FILM BLOWING MACHINE AND METHOD FOR PRODUCING A FILM WEB

Abstract

A film blowing machine for producing a film web from a recycled material having a.-an extruder for melting and homogenizing the recycled material into a melt, b. an annular die for extruding a film tube, c. a guide for a melt flow between the extruder and the annular die via an annular die melt pump, for conveying the melt to the annular die, d. a tube-forming zone for longitudinal and transverse drawing of the film tube, e. a cooling means for the film tube moving in the machine direction, f. a flattening unit on the other side of the tube-forming zone for flattening the film tube into a double layer film web, g. a pair of draw-off rollers on the other side of the cooling means for drawing off the film tube, and h. the extruder is designed as a twin-screw extruder.

Claims

1-43. (canceled)

44. A blown film installation for producing a film web from a recycled material, the blown film installation comprising: an extruder for melting and homogenizing the recycled material into a melt; an annular nozzle for extruding a film tube; a guide for a melt flow between the extruder and the annular nozzle via an annular nozzle melt pump, for conveying the melt to the annular nozzle; a tube formation zone for longitudinal and transverse drawing of the film tube; a cooling means for the film tube moving in the machine direction; a collapsing section beyond the tube formation zone for collapsing the film tube into a double-layer film web; and a pair of draw-off rollers beyond the cooling means for drawing off the film tube, wherein the extruder is configured as a twin-screw extruder.

45. The blown film installation according to claim 44, further comprising: a filter having at least one filter element for filtering the melt from an unfiltered side to a filtered side, wherein the filter is arranged in the guide for the melt flow between the extruder and the annular nozzle.

46. The blown film installation according to claim 45, wherein the filter has a cleaning device which continuously and/or discontinuously replaces the filter element.

47. The blown film installation according to claim 45, further comprising a filter melt pump between the extruder and the annular nozzle melt pump, which pumps the melt to the filter.

48. The blown film installation according to claim 44, wherein the twin-screw extruder has at least one degassing unit which makes it possible to extract impurities and contaminants,

49. The blown film installation according to claim 48, wherein the vacuum degassing unit has a means for collecting condensate which arises during the vacuum degassing.

50. The blown film installation according to claim 46, wherein the extruder has a recycled material supply with a stuffing screw.

51. The blown film installation according to claim 50, further comprising at least two pressure sensors for capturing pressures within the guide for the melt flow, in each case in the melt flow at the extruder and upstream of the annular nozzle, wherein the extruder and/or the annular nozzle melt pump and/or the recycled material supply can be regulated as a function of a melt pressure in the melt flow at the extruder and/or upstream of the annular nozzle.

52. The blown film installation according to claim 51, further comprising two additional pressure sensors for capturing the melt pressure in the melt flow upstream and downstream of the filter, wherein the extruder and/or the annular nozzle melt pump and/or the recycled material supply and/or a deflection device of the filter and/or a filter element changing apparatus can be regulated as a function of the melt pressure upstream and/or downstream of the filter.

53. The blown film installation according to claim 44, further comprising a storage silo for stocking the recycled material.

54. The blown film installation according to claim 53, further comprising a screw conveyor which conveys the recycled material from the storage silo to a recycled material supply.

55. The blown film installation according to claim 53, wherein the storage silo has a means for mixing the recycled material within the storage silo.

56. The blown film installation according to claim 53, wherein the storage silo has a means for determining a level to which it is filled with the recycled material.

57. The blown film installation according to claim 53, wherein the storage silo has a means for determining a recycled material consumption thereof, wherein the means for determining the recycled material consumption is a weighing device of the storage silo.

58. The blown film installation according to claim 53, further comprising a dispensing silo for filling the recycled material in the storage silo.

59. The blown film installation according to claim 58, further comprising a shredder for comminuting a starting material, wherein the shredder is configured to comminute the starting material into the recycled material.

60. The blown film installation according to claim 59, further comprising a transport device for transporting the recycled material from the shredder to the storage silo and/or the dispensing silo, wherein the transport device is configured as a conveyor belt and/or as a screw conveyor or as a pressure conveying system.

61. The blown film installation according to claim 60, further comprising at least one mixing silo for mixing the recycled material with further materials, wherein the mixing silo is connected to the storage silo and/or the dispensing silo via a blower and/or a conveyor belt and/or a screw conveyor for introducing the recycled material and/or mixtures thereof.

62. The blown film installation according to claim 44, wherein a recycled material supply is configured to additionally or alternatively receive a pelleted recycled material, in addition to the recycled material, in order to convey it to the extruder, wherein the blown film installation has a pellet metering device for stocking and metering the pelleted material, and wherein the pelleted material is virgin material and/or higher-quality recyclates compared to the recycled material.

63. The blown film installation according to claim 62, wherein the pellet metering device has a screw conveyor which conveys the recycled material to the extruder.

64. The blown film installation according to claim 44, wherein the blown film installation is configured to produce the film web with at least one further layer in addition to a layer made of the recycled material, wherein the blown film installation has at least one additional extruder which melts and homogenizes the material of at least one additional layer into a melt, and wherein the at least one additional extruder is configured as a twin-screw extruder.

65. The blown film installation according to claim 64, wherein the blown film installation is configured to produce the film web in which the recycled material is arranged between at least two further layers in the film web.

66. The blown film installation according to claim 44, wherein a machine direction is oriented substantially vertically in a bottom-top direction.

67. Use of a twin-screw extruder for feeding an annular nozzle of a blown film installation.

68. A method for producing the film web from the recycled material according to claim 44, the method comprising steps of: a. the twin-screw extruder melts and homogenizes the recycled material into the melt, b. the melt is conveyed to the annular nozzle via the melt flow with the annular nozzle melt pump, c. the melt is extruded into the film tube via the annular nozzle, d. the film tube is longitudinally and transversely drawn at the tube formation zone, e. the collapsing section for the film tube combines the film tube beyond the tube formation zone into the double-layer film web, and f. the blown film installation has the pair of draw-off rollers beyond the collapsing section for drawing off the film tube.

69. The method according to claim 68, wherein the melt flow is filtered by means of a filter having at least one filter element within the melt flow by conducting the melt flow from an unfiltered side to a filtered side, and wherein the filter is arranged in the melt flow between the extruder and the annular nozzle.

70. A method for producing a film web from a recycled material, wherein the filter element is configured according to claim 46.

71. The method according to claim 70, further comprising a filter melt pump arranged between the extruder and the annular nozzle melt pump and pumps the melt to the filter.

72. The method according to claim 68, wherein the melt is degassed in the twin-screw extruder via at least one degassing unit, as a result of which an extraction of impurities and contaminants takes place.

73. The method according to claim 68, wherein the extruder is filled with the recycled material via a recycled material supply with a stuffing screw.

74. The method according to claim 68, further comprising: a. a pressure sensor which captures a melt pressure in the melt flow at the extruder, b. a pressure sensor which captures the melt pressure in the melt flow upstream of the annular nozzle, and c. a control and regulating device which regulates the extruder and/or the annular nozzle melt pump and/or a supply of the recycled material as a function of the melt pressure in the melt flow at the extruder and/or upstream of the annular nozzle.

75. The method according to claim 74, further comprising: a. a pressure sensor which captures the melt pressure in the melt flow upstream of the filter, b. a pressure sensor which captures the melt pressure in the melt flow downstream of the filter, and c. a control and regulating device which regulates the extruder and/or the annular nozzle melt pump and/or the supply of the recycled material and/or a deflection device of a filter and/or a filter element changing apparatus as a function of the melt pressure in the melt flow upstream and/or downstream of the filter.

76. The method according to claim 75, wherein the control and regulating device regulates the extruder and/or the annular nozzle melt pump and/or the supply of the recycled material and/or the deflection device of the filter as a function of the pressure sensor for capturing the melt pressure in the melt flow at the extruder and the pressure sensor for capturing the melt pressure in the melt flow upstream of the annular nozzle and the pressure sensor for capturing the melt pressure in the melt flow upstream of the filter and the pressure sensor for capturing the melt pressure in the melt flow downstream of the filter.

77. The method according to claim 76, further comprising a screw conveyor which conveys the recycled material from a storage silo to a supply of the recycled material.

78. The method according to claim 77, wherein the screw conveyor conveys the recycled material from the storage silo as a function of a filling degree of the storage silo and/or as a function of the melt pressure in the melt flow at one of the pressure sensors to the supply of the recycled material of the extruder.

79. The method according to claim 78, wherein the storage silo is filled with the recycled material from a dispensing silo as a function of a filling degree of the storage silo.

80. The method according to claim 68, further comprising a shredder which comminutes a starting material into the recycled material.

81. The method according to claim 80, further comprising a transport device which transports the recycled material from the shredder to a storage silo via a conveyor belt or a pressure conveying system.

82. The method according to claim 81, wherein in addition to the recycled material, a pelleted material is additionally or alternatively added to the extruder, wherein the pelleted material is added to the extruder via a pellet metering device, and wherein the pelleted material is virgin material and/or higher-quality recyclates compared to the recycled material.

83. The method according to claim 82, wherein as a function of the filling level of the storage silo and/or of a recycled material consumption and/or as a function of the melt pressure in the melt flow at one of the pressure sensors, the pelleted material is additionally or alternatively added to the extruder, in addition to the recycled material.

84. The method according to claim 68, wherein the film web with the recycled material is extruded with at least one further layer of a further plastic in addition to a layer made of the recycled material.

85. The method according to claim 84, wherein the further layer of the further plastic is virgin material and/or higher-quality recyclates compared to the recycled material.

86. The method according to claim 68, wherein the recycled material is extruded with at least one further layer of a further plastic on each flat side.

Description

BRIEF DESCRIPTION OF THE FIGURE

[0142] Further advantages and aspects of the invention are set out by the claims and the following description of a preferred exemplary embodiment of the invention, which is explained below using a figure.

[0143] The figure shows a detail of a schematic exemplary embodiment of a blown film installation according to the invention.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT

[0144] The figure shows a blown film installation 10 according to the invention, which is provided for producing a film web from a recycled material 4.

[0145] The blown film installation 10 has an extruder 20 for melting and homogenizing the recycled material 4 into a melt. In this exemplary embodiment, the extruder 20 is arranged horizontally on the floor.

[0146] The extruder 20 is configured as a twin-screw extruder. In this exemplary embodiment, it is a closely intermeshing co-rotating twin-screw extruder.

[0147] In the present case, the recycled material 4 is a plastic from the group of polymers, polycondensates, polyethylenes, polypropylenes, thermoplastic materials, ionomers, ethylene copolymers, cyclic olefin copolymers, polyamides, thermoplastic elastomers, polyethylene terephthalates, polyisobutylene, bio-based and biodegradable plastics.

[0148] The extruder 20 is driven by an electric motor. In this exemplary embodiment, the extruder 20 has both an atmospheric degassing unit and a vacuum degassing unit 24. The vacuum degassing unit 24 is operatively connected to a vacuum pump 26. The vacuum degassing unit 24 has a means for collecting condensate. The extruder 20 has a guide for a melt flow 40 to an annular nozzle 30 for extruding a film tube 6. An annular nozzle melt pump 42 is arranged between the extruder 20 and the annular nozzle 30, which conveys the melt to the annular nozzle 30. As a result of this design, a pressure in the melt flow does not have to be built up exclusively by the extruder 20, but rather can be built up and/or increased by the annular nozzle melt pump 42. The annular nozzle 30 is followed by a tube formation zone 32 for drawing the film tube 6 longitudinally and transversely. The blown film installation 10 has a cooling means 34 for the film tube 6 moving in the machine direction. In the present case, the cooling means 34 is air which is blown into or, respectively blown onto the blown film tube 6. Beyond the tube formation zone 32, the blown film installation 10 has a collapsing section 36 for collapsing 36 the film tube 6 into a double-layer film web 8. Beyond this collapsing section 36, a pair of draw-off rollers 38 is arranged, which are provided beyond the cooling means 34 for drawing off the film tube 6.

[0149] In this exemplary embodiment, the blown film installation 10 has a filter 50 which is arranged between the annular nozzle melt pump 42 and the extruder 20. In this exemplary embodiment, a filter melt pump 60 is arranged between the filter 50 and the extruder 20. In addition, the extruder 20 has a recycled material supply 44 with a stuffing screw 46. The stuffing screw 46 is driven by an electric motor. In this exemplary embodiment, the blown film installation 10 has a shredder 80 into which a starting material 2 can be fed, which is comminuted into the recycled material 4. The starting material 2 can be a plastic from the aforementioned group. The starting material 2 can be present in the form of sheet material, comminuted sheet material, shredded film, etc. The shredder 80 comminutes the starting material 2 into flakes between 5 mm and 12 mm in size. The shredder 80 has a transport device 82 which conveys the shredded recycled material 4 to a dispensing silo 100. The dispensing silo 100 is arranged above the storage silo 90 and has a metering device 102 via which the recycled material 4 can be discharged, if necessary, into the storage silo 90. In this exemplary embodiment, the metering device 102 is configured as a slide. The storage silo 90 has a means for mixing the recycled material 92, which is configured as an agitator in this exemplary embodiment. The recycled material 4 is guided from the storage silo 90 via a screw conveyor 94 into the recycled material supply 44 at the extruder 20.

[0150] The storage silo 90 has means for determining the recycled material consumption. In this exemplary embodiment, the means for determining the recycled material consumption is configured as a weighing device of the storage silo 96. As a result, the consumption of the recycled material 4 can be established as a unit of weight per unit of time. In this exemplary embodiment, the means for determining the filling level of the storage silo 90 is realized by the weighing device of the storage silo 96. As soon as the filling level and, thus, the weight of the storage silo 90 falls below a predetermined value, the storage silo 90 is filled with recycled material 4 from the dispensing silo 100.

[0151] The recycled material supply 44 is configured to additionally or alternatively receive a pelleted recycled material 4, in addition to the recycled material 4, in order to convey it to the extruder 20. For this purpose, the blown film installation 10 has a pellet metering device 110 for stocking and metering the pelleted material. The pelleted material is preferably virgin material and/or higher-quality recyclates compared to the recycled material.

[0152] A pressure sensor 70 captures the melt pressure in the melt flow at the extruder 20, and a further pressure sensor 76 captures the melt pressure in the melt flow upstream of the annular nozzle 30. A control and regulating device (not depicted) regulates the extruder 20, the annular nozzle melt pump 42 and the recycled material supply 44 as a function of the melt pressure in the melt flow at the extruder 20 and upstream of the annular nozzle 30. This makes it possible to extrude recycled material 4 constantly.

[0153] An additional pressure sensor 72 captures the melt pressure in the melt flow upstream of the filter 50, and an additional pressure sensor 74 captures the melt pressure in the melt flow downstream of the filter 50. The first pressure sensor 70 captures the melt pressure beyond the extruder 20. The second pressure sensor 76 captures the melt pressure directly at the annular nozzle 30.

[0154] A cut-off pressure is monitored by means of the pressure sensor 76, which captures the melt pressure directly at the annular nozzle 30. The cut-off pressure provides information as to whether a maximum pressure has been reached in the melt flow. This maximum pressure in the melt flow can be reached if, for example, the temperature at the annular nozzle 30 is too low and the recycled material 4 can no longer be conveyed through the annular nozzle 30 in the necessary quantity. The pressure sensor 76, which is arranged directly on the annular nozzle 30, is used to regulate the speed of the annular nozzle melt pump 42. A further pressure sensor 72 for monitoring a further cut-off pressure is arranged immediately upstream of the filter 50. The pressure sensor 72, which is arranged immediately upstream of the filter 50, is also used for regulating the cleaning device. The pressure sensor 70, which is arranged immediately downstream of the extruder 20, is used to regulate the extruder speed. The pressure sensor 74, which is arranged immediately downstream of the filter 50, is used to regulate the speed of the filter melt pump 60 and the speed of the annular nozzle melt pump 42.

LIST OF REFERENCE NUMERALS

[0155] 2 Starting material [0156] 4 Recycled material [0157] 6 Film tube [0158] 8 Double-layer film web [0159] 10 Blown film installation [0160] 20 Extruder [0161] 22 Atmospheric degassing unit [0162] 24 Vacuum degassing unit [0163] 26 Vacuum pump [0164] 28 Condensate collector [0165] 30 Annular nozzle [0166] 32 Tube formation zone [0167] 34 Cooling means [0168] 36 Collapsing section [0169] 38 Pair of draw-off rollers [0170] 40 Guide for a melt flow [0171] 42 Annular nozzle melt pump [0172] 44 Recycled material supply [0173] 46 Stuffing screw [0174] 50 Filter [0175] 52 Filter element [0176] 60 Filter melt pump [0177] 70 Pressure sensor [0178] 72 Pressure sensor [0179] 74 Pressure sensor [0180] 76 Pressure sensor [0181] 80 Shredder [0182] 82 Transport device [0183] 90 Storage silo [0184] 92 Means for mixing the recycled material [0185] 94 Screw conveyor [0186] 96 Weighing device of the storage silo [0187] 100 Dispensing silo [0188] 110 Metering device [0189] 110 Pellet metering device