Method for producing an injection molded part, injection molded part and intermediate product

Abstract

The invention relates to a method for producing an injection molded part (50), wherein in particular the following steps are carried out in the following order: a) providing an insert film or insert sheet, wherein the insert film or insert sheet (10) comprises a haptics layer (11); b) applying a cushioning protection film comprising an adhesive layer (21) and a cushioning layer (22) onto the haptics layer (11) of the insert film or insert sheet (10); c) inserting the insert film or insert sheet (10) into an injection mold (60) of an injection molding machine such that the cushioning protection foil (20) is in contact with the walls of the injection mold (60); d) back injection molding the insert film or insert sheet (10) with a plastic compound to provide the injection molded part (50); e) removing the injection molded part (50) from the injection mold (60).

Description

Technical Field

[0001] This invention relates to a method for producing injection-molded parts, as well as injection-molded parts and intermediate products. Background Technology

[0002] To produce decorative molded parts, insert molding processes are typically used. For this purpose, inserts, which can be embedded films or insert sheets, are back-injected with a plastic compound in an injection molding machine. To provide injection-molded parts with a tactilely perceptible surface, these insert sheets or films include a tactile layer. The tactile layer then forms the outermost layer of the injection-molded part. Typically, these insert sheets or films are first deep-drawn or vacuum-formed before back-injection molding. The pre-formed insert sheet or film is then placed in the injection molding machine and back-injected. Due to the high temperatures and pressures during injection molding, deep drawing, and vacuum forming, the outer tactile layer is severely damaged and deformed. This results in a diminished tactile effect that does not meet customer requirements in terms of tactile feel or visual appearance. Summary of the Invention

[0003] The aim is to provide a method for producing injection-molded parts including tactile structures and injection-molded parts including tactile structures, wherein the resulting tactile effect is improved.

[0004] This objective is achieved by a method for producing injection-molded parts, wherein the following steps are performed in particular in the following order:

[0005] a) Provide an embedded film or embedded sheet, wherein the embedded film or embedded sheet includes a tactile layer;

[0006] b) Apply a cushioning protective film, including an adhesive layer and a buffer layer, to the tactile layer of the embedded film or embedded sheet;

[0007] c) Embed the embedded film or embedded sheet into the injection mold of the injection molding machine so that the buffer protective foil contacts the wall of the injection mold;

[0008] d) Back injection molding of the embedded film or embedded sheet with a plastic compound to provide an injection molded part;

[0009] e) Remove the injection molded part from the injection mold.

[0010] This objective is also achieved by an injection-molded part, which is produced, in particular, by the method according to any one of claims 1 to 29.

[0011] The injection-molded component includes a matrix composed of a plastic compound and a tactile layer fixedly attached to the matrix.

[0012] Additionally, this objective is achieved through an intermediate product comprising an injection-molded part according to any one of claims 30 to 36, preferably produced by the method according to any one of claims 1 to 29, wherein the intermediate product further comprises a releasable cushioning foil adjacent to the tactile layer, wherein the cushioning foil comprises an adhesive layer and a cushioning layer.

[0013] This invention now provides an injection-molded part with an external tactile layer, whereby the tactile layer remains substantially unchanged in shape compared to the tactile layer of an embedded sheet or film in its undeformed state. In other words, the tactile structure or tactile layer of the finished injection-molded part is completely undeformed or only minimally deformed. This is achieved in particular by the fact that a cushioning protective foil is a layer that contacts the mold wall during forming processes such as deep drawing, vacuum forming, or injection molding, and acts as a damping layer. The high pressure and high temperature present during the forming process now compress the cushioning protective foil but not the tactile layer. The result is an injection-molded part with an external tactile layer whose structure has a high-quality optical appearance and is also very easily perceived in terms of tactile sensation.

[0014] Layers and / or membranes should be understood to specifically refer to substantially planar structures, which are correspondingly single-layered or multi-layered. Membranes are preferably self-supporting. Layers may be self-supporting or non-self-supporting, for example.

[0015] Advantageous embodiments of the invention are described in the dependent claims.

[0016] It can be further specified that the following steps are performed after step e):

[0017] f) Peel off the cushioning protective foil from the injection-molded part. After step f), an injection-molded part comprising a substrate and an insert foil or insert sheet is preferably obtained, with the tactile layer on the outer side. If step f) is not performed, an intermediate product corresponding to the finished injection-molded part is preferably obtained, but with the cushioning protective foil remaining on the tactile layer. This cushioning protective foil then continues to be used as a protective layer for further processing steps or for transporting the intermediate product or injection-molded part to the customer.

[0018] Preferably, the embedded film or sheet includes a carrier film, onto which the tactile layer is applied. In this case, the carrier film may ensure the stability of the embedded film or sheet. However, a support layer, particularly a carrier film, may not be necessary, in which case the tactile layer of the embedded film or sheet is self-supporting.

[0019] The carrier membrane may contain materials or combinations thereof selected from the following: polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene (PE), polyvinyl chloride (PVC), acrylonitrile-butadiene-styrene (ABS), polyurethane (PU), polybutylene succinate (PBS), thermoplastic polyurethane (TPU), polypropylene (PP), polylactide (PLA), polyvinyl furanoate (PEF), and / or polyacrylonitrile (PAN).

[0020] The embedded film or sheet can be formed as a multilayer body composed of several layers. Specifically, the embedded film or sheet is specified to have at least one additional layer or combination of layers selected from the following, excluding the tactile layer: an adhesive layer, a decorative layer, a metal layer, a metal oxide layer, a carbon black layer, an adhesion-promoting layer, a primer layer, a color layer, and a functional layer. Preferably, the additional layers are arranged adjacent to or at a distance from the tactile layer.

[0021] The decorative layer can be formed as a single layer or multiple layers. The decorative layer preferably comprises one or more layers.

[0022] The decorative layer may preferably have one or more color layers, particularly colored varnish layers. In each case, these color layers may be differently colored and / or may be formed as transparent and / or opaque, and may also be separated by one or more additional layers, particularly transparent layers. In each case, the color layers may be present on the entire surface or only partially present in their layer planes. The color layers are preferably applied by means of known printing methods selected from: gravure printing, screen printing, offset printing, inkjet printing, pad printing, electrostatic photocopying, or combinations thereof. Here, the color layer may consist of a binder and at least one component or combination of components selected from: colorants, fillers, pigments, optically variable pigments, interference layer pigments, liquid crystal pigments, magnetically oriented pigments, thermochromic pigments, metallic pigments, phosphorescent dyes, and luminescent dyes.

[0023] Additionally, the decorative layer may include one or more reflective layers, which are preferably formed as opaque, translucent, and / or partially reflective. In particular, the reflective layer may consist of a metal and / or an HRI layer (HRI = High Refractive Index), and is therefore a layer with a high refractive index, particularly a refractive index greater than 1.5. For example, aluminum, tin, indium, chromium, silver, gold, or copper, or alloys thereof, are considered metals. For example, ZnS or SiO2 are considered HRI layers.

[0024] Additionally, the decorative layer may have one or more optically active relief structures, particularly diffraction structures and / or holograms and / or refractive structures and / or matte structures. At least one reflective layer is disposed directly on the relief structure, at least in the area.

[0025] In the case of a metallic layer, it is advantageous to apply the metallic layer by vapor deposition, physical vapor deposition (PVD), and / or chemical vapor deposition (CVD) and / or sputtering. Different decorative layers can also consist of different metals, especially metals of different colors.

[0026] The metal layer is preferably applied to a clear varnish layer or a pigment-containing varnish layer. Then, it is advantageous to apply an additional varnish layer to the metal layer as a metal adhesion promoting layer in order to improve the adhesion of the layer constructed thereon.

[0027] In particular, the decorative layer can also form one or more patterns. Patterns can be, for example, graphic outlines, figurative representations, images, visually recognizable design elements, symbols, logos, portraits, designs, repeating patterns, alphanumeric characters, codes, code patterns, cipher patterns, text, color schemes, etc. Patterns can also be personalized.

[0028] Personalization specifically means that the decorative layer includes information items that are individually unique to each individual print, such as, for example, a unique serial number. Personalization also specifically means that the decorative layer includes information items that are the same for a set of prints, but are unique to each set of prints in each case, such as a batch number. In the following text, when the term printing is used, this can mean personalized printing or non-personalized printing.

[0029] Preferably, the primer has an adhesive layer and / or an adhesion-promoting layer. The primer layer may be specified to have a layer thickness ranging from 1 μm to 5 μm. Materials considered for the primer include PMMA, PVC, polyester, polyurethane, chlorinated polyolefin, polypropylene, epoxy resin, or polyurethane-polyol in combination with deactivated isocyanate. Furthermore, the primer layer may contain inorganic fillers. The primer layer is preferably made of PVC for embedding in molding or mold decoration.

[0030] Preferably, the functional layer is an electrical functional layer, for example, in the form of a capacitive element for providing touchpad functionality, resulting in the electrical functional layer being a sensor. Alternatively or additionally, the electrical functional layer may carry at least one light-emitting diode element, such as an organic light-emitting diode (“OLED”). In particular, the electrical functional layer may also have touch functionality and / or RFID functionality. Alternatively or additionally, the electrical functional layer may include conductive wires for providing electrical connection functionality and / or heating functionality.

[0031] Furthermore, it is preferable that the functional layer has a contact area, preferably in a first region. Electrical connections for the element may also be provided, and contact reinforcements may be present in the functional layer, particularly the electrical functional layer, in the first region. The contact reinforcements facilitate contact between the connecting element and the mating contact. The term "region" here means a defined surface area occupied by the embedded film or insert, wherein this surface area lies in a plane formed in a top view of the embedded film or insert. For example, the first region may completely or only partially occupy the entire surface area of ​​the embedded film or insert.

[0032] Functional layers enable a variety of designs that generate exceptionally high-quality optical impressions. They can also be designed as displays and / or touchscreens.

[0033] The functional layer may also preferably have a soft-touch surface and / or an anti-slip coating.

[0034] Preferably, the tactile layer includes a tactile pattern with raised and recessed areas. The tactile pattern can be, for example, a graphically depicted outline, a representation of an image, a visually recognizable design element, a symbol, a logo, a portrait, a pattern, a continuous pattern, alphanumeric characters, codes, code patterns, password patterns, text, color schemes, etc. The tactile pattern can also be personalized.

[0035] Possibly, the bumps have a height ranging from 10 μm to 100 μm, particularly from 20 μm to 50 μm, and preferably from 25 μm to 35 μm. Furthermore, the bumps may have a length and / or width ranging from 0.3 mm to 20 mm, preferably from 1 mm to 5 mm. Additionally, it is preferably specified that the depressions have a width ranging from 0.1 mm to 3 mm, preferably from 0.4 mm to 1 mm. These values ​​achieve precise tactile feedback and a visually appealing surface texture.

[0036] Furthermore, the tactile layer may have a pencil hardness of F or better, preferably measured according to ASTM D3363. See below for reference. Figure 6a and Figure 6b Describe in detail the measurement of pencil hardness. A pencil hardness of F or better ensures that the tactile layer is sufficiently scratch-resistant and therefore resistant to the effects of mechanical environments.

[0037] Preferably, the tactile layer comprises a UV-curable varnish, preferably a polyurethane acrylate resin. This allows the tactile structure to be applied to the varnish without applying significant force, and then the tactile structure is cured using UV radiation. Furthermore, it ensures the durability and scratch resistance of the tactile structure.

[0038] Preferably, the tactile layer is produced or supplied by screen printing. Alternatively, the UV-curable varnish may be pre-cured or fully cured by UV radiation after molding or stamping of the tactile structure. The tactile structure is preferably molded or stamped into the not-yet-finally-cured UV-curable varnish by the action of a stamping tool, and the tactile layer is cured by direct UV light irradiation during or after molding or stamping. Additional UV light irradiation may be applied before and / or during molding or stamping.

[0039] Preferably, the buffer protective foil has a thickness ranging from 10 μm to 100 μm, more preferably from 30 μm to 80 μm, and even more preferably from 50 μm to 70 μm. Such a thickness ensures that the buffer protective foil can be sufficiently compressed so that the tactile structure beneath the tactile layer is not damaged or deformed by the high pressure and high temperature during injection molding, deep drawing, or vacuum forming.

[0040] Specifically, the cushioning protective foil, preferably the adhesive layer of the cushioning protective foil, can have an adhesive force on the tactile layer in the range of 0.01 N / 25 mm to 1 N / 25 mm, preferably from 0.1 N / 25 mm to 1 N / 25 mm, and more preferably from 0.5 N / 25 mm to 1 N / 25 mm. This adhesive force ensures reliable adhesion during processing, preferably during preforming and / or injection molding, and easy removal of the cushioning protective foil thereafter.

[0041] It can also be specified that the buffer protective foil has a strength of 0.5 N / mm. 2 Up to 25 N / mm 2 Preferably from 5 N / mm 2 Up to 25 N / mm 2 More preferably from 5 N / mm 2 Up to 15 N / mm 2 The tensile strength is within a certain range. These tensile strength values ​​advantageously ensure that the cushioning protective foil can withstand forming forces during deep drawing, vacuum forming, or back injection molding.

[0042] Furthermore, the cushioning protective foil can have an elongation ranging from 100% to 250%, preferably from 100% to 200%, and more preferably from 100% to 150%. These elongation values ​​ensure that the cushioning protective foil has sufficient elasticity during forming, especially during deep drawing or vacuum forming or back injection molding, and will not tear during forming.

[0043] Furthermore, it is advantageous that the adhesive layer has a thickness ranging from 0.5 μm to 3 μm, preferably from 1.2 μm to 1.8 μm, and more preferably from 1.5 μm to 1.8 μm. Preferably, the adhesive layer is provided or produced by means of a slit mold.

[0044] Furthermore, the adhesive layer may have a Shore A hardness of 50 or less, preferably measured using a Shore A hardness tester.

[0045] Preferably, the adhesive layer comprises a pressure-sensitive adhesive having an acrylic component. This ensures a reliable bond with the tactile layer, preferably the tactile structure, without permanent adhesion. This means the cushioning protective foil is easily peeled off from the tactile layer, but also has sufficient adhesion to protect the tactile layer (preferably the tactile structure) from deformation during deep drawing, vacuum forming, back injection molding, or other process steps or during transport.

[0046] Advantageously, the buffer layer has a thickness ranging from 10 μm to 100 μm, preferably from 30 μm to 80 μm, and more preferably from 50 μm to 70 μm. Preferably, the thickness of the buffer layer before back injection molding is greater than its thickness after back injection molding. This is because the buffer layer is compressed during back injection molding due to the injection pressure of the plastic compound, undergoing partial elastic compression but also plastic compression. This plastic compression results in the buffer protective foil being thinner after back injection molding than before.

[0047] Furthermore, preferably, the buffer layer may be specified to have a glass transition temperature in the range of 80°C to 110°C, preferably from 85°C to 105°C.

[0048] Advantageously, the buffer layer comprises at least one material or a combination of materials selected from: polyvinyl chloride (PVC), polyethylene (PE), and / or polypropylene (PP). Furthermore, it is preferably specified that the buffer layer may have a Shore A hardness of 25 or less, preferably measured using a Shore A hardness tester. This ensures that the buffer layer has a good damping effect during back injection. Moreover, the buffer layer may conform to the contour of the tactile structure of the tactile layer. This ensures that the tactile layer or tactile structure is well protected against deformation during back injection, deep drawing, and / or vacuum forming.

[0049] Preferably, the application in step b) is performed by means of a lamination process. This allows the cushioning protective foil to be applied to the tactile layer, particularly the tactile structure, in a cavitation-free and contour-following manner.

[0050] Moreover, the lamination temperature in step b) can be in the range of 30°C to 150°C, preferably from 50°C to 100°C, and more preferably from 60°C to 80°C.

[0051] Preferably, the lamination speed in step b) can be in the range of 1 m / min to 5 m / min, preferably from 1.5 m / min to 4 m / min, and more preferably from 2 m / min to 4 m / min.

[0052] Furthermore, the lamination pressure in step b) can be in the range of 10 bar to 100 bar, preferably from 10 bar to 50 bar, and more preferably from 30 bar to 50 bar. This pressure ensures that the cushioning protective foil is applied in a manner that the cushioning protective foil follows the contour of the tactile layer.

[0053] Furthermore, it is possible that, after step b), and particularly before step c), the following steps may be performed:

[0054] b1) Deep draw or vacuum form the embedded foil or sheet together with the applied buffer protective foil.

[0055] This allows the insert sheet or insert film to be pre-formed prior to back injection molding. Preferably, the insert sheet or insert film has already been shaped into the final shape of the injection-molded part, so that the insert sheet or insert film will not undergo further deformation during back injection molding in the injection molding machine. As explained above, the cushioning protective foil is preferably designed so that it can easily withstand the forming forces in step b1).

[0056] Preferably, the deep drawing or vacuum forming in step b1) is performed at a deep drawing temperature or vacuum forming temperature ranging from 50°C to 300°C, preferably from 90°C to 200°C, and more preferably from 120°C to 150°C. This temperature ensures that the insert sheet or insert film, together with the cushioning protective foil, becomes sufficiently stretchable for forming while preserving the tactile structure of the tactile layer.

[0057] It can also be specified that the back injection molding in step d) has an injection temperature in the range of 100°C to 500°C, preferably from 180°C to 400°C, and more preferably from 200°C to 300°C. Furthermore, it is possible that the back injection molding in step d) has an injection pressure in the range of 800 bar to 1300 bar.

[0058] Advantageously, the injection-molded part, particularly the matrix, and / or the plastic compound includes plastic materials, including thermoplastics, especially impact-resistant thermoplastics. Additionally, the plastic materials particularly include polyethylene (PE), polycarbonate (PC), polypropylene (PP), polystyrene (PS), polybutadiene, polyacrylonitrile, polyester, polyurethane, polymethacrylate, polyacrylate, polyamide, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), preferably acrylonitrile-butadiene-styrene (ABS), acrylonitrile-styrene acrylate (ASA), ABS-PC, PET-PC, PBT-PC, PC-PBT and / or ASA-PC and / or copolymers or mixtures thereof. The plastic material may also contain inorganic or organic fillers, preferably SiO2, Al2O3, TiO2, clay minerals, silicates, zeolites, glass fibers, carbon fibers, glass beads, organic fibers, or mixtures thereof. Here, fillers are particularly added to the plastic material to further increase the stability of the injection-molded part, particularly the matrix. In addition, these fillers can reduce the proportion of polymer materials, thereby reducing the production cost and / or weight of injection-molded parts, especially the matrix. The plastic material may also contain inorganic or organic additives that particularly improve its processability. Furthermore, the plastic material can be biodegradable and / or compostable. For example, plastic materials thus include polylactide (PLA) or polylactic acid.

[0059] Furthermore, it is preferably specified that during and / or after step d), the deformation of the tactile structure bulge is less than 10% relative to the height of the bulge, particularly less than 5%.

[0060] Comparative tests were conducted to determine the deformation of the tactile layer, preferably the tactile structure, during back injection molding in injection molding machines with and without a cushioning protective foil. For this purpose, two different embodiments of the embedded film were tested.

[0061] The first embodiment is an embedded film having a single tactile structure in the form of a trident pattern as a tactile layer. The tactile layer has a pencil hardness of F and includes a UV-curable varnish, which is a varnish with 100% solids content in a polyurethane acrylate resin. The trident shape is configured as a single ridge of the tactile structure. The height of the trident is 32µm ± 1µm. In each of the other two spatial directions, the size of the trident is 600µm ± 5µm. These values ​​of the tactile structure are before back injection molding. This embedded film is then back injection molded into an injection molding machine without a buffer protective foil, and the dimensions of the tactile structure or trident shape are then measured. After back injection molding, the height of the tactile structure or trident is 22µm ± 1µm. However, the dimensions in the other two spatial directions remain almost unchanged. The same embedded film with the same tactile structure is also back injection molded, but the difference is that this time, a buffer protective foil is applied to the tactile layer or tactile structure of the embedded film before back injection molding. The cushioning protective foil used was a cushioning protective foil with a cushioning layer and an adhesive layer. The thickness of the cushioning layer was 80 μm ± 2 μm, and the Shore A hardness was <25. The thickness of the adhesive layer was 1.5 μm ± 0.3 μm, and the Shore A hardness was <50. The embedded film with the cushioning protective foil applied was then placed in an injection molding machine, such that the cushioning protective foil contacted one wall of the injection mold, and finally, back injection molding was performed with a plastic compound. The plastic compound was injected at an injection pressure of 1300 bar and an injection speed of 65 m / s. The injection temperature of the plastic compound was in the range of 250°C to 270°C. Furthermore, the injection time was in the range of 2 s to 4 s, and the cooling time was in the range of 15 s to 20 s, with a cooling temperature of 45°C. Finally, the injection-molded part was removed from the mold, the cushioning protective foil was released, and the dimensions of the tactile structure or trident were measured. This resulted in a height of 30.5 µm ± 1 µm for the tactile structure or trident. The dimensions in the other two spatial directions remained unchanged.

[0062] In the second embodiment, a large-area continuous pattern was tested as the tactile structure of the embedded film. The parameters regarding the layer thickness, layer structure, and hardness of the tactile layer and the buffer protective foil were the same as in the first embodiment. The tactile structure was a grid with multiple equally sized squares having a side length of 5 mm. The bulges of the tactile structure were the grid lines of the squares, with a height of 22 µm and a width of 344 µm. For back injection molding of the embedded film without the buffer protective foil, the tactile structure or grid had a height of 2 μm and a width of 417 μm after back injection molding. For back injection molding of the embedded film with the buffer protective foil, the tactile structure had a height of 20 µm and a constant width of 344 µm after back injection molding.

[0063] For a better overview, the results of the comparative tests are shown in the table below.

[0064]

[0065] Therefore, these comparative tests clearly demonstrate that when a cushioning protective foil is used, the deformation of the tactile layer or tactile structure is significantly reduced compared to back injection molding without a cushioning protective foil, as is known in the prior art.

[0066] For both embodiments described above, for the variant with a cushioning protective foil, the adhesive force of the cushioning protective foil on the tactile layer was also measured before and shortly after back injection molding, as well as several days after back injection molding. For this purpose, several samples measuring 20 cm in length and 2.5 cm in width were prepared. Therefore, measurements performed before back injection molding only involved the embedded foil with the cushioning protective foil applied thereto, while measurements performed after back injection molding involved the injection-molded part with the cushioning protective foil. The sample was attached to an aluminum plate with strong double-sided adhesive tape, such that the cushioning protective foil faced away from the aluminum plate. Furthermore, the sample was pressed onto the aluminum plate using rollers. The prepared aluminum plate was then placed in a ZwickRoell GmbH&Co.KG type Z005 testing machine. One end of the cushioning protective foil was then attached to the testing device of the testing machine, and finally, the cushioning foil was pulled away from the embedded foil or from the injection-molded part via the testing device, and the required force was determined. The adhesive forces shown in the table below were determined.

[0067]

[0068] The adhesive force determined during this process ensures that the cushioning protective foil is firmly bonded to the tactile layer, thereby protecting the tactile structure from deformation. Furthermore, the determined adhesive force is also low, allowing the cushioning protective foil to be removed from the tactile layer without leaving any residue and without requiring excessive force.

[0069] This invention is applicable to any tactile surface requiring injection-molded components. This can be used, for example, in the automotive industry, particularly for cockpit components, panels, armatures, etc. Furthermore, the invention is also applicable to household appliances, particularly for control panels and operating panels, covers, housings, etc.

[0070] Further embodiments of the invention are illustrated in the accompanying drawings and described below. Therefore, the illustrated embodiments should not be construed as limiting. Attached Figure Description

[0071] Figures 1a to 1c The back injection process of an embedded membrane with a tactile structure according to the prior art is illustrated;

[0072] Figure 2 A schematic representation of a method for producing injection-molded parts is shown;

[0073] Figures 3a to 3fA schematic representation of the steps of a method for producing injection-molded parts is shown in detail;

[0074] Figure 4 A schematic representation of the intermediate product is shown;

[0075] Figure 5 A schematic representation of an injection-molded part is shown;

[0076] Figures 6a to 6b A schematic representation of a pencil hardness test is shown. Detailed Implementation

[0077] The accompanying drawings illustrate various examples of embodiments of the invention. In each case, components with the same or similar functions have the same reference numerals. Where the embodiments shown in the drawings are similar, these similarities are not described more than once to avoid repetition. Corresponding differences between embodiments are described with respect to the drawings. It is self-evident that those skilled in the art can modify the various embodiments or combine the various features of these embodiments with each other within the scope of the claims.

[0078] Figures 1a to 1c A method for back-injecting a plastic compound into a membrane 100 is shown, thereby giving the membrane 100 a tactile structure, as known in the prior art. Figure 1a As shown, an embedded membrane 100 with a tactile structure is first provided. The embedded membrane 100 is then placed in an injection mold 110 of an injection molding machine, such that the tactile structure directly abuts against the wall of the cavity of the injection mold 110, as shown. Figure 1b The diagram is schematically shown. Then, a molten plastic compound is injected into the embedded film 100 and removed from the injection mold 110. The finished injection-molded part 120, according to the prior art, is... Figure 1c As shown in the figure. However, in the prior art, the tactile structure of the embedded film 100 deforms or compresses due to the high pressure and thermal shock during back injection in the injection molding machine. In other words, in the prior art process, the tactile structure loses height due to back injection molding. Therefore, in the prior art, an injection molded part 120 with a deformable tactile structure is provided.

[0079] Figure 2 A schematic representation of a method for producing an injection-molded part 50 is shown. Figure 2 The method shown involves performing the following steps:

[0080] a) Provide an embedded film or embedded sheet 10, wherein the embedded film or embedded sheet 10 includes a tactile layer 11;

[0081] b) Apply a buffer protective film, including an adhesive layer 21 and a buffer layer 22, to the tactile layer 11 of the embedded film or embedded sheet 10;

[0082] c) Embed the embedded film or embedded sheet 10 into the injection mold 60 of the injection molding machine, so that the buffer protective foil 20 contacts the wall of the injection mold 60.

[0083] d) Back injection molding of the embedded film or embedded sheet 10 with a plastic compound to provide an injection molded part 50;

[0084] e) Remove the injection molded part 50 from the injection mold 60.

[0085] Preferably, such as Figure 2 As shown, this method is used to provide an intermediate product 40, which substantially corresponds to the final injection-molded part 50 and also includes a cushioning protective foil 20. The cushioning protective foil 20 is then used as a protective layer for further processing steps or for transportation.

[0086] In an alternative embodiment, it is possible that the following steps are performed after step e):

[0087] f) Peel the cushioning protective foil 20 from the injection molded part 50.

[0088] After performing step f), an injection-molded part 50 comprising a substrate 30 and an embedded foil or embedded sheet is preferably obtained, wherein the tactile layer 11 is on the outer side.

[0089] Figures 3a to 3f Schematic details of a method for producing injection-molded part 50 are shown.

[0090] Figure 3a First, method step a) is shown, namely, providing an embedding membrane or embedding sheet 10, thereby... Figure 3a One embodiment is an embedded film 10. The embedded film 10 includes a tactile layer 11. In this case, the tactile layer 11 is a self-supporting layer and therefore the only layer of the embedded film 10. However, in an alternative embodiment, the embedded film or embedded sheet 10 may include a carrier film onto which the tactile layer 11 is applied. In this case, the carrier film ensures the stability of the embedded film or embedded sheet 10.

[0091] As in Figure 3aAs can be seen, the tactile layer 11 includes a tactile pattern with raised and recessed areas. The raised and recessed areas ensure the generation of a tactilely perceptible effect. Specifically, the raised areas are specified to have a height ranging from 10 μm to 100 μm, particularly from 20 μm to 50 μm, and preferably from 25 μm to 35 μm. Correspondingly, the recessed areas preferably have a depth ranging from 10 μm to 100 μm, particularly from 20 μm to 50 μm, and preferably from 25 μm to 35 μm. Such height and depth ensure that the raised and recessed areas are tactilely perceptible. It is also possible that the raised areas have a length and / or width ranging from 0.3 mm to 20 mm, preferably from 1 mm to 5 mm. Furthermore, the recessed areas may have a width ranging from 0.1 mm to 3 mm, preferably from 0.4 mm to 1 mm. Advantageously, the raised and recessed areas form a pattern.

[0092] It is possible that the tactile layer 11 may comprise a UV-curable varnish, preferably a polyurethane acrylate resin. Furthermore, the tactile layer 11 may be produced or applied by means of screen printing.

[0093] Specifically, the tactile layer 11 is specified to have a pencil hardness of F or better, preferably measured according to ASTM D3363. The pencil hardness test is described in detail with reference to Figure 6.

[0094] exist Figure 3b The diagram illustrates method step b), namely, applying the buffer protective foil 20 to the tactile layer 11 of the embedded film or embedded sheet 10. (As shown in...) Figure 3b As can be seen, the cushioning protective foil 20 includes an adhesive layer 21 and a cushioning layer 22. Preferably, the cushioning protective foil 20 is applied such that the adhesive layer 21 is positioned directly adjacent to the tactile layer 11. Preferably, the adhesive layer 21 ensures sufficient adhesion to the tactile layer 11, which is large enough to withstand the effects of injection molding and transportation, but small enough so that the cushioning protective foil 20 can be easily removed from the tactile layer 11. In particular, the cushioning protective foil 20, preferably the adhesive layer 21 of the cushioning protective foil 20, has an adhesion on the tactile layer 11 in the range of 0.01 N / 25 mm to 1 N / 25 mm, preferably from 0.1 N / 25 mm to 1 N / 25 mm, and more preferably from 0.5 N / 25 mm to 1 N / 25 mm.

[0095] Preferably, the adhesive layer 21 has a thickness in the range of 0.5 μm to 3 μm, more preferably from 1.2 μm to 1.8 μm, and more preferably from 1.5 μm to 1.8 μm.

[0096] It is possible that the adhesive layer 21 has a Shore A hardness of 50 or less, preferably measured using a Shore A hardness tester.

[0097] Specifically, the adhesive layer 21 comprises a pressure-sensitive adhesive having an acrylic component. Preferably, the adhesive layer 21 is applied to the buffer layer 22 by means of a slit mold.

[0098] Preferably, adhesive layer 21 is necessary because the application in step b) is advantageously carried out by means of a lamination process. It is possible that the lamination temperature in step b) is in the range of 30°C to 150°C, preferably from 50°C to 100°C, and more preferably from 60°C to 80°C. Furthermore, it is possible that the lamination speed in step b) is in the range of 1 m / min to 5 m / min, preferably from 1.5 m / min to 4 m / min, and more preferably from 2 m / min to 4 m / min. Moreover, the lamination pressure in step b) is in the range of 10 bar to 100 bar, preferably from 10 bar to 50 bar, and more preferably from 30 bar to 50 bar.

[0099] Furthermore, preferably, the thickness of the buffer layer 22 is specified to be in the range of 10 μm to 100 μm, more preferably from 30 μm to 80 μm, and even more preferably from 50 μm to 70 μm, particularly before back injection. Moreover, it is possible that the buffer layer 22 may have a glass transition temperature in the range of 80°C to 110°C, preferably from 85°C to 105°C.

[0100] Advantageously, the buffer layer 22 may comprise at least one material or a combination of materials selected from: polyvinyl chloride (=PVC), polyethylene (=PE), and / or polypropylene (=PP). Preferably, the buffer layer 22 has a Shore A hardness of 25 or less, preferably measured using a Shore A hardness tester.

[0101] The buffer layer 22, which is part of the buffer protective foil 20, serves as a damping layer during the back injection molding of the embedded film or embedded sheet 10, so that the tactile structure is not deformed at all or is deformed less than that of the prior art due to the pressure during injection molding.

[0102] After applying the buffer protective foil 20 to the embedded film or embedded sheet 10 in step b), the following steps (not shown in the figure) may also be performed:

[0103] b1) Deep draw or vacuum form the embedded foil or embedded sheet together with the applied buffer protective foil 20.

[0104] Preferably, step b1) is performed after step b) and before step c).

[0105] The deep drawing or vacuum forming of the insert film or insert sheet 10 in step b1) is preferably used for the initial preforming of the insert film or insert sheet 10, so that the subsequent back injection molding can directly follow the contour of the insert film or insert sheet 10. This ensures that the insert film or insert sheet no longer deforms in the injection mold 60, and thus provides a high-quality injection molded part 50.

[0106] Advantageously, the deep drawing or vacuum forming in step b1) is carried out at a deep drawing temperature or vacuum forming temperature in the range of 50°C to 300°C, preferably from 90°C to 200°C, and more preferably from 120°C to 150°C.

[0107] Preferably, the buffer protective foil 20 is designed to withstand the strong deformation that sometimes occurs during deep drawing or vacuum forming without wrinkling or cracking. In this case, it is preferably specified that the buffer protective foil 20 has an elongation in the range of 100% to 250%, preferably from 100% to 200%, and more preferably from 100% to 150%. This is preferably achieved by selecting the material of the buffer layer 22. As mentioned above, the preferred material for the buffer layer 22 is PVC, PE, or PP.

[0108] Next, as in Figure 3c As can be seen from the diagram, according to method step c), the embedding film or embedding sheet 10 is embedded into the injection mold 60 of the injection molding machine, so that the buffer protective foil 20 contacts the wall of the injection mold 60. For example, in... Figure 3c As can be seen, the insert film or insert sheet 10 is a flat, planar insert film or insert sheet 10. This means that the insert film or insert sheet 10 has not been deep-drawn or vacuum-formed. As described above, in advantageous embodiments, the insert film or insert sheet 10 may be pre-formed in any case, particularly by deep drawing or vacuum forming. In this case, the pre-formed insert film or insert sheet 10 is then inserted into the injection mold 60 of the injection molding machine.

[0109] Moreover, in Figure 3c The height x of the buffer protective foil 20 is shown in the figure. x represents the height of the buffer protective foil before back injection molding.

[0110] Later, as in Figure 3d As can be seen, according to step d), the embedded film or embedded sheet 10 is back-injected molded with a plastic compound. Preferably, the back-injection molding is performed at an injection temperature ranging from 100°C to 500°C, more preferably from 180°C to 400°C, and more preferably from 200°C to 300°C. Furthermore, the back-injection molding in step d) can have an injection pressure ranging from 800 bar to 1300 bar.

[0111] The plastic compound then forms the substrate 30 of the subsequently injection-molded part 50 and bonds to the side of the embedded film or insert sheet 10 facing away from the cushioning protective foil 20. During back injection molding, the cushioning protective foil 20 is elastically and plastically compressed due to the thermal effects and injection pressure during injection molding. This is caused by... Figure 3d The height y of the buffer protective foil 20 is indicated. (With) Figure 3c The height y of the buffer protective foil 20 is lower than the height x, either before back injection molding or due to compression of the buffer protective foil 20. The compression of the buffer protective foil 20 prevents deformation or compression of the tactile structure of the tactile layer 11 of the embedded film or sheet 10. However, small deformation or compression of the tactile structure may still occur. Preferably, the deformation relative to the height of the bulge is less than 10%, particularly less than 5%. However, this deformation is significantly smaller than deformations known in the prior art.

[0112] Figure 3e Method step e) is now shown, namely, removing the injection-molded part 50 from the injection mold 60. However, since the injection-molded part 50 still includes the cushioning protective foil 20, the injection-molded part 50 serves as an intermediate product 40. Regarding... Figure 4 Further details of the intermediate product 40 are described. This intermediate product 40 can be processed immediately or shipped to the customer first. The cushioning protective foil 20 is preferably retained on the injection-molded part 50. In this way, the cushioning protective foil 20 continues to act as a protective element against external environmental influences.

[0113] at last, Figure 3f The process step f) is shown, namely, peeling off the buffer protective foil 20. This yields or provides the final injection-molded part 50. Regarding... Figure 5 Further details of intermediate product 40 are described.

[0114] Figure 4 A schematic diagram of intermediate product 40 is shown, for example, as Figure 3e As shown. According to Figure 4 The intermediate product 40 includes a substrate 30 formed of a plastic compound, a tactile layer 11 fixedly attached to the substrate 30, and a releasable cushioning protective foil 20 adjacent to the tactile layer 11. According to... Figure 4 The buffer protective foil 20 includes an adhesive layer 21 and a buffer layer 22, wherein the buffer layer 22 represents the outer layer of the intermediate product 40.

[0115] Preferably, the buffer protective foil 20 has a thickness ranging from 10 μm to 100 μm, more preferably from 30 μm to 80 μm, and even more preferably from 50 μm to 70 μm.

[0116] Furthermore, the cushioning foil 20 may have an adhesive strength on the tactile layer 11 ranging from 0.01 N / 25 mm to 1 N / 25 mm, preferably from 0.1 N / 25 mm to 1 N / 25 mm, and more preferably from 0.5 N / 25 mm to 1 N / 25 mm. This adhesive strength ensures that the cushioning foil 20 has sufficient adhesion so that it does not loosen during transport or further processing, but is still easy enough to remove from the tactile layer 11.

[0117] Figure 5 It has been shown, for example, that it has already been shown. Figure 3f A schematic diagram of the injection-molded part 50 is shown. According to... Figure 5 The injection-molded component 50 includes a substrate 30 composed of a plastic compound and a tactile layer 11 fixedly connected to the substrate 30. Preferably, the tactile layer 11 is part of an insert film or insert sheet 10. In alternative embodiments, the injection-molded component 50 may include a substrate 30 composed of a plastic compound and an insert film or insert sheet 10, wherein the insert film or insert sheet 10 is fixedly connected to the substrate 30, and wherein the insert film or insert sheet 10 includes the tactile layer 11. In each embodiment of the injection-molded component 50, the tactile layer 11 is preferably defined as representing the outer layer of the injection-molded component 50. This ensures that the tactile structure of the tactile layer 11 can also be perceived by touch.

[0118] Preferably, the tactile layer 11 includes a tactile pattern with raised and recessed areas. The raised areas may have a height ranging from 10 μm to 100 μm, particularly from 20 μm to 50 μm, and preferably from 25 μm to 35 μm. Furthermore, it is preferably specified that the raised areas have a length and / or width ranging from 0.3 mm to 20 mm, and preferably from 1 mm to 5 mm. Moreover, the recessed areas may have a width ranging from 0.1 mm to 3 mm, and preferably from 0.4 mm to 1 mm.

[0119] Preferably, the tactile layer 11 comprises a UV-curable varnish, and preferably has a polyurethane acrylate resin.

[0120] Preferably, the tactile layer 11 is specified to have a pencil hardness of F or better, preferably measured according to ASTM D3363.

[0121] Pencil hardness test Figure 6a and Figure 6bThe diagram is schematically shown. Pencil hardness was determined using an electric pencil hardness tester, model A-3086*1, from Tianjin Jin Fu Lun Technology Corporation. The tests were conducted at a temperature of 23℃±2℃ and a relative humidity of 50%±5%. Various hardness grades of Mitsubishi Pencil Company Limited pencils, such as F and 6B, were used, model name "Uni". For the test, a cylindrical pencil lead containing graphite was extended 5 to 6 cm beyond the pencil 300. The pencil was then ground on sandpaper 310 at a 90° angle until the pencil tip was flat. Figure 6a As shown.

[0122] Then, the pencil 300 is positioned at a 45° angle and pushed forward 5-6 cm along the surface of the tactile layer 11 of the injection-molded part 50, as in... Figure 6b As can be seen schematically, the contact load applied to the surface of the tactile layer 11 corresponds to an equivalent of 500 grams.

[0123] To determine the pencil hardness of the tactile layer 11, different pencil hardnesses are tested one after another. The surface of the tactile layer 11 is checked for scratches. If no scratches are found, the tactile layer 11 has passed the test for the corresponding pencil hardness. Testing is conducted with increasingly harder pencil hardnesses until a scratch appears on the surface of the tactile layer 11. The test immediately preceding this scratch-inducing test then determines the pencil hardness of the tactile layer 11. For example, if the pencil hardness of the tactile layer 11 is specified as 4H, a test with a 4H pencil 300 will not cause any scratches on the surface, but a test with a 5H pencil 300 will cause scratches.

[0124] List of reference numerals

[0125] 10. Embedded film or embedded sheet

[0126] 11. Tactile layer

[0127] 20 Buffer Protective Foil

[0128] 21 Adhesive layer

[0129] 22 Buffer layer

[0130] 30 matrix

[0131] 40 Intermediate products

[0132] 50 Injection Molded Parts

[0133] 60 Injection mold

[0134] 100 Embedded films according to the prior art

[0135] 110 Injection molds according to the prior art

[0136] 120. Based on the existing technology

[0137] 200 Injection-molded parts according to the prior art

[0138] 300 pencils

[0139] 310 sandpaper

[0140] x Height of the buffer protective foil prior to injection molding

[0141] y is the height of the buffer protective foil after injection molding.

Claims

1. A method for producing injection-molded parts (50), wherein, Perform the following steps in the following order: a) Provide an embedded film or embedded sheet, wherein the embedded film or embedded sheet (10) includes a tactile layer (11). b) Apply a cushioning protective foil, including an adhesive layer (21) and a cushioning layer (22), to the tactile layer (11) of the embedded film or embedded sheet (10); c) The embedded film or embedded sheet (10) is embedded into the injection mold (60) of the injection molding machine, such that the buffer protective foil (20) contacts the wall of the injection mold (60); d) Back injection molding of the embedded film or embedded sheet (10) with a plastic compound to provide an injection molded part (50). e) Remove the injection molded part (50) from the injection mold (60).

2. The method according to claim 1, Its features After step e), perform the following steps: f) Peel off the buffer protective foil (20) from the injection molded part (50).

3. The method according to claim 1 or 2, Its features The embedded film or embedded sheet (10) includes a carrier film, and the tactile layer (11) is applied to the carrier film.

4. The method according to claim 1 or 2, Its features The tactile layer (11) includes a tactile pattern with raised and recessed areas.

5. The method according to claim 4, Its features The bulge has a height ranging from 10 μm to 100 μm.

6. The method according to claim 4, Its features The bulge has a length and / or width ranging from 0.3 mm to 20 mm.

7. The method according to claim 4, Its features The recess has a width ranging from 0.1 mm to 3 mm.

8. The method according to claim 1 or 2, Its features The tactile layer (11) has a pencil hardness of F or better as measured according to ASTM D3363.

9. The method according to claim 1 or 2, Its features The tactile layer (11) comprises a UV-curable varnish.

10. The method according to claim 1 or 2, Its features The buffer protective foil (20) has a thickness in the range of 10 μm to 100 μm.

11. The method according to claim 1 or 2, Its features The adhesive layer (21) of the buffer protective foil (20) has an adhesive force on the tactile layer (11) in the range of 0.01 N / 25 mm to 1 N / 25 mm.

12. The method according to claim 1 or 2, Its features The buffer protective foil (20) has a strength of 0.5 N / mm. 2 Up to 25 N / mm 2 The tensile strength within the range.

13. The method according to claim 1 or 2, Its features The buffer protective foil (20) has an elongation in the range of 100% to 250%.

14. The method according to claim 1 or 2, Its features The adhesive layer (21) has a thickness ranging from 0.5 μm to 3 μm.

15. The method according to claim 1 or 2, Its features The adhesive layer (21) has a Shore A hardness of 50 or less, as measured by using a Shore A hardness tester.

16. The method according to claim 1 or 2, Its features The adhesive layer (21) comprises a pressure-sensitive adhesive having an acrylic component.

17. The method according to claim 1 or 2, Its features The buffer layer (22) has a thickness ranging from 10 μm to 100 μm.

18. The method according to claim 1 or 2, Its features The buffer layer (22) has a glass transition temperature in the range of 80°C to 110°C.

19. The method according to claim 1 or 2, Its features The buffer layer (22) comprises at least one material or a combination of materials selected from the following: polyvinyl chloride (=PVC), polyethylene (=PE) and / or polypropylene (=PP).

20. The method according to claim 1 or 2, Its features The buffer layer (22) has a Shore A25 or less hardness as measured by using a Shore A hardness tester.

21. The method according to claim 1 or 2, Its features The application in step b) is performed by means of the lamination process.

22. The method according to claim 21, Its features The lamination temperature in step b) is in the range of 30°C to 150°C.

23. The method according to claim 21, Its features The lamination rate in step b) is in the range of 1 m / min to 5 m / min.

24. The method according to claim 21, Its features The lamination pressure in step b) of the lamination process is in the range of 10 bar to 100 bar.

25. The method according to claim 1 or 2, Its features Following step b), the following steps are performed: b1) Deep draw or vacuum form the embedded film or embedded sheet together with the applied buffer protective foil (20).

26. The method according to claim 25, Its features The deep drawing or vacuum forming in step b1) is performed at a deep drawing temperature or vacuum forming temperature ranging from 50°C to 300°C.

27. The method according to claim 1 or 2, Its features The back injection molding in step d) has an injection temperature in the range of 100°C to 500°C.

28. The method according to claim 1 or 2, Its features The back injection molding in step d) has an injection pressure in the range of 800 bar to 1300 bar.

29. The method according to claim 4, Its features During and / or after step d), the deformation of the bulge of the tactile layer is less than 10% relative to the height of the bulge.

30. An injection-molded part (50) produced by the method according to any one of claims 1 to 29. in, The injection-molded component (50) includes a substrate (30) composed of a plastic compound and a tactile layer (11) fixedly attached to the substrate (30).

31. The injection-molded component (50) according to claim 30. Its features The tactile layer (11) includes a tactile pattern with raised and recessed areas.

32. The injection-molded component (50) according to claim 31. Its features The bulge has a height ranging from 10 μm to 100 μm.

33. The injection-molded component (50) according to claim 31. Its features The bulge has a length and / or width ranging from 0.3 mm to 20 mm.

34. The injection-molded component (50) according to claim 31. Its features The recess has a width ranging from 0.1 mm to 3 mm.

35. The injection-molded part (50) according to claim 30 or 31. Its features The tactile layer (11) has a pencil hardness of F or better as measured according to ASTM D3363.

36. The injection-molded part (50) according to claim 30 or 31. Its features The tactile layer (11) comprises a UV-curable varnish.

37. An intermediate product (40) comprising an injection-molded part (50) according to claim 30 or 31 produced by the method according to any one of claims 1 to 29. Its features The intermediate product (40) also includes a releasable cushioning protective foil (20) adjacent to the tactile layer (11), wherein the cushioning protective foil (20) includes an adhesive layer (21) and a cushioning layer (22).

38. The intermediate product (40) according to claim 37. Its features The buffer protective foil (20) has a thickness in the range of 10 μm to 100 μm.

39. The intermediate product (40) according to claim 37 or 38. Its features The buffer protective foil (20) has an adhesive force on the tactile layer (11) in the range of 0.01 N / 25 mm to 1 N / 25 mm.

40. The intermediate product (40) according to claim 37 or 38. Its features The adhesive layer (21) has a thickness ranging from 0.5 μm to 3 μm.

41. The intermediate product (40) according to claim 37 or 38. Its features The adhesive layer (21) has a Shore A hardness of 50 or less, as measured by using a Shore A hardness tester.

42. The intermediate product (40) according to claim 37 or 38. Its features The adhesive layer (21) comprises a pressure-sensitive adhesive having an acrylic component.

43. The intermediate product (40) according to claim 37 or 38. Its features The buffer layer (22) has a thickness ranging from 10 μm to 100 μm.

44. The intermediate product (40) according to claim 37 or 38. Its features The buffer layer (22) comprises at least one material or a combination of materials selected from the following: polyvinyl chloride (=PVC), polyethylene (=PE) and / or polypropylene (=PP).

45. The intermediate product (40) according to claim 37 or 38. Its features The buffer layer (22) has a Shore A25 or less hardness as measured by using a Shore A hardness tester.

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