WO2023078921A1 - Heating element made of a ceramic material - Google Patents

Abstract

The present invention relates to a sealing or forming tool of a packaging machine having a heating element (19) for heating the packaging material, in particular a plastic monofilm, and also having a plurality of ceramic heating modules (21). The present invention further relates to the packaging machine (1, figure 1) as such and to a method for heating a material web (8, 14) or for producing a packaging tray. The modules (21) do not have a cover but can have a protective coating.

Description

Ceramic heating element

The present invention relates to a preheating, a sealing or a forming tool of a packaging machine with a heating element for heating the packaging material, in particular a monoplastic film, with a large number of ceramic heating modules. Furthermore, the present invention relates to the packaging machine itself and a method for heating a material web or for producing a packaging tray.

Heating elements are known from the prior art and are part of a packaging machine. With these packaging machines, a trough is formed by deep-drawing in a planar web of material, for example a film web. To do this, the material web must be heated with a heating element before deep-drawing. Particularly in the case of monofoils, which consist of a single material, the heating must take place quickly and evenly, a minimum permissible temperature for the desired shape result must not be fallen below and a maximum permissible temperature must not be exceeded, with the difference between the minimum and maximum permissible temperature being very large is small, i.e. there is only a small temperature window. At the same time, the warm-up must take place quickly in order to be able to provide sufficient cycle power. Conventional heating elements do not or only insufficiently meet these requirements.

It was therefore the object of the present invention to provide a preheating, a sealing or a forming tool and a packaging machine and a method for heating a material web or for producing a packaging tray which does not have the disadvantages of the prior art.

The task is solved by a preheating, a sealing or a molding tool of a packaging machine with a heating element for heating the packaging material, in particular a monoplastic film, with a large number of ceramic heating modules, in which the modules have no cover.

The statements made on this subject matter of the present invention apply equally to the other subjects and vice versa. Features of this subject of the present invention may be incorporated into other subjects and vice versa.

This subject matter of the present invention relates to a preheater, a sealing or a forming tool with a heating element used for heating a material web, used in particular in a packaging machine. Preferably, the web of material is stationary when heated and rests against the heating element. For this purpose, the heating element can have a means that improves the contact between the web of material and the heating element, which is provided in particular in such a way that the web of material bears against the heating element over its entire surface. Preferably the heating element is a plate, but not necessarily but preferably such a flat two-dimensional object. However, it can also be curved or have a different 3-dimensional shape. The heating element is preferably located upstream of the forming tool, in relation to the transport direction of the material web, for example as a so-called preheater or as a so-called sandwich heater and/or in the sealing tool. Alternatively or additionally, the heating element is integrated into the mold, for example as a so-called cover heater. The heating element can be connected directly to a carrier that is part of the packaging machine, in particular part of the forming station and here in particular part of the upper tool, or be an integral part of the carrier. This carrier can be provided to be vertically movable, so that it can be moved towards and away from the material web. Thermal insulation is preferably provided between the heating element and the carrier.

The heating element, which is operated with electrical energy, heats the material web preferably from one side, for example from above as in a lid heater or from below as in a so-called "preheating from below", or from both sides, for example from above and below as in a sandwich heating as so-called "pre-heating from above and below", especially if the energy input into the material web should be even faster.

The heating element has a large number of ceramic heating modules. Each module preferably has a plurality of, in particular discrete, heating means, for example 5-50, preferably 51-100, even more preferably 101->1000 heating means, in particular pixels. Such heating means are, for example, one or more printed circuit boards. Electrical energy can be applied to each heating element/pixel in different ways in order to achieve different actual temperatures, for example per heating element/pixel, and/or be regulated/controlled with different actual and/or setpoint values. The heating means can be provided according to a specific pattern on the module. They are preferably provided equidistantly. The modules of a heating element can differ from one another in shape and/or size and/or heat output. The module can also consist of a large number of pixels that can be controlled individually and/or in groups. These pixels can be arranged in a specific pattern in a module. The Pixels are preferably distributed equidistantly across the heating element. A specific number of pixels are preferably arranged on a printed circuit board, it being possible for the heating element to have a large number of such printed circuit boards. The pixels of a circuit board can be controlled individually or as one or more groups.

On the side of the heating element facing the web of material to be heated, the heating element has no cover. The heating element is therefore in direct contact with the web of material. For heating, the web of material lies directly against the heating modules of the heating element.

This preferred embodiment of the present invention can have the advantage of introducing the heating energy to be introduced into the material web in a targeted manner and with the local differences provided, for example from pixel to pixel, into the material web without the heating energy flowing away unintentionally into adjacent areas of the cover and thus can also come from the material web if the material web is intended to be colder there, for example, as can happen with a cover that conducts heat well. The omission of a cover makes it possible, even with large temperature gradients between heating means/pixels, to introduce the respective heating energy in a targeted manner into the areas of the material web in which it is intended. The principle-related outflow of heating energy within the material web itself is minimized by fast process steps and their quick succession, for example if the heating time is short and a subsequent intended shaping takes place immediately after the transfer of the desired heating energy. The person skilled in the art understands that the heating element is alternatively provided with a coating, in particular a coating applied chemically, thermally or by adhesive, for example in order to eliminate or at least minimize the tendency for the material web to stick to the heating element, such a coating not being a covering in the sense of the invention because it is thin compared to a cover and/or has a low thermal capacity or does not permit a pronounced outflow of heating energy into adjacent areas.

The energy transfer between the web of material and the heating element for heating the web of material preferably takes place by thermal conduction. The contact between the material web and the heating element is therefore preferably improved, for example by sucking the material web onto the heating element. The negative pressure required for this can take place through recesses in the heating modules of the heating element and/or through gaps and/or recesses between adjacent heating modules. The heating element preferably has a controller/regulator with which a setpoint temperature and/or an energy input value for the respective module or a group of heating modules can be specified and regulated/controlled. This control/regulation can be part of the control/regulation of the packaging machine or a separate unit.

Preferably controls / regulates the modules so that their actual temperature and / or their energy input before and / or during heating is different, for example, the energy input from the moment of contact between the heating modules and to be heated Material web increase by leaps and bounds.

Each module or group of heating modules and/or each pixel preferably has a sensor with which the actual temperature and/or the energy input can be measured, for example using the ohmic resistance of the heating element or using a separate sensor. This measurement is preferably carried out discontinuously, alternatively continuously.

The control/regulation preferably controls/regulates the module(s) in the edge area of the heating element with a higher setpoint temperature and/or a higher energy input than the module(s) in the central area of the heating element itself.

The web of material is preferably a monoplastic film or monofoil, i.e. a plastic film which consists of at least one layer and/or a single material or predominantly consists of a single material, for example at least 95% by weight of one material and/or a mixture of substances consists of a group of materials and is preferably considered to be recyclable and/or moderately or highly recyclable; in contrast to multi-layer foils or foils that consist of a mixture of substances from different material groups that are considered to be non-recyclable or at most slightly recyclable. The material of the monofilm is preferably 100% by weight or the majority, in particular at least 95% by weight, polypropylene (PP), polyethylene (PE) or polyethylene terephthalate (PET) or amorphous polyethylene terephthalate (APET) or a mixture of substances from only one material group, for example the polyolefins, for example PP and PE. For example, a monofilm can consist of at least 95% by weight of at least one PP layer, which is connected to a sealing or peeling layer made of PE. The thickness of the monofilm is preferably 250-500 μm, particularly preferably 290-310 μm. The temperature of the temperature window is preferably 135-137° C. or the temperature window covers a range of preferably 3 Kelvin. Preferably, the recycled content of the material is the

Material web, especially with A-PET no more than 20 - 50% by weight

With a thickness of the monofoil of 250-500 μm, 2.5-5 seconds are preferably required, or even only 1-3 seconds with greater energy input, in order to bring the material web to the desired temperature, at which thermoforming with a thermoforming result, i.e for example good shape is possible.

According to a further preferred subject matter of the present invention, the energy transfer per unit of time from the heating element to the material web is not constant over time during the heating. Preferably, at least 40%, preferably at least 50%, even more preferably at least 60% of the heating energy required to reach the desired temperature of the material web is transferred to the material web within 30% of the heating time.

Furthermore, the setpoint temperature preferably changes for at least one, preferably several, in particular all heating means/pixels during a heating cycle.

Alternatively or additionally, the heating system can be operated with a low-voltage network, for example 400V, or in particular a low-voltage network, for example less than 50V, in order to be able to provide very high amounts of electrical energy for a short time, which is then converted into heating energy.

The material web can be heated up quickly thanks to the increased set temperature and/or the booster function. This has proven to be the quality of the resulting deep-drawn packaging tray in terms of shape, for example in terms of pronounced contours, shape and dimensional accuracy compared to the shape of the tool, thickness distribution, for example within a package and/or an entire preference, transparency and/or color turned out to be advantageous.

According to the invention, the heating element is made up of a large number of heating modules, the surface of which is preferably partially rectangular and partially square. As a result, the most varied widths of material webs, ie different extensions of material webs in the direction transverse to the direction of transport, can be heated very efficiently. In the longitudinal direction, the modules can all have the same length. In the case of rectangular heating modules, extensions transverse to the transport direction of the material web of between 10 and 70 mm, preferably 20 and 60 mm, even more preferably 25 and 55mm The surface is to be understood as the surface of the module facing the material path.

The modules are preferably provided with a square surface in the central area and the modules with a rectangular surface in the edge area of the heating element.

A gap is preferably provided between two adjacent heating modules, which gap is preferably sealed, in particular with an elastic material. However, the gap can also be completely or at least partially open, for example to generate a negative pressure between the module and the web of material.

A heating element that has a large number of ceramic heating modules is preferably provided in a particularly thin-walled housing that encompasses the heating element from below and on the sides, but not on the side facing the material web, preferably in the space between the heating element and the housing is provided with a vacuum which preferably also acts through recesses in the heating modules of the heating element and/or through gaps and/or recesses between adjacent heating modules and between the module and the material web.

The object is also achieved with a packaging machine with a forming station that forms troughs in a base material web, with a heating element heating the base material web before and/or during shaping, and a sealing station that connects a top material web with the base material web and has a heating means for this purpose, wherein it has a forming and/or sealing tool according to one of the preceding claims.

The statements made on this subject matter of the present invention apply equally to the other subjects and vice versa. Features of this subject of the present invention may be incorporated into other subjects and vice versa.

This subject matter of the present invention relates to a packaging machine for producing packaging, in which a base web of material, for example a plastic film, in particular a monofilm or a web of material, which in particular has a layer of cardboard, paper or another layer other than plastic, is unwound from a supply roll and is preferably transported intermittently/cyclically along the packaging machine in a transport plane. In a forming station, this lower web of film is then initially formed by means of a deep-drawing tool in order to For example, to form a trough and/or a structure, in particular an anti-slip structure, in the base web of material. As a rule, the forming station has a lower and an upper tool, which are moved towards one another for forming and away from one another for further transport of the lower web of material. The lower tool is located below and the upper tool above the transport level of the lower web of material. As a rule, in the packaging machine according to the invention, several packages arranged in a so-called format are processed simultaneously and subsequently transported along the packaging machine at the same time. Before and/or during deep-drawing, the web of base material is heated with a heating element. The lower web of material is then covered with packaged goods, in particular foodstuffs such as sausage, ham or cheese, alternatively, for example, non-food packaged goods such as medical technology or other products, and in a next step sealed with a top film in a sealing station, with the Upper film is usually sealed to the lower film web. Another heating element is used for this purpose, which provides the thermal energy required for sealing. The packaging thus finished is then separated by cutting out the packaging from the lower and upper web of material, for example using a cross cutter and a longitudinal cutter. The longitudinal or cross cutter can also be made available as a contour punch. The web of upper material is also unrolled from a supply roll and can also be thermoformed, for example in an upper film forming station, after it has preferably been heated with the heating element according to the invention. In relation to the transport direction of the respective film web, a dancer is preferably located downstream of at least one supply roll, which dancer keeps the tension in the respective material web at least substantially constant. The dancer can be, for example, a linear or a rotary dancer.

The heating element, which heats the material web to be thermoformed, is preferably located upstream of the forming tool(s) of the forming station and/or in the forming station. The heating element can be firmly connected to one tool, for example the upper tool, and/or its frame and can, for example, be moved vertically together with it.

The distance between the mold and the upstream heating element and/or the housing is preferably as small as possible, preferably a few millimeters, preferably 0.5 to 1 mm, on the one hand to save space and material web, on the other hand to cool the material web before molding to reduce or even eliminate, but in particular to be able to heat the material web in the format area directly upstream. Preferably, a heating means/pixel whose longitudinal extension parallel to the transverse extension of the heating element, provided immediately adjacent to the molding station.

The deep-drawn material web is preferably cooled in the forming station. It is particularly preferable for the shape (die) to be cooled, particularly preferably for rapid cooling.

The object is also achieved with a method for heating a material web or for producing packaging from a lower material web and an upper material web, with the inventive or preferred sealing and/or forming tool and/or the inventive or preferred packaging machine, the lower material web and/or the face material web is brought into direct contact with the ceramic modules during heating.

The statements made on this subject matter of the present invention apply equally to the other subjects and vice versa. Features of this subject of the present invention may be incorporated into other subjects and vice versa.

This subject matter of the present invention relates to a method for heating a material web, for example in a packaging machine, in particular in a so-called “form-fill-seal” packaging machine.

The web of material is preferably a plastic film, in particular a so-called monofilm, which is disclosed in detail above.

The method according to the invention ensures that the material web is heated quickly and uniformly within a narrow temperature window.

The material web is preferably heated by means of the heating element by radiation and thermal conduction, but in particular by thermal conduction.

The energy input for heating the material web preferably takes place by means of an energy boost, which begins as soon as the material web touches the modules of the heating element. With an energy boost within the meaning of the invention, at least 40%, preferably at least 50%, even more preferably at least 60% of the heating energy is transferred to the material web within 30% of the heating time. The amount of energy required for this can be made available by an increased amount of energy that is stored in the heating element and/or by an electronic booster.

The booster acts preferably in one and/or two time periods of the heating of the material web and preferably differently therein. In the first period of time, the booster is preferably started together with or when the signal that initiates or starts the advancement of the material web is present, and preferably ends when the lower and upper tools are closed after they have previously been moved towards one another. The second period of time preferably starts at the time when the material web touches the heating element, which preferably starts at the end of the heating of the material web, for example when the ventilation starts and/or the material web detaches from the heating element, shortly before the lower and upper tools open. ends.

During the first period of time, the booster increases the temperature of the heating element, for example from 100°C to 135-137°C, which corresponds for example to the critical film temperature of PP film, or particularly preferably even to 138° or 139°C with some excess heat. The excess heat above the critical film temperature is implemented in order to be able to transfer as much energy as possible into the film without overheating the film. For example, the first time period lasts only about 1-1.5 seconds.

During the second period of time, the booster compensates for the heat dissipation through the material web, which is usually only exposed to ambient temperature before contact, which takes energy from the heated heating element, so that energy also has to be fed into the heating element so that the target temperature in the material web, for example 135 -137°C is reached. The duration of the second period of time depends in particular on the thickness of the material web, with a duration of approx. 1 second per 100 μm thickness of the material web being used as a guide value, ie a duration of approx. 4 seconds is required for a thickness of 400 μm.

A material web, in particular a monofoil, which has a maximum permissible heating temperature is also preferably heated in the preferred method in such a way that the temperature of the heating element is at least temporarily and/or locally higher than the permissible heating temperature of the material web. Preferably, the temperature of at least one module of the heating element is in particular before touching the module and the Material web increases above the maximum permissible temperature of the material web and is preferably lowered when touched, preferably at least temporarily reduced below the maximum permissible temperature of the material web.

The material web is preferably cooled during and/or after forming.

The forming station preferably has cooled deep-drawing molds for this purpose; i.e. the matrix into which the material web is drawn and/or pressed is preferably cooled.

The web of material is preferably a mono-PP or a mono-PE or an A-PET film. The recycled content of the film is preferably <40% by weight, particularly preferably <100% by weight. The recycled content of the film is the proportion that the film contains as recycled material.

The invention is explained below with reference to FIGS. These explanations are merely exemplary and do not limit the general inventive concept. The explanations apply equally to all objects of the present invention.

FIG. 1 schematically shows the packaging machine according to the invention.

Figure 2 shows a detail of the packaging machine

Figure 3 shows a possible configuration of ceramic heating modules

heating element

FIGS. 4-7 show possible widths of the heating element relative to the packaging format to be produced.

FIG. 1 shows the packaging machine 1 according to the invention, which has a forming station 2 , a filling station 7 and a sealing station 15 . The packaging machine can be a so-called thermoformer. A base web 8, here a plastic film 8, in particular a monofilm made of PP, PE, PET or A-PET, is pulled off a supply roll and transported in cycles from right to left along the packaging machine according to the invention. With each cycle, the sub-material web 8 is transported further by one format length/advance length. For this, the packaging machine has two transport means 26 (see FIG. 2), in the present case two endless chains, alternatively for example two toothed belts, which are arranged on the right and left of the base web 8 . At least one gear wheel is provided for each chain both at the beginning and at the end of the packaging machine, around which the respective chain is deflected. At least one of these gears is driven. The gear wheels in the input area and/or in the output area can be connected to one another, preferably by a rigid shaft. Each transport means has a large number of clamping means/grippers 22 which grip the base material web 8 in a clamping manner in the infeed area and transmit the movement of the transport means to the base material web 8 . In the outlet area of the packaging machine, the clamping connection between the transport means and the base material web 8 is released again. A heating element is provided downstream of the inlet area and upstream of the forming station 2, which heats the base material web 8, in particular when the latter is at a standstill. The heating element is a so-called pre-heating from below 25 and/or pre-heating from above 26 . The forming station 2 has a lower tool 4 and an upper tool 3 . As indicated by the double arrow, the lower tool 4 can be moved up and down, being moved upwards in the direction of the lower material web 8 for shaping and downwards for further transport of the lower material web 8 . In the raised position, the web of base material is preferably clamped between the two tools 3, 4. The lower tool 4 can be arranged on a lifting table 5, which, as symbolized by the double arrow, can be vertically adjustable in order to produce the movement of the lower tool described above. In the further course of the packaging machine, the packaging troughs 6 indicated here formed in the base material web or the base material web 8 are then filled with the packaged goods 16 in the filling station 7 . In the subsequent sealing station 15, which also consists of an upper tool 12 and a lower tool 11, which can be vertically adjusted if necessary, an upper film 14 is fixed to the lower web of material 8 by sealing in a materially bonded manner. As a result, the movement of the lower material web 8 is transferred to the upper material web 14 . In the sealing station, too, the upper tool and/or optionally the lower tool are lowered or raised before and after each film transport. The upper film 14 can also be guided in transport means or transported by transport chains, with these transport means then only extending in front of the sealing station and possibly upstream. Otherwise, the statements made regarding the means of transport for the lower film apply. Alternatively, the means of transport for the lower film and/or upper film can only be provided on one side. The top film can also be heated and/or thermoformed with a heating element. For the sealing, a sealing frame is provided as the lower tool 11, for example, which has an opening per packaging trough into which the packaging trough, if any, is inserted during the sealing, ie at the Upward movement of bottom seal tool, dips. For sealing, the upper and lower webs of material are pressed together between the upper and lower tools 12, 11 and bond under the influence of heat and pressure. After sealing, the tools 11, 12 are moved apart again vertically. A dancer, for example a rotary dancer, can be provided between the supply roll of the upper material web 14 and the sealing tool, which keeps the material web 14 at a constant tension as far as possible. The person skilled in the art understands that a dancer is preferably also provided in the area of the base material web 8, preferably downstream of the supply roll. The dancer is preferably a linear dancer. Before and/or during the sealing of the web of upper material to the web of lower material, a gas exchange preferably takes place in each packaging cavity. For this purpose, the air present in the packaging tray is first of all partially sucked off and/or replaced by an exchange gas. For this purpose, holes can be made in the base web 8 in the area of the transport chains in the area of each format, through which the air between the webs 8, 14 is sucked out and/or the exchange gas is blown in. In the further course of the packaging machine, the finished packages are separated, which is done with the cross cutter 18 and the longitudinal cutter 17, for example. In the present case, the cross cutter 18 can also be raised or lowered with a lifting device 9 . According to another embodiment, the sealing tool 11, 12 has a punch that cuts through the lower and upper material web before, during and/or after the sealing. Preferably, several packages are produced at the same time in each cycle, which are arranged in a so-called format as a matrix.

Preferably, the web of base material is heated by a heating element 19 in the forming station and/or upstream thereof and/or the sealing station has a heating element 19 .

This heating element preferably has a large number of ceramic heating modules, against which the material web lies directly during heating. The heating element provides the thermal energy with which the web of material is heated. The heating element can be provided in the form of a plate. A plate in the sense of the invention is not necessarily but preferably a flat two-dimensional object. It can also be curved or have a different 3-dimensional shape. The material web to be heated is preferably in full contact with the heating element.

FIG. 2 shows a view of the packaging machine transversely to the transport direction of the material web 8, which has a width FB and is transported along the packaging machine here by means of two chains 21 (only one shown). are on the chain Means of transport/clamping means 22 are provided, which grip the web in a clamping manner during transport. The transport means 22 are provided at a distance A from one another. The material web is gripped in a width F per edge area. This results in a nominal useful width N of the material web.

The tool that processes the web of material, for example forms it, has an extension W transverse to the transport direction of the web of material. A gap L is generally provided between the tool and the means of transport 22 . With the tool W, packaging or a format of packaging with a width P can be produced transversely to the transport direction of the material web.

FIG. 3 shows a heating element 19 which has a large number of ceramic modules 21, here six, which heat the material web 8, 14 (not shown). In the present case, three modules are provided transversely to the transport direction T of the material web and two modules 21 are provided in the transport direction. In reality, however, there will be significantly more, which depends on the size of the modules and the area to be heated, which is influenced by the number and size of the packaging and the format. In the present case, two rectangular elements are provided in the edge area and one square element in the central area between the two edge elements transversely to the transport direction. In relation to the transverse direction, the edge modules 21 (at the very top and at the very bottom) have a larger or smaller transverse extension BM than the central module (module in the middle). As a result, the overall width B of the modules 21 can be adapted to the useful width of the web of material. Parallel to the transport direction, the length LM of all modules can be the same. Preferably B<N.

FIG. 4 shows a possible tool width W and a possible heating element width B relative to the film width. The width W of the tool and the width B of the ceramic modules is preferably <the usable width N of the material web. The widths W, B are shown here to be the same for the sake of simplicity. Optionally, however, B > W and/or B < FB. Preferably W<=N. When B=W, preferably B<=N.

FIGS. 5-7 each show a format of packaging trays/packaging 6 that can be processed and/or produced with a tool 3, 4, 11, 12. In the present case, it is a 4 x 4 format shown in FIG Packagings. Preferably P<N. An alternative is P=N. P>N is also technically possible. In the variant shown in FIG. 6, P=W=B. The width BM of the modules is selected in such a way that the total is B, with the gaps between the heating modules preferably being taken into account.

In the variant shown in FIG. 7, P<W. B can be equal to W or, preferably, equal to P. Otherwise, reference is made to the comments on FIG.

Reference list:

1 packaging machine

2 forming station, deep-drawing station

3 Upper tool of the deep-drawing station

4 Lower tool of the deep-drawing station

5 lifting table, carrier of a tool for the sealing, deep-drawing station and/or the cutting device

6 packaging tray

7 filling station, insertion station

8 material web, sub-material web

9 lifting device, lift

10 Central area of the heating element

11 Lower tool of the sealing station

12 Sealing station upper die

13 Lower part of the material web clamping means

14 face material web, lid material web

15 sealing station

16 packaged goods

17 longitudinal cutters

18 cross cutters

19 heating element

20 running direction

21 module, heating module, ceramic module

22 Means of transport, grippers, clamping means

23 waste

24 means of transport, chain, toothed belt

25 pre-heating from below

26 Preheating from above

A Distance between the means of transport, useful width of the film between the means of transport

B Dimensions of the modules transverse to the transport direction of the web, useful width of the heater

F Foil gripping width

FB foil width

L Gap width, width of the gap between the means of transport 22 and the tool/lower tool/upper tool N Useful width of foil, nominal

P Usable width of the packaging (overall outer edge)

T Transport direction of the material web

W Usable width of the tool / lower tool / upper tool

BM dimension module, width module

LM dimension module, length module

T Transport direction of the material web

Claims

Patent Claims: 1 . Preheating, sealing or forming tool (3, 12) of a packaging machine with a heating element (19) for heating the packaging material, in particular a monoplastic film, with a large number of ceramic heating modules (21), characterized in that the heating modules have no cover exhibit. 2. pre-heating, sealing or molding tool (3, 12) according to claim 1, characterized in that the heating modules (21) can be controlled individually or as a group with electrical energy. 3. Preheating, sealing or molding tool (3, 12) according to one of claims 1 or 2, characterized in that the heating element is composed of a plurality of heating modules (21) whose surface is partially rectangular and partially square. 4. Preheating, sealing or molding tool (3, 12) according to claim 3, characterized in that the heating modules (31) have a square surface in the central area and the heating modules have a rectangular surface in the edge area of the heating element (19) are provided. 5. preheating, sealing or molding tool (3, 12) according to one of the preceding claims, characterized in that a gap is provided between two heating modules, which is preferably sealed, in particular with an elastic material. 6. preheating, sealing or molding tool (3, 12) according to one of the preceding claims, characterized in that the heating modules have at least some recesses. . Preheating, sealing or forming tool (3, 12) according to one of the preceding claims, characterized in that it has an electronic booster with which an increased energy input into the respective heating element occurs for a short time independently of the target temperature. Packaging machine (1) with a forming station (2) that forms troughs (6) in a base material web (8), a heating element (19) heating the base material web (8) before and/or during shaping, and a sealing station that forms a top material web (14) to the base material web (8) and has heating means (19) for this, characterized in that it has a forming and/or sealing tool according to one of the preceding claims. Packaging machine (1) according to Claim 8, with transport means (22) which transport the base material web in a transport direction (T), the transport means being provided at a distance (A) transversely to the transport direction (T), characterized in that the extent ( B) of the heating means (19) transversely to the transport direction (T) < than the distance (A). Method for heating a web of material or for producing packaging from a web of lower material (8) and a web of upper material (14), with a sealing or forming tool according to one of Claims 1 - 6 and/or a packaging machine according to one of Claims 7 or 8, characterized in that that the lower material web (8) and/or the upper material web (14) is brought into direct contact with the ceramic heating modules (21) during heating. Method according to Claim 10, characterized in that the lower material web (8) and/or the upper material web (14) is sucked onto the ceramic modules for heating. Method according to one of Claims 10 or 11, characterized in that the web of material is a mono-PP or a mono-PE or an A-PET film. Method according to Claim 12, characterized in that the recycled content of the film is <100% by weight.