SE434817B - PROCEDURE AND DEVICE FOR MANUFACTURING CORRUGATED PLASTIC BOARD MATERIAL - Google Patents

Description

7906139-6 2 heat-exchanging calibration device, The material ;. which leaves the device, is cut to width and possibly lengthwise to sheets of desired size.

Known plants for cooling corrugated plastic cardboard material consist of two steel blocks placed parallel to each other with a distance between the blocks corresponding to the desired thickness of the material. Each block has parallel bores arranged perpendicular to the feed direction of the material, through some of the channels a cooling medium, eg water, and the rest of the ducts are connected via small holes to the space between the blocks and connected to a vacuum source. The corrugated material passes between both blocks and through the contact with the surfaces of the blocks it is cooled and the thickness is determined.

Corrugated plastic cardboard material must meet a number of basic requirements in order to be used industrially. It must therefore be sufficiently flat and devoid of warping and cheap enough to be able to compete with corrugated board made of pulp. Corrugated materials made according to the prior art of such relatively inexpensive plastics as polyolefins, in particular polypropylene and polyethylene, unfortunately have several disadvantages. This includes in particular that they have a tendency to swell, with time exhibiting skewed edges and a considerable variation in thickness along the entire length. The object of the invention was therefore to try to produce corrugated plastic cardboard materials, in particular of crystallizable polyolefins such as polypropylene and polyethylene, which do not have the said disadvantages, and a device for carrying out this process.

The method and the device according to the invention make it possible to produce corrugated plastic cardboard materials, in particular from polyolefins, which are stable for extended storage time in order to avoid stress and the formation of skewed edges.

The method according to the invention is characterized in that the cardboard material cools more intensively in its central portion than in its outer areas and less intensively at the inlet end of the calibration device than in its outlet end and that the carton material is then subjected to reheating in a tunnel at a temperature of between 40 ° C. 120 ° C, whereby the carton material is reheated less intensively in its central part than in the outer areas and more intensively in the central zone of the tunnel than in zones closest to the inlet and discharge ends of the tunnel. The scope of the invention is apparent from the following claims.

When applying the method according to the invention, it is provided that plastic materials, in particular polyolefins such as polypropylene or polyethylene, are heated and sprayed through a spray head provided with a nozzle consisting of a series of separate cores, the shape of which determines the shape of the channels of the material being sprayed. the ducts of the material, compressed air is pumped in through holes made in the cores of the spray nozzle. The sprayed material length is fed between two cooling surfaces in a heat-exchanging calibration device and cools down more intensively in the middle part than in the outer areas and more intensively when the material length exits the device than when it enters it. After leaving the calibration device, the material length remains at ambient temperature until the temperatures at each point of the cross section have been evened out. Thereafter, the material length is subjected to a reheating to a temperature of 40-120 ° C in a suitable tunnel. whereby the reheating is carried out in such a way that the length is reheated less intensively in the central part than in the outer areas and more intensively in the central zone of the tunnel than in the zones closest to the inlet and discharge ends of the tunnel.

The temperature of the surface of the cardboard material in its central part is preferably 15-40 ° C lower than the outer areas and 1-40 ° C higher in the central zone of the tunnel than in zones closest to the inlet and discharge ends of the tunnel.

The corrugated plastic cardboard material, in particular of polyolefins, manufactured in accordance with the process according to the invention is characterized by a low deviation from the basis weight across and along the material length and amounting to 3% of the average value. Furthermore, the length of material is completely flat and shows no tendency to warp during or after prolonged storage. The device according to the invention comprises an extruder, an extruder nozzle having a series of separate cores, the shape of which determines the shape of the channels in the carton material. heat-exchanging calibration device for cooling the hot, sprayed material from the nozzle and two sets of transport rollers and is characterized in that it contains a reheating device for reheating the cooled sprayed material from the heat-exchanging calibration device, the heat-exchanging device at a distance of at least three times the length of the calibration device, so that the cooled, sprayed material can be exposed to ambient air, the calibration device comprising a pair of spaced apart opposing blocks, between to which the hot, sprayed material passes, each block having continuous passages having coolant-comprising central, longitudinal channels with inlet openings on the downstream side, transverse channels emanating from the central, longitudinal channels and outer, longitudinal collection channel connected to the side side members and having an outlet opening at the upstream end, that the opposite blocks have vacuum chambers and vacuum passages extending from the vacuum chambers to opposite sides of the block, that the reheating device comprises a pair of opposite compartments, which delimit a gutter-like tunnel for material through them. on transverse rows of infrared lamps in the spaces, the transverse rows of lamps in each compartment forming longitudinal, continuous, central, intermediate and outer series of lamps and the lamps in the outer series are stronger than the lamps in the intermediate series , which in turn are stronger than the lamps in the central series, and that each row of lamps has an individual system for power supply, which is adjustable to be able to vary the current intensity.

The working surfaces of the device are formed by the surfaces of the two blocks facing each other. Opposite opposite surfaces of the blocks are flat iron and plates are welded and form two chambers. In the blocks between the chambers, a number of holes are made, which connect the working space of the device to the chambers, which in turn are connected to a vacuum pump.

The reheating device used according to the invention has, for example, the shape of a flat retangular prism made of plates 7906139-6 provided with narrow, elongate openings in both front walls. The plane bounded by these openings divides the interior of the tunnel into two parts. At the bottom of each such part, flat infrared lamps are mounted in rows perpendicular to the longitudinal axis of the device, lamps with the same position in the rows forming series; which runs parallel to the longitudinal axis of the device. The infrared lamps in the outer horizontal series have the highest power, while those in the centrally located series have the lowest power. The infrared lamps placed in the same row have a common power supply with unlimited variable control of the current intensity.

The device according to the invention is illustrated in more detail below in connection with the accompanying drawing figures. Fig. 1 shows the device according to the invention for stabilizing corrugated plastic cardboard materials comprising the calibration device 1, transport rollers 2 and 3 and the reheating device 4. Fig. Shows in perspective the calibration device. Fig. 3 is a cross-section of the bottom unit of the calibration device in a plane parallel to its working surface. Fig. 4 shows a section of the bottom unit of the calibration device along the line A-A in Fig. 3. Fig. 5 shows the reheating device with a subsection of its upper part. U The distance between the calibration device 1 and the reheating device 4 measured from the rear edge of the calibration device and the front edge of the reheating device is at least three times the length of the calibration device and, for example, five times its length. in the Calibration device 1 have two identical units 5 placed parallel to each other. The distance between the working surfaces is adjusted by means of a GH adjusting device depending on the desired thickness of the processed corrugated plastic cardboard material. The lower unit is fixedly connected to the horizontal chassis 6. In the corner of the chassis, four threaded pins are mounted. Towards the upper unit, four square plates 8 are welded each provided with an opening fitting to the outer diameter of the pipe connections. Threaded pins 7 have surface-mounted threads and each two nuts 9 for controlling the distance between the working surfaces of the calibration device. Each of the two units is provided with pipe connections 10,11 for coolant and .12 for connection to a vacuum source, 1906139-6 in Each unit of the calibration device consists of the metal block 13 and the chamber 14 made of angle iron and plates and welded with the block from the side which is not a working surface In the middle of the block and symmetrically with respect to its longitudinal axis, there are two cylindrical channels 15 clogged at one end and at the other end via a cylindrical chamber 16 connected to the pipe connection 11. Each of the channels. 15 is connected to a series of channels 17 arranged perpendicularly therearound, joined along the sides of the block to a common collecting unit 18 parallel to the longitudinal axis of the block. In the blocks between the channels there are a number of holes 19, which connect the working space in the calibration device with the chambers . Water fed through the pipe connection flows through the channels 15 and 16 and is collected in the unit 17 and flows out through the pipe connection 10. The reheating unit 4 has the shape of a flat rectangular prism made of plates and heat insulated and provided with openings 2Q in both front walls . From the plane formed by said openings, the interior of the unit is divided into two compartments, an upper compartment 21 and a lower compartment 22. At the bottom of these two compartments, infrared lamps 23 are installed with power numbers of 250, 400, 650 and 1000W in nine rows perpendicular to the longitudinal axis of the unit and with seven lamps in each row. The lamps with the same position in the rows form series with nine lamps in each series. The infrared lamps in the two outermost series 24 have a wattage of 1000 W and the lamps in the inner series 650 W, the lamps in the inner series 400 W and in the middle series 250 W. All nine rows are connected to a common power supply system with unlimited variable control of the current intensity by means of knobs 25. The tunnel is fixedly connected to the horizontal chassis 26. The invention is illustrated in more detail below in connection with exemplary embodiments.

Example 1 Pclypropylene with the trade name "Daplen EE" and with a discharge coefficient of 0.4 g / 10 min was heated and extruded through a spray head provided with a spray nozzle consisting of a series of separate cores with a rectangular cross section, the shape of which will determine the In the channels of the material being injected, compressed air was fed through holes in the cores of the nozzle, the extruded material was then fed between two cooling surfaces in a calibration device of the drawing figures. , the distance between the surfaces being 5 mm; and cooled more intensively in the middle part than in the outer areas and more intensively when the carton material exits the calibration device than when it enters it.

The desired distribution of the cooling intensity on the working surfaces of the calibration device is achieved by using a calibration device of the above-mentioned type consisting of two identical metal blocks, one of which is placed parallel above the other. The width of the calibration device was slightly greater than the width of the sprayed cardboard material and its length was about 0.75 of the width of the cardboard material. In the middle of each block and symmetrically with its longitudinal axis were two cylindrical channels, which were clogged from the side as Vette towards the spray head, which extruded the cardboard material. Each of the channels was connected via a series of these perpendicular channels to the longitudinal axis of the block via a collecting unit common to this parallel. at such surfaces of the blocks which did not constitute working surfaces, flat chambers were welded made of flat bars and plates. In the blocks between the channels, a number of small holes were found, which connected the working space of the calibration device with the chambers of the blocks.

In the cylindrical channels of both blocks, the demineralized water with a temperature of 120 ° C in countercurrent was supplied to the fed material. The water then flowed through the channels perpendicular to the feed direction of the carton material and was fed through the collection unit on either side of the blocks to a closed circulation system. The temperature of the water leaving the collection units was about 25 ° C.

The chambers in the two blocks were connected to a vacuum pump, which in the chambers maintained a vacuum of 20 mm Hg. 7906139-6 After leaving the calibration device, the plastic carton material was retained at ambient temperature until the temperature at each point of the cross section of the material had equalized.

Thereafter, the material was fed through a flat tunnel for reheating to a temperature of 50 - 100 ° C; the heating was carried out in such a way that the material was reheated less intensively in its central part than in the outer areas and less intensively in the zones closest to the tunnel inlet and discharge ends than in its central zone. The temperature of the material vta in the central zone was 70 ° C in the middle of the material and increased to 100 ° C near its edges. In the discharge zone of the tunnel, the temperature was 50 and 70 ° C, respectively. The total time required to reheat the material was about 70 seconds.

The material in the tunnel was heated from below and from above with the help of infrared lamps with power figures of 250, 400, 650 and 1000 W placed in nine rows parallel to the feed direction of the material web in groups of seven lamps in each row. The lamps which assumed the same position in the rows formed series, which ran parallel to the feed direction of the material web. In the two outermost series there were infrared lamps with a power of 00OW, in the inner series there were lamps with the power 650 W, in the inner series there were lamps with the power 400 W and in the middle series there were lamps with power 250 W. each of these nine lines had a common power supply with unlimited variable control of the current intensity. The center line was supplied with a current of the highest intensity and the current gradually decreased in the subsequent lines. The current intensity to the outermost rows was insignificant over half the current intensity of the current to the middle row.

The temperature of the material at the discharge end was measured using a contactless thermometer. The temperature in the center row was determined by changing the color of a strip painted on the surface of the disc, which color changed depending on the temperature. After leaving the reheating tunnel, the material was cooled down to ambient temperature and cut into sheets of desired dimensions. 7906139-6 The obtained corrugated plastic cardboard material of polypropylene showed a basis weight of 850'g / m2 with a deviation of 3 3%, a compressive strength of 3; 6 kp / cm? and cracked at a temperature of 50 ° C at a pressure of 15 kg / cm 2. The material was completely flat and during and after lapping for several days it showed no tendency to warp.

Example 2 A corrugated plastic board material was prepared from a copolymer of propylene and ethylene under the trade name "Moplençg EPQ-30M" with a feed coefficient of 0.7 g / 10 min in the same manner as in Example 1 but the heating was carried out at -5-10 ° C lower temperature and with a heating time of 60 seconds. The material produced showed a basis weight of 860 g / m 2 with a deviation of 2.8% and a compressive strength of 3.2 kg / cm 2.

Claims (3)

1906139-6 Patent claims A process for the production of corrugated plastic board material, in particular polyolefins, wherein the heated polymer is subjected to extrusion through a spray head provided with a spray nozzle containing a series of separate cores, the shape of which determines the shape of channels in the board material being compressed. channels in the cardboard material which are sprayed through holes found in the cores of the spray nozzle and that the sprayed cardboard material is fed between two suffocating surfaces in a heat-exchanging calibration device, known as the cardboard material being cooled more intensely in its outer portion and less intensively at the inlet end of the calibration device than at its outlet end and that the carton material is subsequently subjected to reheating in a tunnel at a temperature of between 46-120 ° C, the carton material being reheated less intensively in its central portion than in the outer areas and more intensively in the tunnel mittz on than in zones closest to the inlet and discharge ends of the tunnel. 2. A method according to claim 1, characterized in that the surface temperature of the reheated cardboard material is 1S-40 ° C lower in its central portion than its outer regions and 15-40 ° C higher in the central zone of the tunnel than zones closest to the inlet and discharge ends of the tunnel. ¿' Apparatus for carrying out the method according to claim 1 for producing corrugated plastic carton material, comprising an extruder, an extruder nozzle having a series of separate cores, the shape of which determines the shape of the channels in the carton material being sprayed, a heat exchanging calibration device for cooling, sprayed material from the nozzle and two sets of transport rollers, characterized in that it contains a reheating device (4) for reheating the cooled sprayed material from the heat exchanging calibration device, the heat exchanging calibration device and the reheating device being a distance of at least three times the length of the calibration device so that the cooled, 1 sprayed material can be exposed to ambient air, the calibration device comprises a pair of spaced apart opposing blocks (5), between which the hot, sprayed material the block passes, each block having a continuous passage: for coolant comprising central, longitudinal channels (15) with inlet opening on the downstream side, transverse channels (17) starting from the central, longitudinal channels and external, longitudinal collecting channel (18) connected to the side channels and having an outlet opening at the upstream end, that the opposite blocks have vacuum chambers (14) and vacuum passages (19) extending from the vacuum chambers to opposite sides of the block, that the reheating device comprises a pair of opposite compartments (22), delimiting between them a gutter-like tunnel (20) for the passage of sprayed material, and transverse rows (23) of infrared lamps in the spaces (21, 22), the transverse rows of lamps in each compartment forming longitudinal continuous, central, intermediate and outer series (24) of lamps and the lamps of the outer series are stronger than the lamps of the intermediate series, v which in turn is stronger than the lamps in the central series, and that each row of lamps has an individual system (25) for power supply, which is adjustable to be able to vary the current intensity.