METHOD FOR CONTINUOUS RECYCLING OF SCRAPS OF FIBER AND CLOTH THAT ARE BASED ON THERMOPLASTIC MATERIALS

Abstract

A method for continuous recycling of scraps of fiber and cloth that are based on thermoplastic materials in which when viewed in an extrusion direction, an extrusion apparatus is first supplied with the scrap composed of fibers and cloth and is then supplied with an additional fraction composed of thermoplastic polymers and additives, the supplied scrap and the additional fraction are mixed with each other in the extrusion apparatus, degassed, and then extruded together out of the extrusion apparatus forming an extrudate in which the scrap is embedded into the thermoplastic polymer of the additional fraction while at least partially retaining its fiber structure, with the mixing, degassing, and extruding of the scrap and the additional fraction being carried out at temperatures that lie below the softening temperature of at least one of the thermoplastic materials of the scrap.

Claims

1. A method for continuous recycling of scraps of fiber and cloth based on thermoplastic materials in which viewed in an extrusion direction (E), an extrusion apparatus (1) is first supplied with the scraps of fibers and cloth and is then supplied with an additional fraction of thermoplastic polymers and additives, the supplied scrap and the additional fraction are mixed with each other in the extrusion apparatus (1), degassed, and then extruded together out of the extrusion apparatus (1) forming an extrudate (6) in which the scrap is embedded into the thermoplastic polymers of the additional fraction while at least partially retaining a fiber structure, with the mixing, degassing, and extruding of the scrap and the additional fraction being carried out at temperatures below a softening temperature of at least one of the thermoplastic materials of the scrap.

2. The method according to claim 1, wherein before or after the supply of the additional fraction, the scrap is heated in the extrusion apparatus to a temperature of 100 C. to 160 C. and is degassed atmospherically or by a negative pressure.

3. The method according to claim 2, wherein before the supply of the additional fraction into the extrusion apparatus (1), the additional fraction is plasticized in a separate plasticizing extruder (4) and is supplied from this in a plasticized state to the extrusion apparatus (1) and then the scrap is degassed together with the additional fraction.

4. The method according to claim 3, wherein after the plasticization in the plasticizing extruder (4), the additional fraction is divided into two partial flows and the partial flows are supplied to the extrusion apparatus at successive positions of the extrusion apparatus (1), viewed in the extrusion direction (E).

5. The method according to claim 4, wherein the thermoplastic polymers and the additives of the additional fraction are supplied to the extrusion apparatus (1) together or at successive positions, viewed in the extrusion direction (E).

6. The method according to claim 5, wherein the fibers and cloth of the scrap are polyamide-based or polyester-based.

7. The method according to claim 6, wherein the scrap is supplied to the extrusion apparatus (1) in a proportion of at least 50% of the extrudate (6).

8. The method according to claim 7, wherein a moisture content of the scrap is regulated.

9. The method according to claim 8, wherein the extrudate (6) is formed into a tube, a profile, a cable, a film, a plate, a core material of a multilayered composite, a melt strand, or a granulate.

10. The method according to claim 1, wherein before the supply of the additional fraction into the extrusion apparatus (1), the additional fraction is plasticized in a separate plasticizing extruder (4) and is supplied from this in a plasticized state to the extrusion apparatus (1) and then the scrap is degassed together with the additional fraction.

11. The method according to claim 10, wherein after the plasticization in the plasticizing extruder (4), the additional fraction is divided into two partial flows and the partial flows are supplied to the extrusion apparatus at successive positions of the extrusion apparatus (1), viewed in the extrusion direction (E).

12. The method according to claim 1, wherein the thermoplastic polymers and the additives of the additional fraction are supplied to the extrusion apparatus (1) together or at successive positions, viewed in the extrusion direction (E).

13. The method according to claim 1, wherein the fibers and cloth of the scrap are polyamide-based or polyester-based.

14. The method according to claim 1, wherein the scrap is supplied to the extrusion apparatus (1) in a proportion of at least 50% of the extrudate (6).

15. The method according to claim 1, wherein a moisture content of the scrap is regulated.

16. The method according to claim 1, wherein the extrudate (6) is formed into a tube, a profile, a cable, a film, a plate, a core material of a multilayered composite, a melt strand, or a granulate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Details of this invention are explained in conjunction with exemplary embodiments, wherein:

[0020] FIG. 1 schematically shows an extrusion apparatus, according to a first embodiment of this invention;

[0021] FIG. 2 shows an extrusion apparatus, according to a second embodiment of this invention; and

[0022] FIG. 3 shows an extrusion apparatus, according to a third embodiment of this invention.

DETAILED DESCRIPTION OF THE INVENTION

[0023] FIGS. 1-3 show various embodiments of extrusion apparatuses, which are labeled with the reference numeral 1 and are used for carrying out the above-described method. The extrusion apparatus can optionally be a single-screw extruder or twin-screw extruder of an intrinsically known design, a selection made by the person skilled in the art depending on the application.

[0024] In the exemplary embodiment according to FIG. 1, viewed in the extrusion direction E, the extrusion apparatus 1 first has a feeder 10 for scraps of or composed of fibers and cloth based on thermoplastic materials such as shredder flows or fiber/cloth fractions, for example from recycling processes of end-of-life vehicles. This scrap is first compressed and homogenized in the extrusion apparatus, before a thermoplastic polymer supplied by a metering station 11 and suitable additives supplied by another metering station 12 are supplied together to the extrusion apparatus 1 at a point downstream, viewed in the extrusion direction E and in the extrusion apparatus 1, together with the already supplied scrap, are mixed, degassed, and extruded together out of the extrusion apparatus 1 forming an extrudate 6. In this connection, the temperature control takes place inside the extrusion apparatus 1 so that the mixing, degassing, and extruding of the scrap and the additional fraction are carried out at temperatures that lie below the softening temperature of at least one of the thermoplastic materials of the scrap so that in the extrudate 6, the scrap is embedded into the thermoplastic polymer of the additional fraction while partially retaining its fiber structure, which consequently forms a matrix material for accommodating the fibers and cloth remnants.

[0025] A typical recipe can, for example, be of or composed of the following: [0026] 40-80% scrap (fibers, cloth, etc.); [0027] 20-50% thermoplastic polymer (e.g. HDPE, MDPE, PP, EVA, or recycling shredder products); [0028] 5-50% additives (coupling agents, colorants, lubricants, etc.)

[0029] Degassing requires a temperature in the extrusion apparatus 1 of preferably 100 C. or more, while temperatures of approximately 120 C. to 160 C. are provided for the homogenization and molding.

[0030] By comparison, FIG. 2 shows a modified system in which the supply of the scrap and the additives is carried out by the corresponding metering units 10, 12 analogous to the embodiment in FIG. 1, but the polymer, which together with the additives forms the additional fraction, is first separately supplied to a plasticizing extruder 4 by a metering station 40 and plasticized and is then supplied to the extrusion apparatus 1 by a corresponding supply line 43 in an already plasticized state.

[0031] The exemplary embodiment according to FIG. 3 shows a system that has once again been modified by comparison, in which the thermoplastic polymer from the plasticizing extruder 4 is divided into two partial flows 41, 42, with the first partial flow 41 being supplied to the extrusion apparatus 1 immediately after the addition of the scrap, while the other partial flow 42 is supplied at a downstream position viewed in the extrusion direction E together with the additives that are dispensed into the extrusion apparatus 1 by the metering station 12.

[0032] The extrudate 6 obtained in all of the embodiments illustrated above can, for example, be processed into a tube, a profile, a cable, a film, a plate, or a core material of a multilayered composite such as a co-extrusion composite or can constitute or form a melt strand, which is subsequently pressed to form a three-dimensional component, for example, or also formed into a granulate, which can then undergo further processing, for example, in an injection molding process.

[0033] The obtained extrudates 6 feature high-quality mechanical properties due to the retention of the fiber structure in the polymer serving as the matrix material so that in the end, a fiber-reinforced polymer of or composed of the scraps and the additional fraction is obtained.

[0034] European Patent Application EP 15197545.5, filed 2 Dec. 2015, the priority document corresponding to this invention, to which a foreign priority benefit is claimed under Title 35, United States Code, Section 119, and its entire teachings are incorporated, by reference, into this specification.