Preparation method and application of performance-enhanced light calcium carbonate filler

Abstract

The application discloses a preparation method of performance-enhanced light calcium carbonate filling material and application thereof, and utilizes microporous nanometer aeration technology to effectively increase the contact area of CO2 and calcium hydroxide molecules, so that the calcium hydroxide molecules are fully carbonized, and the crystal structure of calcium carbonate is more regular by combining with a crystal form directing agent; and the ultrasonic technology is combined with a dispersing agent and a compound active agent to perform active modification on the calcium carbonate, so that the calcium carbonate particles are more comprehensively and uniformly coated, the functionalization of the light calcium carbonate is realized, and the method is an environment-friendly, simple and easy-to-realize industrial production method.

Description

Technical Field

[0001] This invention belongs to the field of biodegradable membrane materials, specifically relating to a method for preparing a performance-enhanced lightweight calcium carbonate filler and its application. Background Technology

[0002] In recent years, with the global emphasis on environmental protection and energy conservation, as well as the rapid development of industries such as rubber, plastics, papermaking, and sealants, and the increasing demand for high-quality products, it is imperative to strengthen the research and development and production of high-quality light calcium carbonate.

[0003] Light calcium carbonate is an important filler in rubber, plastics, paper and sealant products. It can effectively improve the heat resistance, wear resistance, dimensional stability, rigidity and processability of the products, and reduce the cost of materials.

[0004] However, when light calcium carbonate is used directly in organic media, it suffers from common problems such as poor dispersibility and poor compatibility. These drawbacks become more pronounced with increasing amounts of light calcium carbonate used, and overfilling can even reduce the performance of the product. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0007] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a performance-enhanced lightweight calcium carbonate filler.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for preparing a performance-enhanced lightweight calcium carbonate filler, comprising, Quicklime is reacted with hot water to undergo a digestion reaction, then allowed to stand at room temperature for aging and is sieved to obtain calcium hydroxide slurry. Add calcium hydroxide slurry to the reaction vessel and stir. Release a mixture of CO2 and N2 gas into the reaction vessel in the form of microporous nano-aeration to allow it to undergo an in-situ carbonization reaction with the calcium hydroxide slurry. At the same time, add a crystal-directing agent to the slurry. When the pH value of the reaction slurry drops to 6.5~7, stop the carbonization reaction. After standing and aging at room temperature, carry out a second carbonization reaction. After standing and aging, extract the upper clear liquid to obtain a highly concentrated slurry. The highly concentrated slurry is transferred to an activation reactor. Under stirring conditions, the slurry temperature rises to 60-90℃. Then, a dispersant and a compound activator are added to the slurry. After ultrasonic activation and modification treatment for 1-3 hours, the slurry is filtered, dried, pulverized, and sieved to obtain functionalized light calcium carbonate powder.

[0009] In a preferred embodiment of the preparation method described in this invention, quicklime is digested with hot water in a mass ratio of 1:6 to 8, and the hot water temperature is 80 to 100°C.

[0010] As a preferred embodiment of the preparation method described in this invention, the step of standing at room temperature for aging and sieving includes aging for 24-72 hours and sieving through a 200-mesh sieve.

[0011] As a preferred embodiment of the preparation method of the present invention, the CO2 and N2 mixed gas is released into the reaction vessel in the form of microporous nano-aeration to carry out in-situ carbonization reaction with calcium hydroxide slurry. The pore size of the aeration holes of the microporous nano-aeration is less than 2 μm, and the flow rate of the mixed gas is 1~2 L / min for CO2 and 2~4 L / min for N2.

[0012] As a preferred embodiment of the preparation method described in this invention, the crystal-directing agent includes any one of sucrose, glucose, sorbitol, citric acid and chitosan, and the crystal-directing agent accounts for 0.15~0.2% of the mass of the slurry.

[0013] As a preferred embodiment of the preparation method described in this invention, the dispersant is any one of polyvinylpyrrolidone, polysorbate-80, alkyl glycoside, and disodium lauroylamphodiacetate, and the compound activator is any combination of several of polyacrylate, stearate, lauric acid, palmitic acid, sodium dodecylbenzenesulfonate, and silane coupling agent.

[0014] In a preferred embodiment of the preparation method described in this invention, the compound activator accounts for 1-3% of the mass percentage of the slurry, and the dispersant accounts for 0.1-0.2% of the mass percentage of the slurry.

[0015] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for preparing a performance-enhanced lightweight calcium carbonate filler, resulting in functionalized lightweight calcium carbonate powder with a particle size of 50-100 nm and a water contact angle of 129.7°. ° .

[0016] Another objective of this invention is to overcome the shortcomings of the prior art and provide an application of functionalized lightweight calcium carbonate powder in the preparation of biodegradable membranes, including, By weight, PLA is 30-40 parts, PBAT is 20-30 parts, chain extender is 0.1-0.2 parts, lubricant is 0.1-0.2 parts, and functionalized light calcium carbonate is 20-40 parts; PLA, PBAT, chain extender, lubricant, and functionalized light calcium carbonate are prepared separately, and the raw materials are mixed evenly. The chain extender is an amine compound; the lubricant is one of erucamide, oleamide, and stearamide, etc. The resulting mixture was melt-blended and extruded into granules to obtain a performance-enhanced biodegradable masterbatch. The obtained performance-enhanced biodegradable masterbatch was heated and melted by a blown film machine and blown into a film to obtain a performance-enhanced biodegradable film. The melt blending process is carried out in a twin-screw extruder. The temperature of the twin-screw extruder is 135~155℃ in zone 1, 145~165℃ in zone 2, 155~185℃ in zone 3, 155~185℃ in zone 4, and 155~185℃ in zone 5. The die head speed is 1000~2000 RPM. The blown film machine heats and melts the film before blowing it into a thin film. The screw speed of the blown film machine is 600-1000 RPM. The temperature of the first zone of the barrel is 135-155℃, the temperature of the second zone of the barrel is 155-185℃, the temperature of the third zone of the barrel is 155-185℃, and the temperature of the first zone of the die is 135-155℃. The traction speed is 350-450 RPM, and the winding speed is 350-450 RPM.

[0017] Beneficial effects of this invention: (1) This invention provides a method for preparing a performance-enhanced lightweight calcium carbonate filler. The microporous nano-aeration technology can effectively increase the contact area between CO2 and calcium hydroxide molecules, allowing them to fully carbonize. Combined with a crystal guiding agent, the calcium carbonate crystal structure becomes more regular. Furthermore, the ultrasonic technology combined with dispersants and activators is used to activate and modify the calcium carbonate, which can more comprehensively and uniformly coat the calcium carbonate particles, thereby achieving surface functionalization of lightweight calcium carbonate. This is an environmentally friendly, simple, and easily industrialized method.

[0018] (2) In this invention, performance-enhanced light calcium carbonate is used as a filler for biodegradable matrix materials. By utilizing the interfacial interaction and good affinity between functionalized light calcium carbonate and biodegradable matrix materials, the thermal stability, mechanical properties, aging resistance and electrical properties of biodegradable composite materials are effectively enhanced. The ultra-high filling amount of functionalized light calcium carbonate can also reduce the material cost of biodegradable matrix materials. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a scanning electron microscope image of the light calcium carbonate prepared in Example 1 of the present invention.

[0020] Figure 2 This is a transmission electron microscope image of the light calcium carbonate prepared in Example 1 of the present invention.

[0021] Figure 3 This is a water contact angle diagram of the light calcium carbonate prepared in Example 1 of the present invention. Detailed Implementation

[0022] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0023] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0024] The testing methods for D10, D50, and D90 in this invention are as follows: The testing instrument is a laser particle size analyzer, and the testing method is to use wet dispersion technology, mechanical stirring to make the sample evenly dispersed, ultrasonic high-frequency oscillation to fully disperse the agglomerated particles, and electromagnetic circulation pump to make the particles of different sizes evenly distributed in the entire circulation system. The particle size distribution reflects the quality stability of the product performance.

[0025] The testing methods for tensile strength and elongation at break in this invention are as follows: The thickness and width of the film sample should be measured at three points within the gauge length, and the arithmetic mean should be taken; the thickness should be accurate to 0.001 mm, and the width to 0.1 mm. The film should be cut into 10×150 mm samples in both the transverse and longitudinal directions. The samples should be placed in the two clamps of the testing machine, with the longitudinal axis of the sample coinciding with the line connecting the centers of the upper and lower clamps. The clamps should be properly tightened to prevent the samples from slipping or breaking within the clamps. The testing machine should be started at a tensile speed of 50 mm / min. After the sample breaks, the required load and the corresponding elongation between the gauges should be read.

[0026] The test conditions and test methods for the nominal fracture strain after aging for 100 hours in this invention are as follows: Samples of a certain size were cut from the thin film, ensuring that the size and shape of the samples were consistent. The prepared thin film samples were then placed in an aging chamber and exposed to ultraviolet light for 100 hours (where the ultraviolet light wavelength was 400-10nm and the ultraviolet radiation intensity was a narrow band (340nm) of 0.51W / (m²). 2 The film was subjected to ultraviolet radiation (nm) to simulate the effects of everyday exposure, and then mechanical property tests were performed on the film.

[0027] Example 1

[0028] This embodiment provides a method for preparing a performance-enhanced lightweight calcium carbonate filler and its application. The main steps are as follows: (1) In-situ carbonation preparation of functionalized light calcium carbonate: Quicklime was slaked with hot water (the ratio of quicklime to hot water was 1:8, and the hot water temperature was above 80℃). After standing at room temperature for 48 hours, the solution was passed through a 200-mesh sieve and the concentration of calcium hydroxide slurry was adjusted to 2 mol / L. The slurry was taken into the reactor and the stirring speed was set to 200 r / min. A mixture of CO2 and N2 gas was released in the form of microporous nano-aeration (microporous nano-aeration disc with a pore size of less than 2 μm) to allow it to undergo an in-situ carbonization reaction with the calcium hydroxide slurry. At the same time, a crystal-directing agent, glucose, was added to the slurry. The flow rate of the mixed gas was 2 L / min for CO2 and 4 L / min for N2. The amount of crystal-directing agent added accounted for 0.15% of the mass percentage of the slurry.

[0029] When the pH value of the slurry drops below 7, the carbonization reaction is stopped. After standing at room temperature for 16 hours, a second carbonization reaction is carried out. After standing and aging, the upper clear liquid and the concentrated slurry are extracted.

[0030] The concentrated slurry was transferred to an activation reactor. After the slurry temperature reached 70°C at a rotation speed of 1000 r / min, the dispersant polyvinylpyrrolidone (PVP-K30) and the compound activator (polyacrylate and palmitic acid in a mass ratio of 2:1) were added to the slurry. Ultrasonic treatment was then started (ultrasonic input power of 500 W, total input power of 1.3 kW, ultrasonic frequency of 40 kHz). After ultrasonic activation and modification treatment for 1 hour, the slurry was filtered, dried, pulverized and sieved to obtain functionalized light calcium carbonate powder. The compounded surfactant accounts for 3% of the slurry's mass, the dispersant accounts for 0.2% of the slurry's mass, the functionalized lightweight calcium carbonate powder has a particle size of 50-100 nm, and a water contact angle of 129.7°. ° This indicates that functionalized light calcium carbonate has excellent dispersibility and oleophilic-hydrophobic properties.

[0031] See the scanning electron microscope image of the prepared light calcium carbonate. Figure 1 The transmission electron microscope image of the prepared light calcium carbonate is shown in [reference]. Figure 2 ,from Figure 1 and Figure 2 As can be seen, the morphology of the light calcium carbonate is a regular cubic shape with a particle size between 50 and 100 nm. No agglomeration of calcium carbonate was observed, which clearly demonstrates the good dispersibility of the functionalized light calcium carbonate. The water contact angle diagram of the prepared light calcium carbonate is shown in the figure. Figure 3 As can be seen, its water contact angle is 129.7°. ° This indicates that calcium carbonate has been modified from hydrophilic to hydrophobic, improving the compatibility of functionalized light calcium carbonate with organic matrix materials, and further verifying the dispersibility of functionalized light calcium carbonate.

[0032] (2) Preparation of performance-enhanced functionalized lightweight calcium carbonate-filled biodegradable membranes: By weight percentage, PLA is 40 parts, PBAT is 30 parts, chain extender is 0.1 parts, lubricant is 0.1 parts, and functionalized light calcium carbonate is 30 parts; PLA, PBAT, chain extender, lubricant, and functionalized light calcium carbonate are prepared by weight percentage, and the raw materials are mixed evenly. The resulting mixture was melt-blended and extruded into granules to obtain a performance-enhanced biodegradable masterbatch. The obtained performance-enhanced biodegradable masterbatch was heated and melted by a blown film machine and blown into a film to obtain a performance-enhanced biodegradable film with a thickness of 0.01 mm. The melt blending process is carried out in a twin-screw extruder. The temperature of the twin-screw extruder is 135~155℃ in zone 1, 145~165℃ in zone 2, 155~185℃ in zone 3, 155~185℃ in zone 4, and 155~185℃ in zone 5. The die head speed is 1000~2000 RPM. The blown film machine heats and melts the film before blowing it into a thin film. The screw speed of the blown film machine is 600-1000 RPM. The temperature of the first zone of the barrel is 135-155℃, the temperature of the second zone of the barrel is 155-185℃, the temperature of the third zone of the barrel is 155-185℃, and the temperature of the first zone of the die is 135-155℃. The traction speed is 350-450 RPM, and the winding speed is 350-450 RPM.

[0033] Comparative Example 1

[0034] Under the conditions of Example 1, without adding a dispersant, and with other conditions the same as in Example 1, functionalized lightweight calcium carbonate powder was prepared. The particle size distribution of the powder was measured, as shown in Table 1.

[0035] Table 1

[0036] As can be seen from Table 1, when no dispersant is added, the particle size distribution of calcium carbonate particles is relatively wide, indicating that the quality stability of the obtained modified calcium carbonate product is poor.

[0037] Comparative Example 2

[0038] Under the conditions of Example 1, without adding ultrasonic treatment or dispersant, and with other conditions the same as in Example 1, functionalized lightweight calcium carbonate powder was prepared. The particle size distribution of the powder was measured, see Table 2.

[0039] Table 2

[0040] As can be seen from Table 2, when no dispersant is added and no ultrasonic treatment is performed, the particle size distribution of calcium carbonate particles is relatively wide, indicating that the quality stability of the obtained modified calcium carbonate product is poor.

[0041] Comparative Example 3

[0042] Under the conditions of Example 1, without adding ultrasonic treatment, dispersant, or activator, and with other conditions the same as in Example 1, functionalized lightweight calcium carbonate powder was prepared. The particle size distribution of the powder was measured, see Table 3.

[0043] Table 3

[0044] As can be seen from Table 3, when no dispersant, no ultrasonic treatment, and no activator are added, the particle size distribution of granular calcium carbonate is relatively wide, indicating that the quality stability of the obtained modified calcium carbonate product is poor.

[0045] Comparative Example 4

[0046] Under the conditions of Example 1, a thin film was prepared by filling a biodegradable matrix material with ordinary light calcium carbonate powder (purchased from Enping Yanyi New Materials Co., Ltd.); The test results are shown in Tables 4 and 5.

[0047] Table 4 Comparison of Mechanical Properties

[0048] Table 5 Comparison of Anti-aging Performance

[0049] As can be seen from Tables 4 and 5, the mechanical properties and anti-aging properties of the functionalized light calcium carbonate prepared in this invention and ordinary light calcium carbonate filled biodegradable biofilms were compared. The tensile strength was increased by about 18.5%, the elongation at break was increased by about 8.8%, and the nominal strain at break after aging for 100 hours was increased by about 14%. This indicates that the functionalized light calcium carbonate prepared in this invention enhances the mechanical properties and anti-aging properties of the biodegradable membrane.

[0050] Comparative Example 5

[0051] (1) In-situ carbonation preparation of functionalized light calcium carbonate: Quicklime was slaked with hot water (the ratio of quicklime to hot water was 1:8, and the hot water temperature was above 80℃). After standing at room temperature for 48 hours, the solution was passed through a 200-mesh sieve and the concentration of calcium hydroxide slurry was adjusted to 2 mol / L. A certain amount of slurry was added to the reactor, and the stirring speed was set to 200 r / min. CO2 and N2 mixed gas were released in the form of microporous nano-aeration (microporous nano-aeration disc with a pore size of less than 2 μm) to allow it to undergo in-situ carbonization reaction with the calcium hydroxide slurry. At the same time, glucose, a crystal-directing agent, was added to the slurry. The flow rate of the mixed gas was 2 L / min for CO2 and 4 L / min for N2. The amount of crystal-directing agent added accounted for 0.15% of the mass percentage of the slurry.

[0052] Once the pH value of the slurry drops below 7, the carbonization reaction is stopped. After standing at room temperature for 16 hours, a second carbonization reaction is carried out. After standing and aging, the upper clear liquid and the concentrated slurry are extracted.

[0053] The high-concentration slurry was transferred to an activation reactor. After the slurry temperature reached 70°C at a rotation speed of 1000 r / min, a compound activator (composed of polyacrylate and palmitic acid in a mass ratio of 2:1) was added to the slurry, and ultrasound was turned on (ultrasound input power of 500 W, total input power of 1.3 Kw, and ultrasound frequency of 40 KHz). After ultrasonic activation and modification treatment for 1 hour, the slurry was filtered, dried, pulverized, and sieved to obtain functionalized light calcium carbonate powder. The compound surfactant accounts for 3.2% of the mass percentage of the slurry.

[0054] (2) Preparation of performance-enhanced functionalized lightweight calcium carbonate-filled biodegradable membrane, same as in Example 1.

[0055] Table 6 Comparison of Mechanical Properties

[0056] Table 7 Comparison of Anti-aging Performance

[0057] As can be seen from Tables 6 and 7 above, filling biodegradable matrix materials with lightweight calcium carbonate powder without dispersants results in poor mechanical and anti-aging properties. The main reason for this is that calcium carbonate agglomerates in the biodegradable matrix materials, which reduces their mechanical and anti-aging properties.

[0058] Comparative Example 6

[0059] Under the conditions of Example 1, no compound activator was added to the calcium carbonate for modification, and other conditions were the same as in Example 1.

[0060] (1) In-situ carbonation preparation of functionalized light calcium carbonate: Quicklime was slaked with hot water (the ratio of quicklime to hot water was 1:8, and the hot water temperature was above 80℃). After standing at room temperature for 48 hours, the solution was passed through a 200-mesh sieve and the concentration of calcium hydroxide slurry was adjusted to 2 mol / L. The slurry was taken into the reactor and the stirring speed was set to 200 r / min. A mixture of CO2 and N2 gas was released in the form of microporous nano-aeration (microporous nano-aeration disc with a pore size of less than 2 μm) to allow it to undergo an in-situ carbonization reaction with the calcium hydroxide slurry. At the same time, a crystal-directing agent, glucose, was added to the slurry. The flow rate of the mixed gas was 2 L / min for CO2 and 4 L / min for N2. The amount of crystal-directing agent added accounted for 0.15% of the mass percentage of the slurry.

[0061] When the pH value of the slurry drops below 7, the carbonization reaction is stopped. After standing at room temperature for 16 hours, a second carbonization reaction is carried out. After standing and aging, the upper clear liquid and the concentrated slurry are extracted.

[0062] The concentrated slurry was transferred to an activation reactor. After the slurry temperature reached 70°C at a rotation speed of 1000 r / min, the dispersant polyvinylpyrrolidone (PVP-K30) was added to the slurry, and the ultrasonic process was started (ultrasonic input power of 500 W, total input power of 1.3 kW, ultrasonic frequency of 40 kHz). After ultrasonic activation and modification treatment for 1 hour, the slurry was filtered, dried, pulverized, and sieved to obtain functionalized light calcium carbonate powder. The dispersant accounts for 3.2% of the mass of the slurry.

[0063] (2) Preparation of performance-enhanced functionalized lightweight calcium carbonate-filled biodegradable membrane, same as in Example 1.

[0064] Table 8 Comparison of Mechanical Properties

[0065] Table 9 Comparison of Anti-aging Performance

[0066] As can be seen from Tables 8 and 9 above, the mechanical properties and anti-aging properties of films prepared by filling calcium carbonate powder without adding compound surfactants into biodegradable matrix materials are not good. The main reason is that the hydrophilic end of the calcium carbonate was not modified into the hydrophobic end, resulting in poor compatibility and dispersibility with the biodegradable matrix material.

[0067] Comparative Example 7

[0068] Under the conditions of Example 1, a single active agent, sodium polyacrylate, was added to the calcium carbonate slurry, while other conditions remained the same as in Example 1.

[0069] Table 10 Comparison of Mechanical Properties

[0070] Table 11 Comparison of Anti-aging Performance

[0071] As can be seen from Tables 10 and 11 above, the mechanical properties and anti-aging properties of the film prepared by filling the biodegradable matrix material with calcium carbonate powder containing only a single surfactant (sodium polyacrylate) are slightly worse than those of Example 1. The main reason is that the single surfactant does not completely coat the calcium carbonate, so that hydrophilic calcium carbonate still exists, resulting in slightly poor compatibility and dispersion of light calcium carbonate in the film.

[0072] Comparative Example 8

[0073] Under the conditions of Example 1, a single active agent, palmitic acid, was added to the calcium carbonate slurry, while other conditions remained the same as in Example 1.

[0074] Table 12 Comparison of Mechanical Properties

[0075] Table 13 Comparison of Anti-aging Performance

[0076] As can be seen from Tables 12 and 13, the mechanical properties and anti-aging properties of the film prepared by filling the biodegradable matrix material with calcium carbonate powder containing only a single surfactant (palmitic acid) are slightly worse than those of Example 1, which is consistent with the results of Comparative Example 7. This further verifies that calcium carbonate modified with a single surfactant cannot achieve complete coating.

[0077] This invention utilizes microporous nano-aeration technology combined with a crystal-directing agent to conduct an in-situ carbonization reaction to obtain calcium carbonate with a regular crystal structure. Then, ultrasonic technology combined with dispersants and compound activators is used to reactivate the calcium carbonate, resulting in a performance-enhanced lightweight calcium carbonate material. The regularity of the lightweight calcium carbonate crystal structure makes its surface-coated functional layer more comprehensive and uniform, effectively improving its dispersibility and dispersion stability in the polymer matrix, as well as its chemical affinity with the polymer, thereby increasing its compatibility with polymers and elevating it from a general "incremental" filler to a "performance-enhanced" filler. Using functionalized lightweight calcium carbonate as a filler in a biodegradable matrix material can effectively improve the thermal stability, mechanical properties, aging resistance, and electrical properties of biodegradable membrane materials, while the ultra-high filler content can reduce the material cost of biodegradable film materials.

[0078] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A process for the preparation of a performance-enhanced light calcium carbonate filler, characterized in that: include, Quicklime is reacted with hot water to undergo a digestion reaction, then allowed to stand at room temperature for aging and is sieved to obtain calcium hydroxide slurry. Add calcium hydroxide slurry to the reaction vessel and stir. Release a mixture of CO2 and N2 gas into the reaction vessel in the form of microporous nano-aeration to allow it to undergo an in-situ carbonization reaction with the calcium hydroxide slurry. At the same time, add a crystal-directing agent to the slurry. When the pH value of the reaction slurry drops to 6.5~7, stop the carbonization reaction. After standing and aging at room temperature, carry out a second carbonization reaction. After standing and aging, extract the upper clear liquid to obtain a highly concentrated slurry. The highly concentrated slurry is transferred to an activation reactor. Under stirring conditions, the slurry temperature rises to 60-90℃. Then, a dispersant and a compound activator are added to the slurry. After ultrasonic activation and modification treatment for 1-3 hours, the slurry is filtered, dried, pulverized, and sieved to obtain functionalized light calcium carbonate powder.

2. The production method according to claim 1, characterized by: The process involves reacting quicklime with hot water to induce a digestion reaction, wherein the mass ratio of quicklime to hot water is 1:6~8, and the hot water temperature is 80~100℃.

3. The production method according to claim 1, wherein: The static room temperature aging and sieving process involves aging for 24-72 hours and sieving through a 200-mesh sieve.

4. The production method according to claim 1, wherein: The calcium hydroxide slurry has a molar concentration of 1~3 mol / L.

5. The preparation method according to claim 1, characterized in that: The process involves releasing a mixture of CO2 and N2 gas into the reactor in the form of microporous nano-aeration, which then reacts with the calcium hydroxide slurry in situ to carry out an in-situ carbonization reaction. The pore size of the microporous nano-aeration pores is less than 2 μm, and the flow rate of the mixed gas is 1~2 L / min for CO2 and 2~4 L / min for N2.

6. The production method according to any one of claims 1 to 4, characterized by: The crystal-directing agent includes any one of sucrose, glucose, sorbitol, citric acid and chitosan, and the crystal-directing agent accounts for 0.1~0.5% of the slurry by mass.

7. The production method according to claim 1, wherein: The dispersant is any one of polyvinylpyrrolidone, polysorbate-80, alkyl glycoside, and disodium lauroyl amphoteric diacetate, and the compound activator is any combination of several of sodium polyacrylate, sodium stearate, lauric acid, palmitic acid, sodium dodecylbenzene sulfonate, and silane coupling agent.

8. The production method according to any one of claims 1 or 7, characterized by: The compounded activator accounts for 1-5% of the mass of the slurry, and the dispersant accounts for 0.5-2% of the mass of the slurry.

9. The functionalized light calcium carbonate powder prepared by the method of any one of claims 1 to 8, characterized in that: The functionalized light calcium carbonate powder has a particle size of 50-100 nm and a water contact angle of 129.7 ° .

10. Use of the functionalized light calcium carbonate powder according to claim 9 for the production of biodegradable films, characterized in that: include, By weight, PLA is 30-40 parts, PBAT is 20-30 parts, chain extender is 0.1-0.2 parts, lubricant is 0.1-0.2 parts, and functionalized light calcium carbonate is 20-40 parts; PLA, PBAT, chain extender, lubricant, and functionalized light calcium carbonate are prepared separately, and the raw materials are mixed evenly. The chain extender is an amine compound; the lubricant is any one of erucamide, oleamide, and stearamide. The resulting mixture was melt-blended and extruded into granules to obtain a performance-enhanced biodegradable masterbatch. The obtained performance-enhanced biodegradable masterbatch was heated and melted by a blown film machine and blown into a film to obtain a performance-enhanced biodegradable film. The melt blending process is carried out in a twin-screw extruder. The temperature of the twin-screw extruder is 135~155℃ in zone 1, 145~165℃ in zone 2, 155~185℃ in zone 3, 155~185℃ in zone 4, and 155~185℃ in zone 5. The die head speed is 1000~2000 RPM. The blown film machine heats and melts the film before blowing it into a thin film. The screw speed of the blown film machine is 600-1000 RPM. The temperature of the first zone of the barrel is 135-155℃, the temperature of the second zone of the barrel is 155-185℃, the temperature of the third zone of the barrel is 155-185℃, and the temperature of the first zone of the die is 135-155℃. The traction speed is 350-450 RPM, and the winding speed is 350-450 RPM.

Images