Method for removing volatile components from elastomer-containing media and degassing devices therefor

Patent metadata

Field	Value
Publication number	US-9925693-B2
Application number	US-201414782043-A
Country	US
Kind code	B2
Filing date	Apr 4, 2014
Priority date	Apr 4, 2013
Publication date	Mar 27, 2018
Grant date	Mar 27, 2018

Abstract

The invention relates to a method for degassing elastomer-containing media, such as elastomer solutions and dispersions in particular, and degassing devices ( 1 ) for carrying out said method.

First claim

What is claimed is:

1. A treatment and degassing device comprising at least one extruder, the extruder comprising:
a housing and n housing bores B n with corresponding bore diameters D n , where n is a whole number from 2 to 16, and wherein the housing bores intersect and are parallel to one another;
n shafts W n , configured to rotate 360° in the same direction and each of which is arranged concentrically in one of the housing bores B n , each of which has a rotational axis A n and each of which is provided with at least one treatment element whose cross-sectional profile, in the peripheral direction, has:
m relative maxima R m max n in respect of the radial extension of the cross-section profile of the treatment element to the rotating axis A n of the shaft W n , where m is a whole number from 1 to 16, wherein, in addition, at least one relative maximum R m max n is an absolute maximum of the radial extension R max n in respect of the radial extension of the cross-sectional profile of the treatment element to the rotational axis A n of the shaft W n , wherein:
R max n <=(D n /2),

at least one feed zone,
one or more degassing zones, each comprising at least one degassing vent, configured for discharging volatile components from a medium containing elastomers from the extruder,
at least one discharge zone,
wherein the treatment elements comprise screw elements SE, wherein:
a clearance A SE between profiles of the screw elements of two shafts, each of which is arranged concentrically in adjacent housing bores B n and B n+1 , is:
i) from 0.001 to 0.2 A D , wherein A D is the clearance between the rotational axes of the two adjacent shafts,
ii) and has at least one absolute minimum A minSE and one absolute maximum A maxSE , wherein A maxSE is ≥1.5 A minSE .

2. The device in accordance with claim 1 , wherein:
a cross-section profile of the screw elements has at least one absolute maximum R max n with respect to the radial extension of the profile curve, wherein:
0.420 D n <R max n <0.496 D n .

3. The device in accordance with claim 1 wherein:
the screw elements SE, as a modular design, consist of a core shaft and screw elements which have a locating socket for the shafts, or, as screws in a solid construction, or as screw shafts consisting of individual subsegments manufactured as a solid construction;
the extruder comprises twin-screw extruders, planetary-gear extruders, or ring extruders; and
the extruder has at least one dispersion zone.

4. The device in accordance with claim 1 , wherein:
the extruder comprises 1 to 20 degassing zones;
at least one degassing zone is upstream from the feed zone, in the conveying direction of the extruder; and
at least a last degassing zone of the extruder, in the conveying direction of the extruder comprises screw elements SE.

5. The device in accordance with claim 1 , wherein the degassing zones further comprise at least one of gas vents and degassing domes configured to effectively prevent or reduce any leakage of medium containing elastomers therefrom.

6. The device in accordance with claim 1 , wherein the gas vents have internal surfaces and the surfaces comprise coatings which prevent or reduce adhesion of the medium to the surface.

7. The device in accordance with claim 1 , wherein the extruder further comprises:
expansion elements arranged upstream from the degassing zones, in the conveying direction of the extruder; and
one or more feed openings for introducing additives.

8. The device in accordance with claim 7 , wherein the expansion elements comprise rotating or fixed perforated plates having multiple parts configured to allow for removal of the perforated plates from the housing without removing the shafts.

9. The device in accordance with claim 1 ,
wherein the screw elements SE are: two-start or three-start;
asymmetrical or symmetrical; and
made of steel or metallic composite materials manufactured using powder metallurgy based-on iron, nickel or cobalt.

10. The device in accordance with claim 1 , further comprising:
a pre-extruder or pre-kneader arranged upstream from the extruder, each of which comprises a degassing extruder or a degassing kneader; and
a connecting transfer zone between the degassing pre-extruder or degassing pre-kneader and the extruder, wherein the transfer zone has at least one expansion element and at least one pressure control unit.

11. The device in accordance with claim 2 , wherein:
A maxSE is ≥10.0 A minSE ;

0.450 D n <0.480 D n ;
the screw elements SE, as a modular design, consist of a core shaft and screw elements, which have a locating socket for the shafts, or, as screws in a solid construction, or as screw shafts consisting of individual subsegments manufactured as a solid construction, and the screw elements SE are: two-start or three-start; asymmetrical or symmetrical; and made of nitrided steels, chromium steels, tool steels, stainless steels or metallic composite materials manufactured using powder metallurgy and based on iron, nickel or cobalt;
the extruder is a twin-screw extruders, and comprises:
at least one dispersion zone;
2 to 8 degassing zones, with at least one degassing zone upstream from the feed zone, in the conveying direction of the extruder, wherein all the degassing zones comprise:
screw elements SE, and
at least one of degassing domes and degassing vents, wherein the degassing vents comprise single-or multi-shaft plug screws mounted inside of the degassing vents to push medium containing elastomers or product back into the extruder, and internal surfaces with coatings which prevent or reduce adhesion of the medium or product to the surfaces;

rotating or fixed perforated plate expansion elements arranged upstream from the degassing zones, in the conveying direction of the extruder, wherein the rotating or fixed perforated plates have two parts configured to allow for removal of the perforated plates from the housing without removing the shafts; and
one or more feed openings for introducing additives; and the device further comprises:

one or more further concentrator units arranged upstream;
a degassing pre-extruder or degassing pre-kneader arranged upstream from the extruder; and
a connecting transfer zone between the degassing pre-extruder or degassing pre-kneader and the extruder, wherein the transfer zone comprises:
one perforated plate expansion element; and
at least one throttle to control pressure.

12. A method for removing volatile compounds from a medium containing elastomers (EM) containing at least one elastomer and at least one volatile compound, the method comprising:
conveying the medium containing elastomers (EM) into a degassing device in accordance with claim 1 ,
operating the degassing device in such a way that volatile compounds from the medium containing elastomers (EM) can escape through the degassing unit, thus reducing the content of the volatile compounds in the medium containing elastomers (EM), and
discharging from the degassing device, a polymer obtained from the medium containing elastomers as the product P, having a lower proportion of volatile compounds than the medium containing elastomers (EM) conveyed into the degassing device, and a total volatile compound content of 1% w/w or less based on the mass of the elastomer.

13. The method in accordance with claim 12 , wherein the medium containing elastomers (EM) contains at least one natural or synthetic elastomer having a mean molecular weight of greater than 2,000 g/mol.

14. The method in accordance with claim 12 , wherein the medium containing elastomers (EM) com

Assignees

• Lanxess Int Sa
• Arlanxeo Deutschland Gmbh

Inventors

• Paul Hanns-Ingolf
• Kirchhoff Joerg
• Wiesner Udo
• Timmermans Luc
• Dieltiens Nicolai

Classifications

• B29B7/845 Primary

  Venting, degassing or removing evaporated components in devices with rotary stirrers · CPC title

• B29C48/507

  characterised by the material or their manufacturing process · CPC title

• B29C48/2517

  of intermeshing screws · CPC title

• C08F114/16

  Monomers containing bromine or iodine · CPC title

• B29B7/7495

  for mixing rubber · CPC title