Paper machine clothing

Abstract

The invention relates to a clothing for a machine for producing or processing a fibrous web, said clothing consisting of one or more polymer materials, wherein at least some of the polymer materials consist of recycled polymer (A) and / or bio-based or CO2-based polymers (B). The invention is characterized in that at least 20 wt.%, in particular at least 25 wt.%, of the clothing consists of recycled polymer (A) and / or bio-based or CO2-based polymers (B), and among the polymer materials, a main component (X) makes up at least 70 wt.%, in particular 80 wt.% or more, of the total weight of the clothing.

Description

[0001] covering

[0002] The invention relates to a clothing for a machine for producing or processing a fibrous web according to the preamble of claim 1.

[0003] Paper machine clothing (PMC) is now made from synthetic polymers. The polymers are extruded and spun into monofilaments, twisted yarns, multifilament yarns, and fibers or staple fibers. These are then used to produce woven fabrics, nonwovens, and nonwovens as intermediate products. These fabrics, nonwovens, and nonwovens are then converted into clothing after further processing steps – typically forming fabrics, press felts, dryer fabrics, spiral fabrics, but also support structures for transfer belts, shoe press sleeves, or special processing belts.

[0004] The main components of paper machine clothing are typically various polyamides such as PA6, PA6.6, PA6.10, PA6.12, polyesters such as PET and PBT, or PPS and other polymer materials. Components such as fibers, adhesive polymers, monofilaments, or functional layers made of elastomeric materials such as polyurethanes are also sometimes used.

[0005] The various polymers used for the coverings are predominantly made from fossil raw materials such as petroleum. Given the increasing efforts to reduce the use of fossil raw materials, several ideas are known from the state of the art to reduce dependence on fossil raw materials in the production of coverings. For example, EP 4 155 456 A1 describes coverings comprising a thermoplastic elastomer that is partially based on bio-based or CO2-based raw material.

[0006] EP 4202 095 A1 discloses multifilaments for use in press felts, wherein these multifilaments are partly made of bio-based materials or recycled material.

[0007] The utility model DE 2020 21101509 U1 shows an industrial textile, in particular a paper machine clothing, which consists partly or entirely of at least one biopolymer produced using 2,5-furandicarboxylic acid.

[0008] A disadvantage of the current state-of-the-art solutions, however, is that while attempts are made to partially eliminate the use of fossil raw materials in the production of the coverings, the entire life cycle of the coverings is not considered. The coverings described there are usually either landfilled or incinerated, as no recycling processes are established.

[0009] The object of the invention is therefore to propose a covering that has a measurably reduced CO2 footprint compared to known coverings. It is also an object of the invention to improve the entire life cycle of a covering with regard to its CO2 footprint. Finally, it is an object of the invention to significantly improve the recyclability of the coverings.

[0010] The object is achieved according to the invention by an embodiment according to the independent claim. Further advantageous embodiments of the present invention can be found in the subclaims. A clothing for a machine for producing or processing a fibrous web is proposed, wherein the clothing consists of one or more polymer materials, wherein at least some of these polymer materials consist of recycled polymer (A) and / or bio-based or CO2-based polymers (B).

[0011] It is provided that at least 20 wt%, in particular at least 25 wt% of the covering consists of polymer recyclate (A) and / or bio-based or CO2-based polymers (B) and that among the polymer materials a main component (X) makes up at least 70 wt%, in particular 80 wt% or more of the total weight of the covering.

[0012] Designs of the coverings as described above can therefore, for example, comprise: a) At least 20% by weight of recycled polymer (A) b) At least 20% by weight of recycled polymer (A) plus additional bio-based or CO2-based polymers (B) c) Less than 20% by weight of recycled polymer (A) plus additional bio-based or CO2-based polymers (B), whereby the total proportion of recycled polymer (A) plus bio-based or CO2-based polymers (B) is at least 20% by weight or at least 25% by weight. d) In the designs according to c), it is usually advantageous if at least 10% by weight of recycled polymer (A) is provided.

[0013] The invention is not limited to the embodiments a) to d).

[0014] Bio-based polymers (bio-based plastics) are polymeric plastics produced from renewable raw materials. Bio-based plastics derived from plants only release as much CO2 during decomposition or energy use as they absorbed during the growth phase. This gives them an advantage over petrochemical-based plastics in terms of CO2 emissions based on the raw materials. CO2-based polymers are plastics in which CO2 is incorporated into the plastics as a carbon source. They can be used to establish an efficient carbon cycle economy and reduce the use of fossil resources.

[0015] What chemically recycled and bio-based polymers have in common is a significantly lower carbon footprint compared to their fossil-based counterparts. Therefore, the use of such polymers in coverings is advantageous.

[0016] However, only a comparatively small amount of recycled polymer is currently available. Much of the plastic used is either a blend or heavily contaminated, making chemical recycling difficult. The goal is not to produce a polymer blend made from different polymer materials.

[0017] The inventors therefore sought ways to recycle the coverings themselves after use. However, most of the coverings currently in use are unsuitable for polymer recycling, particularly due to their material blends.

[0018] For this purpose, it is important that the polymer materials from which the covering is constructed have a main component (X) which accounts for at least 70% by weight, in particular 80% by weight or more of the total weight of the covering.

[0019] An even higher proportion of the main component (X) of 85% or 90% by weight is advantageous. It can also be provided that the entire covering is composed exclusively of the main component (X).

[0020] The weight percentage (wt%) is determined under dry conditions at a standard textile climate of 20+-2 °C, 56+-4% relative humidity, conditioned for 12 hours. Soiling is not included in the mass. Fabrics such as forming and drying fabrics usually consist of monofilaments that are converted into a flat structure in a weaving process. Monofilaments are currently manufactured from the polymer materials described above, which are generally made predominantly from fossil raw materials. To ensure high stability and low elongation of the monofilaments, they are made from high-molecular-weight polymer variants and stretched after filament extrusion. Monofilaments with property profiles such as shrinkage, elongation, tear strength, hydrolysis resistance, etc. are specifically manufactured.Low variability in these adjusted properties is particularly important and advantageous, as otherwise, later fabrics and coverings may contain areas with structural differences or deviations in other functional properties that impair the performance of the coverings. It has been shown that this is often not possible with mechanically recycled materials (high variability in yarn extrusion and drawing).

[0021] Chemical recycling is also an alternative to mechanical recycling. The chemical recycling of industrial polymers and the production of polymer recyclate are well-known. This process allows plastic waste to be broken down into its building blocks (monomers or oligomers) and, after purification, converted back into technical polymers (polymerization). Alternatively, basic raw materials for the production of polymers can be obtained using pyrolysis processes, although the polymer building blocks usually have to be resynthesized.

[0022] In the context of this invention, recyclability, in particular chemical recyclability, is assumed if the covering consists of a polymer material X as the main component with >70% by weight.

[0023] At lower proportions of X, chemical recycling is often not economically feasible, since usually only the main component X can be recycled, and other polymer materials only arise as thermally recyclable waste and often even complicate the recycling of the main component X. The economic viability of chemical recycling increases with increasing proportions of polymer material X.

[0024] It is particularly advantageous if at least 20% by weight, in particular at least 25% by weight, of the polymer of the main components (X) itself consists of polymer recyclate (A). It is particularly advantageous if more than 30% by weight or more than 40% by weight of the main components (X) consists of polymer recyclate (A).

[0025] Due to the high proportion of recycled material in the main component, the quality of this recycled material must be very good and must not differ significantly from the quality of a new polymer.

[0026] Due to the high proportion of more than 70 wt% of a polymer material X as the main component, such a high-quality recyclate can be produced from the used coverings, especially if the materials contained therein can be separated in a recycling process without the main component containing significant traces of the secondary components.

[0027] By combining a high proportion of the main component (X) in the total weight of the covering with a high proportion of recycled material in this main component, the CO2 footprint can also be reduced particularly efficiently.

[0028] The high proportion of the main component X enables sufficient pure recycling of at least the majority of the covering, while the high proportion of recycled material in the main component means that a large amount of the recycled material obtained from the recycling of the coverings or from other sources can be reused in a covering.

[0029] The recycling of the coverings can be carried out, in particular, at the site of production. This eliminates a large portion of transport, as the old covering can be transported back with the new covering when it is delivered to a customer. In general, the other materials, apart from the main component X, can also be made entirely or partially from recycled or bio-based or CO2-based materials.

[0030] According to aspects of the invention, a variety of different covering types can be produced. This will be explained using a few examples. However, the invention is not limited to these examples:

[0031] Example 1

[0032] The fabric can be a dryer fabric, especially a woven dryer fabric. Dryer fabrics usually consist of monofilaments and / or twisted yarns, with at least the longitudinal or transverse threads forming the fabric, or both, consisting at least partially of recycled polymer (A) and / or bio-based or CO2-based polymer material (B).

[0033] The main material (X) can be a hydrolysis-stabilized polyester, preferably a PET or a polyphenylene sulfide (PPS), which is incorporated into the covering in particular in the form of filaments and / or threads.

[0034] It is known to those skilled in the art that a monofilament made of PET or PPS can also contain additives, pigments and other additives in total up to approximately 10%.

[0035] Example 2:

[0036] The covering can also be a press felt. Press felts typically consist essentially of components such as monofilaments, multifilaments, twisted yarns, staple fibers, etc.

[0037] A polyamide can be used as the main material (X).

[0038] Polyamide 6 is particularly preferred. Some of the components (<30 wt%) can also consist of other polymer materials Y, for example PA6.12, PA6.10, elastic polyurethanes, polyamide copolymers, etc. In this case, it is important that the main material (X) consists of a single type of polyamide. To achieve this, it may be necessary for this type of polyamide to be used both for the basic structure - e.g. in the form of a base fabric - and for the staple fibers of the nonwoven overlay. High weight proportions of the main component X (e.g. 80 wt% polyamide 6) can often not be achieved with the basic structure alone. In this case, the material of the nonwoven overlay and the basic structure must be coordinated with one another with regard to recyclability.

[0039] Example 3:

[0040] The fabric can also be a woven forming fabric made of monofilaments, with the main component (X) being a polyamide or a polyester—particularly PET. A portion of the components (<30%) can also consist of other polymer materials Y. Thus, a combination of a main component (X) of PET with smaller amounts of a polyamide is conceivable.

[0041] Alternatively, a polyamide (e.g. polyamide 6) can form the main component (X), and another polyamide (e.g. polyamide 6.12) can be contained in smaller quantities in the forming fabric.

[0042] Example 4:

[0043] The covering can also be a spiral screen comprising spiralized monofilaments as well as pintle wires and optional filling threads, wherein the main material (X) is hydrolysis-stabilized polyester, preferably a PET or PPS.

[0044] It is known to those skilled in the art that a PET monofilament can generally also contain additives, pigments and other additives in total up to approximately 10%.

[0045] As already described, the present invention aims, among other things, to reduce the CO2 footprint of the coverings. Product Carbon Footprint (PCF) modeling can be used, in particular, to determine the CO2 footprint. The Product Carbon Footprint (PCF) modeling was performed within the scope of this application using LCA for Experts Software System and Database for Life Cycle Engineering from Spher Solutions GmbH (version 10.7.0.183).

[0046] The declared unit is 1 kg of fabric, unpackaged, at the declarant's factory gate. The calculation was performed for the reference year 2022. The system boundaries include raw materials, inbound transport, renewable energy (purchased and / or self-generated), own operations, and exclude packaging and outbound transport – this corresponds to the "cradle-to-gate" definition (partial carbon footprint) in linear product systems.

[0047] The modeling is based on primary data combined with cradle-to-gate background data. The primary data from the notifying party's plants refer to average production conditions in 2022. The background data is no older than five years. Background data sources are the MLC databases 2023 Edition from Sphere Solutions GmbH. The cut-off rule for the inventory is set at less than 1% of the total environmental impacts. When sourcing and selecting the available data, attention was paid to representativeness, consistency, accuracy, and geographical and temporal relevance.

[0048] The LCIA characterization method focuses on greenhouse gas emissions. The characterization method "ISO14067 GWP100 (based on IPCC AR6), Fossil Greenhouse Gas Emissions [kg CO2 eq.]" from the LCA for Experts Software Solution System was used.

[0049] The calculation of the Product Carbon Footprint (PCF) follows the requirements and guidelines of ISO 14067:2018. This standard allows for discretionary decisions, which lead to a range of possible results. Results from other sources may be based on different decisions. Therefore, a comparison of the present quantitative PCF results with other studies is only possible if the methodological and data-related assumptions are the same. The following table shows examples of the PCF reductions that can be achieved with coverings as described above. The table shows examples of coverings manufactured using recycled material. Similar effects can also be achieved with designs using bio-based or CO2-based polymers.

[0050] It is clear that the use of recycled material alone significantly reduces the CO2 footprint of the coverings. This analysis does not even take into account the fact that coverings according to the present invention are themselves recyclable. This provides a further positive effect on reducing the CO2 footprint.

Claims

Patent claims 1 . Clothing for a machine for producing or processing a fibrous web, wherein the clothing consists of one or more polymer materials, wherein at least a part of these polymer materials consists of polymer recyclate (A) and / or bio-based or CO2-based polymers (B), characterized in that at least 20% by weight, in particular at least 25% by weight of the clothing consists of polymer recyclate (A) and / or bio-based or CO2-based polymers (B) and that among the polymer materials a main component (X) makes up at least 70% by weight, in particular 80% by weight or more of the total weight of the clothing.

2. Covering according to claim 1, characterized in that at least 20% by weight, in particular at least 25% by weight, of the polymer of the main components (X) consists of polymer recyclate (A).

3. Fabric according to one of the preceding claims, characterized in that the fabric is a dryer fabric, and the main material (X) is a hydrolysis-stabilized polyester, preferably a PET or a polyphenylene sulfide (PPS), which is incorporated into the fabric in particular in the form of filaments and / or twisted yarns.

4. Covering according to one of claims 1 or 2, characterized in that the covering is a press felt, wherein the main material (X) is a polyamide, particularly preferably a polyamide 6.

5. Fabric according to one of claims 1 or 2, characterized in that the fabric is a woven forming fabric which is formed from monofilaments, wherein the main material (X) is a polyamide or a polyester - especially PET.

6. Covering according to one of claims 1 or 2, characterized in that the covering is a spiral sieve which comprises spiralized monofilaments as well as pintle wires and optional filling threads, wherein the main material (X) is hydrolysis-stabilized polyester, preferably a PET or PPS.

7. Clothing, in particular according to one of claims 1 or 2, wherein the clothing a) is a press felt or a spiral screen, and the clothing has a product carbon footprint (PCF) of less than 8 kg CO2 / kg, preferably less than 6 kg CO2 / kg or b) is a forming screen, and the clothing has a product carbon footprint (PCF) of less than 7 kg CO2 / kg, preferably less than 6 kg CO2 / kg or c) is a dryer screen, and the clothing has a product carbon footprint (PCF) of less than 3.5 kg CO2 / kg, preferably less than 3 kg CO2 / kg.

Images