DE102023200311A1 - Process for producing a composite plastic and composite plastic - Google Patents

Abstract

The invention relates to a composite plastic and a method for producing a composite plastic, comprising the steps:
- Provision of processed textiles (S1), preferably used textiles, from which impurities have been removed to the greatest possible extent (S101),
- Shredding the processed textiles into a ground material (S3),
- dosing of components (S4, S6), wherein the components comprise the ground material and a plastic, in particular comprising plastic recyclate, preferably exclusively comprising plastic recyclate,
- Mixing the components (S5, S501, S7) and
- Extruding the components through an extruder to form a composite plastic (S8).

Description

The invention relates to a method for producing a composite plastic and to a composite plastic.

In Germany, a considerable amount of (old) textiles are collected every year, only a small proportion of which are recycled or reused through downcycling. Worldwide, (old) textiles are mostly burned or dumped. There are various approaches to the resource-saving reuse of (old) textiles. Discarded (old) textiles that are neither dirty, wet nor damaged can be reused as second-hand clothing. Other textiles are processed into cleaning rags, for example. Only around 1 percent is used as recycled fibers in textile production. However, textiles made from low-quality synthetic fibers and mixed fibers are generally no longer suitable for this type of recycling.

Another option is to recycle (old) textiles into composite plastics. A plastic, usually a thermoplastic, is mixed with shredded textiles and heated. This recycling process also enables the recycling of low-quality synthetic fibers and mixed fibers.

In EP 3 922 665 A1 A process for recycling textiles into composite plastic granules is described. Textiles are first crushed into a powder of fabric particles and the powder is processed into fabric pellets with a binding agent. The fabric pellets are then mixed with plastic in an extruder and extruded into a composite plastic. The extruded composite plastic is granulated for further processing, for example into sunglasses using the injection molding process.

Another process for producing composite plastic is in US 10 047 462 B1 described. Powdered textiles are mixed with a thermoplastic and heated. This mixture is then used to produce a flat mat, which can be molded into various shapes using a pressing process.

The problem with the known processes is that the pelletizing of the shredded tissue in particular requires a lot of energy. A considerable amount of the natural and increasingly scarce resource water is used. Pelletizing also takes additional time. Another problem with the known process is that the composite plastic produced cannot be reused as a component after use. A closed value creation cycle is therefore not possible. The shaping of components made of composite plastic, which can be made from prefabricated flat mats, is also severely limited.

The present invention is therefore based on the object of designing and developing a method for producing a composite plastic and a composite plastic of the type mentioned at the beginning in such a way that an energy-efficient and resource-saving production process with the shortest possible process time is provided. In addition, a composite plastic should be produced using simple means. The plastic should also be able to be reused after its use as a plastic component.

• - Bereitstellen aufbereiteter Textilien, vorzugsweise Alttextilien, bei welchen Störanteile zumindest weitestgehend entfernt worden sind,
• - Zerkleinern der aufbereiteten Textilien zu einem Mahlgut,
• - Dosieren von Komponenten, wobei die Komponenten das Mahlgut und einen Kunststoff, insbesondere umfassend Kunststoffrezyklat, vorzugsweise ausschließlich umfassend Kunststoffrezyklat, aufweisen,
• - Mischen der Komponenten und
• - Extrudieren der Komponenten durch einen Extruder zu einem Verbundkunststoff.

According to the invention, the above object is achieved by a manufacturing method having the features of the independent claim 1. The method in question comprises the steps:

• - Provision of processed textiles, preferably old textiles, from which impurities have been removed to the greatest possible extent,
• - Shredding the processed textiles into a ground material,
• - Dosing of components, wherein the components comprise the ground material and a plastic, in particular comprising plastic recyclate, preferably exclusively comprising plastic recyclate,
• - Mixing the components and
• - Extruding the components through an extruder to form a composite plastic.

• - 5-70 Gew.-% Textilien und 30-95 Gew.-% Kunststoff, vorzugsweise 10-50 Gew.-% Textilien und 50-90 Gew.-% Kunststoff, insbesondere vorzugsweise 15-35 Gew.-% Textilien und 65-85 Gew.-% Kunststoff,
• - 1-10 Gew.-% Additive,
• - 1-10 Gew.-% Farbpigmente und
• - 1-30 Gew.-% Füllstoffe.

With regard to a composite plastic, the above object is achieved by the features of the independent claim 21. According to this, the composite plastic in question comprises:

• - 5-70 wt.% textiles and 30-95 wt.% plastic, preferably 10-50 wt.% textiles and 50-90 wt.% plastic, particularly preferably 15-35 wt.% textiles and 65-85 wt.% plastic,
• - 1-10 wt.% additives,
• - 1-10 wt.% colour pigments and
• - 1-30 wt.% fillers.

In accordance with the invention, it was first recognized that the pelletizing process step can be eliminated by precisely dosing the ground textiles or the ground material. After the processed textiles have been shredded, no complex step is required to further process the ground material before mixing the components. This makes it particularly easy to produce the composite plastic. This results in a cheaper and faster production process. Furthermore, less energy and fewer natural resources, such as water, are used during the production process.

The textiles to be processed can, for example, be taken as old textiles to a disposal company, where they are collected and, if necessary, sorted and cleaned. The textiles that accrue to a disposal company can generally contain natural fibers and/or chemical fibers. The natural fibers can be plant-based, such as jute, hemp, cotton, linen or sisal, or animal-based, such as wool, silk, angora or cashmere. The chemical fibers can be cellulosic, such as viscose, modal or acetate, or synthetic, such as polyamide, polyacrylic, polyester or elastane. Other fiber materials are not excluded. Mixed fibers are particularly common, which in particular contain cotton together with elastane, polyester or polyacrylic.

During processing, any impurities such as buttons, zippers and other metallic and non-material parts are removed from the textiles, at least as far as possible. The removal of impurities can be carried out by machines using automated and digitalized methods and/or by people. Processing can also include sorting the textiles, for example according to the type of fiber, and cleaning the textiles, especially after the impurities have been removed.

The textiles provided are shredded before dosing to form the ground material in order to enable mixing with the plastic and to obtain a mixture that is as homogeneous as possible. A cutting mill is preferably used to shred the textiles. The choice of the shape and size of the ground material can influence the mechanical properties of the composite plastic in particular. Ground material in powder form can be mixed particularly well and can be used to achieve isotropic material properties of the composite plastic. The term "powdery" is to be understood in the broadest sense in the context of the present disclosure and also includes dust-like components. If the composite plastic has ground material that has a fiber- or fabric-like shape, a fiber composite effect can occur. When subjected to mechanical stress, the fiber- or fabric-like textiles interact with the plastic that forms the matrix of the composite material. This fiber composite effect can lead to an increase in the mechanical properties of the composite plastic, such as stiffness, strength or elongation at break. The term "fibrous or fabric-like form" is to be understood in the broadest sense in the context of the present disclosure and includes individual fibers as well as any type of fiber fabric, such as plain weave, twill or satin fabric.

The ground material can be extracted by a high-performance cyclone and packaged before further use. Packaging can be done by vacuuming, pressing or simply filling into suitable containers.

The components include the ground material and the plastic. The plastic particularly includes plastic recyclate, preferably exclusively plastic recyclate, whereby this plastic recyclate can be post-industrial goods and/or post-consumer goods. The term “post-industrial goods” is to be understood in the broadest sense within the scope of the present disclosure and refers, for example, to plastics from production residues in the manufacture of plastic packaging or other plastic products that cannot be reused in the same process. The term “post-consumer goods” is also to be understood in the broadest sense within the scope of the present disclosure and refers, for example, to plastics that accrue as waste from end consumers, such as households, industry or commerce. The plastic can also include new goods that have not yet been used.

In principle, the dosed components can be mixed in a mixing device and/or in the extruder, whereby the dosed components can be added in any order.

Mixing can be carried out partially or completely in a mixing device. Components mixed in a mixing device can then be fed into the extruder and mixed with other components therein. It is also conceivable that the components are fed into the extruder without prior mixing and are only mixed by the extruder. The plastic and then the textiles can be fed into the extruder first. It is also conceivable that the textiles are added first and then the plastic, or both components are added simultaneously, or partial amounts of both components are added alternately.

The extruder then extrudes the components into the composite plastic. It is conceivable that extruded profiles such as round bars, hollow profiles or other profiles can be produced using the extruder. These extruded profiles can be used to create various constructions, for example in the window, furniture, vehicle, ship, electronics or construction industries. The extruded composite plastic can basically be used for further processing into any product. Standard methods for processing plastics can be used. Alternatively or additionally, films could also be produced from the components using the extruder.

The extruded plastic can advantageously be granulated. A granulator can be used for this purpose, for example. The granulate can be further processed particularly well using primary and forming techniques. Such techniques can include compression molding, injection molding, transfer molding, extrusion, deep drawing, calendering or blow molding.

The processed textiles can advantageously be subjected to pre-shredding to a size of no more than 8 cm, preferably no more than 4 cm, before shredding. This allows a more homogeneous distribution of the sizes of the ground textiles to be achieved in the subsequent shredding step. In addition, pre-shredding can simplify the handling of the textiles, for example by simplifying the use of suction technology to collect the textiles or filling them for temporary storage.

In a further advantageous manner, the ground material or the particles forming the ground material can generally have a grain size of between 0.05 mm and 10 mm. In a particularly advantageous manner, the particles can have at least essentially the same grain size, for example approx. 1 mm. In addition to powdery components, the ground textiles can also have fiber or fabric-like components, which can result in a fiber composite effect. This can lead to an increase in the mechanical properties of the composite plastic, such as stiffness, strength or elongation at break. The mechanical properties of the composite plastic can then exceed those of the pure plastic.

The ground material can also contain natural fibers and/or chemical fibers. The natural and chemical fibers can be in powder form and/or in fibrous form and/or in fabric-like form. Natural fibers are made from renewable raw materials that can be of animal or plant origin. Natural fibers are therefore ecologically sustainable. Chemical fibers have a high tear resistance and a low specific weight. The processing of chemical fibers from used textiles in the composite plastic can also make an important contribution to the recycling of these chemical fibers. Environmentally harmful landfilling or incineration of the chemical fibers is not necessary.

In a further advantageous manner, the ground material can contain more than 50% by weight of chemical fibers, in particular more than 99% by weight of chemical fibers, or more than 50% by weight of natural fibers, in particular more than 99% by weight of natural fibers. The weight proportions of the natural and chemical fibers can be specifically selected so that the desired properties of the composite plastic are achieved. The selection can be made taking ecological and/or material-mechanical aspects into account.

It is also conceivable that the plastic contains thermoplastic. Thermoplastics can be reversibly melted and plastically deformed by applying heat with little effect on the material properties. This particularly improves the recyclability of the composite plastic. Thermoplastics also have a high resistance to chemical attack and high impact strength. Thermoplastics are characterized by their weldability and good processability, for example by injection molding, extrusion or vacuum deep drawing. In addition, high-quality aesthetic surfaces can be created.

In a further advantageous manner, the plastic can comprise plastic based on fossil raw materials, preferably wherein the plastic based on fossil raw materials comprises polyethylene (PE), for example high-density polyethylene (HDPE) and/or low-density polyethylene (LDPE) and/or low-low-density polyethylene (LLDPE), and/or polyolefin mixture (POM) and/or polypropylene (PP) and/or polyethylene terephthalate (PET). Plastic based on fossil raw materials is available particularly cheaply. When using recycled plastic, the production of new plastic from fossil raw materials is avoided, which in particular improves the ecological sustainability of the composite plastic.

Advantageously, the plastic can comprise bio-based plastic, preferably wherein the bio-based plastic comprises polylactic acid/polylactide (PLA) and/or polyhydroxybutyric acid (PHB) and/or plastics based on renewable raw materials such as chitin, lignin, gelatin, casein, sugar, starch, vegetable oils and other proteins. It is advantageous that the production of bio-based plastics does not use fossil fuels. Saves raw materials and CO _2. This also improves the ecological sustainability of the composite plastic.

It is also conceivable that the plastic includes the composite plastic. The composite plastic can be recycled after use by being added as a component during production. This means that the composite plastic itself can also be recycled.

It is expressly pointed out again that regardless of which plastic or plastics are used as components, they can only be recycled material or recyclates.

In a further advantageous manner, the components can comprise at least one additive. The properties of the composite plastic can be improved by adding additives. The additives are preferably first mixed with the plastic and then this mixture is mixed with the textiles. It is also conceivable that the additives are mixed into a mixture comprising plastic and textiles.

The at least one additive can comprise a stabilizer, preferably wherein the stabilizer comprises antioxidants, in particular phenols and/or amines and/or phosphines, and/or co-stabilizers and/or UV stabilizers, in particular carbon black and/or σ-hydroxybenzophenone and/or dialkyldithiocarbamates. The use of a stabilizer increases the resistance of the composite plastic, in particular to environmental influences. The resistance can, for example, include resistance to extreme thermal influences in summer and winter, to oxygen or to UV radiation. For example, when the composite plastic is used to manufacture furniture that is used outdoors, a stabilizer can counteract fading as a result of exposure to sunlight.

Furthermore, the at least one additive can comprise an adhesion promoter, preferably wherein the adhesion promoter comprises carboxylated polyethylene functionalized with maleic anhydride and/or ethylene-octene copolymer functionalized with maleic anhydride. The adhesion promoter increases the physical and/or chemical bonding forces in the interface between textile and plastic. This leads to increased strength, increased resistance, in particular to moisture and chemical effects, as well as increased tolerance of the composite material to surface contamination.

It is conceivable that at least one additive includes an odor neutralizer. This reduces the odor pollution of the components, especially old textiles and recycled plastics.

In a further advantageous manner, the at least one additive can comprise a flame retardant, preferably wherein the flame retardant comprises aluminum hydroxide and/or magnesium hydroxide and/or expanded graphite and/or phosphorus and/or a modification of phosphorus. The flame retardant reduces the flammability of the composite plastic, whereby the occurrence of fires can be limited, slowed down or prevented. The use of the flame retardant is particularly advantageous if the composite plastic is used to manufacture furniture or components, in particular for electrical devices. The flame retardant can be halogen-free and REACH-compliant in order to provide a composite plastic with as few pollutants as possible. The chemicals regulation REACH, Regulation (EC) No. 1907/2006 , and its ongoing updates, regulates, among other things, the authorisation and restriction of chemicals for the manufacture of products in the European Union.

It is also conceivable that the components include color pigments, in particular bio-based and/or chemically based color pigments. This makes it possible to achieve any coloring of the composite plastic or the products made with it. The color pigments can be in the form of powder and/or granules. The color pigments are preferably first mixed with the plastic and then this mixture is mixed with the textiles. It is also conceivable that the color pigments are added to a mixture comprising plastic and textiles.

According to an advantageous development, the components comprise fillers, preferably reinforcing fibers, in particular glass and/or carbon fibers, and/or talcum and/or chalk. Reinforcing fibers made of glass or plastic can increase the rigidity, strength and elongation at break of the composite plastic and reduce the tendency of the composite plastic to creep. Glass fibers are characterized by a high resistance to chemical influences and UV radiation. They do not conduct electricity, which is particularly advantageous when the composite plastic is used for components for electrical devices. Glass fibers are also inexpensive to obtain. In addition to a low specific weight, carbon fibers have particularly high rigidities and strengths. The resistance to long-term cyclic stress The stress is very high, so the use of carbon fibers can be advantageous, especially when the composite plastic is used for components subject to high dynamic stress. Talc or chalk can increase the stiffness, strength and dimensional stability. In addition, the extrusion properties can be improved. The fillers are preferably first mixed with the plastic and then this mixture is mixed with the textiles. It is also conceivable that the fillers are added to a mixture comprising plastic and textiles.

Another advantage is that the components can be dosed using a gravimetric and/or volumetric dosing system. This enables particularly precise, controlled and easily reproducible dosing of the ground material. The use of a differential scale is particularly advantageous here, as it is well suited to dosing bulk materials such as the ground material.

It is conceivable that the temperature in the extruder is at most 240 °C, in particular between 180 °C and 240 °C. In this temperature range, the components can be processed particularly gently. Irreversible deterioration of the mechanical properties of the plastic or textiles is thus avoided. In a temperature range between 180 °C and 240 °C, the components are also particularly easy to mix. This leads to a component mixture with a high degree of homogeneity.

In a particularly advantageous manner, the extruder can be a twin-screw extruder with two transport screws, whereby the transport screws rotate in the same or opposite directions. A particularly good mixing result can be achieved with a twin-screw extruder.

• 1 Schritte eines Verfahrens gemäß einer Ausführungsform der vorliegenden Erfindung.

There are now various possibilities for designing and developing the teaching of the present invention in an advantageous manner. For this purpose, reference is made on the one hand to the claims subordinate to claim 1 and on the other hand to the following explanation of preferred embodiments of the invention with reference to the drawing. In connection with the explanation of the preferred embodiments of the invention with reference to the drawing, generally preferred embodiments and developments of the teaching are also explained. The drawing shows

• 1 Steps of a method according to an embodiment of the present invention.

1 shows in schematic form process steps for producing a composite plastic according to an embodiment of the present invention. It should be expressly pointed out that the implementation of process steps does not necessarily have to be carried out in the 1 must be done in the order shown.

In a first step S1, processed old textiles are provided. The most disruptive parts of the old textiles have been removed (step S101). These disruptive parts can include buttons, zippers and other metallic and non-material parts.

The processed used textiles are then pre-shredded in step S2 using a shredder to a size of no more than 8 cm, preferably no more than 4 cm.

In step S3, the pre-shredded old textiles are further shredded. For example, a cutting mill is used, which produces ground old textiles with a grain size of between 0.05 mm and 10 mm, whereby the grain size is advantageously at least essentially uniform, for example 1 mm. The ground old textiles or the ground material can be sucked off by a high-performance cyclone and packaged before further use.

The components are then dosed and mixed. First, the plastic and additives, for example comprising a stabilizer and/or an adhesion promoter and/or an odor neutralizer and/or a flame retardant, and, depending on the properties of the composite plastic to be achieved, color pigments and/or fillers, such as reinforcing fibers and/or talcum and/or chalk, are dosed (step S4). Then, in step 5, the dosed plastic and the dosed additives are mixed with a mixing device. In addition, color pigments and/or fillers can be mixed with the plastic and the additives as part of this mixing process (step S501).

In step S6, the premixed components, including the plastic, the additives and, if applicable, the color pigments and/or fillers, as well as the ground material, are then dosed into a twin-screw extruder. In this, all components are mixed (step S7) and extruded into a composite plastic (step S8).

In principle, the dosed components, which may include the ground material, the plastic, the additives, the color pigments or the fillers, can be mixed in the mixing device and/or in the extruder. The dosed components can be added in any order.

Finally, the composite plastic is processed into granules using a granulator (step S9). The granules produced in this way can be further processed particularly well using primary and forming techniques such as injection molding or deep drawing, for example to make furniture.

With regard to further advantageous embodiments of the method according to the invention, reference is made to the general part of the description and to the appended claims in order to avoid repetition.

Finally, it should be expressly pointed out that the embodiments of the method according to the invention described above serve only to explain the claimed teaching, but do not limit it to the embodiments.

List of reference symbols

S1

Providing old textiles

S101

Removal of contaminants

S2

Pre-shredding of old textiles

S3

Shredding old textiles

S4

Dosing of plastic, additives, color pigments and fillers

S5

Mixing the plastic with additives

S501

Mixing the plastic and additives with color pigments and/or fillers

S6

Dosing of the premixed components and the ground material

S7

Mixing the components in the twin-screw extruder

S8

Extruding the composite plastic

S9

Granulating the composite plastic

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• EP 3922665 A1 [0004]
• US 10047462 B1 [0005]
• EC 1907/2006 [0033]

Claims (21)

Method for producing a composite plastic, comprising the steps: - providing processed textiles (S1), preferably used textiles, from which impurities have been removed at least to the greatest extent possible (S101), - comminuting the processed textiles to form a ground material (S3), - dosing components (S4, S6), the components comprising the ground material and a plastic, in particular comprising recycled plastic, preferably exclusively comprising recycled plastic, - mixing the components (S5, S501, S7) and - extruding the components through an extruder to form a composite plastic (S8). Procedure according to Claim 1 , characterized in that the extruded composite plastic is granulated (S9). Procedure according to Claim 1 or 2 , characterized in that the processed textiles are subjected to pre-shredding to a size of no more than 8 cm, preferably no more than 4 cm, before shredding (S2). Method according to one of the Claims 1 until 3 , characterized in that the particles forming the ground material have a grain size between 0.05 mm and 10 mm (S3). Method according to one of the Claims 1 until 4 , characterized in that the ground material comprises natural fibres and/or chemical fibres. Procedure according to Claim 5 , characterized in that the ground material contains more than 50 wt.% chemical fibres, in particular more than 99 wt.% chemical fibres, or more than 50 wt.% natural fibres, in particular more than 99 wt.% natural fibres. Method according to one of the Claims 1 until 6 , characterized in that the plastic comprises thermoplastic. Method according to one of the Claims 1 until 7 , characterized in that the plastic comprises plastic based on fossil raw materials, preferably wherein the plastic based on fossil raw materials comprises polyethylene (PE), for example high-density polyethylene (HDPE) and/or low-density polyethylene (LDPE) and/or low-low-density polyethylene (LLDPE), and/or polyolefin mixture (POM) and/or polypropylene (PP) and/or polyethylene terephthalate (PET). Procedure according to one of the Claims 1 until 8th , characterized in that the plastic comprises bio-based plastic, preferably wherein the bio-based plastic comprises polylactic acid/polylactide (PLA) and/or polyhydroxybutyric acid (PHB) and/or plastics based on renewable raw materials such as chitin, lignin, gelatin, casein, sugar, starch, vegetable oils and other proteins. Method according to one of the Claims 1 until 9 , characterized in that the plastic comprises the composite plastic. Procedure according to one of the Claims 1 until 10 , characterized in that the components comprise at least one additive. Procedure according to Claim 11 , characterized in that the at least one additive comprises a stabilizer, preferably wherein the stabilizer comprises antioxidants, in particular phenols and/or amines and/or phosphines, and/or co-stabilizers and/or UV stabilizers, in particular carbon black and/or σ-hydroxybenzophenone and/or dialkyldithiocarbamates. Procedure according to Claim 11 or 12 , characterized in that the at least one additive comprises an adhesion promoter, preferably wherein the adhesion promoter comprises carboxylated polyethylene functionalized with maleic anhydride and/or ethylene-octene copolymer functionalized with maleic anhydride. Method according to one of the Claims 11 until 13 , characterized in that the at least one additive comprises an odor neutralizer. Method according to one of the Claims 11 until 14 , characterized in that the at least one additive comprises a flame retardant, preferably wherein the flame retardant comprises aluminum hydroxide and/or magnesium hydroxide and/or expandable graphite and/or phosphorus and/or a modification of phosphorus. Procedure according to one of the Claims 1 until 15 , characterized in that the components comprise color pigments, in particular bio-based and/or chemically based color pigments. Method according to one of the Claims 1 until 16 , characterized in that the components comprise fillers, preferably reinforcing fibers, in particular glass and/or carbon fibers, and/or talc and/or chalk. Method according to one of the Claims 1 until 17 , characterized in that the dosing of the components is carried out by means of a gravimetric and/or volumetric dosing system. Method according to one of the Claims 1 until 18 , characterized in that the temperature in the extruder is at most 240 °C, in particular between 180 °C and 240 °C. Method according to one of the Claims 1 until 19 , characterized in that the extruder is a twin-screw extruder with two transport screws, wherein the transport screws rotate in the same or opposite directions. Composite plastic, preferably produced according to the process of any of the Claims 1 until 20 , with: - 5-70 wt.% textiles and 30-95 wt.% plastic, preferably 10-50 wt.% textiles and 50-90 wt.% plastic, particularly preferably 15-35 wt.% textiles and 65-85 wt.% plastic, - 1-10 wt.% additives, - 1-10 wt.% color pigments and - 1-30 wt.% fillers.

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