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CN-122010154-A - Method for preparing high-whiteness cubic nano calcium carbonate at low temperature

CN122010154ACN 122010154 ACN122010154 ACN 122010154ACN-122010154-A

Abstract

The invention discloses a method for preparing high-whiteness cubic nano calcium carbonate at low temperature. The invention prepares the cubic nano calcium carbonate with high whiteness, high dispersion, uniform particle size and high crystal form regularity by (1) low-temperature control of the carbonization whole process and (2) adding coumarin fluorescent whitening agent in the carbonization stage by adopting a carbonization-whitening integrated system. Experimental results show that the whole process of carbonization is controlled at low temperature, and coumarin fluorescent whitening agents are added to improve the whiteness, the crystal form regularity, the dispersibility and the narrowed particle size distribution of the nano calcium carbonate. The cubic nano calcium carbonate crystal prepared by the method has regular morphology and narrow particle size distribution, and has high whiteness and high dispersibility.

Inventors

  • DONG YANCHUN
  • YU SHAOQIANG
  • HU JIASHUN
  • NIU ZHENJIE
  • WANG JINGMING

Assignees

  • 湖北三峡实验室
  • 襄阳兴发化工有限公司

Dates

Publication Date
20260512
Application Date
20251124

Claims (10)

  1. 1. The method for preparing the high-whiteness cubic nano calcium carbonate at low temperature is characterized by comprising the following steps of: S1, calcining limestone at high temperature to obtain calcium oxide; S2, weighing a certain amount of calcium oxide, adding the calcium oxide into water at 40-80 ℃ for digestion reaction, and slaking after the slaking is finished to obtain calcium hydroxide slurry; S3, mixing slaked calcium hydroxide slurry, putting the mixture into a carbonization reaction kettle, adding a crystal form control agent, stirring uniformly, starting to introduce CO 2 gas, adding a dispersing agent to continue the reaction after the gel phenomenon occurs, adding a brightening agent in the later stage of the reaction, and marking the reaction end when the pH value is reduced to below 6.5; s4, heating the slurry obtained in the step S3 to 60-90 ℃, starting stirring, and carrying out aging reaction under the condition of heat preservation; and S5, after the aging reaction is finished, adding a surfactant to perform an activation reaction, and then performing suction filtration, washing and drying to obtain the high-whiteness cubic nano calcium carbonate.
  2. 2. The method for preparing high-whiteness cubic nano calcium carbonate at low temperature according to claim 1, wherein the concentration of calcium hydroxide slurry in the step S3 is in the range of 4% -12%, the initial carbonization temperature is 10% -30 ℃, the concentration of CO 2 is 30% -40%, the stirring speed is 1000-2500 r/min, the gas flow rate of CO 2 is 1.0-6.0 ml/min, the whole-process temperature control is carried out by using a high-low temperature circulating integrated machine, the reaction maximum temperature is controlled to be less than or equal to 40 ℃, and the whole-process reaction process is monitored by a pH meter.
  3. 3. The method for preparing high-whiteness cubic nano calcium carbonate according to claim 1, wherein the crystal form control agent used in the step S3 is one of sucrose or glucose, and the dosage is 0.1% -0.5% of the dry mass of calcium hydroxide.
  4. 4. The method for preparing high-whiteness cubic nano calcium carbonate according to claim 1, wherein the dispersant used in the step S3 is at least one of trisodium citrate, sodium tartrate, sodium dodecyl benzene sulfonate, sodium hexametaphosphate, sodium pyrophosphate, sodium silicate, sodium alginate, sodium polyacrylate, sodium styrene-maleic anhydride copolymer and sodium hydroxymethyl cellulose, and the dosage is 0.1% -4% of the dry mass of calcium hydroxide.
  5. 5. The method for preparing high-whiteness cubic nano calcium carbonate at low temperature according to claim 1, wherein the brightening agent used in the step S3 is coumarin fluorescent brightening agent, and the total consumption is 0.1% -3% of the dry basis of calcium hydroxide.
  6. 6. The method for preparing high-whiteness cubic nano calcium carbonate according to claim 5, wherein the coumarin fluorescent whitening agent is at least one of 7-amino-4-methylcoumarin, 7-diethylamino-4-methylcoumarin, 6, 7-dihydroxycoumarin, 4,5, 7-trihydroxy-3-phenylcoumarin, 3-cyano-7-hydroxy-4-methylcoumarin, 5, 7-dihydroxy-4-methylcoumarin and 5, 7-dihydroxy-4-phenylcoumarin.
  7. 7. The method for preparing high-whiteness cubic nano calcium carbonate at low temperature according to claim 1, wherein the surfactant used in the step S5 is a saponified fatty acid sodium compound borate modifier, and the dosage is 2% -8% of the dry mass of the calcium carbonate.
  8. 8. The method of preparing cubic nano calcium carbonate with high whiteness according to claim 7, wherein the saponified sodium fatty acid used in the step S5 is at least one of sodium stearate, sodium laurate, sodium oleate, sodium palmitate and sodium myristate, and the borate used is at least one of diethanolamine borate, triphenylborate, tris (trimethylsilyl) borate ‌ (TMSB) and ‌ distearyloxy isopropyl borate ‌ (LD-100P).
  9. 9. A high whiteness cubic nano calcium carbonate, comprising the nano calcium carbonate obtained by the preparation method according to any one of claims 1 to 8.
  10. 10. Use of the high whiteness cubic nano calcium carbonate according to claim 9 in new energy, electronic information, biological medicine, high grade paper, automotive paint, high performance plastic products or environmental treatment.

Description

Method for preparing high-whiteness cubic nano calcium carbonate at low temperature Technical Field The invention discloses a novel method for preparing cubic nano calcium carbonate with high whiteness and excellent regular crystal form dispersibility at low temperature. Background The nano calcium carbonate is an ultrafine inorganic filler with the particle size of 1-100 nm, and has the conventional advantages of the calcium carbonate, the special surface effect of the nano material, the small-size effect and the quantum size effect. Along with the maturation of the technologies such as critical carbonization, biological templates, in-situ modification, composite functionalization and the like, the preparation method endows the material with excellent activity in terms of photo-thermal resistance, magnetism, mechanics, chemistry, catalytic performance and the like, so that the material becomes a novel inorganic functional material, and has wide application value in high-end application scenes such as new energy, electronic information, biological medicine, high-grade paper, automobile paint, high-performance plastic products, environmental management and the like. The existing preparation method of the nano calcium carbonate is mainly a chemical method, wherein the chemical method also comprises a carbonization method, a double decomposition method, a precipitation method, an emulsion method and a sol-gel method, and the carbonization method is a main production process for industrially preparing the nano calcium carbonate, but has the problems of long carbonization time, poor quality stability, irregular shape, uneven particle size distribution, easy alkali return of products, serious particle agglomeration and the like, and influences the application of the nano calcium carbonate in downstream products. Therefore, further improvement and optimization of the production process are urgently needed, and a novel production process of nano calcium carbonate with regular crystal form, narrow particle size distribution and good dispersibility is developed. Whiteness is one of the key indexes for evaluating the quality of nano calcium carbonate, and not only affects the quality of powder, but also affects the market price and the downstream application field. The whiteness of paper making, water paint and toothpaste is generally more than or equal to 93%, and the whiteness of high-end art paper and UV wood lacquer is even more than or equal to 96%. The mineral deposits in China mainly comprise medium-low grade limestone ores, wherein Si, mg, fe, mn and other impurities have high content, and the nano calcium products produced by the lime through the conventional carbonization process have low whiteness and cannot meet the national standard requirements. At present, the whitening research on nano calcium carbonate is relatively less, the conventional nano calcium carbonate whitening method in the prior art is mainly an oxidation-reduction method, but the strong reducing agent added in the process is easy to cause side reactions, so that excessive consumption of the medicament can be caused, the quality of the product can be influenced, and the yellowing problem of the product can be caused if the product is not washed and dried in time, so that a novel whitening technology is yet to be developed. Disclosure of Invention In order to solve the problems, the invention provides a novel method for preparing cubic nano calcium carbonate with high whiteness and excellent regular and dispersive crystal form at low temperature, which comprises the following steps: S1, calcining limestone at high temperature to obtain calcium oxide; S2, weighing a certain amount of calcium oxide, adding the calcium oxide into water at 40-80 ℃ for digestion reaction, and slaking after the slaking is finished to obtain calcium hydroxide slurry; s3, mixing slaked calcium hydroxide slurry, putting the mixture into a carbonization reaction kettle, adding a crystal form control agent, stirring uniformly, introducing CO 2 gas, adding a dispersing agent to continue the reaction after the gel phenomenon occurs, and adding a brightening agent at the later stage of the reaction (namely, when the pH is about 7-12 in alkaline or weak alkaline environment), wherein the pH is reduced to below 6.5 to mark the end of the reaction; S4, heating the slurry obtained in the step S3 to 60-90 ℃, starting stirring, and carrying out aging reaction under the condition of heat preservation; and S5, after the aging reaction is finished, adding a surfactant to perform an activation reaction, and then performing suction filtration, washing and drying to obtain the high-whiteness cubic nano calcium carbonate. Preferably, in the step S1, the content of limestone calcium carbonate is more than or equal to 85 percent, the content of magnesium is less than or equal to 0.5 percent, and the particle size is 15-30 mm. Preferably, in the step S1, the calcination temperature of t