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What is Sodium Stearate?

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Update time : 2019-10-10 10:44:17

Sodium stearate is also known as sodium octadecanoic. White fine powder or lumpy solid with a slippery feel, a fatty taste, and water absorption in the air. Soluble in hot water or hot alcohol, decomposed into stearic acid, and the corresponding sodium salt in case of acid. Insoluble in ether, light gasoline, acetone, and similar organic solvents. It is also insoluble in electrolyte solutions such as salt and sodium hydroxide. The aqueous solution is alkaline due to hydrolysis, and the alcohol solution is neutral. It is prepared by the interaction of stearic acid and sodium hydroxide. It is widely used in the manufacture of toothpaste, soap, and cosmetics, as well as waterproofing agents, plastic stabilizers, and adhesives. Sodium stearate is an organic substance and is a natural acid salt.

 

Sodium stearate is obtained by the metathesis reaction of calcium stearate and sodium chloride. The metal calcium content is 6.5%, the melting point is 149-155 ° C, the hearing loss is less than 2%, the relative density is 1.08, and the fineness is 0.075 mm. 99.5%, free acid (calculated as stearic acid) 0.5%, water-absorbent in air.

 

Sodium stearate can be used as a heat stabilizer for polyethylene. It has excellent lubricity and good processing properties. It has a synergistic effect with zinc soap and epoxy compound, can improve thermal stability, and base-based lead salt and lead. Soap is used in hard products to increase the rate of gelation. The use of sodium stearate in polyethylene and polypropylene eliminates the adverse effects of residual catalysts on the color and stability of the resin. This product is also widely used as a lubricant and release agent for polyolefins, polyester reinforced plastics, phenolic resin amino resins, and other heat-curing plastics.

 

 
 

Preparation:

 

1. Stearic acid was added to the reaction vessel, heated to melt, and then added with NaOH aqueous solution under stirring, heated at 65 ° C for two h, and the pH was controlled at 8.0 to 8.5. Spray-dried to give the product. C17H35COOH+NaOH=C17H35COONa+H2O

 

2, 10g stearic acid is dissolved in 100mL 95% ethanol, titrated with 0.5mol / L sodium hydroxide ethanol solution, using phenolphthalein as an indicator, titrated to the equivalent point, the precipitated sodium stearate soap Filter out. The crude product can be recrystallized from 95% ethanol to give a pure product.

 

The chemical equation for the reaction of sodium stearate with water C17H35COONa+H2O=reversible=C17H35COOH+NaOH

 

Saponification reaction chemical equation of sodium stearate

CH2OCOC17H35

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CHOCOC17H35 + 3NaOH ----> 3C17H35-COONa + CH2OH-CHOH-CH2OH

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CH2OCOC17H35

use:
 
1. It is used in the manufacture of toothpaste. It is also used as a waterproofing agent and plastic stabilizer for metal heat treatment and chemical stabilizer for soap detergent. It is used as an emulsifier in cosmetics.
 
2. Used in the manufacture of soap detergents. It is used both as an active agent and as an excipient in block soaps, as an emulsifier for cosmetics and as an emulsifier for O/W type products.
 
Detergent: Used to control the foam during the rinsing process. (Sodium stearate is the main ingredient of soap)
 
Emulsifier or dispersant: used for emulsification of polymers and medium antioxidants.
Corrosion inhibitor: It has protective properties and the like in a polyethylene packaging film.
 
Cosmetics: shaving gel, transparent adhesive, etc.
 
Adhesive: used as natural rubber and then attached to the paper
 
Toxicity:
 
By studying the irritating effects of sodium stearate on the skin, including the permeability of its aqueous solution, it was found that the skin absorption rate of the 0.5% solution concentration was about 0.1%, and it was found that there was a close relationship between osmosis and skin irritation. Sodium stearate caused a lower percentage of positive reactions in the test for allergic skin contact tests, but sodium stearate had a little detrimental effect in cosmetic cold creams. It has been observed that the stenching effect of sodium stearate raw milk is likely to be caused by the deposition of calcium soap and other similar soaps on the skin. (If you wash your face with hard water, it will produce calcium soap.) Some of the residues of the cold cream will remain irritating on the skin.
 
 
Storage and transportation:
 
Sealed in a cold, dry, and ventilated place to preserve the taste, soluble in hot water or alcoholic water, water-absorbing in the air, the solution is alkaline due to hydrolysis. It should be stored in a cool, dry, ventilated place.
 
First aid:
 
Inhalation: If inhaled, move the patient to fresh air.
 
Skin contact: Remove contaminated clothing and wash skin thoroughly with soap and water. If you still feel unwell, seek medical attention as soon as possible.
 
Eye contact: Separate the eyelids and rinse with running water or saline. Then seek medical attention immediately.
 
Ingestion: gargle, be careful not to induce vomiting! Then seek medical attention immediately.
 
Advice for protecting the rescuer: First, transfer the patient to a safe place. Consult a doctor and present this chemical safety data sheet to the doctor on site.