Packing of polysilicon

Patent metadata

Field	Value
Publication number	US-9725212-B2
Application number	US-201314072277-A
Country	US
Kind code	B2
Filing date	Nov 5, 2013
Priority date	Dec 4, 2012
Publication date	Aug 8, 2017
Grant date	Aug 8, 2017

Abstract

A bag contains polysilicon, has been welded and includes at least one weld seam and a polyethylene film having: a thickness of 150-900 μm; a stiffness at a flexural modulus F max of 300-2000 mN and F t of 100-1300 mN; a fracture force F determined by dynamic penetration testing of 200-1500 N; a fracture energy Ws of 2-30 J; a penetration energy W tot of 2.2-30 J; a film tensile stress at 15% longitudinal and transverse elongation of 9-50 MPa; an Elmendorf longitudinal film tear resistance of 10-60 cN; an Elmendorf transverse film tear resistance of 18-60 cN; a longitudinal film elongation at break of 300-2000%; a transverse film elongation at break of 450-3000%; and a weld seam strength of 25-150 N/15 mm. A method includes filling a bag with polysilicon, and welding by pulse sealing with contact pressure greater than 0.01 N/mm 2 to obtain a 25-150 N/15 mm weld seam strength.

First claim

What is claimed is:

1. A method for packing polysilicon into a plastic bag from a PE film with a thickness of 150-900 μm, a stiffness at a flexural modulus F max of 300-2000 mN and F t of 100-1300 mN, having a fracture force F determined by dynamic penetration testing of 200-1500 N, a fracture energy W s of 2-30 J and a penetration energy W tot of 2.2-30 J, having a film tensile stress at 15% longitudinal and transverse elongation of 9-50 MPa, having an Elmendorf longitudinal film tear resistance of 10-60 cN and an Elmendorf transverse film tear resistance of 18-60 cN, having a longitudinal film elongation at break of 300-2000% and having a transverse film elongation at break of 450-3000, and is produced by means of an extruder from a tubular PE film, comprising production of the bag, sealing the PE film prior to filling the bag, filling the bag with polysilicon and welding the bag after filling the bag, wherein the sealing and welding steps are effected by time-controlled, temperature regulated pulse sealing with a contact pressure by means of welding jaws greater than 0.01 N/mm 2 , resulting in a weld seam having a weld seam strength of 25-150 N/15 mm, wherein in each sealing and welding operation, the sealing and welding temperatures are detected without a sensor through electrical resistance measurement of a metallic seal wire that is sheathed in a nonmetallic material and regulated, in order to ensure reproducible sealing results and a homogeneous sealing quality, especially in prolonged operation with high frequency.

2. The method of claim 1 , wherein prior to the welding, air is sucked out of the bag until a flat bag containing little air arises.

3. The method of claim 2 , wherein before packing, the polysilicon is first portioned and weighed.

4. The method of claim 3 , comprising fold-free shaping of a second plastic bag from a PE film by means of tubular preforms or air injection or film spreaders or through a combination thereof, and introducing a first already closed polysilicon-filled PE bag horizontally into the second plastic bag by means of a conveying channel or other suitable transport units and welding of the second plastic bag by means of two welding jaws.

5. The method of claim 1 , wherein before packing, the polysilicon is first portioned and weighed.

6. The method of claim 5 , comprising fold-free shaping of a second plastic bag from a PE film by means of tubular preforms or air injection or film spreaders or through a combination thereof, and introducing a first already closed polysilicon-filled PE bag horizontally into the second plastic bag by means of a conveying channel or other suitable transport units and welding of the second plastic bag by means of two welding jaws.

7. The method of claim 6 , comprising introducing a first already closed polysilicon-filled PE bag horizontally into a second plastic bag of tubular PE film by means of a conveying channel or other suitable transport units and welding of the second plastic bag by means of two welding jaws, wherein the conveying channel or the transport unit is lowered to such an extent that the first bag can slide within the second plastic bag as far as the weld seam already produced so that the tubular film is pulled over the edge of the welding jaw and a fold-free weld seam arises.

8. The method of claim 1 , comprising fold-free shaping of a second plastic bag from a PE film by means of tubular preforms or air injection or film spreaders or through a combination thereof, and introducing a first already closed polysilicon-filled PE bag horizontally into the second plastic bag by means of a conveying channel or other suitable transport units and welding of the second plastic bag by means of two welding jaws.

9. The method of claim 8 , comprising introducing a first already closed polysilicon-filled PE bag horizontally into a second plastic bag of tubular PE film by means of a conveying channel or other suitable transport units and welding of the second plastic bag by means of two welding jaws, wherein the conveying channel or the transport unit is lowered to such an extent that the first bag can slide within the second plastic bag as far as the weld seam already produced so that the tubular film is pulled over the edge of the welding jaw and a fold-free weld seam arises.

10. The method of claim 1 , comprising introducing a first already closed polysilicon-filled PE bag horizontally into a second plastic bag of tubular PE film by means of a conveying channel or other suitable transport units and welding of the second plastic bag by means of two welding jaws, wherein the conveying channel or the transport unit is lowered to such an extent that the first bag can slide within the second plastic bag as far as the weld seam already produced so that the tubular film is pulled over the edge of the welding jaw and a fold-free weld seam arises.

11. The method of claim 1 , wherein prior to the welding, air is sucked out of the bag until a flat bag containing little air arises.

Assignees

• Wacker Chemie Ag

Inventors

• Wochner Hanns

Classifications

• B29C66/929

  characterized by specific pressure, force, mechanical power or displacement values or ranges · CPC title

• B29C65/7433

  the tool being a wire · CPC title

• B29K2827/18

  PTFE, i.e. polytetrafluoroethylene, e.g. ePTFE, i.e. expanded polytetrafluoroethylene · CPC title

• B65D33/00 Primary

  Details of, or accessories for, sacks or bags · CPC title

• B29C66/71

  characterised by the composition of the plastics material of the parts to be joined (welding bar compositions B29C65/125) · CPC title