CZ20002065A3 - A method for producing a surface-hardened, high-gloss gel-free film free of gel particles, processable by a film-pressing process - Google Patents

Abstract

In the process for producing a surface-hardened, double-sided, high-gloss film that is practically free of gel particles and has a thickness of 80 to 300 μm, a melt, e.g. of polymethyl methacrylate, is produced using an extruder and fed via a flexible lamellar nozzle to a smoothing roll stand that is designed for particularly high contact forces in the roll gap, the smoothing rolls being domed. The films are used for the surface decoration of high-quality thermoplastic molded parts.

Description

Technical field

If injection-molded parts are decorated with printed polymethacrylate (PMMA) films, PMMA films with a thickness of 80 to 300 pm are used to achieve a certain "depth effect" of printing. For decoration, either printed PMMA films, co-laminated with thermoplastic carrier materials, are pre-shaped and embossed into the desired geometry, fed into an injection molding machine and injected, or the printed PMMA film in roll form is fed into an injection molding machine and injected. Injection is carried out on the printed side, so that the print is protected by a PMMA film containing a UV absorber. The following thermoplastics and polymer blends can be used for injection molding: ABS, PC/ABS blends, PVC, PC, PC/ASA blends, PP, PP blends.

For decoration, either printed foil blanks (optionally pre-formed) are inserted into an injection molding machine and injected, or the printed PMMA foil is fed from a roll into an injection molding tool and injected, or the PMMA foil is laminated onto a thermoplastic carrier material and (optionally pre-formed) is fed into an injection molding machine and injected. The following thermoplastics can be used as carrier materials that are laminated with the printed foil according to the invention: ABS, polycarbonate-ABS blends, ASA (acryloester-styrene-acrylonitrile copolymer), polycarbonate-ASA blends, blends containing polyolefins, such as polyethylene, polypropylene, PVC, and blends containing polyphenylene. All thermoplastic materials can be reinforced with glass fibers

-2or mineral fillers.

The PMMA film takes on the function of a protective varnish. In contrast to injection-molded parts, protected with a protective varnish or printed directly or indirectly (thermal transfer, wet transfer), surface decoration with printed PMMA films offers the following advantages:

- significant cost reduction (surface finishing and decoration are done in a single step)

- solvent-free process

- low investment costs and environmental protection costs

- easy replacement of the printed pattern

- greater freedom of choice of pattern.

The decoration of thermoplastic moldings with printed films as part of the injection molding process is generally called "In-mould-film-decoration". The best-known form of this method is the so-called "Insert-Moulding". For this, a decoratively printed PMMA film is co-laminated with a thermoplastic carrier material for reinforcement. ABS, ASA, PC, PVC, PP, PPE and mixtures of these materials are preferably used for this.

The foil laminate is shaped and stamped into the desired geometry using a thermoforming process. The preforms are then fed to the injection molding process for the actual production of the moldings. For this purpose, the preforms are usually automatically fed into an injection molding machine and injected with thermoplastic plastics. ABS, ASA, PC, PVC, PP, PPE, as well as mixtures of these materials are preferably used for injection molding. If a carrier material of sufficient

-3• tt thicknesses, it is possible to avoid spraying and it is possible to use directly preformed, embossed or cut laminate.

“In-Mould-Film-Decoration offers mold makers and mold manufacturers the option of replacing the traditional, costly method, based on very rational process management and the possibility of rapid pattern changes.

PMMA foil printed with transparent, elastic varnishes and sprayed with transparent thermoplastic can be used rationally, for example, for the production of car taillight covers. PMMA molding compounds, SAN, polystyrene molding compounds, polycarbonates and PMMA/SAN blends are preferably used as transparent thermoplastics.

This method offers the possibility of rapid pattern changes without having to build new, expensive multi-component injection molding machines. In addition, the costly coloring of PMMA molding materials for multi-component injection molding is avoided.

“In-Mould-Film-Decoration (decoration by in-moulding foil) enables the production of complete car body parts in this area of application, which can optionally include taillight covers as functional areas.

Optionally, the PMMA film printed with a transparent elastic varnish can be sprayed with transparent, thermoplastic carrier materials to increase rigidity in this application before the production of the molding to protect the varnish against the hot, high-pressure melt of the thermoplastic material used for spraying.

Special, very economical design „In• · • · · · • 8

8

Mould-Film-Decoration uses a combined moulding injection tool, which combines both film moulding and injection moulding in one process using printed films in roll form. This process is generally called “Film-Insert-Molding”.

When using PMMA films to decorate injection molded parts using "Film Insert Molding", high demands are placed on the PMMA film material:

- good manipulability in the printing process, i.e. sufficient ductility

- high surface hardness (at least the hardness of an HB pencil) to prevent scratching of moldings decorated with PMMA foils

- high surface gloss (measured according to DIN 67530) >120

- slight cloudiness due to humidity <2% fogging according to the method described on page 15

- low surface haze <1.5%

- extremely low number of gel particles max. 1 gel particle per 200 cm ²

- high weather resistance; comparable to standard PMMA

- sufficient UV light absorption; UV absorption in the range of 290 to 370 nm <1%.

State of the art

DE 38 42 796 (Rohm GmbH) describes PMMA-films based on

PMMA molding compounds with small elastomer particle size and high elastomer content. The films according to the invention are not,

-5 with regard to the parameter "surface hardness, producible from this molding compound.

WO 96/30435 and EP 763 560 (Mitsubishi Rayon) describe the production of PMMA films with a thickness of up to 0.3 mm, based on a specific PMMA composition: an impact modifier based on polybutyl acrylate with a specific particle diameter, a PMMA polymer matrix and (optionally) the addition of meltability modifiers (polymer I).

The film is produced in a single-roll process (so-called cold roll extrusion), in which the thermoplastic melt is brought into contact with a single metal roll during the cooling and solidification process and cooled. It should be explicitly noted that the thermoplastic melt cannot be shaped between two metal rolls to produce films of the required thickness.

This method has significant disadvantages compared to the two-roll process, which have a decisive influence on the quality of the film. The gel particles, which impact-modified PMMA molding materials generally tend to form, are not pressed under the surface during molding on a single cooled roll, unlike the two-roll (smoothing) process, and thus remain visible as an optical defect. They are particularly disadvantageous in the subsequent printing process when producing decorative film, in which clearly visible missing areas appear in the area of the gel particles. Furthermore, the film surface facing away from the cooled roll, which is cooled freely in the air, exhibits a noticeable surface haze, caused by the varying volume contraction of the elastomer particles and the PMMA matrix. This creates a "hill and valley" surface structure that scatters light and thus causes an unfavorable effect • φφφ

-6Φ φ φφφφ φφφφ φφφ φφ φφ φφ φφ φφ turbidity.

DE 195 44 563 (Rohm GmbH) describes impact-resistant PMMA molding materials used for the production of films according to the invention.

DE 40 18 530 (Rohm GmbH) describes a method for producing solid sheets or films with a thickness of less than 1 mm from a thermoplastic plastic with a glass transition temperature of >50 °C. Smoothing is achieved by guiding the film on an endless belt. The sheets or films obtained are practically free of orientation and birefringence.

EP 659 829 (Rohm GmbH) describes a weather protection film and moldings coated therewith, which film has the function of absorbing UV radiation in addition to providing weather protection. It consists of a hard phase made of PMMA and a damping phase, the substance absorbing UV radiation.

EP 391 193 (Bayer AG) describes a method for producing a double-sided, optically isotropic extrusion film with a thickness of less than 0.6 mm, which can be either

1. manufactured by extrusion and subsequent calendering between a varnished elastic roller and a high-gloss steel roller, or

2. is formed in two extrusion steps, whereby in the first step a film is produced by extrusion and subsequent calendering between a ground elastic roller and a high-gloss steel roller, high-gloss on one side and matt on the other. In the second extrusion step, the film produced in the first step is coated on the matt side with a melt of the same thermoplastic plastic, the coated film thus obtained is

9

-79 9 9 9999 9 99 9

9 9 99 9 9 99 9

999 99 99 99 99 99 is again calendered between two high-gloss steel rolls and a ground elastic roll, with the high-gloss side of the coated film facing the ground elastic roll.

Both methods, which are both technologically demanding and associated with high production costs, according to the prior art are unusable for the production of double-sided glossy foil between two highly glossy steel rollers due to the extremely high and difficult-to-control forces in the roll gap.

Method 1 has the disadvantage that it is not feasible for large-scale production, because the varnish layers on the rubber rollers become brittle very quickly due to the high melting temperature. To prevent the influence of high melting temperatures, the varnished rubber rollers can be cooled in a water bath, but the humidity leads to a disadvantageous influence on the surface quality of the film.

Method 2 has an extremely unfavorable economy, since the film must be produced in two extrusion steps. The extrusion coating of the film with the melt and subsequent calendering, especially in the desired thickness range according to the invention, also leads to unfavorable surface properties.

EP 195 075 (Exxon) describes a process for producing a film of 10-85 wt. % elastomer and 90-15 wt. % polyolefin, in which an extruded web is passed at a temperature above the softening point through a nip of counter-rotating rolls. One of the rolls is a high gloss cooled roll and the other roll is a roll with a high gloss rubber surface, the film being cooled.

The foils obtained in this way have a thickness between 25 and 250

-8φφ φφ φφ micrometers (10' ⁶ m). The pressing forces are not described here, the disadvantages described in the discussion of EP 391 193 also exist here.

EP 212 355 (Bayer AG) describes a polycarbonate film which is optionally printed with an adhesive-free polyurethane layer. The films are matt on one side or structured on one side by structured cooling printing and injection molding.

are drawn through matt or rollers. The films obtained in this way are

A copolymer of acrylonitrile, butadiene and styrene is used as the plastic for injection molding.

EP 294 705 (Rohm GmbH) describes a method for producing double-sided glossy films, which uses as a smoothing element an already smoothed film, which is produced in advance and fed back in this method.

A. Huemer (Kunststoffe 87 (1997), 10, p. 1351 et seq.) discusses the advantages and disadvantages of the arrangement of smoothing rollers, as does H. Gross (Kunststoffe 87 (1997), 5, p. 564).

Huemer states that “experiments with higher pressure fail because neither the residence time in the roll gap nor the relaxation time of the polymer changes.

The measures described by Huemer (the correct ratio of the nozzle exit speed to the draw-off speed) are not sufficient to obtain films with high surface quality. To smooth the surface, as Huemer concludes, it is not the lowest possible pressure in the roll gap that is needed, but the highest possible.

The essence of the invention

This creates the need to create an economically working,

-9• Φ φ · φφφ · Φ « 9

4 4 4 4 · 44 9 4 9 4

444 44 44 944 99 4 • 4 4 4·· ·· 4 ·

9 9 9 4 4 9 94 4 44 a process for producing films with a thickness of <0.3 mm from impact-resistant PMMA molding materials that can be used on a large scale and which also provides a high-gloss film on both sides, with a surface quality that is almost free of gel particles and with a surface hardness sufficient for decoration. Furthermore, this film must be reliably and economically processable in the printing process as well as in the "in-mould-film-decoration" method, and must have a correspondingly sufficient ductility.

Therefore, great attention had to be paid to the correct choice of PMMA component, especially with regard to the balance between surface hardness and ductility.

The following properties of PMMA film, necessary for decorating surfaces, can only be achieved if:

polybutylacrylate is used as the basis for weather-resistant impact modifiers the impact modifier used has a certain minimum particle size of the effective elastomeric phase (particle size range) the impact modifier used can be used in a relatively large dilution due to its morphological structure (clear separation of the tough and elastomeric phase, the highest possible effective elastomeric proportion, the largest possible particle size), thus ensuring the minimum necessary surface hardness for the production of the raw material for the film a special method of producing the molding compound is used which, based on the integrated coagulation technique of the impact modifiers, enables sufficient separation of water-soluble polymerization auxiliaries from the production of the impact modifiers,

- 10• 4 44 44 44 44 • · · · 4 4 4 * · 4 4 4 4 · 44 4 • 44 44 ·· 444 4· 4

4444 4444 · 44 4 · 44 44 which ensures only a slight tendency for the film to become cloudy due to the effect of water vapor.

good processability in the printing process (for "Film-InsertMolding" decoratively printed PMMA films are usually used), i.e. sufficient ductility high surface hardness (at least the hardness of an HB pencil) to prevent scratching of the molded parts decorated with PMMA films

- high surface gloss (measured according to DIN 67530) >120

- slight cloudiness due to humidity <2% fogging according to the method described on page 15

- low surface haze <1.5%

- extremely low number of gel particles max. 1 gel particle per 200 cm ²

- high weather resistance, comparable to standard PMMA

- sufficient UV light absorption; UV absorption in the range of 200 to 370 nm <1%.

The production of the impact-resistant PMMA molding materials used is described in DE 195 44 563 (Rohm GmbH).

Furthermore, the method of forming the film according to the invention is necessary to ensure high film quality (extremely low number of gel particles, high surface gloss, high weather resistance, low surface haze). The above-mentioned combination of properties is not possible with the method of extrusion onto a cooled roll, which is usual for films in the claimed thickness range.

The production of the foil according to the invention is carried out by a special shaping method based on the smoothing rolling technique ·· ·» 99

9 9 9 9

9 9 9 999

9 9 9

99 99 9· using a special pressure system and a pair of specially domed, mirror-polished rollers, in whose rolling gap the foil shaping according to the invention is carried out. So far, only significantly thicker foils (d>0.3 mm; see "Folien fur thermogeformte Verpackungen, VDI-Verlag, 1992) have been produced using the smoothing rolling technique.

For the production of films according to the invention (thickness range 80 to 300 μm, preferably 95 to 250 μm, particularly preferably 105 to 250 μm), extremely high pressure forces in the roller gap are necessary, which cannot be realized with the structures used so far (pressing with a bent lever, see Fig. 1, or with conventional hydraulic pressing). Hydraulic pressing, which is supposed to exert these pressure forces only approximately, is considerably more structurally demanding than the solution according to the invention. Surprisingly, it was possible to exert high pressure forces by means of the structure according to the invention: One of the rollers forming the smoothing gap is fixed motionlessly in the smoothing rolling mill. The second, displaceable roller is connected by means of two parallel drives (electric or hydraulic) via a worm gear to the rods located on the roller bearing pins (see Fig. 2).

In this way, for the required gap between the rolls, the opening of the roll gap due to the pressure caused by the melt is prevented. The maximum achievable contact pressure is 1500 N/cm.

The melt, produced by a single- or twin-screw extruder (melt pumps can optionally be used to ensure a constant melt flow), is fed to the shaping method according to the invention via a nozzle sized for film extrusion. The melt is shaped in a defined

-12* *«r ·· ·· ·· ·♦ ·· » * · · · · β 9 » • · · · · · · · · ·« ·

999 99 9 9 999 99 9

9 9 9 9 9 9 9 9 9

999 99 99 ·9 99 99 in the roll gap and is smoothed and cooled by the surface of tempered, mirror-polished rolls (roughness depth RA 0.002-0.006, RT=0.02 - 0.04, measured according to DIN 4768). The geometric shape of one or both rolls is ground in a dome shape, deviating from the cylindrical shape. The dome is of decisive importance for an even distribution of thickness across the width of the foil.

Definition of "cropping: parabolic increase in diameter from the edges of the cylinders to the center. Literature: Hensen, Knappe, Patente: Kunststoff-Extrusionstechnik II, Extrusions-anlagen, HanserVerlag, 1986. The cropping must be adapted to the thickness and width of the film to be achieved (i.e. there is no universally applicable cropping).

Alternatively, the following design measures can be taken to ensure uniform thickness distribution:

- cylinder axis crossing ("Ax-Crossing")

- mutual curvature of the rollers ("Roli-bending")

Both of these methods are unusual for smoothing mills, as they involve high construction costs. They are usually used on calendering machines.

The result of the method according to the invention is a double-sided, highly glossy film, almost free of gel particles, with excellent surface properties.

The method according to the invention can also be used for the production of polycarbonate films with excellent surface properties.

-13 * φ· φφ ·· φ* φφ • Φ φφ φφφ φ φ φ φ φ φ φ φ φφφ φ φ φ φ φφφ φφ φφ φφφ φφ · φ φ φφφ φφφφ φφφ φφ φφ φφ φφ

In the two-roll process, the elastomer-modified PMMA melt is shaped between two tempered steel rolls, with the surface temperature of the steel rolls being below the glass transition temperature of the PMMA matrix polymer used. This results in a preferential orientation of the PMMA matrix molecules (which have a significantly higher solidification driving force compared to the elastomer phase) on the metal or foil surface, resulting in a highly glossy foil surface with negligible surface haze.

The two-roll process also ensures significantly better weathering behavior, as the smooth film surfaces are less sensitive to erosion caused by UV light.

It is certainly possible, by appropriate selection of extremely small particle size modifiers (as described in DE 42 796), to produce highly glossy film surfaces on both sides by means of cold roll extrusion. However, these exhibit the typical formation of gel particles for PMMA films produced by cold roll extrusion, which is disadvantageous for surface decoration.

Furthermore, to ensure sufficient ductility of the film, it is necessary to increase the elastomer content with decreasing elastomer particle size, which again adversely affects the surface hardness, which is essential for decorative use (the minimum requirement is a pencil hardness of "HB", preferably at least H, particularly preferably 2H).

The optimum molding temperature range for thermoplastic, non-crystalline plastics lies between the glass transition temperature (ET) and the plastic-viscous range.

- 14flow. To achieve a high surface gloss, it is necessary to set the surface temperatures of the smoothing forming rolls lower than the glass transition temperature during the smoothing process. This means that the greater the temperature difference between the roll temperature (which must be lower than the glass transition temperature T _G ) and the optimal temperature range for thermoforming, the more difficult it is for films made of thermoplastic materials to be formed into thin layers.

As is clear from H. Saechtling, Kunststoff-Taschenbuch, 21st edition (1979), Fig. 99 on page 166, for the above reasons, thermoforming of thin films with high-gloss surfaces is possible in the case of polycarbonate in the case of polymethyl methacrylate.

The smoothing process used allows for the extrusion of polycarbonates with a minimum thickness of about 120 μΜ and PMMA with a minimum thickness of about 100 μη. The required pressure forces increase exponentially with increasing thickness.

considerably more difficult than It follows that when

Furthermore, the film forming is easier to implement with the claimed smoothing process in the case of thermoplastic materials, the wider the temperature range for optimal thermoforming. Since a high temperature gradient is established when the shaped melt film passes through the smoothing gap, the shaped thermoplastic must have a reasonably wide range of thermoforming temperatures. This means that it is practically impossible to process thermoplastics such as PP or PE into the claimed films.

Test methods

The modulus of elasticity, tensile strength and elongation at break were tested according to ISO 527-3, the clamping length was 60 mm and the test speed was 50 mm/min.

- 15Pencil hardness was tested according to ASTM D 3363-92a.

The gloss level was measured at 60° according to DIN 67530.

"Haze" was measured according to ASTM D 1003. To calculate "surface haze", the haze of the film after double-sided treatment with silicone oil was subtracted from the haze measured in the untreated state.

The determination of the number of gel particles is an internal method of the Rohm company (Quality Assurance Work Instructions 1/021/220).

Gel particles are dark/light flashing particles, visible under magnification when zooming in and out on the test specimen. They are mainly caused by high molecular weight fractions unavoidable during the melting process or, as in the case of impact-modified PMMA, by aggregation of elastomeric particles of the impact modifier component.

The enumeration of gel particles per 200 ^cm2 of film is carried out using a particle counting device "Copea CP-3 from Agfa Gaevert.

Haze due to humidity: The films were placed for 96 hours above water at a temperature of more than 60°C (90% humidity). Haze was then measured according to ASTM D 1003.

Examples of embodiments of the invention

Production of used impact-resistant molding compound and its

-1644 563 (Rohm GmbH).

φφ Φ·· ·«· φ φ φφφφ · · · impact modifier has the following composition:

methyl methacrylate/ethyl acrylate/ composition is described in DE 195

Raw materials used

Latex dispersion as a three-component emulsion polymer

1st component: allyl methacrylate copolymer 95.7/4.0/0.3 (by weight)

2nd component: butyl acrylate/styrene/allyl methacrylate copolymer

82/17/1 (by weight)

3rd component: methyl methacrylate ethyl acrylate copolymer 96/4.

The weight ratio of these three components is 23/40/30 (by weight). The latex dispersion has a solids content of 45% by weight.

Matrix polymer 1 is produced by continuous polymerization, average molecular weight (weight center) 110,000 Dalton. It is a copolymer of 96 wt. % methyl methacrylate and 4 wt. % methyl acrylate.

Matrix polymer 2 is produced by discontinuous polymerization, is a copolymer of 80 wt. % methyl methacrylate and 20 wt. % butyl acrylate. Molecular weight (weight center) 270,000 Dalton.

Matrix polymer 3 is produced by continuous polymerization. Average molecular weight (weight center) 110,000 Dalton. It is a copolymer of 99 wt. % methyl methacrylate and 1 wt. % methyl acrylate.

Production of impact-resistant PMMA molding compounds, which are the basis for examples 1, 2 and 4

The production of impact-resistant PMMA molding compounds for examples 1, 2 and 4 is carried out in two steps. In the first step, the production of an impact-resistant molding compound blank is carried out using a combined coagulation/compounding device. In the second step, this molding compound blank is mixed with matrix polymer 2 in a twin-screw compounder to form the final raw material for the film, the mixing ratio of the molding compound blank to matrix polymer 2 is 1:1, 0.3% by weight of Tinuvin P (UV absorber based on benzotriazole, manufactured by Ciba-Geigy) is added during the compounding.

Step 1 is carried out in a device consisting of two extruders arranged in series, in which the latex dispersion is dewatered in the first extruder and combined with a portion of the matrix polymer 1, which is fed as a melt. In the second extruder, which functions as a coupling and degassing extruder, the main amount of matrix polymer 1 is added via a side charge. At the end of the degassing zone, the addition of bleaches and anti-yellowing stabilizers is carried out via a masterbatch. Based on the semi-finished molding material produced, 4 ppm of Ultramarine blue 31 and 14 ppm of Ultramarine violet 11 are added. 40 ppm of sodium phosphate is added as an anti-yellowing stabilizer. The weight ratio of dispersion to matrix polymer is 82 to 63.

Production of impact-resistant PMMA molding compounds, which are the basis for example 3

Production of impact-resistant PMMA molding compounds for example

- 18 ·· · · · · · · · · · · · · · · · · · · • ····· · · · t · • tt ···· ···· • · · · · · · · · · * · · is carried out using a combined coagulation/bonding device consisting of two extruders arranged in series. In the first step, the latex dispersion is dewatered and combined with a portion of the matrix polymer 2, which is fed as a melt. In the second extruder, which functions as a bonding and degassing extruder, the remaining amount of matrix polymer 2 is added via a side charge. At the end of the degassing zone, the bleach, anti-yellowing stabilizer and UV absorber are added via a premix. Based on the semi-finished molding material produced, 4 ppm Ultramarinblau 31, 14 ppm Ultramarinviolett 11, 40 ppm sodium phosphate and 0.5% by weight Mark LA 31 (UV absorber based on benzotriazole, manufactured by Asahi-Denka) are added. The weight ratio of dispersion to matrix polymer is 42/81.

Production of films according to examples 1 and 3 (according to the invention)

The melt is produced using a single-screw extruder with a diameter of 120 mm and is fed to the smoothing rolling mill according to the invention via a flexible lamellar die (width 1500 mm) dimensioned for extrusion of the film. The gap setting of the lamellar die is 0.8 mm. According to the invention, the smoothing rolling mill is dimensioned for developing high pressure forces in the rolling gap (see Fig. 2) by means of a special design.

One of the rollers forming the smoothing gap is fixed in the calendering stand. The movable roller is connected to the rods located on the roller bearing blocks by means of two parallel electric drives with a worm gear. In this way, the developed pressure force of 1500 N/cm prevents the opening of the • 4 · · · ····

4 4 4 · 4 4 4 »4 4 «4444 44 444 44 4 • «444 4444 ··· 44 «4 4 · 44

-19 rolling nips in the production of 0.125 mm thick foil by pressure caused by the cooled melt. The melt is shaped in the rolling nip and smoothed and cooled by the surface of the rollers, polished to a mirror shine and tempered to a temperature below the glass transition temperature of the PMMA matrix polymer (roughness depth RA=0.004). One of the rollers is domed. The domedness is 0.1 mm.

The result is a double-sided, high-gloss film free of gel particles with very little surface haze. The film is printed with the desired pattern and then processed via in-mould-film-decoration to the desired decorated molding.

Production of foil according to example 2 (comparative example, method of extrusion onto a cooled roller analogous to the cited patent EP 763 560, Mitsubishi)

The melt is produced using a single-screw extruder with a diameter of 120 mm and is fed to the film forming device on a cooled roll via a flexible lamella nozzle with a width of 1500 mm. The lamella nozzle gap is set to 0.8 mm.

The melt film is deposited on the surface of the cooled roll and cooled. The result is a film, compared to films made according to the invention, with a relatively low surface gloss, a high number of gel particles, low brilliance and significant surface haze (see Table 1).

Film production according to example 4 (comparative example, smoothing rolling mill with pressing by a bent lever, see Fig. 1)

-20The melt is produced using a single-screw extruder with a diameter of 120 mm and is fed to a smoothing rolling mill equipped with a bent lever through a flexible lamella nozzle with a width of 1500 mm. The lamella nozzle gap is set to 0.8 mm.

The result is a product with respect to surface properties corresponding to the films of Examples 1 and 3. However, the desired film thickness of <300 μm is not achieved with the lever-type pressing system. This pressing system does not have the rigidity necessary in the approximated state, due to the necessarily incompletely straightened joint (a fully straightened joint under load requires an infinitely large opening force), to develop the necessary extremely high pressing force. This is of decisive importance with high counterforces (developed by the thin film of melt during film production).

Example 5

Lamination of PMMA films produced according to the invention according to examples 1 and 3 with carrier material

The ABS melt film is produced using a 90 mm diameter single-screw extruder and is fed to the smoothing mill through a wide slot die. The slot setting of the slot die is 1.2 mm.

In the smoothing slot, the PMMA film, printed with, for example, a so-called "angular pattern" and a topcoat that causes adhesion to ABS, is laminated with a film of ABS melt heated to 240 °C. The PMMA film according to the invention is suspended on a brakeable winding shaft. To ensure crease-free running and correct lamination, the Plexiglas film according to the invention is guided

-21 over a so-called "expanding roller". The resulting foil laminate has a total thickness of 0.50 mm, of which 125 nm is the PMMA layer. The speed of withdrawal from the smoothing roller stand is 5 m/min. The laminated foil is used for surface decoration of moldings using the so-called "Insert-Moulding" process. The resulting injection-molded parts have an attractive surface pattern due to the finishing print used. Due to its valuable surface properties, PMMA foil is an ideal substrate for valuable paint systems.

• · · · · · · · · · · · · · · · · · · · · · · ··» • · · 9 « · 4 4

gel particles/ 2 0 0 cm ² About 15 0-1 claimed thickness not possible surface fog (%) 1.1 rH CM about gloss 60° 133 108 136 hardness of a pencil IH fn 2H elongation at break (%) 00 r- tensile strength (MPa) ⁶¹ 67 83 E-modulus (MPa) 1591 1603 1530 property 1* CN * cn <4· Example No.

List of reference marks

Fig. 1

100 flexible flap nozzle

110 solid cylinder

120 movable cylinder

130 angled lever

140 pneumatic cylinder

150 foils

Fig. 2

200 flexible flap nozzle

210 solid cylinder

220 movable cylinder

230 pull rod

240 worm gear

250 measuring boxes of foil

Fig. 3

310 cylinder smoothing rolling chair 320 cylinder smoothing rolling chair 330 cylinder smoothing rolling chair 340 PMMA- foil 350 expanding cylinder 360 foil

pp 2000 ~206&

Claims (9)

1. A method of producing double-sided glossy films from thermoplastic plastics in the thickness range of 80 to 300 μιυ using a special characterized in that. rolling process, the rolling mill is designed for high contact forces in the rolling nip. 2. A method of producing double-sided glossy films from thermoplastic plastics in the thickness range of 80 to 300 μm using a special smoothing rolling process according to claim 1, characterized in that the temperature range of optimal thermoforming is at least 15 K. 3. Production of double-sided glossy foils from thermoplastic plastics in the thickness range of 80 to 300 μm using a special smoothing rolling process according to claim 1, characterized in that the temperature difference between the glass transition temperature and the optimal temperature range is max. 50 K. 4. Production of double-sided glossy films from thermoplastic plastics in the range of thicknesses from 80 to 300 μm by rolling process, the plastic is characterized by the fact that thermoplastic polymethyl methacrylate or polycarbonate. PMMA. 5. Production of double-sided glossy foils from thermoplastic plastics in the thickness range of 80 to 300 μιυ using a special smoothing rolling process according to claim 1, characterized in that the thermoplastic plastic is -256. The method according to claim 1, characterized in that the cylinder is domed. 7. Use of a film produced by the method according to any one of claims 1 to 6 as a decorative film for injection molded parts. 8. A product made of an injected thermoplastic molding material, characterized in that it is decorated with a foil made according to any one of claims 1 to 6. 9. The product according to claim 8, characterized in that the thermoplastic molding compound is a transparent molding compound. 10. A product according to any one of claims 7 to 9, characterized in that the film made according to any one of claims 1 to 6 is laminated with a thermoplastic carrier material before use as a decorative film. 11. Using foil, made by way of according to someone from claims 1 to 6, as decorative foil for extruded stampings. 12 . Using foil, made by way of according to someone from claims 1 to 6, as decorative foil for extruded reformed moldings. WO 99/29766