Method for producing a plastic molding

Abstract

The invention relates to a method for producing a plastic molding, wherein a) a plastic film (5) is placed on a main frame (2) having a first through-opening (3) such that the plastic film (5) completely covers the first through-opening (3) and lies on an edge zone (6) of an upper face (4) of the main frame (2), which edge zone delimits the first through-opening (3), b) the plastic film lying on the main frame (2) is heated, and c) a fluid pressure medium is applied to the plastic film lying on the main frame (2) and heated in step (b), such that the plastic film (5) is pushed against a mold (39), thereby forming the film to give a plastic molding. In step a) a tensioning frame (10), which has a second through-opening (11), is applied to the plastic film (5) lying on the main frame (2) and is positioned such that the tensioning frame (10) pushes the plastic film (5) in the edge region (6) against the upper face (4) of the main frame (2), thereby fixating it, and that the second through-opening (11) in the tensioning frame (10) is at least partially opposite the first through-opening (3) in the main frame (2), and step b) is carried out with the plastic film (5) fixated between the main frame (2) and the tensioning frame (10).

Description

[0001] Method for producing a plastic molded part

[0002] The present invention relates to a method for producing a plastic molded part and in particular a plastic molded part for optical applications.

[0003] Such plastic molded parts can be manufactured from a plastic film using high-pressure forming (also known as the Niebling process). During this high-pressure forming process, the plastic film is heated (often above its softening point) and then pressed against a mold using high pressure (up to 300 bar, preferably isostatically). This method allows for reproducible, contour-accurate molds (with tolerances of, for example, less than + / - 0.4 mm). Further details on this high-pressure forming process can be found, for example, in DE 10 2008 050 564 A1.

[0004] Since the plastic films used are typically manufactured using a flat film extrusion process, and the final surface structure (such as gloss and thickness) is created by rolling, anisotropic internal stresses can occur. The heating required for the described high-pressure forming process then has the disadvantage that these intrinsic anisotropic stresses are released due to the heating, which can lead to warping. Even slight waves / wrinkles during the heating process can result in the required accuracy of the mold being lost.

[0005] It is therefore an object of the invention to provide an improved method for producing a plastic molded part in which the disadvantages described above can be avoided as completely as possible.

[0006] The invention is defined in independent claims 1, 11 and 12. Advantageous embodiments are specified in the dependent claims.

[0007] The clamping frame allows the plastic film to be fixed or clamped evenly in the region of the edge zone and in particular along a closed line around the first through-opening, thereby effectively preventing undesired warping during heating. The edge zone can, for example, be defined as the region of the upper side of the base frame that extends from the edge of the through-opening to a predetermined distance from the edge of the first through-opening. The edge zone can also be defined by being the region of the upper side of the base frame on which the plastic film rests and in which it is pressed against the upper side by the clamping frame when the plastic film covers the first through-opening.

[0008] The first and / or second through-opening can, in particular, be circular. However, an oval shape or any other shape is also possible.

[0009] The tensioning frame can press the plastic film against the top of the base frame along a closed path that encloses the first through opening.

[0010] In particular, the clamping frame can have an annular groove that encloses the second through-opening. A seal that presses against the plastic film can be located in the groove. In particular, the annular groove can press against the plastic film in an area that lies above the first through-opening.

[0011] The groove and / or the seal can be circular or any other ring shape, such as square, rectangular, oval, polygonal or the shape of any other closed path curve.

[0012] The base frame can have several protruding pins on its top. The clamping frame can have corresponding holes or adjustment holes. In step a), the clamping frame with its adjustment holes can be slid over the pins and thus placed on the plastic film.

[0013] Alternatively, the clamping frame can be positioned between the pins that serve as a stop for the clamping frame. In this case, the clamping frame can be designed without the corresponding bores or adjustment holes. Instead of pins, the stop function can also be performed with any other type of mechanical stop or stop.

[0014] stop element must be implemented.

[0015] Furthermore, the clamping frame can have a flat or non-flat underside that rests on the plastic film. The design of the non-flat underside can be implemented in such a way that a better fixation of the plastic film is achieved. For example, the clamping frame can have points, teeth and / or a rough surface on the underside in the area of ​​the edge zone to fix the plastic film. The top side of the base frame can be flat or non-flat. The non-flat top side can be implemented with points, teeth and / or a rough surface. This can improve the fixation of the plastic film. Furthermore, a clamping means can be provided that applies a force to the clamping frame that presses the clamping frame against the base frame and thereby increases the clamping effect already exerted on the plastic film due to the weight of the clamping frame. The clamping means can be implemented by clamping elements, such as e.g.by means of a screw connection and / or one or more clamping levers, or also by means of magnetic force.

[0016] In the method according to the invention, a pressure chamber can be present in step c) in which the forming of the plastic film is carried out.

[0017] To form the pressure chamber, for example, a wall surrounding the tool can press the plastic film against the clamping frame, so that the clamping frame is part of the pressure chamber and the base frame is not part of the pressure chamber.

[0018] Furthermore, to form the pressure chamber, the plastic film can be clamped directly between a wall surrounding the tool and a wall of a first partial chamber, so that neither the clamping frame nor the base frame is part of the pressure chamber.

[0019] In particular, the pressure chamber can be formed such that the plastic film is lifted from the base frame, so that during the time at which the pressure chamber is formed, a gap, for example an air gap, is present between the plastic film and the base frame.

[0020] With the exception of the plastic film, the elements forming the pressure chamber are preferably made of metal. It is preferable to provide only one (usually annular) seal per parting plane between two metal surfaces of the metal elements (excluding the plastic film) to ensure tightness in this parting plane. Thus, the sequence metal-seal-metal, metal-seal-plastic film-metal, and metal-plastic film-seal-metal can be used to ensure tightness.

[0021] The annular seal can be circular, oval, square, rectangular, polygonal or the shape of any other closed trajectory curve.

[0022] All of the seals described can be made, for example, from a heat-resistant elastomer (such as fluororubber). In step c), the tool can be provided with a contour, with the fluid pressure medium pressing the plastic film against the contour for deformation.

[0023] The forming in step c) is preferably carried out isostatically.

[0024] The plastic film can comprise any plastic that a person skilled in the art would select for forming. In particular, the plastic is a thermoplastic polymer.

[0025] Thermoplastic polymers, such as polycarbonate, PMMA (polymethyl methacrylate), PA (polyamide), PS (polystyrene), PET (polyethylene terephthalate), PEN (polyethylene naphthalate), TAC (cellulose acetate), and COP / COC (cycloolefin polymer or copolymer), can be used as materials for the plastic film. Furthermore, reactive polymer precursors can be used, which are partially or fully cured thermally or by radiation curing during the forming process or in a subsequent process step. Examples of this can be found in the field of polyurethane chemistry, among others. Furthermore, coated and / or pretreated films, coextrusion films, hybrid and / or composite films can be used.

[0026] The thermoplastic material can preferably be at least one thermoplastic material selected from polymers of ethylenically unsaturated monomers and / or polycondensates of bifunctional reactive compounds and / or polyaddition products of bifunctional reactive compounds, preferably at least one thermoplastic material selected from polymers of ethylenically unsaturated monomers and / or polycondensates of bifunctional reactive compounds. For certain applications, it may be advantageous and therefore preferred to use a transparent thermoplastic material.

[0027] Particularly suitable thermoplastics are polycarbonates or copolycarbonates based on diphenols, poly- or copolyacrylates and poly- or copolymethacrylates such as, for example and preferably, polymethyl methacrylate or poly(meth)acrylate (PMMA), polyor copolymers with styrene such as, for example and preferably, polystyrene or polystyreneacrylonitrile (SAN), thermoplastic polyurethanes, and polyolefins such as, for example and preferably, polypropylene types or polyolefins based on cyclic olefins (e.g., TOPAS®, Hoechst), poly- or copolycondensates of terephthalic acid such as, for example and preferably, poly- or copolyethylene terephthalate (PET or CoPET), glycol-modified PET (PETG), glycol-modified poly- or copolycyclohexanedimethylene terephthalate (PCTG) or poly- or copolybutylene terephthalate (PBT or CoPBT) or mixtures of the aforementioned. Polyolefins such as, for exampleHowever, polypropylene, without the addition of other thermoplastics mentioned above, is less preferred for the process according to the invention.

[0028] Preferred thermoplastics are polycarbonates or copolycarbonates, poly- or copolyacrylates, poly- or copolymethacrylates or blends containing at least one of these thermoplastics. Particular preference is given to polycarbonates or copolycarbonates, in particular having average molecular weights Mw of 500 to 100,000, preferably 10,000 to 80,000, particularly preferably 15,000 to 40,000, or blends thereof with at least one poly- or copolycondensate of terephthalic acid having average molecular weights Mw of 10,000 to 200,000, preferably 26,000 to 120,000, or poly- or copolyacrylates and poly- or copolymethacrylates having average molecular weights Mw in the range from 30,000 to 300,000, particularly preferably in the range from 80,000 to 250,000.

[0029] In preferred embodiments of the invention, polyalkylene terephthalates are suitable as poly- or copolycondensates of terephthalic acid. Suitable polyalkylene terephthalates include, for example, reaction products of aromatic dicarboxylic acids or their reactive derivatives (e.g., dimethyl esters or anhydrides) and aliphatic, cycloaliphatic, or araliphatic diols, and mixtures of these reaction products.

[0030] Preferred polyalkylene terephthalates can be prepared from terephthalic acid (or its reactive derivatives) and aliphatic or cycloaliphatic diols with 2 to 10 C atoms by known methods (Kunststoff-Handbuch, Vol. VIII, p. 695 ff, Karl-Hanser-Verlag, Munich 1973).

[0031] Preferred polyalkylene terephthalates contain at least 80 mol%, preferably 90 mol% of terephthalic acid residues, based on the dicarboxylic acid component, and at least 80 mol%, preferably at least 90 mol% of ethylene glycol and / or butanediol-1,4- and / or 1,4-cyclohexanedimethanol residues, based on the diol component.

[0032] The preferred polyalkylene terephthalates may contain, in addition to terephthalic acid residues, up to 20 mol% of residues of other aromatic dicarboxylic acids having 8 to 14 C atoms or aliphatic dicarboxylic acids having 4 to 12 C atoms, such as, for example, residues of phthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, 4,4'-diphenyldicarboxylic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, cyclohexanediacetic acid.

[0033] The preferred polyalkylene terephthalates can contain, in addition to ethylene or butanediol-1,4-glycol residues, up to 80 mol% of other aliphatic diols having 3 to 12 C atoms or cycloaliphatic diols having 6 to 21 C atoms, e.g. B. residues of propanediol-1,3, 2-ethylpropanediol-1,3, neopentyl glycol, pentane-diol-1,5, hexanediol-1,6, cyclohexane-dimethanol-1,4, 3-methylpentanediol-2,4, 2-methylpentanediol-2,4, 2,2,4-trimethylpentanediol-1,3 and 2-Ethylhexanediol-1,6, 2,2-diethylpropanediol-1,3, hexanediol-2,5, 1,4-di-([beta]-hydroxyethoxy)-benzene, 2,2-bis-(4-hydroxycyclohexyl)-propane, 2,4-dihydroxy-1,1,3,3-tetramethylcyclobutane, 2,2-Bis-(3-[beta]-hydroxyethoxyphenyl)-propane and 2,2-Bis-(4-hydroxypropoxyphenyl)-propane (see DE-OS 24 07 674, 24 07776, 27 15 932).

[0034] The polyalkylene terephthalates can be branched by incorporating relatively small amounts of tri- or tetrahydric alcohols or tri- or tetrabasic carboxylic acids, as described, for example, in German Offenlegungsschrift 19 00270 and US Pat. No. 3,692,744. Examples of preferred branching agents are trimesic acid, trimellitic acid, trimethylolethane and propane, and pentaerythritol.

[0035] Preferably, not more than 1 mol% of the branching agent is used, based on the acid component.

[0036] Particularly preferred are polyalkylene terephthalates which have been prepared solely from terephthalic acid and its reactive derivatives (e.g. its dialkyl esters) and ethylene glycol and / or 1,4-butanediol and / or 1,4-cyclohexanedimethanol residues, and mixtures of these polyalkylene terephthalates.

[0037] Preferred polyalkylene terephthalates are also copolyesters which are prepared from at least two of the above-mentioned acid components and / or from at least two of the above-mentioned alcohol components; particularly preferred copolyesters are poly(ethylene glycol / butanediol-1,4) terephthalates.

[0038] The polyalkylene terephthalates preferably used as components preferably have an intrinsic viscosity of approximately 0.4 to 1.5 dl / g, preferably 0.5 to 1.3 dl / g, each measured in phenol / o-dichlorobenzene (1:1 parts by weight) at 25°C.

[0039] In particularly preferred embodiments of the invention, the blend of at least one polycarbonate or copolycarbonate with at least one poly- or copolycondensate of terephthalic acid is a blend of at least one polycarbonate or copolycarbonate with poly- or copolybutylene terephthalate or glycol-modified poly- or copolycyclohexanedimethylene terephthalate. Such a blend of polycarbonate or copolycarbonate with poly- or copolybutylene terephthalate or glycol-modified poly- or copolycyclohexanedimethylene terephthalate can preferably be one with 1 to 90 wt.% polycarbonate or copolycarbonate and 99 to 10 wt.% poly- or copolybutylene terephthalate or glycol-modified poly- or copolycyclohexanedimethylene terephthalate, preferably with 1 to 90 wt.% polycarbonate and 99 to 10 wt.% polybutylene terephthalate or glycol-modified polycyclohexanedimethylene terephthalate, where the proportions are 100 wt.-%. Particularly preferably, such a blend of polycarbonate or copolycarbonate with poly- or copolybutylene terephthalate or glycol-modified poly- or copolycyclohexane dimethylene terephthalate can be one with 20 to 85 wt.% polycarbonate or copolycarbonate and 80 to 15 wt.% poly- or copolybutylene terephthalate or glycol-modified poly- or copolycyclohexane dimethylene terephthalate, preferably with 20 to 85 wt.% polycarbonate and 80 to 15 wt.% polybutylene terephthalate or glycol-modified polycyclohexane dimethylene terephthalate, where the proportions add up to 100 wt.%. Most preferably, such a blend of polycarbonate or copolycarbonate with poly- or copolybutylene terephthalate or glycol-modified poly- or copolycyclohexanedimethylene terephthalate can be one with 35 to 80 wt.% polycarbonate or copolycarbonate and 65 to 20 wt.-% poly- or copolybutylene terephthalate or glycol-modified poly- or copolycyclohexanedimethylene terephthalate, preferably with 35 to 80 wt.% polycarbonate and 65 to 20 wt.% polybutylene terephthalate or glycol-modified polycyclohexanedimethylene terephthalate, the proportions adding up to 100 wt.%. In particularly preferred embodiments, the above-mentioned compositions can be blends of polycarbonate and glycol-modified polycyclohexanedimethylene terephthalate.

[0040] In preferred embodiments, aromatic polycarbonates or copolycarbonates are particularly suitable as polycarbonates or copolycarbonates.

[0041] The polycarbonates or copolycarbonates can be linear or branched in a known manner.

[0042] These polycarbonates can be produced in a known manner from diphenols, carbonic acid derivatives, optionally chain terminators, and optionally branching agents. Details of the production of polycarbonates have been documented in numerous patents dating back about 40 years. As examples, reference is made here to Schnell, "Chemistry and Physics of Polycarbonates", Polymer Reviews, Volume 9, Interscience Publishers, New York, London, Sydney 1964, to D. Freitag, U. Grigo, PR Müller, H. Nouvertne', BAYER AG, "Polycarbonates" in Encyclopedia of Polymer Science and Engineering, Volume 11 , Second Edition, 1988, pages 648-718 and finally to Dres. U. Grigo, K. Kirchner and PR Müller "Polycarbonate" in Becker / Braun, Kunststoff-Handbuch, Volume 3 / 1 , Polycarbonates, Polyacetals, Polyesters, Celluloseesters, Carl Hanser Verlag Munich, Vienna 1992, pages 1 17-299.

[0043] Suitable diphenols can be, for example, dihydroxyaryl compounds of the general formula (I),

[0044] HO-Z-OH (I) wherein Z is an aromatic radical having 6 to 34 C atoms, which may contain one or more optionally substituted aromatic nuclei and aliphatic or cycloaliphatic radicals or alkylaryls or heteroatoms as bridge members.

[0045] Examples of suitable dihydroxyaryl compounds are: dihydroxybenzenes, dihydroxydiphenyls, bis-(hydroxyphenyl)-alkanes, bis-(hydroxyphenyl)-cycloalkanes, bis-(hydroxyphenyl)-aryls, bis-(hydroxyphenyl)-ethers, bis-(hydroxyphenyl)-ketones, bis-(hydroxyphenyl)-sulfides, bis-(hydroxyphenyl)-sulfones, bis-(hydroxyphenyl)-sulfoxides, 1,1'-bis-(hydroxyphenyl)-diisopropylbenzenes, and their nuclear alkylated and nuclear halogenated compounds.

[0046] These and other suitable dihydroxyaryl compounds are described, for example, in DE-A 3 832 396, FR-A 1 561 518, in H. Schnell, Chemistry and Physics of Polycarbonates, Interscience Publishers, New York 1964, p. 28 ff.; p. 102 ff. and in DG Legrand, JT Bendler, Handbook of Polycarbonate Science and Technology, Marcel Dekker, New York 2000, p. 72 ff.

[0047] Bevorzugte Dihydroxyarylverbindungen sind beispielsweise Resorcin, 4,4'-Dihydroxydiphenyl, Bis-(4-hydroxyphenyl)-methan, Bis-(3,5-dimethyl-4-hydroxyphenyl)-methan, Bis-(4- hydroxyphenyl)-diphenyl-methan, 1 ,1 -Bis-(4-hydroxyphenyl)-1 -phenyl-ethan, 1 ,1 -Bis-(4- hydroxyphenyl)-1 -(1 -naphthyl)-ethan, 1 ,1 -Bis-(4-hydroxyphenyl)-1 -(2-naphthyl)-ethan, 2,2-Bis- (4-hydroxyphenyl)-propan, 2,2-Bis-(3-methyl-4-hydroxyphenyl)-propan, 2,2-Bis-(3,5-dimethyl-4- hydroxyphenyl)-propan, 2,2-Bis-(4-hydroxyphenyl)-1 -phenyl-propan, 2,2-Bis-(4-hydroxyphenyl)- hexafluor-propan, 2,4-Bis-(4-hydroxyphenyl)-2-methyl-butan, 2,4-Bis-(3,5-dimethyl-4- hydroxyphenyl)-2-methylbutan, 1 ,1 -Bis-(4-hydroxyphenyl)-cyclohexan, 1 ,1 -Bis-(3,5-dimethyl-4- hydroxyphenyl)-cylohexan, 1 ,1 -Bis-(4-hydroxyphenyl)-4-methyl-cylohexan, 1 ,3-Bis-[2-(4- hydroxyphenyl)-2-propyl]-benzol, 1 ,T- Bis-(4-hydroxyphenyl)-3-diisopropyl-benzol, 1 ,1 '-Bis-(4- hydroxyphenyl)-4-diisopropyl-benzol, 1 ,3-Bis-[2-(3,5-dimethyl-4-hydroxyphenyl)-2-propyl]-benzene, bis(4-hydroxyphenyl) ether, bis(4-hydroxyphenyl) sulfide, bis(4-hydroxyphenyl) sulfone, bis(3,5-dimethyl-4-hydroxyphenyl) sulfone and 2,2',3,3'-tetrahydro-3,3,3',3'-tetramethyl-1,1'- spirobi-[1 H-indene]-5,5'-diol or dihydroxydiphenylcycloalkanes of the formula (la), wherein

[0048] R 1 and R 2 independently of one another hydrogen, halogen, preferably chlorine or bromine, Ci-Cs-alkyl, Cs-Ce-cycloalkyl, Ce-C-aryl, preferably phenyl, and C?-Ci2-aralkyl, preferably phenyl-Ci-C4-alkyl, in particular benzyl, m is an integer from 4 to 7, preferably 4 or 5, R 3 and R 4 for each X individually selectable, independently of one another, hydrogen or Ci-Ce-alkyl and X is carbon, with the proviso that at least one atom X, R 3 and R 4simultaneously denote alkyl. In formula (Ia), one or two X atoms, in particular only one XR atom, are preferably 3 and R 4 simultaneously alkyl.

[0049] Preferred alkyl radical for the radicals R 3 and R 4 in formula (Ia) is methyl. The X atoms in the alpha position to the diphenyl-substituted C atom (C-1) are preferably not dialkyl-substituted; however, alkyl disubstitution in the beta position to C-1 is preferred.

[0050] Particularly preferred dihydroxydiphenylcycloalkanes of formula (Ia) are those having 5 and 6 ring C atoms X in the cycloaliphatic radical (m = 4 or 5 in formula (Ia)), for example the diphenols of formulas (Ib) to (Id),

[0051] (la-1 )

[0052] (la-3)

[0053] A particularly preferred dihydroxydiphenylcycloalkane of formula (Ia) is 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethyl-cyclohexane (formula (Ia-1) with R 1 and R 2 equal to H).

[0054] Such polycarbonates can be prepared according to EP-A 359 953 from dihydroxydiphenylcycloalkanes of formula (Ia).

[0055] Particularly preferred dihydroxyaryl compounds are resorcinol, 4,4'-dihydroxydiphenyl, bis-(4-hydroxyphenyl)-diphenyl-methane, 1,1-bis-(4-hydroxyphenyl)-1-phenyl-ethane, bis-(4-hydroxyphenyl)-1-(1-naphthyl)-ethane, bis-(4-hydroxyphenyl)-1-(2-naphthyl)-ethane, 2,2-bis-(4-hydroxyphenyl)-propane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)-propane, 1,1-bis-(4-hydroxyphenyl)-cyclohexane, 1,1-bis-(3,5-dimethyl-4-hydroxyphenyl)-cyclohexane, 1,1-bis-(4- hydroxyphenyl)-3,3,5-trimethylcyclohexane, 1,1 '-Bis-(4-hydroxyphenyl)-3-diisopropylbenzene and 1,1'-bis-(4-hydroxyphenyl)-4-diisopropylbenzene. Particularly preferred dihydroxyaryl compounds are 4,4'-dihydroxydiphenyl, 2,2-bis-(4-hydroxyphenyl)propane, and 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane.

[0056] Both a single dihydroxyaryl compound can be used to form homopolycarbonates and various dihydroxyaryl compounds can be used to form copolycarbonates. Both a single dihydroxyaryl compound of formula (I) or (Ia) can be used to form homopolycarbonates, and several dihydroxyaryl compounds of formula (I) and / or (Ia) can be used to form copolycarbonates. The various dihydroxyaryl compounds can be linked to one another either randomly or blockwise.In the case of copolycarbonates of dihydroxyaryl compounds of formula (I) and (Ia), the molar ratio of dihydroxyaryl compounds of formula (Ia) to the other dihydroxyaryl compounds of formula (I) optionally to be used is preferably between 99 mol% (Ia) to 1 mol% (I) and 2 mol% (Ia) to 98 mol% (I), preferably between 99 mol% (Ia) to 1 mol% (I) and 10 mol% (Ia) to 90 mol% (I) and in particular between 99 mol% (Ia) to 1 mol% (I) and 30 mol% (Ia) to 70 mol% (I).

[0057] A particularly preferred copolycarbonate can be prepared using 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethyl-cyclohexane and 2,2-bis-(4-hydroxyphenyl)-propane dihydroxyaryl compounds of formula (Ia) and (I).

[0058] Poly- or copolycarbonates prepared using dihydroxyaryl compounds of formula (Ia) usually have a higher glass transition temperature T gand a higher Vicat softening temperature B / 50 than polypolycarbonate based on 2,2-bis-(4-hydroxyphenyl)propane as a dihydroxyaryl compound.

[0059] Suitable carbonic acid derivatives can be, for example, diaryl carbonates of the general formula (II), wherein R, R' and R" independently of one another, identical or different, represent hydrogen, linear or branched C1-C34 alkyl, C1-C34 alkylaryl or C1-C34 aryl, R can also represent -COO-R'", where R'" represents hydrogen, linear or branched C1-C34 alkyl, C1-C34 alkylaryl or C1-C34 aryl. Preferred diaryl carbonates are, for example, diphenyl carbonate, methylphenyl phenyl carbonates and di-(methylphenyl) carbonates, 4-ethylphenyl phenyl carbonate, di-(4-ethylphenyl) carbonate, 4-n-propylphenyl phenyl carbonate, di-(4-n-propylphenyl) carbonate, 4-isopropylphenyl phenyl carbonate, di-(4-isopropylphenyl) carbonate, 4-n-butylphenyl phenyl carbonate, di-(4-n-butylphenyl) carbonate, 4-iso-butylphenyl phenyl carbonate, di-(4-iso-butylphenyl) carbonate, 4-tert-butylphenyl phenyl carbonate, di-(4-tert-butylphenyl) carbonate, 4-n-pentylphenyl phenyl carbonate, di-(4-n-pentylphenyl) carbonate, 4-n-hexylphenyl phenyl carbonate, di-(4-n-hexylphenyl) carbonate,4-iso-Octylphenyl-phenyl-carbonat, Di-(4-iso- octylphenyl)-carbonat, 4-n-Nonylphenyl-phenyl-carbonat, Di-(4-n-nonylphenyl)-carbonat, 4- Cyclohexylphenyl-phenyl-carbonat, Di-(4-cyclohexylphenyl)-carbonat, 4-(1 -Methyl-1 - phenylethyl)-phenyl-phenyl-carbonat, Di-[4-(1 -methyl-1 -phenylethyl)-phenyl]-carbonat, Biphenyl- 4-yl-phenyl-carbonat, Di-(biphenyl-4-yl)-carbonat, 4-(1 -Naphthyl)-phenyl-phenyl-carbonat, 4-(2- Naphthyl)-phenyl-phenyl-carbonat, Di-[4-(1 -naphthyl)-phenyl]-carbonat, Di-[4-(2- naphthyl)phenyl]-carbonat, 4-Phenoxyphenyl-phenyl-carbonat, Di-(4-phenoxyphenyl)-carbonat, 3-Pentadecylphenyl-phenyl-carbonat, Di-(3-pentadecylphenyl)-carbonat, 4-T r ity I phenyl-ph e n y I - carbonat, Di-(4-tritylphenyl)-carbonat, Methylsalicylat-phenyl-carbonat, Di-(methylsalicylat)- carbonat, Ethylsalicylat-phenyl-carbonat, Di-(ethylsalicylat)-carbonat, n-Propylsalicylat-phenyl- carbonat, Di-(n-propylsalicylat)-carbonat, iso-Propylsalicylat-phenyl-carbonat, Di-(iso- propylsalicylat)-carbonat,n-Butyl salicylate phenyl carbonate, di-(n-butyl salicylate) carbonate, iso-butyl salicylate phenyl carbonate, di-(iso-butyl salicylate) carbonate, tert-butyl salicylate phenyl carbonate, di-(tert-butyl salicylate) carbonate, di-(phenyl salicylate) carbonate and di-(benzyl salicylate)- carbonate.,

[0060] Particularly preferred diaryl compounds are diphenyl carbonate, 4-tert-butylphenyl phenyl carbonate, di-(4-tert-butylphenyl) carbonate, biphenyl-4-yl phenyl carbonate, di-(biphenyl-4-yl) carbonate, 4-(1-methyl-1-phenylethyl)-phenyl phenyl carbonate, di-[4-(1-methyl-1-phenylethyl)-phenyl] carbonate and di-(methyl salicylate) carbonate.

[0061] Diphenyl carbonate is particularly preferred.

[0062] Either one diaryl carbonate or different diaryl carbonates can be used.

[0063] To control or modify the end groups, one or more monohydroxyaryl compounds can be used as chain terminators, for example, which were not used in the preparation of the diaryl carbonate(s). These can be those of the general formula (III), where R A represents linear or branched C1-C34-alkyl, C1-C34-alkylaryl, C1-C34-aryl or -COO- R D where R D represents hydrogen, linear or branched C1-C34 alkyl, C1-C34 alkylaryl or C1-C34 aryl, and R B , R c independently of one another, identically or differently, represent hydrogen, linear or branched C1-C34 alkyl, C7-C34 alkylaryl or C1-C34 aryl.

[0064] Such monohydroxyaryl compounds are, for example, 1-, 2- or 3-methylphenol, 2,4-dimethylphenol, 4-ethylphenol, 4-n-propylphenol, 4-isopropylphenol, 4-n-butylphenol, 4-isobutylphenol, 4-tert-butylphenol, 4-n-pentylphenol, 4-n-hexylphenol, 4-iso-octylphenol, 4-n-nonylphenol, 3-pentadecylphenol, 4-cyclohexylphenol, 4-(1-methyl-1-phenylethyl)-phenol, 4-phenylphenol, 4-phenoxyphenol, 4-(1-naphthyl)-phenol, 4-(2-naphthyl)-phenol, 4-tritylphenol, methyl salicylate, Ethyl salicylate, n-propyl salicylate, iso-propyl salicylate, n-butyl salicylate, iso-butyl salicylate, tert-butyl salicylate, phenyl salicylate and benzyl salicylate.

[0065] Preferred are 4-tert-butylphenol, 4-iso-octylphenol and 3-pentadecylphenol.

[0066] Suitable branching agents can be compounds with three or more functional groups, preferably those with three or more hydroxyl groups.

[0067] Suitable compounds with three or more phenolic hydroxyl groups are, for example, phloroglucinol, 4,6-dimethyl-2,4,6-tri-(4-hydroxyphenyl)-heptene-2, 4,6-dimethyl-2,4,6-tri-(4-hydroxyphenyl)-heptane, 1,3,5-tri-(4-hydroxyphenyl)-benzene, 1,1,1-tri-(4-hydroxyphenyl)-ethane, tri-(4-hydroxyphenyl)-phenylmethane, 2,2-bis-(4,4-bis-(4-hydroxyphenyl)-cyclohexyl]-propane,

[0068] 2,4-bis-(4-hydroxyphenyl-isopropyl)-phenol and tetra-(4-hydroxyphenyl)-methane.

[0069] Other suitable compounds with three or more functional groups are, for example,

[0070] 2,4-Dihydroxybenzoic acid, trimesic acid trichloride, cyanuric acid trichloride and 3,3-bis-(3-methyl-4-hydroxyphenyl)-2-oxo-2,3-dihydroindole.

[0071] Preferred branching agents are 3,3-bis(3-methyl-4-hydroxyphenyl)-2-oxo-2,3-dihydroindole and 1,1,1-tri(4-hydroxyphenyl)ethane. Polymethyl(meth)acrylate can be either polymethyl(meth)acrylate (PMMA) or impact-modified PMMA (sz-PMMA), or blends of PMMA or sz-PMMA. These are available under the Plexiglas brand from Röhm GmbH. Polymethyl(meth)acrylate includes polymers of methacrylic acid and its derivatives, such as its esters, as well as polymers of acrylic acid and its derivatives, and mixtures of both of the above components.

[0072] Preferred are polymethyl(meth)acrylate plastics with a methyl methacrylate monomer content of at least 80% by weight, preferably at least 90% by weight, and optionally 0% by weight to 20% by weight, preferably 0% by weight to 10% by weight, of other vinylically copolymerizable monomers such as, for example, C1- to C8-alkyl esters of acrylic acid or methacrylic acid, e.g., methyl acrylate, ethyl acrylate, butyl acrylate, butyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, and also styrene and styrene derivatives, such as, for example, [alpha]-methylstyrene or p-methylstyrene. Other monomers may be acrylic acid, methacrylic acid, maleic anhydride, hydroxyesters of acrylic acid, or hydroxyesters of methacrylic acid.

[0073] The thermoplastics may also contain fillers, optionally preferably in an amount of up to 30% by weight. Such fillers are known to those skilled in the art. For example, inorganic fillers such as inorganic pigments can be used.

[0074] Suitable inorganic pigments include, for example, oxides such as silicon dioxide, titanium dioxide, zirconium dioxide, iron oxide, zinc oxide, and chromium(III) oxide; sulfides such as zinc sulfide and cadmium sulfide; and compounds such as barium sulfate, cadmium selenide, ultramarine, and nickel chromium titanate. Also suitable as pigments in the present context are carbonates such as calcium carbonate and barium carbonate, and carbon black. A particularly preferred color pigment is barium sulfate. These pigments are incorporated into the composition of the invention in an amount of 0.1 to 30 wt.%, preferably 2 to 15 wt.%, based on the weight of the composition.

[0075] The thermoplastics may also contain scattering pigments as fillers, which are well known to the person skilled in the art and are described, for example, in WO-A 2007 / 045380.

[0076] These fillers can preferably be used in average particle sizes ranging from 0.01 pm to 50 pm. The thermoplastics can also contain additives in dissolved or dispersed form that serve to improve processability, stabilization, or functionalization.

[0077] For example, release agents and thermal stabilizers can be used to improve processing during injection molding, extrusion, and / or forming. For long-term stabilization, the plastics can also contain UV absorbers and hindered amine light stabilizers (HALS). Dyes and pigments can also be used to create special absorption and / or reflection properties. Furthermore, functional components can be added, such as photochromic dyes, which cause a color change upon UV irradiation, or dichroic dyes, which can be used to create polarizing properties.

[0078] The film pieces made of at least one thermoplastic material to be formed according to the invention can also be a multilayer coextrusion film made of at least two different thermoplastic materials.

[0079] The plastic films are usually produced by extrusion or coextrusion.

[0080] The plastic films can be at least partially printed, metallized and / or otherwise coated on one or both sides.

[0081] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations indicated, but also in other combinations or in isolation, without departing from the scope of the present invention.

[0082] The invention is explained in more detail below using exemplary embodiments with reference to the accompanying drawings, which also disclose features essential to the invention. These exemplary embodiments are for illustrative purposes only and are not to be interpreted as restrictive. For example, a description of an embodiment with a large number of elements or components should not be interpreted to mean that all of these elements or components are necessary for implementation. Rather, other embodiments may also contain alternative elements and components, fewer elements or components, or additional elements or components. Elements or components of different embodiments may be combined with one another unless otherwise stated. Modifications and variations described for one of the exemplary embodiments may also be applicable to other embodiments.To avoid repetition, identical or corresponding elements in different figures are designated by the same reference numerals and are not explained more than once. The figures show:

[0083] Fig. 1 is a sectional view of an embodiment of the fixing unit 1 according to the invention;

[0084] Fig. 2 is a plan view of the fixing unit of Fig. 1;

[0085] Fig. 3 is a view of the underside 13 of the clamping frame 10 of Fig. 1;

[0086] Fig. 4 is a schematic representation of the device 20 according to the invention for

[0087] high pressure forming;

[0088] Fig. 5 is an enlarged sectional view of the fixing unit 1 positioned on a carriage 22 of the high-pressure forming device 2;

[0089] Fig. 6 is a schematic representation of the heating device 25 of the high-pressure forming device 20;

[0090] Fig. 7 to 9 are schematic representations of the high-pressure device 26 of the high-pressure deformation device 20 for explaining the isostatic high-pressure deformation of the plastic film 5;

[0091] Fig. 10 is a sectional view of the manufactured plastic molded part 50;

[0092] Fig. 11 is a sectional view of another embodiment of the fixing unit 1 according to the invention;

[0093] Fig. 12 is a sectional view of another embodiment of the fixing unit 1 according to the invention;

[0094] Fig. 13 is a plan view of the fixing unit of Fig. 12, and

[0095] Figs. 14 and 15 are schematic representations of the high-pressure device 26 of the high-pressure forming device 20 for explaining the isostatic high-pressure forming of the plastic film 5 according to another embodiment. In the embodiment shown in Fig. 1, the fixing unit 1 according to the invention for fixing a plastic film 5 for a high-pressure forming device comprises a base frame 2 with a first through-opening 3 and a top side 4.

[0096] The plastic film 5 is positioned on the upper side 4 of the base frame 2 (hereinafter also referred to as the base plate 2) in such a way that it covers the entire first through-opening 3 and rests on an edge zone 6 of the upper side 4 that delimits the first through-opening 3. The first through-opening 3 is circular, as can be seen, for example, from the top view in Fig. 2. Of course, other delimiting contours of the first through-opening 3 are also possible, such as square, rectangular, oval, or polygonal.

[0097] The base frame 2 has eight pins 7 arranged in a rectangle (here in a square) in the edge zone 6, which protrude upwards from the upper side 4, although other arrangements and / or a different number of pins 7 as well as other geometries as pins are also possible.

[0098] In the embodiment described here, the plastic film 5 is square in shape so that it can be placed on the top side 4 of the base frame 2 precisely in the area defined by the pins 7. Clear positioning can also be achieved using additional pins (or other geometries and / or recesses). This can be advantageous, for example, with pre-printed plastic films 5.

[0099] A clamping frame 10 is positioned on the plastic film 5 (Figures 1 and 2), which has a second circular through-opening 11 with a smaller diameter than the first through-opening 3 of the base frame 2. Of course, other boundary contours of the second through-opening 11 are also possible, such as square, rectangular, oval or polygonal. The clamping frame 10 is also square in shape so that it can be positioned exactly in the area on the plastic film 5 delimited by the pins 7. The clamping frame 10 then rests with its underside 13 on the plastic film 5 and thereby presses this flat onto the edge zone 6 of the top side 4 of the base frame 2. The edge zone 6 is thus the area of ​​the top side 4 that extends from the edge of the first through-opening 3 to the area on the top side 4 delimited by the pins 7.

[0100] The pins 7 thus serve, on the one hand, to determine the position of the plastic film 5 on the base frame 2 and to determine the position of the clamping frame 10 on the plastic film 5. On the other hand, the pins 7 serve as a stop and ensure that the positions of the plastic film 5 and the clamping frame 10 relative to the base frame 2 and in particular relative to the first through opening 3 of the base frame 2 are securely maintained, even if the fixing unit 1 is moved in the high-pressure forming device, as described below.

[0101] The square design of the plastic film 5 and the clamping frame 10 is merely exemplary. Of course, other contours can also be realized. What is essential is the flat and preferably circumferential contact of the plastic film 5 with the upper side 4 of the base frame 2 due to the clamping frame 10 resting on the plastic film 5.

[0102] As can be seen in the sectional view of Fig. 1, the base frame 2 and the clamping frame 10 are designed such that when the plastic film 5 is fixed, the two through openings 3, 11 are aligned coaxially with each other.

[0103] As can be seen in particular from Fig. 3, the underside 13 of the clamping frame 10 has an annular groove 14 with a larger inner diameter than the diameter of the first through-opening 3. An annular seal 15 is located in the groove 14 and protrudes beyond the underside 13. The seal 15 can be made of a heat-resistant elastomer, such as FKM (fluororubber). As shown in Fig. 1, the seal 15 thus rests on the upper side of the plastic film 5 in an area within the first through-opening 3.

[0104] In the embodiment described here, both the underside 13 and the top side 16 of the clamping frame 10 are flat. The plastic film 5 is thus secured by the weight of the clamping frame 10, which presses the plastic film 5 against the top side 4 of the base frame 2. The clamping frame 10 can have a panel thickness of 2 mm - 50 mm, preferably 5 mm - 10 mm. The panel thickness of the clamping frame 10 can be selected in particular such that the weight of the clamping frame 10 is sufficient to ensure the desired fixation of the plastic film 5.

[0105] The fixing unit 1 is designed for a device 20 for high-pressure forming, as shown schematically in Fig. 4. The high-pressure forming device 20 comprises a conveyor device 21 with a carriage 22 for receiving the fixing unit 1, a conveyor belt or a conveyor chain 23 and a drive 24, a heating device 25, a high-pressure device 26 and a control unit S for controlling the high-pressure forming device 20. The control unit S can, for example, have a processor P and a memory M. In the illustration in Fig. 4 and the enlarged partial illustration in Fig. 5, the carriage 22 is in the loading / unloading position, with the complete fixing unit 1 already being placed on the carriage 22 or in a recess 27 of the carriage 22.In the region of the recess 27, the carriage has a third through-opening 28 which is larger than the first and second through-openings 3, 11 and completely covers the first and second through-openings 3, 11, as can be clearly seen, for example, in the enlarged illustration in Fig. 5.

[0106] A fixing unit 1 fastened in this way on the carriage 22 can be transported by means of the conveyor device 21 into the heating device 25, in which, as schematically shown in Fig. 4 and 6, two controllable planar heat sources 29i and 292 are arranged. The two heat sources 29i and 292 are preferably arranged and / or designed such that they provide the same heating power. This can be achieved, for example, in the event that the planar heat sources 29i and 292 already provide the same heating power, by having them at the same distance from the plastic film 5 in a direction from one heat source 29i to the other heat source 292. In practice, however, differences can arise, for example due to convection, which are then compensated for by controlling the power of the two planar heat sources 29i and 292.

[0107] The heat sources 29i and 292 heat the plastic film 5 fixed in the fixing unit 1 above its softening point. Due to the clamping frame 10, the plastic film 5 is not heated with the same intensity in the area of ​​the edge zone 6 as in the area of ​​the through-opening 11, so that the film temperature in the edge zone generally remains below the softening point. This results in a circumferentially stabilized plastic film 5.

[0108] The plastic film 5 heated in this way is then transported by means of the conveyor device 21 into the high-pressure device 26, in which an isostatic high-pressure forming is carried out by applying a fluid pressure medium.

[0109] For this purpose, the high-pressure device 26 comprises a pressure chamber 30, which can be closed and opened, as described below. The pressure chamber 30 has a first and a second sub-chamber 31 and 32.

[0110] The first sub-chamber 31 forms a pressure bell and is typically arranged at the top, so that the open cavity 33 of the pressure bell 31 points downwards. Furthermore, the first sub-chamber 31 comprises a downward-facing, annular contact surface 34, the inner contour of which is circular here and preferably has the same diameter as the second through-opening 11 of the clamping frame 10. However, it is also possible for the diameter of the inner contour of the annular contact surface 34 to be slightly smaller or slightly larger than the diameter of the second through-opening 11 of the clamping frame 10. The inner contour of the annular contact surface can alternatively have a diameter that is larger than the diameter of the second through-opening 11. An annular seal 35 is arranged on the contact surface 34 (e.g., in an annular groove not shown), which protrudes from the contact surface 34. The annular seal 35 can, for example,It can be circular, oval, polygonal or have the shape of any other closed trajectory curve.

[0111] The first subchamber 31 contains a channel 36 that opens into the cavity 33 and through which a fluid pressure medium can be supplied and removed again, as indicated by the arrows P1 and P2. For this purpose, a schematically illustrated valve 37 is arranged to supply and discharge the fluid pressure medium.

[0112] The second sub-chamber 32 comprises a base plate 38, which supports the tool 39 (or mold 39) with the desired contour 40 for the plastic film 5. Furthermore, the second sub-chamber 32 comprises a chamber wall 41, which is spring-mounted on the base plate 38 and laterally encloses the tool 39. The springs 42 shown schematically are provided for the spring-mounted support.

[0113] The chamber wall 41 has an upwardly pointing end 43 which is stepped, wherein the step height corresponds at least to the thickness of the base frame 2 (the step height can, for example, preferably be minimally above the thickness of the base frame 2, which can be, for example, 50 μm to 10 mm, 0.2 mm to 5 mm, 1 mm to 3 mm, 0.5 mm - 2 mm or 0.5 mm to 1 mm) and the upwardly projecting part 44 of the stepped end 43 has an outer diameter which is smaller than the diameter of the first through-opening 3 of the base frame 2 and an inner diameter which corresponds to the diameter of the second through-opening 11 of the clamping frame 10. Furthermore, the upwardly projecting part 44 of the stepped end 43 has a contact surface 45.

[0114] In the illustration shown in Fig. 7, the pressure chamber 30 is shown in its open position, in which the carriage 22 with the fixing unit 1 can be positioned between the two sub-chambers 31 and 32. As soon as the carriage 22 is accordingly positioned, the second sub-chamber 32 can be moved upwards in the direction of the first sub-chamber 31 via a lifting device 47, whereby the second sub-chamber 32 lifts the fixing unit 1 from the carriage 22 by means of the stepped end 43. If the step height of the upwardly projecting part 44 is greater than the thickness of the base frame 2, the upwardly facing part 44 lifts the plastic film 5 (the contact surface 45 presses against the plastic film 5) together with the clamping frame 10 from the base frame 2, so that an air gap 46 is formed between the plastic film 5 and the base frame 2, as shown schematically in Fig. 8.At the same time, the tool 39 is moved upward relative to the chamber wall 41 by the base plate 38 being in contact with an underside of the wall 41 against the force of the springs 42. As a result, the tool 39, with its contour 40, is already in contact with the plastic film 5 (as shown in Fig. 8) or is at a slight distance from the plastic film 5.

[0115] As can also be seen from Fig. 8, the pressure chamber 30 is thus closed, whereby the necessary sealing of the pressure chamber 30 (indicated by arrows D1 and D2) with the plastic film 5 clamped between the two sub-chambers 31 and 32 is achieved by means of the seals 35 and 15 and the contact of the contact surface 45 with the plastic film 5. Thus, the clamping frame 10 is part of the pressure chamber 30.

[0116] In this closed position of the pressure chamber 30 shown in Fig. 8, the fluid pressure medium is guided into the cavity 33 via the channel 36, so that an overpressure is created which leads to an isostatic deformation of the plastic film 5, which is thereby pressed against the contour 40 of the tool 39.

[0117] Thereafter, the fluid pressure medium is discharged from the cavity 33 and, if necessary, the pressure chamber 30 is closed until the deformed plastic film 5 has cooled sufficiently.

[0118] After this deformation of the plastic film 5 has been carried out, the desired plastic molded part 50 is present and the pressure chamber 30 is brought back into its open position (Fig.

[0119] 9). The fixing unit 1 is then placed back on the carriage 22 and is transported back to the loading / unloading position together with the deformed plastic film 5. Thus, a plastic molded part 50 (Fig. 1) was formed from the plastic film 5 in the manner described.

[0120] 10) were manufactured.

[0121] During all movements of the carriage 22, the pins 7 serve to ensure that the plastic film 5 and the clamping frame 10 maintain their position.

[0122] Since the plastic film 5 is positioned in the fixing unit 1 both during heating and during deformation, the plastic film 5 is always fixed or clamped in the edge zone 6 around the entire first through-opening 3, so that any distortion of the shape of the plastic film 5 during heating above the softening point and during deformation can be prevented as effectively as possible. When the plastic film 5 is lifted from the base frame 2, as shown in Fig. 8, the desired fixing is achieved by the contact surface 45, which presses the plastic film 5 against the underside 13 of the clamping frame 10. Such distortion would occur in particular because the plastic films 5 used are usually produced using an extrusion process (e.g., flat film extrusion process) and further processed using rollers to adjust film thickness and surface quality.This leads to intrinsic anisotropic stresses in the material, which are released upon heating and would then lead to the undesirable distortion in a previously known variant in which the plastic film 5 is merely placed on the base frame 2 and no clamping frame 10 is provided.

[0123] In the embodiment described so far, the plastic film 5 is fixed primarily by means of the weight of the clamping frame 10 lying on top. However, it is additionally or alternatively possible to achieve the desired fixation by means of points, teeth and / or a rough surface, wherein the points, teeth and / or the rough surface can be formed on the upper side 4 of the base frame 2 and / or on the underside 13 of the clamping frame 10. Furthermore, a mechanical screw connection or clamping (by means of, for example, a clamping lever, springs, etc.) can be implemented additionally or alternatively. Fixation by magnetic forces is also additionally or alternatively possible.

[0124] The plastic film can be, for example, a PC film (polycarbonate film). For example, the PC film can be Makrofol® DE 1-1 from Covestro Deutschland AG in Germany. The layer thickness of the plastic film 5 (or the film piece 5) can, for example, be in the range from 10 pm to 3000 pm, from 12 pm to 2000 pm, from 100 pm to 2000 pm, from 150 pm to 1000 pm, from 125 pm to 1000 pm (or 175 pm to 1000 pm), from 125 pm to 750 pm, from 125 pm to 600 pm, from 150 pm to 650 pm, and from 250 pm to 600 pm, or from 200 pm to 500 pm. In particular, the layer thickness of the plastic film 5 can be in the range from 350 pm to 650 pm or from 375 pm to 500 pm.

[0125] During deformation in the high-pressure device 26, the fluid pressure medium can be supplied at 2 to 300 bar and preferably at 10 to 100 bar.

[0126] Further details on high-pressure forming can be found, for example, in DE 10 2008 050 564 A1, the content of which is hereby included.

[0127] The softening temperature of the PC plastic film 5 used can be in the range of 144 to 146°C. When heated above the softening temperature, a temperature of greater than 146°C and preferably less than 190°C is generated in the heating device 25. The plastic film can contain any plastic that a person skilled in the art would select for forming. In particular, the plastic is a thermoplastic polymer.

[0128] After the described forming step, further steps can be performed to obtain a desired end product from the plastic molded part 50. In particular, a punching step, a coating step, etc., can be performed. Of course, it is also possible for the plastic molded part 50 itself to be the desired end product.

[0129] Since the fixing unit 1 is provided as a separate unit that is to be placed on the carriage 22 in the loading / unloading position, the fixing unit 1 can be loaded externally and then inserted as a unit into the high-pressure forming device 20 and removed again after forming. If the clamping frame 10 is designed as a pure support frame (e.g., with a sealing ring 15), installation into the fixing unit 1 and removal from the fixing unit 1 can be carried out quickly and easily without significantly affecting the existing process. The handling steps relating to the plastic film 5 are minimized, which also leads to less contamination.

[0130] However, it is also possible to arrange the base frame 2 already in the carriage 22 in the loading / unloading station and to simply place the plastic film 5 and the clamping frame 10 in the manner described. After forming, the clamping frame 10 can be lifted off, and the resulting plastic molded part 50 can be removed.

[0131] Afterwards, a new plastic film 5 and the clamping frame 10 can be placed on top of it so that a further forming process can be carried out.

[0132] Furthermore, it is possible to carry out automation, for example, in such a way that the placing of the plastic film 5 and the clamping frame 10 onto the base frame and the removal of the formed plastic molded part 50 after the forming process is carried out automatically after the clamping frame 10 has been lifted off.

[0133] Fig. 11 shows a modification of the fixing unit 1 according to the invention. In this modification, the plastic film 5 and the clamping frame 10 are placed on the pins 7. For this purpose, the plastic film 5 has through-openings, and the clamping frame 10 has corresponding blind holes or through-bores.

[0134] Figures 12 and 13 show a modification of the fixing unit 1 according to the invention in the same way as in Figures 1 and 2. In this modification, the base frame 2 has two through-openings 3i and 32. Similarly, the clamping frame 10 has two through-openings 111 and 112 as well as two seals 15i and 152. With such a fixing unit 1, the throughput during forming can be doubled, since two plastic molded parts 50 can always be produced. The device 20 for high-pressure forming is, of course, adapted accordingly for this purpose. Thus, in the heating device 25, the plastic film 5 can be heated such that the areas in both through-openings 111 and 112 of the plastic film are heated in the manner described. In the high pressure device 26, two pressure chambers 30 are then provided (one for each pair of through openings 3i, 111 and 32 and 112).

[0135] Of course, it is also possible to provide only one pressure chamber 30 for both pairs of through-holes 3i, 111 and 32, 112. Furthermore, identical or different tools 39 with identical or different contours 40 can be provided. Of course, more than two pairs of through-holes can also be provided.

[0136] In Figures 14 and 15, in the same way as in Figures 7 and 8, a further fixing unit 1 according to the invention and a further method according to the invention for producing a plastic molded part 50 are shown.

[0137] In this embodiment, the pressure chamber 30 is formed such that neither the base frame 2 nor the clamping frame 10 are part of the pressure chamber 30. Instead, the plastic film 5 is clamped directly between the wall 41 and the pressure bell 31, as indicated in Figure 15 by the arrows D1 and D2. In this case, for example, as shown in Figures 14 and 15, an annular seal can be omitted from the clamping frame 10.

Claims

Claims: A method for producing a plastic molded part, in which a) a plastic film (5) is placed on a base frame (2) having a first through-opening (3) such that the plastic film (5) completely covers the first through-opening (3) and lies on an edge zone (6) of a top surface (4) of the base frame (2) that limits the first through-opening (3), b) the plastic film (5) lying on the base frame (2) is heated, and c) the plastic film (5) lying on the base frame (2) and heated in step (b) is subjected to a fluid pressure medium such that the plastic film (5) is pressed against a tool (39) and thereby formed into the plastic molded part (50), characterized in that in step a) a clamping frame (10) having a second through-opening (1 1 ) is positioned on the plastic film (5) lying on the base frame (2) such thatthat the clamping frame (10) presses the plastic film (5) against the top surface (4) of the base frame (2) in the area of ​​the edge zone (6) and thereby fixes it, and that the second through-opening (1 1 ) of the clamping frame (10) is at least partially opposite the first through-opening (3) of the base frame (2), wherein step b) is carried out with the plastic film (5) fixed between the base frame (2) and the clamping frame (10). Method according to claim 1, wherein in step c) the forming is carried out isostatically. Method according to claim 1 or 2, wherein in steps a) and b) the clamping frame (10) presses the plastic film (5) against the top surface (4) of the base frame (2) along a closed path that encloses the first through-opening (3). Method according to one of the above claims, wherein the clamping frame (10) has an annular groove (14) enclosing the second through-opening (1 1 ) in which a seal (15) is seated,which presses against the plastic film (5) in steps a) and b).

5. Method according to one of the above claims, wherein the base frame (2) has several stop elements (7) projecting from its top (4) and in step a) both the plastic film (5) and the tensioning frame (10) are positioned between the projecting stop elements (7).

6. Method according to one of the above claims, wherein the tensioning frame (10) has a flat underside (13) which rests on the plastic film (5) after step a) has been carried out.

7. Method according to any one of claims 1 to 5, wherein the tensioning frame (10) and / or the base frame (2) has points, teeth and / or a rough surface in the area of ​​the edge zone (6) for fixing the plastic film (5).

8. Method according to one of the above claims, wherein a clamping means is provided which applies a force to the clamping frame (10) which presses the clamping frame (10) against the base frame (2) and thereby increases the clamping effect already exerted on the plastic film (5) due to the weight of the clamping frame (10).

9. Method according to one of the above claims, wherein in step c) a pressure chamber (30) is provided in which the forming of the plastic film (5) is carried out, wherein to form the pressure chamber (30) a wall (41) surrounding the tool (39) presses the plastic film (5) against the clamping frame (10), so that the clamping frame (10) is part of the pressure chamber (30) and the base frame (2) is not part of the pressure chamber (30).

10. Method according to any one of claims 1 to 8, wherein in step c) a pressure chamber (30) is provided in which the forming of the plastic film (5) is carried out, wherein to form the pressure chamber (30) the plastic film (5) is clamped directly between a wall (41) surrounding the tool (39) and a wall of a first partial chamber (31), so that neither the clamping frame (10) nor the base frame (2) is part of the pressure chamber (30).

11. Fixing unit for fixing a plastic film for a high-pressure forming device, wherein the fixing unit (1) has a base frame (2) with a first through-opening (3) and a top (4), The plastic film (5) is placed on the base frame (2) such that it completely covers the first through-opening (3) and rests on an edge zone (6) of the top of the base frame (2) that defines the first through-opening (3), characterized in that a clamping frame (10) with a second through-opening (11) is provided, which rests on the plastic film (5) such that the film is pressed against the top (4) of the base frame (2) in the area of ​​the edge zone (6) and thereby fixed, and that the second through-opening (11) of the clamping frame (10) is at least partially opposite the first through-opening (3) of the base frame (2). High-pressure forming device (20) with a conveying device (21), a heating device (25), and a high-pressure device (26), wherein the conveying device (21) incorporates a fixing unit according to claim 11 into the heating device (25) and the high-pressure device. (26) can transport.

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