CN101353486A - A kind of preparation method of calcium carbonate composite particle - Google Patents

Abstract

The invention discloses a method for preparing calcium carbonate composite particles. The method comprises: adding water glass to calcium carbonate slurry with a concentration of 5% to 20% for mixing, heating the mixed slurry to 80-90°C, React under the stirring state of 1000 rpm ~ 1500 rpm, the reaction time is 0.5 ~ 1 hour, and add a pH regulator to adjust the pH of the slurry to 7 ~ 11, after the reaction, the temperature is 80 ~ 90 ° C Aging, the aging time is 2-5 hours, drying at a temperature of 120-140°C after aging, and pulverizing after drying to obtain calcium carbonate composite particles. The method uses a pH regulator to better control the change of the pH value of the solution, effectively control the SiO ₂ film forming rate, and make the SiO ₂ film form uniformly on the calcium carbonate surface. The hydrolysis of water glass is used to form a tightly bonded hydrated silicon dioxide layer on the surface of calcium carbonate, which has the advantages of simple operation conditions, compact structure of prepared calcium carbonate composite particles, and strong acid resistance.

Description

A kind of preparation method of calcium carbonate composite particle

technical field

The invention relates to a preparation technology of calcium carbonate particles, in particular to a preparation method of calcium carbonate composite particles which can be widely used in various industries as inorganic fillers and the like.

Background technique

Calcium carbonate has the characteristics of easy source of raw materials, low price, low toxicity, high whiteness, large filling capacity and good mixing and processing performance. It is widely used in rubber, paint, papermaking, plastics and other industries. It is an important inorganic filler. However, the surface of calcium carbonate has a strong polarity. When it is applied to those low-polarity polymers, surface modification is required to improve the filler-filler and filler-polymer effects, which is beneficial to the calcium carbonate in the polymer matrix. scattered. When commonly used reactive coupling agents, such as silane coupling agents and titanate coupling agents, are used for surface modification of powders, there should be reactive sites on the surface of the powders. Titanate is easy to interact with calcium carbonate, and the direct interaction between silane coupling agent and calcium carbonate is relatively weak.

Also have the processing method to calcium carbonate in the prior art, these processing methods have sol-gel method (as the hydrolysis reaction of silicate) and chemical precipitation method (as the reaction of sodium silicate and acid). In the prior art, the method of directly reacting sodium silicate and acid to generate precipitation is adopted. Under the influence of acid, SiO ₂ gels too quickly, which will nucleate itself and produce SiO ₂ particles, and the calcium carbonate particles are mixed with SiO ₂ particles; If the gelation is too slow, _SiO2 is difficult to form a film on the surface of calcium carbonate particles, and the surface coating of calcium carbonate is not tight. The hydrolysis of silicate to form a sol-gel method has the disadvantages of long processing time, difficulty in filtering and drying the precipitate, and the need for a large amount of organic solvents.

Contents of the invention

The embodiment of the present invention provides a method for preparing calcium carbonate composite particles. By coating the surface with a _SiO2 film, a calcium carbonate particle with strong acid resistance and wide application is obtained.

The purpose of the present invention is achieved through the following technical solutions:

The embodiment of the present invention provides a kind of preparation method of calcium carbonate composite particle, this method comprises:

Add water glass to the calcium carbonate slurry with a concentration of 5% to 20% for mixing, heat the mixed slurry to 80-90°C, and react under the stirring state of 1000 rpm to 1500 rpm, and the reaction time 0.5 to 1 hour, and add a pH regulator to adjust the pH of the slurry to 7 to 11. After the reaction, it is aged at a temperature of 80 to 90 ° C. The aging time is 2 to 5 hours. After aging, it is aged at a temperature of 120 Dry at ~140°C, and then pulverize after drying to obtain calcium carbonate composite particles.

The method also includes: adding a dispersing aid to the calcium carbonate slurry.

The dispersing aid is any one of low molecular weight glycols, monohydric alcohols, polyoxyethylene ether surfactants, and aluminum salts.

The added amount of the dispersing aid is 0.1-3% of the mass of _CaCO3 in the calcium carbonate slurry.

The calcium carbonate slurry and the water glass are added to the reaction vessel at the same time, and then a pH regulator is added to control the pH of the mixed slurry.

The added pH regulator is any one of strong acid, acid gas or ester.

The concentration of the calcium carbonate slurry is 5%-20%.

The mass ratio of _SiO2 in the added water glass solution to _CaCO3 in the calcium carbonate slurry is 5% to 25%.

The drying time is 30-120 minutes.

As can be seen from the technical solutions provided by the above-mentioned embodiments of the present invention, the embodiments of the present invention obtain Calcium carbonate composite particles coated with intact _SiO2 film. Improve the effect of calcium carbonate and coupling agent, reduce the pH value of the calcium carbonate surface, improve the acid resistance of the obtained calcium carbonate particles, greatly broaden the application field of calcium carbonate or enhance its application effect, and simplify the synthesis of calcium carbonate Process of composite particles. The method uses a pH regulator to better control the change of the pH value of the solution, effectively control the SiO ₂ film forming rate, and make the SiO ₂ film form uniformly on the calcium carbonate surface. The hydrolysis of water glass is used to form a tightly bonded hydrated silicon dioxide layer on the surface of calcium carbonate, which has the advantages of simple operation conditions, compact structure of prepared calcium carbonate composite particles, and strong acid resistance.

Description of drawings

Fig. 1 is the process flow chart of the preparation method of the embodiment of the present invention;

Fig. 2 is a 50,000 times magnified TEM photo of calcium carbonate composite particles with a SiO ₂ /CaCO ₃ mass ratio of 20% prepared in the embodiment of the present invention coated.

Fig. 3 is a 100,000 times magnified TEM photo of coated calcium carbonate composite particles with a SiO ₂ /CaCO ₃ mass ratio of 20% prepared in the embodiment of the present invention.

Detailed ways

The embodiment of the present invention is a preparation method of calcium carbonate composite particles, which can prepare calcium carbonate particles with strong acid resistance. The specific preparation method includes: adding a dispersing aid to the calcium carbonate slurry and mixing with water glass, stirring vigorously, adding pH The regulator adjusts the pH value of the mixed slurry, controls the temperature and pH, ages for a period of time, and obtains calcium carbonate composite particles after drying. The calcium carbonate composite particles have strong acid resistance and can be widely used in multiple fields.

For ease of understanding, the implementation process of the present invention will be further described below in conjunction with specific embodiments and accompanying drawings.

Embodiment one

This embodiment provides a preparation method for synthesizing calcium carbonate composite particles, which can prepare a kind of calcium carbonate particles with strong acid resistance, as shown in Figure 1, and the specific preparation method is as follows:

In the calcium carbonate slurry with a concentration of 5% to 20%, water glass solution is added, and the mass ratio of _SiO2 in the added water glass solution to _CaCO3 in the calcium carbonate slurry is 5 to 25%. The slurry is added with a dispersing aid, and the amount of the dispersing aid added is 0.1 to 3% of the weight of the calcium carbonate slurry, and the mixed slurry is heated to 80 to 90 ° C, and in a state of vigorous stirring (generally referring to that the stirring device reaches 1000 revolutions) /min～1500 rev/min stirring state) under reaction 1～1.5 hours, after the reaction, add a pH regulator to adjust the pH value of the slurry to be 8～10, keep the temperature at 80～90°C, and age at a constant temperature for 2 After aging for ~5 hours, wash and filter, and then dry at 130° C. for 30 to 120 minutes to obtain calcium carbonate composite particles.

The above-mentioned method can obtain calcium carbonate composite particles coated with a complete _SiO2 film by controlling the appropriate calcium carbonate slurry concentration, the pH of the slurry, the aging time, the degree of dispersion of calcium carbonate in the slurry, the amount of water glass and the like. By using an acid diluent, the process of synthesizing calcium carbonate composite particles is simplified, and the control of _SiO2 film-forming reaction on the surface of calcium carbonate is simplified, and it also has the ability to rarely bring in other impurity ions except for Na ⁺ ions. advantage.

The method reduces the pH value on the surface of calcium carbonate, improves the acid resistance of the prepared calcium carbonate composite particles, improves the interaction between calcium carbonate and coupling agent, greatly broadens the application field of calcium carbonate, and also enhances the strength of calcium carbonate. The application effect of calcium.

Embodiment two

The present embodiment provides a kind of preparation method of calcium carbonate composite particle, can prepare the calcium carbonate particle with strong acid resistance, this calcium carbonate composite particle can be used in a wider range, and specific preparation process is as follows:

Be in the calcium carbonate slurry that concentration is 15%, add water glass solution, add the consumption of water glass solution with SiO in the water glass solution ₂ and the CaCO in the described calcium carbonate slurry _The mass ratio is 15%, the described The mixed slurry is heated to 85°C, and under vigorous stirring (generally refers to stirring at a state of 1000 rpm to 1500 rpm), use ethyl acetate as a pH regulator to adjust the pH of the slurry to 8.5 , aged at 85°C for 3 hours, washed and filtered, dried at 130°C after washing for 60 minutes, dried and crushed to obtain calcium carbonate composite particles.

Embodiment Three

This embodiment provides a preparation method of calcium carbonate composite particles, which can well prepare calcium carbonate particles with strong acid resistance. The specific preparation process is as follows:

In the calcium carbonate slurry that concentration is 20%, add water glass solution, add the consumption of water glass solution with SiO in the water glass solution ₂ and the CaCO in the described calcium carbonate slurry _The mass ratio is 5%, the described The mixed slurry is heated to 80°C, and under vigorous stirring, the pH value of the slurry is adjusted to 9-10 by adding _CO2 as a pH regulator, aging at a constant temperature at 80°C for 3 hours, and then washing and filtering , after washing, dry at 130°C for 50 minutes, and then pulverize after drying to obtain calcium carbonate composite particles.

Embodiment Four

This embodiment provides a kind of preparation method of calcium carbonate composite particle, can prepare the calcium carbonate particle with strong acid resistance, specific preparation process is as follows:

In the calcium carbonate slurry whose concentration is 6%, add ethylene glycol and water glass solution as dispersion aid, wherein, the add-on of ethylene glycol is to account for the 1% of _CaCO3 weight in the calcium carbonate slurry, add water glass The consumption of solution is with the SiO in the water glass solution ₂ and the _CaCO in the described calcium carbonate slurry The mass ratio is 20%, the slurry after the mixing is heated to 90 ℃, under vigorous stirring, it is used as the pH adjusting agent. Adjust the pH value of the slurry to 8.5 with ethyl acetate, age at 90°C for 3 hours, wash and filter, dry at 120°C for 100 minutes after washing and filtering, and obtain calcium carbonate composite particles after crushing.

Embodiment five

This embodiment provides a kind of preparation method of calcium carbonate composite particle, can prepare the calcium carbonate particle with strong acid resistance, specific preparation process is as follows:

Be that in the calcium carbonate slurry of 16% in concentration, add Tween80 and water glass solution as dispersing aid, wherein, the add-on of Tween 80 is to account for CaCO in the calcium carbonate slurry ₃ % by weight, add the water glass solution Consumption is 25% with the SiO in the water glass solution ₂ and the _CaCO in the calcium carbonate slurry The mass ratio is 25%, the slurry after heating described mixing is to 90 ℃, regulates with dilute sulfuric acid as pH regulator under vigorous stirring The slurry has a pH value of 8.5, aged at 90°C for 3 hours, washed and filtered, dried at 130°C for 80 minutes, and crushed to obtain calcium carbonate composite particles.

Embodiment six

This embodiment provides a kind of preparation method of calcium carbonate composite particle, can prepare the calcium carbonate particle with strong acid resistance, specific preparation process is as follows:

In the calcium carbonate slurry whose concentration is 10%, add dispersing aid _AlCl3 and water glass solution, the slurry is heated to 80 ℃, wherein, the addition of _AlCl3 is to account for ₂ % of the weight of CaCO3 in the calcium carbonate slurry , the consumption of adding water glass solution is 10% with SiO in the water glass solution ₂ and the CaCO in the described calcium carbonate slurry The mass ratio is ₁₀ %, and the pH value of the slurry is adjusted with ethyl acetate as a pH regulator under vigorous stirring. 8.5. Aging at a constant temperature of 80°C for 3 hours, washing and filtering, drying at 140°C for 50 minutes after washing and filtering, and crushing after drying to obtain calcium carbonate composite particles.

Embodiment seven

The present embodiment provides a kind of preparation method of calcium carbonate composite particle, can prepare a kind of calcium carbonate particle with strong acid resistance by this method, concrete preparation process is as follows:

In the calcium carbonate slurry with a concentration of 20%, add dispersing aid ethylene glycol and water glass solution, heat the slurry to 85°C, wherein the addition of ethylene glycol is _0.3 % of the weight of CaCO in the calcium carbonate slurry , the consumption of adding water glass solution is 5～25% with the SiO in the water glass solution ₂ and the _CaCO in the described calcium carbonate slurry The mass ratio is 5～25%, adjust the described slurry with the ethyl acetate as pH adjuster under vigorous stirring The pH value is 8.5, aged at 85°C for 3 hours at a constant temperature, washed and filtered, dried at 130°C for 120 minutes, and crushed after drying to obtain calcium carbonate composite particles.

Below with the calcium carbonate composite particle that prepares in above-mentioned embodiment seven as raw material, carry out experimental detection, concrete inspection is as follows:

Accurately weigh 0.200 g of the prepared calcium carbonate composite particles to make a 1% aqueous solution, add 0.36 mol/1 HCL under vigorous stirring, and record the volume of hydrochloric acid consumed to keep the pH of the solution at 5.5 within 15 minutes at a temperature of 25 °C. The smaller the consumption of hydrochloric acid, the stronger the anti-acid ability of calcium carbonate composite particles.

SiO ₂ % 0 5 10 15 20 25 Consumption of hydrochloric acid volume (ml) 6.50 5.40 4.42 3.55 2.45 3.60

The above experimental results show that the volume of hydrochloric acid consumed when maintaining the pH of the solution at 5.5 within 15 minutes with the calcium carbonate composite particles prepared in the embodiment of the present invention is very small, indicating that the calcium carbonate composite particles have strong acid resistance.

Those skilled in the art can know by above-mentioned experiment, and also can foresee that above-mentioned experiment only takes the calcium carbonate composite particle prepared in embodiment seven as example to carry out experimental explanation, and utilize the calcium carbonate composite particle prepared by the preparation method in the embodiment of the present invention ( Such as: the calcium carbonate composite particle prepared in embodiment two, four, six and seven), all can reach same effect.

In summary, in the embodiments of the present invention, by coating the _SiO film on the surface, the effect of calcium carbonate and coupling agent is improved, the pH value on the surface of calcium carbonate is reduced, and then the acid resistance of the calcium carbonate particles obtained is improved, thereby It greatly broadens the application field of calcium carbonate and effectively enhances the application effect of calcium carbonate particles.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, nor does the order of each embodiment cause any limitation to the scope of protection of the present invention. Anyone familiar with the technical field Within the technical scope disclosed in the present invention, any changes or substitutions that can be easily conceived by a skilled person shall fall within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (9)

1, a kind of preparation method of calcium carbonate composite particle is characterized in that, the method comprises: Add water glass to the calcium carbonate slurry with a concentration of 5% to 20% for mixing, heat the mixed slurry to 80-90°C, and react under the stirring state of 1000 rpm to 1500 rpm, and the reaction time 0.5 to 1 hour, and add a pH regulator to adjust the pH of the slurry to 7 to 11. After the reaction, it is aged at a temperature of 80 to 90 ° C. The aging time is 2 to 5 hours. After aging, it is aged at a temperature of 120 Dry at ~140°C, and then pulverize after drying to obtain calcium carbonate composite particles. 2. The method according to claim 1, further comprising: adding a dispersing aid to the calcium carbonate slurry. 3. The method according to claim 2, characterized in that the dispersing aid is any one of low molecular weight glycols, monohydric alcohols, polyoxyethylene ether surfactants, and aluminum salts. 4. The method according to claim 2, characterized in that the added amount of the dispersing aid is 0.1-3% of the mass of CaCO ₃ in the calcium carbonate slurry. 5. The method according to claim 1, characterized in that the calcium carbonate slurry and water glass are added to the reaction vessel at the same time, and then a pH regulator is added to control the pH of the mixed slurry. 6. The method according to claim 1 or 3, characterized in that the added pH regulator is any one of strong acid, acid gas or ester. 7. The method according to claim 1, characterized in that the concentration of the calcium carbonate slurry is 5%-20%. 8. The method according to claim 1, characterized in that the mass ratio of SiO ₂ in the added water glass solution to CaCO ₃ in the calcium carbonate slurry is 5%-25%. 9. The method according to claim 1, characterized in that the drying time is 30-120 minutes.

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