DE4311708C2 - Process for the recycling of plastic-containing textile composites, and the recyclate available thereby and its use - Google Patents

Description

The present invention relates to a method for Recycling of plastic-containing textile composites, such. B. Carpets, in particular automotive molded carpets.

Carpets are generally made of natural or synthetic Textile fibers or combinations thereof by knotting or Weaving made. One distinguishes so-called smooth carpets, those with a solid, coarse chain and coarse, mostly colored Weft are woven and so-called. Flor rugs. The latter can knotted, woven (web-pile rugs with closed Slings or cut tufts, z. B. Velor carpets) or needled. Needled pile carpets are also called tufted carpets or tufted carpets designate and find increasingly broad application. at their production are the textile fibers, mostly Polyamide (PA) -, less common polyester (PES) - or Polypropylene (PP) fibers, sewing machine principle in one finished base fabric or ground fleece used and afterwards on the back with a binder, z. B. natural rubber or Styrene-butadiene (SB) latices, glued. The tufting or Tufted carpets are becoming textile composites expected.

Automotive molding carpets used in comfort vehicles are usually based on tufting Built up velor carpets. The construction of such Shaped rugs is such that a base fabric or Basic fleece, a so-called spunbonded carrier based on a Polyesters or polyesters with polyamide sheath, with a Weight of about 100-150 g / m² with textile fibers (Tufting fibers) from, for example, PA 6,6 or PA 6  tufted so that a raw fragrance of the tufting type is Velor carpet is obtained. The yarn insert weights of the Tufting fibers are usually 300-800 g / m².

This raw air is used to fix the filaments back with a thermoformable binder, for example a Styrene-butadiene rubber (SBR), in a print run of about 30% 100 g / m² provided. This is a so-called carpet blank receive.

To achieve the required in the automotive sector Soundproofing and soundproofing values are based on the Carpet blank on the side facing away from the pile Layer of a thermoformable polymer, eg. B. Polyethylene (PE) and / or an ethylene-vinyl acetate copolymer (EVA) in an amount of 300-800 g / m² sintered.

On the thermoformable polymer may optionally be Cover fleece of, for example, PES-PA, d. H. a polyester with polyamide sheath, which is also thermoformable, in in an amount of about 30-100 g / m² or the layer of thermoformable polymer becomes direct with a heavy layer in an edition of 2000-7500 g / m² laminated.

Finally, if necessary, again a cover fleece of the aforementioned type are applied.

The heavy layer, usually a Ethylene-propylene-diene copolymer (EPDM) and at least contains an inorganic or organic filler for example, the following composition:

Barite (BaSO₄) 80 parts by weight EPDM 6 parts by weight EVA 8 parts by weight mineral oil 5 parts by weight Auxiliaries (such as, for example, lubricants,  1 part by weight Antioxidant) 100 parts by weight

or

barite 80 parts by weight EPDM 8 parts by weight PE 4 parts by weight mineral oil 7 parts by weight excipients  1 part by weight 100 parts by weight

A typical automotive molding carpet has z. B. following Construction on:

Carpet blank:
PES carrier (100 g / m²)
Tufting fibers (PA 6,6 or PA 6, 500 g / m²)
Binder (SBR, 50 g / m²)

thermoformable layer:
PE high pressure type (300-800 g / m, especially 500 g / m²)
(if applicable) cover fleece (PES-PA (polyamide with polyamide jacket), 50 g / m²)

Heavy layer:
EPDM-containing composition according to the above formulations (2000-7500 g / m², especially 3500 g / m²)
(if applicable) cover fleece (PES-PA (polyester with polyamide jacket), 50 g / m²).

Optionally, the textile composites of the above described type still with a polyurethane (PU) foam be foamed back.

These textile composites are initially used as a web material made and can then, especially in the application in the field of automotive molding carpets, from the back, for example, by the action of IR radiation, heated and then in suitable tools in the desired shape be deep-drawn.

Subsequently, the carpets are to the desired shape cut or punched. In unfavorable designed Carpet parts can cover up to 45% of the edge sections Surface of the carpet used, d. H. the carpet from the the desired shapes are obtained. These Edge sections as well as the disused textile composites were recently dumped in landfills and carry thus contributing to the burden on the environment.

To solve this problem, it was suggested that Production waste, z. B. from the automotive molding carpet production, reuse. Because these production waste by weight predominantly of heavy-layer material they will become one after suitable pretreatment certain share in the production of new heavy-layer Material added. This is done by the known method proceeded in the following way.

In a first, separate operation, the Fiber structure of the PA (tufted fibers) destroyed in which the Waste pieces by means of a disk mill, a so-called. Plastagglomerator, in a partially molten state brought, homogenized and then granulated.  

The granules fall in a grain size of up to about 6 mm Diameter on. The disadvantage is that this first operation requires a separate machine and relatively energy consuming, since the material is heated to melt must and this heat energy when cooling for granulation get lost. That's why the price of the granules is with about 0.3-0.6 DM / kg relatively high and makes the use of the granules uneconomical.

This granulate (i.e., regenerate) may then be used in a second Operation according to quality requirements in quantities of 5 50 wt .-% added to the composition (so-called Neumasse) from which even without the addition of reclaimed a new Heavy layer can be formed.

For compounding components of the material to Production of heavy layers is usually one Twin-screw extruder with exchangeable conveyor and Kneading elements used, which has a screw length of about 20 to 25 D, in particular 20 D has. D means that Ratio of the length to the diameter of the extruder screw. The twin-screw extruder is equipped with a dosing and Addition unit provided with the extruder all premixed components of the heavy layer material, d. H. the Neumasse and the granulate (Regenerat) from the first Operation, be supplied. The ingredients are then mixed in the extruder with heating and after Homogenization discharged from the extruder. The extrudate is then in a suitable surface-forming Process element, for example, a rolling mill or a Calender, processed to a heavy layer.

This method has several disadvantages. For one thing the process is carried out in two separate operations, for the two different machines (Plastagglomerator  and extruder) are needed. This increases the space, Energy and production costs in the production of Heavy layers, which contain a proportionate amount of regenerate.

On the other hand, a relatively large amount of energy is needed because the Carpet waste first heated in plastagglomerator, then cooled during granulation and then the granules when compounding Neumasse must be reheated. Besides the cost disadvantages and the larger energy and Time expenditure also leads to twice the thermal load Regeneration to a qualitative deterioration thermal degradation of the polymers, so that the quality of a Heavy layer containing a proportion of regenerate, with regard to z. B. tensile strength and elongation at break not nearly the quality of a heavy layer that no Regenerat contains.

An object of the present invention is therefore, a Method for simpler, more energy-efficient, cost-effective and material-friendly recycling of to provide plastic-containing textile composites.

Another object of the present invention is to Regenerat containing recyclate to provide a Higher quality than previously available recyclate.

These objects are achieved by those in the claims marked objects solved.

In the method according to the invention is the reusable material, d. H. the production waste in the manufacture of textile composites such as carpets, in particular automobile molding carpets, in one operation processed.  

This is a twin-screw extruder with a extended screw geometry of 25-35 D, preferably from 28-30 D used, with a concurrent Twin-screw extruder is preferred.

Are waste chips of 2-10 cm in length, 0.5-5 cm Width and 0.5 to 1.5 cm thickness used as at usual carvings, it is advantageous to one Extruder with screws of a relatively large flight depth of 1.5 to 3.0 cm (with a screw diameter of approx. 90- 180 mm) in order to ensure trouble-free insertion of the Waste chips also at low screw speed too guarantee.

The cylinder temperature of the twin-screw extruder is at Collection of waste chips about 0 ° to 50 ° C, preferably Room temperature (15 to 22 ° C). The temperature in the Slurry cylinders is 100 to 250 ° C, preferably 130 to 180 ° C. If desired, individual digestion cylinder temperatures below 100 ° C have.

In the first part of the extruder, the waste chips compacted and crushed. The temperature in this first Part of the extruder is chosen so that they are not possible above the melting point of the highest melting component of the Textile composite lies as the goal of this process step is just a pre-mixing and the material should not be overly thermally stressed. That up this material obtained is a second part of the Extruder supplied, the kneading elements, whose Geometry in combination with the screw speed so is designed so that in the material, the temperature Friction briefly rises to 220-270 ° C. This will any fibrous material present in the material, e.g. B. the tufted fibers of PA, melted and there is a homogeneous dispersion with the other constituents of the Textile composite.  

The homogeneous mixture (regenerated) is then a third Part of the extruder fed, having the conveying elements and in the homogeneous mixture, a predetermined amount Neumasse is metered. This Neumasse can z. B. in the Production of a heavy layer material for a Automotive molding carpet have a composition such as is described at the beginning.

The temperature of the Neumasse is in the addition in the Extruder about 10-50 ° C, preferably about room temperature. As a result, on the one hand, the temperature of the homogenized Mixture (regenerates) within a short time of about 220- 270 ° C lowered to about 120-200 ° C, creating a thermal Overloading of the material is avoided. on the other hand is the relatively high temperature of the regenerate to do so used to heat up the Neumasse and the heat energy is not, as in the previously known method, during cooling lost the granules.

Overall, energy-saving and material-saving Way in the third part of the extruder a very good one Dispersion of the ingredients achieved.

Subsequent to this process step, a Vacuum degassing done. The possibility of this Vacuum degassing is prolonged by the chosen one Helical geometry of the extruder favors. With this Vacuum degassing step can evacuate volatile substances removed from the mixture. Such volatile substances can z. B. be moisture, mainly in the PA fibers, as well as residual monomers, oligomers, Decomposition products and other volatile odors. One receives thereby opposite masses, which on one Plastagglomerator were processed, products with less volatile organic content by determination the VOC shares, d. H. fleeting org. Chemicals (carbon in volatile org. Verb.) Can be characterized what especially when using textile composites in  Passenger compartments of motor vehicles and other Transportation is becoming increasingly important.

If a vacuum degassing has been carried out or even without this step takes place in another part of the Extruder, which in turn has kneading elements, a repeated brief dispersion and homogenization before the material is extruded out of the extruder. Preferably, the material is directly from the extruder a surface-forming process element (eg rolling mill, calender) fed.

The present invention is illustrated by the following example explained in more detail.

example

Unless otherwise indicated, all quantities are given Weight.

On a twin-screw extruder ZE 90A (28D) from Berstorff were in the first housing 10, 20, 30 and 40 wt .-%, based on the overall approach, an automotive molding carpet, the previously shredded with a standard shredder, dosed.

The automobile molding carpet had the following chemical Composition:

Polymer fiber content (PA) | 10% PES 3% PE, EVA, EPDM of laminating and heavy layer 31% Heavy spar from heavy layer 56%

After homogeneous dispersion was added to the obtained Regenerate in the second third of the screw 60, 70, 80 or 90 Wt .-% Neumasse, based on the total batch, dosed.  

The Neumasse had the following composition:

80.0 BaSO₄ (Schwerspat®TS Fa. Sachtleben)
5.0 EPDM (Buna®AP 447 from Huls AG)
9.0 EVA (Escorene®UL 00728 from Exxon)
5.0 mineral oil (Flexon® 815 from Esso AG)
0.3 Lubricant (Bärolub®FTA from Bärlocher)
0.2 antioxidant (Irganox®1010 from Ciba Geigy)
0.5 antioxidant (Irganox®PS 802 from Ciba Geigy)
100.0

process conditions Housing temperatures of the twin-screw extruder Screw speeds

without regeneration 75 rpm 10% without regeneration 75 rpm 20% without regeneration 75 rpm 30% without replenishment 100 rpm 40% without regeneration 135 rpm

The speed adjustment is because of the higher proportion of regenerated necessary.

The process is carried out under known pressures in Extruder performed. As the expert knows, this depends of course from the snails and the others Process and reaction conditions from.  

The throughput of total mass was about 400 kg / h.

The extruded strand was placed on a rolling mill the company Schwabenthan, Berlin, and from there one 4-roll calender supplied by Berstorff. The Rolling temperature of the rolling mill was 150 ° C. The Calender rolls were tempered to 85 ° C. At the calender were Films with 1.0 mm +/- 0.10 mm thickness deducted.

Tensile strength and elongation at break were according to DIN 53 455 with a Zwick tensile testing machine Model 1445 (sample clamping length 120 mm, sample width 15 mm, feed 200 mm / min). These Values are used to assess the quality of the obtained Recyclates. Before the test, the samples were at least 24 h in standard climate (23 ° C / 50% relative humidity) conditioned. The values obtained are in Table I. shown.

The inventive method thus has over the previously known methods advantages, as it allows on less expensive, time-consuming, costly and more energy-saving and material-friendly way wastes from To reuse textile composites.

The inventive method requires only one Machine, namely a twin-screw extruder. The mixing Regeneration with Neumasse takes place without intermediate Cooling, because the introduced into the Regenerat heat energy is absorbed by the Neumasse, so that the energy balance much cheaper fails. Moreover, that gives inventive method a higher quality Product, as the thermal damage of the regenerate and the Neumasse due to the shorter residence time in comparison shorter with processing in a plastagglomerator. The optionally feasible vacuum degassing is also increasing an increase in product quality at:

Improving the quality of the produced Heavy layer can be taken directly from an experiment at the tear strength and the elongation at break of heavy layers be determined, with the heavy layers

• a) only with Neumasse,
• b) a recyclate containing a regenerate, which by means of a plastagglomerator is available, and
• c) with a recyclate, which with the inventive Method is available

were manufactured.

The result shows (see example) that at the same Regeneratmenge using the with the Materials available according to the invention produced heavy layer (c) in terms of breaking strength and Elongation at break of the heavy layer produced only with Neumasse (a) is much closer than that with the previously known Material-produced heavy layer (b).  

This is probably partly due to the better dispersion of the Attributable to components in the process according to the invention, partly on the material-saving processing method. at Heavy layers containing reclaimed from a plastagglo merator are already produced at lower additions a drop in mechanical properties, since here the Dispersion of the components is worse and that Material partially due to the thermal double loading is molecularly degraded.

Overall, the inventive method offers economic benefits and leads, otherwise the same Recipes, to better quality products.

Claims (10)

1. A process for recycling plastic-containing textile composites, such. As carpets, especially automotive molded carpets, characterized in that

• (a) the shredded textile composite is fed to a first part of a twin-screw extruder,
• (b) the textile composite is compacted in the first part of the two-screw extruder, comminuted, and the resulting material is then fed to a second element of the twin-screw extruder, a kneading element,
• (c) in this second part of the twin-screw extruder, the material of step (b) is kneaded,
• (d) the material from step (c) is fed to a conveying element having third part of the twin-screw extruder,
• (e) in this third part of the twin-screw extruder, adding to the material of step (d) a predetermined amount of a new mass,
• (f) the material from step (e) is homogenized by means of kneading elements and
• (G) is discharged from the twin-screw extruder.

2. The method according to claim 1, characterized in that the twin-screw extruder a synchronous Zwewel lenextruder is. 3. The method according to claim 1 or 2, characterized  that the twin-screw extruder has a screw length of 25 to 35 D has. 4. The method according to any one of the preceding claims, since characterized in that the twin-screw extruder a Has a snail with large flight depth. 5. The method according to claim 4, characterized in that the plastic-containing textile composite in one size from 2 to 10 cm in length, 0.5 to 5 cm in width and 0.5 to 1.5 cm thickness is added to the twin-screw extruder. 6. The method according to any one of the preceding claims, since characterized in that the temperature of the cylinder of Twin-screw extruder 0 to 250 ° C. 7. The method according to any one of the preceding claims, since characterized in that the from the twin-screw extruder extruded material from step (g) directly to a fla chenbildenden process element is supplied. 8. The method according to any one of the preceding claims, since characterized in that between step (e) and Step (f) additionally a vacuum degassing takes place. 9. Recyclate obtainable according to one of claims 1 to 8. 10. Use of a recyclate according to claim 9 as a compo nente of a plastic-containing textile composite.