WO2020199348A1

WO2020199348A1 - Polymer-modified nano calcium carbonate, preparation method therefor and application thereof

Info

Publication number: WO2020199348A1
Application number: PCT/CN2019/091134
Authority: WO
Inventors: 尹应武; 黄剑岚; 廖翠莺; 叶李艺; 吐松; 赵玉芬
Original assignee: 厦门大学; 宁波大学; 北京紫光英力化工技术有限公司
Priority date: 2019-03-29
Filing date: 2019-06-13
Publication date: 2020-10-08
Also published as: CN109867986B; CN109867986A

Abstract

A polymer-modified nano calcium carbonate, which is prepared by means of a glycine-nitrate combustion method or a direct carburation method. A water-soluble polymer or a polymer emulsion is added to raw materials as a templating agent and a modifier, to obtain polymer in-situ modified nano calcium carbonate. The prepared in-situ modified nano calcium carbonate is vaterite-type calcium carbonate having a single crystal grain size of less than 10 nm and calcite-type calcium carbonate having a single crystal grain size of less than 25 nm.

Description

A new series of polymer modified nanometer calcium carbonate

Technical field

The invention belongs to the field of nano material production, and specifically relates to a polymer modified nano calcium carbonate series product and a production method.

Background technique

As a new type of ultrafine solid powder material, ultrafine calcium carbonate brings quantum size effect, small size effect, surface effect and macroscopic quantum effect that ordinary calcium carbonate does not have due to its nanometer size. It is widely used in plastics, rubber, coatings, sealants, inks, papermaking and other products as fillers, additives, reinforcing agents and brighteners. It has the effects of saving masterbatch, increasing capacity, reducing cost, improving product quality, and increasing product added value. The development of new nano-calcium carbonate products and new production processes with uniform particles, easy dispersion, large addition, good performance, and low production cost has always been the focus of technology research and development in the calcium carbonate industry and composite materials.

Polypropylene (PP) is a typical representative of synthetic materials. Among the five general plastics, it has the advantages of good chemical stability, heat resistance, easy processing, and high frequency insulation, and it has a wide range of uses. In order to increase the wear resistance, hardness and cost of PP materials, cheap inorganic fillers such as calcium carbonate are usually added. Studies have shown that calcium carbonate has an obvious anisotropic nucleation effect on the crystallization of PP. Nano calcium carbonate filled with PP with a small particle size can significantly improve the mechanical properties of composite materials such as strength and toughness. The production cost of nano calcium carbonate is high and difficult to disperse and easy to agglomerate. The characteristics of the material lead to a rapid decline in the strength and toughness of the material, and the use performance is quickly close to ordinary light calcium, which makes it impossible to add a large amount. Therefore, the current addition of nanomaterials in PP generally does not exceed 10%. The primary strategy to solve the uniform dispersion of nanometer calcium carbonate is to synthesize the more uniform nanometer calcium carbonate and the smaller the particle size, the better. The particle size of the nanometer calcium carbonate produced by the current process is usually about 50 nanometers, and the uniformity is relatively poor, that is, it is produced by the glycine method. The particle size of nano calcium carbonate is also above 15 nanometers. Secondly, a calcium carbonate synthesis process or a wet modification with stearic acid added after synthesis or a dry process in which dry calcium carbonate powder is added to stearic acid and heated and mixed to coat calcium carbonate particles. By reducing the particle size and increasing the lipophilicity, the dispersibility of the product can be improved to a certain extent, but the effect is limited, especially the strength reduction is large, it is difficult to achieve the effect of low-cost production, large-scale addition, and strengthening and toughening at the same time.

Through in-depth research, we found that only a certain amount of water-soluble polymer or polymer emulsion is added to the original calcium carbonate production process, and the presence of these polymers in the system can play a role in controlling the crystallization process of calcium carbonate as a template and nano-products. The role of the sexing agent has a good effect on inhibiting crystal growth, controlling particle uniformity, improving product dispersibility, increasing dosage, and at the same time strengthening, toughening and increasing cohesive force. Different polymer modifiers are used in different dosages. In the case of in-situ calcium carbonate synthesis and modification methods, it is possible to obtain calcite-type nano-calcite calcium carbonate with a single crystal less than 25nm and vaterite-type particles with a single crystal particle size of less than 10nm. Uniform polymer modified calcium carbonate with agglomerate size smaller. Therefore, the present invention provides a modified nano-calcium carbonate product and a production process that are innovatively developed by changing ideas.

Summary of the invention

The present invention provides a new product series of modified nano calcium carbonate that is easy to produce, low cost and good performance. The preliminary application results show that modified vaterite and calcite calcium carbonate are used in composite materials represented by polypropylene , It can significantly improve or maintain the toughness and strength of the material in the case of high addition, showing a huge application development potential.

In the method of patent 200710098833.6, we once proposed a new process of utilizing glycine and calcium carbide slag to obtain amino acid calcium by reaction filtration and purification. The chemical reaction equation is as follows: Ca(OH) ₂ +NH ₂ CH ₂ COOH→(NH ₂ CH ₂ COO) ₂ Ca+H ₂ O. The calcium glycinate solution of the dissolution reaction is suction filtered to remove insoluble impurities such as carbon residue, silicon, iron, and aluminum in the calcium carbide slag, and then carbon dioxide is introduced to obtain vaterite-type calcium carbonate. In this method, glycine is both a cosolvent and an acid binding agent. It is also a crystal form regulator and modifier. However, this method can only obtain vaterite-type calcium carbonate above 15nm, and the aggregate particle size is about 2μm, and the effect of strengthening and toughening is not good, which is worse than the production of calcium carbonate by ordinary carbonization method.

We found that the reaction of the carbon dioxide sodium glycinate solution obtained by absorbing carbon dioxide with sodium glycinate and the calcium glycinate solution can greatly shorten the reaction time, reduce the crystal grain size, realize the resource utilization of flue gas and calcium carbide slag, and the existence of system polymers can Control the generation of crystal nuclei from steric hindrance, surface adsorption and insufficient local concentration, inhibit crystal growth, maintain the uniformity of crystal grains, and realize in-situ modification and simple and convenient production of polymer-nanocarbonic acid. The purpose of the new calcium complex product.

Based on the above findings, after repeated exploration and process optimization, we invented a new product series and preparation methods for in-situ modification of polymer modifiers to produce different crystal forms of nano calcium carbonate.

Specifically, the present invention provides a nano calcium carbonate prepared by using a synthetic or natural polymer modifier as a crystallization control template and an in-situ modifier. The nano calcium carbonate is calcite type nano calcium carbonate or vaterite type. Nano calcium carbonate, nano calcium carbonate is a paste or dry powder that is filtered and washed; the polymer modifier is a water-soluble polymer modifier or a polymer modifier that can form an emulsion; the polymer modifier The sex agent is a hydrophilic polymer or lipophilic polymer, including but not limited to styrene-acrylic emulsion, sodium lignin, pure acrylic emulsion, silicone pure acrylic emulsion, fluorine pure acrylic emulsion, polyvinyl alcohol, polyethylene glycol, One or more of urinary resin, phenolic resin, lignosulfonate or cellulose sulfonate.

Preferably, in the above nanometer calcium carbonate, it is characterized in that the nanometer calcium carbonate is prepared by a glycine method or a direct carbonization method, wherein the glycine method is prepared by in-situ modification with 5% styrene-acrylic emulsion or 10% sodium lignin to obtain vaterite type Calcium carbonate, the average crystal grain diameter d of the calcium carbonate can be controlled below 10nm, the oil absorption value is about 80g/100g or about 105g/100g, and the specific surface area S is above 20m ² /g; the direct carbonization method is used 1% styrene-acrylic emulsion or 5% sodium lignin modified in situ to prepare calcite calcium carbonate. The average crystal grain diameter d of calcium carbonate is below 25nm, the specific surface area S is above 30m ² /g, and the oil absorption value is 190g/ About 100g or 113g/100g; modified calcium carbonate can significantly improve the processing performance of composite materials, among which styrene-acrylic emulsion modified calcium carbonate is more suitable for toughening, and lignin modified calcium carbonate is more suitable for reinforcement. Different requirements of materials, increase the amount and reduce costs, and flexibly choose different modified calcium carbonates for strengthening or toughening.

The present invention also provides a method for preparing nano-vaterite calcium carbonate by in-situ modification using a polymer modifier, the method comprising the following steps:

Add the polymer modifier dropwise to the calcium glycinate solution, and pass in the gas containing carbon dioxide or the glycinate carbon dioxide absorption solution under stirring until the pH value drops to 7.5 as the end of the reaction. The resulting precipitate is filtered and washed to obtain a polymer surface modification. Vaterite calcium carbonate paste product with a single crystal size of 10nm or less is dried to obtain a powder product. Preferably, the polymer modifier is sodium lignin or styrene-acrylic emulsion, and the styrene-acrylic emulsion is styrene-acrylate emulsion. When the polymer modifier is sodium lignin, the addition amount of sodium lignin is theoretically generated carbonic acid 5-15% by weight of the calcium mass; or, when the polymer modifier is a styrene-acrylic emulsion, the addition amount of the styrene-acrylic emulsion is 1-5% by weight of the theoretically generated calcium carbonate mass. The filtrate can be recycled. A part of the filtrate is used to neutralize and dissolve calcium carbide residue or calcium hydroxide to prepare calcium glycinate, and a part is used to absorb carbon dioxide in the flue gas to prepare a glycinate carbon dioxide absorption liquid.

Preferably, in the method for preparing nano-vaterite calcium carbonate by in-situ modification with a polymer modifier, it is characterized in that the concentration of the calcium glycinate solution is 1 mol/L, and the molar ratio of glycine to calcium raw material is 2:1 , The calcium is calculated as calcium hydroxide; the concentration of sodium glycinate solution is about 1mol/L, and it is dissolved at room temperature.

Preferably, in the above-mentioned method for preparing nano-vaterite calcium carbonate by in-situ modification using a polymer modifier, it is characterized in that the method includes the following steps:

Step (1): Stir the glycine solution with calcium carbide slag or slaked lime to neutralize and dissolve, and filter with suction to obtain a calcium glycinate solution;

Step (2): reacting glycine with alkali to obtain a glycine salt solution, and using the glycine salt solution to absorb carbon dioxide in the flue gas or directly absorb carbon dioxide until the pH is about 7.5 to obtain a glycinate carbon dioxide mixture;

Step (3): Add a polymer modifier to the calcium glycinate solution in step (1), and stir evenly;

Step (4): Add the mixed solution of step (2) to the solution of step (3) or directly pass in flue gas or carbon dioxide gas to synthesize modified nano-calcium carbonate in situ under mixing and stirring, and then filter to obtain nano-vaterite calcium carbonate Paste products, dry to obtain powder products;

Preferably, in the method for preparing nano-vaterite calcium carbonate by in-situ modification with a polymer modifier, the method further includes the following step (5):

Step (5): Recycle the filtrate filtered in step (4), a part of the filtrate is used to dissolve calcium carbide slag or slaked lime to obtain a purified calcium glycinate solution, and the other part of the filtrate is used to absorb and utilize CO ₂ in the flue gas to obtain The carbon dioxide absorption solution of glycine recycles synthetic products.

The present invention also provides a method for preparing nano-calcite-type calcium carbonate by in-situ modification of polymer, and the method includes the following steps:

Add the polymer modifier dropwise to the calcium hydroxide slurry, pass in carbon dioxide or flue gas containing carbon dioxide, react and carbonize until the pH of the solution drops to 7, stop the reaction, and then suction filter and wash the obtained precipitate to obtain polymer modification Calcite type calcium carbonate paste with an average crystal grain diameter d of 20-25nm is dried to obtain powdered calcium carbonate. When the polymer modifier is styrene-acrylic emulsion, the addition amount of styrene-acrylic emulsion is theoretically generated calcium carbonate When the polymer modifier is sodium lignin, the addition amount of sodium lignin is 5%-10% by weight of the theoretically generated calcium carbonate.

Preferably, in the above-mentioned method for preparing nano-calcite calcium carbonate by in-situ modification of polymer, it is characterized in that the method includes the following steps:

Step (1): Make a calcium hydroxide slurry with a certain quality of calcium oxide or calcium hydroxide, and stir and mix;

Step (2): Drop a polymer modifier into the calcium hydroxide slurry of step (1) to obtain a polymer-containing calcium hydroxide slurry; when the polymer modifier is a styrene-acrylic emulsion, When the solid content of the emulsion is 50%, the addition amount of the styrene-acrylic emulsion is 1% by weight of the theoretically generated calcium carbonate mass;

Step (3): Pour carbon dioxide gas into the calcium hydroxide slurry containing the polymer modifier in step (2), stir for carbonization reaction, stop the reaction until the pH of the solution drops to 7, and pump the resulting precipitate Filtering and washing to obtain modified nano-calcite calcium carbonate paste, and drying to obtain powdered calcium carbonate;

Preferably, in the above method for preparing nano-calcite-type calcium carbonate by in-situ modification of polymer, the calcium hydroxide slurry prepared in step (1) has a concentration of 7%-10%, and is mixed and stirred at room temperature.

The present invention also provides the application of the above-mentioned modified nano calcium carbonate as fillers, additives or modifiers for plastics, rubber, coatings, sealants, inks, adhesives, asphalt, paper or composite materials, so as to increase the dosage, reduce the cost and / Or improve performance. Preferably, the performance is one or more of strengthening, toughening, and increasing cohesive force; or the use of polymer modifiers to effectively control the growth of crystals in the process of preparing nanometer calcium carbonate, which can be directly sold as a series of commodities Calcium carbonate paste or a series of calcium carbonate powders mixed to prepare composite masterbatch.

After further research in the present invention, it is found that the modified nano-calcium carbonate can be placed for a long time without being easily reunited, and can be sold as a commodity. The research results are as follows:

Under the process conditions of the carbonization method to directly produce calcite-type calcium carbonate, the influence of the addition of the polymer modifier on the grain size is shown in Figure 1. According to the modification process of the carbonization method, the reaction system was placed directly in the reaction system without filtering after the completion of the reaction, and the reaction system was exposed to the air. Samples were taken for different storage days, and finally placed for 47 days. The results show that the addition of polymer modifiers can indeed effectively control the growth of calcium carbonate crystals; the modification effect of 1.4% emulsion is better than that of 7% emulsion, and the modification effect of 7% lignin sodium is better than 1.4% wood Sodium modification. The addition of polymer modifier can effectively control the growth of crystals. Therefore, the calcium carbonate paste obtained by washing and filtering can be placed for a long time and directly applied to the water system product series.

The preparation of composite materials using the nano vaterite and/or calcite calcium carbonate filled plastic prepared by in-situ modification of the above polymer modifier is performed as follows:

Step (1): Accurately weigh 100 parts of plastic and add different parts of modified nano-vaterite-type calcium carbonate or modified nano-calcite-type calcium carbonate according to weight percentage, and mix them thoroughly;

Step (2): adding the mixture material obtained in step (1) into an internal mixer, pelletizing, cooling and drying after melt extrusion to obtain a finished composite material.

Preferably, in the above method for preparing a composite material, the temperature of the extruder barrel is 180-200°C, the screw speed is 30-40 rpm, and the melt mixing and stirring time is 15 minutes.

In the above-mentioned nanometer calcium carbonate and its preparation method, the "left and right" refers to the value indicated by the pointer, and the variable range is within 10% up and down, that is, "1±0.1" times the original value is about.

The beneficial effects of the present invention are:

1. The polymer modifier used in the present invention is a polymer substance that is a crystallization template control agent, as well as an in-situ modifier and a composite material component. Adding polymer modifiers to the two calcium carbonate production processes can effectively control the particle size and crystal size of calcium carbonate, and simply produce cost-effective nano-vaterite-type calcium carbonate and nano-calcite-type calcium carbonate. In the representative composite material, the dispersion can be significantly improved, and the strengthening and toughness effect is significant when the dosage is greatly increased.

2. When the mass of calcite-type calcium carbonate filled polypropylene composite prepared by in-situ modification of 1% styrene-acrylic emulsion accounts for 20%, the flexural strength of the polypropylene composite increases by 27.4%, the impact toughness increases by 30.3%, and the melt index increases by 24.9 %. When the calcite calcium carbonate-filled polypropylene composite prepared by in-situ modification of 5% sodium lignin accounts for 10% of the mass, the impact toughness of the polypropylene composite is increased by 72%, and the tensile strength remains basically unchanged. When the mass of the vaterite-type calcium carbonate filled polypropylene composite material prepared by 5% E01 styrene-acrylic emulsion modification accounts for 20%, the flexural strength of the polypropylene composite material is increased by 13%, and the impact toughness is increased by 4.1%. When the mass of the vaterite-type calcium carbonate filled polypropylene composite material prepared by in-situ modification of 10% lignin sodium accounts for 20%, the impact toughness of the composite material can still be maintained, and the reduction of the tensile strength of the composite material can be effectively alleviated.

3. The present invention uses a polymer material to control the growth of calcium carbonate crystals, uses calcium glycinate and sodium glycinate to absorb carbon dioxide, and quickly reacts to obtain high-quality ultrafine vaterite-type calcium carbonate with good dispersibility and good uniformity. It can use calcium carbide slag and Flue gas produces high-quality polymer-modified nano-calcium carbonate products. The presence of the polymer components of the system can also control the growth of calcium carbonate crystals in the carbonization process, and produce a more cost-effective polymer modified nano-calcite calcium carbonate. The results are shown in Figure 1. The vaterite-type calcium carbonate and calcite-type calcium carbonate prepared by this method were characterized by X-ray diffractometer (XRD), field emission electron scanning electron microscope (SEM), and nitrogen adsorption and desorption curve (BET). The characterization results are shown in Figure 2 ~14.

4. In the present invention, nano-calcium carbonate prepared by in-situ modification of a polymer modifier is used as a filler for, for example, PP, and PP and calcium carbonate are mixed into a twin-screw extruder to melt, extrude, and granulate, with excellent performance. This method makes full use of existing production lines and "three wastes" resources for low-cost production, and can produce a new generation of nanomaterials with a wide range of applications.

Description of the drawings

Figure 1 The influence of aging time on the grain size of calcium carbonate prepared by carbonization method under emulsion and sodium lignin modification, a is the grain size change curve of unmodified calcite calcium carbonate under different aging time, b is the grain size change curve of 7% E01 emulsion in-situ modified calcite-type calcium carbonate under different aging time, c is 1.4% E01 emulsion in-situ modified calcite-type calcium carbonate under different aging time Grain size change curve, d is the grain size change curve of 1.4% sodium lignin in-situ modified calcite-type calcium carbonate under different aging time, e is 7% sodium lignin in-situ modified calcite-type carbonate Calcium crystal grain size change curve under different aging time.

Figure 2 Scanning electron micrograph of vaterite-type calcium carbonate prepared in Example 1, with a scale of 1 μm.

Fig. 3 Scanning electron micrograph of vaterite calcium carbonate prepared in Example 2, and the scale is 2 μm.

Figure 4a line is the XRD pattern of vaterite-type calcium carbonate prepared in Example 1, line b is the XRD pattern of vaterite-type calcium carbonate prepared in Example 2, and line c is the vaterite-type carbonate prepared in Comparative Example 1. XRD pattern of calcium, the ordinate is intensity (Intensity), the unit is relative intensity, and the abscissa is position (2θ/°). The columnar straight line in the figure represents the standard peak position corresponding to vaterite-type calcium carbonate.

Fig. 5 The adsorption and desorption curve of vaterite-type calcium carbonate prepared in Example 2.

Fig. 6 is a particle size distribution diagram of agglomerates of vaterite-type calcium carbonate prepared in Example 1.

Fig. 7 is a particle size distribution diagram of agglomerates of vaterite-type calcium carbonate prepared in Example 2.

Figure 8 Scanning electron micrograph of vaterite-type calcium carbonate prepared in Comparative Example 1, with a scale of 20 μm.

Figure 9 is a particle size distribution diagram of agglomerates of vaterite-type calcium carbonate prepared in Comparative Example 1.

Fig. 10 is a scanning electron micrograph of the modified nano-calcite calcium carbonate product prepared in Example 3, and the scale is 200 nm.

Figure 11 TEM image of the modified nano-calcite calcium carbonate product prepared in Example 3, the scales are 200nm and 100nm.

Figure 12 Scanning electron micrograph of the modified calcite calcium carbonate product prepared in Example 4, with a scale of 1 μm.

Figure 13a line is the XRD pattern of the modified nano-calcite calcium carbonate product prepared in Example 3, the b line is the XRD pattern of the calcite calcium carbonate product prepared in Comparative Example 2, and the c line is the calcite calcium carbonate product prepared in Example 4. XRD diagram, the ordinate is intensity (Intensity), the unit is relative intensity, and the abscissa is position (2θ/°). The columnar straight line in the figure represents the standard peak position corresponding to calcite calcium carbonate.

Figure 14 Scanning electron micrograph of calcium carbonate prepared in Comparative Example 2, and the scale is 1 μm.

detailed description

The present invention provides a nano-calcium carbonate prepared by using a synthetic or natural polymer modifier as a crystallization control template and an in-situ modifier. The nano-calcium carbonate is calcite-type nano-calcium carbonate or vaterite-type nano-calcium carbonate , Nano calcium carbonate is dried powder or filtered and washed paste; the polymer modifier is a water-soluble polymer modifier or a polymer modifier that can form an emulsion; the polymer modified The agent is a hydrophilic polymer or lipophilic polymer, including but not limited to styrene-acrylic emulsion, sodium lignin, pure acrylic emulsion, silicone pure acrylic emulsion, fluorine pure acrylic emulsion, polyvinyl alcohol, polyethylene glycol, urine One or more of aldehyde resin, phenol resin, lignosulfonate or cellulose sulfonate.

Preferably, the aforementioned nano-calcium carbonate is prepared by a glycine method or a direct carbonization method, wherein the glycine method is modified in situ with 5% styrene-acrylic emulsion or 10% sodium lignin to prepare vaterite-type calcium carbonate, with an average crystal grain diameter d It can be controlled below 10nm, the oil absorption value is about 80g/100g or about 105g/100g, the specific surface area S is above 20m ² /g; the direct carbonization method uses 1% styrene-acrylic emulsion or 5% sodium lignin in situ Calcite-type calcium carbonate is prepared by modification, the average crystal grain diameter d of calcium carbonate is below 25nm, the specific surface area S is above 30m ² /g, and the oil absorption value is about 190g/100g or 113g/100g respectively; modified carbonic acid Calcium can significantly improve the processing performance of composite materials. Among them, styrene-acrylic emulsion modified calcium carbonate is more suitable for toughening, and lignin modified calcium carbonate is more suitable for reinforcement. According to the different requirements of composite materials, increase the dosage and reduce the cost, and flexible selection Different modified calcium carbonates are used for strengthening or toughening.

The glycine method is a method of preparing calcium carbonate by reacting calcium glycinate with a sodium glycinate solution containing carbon dioxide or a solution containing carbonate radicals, and the direct carbonization method is a method of preparing calcium carbonate by reacting a solution containing calcium (non-calcium glycinate) with carbon dioxide or a solution containing carbonate radicals. Calcium carbonate method.

More preferably, the nano calcium carbonate is calcite type nano calcium carbonate or vaterite type nano calcium carbonate.

Further preferably, the nano calcium carbonate is calcite nano calcium carbonate or vaterite nano calcium carbonate, wherein the average crystal grain diameter d of the vaterite nano calcium carbonate is 5-10 nanometers, and the average aggregate diameter D is 500-750 nm, The average crystal grain diameter d of calcite-type nano calcium carbonate is 15-25 nm, and the average aggregate diameter D is 30-70 nm.

Still further preferably, for vaterite-type nano calcium carbonate, 60≤D/d≤80nm, preferably 70≤D/d≤75nm, more preferably, 72.5≤D/d≤74.5nm.

Still further preferably, for the calcite-type nano calcium carbonate, 1≤D/d≤20nm, preferably, 1≤D/d≤10nm, and more preferably, 1≤D/d≤5nm.

In another aspect of the present invention, there is provided a method for preparing nano-vaterite calcium carbonate by in-situ modification using a synthetic or natural polymer modifier, the method comprising the following steps:

Add the polymer modifier dropwise to the calcium glycinate solution, and pass in the gas containing carbon dioxide or the carbon dioxide absorption solution of glycinate under stirring until the pH value drops to 7.5 as the end of the reaction. The resulting precipitate is filtered, washed, and dried to obtain a high The molecular surface modified vaterite calcium carbonate product whose crystal particle diameter d is less than 10nm, preferably, the polymer modifier is sodium lignin or styrene-acrylic emulsion, and the styrene-acrylic emulsion is styrene-acrylate emulsion. When the modifier is sodium lignin, the addition amount of sodium lignin is 5-15% by weight of the theoretically generated calcium carbonate mass, or, when the polymer modifier is styrene-acrylic emulsion, the addition amount of the styrene-acrylic emulsion is theoretical 1-5 wt% of calcium carbonate is produced. The filtrate can be recycled. A part of the filtrate is used to neutralize and dissolve calcium carbide slag or calcium hydroxide to prepare calcium glycinate, and a part is used to absorb carbon dioxide in flue gas to prepare glycinate carbon dioxide. Absorbing liquid.

Preferably, the aforementioned method is characterized in that the concentration of the calcium glycinate solution is 1 mol/L, the molar ratio of glycine to the calcium raw material is 2:1, wherein the calcium is calculated as calcium hydroxide; the glycinate is sodium glycinate, sodium glycinate The concentration of the solution is about 1mol/L, and it dissolves at room temperature.

More preferably, in the foregoing method, the water-soluble polymer modifier or the polymer modifier that can form an emulsion is a hydrophilic polymer or a lipophilic polymer, selected from styrene-acrylic emulsion, sodium lignin, pure One or more of acrylic emulsion, silicone pure acrylic emulsion, fluorine pure acrylic emulsion, polyvinyl alcohol, polyethylene glycol, urea resin, phenol resin, lignosulfonate or cellulose sulfonate.

More preferably, the aforementioned method is characterized in that the method includes the following steps:

Step (2): reacting glycine with alkali to obtain a glycinate salt solution, which is used to absorb carbon dioxide in the flue gas or directly absorb carbon dioxide to a pH of about 7.5 to obtain a sodium glycinate carbon dioxide mixture;

In another aspect of the present invention, there is provided a method for preparing nano-calcite-type calcium carbonate by in-situ modification using a synthetic or natural polymer modifier, the method comprising the following steps:

Add the polymer modifier dropwise to the calcium hydroxide slurry, pass in carbon dioxide or flue gas containing carbon dioxide, mix and carbonize until the pH value of the solution drops to 7, stop the reaction, and filter and wash the obtained precipitate to obtain polymer modification The calcite type calcium carbonate paste with the crystal grain diameter d of 20-25nm is dried to obtain powdered calcium carbonate. When the polymer modifier is a styrene-acrylic emulsion, the addition amount of the styrene-acrylic emulsion is the theoretical mass of calcium carbonate produced When the polymer modifier is sodium lignin, the addition amount of sodium lignin is 5%-10% (weight) of the theoretically produced calcium carbonate mass.

Preferably, the aforementioned method is characterized in that the method includes the following steps:

Step (2): Drop a polymer modifier into the calcium hydroxide slurry of step (1) to obtain a polymer-containing calcium hydroxide slurry; when the polymer modifier is a styrene-acrylic emulsion, When the solid content of the emulsion is 50%, the addition amount of the styrene-acrylic emulsion is 1% (weight) of the theoretically generated calcium carbonate mass;

Preferably, in the above-mentioned method for preparing nano-calcite-type calcium carbonate by in-situ modification using synthetic or natural polymer modifiers, the concentration of the calcium hydroxide slurry prepared in step (1) is 7%-10%, and at room temperature Mix and stir.

In another aspect of the present invention, the use of nano calcium carbonate as a filler, additive or modifier for plastics, rubber, coatings, sealants, inks, adhesives, asphalt, paper or composite materials is provided to increase the amount and reduce Cost and/or performance improvement. Preferably, the performance is one or more of strengthening, toughening, and increasing adhesion.

The invention also provides effective control of crystal growth in the process of preparing nanometer calcium carbonate by applying the polymer modifier; a series of calcium carbonate pastes or composite material masterbatches prepared by mixing series of calcium carbonate powders can be sold directly as commodities.

In another aspect of the present invention, a nano calcium carbonate is provided, which is calcite type nano calcium carbonate or vaterite type nano calcium carbonate.

Preferably, the nano calcium carbonate is calcite nano calcium carbonate or vaterite nano calcium carbonate, wherein the average crystal grain diameter d of the vaterite nano calcium carbonate is 5-10 nanometers, and the average aggregate diameter D is 500-750 nm. The average crystal grain diameter d of nanometer calcium carbonate is 15-25 nm, and the average aggregate diameter D is 30-70 nm.

More preferably, for the vaterite-type nano calcium carbonate, 60≤D/d≤80, preferably 70≤D/d≤75, and more preferably, 72.5≤D/d≤74.5.

More preferably, for the calcite type nano calcium carbonate, 1≤D/d≤20, preferably, 1≤D/d≤10, more preferably, 1≤D/d≤5.

The present invention will be further described below in conjunction with specific embodiments. The raw materials, equipment and test analysis methods used in the examples are:

Glycine: Sinopharm Chemical Reagent Co., Ltd., purity ≥99.5%;

E01 Styrene-Acrylic Emulsion, namely Styrene-Acrylic Emulsion: Beijing Ziguang Yingli Chemical Technology Co., Ltd., 50% solid content water emulsion;

Sodium lignin solid: Beijing Ziguang Yingli Chemical Technology Co., Ltd., pulping by-product;

Calcium hydroxide: Sinopharm Chemical Reagent Co., Ltd., purity ≥95%;

Carbon dioxide gas: Linde gas, purity ≥99.9%;

Polypropylene resin: Ningbo Fude Energy Co., Ltd.;

Calcium hydroxide: Sinopharm Chemical Reagent Co., Ltd., purity ≥95%;

Circulating water vacuum pump: Gongyi Yuhua Co., Ltd., SHZ-(III);

Collector type constant temperature heating magnetic stirrer: Gongyi City Yuhua Co., Ltd., DF-101S;

Electronic balance: Sartorius Scientific Instruments Co., Ltd., BS224S;

Vacuum drying oven: Gongyi Yuhua Co., Ltd., DZF-6020;

Shanghai Kechuang internal mixer: LH200;

Ningbo Haitian Injection Molding Machine: SA600/150;

Computer controlled electronic universal testing machine: AGS-X, 10N-10kN+250mm;

MTS pendulum impact testing machine: ZBC7251-B;

MTS melt flow rate testing machine: ZRZ1452;

Transmission Electron Microscope from Philips, Netherlands: TECNAI F30;

Japan's Hitachi Rigaku Ultima IV-ray powder diffractometer: test the grain size and crystal form of calcium carbonate;

The method for measuring the average particle size (agglomerate size) of the electron microscope: Measure according to 6.4 in the national standard "GB/T 19590-2011 Nano Calcium Carbonate", and the test and analysis software used is Nanomeasure1.2;

Oil absorption value: Measured in accordance with 3.21 of the national standard "GB/T19281-2003 Calcium Carbonate Analysis Method";

American Mike Instrument Company TriStarⅡ3020 automatic specific surface and pore analyzer: specific surface analysis.

Preparation examples

Example 1

Weigh 75g of glycine to dissolve in water, then add 40g of sodium hydroxide to stir the reaction, and dilute to a 1L volumetric flask to prepare a 1mol/L sodium glycinate solution. Pour the sodium glycinate solution into a three-necked round-bottomed flask, introduce carbon dioxide gas, stir to absorb the carbon dioxide gas, stop ventilation when the pH of the solution reaches 7.5, and obtain a carbon dioxide absorption solution of sodium glycinate.

Weigh 150g of glycine to dissolve in water, then add 74g of calcium hydroxide/106g of calcium hydroxide slag (the calcium hydroxide content in calcium hydroxide slag is 70%), stir at 100rpm for 40min, filter to obtain calcium glycinate solution, and then dilute to a 1L volumetric flask Prepare 1mol/L calcium glycinate solution, pour the calcium glycinate solution into a 2000mL beaker, add 9g sodium lignin, then stir and mix for 5min, slowly pour the carbon dioxide absorption solution of sodium glycinate, stir for 5min, the reaction is over, filter Drying, at a drying temperature of about 100°C, obtains a modified nano-vaterite-type calcium carbonate powder product.

After analysis, the calcium carbonate prepared in Example 1 is vaterite calcium carbonate, with an average crystal grain diameter d of 6.0nm, all crystal forms are vaterite, average aggregate diameter D of 650nm, oil absorption value 105g/100g, specific surface area S is 15.72m ² /g. . The electron micrograph of the modified nano-vaterite-type calcium carbonate is shown in FIG. 2, the XRD pattern is shown in line a in FIG. 4, and the particle size distribution of agglomerates is shown in FIG. 6.

Example 2

Weigh 150g of glycine and dissolve it in water, then add 74g of calcium hydroxide/106g of calcium hydroxide slag (the calcium hydroxide content in the calcium hydroxide slag is 70%), stir and react for 40 minutes, filter to obtain the calcium glycinate solution, and then dilute it to a 1L volumetric flask. Make a 1mol/L calcium glycinate solution. Pour the calcium glycinate solution into a 2000mL beaker, add 4g E01 styrene-acrylic emulsion (50% solid content), stir and mix for 2 minutes, slowly pour the carbon dioxide absorption solution of sodium glycinate, stir for 5 minutes, the reaction is complete, filter and dry, and the drying temperature is 100℃ Around, the E01 emulsion modified vaterite type calcium carbonate powder product was obtained.

After analysis, the calcium carbonate prepared in Example 2 is vaterite-type calcium carbonate, the average crystal grain diameter d is 8.8nm, all crystal forms are vaterite type, the average aggregate diameter D is 650nm, the oil absorption value is 80g/100g, and the specific surface area S is 25.88m ² /g. The electron micrograph of the modified nano-vaterite-type calcium carbonate is shown in FIG. 3, the XRD pattern is shown in line b in FIG. 4, the adsorption and desorption curve is shown in FIG. 5, and the particle size distribution of agglomerates is shown in FIG.

Example 3

Weigh calcium hydroxide, add water to prepare a slurry with a concentration of 7%-10%, stir and mix well, and control the temperature below 40°C. Then, under stirring, E01 styrene-acrylic emulsion (solid content 50%) was added dropwise to the calcium hydroxide slurry. The weight of the dropped E01 styrene-acrylic emulsion accounted for 1% by weight of the theoretically generated calcium carbonate. Stir for 2 minutes, and the temperature is controlled at room temperature. under. Finally, carbon dioxide gas was introduced into the calcium hydroxide slurry to which the emulsion was added dropwise, and the carbonization reaction was carried out with stirring. The reaction temperature was 30°C. The reaction was stopped until the pH value of the solution dropped to 7. The obtained precipitate is suction filtered and washed to obtain a modified nano-calcite calcium carbonate paste product, and a powder product is obtained after drying.

After analysis, the calcium carbonate prepared in Example 3 is nano-calcite calcium carbonate, with an average crystal grain diameter d of 21 nm, an average aggregate diameter D of 59 nm, a specific surface area S of 35 m ² /g, a density of 2.4 g/cm ³ and oil absorption Value 190g/100g. The scanning electron micrograph of the modified nano-calcite calcium carbonate is shown in FIG. 10, the transmission electron micrograph is shown in FIG. 11, and the XRD pattern is shown in line a of FIG.

Example 4

Weigh calcium hydroxide, add water to prepare a slurry with a concentration of 7%-10%, stir and mix at 100-200rpm, and control the temperature below 40°C. Then, sodium lignin is added to the calcium hydroxide slurry, the mass of the sodium lignin accounts for 5% by weight of the theoretically generated calcium carbonate mass, and the mixture is stirred for 2 minutes, and the temperature is controlled at room temperature. Finally, carbon dioxide gas was introduced into the calcium hydroxide slurry to which sodium lignin was added dropwise, and the carbonization reaction was carried out with stirring. The reaction temperature was 30°C. Stop the reaction until the pH of the solution drops to about 7. The obtained precipitate is suction filtered and washed to obtain a modified nano-calcite calcium carbonate paste product, and a powder product is obtained after drying.

After analysis, the calcium carbonate prepared in Example 4 is calcite calcium carbonate, with an average crystal grain diameter d of 21.9 nm, an oil absorption value of 112.7 g/100 g, and a specific surface area S of 21.91 m ² /g. The scanning electron micrograph of the modified nano-calcite calcium carbonate is shown in FIG. 12, and the XRD pattern is shown in line c of FIG. 13.

Comparative example 1

Weigh 75g of glycine to dissolve in water, then add 40g of sodium hydroxide to stir the reaction, and dilute to a 1L volumetric flask to prepare a 1mol/L sodium glycinate solution. Pour the sodium glycinate solution into a three-necked round-bottomed flask, add carbon dioxide gas, stir to absorb the carbon dioxide gas, and stop the aeration when the pH of the solution reaches 7.5.

Weigh 150g glycine to dissolve in water, then add 74g calcium hydroxide/106g calcium hydroxide residue (calcium hydroxide content in calcium hydroxide residue is 70%), stir for 40min at 100rpm, filter to obtain calcium glycinate solution, and then dilute to a 1L volumetric flask , Made into 1mol/L calcium glycinate solution. Pour the calcium glycinate solution into a 2000 mL beaker, slowly pour the carbon dioxide absorption solution of sodium glycinate under stirring, stir for 20 minutes and the reaction is over, filter and dry, and dry at 100°C to obtain unmodified vaterite-type calcium carbonate.

After analysis, the calcium carbonate prepared in Comparative Example 1 is unmodified vaterite calcium carbonate, with an average crystal grain diameter d of 15nm, an average aggregate diameter D of 5.28μm, and the proportion of vaterite calcium carbonate is 96.72%. The proportion of calcite type calcium carbonate is 3.28%. The scanning electron micrograph of the unmodified vaterite calcium carbonate is shown in FIG. 8, the particle size distribution of the agglomerates is shown in FIG. 9, and the XRD pattern is shown in line c of FIG. 4.

Comparative example 2

Weigh calcium hydroxide, add water to prepare a slurry with a concentration of 7%-10%, stir and mix at 100-200rpm, and control the temperature below 40°C. Then, carbon dioxide gas was introduced into the slurry, and the carbonization reaction was carried out with stirring. The reaction temperature was 30°C. The reaction was stopped until the pH value of the solution dropped to 7. The obtained precipitate is suction filtered, washed, and dried to obtain unmodified calcite calcium carbonate.

After analysis, the calcium carbonate prepared in Comparative Example 2 is calcite calcium carbonate, with an average crystal grain diameter d of 31nm, a specific surface area S of 7.19m ² /g, an oil absorption value of 96.6g/100g, and the agglomerates are irregularly shaped blocks. . The scanning electron microscope image of the unmodified vaterite-type calcium carbonate is shown in FIG. 14, and the XRD image is shown in line b of FIG. 13.

Application Examples

According to the formula in Table 1, different calcium carbonate products and polypropylene (PP) were extruded and pelletized on an internal mixer, and then injected into five standard specimens through an injection molding machine for a series of performance tests, and the test results were averaged.

Table 1 Composition of PP composite materials prepared with different calcium carbonate filling amounts

Addition of calcium carbonate/g

PP quality/g

Percentage of calcium carbonate in total mass

00	280280	0％0%
2828	252252	10％10%
5656	224224	20％20%
8484	196196	30％30%
112112	168168	40％40%
140140	140140	50％50%

According to the formula in Table 1, the application data results of different types of calcium carbonate are shown in Table 2 to Table 7 (Note: The test results of pure PP are different due to the different batches of polypropylene resin used in the test).

Table 2 Performance test results of PP filled with different components of unmodified vaterite calcium carbonate (prepared in Comparative Example 1)

The impact toughness and tensile strength of unmodified vaterite-type calcium carbonate in PP decreased significantly with the increase of the addition amount. When the filling volume increases, the melt index decreases significantly.

Table 3 Performance test results of PP filled with different components of nano vaterite calcium carbonate prepared by in-situ modification of 10% sodium lignin (prepared in Example 1)

Vaterite-type calcium carbonate modified with 10% sodium lignin has a significant improvement in the melt index in PP, and the tensile strength can be better maintained. Even if the loading amount reaches 30%, the tensile strength is better than that of unmodified vaterite-type carbonate. The calcium loading is high at 20%. Even if the filling amount reaches 20%, the impact toughness can be maintained without decreasing.

Table 4 Performance test results of PP filled with different components of nano vaterite calcium carbonate prepared by in-situ modification of 5% E01 styrene-acrylic emulsion (prepared in Example 2)

Vaterite-type calcium carbonate modified with 5% E01 styrene-acrylic emulsion also improves the melt index in PP significantly, and the tensile strength is slightly worse than that of lignin modified. The retention of impact toughness at 30% loading is better than that of sodium lignin modified and unmodified vaterite calcium carbonate. For composite materials with high strength requirements, vaterite calcium carbonate modified by sodium lignin can be used, and for composite materials with high impact toughness requirements, emulsion modified vaterite calcium carbonate can be used.

Table 5 Performance test results of PP filled with different components of unmodified calcite calcium carbonate (prepared in Comparative Example 2) by carbonization method

Unmodified calcite calcium carbonate by carbonization method can maintain better mechanical properties and processing properties in PP than unmodified vaterite calcium carbonate in PP. When the filling amount is 20%, the impact toughness is still maintained, which indicates that the performance of calcite-type calcium carbonate in PP is generally better than that of vaterite-type calcium carbonate.

Table 6 Performance test results of filling PP with different components of nano-calcite calcium carbonate prepared by in-situ modification of 1% E01 styrene-acrylic emulsion (prepared in Example 3)

When the calcite-type nano calcium carbonate modified by 1% emulsion is filled with 30% in PP, the mechanical properties are not greatly reduced, and the processing performance is significantly improved. When the addition amount is 20%, the impact toughness increases by 30.3%. It shows that the calcite-type calcium carbonate modified in-situ by the emulsion can be strengthened and toughened when the filling amount of the composite is 30%.

Table 7 Performance test results of PP filled with different components of nano-calcite calcium carbonate prepared by in-situ modification of 5% sodium lignin (prepared in Example 4)

The calcite-type calcium carbonate modified by 5% sodium lignin has a significant improvement in the melt index in PP, and the tensile strength can be better maintained, even if the filling amount is 40%, the tensile strength is basically unchanged. When the addition amount is 10%, the impact toughness increases by 72.1%.

In summary, whether it is vaterite-type calcium carbonate or calcite-type calcium carbonate, the application performance in PP after being modified by a polymer modifier is better than that of unmodified calcium carbonate. The filling amount can make the performance of the composite material not decrease, and greatly reduce the cost. This shows that the dispersion performance of calcium carbonate has been greatly improved after modification. Emulsion-modified calcium carbonate has a better effect on improving the impact toughness of composite materials, and sodium lignin-modified calcium carbonate has a better effect on improving the tensile strength of composite materials. The melt index of modified calcium carbonate has been significantly improved. This makes composite materials more conducive to processing. Among polypropylene resin materials, the mechanical properties of calcite calcium carbonate as a filler powder are better than that of vaterite calcium carbonate.

Even if 40% by mass of 1% emulsion modified calcite calcium carbonate is added to the styrene-acrylic emulsion, the tensile strength of the composite adhesive will not decrease much, but the cost of the composite adhesive can be significantly reduced.

The above-mentioned embodiments of the present invention are described in order to facilitate those skilled in the art to understand and apply the present invention. Those skilled in the art can obviously easily make various modifications to these embodiments, and apply the general principles described here to other embodiments without creative work. Therefore, the present invention is not limited to the embodiments of the present results. According to the disclosure of the present invention, those skilled in the art make improvements and modifications without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims

A nano calcium carbonate prepared by using a synthetic or natural polymer modifier as a crystallization control template and an in-situ modifier. The nano calcium carbonate is calcite type nano calcium carbonate or vaterite type nano calcium carbonate, and nano calcium carbonate It is a dried powder or a paste that has been filtered and washed; the polymer modifier is a water-soluble polymer modifier or a polymer modifier that can form an emulsion; the polymer modifier is hydrophilic Type polymer or lipophilic polymer, including but not limited to styrene-acrylic emulsion, sodium lignin, pure acrylic emulsion, silicone pure acrylic emulsion, fluorine pure acrylic emulsion, polyvinyl alcohol, polyethylene glycol, urea resin, phenolic aldehyde One or more of resin, lignosulfonate or cellulose sulfonate.
The nano-calcium carbonate according to claim 1, wherein the nano-calcium carbonate is prepared by glycine method or direct carbonization method, wherein the glycine method uses 5% styrene-acrylic emulsion or 10% sodium lignin to prepare vaterite type For calcium carbonate, the average grain diameter d can be controlled below 10nm, the oil absorption value is about 80g/100g or about 105g/100g, and the specific surface area S is above 20m 2 /g; the direct carbonization method uses 1% styrene-acrylic emulsion Or 5% sodium lignin modified in situ to prepare calcite calcium carbonate, the average crystal grain diameter d of calcium carbonate is below 25nm, the specific surface area S is above 30m 2 /g, and the oil absorption value is about 190g/100g or 113g/ About 100g; modified calcium carbonate can significantly improve the processing performance of composite materials. Among them, styrene-acrylic emulsion modified calcium carbonate is more suitable for toughening, and lignin modified calcium carbonate is more suitable for reinforcement. According to the different requirements of composite materials, Increase the dosage and reduce the cost, and flexibly choose different modified calcium carbonate for strengthening or toughening.
The nano-calcium carbonate according to claim 1 or 2, which is calcite-type nano-calcium carbonate or vaterite-type nano-calcium carbonate, wherein the average crystal grain diameter d of vaterite-type nano-calcium carbonate is 5-10 nm, and the average aggregate diameter D is 500-750nm, the average crystal grain diameter d of calcite nano calcium carbonate is 15-25nm, and the average aggregate diameter D is 30-70nm, preferably, for vaterite nano calcium carbonate, 60≤D/d≤80 , Preferably, 70≤D/d≤75, more preferably, 72.5≤D/d≤74.5, for calcite type nano calcium carbonate, 1≤D/d≤20, preferably, 1≤D/d≤10, More preferably, 1≤D/d≤5.
A method for preparing nano-vaterite calcium carbonate by in-situ modification using a synthetic or natural polymer modifier, the method comprising the following steps:

Add the polymer modifier dropwise to the calcium glycinate solution, and pass in the gas containing carbon dioxide or the carbon dioxide absorption solution of glycinate under stirring until the pH value drops to 7.5 as the end of the reaction. The resulting precipitate is filtered, washed, and dried to obtain a high Molecular surface modified vaterite calcium carbonate product with a single crystal size of 10nm or less. Preferably, the polymer modifier is sodium lignin or styrene-acrylic emulsion, and the styrene-acrylic emulsion is styrene-acrylate emulsion. When the agent is sodium lignin, the addition amount of sodium lignin is 5-15 wt% of the theoretically generated calcium carbonate mass, or, when the polymer modifier is a styrene-acrylic emulsion, the addition amount of the styrene-acrylic emulsion is theoretically generated carbonic acid 1-5 wt% of the calcium mass, the filtrate can be recycled, part of the filtrate is used to neutralize and dissolve calcium carbide slag or calcium hydroxide to prepare calcium glycinate, and part is used to absorb carbon dioxide in flue gas to prepare glycinate carbon dioxide absorption liquid .
The method according to claim 4, characterized in that the concentration of the calcium glycinate solution is 1 mol/L, the molar ratio of glycine to the calcium raw material is 2:1, wherein the calcium is calculated as calcium hydroxide; the glycinate is glycine The concentration of sodium and sodium glycinate solution is about 1mol/L, and it dissolves at room temperature.
The method according to claim 4, characterized in that the method comprises the following steps:

Step (1): Stir the glycine solution with calcium carbide slag or slaked lime to neutralize and dissolve, and filter with suction to obtain a calcium glycinate solution;

Step (2): reacting glycine with alkali to obtain a glycinate solution, which is used to absorb carbon dioxide in the flue gas or directly absorb carbon dioxide to a pH of about 7.5 to obtain a glycinate carbon dioxide mixture;

Step (3): Add a polymer modifier to the calcium glycinate solution in step (1), and stir evenly;

Step (4): Add the mixed solution of step (2) to the solution of step (3) or directly pass in flue gas or carbon dioxide gas to synthesize modified nano-calcium carbonate in situ under mixing and stirring, and then filter to obtain nano-vaterite calcium carbonate Paste products, dry to obtain powder products;

Preferably, in the method for preparing nano-vaterite calcium carbonate by in-situ modification with a polymer modifier, the method further includes the following step (5):

Step (5): Recycle the filtrate filtered in step (4), a part of the filtrate is used to dissolve calcium carbide slag or slaked lime to obtain a purified calcium glycinate solution, and the other part of the filtrate is used to absorb and utilize CO 2 in the flue gas to obtain The carbon dioxide absorption solution of glycine recycles synthetic products.
A method for preparing nano-calcite-type calcium carbonate by in-situ modification of polymer, the method comprising the following steps:

Add the polymer modifier dropwise to the calcium hydroxide slurry, pass in carbon dioxide or flue gas containing carbon dioxide, mix and carbonize until the pH value of the solution drops to 7, stop the reaction, and filter and wash the obtained precipitate to obtain polymer modification Calcite-type calcium carbonate paste with an average grain size of 20-25nm is dried to obtain powder calcium carbonate. When the polymer modifier is a styrene-acrylic emulsion, the addition amount of the styrene-acrylic emulsion is the theoretical mass of calcium carbonate produced When the polymer modifier is sodium lignin, the addition amount of sodium lignin is 5%-10% of the theoretically generated calcium carbonate mass.
The method according to claim 7, characterized in that the method comprises the following steps:

Step (1): Make a calcium hydroxide slurry with a certain quality of calcium oxide or calcium hydroxide, and stir and mix;

Step (2): Drop a polymer modifier into the calcium hydroxide slurry of step (1) to obtain a polymer-containing calcium hydroxide slurry; when the polymer modifier is a styrene-acrylic emulsion, When the solid content of the emulsion is 50%, the addition amount of the styrene-acrylic emulsion is 1% of the theoretical mass of calcium carbonate;

Step (3): Pour carbon dioxide gas into the calcium hydroxide slurry containing the polymer modifier in step (2), stir for carbonization reaction, stop the reaction until the pH of the solution drops to 7, and pump the resulting precipitate Filtering and washing to obtain modified nano-calcite calcium carbonate paste, and drying to obtain powdered calcium carbonate;

Preferably, in the above method for preparing nano-calcite-type calcium carbonate by in-situ modification of polymer, the calcium hydroxide slurry prepared in step (1) has a concentration of 7%-10%, and is mixed and stirred at room temperature.
The use of the nano calcium carbonate according to any one of claims 1 to 8 as a filler, additive or modifier for plastics, rubber, coatings, sealants, inks, adhesives, asphalt, paper or composite materials to achieve increased dosage , Reduce cost and/or improve performance. Preferably, the performance is one or more of strengthening, toughening, and increasing cohesive force; or the use of polymer modifiers to effectively control the crystallinity in the process of preparing nanometer calcium carbonate Grow up; it can be used as a commercial direct sale series of calcium carbonate paste or a series of composite masterbatches prepared by mixing calcium carbonate powder.