Method for identifying textile types

Abstract

The invention relates to methods for identifying textile types within a garment or part of a garment, the method comprising the steps of labelling a garment or part thereof 5 with a fluorescent dye or mixture of dyes with a selective binding for a synthetic or for a natural polymer, performing fluorescence imaging to detect the binding of the dye to garment, isolating a garment or part thereof based on the labelled polymer.

Description

[0001] METHOD FOR IDENTIFYING TEXTILE TYPES

[0002] Technical field

[0003] The present invention relates to the field of textile recycling, particularly to a method for identifying different textile types within a garment using fluorescent dyes and fluorescence spectroscopy.

[0004] Background of the invention

[0005] In recycling industries, it is crucial to identify different textile types within a garment to enable efficient recycling. The current industry standard relies on near-infrared (NIR) spectroscopy for this purpose. However, NIR spectroscopy has significant limitations, particularly in detecting minority textile fractions obscured by majority fractions and in handling black and dark-coloured textiles, which absorb NIR radiation, leading to detection failures. Therefore, there is a need for a robust alternative optical detection technology that can accurately detect minority fibres within post-consumer collected garments, even if present in quantities < 20%. Fluorescence imaging and spectroscopy is advantageous for this purpose as it allows to detect tiny quantities of fluorescence emitters in a large quantity of non- fluorescent material.

[0006] Summary of the Invention

[0007] The invention provides methods that utilizes fluorescent dyes to tag textiles after post-consumer collection, allowing for the identification of different polymers within a garment through fluorescence spectroscopy. The fluorescent dyes selectively bind to synthetic or natural polymers, and their emissions under fluorescence imaging enable the differentiation and identification of textile types.

[0008] The methods can be implemented in an automated textile sorting line designed to identify and sort textiles containing elastane, a synthetic polymer commonly used in stretch fabrics. Such sorting line can be equipped with systems for the labelling, detection, and isolation of textiles based on their elastane content.

[0009] A sorting line includes a labelling step where textiles are treated with a fluorescent dye that selectively binds to elastane fibres. The dye is chosen for its strong affinity for elastane and its distinct fluorescence emission that can be well differentiated from any autofluorescence of the garment or optical brightener present in washing detergent.

[0010] The textiles pass through a dye application unit where they are sprayed or dipped in the dye solution. This unit ensures even and thorough application of the dye to all incoming textiles. Alternatively, the dyes could be applied during a washing step.

[0011] After labelling, the textiles move to an optional drying station where they are dried to proper mechanical handling.

[0012] The dried, labelled textiles then proceed to a fluorescence imaging station. Here, high-resolution fluorescence imaging systems equipped with optical sensors detect the fluorescence emissions from the labelled elastane fibres. The imaging system captures the emission data and processes it to identify textiles containing elastane based on the unique fluorescence signature of the dye bound to the elastane fibres.

[0013] The processed data are used to activate a sorting mechanism downstream of the imaging station. This mechanism can include conveyor belts, air jets, or robotic arms that physically separate textiles containing elastane from those that do not.

[0014] The textiles identified as containing elastane are directed to designated bins or areas for further processing or recycling, while the remaining textiles are sorted according to other criteria or continue along the sorting line for additional identification steps.

[0015] The methods of the present invention provide different advantages:

[0016] Enhanced Accuracy: The use of fluorescent dyes that specifically bind to elastane ensures high accuracy in identifying elastane-containing textiles, even at low quantities, overcoming the limitations of traditional NIR spectroscopy.

[0017] High Throughput: The automated nature of the sorting line allows for high throughput, making it suitable for large-scale textile recycling operations.

[0018] Versatility: The methods can be integrated into existing sorting lines or designed as a standalone system, providing flexibility in implementation.

[0019] The invention is further summarised in the following statements:

[0020] 1. A method for identifying textile types within a garment or part of a garment, the method comprising the steps of : a) labelling a garment or part thereof with a fluorescent dye or mixture of fluorescent dyes with a selective binding for a synthetic or for a natural polymer, b) performing fluorescence imaging to detect the binding of the dye to garment. c) Isolating a garment or part thereof based on the labelled polymer.

[0021] 2. The method according to statement 1, wherein a mixture of fluorescent yes is used, and wherein said dyes in the mixture have an affinity and emission property allowing the identification and isolation of different types of textile.

[0022] 3. The method according to statement 1 or 2, where the synthetic or natural polymer is selected from the groups consisting of elastane, polyester, cotton, viscose.

[0023] 4. The method according to any one of statements 1 to 3, wherein the garment is a black, dark blue or dark grey coloured garment where near-infrared and visible light is predominantly absorbed.

[0024] 5. The method according to any one of statements 1 to 4, wherein the fluorescent dye is chosen such that the emission of said dye is spectrally distinct from the autofluorescence of the garment.

[0025] 6. The method according to any of statements 1 to 5, wherein auto-fluorescence of one or more textile fractions is suppressed using an additional, non-emissive dye or pigment.

[0026] 7. The method according to any one of statements 1 to 6, wherein, in a mixture of dyes, the emission of each fluorescent dye is distinct from the emission of other dyes in the mixture.

[0027] 8. The method according to any of statements 1 to 7, wherein the emission of the fluorescent dye or mixture of fluorescent dyes is spectrally distinct from the fluorescence emission of optical brighteners and fluorescent substances that occur in washing detergents or their preparations used for washing textiles.

[0028] 9. The method according to any one of any of statements 1 to 8, wherein the fluorescent dyes or mixtures of dyes remain stable at temperatures between 20 and 35 °C, between 20 and 45 °C, between 20 and 70 °C or between 20 and 100 °C.

[0029] 10. The method according to any of statements 1 to 9, wherein the labelling with the fluorescent dye or mixture of fluorescent dyes is performed during the washing of the garment. 11. The method according to any of statements 1 to 10, wherein the labelling is performed during a local steaming of the garment.

[0030] 12. The method according to any one of statements 1 to 11, wherein the fluorescent dye is an optical brightener, or is a fluorescent dyes selected from the group consisting of xanthenes, cyanines, squaraines, naphthalenes, coumarines, oxadiazoles, anthracenes, pyrenes, oxazines acridines, arylmethines, tetrapyrroles, dipyrromethenes, azo dyes and natural dyes from plant extracts.

[0031] 13. The method according to any one statements 1 to 12, wherein a fibre in garment is stained of the amount of fibre in the garment is calculated by a computational analysis of the fluorescence imaging or spectroscopic data from said tagged garment.

[0032] 14. The method according to any one of statements 1 to 13 wherein the garment is cotton and the synthetic polymer is elastane.

[0033] 15. The method according to statement 14, wherein elastane is stained with the fluorescent dye 2-Butyl-6-(butylamino)-lH-benz[de]isoquinoline-l,3(2H)-dione.

[0034] Detailed Description of the Invention

[0035] Figure legend :

[0036] Figure 1: Macro-photograph of Jeans tissue (dark or dark grey) with tagged elastane fibres (white / grey, 1.5 wt%). The garment is stained with the optical brightener Solvent Yellow 43 binding preferably to elastane. The presence of Solvent Yellow 43 is detected by means of a UV light source and a camera sensitive to light with a wavelength of 500nm. The staining allows to identify the presence of elastane in a cotton fabric

[0037] The invention addresses the need to detect material compositions of textiles and involves the following steps:

[0038] Labelling: A garment or part thereof is labelled with a fluorescent dye or a mixture of dyes that selectively binds to certain synthetic or natural polymers (e.g., elastane, polyester, cotton, viscose). The dye adsorbs on the surface or is absorbed inside the polymer matrix.

[0039] Solvent Yellow 43 (2-Butyl-6-(butylamino)-lH-benz[de]isoquinoline-l,3(2H)-dione) is a suitable dye for the detection of elastane. Fluorescence Imaging: The labelled garment is subjected to fluorescence imaging to detect the emissions from the dye, thereby identifying the presence and type of polymers based on their unique fluorescence.

Claims

6CLAIMS1. A method for identifying textile types within a garment or part of a garment, the method comprising the steps of : a) labelling a garment or part thereof with a fluorescent dye or mixture of fluorescent dyes with a selective binding for a synthetic or for a natural polymer, b) performing fluorescence imaging to detect the binding of the dye to garment. c) Isolating a garment or part thereof based on the labelled polymer.

2. The method according to claim 1, wherein a mixture of fluorescent yes is used, and wherein said dyes in the mixture have an affinity and emission property allowing the identification and isolation of different types of textile.

3. The method according to claim 1 or 2, where the synthetic or natural polymer is selected from the groups consisting of elastane, polyester, cotton, viscose.

4. The method according to any one of claims 1 to 3, wherein the garment is a black, dark blue or dark grey coloured garment where near-infrared and visible light is predominantly absorbed.

5. The method according to any one of claims 1 to 4, wherein the fluorescent dye is chosen such that the emission of said dye is spectrally distinct from the autofluorescence of the garment.

6. The method according to any of claims 1 to 5, wherein auto-fluorescence of one or more textile fractions is suppressed using an additional, non-emissive dye or pigment.

7. The method according to any one of claims 1 to 6, wherein, in a mixture of dyes, the emission of each fluorescent dye is distinct from the emission of other dyes in the mixture.

8. The method according to any of claims 1 to 7, wherein the emission of the fluorescent dye or mixture of fluorescent dyes is spectrally distinct from the7 fluorescence emission of optical brighteners and fluorescent substances that occur in washing detergents or their preparations used for washing textiles.

9. The method according to any one of any of claims 1 to 8, wherein the fluorescent dyes or mixtures of dyes remain stable at temperatures between 20 and 35 °C, between 20 and 45 °C, between 20 and 70 °C, or between 20 and 100 °C.

10. The method according to any of claims 1 to 9, wherein the labelling with the fluorescent dye or mixture of fluorescent dyes is performed during the washing of the garment.

11. The method according to any of claims 1 to 10, wherein the labelling is performed during a local steaming of the garment.

12. The method according to any one of claims 1 to 11, wherein the fluorescent dye is an optical brightener, or is a fluorescent dyes selected from the group consisting of xanthenes, cyanines, squaraines, naphthalenes, coumarines, oxadiazoles, anthracenes, pyrenes, oxazines acridines, arylmethines, tetrapyrroles, dipyrromethenes, azo dyes and natural dyes from plant extracts.

13. The method according to any one claims 1 to 12, wherein a fibre in garment is stained of the amount of fibre in the garment is calculated by a computational analysis of the fluorescence imaging or spectroscopic data from said tagged garment.

14. The method according to any one of claims 1 to 13 wherein the garment is cotton and the synthetic polymer is elastane.

15. The method according to claim 14, wherein elastane is stained with the fluorescent dye 2-Butyl-6-(butylamino)-lH -benz [de] isoquinoline- 1,3(2H)- dione.

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