A composite talc paper filler, its preparation method and application

Abstract

This invention discloses a composite talc paper filler, its preparation method, and its application, belonging to the field of papermaking technology. The invention involves dissolving polylactic acid and didecyl dimethyl ammonium chloride in a dichloromethane / acetone mixed solvent, adding talc and polyethylene glycol octadecyl ether, and dispersing them evenly to obtain an oil phase. The oil phase is then added dropwise to a polyvinyl alcohol / hydroxyethyl starch aqueous solution and homogenized to obtain an emulsion. The organic solvent is removed from the emulsion to obtain solidified microspheres, which are then centrifuged, washed, and dried to obtain modified talc. The prepared composite talc paper filler has a core-shell structure and possesses cationic group characteristics on its surface, which is beneficial for improving the retention of fillers and fine fibers. Furthermore, the use of this composite talc paper filler improves paper performance, such as smoothness, surface strength, whiteness, and opacity, and enhances paper sizing and ink absorption.

Description

Technical Field

[0001] This invention belongs to the field of papermaking technology, specifically relating to a composite talc papermaking filler, its preparation method, and its application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Adding fillers to papermaking effectively solves the problem of fiber raw material shortage in the papermaking industry, reduces production costs, and can also improve certain specific properties of paper. Currently, commonly used fillers in the papermaking industry include inorganic fillers such as calcium carbonate, talc, kaolin, and titanium dioxide. When these fillers are added to the pulp, they disperse between the fibers, making the paper structure loose and porous, reducing the contact and hydrogen bonding between fibers, thus decreasing the physical strength of the paper sheet; increasing paper dusting and linting, and increasing paper capillary porosity, thereby improving paper absorbency, reducing paper stretching and deformation, and improving water retention; facilitating dehydration in the wire and press sections and accelerating drying speed; and reducing paper sizing, especially alkaline fillers which are more detrimental to acidic sizing.

[0004] In recent years, the demand for high-performance fillers has been continuously increasing. Improving paper performance by enhancing filler properties is an important development direction. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a composite talc paper filler, its preparation method, and its application. The composite talc paper filler provided by this invention can significantly improve paper performance.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] In a first aspect, the present invention provides a method for preparing a composite talc paper filler, comprising the following steps:

[0008] Polylactic acid (PLA) and didecyl dimethyl ammonium chloride were dissolved in a dichloromethane (DCM) / acetone mixed solvent, and talc and polyethylene glycol octadecyl ether were added and dispersed evenly to obtain the oil phase;

[0009] The oil phase was added dropwise to a polyvinyl alcohol (PVA) / hydroxyethyl starch aqueous solution and homogenized to obtain an emulsion.

[0010] The organic solvent was removed from the emulsion to obtain solidified microspheres, which were then centrifuged, washed, and dried to obtain composite talc paper filler.

[0011] In some embodiments of the present invention, the concentration of polylactic acid in the oil phase is 36-52 g / L, and the concentration of didecyldimethylammonium chloride is 9-13 g / L.

[0012] In some embodiments of the present invention, the molecular weight of the polylactic acid is 36,000-48,000, and the ratio of polylactic acid to didecyl dimethyl ammonium chloride is 4:1.

[0013] In some embodiments of the present invention, the dichloromethane / acetone mixed solvent contains 90%-95% dichloromethane and 5%-10% acetone by volume.

[0014] In some embodiments of the present invention, the average particle size of the talc is 0.6-1.5 μm, and the mass ratio of talc to polylactic acid is 1.5-2.0:1.

[0015] In some embodiments of the present invention, the concentration of polyethylene glycol octadecyl ether in the oil phase is 0.2-0.5 g / L.

[0016] In some embodiments of the present invention, the weight-average molecular weight of the polyvinyl alcohol is 20,000-26,000;

[0017] In the polyvinyl alcohol / hydroxyethyl starch aqueous solution, the concentration of polyvinyl alcohol is 0.5%-1.0%, and the concentration of hydroxyethyl starch is 0.1%-0.3% by mass.

[0018] In some embodiments of the present invention, the volume ratio of the oil phase to the polyvinyl alcohol / hydroxyethyl starch aqueous solution is 1:8-12.

[0019] In some embodiments of the present invention, the homogenization is high-speed homogenization dispersion with a rotation speed of 12,000-24,000 rpm and a dispersion time of 45-60 min.

[0020] In some embodiments of the present invention, organic solvents in the emulsion are removed by stirring, wherein the stirring speed is 500-800 rpm and the stirring time is 80-140 min.

[0021] In some embodiments of the present invention, the centrifugation speed is 3000-6000 rpm and the time is 5-10 min.

[0022] In a second aspect, the present invention provides a composite talc paper filler, wherein the composite talc paper filler is prepared by the preparation method described in the first aspect.

[0023] The composite talc paper filling material provided by this invention is a talc filling material with a surface-cationized polymer coating. It has a core-shell structure, with polylactic acid coating the surface of the talc powder, and quaternary ammonium salt groups attached to the polylactic acid surface. The coating improves the shape of the talc powder particles, making their structure more regular and ordered, which is conducive to their arrangement and filling inside the paper sheet. The surface of the filling material has cationic group characteristics, which can improve the electrostatic adsorption and physical adsorption with the fiber surface, which is beneficial to the retention of the filling material. The surface groups of the filling material enhance the flocculation effect with fine fibers, which is beneficial to the retention of fine fibers, improves the water filtration performance of the wire section, and reduces the amount of retention aids and filter aids used. When used, the composite talc paper filler provided by this invention can improve the smoothness, surface strength, whiteness, and opacity of paper sheets; due to the improved bonding of paper sheet components, it can improve the physical strength of the finished paper; it improves the interaction between sizing agents and fibers, which is beneficial to improving the sizing degree of the paper sheet; it can also improve the surface energy of the paper, optimize the pore structure of the paper sheet, which is beneficial to the transfer and penetration of ink, improve the ink absorption value of the paper, ensure that the ink can be uniformly attached to the paper surface, and improve the clarity and detail of the printing.

[0024] A third aspect of the present invention provides an application of the composite talc paper filler described in the second aspect in the papermaking field;

[0025] The application is that composite talc powder is used as a paper filling material to improve paper performance.

[0026] The beneficial effects of this invention are as follows:

[0027] This invention utilizes emulsification to coat talc powder with a cationic polymer, resulting in a composite talc paper filler that significantly improves paper performance and reduces the adverse effects of fillers on paper properties. Specifically, the composite talc paper filler provided by this invention is a talc filler with a surface-coated cationic polymer. It has a core-shell structure, and the coating improves the shape of the talc particles, making their structure more regular and ordered, which is beneficial for their arrangement and filling within the paper sheet. The filler surface possesses cationic group characteristics, which improves electrostatic and physical adsorption with the fiber surface, thus promoting filler retention. The surface groups of the filler enhance the flocculation effect with fine fibers, further improving fiber retention, enhancing the filtration performance of the wire section, and reducing the amount of retention aids and filter aids required. When used, the composite talc paper filler provided by this invention can improve the smoothness, surface strength, whiteness, and opacity of paper sheets; due to the improved bonding of paper sheet components, it can improve the physical strength of the finished paper; it improves the interaction between sizing agents and fibers, which is beneficial to improving the sizing degree of the paper sheet; it can also improve the surface energy of the paper, optimize the pore structure of the paper sheet, which is beneficial to the transfer and penetration of ink, improve the ink absorption value of the paper, ensure that the ink can be uniformly attached to the paper surface, and improve the clarity and detail of the printing. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0029] Example 1

[0030] Double-sided offset paper was produced using conventional talc filler. The average particle size of the talc was 0.94 μm, and its dosage was 20% of the pulp. The fiber retention rate in the wet end of the paper machine was 93.8%, the filler single-pass retention rate was 54.2%, the dynamic water filtration rate over 30 seconds was 408.4 g, and the white water concentration was 0.54%. The bulk of the prepared paper was 2.76 g / cm³. 3 Whiteness 82.3% ISO, opacity 84.2%, smoothness 284s, print roughness 1.12m / s, bursting strength 5.17kPa·m 2 ·g -1 Tensile strength: 52.8 N·m / g; Tear strength: 4.28 mN·m 2 ·g -1 The sizing time is 27.4s, and the K&N value is 52.7%.

[0031] This invention relates to the preparation of composite talc paper fillers coated with cationic polymers. The preparation method of the composite talc paper filler includes the following steps:

[0032] A mixed solvent for the oil phase was prepared, comprising 92% DCM and 8% acetone. PLA and didecyl dimethyl ammonium chloride were dissolved in the DCM / acetone mixed solvent. The PLA had a molecular weight of 36,000 and a concentration of 52 g / L, while the didecyl dimethyl ammonium chloride concentration was 13 g / L, with a ratio of 4:1. The aforementioned comparative talc and polyethylene glycol octadecyl ether were added and dispersed evenly. The average particle size of the talc was 0.94 μm, the mass ratio of talc to PLA was 1.7:1, and the concentration of polyethylene glycol octadecyl ether was 0.30 g / L. This mixture served as the oil phase.

[0033] Prepare an aqueous solution with PVA weight average molecular weight of 26,000, PVA concentration of 1.0% in aqueous solution, hydroxyethyl starch concentration of 0.10%, and oil phase to aqueous phase volume ratio of 1:8.

[0034] The oil phase was added dropwise to a PVA / hydroxyethyl starch aqueous solution and homogenized at high speed using a homogenizer at 18,000 rpm for 56 min to obtain an emulsion. The emulsion was stirred at 800 rpm for 80 min to evaporate the organic solvent, resulting in solidified microspheres. These microspheres were then centrifuged at 4,500 rpm for 8 min. The product was washed and dried to obtain a composite talc paper filler.

[0035] The composite talc paper filler has an average particle size of 1.15 μm and is used at 20% of the pulp. The fiber retention rate in the wet end of the paper machine is 95.1%, and the filler single-pass retention rate is 61.3%, both significantly improved. The dynamic water filtration rate in 30 seconds is 419.7 g, indicating improved filtration performance. The white water concentration is 0.32%, reducing white water concentration and facilitating its recovery, treatment, and reuse. The resulting paper sheet has a bulk of 2.81 g / cm³. 3 Whiteness 83.4% ISO, opacity 86.8%, increased filler retention improves paper optical properties; smoothness 304s, print roughness 1.21m / s, improved surface strength and smoothness, bursting strength 5.32KPa·m 2 ·g -1 Tensile strength: 54.6 N·m / g; Tear strength: 4.54 mN·m 2 ·g -1 With a sizing degree of 31.2s and a K&N value of 49.6%, it improves sizing and ink absorption.

[0036] Comparative Example 1

[0037] The difference from Example 1 is that the solvent in the preparation system is 100% DCM, while the rest is the same as in Example 1.

[0038] The average particle size of the obtained composite talc paper filler was 1.14 μm, and its dosage was 20% of the pulp. The fiber retention rate in the wet end of the paper machine was 94.3%, the filler single-pass retention rate was 57.5%, the dynamic water filtration rate over 30 seconds was 412.3 g, and the white water concentration was 0.39%. The bulk of the prepared paper was 2.79 g / cm². 3 Whiteness 82.9% ISO, opacity 85.9%, smoothness 293s, printing fuzz strength 1.16m / s, bursting strength 5.25KPa·m 2 ·g -1 Tensile strength: 53.5 N·m / g; Tear strength: 4.35 mN·m 2 ·g -1 The sizing time was 29.3s, and the K&N value was 51.6%.

[0039] Comparative Example 2

[0040] The difference from Example 1 is that hydroxyethyl starch is not added to the aqueous phase system in the preparation system, but the rest is the same as in Example 1.

[0041] The average particle size of the obtained composite talc paper filler was 1.16 μm, and its dosage was 20% of the pulp. The fiber retention rate in the wet end of the paper machine was 94.1%, the filler single-pass retention rate was 57.2%, the dynamic water filtration rate over 30 seconds was 411.9 g, and the white water concentration was 0.38%. The bulk of the prepared paper was 2.78 g / cm².3 Whiteness 82.7% ISO, opacity 85.6%, smoothness 295s, print roughness 1.15m / s, bursting strength 5.27kPa·m 2 ·g -1 Tensile strength: 53.8 N·m / g; Tear strength: 4.41 mN·m 2 ·g -1 The sizing time is 28.9s, and the K&N value is 51.8%.

[0042] Comparative Example 3

[0043] The difference from Example 1 is that polyethylene glycol octadecyl ether is not added to the preparation system, and hydroxyethyl starch is not added to the aqueous system; otherwise, it is the same as Example 1.

[0044] The average particle size of the obtained composite talc paper filler was 1.15 μm, and its dosage was 20% of the pulp. The fiber retention rate in the wet end of the paper machine was 94.3%, the filler single-pass retention rate was 57.1%, the dynamic water filtration rate over 30 seconds was 410.5 g, and the white water concentration was 0.37%. The bulk of the prepared paper was 2.77 g / cm². 3 Whiteness 82.6% ISO, opacity 85.3%, smoothness 291s, print roughness 1.16m / s, bursting strength 5.21kPa·m 2 ·g -1 Tensile strength index: 53.3 N·m / g; Tear strength index: 4.37 mN·m 2 ·g -1 The sizing time was 28.3s, and the K&N value was 51.7%.

[0045] Example 2

[0046] Double-sided offset paper was produced using conventional talc filler. The average particle size of the talc was 1.21 μm, and its dosage was 20% of the pulp. The fiber retention rate in the wet end of the paper machine was 93.2%, the filler single-pass retention rate was 53.1%, the dynamic water filtration rate over 30 seconds was 409.0 g, and the white water concentration was 0.55%. The bulk of the prepared paper was 2.74 g / cm². 3 Whiteness 82.1% ISO, opacity 83.9%, smoothness 281s, print roughness 1.10m / s, bursting strength 5.19KPa·m 2 ·g -1 Tensile strength: 53.2 N·m / g; Tear strength: 4.31 mN·m 2 ·g -1 The sizing time is 27.7s, and the K&N value is 52.5%.

[0047] This invention relates to the preparation of composite talc paper fillers coated with cationic polymers. The preparation method of the composite talc paper filler includes the following steps:

[0048] A mixed solvent for the oil phase was prepared, comprising 90% DCM and 10% acetone. PLA and didecyl dimethyl ammonium chloride were dissolved in the DCM / acetone mixed solvent. The PLA had a molecular weight of 46,000 and a concentration of 48 g / L, while the didecyl dimethyl ammonium chloride concentration was 12 g / L, with a ratio of 4:1. The aforementioned comparative talc and polyethylene glycol octadecyl ether were added and dispersed evenly. The average particle size of the talc was 1.21 μm, the mass ratio of talc to PLA was 2.0:1, and the concentration of polyethylene glycol octadecyl ether was 0.50 g / L, forming the oil phase.

[0049] Prepare an aqueous solution with PVA weight average molecular weight of 24,500, PVA concentration of 0.8% in aqueous solution, hydroxyethyl starch concentration of 0.15%, and oil phase to aqueous phase volume ratio of 1:9.

[0050] The oil phase was added dropwise to a PVA / hydroxyethyl starch aqueous solution and homogenized at high speed using a homogenizer at 24,000 rpm for 49 min to obtain an emulsion. The emulsion was then stirred at 500 rpm for 140 min to evaporate the organic solvent, resulting in solidified microspheres. These microspheres were subsequently centrifuged at 6,000 rpm for 5 min. The product was washed and dried to obtain a composite talc paper filler.

[0051] The composite talc paper filler has an average particle size of 1.34 μm and is used at 20% of the pulp. The fiber retention rate in the wet end of the paper machine is 95.0%, the filler single-pass retention rate is 61.2%, the dynamic water filtration rate over 30 seconds is 421.3 g, and the white water concentration is 0.33%. The resulting paper sheet has a bulk of 2.80 g / cm². 3 Whiteness 83.3% ISO, opacity 86.7%, smoothness 302s, print roughness 1.20m / s, bursting strength 5.38kPa·m 2 ·g -1 Tensile strength: 55.3 N·m / g; Tear strength: 4.58 mN·m 2 ·g -1 The sizing degree is 31.0s, and the K&N value is 49.8%.

[0052] Example 3

[0053] Double-sided offset paper was produced using conventional talc filler. The average particle size of the talc was 1.45 μm, and its dosage was 20% of the pulp. The fiber retention rate in the wet end of the paper machine was 93.0%, the filler single-pass retention rate was 52.4%, the dynamic water filtration rate over 30 seconds was 409.3 g, and the white water concentration was 0.56%. The bulk of the prepared paper was 2.73 g / cm². 3Whiteness 82.2% ISO, opacity 83.1%, smoothness 280s, print roughness 1.13m / s, bursting strength 5.13KPa·m 2 ·g -1 Tensile strength: 53.7 N·m / g; Tear strength: 4.35 mN·m 2 ·g -1 The sizing time was 28.1s, and the K&N value was 52.3%.

[0054] This invention relates to the preparation of composite talc paper fillers coated with cationic polymers. The preparation method of the composite talc paper filler includes the following steps:

[0055] A mixed solvent for the oil phase was prepared, comprising 93% DCM and 7% acetone. PLA and didecyl dimethyl ammonium chloride were dissolved in the DCM / acetone mixed solvent. The PLA had a molecular weight of 39,000 and a concentration of 44 g / L, while the didecyl dimethyl ammonium chloride concentration was 11 g / L, with a ratio of 4:1. The aforementioned comparative talc and polyethylene glycol octadecyl ether were added and dispersed evenly. The average particle size of the talc was 1.45 μm, the mass ratio of talc to PLA was 1.8:1, and the concentration of polyethylene glycol octadecyl ether was 0.40 g / L. This mixture served as the oil phase.

[0056] Prepare an aqueous solution with PVA weight average molecular weight of 23,000, PVA concentration of 0.5% in aqueous solution, hydroxyethyl starch concentration of 0.30%, and oil phase to aqueous phase volume ratio of 1:12.

[0057] The oil phase was added dropwise to a PVA / hydroxyethyl starch aqueous solution and homogenized at high speed using a homogenizer at 12,000 rpm for 52 min to obtain an emulsion. The emulsion was stirred at 650 rpm for 125 min to evaporate the organic solvent, resulting in solidified microspheres. These microspheres were then centrifuged at 5,250 rpm for 7 min. The product was washed and dried to obtain a composite talc paper filler.

[0058] The composite talc paper filler has an average particle size of 1.54 μm and is used at 20% of the pulp. The fiber retention rate in the wet end of the paper machine is 95.1%, the filler single-pass retention rate is 60.7%, the dynamic water filtration rate over 30 seconds is 420.5 g, and the white water concentration is 0.34%. The resulting paper sheet has a bulk of 2.81 g / cm². 3 Whiteness 83.4% ISO, opacity 86.9%, smoothness 304s, print roughness 1.23m / s, bursting strength 5.35kPa·m 2 ·g -1 Tensile strength: 55.6 N·m / g; Tear strength: 4.62 mN·m 2 ·g -1The sizing time is 31.3s, and the K&N value is 49.9%.

[0059] Example 4

[0060] Double-sided offset paper was produced using conventional talc filler. The average particle size of the talc was 0.78 μm, and its dosage was 20% of the pulp. The fiber retention rate in the wet end of the paper machine was 93.2%, the filler single-pass retention rate was 52.9%, the dynamic water filtration rate over 30 seconds was 409.9 g, and the white water concentration was 0.54%. The bulk of the prepared paper was 2.71 g / cm². 3 Whiteness 82.5% ISO, opacity 83.3%, smoothness 282s, print roughness 1.14m / s, bursting strength 5.21kPa·m 2 ·g -1 Tensile strength: 53.9 N·m / g; Tear strength: 4.31 mN·m 2 ·g -1 The sizing time is 27.7s, and the K&N value is 52.4%.

[0061] This invention relates to the preparation of composite talc paper fillers coated with cationic polymers. The preparation method of the composite talc paper filler includes the following steps:

[0062] A mixed solvent for the oil phase was prepared, comprising 95% DCM and 5% acetone. PLA and didecyl dimethyl ammonium chloride were dissolved in the DCM / acetone mixed solvent. The PLA had a molecular weight of 42,000 and a concentration of 36 g / L, while the didecyl dimethyl ammonium chloride concentration was 9 g / L, with a ratio of 4:1. The aforementioned comparative talc and polyethylene glycol octadecyl ether were added and dispersed evenly. The average particle size of the talc was 0.78 μm, the mass ratio of talc to PLA was 1.5:1, and the concentration of polyethylene glycol octadecyl ether was 0.35 g / L. This mixture served as the oil phase.

[0063] Prepare an aqueous solution with PVA weight average molecular weight of 20,000, PVA concentration of 0.6% in aqueous solution, hydroxyethyl starch concentration of 0.25%, and oil phase to water phase volume ratio of 1:11.

[0064] The oil phase was added dropwise to a PVA / hydroxyethyl starch aqueous solution and homogenized at high speed using a homogenizer at 21,000 rpm for 60 min to obtain an emulsion. The emulsion was stirred at 700 rpm for 95 min to evaporate the organic solvent, resulting in solidified microspheres. These microspheres were then centrifuged at 3750 rpm for 9 min. The product was washed and dried to obtain a composite talc paper filler.

[0065] The composite talc paper filler has an average particle size of 0.94 μm and is used at 20% of the pulp. The fiber retention rate in the wet end of the paper machine is 95.2%, the filler single-pass retention rate is 60.3%, the dynamic water filtration rate over 30 seconds is 421.4 g, and the white water concentration is 0.35%. The resulting paper sheet has a bulk of 2.83 g / cm². 3 Whiteness 83.5% ISO, opacity 87.3%, smoothness 309s, printing fuzzing strength 1.25m / s, bursting strength 5.33KPa·m 2 ·g -1 Tensile strength: 55.4 N·m / g; Tear strength: 4.65 mN·m 2 ·g -1 The sizing time is 32.2s, and the K&N value is 49.7%.

[0066] Example 5

[0067] Double-sided offset paper was produced using conventional talc filler. The average particle size of the talc was 0.62 μm, and its dosage was 20% of the pulp. The fiber retention rate in the wet end of the paper machine was 93.3%, the filler single-pass retention rate was 52.5%, the dynamic water filtration rate over 30 seconds was 408.3 g, and the white water concentration was 0.56%. The bulk of the prepared paper was 2.76 g / cm². 3 Whiteness 82.3% ISO, opacity 83.6%, smoothness 285s, print roughness 1.11m / s, bursting strength 5.23kPa·m 2 ·g -1 Tensile strength: 54.2 N·m / g; Tear strength: 4.33 mN·m 2 ·g -1 The sizing time is 27.9s, and the K&N value is 52.8%.

[0068] This invention relates to the preparation of composite talc paper fillers coated with cationic polymers. The preparation method of the composite talc paper filler includes the following steps:

[0069] A mixed solvent for the oil phase was prepared, comprising 94% DCM and 6% acetone. PLA and didecyl dimethyl ammonium chloride were dissolved in the DCM / acetone mixed solvent. The PLA had a molecular weight of 48,000 and a concentration of 40 g / L, while the didecyl dimethyl ammonium chloride concentration was 10 g / L, with a ratio of 4:1. The aforementioned comparative talc and polyethylene glycol octadecyl ether were added and dispersed evenly. The average particle size of the talc was 0.62 μm, the mass ratio of talc to PLA was 1.6:1, and the concentration of polyethylene glycol octadecyl ether was 0.20 g / L, forming the oil phase.

[0070] Prepare an aqueous solution with PVA weight average molecular weight of 21,500, PVA concentration of 0.7% in aqueous solution, hydroxyethyl starch concentration of 0.20%, and oil phase to aqueous phase volume ratio of 1:10.

[0071] The oil phase was added dropwise to a PVA / hydroxyethyl starch aqueous solution and homogenized at high speed using a homogenizer at 15,000 rpm for 45 min to obtain an emulsion. The emulsion was stirred at 600 rpm for 110 min to evaporate the organic solvent, resulting in solidified microspheres. These microspheres were then centrifuged at 3,000 rpm for 10 min. The product was washed and dried to obtain a composite talc paper filler.

[0072] The composite talc paper filler has an average particle size of 0.79 μm and is used at 20% of the pulp. The fiber retention rate in the wet end of the paper machine is 95.3%, the filler single-pass retention rate is 60.2%, the dynamic water filtration rate over 30 seconds is 422.8 g, and the white water concentration is 0.34%. The resulting paper sheet has a bulk of 2.85 g / cm³. 3 Whiteness 83.3% ISO, opacity 87.6%, smoothness 307s, print roughness 1.24m / s, bursting strength 5.38kPa·m 2 ·g -1 Tensile strength: 55.7 N·m / g; Tear strength: 4.74 mN·m 2 ·g -1 The sizing time is 33.3s, and the K&N value is 49.8%.

[0073] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a composite talc paper filler, characterized in that, Includes the following steps: Polylactic acid and didecyl dimethyl ammonium chloride were dissolved in a dichloromethane / acetone mixed solvent, and talc and polyethylene glycol octadecyl ether were added and dispersed evenly to obtain an oil phase; The oil phase was added dropwise to a polyvinyl alcohol / hydroxyethyl starch aqueous solution and homogenized to obtain an emulsion. The organic solvent was removed from the emulsion to obtain solidified microspheres, which were then centrifuged, washed, and dried to obtain modified talc powder. In the oil phase, the concentration of polylactic acid is 36-52 g / L, and the concentration of didecyldimethylammonium chloride is 9-13 g / L; The polylactic acid has a molecular weight of 36,000-48,000, and the ratio of polylactic acid to didecyl dimethyl ammonium chloride is 4:

1. In the dichloromethane / acetone mixed solvent, the dichloromethane content is 90%-95% and the acetone content is 5%-10% by volume. The talc powder has an average particle size of 0.6-1.5 μm, and the mass ratio of talc powder to polylactic acid is 1.5-2.0:

1. Alternatively, in the oil phase, the concentration of the polyethylene glycol octadecyl ether is 0.2-0.5 g / L; The weight-average molecular weight of the polyvinyl alcohol is 20,000-26,000; In the polyvinyl alcohol / hydroxyethyl starch aqueous solution, the concentration of polyvinyl alcohol is 0.5%-1.0% and the concentration of hydroxyethyl starch is 0.1%-0.3% by mass. The volume ratio of the oil phase to the polyvinyl alcohol / hydroxyethyl starch aqueous solution is 1:8-12.

2. The preparation method of the composite talc paper filler as described in claim 1, characterized in that, The homogenization is a high-speed homogenization dispersion with a rotation speed of 12,000-24,000 rpm and a dispersion time of 45-60 min; Alternatively, the organic solvent in the emulsion can be removed by stirring, wherein the stirring speed is 500-800 rpm and the stirring time is 80-140 min; Alternatively, the centrifugation speed is 3000-6000 rpm, and the time is 5-10 min.

3. A composite talc paper filler, characterized in that, The composite talc paper filler is prepared by any one of the preparation methods described in claims 1-2.

4. The application of the composite talc paper filler as described in claim 3 in the papermaking field; The application is that composite talc powder is used as a paper filling material to improve paper performance.