Method for producing a foamed plastic molded body having a film layer coating

Abstract

The present invention relates to a method for manufacturing a foamed plastic molded body with a film layer coating by forming a molding mold cavity using a tool mold having at least one tool cavity, the method comprising the following method steps: -A) heating at least one tool cavity of the tool mold; -B) applying granules to the at least one heated tool cavity; -C) fusing the granules in the heated tool cavity to form a liquid film layer; -D) applying the liquid film layer to the foamed plastic molded body to form a film layer coating on the surface of the plastic molded body by fusing the liquid film layer with the surface of the plastic molded body; -E) cooling the at least one tool cavity and ejecting the plastic molded body coated with the film layer.

Description

[Technical field]

[0001] The invention relates to a method for producing a foamed plastic molded body having a film layer coating by forming a mold cavity using a tool mold having at least one tool cavity. [Background technology]

[0002] A manufacturing method and a one-part or multi-part tool mold for manufacturing a foamed plastic molded body are known from the prior art. In the known method, in a one-part or multi-part tool mold comprising at least one tool cavity, a mold cavity is filled with expandable particles and / or foam beads to form a molded mold cavity, and pressurized steam with a temperature and humidity that causes the particles and / or foam beads to expand and weld together in the mold cavity (the method is also called a steam chamber method) flows through the mold cavity. It is also known from the prior art that the molded mold cavity is heated via two opposing tool halves and the interior of the mold cavity, and then expandable particles and / or foam beads are filled into the mold cavity, which absorb heat energy through the heated mold cavity, expand in the mold cavity and fuse with each other, while forming a foamed plastic molded body. The mold cavity defined by at least one tool cavity of the tool mold is of decisive significance for the geometry of the foamed plastic molded body to be manufactured. After cooling, the plastic molded body manufactured in the tool mold can be ejected or demoulded from the tool mold by opening the tool mold.

[0003] Such an apparatus and a method for producing a foamed plastic molding are known, for example, from DE 10 2009 006 507 B3.

[0004] The foamed plastic molded bodies previously known from the prior art do not have a closed or continuous surface after the above-mentioned production process. Instead, the expansion process leaves microcavities on the surface of the foamed plastic molded body, into which, for example, liquids can enter. It is also disadvantageous that, due to the above-mentioned cavities, the plastic molded body does not have a closed planar structure and is therefore not directly suitable for painting the molded body, for example, for use in automotive engineering.

[0005] Furthermore, previously known foamed plastic moldings have only the color of the expanded plastic particles or foamed plastic particles, respectively, as starting material. For certain areas of application, such as in the food industry, but also in the automotive industry, it is required to produce foamed plastic moldings with a low-roughness closed surface in order to be able to paint the moldings directly and use them, for example, as bumpers in motor vehicles.

[0006] It is also known from the prior art to obtain closed surfaces of textile molded bodies by coating the above-mentioned foamed plastic molded bodies with additional film layers, wherein a disadvantage in previous production methods is that the above-mentioned plastic film must be applied to the foamed plastic molded body in a separate working step. [Summary of the invention]

[0007] Based on the above-mentioned prior art, the object of the present invention is to propose a simplified manufacturing method for producing a foamed plastic molded body with a film layer coating, which method is more cost-effective, can be carried out with reduced manufacturing time, and in addition, the properties of the plastic molded body can be specifically adjusted according to the intended application purpose.

[0008] According to the present invention, the object of the present invention is achieved by a manufacturing method, which uses a tool mold with at least one tool cavity to form a molding mold cavity to manufacture a foamed plastic molded body with a film layer coating, and the method comprises the following method steps:

[0009] -A) heating at least one tool cavity of a tool mold;

[0010] -B) applying pellets to at least one heated tool cavity;

[0011] -C) fusing the pellets in the heated tool cavity to form a liquid film layer;

[0012] -D) applying the liquid film layer to the foamed plastic molding to form a film layer coating on the surface of the plastic molding by fusing the liquid film layer with the surface of the plastic molding;

[0013] -E) Cooling the tool cavity and ejecting the plastic molded body (1) coated with the film layer.

[0014] In method step E), the tool mold, in particular at least one heated tool cavity in the tool mold, is cooled to the demolding temperature, and the plastic molded body with the film layer coating is ejected or demolded from the tool mold and released from the tool as a component. The granules applied in method step B) are the required material, and the film layer coating to be formed with this material is used to form the foamed plastic molded body. In method step A), at least one tool cavity is heated at least to the melting temperature of the granules applied in method step B) to form a liquid film layer in method step C), which is formed by the melted granules. When carrying out the method, the temperature of at least one tool cavity can be guided or controlled respectively so that the temperature is basically at least higher than the melting temperature of the applied granules during the entire period of at least method steps B) to D).

[0015] The method according to the invention has the advantage that a closed film layer coating can be produced on a plastic molded body by using existing tools, in particular multi-part tool molds. At the same time, additional devices previously required according to the prior art for achieving a coating on a plastic molded body, in particular for applying a plastic film layer or a textile layer with a plastic layer, are obsolete. It is particularly advantageous in the method according to the invention that the method can be smoothly integrated into the production process of an existing manufacturing method or can be directly connected thereto, which respectively leads to a significant saving of time and an increase in efficiency. By fusing the granules in method step C), a continuous film layer of the granules with a defined film layer thickness is formed in the heated tool cavity, wherein after completion of method step C), the continuous film layer is in a fused or liquid state in the heated tool cavity. In method step D), the fused film layer is applied in a liquid state at least proportionally to the surface of the foamed plastic molded body in order to form a closed film layer coating on the surface of the plastic molded body and is directly fused or solidified on the previous surface of the plastic molded body, respectively. The film layer can cover the entire surface of the foamed plastic molding or, alternatively, only a partial surface sub-region of the plastic molding as a closed film layer. The method according to the invention also has the advantage that no burrs occur on the manufactured plastic molding, which is why no reworking of the manufactured finished part (e.g. removal of gates or protruding burrs) is required.

[0016] According to the invention, provision can be made that, before carrying out method steps A) to E), the actual plastic molded body is initially produced in a tool mold by a foaming or expansion method known from the prior art, the tool mold is then opened, wherein the foamed plastic molded body remains in at least one tool cavity, and method steps A) to E) are then carried out for at least one second, opposite tool cavity, wherein the film layer is applied according to method step D) by closing the tool mold again around the already expanded plastic molded body, and in method step E) the cooling of the at least one tool cavity is carried out in the closed molded state. The above-described embodiment of the manufacturing method according to the invention has the advantage that the film layer coating is produced directly after the methods known from the prior art for producing foamed plastic molded bodies using known expansion methods, and that, according to the invention, the film layer can be applied by using an existing tool mold. Due to the production and application of the film layer directly after the production of the plastic molded body, good bonding or adhesion of the film layer to the plastic molded body can be achieved, since intermediate contamination of the bonding surfaces of the plastic molded body is avoided.

[0017] The plastic molded body can be produced by an expansion method by using all expandable particle foams such as EPS (expandable polystyrene), EPP (expandable polypropylene), EPE (expandable polyethylene), expandable thermoplastic polyurethane (E-TPU) and polystyrene containing graphite or carbon in the cavity of the tool mold. In an alternative embodiment of the production method, it can also be provided that the plastic molded body is produced by an expansion method in a first tool mold and then the method steps according to the invention are carried out in a second tool mold.

[0018] In a further preferred embodiment of the manufacturing method according to the present invention, it can be provided that the first method steps A) to C) are carried out in the area of ​​at least one tool cavity, and then the tool mold is closed and the mold cavity of the tool mold is filled with first expandable plastic pellets or foam beads, respectively, and the first expandable plastic pellets or foam beads are then expanded in the mold cavity, wherein method step D) is carried out based on the fact that the plastic molded body expands against the liquid film layer formed on at least one tool cavity and directly fuses with it.

[0019] Particularly preferably, provision can be made for the expansion process of the first expandable plastic pellets to be cancelled prematurely or to be stopped prematurely after a defined period of time, which is why only a portion of the plastic pellets or foam beads, respectively, expands. The portion of the first plastic pellets that has not yet melted or expanded is then removed from the mold cavity, so that only one layer of the first expanded plastic pellets adheres to the film layer. The intermediate product obtained can remain in the mold cavity or be demoulded from the mold cavity for further processing steps.

[0020] Preferably, when the intermediate product remains in the mold cavity, after removing the non-expanded part of the first plastic particles, the mold cavity can be filled with a second expandable plastic pellet or with foam beads, respectively, and then expanded to form a plastic molded body. The method can be used to produce a plastic molded body with a film layer, wherein below the film layer is a first expandable plastic pellet or foam bead layer of a first material fused or bonded to the film layer, respectively, and below the layer is a second expandable plastic pellet or plastic bead of a second layer, respectively, the second expandable plastic pellet or plastic bead is formed of a second material and connected or bonded to at least the first layer. The method enables the production of a plastic molded body consisting of two different foamed pellets.

[0021] Preferably, at least two different expandable plastic pellets with different material properties are used in the manufacturing process. In a first exemplary embodiment, the first expandable plastic pellet can be selected so that a local foam with low density is produced, while having high elasticity, while the second pellet produces a local foam with higher density and lower elasticity compared to the first expandable plastic pellet. Thus, a resulting foamed plastic molded body can be obtained, which has a soft and tough surface below the film layer coating in the surface area, wherein the lower local foam area is structurally stable and does not deform.

[0022] In an alternative embodiment, the first expandable plastic pellets can have a higher hardness and a higher density than the second expandable plastic pellets, so that an article with a very hard surface and at the same time reduced weight can be obtained. The advantage of providing a first foam layer formed of expandable plastic pellets with high hardness and high density is that a film layer coating with a low film thickness can be achieved.

[0023] By specifically selecting the first and second expandable plastic pellets, the resulting local characteristics of the foam layer forming the plastic molded body can be specifically influenced. In addition, it can be provided that, by repeating the method, two or more different expandable plastic pellets are used to form the plastic molded body. Therefore, in a preferred embodiment, it can be provided that after removing the non-expanded part of the first plastic pellet, when the intermediate product is left in the mold cavity, the mold cavity is filled with at least two additional expandable plastic pellets or plastic beads, respectively, and then expanded to form the plastic molded body. In doing so, the expansion process of the additional expandable plastic pellets is canceled in advance or stopped in advance after a defined time period, which is why only part of the additional plastic particles or plastic beads are expanded respectively. Then, the part of the additional plastic pellets that has not yet melted or expanded can be removed from the mold cavity, so that a layer of additional expanded plastic pellets with a defined thickness can be produced. The method enables the production of a plastic molded body having a film layer, wherein underneath the film layer is respectively a layer of a first expanded plastic granulate or plastic beads of a first material, which is fused to or bonded to the film layer, and underneath the layer is respectively an arbitrary number of further layers of further expanded plastic granulates or plastic beads of a further material, which layers are respectively connected to or bonded to at least the first layer. The method enables the production of a plastic molded body having a film layer and an arbitrary number of underlying layers of expanded plastic granules. Thus, in particular, so-called multilayer molded bodies having 3 to 6 layers can be produced.

[0024] It can also be provided that in method step B), granules are applied to the surface of the multi-part tool mold outside the region of at least one tool cavity, and at least one part of the multi-part tool mold comprises a sealing ring, which, when the tool mold is closed, throws the granules outside the region of at least one tool cavity and forms a rim in the edge region of at least one first and / or second tool cavity. The sealing ring is arranged in the first part of the tool mold and, when the tool mold is closed, expands in the surrounding region of the opposing tool cavity of at least one second part of the tool mold. During the above expansion process, the granules applied outside the tool cavity are pushed together in the fused state by the movement of the sealing ring relative to the opposing tool cavity and form a rim that limits the opposing tool cavity. Thus, when the film coating is applied, a visible edge of the end of the film coating is avoided only on a part of the surface of the plastic molded body. In addition, the circumferential edge of the film coating is better bonded to the foam body by the rim, so that the edge region of the film coating can be prevented from falling off. It is particularly preferred that the tool mold opposite to the sealing ring is designed to be conical, so that the sealing ring can be better inserted into the opposing tool mold.

[0025] Preferably, according to the invention, provision can also be made that, in method step B), granules for the film coating are applied to at least one tool cavity by means of a spray gun.

[0026] According to a further preferred embodiment of the manufacturing process according to the invention, it can be provided that in method step A), a heating medium is introduced via a corresponding heating channel in at least one tool cavity to heat the at least one tool cavity to be heated. For example, heated oil, water or a steam mixture can be supplied as the heating medium.

[0027] Alternatively, at least one tool cavity may be heated by at least one active heating device, such as an electrical heating element (such as a resistive heating element, a resistor element or an inductive heating element).

[0028] Preferably, it can also be provided that at least one tool chamber is heated directly by an external heat source, such as a heated gas flow.

[0029] According to a further embodiment, at least one tool cavity can be heated by a radiant heater, such as an infrared radiator, or alternatively by at least one heating burner.

[0030] It can also be provided that in method step A), the at least one tool chamber to be heated is heated at least to a temperature above the melting temperature of the applied granular material, in particular to a temperature in the range of 80° C. to 260° C.

[0031] According to a preferred embodiment, provision can be made that in method step B), powdered thermoplastic granules are applied to at least one tool cavity. The thermoplastic granules can be fused by heating the tool cavity, so that the tool cavity comprises a continuous fused layer of thermoplastic.

[0032] The granular material can also be mixed with an additive and applied to at least one tool cavity. In particular, glass fibers and / or carbon fibers can be used as granular additives.

[0033] According to the invention, it can be provided that during or after method step C), at least in a partial region of the surface of at least one tool cavity, a layer of nonwoven fabric or textile (e.g. woven or knitted fabric) is placed and preferably embedded in or soaked with the liquid film layer. It is particularly preferred that the placed layer can include a defined outer contour and dimensions.

[0034] Particularly preferably, thermoplastic granules with a defined RAL color can be applied to at least one tool cavity, so that the film coating can be produced in the desired defined RAL color. In addition, plastic granules with special properties such as dissipative properties, flame retardancy, suitability for food, resistance to UV radiation, heat resistance, increased water resistance, increased dielectric strength and increased wear resistance can be used. In addition, plastics can be used as film coatings, which form a substance-to-substance bond with the plastic molded body. This enables the plastic molded body to be further specifically designed with the desired properties.

[0035] According to the invention, it can also be provided that the plastic molded body and the film coating have the same thermoplastic to achieve a composite material of a single material, for example a combination of the plastics PP and EPP or PS and EPS can be used. Due to the use of a composite material of a single material, the manufactured plastic molded body with the film coating can be better recycled due to the consistent material.

[0036] Furthermore, according to the invention, at least one tool cavity with a defined surface texture can be used, which will result in defined surface characteristics of the film layer. For example, the surface of the film layer coating can be provided with a defined texture, an extremely smooth or defined roughness surface or a hook-and-loop surface.

[0037] According to a particularly preferred embodiment of the production method according to the invention, provision can be made that in method step B), powdered polypropylene (PP) is applied to at least one tool cavity.

[0038] According to a further particularly preferred embodiment, it can be provided that in method step B), the granules are applied only in proportion to a defined sub-region of at least one tool cavity in order to form at least one film layer in certain areas, wherein in particular a sub-region of at least one tool cavity can be covered to prevent the application of granules in method step B).

[0039] Preferably, provision can also be made for the granules to be applied with defined different layer thicknesses in different sub-regions of the tool cavity, so that a film coating with locally different film thicknesses can be produced on the foamed plastic molded body. The above-described method makes it possible for the first time to specifically realize surface regions with different strengths and bending stiffnesses in the film coating. In particular, it makes it possible to introduce weakened regions in the surface, which, for example, when the plastic molded body is used in the automotive sector, can lead to a defined deformation behavior, for example in the event of an impact.

[0040] In particular, it can be provided that in method step B), the granules are applied to the tool cavity with a layer thickness in the range of 0.05 mm to 2 mm. The layer thickness of the granules can be selected depending on the underlying expanded plastic granules.

[0041] According to a further preferred embodiment, provision can be made in method step E) for the at least one tool chamber to be cooled to be cooled convectively and / or conductively.

[0042] According to a particularly preferred embodiment, it can be provided that in method step E), at least one tool cavity to be cooled is cooled by guiding a cooling medium through a channel of at least one tool cavity. For example, the supplied cooling medium can be a cooling fluid, in particular oil, cooling air or cooling water.

[0043] Alternatively, it can be provided that in method step E), at least one tool cavity to be cooled is cooled by spraying a cooling medium onto at least one tool cavity to be cooled with the aid of at least one nozzle device. In particular, it can be provided that liquid water is sprayed onto at least one tool cavity to be cooled with the aid of multiple nozzle devices, especially atomizing nozzles.

[0044] According to the invention, it can further be provided that the temperature of at least one tool chamber to be heated in method step A) is monitored by means of a temperature sensor. Preferably, the required process temperature can also be monitored during the entire production method or in defined method steps by means of a temperature sensor and specific control can be carried out based on the measured value.

[0045] It can also be provided that the supply of the heating medium or alternatively the electric nozzle arrangement can be controlled by means of a temperature sensor.

[0046] In particular, it can be provided that, in order to produce the foamed plastic molded body after carrying out method steps A) to C), at least one granular foam pellet is supplied to the closed mold by means of at least one injector device. The mold can also be partially filled with different expandable plastic pellets by means of several injector devices.

[0047] Furthermore, it can be provided according to the invention that method steps A) to C) are carried out on at least one external tool cavity which forms the mold cavity together with the tool mold by displacement in method steps D) and E). For example, according to the invention, a rotating disk tool with a plurality of tool cavities can be used.

[0048] Hereinafter, some embodiments of the manufacturing method according to the present invention will be described.

[0049] Embodiment 1, 2 and 3:

[0050] The panels were produced according to the steam chamber method based on EPP-expanded polypropylene foam particles (trademarks Eperan-PPVB45, M30 and VB15 of Kaneka Belgium NV) using square tools with dimensions of 370×370×60 mm. The panels were stabilized in an oven at 80° C. for 24 hours and stored under ambient conditions (23° C.-50% relative humidity). A circular hot plate was electrically heated to a temperature of 220° C., and the pellets (polypropylene "Gray EX1Y 1876", produced by Axalta Coating Systems Ltd.) were sprayed onto the heated plate and fused therewith. The EPP panel was pressed onto the molten pellet layer, the panel was air-cooled, and as a result a film-coated foamed plastic part was obtained.

[0051] Embodiment 4 and 5:

[0052] The cavity of the tool for producing the bowl (Example 4) and the cavity of the tool for producing the A-pillar trim for vehicles (Example 5) were heated to 185° C. or 180° C. respectively by using thermostat technology. Thermostat technology is a heating and cooling system that can precisely control the temperature in all areas of the tool. The tool cavity does not necessarily have to be integrated into the steam chamber of the molding machine. The granules (polypropylene "black EX1Y 1886" or "EX1Y 1886blue 565", produced by Axalta Coating Systems Ltd.) are sprayed on the heated cavity and fused with it. The tool is closed and the cavity is filled with EPP-expanded polypropylene foam granules (trademarks "Eperan-PP MN20" and "Eperan-PP VB 20" of Kaneka Belgium NV) and the steam chamber method is used. In both cases, a foamed plastic part can be produced, which is 100% covered with a film layer in the partially required area.

[0053] Examples 6, 7, 8, 9, 10 and 11:

[0054] The tools used to produce bowls (Examples 6, 7) and vehicle A-pillar trims (Examples 8, 9, 10, 11) were used to produce foamed plastic parts according to the steam chamber method based on EPP-expanded polypropylene foam particles (trademark Eperan-PPVB30, VB20, M30 and MN20 from Kaneka Belgium NV). However, at the end of the cycle, the parts were not ejected but remained in the cavity. Another cavity was heated to 180 to 185° C. using thermostat technology. The pellets (polypropylene "black EX1Y 1886" and "EX1Y 1886blue 565", produced by Axalta Coating Systems Ltd.) were sprayed on the heated cavity surface and fused to it. The tool was closed again and cooled. In both cases, foamed plastic parts can be produced, which are 100% covered with a film layer in the partially desired area.

[0055] Examples 12 and 13:

[0056] The A-pillar trim for the vehicle is manufactured according to the steam chamber method based on EPP-expanded polypropylene foam particles (trademark Eperan-PPVB20 and M30 from Kaneka Belgium NV). The A-pillar trim is stabilized in an oven at 80°C for 24 hours and stored under ambient conditions (23°C-50% relative humidity). The cavity of the A-pillar trim is heated to 180°C using thermostat technology, and the granules (polypropylene "Black EX1Y 1886", produced by Axalta Coating Systems Ltd.) are sprayed on the heated cavity and fused with it. The foamed A-pillar trim is pressed onto the molten granule layer, the plate is cooled, and a foamed plastic part with a film coating can be produced. This method has proven to be very practical for small batches.

[0057] Embodiment 14:

[0058] The cavity of the A-pillar trim is heated to 180°C using thermostat technology, and granules (polypropylene "Black EX1Y1886", produced by Axalta Coating Systems Ltd.) are sprayed on the heated cavity and fused with it. The tool with the hot cavity is closed, and X-type expanded polypropylene foam particles (Eperan-PP M30, a trademark of Kaneka Belgium NV) are filled into the tool, which then partially adhere to the molten film layer and form a first low-density (soft) layer. Non-adhesive, excess foam particles are sucked out of the cavity. Y-type foam particles (Eperan-PP VB20, a trademark of Kaneka Belgium NV) are filled into the tool and the steam chamber method is applied. It is possible to produce a foamed plastic part that is covered with 100% of the film layer in some desired areas. In addition, by using X-type and Y-type, two layers of different densities (soft and hard) can be achieved.

[0059] Embodiment 15:

[0060] The cavity of the A-pillar trim is heated to 180°C using thermostat technology, and granules (polypropylene "Black EX1Y1886", produced by Axalta Coating Systems Ltd.) are sprayed onto the heated cavity and fused with it. The tool with the hot cavity is closed, X-type expanded polypropylene foam particles (Eperan-PP M30, a trademark of Kaneka Belgium NV) are filled into the tool, which are then partially adhered to the molten film layer to form a first low-density (soft) layer. The cavity is cooled. The non-adhesive, over-expanded polypropylene foam particles are sucked out of the cavity, and the layer formed by the film layer and the adhered X-type foam particles is removed from the tool and stored. At a later stage, the film layer with the fused layer of foam particles is put back into the tool. Y-type expanded polypropylene foam particles (Eperan-PP VB20, a trademark of Kaneka Belgium NV) are blown into the tool and the steam chamber method is applied. A foamed plastic part can be produced, which is 100% covered with a film layer in some required areas. Furthermore, by using X-type and Y-type, two layers of different densities (soft and hard) can be achieved.

[0061]

[0062]

[0063]

[0064]

[0065]

[0066] Evaluation Methodology

[0067] Density of foam parts:

[0068] The density MD (g / liter, g / l) of the molded part of the foamed plastic part listed in Table 3 is calculated by dividing the weight W1 (g) of the foamed plastic part by the volume V1 (l) of the foamed plastic part:

[0069] MD=W1 / V1(g / l)

[0070] Water Permeability

[0071] A 1% water-based soap solution was prepared by adding 25 grams of dishwashing detergent (trademark "Dreft-Original" of Procter & Gamble) to 2500 ml of water at a temperature of 25°C.

[0072] The total volume of the foam part in the form of a cylindrical bowl is 1600 ml. The inner surface of the bowl is coated with a film layer. Its opening diameter D is 190 mm, and the thickness of the bottom and the wall is 10 mm. The bowl is stored under ambient conditions (23°C-50% relative humidity), and the weight W2 (g) of the bowl is measured.

[0073] A volume of 800 ml or 800.000 mm3 (equivalent to 50% of the total volume of the bowl) of soap dispersion is poured into the bowl. The height of the water column in the bowl is 28.32 mm = 800,000 / ((π*1902) / 4). The bowl is stored under ambient conditions (23°C-50% relative humidity) for 24 hours.

[0074] Then, remove the remaining soap solution from the bowl, wipe the inner surface of the bowl dry with a paper towel, and measure the "wet weight" W3 (g) of the bowl within 5 minutes after removing the soap dispersion.

[0075] The water permeability WP is expressed as the percentage of the increase in the weight of the bowl: WP (%) = (W3-W2) / W2*100

[0076] hardness

[0077] The hardness of foamed plastic parts is measured according to ASTM D2240. The results are expressed as "Shore A" values.

[0078] Color uniformity

[0079] The color of the foamed plastic parts with or without film coating was measured using an apparatus from BYK Gardner, the color sphere system of which is based on the CIElab color system.

[0080] The results of color measurements are expressed as a set of L, a*, and b* values.

[0081] L values ​​range from 0 to 100, from white to black.

[0082] The a* values ​​range from -127 to +127, from green to red.

[0083] The b* values ​​range from -127 to +127, from blue to yellow.

[0084] Color measurement and 20,000mm 2 The average L-, a*, and b* values ​​were calculated from five different points on the surface of the

[0085] The color difference between 2 measurements is expressed as ΔE and is calculated as follows:

[0086]

[0087] Measure ΔE for each individual color i is calculated for the average L, a*, and b* values, with i ranging from 1 to 5. Finally, the total ΔE of the change is calculated as five ΔE i The average of the values.

[0088] Table 3

[0089]

Brief Description of the Drawings

[0090] In the following, preferred exemplary embodiments of the method according to the present invention will be explained with reference to the accompanying drawings, in which:

[0091] Figure 1 shows a cross-sectional view of the tool mold in a closed state;

[0092] Figure 2 shows a cross-sectional view of a tool cavity according to the present invention when applying granular material;

[0093] Figure 3 An exemplary embodiment of a tool mold having a foamed plastic mold made according to the present invention is shown; and

[0094] Figure 4 A further exemplary embodiment of a tool mold with an external heating system is shown. [Specific implementation method]

[0095] Figure 1 A cross-sectional view of a tool mold 2 in a closed state is shown, wherein the tool mold 2 is formed by two opposing tool cavities 21a and 21b, wherein the opposing tool cavities 21a and 21b surround a molding mold cavity 22. In the exemplary embodiment shown, the first tool cavity 21a is provided with a plurality of heating channels 24, through which a heating medium can be supplied to the first tool cavity 21a, so that the first tool cavity 21a can be heated to a defined temperature.

[0096] exist Figure 2 In FIG. 4 , an exemplary embodiment of a tool cavity 21 of a tool mold 2 is shown, wherein the tool cavity shown comprises a temperature sensor 4 , by means of which the temperature of the tool cavity 21 can be measured. Figure 2 , the process of applying granular material 3 by means of a spray gun 32 is shown, wherein the applied granular material forms a film 31 with a film thickness 33 in the region of the tool cavity 21. Figure 2 It can also be seen in FIG. 2 that by means of the specific application of the granular material 3 by means of the spray gun 32 , a layer thickness 33 of the applied granular material 3 can be adjusted or specifically influenced in parts of the tool chamber 21 .

[0097] Figure 3A plastic molded body with a proportional film layer coating 11 is shown, wherein the foam molded body is manufactured by using a tool mold 2, which is formed by a first tool cavity 21a and a second opposing tool 21b, by which the plastic molded body is produced, and the film layer coating 11 is applied to the plastic molded body 1 according to the present invention by applying plastic pellets 3 to the second tool cavity 21.

[0098] Figure 4 A further exemplary embodiment of a tool cavity 21 according to the invention is shown, which has a temperature sensor 4 and an external heat source 55 in the form of a plurality of radiant heaters with directional holes. The tool cavity 21 can be heated to a defined temperature by the external heat source 55, and the sensor 4 can be used to control the heat source 55.

Claims

1. A method for producing a foamed plastic molded body (1) having a film layer coating (11) by forming a molding mold cavity (22) using a tool mold (2) having at least one tool cavity (21), the method comprising the following method steps: -A) heating at least one tool cavity (21) of the tool mold (2); - B) applying pellets (3) to at least one heated tool cavity (21); -C) fusing the pellets (3) in the heated tool cavity (21) to form a liquid film layer (31); -D) applying the liquid film layer (31) to the foamed plastic molded body (1), and forming a film layer coating (11) on the surface of the plastic molded body (1) by fusing the liquid film layer (31) with the surface of the plastic molded body (1); -E) cooling the at least one tool cavity (21) and ejecting the plastic molded body (1) coated with the film layer (11), When carrying out the method, the temperature of the at least one tool chamber (21) is controlled so that during the entire period of carrying out the above-mentioned method steps B) to D), the temperature is at least higher than the melting temperature of the applied granular material (3).

2. The manufacturing method according to claim 1, characterized in that: Prior to carrying out method steps A) to E), the plastic molded body (1) is produced in the tool mold (2) by an expansion method, the tool mold (2) is then opened, wherein the plastic molded body (1) remains in at least one first tool cavity (21a), and method steps A) to E) are then carried out on at least one second opposing tool cavity (21b), wherein the operation of applying the liquid film layer (31) by fusing the liquid film layer (31) with the surface of the plastic molded body (1) according to method step D) is carried out by closing the tool mold (2) again, and cooling of the at least one tool cavity (21) in method step E) is carried out in the closed molding state.

3. The manufacturing method according to claim 1, characterized in that: In the area of ​​the at least one tool cavity (21a, 21b), method steps A) to C) are first performed, then the tool mold (2) is closed, and the mold cavity (22) of the tool mold (2) is filled with first expandable plastic pellets or with foam beads, respectively, and then the first expandable plastic pellets or the foam beads are expanded in the mold cavity (22), respectively, wherein method step D) is performed based on the fact that the plastic molded body (1) or the first expandable plastic pellets or the foam beads are respectively pressed against the liquid film layer (31) formed on the at least one tool cavity (21) to expand and fuse with it.

4. The manufacturing method according to claim 1, 2 or 3, characterized in that: In method step B), the granular material (3) is applied to the multi-part tool mold (2) outside the area of ​​the at least one tool cavity (21a, 21b), and at least one part of the multi-part tool mold (2) includes a sealing ring, which, when the tool mold (2) is closed, throws the granular material (3) outside the area of ​​the at least one first and / or second tool cavity (21a, 21b) to form a surrounding edge in the edge area of ​​the at least one first and / or second tool cavity (21a, 21b).

5. The manufacturing method according to claim 3, characterized in that: In the method steps for respectively expanding the first expandable plastic pellets or the foam beads, the expansion process is terminated after a defined period of time, and the first expandable plastic pellets or the foam beads that have not yet melted or expanded are respectively removed from the mold cavity (22), so that only one layer of the first expandable plastic pellets or the foam beads is adhered to the film layer (31).

6. The manufacturing method according to claim 5, characterized in that: After removing the non-expanded portion of the first expandable plastic pellets or the foam beads, respectively, the mold cavity (22) is filled with second expandable plastic pellets or foam beads, respectively, and then the second expandable plastic pellets or foam beads are expanded to form the plastic molded body (1).

7. The manufacturing method according to any one of claims 1, 2, 3, 5 and 6, characterized in that: In method step B), the granulate (3) is applied to the at least one tool chamber (21) by means of a spray gun (32).

8. The manufacturing method according to any one of claims 1, 2, 3, 5 and 6, characterized in that: In method step A), the at least one tool chamber (21) to be heated is heated by introducing a heating medium into the at least one tool chamber (21) via a corresponding heating channel (24).

9. The manufacturing method according to any one of claims 1, 2, 3, 5 and 6, characterized in that: In method step A), the at least one tool chamber (21) to be heated is heated to a temperature at least above the melting temperature of the granular material (3).

10. The manufacturing method of claim 9, wherein the at least one tool cavity is heated to a temperature in the range of 80°C to 260°C.

11. The manufacturing method according to any one of claims 1, 2, 3, 5 and 6, characterized in that: In method step B), powdered thermoplastic granules (3) are applied to the at least one tool cavity (21).

12. The manufacturing method according to any one of claims 1, 2, 3, 5 and 6, characterized in that: In method step A), the at least one tool cavity (21) to be heated is heated by an external heat source (55) which is arranged spaced apart from the at least one tool cavity (21).

13. The manufacturing method according to claim 12, wherein the external heat source is a radiant heater.

14. The manufacturing method according to any one of claims 1, 2, 3, 5 and 6, characterized in that: In method step B, the granular material (3) is applied only proportionally to a defined partial area of ​​the at least one tool cavity (21) to form at least one film layer (31) in certain areas, wherein the sub-area of ​​the at least one tool cavity (21) is covered to prevent the application of the granular material in method step B.

15. The manufacturing method according to any one of claims 1, 2, 3, 5 and 6, characterized in that: In method step B), granulate (3) is applied to the tool cavity (21) with a layer thickness (33) in the range from 0.05 mm to 2 mm.

16. The manufacturing method according to any one of claims 1, 2, 3, 5 and 6, characterized in that: In method step E), the at least one tool chamber (21) to be cooled is cooled convectively and / or conductively.

17. The manufacturing method according to any one of claims 3, 5 and 6, characterized in that: The expandable plastic pellets or the foam beads are each supplied and / or discharged by means of at least one injector device.

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