terephthalate is 2.14. The glass transition temperature is 83 ° C.

Before the extrusion, the polyethylene terephthalate with a crystallinity of 59% is dried in a dryer at 170 ° C. for 5 hours and then extruded in a single-screw extruder at an extrusion temperature of 286 ° C. through a slot die onto a smoothing calender whose rolls are arranged in an S-shape and smoothed into a 3 mm thick plate. The first calender roll has a temperature of 73 ° C and the subsequent rolls each have a temperature of 67 ° C. The speed of the take-off and the calender rolls is 6.5 m / min.

After the after-cooling, the transparent, 3 mm thick PET sheet is trimmed at the edges with separating saws, cut to length and stacked. The transparent, amorphous PET sheet produced has the following property profile:

3 mm thick

Surface gloss 1. Page 198

(Measuring angle 20 °) 2nd page 196

Light transmission 91%

Clarity 100%

Turbidity 1.5%

Surface defects per m ² none

(Specks, orange peel, blisters, etc.)

Charpy impact strength a _n no break

Notched impact strength a _k according to Izod 4.2 kJ / m ²

Cold formability good, no defects

Crystallinity 0%

Density 1.33 g / cm ³

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

3 mm thick

Surface gloss 1. Page 1 96

(Measuring angle 20 °) 2nd page 1 95

Light transmission 91.1%

Clarity 100%

Turbidity 1.6%

Total discoloration ΔE 0, 22

Dark discoloration ΔL -0, 1 8

Red-green discoloration ΔA -0.08

Blue-yellow discoloration ΔB 0, 10 No surface defects

(Cracks, embrittlement)

Yellowness index G 4

Charpy impact strength a _n no break

Notched impact strength a _k according to Izod 4, 1 kJ / m ²

Cold formability good

Example 2:

Analogous to Example 1, a transparent, amorphous plate is produced, the UV stabilizer being 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5- (hexyl) -oxyphenol (^ Tinuvin 1 577 ) is metered in in the form of a master batch. The masterbatch is composed of 5% by weight of ^® Tinuvin 1577 as active ingredient and 95% by weight of the polyethylene terephthalate from Example 1.

Before the extrusion, 80% by weight of the polyethylene terephthalate from Example 1 and 20% by weight of the masterbatch are dried at 1 70 ° C. for 5 hours. The extrusion and sheet production take place analogously to Example 1.

The transparent, amorphous PET sheet produced has the following property profile:

3 mm thick

Surface gloss 1. Page 194

(Measuring angle 20 °) 2nd page 193

Light transmission 91.3%

Clarity 100%

Turbidity 1.4%

No surface defects

(Specks, orange peel, blisters, etc.)

Charpy impact strength a _n no break

Notched impact strength a _k acc. To Izod: 4.0 kJ / m Cold formability good

Crystallinity o%

Density 1.33 g / crrr

3 mm thick

Surface gloss 1. Page 1 92

(Measuring angle 20 °) 2nd page 1 90

Light transmission 91.1%

Clarity 100%

Turbidity 1.5%

Total discoloration ΔE 0.24

Dark discoloration ΔL -0, 1 9

Red-green discoloration ΔA -0.08

Blue-yellow discoloration ΔB 0, 1 2

No surface defects

(Cracks, embrittlement)

Yellowness index G

Charpy impact strength a _n no break

Notched impact strength a _k according to Izod 4.0 kJ / m ²

Cold formability good

Example 3:

Analogous to Example 1, a transparent, amorphous plate is produced, with a

Polyethylene terephthalate is used, which has the following properties:

SV (DCE) 1 100 IV (DCE) 0.85 dl / g density 1.38 g / crτr Crystallinity 44%

Crystallite melting point T _m 245 ° C crystallization temperature range T _c 82 ^D C to 245 ° C post (cold) crystallization temperature T _CN : 152 ° C polydispersity M _w / M _n : 2.02

Glass transition temperature: 82 ³ C

A 6 mm thick, transparent, amorphous plate is produced which, as the main constituent, contains the polyethylene terephthalate described and 0.6% by weight of the UV stabilizer 2,2'-methylene-bis- (6- (2H-benzotriazole-2- yl) -4- (1, 1, 3,3-tetramethylbutyD-phenol (^ Tinuvin 360 from Ciba-Geigy), based on the weight of the polymer.

Tinuvin 360 has a melting point of 1 95 ° C and is thermally stable up to approx. 250 ° C.

As in Example 1, 0.6% by weight of the UV stabilizer is incorporated directly into the polyethylene terephthalate at the raw material manufacturer.

The extrusion temperature is 280 ° C. The first calender roll has a temperature of 66 ° C and the subsequent rolls have a temperature of 60 ° C. The speed of the take-off and the calender rolls is 2.9 m / min.

The transparent PET sheet produced has the following property profile:

Thickness 6 mm

Surface gloss 1. Page 1 75

(Measuring angle 20 °) 2. Page 1 73

Light transmission 88.6%

Clarity 99.6%

Turbidity 2.5% No surface defects per irr

(Specks, orange peel, blisters, etc.)

Charpy impact strength a _n no break

Notched impact strength a _k according to Izod 4.8 kJ / m ²

Cold formability good, no defects

Crystallinity 0%

Density 1.33 g / cm ³

Thickness 6 mm

Surface gloss 1. Page 1 71

(Measuring angle 20 °) 2nd page 1 69

Light transmission 88.3%

Clarity 99.5%

Turbidity 2.7%

Total discoloration ΔE 0.56

Dark discoloration ΔL -0.21

Red-green discoloration ΔA -0, 1 1

Blue-yellow discoloration ΔB + 0.51

No surface defects

(Cracks, embrittlement)

Yellowness index G

Charpy impact strength a _n no break

Notched impact strength a _k according to Izod 4.6 kJ / m ²

Cold formability good, no defects Example 4:

Analogous to example 3, a transparent, amorphous plate is produced. The extrusion temperature is 275 ° C. The first calender roll has a temperature of 57 ° C and the subsequent rolls have a temperature of 50 ° C. The speed of the take-off and the calender roll is 1.7 m / min. The plate is stabilized as described in Example 3.

The PET sheet produced has the following property profile:

Thickness 10 mm

Surface gloss 1. Page 163

(Measuring angle 20 °) 2nd page 161

Light transmission 86.5%

Clarity 99.2%

Turbidity 4.95%

Surface defects per m ² none

(Specks, orange peel, blisters, etc.)

Charpy impact strength a _n no break

Notched impact strength a _k acc. To Izod 5, 1 kJ / m ²

Cold formability good, no defects

Crystallinity 0.1%

Density 1.33 g / cm ³

Thickness 10 mm

Surface gloss 1. Page 160 (measuring angle 20 °) 2nd Page 159 Light transmission 86.2% Clarity 99.1% Turbidity 5.0%

Total discoloration ΔE 0.47

Dark discoloration ΔL -0, 1 8

Red-green discoloration ΔA -0.09

Blue-yellow discoloration ΔB + 0.42

No surface defects

(Cracks, embrittlement)

Yellowness index G

Charpy impact strength a _n no break

Notched impact strength a _k according to Izod 4.5 kJ / m ²

Cold formability good, no defects

Comparative Example 1:

Analogous to example 1, a transparent, amorphous plate is produced. In contrast to example 1, the plate contains no UV stabilizer. The polyethylene terephthalate used, the extrusion parameters, the process parameters and the temperatures are chosen as in Example 1.

The transparent PET sheet produced has the following property profile:

3 mm thick

Surface gloss 1. Page 200

(Measuring angle 20 °) 2nd page 198

Light transmission 91.4%

Clarity 100%

Turbidity 1.3%

Surface defects per m ² none

(Specks, orange peel, blisters, etc.)

Charpy impact strength a _n no break

Notched impact strength a _k according to Izod 4.3 kJ / m ²

Cold formability: good, no defects Crystallinity 0% density 1.33 g / cnv

3 mm thick

Surface gloss 1st page 98

(Measuring angle 20 °) 2nd page 95

Light transmission 79.5%

Clarity 81.2%

Turbidity 7.8%

Total discoloration ΔE 3.41

Dark discoloration ΔL -0.29

Red-green discoloration ΔA -0.87

Blue-yellow discoloration ΔB + 3.29

Surface embrittlement defects

(Cracks, embrittlement)

Yellowness index G 17

Impact strength a _n according to Charpy complete break at 34.8 U / m ²

Notched impact strength a _k acc. To Izod 1, 3 U / m ² cold formability crack formation

Visually, the plate shows a clearly visible "yellow" discoloration. The surfaces are dull and brittle.

Comparative Example 2:

Analogous to example 3, a transparent, amorphous plate is produced. In contrast to Example 3, the plate produced does not contain a UV stabilizer. The polyethylene terephthalate used, the extrusion parameters, the Process parameters and the temperatures are chosen as in Example 3.

The transparent PET sheet produced has the following property profile:

Thickness: 6 mm

Surface gloss 1. Page 1 80

(Measuring angle 20 °) 2nd page 1 78

Light transmission: 88.9%

Clarity 99.6%

Turbidity 2.3%

Surface defects per m ² none

(Specks, orange peel, blisters, etc.)

Charpy impact strength a _n no break

Notched impact strength a _k according to Izod 4.8 U / m ²

Cold formability good, no defects

Crystallinity 0%

Density 1.33 g / cm ³

Thickness 6 mm

Surface gloss 1. Page 91

(Measuring angle 20 °) 2.page 87

Light transmission 72.5%

Clarity 78.3%

Turbidity 1 2.9%

Total discoloration ΔE 3.61

Dark discoloration ΔL -0.26

Red-green discoloration ΔA -0.91

Blue-yellow discoloration ΔB + 3.48 Surface defects embrittlement, cracks

(Cracks, embrittlement)

Yellowness index G 1 8

Impact strength a _n according to Charpy complete break at

46.2 U / m '

Notched impact strength a _k acc. To Izod 1.6 kJ / πV Cold formability Cracking

Visually, the plate shows a clearly visible "yellow" discoloration. The surfaces are badly attacked (blunt, brittle, cracking).

Comparative Example 3:

Analogously to Example 3, a UV-stabilized, transparently colored, translucent plate is produced, the polyethylene terephthalate, the UV stabilizer and the masterbatch from Example 3 also being used. The first calender roll has a temperature of 83 ° C and the subsequent rolls each have a temperature of 77 ° C.

The plate produced is extremely cloudy and almost opaque. The light transmission, the clarity and the gloss are significantly reduced. The plate shows surface defects and structures. The optics are unacceptable for a transparent application.

The plate produced has the following property profile:

Thickness 6 mm

Surface gloss 1. Page 86

(Measuring angle 20 °) 2nd page 88

Light transmission 8%

Clarity is not measurable

Turbidity cannot be measured Surface defects per nrr bubbles, orange peel

(Specks, orange peel, blisters, etc.

Charpy impact strength a _n no break

Notched impact strength a _k according to Izod 5.0 U / m ²

Cold formability good

Crystallinity approx. 8%

Density 1.34 g / cm ³

Because of the unacceptable appearance, the 6 mm plate was not subjected to any weathering test.

Claims

Claims:

1 . Transparent, amorphous plate with a thickness in the range from 1 to 20 mm, which contains a crystallizable thermoplastic as the main component, characterized in that it contains at least one UV stabilizer as a light stabilizer.

2. Plate according to claim 1, characterized in that the concentration of the UV stabilizer is in the range of 0.01 to 5 wt .-%, based on the weight of the crystallizable thermoplastic.

3. Plate according to claim 1 or 2, characterized in that the UV stabilizer is selected from 2-hydroxybenzotriazoles and triazines.

4. Plate according to claim 3, characterized in that as a UV stabilizer at least one compound selected from 2- (4,6-diphenyl-1, 3,5-triazin-2-yl) -5- (hexyl) oxy-phenol and 2,2'-methylene-bis (6- (2H-benzotriazol-2-yl) -4- (1, 1, 3,3-tetramethylbutylD-phenol.

5. Plate according to one of the preceding claims, characterized in that the surface gloss, measured according to DIN 67530 (measuring angle 20 °), is greater than 1 20.

6. Plate according to one of the preceding claims, characterized in that the light transmission, measured according to ASTM D 1003, is more than 84%.

7. Plate according to one of the preceding claims, characterized in that the haze, measured according to ASTM D 1 003, is less than 1 5%.

8. Plate according to one of the preceding claims, characterized in that the crystallizable thermoplastic has a crystallinity which is in the range from 5 to 65%.

9. Plate according to one of the preceding claims, characterized in that the crystallizable thermoplastic is selected from polyethylene terephthalate, polybutylene terephthalate, a cycloolefin polymer and a cycloolefin copolymer.

10. Plate according to claim 9, characterized in that polyethylene terephthalate is used as the crystallizable thermoplastic.

1 1. Plate according to claim 10, characterized in that the polyethylene terephthalate contains polyethylene terephthalate recyclate.

12. Plate according to claim 10 or 1 1, characterized in that when measuring the impact strength a _n according to Charpy, measured according to ISO 1 79/1 D, no breakage occurs.

13. Plate according to one of claims 1 0 to 1 2, characterized in that the notched impact strength a _k according to Izod, measured according to ISO 1 80/1 A, is in the range from 2.0 to 8.0 U / m ² .

14. Plate according to one of claims 1 0 to 1 3, characterized in that the image sharpness, measured according to ASTM D 1003 at an angle less than 2.5 °, is over 96%.

1 5. Plate according to one of claims 10 to 14, characterized in that the polyethylene terephthalate has a crystallite melting point, measured by DSC with a heating rate of 10 ° C / min., In the range of 220 ° to 280 ° C.

16. Plate according to one of claims 10 to 1 5, characterized in that the polyethylene terephthalate has a crystallization temperature, measured by DSC with a heating rate of 10 ° C / min., In the range from 75 ° to 280 ° C.

17. Plate according to one of claims 10 to 16, characterized in that the polyethylene terephthalate used has a standard viscosity SV (DCE), measured in dichloroacetic acid according to DIN 53728, which is in the range from 800 to 1800.

18. A method for producing a transparent, amorphous plate according to one of claims 1 to 17, characterized in that the crystallizable thermoplastic is melted in the extruder together with the UV stabilizer, the melt is shaped by a nozzle and then in the smoothing unit with at least two rollers calibrated, smoothed and cooled before the plate was made to measure, the first roller of the smoothing unit having a temperature in the range from 50 to 80 ° C.

19. The method according to claim 18, characterized in that the crystallizable thermoplastic is dried in the extruder before melting.

20. The method according to claim 18 or 19, characterized in that the crystallizable thermoplastic is polyethylene terephthalate.

21. Process according to claim 20, characterized in that the polyethylene terephthalate is dried for 4 to 6 hours at 160 to 180 ° C before extrusion.

22. The method according to claim 20 or 21, characterized in that the temperature of the PET melt is in the range of 250 to 320 ° C.

23. The method according to any one of claims 20 to 22, characterized in that the addition of the UV stabilizer is carried out via the masterbatch technology.

23. Use of a transparent, amorphous plate according to at least one of claims 1 to 17 outdoors.