EASILY RECYCLABLE BRISTLES

Description

[0001] The present invention relates to bristle products that can be easily recycled because their components comprise or consist of the same material.

[0002] In the prior art, a variety of materials, or at least a combination of materials, is generally used to ensure a certain durability of the bristle. In toothbrushes, for example, metal plates are used alongside plastic on the monofilaments or bristles. The bundled bristles are looped around these metal plates and pressed into the hole in the head of the bristle. An alternative is to coat the bundled bristles with flowing plastic, which is then anchored in the cavities of the bristle head using the well-known bundle injection molding process.

[0003] In a variation of this procedure, the bristle material is combined with a base plastic that becomes plastic when heated. In the so-called bundle insertion technique, the bristle bundles are coated with this base plastic and, while heated, inserted into the cavities of the head.

[0004] An overview of these techniques can be found, for example, in the dissertation by Susanne Wurbs at the Medical Faculty of the Georg-August University of Göttingen, 2011. An illustration is shown in the video "How Toothbrushes Are Made", https: / / youtube.com / watch?v=i2pIIaI6HmU&feature=youtu.be.

[0005] A particular problem with plastic brushes is their disposal. Although keeping our environment clean has long been a public concern, recycling polymers still presents a major technical challenge.

[0006] Recycling in the sense of a materialProcessing is only found in 33% of all plastics, as explained, for example, in an internet article by Hunold + Knoop Kunststofftechnik, https: / / www.hunold-knoop.de / kunststoffwissen / kunststoffblog / details / kunststoff-recycling-3-methoden).

[0007] In this process, used parts are shredded, cleaned, and separated by type. Metallic components can be removed through melt filtration, shredding, separation, or density separation. Thermoplastics are then melted at high temperatures and reprocessed.

[0008] However, the more types of plastic are used in the item to be recycled, the more complex the separation becomes. For complex items like a toothbrush, separation is not economically feasible. Without separation by type, the material quality of the item made of recycled plastic is expected to be reduced, or at least very difficult to control.

[0009] Only 1% of all plastics are recycled as raw materials recycled. In such processes, the polymer chains in the plastic are broken down. This creates monomers, oils, and gases that can be processed into new plastics. This process is also suitable for mixed and contaminated materials. Of course, the breakdown of polymer chains in the plastic depends on the combination of different plastics. One example of this raw material recycling is the non-selective thermochemical production of so-called pyrolysis oil, which involves converting liquefied polymers in a cracker (https: / / www.basf.com / global / de / who-weare / sustainability / we-drive-sustainable-solutions / circular-economy / mass-balanceapproach / chemcycling.html).

[0010] In so-called monomer recycling, polymer chains are converted into monomer units through selective chemical reactions. One example is the cleavage of nylon 6 into the monomer caprolactam. The reaction products can be partially repolymerized after purification.

[0011] It is well known that inclusions of other polymers in a basically homogeneous plastic matrix behave like foreign bodies. Many polymers are chemically incompatible with each other, meaning they develop limited adhesion when combined and melted. Furthermore, different polymers are generally immiscible. If necessary, so-called "compatibility enhancers" must be used to achieve the desired toughness modification.

[0012] In the current state of the art, it is generally observed that even with small amounts of one plastic in another, the properties of the matrix plastic are reduced the more the chemical structure of its components differs. Depending on the type of plastic component included or intentionally added, completely unsatisfactory results can also occur.

[0013] In general, the purity of plastic waste is of increasing interest. The demand to reduce the variety of plastics used is also gaining importance. An overview can be found at "Kunststoffe.de", https: / / www.kunststoffe.de / themen / basics / recycling / werkstoffliches-recycling / artikel / recyclingvon-mischkunststoffen-1 001658. html. WO 2017 / 076839 A1 discloses body brushes with injected bristles. The components of the brushes can consist of the same or different components. The Wikipedia article "Polyamide" states that polyamide is used in toothbrushes, especially bristles (Anonymous: Polyamide, Wikipedia, December 31, 2019, https: / / de.wikipedia.org / wiki / Polyamide). EP 2202260 B1 describes polyamide elastomers and molded parts made from them. They can be used, for example, as brushes.In addition, the pre-filed and subsequently published WO 2021 / 069693 A2 discloses oral hygiene products such as toothbrushes.

[0014] The objective of the invention was therefore to provide plastic objects that meet the aforementioned requirements and problems. Furthermore, monofilaments or bristles should exhibit a minimum degree of resilience and be non-brittle.

[0015] The subject of the invention is therefore a bristle product comprising the components: Monofilament or bristles, and at least one head, handle, and / or neck, wherein the components comprise or consist of polymers from the same polymer class, selected from polymer, and wherein the polymer class is selected from polyamide, characterized in that the polymer is a polymer of the monomers w-aminododecanoic acid and / or laurolactam.

[0016] The invention is explained in more detail below.

[0017] The bristle product according to the invention can have at least one grip element on its head, on the handle, and / or on its neck, wherein the at least one grip element comprises or consists of polymers from the same polymer class (e.g. polyamide and polyether block amide) as the components of the bristle product.

[0018] Preferably, the components of the brush material should be made of polymers of the same polymer class. Such ideal purity significantly simplifies recycling.

[0019] It may further be advantageous if the polymer or a copolymer of the disclosed bristle product is additionally selected from polymers of the monomers hexamethylenediamine / azelaic acid, hexamethylenediamine / dodecanedioic acid, 11-aminoundecanoic acid, tetramethylenediamine / adipic acid, dodecanediamine / dodecanedioic acid, caprolactam / laurolactam, hexamethylenediamine / decanedioic acid, 1,10-decamethylenediamine / 1,10-decanedioic acid.

[0020] The polymer of the disclosed brushware may additionally be selected from polyethylene terephthalate (PET), acid-modified polyethylene terephthalate (PETA), glycol-modified polyethylene terephthalate (PETG), polybutylene terephthalate (PBT), acid-modified polycyclohexylenedimethylene terephthalate (PCT-A), and glycol-modified polycyclohexylenedimethylene terephthalate (PCT-G).

[0021] Some materials are also known to the person skilled in the art under the following names, which are also used in this disclosure. Polyamide from:

[0022] Hexamethylenediamine / Azelaic acid PA6.9 Hexamethylenediamine / dodecanedioic acid PA6.12 11-Aminoundecanoic acid PA11 Laurolactam or ω-aminododecanoic acid PA12 Tetramethylenediamine / adipic acid PA4.6 Dodecanediamine / dodecanedioic acid PA12.12 Caprolactam / Laurollactam PA6.12 1,10-decamethylenediamine / 1,10-decanedioic acid PA10.10 Hexamethylenediamine / Decanedioic acid PA610 polyamide PA Polybutylene terephthalate PBT Polypropylene PP Polyether block amide PEBA

[0023] Most preferably, the bristle article according to the invention can be a toothbrush.

[0024] The invention is explained in more detail using the following examples.

[0025] In all examples, toothbrushes made of different materials or different material combinations were subjected to conventional recycling processes. The suitability for mechanical and chemical recycling, as well as the adhesion of the materials, were evaluated.

[0026] Within the scope of the invention, Suitability for mechanical recycling means that a largely pure polymer can be recovered. "Poor" suitability means that mixtures of different polymers or differently modified polymers are present, which have a negative influence on, for example, color, mechanical properties, or toxicology. Suitability for monomer recycling means that a largely pure polymer can be recovered. Since small amounts of impurities can be removed, the process can, in principle, be used more broadly than mechanical recycling. A "poor" suitability here means that complex additional separation steps are required due to the complex material mixtures used. Adhesion of the materials means that both materials cannot be separated under stress. This can be tested, for example, using a tensile test according to DIN EN ISO 527. Cleaning effect means that the bristle material can technically achieve the required stiffness from soft to hard. The resilience of the bristles meets the requirements and the bristles fatigue more slowly than other materials. Suitability for filament extrusion means that small filament diameters for bristle material can be manufactured without filament breakage. Semi-crystalline thermoplastics enable stretching in the direction of force during filament extrusion to strengthen the material. Break resistance means that the bristle material is not brittle and does not break even after long use when brushing teeth. Sources for

[0027] PA612: VESTAMID ®< D16, Evonik; PA12: VESTAMID ®< LX9039, Evonik; SEBS: Delene 1010, Lingen Plastic Rubber; PMMA: ACRYLITE ®< SuPure, Röhm; PC: 4Lex 10F10000, 4Plas; PS: ACLCOM MED PS, MOCOM; PBT: VESTODUR 2000, Evonik.

[0028] Comparative examples 1 - 6. Toothbrush comprising a material combination of PA6.12 and PP, PA6.12 and PET, PA6.12, PP and block copolymer of styrene-ethylene-butylene-styrene (SEBS), PA6.12 and PE, PA612 and PU, PA6.12 and PA12.

[0029] Comparative examples 7 - 9. Toothbrushes whose bristles and handle are made of the same material: PMMA, PS, or SEBS. However, the bristles themselves do not have sufficiently good properties.

[0030] Examples 1 - 3. Toothbrush whose bristles, head, handle, and neck are each made of the same polymer: PA6.12, PA12, or PBT. Examples 1 and 3 are comparative examples.

[0031] Examples 4 and5. Toothbrushes whose bristles, head, handle, and neck are each made of the same polymer, namely PBT or PA12, and which additionally have a grip element made of PEBA based on PA12 or PEBA based on PA6.12. The ratings are summarized in Table 1. The symbols are assigned the following meaning: "-" "bad" "+" "good" "s" "too brittle" "b" "only conditionally" "w" "too soft" Table 1. Assessments of the recyclability of the toothbrush, the adhesion of the materials and assessment of the material as a bristle product. bristles Head, handle and neck Grip element Suitability for mechanical recycling Suitability for monomer recycling Liability of materials Cleaning effect Suitability for filament extrusion Break resistance Comparison example 1 PA6.12 PP - - - + + + Comparison example 2 PA6.12 PET - - - + + + Comparison example 3 PA6.12 PP SEBS - - - + + + Comparison example 4 PA6.12 PE - - - + + + Comparison example 5 PA6.12 PU - - - + + + Comparison example 6 PA6.12 PA12 - - - + + + Comparison example 7 PMMA PMMA + + + s b - Comparative example 8 PS PS + + + s b - Comparison example 9 SEBS SEBS + + + w b - Example 1* PA6.12 PA6.12 + + + + + + Example 2 PA12 PA12 + + + + + + Example 3* PBT PBT + + + + + + Example 4 PA12 PA12 PEBA (PA12) + + + + + + Example 5 PA6.12 PA6.12 PEBA (PA6.1 2) + + + + + + * Comparison examples

Claims

1. Brushware comprising the constituents: - monofilaments or bristles and - at least one head, handle and / or neck, wherein the constituents comprise or consist of polymers from the same polymer class selected from polymer and wherein the polymer class is selected from polyamide, characterized in that the polymer is a polymer derived from the monomers ω-aminododecanoic acid and / or laurolactam.

2. Brushware according to Claim 1, wherein the head, handle and / or neck has at least one grip element and the at least one grip element comprises or consists of polymers from the same polymer class as the constituents.

3. Brushware according to Claim 1 or 2, wherein the constituents consist of polymer of the same polymer class.

4. Brushware according to any of the preceding claims, wherein the brushware is a toothbrush.