Black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent as well as preparation method and application thereof

Abstract

The invention relates to the field of nylon 6 nucleating agents, and particularly discloses a black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent which is obtained by modifying black phosphorus crystals with organic phosphoric acid basic metal salt. The black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent is of a lamellar structure, the average thickness ranges from 2.2 nm to 2.9 nm, and the average number of layers ranges from 4 to 5; when the use amount of the prepared black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent in nylon 6 is 0.2 wt%, the tensile strength of the nylon 6 can be improved by 30.7%, the bending strength of the nylon 6 can be improved by 22.3%, meanwhile, the notch impact strength of the nylon 6 is good, the hardness of the nylon 6 can be improved, and the nylon 6 can be widely applied to the field of nylon 6. The nucleating agent has a good application prospect as a high-efficiency nucleating agent in the field of nylon resin.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer material modification, and in particular to an organic phosphoric acid basic metal salt modified black phosphorus nanosheet composite nucleating agent, a preparation method thereof, and application of the composite nucleating agent as a high-efficiency nucleating agent in nylon 6. Background Art

[0002] As an important engineering plastic, nylon 6 (PA6) is widely used in the fields of automobiles, electronics, machinery, etc. due to its excellent mechanical strength, wear resistance and chemical stability. However, the crystallization rate of PA6 is slow and the injection molding cycle is long. The addition of nucleating agents can effectively improve the crystallization performance of PA6, while enhancing its mechanical properties and thermal stability. Although inorganic nucleating agents such as montmorillonite, kaolin, talc, ZnO, etc. are cheap and can theoretically continue to improve the crystallization rate of PA6 as the amount added increases, these substances actually mainly play the role of fillers, and excessive addition will cause serious agglomeration, which will cause the crystallization performance of PA6 to deteriorate and the toughness to decrease. Organic nucleating agents have the characteristics of good compatibility with PA6 and strong nucleating ability, but their effect on improving the mechanical properties of materials still has certain limitations. Excessive introduction will destroy the rigidity and toughness balance of PA6. Generally, with the increase of the amount of organic nucleating agent added, the tensile strength of PA6 is improved, but this improvement is at the expense of its impact strength. This trade-off relationship limits the widespread use of organic nucleating agents to a certain extent. Xiao Guowen (Effect of nucleating agent on injection molding and performance of nylon 6, Synthetic Fiber Industry, 2020, 43(06): 44-47.) used organic nucleating agents N22 and DN for PA6 and found that when their addition amount was 0.2%, the tensile strength of pure PA6 increased from 66.3MPa to 74.9MPa and 77.1MPa respectively; however, the notched impact strength decreased from 10.2kJ / m 2 Reduced to 8.1 kJ / m 2 and 8.7 kJ / m 2 . Organic-inorganic nucleating agent composites can combine the advantages of both and improve the mechanical properties and heat deformation temperature of PA6. Nucleating agent P22 is a mixture of organic and inorganic components. Liu Shi et al. (Effects of different nucleating agents on the crystallization behavior and mechanical properties of chain-extended toughened PA6, Engineering Plastics Applications, 2021, 49(09): 103-108.) After adding nucleating agent P22 to PA6, the tensile strength, flexural strength and flexural elastic modulus increased by 10.5%, 10.1% and 13.2% respectively, and the heat deformation temperature increased by 8°C, but the notched impact strength decreased by 56.2%. In summary, the application effect of nucleating agents still needs to be further improved.

[0003] Therefore, in view of the above problems, it is necessary to develop a nucleating agent for PA6 and its preparation method. After adding this nucleating agent, the nucleating performance of PA6 can be improved while obtaining a PA6 composite material with good rigidity and toughness. Summary of the Invention

[0004] Based on the defects existing in the above-mentioned prior art, the purpose of the present invention is to provide a composite nucleating agent for PA6, aiming to solve the technical problems that the nucleating agents used in existing PA6 cannot achieve the improvement of nucleating performance and the simultaneous maintenance of rigidity and toughness.

[0005] Specifically, an object of the present invention is to provide a black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent and its preparation method. When the dosage of this nucleating agent is as low as 0.2 wt%, it has excellent nucleating performance for PA6. It can not only effectively promote the rapid crystallization of PA6, and has a good injection molding and demolding effect, but also has a reinforcing effect and improves the rigidity of PA6.

[0006] Another object of the present invention is to provide the application of the black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent in the preparation of PA6 composite materials with high rigidity and good toughness.

[0007] The layered structure of the black phosphorus (BP) nanosheets is formed by phosphorus atoms through sp 3 hybridization to form a triangular pyramid structure, and stacked by van der Waals forces. This structure endows BP nanosheets with excellent physical and chemical properties. As a new type of two-dimensional nanomaterial, due to its unique layered structure and high specific surface area, it is used as a reinforcing modifier in polymer materials to improve the mechanical properties of materials to a certain extent. For BP nanosheets, after the phosphorus atoms form chemical bonds with other three phosphorus atoms, there is still a pair of free lone pair electrons, which are relatively active and easily taken away by oxygen molecules, resulting in the oxidation of the outer phosphorus atoms. In addition, in a humid or water-containing environment, the phosphorus oxide generated by the oxidation on the surface of BP nanosheets will quickly react with water molecules, causing the P-P bond to break, generating various phosphoric acids and degrading. The exposed BP inside is further oxidized and damaged and degraded. BP nanosheets are not easy to be stored for a long time and stably applied because they are easily oxidized and degraded in the environment, resulting in the destruction of the sheet structure. This greatly limits its application, especially the reduced structural stability and material service life, bringing many limitations and adverse effects to the large-scale preparation, long-term stable storage and wide practical application of BP nanosheets. The surface of BP nanosheets has no active groups, is chemically inert, and is prone to agglomeration. Surface modification is required for the modification of polymer materials. The surface modification method can also eliminate the lone pair electrons, thereby reducing the active chemical properties of BP nanosheets and improving the air stability of BP nanosheets.

[0008] When black phosphorus (BP) nanosheets prepared by an electrochemical method are added to epoxy resin (Ce L., Xuemei C., Xing G., et al. Electrochemically prepared black phosphorene micro-powder as flame retardant for epoxy resin[J]. Composite Interfaces, 2020, 28(7): 693 - 705.), the mechanical properties of the epoxy resin are improved with the increase of the dosage. For example, when 0.2% is added, the flexural strength and flexural modulus of the composite material reach more than twice those without addition. As a thermosetting polymer material, the core of the processing process of epoxy resin lies in the curing reaction. In this process, epoxy resin starts from a liquid or semi-solid state and gradually transforms into a hard solid structure by heating or adding a curing agent. This characteristic enables the convenient addition of BP nanosheets when the epoxy resin is in the liquid phase. Since the epoxy resin has good fluidity at this time, the BP nanosheets can be more evenly dispersed in the resin matrix, thus significantly improving the mechanical properties and thermal stability of the composite material after curing, and the enhancement effect is very excellent. In contrast, PA6 belongs to a thermoplastic polymer, and its processing process is mainly melt processing. The processing time in the molten state is relatively short, which limits the mixing time of BP nanosheets and the PA6 matrix. Due to insufficient mixing time, the BP nanosheets are difficult to be fully dispersed in the nylon 6 matrix, resulting in poor dispersion, which in turn affects the final performance of the composite material. This dispersion problem to a certain extent limits the application effect of BP nanosheets in PA6 composites. It is necessary to further optimize the processing technology or adopt other methods to improve the dispersion of BP nanosheets in PA6 to fully exert its reinforcing effect. However, there are relatively few reports on modifying and decorating BP nanosheets specifically with PA6 as the matrix material, and the research on the dispersion performance and interfacial bonding performance of BP nanosheets in PA6 is still relatively weak.

[0009] The object of the present invention is achieved through the following technical solutions:

[0010] In the first aspect, a black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent is provided, and the black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent is obtained by modifying black phosphorus crystals with an organic phosphoric acid basic metal salt;

[0011] Preferably, the black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent has a lamellar structure, with an average thickness of 2.2 nm to 2.9 nm and an average number of layers of 4 - 5 layers;

[0012] Preferably, the mass ratio of the black phosphorus crystals to the organic phosphoric acid basic metal salt is 1:(1 - 10);

[0013] Preferably, the basic metal salt of organic phosphoric acid is selected from one or more of basic sodium salt of organic phosphoric acid, basic aluminum salt of organic phosphoric acid, and basic zinc salt of organic phosphoric acid;

[0014] More preferably, the basic metal salt of organic phosphoric acid is selected from one or more of sodium 2,2′-methylenebis(4,6-di-tert-butylphenyl)phosphate, aluminum 2,2′-methylenebis(4,6-di-tert-butylphenyl)phosphate, and zinc bis(2,4-di-tert-butylphenyl)phosphate;

[0015] Preferably, the black phosphorus crystal is a bulk black phosphorus crystal.

[0016] In a second aspect, a method for preparing a black phosphorus nanosheet / basic metal salt of organic phosphoric acid composite nucleating agent is provided, which is prepared by a ball milling exfoliation method, and specifically includes the following preparation steps:

[0017] S1. Grind the black phosphorus crystal into black phosphorus powder, and then ball mill the black phosphorus powder, the basic metal salt of organic phosphoric acid, and the ball milling beads in a protective gas atmosphere;

[0018] S2. After the ball milling process ends, cool to room temperature, then remove the ball milling beads by sieving, and then wash, centrifuge, and dry to obtain the black phosphorus nanosheet / basic metal salt of organic phosphoric acid composite nucleating agent.

[0019] Preferably, the mass ratio of the black phosphorus crystal to the ball milling beads is 1:(40-100);

[0020] Preferably, the ball milling beads are stainless steel balls;

[0021] More preferably, the diameter of the ball milling beads is 1-10 mm;

[0022] More preferably, the ball milling beads are a compound of stainless steel balls with a diameter ratio of 1:(3-6), and the compounding ratio is 1:(1-3);

[0023] Preferably, the protective gas is helium, argon, or nitrogen;

[0024] Preferably, the ball milling process is: the ball milling speed is 300-500 r / min, the ball milling time is 24-48 h, and it pauses for 5-10 min every 30 min of ball milling;

[0025] Preferably, the washing method is suction filtration washing or centrifugal washing, and the washing solvent is anhydrous ethanol; the number of suction filtration washing times is 1-5 times; centrifugal washing is to wash the product and then centrifuge, and this process lasts for 3-5 times; the centrifugal condition is that the centrifugal speed is 10000-12000 r / min, and the single centrifugal time is 10-15 min;

[0026] Preferably, the drying is vacuum drying, the drying temperature is 70-100 °C, and the drying time is 6-8 h.

[0027] In a third aspect, there is provided an application of the black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent in the preparation of a high-rigidity and good-toughness nylon 6 composite material.

[0028] Preferably, the added mass concentration of the black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent in the nylon 6 composite material is 0.05%-0.3%.

[0029] In a fourth aspect, there is provided a black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent modified nylon 6 composite material, which comprises the following components in parts by weight: 99.7-99.95 parts of nylon 6 resin; 0.05-0.3 part of the black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent.

[0030] In a fifth aspect, there is provided a preparation method of a black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent modified nylon 6 material, which comprises the following steps:

[0031] (1) Mix the nylon 6 resin and the black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent evenly;

[0032] (2) Place it into an extruder for melt extrusion granulation to obtain the black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent modified nylon 6 composite material.

[0033] The beneficial effects of the present invention are as follows:

[0034] (1) The present invention creatively uses black phosphorus nanosheets as nucleating agents in nylon 6 composite materials. Based on the characteristics of easy aggregation and instability of black phosphorus nanosheets, organic phosphoric acid basic metal salts are creatively used to modify the surface of BP nanosheets and used to modify nylon 6. By means of co-ball milling of black phosphorus crystals and organic phosphoric acid basic metal salts, organic phosphoric acid basic metal salts with a specific structure are introduced onto the surface of BP nanosheets. The stability of such BP nanosheets is improved, and the surface contains rich polar groups. These groups interact with the amide groups, terminal carboxyl groups or terminal amino groups of nylon 6 and are connected to some nylon 6 molecules, improving the compatibility with nylon 6 and improving the dispersion effect. At the same time, the heterogeneous nucleation activity of BP nanosheets effectively improves the crystallization performance of nylon 6 resin molecules, increases the probability of grain collision and reduces the grain size, and finally increases the crystallization temperature of nylon 6. Moreover, the BP nanosheets modified with organic phosphoric acid basic metal salts have high strength. When introduced into nylon 6, they have a reinforcing effect, can improve the rigidity of nylon 6, and because of their good dispersion in the matrix, the toughness will not be overly sacrificed.

[0035] (2) The present invention creatively uses the ball milling method which is easy to industrialize to obtain the organophosphoric acid basic metal salt modified BP nanosheets in one step. The organophosphoric acid basic metal salt is creatively added during the ball milling process to achieve the modification of BP nanosheets while exfoliating BP. The exfoliation and modification are completed in one step. The preparation method is simple, easy to implement, has good repeatability, and has good prospects for industrial production and application.

[0036] (3) The BP nanosheet / organophosphoric acid basic metal salt composite nucleating agent prepared by the present invention is easily and uniformly dispersed in the nylon 6 matrix and has a high nucleation efficiency. When the dosage is as low as 0.2 wt%, it can significantly increase the crystallization temperature of nylon 6 and shorten the molding cycle.

[0037] (4) The BP nanosheet / organophosphoric acid basic metal salt composite nucleating agent prepared by the present invention has a certain strengthening effect. When the dosage is 0.2 wt%, it can increase the tensile strength of nylon 6 by 30.7% and the flexural strength by 22.3%, and at the same time, the notched impact strength is good. Description of the Drawings

[0038] Figure 1 It is the transmission electron microscope image of NBP-1 in Example 1 of the present invention;

[0039] Figure 2 It is the Raman spectrum of NBP-1 and BP crystal blocks prepared in Example 1. Detailed Embodiments

[0040] To better understand the present invention, the following further illustrates the present invention in conjunction with specific embodiments. These embodiments are only used to illustrate the technical solutions and effects of the present invention, and do not limit the protection scope of the present invention.

[0041] The PA6 of industrial grade with the brand of M2400 from Guangdong Xinhui Meida Nylon Co., Ltd. is used in each embodiment and comparative example of the present invention; BP is provided by Kunming Black Phosphorus Technology Co., Ltd. (China); the ball mill selects the product of Nanjing Nanda Instrument Co., Ltd. (model QM-DK2).

[0042] Example 1:

[0043] (1) Weigh 2 g of BP crystal blocks and grind them in a glove box for 60 min. Then, in the glove box under a nitrogen atmosphere, mix them with 10 g of bis(4,6-di-tert-butylphenyl) phosphite aluminum (Asahi Denka Co., Ltd., Japan), 40 g of stainless steel ball milling beads with a diameter of 1 mm and 40 g of stainless steel ball milling beads with a diameter of 4 mm, and encapsulate them in a 200 mL ball milling tank. Place the ball milling tank in a ball mill for ball milling; set the ball milling speed to 300 r / min, pause for 5 min every 30 min of rotation, and the total ball milling time is 48 h; after the ball milling is completed, cool it to room temperature, and remove the ball milling beads by sieving to obtain a mixture;

[0044] (2) Transfer the mixture obtained in step (1) to a 500 mL beaker, add 200 mL of absolute ethanol for washing; place it in a centrifuge and centrifuge at a speed of 5000 r / min for 10 min, pour off the upper layer solution, and repeat the washing and centrifugation of the precipitate 3 times; place the obtained precipitate in a vacuum oven at 70 °C and dry for 6 h to obtain a grayish-black powder, which is the BP nanosheet / alkaline metal salt of organic phosphoric acid composite nucleating agent, named NBP-1; during the whole ball milling and washing process, wrap the container with black cloth to avoid the influence of light on the performance of the nanosheets. After testing, the average thickness of NBP-1 is 2.3 nm and the average number of layers is 4 layers.

[0045] Example 2:

[0046] (1) Weigh 2 g of BP crystal blocks, grind them in a glove box for 60 min, then encapsulate them with 15 g of sodium 2,2′-methylenebis(4,6-di-tert-butylphenyl) phosphate (Shanghai Aladdin Biochemical Technology Co., Ltd.), 40 g of stainless steel ball milling beads with a diameter of 1 mm and 40 g of stainless steel ball milling beads with a diameter of 4 mm in a glove box under a nitrogen atmosphere in a 200 mL ball milling jar, and place it in a ball mill for ball milling; set the ball milling speed to 350 r / min, pause for 10 min every 30 min of rotation, and the total ball milling time is 36 h; after the ball milling is completed, cool it to room temperature, and remove the ball milling beads by sieving to obtain a mixture.

[0047] (2) Transfer the mixture obtained in step (1) to a 500 mL beaker, add 250 mL of absolute ethanol for washing; place it in a centrifuge and centrifuge at a speed of 6000 r / min for 15 min, pour off the upper layer solution, and repeat the washing and centrifugation of the precipitate 3 times; place the obtained precipitate in a vacuum oven at 80 °C and dry for 7 h to obtain a grayish-black powder, which is the BP nanosheet / alkaline metal salt of organic phosphoric acid composite nucleating agent, named NBP-2; during the whole ball milling and washing process, wrap the container with tin foil to avoid the influence of light on the performance of the nanosheets. After testing, the average thickness of NBP-2 is 2.9 nm and the average number of layers is 5 layers.

[0048] Example 3:

[0049] (1) Weigh 2 g of BP crystal blocks, grind them in a glove box for 60 min, then encapsulate them with 20 g of aluminum 2,2′-methylenebis(4,6-di-tert-butylphenyl) phosphate (Asahi Denka Co., Ltd., Japan), 40 g of stainless steel ball milling beads with a diameter of 1 mm and 40 g of stainless steel ball milling beads with a diameter of 4 mm in a glove box under a nitrogen atmosphere in a 200 mL ball milling jar, and place it in a ball mill for ball milling; set the ball milling speed to 300 r / min, pause for 5 min every 30 min of rotation, and the total ball milling time is 48 h; after the ball milling is completed, cool it to room temperature, and remove the ball milling beads by sieving to obtain a mixture;

[0050] (2) Transfer the mixture obtained in step (1) to a 500 mL beaker, add 200 mL of absolute ethanol for washing; place it in a centrifuge and centrifuge at a speed of 5000 r / min for 10 min, pour off the upper layer solution, and repeat the washing and centrifugation of the precipitate 3 times; place the obtained precipitate in a vacuum oven at 70 °C and dry it for 6 h to obtain a grayish-black powder, which is the BP nanosheet / organic phosphoric acid basic metal salt composite nucleating agent, named NBP-3; during the whole ball milling and washing process, wrap the container with black cloth to avoid the influence of light on the performance of the nanosheets. After testing, the average thickness of NBP-3 is 2.4 nm and the average number of layers is 4 layers.

[0051] Example 4:

[0052] (1) Weigh 2 g of BP crystal blocks, grind them in a glove box for 60 min, then encapsulate them with 10 g of 2,2′-methylenebis(4,6-di-tert-butylphenyl) aluminum phosphate (Asahi Denka Co., Ltd., Japan), 40 g of stainless steel ball milling beads with a diameter of 1 mm and 40 g of stainless steel ball milling beads with a diameter of 3 mm in a glove box under a nitrogen atmosphere in a 200 mL ball milling tank, and place it in a ball mill for ball milling; set the ball milling speed to 300 r / min, pause for 5 min every 30 min of rotation, and the total ball milling time is 48 h; after the ball milling is completed, cool it to room temperature, and remove the ball milling beads by sieving to obtain a mixture;

[0053] (2) Transfer the mixture obtained in step (1) to a 500 mL beaker, add 200 mL of absolute ethanol for washing; place it in a centrifuge and centrifuge at a speed of 5000 r / min for 10 min, pour off the upper layer solution, and repeat the washing and centrifugation of the precipitate 3 times; place the obtained precipitate in a vacuum oven at 70 °C and dry it for 6 h to obtain a grayish-black powder, which is the BP nanosheet / organic phosphoric acid basic metal salt composite nucleating agent, named NBP-4; during the whole ball milling and washing process, wrap the container with black cloth to avoid the influence of light on the performance of the nanosheets. After testing, the average thickness of NBP-4 is 2.8 nm and the average number of layers is 5 layers.

[0054] Example 5:

[0055] (1) Weigh 2 g of BP crystal blocks, grind them in a glove box for 60 min, then encapsulate them with 10 g of 2,2′-methylenebis(4,6-di-tert-butylphenyl) aluminum phosphate (Asahi Denka Co., Ltd., Japan), 20 g of stainless steel ball milling beads with a diameter of 1 mm and 60 g of stainless steel ball milling beads with a diameter of 4 mm in a glove box under a nitrogen atmosphere in a 200 mL ball milling tank, and place it in a ball mill for ball milling; set the ball milling speed to 300 r / min, pause for 5 min every 30 min of rotation, and the total ball milling time is 48 h; after the ball milling is completed, cool it to room temperature, and remove the ball milling beads by sieving to obtain a mixture;

[0056] (2) Transfer the mixture obtained in step (1) to a 500 mL beaker, add 200 mL of absolute ethanol for washing; place it in a centrifuge and centrifuge at a speed of 5000 r / min for 10 min, pour off the upper layer solution, and repeat the washing and centrifugation of the precipitate 3 times; place the obtained precipitate in a vacuum oven at 70 °C and dry for 6 h to obtain a grayish-black powder, which is the BP nanosheet / organic phosphoric acid basic metal salt composite nucleating agent, named NBP-5; during the whole ball milling and washing process, wrap the container with black cloth to avoid the influence of light on the performance of the nanosheets. After testing, the average thickness of NBP-5 is 2.9 nm and the average number of layers is 5 layers.

[0057] Example 6:

[0058] (1) Weigh 2 g of BP crystal blocks, grind them in a glove box for 60 min, then encapsulate them with 10 g of 2,2′-methylenebis(4,6-di-tert-butylphenyl) aluminum phosphate (Asahi Denka Co., Ltd., Japan), 50 g of stainless steel ball milling beads with a diameter of 1 mm and 50 g of stainless steel ball milling beads with a diameter of 4 mm in a glove box under a nitrogen atmosphere in a 200 mL ball milling jar, and place it in a ball mill for ball milling; set the ball milling speed to 300 r / min, pause for 5 min every 30 min of rotation, and the total ball milling time is 48 h; after the ball milling is completed, cool to room temperature, and remove the ball milling beads by sieving to obtain a mixture;

[0059] (2) Transfer the mixture obtained in step (1) to a 500 mL beaker, add 200 mL of absolute ethanol for washing; place it in a centrifuge and centrifuge at a speed of 5000 r / min for 10 min, pour off the upper layer solution, and repeat the washing and centrifugation of the precipitate 3 times; place the obtained precipitate in a vacuum oven at 70 °C and dry for 6 h to obtain a grayish-black powder, which is the BP nanosheet / organic phosphoric acid basic metal salt composite nucleating agent, named NBP-6; during the whole ball milling and washing process, wrap the container with black cloth to avoid the influence of light on the performance of the nanosheets. After testing, the average thickness of NBP-6 is 2.8 nm and the average number of layers is 5 layers.

[0060] Comparative Example 1

[0061] (1) Weigh 2 g of BP crystal blocks, grind them in a glove box for 60 min, then encapsulate them with 21 g of 2,2′-methylenebis(4,6-di-tert-butylphenyl) aluminum phosphate (Asahi Denka Co., Ltd., Japan), 40 g of stainless steel ball milling beads with a diameter of 1 mm and 40 g of stainless steel ball milling beads with a diameter of 4 mm in a glove box under a nitrogen atmosphere in a 200 mL ball milling jar, and place it in a ball mill for ball milling; set the ball milling speed to 300 r / min, pause for 5 min every 30 min of rotation, and the total ball milling time is 48 h; after the ball milling is completed, cool to room temperature, and remove the ball milling beads by sieving to obtain a mixture;

[0062] (2) Transfer the mixture obtained in step (1) to a 500 mL beaker, add 200 mL of anhydrous ethanol for washing; place it in a centrifuge and centrifuge at a speed of 5000 r / min for 10 min, pour off the upper layer solution, and repeat the washing and centrifugation of the precipitate 3 times; place the obtained precipitate in a vacuum oven at 70 °C for drying for 6 h to obtain a grayish-black powder, which is the BP nanosheet / alkaline metal salt of organophosphoric acid composite nucleating agent, named NBP-C1; during the whole ball milling and washing process, wrap the container with black cloth to avoid the influence of light on the performance of the nanosheets. After testing, the average thickness of NBP-C1 is 3.1 nm and the average number of layers is 6 layers.

[0063] Comparative Example 2

[0064] (1) Weigh 2 g of BP crystal blocks, grind them in a glove box for 60 min, then encapsulate them with 10 g of aluminum bis(4,6-di-tert-butylphenyl) phosphate (Asahi Denka Co., Ltd., Japan), 20 g of stainless steel ball milling beads with a diameter of 1 mm and 20 g of stainless steel ball milling beads with a diameter of 4 mm in a glove box under a nitrogen atmosphere in a 200 mL ball milling jar, and place it in a ball mill for ball milling; set the ball milling speed to 300 r / min, pause for 5 min every 30 min of rotation, and the total ball milling time is 48 h; after the ball milling is completed, cool to room temperature, and remove the ball milling beads by sieving to obtain a mixture;

[0065] (2) Transfer the mixture obtained in step (1) to a 500 mL beaker, add 200 mL of anhydrous ethanol for washing; place it in a centrifuge and centrifuge at a speed of 5000 r / min for 10 min, pour off the upper layer solution, and repeat the washing and centrifugation of the precipitate 3 times; place the obtained precipitate in a vacuum oven at 70 °C for drying for 6 h to obtain a grayish-black powder, which is the BP nanosheet / alkaline metal salt of organophosphoric acid composite nucleating agent, named NBP-C2; during the whole ball milling and washing process, wrap the container with black cloth to avoid the influence of light on the performance of the nanosheets. After testing, the average thickness of NBP-C2 is 3.6 nm and the average number of layers is 7 layers.

[0066] Comparative Example 3

[0067] Weigh 2 g of BP crystal blocks, grind them in a glove box for 60 min, then encapsulate them with 40 g of stainless steel ball milling beads with a diameter of 1 mm and 40 g of stainless steel ball milling beads with a diameter of 4 mm in a glove box under a nitrogen atmosphere in a 200 mL ball milling jar, and place it in a ball mill for ball milling; set the ball milling speed to 300 r / min, pause for 5 min every 30 min of rotation, and the total ball milling time is 48 h; after the ball milling is completed, cool to room temperature, and remove the ball milling beads by sieving to obtain BP nanosheets. After testing, the average thickness of the BP nanosheets is 5.2 nm and the average number of layers is 10 layers.

[0068] Application Example 1

[0069] Weigh 99.95 g of PA6 resin (PA6) and 0.05 g of NBP-1 prepared in Example 1 and add them to a high-speed mixer, and stir at a speed of 300 r / min for 5 min; then add them to a twin-screw extruder, set the melting extrusion temperature to 230-250 °C, and the screw speed to 75-100 r / min; after extrusion, cooling, and pelletizing, a PA6 composite material is obtained.

[0070] Application Example 2

[0071] Weigh 99.9 g of PA6 resin (PA6) and 0.1 g of NBP-1 prepared in Example 1 above and add them to a high-speed mixer, and stir at a speed of 350 r / min for 4 min; then add them to a twin-screw extruder, set the melting extrusion temperature to 230-250 °C, and the screw speed to 75-100 r / min; after extrusion, cooling, and pelletizing, a PA6 composite material is obtained.

[0072] Application Example 3

[0073] Weigh 99.8 g of PA6 resin (PA6) and 0.2 g of NBP-1 prepared in Example 1 above and add them to a high-speed mixer, and stir at a speed of 350 r / min for 4 min; then add them to a twin-screw extruder, set the melting extrusion temperature to 230-250 °C, and the screw speed to 75-100 r / min; after extrusion, cooling, and pelletizing, a PA6 composite material is obtained.

[0074] Application Example 4

[0075] Weigh 99.8 g of PA6 resin (PA6) and 0.3 g of NBP-1 prepared in Example 1 above and add them to a high-speed mixer, and stir at a speed of 350 r / min for 4 min; then add them to a twin-screw extruder, set the melting extrusion temperature to 230-250 °C, and the screw speed to 75-100 r / min; after extrusion, cooling, and pelletizing, a PA6 composite material is obtained.

[0076] Application Examples 5-9

[0077] Weigh 99.8 g of PA6 resin (PA6) and 0.2 g of NBP-2-NBP-6 prepared in Examples 2-6 above and add them to a high-speed mixer, and keep the others the same as in Application Example 3 to obtain a PA6 composite material.

[0078] Application Comparative Example 1

[0079] Prepare PVP@BP nanosheets according to the literature (Chu Hanghang, Preparation and Research of Exfoliated Modified Black Phosphorus Nanosheets and Their Flame Retardant Epoxy Resins [D]. South China University of Technology, 2023.). Prepare PVP@BP nanosheets by ball milling exfoliation method. Mix 1.0 g of BP bulk, 10.0 g of polyvinylpyrrolidone (PVP) powder and stainless steel ball milling beads with diameters of 5 mm (45.3 g) and 1 mm (50.8 g) respectively, transfer them to a stainless steel ball milling jar, and seal them in an argon environment in a glove box. Then install the ball milling jar on a planetary ball mill and perform ball milling at room temperature, with the rotation speed set at 500 r / min. Pause for 5 minutes every 30 minutes of ball milling, and the total ball milling is carried out for 48 cycles, with a total duration of 28 hours. After ball milling, wait for the ball milling jar to cool to room temperature and then open it. Then wash the milled sample with absolute ethanol, and then centrifuge the suspension at a speed of 10000 r / min for 10 minutes, three times. Finally, place the centrifuged product in a vacuum oven at 60 °C and dry it to a constant weight to obtain PVP@BP nanosheets. Replace NBP-1 in Application Example 3 with PVP@BP nanosheets, and keep the others unchanged to obtain PVP@BP modified PA6 composite materials.

[0080] Application Comparative Example 2

[0081] Replace NBP-1 in Application Example 3 with 2,2′-methylene-bis(4,6-di-tert-butylphenyl) aluminum phosphate (organic nucleating agent), and keep the others unchanged to obtain organic nucleating agent modified PA6 composite materials.

[0082] Application Comparative Examples 3-5

[0083] Replace NBP-1 in Application Example 3 with NBP-C1, NBP-C2 and unmodified BP nanosheets in Comparative Examples 1-3, and keep the others unchanged to obtain modified PA6 composite materials.

[0084] The twin-screw extruder models used in Application Examples 1-9 and Application Comparative Examples 1-5 are LTE26 / 40 (LabTech Company, Germany); the obtained composite materials are injection molded into standard specimens using an injection molding machine with the model EC 75NII (Toshiba Company, Japan), and the performance tests are carried out after placing them in a dry room temperature environment for 48 hours. The performance results of Application Examples 1-9 and Application Comparative Examples 1-5 are summarized in Table 1.

[0085] The test methods are as follows:

[0086] According to ISO 11357-3-2018, the maximum crystallization temperature (T c ) is tested. The higher T c , the faster crystallization will start during cooling, and the crystallization rate is also relatively larger.

[0087] Mechanical property tests: The Izod notched impact property was tested according to GB / T 1043.1-2008 using a Zwick 5113 digital pendulum impact tester; the tensile property was tested according to ASTM D-638 standard using an AGS-10KNI universal material testing machine at a tensile rate of 50 mm / min; the flexural property was tested according to ASTM D-790 standard using an AGS-10KNI universal material testing machine at a test rate of 20 mm / min.

[0088] Evaluation of mold sticking phenomenon: Each PA6 composite was injection molded (injection temperature 230 - 260 °C, injection pressure 60 MPa, injection time 3 s, holding pressure 60 MPa, holding time 8 s, cooling time 2 s), and then whether there was a mold sticking phenomenon in the sample was visually confirmed during demolding.

[0089] Table 1 Properties of PA6 composites prepared in Application Examples 1 - 9 and Application Comparative Examples 1 - 5

[0090]

[0091]

[0092] As can be seen from Table 1, the PA6 composites obtained in each application example of the present invention all have ideal rigidity and toughness, with a tensile strength reaching 83.0 MPa, a flexural strength reaching 104.2 MPa, and only a 6% decrease in the notched impact strength. Meanwhile, the crystallization rate is fast, and their maximum crystallization temperature is higher than 191 °C, that is, crystallization can start when the temperature drops to 191 °C. At the same time, under certain process conditions, it is more difficult for the product to stick to the mold during demolding. In contrast, the improvement in the crystallization rate of PA6 composites modified with unmodified BP powder or organic nucleating agents is not significant.

[0093] (1) Crystallization property: The organophosphoric acid basic metal salt modified BP nanosheet composite nucleating agent of the present invention has excellent dispersibility and crystallization property in the PA6 matrix, and can significantly increase T when the dosage is as low as 0.2 wt%. c from 169.4 °C of pure PA6 to 192.7 °C, and the maximum crystallization temperature is increased by 23 °C.

[0094] (2) Improvement in mechanical properties: Compared with PA6 without adding a nucleating agent, the tensile strength of PA6 added with the composite nucleating agent of the present invention is increased by 30.7% and the flexural strength is increased by 22.3%.

[0095] (3) Comparison with PVP-modified BP powder, unmodified BP powder and organic nucleating agent: The composite nucleating agent of the present invention shows better effects in improving mechanical properties and crystallization rate.

[0096] (4) When the ratio of the organic phosphoric acid basic metal salt to the black phosphorus crystal is not within the scope of the present invention, and the ball milling beads and the black phosphorus crystal are not within the scope of the present invention, the novel composite nucleating agent developed by the present invention exhibits a synergistic optimization effect in improving the crystallization rate and mechanical properties, having significant advantages.

[0097] The application of the organic phosphoric acid basic metal salt modified black phosphorus nanosheet composite nucleating agent of the present invention in PA6 has significant advantages. This composite nucleating agent can not only significantly improve the crystallization rate and mechanical properties of PA6 at low dosages, but also exhibit excellent demolding effects and shorten the molding cycle during the injection molding process. In addition, by optimizing parameters such as ball milling conditions, protective gas, and drying temperature, the performance of the composite nucleating agent can be further improved, enabling it to show better effects in different application scenarios. The composite nucleating agent of the present invention has good industrial application prospects.

[0098] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0099] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations fall within the scope defined by the appended claims.

Claims

1. A black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent, characterized in that, The black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent is obtained by modifying black phosphorus crystals with organic phosphoric acid basic metal salts; the black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent has a lamellar structure, with an average thickness of 2.2 nm to 2.9 nm and an average number of layers of 4 - 5 layers.

2. The black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent according to claim 1, wherein The mass ratio of the black phosphorus crystals to the organic phosphoric acid basic metal salts is 1:(1 - 10); The organic phosphoric acid basic metal salts are selected from one or more of organic phosphoric acid basic sodium salts, organic phosphoric acid basic aluminum salts, and organic phosphoric acid basic zinc salts; The black phosphorus crystals are massive black phosphorus crystals.

3. The black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent according to any one of claims 1 or 2, characterized in that, The organic phosphoric acid basic metal salts are selected from one or more of sodium 2,2′-methylenebis(4,6-di-tert-butylphenyl)phosphate, aluminum 2,2′-methylenebis(4,6-di-tert-butylphenyl)phosphate, or zinc bis(2,4-di-tert-butylphenyl)phosphate.

4. A method for preparing the black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent according to any one of claims 1-3, characterized in that, It is prepared by a ball milling exfoliation method, specifically including the following preparation steps: S1. Grind the black phosphorus crystals into black phosphorus powder, and then ball mill the black phosphorus powder, organic phosphoric acid basic metal salts, and ball milling beads in a protective gas atmosphere; S2. After the ball milling process ends, cool to room temperature, then remove the ball milling beads by sieving, and then wash, centrifuge, and dry to obtain the black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent.

5. The preparation method of the black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent according to claim 4, wherein, The mass ratio of the black phosphorus crystals to the ball milling beads is 1:(40 - 100); The ball milling beads are stainless steel balls; The protective gas is helium, argon, or nitrogen; The ball milling process is: the ball milling speed is 300 - 500 r / min, the ball milling time is 24 - 48 h, and it pauses for 5 - 10 min every 30 min of ball milling; The washing method is suction filtration washing or centrifugal washing, and the washing solvent is anhydrous ethanol; the number of suction filtration washing times is 1 - 5 times; Centrifugal washing is to wash the product and then centrifuge, and this process lasts for 3 - 5 times; the centrifugation conditions are that the centrifugation speed is 10000 - 12000 r / min and the single centrifugation time is 10 - 15 min; The drying is vacuum drying, the drying temperature is 70 - 100 °C, and the drying time is 6 - 8 h.

6. The preparation method of the black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent according to claim 4 or 5, characterized in that, The diameter of the ball milling beads is 1 - 10 mm; The ball milling beads are compound stainless steel balls with a diameter ratio of 1:(3 - 6), and the compounding ratio is 1:(1 - 3).

7. Application of the black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent according to any one of claims 1 - 3 or the black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent obtained by the preparation method of the black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent according to any one of claims 4 - 6 in the preparation of a high-rigidity and good-toughness nylon 6 composite material.

8. The application according to claim 7, characterized in that, The added mass percentage of the black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent in the nylon 6 composite material is 0.05% - 0.3%.

9. A nylon 6 composite material modified by a black phosphorus nanosheet / organic phosphoric acid basic metal salt nucleating agent, characterized in that, Comprising the following components in parts by mass: 99.7 to 99.95 parts of nylon 6 resin and 0.05 to 0.3 parts of the black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent according to any one of claims 1 to 3 or the black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent obtained by the preparation method of the black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent according to any one of claims 4 to 6.

10. A preparation method of the black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent modified nylon 6 composite material according to claim 9, comprising the following steps: (1) Mix the nylon 6 resin and the black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent evenly; (2) Place it in an extruder for melt extrusion granulation to obtain the black phosphorus nanosheet / organic phosphoric acid basic metal salt composite nucleating agent modified nylon 6 composite material.

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