Method and apparatus for detecting minority fractions in textile fabrics

Abstract

The invention relates to methods of detecting a minority fraction in a textile fabric comprising the step of treating a textile fabric or part thereof by abrasion of the surface to expose minority fibres within the fabric, and -detecting exposed minority fibres within the treated fabric using imaging or spectroscopy techniques.

Description

[0001] METHOD AND APPARATUS FOR DETECTING MINORITY FRACTIONS IN

[0002] TEXTILE FABRICS

[0003] Field of the Invention

[0004] The present invention relates to the field of textile recycling.

[0005] Background of the Invention

[0006] In textile recycling industries, it is important to supply pure streams of used (secondhand) textile fabrics for efficient recycling. However, textile fabrics often consist of mixtures of fibres that are interwoven or where a cladding of a majority fibre material is spun around a core of a different minority fibre material (core-spun material). Detecting minority fractions in such interwoven or core-spun materials is challenging, as optical signatures from visible, shortwave infrared, or infrared absorption spectroscopy do not effectively identify fabrics consisting of material mixtures. This issue hampers the recycling process and reduces economic viability.

[0007] The presence of minority fractions in textiles, particularly in garments like jeans, complicates recycling due to the difficulty in detecting and separating these fractions.

[0008] Summary of the Invention

[0009] The invention relates to methods and apparatus for detecting minority fibre fractions in textile fabrics to improve the purity of recycled textiles.

[0010] The present invention proposes a method for reliably detecting minority fibre fractions in textile fabrics. This method involves abrading the fabric to reveal hidden minority fibres and subsequently detecting these fibres using imaging or spectroscopy techniques. The abrasion can be done mechanically, chemically, or by using heat sources like laser light, which allows for revealing minority fractions in a 'stair pattern' at different depths. This method enhances the ability to detect minority fractions even when they are not visible on the surface of the fabric.

[0011] The invention is further summarised in the following statements:

[0012] 1. A method of detecting a minority fraction in a textile fabric comprising the step of:

[0013] -treating a textile fabric or part thereof by abrasion of the surface to expose minority fibres within the fabric,

[0014] -detecting exposed minority fibres within the treated fabric using imaging or spectroscopy techniques. 2. The method according to statement 1, wherein the abrasion is performed at different depths on a textile fabric.

[0015] 3. The method according to statement 1 or 2, wherein the abrasion of the textile fabric is performed using mechanical abrasion.

[0016] 4. The method according to statement 1 or 2, wherein the abrasion of the textile fabric is performed using chemical abrasion

[0017] 5. The method according to statement 1 or 2, wherein the abrasion of the textile fabric is performed by burning or vaporising fibres using a heat source such as laser light.

[0018] 6. The method according to any one of statements 1 to 5, wherein the imaging techniques comprises microscopic imaging involving scattering or absorption processes.

[0019] 7. The method according to any one of statements 1 to 5, wherein the imaging techniques comprises non-microscopic techniques such as absorption spectroscopy in reflection geometry.

[0020] 8. The method according to any one of statements 1 to 7, comprising the step of determining the presence of a regular pattern of minority fibres in the textile fabric.

[0021] 9. The method according to any one of cla8ms 1 to 8, wherein the textile fabric is a core-spun yarn consisting of a majority fibre spun around a minority fibre.

[0022] 10. The method according to any one of statements 1 to 8, wherein the textile fabric is an interwoven minority fibre in a majority fibre.

[0023] 11. The method according to any one of statements 1 to 10, wherein the minority fibre is elastane, polyamide, polyester.

[0024] 12. The method according to any one of statements 1 to 11, wherein the majority fibre is cotton or polyester.

[0025] 13. The method according to any one of statement 1 to 12, wherein the majority fibre is cotton and the minority fibre is elastane.

[0026] 14. The method according to any one of statement 1 to 13, which is performed without staining of the minority fibre and without staining of the majority fibre. Detailed description

[0027] Figure legend

[0028] Figure 1: Jeans tissue after abrasion of layers of increasing depth (left to right) using a laser engraving system.

[0029] The majority fractions in fabrics can include cotton, polyamide, and polyester, while the minority fraction often comprises elastane, which, despite its typically low content (<20%), imparts desirable mechanical properties to the fabric, such as stretchability and comfort.

[0030] A minority fraction can be a fraction less than 20 wt%, less than 10 wt%, less than 5 wt%, less than 2 wt% or less than 1 wt% of the textile fabric.

[0031] The invention solves the problem of detecting minority fractions in textile fabrics, thereby improving the recycling process.

[0032] The methods comprise the following steps:

[0033] Abrasion of Textile Fabric

[0034] A textile fabric or part thereof is abraded to expose minority fibres within the fabric. This can be done either locally or on a full scale, using mechanical abrasion, chemical abrasion, or by applying heat using a laser engraver. The abrasion can for example be performed in a 'stair pattern,' or other methods to reveal different depths to ensure the detection of minority fibres at various levels within the fabric.

[0035] Detection of Minority Fibres

[0036] The exposed minority fibres are detected using imaging or spectroscopy techniques. Microscopic imaging involving scattering or absorption processes can be employed, as well as non-microscopic techniques like absorption spectroscopy in reflection geometry. The presence of minority fibres is indicated by a regular pattern (e.g., regular stripes) within the abraded area, and which is not seen in the non-treated region of the fabric.

[0037] EXAMPLES

[0038] Example 1. Textile Sorting Line with Laser Engraver and Imaging Setup In a textile recycling facility, a sorting line is equipped with a device for spreading garments and a laser engraver for localized abrasion. The process comprises the following steps:

[0039] Spreading the Garment:

[0040] A conveyor system feeds garments onto a spreading device that flattens the fabric to ensure an even surface for abrasion.

[0041] Localized Abrasion:

[0042] The garment is moved under a laser engraver that abrades a 20x20mm area on the fabric. The laser engraver is programmed to create a 'stair pattern' with a step size of several lOths of micrometres, abrading at different depths to expose potential minority fibres.

[0043] Imaging and Detection:

[0044] An imaging setup, comprising a high-resolution camera and microscopic imaging system, scans the abraded area. The imaging system is configured to detect regular patterns indicative of minority fibres within the abraded section.

[0045] Detection algorithms analyse the imaging data to classify the garment based on the presence or absence of minority fibres.

[0046] Sorting:

[0047] Garments identified as containing minority fibres are sorted out by a mechanical ejection device and diverted to a separate processing stream. Garments without minority fibres continue along the main recycling line.

[0048] This procedure enables efficient and accurate sorting of garments based on the presence of minority fibres, improving the quality of recycled textile streams.

[0049] The use of a laser engraver allows for precise abrasion and exposure of minority fibres at different depths.

[0050] Example 2. Textile Blend Analysis Device for Jeans Fabric

[0051] A specialized device for analysing the fibre composition of jeans fabric is designed to assess the elastane content in core-spun and interwoven textiles. The process includes the following steps:

[0052] Sample Preparation:

[0053] A 20x20mm sample of jeans fabric is cut and placed on a sample holder within the analysis device.

[0054] Abrasion with Laser Engraver: The sample holder moves under a laser engraver that abrasively removes material in a 'stair pattern,' with step sizes of several lOths of micrometres. This controlled abrasion reveals the underlying layers of the fabric, exposing hidden elastane fibres. Microscopic Imaging:

[0055] After abrasion, the sample is moved to an imaging station equipped with a microscopic imaging system. The system captures high-resolution images of the abraded area, focusing on the regular patterns formed by the exposed minority elastane fibres.

[0056] Analysis and Quantification:

[0057] Image analysis software processes the microscopic images to identify and quantify the presence of elastane fibres. The software calculates the overall elastane content in the fabric based on the detected minority fibres.

[0058] The analysis results are displayed on a user interface, providing detailed information about the fabric's composition.

[0059] This procedure allows for precise quantification of elastane content in jeans fabric, aiding in the assessment of material properties and recyclability.

[0060] The use of microscopic imaging and advanced image analysis ensures accurate detection and quantification of minority fibres.

Claims

6CLAIMS1. A method of detecting a minority fraction in a textile fabric comprising the step of:-treating a textile fabric or part thereof by abrasion of the surface to expose minority fibres within the fabric,-detecting exposed minority fibres within the treated fabric using imaging or spectroscopy techniques.

2. The method according to claim 1, wherein the abrasion is performed at different depths on a textile fabric.

3. The method according to claim 1 or 2, wherein the abrasion of the textile fabric is performed using mechanical abrasion.

4. The method according to claim 1 or 2, wherein the abrasion of the textile fabric is performed using chemical abrasion5. The method according to claim 1 or 2, wherein the abrasion of the textile fabric is performed by burning or vaporising fibres using a heat source such as laser light.

6. The method according to any one of claims 1 to 5, wherein the imaging techniques comprises microscopic imaging involving scattering or absorption processes.

7. The method according to any one of claims 1 to 5, wherein the imaging techniques comprises non-microscopic techniques such as absorption spectroscopy in reflection geometry.

8. The method according to any one of claims 1 to 7, comprising the step of determining the presence of a regular pattern of minority fibres in the textile fabric.

9. The method according to any one of cla8ms 1 to 8, wherein the textile fabric is a core-spun yarn consisting of a majority fibre spun around a minority fibre.

10. The method according to any one of claims 1 to 8, wherein the textile fabric is an interwoven minority fibre in a majority fibre.

11. The method according to any one of claims 1 to 10, wherein the minority fibre is elastane, polyamide, polyester.

12. The method according to any one of claims 1 to 11, wherein the majority fibre is cotton or polyester.

13. The method according to any one of claim 1 to 12, wherein the majority fibre is cotton and the minority fibre is elastane.

14. The method according to any one of claim 1 to 13, which is performed without staining of the minority fibre and without staining of the majority fibre.

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