Stearic Acid
Time: 2012-10-01 16:05:41
Stearic Acid
Synonyms
Octadecanoic Acid;
Category
Anionic Surfactant
>> Carboxylate
>> Chain Carboxylate
>> Alkyl Carboxylate
>> Linear Alkyl Carboxylate
Chemical Numbering System
CASRN57-11-4
EINECS200-313-4
Molecular Formula & Molecular Weight
Molecular Formula: C18H36O2
Molecular Weight: 284.48
Structure
 
Properties
Appearance    (1), white or pale yellow waxy solid.
Solubility    insoluble in water. soluble in ethanol, acetone, ether, chloroform, carbon tetrachloride, benzene, carbon disulfide.
Physical - chemical properties
Water solubility, mg/L
0.597 / 0.568 (25°C)[1]
Melting point, °C
69.3[1]
Stability    stable.
Risk    Solid form: flammable material; irritation, irritation to skin, eye, respiratory system. Harmful products of combustion are CO, CO2 and so on. Contact with strong oxidants, can cause to burn.
GHS (Rev.6) label:  
Animal Toxicity
Table 1 Animal toxicity values
rat oral LDLo
4640mg/kg[2]
rat intravenous LD50
21.5mg/kg[2]
rabbit skin LD50
> 5000mg/kg[2]
mouse intravenous LD50
23mg/kg[2]
Ecology    may be hazardous to environment. Water body should be given special attention.
Biodegradability    biodegradable.
Characteristics    excellent lubricating, cleansing, emulsifying, dispersing, solubilizing abilities. Nonresistant to hard water. Typical ingredient in soap.
Note    (1), Commercial stearic acid is actually a mixture of stearic acid and palmitic acid, and contains a small amount of oleic acid, has a slightly fat odor.
Synthesis
The main production methods of industrial stearic acid have fractionation method and pressing method.
1, Fractionation method
(1), The crude fatty acids are obtained by saponifying hydrolysis reaction of animal fat or hardened oil.
(2), Crude fatty acids are washed, distilled and decolored, then obtain finished stearic acid. At the same time, obtain by-product glycerin.
Quality Standards & Test Methods
1. Physical and chemical indexes
Item
Physical and chemical indexes
Solid
Stearic acid, %, ≥
35.0
Saponification value(as KOH), mg/g
190 - 225
Acid value(as KOH), mg/g
190 - 224
Iodine value(as I2), g/100g, ≤
8.0
Color (15% ethanol solution), Hazen, ≤
400
Freezing point, °C
52.0 - 62.0
Moisture, %, ≤
0.2
Test Methods
GB/T 9104 Test methods for industrial stearic acids
GB/T 18953 Rubber compounding ingredients--Stearic acid--Definition and test methods
ISO 8312 Rubber compounding ingredients -- Stearic acid -- Definition and test methods
2. Hazardous substances indexes
Item
Hazardous substances indexes
Solid
Heavy metals (as Pb), mg/Kg, ≤
20
As, mg/Kg, ≤
3
Test Methods
(1), Heavy metals (as Pb)
Safety and Technical Standards for Cosmetics (2015 Edition)
GB/T 30799 The test method of food detergents - Determination of heavy metals
(2), As
Safety and Technical Standards for Cosmetics (2015 Edition)
GB/T 30797 The test method of food detergents - Determination of total arsenic
3. Product standards
(1), Chinese standards
(1a), GB 1886.101 Food safety national standard -- Food additive -- Stearic acid
(1b), GB/T 9103 Industrial stearic acids
(1c), Chinese Pharmacopoeia (2015 Edition) Stearic acid
4. Further explanation
(a), On physical and chemical indexes: firstly, shall be indicated carbon atom distribution; secondly, shall be indicated average molecular weight.
(b), Used in cosmetics, should be test for harmful substances; or furtherly test for microorganisms.
Major Uses
1. Typical applications
Use as lubricant.
Use as cleansing agent.
Use as emulsifying agent, dispersing agent.
2. Household detergents
Use as cleansing agent.
3. Personal care products
Cleansing agent, emulsifying agent, emulsifying stabilizing agent, refatting agent, emollient in personal care products.
Can make the paste stable and white.
4. Machinery industry
Lubricant in metal processing, machinery.
5. Rubber industry
Vulcanization active agent, plasticizer, softening agent, emulsifying agent, release agent in synthesis and processing of rubber.
6. Plastics
Use as heat stabilizer, lubricant. For example: processing and manufacturing of PVC.
Can prevent coking phenomenon in the process, and can prevent finished product discoloration caused by sulfides.
7. Medicine
Pharmaceutical excipients. Use as lubricant, ointment base. (This section is for reference only, should be implemented according to local Pharmacopoeia.)
8. Organic synthesis
Widely used in preparation of stearic acid ester. Stearic acid ester can be used in personal care products, food, medicine, etc.
Widely used in preparation of stearic acid salts. Stearic acid salts can be used in personal care products, household cleaning products, fabricated metal products, plastic products, coatings, etc.
9. Pets
Use as cleansing agent, emulsifying agent.
10. Food
Food additive, use as coating agent, gum base.
Manufacturers
 
References
[1]: HSDB. 57-11-4, Stearic Acid
[2]: ChemIDplus. 57-11-4, Stearic Acid
Update: 20131102(1); 20171215(2);