Preparation method of nanometer calcium carbonate for automobile primer

Abstract

The invention discloses a preparation method of nanometer calcium carbonate for an automobile primer. The preparation method comprises the following steps: adjusting the specific gravity of refined lime milk to 1.055-1.080, controlling the temperature at a certain value, adding a metal salt crystal form control agent, performing uniform mixing, then introducing the obtained mixture into a bubblingcarbonation reaction kettle, performing a carbonation reaction, stopping the reaction when the pH value of the obtained slurry is less than or equal to 7 in order to obtain a calcium carbonate suspension, heating the calcium carbonate suspension to 55-75 DEG C, adding an agent composed of higher sodium aliphatate, a modified imide cyclosilane coupling agent and epoxidized cyclohexane dioctyl phthalate under the stirring of an emulsifying machine, and performing compounding to obtain a surface treating agent; performing continuous stirring for 30-90 min to finish surface modification treatmentin order to obtain a modified nano calcium carbonate suspension; and carrying out press filtration, drying, crushing and sieving to obtain the nanometer calcium carbonate for the automobile primer. The automobile primer obtained by filling with the prepared nanometer calcium carbonate filled has excellent thixotropy, remarkably reduced shear viscosity and improved anti-sagging performance, well meets the performance requirement of the automobile primer, and has a very broad market prospect.

Description

technical field [0001] The invention relates to the technical field of nano-calcium carbonate, in particular to a preparation method of nano-calcium carbonate for automobile primers. Background technique [0002] Nano-calcium carbonate can be used as a filler or reinforcing agent for coatings, plastics, rubber, polymer resins, etc. to improve product performance. Usually the surface of nano-calcium carbonate particles is hydrophilic and oleophobic, and nano-calcium carbonate without surface modifier is easy to agglomerate, its dispersion in organic matter is poor, and its binding performance with organic matter is not good, so surface modification is required to enhance Its combination with organic matter, as an important component in the formula of automobile primer, nano-calcium carbonate provides thixotropy for automobile primer, ensures good construction performance during construction, and improves the tensile strength and elongation at break of the coating. Rate and y...

AI Technical Summary

Problems solved by technology

[0004] Chinese patent CN 104098928 A discloses a preparation method of nano-calcium carbonate with negative thixotropy and its thixotropy test method. The specific surface area of ​​calcium carbonate produced by this method is relatively high, up to 40m 2 / g, which is not conducive to the dispersion of nano-calcium carbonate in the automotive primer, and will also affect the fluidity of the automotive primer, and is not suitable for the application of automotive primer systems

[0005] Chinese patent CN 109054526 A discloses a preparation method of modified nano-calcium carbonate for PVC automobile primers. The calcium chloride method used in the method needs to use more types of raw materials when preparing nano-calcium carbonate, and the cost is greater, which is not conducive to large-scale production. batch industrial production

[0006] Chinese patent CN 103756365 A discloses a surface treatment method for nano-calcium carbonate. This method uses dry treatment, and the coating effect of the treatment agent is not as good as that of wet treatment. The treatment agent used is stearic acid, and the organic chain of fatty acid is relatively short. And without polar groups, the possibility of entanglement with the organic polymer of the car primer is reduced, and the molecular force is also reduced

Automobile primer is a highly polar organic system. Even if the nano-calcium carbonate with fatty acid treatment agent is stirred at high speed with high-speed dispersant, the dispersion is relatively poor and the agglomeration is serious

[0007] Chinese patent CN 107739530 A discloses a method for preparing a highly thixotropic nano-calcium carbonate specially used for coatings. Ethylene glycol is used in the carbonization reaction, which has certain toxicity. There is no specific data in this scheme to indicate that the product has high thixotropy, such as thixotropy Index, thixotropic ring area to illustrate that the nano-calcium carbonate produced by this method has high thixotropy

[0008] Chinese patent CN 101451023 A discloses a surface-modified nano-calcium carbonate and its polyvinyl chloride plastisol. The nano-calcium carbonate prepared by this method needs to be placed at room temperature for too long, and the acid value of the carboxyl-terminated polyamide resin used in the scheme Strict control is required. If the acid value is too small, it is not conducive to the formation of covalent bonds with calcium carbonate. If the acid value is too large, it may not be conducive to the synthesis of this type of carboxypolyamide resin. The control requirements are too high, and the cost will increase if the control is not good.

[0010] In summary, there are still many defects in the current production method of nano-calcium carbonate for automotive primers. The existing surface modification methods of nano-calcium carbonate for automotive primers cannot meet the performance requirements of automotive primer preparation companies.

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