Hollow sphere plastic pigment and preparation method thereof

Abstract

The invention provides a hollow sphere plastic pigment and a preparation method thereof, and belongs to the technical field of plastic pigments. After the surface of nano silicon dioxide is modified by a silane coupling agent with double bonds, the nano silicon dioxide is polymerized with an acrylic monomer and a styrene monomer, swelling and filtering are performed in a supercritical CO2 fluid to remove a template, after surface activation, carboxymethyl chitosan is coupled and cross-linked, then 2, 2, 2-trifluoroethylamine and aspartic acid are coupled, and the nano silicon dioxide is prepared. And reacting with a silane coupling agent modified titanium dioxide nanosphere with an epoxy group to prepare the hollow sphere plastic pigment. The prepared hollow sphere plastic pigment has good covering power, paper surface glossiness, printing glossiness and ink absorbability are obviously improved, the mechanical property of paper can be enhanced, preparation is safer and more environmentally friendly, and the hollow sphere plastic pigment has wide application prospects.

Description

Technical Field

[0001] This invention relates to the field of plastic pigment technology, specifically to a hollow sphere plastic pigment and its preparation method. Background Technology

[0002] Hollow spherical plastic pigments have a spherical hollow structure with a high glass transition temperature polymer shell. The hollow spherical structure gives them low density, good heat insulation and high hiding power, so they are widely used in thermal printing paper, lightweight coated paper and other fields.

[0003] The effective component of hollow sphere plastic pigments is a styrene-acrylic polymer with a diameter of approximately 1 μm and a porosity greater than 50%. The current mainstream preparation technique is the alkali swelling method, which involves first preparing seeds with a particle size of tens of nanometers, then using a seed emulsion polymerization method to dropwise add polyacrylic acid monomers to the seed system to polymerize them into nuclei. Next, styrene-based monomers are added dropwise to coat the nuclei, forming a core-shell structure. Finally, the carboxylic acid groups absorb water and swell under alkaline conditions, expanding the shell to obtain the hollow structure. To ensure that the hydrophobic shell effectively coats the hydrophilic core, a transition layer is usually introduced between the core and shell, making the preparation of hollow spheres quite complex. Meanwhile, seed growth is achieved through the adsorption of added monomers or monomer chains. Therefore, a high specific surface area is one of the main driving forces promoting seed growth and inhibiting the re-nucleation of newly added monomers. This means that the larger the seed size, the more difficult it is for it to continue growing. If newly added monomers cannot be adsorbed by the seeds in time, they are prone to re-nucleation after polymerization by adsorbing emulsifiers. The newly generated nuclei are small in size and are more likely to adsorb monomers or chains and grow, thus inhibiting or even stopping seed growth. Although slowing down the monomer dripping rate and reducing the amount of emulsifier can inhibit the re-nucleation of added monomers to some extent, this will undoubtedly greatly prolong the production cycle of hollow spheres, harm the stability of the emulsion system, and make it difficult to ensure the diameter of the styrene-acrylic polymer in the hollow spheres. Furthermore, the hydrofluoric acid etching wastewater usually has a high fluoride content, causing environmental problems.

[0004] Therefore, new methods for preparing hollow sphere plastic pigments are needed to solve these problems. Summary of the Invention

[0005] The purpose of this invention is to propose a hollow sphere plastic pigment and its preparation method, which has good hiding power, significantly improves paper gloss, printing gloss and ink absorption, enhances the mechanical properties of paper, and is safer and more environmentally friendly to prepare, with broad application prospects.

[0006] The technical solution of this invention is implemented as follows:

[0007] This invention provides a method for preparing hollow sphere plastic pigment. The surface of nano-silica is modified with a silane coupling agent containing double bonds, then polymerized with acrylic monomers and styrene monomers, swollen in supercritical CO2 fluid, filtered to remove the template, surface activated, coupled with carboxymethyl chitosan and crosslinked, then coupled with 2,2,2-trifluoroethylamine and aspartic acid, and reacted with titanium dioxide nanospheres modified with an epoxy-containing silane coupling agent to obtain hollow sphere plastic pigment.

[0008] As a further improvement to the present invention, the following steps are included:

[0009] S1. Add nano-silica to ethanol, add a silane coupling agent with double bonds, heat and stir to react, centrifuge, wash, and dry to obtain modified nano-silica;

[0010] S2. Add the modified nano-silica and monomer to an aqueous ether solution, stir and mix evenly, add a pore-forming agent, add an initiator dropwise under inert gas protection, heat and stir to react, centrifuge, wash, and dry to obtain porous polystyrene / polyacrylate modified nanospheres;

[0011] S3. Porous polystyrene / polyacrylate modified nanospheres were added to supercritical CO2 fluid to swell, filtered, washed with solids, and dried to obtain porous polystyrene / polyacrylate hollow spheres.

[0012] S4. Add porous polystyrene / polyacrylate hollow spheres to water, add N-hydroxysuccinimide and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, stir to activate, add carboxymethyl chitosan, stir to react, add glutaraldehyde curing agent, centrifuge, wash, dry, and obtain chitosan@porous polystyrene / polyacrylate hollow spheres;

[0013] S5. Add titanium dioxide nanospheres to ethanol, add silane coupling agent with epoxy group, heat and stir to react, centrifuge, wash, and dry to obtain modified titanium dioxide nanospheres;

[0014] S6. Chitosan@porous polystyrene / polyacrylate hollow spheres were added to water, along with N-hydroxysuccinimide and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide. The mixture was stirred and activated, and then 2,2,2-trifluoroethylamine and aspartic acid were added. The mixture was stirred and reacted, centrifuged, washed, and dried to obtain modified hollow nanospheres.

[0015] S7. Add modified hollow nanospheres to water, add modified titanium dioxide nanospheres, stir to react, centrifuge, wash, and dry to obtain hollow sphere plastic pigment.

[0016] As a further improvement of the present invention, the average particle size of the nano-silica in step S1 is 100-200 nm, the mass ratio of the nano-silica to the silane coupling agent with double bonds is 10:2-3, the temperature of the heating and stirring reaction is 45-55°C, and the time is 2-4 h, wherein the silane coupling agent with double bonds is selected from at least one of KH570, A151, and A171.

[0017] As a further improvement of the present invention, the monomers in step S2 include styrene, methacrylic acid, and butyl methacrylate in a mass ratio of 8-10:4-6:1-2; the mass ratio of the modified nano-silica, monomers, porogen, and initiator is 10:4-6:0.5-1:0.01-0.015; the heating and stirring reaction is carried out at a temperature of 65-75°C for 4-6 hours; the porogen is selected from at least one of hexadecyltrimethylammonium chloride, hexadecylbenzyldimethylammonium chloride, hexadecyltrimethylsodium chloride, hexadecyltrimethylammonium bromide, hexadecyltrimethylsodium bromide, and hexadecylbenzyldimethylsodium chloride; and the initiator is selected from at least one of sodium persulfate, potassium persulfate, and ammonium persulfate.

[0018] As a further improvement of the present invention, the swelling time in step S3 is 1-2 days.

[0019] As a further improvement of the present invention, the mass ratio of the porous polystyrene / polyacrylate hollow spheres, N-hydroxysuccinimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, carboxymethyl chitosan, and glutaraldehyde in step S4 is 12-15:3-4:3-4:6-10:0.1-0.15, and the stirring reaction time is 6-10 h.

[0020] As a further improvement of the present invention, the mass ratio of the titanium dioxide nanospheres and the epoxy-containing silane coupling agent in step S5 is 5-7:1-2, the temperature of the heating and stirring reaction is 45-55℃, the time is 1-3h, and the epoxy-containing silane coupling agent is KH560.

[0021] As a further improvement of the present invention, in step S6, the mass ratio of chitosan@porous polystyrene / polyacrylate hollow spheres, N-hydroxysuccinimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, 2,2,2-trifluoroethylamine and aspartic acid is 10-15:3-5:3-5:1-3:2-4, and the stirring reaction time is 5-7 hours.

[0022] As a further improvement of the present invention, the mass ratio of the modified hollow nanospheres and the modified titanium dioxide nanospheres in step S7 is 10:1-3, and the stirring reaction time is 4-6 hours.

[0023] The present invention further protects a hollow sphere plastic pigment prepared by the above-described preparation method.

[0024] The present invention has the following beneficial effects:

[0025] This invention modifies the surface of nano-silica with a silane coupling agent containing double bonds, allowing the double bonds to participate in the polymerization reaction of acrylic acid and styrene monomers. This results in the formation of a porous polystyrene / polyacrylate shell on the surface of the silica nanospheres. A supercritical CO2 fluid swelling method replaces hydrofluoric acid (HF) etching. The nano-silica template is removed through a supercritical fluid swelling-contraction process. Filtering with pores larger than the nano-silica allows for the removal of the nano-silica template while simultaneously removing the supercritical CO2 fluid. Excess supercritical CO2 fluid can be removed by drying and evaporation, achieving non-destructive template removal, avoiding HF pollution, and making it safer and more environmentally friendly.

[0026] This invention activates the carboxyl groups on the surface of porous polystyrene / polyacrylate hollow spheres and couples them with carboxymethyl chitosan to form a chitosan layer on the surface. Glutaraldehyde is then used for curing and crosslinking, resulting in a double-layered hollow sphere plastic pigment. The crosslinking effect of chitosan enhances structural stability, while the flexibility of the second shell improves the pigment's deformation adaptability in the coating, enhancing paper strength and opacity.

[0027] This invention produces chitosan@porous polystyrene / polyacrylate hollow spheres with 2,2,2-trifluoroethylamine and aspartic acid coupled to the surface. The microsphere surface is treated with 2,2,2-trifluoroethylamine as a modifier to enhance hydrophobicity and chemical stability, followed by emulsion polymerization to coat the microspheres with a polymer shell. Fluorine modification addresses the issues of high surface energy and easy aggregation in traditional microspheres due to the low surface energy of fluorine atoms. Aspartic acid modification, with the hydrophilic groups of the amino acid, enables rapid and complete water droplet spreading, improving the ink absorption of paper coatings.

[0028] The modified hollow nanospheres prepared by this invention also have titanium dioxide nanospheres coupled to the surface through epoxy and amino reactions, which replace part of the calcium carbonate, improve the hiding power, and significantly improve the paper gloss, printing gloss and ink absorption, as well as the paper strength.

[0029] The hollow sphere plastic pigment prepared by this invention has good hiding power, and significantly improves paper gloss, printing gloss and ink absorption, which can enhance the mechanical properties of paper. Moreover, the preparation is safer and more environmentally friendly, and has broad application prospects. Detailed Implementation

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] The particle size range of nano-silica is 100-200 nm. The particle size range of titanium dioxide nanospheres is 30-50 nm. The operating temperature of the supercritical CO2 fluid is 31℃, and the pressure is 7.38 MPa.

[0032] Example 1

[0033] This embodiment provides a method for preparing hollow sphere plastic pigment, including the following steps:

[0034] S1. Add 10g of nano-silica to 200mL of ethanol, add 2g of silane coupling agent A151, heat to 45℃, stir and react for 2h, centrifuge, wash, dry, and obtain modified nano-silica.

[0035] S2. Add 10g of modified nano-silica and 4g of monomer to 200mL of diethyl ether aqueous solution (diethyl ether content is 50wt%), stir and mix for 10min, add 0.5g of cetylbenzyldimethylammonium chloride, add 0.01g of sodium persulfate under nitrogen protection, heat to 65℃, stir and react for 4h, centrifuge, wash, dry, and obtain porous polystyrene / polyacrylate modified nanospheres;

[0036] The monomers include styrene, methacrylic acid, and butyl methacrylate in a mass ratio of 8:4:1.

[0037] S3. Add 10g of porous polystyrene / polyacrylate modified nanospheres to 100mL of supercritical CO2 fluid to swell for 1d, filter, filter pore size greater than 500nm, wash the solid, dry, and obtain porous polystyrene / polyacrylate hollow spheres.

[0038] S4. Add 12g of porous polystyrene / polyacrylate hollow spheres to 300mL of water, add 3g of N-hydroxysuccinimide and 3g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, stir and activate for 30min, add 6g of carboxymethyl chitosan, stir and react for 6h, add 0.1g of glutaraldehyde, stir and react for 10min, centrifuge, wash, dry, and obtain chitosan@porous polystyrene / polyacrylate hollow spheres;

[0039] S5. Add 5g of titanium dioxide nanospheres to 150mL of ethanol, add 1g of silane coupling agent KH560, heat to 45℃, stir and react for 1h, centrifuge, wash, dry, and obtain modified titanium dioxide nanospheres.

[0040] S6. Add 10g of chitosan@porous polystyrene / polyacrylate hollow spheres to 200mL of water, add 3g of N-hydroxysuccinimide and 3g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, stir and activate for 30min, add 1g of 2,2,2-trifluoroethylamine and 2g of aspartic acid, stir and react for 5h, centrifuge, wash, dry, and obtain modified hollow nanospheres;

[0041] S7. Add 10g of modified hollow nanospheres to 200mL of water, add 1g of modified titanium dioxide nanospheres, stir and react for 4h, centrifuge, wash, and dry to obtain hollow sphere plastic pigment.

[0042] Example 2

[0043] This embodiment provides a method for preparing hollow sphere plastic pigment, including the following steps:

[0044] S1. Add 10g of nano-silica to 200mL of ethanol, add 3g of silane coupling agent A171, heat to 55℃, stir and react for 4h, centrifuge, wash, dry, and obtain modified nano-silica.

[0045] S2. Add 10g of modified nano-silica and 6g of monomer to 200mL of diethyl ether aqueous solution (diethyl ether content is 50wt%), stir and mix for 10min, add 1g of hexadecyltrimethylammonium bromide, add 0.015g of potassium persulfate under nitrogen protection, heat to 75℃, stir and react for 6h, centrifuge, wash, and dry to obtain porous polystyrene / polyacrylate modified nanospheres;

[0046] The monomers include styrene, methacrylic acid, and butyl methacrylate in a mass ratio of 10:6:2.

[0047] S3. Add 10g of porous polystyrene / polyacrylate modified nanospheres to 100mL of supercritical CO2 fluid to swell for 2d, filter, filter pore size greater than 500nm, wash the solid, dry, and obtain porous polystyrene / polyacrylate hollow spheres.

[0048] S4. Add 15g of porous polystyrene / polyacrylate hollow spheres to 300mL of water, add 4g of N-hydroxysuccinimide and 4g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, stir and activate for 30min, add 10g of carboxymethyl chitosan, stir and react for 10h, add 0.15g of glutaraldehyde, stir and react for 10min, centrifuge, wash, dry, and obtain chitosan@porous polystyrene / polyacrylate hollow spheres;

[0049] S5. Add 7g of titanium dioxide nanospheres to 150mL of ethanol, add 2g of silane coupling agent KH560, heat to 55℃, stir and react for 3h, centrifuge, wash, and dry to obtain modified titanium dioxide nanospheres.

[0050] S6. Add 15g of chitosan@porous polystyrene / polyacrylate hollow spheres to 200mL of water, add 5g of N-hydroxysuccinimide and 5g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, stir and activate for 30min, add 3g of 2,2,2-trifluoroethylamine and 4g of aspartic acid, stir and react for 7h, centrifuge, wash, dry, and obtain modified hollow nanospheres;

[0051] S7. Add 10g of modified hollow nanospheres to 200mL of water, add 3g of modified titanium dioxide nanospheres, stir and react for 6h, centrifuge, wash, and dry to obtain hollow sphere plastic pigment.

[0052] Example 3

[0053] This embodiment provides a method for preparing hollow sphere plastic pigment, including the following steps:

[0054] S1. Add 10g of nano-silica to 200mL of ethanol, add 2.5g of silane coupling agent KH570, heat to 50℃, stir and react for 3h, centrifuge, wash, and dry to obtain modified nano-silica;

[0055] S2. Add 10g of modified nano-silica and 5g of monomer to 200mL of diethyl ether aqueous solution (diethyl ether content is 50wt%), stir and mix for 10min, add 0.7g of hexadecyltrimethylammonium chloride, add 0.012g of ammonium persulfate under nitrogen protection, heat to 70℃, stir and react for 5h, centrifuge, wash, dry, and obtain porous polystyrene / polyacrylate modified nanospheres;

[0056] The monomers include styrene, methacrylic acid, and butyl methacrylate in a mass ratio of 9:5:1.5.

[0057] S3. Add 10g of porous polystyrene / polyacrylate modified nanospheres to 100mL of supercritical CO2 fluid to swell for 1.5d, filter, filter pore size greater than 500nm, wash the solid, dry, and obtain porous polystyrene / polyacrylate hollow spheres.

[0058] S4. Add 13g of porous polystyrene / polyacrylate hollow spheres to 300mL of water, add 3.5g of N-hydroxysuccinimide and 3.2g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, stir and activate for 30min, add 8g of carboxymethyl chitosan, stir and react for 8h, add 0.12g of glutaraldehyde, stir and react for 10min, centrifuge, wash, dry, and obtain chitosan@porous polystyrene / polyacrylate hollow spheres;

[0059] S5. Add 6g of titanium dioxide nanospheres to 150mL of ethanol, add 1.5g of silane coupling agent KH560, heat to 50℃, stir and react for 2h, centrifuge, wash, and dry to obtain modified titanium dioxide nanospheres.

[0060] S6. Add 12g of chitosan@porous polystyrene / polyacrylate hollow spheres to 200mL of water, add 4g of N-hydroxysuccinimide and 4g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, stir and activate for 30min, add 2g of 2,2,2-trifluoroethylamine and 3g of aspartic acid, stir and react for 6h, centrifuge, wash, dry, and obtain modified hollow nanospheres;

[0061] S7. Add 10g of modified hollow nanospheres to 200mL of water, add 2g of modified titanium dioxide nanospheres, stir and react for 5h, centrifuge, wash, and dry to obtain hollow sphere plastic pigment.

[0062] Comparative Example 1

[0063] The difference from Example 3 is that step S4 was not performed.

[0064] Specifically as follows:

[0065] S1. Add 10g of nano-silica to 200mL of ethanol, add 2.5g of silane coupling agent KH570, heat to 50℃, stir and react for 3h, centrifuge, wash, and dry to obtain modified nano-silica;

[0066] S2. Add 10g of modified nano-silica and 5g of monomer to 200mL of diethyl ether aqueous solution (diethyl ether content is 50wt%), stir and mix for 10min, add 0.7g of hexadecyltrimethylammonium chloride, add 0.012g of ammonium persulfate under nitrogen protection, heat to 70℃, stir and react for 5h, centrifuge, wash, dry, and obtain porous polystyrene / polyacrylate modified nanospheres;

[0067] The monomers include styrene, methacrylic acid, and butyl methacrylate in a mass ratio of 9:5:1.5.

[0068] S3. Add 10g of porous polystyrene / polyacrylate modified nanospheres to 100mL of supercritical CO2 fluid to swell for 1.5d, filter, filter pore size greater than 500nm, wash the solid, dry, and obtain porous polystyrene / polyacrylate hollow spheres.

[0069] S4. Add 6g of titanium dioxide nanospheres to 150mL of ethanol, add 1.5g of silane coupling agent KH560, heat to 50℃, stir and react for 2h, centrifuge, wash, and dry to obtain modified titanium dioxide nanospheres.

[0070] S5. Add 12g of porous polystyrene / polyacrylate hollow spheres to 200mL of water, add 4g of N-hydroxysuccinimide and 4g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, stir and activate for 30min, add 2g of 2,2,2-trifluoroethylamine and 3g of aspartic acid, stir and react for 6h, centrifuge, wash, dry, and obtain modified hollow nanospheres;

[0071] S6. Add 10g of modified hollow nanospheres to 200mL of water, add 2g of modified titanium dioxide nanospheres, stir and react for 5h, centrifuge, wash, and dry to obtain hollow sphere plastic pigment.

[0072] Comparative Example 2

[0073] The difference from Example 3 is that 2,2,2-trifluoroethylamine was not added in step S6.

[0074] Specifically as follows:

[0075] S6. Add 12g of chitosan@porous polystyrene / polyacrylate hollow spheres to 200mL of water, add 4g of N-hydroxysuccinimide and 4g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, stir and activate for 30min, add 5g of aspartic acid, stir and react for 6h, centrifuge, wash, and dry to obtain modified hollow nanospheres.

[0076] Comparative Example 3

[0077] The difference from Example 3 is that aspartic acid was not added in step S6.

[0078] Specifically as follows:

[0079] S6. Add 12g of chitosan@porous polystyrene / polyacrylate hollow spheres to 200mL of water, add 4g of N-hydroxysuccinimide and 4g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, stir and activate for 30min, add 5g of 2,2,2-trifluoroethylamine, stir and react for 6h, centrifuge, wash, and dry to obtain modified hollow nanospheres.

[0080] Comparative Example 4

[0081] The difference from Example 3 is that step S6 was not performed.

[0082] S1. Add 10g of nano-silica to 200mL of ethanol, add 2.5g of silane coupling agent KH570, heat to 50℃, stir and react for 3h, centrifuge, wash, and dry to obtain modified nano-silica;

[0083] S2. Add 10g of modified nano-silica and 5g of monomer to 200mL of diethyl ether aqueous solution (diethyl ether content is 50wt%), stir and mix for 10min, add 0.7g of hexadecyltrimethylammonium chloride, add 0.012g of ammonium persulfate under nitrogen protection, heat to 70℃, stir and react for 5h, centrifuge, wash, dry, and obtain porous polystyrene / polyacrylate modified nanospheres;

[0084] The monomers include styrene, methacrylic acid, and butyl methacrylate in a mass ratio of 9:5:1.5.

[0085] S3. Add 10g of porous polystyrene / polyacrylate modified nanospheres to 100mL of supercritical CO2 fluid to swell for 1.5d, filter, filter pore size greater than 500nm, wash the solid, dry, and obtain porous polystyrene / polyacrylate hollow spheres.

[0086] S4. Add 13g of porous polystyrene / polyacrylate hollow spheres to 300mL of water, add 3.5g of N-hydroxysuccinimide and 3.2g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, stir and activate for 30min, add 8g of carboxymethyl chitosan, stir and react for 8h, add 0.12g of glutaraldehyde, stir and react for 10min, centrifuge, wash, dry, and obtain chitosan@porous polystyrene / polyacrylate hollow spheres;

[0087] S5. Add 6g of titanium dioxide nanospheres to 150mL of ethanol, add 1.5g of silane coupling agent KH560, heat to 50℃, stir and react for 2h, centrifuge, wash, and dry to obtain modified titanium dioxide nanospheres.

[0088] S6. Add 10g of chitosan@porous polystyrene / polyacrylate hollow spheres to 200mL of water, add 2g of modified titanium dioxide nanospheres, stir and react for 5h, centrifuge, wash, and dry to obtain hollow sphere plastic pigment.

[0089] Comparative Example 5

[0090] The difference from Example 3 is that step S7 was not performed.

[0091] S1. Add 10g of nano-silica to 200mL of ethanol, add 2.5g of silane coupling agent KH570, heat to 50℃, stir and react for 3h, centrifuge, wash, and dry to obtain modified nano-silica;

[0092] S2. Add 10g of modified nano-silica and 5g of monomer to 200mL of diethyl ether aqueous solution (diethyl ether content is 50wt%), stir and mix for 10min, add 0.7g of hexadecyltrimethylammonium chloride, add 0.012g of ammonium persulfate under nitrogen protection, heat to 70℃, stir and react for 5h, centrifuge, wash, dry, and obtain porous polystyrene / polyacrylate modified nanospheres;

[0093] The monomers include styrene, methacrylic acid, and butyl methacrylate in a mass ratio of 9:5:1.5.

[0094] S3. Add 10g of porous polystyrene / polyacrylate modified nanospheres to 100mL of supercritical CO2 fluid to swell for 1.5d, filter, filter pore size greater than 500nm, wash the solid, dry, and obtain porous polystyrene / polyacrylate hollow spheres.

[0095] S4. Add 13g of porous polystyrene / polyacrylate hollow spheres to 300mL of water, add 3.5g of N-hydroxysuccinimide and 3.2g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, stir and activate for 30min, add 8g of carboxymethyl chitosan, stir and react for 8h, add 0.12g of glutaraldehyde, stir and react for 10min, centrifuge, wash, dry, and obtain chitosan@porous polystyrene / polyacrylate hollow spheres;

[0096] S5. Add 6g of titanium dioxide nanospheres to 150mL of ethanol, add 1.5g of silane coupling agent KH560, heat to 50℃, stir and react for 2h, centrifuge, wash, and dry to obtain modified titanium dioxide nanospheres.

[0097] S6. Add 12g of chitosan@porous polystyrene / polyacrylate hollow spheres to 200mL of water, add 4g of N-hydroxysuccinimide and 4g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, stir and activate for 30min, add 2g of 2,2,2-trifluoroethylamine and 3g of aspartic acid, stir and react for 6h, centrifuge, wash, and dry to obtain modified hollow nanospheres, which are hollow sphere plastic pigments.

[0098] Test Example 1

[0099] The hollow sphere plastic pigments obtained in Examples 1-3 and Comparative Examples 1-5 of this invention were used to formulate coatings with the following formulas (parts by weight): 20 parts calcium carbonate, 60 parts kaolin, 7 parts hollow sphere plastic pigment, 5 parts starch, 13 parts latex, 1.2 parts water-resistant agent, and 0.4 parts lubricant. The solid content of the coating was 60.2%. The prepared coating was coated onto paper using a soft calender, with a coating weight of 8 g / m². 2 • The drying temperature was 160℃. The blank group used kaolin instead of hollow sphere plastic pigments. The performance of the prepared lightweight coated paper (LWC) was tested, and the results are shown in Table 1.

[0100] Table 1

[0101]

[0102] As can be seen from the table above, the hollow sphere plastic pigments obtained in Examples 1-3 of the present invention can significantly improve the performance of the prepared lightweight coated paper (LWC).

[0103] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a hollow sphere plastic pigment, characterized in that, After the surface of nano-silica is modified with a silane coupling agent containing double bonds, it is polymerized with acrylic monomers and styrene monomers, swelled in supercritical CO2 fluid, filtered to remove the template, surface activated, coupled with carboxymethyl chitosan and crosslinked, then coupled with 2,2,2-trifluoroethylamine and aspartic acid, and reacted with titanium dioxide nanospheres modified with epoxy-containing silane coupling agents to obtain hollow spherical plastic pigments.

2. The preparation method according to claim 1, characterized in that, Includes the following steps: S1. Add nano-silica to ethanol, add a silane coupling agent with double bonds, heat and stir to react, centrifuge, wash, and dry to obtain modified nano-silica; S2. Add the modified nano-silica and monomer to an aqueous ether solution, stir and mix evenly, add a pore-forming agent, add an initiator dropwise under inert gas protection, heat and stir to react, centrifuge, wash, and dry to obtain porous polystyrene / polyacrylate modified nanospheres; S3. Porous polystyrene / polyacrylate modified nanospheres were added to supercritical CO2 fluid to swell, filtered, washed with solids, and dried to obtain porous polystyrene / polyacrylate hollow spheres. S4. Add porous polystyrene / polyacrylate hollow spheres to water, add N-hydroxysuccinimide and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, stir to activate, add carboxymethyl chitosan, stir to react, add glutaraldehyde curing agent, centrifuge, wash, dry, and obtain chitosan@porous polystyrene / polyacrylate hollow spheres; S5. Add titanium dioxide nanospheres to ethanol, add silane coupling agent with epoxy group, heat and stir to react, centrifuge, wash, and dry to obtain modified titanium dioxide nanospheres; S6. Chitosan@porous polystyrene / polyacrylate hollow spheres were added to water, along with N-hydroxysuccinimide and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide. The mixture was stirred and activated, and then 2,2,2-trifluoroethylamine and aspartic acid were added. The mixture was stirred and reacted, centrifuged, washed, and dried to obtain modified hollow nanospheres. S7. Add modified hollow nanospheres to water, add modified titanium dioxide nanospheres, stir to react, centrifuge, wash, and dry to obtain hollow sphere plastic pigment.

3. The preparation method according to claim 2, characterized in that, The average particle size of the nano-silica in step S1 is 100-200 nm, the mass ratio of the nano-silica to the silane coupling agent with double bonds is 10:2-3, the heating and stirring reaction temperature is 45-55℃, and the time is 2-4 h, wherein the silane coupling agent with double bonds is selected from at least one of KH570, A151, and A171.

4. The preparation method according to claim 2, characterized in that, The monomers in step S2 include styrene, methacrylic acid, and butyl methacrylate in a mass ratio of 8-10:4-6:1-2. The mass ratio of the modified nano-silica, monomers, porogen, and initiator is 10:4-6:0.5-1:0.01-0.

015. The heating and stirring reaction is carried out at a temperature of 65-75°C for 4-6 hours. The porogen is selected from at least one of hexadecyltrimethylammonium chloride, hexadecylbenzyldimethylammonium chloride, hexadecyltrimethylsodium chloride, hexadecyltrimethylammonium bromide, hexadecyltrimethylsodium bromide, and hexadecylbenzyldimethylsodium chloride. The initiator is selected from at least one of sodium persulfate, potassium persulfate, and ammonium persulfate.

5. The preparation method according to claim 2, characterized in that, The swelling time described in step S3 is 1-2 days.

6. The preparation method according to claim 2, characterized in that, In step S4, the mass ratio of porous polystyrene / polyacrylate hollow spheres, N-hydroxysuccinimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, carboxymethyl chitosan, and glutaraldehyde is 12-15:3-4:3-4:6-10:0.1-0.15, and the stirring reaction time is 6-10 hours.

7. The preparation method according to claim 2, characterized in that, In step S5, the mass ratio of the titanium dioxide nanospheres to the epoxy-containing silane coupling agent is 5-7:1-2, the heating and stirring reaction temperature is 45-55℃, the time is 1-3h, and the epoxy-containing silane coupling agent is KH560.

8. The preparation method according to claim 2, characterized in that, In step S6, the mass ratio of chitosan@porous polystyrene / polyacrylate hollow spheres, N-hydroxysuccinimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, 2,2,2-trifluoroethylamine, and aspartic acid is 10-15:3-5:3-5:1-3:2-4, and the stirring reaction time is 5-7 hours.

9. The preparation method according to claim 2, characterized in that, In step S7, the mass ratio of the modified hollow nanospheres to the modified titanium dioxide nanospheres is 10:1-3, and the stirring reaction time is 4-6 hours.

10. A hollow sphere plastic pigment prepared by the preparation method according to any one of claims 1-9.

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