Luminous Yarn White Paper

Version: v1.2
Release Date: 2025-08-30

Prepared by: Dongguan Yuexiong Textile Co., Ltd. (MONALISHAMAGIC)
Compilation unit: Dongguan Yuexiong Textile Co., Ltd.（MONALISHAMAGIC）

Copyright & Disclaimer

This white paper is intended for technical exchange and supply-demand matching. It does not constitute a legal guarantee or commercial warranty. The involved indicators and recommendations need to be reviewed in conjunction with enterprise equipment and regulations. Reproduction without permission is prohibited.

1 Executive Summary

Luminous Yarn (Glow-in-the-Dark Yarn / Fluorescent Yarn) is a functional textile solution that composites rare earth long-afterglow self-luminous materials with fiber substrates to achieve "light absorption - energy storage - light release". Compared to active light-emitting devices, it requires no power supply during use, offering advantages such as lightweight, durability, and passive recognition. Based on the "Luminous Afterglow Value Test Report" (Sample: Luminous Yarn), after pre-excitation for 20 minutes under 980 lx conditions, the initial brightness at 1 second reached 583.6 mcd/m², and the brightness at 120 minutes was 0.64 mcd/m². The time for brightness to decay to 0.3 mcd/m² was approximately 220.32 minutes. These results indicate a balance between "short-term high brightness + long-term visibility" can be achieved under standard indoor illumination - UV supplementary light conditions.

This white paper systematically covers terminology and definitions, luminescence mechanism, raw materials and formulations, manufacturing processes, testing methods and indicators, chemical compliance, environment and sustainability, application design guidelines, quality control, risks and limitations, and mass production introduction strategies. Each chapter references actual measured data as engineering boundaries and verification basis, providing executable parameter windows and sampling inspection schemes.

2 Scope & Audience

Applicable Audience: Functional yarn and fabric/trim suppliers, R&D/process/quality teams of brands and OEMs, testing institutions, and researchers.

Applicable Products: Luminous functional yarns and their fabrics (knitted/woven/footwear materials/backpacks/home furnishings/trims), including coated, blended/embedded, and covered technical routes.

Out of Scope: Active light-emitting devices requiring a power supply (LED optical fibers, EL wires, etc.) are not within the scope of this document.

3 Normative References

• ISO 6330 Textiles — Domestic washing and drying procedures (for appearance and durability assessment)

• DIN EN ISO 3071 Textiles — Determination of pH (KCl method)

• EN 14362-1/3 Banned amines; ISO 14389/EN 14372 Phthalates; ISO/TS 16179 Organotin; DIN EN 16711-2 Heavy metals; NP/OP/NPEO/OPEO related methods

• Luminous Performance: Enterprise Standard/Methodology (See Chapter 10 and Appendix F)

4 Terms & Abbreviations

5 Luminous Principle

Under photon excitation, electrons in long-afterglow materials transition and are captured by trap energy levels; after excitation is removed, electrons return to the luminescent center via thermal activation or quantum tunneling, releasing photons to form afterglow. Trap depth determines the energy release rate; trap density and distribution affect initial brightness and long-term visibility. Smaller particle size increases specific surface area, leading to more uniform dispersion but enhanced scattering; excessively large particle size affects hand feel and film layer density.

The actual measurement from this batch shows: high initial brightness at 1s (583.6 mcd/m²), entering a rapid decay region between 1-10 min (1 min 104.5, 10 min 13.47 mcd/m²), transitioning to a slow decay region between 10-120 min (60 min 1.63, 120 min 0.64 mcd/m²), exhibiting typical "fast-slow" two-stage decay characteristics (approximated by a stretched exponential model).

6 Energy Sources & Excitation

Establishing unified excitation conditions is recommended: light source type (natural daylight/white light/UV), illuminance (e.g., 980 lx), distance (30-50 cm), time (20 min), environment (23±2°C, 50±10% RH). Unified conditions enhance cross-batch comparison and reproducibility for external delivery.

Different light sources have different spectral power distributions; the UV band typically has higher excitation efficiency. When scene conditions are limited, compensation can be achieved by extending excitation time or increasing illuminance. To avoid overshoot and thermal damage, the excitation device must maintain stable temperature rise and ventilation.

7 Raw Materials & Properties

Commonly used are rare-earth doped aluminate/silicate luminous powders, employing surface coating to improve water resistance and chemical stability. The binder system requires a compromise between strong adhesion and hand feel, preferably low VOC, flexible, fold-resistant, and wash-resistant systems; substrates can be polyester, nylon, cotton/viscose, and their blends, etc. It is suggested to establish a multi-objective trade-off matrix of "particle size - film thickness - brightness/afterglow - tactile feel".

Representative particle size suggestion (for reference): D50 5-20 μm (smaller for knit types, larger for footwear/backpack straps possible); overly wide particle size distribution affects coating uniformity and surface texture.

8 Manufacturing Overview

Coating Method Process: Slurry preparation → Sizing/3D printing → Baking and curing → Moisture regaining and setting → Finishing → Inspection. Key Controls: Solid content and viscosity (e.g., 1000-3000 mPa·s), sizing add-on/grammage uniformity, baking temperature/time curve (avoid thermal yellowing and embrittlement), anti-settling and anti-delamination strategies.

Embedding/Blending: Masterbatch preparation → Spinning/compositing → Drawing and setting → Winding; attention needed to melt rheology and filtration, preventing spinneret clogging and increased breakage rate.

Online Quality Points: Quick brightness sampling (5 min excitation quick test method), appearance particle feel/hand feel, width, and curling. Offline Quality Points: Afterglow curve, home wash appearance, chemical compliance, and pH.

9 Specifications & Recommended Ranges

The following are engineering suggestion windows, needing adjustment based on customer use and legal requirements (subject to actual measurement and third-party testing):

10 Performance & Testing

10.1 Luminescence & Afterglow:

• Sample Pretreatment: Condition at 23±2°C, 50±10% RH for 24 h;

• Excitation Conditions: According to Chapter 6 unified conditions (e.g., 980 lx × 20 min);

• Recording Points: 1 s/1/2/10/30/60/120 min (can be extended to 240 min);

• Data Processing: Plot brightness-time curve, extract node values and time to 0.3 mcd/m²;

• Rapid Assessment: Allow 5 min excitation + 30/60 min node sampling for line release, retain batch samples for full curve testing.

This batch's representative data: 1 s 583.6; 1 min 104.50; 10 min 13.47; 60 min 1.63; 120 min 0.64 (Unit: mcd/m²), time to 0.3 mcd/m² approx. 220.32 min (See Appendix F for details).

10.2 Color & Appearance:

• Observe color, uniformity, and particle feel "before/after excitation";

• Use image uniformity evaluation (grayscale variance, texture indicators) supplemented by subjective review;

• When particle feel conflicts with hand feel, determine weighting based on the principle of application priority.

10.3 Wearability & Durability:

• Home Wash Appearance: ISO 6330 program 3N (30°C), record appearance rating after 10/15/20 cycles, representative samples "acceptable" after 20 cycles with light to moderate fading;

• Fastness: Color fastness to washing, rubbing (dry/wet), perspiration (acid/alkaline), and water performed according to standards.

10.4 Chemical & Safety:

• pH (KCl method), formaldehyde, banned amines, phthalates, organotin, NP/OP/NPEO/OPEO, heavy metals, etc., performed according to respective standards;

• Recommend importing quarterly rolling comparisons against buyer RSL/MRSL.

11 Chemical Compliance & Safety

Representative third-party testing shows: pH within the 4.0-7.5 range; formaldehyde not detected (below method detection limit); banned amines not detected; total phthalates below 0.1% limit; organotin not detected; NP/OP/NPEO/OPEO not detected; heavy metal extraction amounts meet limits. Variations exist between batches; results should be based on current batch testing, and an annual baseline should be established.

12 Applications & Design Guidelines

Sports Safety & Children: Night running jackets, footwear materials, backpack straps, children's accessories, emphasizing immediate visibility in dark environments; recommend using zonal and border highlighting layouts to enhance recognition.

Fashion & Accessories: Knitted/woven fabrics, jacquard/space dyeing, and local decoration; recommend converting the functional layer in high-wear areas to an "embedded + protective film" structure to reduce peeling.

Home Furnishings & Guidance: Cushions, carpets, curtains, wallcoverings, emergency guidance; large-area applications require focused attention on brightness uniformity and texture acceptability.

13 Care, Storage & Lifetime

• Store in a cool, dark, dry, and sealed place;

• Avoid high-temperature ironing and prolonged direct strong UV exposure;

• Gradual brightness decay with routine home washing cycles is normal;

• Recommend quarterly sampling and review of sold styles to update usage recommendations.

14 Environment & Sustainability

No power supply is required during the use phase, reducing energy consumption compared to active light-emitting devices; during the production phase, environmental load is reduced through low VOC systems, water recycling, and waste heat recovery; establish recycling/reuse evaluation and a chemical compliance closed loop.

15 Quality Control Plan

Three-level quality gate: Incoming - Process - Finished Product.

Measurement System: Annual calibration and quarterly review of brightness meters are recommended, MSA (R&R) ≥ 10:1.

16 Risks & Limitations

17 Data & Case Studies

Based on actual measurements of this batch's sample (Luminous Embroidery Yarn, Medium Green):

• 1 s 583.6 mcd/m²; 1 min 104.5; 10 min 13.47; 60 min 1.63; 120 min 0.64.

• Time to 0.3 mcd/m² is 220.32 min, meeting the "long-term visibility" target.

• Home Wash Appearance: Acceptable after 10/15/20 cycles, moderate fading but structurally intact after 20 cycles (ISO 6330).

• Chemical Compliance: pH compliant; formaldehyde/banned amines/organotin/NP&OP/NPEO&OPEO/Phthalates/Heavy metals meet limits.

Engineering Interpretation: The 1/10/60/120 min nodes can be used as "multi-segment anchors" for mass production release, setting the 90% target value as the batch threshold, ensuring customer experience while accommodating manufacturing fluctuations.

18 Engineering Optimization: S Series Reference

Formula and Structure Optimization: Under the premise of maintaining the brightness and afterglow range, achieve a balance of "softer, more elastic, more wash-resistant" hand feel and durability through flexible binder systems, particle size grading, and film thickness gradients; for skin-contact applications, recommend using a skin-friendly substrate + functional layer gradient transition, with seam/hem reinforcement.

Validation Suggestion: Compare the conventional version and the S version for 20-cycle home wash appearance and 120-min node brightness, targeting maintenance/improvement ≥ 95%.

19 Validation & Ramp-up

Phased Validation:

• EVT: Small trial confirms particle size - film thickness - brightness relationship and baking curve;

• DVT: Medium trial verifies curve consistency under different weaving/finishing conditions;

• PVT: Rhythm/yield ramp-up, establishes release anchors (1/10/60/120 min) and AQL sampling plan.
  Sample & Record Retention: Retain raw curve data and sample fabric for each batch, facilitating review and customer complaint tracing.

20 Appendix F Luminous Afterglow Value Test Report (Integrated Measured Data)

Test Source: Luminous Afterglow Value Test Report (2022-03-21, Dongguan Yuexiong Textile Co., Ltd.).

https://media/image1.png{width="6.3in" height="3.876922572178478in"}

Figure F-1: Afterglow decay curve (1-120 min), node values detailed in Chapters 10 and 17.

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