Photochromic Yarn / UV Color-Changing Yarn White Paper
Version: v2.0
Date: 2025-08-30
Archiving Level: Public Release
Copyright © MONALISHAMAGIC / Dongguan Yuexiong Textile Co., Ltd.
Executive Summary
This white paper clarifies the mechanism, indicators, third-party verification, and compliance key points of Photochromic Yarn (Light-Induced Color-Changing Yarn/UV Color-Changing Yarn/Sunlight Color-Changing Yarn). It integrates the technical requirements from the "Notes on Color-Changing Yarn" regarding storage, temperature & humidity, process temperature, compatibility, color development stability, and wavelength differences, forming executable SOPs and risk boundaries.
1 Scope & Applicability
Applicable to yarns and their fabrics (knitted/woven) containing photochromic functional agents, as well as technical evaluation when combined with multi-functions like thermochromic, luminous, reflective, etc.
2 Normative References
ISO 105 C06/X12/E04/E01
ISO 6330
GB/T 18830-2009
Buyer Chemical Restriction Policies (e.g., Adidas A-01 v20)
3 Terms & Definitions
Photochromism
Color Development Time
Reversion Time
Contrast Ratio
UVA/UVB Bands & Lamp Wavelength (UVA/UVB 波段与灯具波长)
4 Working Mechanism & Wavelength Considerations
Under UV/sunlight irradiation, functional molecules undergo reversible conformational changes, causing absorption peak shifts and coloration; they revert when the light is removed. Sensitivity to wavelength varies for different colors: e.g., yellow is more sensitive to ~385 nm, while red/purple/blue are sensitive to ~365 nm. When evaluated using a 365 nm UV lamp, yellow coloration may be insufficient; it performs normally under sunlight (orange, being mixed from red × yellow, may appear redder under a 365 nm lamp).
5 Material System & Technical Indicators (Integrated with Notes)
Photochromic Yarn / Color-Changing Yarn / Light-Sensitive Yarn usually has a surface coating structure, exhibiting batch-to-batch and color state (colored/faded) color differences (common ΔE ≥ 7). Baseline indicators are as follows:
光变纱线/变色纱线/感光变色纱线，通常为表面涂层（surface coating）结构，存在批间与显/隐色状态的色差（常见ΔE≥7）。基线指标如下：
| Item 项目 | Baseline/Range 基线/范围 | Source/Remarks 来源/备注 |
|---|---|---|
| Color Trigger 显色触发 | UV/Sunlight; 5s evaluation SOP | Lamp wavelength sensitivity see Chapter |
| Reversion Time 回退时间 | Sensitive colors (e.g., White-Red/White-Blue) within seconds; some colors up to tens of minutes | Depends on formula/environment/thickness |
| Color Fastness 色牢度 | Wash/Rubbing/Perspiration/Water ≥4~4-5 | Subject to 3rd party tests |
| Appearance After Wash 机洗外观 | Acceptable after 5~20 cycles ISO 6330 (requires batch verification) | Default建议“不机洗”, details Chap 12 默认建议“不机洗”，详见第12章 |
| Finishing Temperature 后整温度 | ≤150°C preferred; upper limit ≤160°C; single heat exposure ≤3 min | High temp/duration damages performance 高温/长时会损害变色性能 |
| Chemical Compatibility 化学相容 | Avoid strong acids/alkalis & strong solvents; avoid use with UV absorbers | To prevent failure or hindered coloration 以防失效或显色受阻 |
| Storage Stability 储存稳定 | Ambient temp (<40°C), humidity 20–70%, fully light-sealed; most formulas show no significant degradation within 2 years | See Chapter 13 见第13章 |
6 Basic Color Range (13 Colors)
Red, Yellow, Blue, Purple, Orange Red, Carmine, Sea Blue, Violet, Rose Purple, Garnet Red, Pink, Daffodil Yellow, Lake Blue (colorless → colored). Intermediate colors can be obtained by mixing base colors; note wavelength sensitivity differences.
7 Design & Structure Suggestions
Prioritize light background with high contrast coloration; dark backgrounds require patterning for recognition.
Thin structures revert faster; thick structures have fuller contrast; choose plain/rib/jacquard based on target effect.
When zoning with thermochromic/luminous/reflective, verify color fastness and appearance retention separately.
8 Key Production Process Points
Sample Making & Retention: Prepare 20×20cm samples per "5s Evaluation SOP", record environment/distance/time. 打样留样：按“5秒评估SOP”制备20×20cm样，记录环境/距离/时间。
Finishing: Prefer ≤150°C; upper limit ≤160°C; single heat exposure ≤3 minutes; avoid strong solvents and dry cleaning. 后整：优先≤150℃；上限≤160℃；单次受热≤3分钟；避免强溶剂与干洗。
Chemical Compatibility: Avoid strong acids, alkalis, and UV absorbers; pre-evaluate polarity-sensitive systems. 化学相容：避免强酸强碱及紫外吸收剂；对极性敏感体系需预评估。
Batch Production: Establish batch number, formula version, test records; sample inspection at least once per batch. 批量：建立批号、配方版本、测试记录；每批至少一次抽检。
9 Testing & Verification
| Category 类别 | Method/Condition 方法/条件 | Frequency 样次 | Baseline 判定基线 |
|---|---|---|---|
| Appearance After Wash 机洗外观 | ISO 6330 (30°C/3N) 5/10/15/20 cycles | ≥1 per batch 每批≥1 | Appearance acceptable 外观可接受 |
| Fastness - Wash 色牢度-皂洗 | ISO 105 C06 | ≥1 per batch 每批≥1 | Color Chg ≥4; Staining ≥4-5 变色≥4；沾色≥4-5 |
| Fastness - Dry/Wet Rub 色牢度-干/湿摩擦 | ISO 105 X12 | ≥1 per batch 每批≥1 | Dry ≥4; Wet ≥4-5 干≥4；湿≥4-5 |
| Fastness - Perspiration (Acid/Alk) 色牢度-汗渍（酸/碱） | ISO 105 E04 | ≥1 per batch 每批≥1 | Chg/Stain ≥4-5 变/沾≥4-5 |
| Fastness - Water 色牢度-水渍 | ISO 105 E01 | ≥1 per batch 每批≥1 | Chg/Stain ≥4-5 变/沾≥4-5 |
| UV Protection (Optional) 防紫外（可选） | GB/T 18830-2009 | As needed 按需 | UPF>40; UVAavg<5% |
10 Color Development Evaluation SOP (5-Second Method)
Environment 环境: 20–26°C; RH 45–65%. Fabric sample 20×20cm; light background preferred. 20–26℃；RH 45–65%。样布：20×20cm；浅底底色优先。
Light Source 光源: UVA or sunlight; fixed distance (record value). UVA或日光；固定距离（记录数值）。
Steps 步骤: A) Block/move light source for 3s observe contrast; B) Stable irradiation for 5s record color depth; C) Remove source, time reversion to near original color. A）遮挡/移开3s观察对比；B）稳定照射5s记录显色深度；C）移开光源，计时回退至接近原色。
Records 记录: Photos/video + form (environment, distance, time, subjective rating or ΔE). 照片/视频 + 表单（环境、距离、时间、主观等级或ΔE）。
11 Chemical Safety & Compliance
Based on historical third-party testing: Formaldehyde not detected, Azo compliant, Phthalates below limits; Buyer policy整套判定Pass (subject to current batch report). Recommend establishing RSL/MRSL dual lists and a batch sample retention mechanism.
依据历史第三方检测：甲醛未检出、偶氮符合、邻苯二甲酸酯低于限值；买家政策整套判定Pass（以当批报告为准）。建议建立RSL/MRSL双清单与批次留样机制。
12 Risks & Boundaries (Integrated with Notes)
12 风险与边界（融合注意事项）
Light/Heat Resistance Degradation: Long-term strong sunlight will reduce color contrast; high temperature/long duration finishing damages color-changing performance. 耐光/热衰减：长期强日照会使显色对比下降；高温长时后整会损害变色性能。
Washing Boundary: Due to the surface coating structure, default is "Do Not Machine Wash"; if machine washing is absolutely required by the customer, verification per ISO 6330 must be completed and care conditions clearly stated in the order/hangtag. 洗涤边界：由于为表面涂层结构，默认“不机洗”；如客户确需机洗，必须按ISO 6330完成验证并在订单/吊牌中明确护理条件。
Chemical Compatibility: Avoid strong acids, alkalis, strong solvents, and concurrent use of UV absorbers; sensitive to polar systems. 化学相容性：避免强酸、强碱、强溶剂与紫外吸收剂并用；对极性体系敏感。
Wavelength Differences: 365 nm lamps are insensitive to yellow; evaluation requires matching the appropriate wavelength. 波长差异：365 nm灯对黄色不敏感，评价需匹配合适波长。
Inter-Batch Color Difference: ΔE fluctuation between colored/faded states is a characteristic; tolerances must be agreed upon in advance based on retained samples. 批间色差：显/隐色ΔE波动属特性，需事先约定容差并以留样为准。
13 Maintenance, Storage & Transportation Conditions
Storage 存储: Ambient temperature <40°C, relative humidity 20–70%, fully light-sealed; seal storage boxes. 常温<40℃、相对湿度20–70%、全避光密封；储物箱封口。
Display 陈列: Avoid direct sunlight; avoid environments with UV absorbers. 避免暴晒；避免紫外线吸收剂环境。
Use 使用: Avoid contact with industrial strong acid/alkali auxiliaries; avoid dry cleaning and strong solvents. 避免接触工业强酸/强碱助剂；避免干洗与强溶剂。
Stability 稳定性: Under the above conditions, most formulas show no significant performance degradation within 2 years (can withstand approx. 3,000–5,000 color/fade cycles, subject to formula and actual measurement). 在上述条件下，多数配方2年内性能无明显退化（可承受约3,000–5,000次显/隐色循环，需以配方与实测为准）。
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