p-Phenylenediamine HCl

Also known as: PPD hydrochloride

INCI: p-Phenylenediamine HCl | Function: Hair Dye | Type: Oxidative hair dye (aromatic amine)

What Is p-Phenylenediamine HCl?

p-Phenylenediamine HCl 是对苯二胺 (PPD) 的盐酸盐形式, 是一种氧化型染发剂 (oxidative hair dye)。通过氧化反应在发丝内形成颜色分子, 提供持久的染发效果。PPD 是染发剂中最常见的致敏原 (potent sensitizer), EU 对其有严格浓度限制。

Key Skin Benefits

+ Permanent hair coloring — 持久染发
+ Wide color range — 可调制多种色系
+ Good gray coverage — 白发遮盖效果好

Pros

+ Most effective permanent hair dye
+ Versatile color range
+ Long-lasting results

Cons

− POTENT ALLERGEN — leading cause of hair dye allergy
− EU restricted to max 2% after mixing
− Patch test required 48h before each use
− Cross-reactivity with azo dyes
− Occupational hazard for hairdressers

Specifications

Property	Value
Usage Areas	Hair
Product Type	Rinse-Off
Source	Synthetic
Natural Level	Synthetic

Safety Ratings

Metric	Rating
Skin Sensitivity	4/5 (high allergen)
Comedogenic Rating	N/A (hair only)
EWG Score	7/10

Regional Regulatory Limits

Region	Leave-on %	Rinse-off %	Status
EU (CosIng)	2% (after mixing)	2% (after mixing)	RESTRICTED — Annex III, max 2%, warning label required
US (FDA)	No specific limit	No specific limit	Allowed — warning label required
Japan (MHLW)	Restricted	Restricted	Allowed — restricted concentration
ASEAN	2% (after mixing)	2% (after mixing)	RESTRICTED — follows EU
China (NMPA)	Restricted	Restricted	Allowed — restricted use in hair dyes

Typical Usage % by Product Type

Product Type	Typical %
Permanent hair color	≤2% (after mixing)
Oxidative hair dye	≤2% (after mixing)

References

EU CosIng — Annex III restricted substances. https://ec.europa.eu/growth/tools-databases/cosing/
SCCS — Opinion on p-phenylenediamine. https://ec.europa.eu/health/scientific_committees/
McFadden JP et al. (2011) — PPD allergy. PMID: 21284645
EWG Skin Deep — PPD report. https://www.ewg.org/skindeep/

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