Enhanced flame-retardant nano calcium carbonate, preparation method and application thereof

Abstract

The application belongs to the technical field of nanometer material preparation, and discloses a reinforced flame-retardant nano calcium carbonate, a preparation method and application. The reinforced flame-retardant nano calcium carbonate is prepared by modifying nano calcium carbonate dispersed by deionized water twice by melamine solution and phytic acid solution in sequence. The prepared reinforced flame-retardant nano calcium carbonate is applied in the field of flame-retardant polymer materials. The prepared reinforced flame-retardant nano calcium carbonate has good dispersibility, and can improve the mechanical properties of the composite material after being compounded with the polymer material. The prepared reinforced flame-retardant nano calcium carbonate has good flame retardancy and thermal stability, and is an excellent flame-retardant and reinforcing filler. The preparation method is simple, the raw material cost is low, and the method is suitable for popularization in industry.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of nanometer material preparation, in particular to enhanced flame-retardant nanometer calcium carbonate, a preparation method and application. BACKGROUND

[0002] Nanometer calcium carbonate is an important inorganic chemical product, which is widely used in the industrial production and manufacturing of plastics, paints, inks, automobile paints, food, cosmetics and the like, and has many irreplaceable functions. In the application process of polymers, in addition to the above-mentioned advantages, the main disadvantage of nanometer calcium carbonate is poor flame-retardant performance, which seriously restricts its more extensive application. Meanwhile, nanometer calcium carbonate without surface modification is prone to agglomeration in polymers, which seriously causes the mechanical properties to decrease and the nanometer particle characteristics to be not played.

[0003] Although the traditional halogen-based flame retardant has good flame-retardant effect, the flame-retardant material will generate a large amount of toxic smoke and toxic gas when burning, which is not conducive to the safety of people's lives. Therefore, developing a low-smoke and non-toxic flame retardant has become a hot spot in the flame-retardant field. In order to broaden the application of nanometer calcium carbonate in the flame-retardant field, the surface of nanometer calcium carbonate is modified, so as to enhance its flame-retardant performance and make the surface of nanometer calcium carbonate lipophilic and hydrophobic, enhance the compatibility with organic high polymer materials, and improve and enhance the performance of the composite material. SUMMARY

[0004] In order to solve at least one of the above technical problems, a nanometer calcium carbonate with good flame-retardant performance, good dispersibility and compatibility in high polymer materials and good reinforcing effect is developed. The application provides an enhanced flame-retardant nanometer calcium carbonate, a preparation method and application.

[0005] In a first aspect, the application provides a preparation method of the enhanced flame-retardant nanometer calcium carbonate, which comprises the following steps:

[0006] S1, nanometer calcium carbonate is added to a reaction container and deionized water is added, the temperature is increased to 85-100 DEG C, and constant temperature stirring is performed for 10-30 min;

[0007] S2, a first surface modifier is added to the reaction container, the temperature is kept at 85-100 DEG C, and constant temperature stirring is performed for 25-40 min;

[0008] S3, a second surface modifier is added to the reaction container, the temperature is kept at 85-100℃, and the reaction is stirred at constant temperature for 1.5-3h to obtain a suspension; the suspension is filtered to obtain filter residue, which is washed, dried, and ground to obtain the enhanced flame-retardant nano calcium carbonate.

[0009] In some preferred embodiments, the method for preparing the enhanced flame-retardant nano calcium carbonate comprises the following steps: S1, nano calcium carbonate is added to a reaction container and deionized water is added, the temperature is raised to 90℃, and the mixture is stirred at constant temperature for 15min;

[0010] S2, a first surface modifier is added to the reaction container, the temperature is kept at 90℃, and the mixture is stirred at constant temperature for 30min;

[0011] S3, a second surface modifier is added dropwise to the reaction container within 10min, the temperature is kept at 90℃, and the reaction is stirred at constant temperature for 2h to obtain a suspension; the suspension is filtered to obtain filter residue, which is washed, dried, and ground to obtain the enhanced flame-retardant nano calcium carbonate.

[0012] In some embodiments, the first surface modifier is a 2-10wt% melamine solution, and the second surface modifier is a 10-30wt% phytic acid solution.

[0013] In some embodiments, the weight ratio of the nano calcium carbonate, deionized water, first surface modifier, and second surface modifier is 80-110:40-60:7-15:18-35.

[0014] In some preferred embodiments, the weight ratio of the nano calcium carbonate, deionized water, first surface modifier, and second surface modifier is 80-100:40-60:10:18-30.

[0015] By using the above technical solution, the enhanced flame-retardant nano calcium carbonate prepared has a better balance between dispersibility and flame-retardant performance, so that the composite material prepared has a better balance between mechanical properties and flame-retardant performance.

[0016] In some embodiments, the particle size of the nano calcium carbonate is 20-100nm.

[0017] By adopting the technical scheme, through the surface treatment of the nano calcium carbonate for three times in succession, the dispersibility and processing fluidity of the nano calcium carbonate can be improved, the compatibility of the nano calcium carbonate particles with the high polymer material can be improved, and the thermal stability and the flame retardant performance of the nano calcium carbonate can be improved. The nano calcium carbonate is modified by using the melamine solution, so that the nano calcium carbonate particles are coated with the melamine molecules. After the flame retardant material prepared by compounding the nano calcium carbonate particles with the high polymer material such as polypropylene, when the flame retardant material meets fire or is in a high temperature condition, the melamine is decomposed by heat to release inert gases such as nitrogen dioxide, carbon dioxide, nitrogen and ammonia. The inert gases are wrapped around the polypropylene material, which can not only inhibit the escape of the combustible products generated by the thermal decomposition of the high polymer material, but also cut off the contact of the high polymer material with oxygen. In addition, the nitrogen atoms released by the thermal decomposition of the melamine can capture free radicals to prevent the material from continuing to burn, so that the flame retardant effect is achieved. In addition, after the nano calcium carbonate particles are coated with the melamine molecules, it is beneficial to the further coating of the phytic acid molecules. The nano calcium carbonate is modified by using the phytic acid solution, and the phytic acid solution will crosslink with the high polymer material such as polypropylene to generate a P-O-C structure under the condition of meeting fire or being in a high temperature condition. The structure can form a carbonized protective layer to prevent the material from continuing to burn. In addition, the phytic acid molecules coated on the outermost layer of the nano calcium carbonate particles can significantly improve the compatibility with the high polymer material such as polypropylene, and promote the dispersion of the modified calcium carbonate particles in the high polymer material such as polypropylene.

[0018] In some embodiments, the nano calcium carbonate used in step S1 is modified nano calcium carbonate, and the preparation process of the modified nano calcium carbonate is as follows: nano calcium carbonate, MPTMS, butyl acrylate and an initiator are added to an organic solvent to perform polymerization reaction, and then the filter residue is taken and dried to obtain the modified nano calcium carbonate.

[0019] In some preferred embodiments, the nano calcium carbonate used in step S1 is modified nano calcium carbonate, and the preparation process of the modified nano calcium carbonate is as follows: nano calcium carbonate, MPTMS, butyl acrylate and an initiator are added to anhydrous ethanol, and polymerization is performed at 70-80°C for 2h, and then polymerization is performed under ethanol reflux for 5h; after the reaction is completed, the filter residue is taken and dried for 6h, and then ground to obtain the modified nano calcium carbonate, wherein the weight ratio of nano calcium carbonate, MPTMS, butyl acrylate and the initiator is 12-16:0.6-0.9:0.8:0.1.

[0020] By adopting the technical scheme, the polybutyl acrylate molecular chain is grafted on the surface of the nano calcium carbonate by using the method of grafting the surface of the inorganic particles, so that the compatibility of the nano calcium carbonate particles with the high polymer material such as polypropylene is improved.

[0021] In a second aspect, the application provides the enhanced flame-retardant nano calcium carbonate prepared by the above method.

[0022] In a third aspect, the application provides an enhanced flame-retardant nano calcium carbonate / polypropylene composite material prepared by the above enhanced flame-retardant nano calcium carbonate, comprising the following components in parts by weight: polypropylene 70-95 parts, enhanced flame-retardant nano calcium carbonate 5-28 parts, and antioxidant 0.5-1 part.

[0023] In some preferred embodiments, the enhanced flame-retardant nano calcium carbonate / polypropylene composite material comprises the following components in parts by weight: polypropylene 80-95 parts, enhanced flame-retardant nano calcium carbonate 10-28 parts, and antioxidant 0.5-1 part.

[0024] In a fourth aspect, the application provides a preparation method of the above enhanced flame-retardant nano calcium carbonate / polypropylene composite material, characterized in that it comprises the following steps:

[0025] S1, stirring and mixing raw materials to prepare a premix;

[0026] S2, extruding and granulating the premix prepared in step S1 to prepare granules;

[0027] S3, calendering the granules prepared in step S2 in a mold to obtain a plate, pressing the plate on a flat plate vulcanizer, and then compression molding to prepare the enhanced flame-retardant nano calcium carbonate / polypropylene composite material.

[0028] In some embodiments, in step S2, the extrusion process is carried out in a twin-screw extruder, and the specific operating parameters include: zone 1 temperature 165-175℃, zone 2 temperature 175-185℃, zone 3 temperature 185-195℃, feeding speed 18-25r / min, and main machine speed 25-36r / min.

[0029] In some embodiments, in step S3, when compression molding is carried out, the hot pressing process conditions are: temperature 180-220℃, pressure 10-15MPa, and time 10-25min; and the cold pressing process conditions are: temperature 5-35℃, pressure 10-15MPa, and time 10-25min.

[0030] In summary, the application has the following at least one beneficial technical effect:

[0031] 1. The enhanced flame-retardant nano calcium carbonate prepared by the application has good dispersibility and good compatibility with polymer materials. After the enhanced flame-retardant nano calcium carbonate is compounded with polymer materials, the interface adhesion of the reaction system of the composite material can be improved, and the mechanical properties of the composite material can be improved. Meanwhile, the enhanced flame-retardant nano calcium carbonate prepared by the application has good flame retardancy and thermal stability, and is an excellent flame-retardant reinforcing filler.

[0032] 2. The preparation method of the enhanced flame-retardant nano calcium carbonate in the application is simple, and the raw material cost is low. As a flame-retardant barrier filler, the enhanced flame-retardant nano calcium carbonate can achieve good flame-retardant effect at a low cost, and is suitable for popularization in industry. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The figure is a comparison chart of infrared spectra of the enhanced flame-retardant nano calcium carbonate prepared in Example 1.

[0034] Figure 2 The figure is a comparison chart of thermogravimetric spectra of the enhanced flame-retardant nano calcium carbonate prepared in Example 1. DETAILED DESCRIPTION

[0035] The application will be further described in detail below in combination with the drawings and examples.

[0036] The application designs a preparation method of enhanced flame-retardant nano calcium carbonate, which comprises the following steps:

[0037] S1, nano calcium carbonate is added to a reaction container and deionized water is added, and the temperature is raised to 85-100 DEG C, and constant temperature stirring is carried out for 10-30 min;

[0038] S2, a first surface modifier is added to the reaction container, and the temperature is kept at 85-100 DEG C, and constant temperature stirring is carried out for 25-40 min;

[0039] S3, a second surface modifier is added to the reaction container, and the temperature is kept at 85-100 DEG C, and constant temperature stirring is carried out for 1.5-3 h to prepare a suspension. The suspension is filtered to obtain filter residue, which is washed, dried, ground, and the enhanced flame-retardant nano calcium carbonate is prepared.

[0040] The first surface active agent is a 2-10 wt% melamine solution, and the second surface active agent is a 10-30 wt% phytic acid solution.

[0041] The weight ratio of the nano calcium carbonate, deionized water, first surface active agent and second surface active agent is 80-110:40-60:1-15:18-35.

[0042] The application designs an enhanced flame-retardant nano calcium carbonate prepared by the above preparation method of enhanced flame-retardant nano calcium carbonate.

[0043] The application designs a reinforced flame-retardant nano calcium carbonate / polypropylene composite material prepared from the above-mentioned reinforced flame-retardant nano calcium carbonate, which comprises the following components in parts by weight: polypropylene 70-95 parts, reinforced flame-retardant nano calcium carbonate 5-28 parts, and antioxidant 0.5-1 part.

[0044] The application discloses a preparation method of the reinforced flame-retardant nano calcium carbonate / polypropylene composite material.

[0045] S1, the raw materials are stirred and mixed to prepare a premix;

[0046] S2, the premix prepared in step S1 is extruded and granulated to prepare granules;

[0047] S3, the granules prepared in step S2 are calendered in a mold to obtain a plate, and the plate is pressed on a flat plate vulcanization instrument, and then compression molded to prepare the reinforced flame-retardant nano calcium carbonate / polypropylene composite material.

[0048] The technical problem solved by the reinforced flame-retardant nano calcium carbonate in the application is that the compatibility of nano calcium carbonate with polypropylene and other high molecular materials is very poor, and a high amount of calcium carbonate added usually greatly reduces the mechanical properties of polypropylene and other high molecular materials, is not easy to disperse, and has poor flame-retardant performance. The application modifies the nano calcium carbonate twice in turn, so that the surface of the nano calcium carbonate is lipophilic and hydrophobic, the compatibility with organic high molecular materials is enhanced, and on the other hand, the flame-retardant performance and thermal stability of the nano calcium carbonate are also enhanced; so that the prepared composite material has good mechanical properties and flame-retardant performance.

[0049] The raw materials used in the embodiments of the application are all commercially available, and the sources are as follows:

[0050] Nano calcium carbonate, Shanghai Maiyier Biochemical Technology Co., Ltd.;

[0051] Melamine, Hubei Guangao Biological Technology Co., Ltd.;

[0052] Phytic acid, Jinjile Chemical Co., Ltd.;

[0053] Polypropylene, Jinjile Chemical Co., Ltd.

[0054] Antioxidant T521, Changzhou Junchi Chemical Co., Ltd.;

[0055] Azobis isobutyronitrile, Wuhan Jixinyibang Biological Technology Co., Ltd.

[0056] MPTMS (gamma-mercaptopropyl trimethoxysilane), Shanghai Yuanye Biological Technology Co., Ltd.,

[0057] Butyl acrylate, Sigma-Aldrich (Shanghai) Trading Co., Ltd.

[0058] Examples 1-5

[0059] Examples 1-5 are enhanced flame-retardant nano calcium carbonate prepared after modification using different amounts of modifier, wherein the specific amounts of the first surface modifier, the second surface modifier and the third surface modifier used in Examples 1-5 are shown in Table 1.

[0060] Table 1

[0061]

[0062] The average particle size of the nano calcium carbonate used in Examples 1-5 is 50 nm.

[0063] The first surface modifier used in Examples 1-5 is a 7wt% melamine solution, and the second surface modifier used in Examples 1-5 is a 26wt% phytic acid solution.

[0064] The preparation process of Examples 1-5 is as follows:

[0065] S1, add nano calcium carbonate into a reaction vessel and add deionized water, heat to 90°C, and constant temperature stirring for 15 min;

[0066] S2, add the first surface modifier to the reaction vessel, keep the temperature at 90°C, and constant temperature stirring for 30 min;

[0067] S3, add the second surface modifier dropwise into the reaction vessel within 10 min, keep the temperature at 90°C, and constant temperature stirring for 2 h to prepare a suspension. Filter the suspension to obtain filter residue, wash, dry, grind, and prepare enhanced flame-retardant nano calcium carbonate.

[0068] Figure 1 The above is a comparison chart of the infrared spectra of the enhanced flame-retardant nano calcium carbonate prepared in Example 1, wherein “neat nano-CaCO3” is the infrared spectrum curve of the unmodified nano calcium carbonate, and “wet-nano-CaCO3” is the infrared spectrum curve of the enhanced flame-retardant nano calcium carbonate prepared in Example 1.

[0069] Figure 2 The above is a comparison chart of the thermogravimetric spectra of the enhanced flame-retardant nano calcium carbonate prepared in Example 1, wherein “neat nano-CaCO3” is the thermogravimetric spectrum curve of the unmodified nano calcium carbonate, and “wet-nano-CaCO3” is the thermogravimetric spectrum curve of the enhanced flame-retardant nano calcium carbonate prepared in Example 1.

[0070] Example 6

[0071] Example 6 is based on Example 2, except that the nano calcium carbonate used in Example 6 is modified nano calcium carbonate, and the preparation process of the modified nano calcium carbonate is as follows: nano calcium carbonate, MPTMS, butyl acrylate and initiator are added into anhydrous ethanol, and polymerization is carried out at 75°C for 2h, and then polymerization is carried out under ethanol reflux for 5h; after the reaction is completed, the filter residue is filtered, dried for 6h, ground, and the modified nano calcium carbonate is prepared; wherein the weight ratio of nano calcium carbonate, MPTMS, butyl acrylate and initiator is 12-16:0.6-0.9:0.8:0.1. Among them, the initiator uses azobisisobutyronitrile.

[0072] Comparative Examples 1-3

[0073] Comparative Example 1 is based on Example 2, except that the operation of step S1 is deleted in Comparative Example 1, that is, the preparation process of Comparative Example 1 is as follows: nano calcium carbonate is added to a reaction container, and a first surface modifier is added, the temperature is kept at 90°C, and constant temperature stirring is carried out for 30min; the second surface modifier is added dropwise into the reaction container within 10min, the temperature is kept at 90°C, and constant temperature stirring is carried out for 2h to prepare a suspension; the suspension is filtered to obtain the filter residue, which is washed, dried and ground to prepare the enhanced flame-retardant nano calcium carbonate.

[0074] Comparative Example 2 is based on Example 2, except that in Comparative Example 2, the addition of the first surface modifier in step S2 is replaced by the addition of the second surface modifier in step S3, that is, the preparation process of Comparative Example 2 is as follows: nano calcium carbonate is added to a reaction container and deionized water is added, the temperature is raised to 90°C, and constant temperature stirring is carried out for 15min; the second surface modifier is added dropwise into the reaction container within 10min, the temperature is kept at 90°C, and constant temperature stirring is carried out for 2h; the first surface modifier is added to the reaction container, the temperature is kept at 90°C, and constant temperature stirring is carried out for 30min to prepare a suspension; the suspension is filtered, the filter residue is washed, dried and ground to prepare the enhanced flame-retardant nano calcium carbonate.

[0075] Comparative Example 3 is based on Example 2, except that the operation of step S2 is deleted in Comparative Example 3, that is, the preparation process of Comparative Example 3 is as follows: nano calcium carbonate is added to a reaction container and deionized water is added, the temperature is raised to 90°C, and constant temperature stirring is carried out for 15min; the second surface modifier is added to the reaction container, the temperature is kept at 90°C, and constant temperature stirring is carried out for 2h to prepare a suspension; the suspension is filtered, the filter residue is washed, dried and ground to prepare the enhanced flame-retardant nano calcium carbonate.

[0076] Application Examples 1-6 and Comparative Examples 1-3

[0077] The application examples 1-6 are enhanced flame-retardant nano calcium carbonate / polypropylene composites prepared by different raw material ratios, which are different in the enhanced flame-retardant nano calcium carbonate. The enhanced flame-retardant nano calcium carbonate used in the application examples 1-6 corresponds to the examples 1-6 in turn, and the enhanced flame-retardant nano calcium carbonate used in the application comparative examples 1-3 corresponds to the comparative examples 1-3 in turn. See Table 2 for details.

[0078] The amount of the barrier flame-retardant nano calcium carbonate used in the application examples 1-6 and the application comparative examples 1-3 is 20 parts by weight, the amount of the polypropylene is 85 parts by weight, and the amount of the antioxidant is 0.7 parts by weight.

[0079] Table 2

[0080]

[0081] The antioxidant used in the application examples 1-6 is antioxidant T521.

[0082] The preparation process of the application examples 1-6 is as follows:

[0083] S1, the raw materials are stirred and mixed to prepare a premix;

[0084] S2, the premix prepared in step S1 is extruded and granulated to prepare granules; the extrusion process is carried out in a twin-screw extruder, and the specific operation parameters are as follows: the temperature of the first zone is 170 ℃, the temperature of the second zone is 180 ℃, and the temperature of the third zone is 190 ℃; the feeding speed of the twin-screw extruder is 20 r / min, and the main machine speed is 30 r / min;

[0085] S3, the granules prepared in step S2 are calendered and formed into a plate in a mold, and the plate is pressed on a flat plate vulcanizer, and then compression molded to prepare the enhanced flame-retardant nano calcium carbonate / polypropylene composite material; when compression molding, the hot pressing temperature is 190 ℃, the hot pressing pressure is 15 Mpa, the hot pressing time is 15 min; the cold pressing temperature is 15 ℃, the cold pressing pressure is 15 Mpa, and the cold pressing time is 20 min.

[0086] Application examples 7-9 and application comparative example 4

[0087] The enhanced flame-retardant nano calcium carbonate used in the application examples 7-9 is prepared in example 2. The application examples 7-9 are enhanced flame-retardant nano calcium carbonate / polypropylene composites prepared by different raw material ratios, which are different in the amount of polypropylene and enhanced flame-retardant nano calcium carbonate. See Table 3 for details.

[0088] Table 3

[0089]

[0090] The preparation processes of application examples 7-9 and application comparative example 4 are the same as those of application examples 1-5.

[0091] Performance detection

[0092] 1. The composite materials prepared in application examples 1-9 and application comparative examples 1-4 were processed into samples with a width of 6.8 mm and a thickness of 3 mm, and the oxygen index (%) of the composite materials prepared in application examples 1-9 and application comparative examples 1-4 was determined by using an oxygen index tester for combustion performance test according to the standard ISO 4589.

[0093] 2. The tensile strength and elongation at break of application examples 1-9 and application comparative examples 1-4 were determined according to the standard GB / T1040-2006 "Determination of tensile properties of plastics".

[0094] The specific detection results are shown in Table 4.

[0095] Table 4

[0096]

[0097]

[0098] Through analysis of the data in Table 4, it can be seen that, by comparing application examples 1-9 with application comparative examples 1-4, only when the nano calcium carbonate is sequentially modified by deionized water, melamine solution and phytic acid solution, the enhanced flame-retardant nano calcium carbonate / polypropylene composite material prepared from the enhanced flame-retardant nano calcium carbonate and polypropylene has better performance in flame-retardant performance and mechanical properties. When the nano calcium carbonate is surface grafted and modified, the enhanced flame-retardant nano calcium carbonate / polypropylene composite material has better flame-retardant performance and mechanical properties.

[0099] The above are preferred embodiments of the present application, and do not limit the protection scope of the present application, so: any equivalent changes made on the basis of the structure, shape, principle of the present application should be covered within the protection scope of the present application.

Claims

1. A method for preparing enhanced flame-retardant nano-calcium carbonate, characterized in that, Includes the following steps: S1. Add nano-calcium carbonate to the reaction vessel and add deionized water. Heat to 85-100℃ and stir at a constant temperature for 10-30 minutes. S2. Add the first surfactant to the reaction vessel, maintain the temperature at 85-100℃, and stir at a constant temperature for 25-40 minutes; S3. Add the second surfactant to the reaction vessel, maintain the temperature at 85-100℃, and stir the reaction at a constant temperature for 1.5-3 hours to obtain a suspension; filter the suspension to obtain the filter residue, wash, dry, and grind it to obtain reinforced flame-retardant nano calcium carbonate. The first surfactant is a 2-10 wt% melamine solution, and the second surfactant is a 10-30 wt% phytic acid solution.

2. The preparation method of the enhanced flame-retardant nano-calcium carbonate according to claim 1, characterized in that, The weight ratio of the nano-calcium carbonate, deionized water, first surfactant, and second surfactant is 80-110:40-60:7-15:18-35.

3. The preparation method of the enhanced flame-retardant nano-calcium carbonate according to claim 1, characterized in that, The particle size of the nano-calcium carbonate is 20-100 nm.

4. The preparation method of the enhanced flame-retardant nano-calcium carbonate according to claim 1, characterized in that, The nano-calcium carbonate in step S1 is modified nano-calcium carbonate. The preparation process of the modified nano-calcium carbonate is as follows: nano-calcium carbonate, MPTMS, butyl acrylate and initiator are added to an organic solvent to carry out a polymerization reaction, filtered, the filter residue is collected and dried to obtain the modified nano-calcium carbonate.

5. The enhanced flame-retardant nano-calcium carbonate prepared by the method of any one of claims 1-4.

6. A reinforced flame-retardant nano-calcium carbonate / polypropylene composite material prepared from the reinforced flame-retardant nano-calcium carbonate as described in claim 5, characterized in that, It includes the following components in parts by weight: 70-95 parts polypropylene, 5-28 parts reinforced flame-retardant nano calcium carbonate, and 0.5-1 parts antioxidant.

7. A method for preparing the reinforced flame-retardant nano-calcium carbonate / polypropylene composite material according to claim 6, characterized in that, Includes the following steps: S1. Mix the raw materials to obtain a premix; S2. The premix obtained in step S1 is extruded and granulated to obtain granules. S3. The granules obtained in step S2 are calendered in a mold to obtain a sheet, the sheet is pressed into a sheet on a flat vulcanizing apparatus, and then pressed into shape to obtain the reinforced flame-retardant nano calcium carbonate / polypropylene composite material.

8. The method for preparing the reinforced flame-retardant nano-calcium carbonate / polypropylene composite material according to claim 7, characterized in that, In step S2, the extrusion process is carried out in a twin-screw extruder, and the specific operating parameters include: zone 1 temperature of 165-175℃, zone 2 temperature of 175-185℃, zone 3 temperature of 185-195℃, feeding speed of 18-25 r / min, and main extruder speed of 25-36 r / min.

9. The method for preparing the reinforced flame-retardant nano-calcium carbonate / polypropylene composite material according to claim 7, characterized in that, In step S3, when performing pressing molding, the hot pressing process conditions are: temperature 180-220℃, pressure 10-15MPa, time 10-25min; the cold pressing process conditions are: temperature 5-35℃, pressure 10-15MPa, time 10-25min.

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