Method for Producing a Plastic Film from a Total Quantity of Raw Materials in a Film Extrusion Machine, and Computer Program Product for Carrying Out the Method

Abstract

The invention relates to a method for producing a plastic film from a total quantity of raw materials in a film extrusion machine. Said method according to the invention comprises the following steps: providing a selection of raw materials from a total quantity of raw materials, setting machine and production parameters of the film extrusion machine, supplying the selection of raw materials to the film extrusion machine in a composition, detecting at least one actual value of a property of the plastic film, forming a difference between the actual value and a target value of the property, changing the selection of raw materials and/or the composition of the raw materials, if the difference exceeds a threshold.

Claims

1. A method for producing a plastic film from a total quantity of raw materials in a film extrusion machine, comprising the following steps: providing a selection of raw materials from a total quantity of raw materials, setting machine and production parameters of the film extrusion machine, supplying the selection of raw materials to the film extrusion machine in a composition, detecting at least one actual value of a property of the plastic film, forming a difference between the actual value and a target value of the property, changing the selection of raw materials and/or the composition of the raw materials if the difference exceeds a threshold.

2. The method according to according to claim 1, additionally comprising the following step: associating at least one raw material with the property of the plastic film based on the film production model.

3. The method according to according to claim 1, additionally comprising the following step: maintaining the machine and production parameters of the film extrusion machine.

4. The method according to claim 1, wherein one of the following steps is carried for detecting the property of the plastic film: determining the bubble shape determining the frost line position within the film extrusion line determining the total thickness of the plastic film determining the thickness variation of the plastic film across its width determining the thickness of at least one individual layer of the film determining the viscosity of a melted-on raw material determining the number of fish eyes in the plastic film determining the Young's modulus of the plastic film determining the tear resistance of the plastic film.

5. The method according to claim 1, wherein the plastic film comprises at least one layer which is created from several raw materials, wherein a main raw material and at least two ancillary raw materials are used, wherein changing the selection of raw materials and/or the composition of the raw materials substantially relates to the ancillary raw materials, wherein, in particular, the main raw material accounts for at least 51% of the total raw material.

6. A computer program product comprising instructions which, when the program is executed on a computer, cause the computer to carry out the steps of a method comprising the features of claim 1.

Description

[0040] Also the subject of the present invention is a computer program product comprising instructions which, when the program is executed on a computer, cause the computer to carry out the steps of a method according to the invention. Thus, a computer program product according to the invention has the same advantages as those explained in detail with reference to a method according to the invention.

[0041] FIG. 1 schematic illustration of a film extrusion machine,

[0042] FIG. 2 schematic illustration of a different film extrusion machine,

[0043] FIG. 3 schematic illustration of the sequence of a method according to the invention.

[0044] In FIGS. 1 and 2, film extrusion machines 10 are shown by way of example. The film extrusion machines have in common that they are equipped with extruders 20. Each individual extruder supplies the film extrusion machines with melted plastic material for a layer of the subsequent film. For this purpose, a first extruder is supplied with one or more raw materials R1, . . . via metering devices 60, a second extruder is supplied with one or more raw materials Rx . . . in said manner. The raw materials are generally provided in the form of plastic granulate. The type and/or quantity of the supplied raw materials are predetermined by the method according to the invention.

[0045] The method according to the invention can be carried out using a cast film or a blown film extrusion line as shown in FIG. 2.

[0046] FIG. 1 shows a blown film line comprising the already described extruders 20. A film web or film 40 for short is discharged from the die 30, the die 30 being designed as an annular blow die. The film web is initially formed as a bubble which is later laid flat. Said film, which now comprises two individual films placed one on top of the other, is wound counter-clockwise onto one winding roller 50 or, after cutting, onto two winding rollers.

[0047] The film extrusion machine in FIG. 2 is a cast film extrusion machine, which, as an example, is also equipped with two extruders 20 for different compositions. A film web 40 is discharged from the die 30, which film web cools down on a cooling roller and is subsequently wound onto a winding roller 50.

[0048] FIG. 3 schematically shows the process of the method according to the invention. A memory and computing unit 100 is provided with film parameters FP relating to the desired properties of the film and raw material parameters RPn relating to the properties of the raw materials. The index n of the raw material parameters RP indicates that this is an entirety of raw materials from which one or more raw materials are selectable. First a grouping of the raw material parameters into at least two raw material parameter groups is carried out in the memory and computing unit, which is illustrated through the reference sign 200. In two subsequent steps, which may be carried out in any order or simultaneously, correlations are formed between raw material parameter groups 300, and correlations are formed between film parameters and the raw material parameter groups 400 based on a film production model which is stored and/or executed within the memory and computing unit. In the subsequent step 500, a selection of at least one raw material from at least one raw material parameter group is detected.

[0049] After the control and computing unit 100 has calculated at least one production parameter PP of the film extrusion machine based on the film production model, the production parameter of the film extrusion machine is output.

REFERENCE SIGN LIST

[0050] 10 Film extrusion machine [0051] 20 Extruder [0052] 30 Die [0053] 40 Film web [0054] 50 Wound roll [0055] 60 Dosing device [0056] 100 Memory and computing device [0057] FPM Film production model