WO2018073111A1

WO2018073111A1 - Method for producing a plastic body suitable as a decorative element

Info

Publication number: WO2018073111A1
Application number: PCT/EP2017/076163
Authority: WO
Inventors: Konstantin LEONHARDT; Roland KÜNZEL; Michael Roppel; Sebastian Bendig
Original assignee: Covestro Deutschland Ag
Priority date: 2016-10-18
Filing date: 2017-10-13
Publication date: 2018-04-26
Also published as: EP3529027A1

Abstract

The present invention relates to a method for producing a plastic body (1), comprising the steps of: a) providing a possibly deformable basic element (2); b) overmoulding or undermoulding the basic element (2) with a transparent or translucent thermoplastic to create a first layer (4) of a transparent or translucent thermoplastic in order to form a preform; c) possibly applying a background film (3) to the first layer (4), formed by the thermoplastic, of the preform; d) encapsulating the preform obtained in step b) or the modified preform obtained in step c) in a transparent or translucent thermoplastic to create a second layer (6) of a transparent or translucent thermoplastic. The invention also relates to a plastic body (1) that can be obtained by such a method and the use thereof as a decorative element, in the automobile industry or in a lighting system.

Description

Process for producing a plastic body which is suitable as a decorative element

The present invention relates to a method of manufacturing a plastic body containing a decorated or printed base. Furthermore, the invention relates to the plastic body obtained by the manufacturing method and the use of this plastic body as a decorative element.

Plastic bodies which contain a partially printed film are known in the art. Thus, US 2007141353 A1 describes a process for the production of decorative plastic compositions which have a decorative layer, a backing layer and a clear outer layer. In this case, an injection molding process can be used for the production.

In order to obtain visually appealing plastic bodies, it is often desirable to have an appearance which, by means of an optical effect, makes the decorative element or the print appear three-dimensional on the film. For example, CN 101954703 AI describes an injection molding process for producing a plastic body. In the process, a first injection molding step is carried out on the decorative film with a transparent injection molding material in order to obtain a first body. The body thus obtained has a transparent injection-molding material on one side of the decorative film. After resting the body thus obtained, it is provided in a second injection molding step on the side on which there is no injection molding material, with a non-transparent injection-molded material. The decoration of the obtained plastic body achieves a three-dimensional effect by the double injection molding.

It is an object of the present invention to provide a low shrinkage plastic body which has a three-dimensional effect of the decorated or printed base and to provide a method of manufacturing the same. Another object of the present invention is to provide a plastic body having a three-dimensional effect of the decorated or printed base having improved optical imaging properties and lower internal stress. The object is achieved by a method for producing a plastic body comprising the steps: a) providing an optionally deformable primitive; b) over or under molding the base member with a transparent or translucent thermoplastic to produce a first layer of transparent or translucent thermoplastic to form a preform; c) optionally applying a background film to the first layer of the preform formed by the thermoplastic;

Overmolding the preform obtained in step b) or the modified preform obtained in step c) with a transparent or translucent thermoplastic to produce a second layer of a transparent or translucent thermoplastic.

The term "substantially" is defined for the present invention to be 95%, preferably 98%, more preferably 99%, even more preferably 99.9% of the particular property or characteristic to which it refers if The invention furthermore relates to a plastic body obtainable by the method according to the invention, in which the base element is preferably located substantially in the center of the plastic body.

The invention further relates to the use of such a plastic body as a decorative element, in particular in the automotive industry, for example as a gear selector lever or warning flasher. The plastic body according to the invention can also be used in a lighting system as a lens with at least one light-emitting diode as the light source.

The optionally deformable basic element has at least in one sub-area an ornament or print on, which is also referred to below as a decoration. In the method according to the invention, the base element can thus be a plastic film which is partially printed. An ornamented base element is also understood to mean a decorative element which is of a cast, for example a shape made of plastic, but not a cuboid or cube. In a preferred embodiment, the base element is a film which is at least partially decorated or printed with a decoration, in particular printed. In the decoration, in particular the printing, it can, for example, to a company emblem, a vehicle type or vehicle class name, a text or a purely decorative pattern.

The base element, in particular if it is a film, is preferably deformed before overmolding or backmolding. As a result, a higher positional accuracy and / or symbol tolerance of the basic element in the final plastic body can be achieved. This can be achieved, for example, by HPF (High Pressure Forming). For example, EP 2 197 656 B1 describes such a process for producing a thermoformed film part made of thermoplastic material. In the method, a piece of film is mounted in a defined arrangement on a frame, which is placed so as to rest on the frame piece of film in a heating zone, and there heats at least the film portion to a predetermined temperature. The thus heated piece of film is then quickly introduced into a deformation zone where it is directly and directly charged with a fluid pressure medium and deformed to the desired deep-drawn part.

After providing the primitive, in the next step it will be over-injected or back-injected on one side to obtain a preform.

If the base element is a foil, it can additionally be deformed in that case, at least in a partial region of the decoration, in particular the printing, has a stronger three-dimensional deformation.

By the targeted deformation before or during the over- or Hinterspritzens of only partial areas of the primitive effects can be achieved, such as the moiré effect, in which a superposition of two different structures, namely the decoration and the deformation takes place. This also allows the simulation of patterns or inlays. The three-dimensional deformation is preferably an elevation of the subarea of the basic element, in particular of the subarea of the decoration, in particular of the printing.

In this case, the deformation takes place by overmolding or back-molding of the base element with a transparent or translucent thermoplastic in an optionally shaping injection mold. In this case, a layer is obtained whose surface, which faces away from the base element, is essentially flat or smooth. The transparent or translucent layer thus obtained achieves a depth effect which dimensional effect of the primitive still improved. Also, this improves the stability of the preform in comparison to the base element.

A transparent thermoplastic is understood to be one which, in the range from 400 nm to 800 nm, determines a transmission of at least 75%, determined according to ISO 13468 at a thickness of 1 mm, preferably at least 85%, and a haze of at most 10% according to ASTM Dl 003 at a layer thickness of 1 mm, preferably of at most 5%. A translucent thermoplastic is understood to mean one which has a transmission of at least 5%, determined to ISO 13468 at a thickness of 1 mm, preferably at least 10%, in the range from 400 nm to 800 nm, and a haze of more than 10%. , determined according to ASTM D1003 at a layer thickness of 1 mm, preferably of at least 15%.

For example, DE102007011338 A1 describes a method and an apparatus for producing thick-walled, optical components made of plastic by a multi-stage injection molding process in which a shell-shaped construction of the component takes place from the inside to the outside in an at least two-stage process. The result is an optically homogeneous component with significantly higher precision than can be achieved in the conventional injection molding or injection compression molding process.

In a preferred embodiment, the base member is a plastic film which is at least partially decorated or printed, in a more preferred embodiment this plastic film is transparent, in the most preferred embodiment the plastic film is additionally deformed prior to step b). The use of a transparent partially printed plastic film enhances the impression of the imprint as a free-floating three-dimensional element. In the present invention, plastic film includes both a monolayer film and a multilayer film, e.g. a film obtained by co-extrusion understood.

Materials used for the base member, and especially the plastic film, are preferably thermoplastics such as polycarbonates, polyacrylates or poly (meth) acrylates, polyamides, polysulfones, polyesters, thermoplastic polyurethanes and polystyrenes, copolymers and blends thereof. Particularly preferred thermoplastics are, for example, polyacrylates, poly (meth) acrylates (eg PMMA, eg commercially available as Plexiglas® Röhm), cycloolefin copolymers (COC, eg commercially available as Topas® from Ticona or Zenoex® from Nippon Zeon or Apel® from Japan Synthetic Rubber), polysulfones (eg commercially available as Ultrason® from BASF or Ude® from Solvay), polyesters, for example polyethylene terephthalate (PET) or polyethylene naphthalate, polycarbonate (PC ), Polycarbonate / polyester blends such as PC / PET, polycarbonate, polycyclohexylmethanol cyclohexanedicarboxylate (PCCD, eg, commercially available as Xylecs® from GE), polycarbonate, polybutylene terephthalate (PBT), and blends thereof. Preferably, the transparent or translucent thermoplastic from step b) is selected from polycarbonates, polyacrylates, poly (meth) acrylates, polyamides, polysulfones, polyesters, thermoplastic polyurethanes, polystyrenes, their copolymers and mixtures thereof. In a particularly advantageous and preferred embodiment of the present invention, the thermoplastic comprises polycarbonate or copolycarbonate.

Suitable polycarbonates according to the invention are all known polycarbonates. These are homopolymers, copolycarbonates and thermoplastic polyestercarbonates. These preferably have average molecular weights Mw of from 18,000 to 40,000 g / mol, preferably from 26,000 to 36,000 g / mol and in particular from 28,000 to 35,000 g / mol, determined by measuring the relative solution viscosity in dichloromethane or in mixtures of equal amounts by weight of phenol / o-dichlorobenzene , calibrated by light scattering.

The preparation of the polycarbonates is preferably carried out by the interfacial process or the melt transesterification process, which has often been described in the literature. For example, with reference to the interfacial methods, reference is made to H. Schnell, Chemistry and Physics of Polycarbonates, Polymer Reviews, Vol. 9, Interscience Publishers, New York 1964, page 33 et seq. For Polymer Reviews, Vol. 10, "Condensation Polymers of Interfacial Coatings" and Solution Methods ", Paul W. Morgan, Interscience Publishers, New York 1965, Ch. VIII, page 325. U. Grigo, dr. K. Kircher and dr. PR Müller "Polycarbonates" [polycarbonates] in Becker / Braun, Kunststoff-Handbuch [Polymer Handbook], Volume 3/1, polycarbonates, polyacetals, polyesters, cellulose esters [polycarbonates, polyacetals, polyesters, cellulose esters], Carl Hanser Verlag, Munich, Vienna , 1992, pp. 118 to 145, and EP 0 517 044 A1. The melt transesterification process is described, for example, in the Encyclopedia of Polymer Science, Volume 10 (1969), Chemistry and Physics of Polycarbonates, Polymer Reviews, H. Schnell, Volume 9, John Wiley and Sons, Inc. (1964), and in the patents DE 10 31 512 Bl and US Pat. No. 6,228,973. The polycarbonates can be obtained in the melt transesterification process by reactions of bisphenol compounds with carbonic acid compounds, in particular phosgene or diphenyl carbonate or dimethyl carbonate. Particular preference is given here to the homopolycarbonates based on bisphenol A and copolycarbonates based on the monomers bisphenol A and 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane. Further bisphenol compounds which can be used for the polycarbonate synthesis are disclosed inter alia in WO 2008/037364 Al, EP 1 582 549 A1, WO 2002/026862 Al and WO 2005/113639 Al.

The polycarbonates may be linear or branched. It is also possible to use mixtures of branched and un-branched polycarbonates.

Suitable branching agents for polycarbonates are known and described in the literature, for example in the patents US Pat. No. 4185009 Bl, DE 25 00 092 AI, DE 42 40 313 AI, DE 19 943 642 AI, US Pat. No. 5367044 Bl and in literature cited therein. Further, the polycarbonates may also be intrinsically branched, in which case no branching agent is added in the course of polycarbonate production. An example of intrinsic branching is that of the so-called frieze structures, as disclosed in EP 1 506 249 A1 for the enamel polycarbonates.

In addition, it is possible to use chain terminators in polycarbonate production. The chain terminators are preferably phenols such as phenol, alkylphenols such as cresol and 4-tert-butylphenol, chlorophenol, bromophenol, cumylphenol or mixtures thereof.

In alternative embodiments, the base member may also be a textile, a metal foil, a veneer, or a laminate. In a preferred embodiment, the base element is decorated or printed at least 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 100%, based on the total surface area of the primitive. The embodiments are in ascending order, with increasing percentage preferred. For example, 40% is more preferable than 30% and 30% is more preferable than 20%. In alternative embodiments, in addition to one of the abovementioned percent minimum printing levels, there are maximum decorating or printing levels which are in particular 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20% or 10%. These are preferred in descending order. In Particularly preferred embodiments, the basic element is printed. In a further preferred embodiment, the basic element is decorated or printed on both sides.

In a preferred embodiment, the base member is located substantially in the center of the plastic body. The position is determined by the fact that the side with the largest surface is defined as the bottom of the plastic body and orthogonal to a cross-section. The position of the base element with respect to the bottom and top of the plastic body is determined. Substantially in the middle means that the distances of the primitive to the respective side does not exceed a difference of 20%, preferably 10%, more preferably 5%, most preferably 1%. After step b) of over or under molding of the base member with a transparent or translucent thermoplastic, a preform is obtained. In a preferred embodiment, a background film is applied to the layer of preform formed by the thermoplastic (step c)). The application of the optional background film is preferably carried out during step b) by fixing the background film in the tool or by antistatic charging. Due to the background film, a further aesthetic effect can be achieved. For example, the background foil may be printed with a motif or pattern. In particular, this motif or pattern may be metallic, brushed or carbon structures, diffuser materials or light-extraction materials. Thereby, another optical effect can be obtained, i.a. the decoration of the inserted foil is especially emphasized. As a result, for example, the impression of a floating figure can be enhanced as a decoration if it is in front of a pattern and or on the back side, preferably diffusely illuminated. In a preferred embodiment, the background film is not transparent. This embodiment is also referred to below as a preform. The background film may be constructed from the same selection of materials as the primitive, but independently of it. That is, the materials may be the same or different.

In the case of the plastic body according to the invention, in principle all the films used for this purpose can be constructed from the same polymer material, it being possible for the films to differ in the additive or after-treatment. Thus, for example, the upper cover sheet may be a sheet of polycarbonate, which is equipped with an additional hardcoat coating. The first of the inner foils may, for example, also be a polycarbonate foil provided with screen printing. The underlying second inner foil can also be constructed of polycarbonate and colored gray or slightly diffused, and the lower film - also made of polycarbonate - can be provided with a screen print to decouple the side fed light to the front can.

Furthermore, the method comprises the step of completely overmolding the preform (step d)). The process of extrusion molding is known to the person skilled in the art. The method of extrusion molding is described for example in the publications WO 2012/069590 AI, EP 2402140 AI and DE 102007011338 AI. The preform is in this case encapsulated with a further layer of a transparent or translucent thermoplastic, so that this further layer of transparent or translucent thermoplastics lays seamlessly around the surface of the preform.

The transparent or translucent thermoplastics used in steps b) and d) may, in preferred embodiments, consist of the materials as described for the primitive above. The respective thermoplastics may independently contain additives such as dyes and pigments. This can produce an optical effect.

In a preferred embodiment, the base member and the transparent or translucent thermoplastics are made of the same material, preferably a polycarbonate.

In a preferred embodiment, the plastic body according to the invention may contain a second background film. Preferably, this film is mounted on the side which is later after installed state of the plastic body according to the invention in its end use on the side facing away from the viewer.

The surface of the plastic body can be painted with a Hardcoatbeschichtung. In a further preferred embodiment, a cover film is optionally applied to the plastic body. Preferably, this cover sheet is attached to the side which is later after installed state of the plastic body according to the invention in its end use on the side facing the viewer. In a more preferred embodiment, the coversheet is a hardcoat film, which is also referred to as a hardcoat-coated film.

The cover sheet is preferably made of thermoplastics as described above for the base member, which may be coated with a coating agent. Preferred embodiments, in particular of the coating agent (coating / coating) and production method for the cover film are described in US2016152863 AI and WO2014206958 AI.

The invention particularly relates to the following embodiments:

According to a first embodiment, the invention relates to a method for producing a plastic body (1), comprising the steps of: a) providing an optionally deformable basic element (2);

b) over or under molding the base member (2) with a transparent or translucent thermoplastic to produce a first layer (4) of a transparent or translucent thermoplastic to form a preform; c) optionally applying a background film (3) to the first layer (4) of the preform formed by the thermoplastic;

d) overmoulding the preform obtained in step b) or the modified preform obtained in step c) with a transparent or translucent thermoplastic to produce a second layer (6) of a transparent or translucent thermoplastic.

According to a second embodiment, the invention relates to a method according to embodiment 1, characterized in that the base element (2) is a plastic film which is partially printed.

According to a third embodiment, the invention relates to a method according to embodiment 1 or 2, characterized in that the transparent or translucent thermoplastic of the first layer (4) of step b) is selected from polycarbonates, polyacrylates, poly (meth) acrylates, polyamides, Polysulfones, polyesters, thermoplastic polyurethanes, polystyrenes, their copolymers and mixtures thereof, preferably polycarbonate.

According to a fourth embodiment, the invention relates to a method according to one of the preceding embodiments, characterized in that the background film (3) is preferably applied at the same time as step b). According to a fifth embodiment, the invention relates to a method according to one of the preceding embodiments, characterized in that the material of the background film (3) is selected from polycarbonates, polyacrylates, poly (meth) acrylates, polyamides, polysulfones, polyesters, thermoplastic polyurethanes, polystyrenes, their copolymers and mixtures thereof, preferably polycarbonate.

According to a sixth embodiment, the invention relates to a method according to one of the preceding embodiments, characterized in that the transparent or translucent thermoplastic of the second layer (6) from step d) is selected from polycarbonates, polyacrylates, poly (meth) acrylates, polysulfones, polyesters , thermoplastic polyurethanes, polystyrenes, their copolymers and mixtures thereof, preferably polycarbonate.

According to a seventh embodiment, the invention relates to a method according to one of the preceding embodiments, characterized in that in step d) or subsequently a back-molding of a cover film (5), preferably a hardcoat-coated cover film, takes place.

According to an eighth embodiment, the invention relates to a method according to embodiment 7, characterized in that the material of the cover sheet (5) is selected from polycarbonates, polyacrylates, poly (meth) acrylates, polysulfones, polyesters, thermoplastic polyurethanes, polystyrenes, their copolymers and mixtures thereof, preferably polycarbonate.

According to a ninth embodiment, the invention relates to a method according to one of the preceding embodiments, characterized in that in step d) or subsequently an overspraying of a further background film (7) takes place.

According to a tenth embodiment, the invention relates to a method according to embodiment 9, characterized in that the background film (7) is a film for increasing the brightness.

According to an eleventh embodiment, the invention relates to a plastic body (1) obtainable by a method according to one of the embodiments 1 to 10. According to a twelfth embodiment, the invention relates to a plastic body according to embodiment 11, characterized in that the base element (2) is located substantially in the center of the plastic body (1).

According to a thirteenth embodiment, the invention relates to the use of a plastic body according to one of the embodiments 11 or 12 as a decorative element.

According to a thirteenth embodiment, the invention relates to the use according to embodiment 13 in the automotive industry, in particular as gear selector lever or warning flasher.

According to a thirteenth embodiment, the invention relates to the use according to embodiment 13 or 14 in a lighting system as a lens having at least one light-emitting diode as the light source.

The present invention will be explained in more detail below with reference to FIG. 1 and an embodiment. It shows

Fig. 1 is a schematic representation of a preferred embodiment of the plastic body.

Fig. 1 shows a side sectional view of a preferred embodiment of the plastic body 1 according to the present invention. The plastic body 1 consists of a base element 2, in the present case in the form of a partially printed plastic film, a first layer 4 made of a transparent or translucent thermoplastic over or under injection, a background film 3, a second layer 6 of a transparent or translucent thermoplastic which has been overmoulded, a background film 7 and a cover film 5.

example

The basic element 2 consists of a polycarbonate film Makrofol® DE1-4 with a total thickness of 250 μm and a surface combination of high-gloss / matt. The base film 2 is decorated using a IMD color system Noriphan HTR N Pröll KG by screen printing and then singulated to a sheet size of 210mm x 240mm. The already decoratively designed film is then in a high-pressure forming system of Niebling GmbH by means of fluid pressure medium in a three-dimensional shape brought so that the decorative element receives a defined position. The design and the decoration of the individual basic elements differ from each other and are determined by the respective positioning of the film 2, 3, 5, 7 in the injection molding.

For further production of the plastic body 1, a 2-component injection molding machine and a two-layer lens tool is used. The first tool cavity forms the negative shape of the core contour 4. Here, the base element 2 and 3 is inserted into the respective tool halves of the preform and positioned in the tool antistatic or on the shape of the film insert. The mold temperature is 90 ° C. The preform is centrally filled with plastic melt via a side-mounted tunnel gate and back-injected or over-injected with the respective foil inserts. The melt temperature of the polycarbonate Makroion® LED2245 is 280 ° C. In a further step, the foil inserts 5 and 7 are also inserted into the second tool cavity. Insert 5 consists of a hardcoat-coated film Makrofol® HF278 and forms the later visible side of the component. The insert 7 consists of a diffuser film Makrofol® LM228 and forms the side facing away from the viewer side. After the preform has cooled down, it is removed from the first cavity, transported to the further cavity and held in the cavity with exact position in the cavity via two lateral retaining tabs. As in the production of the preform, a transparent polycarbonate is also used in the subsequent work cycle. In the further process step, plastic melt is introduced again via a tunnel gate. The Folieninserts 5 and 7 are each injected behind or over-molded and the preform symmetric 6 overmolded.

LIST OF REFERENCE NUMBERS

(1) plastic body

(2) primitive

(3) Background film

(4) First layer of a transparent or translucent thermoplastic

(5) cover sheet

(6) Second layer of a transparent or translucent thermoplastic

(7) Background film

Claims

claims

1. A method for producing a plastic body (1), comprising the steps of: a) providing an optionally deformable base element (2);

2. The method according to claim 1, characterized in that the base element (2) is a plastic film, which is partially printed.

3. The method according to claim 1 or 2, characterized in that the transparent or translucent thermoplastic of the first layer (4) of step b) is selected from polycarbonates, polyacrylates, poly (meth) acrylates, polyamides, polysulfones, polyesters, thermoplastic polyurethanes, Polystyrenes, their copolymers and mixtures thereof, preferably polycarbonate.

4. The method according to any one of the preceding claims, characterized in that the background film (3) is preferably applied at the same time as step b).

5. The method according to any one of the preceding claims, characterized in that the material of the background film (3) is selected from polycarbonates, polyacrylates, poly (meth) acrylates, polyamides, polysulfones, polyesters, thermoplastic polyurethanes, polystyrenes, their copolymers and mixtures thereof, preferably polycarbonate.

6. The method according to any one of the preceding claims, characterized in that the transparent or translucent thermoplastic of the second layer (6) from step d) is selected from polycarbonates, polyacrylates, poly (meth) acrylates, polysulfones, Polyesters, thermoplastic polyurethanes, polystyrenes, their copolymers and mixtures thereof, preferably polycarbonate.

7. The method according to any one of the preceding claims, characterized in that in step d) or subsequently a back-molding of a cover film (5), preferably a hardcoat-coated cover film takes place.

8. The method according to claim 7, characterized in that the material of the cover sheet (5) is selected from polycarbonates, polyacrylates, poly (meth) acrylates, polysulfones, polyesters, thermoplastic polyurethanes, polystyrenes, their copolymers and mixtures thereof, preferably polycarbonate.

9. The method according to any one of the preceding claims, characterized in that in step d) or subsequently overmolding of a further background film (7).

10. The method according to claim 9, characterized in that the background film (7) is a film for increasing the brightness.

11. plastic body (1), obtainable by a method according to one of claims 1 to 10.

12. Plastic body according to claim 11, characterized in that the base element (2) is located substantially in the middle of the plastic body (1).

13. Use of a plastic body according to one of claims 11 or 12 as a decorative element.

14. Use according to claim 13 in the automotive industry, in particular as a gear selector lever or warning flasher.

15. Use according to claim 13 or 14 in an illumination system as a lens having at least one light emitting diode as the light source.