WO2018100207A1 - Method for producing a coated foam sheet and coating device - Google Patents

Abstract

A method for producing a coated foam sheet is described. A foam sheet (F) is created by feeding a first polymer melt mixed with at least one expanding agent through a slot die (S1). At least one side of the foam sheet (F) is coated with an unfoamed coating (B). The coating (B) is created by feeding an extruded, second polymer melt through a second slot die (S2). The coating is brought up to the foam sheet (F). Temperature control is used to prevent the foam sheet (F) from solidifying on the surface or right through until the foam sheet (F) is coated with an unfoamed coating (B).

Description

 Process for the preparation of a coated foam web and feeder

The present invention relates to the field of extrusion technology, and more particularly to the field of foam extrusion.

It is known to use an extruder for the production of foam products, in which a plastic mass is melted. Blowing agent under high pressure is added to the melt thus produced. The blowing agent added melt is pressed through a shaping opening of the extruder, so that after passing through the opening, which has approximately the shape of a nozzle, a foam body is formed. In the production of a foam web, a slot die is used.

In many applications, the smoothest possible surface of the foam web is advantageous, for example for printing.

It is an object to provide a way to create a smooth-surfaced foam sheet without significantly degrading the properties of the foam sheet.

This object is solved by the subject matters of the independent claims. Further advantages, features, properties and embodiments will become apparent from the dependent claims, the following description and the figures. A process for producing a coated foam web is described. A foam sheet is produced by passing at least a first plastic melt through a slot die. The at least one first plastic melt (hereinafter: first plastic melt) is mixed with at least one propellant. As a result, the first plastic melt foams on passing through the slot nozzle and then following.

The plastic melt is produced in particular in an extruder plant with one or more extruders. The plastic melt is produced by plastic particles are melted in the extruder system and the resulting melt with the at least one propellant is added (also in the extruder plant). The extruder system may have an extruder which melts the plastic particles and in which the blowing agent is added. This extruder can also have a tool that forms the slot nozzle. The extruder system may further comprise a first extruder, in which the plastic particles are melted. The resulting melt is fed to a second extruder of the extruder plant, which has the tool which forms the slot nozzle. The blowing agent may be added through the first or the second extruder. To obtain a smooth surface, at least one side of the foam sheet is coated. The foam sheet receives a coating on one side or on both sides (the side surfaces are not considered here). The coating corresponds to a coating layer on one or both sides of the foam web. At least one side is coated with at least one such coating by (one or more times) at least a second plastic melt is passed through an at least second slot die. The at least one second plastic melt is produced by extrusion. The guided through the second slot die plastic melt, which forms the coating (or coating layer) is brought to the foam web. In particular, the coating is brought into physical contact with the foam web. There may be several coatings on one side of the

 Foam web are applied by several coatings produced and applied (by direct physical contact) in particular successively. One or more coatings may be applied to only one side of the foam sheet or both sides.

The coating may be unfoamed or at least comprise an unfoamed layer. Further, the coating may be partially foamed comprising a partially foamed layer. A partially foamed coating has cells which, however, do not constitute more than 50%, 40%, 20% or, in the case of low-foamed coatings, no more than 5%, 2% or 1% of the volume of the coating or layer concerned. The coating may also be completely foamed or comprise such a layer, the internal volume of the cells being greater than 50%, 80%, 90% or 95% (where applicable at least 98% or 99%) of the (total) volume of the coating in question or location. The cells may be (mostly) closed or (for the most part) open in partially or fully foamed coatings or layers. The coating can be one or more layers. The coating may be filled or at least comprise a filled layer. A filled coating or layer comprises particles distributed in the coating or layer. The particles are hollow, for example, but may also be completely filled. The particles can be essentially round. Further, instead of or together with the particles, fibers may be provided in the coating or layer. As the second plastic melt, therefore, a liquid plastic material may be used which comprises blowing agents and / or particles (or fibers) or which comprises neither blowing agent nor particles (or fibers).

The coating produced by the second plastic melt is applied to the

Foam sheet applied. Here, the two slot nozzles are preferably convergent or at least parallel to each other. The foam web and the coating are guided to each other; the transport directions of the foam web and the coating lead together. The transport directions of the foam web and the coating have an intersection where the coating comes into physical contact with the foam web. The merging of the foam web and the coating results in a common transport direction.

The foam web is tempered after exiting the slot die. By tempering the foam sheet is prevented from superficial or complete solidification until the foam sheet is coated with a coating. Prior to merging the foam sheet and the coating, the foam sheet (and in particular the coating) is prevented from superficial or complete solidification by tempering the foam sheet and / or the coating. The tempering can bring about internal (partial) solidification of the foam web and / or the coating. The tempering prevents complete or (only) superficial solidification of the foam web and / or the coating. The tempering takes place after the passage of the first and the second plastic melt. The tempering takes place before the physical contact of the coating with the

Foam web instead. The tempering is designed such that the coating and / or the foam web receives a temperature which prevents more than the surface of the foam web from melting due to the application of the coating. The tempering is set in such a way that cells of the foam web in a region bounded by their surfaces do not burst. The tempering can be adjusted by adjusting a heat transfer performance acting on the coating and / or on the foam sheet. The heat transfer performance depends in particular on a set temperature, set dwell time, set heat medium delivery rate and / or on a set temperature profile (along the relevant conveying direction), these operating parameters can be set to adjust the temperature. The foam sheet is conveyed away from the slot die, along with the coating.

The foam sheet thus does not solidify completely until the coating is applied. This results in a good adhesion of the coating. Furthermore, even after the application of the coating, the foam web is still in a thermoplastically deformable state (due to the tempering) which allows cell growth and / or plastic displacement of cell walls within the foam web. The coating thus does not take place on a cold foam web. The application of the coating thus does not result in the foam web being melted (due to heat transfer from the coating to the foam web) (beyond superficial areas). Due to the tempering, the coating (in relation to a longitudinal section) has a heat amount which is insufficient to melt the foam web over its surface. This amount of heat is defined by the temperature as well as by the ground surface coating of the coating (defined in particular by its thickness). The tempering provides the foam web (or its outer surface) at a temperature which is at least above the ambient temperature, and preferably by a predetermined margin below or above the

Melting temperature (or the beginning of the melting temperature interval) of the foam web is. The margin may be, for example, 30 K, 20 K, 10 K or 5 K and is in particular not greater than 60 K. To ensure good adhesion, the coating and the foam web is combined under pressure. The pressure compresses the coating and the foam web together. The pressure is preferably adjustable. The pressure is exerted in particular on both sides of the foam sheet (and the coating). The coated foam web is combined by means of physical contact by contact surfaces. pressed. This is done when the foam sheet is not superficial or completely solidified.

The coating is applied to the foam web during coating with a contact pressure. Alternatively or additionally, an adjustable contact pressure can be exerted on the coating web coated with the coating (i.e., after the combination of coating and foam web). The contact pressure is preferably exerted (or the compression under pressure) is carried out when the foam web is not superficial or completely solidified. The contact pressure is exerted (or the compression under pressure) is in particular carried out when the coating is not yet superficially or completely solidified. Furthermore, the contact pressure can be exerted (or the merging can be carried out under pressure) if the coating and the foam web are not yet superficially or completely solidified.

The contact pressure can be exerted by pivotable, displaceable or rotatable surfaces. The contact pressure can be exerted by surfaces, of which at least one is movable (and in particular lockable). The contact pressure can be exerted by surfaces whose distance from one another (across the foam web) is adjustable or whose orientation is adjustable relative to one another. It can be provided Anpressflächen to exert the contact pressure. At least one of the contact surfaces is adjustable (in terms of orientation or position). The contact surfaces may be arranged as one or more pairs. Each pair has two opposing contact surfaces. The contact surfaces of a pair can also be offset from each other in the conveying direction. Between the contact surfaces of each pair, the (coated) foam web is conveyed. In the case of several pairs or several contact surfaces, these are preferably arranged one after the other in the conveying direction of the foam web. Both contact surfaces of a pair or only one contact surface of a pair are or is movable.

The contact surfaces are designed in particular tempered or temper the (coated) foam web. The pressing surfaces may include channels for a heat medium, an electric heater or a microwave source in order to be able to influence the foam web in a temperature-controlled manner. Different contact surfaces can be different tempered or adjusted to different temperatures or temperature ranges. In particular, contact surfaces of a pair are tempered or adjusted to the same temperature or to at least overlapping temperature ranges.

The contact pressure can also be exerted by a fluid flow. The fluid flow is directed to the coated foam web. The fluid flow is on opposite sides or surfaces of the coated foam web. In particular, the fluid flow may be directed to a region where the coating is applied to the foam web (ie, a region of physical contacting of the coating and the foam web). The strength of the fluid flow (ie, its flow rate) is adjustable. The fluid flow originates from nozzles directed towards the foam web, particularly nozzles directed towards opposite sides of the (coated) foam web. The direction of the fluid flow is in particular adjustable. The nozzles can be designed to be pivotable. The nozzles may be arranged as one or more pairs. Each pair has two opposing nozzles. These are directed to each other. At least one nozzle may be provided, which is directed onto the foam web, with no nozzle being directed directly onto this nozzle (directed towards the foam web). The nozzles, in particular the nozzles of a pair can also be offset from each other in the conveying direction. Between the nozzles of each pair, the (coated) foam sheet is conveyed. In the case of several pairs or multiple nozzles, these are preferably arranged one after the other in the conveying direction of the foam web. At least one nozzle, both nozzles of a pair, or only one nozzle (a pair) are movable. The nozzles may have a gap through which fluid passes, the gap extending along the entire width or along the entire circumference of the foam web. The result is a fluid (partial) flow, whose cross section extends along a line and preferably along a straight line section or a circle or circular section. The fluid flow can be tempered, ie it can be cooled or heated. The fluid flow may be a gas flow or a fluid flow; as gas comes air or nitrogen or other and liquid or water or oil is considered. There may be provided a heating or cooling device (or a combined heating and cooling device) that controls the fluid flow. In particular, In particular, the fluid is tempered before it passes through the respective nozzle or nozzles. There may be a pump or a pressurized fluid reservoir to deliver the fluid. The tempering can be carried out by at least one of the contact surfaces or by all contact surfaces. The tempering may be carried out by the fluid flow or by at least one partial stream of fluid emerging from a nozzle or by the fluid flow passing out of all the nozzles. Preferably, the tempering of at least one contact surface and at least one nozzle (or the fluid flow) is performed.

 The contact pressure may be exerted by at least one pivotable, displaceable or rotatable (i.e., movable) surface, also referred to as a contact surface. The contact pressure may be exerted by fluid flow directed to the coated foam web. Both variants of the pressure exercise are possible.

Contact surfaces and nozzles can alternate in the conveying direction of the foam web. Preferably, at least two pairs of contact surfaces are provided, wherein at least one nozzle or a pair of nozzles between the Anpressflächen pairs (in the conveying direction of the foam web) is arranged. Between in the conveying direction successive contact surfaces may be provided a nozzle or a pair of nozzles. There may be provided a nozzle or pair of nozzles directing a fluid (partial) flow to a region where the coating contacts the foam web. Optionally, a contact pressure (by at least one contact surface or by fluid flow) is also exerted on the foam web before it comes in contact with the coating. It can act on the foam sheet at least one contact surface or at least one fluid flow before it comes into contact with the coating, in particular (in addition to the pressure) to temper the foam web, ie to cool or to heat. Before the foam web comes in contact with the coating, it can first be cooled (to produce a partial solidification of the foam web), in order then to be heated at least superficially (by a fluid partial flow and / or by a tempering contact surface or a temperature control surface) tempering but not exerting pressure on the foam web). The tempering surfaces and / or the contact surfaces can in particular be individually tempered. It is also possible to temper individual pairs of tempering surfaces and / or contact surfaces. The tempering surfaces and / or the contact surfaces can be essentially flat (ie have over their course not more than 45 °, 30 °, 15 ° or 5 ° angular differences in the normal direction). The tempering surfaces and / or the contact surfaces can also be rounded (convex). The Temperierungsflächen and / or the contact surfaces may be curved to the foam sheet to the outside (convex). The Temperierungsflächen and / or the contact surfaces may have the shape of an outer surface of a hemisphere (a spherical or spherical segment) or the shape of an angular portion of a cylinder jacket. The cylinder in question may have an oval, ellipsoid or circular or polygonal rounded cross-section. The temperature control surfaces are, in particular, surfaces of a contact temperature control arrangement. The contact surfaces are, in particular, surfaces of a combined contact tempering and pressing arrangement.

The term "nozzle" without a prefix here refers to a fluid nozzle through which fluid for pressure application and / or temperature control occurs.The term "slot nozzle" or "round nozzle" or "flat nozzle" refers to a nozzle through which plastic melt passes.

The coated foam web can be passed successively on surfaces of different temperature or (in the conveying direction of the foam web) decreasing temperature. These surfaces may exert pressure on the foam web or may cause it to be punctiform or permanent plastic deformation. Heat is transferred between the surfaces and the foam web (as part of tempering). The surfaces themselves are tempered, ie cooled, heated, or both. The coated foam web can be passed successively to contact surfaces of different temperature or decreasing temperature. The contact surfaces exert a pressure on the (coated) foam web. This can lead to a punctiform or permanent deformation of the foam web, and in particular can lead to a cohesive connection between the foam web and the coating. In one example, three pairs of surfaces or contact surfaces are provided, which are tempered in the conveying direction with decreasing temperature. Also, the partial flows of several nozzles, one after the other in the conveying direction may have different temperatures, in particular in the conveying direction decreasing temperatures.

The first and second plastic melts can be passed through two adjacent slot nozzles. It may be provided a tool or a matrix through which or the first and the second plastic melts are performed. The slit nozzle, through which the first plastic melt is guided and slit nozzle, through which the second plastic melt is guided, can both be formed by the same tool or by the same matrix. In particular, the slot nozzles are not more than 1 m, 50 cm, 30 cm, 5 cm, 1 cm or 5 mm apart. Between the slot nozzles, a partial flow of fluid can be provided. It may be provided a partition wall adjacent to both slot nozzles. The partition separates the slot nozzles from each other. In particular, at least one ring may be provided which separates the slot nozzles and adjoins at least one of the slot nozzles (channels). The partition wall or the ring or its end face can have a thickness in the height of the outlet of the slot nozzles which is less than 10 cm, preferably not more than 5 cm, 2 cm, 1 cm, 5 mm or 3 mm. The partition or the ring may be hollow or made of solid material. The partition or the ring can be tempered. The first slot nozzle and the second slot nozzle are in particular preceded by different extruders or extruder systems. The plastic melts are passed to each other before passing through the slot nozzles, but not mixed.

The first and second plastic melts will be passed through round slit nozzles according to one embodiment. The first and the second slot nozzle can therefore each define a slot which is self-contained, for example in the form of a circle, an oval, an ellipse, or a polygon, in particular with rounded corners. The result of the guiding of the plastic melts is a circumferentially closed body in the form of a hollow cylinder. The cross-section of the resulting (coated) foam web is widened. Along the conveying direction thus increases the cross section of the (circumferentially closed) path. The thickness of the web increases in particular along the conveying direction due to (progressive) foaming. The coated foam web is widened (during conveyance along the conveying direction). The coated foam web is widened, in which the (peripheral) lain closed foam web) is conveyed over a mandrel. The mandrel has a cross section that starts along the conveying direction. Furthermore, it can be provided that the self-contained (coated) foam web is severed at one point of the circumference in order to be able to lay flat the foam web. This preferably takes place after the foam web has been widened (as a circumferentially closed web). The mandrel may be cooled and thus provided as a cooling mandrel. It can be provided that the thickness expansion is limited, in particular in order to obtain a predetermined target width. Preferably, the first and second plastic melt are passed through at least two circular slot nozzles, which are arranged coaxially with each other. In this case, the circular slot nozzles can be separated from a partition wall adjacent to both circular slot nozzles. The Rundschlitzdüse, through which the first (mixed with blowing agent) plastic melt is guided, can surround the Rundschlitzdüse through which the second plastic melt is guided. This leads to a coating of the resulting (circumferentially closed) foam web on an inner side of the (circumferentially closed) foam web. The Rundschlitzdüse through which the first (mixed with blowing agent) plastic melt is guided, can be encompassed by the Rundschlitzdüse through which the second plastic melt is guided. This leads to a coating of the resulting (circumferentially closed) foam web on an outer side of the (circumferentially closed) foam web. The foam web can be coated on both sides. It can be provided two slot nozzles, through which the second plastic melt is guided, while through a slot nozzle, the first (mixed with propellant) plastic melt is guided, which is in particular concentric between the two slot nozzles. At the outlet of the two slot nozzles, a coating is formed, wherein in each case one of the coatings is applied to the foam web, which arises between the two coatings (or coating layers). The slit nozzles can be formed by the same tool or can be formed by different tools, in particular tools which are movable relative to one another. The slot nozzles can be designed to be movable relative to one another.

The slot nozzles can also be flat nozzles. The first and the second plastic melt can be passed through at least two flat nozzles. These are are preferably arranged parallel to each other. The flat nozzles may be formed by the same tool or by the same matrix. The flat nozzles may be separated by a partition wall adjacent to both flat nozzles. The foam web can be coated on one side, wherein a first and a second flat nozzle are provided. The first plastic melt is guided through the first flat nozzle and the second plastic melt is guided through the second flat nozzle. The foam web can be coated on both sides, wherein a first and two second flat nozzle are provided. The first (with propellant) plastic melt is guided through the first flat nozzle and the second plastic melt is guided through the second flat nozzles. The first flat nozzle is located between the two second flat nozzles. At the outlet of the two second slot nozzles, a coating is formed in each case, wherein in each case one of the coatings is applied to opposite sides of the foam web which arises between the two coatings (or coating layers). In the case of two second flat nozzles or round-slot nozzles, a dividing wall which adjoins the flat or round-slot nozzles can be located between each of the second flat or round-slot nozzles and the first flat or round-slot nozzles.

The gap thickness of the flat or round slot dies or slot dies mentioned here is preferably constant, but may vary according to a profiling along the gap. The gap thickness is preferably significantly smaller than the gap length. The gap thickness can not be more than 10%, 2%, 1%, 0.5% or 0.2% of the gap length.

The coated foam web solidifies (especially after tempering). This also solidifies the coating. The solidification results from the ambient temperature and possibly also at least partially by the tempering, in particular by a final phase of the tempering. After solidification, at least one surface of the foam sheet is surface-treated. In this case, the surface can be brought into contact with plasma (in particular in the sense of a treatment with atmospheric plasma). Alternatively or additionally, the surface may be subjected to a corona surface treatment. This may involve a coated or uncoated surface of the foam web. By the surface treatment, the diffusion behavior, gloss, feel, color, adhesion and / or other properties of the foam web can be changed. It can therefore be provided that by surface treatment at least one (mechanical or optical) property of the foam web is modified and in particular improved. In particular, the diffusion behavior can be improved, that is, the diffusion permeability can be increased, in particular for water vapor. The surface treatment in particular can improve the surface roughness, the diffusion permeability, the surface adhesion (in particular the adhesion for at least one further layer, for example a color layer), optical properties such as gloss, and / or haptic properties. By the surface treatment, the surface roughness can be reduced. It can increase the diffusion permeability. Furthermore, the surface adhesion can be increased. In addition, the gloss can be increased by surface treatment, ie the reflection coefficient for light and image fidelity in the reflection. It can reduce the opacity of the surface.

The surface treatment smooths the surface. The surface treatment preferably has only a superficial effect on the foam web or on the coating. The penetration depths of the surface treatment processes is preferably a few micrometers, in particular less than 10 μm. The surface treatment in particular reduces the waviness. Another (full-surface) surface treatment can be omitted.

The coating or each coating layer of the coated foam web preferably has a thickness of at least 1, 2, 5, 10, 25, 40, 70, 120, 150 μιτι or more. The width of the coated foam sheet is preferably at least 500, 900, 1200, 1500, 2000, 2500, 3500, 5000 mm or more.

The first plastic melt, ie the propellant added plastic melt is preferably a melt with one or more thermoplastic materials. Polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polylactides or cellulose acetate are preferably suitable as the plastic. The second plastic melt which serves for coating is preferably one which is preferably a melt with one or more thermoplastics. Suitable plastics are polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polylactides or cellulose acetate. The composition of the first melt may differ from the composition of the second melt. The plastic material Rial of the first plastic melt may substantially correspond to the plastic material of the second plastic melt. However, the plastic materials of the first and second plastic melts may also be different. When solidified, the elasticity of the coating may in some applications be greater than the elasticity of the foamed portion of the coated foam sheet, but may also be smaller depending on the application.

The density of the foamed part of the coated foam web in the solidified state or in the final state of the first melt is preferably not more than 25, 50, 75, 100, 150, 200, 250, 300, 350, 400 kg / m ³ (in particular in the case of polypropylene as plastic material).

The foam sheet is preferably coated with the at least one coating before the foam sheet reaches a fully foamed state. The foam sheet may be coated with the at least one coating before the foam sheet reaches the final thickness (at full solidification). The foam sheet is coated with at least one coating before the foam sheet has reached 100%, 95%, 90%, 85%, 80% or 60% or less of the final thickness. The final thickness may be the thickness of the foam sheet after complete solidification or after the maximum temperature within the foam sheet is at least 20K, 40K or 60K below the melting point or below the melting range of the first plastic melt.

Furthermore, a coating apparatus for carrying out the method described here will be described. The coating apparatus may be configured to be connected to a tool, a matrix or slot nozzles. The foam web coating apparatus comprises a first foam web feed and a second coating feed. These supplies are in a state in which the coating device of a slot nozzle is connected downstream, the openings into which the respective slot nozzles are directed. The feeds are adapted to receive the foam web and the at least one coating. The coating apparatus may have a conveying mechanism which determines the conveying direction of the foam web. The coating device has a controlled tempering device. This is set up to carry out the temperature control described here. The tempering device is in particular designed to act on a tempering zone. This follows (in the conveying direction) on the first feeder and / or on the second feeder. The tempering zone is connected downstream of the feeders. At least part of the tempering described here takes place in the tempering zone. The temperature control device is set up to prevent the foam web from superficial or complete solidification by tempering the foam web (as described here). This is achieved by appropriate heat supply or by appropriate heat dissipation, in particular in the context of tempering. It can be provided a control or regulation of Temperierungsvorrichtung, the operating parameters of tempering (temperature, residence time, fluid flow rate, ...) controls with the regulatory objective to keep at least the surface of the (still uncoated) foam sheet above a point from which the foam sheet would at least superficially freeze. The feeds are hereby directed to a point within or at the edge of the tempering zone. In other words, the feeds lead to the tempering zone, so that the foam web and / or coating supplied by the feeds is guided through the tempering zone and thus exposed to the tempering step.

The coating device further comprises means for compressing the (coated) foam web. The means are arranged to compress the coated foam sheet by physical contact (by contact surfaces), fluid flow, or a combination thereof. The coating device thus has contact surfaces as a means for compressing the foam web, which are arranged to compress the coated foam web by means of physical contact when the foam web is not yet superficially or completely solidified. The means provide that the pressure is applied during application of the coating and, or act on the coated foam sheet. The means are thus set up to act in a pressing area on the foam web in which it receives the coating or is coated. In particular, the pressing region overlaps with the tempering zone. As a result, the means are adapted to exert the pressure of compression when the foam sheet is not completely solidified (especially not at the surface). The pressing area and the tempering zone overlap in particular at the position of the coating device at which the coating is brought into contact with the foam web. This corresponds in particular to a position in which the extension directions of the two feeders intersect. The coating device may have one or more pivotable, displaceable or rotatable (generally: movable) contact surfaces. The coating apparatus may further include one or more fluid nozzles. These are directed to a certain area, wherein the coating device is arranged to transport the coated foam web along this area. This area may correspond to the tempering zone, may correspond to the pressing area, or may overlap with the tempering zone and / or the pressing area. The fluid nozzles of the coating apparatus correspond to the nozzles mentioned in the description of the method (for the delivery of fluid). The pressing surfaces of the coating device correspond to the contact surfaces mentioned in the description of the method.

The coating apparatus may further include an extrusion die (or matrix) having slot dies (slit dies or slot dies, also referred to as flat dies) along which the leads connect. The slot nozzles are aligned with the respective ones of the feeders. The extrusion tool is adapted to be connected to a discharge end of an extruder. A device with an extrusion line, an extrusion tool and a coating device connected thereto can be used to carry out the method. However, essential aspects of the procedure described here can be realized with the coating apparatus equipped with an extrusion tool or not (in particular if this is intended for connection to an extruder which already comprises a tool with slot dies).

The tempering device may have a plurality of surfaces. These are preferably arranged one after the other in a transport direction of the coating device. The tempering device is set up to control the surfaces in the transport direction with different and in particular decreasing temperature. The tempering device may comprise electrical heating elements, may comprise heat medium channels and / or may comprise a microwave source. The relevant components are provided in a body forming the surfaces.

FIG. 1 schematically shows an exemplary embodiment of the coating device described here and serves for a more detailed explanation of the method.

FIG. 1 shows a matrix M (of an extruder (not shown) or as part of the coating device) through which passages (separate) open at a first slot nozzle S1 and a second slot nozzle S2. Shown dashed is another channel that can end in a further slot nozzle, between which and the second slot nozzle S2, the first slot S1 is so as to achieve a double-sided coating (with non-foamed plastic melt). The first slot nozzle S1 or the channel leading to this slot nozzle carries a first plastic melt.

After passage of the first plastic melt through the first slot nozzle S1, the foam web F results, which is conveyed in the course of the conveying direction T. After passage of the second plastic melt through the second slot nozzle S2 results in the coating B. This is not foamed. The coating B is shown in dashed lines.

The first and second slot dies S1, S2 are adjacent to each other and separated, for example, by a distance of less than 10 cm or 5 cm. The slot nozzles S1, S2 (or the further slot nozzle) are aligned parallel to one another or are convergent with one another. The slot nozzles S1, S2 open in directions which are (substantially) aligned parallel to each other.

To coat the foam web F, the coating B is applied. For this purpose there are pressure-exerting devices in the form of surfaces 10a-12b as well as fluid nozzles 20a-21b. These can be combined with each other or used individually.

The pressure applying devices press the foam web F toward the coating B. Alternatively or additionally, they press the coating B toward the foam web F. At least one of the pressure-exerting devices presses at least from one side on the foam path (physically or through the flow). Preferably, this is the side where the coating B is located.

The fluid nozzles 20a and b are arranged in pairs and are located on different sides of the foam web F. The fluid nozzles 20a and b act on a location of the foam web F to which the coating B has already been applied. The fluid nozzles 21 a and b are arranged in pairs and are directed to the foam web. A first fluid nozzle 20a is located in the transport direction T (i.e., upstream) of the fluid nozzle 21a. Both fluid nozzles are directed to the side of the foam web F, on which the coating B is applied.

Furthermore, surfaces 10a-12b are provided, which exert a contact pressure. The surfaces 10a, b are arranged in pairs and are provided opposite each other. The same applies to the surfaces 1 1 a, b. The foam web F is passed between the surfaces 10a, b and 11a, b. The surface 12b acts on one side of the foam sheet F, which is opposite to the side on which the surface 12a acts. The surface 12b is not disposed opposite to the surface 12a, but the surfaces 12a, b are offset relative to each other in the transporting direction T. It may also be provided a surface (which exerts pressure on the foam web F) to which no surface on the opposite side of the foam web F is assigned. At least one of the surfaces 10a-12b is movable (ie, pivotable or movable toward or away from the foam web). The surfaces form contact surfaces according to this approach. At least one of the surfaces 10a-12b may be tempered and thus be part of a tempering device. The surfaces 10a-12b can be tempered individually or in groups individually or have controlled temperatures. There may be pairs of surfaces at the same temperatures and tempered together or have a jointly controlled temperature. Different groups or pairs may have different temperatures. For example, the surfaces 10a, b may have a higher temperature than the surfaces 11a, b. The surfaces 1 1 a, b may have a higher temperature than the surfaces 12 a, b. In particular, the temperature of downstream surfaces in the transport direction T may be lower than the temperature of surfaces which are relatively high. tiv this upstream. The surface form Temperierungsflächen according to this approach. The same surface or surfaces can be both tempering surfaces and contact surfaces. Between the surface 10a and the gap S1, the fluid nozzle 20a acts on the

Foam web F. Between the surface 10b and the gap S1, the fluid nozzle 20b acts on the foam web F. Between the surface 10a and the surface 11a, the fluid nozzle 21a acts on the foam web F. Between the surface 10b and the surface 11b the fluid nozzle 21b acts on the foam web F. Between two successive surfaces in the transport direction F, a fluid nozzle can be provided, which is directed onto the foam web. The surface 12a as the inner surface may be a surface of a mandrel, and the matrix M forming the slit nozzles S1 and S2 may be rotationally symmetrical about an axis A. As shown in FIG The transport direction T can be at least in sections (in particular after the coating or application of pressure) parallel to the axis A. Before or during the application of pressure, the transport direction points away from the axis and corresponds to a widening of the foam web F. the foam web F was coated, the coated foam web BF results.

Right below the matrix M, the outlet from the gap nozzles S1, S2 is shown enlarged. A wall W separates the gap nozzles S1 and S2. The first plastic melt exits the slit nozzle S1 before the coating B is applied to the foam web F (which is formed from the first plastic melt).

The matrix M is not necessarily part of the coating device. The coating device comprises a first feed Z1 (for the foaming foam layer F) and at least one second feed (for the coating B). The first and the second feeders Z1, Z2 lie next to one another (seen perpendicularly to the transport direction T). The feeders Z1, Z2 differ, may partially overlap, but are preferably separate from each other. It may extend between the feeds Z1, Z2 a wall. The feeders are set up to be aligned with the slit nozzles S1, S2 (and optionally further slit nozzles) when the coating device is mounted on the matrix M. The elements with the reference numerals 10a-12b and 20a-21b press the coating (dashed) on the foam web. It can be provided that only a part and thus not all of these elements exert pressure on the foam web F. Furthermore, a part or all of the elements 10a-12b and / or the fluid nozzles 20a-21b (completely or partially) contribute to the temperature control of the foam web F. The fluid delivered by the fluid nozzles 20a-21b may be air in particular. The fluid discharged from the fluid nozzles 20a-21b may be heated or cooled. The surfaces 10a-12b serve to compress the (coated) foam web, to temper it, or both. The nozzles 20, 21 serve for compressing the (coated) foam web, for tempering the same, or both.

Shown in Figure 1 is a one-sided coating, here on the inside of the resulting hollow cylinder (formed by the foam web F). Aiterative or additional borrowed can be applied on both sides, see second coating slot above the foam slot S1, which is shown in dashed lines.

FIG. 2 shows a further embodiment for a more detailed explanation of the procedure described here and the device used for this purpose. Due to the numerous functional similarities with the device of Figure 1, the same reference numerals are used. Designated by like reference numerals elements may be configured the same.

There are shown a first gap S1 and a second gap S2. Both correspond to the initial transport direction T, which, however, angled away with increasing distance from the columns. From the first gap S1 enters the first, mixed with blowing agent plastic melt and there is a foam sheet F, the edges are shown in dashed lines. Between the first and the second gap is a wall partition. This forms one side of the first gap S1 and one side of the second gap S2. From the second gap S2 occurs not mixed with blowing agent plastic melt, which forms the coating after exiting the gap. Again, only a one-sided coating is shown. There may be provided a further second gap on the other side of the first slit nozzle S1, from which also not with Propellant offset plastic melt can occur to form a further coating.

The exiting foam web F foams with increasing distance from the gap S1. The slit nozzles S1 and S2 in this embodiment are circular gaps to give an inner side of the resulting foam tube and an outer side. In a flat nozzle would also be two sides, such as a right and a left side. The same considerations arise, with reference to Figure 2, the left side corresponds to the inner side and the right side of the outer side.

Between a first surface 10a and a second surface 10b, the foam web F and the coating B are passed. The first and the second surface are not arranged opposite to each other, but offset in the transport direction T to each other. The second surface is on the outer side of the foam sheet F. The second surface 10b is closer to the gap nozzles S1 and S2 than the first surface (which lies on the inner side of the foam sheet). Both surfaces 10a, 10b are movable toward the foam web F and can be moved away from it. This is shown by the double arrows. The first surface 10a is formed, in particular in the case of a round nozzle S1, by a cubic surface section (or by a cylinder jacket section in the case of a flat nozzle). This also applies to the second surface 10b. The first and the second surface have the same temperature or are regulated with the same set temperature band. The second surface 10b is located at a point where the coating B has not yet been applied to the foam web F. Therefore, the second surface pushes the foam web inwards or in the direction of coating B. The first surface 10a is located at a point where the coating B is applied on the foam web or on which the coating B is applied to the foam web (ie the coating comes into contact with the foam web F). After the first and the second surface 10a, b, the foam web F is passed between two further surfaces, namely between the third surface 11a and the fourth surface 11b. The third surface 1 1 a and the fourth surface are not arranged opposite to each other, but offset in the transport direction T to each other. The fourth surface is on the outer side of the foam web F. The fourth surface 11b is closer to the gap nozzles S1 and S2 than the third surface 11a (which lies on the inner side of the foam web F). Both surfaces 1 1 a, b are movable toward the foam web F and movable away from it. This is shown by the double arrows. The third surface 11a is formed in particular in the case of a round nozzle S1 from a cubic surface section (or from a cylinder jacket section in the case of a flat nozzle). The fourth surface 11b is less rounded than the third surface. The fourth surface 1 1 b is substantially flat and follows only the course of the foam web. The third and the fourth surface 11a, b have the same temperature or are regulated with the same desired temperature band. The temperature of the third and fourth surfaces 11a, b is lower than the temperature of the first and second surfaces 10a, b.

After the third and fourth surfaces 11a, b, the foam web F is passed between two further surfaces, namely between the fifth surface 12a and the sixth surface 12b. The fifth surface 12a and the sixth surface 12b are not arranged opposite to each other, but offset in the transport direction T to each other. The fourth surface 12b is on the outer side of the foam web F. The sixth surface 12b is closer to the slit nozzles S1 and S2 (seen in the transporting direction T) than the fifth surface 12a (which lies on the inner side of the foam web F). The sixth surface 12b is movable toward the foam web F and movable away from it. This is indicated by the double arrow. The fifth surface 12a is not movable relative to the foam web. The fifth surface 12a is formed, in particular in the case of a circular nozzle S1, by a radial bulge of a widening body (for instance a mandrel). The expansion body is preferably rotationally symmetrical, for example in the form of a cylinder (widened at one end) or in the form of a truncated cone (with a bulge at one end). The bulge points (in the transport direction) towards the gap nozzles S1, S2. The bulge is in particular in the form of a Torusabschnitts. The sixth surface 12b has a smaller curvature than the fifth surface 12a. The sixth surface 12b is substantially flat and follows only the course of the foam web. The fifth and sixth surfaces 12a, b have the same temperature or are regulated with the same set temperature band. The temperature of the fifth and sixth surfaces 12a, b is lower than the temperature of the third and fourth surfaces 11a, b. There are also provided fluid nozzles 20a, 20b and 21a. The first fluid nozzle 20a is provided on the inner side and on the right side of the foam sheet F, respectively. The first fluid nozzle 20a is provided immediately adjacent to the second slot nozzle S2 and is directed to the coating B (and also to the foam web F). The first fluid nozzle 20a is directed to a point which lies between the first surface and the foam web F or the coating B. This results in an air cushion between the surface 10a and the coating B (or the foam web F), which is used for contactless pressure on the coating B or on the foam web F. Between the second surface 10b and the fourth surface 11b, the second fluid nozzle 20b is directed toward the foam web. The first and second fluid nozzles 20a, b are directed from different sides onto the foam web. The second fluid nozzle 20b is directed substantially perpendicular to the foam web B and presses the foam web F in the direction of coating B. In the transport direction F follows (briefly) on the point at which the first surface acts on the coating or on the foam sheet. The third fluid nozzle 21 a is directed into a space which is partially enclosed by the foam sheet B (by more than half a solid angle), and in which the third and the fifth surface are located. The third fluid nozzle 21 a is directed to a location of the foam web F, which is located between the first and the third surface 10 a, 1 1 a. The partial flows generated by the fluid nozzles are represented by the simple arrows emanating from the nozzles.

First (ie, after the plastic melts leave the gap nozzles S1, S2, the second surface exerts a pressure on the foam web in the direction of coating B. The pressure is exerted to the left or inwards, followed by the second nozzle 20b resting on the foam web pressure is exerted in the direction of coating B. Subsequently, pressure is exerted on the coating B in the direction of the foam web by the first fluid nozzle 20a and through the first surface 10a, followed by the fourth surface, which acts on the foam web F (at least in a tempering and possibly pressure-exerting manner) This is followed by the third surface 11a, which acts on the foam web F at least in a tempering and, if appropriate, pressure-exerting manner (from the coated side of the foam web F) on this, the sixth surface 12b acts on the foam web F, at least tempering and optionally applying pressure (From the side of the foam web F, which is opposite to the coated side). Finally, the foam web F is pulled across the fifth surface 12a. This acts at least tempering and possibly pressure exerting on the foam web F.

Pressure from surfaces and / or fluid nozzles may be alternately exerted thereon from the opposite sides of the foam web F. Surfaces and fluid nozzles may be arranged alternately or (in the case of an air cushion as before the first surface) at the same location of the foam web (viewed in the transport direction). The surfaces are particularly pressure-exerting, but can also be tempering or both.

It is envisaged that the at least one coating B and the foam web F are each freshly produced and brought together shortly after their production. The term "fresh" here means that no more than 1 min (or more preferably 10 sec or 2 sec) elapse between production and bringing together, and in particular that the foam web does not completely solidify between its production and coating The foam web and the coating are brought together warm, that is, in a state where neither the foam nor the coating has been (or have been) solidified since its formation foams up the foam web, in particular, the foam web still foams up when brought together with the coating.

FIG. 2 also serves to explain further embodiments. In a further embodiment, the surfaces 10b, 11b and 12b end faces of rings may be formed, which are arranged concentrically with each other. The rings are axially displaceable relative to each other. The front sides have different inclinations. The end faces are in particular rounded hollow cylinder ends. The front sides can be inclined differently. The end faces can follow the curved course of the transport direction T. The rings may have axes which are inclined differently to the nozzle direction of the slot nozzle S1. The outermost ring, which forms the end face 12b, may be inclined at a smaller angle to the nozzle direction of the slot nozzle S1, than the middle ring, which forms the end face 1 1 b. The middle ring, which forms the end face 1 1 b, may be inclined at a smaller angle to the nozzle direction of the slot nozzle S1, as the innermost ring, which the front side 10b forms. The spaces between the rings can be used as a slot nozzle, in particular as a second slot nozzle. An alternative position for the slot nozzle S2 would be the position S2 'between the surface 12b and 1 1 b. A further alternative position for the slot nozzle S2 would also be the position S2 "between the surfaces 11b and 10b The second slot nozzles, which are at alternative positions, are shown as dash-dotted double arrows In one embodiment, the surface 10b extends largely along one In addition, the surface 11b may extend largely along a plane and, moreover, the top surface 12b may extend largely along one plane, and if a second slot nozzle (for the coating B) is at position S2 ", then there would preferably be none Fluid nozzle 20b are present. This would be omitted (or go to the position labeled S2 '). The coating device (used according to the method) can comprise a plurality of rings, which lie in one another. The rings can be oriented inclined to each other, with the inclination decreasing or increasing with the radius. The rings are designed to be movable (displaceable), in particular in their axial direction. The direction of displacement is shown by a dotted double arrow. The displacement direction of a further outward ring is more inclined to the axis of the innermost ring, as the direction of displacement of a comparison in this more inward ring.

Claims

claims 1 . A process for producing a coated foam web, comprising:  Producing a foam web (F) by passing a first plastic melt mixed with at least one propellant through a slot die (S1) and coating at least one side of the foam web (F) with a coating (B) formed by passing an extruded second one Plastic melt is produced through a second slot nozzle (S2) and is brought to the foam web (F),  wherein the foam web (F) is prevented from superficial or complete solidification by tempering until the foam web (F) is coated with the coating (B) and the coated foam web (BF) is pressed together by means of physical contact by pressing surfaces when the foam web ( F) is not superficial or completely solidified. 2. The method of claim 1, wherein at least one coating (B) is coated, which is foamed, partially foamed, closed-cell, porous, single or multi-layered, filled, provided with particles, or is not foamed. 3. A process for the preparation according to claim 1 or 2, wherein the coating (B) is applied during coating with a contact pressure on the foam web and / or on the coated with the coating (B) foam web (F) an adjustable contact pressure is applied, wherein the contact pressure is exerted if the foam web (F) is not yet superficially or completely solidified, if the coating (B) is not superficially or fully solidified, or both. 4. The method of claim 3, wherein the contact pressure of pivotable, displaceable or rotatable surfaces (10a - 1 1 b) is applied, which correspond to the contact surfaces, or is exuded from these surfaces and a flow of fluid flowing on the coated foam web is directed, or both. Method according to one of the preceding claims, wherein the coated foam web (F) successively on the pressing surfaces corresponding surfaces (10a - 12b) of different temperature or decreasing temperature is passed. Method according to one of the preceding claims, wherein the first and the second plastic melt are passed through two adjacent slot nozzles (S1, S2). Method according to one of the preceding claims, wherein the first and the second plastic melt are passed through circular slit nozzles (S1, S2) and wherein the coated foam web is widened by passing the circular cross-sectioned foam web over a mandrel. Method according to one of the preceding claims, wherein the first and the second plastic melt are passed through two circular slot nozzles (S1, S2), which are arranged coaxially to one another and separated by a separating wall (W) adjacent to both circular slot nozzles (S1, S2). Method according to one of the preceding claims, wherein the first and the second plastic melt are passed through two flat nozzles, which are arranged parallel to each other. Method according to one of the preceding claims, wherein the coated foam sheet (S) solidifies and after solidification at least one surface of the foam sheet (S) is surface-treated and in particular the surface roughness, the diffusion permeability, the surface adhesion, optical properties, or haptic properties can be improved. Coating device for a foam web (F) having a first feed (Z1) for a foam web and a second feed (Z2) for a coating (B), the coating device having a controlled tempering device which is adapted to act on a tempering zone is followed by the first feed (Z1), wherein the tempering device is further inserted. is directed, by tempering the foam sheet (F) to prevent them from superficial or complete solidification, wherein the feeds (Z1, Z2) are directed to a point within or at the edge of the Temperierungszone, wherein the coating device pressing surfaces (10a-12b) as Means for compressing the foam sheet, which are established by means of physical Contact the compressed foam sheet together, if the foam sheet (F) is not superficial or completely solidified. Coating device according to claim 1 1, wherein the contact surfaces (10a-12b) are pivotable, displaceable or rotatable and / or the coating device has fluid nozzles (20a-21b), which are directed onto a region, wherein the coating device is arranged, the coated foam web (BS) along this area. Coating device according to claim 1 1 or 12, wherein the coating device further comprises an extrusion tool with round slit nozzles (S1, S2) or slot dies, along which the feeds (Z1, Z2) are connected. Coating device according to one of claims 1 1 - 13, wherein the tempering device has a plurality of surfaces (10a - 12b) corresponding to the contact surfaces, which are arranged one after the other in a transport direction (T) of the coating device, wherein the tempering device is set up, the surfaces (10a - 12b) 12b) with different temperatures with decreasing temperatures in the transport direction.