Calcium stearate is a white powder, insoluble in water, cold ethanol and ether, soluble in organic solvents such as hot benzene, benzene and turpentine, and slightly soluble in hot ethanol and ether. When heated to 400, it decomposes slowly and is combustible. In case of strong acid, it decomposes into stearic acid and corresponding calcium salt, which has hygroscopicity.

Qingdao Sainuocalcium stearate has no sulfur pollution, with good long-term thermal stability, good Lubrication and demoulding performance.

1. Production method of calcium stearate

(1) Direct method

Add a certain amount of stearic acid and CaO into the reaction pot equipped with stirrer and thermometer, raise the temperature to melt, slowly add catalyst H2O2 under continuous stirring, vacuum, control the reaction temperature at 140 ~ 150 and react for 1.5 ~ 2.0h. After the reaction, the product is obtained by discharging, cooling and crushing.

(2) Double decomposition method

Dissolve stearic acid in 20 times the mass of hot water, add saturated caustic soda solution, and carry out saponification reaction at about 75℃ to produce dilute sodium stearate solution. Then add the calcium chloride solution with the content of 1074kg / m3 to the sodium stearate solution, carry out the double decomposition reaction at about 65℃, and the product calcium stearate is precipitated. Then, after filtration, water washing and drying at about 90℃, the finished product is obtained.

2. Lubricating effect of calcium stearate in PVC formula

Calcium stearate is used as heat stabilizer of PVC, lubricant and release agent for various plastic processing. As a PVC lubricant, it is generally considered as an internal lubricant. Calcium stearate is a stearate of medium and strong alkali calcium, which has strong polarity. The chemical active point of PVC resin particles can form a stable complex system with calcium stearate. The two long-chain alkyl groups of calcium stearate have less compatibility with polar resins such as PVC, and form a local micro two-phase interface in PVC resin, that is, lubricating film. The microscopic essence of its lubrication effect is that the force between the local lubrication interface formed by non-polar long-chain alkyl and the polar resin chain segment is less than that between the resin chain segments. In addition, because there are many small pores between the resin chain segments, when the resin chain segment is displaced, the alkyl that can be deformed arbitrarily is squeezed into other adjacent pores, Thus, the resistance during the displacement of the resin chain segment is reduced and the internal lubrication function is played.

In practical application, calcium stearate as a PVC lubricant does not only play the role of internal lubrication, but its lubrication role is more complex. When the proportion of other internal lubrication is relatively high, it will reflect the role of external lubrication. Moreover, it works synergistically with many lubricants.

In hard products, the combination of salt based lead and lead soap can increase the gelation rate. It is also used for food packaging, medical appliances and other soft films and appliances requiring no toxicity. It can be used as halogen absorber for PE and PP to eliminate the adverse effects of residual catalyst on color and stability. As a plasticizer in rubber processing, it can soften natural rubber and synthetic rubber, but has little effect on vulcanization. It is also used as a lubricant for polyolefin fibers and molding plastics, a thickener for lubricating grease, a waterproof agent for textiles, a smoothing agent for paint, a plasticizer in the manufacture of plastic records, a lubricant and release agent for thermosetting plastics such as phenolic and amino, a lubricant for pencil lead, and food grade calcium stearate as an anti caking agent. 

Using calcium stearate alone in the formula can accelerate plasticization, improve melt viscosity, increase torque, and have a certain demoulding effect, while using paraffin alone can delay plasticization, reduce torque and have no demoulding effect. When calcium stearate and paraffin wax (polyethylene wax) are mixed in a certain proportion, it shows a good effect, and the material torque value can be greatly reduced. This is because the paraffin penetrates into the calcium stearate molecules, strengthens the lubrication, shows a strong synergistic effect, and changes the dispersion of the lubricant.

3. Other applications

(1) Calcium stearate is a good non-toxic heat stabilizer and lubricant. It is also a smoothing agent and water resistant agent for adhesives and coatings. It is widely used in chemical production processes such as plastics and rubber. The thermal stability effect is not as good as barium stearate, lead stearate, tin stearate and cadmium stearate. However, it is cheap and easy to obtain, with low toxicity and good processing performance. Combined with zinc soap and epoxy compound, it has synergistic effect and can improve thermal stability. It is commonly used in food packaging film, medical appliances and other soft products requiring non-toxic. It is also widely used as lubricant and release agent for thermosetting plastics such as polyolefin, polyester reinforced plastics, phenolic resin and amino resin.

(2) Used as perfume powder in cosmetics. When added to the fragrance powder, it has strong adhesion to the powder, good lubricity, uniform spreading, and good formability of the fragrance powder.

4. Precautions for use of calcium stearate

(1) When manufacturing PVC transparent products, the addition amount of calcium stearate shall not be greater than 0.5 phr, otherwise the transparency of PVC materials will be affected;

(2) When calcium stearate is added in lead salt composite stabilizer, excessive addition will lead to superplasticity, affect the lubrication system and reduce the strength of mechanical products;

(3) In the calcium zinc composite heat stabilizer system, too low proportion of calcium stearate will lead to poor initial thermal stability, too high proportion will make PVC products yellow and poor weather resistance;

(4) Calcium stearate will affect the decomposition temperature of foaming agent, so the addition amount of stabilizer can be appropriately increased.

Qingdao Sainuo Chemical Co., Ltd. We are manufacturer of  PE wax, PP wax, OPE wax, EVA wax, PEMA, EBS, Zinc/Calcium Stearate…. Our products have passed the REACH, ROHS, PAHS, FDA testing.

Sainuo rest assured wax, welcome your inquiry!

Website：https://www.sainuowax.com

E-mail：sales@qdsainuo.com

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