Blown film installation, method for producing a blown film strip and film produced therewith

Patent metadata

Field	Value
Publication number	US-10137629-B2
Application number	US-201314404875-A
Country	US
Kind code	B2
Filing date	Aug 7, 2013
Priority date	Aug 7, 2012
Publication date	Nov 27, 2018
Grant date	Nov 27, 2018

Abstract

In blown film installations, it is known to provide longitudinal stretching of the produced double layer film strip downstream of the draw-off, more precisely downstream of the reversing unit and upstream of the winder. It is also known to stretch the down-drawn film, wherein the film must then be preheated owing to the long cooling path from the draw-off. According to a first feature, the present invention specifies warming the film above the draw-off and then treating it mechanically. The film can thereby be brought with only little energy from a first level of warmth to a temperature level at which it can easily be worked. According to a second feature, the invention specifies providing a tractive force breakdown brake.

First claim

The invention claimed is:

1. A blown film installation ( 1 ) with an annular nozzle for extruding a film tube, with a tube formation area for longitudinal and transverse stretching of the film tube, with a cooling means for the film tube moving in the machine direction, with a collapsing section of the film tube into a double layer film strip and with a pair of haul-off rollers beyond the cooling means for hauling off the film tube, wherein a processing roller line ( 8 ) for longitudinal stretching of the double layer film strip is disposed beyond the pair of haul-off rollers ( 2 ) in the machine direction,
wherein
the machine direction is oriented vertically from the bottom up and the processing roller line ( 8 ) is disposed above the pair of haul-off rollers, wherein a heating means is provided for the double layer film strip ( 23 ); and
wherein a reversing unit ( 20 ) is provided above the processing roller line ( 8 ).

2. The blown film installation according to claim 1 , wherein a heating section is provided upstream of the first stretching roller.

3. The blown film installation according claim 1 , wherein the processing roller line has a closed-loop temperature control system, wherein the heating means initially heats the double layer film strip by less than 80 K.

4. The blown film installation according to claim 1 , wherein the processing roller line has a heating roller for heating up the double layer film strip for an easier processing in the processing roller line.

5. The blown film installation according to claim 1 , wherein the processing roller line has a stretching section for a longitudinal stretching of the double layer film strip, with a stretching range with a length of 120 cm at the most.

6. The blown film installation according to claim 4 , wherein the processing roller line has a tempering roller, downstream of the stretching section, for releasing the tension of the double layer film strip after stretching.

7. The blown film installation according to claim 1 , wherein the tempering roller has a closed-loop temperature control system, which heats up the double layer film strip by less than 30 K.

8. The blown film installation according to claim 1 , wherein the processing roller line has a cooling means for the double layer film strip.

9. The blown film installation according to claim 1 , wherein the processing roller line has a closed loop control system for improving a flattening, with an extension of the double layer film strip by 0.5% to 5%.

10. The blown film installation according to claim 1 , wherein the processing roller line has a closed-loop control system for stretching, with a stretching of the double layer film strip by more than 5%.

11. The blown film installation according to claim 1 , wherein the processing roller line has a heating roller for the double layer film strip with a temperature gradient of plus/minus 0 K or of plus 1 K to plus 80 K or more in the case of fast moving double layer film strips.

12. The blown film installation according to claim 1 , wherein the processing roller line has a stretching roller for the double layer film strip with a temperature gradient of minus 10 K.

13. The blown film installation according to claim 1 , wherein one of the stretching rollers have a smaller roller diameter than the roller of the previous station and/or than the roller of the following station and/or than a roller of the other stations of the processing roller line.

14. The blown film installation according to claim 13 , wherein the first and the second stretching roller are both designed with a smaller roller diameter, so that the second stretching roller is preceded by the first stretching roller as a slower driven roller with a smaller roller diameter than the roller of the previous and/or than the roller of the following station and/or than a roller of the other stations of the processing roller line.

15. The blown film installation according to claim 1 , wherein the processing roller line has a tempering roller for the double layer film strip with a temperature gradient of minus 10 K.

16. The blown film installation according to claim 1 , wherein the processing roller line has a cooling roller for the double layer film strip with a temperature gradient of minus 10 K to minus 80 K, or minus 100 K in the case of fast moving double layer film strips, as compared to the previous station in the machine direction.

17. The blown film installation according to claim 1 , wherein the processing roller line has a threading aid with a displaceable or pivotable roller, wherein the meshing depth is adjustable in a continuous or stepped manner.

18. The blown film installation according to claim 1 , wherein a silicone inlay is provided in a roller surface in the processing roller line.

19. A method for producing a blown film strip in a blown film installation, with the steps of
a. extruding a film tube;
b. inflating the film tube in a tube formation area for longitudinal and transverse stretching of the film tube;
c. cooling the ascending film tube with a cooling means;
d. collapsing the film tube into a double layer film strip by means of a collapsing section;
e. hauling off the double layer film strip with a pair of haul-off rollers;

comprising the further steps of:
f. guiding the double layer film strip further upwards above the pair of haul-off rollers and through a processing roller line ( 8 ) with a heating means for heating up the double layer film strip; and
g. processing the double layer film strip in the processing roller line; and
providing a reversing unit ( 20 ) above the processing roller line ( 8 ).

20. The method according to claim 19 , wherein, in order to thread the double layer film strip at the start-up of the blown film installation, a roller of the processing roller line is displaced or pivoted away from its operating position and the double layer film strip is tensioned after threading by means of a return displacement or pivoting.

21. The method according to claim 19 , wherein, during processing, the double layer film strip is embossed, irradiated and/or subjected to a corona treatment.

22. The blown film installation according to claim 2 , wherein a heating section is provided wherein all the rollers upstream of the first stretching roller are actively heated up, or exactly one holding roller and one separate heating roller.

23. The blown film installation according claim 3 , wherein the processing roller line has a closed-loop temperature control system, wherein the heating means initially heats the double layer film strip by less than 30 K.

24. The blown film installation according to claim 5 , wherein the processing roller line has a stretching section for a longitudinal stretching of the double layer film strip, with a stretching range with a length of 50 cm at the most.

25. The blown film installation according to claim 7 , wherein the tempering roller has a closed-loop temperature control system, which heats up the double layer film strip by less than 20 K.

26. The blown film installation according to claim 8 , wherein the processing roller line has a cooling roller as said cooling means for the double layer film strip.

27. The blown film installation according to claim 10 , wherein the processing roller line has a closed-loop control system for stretching, with a stretching of the double layer film strip by m

Assignees

• Reifenhaeuser Masch

Inventors

• Gandelheidt Edgar

Classifications

• B29C55/18

  by squeezing between surfaces, e.g. rollers · CPC title

• B29C48/10

  flexible, e.g. blown foils · CPC title

• B29K2883/005

  LSR, i.e. liquid silicone rubbers, or derivatives thereof · CPC title

• B29K2023/12

  PP, i.e. polypropylene · CPC title

• Y10T428/31504

  Composite [nonstructural laminate] · CPC title