ZPT - Zinc Pyrithione

I. Product Information

Product Name Zinc Pyrithione

Synonyms ZPT

Chemical Name 2-Mercaptopyridine N-oxide zinc salt

IUPAC Name zinc; 1-oxidopyridine-2-thione

Molecular Formula C₁₀H₈N₂O₂S₂Zn

Molecular Weight 317.7

CAS No. 13463-41-7

EC Number 236-671-3

II. Product Properties (Key Features)

Property	Description
Appearance	White to off-white powder (pure)
Antimicrobial Spectrum	Broad-spectrum efficacy against molds, bacteria, and yeast; stronger inhibition against Gram-positive than Gram-negative bacteria
Mechanism	Ion gradient disruption: Under neutral/acidic conditions, transports K⁺ out and H⁺ into bacterial cells; under alkaline conditions, transports K⁺ or Mg²⁺ out and Na⁺ in, effectively "starving" cells by eliminating nutrient ion gradients
Stability	Stable at pH 4.5～9.5; excellent thermal stability (stable for at least 120h at 100℃); gradually degrades under UV; converts to mercaptopyridine below pH 3.5; may form soluble basic salts above pH 8.5
Solubility	Water (pH 7) 0.008 g/L; ethanol 0.1 g/L; propylene glycol 0.2 g/L; isopropanol 0.08 g/L; PEG 2 g/L; chloroform 3 g/L; DMF 80 g/L

Physical & Chemical Data:

Boiling Point: 262.0℃
Melting Point: 240℃ (decomposes)
Vapor Pressure: 1.33×10⁻⁴ Pa
Bulk Density (25℃): 0.35 g/mL
pH (5% aqueous suspension): 6.5～8.5
lgKow: 0.97

III. Quality Specifications

Test Item	Specification	Method
Appearance	White to off-white powder	Visual
Content (as Zn)	9.8%～11.2%	AAS
pH (5% suspension)	6.5～8.5	pH Meter
Loss on Drying	≤0.5%	Gravimetric
Residue (325 mesh)	≤0.1%	Sieving
Heavy Metals (as Pb)	≤0.002%	Colorimetric
Arsenic (As)	≤0.0001%	AAS
pH Stability	Stable at pH 4.5～9.5	pH Meter
Thermal Stability	Stable for 120h at 100℃	Thermal Stability Test
Identification	IR spectrum matches reference standard	FTIR

Note: Available as 48% dispersion, pure powder, and other specifications upon request.

IV. Antimicrobial Performance (MIC Data)

Microorganism	MIC (mg/L)	Microorganism	MIC (mg/L)
S. aureus 6538	4	Enterococcus faecalis 19433	16
E. coli 9637	8	P. aeruginosa 9721	512
Klebsiella pneumoniae 4352	8	Fusarium	32
Aspergillus niger 9642	8	Aureobasidium pullulans 9348	2
Chaetomium globosum 6205	2	Gliocladium virens 9645	64
Penicillium funiculosum 9644	2	C. albicans 11651	2
Sporotrichum olivaceum	4	Trentepohlia (aerial algae)	0.06
Chlorococcum	8	Scytonema	0.5

Note: ZPT exhibits excellent antifungal and anti-algal activity with MIC values of 2 mg/L against C. globosum, P. funiculosum, A. pullulans, and C. albicans, and 0.06 mg/L against Trentepohlia; relatively weaker inhibition against P. aeruginosa (512 mg/L).

V. Applications

1. Anti-dandruff & Antipruritic (Core Application)

Shampoos: Highly effective and safe anti-dandruff agent that kills fungi causing dandruff
Efficacy: Anti-itching, anti-dandruff, reduces hair loss, and delays graying
Usage notes: Extremely poorly soluble in organic solvents and water; unsuitable for transparent shampoos; incompatible with EDTA; activity reduced by non-ionic surfactants; light scattering causes matting effect affecting pearlescence; prone to discoloration with iron ions; requires suspending agents and stabilizers
Classic formulation: BIT+ZPT combination (PROXEL BZ Plus, Wanlijing ZB-20), zero VOC, formaldehyde-free, APEO-free, CMIT-free; dual active ingredients provide synergistic fast kill and long-term protection; heat resistant to 150℃

2. Marine Antifouling

Ship antifouling paints: Prevents attachment of crustaceans, algae, and aquatic organisms to hulls
Offshore drilling platforms: Prevents marine biofouling
Formulation: Combined with Cu₂O or pyridine triphenylborane (PTPB); ZPT (3%～5% dry film weight) + cuprous oxide (35%～40%)
Leaching rate: 3～11 μg/(cm²·d) in self-polishing antifouling coatings
Environmental fate: Chemical hydrolysis half-life >90d in artificial seawater, 4d in natural seawater; photodegradation half-life 17.5 min (xenon arc), <2 min under natural light

3. Plastics & Building Materials

Antimicrobial plastics: PVC, PU and other plastics
Carpet fibers: Antimicrobial finishing
Adhesives: Preservation
Sealants: Anti-mold treatment
Coatings: GB/T 35602-2017 limits ZPT to ≤0.5% in coatings

4. Industrial

Marine engineering: Prevention of biofouling on offshore facilities
Water treatment: Algae control (MIC 0.06 mg/L against Trentepohlia)

VI. Regulatory Compliance & Safety

Certification/Regulation	Details
China Cosmetics Regulations	"Cosmetics Safety Technical Specifications" 2015: Max 0.5%; restricted to rinse-off products
US FDA	1981 approval of 29 ZPT-containing formulations; considered safe for daily use at 1%～2% in shampoos
EU ECHA	Approval applications submitted under Directive 98/8/EC (BPD) or Regulation (EU) No.528/2012 (BPR) for PT-2, PT-6, PT-7, PT-9, PT-10, PT-21; currently under review
Coatings Standard	GB/T 35602-2017 "Green Product Assessment - Coatings" limits ZPT to ≤0.5% in coatings

Toxicity Data:

Endpoint	Data
Mouse acute oral LD₅₀	361 mg/kg (Toxic)
Rabbit acute dermal LD₅₀	>2000 mg/kg
Mouse intraperitoneal LD₅₀	22.5 mg/kg
Mouse oral LD₅₀	260 mg/kg
IP toxicity vs oral toxicity	IP toxicity approximately 10× higher than oral
Rat 540 mg/kg daily oral	After 1 week: reduced appetite, decreased activity, unkempt fur, weight loss; after 30 days: no significant pathology except cloudy swelling and vacuolation in hepatocytes of high-dose group
Aquatic toxicity	Rainbow trout LC₅₀ (96h): 3.2 μg/L; Daphnia EC₅₀ (48h): 34 μg/L

Safety Precautions:

Extremely toxic to aquatic organisms (rainbow trout LC₅₀ 3.2 μg/L); avoid discharge to water bodies
Gradually degrades under UV; store protected from light
May cause significant discoloration in presence of iron and copper
Incompatible with EDTA; activity reduced by non-ionic surfactants

VII. Packaging & Storage

Packaging: 25kg/fiber drum (lined with PE bag) / 50kg/iron drum; custom sizes available

Storage: Cool, dry place (≤25°C), sealed, away from light; avoid strong acids, strong alkalis, iron/copper ions, UV

Shelf Life: 24 months (sealed)

Transport: Hazardous chemical (extremely hazardous to aquatic environment); handle with care

VIII. Key Advantages

Anti-dandruff efficacy: World's most widely used anti-dandruff agent; highly effective against dandruff-causing fungi
Unique mechanism: Ion gradient disruption kills microbes without being consumed itself, providing lasting efficacy
Synergistic enhancement: Combined with BIT (PROXEL BZ Plus), zero VOC, formaldehyde-free, APEO-free, provides fast kill + long-term protection, heat resistant to 150℃
Marine antifouling: Core ingredient in ship antifouling paints; prevents crustacean and algal attachment with controlled leaching rates
Broad spectrum: Inhibits molds, bacteria, yeast, and algae with low MIC values (0.06～512 mg/L)
Thermal stability: Stable for 120h at 100℃, suitable for high-temperature processing