Zinc Stearate, Zinc dioctadecanoate, Zinc Octadecanoate, Zinc Soap, 557-05-1

Zinc Stearate, Zinc dioctadecanoate, Zinc Octadecanoate, Zinc Soap, 557-05-1

ZINC STEARATE
PRODUCT IDENTIFICATION INFORMATION

CHEMICAL STRUCTURE

Zinc Stearate

O
║
Zn — O — C — (CH₂)₁₆ — CH₃
|
O
║
C — (CH₂)₁₆ — CH₃

Molecular Formula: Zn(C₁₈H₃₅O₂)₂ or C₃₆H₇₀O₄Zn
SMILES: [Zn+2].[O-]C(=O)CCCCCCCCCCCCCCCCC.[O-]C(=O)CCCCCCCCCCCCCCCCC
InChI: InChI=1S/2C18H36O2.Zn/c2*1-2-3-4-5-6-7-8-9-10-11-12-13-14-15-16-17-18(19)20;/h2*2-17H2,1H3,(H,19,20);/q;;+2/p-2
InChIKey: VUYZGGQGHKLSDJ-UHFFFAOYSA-L
Structure: Zinc ion (Zn²⁺) coordinated to two stearate anions (C₁₈H₃₅O₂⁻); Long hydrocarbon chains provide hydrophobic properties; "Soap" or metallic soap structure.

SECTION 1: CHEMICAL IDENTITY AND DESCRIPTION

SECTION 2: PHYSICAL AND CHEMICAL PROPERTIES

SECTION 3: METALLIC SOAPS COMPARISON

SECTION 4: CHEMICAL PROPERTIES AND REACTIVITY

SECTION 5: PRODUCTION METHODS

Method 1: Direct Reaction (Precipitation Process)

Reaction: 2C₁₇H₃₅COOH (stearic acid) + Zn(OH)₂ → Zn(C₁₈H₃₅O₂)₂ + 2H₂O

Description: Stearic acid is heated to its melting point (70-80°C); Zinc hydroxide (or zinc oxide) is added slowly with stirring; Reaction proceeds at 80-120°C; Water formed is removed by distillation or vacuum; Product is cooled, ground, and sieved to desired particle size. Most common industrial method.

Method 2: Metathesis (Double Decomposition) Process

Reaction: 2C₁₇H₃₅COONa (sodium stearate) + ZnSO₄ → Zn(C₁₈H₃₅O₂)₂↓ + Na₂SO₄

Description: Sodium stearate (from stearic acid + NaOH) is reacted with zinc sulfate in aqueous solution; Zinc stearate precipitates as a white solid; Precipitate is filtered, washed, dried, and ground. Gives very fine particle size.

Method 3: Fusion Process

Process: Stearic acid + ZnO (or Zn(OH)₂) → Zinc stearate (molten state)

Description: Stearic acid and zinc oxide are mixed and heated above melting point (>120°C) in a fusion kettle; Reaction proceeds in molten state; Product is cooled and pulverized. Higher purity grade is obtained.

Method 4: In-situ Formation (Polymer Compounding)

Process: Zinc oxide + Stearic acid → Zinc stearate (formed during compounding)

Description: Zinc oxide and stearic acid are added directly to rubber or plastic compounds; Zinc stearate forms in-situ during processing (especially common in rubber vulcanization). This is not a production method but an application method.

SECTION 6: FUNCTIONAL PROPERTIES AND MECHANISM OF ACTION

SECTION 7: MAIN APPLICATION AREAS

SECTION 8: SAMPLE FORMULATIONS

PVC Pipe Formulation (Internal Lubricant):

Cement-Based Waterproofing Mortar:

Transparent Face Powder (Cosmetics):

SECTION 9: QUALITY SPECIFICATIONS

SECTION 10: TOXICOLOGICAL PROFILE

SECTION 11: GHS CLASSIFICATION AND LABELING

GHS Classification (in accordance with CLP and UN GHS):

SIGNAL WORD: NONE (not classified as hazardous)

Hazard Pictograms: NONE

Hazard Statements (H-Codes): Not classified as hazardous under GHS regulations.

EU Risk & Safety Phrases (Old System):

NFPA 704 Hazard Classification:

SECTION 12: PRECAUTIONARY STATEMENTS (P-CODES)

SECTION 13: FIRST AID MEASURES

SECTION 14: FIREFIGHTING MEASURES

SECTION 15: STORAGE AND SHELF LIFE

SECTION 16: PACKAGING OPTIONS

SECTION 17: TRANSPORT INFORMATION

SECTION 18: REGULATORY STATUS

SECTION 19: OTHER NAMES AND SYNONYMS

SECTION 20: SUMMARY TABLE

SECTION 21: CRITICAL WARNINGS AND BEST PRACTICES

CRITICAL WARNINGS:

• Not classified as hazardous under GHS. Non-toxic, non-irritating, non-carcinogenic.

• Combustible organic material. May form explosive dust clouds when finely dispersed. Avoid dust accumulation.

• Dust may cause mechanical irritation to eyes, skin, and respiratory system. Use appropriate dust control measures.

• Not approved as direct food additive (unlike magnesium stearate). Limited food contact applications with regional compliance.

• Practically non-hygroscopic – does not absorb moisture from air. Advantage for moisture-sensitive formulations.

• Incompatibilities: Strong mineral acids (decomposition to stearic acid and zinc salts), strong oxidizing agents, strong bases.

• Melting point 120-124°C – melts during polymer processing to provide lubrication.

• Soapy texture – provides lubricity and anti-tack properties.

• Zinc content ~10-10.5% – important for PVC stabilization and vulcanization applications.

BEST PRACTICE RECOMMENDATIONS:

Plastics & Rubber Industry: Use as internal/external lubricant in PVC compounds (0.1-1.0 phr); Use as mold release agent and dusting powder in rubber (1-5 phr); Use as PVC heat stabilizer co-stabilizer (synergistic with calcium stearate); Pre-blend with polymer before compounding; For rubber, use as dusting powder to prevent sheets from sticking; For rigid PVC, typical ratio: Ca/Zn stearate 2:1 to 3:1.

Paints & Coatings: Use as matting agent, defoamer, and anti-settling agent; Add at 1-5% by weight in paints/coatings; For varnishes: 2-10%; Add during pigment dispersion stage; Provides sanding aid for surface finishing; Use in flat and semi-gloss formulations.

Construction Chemicals: Use as water repellent in cement-based mortars and grouts; Add 0.5-3% of cement weight; Dry blend with cement and fillers before water addition; Improves water resistance and reduces capillary water absorption.

Cosmetics & Personal Care: Use as emulsifier, thickener, and lubricity agent in powders and foundations; Powder formulations: 1-10%; Emulsions: 0.5-3%; Provides soft, silky, soapy feel; Improves adhesion and spreadability; Approved INCI name: Zinc Stearate.

Pharmaceuticals: Use as anti-tacking agent and lubricant in tablets (external use); Tablet compression: up to 2% (external phase); Not for internal use as primary lubricant (magnesium stearate preferred); Ensure pharmaceutical grade quality.

Paper & Packaging: Use in specialty paper and thermal paper coatings; Provides water resistance and improved surface properties; Coating formulations: 0.2-1.0%; Apply as surface sizing.

Textile: Use as hydrophobic finish and surface smoothness agent; 0.5-2% by bath weight; Apply to fabrics for water repellency.

Powder Metallurgy: Use as internal lubricant and mold release agent; 0.5-1.5% of metal powder weight; Mix thoroughly with metal powder before pressing; Improves green strength and reduces ejection force.

Handling: Use in well-ventilated areas; Avoid dust formation; Use dust masks (N95/FFP2) when handling powder; Use gloves and safety goggles.

Personal Protective Equipment: Dust mask (N95/FFP2 or higher), safety goggles, protective gloves (nitrile, neoprene). Not required for solution/dispersion handling.

Hygiene: Wash hands thoroughly after handling; Do not eat, drink, or smoke while using.

Storage: Store in tightly closed, moisture-proof containers; Store in a cool, dry, well-ventilated area (<30°C); Protect from direct sunlight, heat, and moisture; Avoid dust accumulation (explosion risk); Keep away from incompatible materials; Shelf life: 24-36 months under proper conditions.

Spill Management: Sweep or vacuum (HEPA) and place in suitable sealed container; Avoid dust formation; Do not allow entry into drains or waterways.

Disposal: Dispose of in accordance with local, regional, and national regulations; Non-hazardous waste; Can be incinerated in compliance with regulations.

SPECIAL NOTE ON PVC STABILIZATION:

Zinc stearate is a key component in calcium-zinc (Ca/Zn) PVC stabilizer systems:

• Function: Acts as acid acceptor (scavenges HCl); Provides long-term heat stability; Synergistic effect with calcium stearate.

• Mechanism: Zinc stearate reacts with HCl to form zinc chloride; Calcium stearate reacts with zinc chloride to regenerate zinc stearate (synergistic cycle); Prevents discoloration and degradation of PVC.

• Typical ratio: Calcium stearate : Zinc stearate = 2:1 to 3:1.

• Limitation: Zinc stearate alone can cause "zinc burn" (sudden degradation) if overused; Balanced with calcium stearate for optimal performance.

• Applications: Rigid PVC pipes, profiles, films; Flexible PVC cables, hoses; Food contact PVC (with appropriate approvals).

SPECIAL NOTE ON COSMETIC APPLICATIONS:

Zinc stearate is widely used in cosmetic powders and color cosmetics:

• INCI Name: Zinc Stearate

• Function: Provides soft, silky, soapy feel; Improves adhesion and spreadability; Acts as emollient and thickener; Imparts smoothness and opacity.

• Applications: Face powders, foundations, blushes, eye shadows, lipsticks.

• Concentration: 1-10% in powders; 0.5-3% in emulsions.

• FDA Status: Approved as color additive for cosmetics (21 CFR 73.2252 – subject to purity requirements).

• EU Status: Approved cosmetic ingredient.

• Purity Requirements: Low heavy metals (Pb < 5 ppm, As < 2 ppm); Low free fatty acid (< 1.0%); Fine particle size (< 5 µm).

SPECIAL NOTE ON RUBBER VULCANIZATION:

Zinc stearate is used in rubber processing:

• Function: Activates vulcanization (as zinc oxide precursor); Lubricates rubber sheets (dusting powder); Prevents sticking of uncured rubber.

• Mechanism: Zinc stearate reacts with stearic acid to form zinc soap; Zinc soap accelerates sulfur vulcanization; Provides faster cure and improved physical properties.

• Application: Dusting powder on uncured rubber sheets (1-5 phr); Activator in rubber compounds (0.5-2 phr); Prevents adhesion to molds and calenders.

• Advantage: Provides excellent release properties; Improves surface finish of rubber products.

SPECIAL NOTE ON FOOD CONTACT APPROVALS:

Zinc stearate has limited food contact approvals:

• EU: Approved under EU 10/2011 for food contact plastics; Specific migration limits apply (zinc migration ≤ 25 mg/kg food).

• USA (FDA): Listed in 21 CFR for certain food contact applications; Not GRAS as direct food additive.

• Not a direct food additive (unlike magnesium stearate which is GRAS).

• Check regional regulations before use in food contact applications.

• Ensure compliance with specific migration limits for zinc and stearic acid.

LEGAL DISCLAIMER:
The information provided in this document is based on our current knowledge and experience and is presented in good faith. However, as all conditions of use are beyond our control, it does not constitute a binding specification or warranty. This Technical Data Sheet is for informational purposes only. Users are responsible for testing the suitability for their own applications. For complete safety, storage, use, handling, waste, and regulatory compliance information, please refer to the official Safety Data Sheet (SDS/MSDS) provided by the manufacturer/supplier.