Method and apparatus for the continuous production of thermoplastic sheets

The invention relates to a method for the continuous production of thermoplastic plastic webs according to the preamble of claim 1 and an apparatus for performing this method according to the preamble of claim 24th

Semi-finished products made of thermoplastic material, such as plates, sheets, strips, etc., are predominantly produced by extrusion. In the die of the extruder directed the macromolecules of the polymer melt due to the acting external forces in a preferred direction corresponding to the flow direction out. This orientation freezes at the rapid cooling after leaving the nozzle a, which leads to internal stresses of the semifinished product. furthermore perform such orientations, amplified by vortex the basis of Sectional associations in the nozzle occur, often to melt fracture, wherein the plastic melt then a stick-slip phenomenon from the nozzle emerges, resulting in a rough surface of the semifinished product. A reworking the surface of the extrudate after leaving the die of the Extruder is necessary.

Known production lines for extruded sheets or films consist of thermoplastics from an extruder with a nozzle, a subsequent smoothing and calibrating unit, a cooling device, a Deduction for the plastic sheet and means for cutting the plastic sheet, Stacking the panels, etc. The result of the rough surface of the extrudate necessary reworking is carried out in the calibrating unit. such a Calibrating unit is usually from several rolls with highly polished Surfaces of existing calenders. The calender causes cooling the extrusion taking utmost elimination of thickness variations and a smoothing of the surface of the plastic web. Here, the calender must so be adjusted so that only a smoothing of the surface, but not a occurs deformation of the entire web, since then additional non-symmetric Residual stresses occur, discarding the train to be draws.

A disadvantage of the use of the calender for smoothing and calibration of the extrudate, therefore, is that so that although a certain smoothing of the surface can be achieved, however, it is not possible, already in the web eliminate by extruding existing residual stresses. There is even the danger still incorporate other additional stresses. In the area of ​​the rollers of the calender, a bending of the plastic web is carried out around these rolls, so that the web must be in the thermoelastic state, thus also the temperature of the rolls must be kept relatively high, so that only a limited cooling in the region of the rollers. These therefore cooling takes place especially during the plastic sheet, the cooling rolls of the calender wraps, is so bent, thus form error of the aspired level, low-stress plastic sheet is. The subsequent further cooling in the subsequent cooling unit is then depressurized. But acts also during the passage of the plastic web through the calender Only one brief line pressure on the cooling path so that total during the entire cooling of the plastic sheet for a short time applied pressure and thus the previously obtained properties of the surface the plastic sheet still far from ideally aspired state are.

From AT-PS 3 74 738 a method and apparatus for producing style of hollow profile strips or sheets of plastic. at this method is extruded a plastics belt by means of an extruder and then introduced into a calibration device. The calibration device consists of two stacked, stationary blocks, between which the plastic strip. These blocks have channels, flows through the cooling water to the plastic strip in the calibration cool.

If the plastic tape in a continuous run in the calibration cooled so enters a relative speed between the plastic tape and the surfaces of the blocks because the blocks arranged in a fixed are. On the other hand, cooling of the plastic tape only can take place when the plastic strip touches the surface of the blocks, in turn creates a friction between the surfaces of the plastic tape and the blocks, so that the plastic web during the cooling of a rough, poor quality surface receives.

Using the calibration device can be at most a minimal Surface pressure on the sliding along the surfaces of the blocks Plastic band exercise. With such a minimal surface pressure, the are not calibrated plastic strip on a narrow thickness tolerance and originating from the extrusion residual stresses can also only be very slightly reduced. For the production of high quality Thermoplastic webs is by this method and the device therefore not suitable.

The DE-AS 17 29 076 shows a method and an apparatus for producing a continuous foam strand by extrusion. A foamable Plastic mixture is pressed through an extruder with inner mandrel, at the nozzle outlet is located a calibration device. This calibration is located as a tubular sleeve with a circumferentially Shell space formed. For controlling the temperature of the calibrating a liquid circulated through the jacket space of the sleeve, so that the calibration device to a temperature below the solidification temperature the plastic mixture is maintained.

The foam strand slides on the fixed inner surface of the calibration along, with which between the surface of the foam strand and the inner surface of the calibrating a sliding friction, so that the surface of the foam strand and rough torn becomes. In the calibration device is at most a lower pressure on the Foam strand exercised. Thus, the results described in this Auslegeschrift The method also to thermoplastic webs of inferior quality.

In DE-OS 33 43 981 a double belt press is arranged with two superimposed, described endless press bands that for, among other pressing serving of elastomers and plastics. To transmit the pressing pressure of the pressure plate on the inside of the press belt are continuously circulating, containing a plurality of pressure rollers trolley arranged in the double belt press.

This publication shows a known double belt press, are However, no suggestion to cool a thermoplastic sheet under surface pressure. Thus, in the double belt press also no means for removal of heat to find from the plastic web through the press belt on the printing plates. Another disadvantage are the circulating trolley, which increased a require constructive effort to lead and the risk of severe salvage equipment damage in itself, if running or tilting a such trolley enters. Thus, the one shown in the publication Double belt press is not designed as a calibration and smoothing and for the production of thermoplastic webs with improved surfaces and reduced residual stresses unsuitable.

Other methods and devices are currently known from the prior art, with whom it but also not succeed, thermoplastic webs with improved surface quality produce.

Thus, the CH-PS showed 5 56 737 a method and several devices for producing of extruded profiles made of expandable thermoplastic Plastics. The devices consist of an extrusion press with a nozzle, a following-cooled, forming the mouthpiece for the plastic strand and one located behind water to cool the Plastic strand. The foamable plastic is formed by the nozzle Plodder extruded so that at the inlet of the forming die by expansion of the plastic forms a bead.

Between the surface of the plastic strand and the shaping mouthpiece occurs here again on a sliding friction. This results in a rough Surface of the plastic strand. This can also use this method and with the device produced no high-quality thermoplastic webs will.

GB-A-21 46 941 shows a first extruder for extruding foamed Thermoplastic material. Directly behind the outlet of the first Extruder, a second extruder is arranged, which a film of non-porous Thermoplastic material on at least one side of the foamed plastic body applies. It is followed by cooled rollers which foamed the Thermoplastic layer with the non-porous thermoplastic film compress.

The rolls exert a pressure line and no surface pressure on the two Thermoplastic sheets of. This results in a poor bond between the two thermoplastic webs. A further disadvantage is that the surface of the pressed can be thermoplastic web wavy and additional stresses can be introduced into the thermoplastic web.

The DE-AS 22 52 219 relates to a method and an apparatus for producing of thin-walled moldings of thermoplastic material. The thermoplastic Plastic is extruded through an extruder into a tape. The surface of this volume is between downstream of the extruder plurality of cooling rolls to cool.

From the cooling rolls is only a short acting line pressure and no surface pressure exerted. This in turn leads to an undulating surface and additional stresses in the thermoplastic web.

Starting from this prior art, the invention has the object, a method and an apparatus for the continuous production extruded plastic webs of thermoplastic material, in particular for further processing into plates or foils, to specify with which both an improved quality of the surface of the plastic web as well as reduced Stresses the same can be reached.

This object is in the characterizing part of claim 1 in conjunction with the preamble mediated technical teaching and for the implementation of this Process serving device is in the preamble and in the characterizing part of claim 24 indicated.

The advantages attainable with the invention consist in particular in that the pressure areally without sliding friction during the entire cooling time on the extruded plastic web in the flat position, in which also the should apply and finished product, applied. This results in an excellent Surface of the plastic sheet of yet not known before Quality. Since the web is not subjected to bending stress during cooling, but perfectly level remains, no further internal stresses in the Bahn arise. Rather, it has been found that by extruding inevitably resulting residual stresses with the aid of the invention Process can be reduced largely. The rate of cooling of the Plastic sheet may advantageously to the requirements of the microstructure the respective thermoplastics be adapted. The inventive method therefore, causes a significant improvement in the properties of extruded Plastic sheets of thermoplastic material.

A preferred embodiment of the invention will in more detail below described. It shows

<b>Fig.</b> 1 is a general view of a production plant for the continuous Producing a plate-like or sheet-like extrudate

<b>Fig.</b> 2 a section through a double belt press with upstream extruder,

<b>Fig.</b> 3 a pressure plate in plan view,

<b>Fig.</b> 4 a section through the pressure plate along the line <i>AA</i> in <b>Fig.</b> 3,

<b>Fig.</b> 5 shows a device for the continuous coating of substrate webs,

<b>Fig.</b> 6 shows an enlarged detail of the inlet zone in a device for two-sided coating of carrier webs,

<b>Fig.</b> 7, the inlet zone of a double belt press,

<b>Fig.</b> 8 shows a device for welding a plurality of extruded thermoplastic webs,

<b>Fig.</b> 9 the inlet zone a double belt press with heated reversing drums and

<b>Fig.</b> 10 the inlet zone a double belt press with projecting lower Tape unit.

In <b>Fig.</b> 1 is a production plant for continuous production schematically represented by thermoplastic sheet and film. they consists of a double band press <b>1</b>Before running things, an extruder <b>2</b> is. The out of the nozzle<b>3</b> the extruder <b>2</b> exiting thermoplastic web <b>4</b> in the form of plastic melt according to the invention A method in the double belt press <b>1</b> introduced and in this Action of surface pressure cooled enough that the plastic melt after leaving the double band press <b>1</b> to a solid Plastic sheet <b>5</b> with a smooth and polished or embossed is formed. This plastic sheet<b>5</b> runs with uniform Speed ​​to a cross cutting unit <b>6</b>Where they in plates <b>7</b> any size is split in pallets <b>8th</b> for transportation are stacked. Alternatively, the plastic sheet<b>5</b>If it is a thin, flexible plastic sheet or a film is, on a role <b>12</b> in a winding <b>11</b> after leaving the double band press <b>1</b> be wound. Is the Role<b>12</b> filled, so can not Interruption in production the plastic sheet <b>5 </b>to a substitute role <b>13</b> be wound up. The entire production line is of a computer in a control cabinet <b>9</b> controlled. Data input performed by the user via the terminal <b>14</b>,

The <b>Fig.</b> 2 shows the extruder <b>2</b> with downstream double belt press <b>1</b> schematically in section. The known as trained extruder<b>2</b> has an elongated cylinder <b>19</b>In which a motor- <b>16</b> via a reduction <b>17</b> driven screw <b>18</b> is. The snail <b>18</b> takes in its rear part in their helical wells <b>20</b> the granules <b>14</b> for the processed thermoplastic Plastic on that in a hopper <b>15</b> the extruder <b>2</b> filled becomes. These granules with the worm<b>18</b> transported and during this transport melted. These are at the cylinder <b>19</b> more heating jackets <b>21</b> placed. At the front end of the slug <b>18</b> the plastic melt is homogenized and densified and passes through the nozzle <b>2</b> of the front part of the cylinder <b>19</b> flanged extruder tool <b>22</b> out. The nozzle<b>23</b> the extruder tool <b>22</b> are the emerging, hot plastic melt <b>4</b> the Cross-sectional shape. The nozzle<b>23</b> is designed as a slot die, so that a flat, web-shaped plastic melt <b>4</b> with the substantially rectangular cross section is replaced.

The plastic melt <b>4</b> occurs as a present on processing temperature, viscoelastic web from the nozzle <b>23</b> the extruder <b>2</b> out, is of the bands of the double band press <b>1</b> was added and in the inlet zone <b>61</b> the double band press <b>1</b> introduced. The continuously dual belt press <b>1</b> is in <b>Fig.</b> 2 is also shown in section. It owns four mounted in a press frame deflection drums <b>24, 25, 26, 27</b>, The press frame is in the drawing of clarity, Half omitted. To two of the horizontal on a Plane lying idlers, which according to the Arrows in the guide drums <b>24</b> and <b>25</b> turn, is an endless, from Metal existing press belt <b>28, 29</b> round out the means of hydraulic cylinders <b>30</b> is tensioned. Between the two pressing belts<b>28, 29</b>, In the reaction zone <b>62</b>, Is selected from the plastic melt <b>4</b> existing in the drawing from right to left leading web cooled surface pressure.

The on the plastic melt <b>4</b> applied surface pressure is on printing plates <b>31, 32</b> hydraulically or mechanically to the inner sides the press bands <b>28, 29</b> applied and from there to the plastic melt <b>4</b> transfer. For hydraulic pressure transmission is in the room <b>33</b>, The up and down of the pressure plate <b>31</b> or. the inside of the press belt <b>28</b> and to the sides of the seal <b>34</b> limited is introduced under pressure, a settable, fluid pressure medium, so that the space <b>33</b> acts as a pressure pad. As fluid pressure medium For example, oil or air is used. The structure of the along the edge of the printing plate <b>31</b> Rectangular closed sealing <b>34</b> is in <b>Fig.</b> 4 to see. It consists of a U-shaped retaining strip <b>35</b> made of metal, in which the elastic sealing body <b>36</b> is clamped. The U-shaped retaining strip<b>35</b> located in a groove <b>38</b> along the edge of the printing plate <b>31</b>, On the retaining strip<b>35</b> is the groove base to an O-ring <b>37</b>To which the groove bottom here acts a pressure medium, so that the sealing body <b>36</b> against the Inside the press belt <b>28</b> is pressed and the room <b>33</b> to the Pages seals out.

To the plastic melt <b>4</b> to the desired final temperature at the Leaving the double belt press <b>1</b> To cool down, the printing plates <b>31, 32</b> maintained at a temperature that much ge lower than the final temperature to be reached of the polymer melt <b>4</b> is. For this purpose, in the printing plates<b>31, 32</b> channels <b>40</b> attached as also the <b>Fig.</b> refer. 4 These channels<b>40</b> be of a cooling liquid flows through, which absorbs the heat and discharges and thus the target temperature of the printing plate <b>31</b> on the ge maintains desired low level. Of course, the Küh ment of the printing plate and electrically, for example by Peltier Elements can take place.

In the printing plate <b>31</b> located transversely to the direction of press belt <b>28</b> Inappropriate, rei across the width of the printing plate sponding grooves <b>41</b>Such as from <b>Fig.</b> 3 and 4 is visible. In this Nu th <b>41</b> are rod-shaped heat-conducting elements <b>39</b> used. These thermally conductive elements <b>39</b> made of copper and are Ausbil tion of a good Wärmeleitkontaktes one hand with the pressure plate <b>31</b> connected and touching the other hand, the inside of Preßban of <b>28</b> grinding. The groove bottom of the groove<b>41</b> to lying on the heat conductive elements <b>39</b> an elastomeric seal <b>42</b> on which the groove basic forth is acted upon by a pressure medium, so that that would be meleitende element <b>39</b> always contact with the press belt <b>28</b> owns.

As between the pressure plate <b>31</b> and the plastic melt <b>4</b> heat gradient exists, is a heat flow of the plastic melt <b>4</b> on the press belt <b>28</b> and the heat conductive members <b>39</b> in the pressure plate <b>31</b> a, so that the plastic melt during the passage is cooled continuously through the double belt press. The Geschwin speed of cooling of the molten plastic <b>4</b> depends on the Temperature level of the printing plate <b>31</b> and the number of the thermally conductive elements <b>39</b>, As well as their thermal conductivities from. The achievable Final temperature of the plastic melt <b>4</b> can continue on the Speed ​​of the press bands <b>28, 29</b> regulate in the double belt press. Of course, the pressure plate <b>32</b> also as the pressure plate <b>31</b> be formed and thermally conductive elements <b>39</b> contain, in which case the cooling speed is doubled. More Ma materials and training forms for such heat-conducting elements are described in the published patent application DE-OS 33 25 578, so that to be then no longer be discussed needs.

Instead of the hydraulic pressure transmission in the Doppelbandpres se <b>1</b> can also be a mechanical pressure transfer can be provided, their training in <b>Fig.</b> 2 with reference to the printing plate <b>32</b> explains who the should. Between the pressure plate<b>32</b> and the inside of the press belt <b>29</b> are fixed, consisting of metal rolls <b>43</b> appropriate. with the help of hydraulic cylinders <b>44</b> is the pressure plate <b>32</b> and thus the Rol len <b>43</b> against the inside of the press belt <b>29</b> made so that characterized the desired pressure is exerted on the plastic web. The pressure plate <b>32 </b>is also, as already described further above ben, cooled. This is a heat flow of the plastic melt<b>4</b> on the press belt <b>29</b> and the rollers <b>43</b> in the printing plate <b>32</b> on and the plastic melt <b>4</b> is up to the desired temperature from cooled. If the size of the heat flow over the rollers<b>43</b> not sufficient, additional heat-conducting elements <b>39</b>That as are formed as described above, mounted between the rollers will. If it is desired, in an inventive Device, the mechanical with hydraulic Druckübertra transmission are combined using heat-conducting elements.

The plastic melt <b>4</b> So, after leaving the extruder <b>2</b> on a press belt <b>29</b> or <b>28</b> the double band press in the field of front idlers <b>24, 25</b> launched and of the press belt in promoted the double belt press, or right in the middle of the gap between the two guide drums <b>24, 25</b> in the inlet zone <b>61</b> extruded, so that the plastic melt <b>4</b> by both pressing bands <b>28, 29</b> is detected simultaneously. While the art material melt <b>4</b> continuously through the double belt press <b>1</b> Gezo gene is thus the double belt press <b>1</b> simultaneously as Abzugsein acting direction of the extrudate, it is at the same time a effect of surface pressure cooled. The applied surface pressure acts the calibration of the thermoplastic plastic web a confers certain thickness and a certain surface structure. By the act uniformly and areally during cooling the pressure is obtained, has been found to advantageously a Elimination of existing orientations of Kunststoffmole molecules and the related, originating from the extruding own voltages, so that extruded with the inventive process Plastic sheets or films of not unprecedented Quali are ity produced.

The surface structure of the double belt press <b>1</b> leaving Art material web <b>5</b> depends within wide limits of the surfaces of the press bands <b>28, 29</b> from. Have the press belts have a smooth surface, so the surface of the plastic sheet is replaced by a smooth, polished Appearance, that is, the plastic web <b>5</b> is in the double belt press <b>1</b> preßpoliert. This effect can be enhanced by the surface of the pressing belts with a high-gloss, galvanically deposited chromium layer provides. Possess the press bands a struktuierte surface, for example knobs, corrugations, Orna mente, random structures, and so on, so get the plastic sheet <b>5</b> into the surface embossed image of that pattern. It is also possible to structure the carrier web, the z. B. from a metal foil with structured surface consists, prior to the double belt press as with the to let converge plastic melt that nichtstrukturier te surface of the structure support web on a press belt of double belt press rests and the structured surface of Strukturträ gerbahn on the plastic melt, in which case under the surfaces pressure in the double belt press the structuring of the support structure imprinted in the plastic sheet. On leaving the double band press at the idlers <b>26</b> and <b>27</b> is the structural support then from the Plastic sheet <b>5</b> separated.

Some thermoplastics may a slowdown in require several stages. For this, the printing plates are<b>31, 32</b> the double band press <b>1</b> in several consecutive preparation che divided, required for the different target temperatures are cooled. Each of these is with thermally conductive elements <b>39</b> provided so that the Reaktionszo ne <b>62</b> decreasing temperatures possesses. The plastic melt<b>4</b> then it passes through the reaction zone <b>62</b> in the double belt press <b>1</b> sequentially abge to the different temperatures cools. If required by the plastic melt, can also between rule two areas in the printing plate with heat are provided conductive elements, an area without heat conduct be provided de elements. In the reaction zone<b>62</b> then follows a cooling section each have a track where the Zwischentem temperature is maintained, so that a stepped cooling the Plastic melt occurs. This training may also Cooling the optimal by the microstructure of the Plastic melt-related needs to be adapted. As essential to the invention, however, be emphasized that in the reac tion zone a cooling below surface pressing any Final temperature occurs.

It is also within the scope of the invention the inlet side Umlenktrom drums <b>24</b> and <b>25</b> heat it to an appropriate temperature. at for example, such a temperature between the final temperature the plastic web <b>5</b> on leaving the double band press <b>1</b> and the Temperature of the plastic melt <b>4</b> when leaving the extruder <b>2</b> lie. As in<b>Fig.</b> 9 shown, have the idlers <b>24, 25</b> in the cylinder casing <b>64</b> across the width of the deflecting drums <b>24, 25</b> rei sponding channels <b>63</b>, These channels<b>63</b> be a heat carrier flows through oil that gives off heat to the tail pulleys from where from the press bands <b>28, 29</b> by conduction also he be warmed. The press belts<b>24</b> and <b>25</b> then have also this increased temperature, and the plastic melt <b>4</b> remains in the inlet zone <b>61</b> the double band press <b>1</b> in viscoelastic to was standing. This can advantageously be the residual stresses of Plastic sheet <b>5</b> further reduce their dimensional accuracy and stei gladly. In the field of printing plates<b>31, 32</b> the plastic web is then together with the pressing belts <b>28, 29</b> cooled. It may also conveniently be moderate, einzu the printing plates in a heating and cooling area share, said the inlet side idlers <b>24, 25</b> facing Field is heated to an appropriate temperature and thus on the heat conductive members <b>39</b> the plastic melt <b>4</b> Next he warms. This may be as a substitute for the heating of the inlet-side Idlers or support the same happened. Important This is particularly in the following exemplary embodiment, where multiple extruded thermoplastic webs are welded together. Of the the outlet side idlers <b>26, 27</b> facing the area reaction zone <b>62</b> is then again, as explained above, as Kühlzo ne formed.

In the extrusion of the plastic melt <b>4</b> , as in <b>Fig.</b> 7 ge shows, to work with some excess, so that the The inlet of the double-belt press in front of the reversing drums <b>24</b> and <b>25</b> a bead <b>53</b> forms pent plastic melt. In order to is advantageously prevented that air with the melt in the reaction zone <b>62</b> penetrates and defective plastic sheet produced with pores. Advantageously, the extrusion of the quantity the plastic melt <b>4</b> also depending on the size the bead <b>53</b> be managed. Thus, during the GESAM th processing duration reaches uniform conditions. Around also by extruding the plastic melt already to drive out dissolved air that can inlet side idlers <b>24, 25</b> in direction of arrow <b>54</b> toward adjustable its bar, which means an additional calendering the molten plastic <b>4</b> and leakage of the air against the flow direction of art material melt causes. The calendering of the plastic melt<b>4</b> in the inlet zone <b>61</b> by controlling the roll gap can also important be to trainees a volume contraction of the cooling melt same and so the dimensional stability of the plastic web <b>5</b> to be granted afford. The formation of the inlet-side deflection drums of Double belt press of calendering is known per se and can carried out by the published patent application DE-OS 34 02 751st

Another operating according to the inventive method before direction, which for the production of plastic coated carrier tracks <b>48</b> serving in <b>Fig.</b> 5 is shown. This device has a extruder <b>2</b> with a slot die <b>23</b> and a double belt press <b>1</b>, Before the double-belt press <b>1</b> is in the vicinity of the tail pulley <b>25</b> a role <b>46</b> attached, referring to a well-known, in the drawing Unwinding unit is not shown. From the roll<b>46</b> becomes a carrier web <b>47</b>, For example, from a paper, metal, or Tissue may be made, handled and in the inlet zone <b>61</b> the Dop pelbandpresse <b>1</b> with the plastic melt <b>4</b> from the extruder <b>2</b> to sammengeführt. It is also possible that the carrier web<b>47</b> out a scattered nonwoven is. If necessary, the carrier train <b>47</b> between the roller <b>46</b> and the inlet into the double belt press be preheated by means of an infrared lamp heater or hot air. When passing the plastic melt <b>4</b> on the carrier web <b>47</b> by the reaction zone <b>62</b> the plastic melt <b>4</b> under surface pressure cooled, and goes to the carrier web <b>47</b> a composite one. After this Leaving the double belt press <b>1</b> , the coated backing web <b>48</b> on a roll in a winding unit, as described in <b>Fig.</b> 1 is shown, be wound.

The production of a two-side coated with plastic carrier track is in <b>Fig.</b> 6 where the inlet zone <b>61</b> the double band press <b>1</b> is shown enlarged. In the vicinity of the upper deflection drum<b>24</b> is an upper extruder <b>49</b> mounted, art a material melt <b>50</b> on the press band <b>28</b> extruded. This hot art material melt <b>50</b> adheres to the press belt <b>28</b> and from this into the Laminator <b>1</b> transported. A lower extruder<b>45</b> is in close to the lower deflection drum <b>25</b> mounted and extruded a plastic melt <b>51</b> on the press band <b>29</b>So that this art material melt <b>51</b> also in the double belt press <b>1</b> transported becomes. A drawn from a roller support web<b>52</b> running between the two plastic melts <b>50</b> and <b>51</b> on the double belt press <b>1</b> to and is in the inlet zone <b>61</b> with the plastic melts <b>50, 51</b> brought together such that on each surface of the carrier web <b>52</b> a plastic melt is. In the reaction zone<b>62</b> of the Laminator <b>1</b> is the double-coated carrier web then cooled again under pressure area.

In the <b>Fig.</b> 2 device shown is also suitable for incorporation fillers into the plastic web <b>5</b>, Such as glass or metal fibers. For this purpose, between the extruder tool <b>22</b> and the inlet side Umlenktrommel <b>24</b> a spreading device for the fibers attached. This scatterer scatters the corresponding fibers in the art material melt <b>4</b>Which then so far from sinking into the melt that they are enclosed by the thermoplastic plastics material. Art material melt <b>4</b> with the embedded fibers is then, as previously described above, in the double belt press <b>1</b> a filler with reinforced plastic sheet <b>5</b> cooled.

A further apparatus for carrying out the inventive KISSING procedure is in <b>Fig.</b> 8, respectively. This apparatus is used for Welding individual thermoplastic plastic webs or films into a compact plastic sheet. The individual art can substrate webs from conventionally extruded and calendaring th thermoplastic films are made, which until further processing were stored on rolls. Before the double-belt press<b>1</b> are uncoiling <b>55, 56</b> established in which roles <b>57</b> and <b>58</b> located on thermoplastic films. These individual thermoplastic films are from the rolls <b>57, 58</b> withdrawn, before the twin-belt press <b>1</b> to a laminated thermoplastic web <b>59</b> merged and in the Laminator <b>1</b> introduced. For each role<b>57, 58</b> He is a set role <b>57</b><i>a</i>. <b>58</b><i>a</i> provided so that at the end of a roll, the Pro production by threading of the corresponding replacement roll without lower refraction can be maintained. If necessary, before the double belt press <b>1</b> an infrared radiator heating for preheating of the laminated thermoplastic web <b>59</b> or at the individual thermoplastic films be accommodated.

To the individual thermoplastic sheets together to weld can, they must first be heated in the inlet zone applicable be until they are in the viscoelastic state. These are the inlet-side deflection drums of the double belt press <b>1</b>As further above with reference to <b>Fig.</b> described 9, heated, so that the individual Films in contact with the pressing belts <b>28, 29</b> are heated. If this is not sufficient, then the inlet-side area the reaction zone by means of a heat-conducting elements of the pressure plate ago now also heated, as described in detail above is described. Once the films have a viscoelastic to was to have appropriate temperature, weld the single NEN films under the surface pressure in the reaction zone miteinan of a compact car.

During the further passage through the reaction zone of the double belt press <b>1</b> is this layered, welded thermoplastic web <b>59</b> corre cording to the method of the invention in the reaction zone under Surface pressure cooled. For this, the pressure plate is in the double band press again with thermally conductive elements according to the <b>Fig.</b> 3 and 4 are provided and at least of the outlet side Umlenktrom drums region facing the pressure plate is cooled. If neces sary the printing plate can also again in individual areas be different temperatures divided or stufenför allow Miges cooling. At the outlet of the double belt press<b>1</b> he keeps you a cooled, compact plastic sheet <b>60</b> of thermoplastic plastic material, which, as in <b>Fig.</b> 1 shown, wound can be divided or in individual plates.

Also possible is a calendering the laminated thermoplastic web <b>59 </b>by means of the inlet-side deflection drum, according to the <b>Fig.</b> . 7 If desired, with the various thermoplastic films for ampli kung also a fabric sheet of glass cloth, textile fabric, etc. run, so as to lead to a reinforced thermoplastic sheet. Although the individual thermoplastic films or sheets on the to roll <b>57, 58</b> are conventional extruded and calendered, is be emphasized that the compact plastic web <b>60</b>In which the Films are welded together, the inventive ago parts, such as reduced residual stress, a preßpolierte Oberflä che, good dimensional stability, etc. has.

In <b>Fig.</b> 10 is an embodiment of the invention proceedings procedure shown in which extruded thermoplastic flakes to a thermoplastic web are processed. The lower band unit<b>65</b> the double belt press <b>1</b> is slightly forward, so that the lower press belt <b>66</b> something out of the inlet zone <b>61</b> is protruding. Shortly before the inlet zone<b>61</b>, Over the press belt <b>66</b>, Is a spreading device <b>67</b> appropriate, the extruded thermoplastic flakes <b>68</b> to the lower press belt <b>66</b> scattered into a fleece. This web is the press belt<b>66</b> in the inlet zone <b>61</b> transported, where it is compacted and heated until As already explained above, that there is a cohesive, viscoelastic thermoplastic web <b>69</b> forms. Then the white direct passage through the double belt press <b>1</b> the thermoplastic web <b>69</b> then cooled again under pressure area. It is also here turn calendering the web scattered by the incoming side tail pulley <b>24</b> possible. If desired, also Nonwoven fabric in the double track Press <b>1</b> shrinks and the extruded Thermoplastic flakes or powder can as described before A running zone <b>61</b> are interspersed in this nonwoven fabric. The already ge Advantages mentioned invention of the cooled plastic ground are also present in this embodiment again.

In the above description are wide end Ausführungsbeispie le for devices for implementing the View according to the invention procedure described. What is important in all these Ausführungsfor Men in that the thermoplastic material under pressure from surface is cooled, to which the inventive devices with a Double belt press with heat-conducting elements in the printing plate feature.