Method for producing thermally crosslinkable polymers in a planetary roller extruder

Abstract

A method for producing thermally crosslinkable polymers in a planetary roller extruder is presented. The planetary roller extruder has a filling part and a compounding part made of a roller cylinder region that comprises at least two, preferably at least three coupled roller cylinders, planetary spindles of which are driven by a common central spindle. The polymers are supplied in a plasticized state. The filling part is supplied with a vacuum. The flow temperatures of the central spindle and the at least two roller cylinders under a vacuum are set such that the polymers to be degassed remain in the plasticized state. One or more liquids, such as thermal crosslinkers, crosslinking accelerators, dye solutions, or dye dispersions, are metered to the plasticized polymers downstream of the vacuum degassing, preferably in a continuous manner. Finally, the resulting mixture is directly supplied to a coating assembly.

Claims

1. A method for producing thermally cross-linkable polymers in a planetary roller extruder, wherein: a) the planetary roller extruder has a feed part and a compounding part, the compounding part being formed by a cylinder assembly area which comprises at least two coupled cylinder assemblies, planetary spindles of which are driven by a single common central spindle, b) the polymers are supplied into the planetary roller extruder in a plasticized state, c) the plasticized polymers are fed into a first cylinder assembly of the at least two coupled cylinder assemblies, within a first half of the first cylinder assembly, d) the feed part of the planetary roller extruder is charged with vacuum, e) in case the cylinder assembly area is formed by two cylinder assemblies, a shell of a second cylinder assembly of the at least two coupled cylinder assemblies has an opening via which air and possibly other volatile components are degassed from the plasticized polymers by a vacuum or in case the cylinder assembly area is formed by more than two cylinder assemblies, a shell of the second cylinder assembly of the more than two cylinder assemblies or a shell of a downstream cylinder assembly has an opening via which air and possibly other volatile components are degassed from the plasticized polymers by a vacuum, f) pre-flow temperatures of the central spindle and the at least two coupled cylinder assemblies are adjusted so that the polymers to be degassed remain in the plasticized state, g) one or more liquids are added to the plasticized polymers in the second cylinder assembly or in the downstream cylinder assembly or in an intermediate ring between two cylinder assemblies downstream of the opening via which air and possibly other volatile components are degassed, h) a blend of the plasticized polymers and the liquids in the cylinder assembly area, in which the liquids are incorporated into the plasticized polymers, are cooled so that, after the discharge of the blend from the planetary roller extruder, no evaporation takes place of the liquids mixed in the plasticized polymers, i) a length of the cylinder assembly area in which degassing of the plasticized polymers by vacuum takes place is between more than 50% and 80% of a length of the entire cylinder assembly area, j) the blend of the plasticized polymers and the liquids is supplied to a coating unit without further additional treatment.

2. The method according to claim 1, wherein at least one additional opening is provided in a shell of the first cylinder assembly, via which air and optionally further volatile components are degassed from the plasticized polymers by vacuum.

3. The method according to claim 1, wherein the charging the feed part with vacuum is effected by applying a pressure of less than 50 mbar at an outlet at the feed part or at a shell opening of the first cylinder assembly.

4. The method according to claim 1, wherein the opening in the shell of the second cylinder assembly is equipped with a product holding-down device, which prevents a discharge of the plasticized polymers from the planetary roller extruder, the product holding-down device being an intermeshing twin-screw pair, via free flanks of which the air and optionally the further volatile components are drawn-off of the plasticized polymers under the influence of heat and vacuum.

5. The method according to claim 1, wherein the adding of the liquids into the plasticized polymers takes place in an intermediate ring which is located between the second and a third cylinder assembly and which has at least one radial boring for feeding the liquids.

6. The method according to claim 1, wherein the adding of the liquids into the planetary roller extruder takes place via one or more borings in the shell of a cylinder assembly, the borings being in a region within the first half of the cylinder assembly.

7. The method according to claim 1, wherein the plasticized polymers are fed into the planetary roller extruder through an opening in a wall of the shell of the first cylinder assembly or via an intermediate ring which is located between the feed part and the first cylinder assembly and which has at least one radial boring for feeding the plasticized polymers.

8. The method according to claim 1, wherein the plasticized polymers are fed into the planetary roller extruder by a melt pump, by a single- or multi-screw extruder, or by a barrel or tank melt unit.

9. The method according to claim 1, wherein the discharge of the blend from the planetary roller extruder takes place by a melt pump coupled at an end of the cylinder assembly area.

10. The method according to claim 1, wherein the coating unit is a calendar or a die through which the blend is applied on a carrier material.

11. The method according to claim 1, wherein the plasticized polymers are from the group consisting of non-thermoplastic elastomers, thermoplastic synthetic rubbers, polyacrylates, polyurethanes, polyepoxides, and mixtures in any proportions thereof.

12. The method according to claim 1, wherein the plasticized polymers are blended with at least one of tackifying resins, fillers, softeners, oils, thixotropic agents and further additives.

13. The method according to claim 1, wherein the mixture coming from the planetary roller extruder is a pressure-sensitive self-adhesive or a thermosetting structural adhesive mass.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further details, objects, properties and advantages of the present invention will be explained in more detail by illustrative figures of the following divers, preferred execution examples.

(2) FIG. 1 shows a single-sided pressure-sensitive adhesive tape.

(3) FIG. 2 shows a double-sided pressure-sensitive adhesive tape.

(4) FIG. 3 shows a carrier-free pressure-sensitive adhesive tape (transfer adhesive tape).

(5) FIG. 4 shows a planetary roller extruder.

DETAILED DESCRIPTION

(6) FIG. 1 shows a pressure-sensitive adhesive tape 1 which is adhesive on one side. The pressure-sensitive adhesive tape 1 has an adhesive layer 2, which has been produced by coating of the previously described pressure-sensitive adhesive mass on a carrier 3.

(7) In addition (not shown) may still be provided a release film, which covers and protects the adhesive layer 2 prior to the use of the pressure-sensitive adhesive tape 1. The release film is then removed from the adhesive layer 2 prior to use.

(8) The product structure shown in FIG. 2 shows a pressure-sensitive adhesive tape 1 with a carrier 3, which is coated on both sides with a pressure-sensitive adhesive mass and thus has two adhesive layers 2.

(9) Also in this embodiment, at least one adhesive layer 2 is preferably covered with a release film. In the case of a rolled-up adhesive tape, this one release film may also cover the second adhesive layer 2 if necessary. But also several separating films can be provided.

(10) Furthermore, it is possible that the carrier film is provided with one or more coatings. Furthermore, only one side of the pressure-sensitive adhesive tape may be provided with the pressure-sensitive adhesive mass according to the invention and on the other side another pressure-sensitive adhesive mass may be used.

(11) The product structure shown in FIG. 3 shows a pressure-sensitive adhesive tape 1 in the form of a transfer adhesive tape, i.e. a carrier-free pressure-sensitive adhesive tape 1. For this purpose, the pressure-sensitive adhesive mass is coated on one side on a release film 4, thus forming a pressure-sensitive adhesive layer 2.

(12) Optionally, this pressure-sensitive adhesive layer 2 is still covered on its second side with another release film. To use the pressure-sensitive adhesive tape, the release films are removed then.

(13) As an alternative to release films, for example, release papers or the like can be used. In this case, however, the surface roughness of the release paper should be reduced in order to achieve the smoothest possible side of the pressure-sensitive adhesive mass.

LIST FOR REFERENCE SIGNS

(14) 1) Feed part with single-screw 2) Cylinder assembly 1 3) Cylinder assembly 2 4) Cylinder assembly 3 5) Melt pump for product discharge 6) Back venting vacuum degassing via feed part 7) Feed opening for the plasticized polymers 8) Opening in the cylinder assembly for vacuum degassing with product holding-down device 9) Feed opening in the intermediate ring for liquids 10) Feed opening in the cylinder assembly for liquids 11) Vacuum pump 12) Product discharge 13) Heating-cooling circuit for central spindle 14) Heating-cooling circuit for cylinder assembly 1 15) Heating-cooling circuit for cylinder assembly 2 16) Heating-cooling circuit for cylinder assembly 3 17) Intermediate ring