EP0853543A1

EP0853543A1 - Amorphous moulding from a polyethylene terephthalate plate

Info

Publication number: EP0853543A1
Application number: EP96933400A
Authority: EP
Inventors: Ursula Murschall; Rainer Brunow
Original assignee: Hoechst Research and Technology Deutschland GmbH and Co KG
Current assignee: Aventis Research and Technologies GmbH and Co KG
Priority date: 1995-10-05
Filing date: 1996-09-26
Publication date: 1998-07-22
Also published as: DE19537107A1; CA2233988A1; BR9611159A; HUP9900082A2; JPH11512667A; NO981385L; BG102356A; AU7214996A; MX9802731A; KR19990064018A; NO981385D0; HUP9900082A3; OA10677A; CN1198705A; CZ103198A3; PL325993A1; TR199800638T1; WO1997012750A1

Abstract

The present invention relates to an amorphous, thermoformed moulding, with a thickness in the range of from 1 to 20 mm, which as the main component contains a crystallisable polyethylene terephthalate and is characterised by good mechanical and good optical properties. The moulding can optionally be transparent, dyed to be translucent or dyed to be opaque. In a preferred embodiment, it is also UV-stabilised. The invention also relates to a method for the production of said moulding, and use thereof.

Description

description

Amorphous molded body made of a polyethylene terephthalate plate

The invention relates to a process for the production of amorphous molded articles from amorphous polyethylene terephthalate plates and to the amorphous molded articles themselves. The molded articles can optionally be colored transparent, transparent or opaque. In addition to good optical properties, the shaped articles are distinguished by good mechanical properties.

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 that are processed into sheets are, for example, 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. 1 36, Georg Thieme Verlag, Stuttgart, 1 984). 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 before cooling in the calibration plant. In the case of easily decomposable materials such as PVC, special processing aids such as processing stabilizers against decomposition and lubricants against excessive internal friction and thus uncontrollable heating are necessary for extrusion. Outer lubricants are required for this Prevent getting caught on walls and rollers

When processing PMMA, e.g. A degassing extruder was used to remove moisture.

In the production of transparent plates from amorphous thermoplastics, costly additives are required, which migrate and can lead to production problems due to evaporation and to 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.

PMMA and PC boards absorb moisture. The moisture content increases during production, during transport and during storage. The performance of the extruded sheet is not impaired, but during forming (thermoforming and vacuum forming) bubbles and other surface defects and loss of properties occur due to the increased moisture. Before mechanical forming, these plates must be dried in a forced air oven at temperatures above 1 20 ° C, depending on the plate thickness, between 1 hour and 48 hours (see technical information Handbook GE Plastics Structured Products, Solid Lexan ^® sheets), which is energy and time consuming.

German patent application 1 95 22 1 1 8.4 (state of the art according to § 3 II PatG) describes an amorphous, transparent plate with a thickness in the range from 1 to 20 mm, which contains a thermosetable thermoplastic as the main component and is characterized in that that it contains at least one UV stabilizer as a light stabilizer. In addition to the high UV stability, the plate is characterized by good optical properties such as high light transmission, high surface gloss, low haze and high image sharpness, as well as good mechanical properties such as high impact strength and high breaking strength out

German patent application 1 95 22 120.6 (state of the art according to § 3 II PatG) describes an amorphous, transparently colored, UV-stabilized plate made of a thermoplastic that can be crystallized and whose thickness is in the range from 1 to 20 mm. The plate contains at least one UV stabilizer as a light stabilizer and at least one polymer-soluble dye. In addition to high UV stability, the plate is characterized by good optical and good mechanical properties

German patent application 1 95 22 1 1 9.2 (state of the art according to § 3 II PatG) discloses an amorphous, colored, UV-stabilized plate made of a installable 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 at least one organic and / or inorganic pigment as a colorant. In addition to the high UV stability, the plate is characterized by homogeneous optical and good mechanical properties. EP-A-0 471 528 describes a method for molding an article from a polyethylene terephthalate (PET) plate. The PET sheet is heat-treated on both sides in a deep-drawing mold 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 body produced from this PET sheet has a high degree of crystallization, there is no possibility of obtaining a transparent object. The molded body is always opaque. In addition, the deep-drawn molded body has poor mechanical properties, in particular poor impact resistance, due to the crystallization.

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%. However, the crystallinity of the deep-drawn molded body is greater than 25%. Since the plate described and the molded body drawn therefrom are partially crystalline, there is also no possibility of obtaining a transparent object or a transparent plate. In addition, both the plate and the molded body drawn therefrom show poor mechanical properties, in particular low impact strength, owing to the crystallization.

Processes for the production of transparent or transparent moldings from amorphous or semi-crystalline PET sheets with a thickness of up to 6 mm by vacuum deep drawing are also described in Austrian Patent Nos. 304 086 and 285 1 60.

However, the PET used in AT-PS No. 304 086 is a so-called glycol-modified PET (PET-G), i.e. a copolymer of ether and ester units. PET-G is naturally amorphous and is difficult to crystallize. In addition, the PET used here has one Crystallization temperature - corresponding to the post (cold) crystallization temperature T _CN - of at least 1 60 ° C.

According to AT-PS No. 285 1 60, a PET plate with a thickness of 3 mm was used, which had a degree of crystallization of 21%. The molded body obtained therefrom consequently at least partially crystalline and therefore no longer transparent.

It was therefore an object of the present invention to provide deep-drawn, that is to say thermoformed, shaped articles which can optionally be colored transparently, transparently or opaque, whose thickness is in the range from 1 to 20 mm and whose optical and mechanical properties are essentially those of amorphous polyethylene terephthalate. Plates match.

The good mechanical properties include, in particular, high impact strength and high breaking strength.

In the transparent or transparent colored embodiment, the good optical properties include, for example, high light transmission and a homogeneous appearance.

In addition, the molded body according to the invention should be recyclable, economically producible and flame-retardant, so that it can also be used for indoor applications, for example.

In a special embodiment, the shaped body should also be UV-resistant so that it is suitable for outdoor applications.

This object is achieved by a method for producing an amorphous shaped body, which is characterized in that an amorphous plate with a thickness in the range from 1 to 20 mm, preferably in the range from 1 to 10 mm, which contains crystallizable polyethylene terephthalate as the main component, heated, thermoformed, cooled and then removed from the mold.

Amorphous plates, with a thickness in the range from 1 to 20 mm, which contain crystallizable polyethylene terephthalate as the main constituent, which are suitable as starting materials for the process according to the invention, and their production are described, for example, in German patent applications 195 19 579.5, 195 1 9 578.7, 1 95 19 577.9, 195 22 1 1 8.4, 195 22 1 20.6, 195 22 1 1 9.2, 1 95 28 336.8, 1 95 28 334.1 and 195 28 333.3.

According to the invention, crystallizable polyethylene terephthalate means crystallizable polyethylene terephthalate homopolymers, crystallizable polyethylene terephthalate copolymers, crystallizable polyethylene terephthalate compounds, crystallizable polyethylene terephthalate recyclate and other variations of crystallizable polyethylene terephthalate.

Preferred starting materials for the production of the amorphous plate are polyethylene terephthalate polymers with a post (cold) crystallization temperature T _CN in the range from 1 20 to 1 58 ° C., in particular from 130 to 1 58 ° C.

For the purposes of the present invention, amorphous plates are understood to mean those plates which, although the crystallizable thermoplastic used preferably has a crystallinity of between 25 and 65%, are not crystalline. Not crystalline, i.e. essentially amorphous means that the degree of crystallinity is generally below 5%, preferably below 2% and particularly preferably 0%.

In contrast to plates made of conventional materials, such as. B. polymethyl methacrylate (PMMA) and polycarbonate (PC), need plates that contain crystallizable polyethylene terephthalate as the main component in generally not to be dried before thermoforming, ie thermoforming, but can be processed directly without the usual preparatory steps.

The heating or heating of the plate can be carried out with all heating devices known to the person skilled in the art for deep drawing. Hot air ovens or infrared heaters are preferably used for heating the plate.

In order to achieve the fastest possible or uniform heating of the plate, it is preferably on both sides, i. H. heated with top and bottom heat.

The plate is preferably heated until the plate temperature is in the range from 120 ° to 160 ° C., preferably in the range from 130 ° to 145 ° C.

When using large-area plates, the plates may sag when heating up. In this case, the plates are preferably supported by compressed air during heating.

Typical heating times for transparent plates that contain polyethylene terephthalate as the main component are, for example, about 1/3 of the time required for PMMA and PC plates.

Deviations can occur depending on the type and efficiency of the existing heating. Colored plates may have additional time deviations due to the different heat absorption behavior.

Forming, also called thermoforming or deep drawing, takes place after the heating. The heated plates used can how other materials are thermoformed in standard processes.

In order to ensure a uniform distribution of the thickness over the entire material during the thermoforming process, the usual measures can be used, such as varying the temperature profile of the plate, targeted vacuum settings or inflating a dome as a preliminary stage for molding.

In addition, for the production of an amorphous shaped body, it is advantageous if the temperature of the tool is kept below 80 ° C., preferably below 60 ° C.

Furthermore, the time between the end of the heating period and the completion of the molding process should be kept short. Therefore, a tool design with a maximum number of ventilation holes and a maximum diameter (for example 1 mm) is recommended.

After completing the molding process, the molded part should be quickly cooled with air or air / spray water.

The subsequent demolding preferably takes place only when the molded part has a temperature below 60 ° C.

Due to the low and uniform shrinkage, which is preferably <1.0%, the molded part can be removed from the tool without any problems. The molded part does not shrink over time. The molded part remains dimensionally stable.

Another object of the invention is an amorphous, thermoformed molded body with a thickness in the range from 1 to 20 mm, which contains a crystallizable polyethylene terephthalate as the main component, the characterized in that the surface gloss measured according to DIN 67530 (measuring angle 20 °) is greater than 90, preferably greater than 100.

For the purposes of the present invention, amorphous shaped bodies are understood to mean those shaped bodies whose crystallinity is generally below 5%, preferably below 2% and particularly preferably 0%.

The moldings of the invention have not broken in the measurement of impact strength a _n Charpy (measured according to ISO 179/1 D) preferably.

In addition, the notched impact strength a _k according to Izod (measured according to ISO 180/1 A) of the shaped bodies is preferably in the range from 3.0 to 8.0 kJ / m ² , particularly preferably in the range from 4.0 to 6.0 kJ / m ² .

The amorphous, thermoformed molded body can optionally be transparent, colored or opaque.

In the transparent embodiment, the deep-drawn molded body according to the invention has a light transmission, measured according to ASTM D 1003, of more than 80%, preferably more than 84%.

The haze of the shaped body, measured in accordance with ASTM D 1003, is less than 15%, preferably less than 11%, and the image sharpness of the shaped body, which is also called Clarity, and is determined at an angle of less than 2.5 ° (ASTM D 1003) is preferably above 94% and particularly preferably above 96%.

In the transparent colored embodiment, in which the shaped body contains at least one dye soluble in polyethylene terephthalate, preferably in a concentration of 0.001 to 20% by weight, based on the Weight of the crystallizable polyethylene terephthalate, the light transmission measured according to ASTM D 1003 is in the range from 5 to 80%, preferably in the range from 10 to 70%.

The haze of the shaped body, measured according to ASTM D 1003, is in the range from 2 to 40%, preferably in the range from 3 to 35%, and the image sharpness of the shaped body, which is also called Clarity, and is determined at an angle of less than 2.5 ° (ASTM D 1003), is preferably above 90% and particularly preferably above 92%.

In the opaque colored embodiment, in which the shaped body contains at least one organic and / or inorganic pigment as colorant and, if appropriate, additionally a soluble dye, the concentration of the pigment preferably being in the range from 0.5 to 30% by weight, based on the weight of the crystallizable polyethylene terephthalate, the light transmission, measured according to ASTM D 1003, is less than 5%.

Suitable soluble dyes are disclosed, for example, in German patent application 195 19 578.7 and suitable organic and / or inorganic pigments as colorants are disclosed, for example, in German patent application 195 19 577.9.

In a preferred embodiment, the amorphous, thermoformed molded body has at least one UV stabilizer as light stabilizer, the concentration of the UV stabilizer preferably being in the range from 0.01 to 5% by weight, based on the weight of the crystallizable polyethylene terephthalate.

Suitable UV stabilizers as light stabilizers are disclosed, for example, in German patent applications 195 22 1 1 8.4, 1 95 22 1 20.6 and 1 95 22 1 19.2. Furthermore, measurements showed that the molded part according to the invention is flame-retardant and flame-retardant, so that it is also suitable for indoor applications and in exhibition stand construction.

Furthermore, the molded part 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.

Due to the surprising variety of excellent properties, the amorphous molded part according to the invention is outstandingly suitable for a large number of different uses, for example for interior cladding, for trade fair construction and trade fair items, for signs, for protective glazing of machines and vehicles, in shop and shelf construction, as promotional items, as menu card stands , as a basketball target board, as a room divider, for aquariums and as a brochure and newspaper rack.

In the UV-stabilized embodiment, the amorphous molding according to the invention is also suitable for outdoor applications, such as for greenhouses, roofing, glazing, safety glasses, outer cladding, covers, for applications in the construction sector, illuminated advertising profiles, balcony cladding, roof hatches and caravan windows.

In addition, it was surprisingly found that the amorphous, deep-drawn molded parts according to the invention have good mechanical properties even at low temperatures down to -40 ° C., without any loss of optical properties. The good mechanical properties include high breaking strength, high impact strength, excellent tensile and excellent bending behavior. The molded parts according to the invention can therefore also be used advantageously in cooling systems.

Examples of cooling systems or cooling systems are electric refrigerators and freezers for household and commercial use, compressor refrigerators, cooling systems for milk, refrigerated display cases, blood bank refrigerators, mortuary cooling systems, medical cooling devices and laboratory freezers.

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 determined in accordance with DIN 67 530. The reflector value is measured as the optical core size for the surface of a plate. Based on the standards ASTM-D 523-78 and ISO 2813, the angle of incidence is set at 20 °. A light beam hits the flat test surface at the set angle of incidence and is reflected or scattered by it. The light rays striking the photoelectric receiver are displayed as a proportional electrical quantity. The measured value is dimensionless and must be specified together with the angle of incidence.

Light transmission:

Under light transmission is the ratio of the total let through

To understand light to the incident amount of light.

The light transmission is carried out with the "Hazegard plus" measuring device according to ASTM D 1003 measured.

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.

Whiteness

The degree of whiteness is determined using the electrical reflectance photometer "ELREPHO" from Zeiss, Oberkochem (DE), standard illuminant C, 2 ° normal observer. The whiteness is defined as

WG = RY - (- 3RZ - 3RX.

WG = whiteness, RY, RZ, RX = corresponding reflection factors when using the Y, Z and X color measurement filter. A barium sulfate compact (DIN 5033, part 9) is used as the white standard.

Surface defects:

The surface defects are determined visually.

Impact strength according to Charpy:

This size is determined according to ISO 179/1 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 180/1 A. Density:

The density is determined according to DIN 53479.

SV (DCE), IV (DCE):

The standard viscosity SV (DCE) is based on DIN 53728 in

Dichloroacetic acid measured.

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

IV (DCE) = 6.67 • 10 ^"4 SV (DCE) + 0.118

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 using 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 4982 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 mm

Temperature 63 ° C Relative humidity 50% xenon lamp inner and outer filter made of borosilicate

Irradiation cycle 102 minutes of UV light, then 18 minutes of UV light with water spraying the samples, then again 102 minutes of UV light, etc.

The examples and comparative examples below are each single-layer sheets which are produced on the extrusion line described in the above-mentioned German patent applications.

Example 1 :

An amorphous, transparent plate made of a crystallizable polyethylene terephthalate, the production of which is described in German patent application 195 35 1 80.0, with the following property profile:

4 mm thick

Surface gloss 1. Page 178

(Measuring angle 20 °) 2nd page 1 72

Light transmission 89.4%

Clarity 99.7%

Turbidity 2.1%

Surface defects per m ² none

Crystallinity 0%

Density 1.33 g / cm '

Charpy impact strength a _n at 23 ° C no break

Izod impact strength a _k at 23 ° C 4.7 kJ / m ²

is thermoformed on the Illig / Heilbronn type UA 100 g vacuum thermoforming machine with the following parameters: - plate size 10OO mm x 700 mm

- Panel thickness 4 mm

- Mold area 960 mm x 660 mm

- Deep drawing height 200 mm

- Predrying 0 min (not necessary)

- Mold temperature 50 ° C

- Radiator output top heating 65%

- Radiator output underheating 45%

- Preheating with upper and lower heating / deep drawing 38 sec

- vacuum yes

- temperature of the plate 140 ° C

- Cooling with spray water 40 sec

- The temperature of the molded object when removed from the tool is 50 ° C

The total deep-drawing cycle time is only 78 seconds.

The molded article has the following properties:

Color transparent

Light transmission 87.8% haze 3.4%

Surface gloss 1. Side 1 50 (measuring angle 20 °) 2nd side 1 62 Shrinkage / shrinkage 0.5% Density 1.33 g / cm ³ Crystallinity 0%

Charpy impact strength a _n at 23 ° C no break Izod impact strength a _k at 23 ° C 4.7 kJ / m ² ^■ Charpy impact strength a _n at -40 ° C 78 kJ / m ² - Izod impact strength a _k at -40 ° C 2.4 kJ / m "

Example 2

Analogously to Example 1, an amorphous, transparent plate made of a crystallizable polyethylene terephthalate, the 0.6 wt .-% of the UV stabilizer

2,2'-methylene-bis- (6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol

( ^φ Tinuvin 360 from Ciba-Geigy), based on the weight of the polymer, contains deep-drawn.

The UV-stabilized plate has the following property profile:

4 mm thick

Surface gloss 1. Page 1 76

(Measuring angle 20 °) 2nd page 174

Light transmission 89.1%

Clarity 99.5%

Turbidity 2.3%

Surface defects per m ² none

Crystallinity 0%

Density 1.33 g / cm ³

Charpy impact strength a _n at 23 ° C no break

Izod impact strength a _k at 23 ° C 4.6 kJ / m ²

The deep-drawing parameters, the temperatures and the deep-drawing cycle time are selected as in Example 1.

The shaped, UV-stabilized object has the following properties:

Color transparent

Light transmission 86.9%

Turbidity 3.6% - Surface gloss 1. Page 148 (measuring angle 20 °) 2.page 1 59

- shrinkage / shrinkage 0.5%

- density 1.33 g / cm '

- crystallinity 0%

- Charpy impact strength a _n at 23 ° C no break

- Izod impact strength a _k at 23 ° C 4.5 kJ / m ²

- Charpy impact strength a _n at -40 ° C 79 kJ / m ²

- Izod impact strength a _k at -40 ° C 2.2 kJ / m ²

Example 3:

Analogously to Example 1, an amorphous, red-transparent colored plate made of a crystallizable polyethylene terephthalate, which contains 2% by weight of the soluble dye Solventrot 1 38, an anthraquinone derivative from BASF ( ^® Thermoplast G), based on the weight of the polymer , deep drawn.

The red-transparent colored plate has the following property profile:

Thickness 2 mm

Color red-transparent

Surface gloss I. Page 1 30

(Measuring angle 20 °) 2. Page 1 27

Light transmission 35.8%

Clarity 99, 1%

Turbidity 3.5%

Surface defects per m ² none

Charpy impact strength a _n at 23 ° C no break

Izod impact strength a _k at 23 ° C 4, 1 kJ / m ² Crystallinity 0% density 1.33 g / cm '

The deep-drawing parameters and temperatures are chosen as in Example 1. Due to the lower plate thickness, the deep-drawing cycle time is only 37 seconds, whereby 17 seconds are required for preheating with top and bottom heat and for a deep-drawing process, and 20 seconds for cooling with spray water.

The molded article has the following properties:

- Color red-transparent

- light transmission 34.9%

- turbidity 3.8%

- Surface gloss 1. Page 1 1 8 (measuring angle 20 °) 2.Page 1 26

- shrinkage / shrinkage 0.4%

- density 1.33 g / cm ³

- crystallinity 0%

- Charpy impact strength a _n at 23 ° C no break

- Izod impact strength a _n at 23 ° C 4.0 kJ / m ²

- Charpy impact strength a _n at -40 ° C 69 kJ / m ²

- Izod impact strength a _n at -40 ° C 2.0 kJ / m ²

Example 4:

Analogously to Example 1, an amorphous, white-colored plate made of a crystallizable polyethylene terephthalate, which contains 6% by weight of titanium dioxide, based on the weight of the polymer, is deep-drawn. The titanium dioxide is of the rutile type and is coated with an inorganic coating made of Al ₂ O ₃ and with an organic coating made of polydimethylsiloxane. The titanium dioxide has an average particle diameter of 0.2 μm.

The white colored plate has the following property profile:

Thickness 5 mm

Coloring white

Surface gloss 1. Page 1 19

(Measuring angle 20 °) 2.page 1 17

Light transmission 0%

Whiteness 1 20

Surface defects per m ² none

Charpy impact strength a _n at 23 ° C no break

Izod impact strength a _k at 23 ° C 4.9 kJ / m ²

Crystallinity 0%

The deep-drawing parameters and temperatures are chosen as in Example 1. Due to the higher plate thickness and the heat absorption behavior due to the white color, the deep-drawing cycle time is 95 seconds, with preheating with top and bottom heat and the deep-drawing process 50 seconds and cooling with spray water for 45 seconds.

The molded article has the following properties:

color white

Light transmission 0% surface gloss 1. Page 108 (measuring angle 20 °) 2. Page 1 13 whiteness 1 18 shrinkage / shrinkage 0.6% - crystallinity 0%

- Charpy impact strength a _n at 23 ° C no break

- Izod impact strength a _k at 23 ° C 4.8 kJ / m ²

- Charpy impact strength a _n at -40 ° C 88 kJ / m ²

- Izod impact strength a _k at -40 ° C 2.4 kJ / m ²

Comparative Example 1:

Analogously to Example 1, a transparent, amorphous PMMA plate from Röhm ( ^® Plexiglas GS) is deep-drawn.

The PMMA board has the following property profile:

4 mm thick

Surface gloss 1. Page 1 38

(Measuring angle 20 °) 2nd page 1 36

Light transmission 93.8%

Clarity 99.8%

Turbidity 0.5%

Surface defects per m ² none

Density 1.19 g / ciτr

Charpy impact strength a _n at 23 ° C 1 6 kJ / m ²

Izod impact strength a _k at 23 ° C 1.5 kJ / m ²

With the deep-drawing parameters, temperatures and deep-drawing cycle times analogous to Example 1, it is not possible to produce a shaped article.

The 4 mm thick PMMA plate can only be thermoformed under the following, significantly more uneconomical conditions.

- Panel size: 1000 mm x 700 mm

- Panel thickness 4 mm Mold area 960 mm x 660 mm

Deep drawing height 200 mm

Predry 10 hours at 1 25 ° C

Mold temperature 50 ° C

Radiator output top heating 75%

Radiator output underheating 65%

Preheating with top and bottom heating /

Thermoforming 89 sec

Vacuum yes

Plate 1 temperature 80 ° C

Cooling with spray water 70 sec

Molded object temperature when removed from the tool 50 ° C

The thermoforming cycle time for molding an object is considerably longer at 1 59 seconds, which greatly reduces productivity in today's continuously working thermoforming machines compared to the amorphous molded body made from a PET sheet. In addition, the plate must have a significantly higher temperature during deep drawing, so that the energy costs are higher in comparison to the amorphous molded body made of PET. In particular, it is necessary to dry the plate in a special oven at temperatures above 100 ° C. for several hours before the deep-drawing process in order to remove the water taken up. The total amount of air in the furnace must be exchanged about six times an hour so that the water vapor can escape. Without pre-drying, the molded body made of the PMMA sheet shows unacceptable surface defects as a result of the stored water.

The molded body produced from the pre-dried PMMA sheet with a significantly higher deep-drawing cycle time has the following properties:

Color transparent Light transmission 90.1%

Turbidity 2.3%

Surface gloss 1. Page 1 12

(Measuring angle 20 °) 2nd page 120

Shrinkage / shrinkage 3%

Density 1.19 g / cm ³

Crystallinity 0%

Charpy impact strength a _n at 23 ° C 1 5 kJ / m ²

Izod impact strength a _k at 23 ° C 1 .4 kJ / m ²

Charpy impact strength a _n at -40 ° C no reproducible

Izod impact strength a _k at -40 ° C values measurable (strong scatter)

The molded article produced has a significantly higher shrinkage (so-called shrinkage) in comparison to the amorphous PET molded article and significantly worse impact strength and notched impact strength even at room temperature. Furthermore, dangerous, sharp-edged splinters occur when the breakage occurs easily.

Comparative Example 2:

Analogously to Example 1, a transparent, amorphous polycarbonate sheet from GE Plastics ( ^® Lexan 1 21) is deep-drawn.

The PC board has the following property profile:

4 mm thick

Surface gloss 1. Page 1 76

(Measuring angle 20 °) 2. Page 1 74

Light transmission 89%

Clarity 99, 1% Turbidity 0.5%

Surface defects per m ² none

Density 1, 20 g / cm ³

Charpy impact strength a _n at 23 ° C no break

Izod impact strength a _k at 23 ° C 10 kJ / m ²

With the deep-drawing parameters, the low temperatures, the short deep-drawing cycle times and without predrying as in Example 1, it is not possible to produce a shaped article.

The 4 mm thick PC plate can only be thermoformed under the following, much more uneconomical conditions:

Plate size 1000 mm x 700 mm

Board thickness 4 mm

Mold area 960 mm x 660 mm

Deep drawing height 200 mm

Predry 1 1 hours at 1 26 ° C

Mold temperature 70 ° C

Radiator output top heating 80%

Radiator output underheating 80%

Preheating with top and bottom heating /

Deep drawing 85 sec

Vacuum yes

Plate temperature 190 ° C

Cooling with spray water 70 sec

Temperature of the molded article at

Remove from the tool at 70 ° C

Compared to the examples, the deep-drawing cycle time for shaping an object from a PC plate is much longer, which is the case with today's conventional, continuously working thermoforming machines greatly reduces productivity. In addition, the plate for the forming process must have a much higher temperature, which means that the energy costs are higher in comparison to the amorphous PET molded body. As with PMMA, it is also necessary with PC that the plate is pre-dried for several hours at 125 ± 3 ° C in a forced air oven before the deep-drawing process in order to eliminate the water taken up. The total amount of air in the furnace must be exchanged about six times per hour so that the water vapor can escape. Without pre-drying, the object formed from the PC plate has an unacceptable appearance.

The molded body produced from the pre-dried PC plate is much less economical and has the following properties:

Color transparent

Light transmission 87.2%

Turbidity 3.1%

Surface gloss 1. Page 148

(Measuring angle 20 °) 2nd page 1 59

Shrinkage / shrinkage approx. 5%

Density 1, 20 g / cm ³

Crystallinity 0%

Charpy impact strength a _n at 23 ° C without breakage

Izod impact strength a _k at 23 ° C 9 kJ / m ²

Charpy impact strength a _n at -40 ° C no break

Izod impact strength a _k at -40 ° C 5 kJ / m ²

The molded article produced has a significantly higher shrinkage (shrinkage) compared to the amorphous PET molded article. Comparative Example 3:

Analogously to Example 1 of EP-A-0 471 528, a shaped body is produced which has a crystallization of approximately 35%. As described in EP-A-0 471 528, the deep-drawing cycle times are also significantly longer than in the case of the amorphous PET molded body. In addition, the mold must have a temperature of approximately 1 60 ° C for crystallization to occur. Such high tool temperatures cannot be achieved with conventional water heaters. Here you need an oil-heated or electrically heated tool, which due to the high temperature must not be made of epoxy resin or wood, but must be made of aluminum.

The PET molded body with a crystallization of approx. 35% has the following properties:

Color white, as a result of

Crystallization

Light transmission 34% turbidity not measurable due to the initiated

Clarity (sharpness) crystallization

Surface gloss 1. Page 90

(Measuring angle 20 °) 2nd page 98

Shrinkage / shrinkage approx. 6%

Density 1.37 g / cm ³

Crystallinity approx. 35%

Charpy impact strength a _n at 23 ° C 87 kJ / m ²

Izod impact strength a _k at 23 ° C 2.3 kJ / m ²

The PET molded body with a crystallization of approx. 35% is always opaque due to the crystallization. Consequently, no transparent or transparently colored embodiment can be provided. In addition, this molded article also shows a high post-shrinkage (shrinkage) and significantly worse notch impact and impact strength even at room temperature.

Claims

claims

1 . A process for producing an amorphous molded article, characterized in that an amorphous plate with a thickness in the range from 1 to 20 mm, which contains crystallizable polyethylene terephthalate as the main component, is heated, thermoformed, cooled and then removed from the mold.

2. The method according to claim 1, characterized in that the amorphous plate has a thickness in the range of 1 to 10 mm.

3. The method according to claim 1 or 2, characterized in that the plate is heated by means of convection ovens or infrared heaters.

4. The method according to any one of claims 1 to 3, characterized in that the plate is heated until the plate temperature is in the range of 120 to 1 60 ° C.

5. The method according to claim 4, characterized in that the plate is heated until the plate temperature is in the range from 130 ° to 145 ° C.

6. The method according to any one of claims 1 to 5, characterized in that when thermoforming the temperature of the mold below

80 ° C is maintained.

7. The method according to claim 6, characterized in that the temperature of the mold is kept below 60 ° C during thermoforming.

8. The method according to any one of claims 1 to 7, characterized in that the molded body is cooled with air or air / spray water.

9. The method according to any one of claims 1 to 8, characterized in that the molded part is removed from the mold when the temperature of the molded part is below 80 ° C.

10. The method according to claim 9, characterized in that one removes the molded part when the temperature of the molded part is below 60 ° C.

1 1. Process according to Claim 1, characterized in that the polyethylene terephthalate used has a post (cold) crystallization temperature T _CN in the range from 1 20 ° C to 1 58 ° C.

1 2. Amorphous, thermoformed molded body with a thickness in the range from 1 to 20 mm, which contains a crystallizable polyethylene terephthalate as the main component, characterized in that the surface gloss, measured according to DIN 67530 (measuring angle 20 °), is greater than 90.

13. Shaped body according to claim 1 2, characterized in that no break occurs when measuring the impact strength a _n according to Charpy, measured according to ISO 1 79/1 D.

14. Shaped body according to claim 1 2 or 1 3, 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 3.0 to 8.0 kJ / m ² .

1 5. Shaped body according to one of claims 1 2 to 14, characterized in that it is colored transparent, transparent or opaque.

1 6. Shaped body according to one of claims 1 2 to 1 5, characterized in that it has at least one UV stabilizer as a light stabilizer having.

1 7. Shaped body according to claim 16, characterized in that the concentration of the UV stabilizer in the range of 0.01 to 5 wt .-%, based on the weight of the crystallizable polyethylene terephthalate.

18. Shaped body according to claim 12, characterized in that the polyethylene terephthalate used has a post (cold) crystallization temperature in the range of 1 20 ° C to 1 58 ° C.

1 9. Use of an amorphous, thermoformed molded body according to one of claims 1 2 to 1 8 in the interior and exterior and in cooling systems.