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Source lei little knowledge | rubber industry with what kind of calcium carbonate?

Release time:

2024-01-29 09:34

For rubber, calcium carbonate is the third largest inorganic filler after carbon black and white carbon black. It has certain reinforcing effect in natural rubber and synthetic rubber, which can improve or strengthen the tensile strength and abrasion resistance of rubber vulcanized body, improve the tear strength, adjust the Mooney viscosity of rubber mixture, increase plasticity and facilitate molding.

 

 

What kind of calcium carbonate is used in the rubber industry?

At present, the common calcium carbonate products on the market mainly include light calcium carbonate, heavy calcium carbonate, active calcium carbonate, nano calcium carbonate, etc.

(1) Light calcium carbonate

Light calcium carbonate has a semi-reinforcing effect in rubber, which can improve the mechanical properties of rubber, is easy to disperse, and does not affect the curing speed. Used in the manufacture of rubber hose, tape, rubber plate, tape products, rubber shoes, etc. Used in natural rubber and styrene-butadiene rubber, the amount can be as high as 140 parts, in the natural rubber hot water bag glue in the amount of 75 parts, in the neoprene rubber printing roller in the amount of 20 parts.

(2) active light calcium carbonate

The active calcium carbonate after surface modification has a reinforcing effect in rubber, and its reinforcing performance can be compared with white carbon black. Commonly used as white, light color and color rubber products reinforcing agent. It is easy to disperse in the rubber, but the heat generation is large, and the vulcanization speed will be accelerated after activation. Used in the manufacture of tire buffer layer rubber, inner tube, bicycle inner and outer tube, transmission belt cover rubber, etc., suitable for natural rubber, SBS and latex, in SBS reinforcing effect is obvious, coloring performance is also good.

(3) Heavy calcium carbonate

Heavy calcium carbonate has no reinforcing effect in rubber. It plays a role of filling and compatibilizing in natural rubber, synthetic rubber and latex. It has good dispersion in rubber compound. It can also be used as separating agent or release agent. Whiteness higher than 90% can also be used as whitening agent. Can be used in the manufacture of hose, tape, rubber shoes, extrusion products and foam products. Used in natural rubber, nitrile rubber hose, the amount of up to 80%; used in natural rubber insulation tape, the amount can be as high as 200%.

 

 

(4) Nano calcium carbonate

Nano-calcium carbonate is a fine product of calcium carbonate, and it is also one of the cheapest nanomaterials. Its special quantum size effect, small size effect, surface effect, etc., make it compared with conventional powder materials in the reinforcement, transparency, dispersion and other aspects show obvious advantages.

Crystal form: among the different crystal forms of nano calcium carbonate, the chain-like nano calcium carbonate has the best reinforcing effect on rubber, followed by cubic nano calcium carbonate.

Particle size: Cubic nano calcium carbonate to 80 ~ 120nm is appropriate, the application of nano calcium carbonate in rubber, the finer the particles, the larger the specific surface area of mutual infiltration with rubber, so that the dispersion of calcium carbonate particles is more and more difficult, especially below 80nm, due to the increase of surface energy, in rubber mixing is easy to heat and cause sticky mixing.

The short diameter of the chain-like nano-calcium carbonate should be between 10 and 30nm, but good surface modification and dispersion treatment must be carried out to improve its application effect.

Surface treatment: to choose the appropriate auxiliary dispersant, to improve the blending and dispersion effect.

Oil absorption value: the higher the oil absorption value of nano calcium carbonate for rubber, the better the wettability and reinforcement of calcium carbonate to rubber.

Moisture: As a filler for rubber, the lower the moisture content of nano calcium carbonate, the better, generally less than 0.5%.

(5) Calcium carbonate whiskers

At present, the use of asbestos fibers in friction materials has been banned internationally, and the main materials replaced by inorganic whiskers and natural plant fibers.

Calcium carbonate whisker has the advantages of simple preparation process, strong operability and low cost, which is suitable for large-scale production, and does not cause pollution in the process of use, and belongs to the green environmental protection material.

Calcium carbonate whiskers have good physical properties, mechanical properties, heat recession resistance and heat recovery properties, in addition to excellent high temperature friction and wear properties.

 

Calcium carbonate, rubber, nano, natural rubber, dispersion, material, effect, dosage, surface

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