Method for producing a molded part made of plastic and provided with a UV-cured paint, and said molded part

Abstract

The invention relates to as method for producing a molded part in an injection mold, which molded part is made of plastic and provided with a UV-cured paint, wherein the UV-cured paint forms a visible surface designed as a functional surface. The invention further relates to such a molded part provided with a UV-cured paint, said molded part having a visible surface designed as a functional surface, wherein the UV-cured paint forms said visible surface.

Claims

1. A process for production, in an injection mold, of a plastics molding with a UV-cured lacquer and with a visible area designed as functional area, where the UV-cured lacquer forms said visible area, comprising arranging a film segment that has not been preformed and that is in essence flat, composed of a carrier layer made of a thermoplastic and of a partially thermally cured UV-curable lacquer in a cavity of the injection mold in such a way that the partially cured lacquer layer faces toward a female-mold surface replicating the negative form of the visible area of the molding, and subjecting the film segment arranged in the cavity to insert molding with a thermoplastic on a reverse-side surface facing away from the partially thermally cured UV-curable lacquer, in such a way that the carrier layer of the film segment bonds to the injected hot melt, and wherein a compressive force resulting from the injection pressure of the injected melt acts in the direction of the female-mold surface, whereupon, with exposure to the compressive force and to heating resulting from the direct contact with the hot melt, the entire area of the film segment is forced onto the female-mold surface and subjected to a three-dimensional forming process, removing of the molding, and curing the partially thermally cured UV-curable lacquer to completion by UV radiation and, on the molding, forming the visible area designed as functional area.

2. The process as claimed in claim 1, wherein, before and/or during and/or after the production of the molding, at least a region delimiting the cavity within the injection mold is subjected to temperature control.

3. The process as claimed in claim 1, wherein, in the region of an injection aperture of the injection mold, the film segment is fixed in such a way that the compressive force resulting from the injection pressure of the injected melt acts toward a reverse-side surface facing away from the lacquer layer on the film segment.

4. The process as claimed in claim 1, wherein the thermoplastic injected is loaded with a blowing agent.

5. The process as claimed claim 1, wherein, before the film segment is subjected to insert molding, a color is applied at least on a section of a reverse-side surface facing away from the lacquer layer of the film segment.

6. The process as claimed in claim 1, wherein at least one functional element is injection-molded onto the molding.

7. The process as claimed in claim 1, wherein the molding is produced by subjecting the film segment to insert molding in the single- or multicomponent injection-molding process.

Description

EXAMPLES

(1) The invention is illustrated with reference to examples below, without any restriction to same.

(2) FIG. 1 shows a side view of a mold with inserted film;

(3) FIG. 2 shows a side view of a mold during the insert-molding procedure;

(4) FIG. 3a) shows cracking and fragmentation in comparative film A after the cutting-to-size/punching process, at 50, 150, and 200 magnification;

(5) b) shows visible cracking in the profile of comparative film A after the cutting-to-size/punching process;

(6) FIG. 4 shows a comparative molding A with comparative film A with the following results of insert molding: a) lacquer layer that has undergone the forming process, and small-radius region of the film with cracking, and b) finely structured surface of the lacquer layer with microcracking;

(7) FIG. 5 shows a comparative molding B with comparative film B with visible a) lacquer separation and b) blistering;

(8) FIG. 6 shows a film of the invention after the cutting-to-size/punching process at 50, 150, and 200 magnification;

(9) FIG. 7 shows a molding of the invention with the following results of insert molding: a) lacquer layer that has undergone the forming process with no cracking, and small-radius region of film, b) finely structured surface with no cracking, and c) variously designed surfaces with no cracking, no blistering, and no separation.

1. COMPARATIVE EXAMPLE

(10) Production of a comparative molding A with comparative film A provided with hardened lacquer layer

(11) An optionally reverse-side-printed film made of polycarbonate with layer thickness 280 m and with a hardened lacquer layer based on UV-cured aliphatic urethane acrylate coating in principle corresponding to the disclosure in DE 102010020039A1 was cut to size on a cutting plotter and prepared as 2 D insert. Cracking occurs here at the edge of the film, and separation/fragmentation occurs here in the precured lacquer layer (see FIGS. 3a) and b)).

(12) The film (2), with the lacquer layer, was inserted in the direction of the female mold cavity of the mold (1) for a heating/ventilation panel in an Arburg injection-molding machine, and to some extent pressed manually onto existing cores (FIG. 1). The orientation of the lacquer layer here is toward the external side, and it therefore subsequently represents the visible side of the molding. The mold was then closed, and the film was insert molded with the hot melt (3) (FIG. 2). The locking force here was 200 t, and the screw diameter was 45 mm. The injection time was 2 s. Makrolon 2205 from Bayer MaterialScience AG, Leverkusen, Del., was used as insert-molding material, in the color 901510 (black). Melt temperature was 280 C. and mold temperature was 60 C. As a result of the injection procedure, the temperature and the injection pressure, the film was then converted to its actual shape. A bond was formed here between the film, or the insert, and the thermoplastic material. After cooling, the mold was opened and the molding was removed. The extent of protective covering, and protection, of the small-radius regions of the component by the coated film was partial: about . Cracking in the lacquer layer, extending into the carrier layer, is discernible in the small-radius regions in the micrograph (FIG. 4a)). Even when machine parameters such as melting temperature and mold temperature were varied, no good results were obtained, i.e. when comparative film A with hardened lacquer layer is used, it is not possible to avoid cracking by alterations to the conduct of the process.

(13) An attempt was made to form a grained, finely structured functional area as visible area, by using a grained female mold. When the hardened comparative film A is inserted into a grained mold and subjected to insert molding it is impossible to obtain surface embossment without cracking (microcracks) (FIG. 4b)).

2. COMPARATIVE EXAMPLE

(14) Production of a comparative molding B with comparative film B provided with a thermally dried lacquer layer.

(15) An optionally reverse-side-printed film made of polycarbonate with layer thickness 280 m and with a thermally dried lacquer layer made of a UV-curing acrylate dispersion was cut-to-size and subjected to insert molding as described in example 1.

(16) During the cutting-to-size/punching process, no cracking appeared at the cut edges, and once the insert-molded molding was removed from the mold it was apparent that some separation of the lacquer layer had occurred, and that the some regions of the lacquer layer had blisters (FIGS. 5a) and b)).

3. INVENTIVE EXAMPLE

(17) Production of a molding of the invention with film of the invention provided with a partially thermally cured UV lacquer layer, curing of which can be completed by UV.

(18) An optionally reverse-side-printed film obtainable from Bayer MaterialScience AG, Leverkusen, Makrofol HF 329 G-4 020011, made of polycarbonate, with layer thickness 280 m, with a partially thermally cured lacquer layer, curing of which can be completed by UV, made of a solvent-containing UV-curable binder with additional polyisocyanate crosslinking agent, was cut to size and subjected to insert molding as described in example 1.

(19) During cutting-to-size/punching no cracking appeared at the cut edges (FIG. 6), and once the insert-molded molding of the invention was removed, the component was hardened in a UV system from SSR equipped with a high-pressure mercury lamp. The curing conditions were: UV radiation dose: 2000 mJ/cm.sup.2, belt speed: 3 m/min, distance of lamp from component about 100 mm.

(20) The microtome revealed no cracking in the small-radius region of the lacquer layer (FIG. 7a)).

(21) When this film, equipped with partially thermally cured lacquer layer, curing of which can be completed by UV, is inserted into a grain mold and subjected to insert molding, it is indeed possible to achieve a fine surface embossment. Even when surface structuring of various types, with different levels of complexity, was produced in the lacquer layer, no cracking (microcracks) or blistering or lacquer separation was observed (FIGS. 7b) and c)).

(22) Surprisingly, insert molding was possible without damage to the lacquer layer even at high melt/mold temperatures. Nor were any adverse effects apparent when the machine parameters were altered: examples being melt temperature 280 to 310 C. and mold temperature from 50 to 110 C. It is known that films that have not been precured cannot be subjected to insert molding, because separation of the coating, or blistering can occur to some extent as in comparative example 2. No such effect was observable in the case of the molding of the invention.

(23) Nor was there any adverse effect observable in the injection-compression molding injection-molding process in which the mold initially has a gap which is then closed during or after injection molding, thus avoiding color leaching through the injection-molding composition as it enters.