Preparation method of polypropylene nucleating agent with controllable morphology

Abstract

The present invention discloses a method for preparing a morphology-controllable polypropylene nucleating agent. The method comprises dissolving an organic phosphate in an organic solvent, adding a surfactant, and mixing the solution with water in a planar oscillating reactor placed under ultrasound to precipitate the organic phosphate. The organic phosphate is then separated and dried to obtain organic phosphate crystals of various shapes and sizes. This method can precisely control the shape and size of the organic phosphate crystals to obtain monodisperse organic phosphate crystals. The organic phosphate crystals also have a narrow particle size distribution, stable quality, high yield, and high nucleation efficiency. The resulting crystals are micron-sized powder particles with uniform particle size. When used as a polypropylene nucleating agent, the crystals can be easily and evenly dispersed in a polypropylene resin material, thereby improving their nucleation efficiency. The method is simple to operate, has a short processing time, low energy consumption, mild conditions, and low cost, and can be used for industrial large-scale continuous production.

Description

Technical Field

[0001] The invention belongs to the technical field of micro-nano crystal preparation, and particularly relates to a method for preparing a polypropylene nucleating agent with controllable morphology. Background Art

[0002] Adding a small amount of nucleating agent to partially crystalline polypropylene can effectively improve the performance of the resin material. Organophosphates offer outstanding thermal stability, strong nucleating ability, are nontoxic, and odorless. Polypropylene prepared with them exhibits more complete crystallization and superior performance. However, their high melting point and poor dispersibility lead to low nucleation efficiency, high dosage, and increased economic costs. Zhang Qia et al., in "Effect of Organophosphate Nucleating Agent Particle Size on PP Properties" (Engineering Plastics Applications, 2016, 44, 19-24), conducted a detailed study on the effect of organophosphate nucleating agent particle size on PP properties. They found that smaller nucleating agent particle size significantly improved PP mechanical properties. Han Rui et al., in "Continuously enhanced hoop strength of rotation-extruded polypropylene pipe via self-assembly β-nucleating agent with different aspect ratios" (J Polym Res. 2017, 24, 204), prepared nucleating agents with different aspect ratios by temperature adjustment and found that a larger aspect ratio resulted in better polypropylene performance. Therefore, improving the nucleation efficiency by reducing the particle size of organophosphates and controlling their morphology is a necessary measure to achieve industrial applications.

[0003] Current methods for improving the performance of organophosphates include: Patent Publication No. CN1432594A, "A Polypropylene Nucleating Agent and Its Preparation Method," uses conventional mechanical crushing to reduce the particle size of the nucleating agent, but this method consumes a lot of energy, has a wide particle size distribution, and destroys the crystal form of the nucleating agent. Patent Publication No. CN102382359A, "A Method for Preparing an Ultrafine Organophosphate Nucleating Agent," uses spray drying to prepare the nucleating agent, resulting in a small particle size and high dispersibility, but the operation is complex and costly, making it unsuitable for industrial production. Patent Publication No. CN113354864B, "A Polypropylene Nucleating Agent and Its Preparation Method," uses a compound of higher fatty acid salts to improve nucleation performance, but this is time-consuming, costly, and also destroys the crystal form of the nucleating agent. Patent publication number CN 102827397B, "Method for Changing the Morphology and / or Particle Size of Organic Phosphate Nucleating Agents, Organic Phosphate Nucleating Agents, Applications Thereof, and Polypropylene Materials," uses microwave radiation heating to prepare nucleating agents of different particle sizes and morphologies. This approach offers high efficiency and controllability, but suffers from high energy consumption, uneven crystal size, and easy agglomeration.

[0004] In summary, the morphology control of the organophosphate nucleating agent in the prior art is very uneven, and the size cannot be controlled. The morphology and size of the nucleating agent have a great impact on the preparation of the final plastic product. Summary of the Invention

[0005] To overcome the shortcomings of the aforementioned prior art, the present invention aims to provide a method for preparing organophosphate crystals that can control their morphology. This method utilizes a planar oscillator and ultrasonic techniques to produce organophosphates, achieving precise and controllable crystal preparation. Its morphology and size can be precisely controlled, while also exhibiting narrow particle size distribution, stable quality, high yield, and high nucleation efficiency. By varying process parameters, monodisperse organophosphate crystals of varying sizes and morphologies, such as rods (aspect ratio greater than 3) and hexagonal (aspect ratio 1-3) ranging from 10 to 40 microns, can be obtained, thus addressing the technical issues of difficult morphology control and poor uniformity of nucleating agents in the prior art.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides a method for preparing a polypropylene nucleating agent with controllable morphology, the method comprising the following steps:

[0007] The organophosphate is dissolved in an organic solvent and a surfactant is added; the organic solvent containing the organophosphate and anti-solvent water whose temperature is controlled by a microheat exchanger are respectively introduced into a planar oscillating reactor under different flow rate ratios to fully mix the two phases, and the entire reactor is placed in an ultrasonic environment; the liquid flowing out of the reactor is received, solid-liquid separation is performed, and drying is performed to obtain organophosphate crystals of various morphologies and sizes, which are polypropylene nucleating agents.

[0008] Surfactants can change the crystal growth rate and structural stability, thereby achieving the purpose of regulating crystal morphology; at the same time, they can prevent crystals from aggregating with each other, keeping them in a dispersed state. The concentration and flow rate ratio of organic phosphates affect the supersaturation in the solution. A high supersaturation results in a small crystal particle size, while a low supersaturation results in a large crystal particle size. By controlling different organic phosphate concentrations and flow rate ratios, crystals of different particle sizes can be obtained. The antisolvent temperature also affects the supersaturation. A low temperature results in a high supersaturation, a high nucleation rate, and small crystals. Excessive temperature will change the crystal growth mechanism and lead to crystal transformation. Temperature control with a microheat exchanger is conducive to antisolvent crystallization. Ultrasound can promote the dissolution rate and solute diffusion rate inside the crystal, thereby affecting the crystal morphology. The crystal morphology can be regulated by controlling the ultrasonic power of the external environment of the planar oscillating reactor. Ultimately, the two phases are fully mixed to achieve the purpose of antisolvent crystallization.

[0009] In the above technical solution, further, the organic phosphate is made from a crude product of bis[methylenebis(2,4-dialkylphenoxy)]phosphate, and the molecular formula of the organic phosphate is:

[0010]

[0011] Among them, R1 and R2 represent hydrogen atoms or C1~C 12 alkyl, nitro, halogen, or aryl; R3 represents a C1-C4 alkyl, oxygen, or sulfur; M is an alkali metal or an alkaline earth metal, preferably lithium, sodium, or potassium, and preferably calcium, magnesium, or barium; n is 1 or 2; the crude phosphate product is a commercially available product.

[0012] The concentration of the organophosphate dissolved in the organic solvent is 0.01 g / mL to 6 g / mL, preferably 3 g / mL to 6 g / mL.

[0013] Furthermore, the organic solvent is at least one of methanol, ethanol, propanol, butanol, ethyl acetate, tetrahydrofuran, dimethyl sulfoxide, N-dimethylformamide, N-dimethylacetamide or 1,4-dioxane.

[0014] Furthermore, the surfactant is at least one of sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, octadecyltrimethylammonium chloride, octadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, polyethylene glycol, Pluronic F-127, N-vinylamide polymers, or fatty polyoxyethylene ethers; or there is no surfactant;

[0015] The amount of the surfactant used is 0-5% of the total weight of the system, preferably 0.1%-3%.

[0016] Furthermore, the flow rate ratio of the organic solvent to water is 0.1-10, preferably 0.1-1.

[0017] Furthermore, the anti-solvent temperature is 0°C to 80°C, preferably 2°C to 30°C.

[0018] Furthermore, the structure of the planar oscillating reactor is as follows: Figure 4 As shown, the reactor features a smooth, periodic contraction channel within which the crystallization process occurs. The two inlets of the crystallization channel form a 90° Y-shaped mixing pattern. The channel measures 3 mm at its narrowest point and 8 mm at its widest point, with a liquid holdup of approximately 25 ml.

[0019] Furthermore, the ultrasonic power of the ultrasonic environment does not exceed 100W, and is preferably less than 30W.

[0020] Furthermore, the solid-liquid separation method is sedimentation, filtration, and centrifugation.

[0021] Furthermore, the drying method is oven drying, vacuum drying, or freeze drying; the drying temperature is -60°C to 150°C, preferably -40°C to 80°C.

[0022] Furthermore, by changing the process parameters, organophosphate crystals (polypropylene nucleating agent) with different morphologies and sizes were obtained:

[0023] ①10-40 micron rod-shaped polypropylene nucleating agent

[0024] A commercially available organophosphate nucleating agent (3 g to 6 g of organophosphate) is dissolved in 10 mL of an organic solvent (methanol), and 0.1% to 0.5% of a surfactant (polyoxyethylene octylphenol ether, Pluronic F-127, or cetyltrimethylammonium bromide) is added relative to the total system. A good solvent containing the organophosphate and anti-solvent water, temperature-controlled with a microheat exchanger (reaction temperature: 2°C to 10°C), are introduced into a planar oscillating reactor, respectively, at varying flow rate ratios (the organic solvent to water flow rate ratio is 0.2 to 0.5). The two phases are thoroughly mixed, and the entire reactor is placed in an ultrasonic environment (ultrasonic power not exceeding 20 W). The liquid flowing out of the reactor is collected, subjected to solid-liquid separation (filtration), and dried (freeze-dried) to obtain a 10-40 micron rod-shaped polypropylene nucleating agent.

[0025] ②5-15 micron hexagonal polypropylene nucleating agent

[0026] A commercially available organophosphate nucleating agent (3 g to 6 g of organophosphate) is dissolved in 10 mL of an organic solvent (methanol), and 0.1% to 0.5% of a surfactant (polyoxyethylene octylphenol ether, Pluronic F-127, or cetyltrimethylammonium bromide) is added relative to the total system. A good solvent containing the organophosphate and anti-solvent water, temperature-controlled with a microheat exchanger (reaction temperature: 2° C. to 10° C.), are introduced into a planar oscillating reactor at different flow rate ratios (the organic solvent to water flow rate ratio is 0.2 to 0.5) to fully mix the two phases. The entire reactor is then placed in an ultrasonic environment (ultrasonic power: 20 W to 100 W). The liquid flowing out of the reactor is collected, subjected to solid-liquid separation (filtration), and dried (freeze-dried) to obtain a 5-15 micron hexagonal polypropylene nucleating agent.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] ① The polypropylene nucleating agent (organophosphate crystals) prepared by the present invention is a micron-sized powder particle with uniform particle size, which is very easy to be evenly dispersed in the polypropylene resin material, thereby improving its nucleation efficiency and being able to be widely used commercially.

[0029] ② The method of the present invention is convenient for regulating the morphology of the polypropylene nucleating agent. Rod-shaped or hexagonal crystals can be obtained by changing the process parameters of the experiment. The preparation method is simple to operate.

[0030] ③ The present invention can continuously produce polypropylene nucleating agents (organophosphate crystals), avoiding the problem of product differentiation caused by different industrial batches. At the same time, the processing time is short, the energy consumption is low, the conditions are mild, and the cost is low, so industrial large-scale production can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a photo of the structure of the rod-shaped polypropylene nucleating agent prepared in Example 1;

[0032] Figure 2 This is a photo of the structure of the rod-shaped polypropylene nucleating agent prepared in Example 2;

[0033] Figure 3 This is a photo of the structure of the hexagonal polypropylene nucleating agent prepared in Example 3;

[0034] Figure 4 This is a structural diagram of the planar oscillating reactor in the present invention. DETAILED DESCRIPTION

[0035] The present invention will be further described below with reference to specific examples, but the present invention is not limited in any way. To avoid redundancy, the raw materials in the following examples are all commercially available products unless otherwise specified, and the methods used are all conventional methods unless otherwise specified.

[0036] A method for preparing a polypropylene nucleating agent with controllable morphology comprises the following steps: dissolving an organic phosphate in an organic solvent and adding a surfactant; controlling different flow rate ratios, introducing the organic solvent containing the organic phosphate and anti-solvent water, temperature-controlled by a microheat exchanger, into a planar oscillating reactor to fully mix the two phases, and placing the entire reactor in an ultrasonic environment; receiving liquid flowing out of the reactor, performing solid-liquid separation, and drying to obtain organic phosphate crystals of various morphologies and sizes, which are the polypropylene nucleating agent;

[0037] Wherein, the concentration of the organic phosphate is 0.01 to 6 g / mL;

[0038] The amount of the surfactant is 0-5% of the total weight of the system;

[0039] The flow rate ratio of the organic solvent to water is 0.1 to 10;

[0040] The temperature of the anti-solvent after temperature control is 0°C to 80°C;

[0041] The ultrasonic power of the ultrasonic environment does not exceed 100W.

[0042] The organic phosphate is prepared from a crude product of bis[methylenebis(2,4-dialkylphenoxy)]phosphate; the organic solvent is at least one of methanol, ethanol, propanol, butanol, ethyl acetate, tetrahydrofuran, dimethyl sulfoxide, N-dimethylformamide, N-dimethylacetamide, or 1,4-dioxane; the surfactant is at least one of sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium dodecylbenzenesulfonate, octadecyltrimethylammonium chloride, octadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, polyethylene glycol, Pluronic F-127, N-vinylamide polymers, or fatty polyoxyethylene ethers; the solid-liquid separation method is sedimentation, filtration, or centrifugation; the drying method is drying, vacuum drying, or freeze drying; and the drying temperature is -60°C to 150°C.

[0043] Any matters not described in the following embodiments are the same as those described in the above specific implementation methods.

[0044] Example 1

[0045] A method for preparing a polypropylene nucleating agent with controllable morphology, comprising the following steps:

[0046] 4 g of crude sodium 2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate was dissolved in 10 mL of methanol to prepare an organic phosphate concentration of 4 g / 10 mL (methanol). 0.5% Pluronic F-127 was added relative to the entire system. The flow rate ratio of methanol to water was controlled to be 0.33. The methanol solution containing sodium 2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate and 2°C water were respectively introduced into a planar oscillating reactor (such as Figure 4 As shown), the entire reactor is not ultrasonicated; the liquid flowing out of the reactor is collected, filtered, and freeze-dried to obtain 30-40 micron 2,2'-methylenebis(4,6-di-tert-butylphenyl) sodium phosphate powder. The polypropylene nucleating agent product is a flowable white powder with a rod-like structure, as shown Figure 1 shown.

[0047] Example 2

[0048] A method for preparing a polypropylene nucleating agent with controllable morphology, comprising the following steps:

[0049] 3 g of crude sodium 2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate was dissolved in 10 mL of methanol to prepare an organic phosphate concentration of 3 g / 10 mL (methanol). 0.25% hexadecyltrimethylammonium bromide was added relative to the entire system. The flow rate ratio of methanol to water was controlled to be 0.33. The methanol solution containing sodium 2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate and 2°C water were respectively introduced into a planar oscillating reactor (such as Figure 4 As shown), the entire reactor is placed in a 20W ultrasonic wave; the liquid flowing out of the reactor is collected, filtered, and freeze-dried to obtain 5-15 micron 2,2'-methylenebis(4,6-di-tert-butylphenyl) sodium phosphate powder. The polypropylene nucleating agent product is a flowable white powder with a rod-like structure, as shown Figure 2 shown.

[0050] Example 3

[0051] A method for preparing a polypropylene nucleating agent with controllable morphology, comprising the following steps:

[0052] 6 g of crude sodium 2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate was dissolved in 10 mL of methanol to prepare an organic phosphate concentration of 6 g / 10 mL (methanol). 0.25% hexadecyltrimethylammonium bromide was added relative to the entire system. The flow rate ratio of methanol to water was controlled to be 0.33. The methanol solution containing sodium 2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate and 2°C water were respectively introduced into a planar oscillating reactor (such as Figure 4 As shown), the entire reactor is placed in a 60W ultrasonic wave; the liquid flowing out of the reactor is collected, filtered, and freeze-dried to obtain 15-25 micron 2,2'-methylenebis(4,6-di-tert-butylphenyl) sodium phosphate powder. The polypropylene nucleating agent product is a flowable white powder with a hexagonal structure, as shown Figure 3 shown.

[0053] Anyone skilled in the art will be able to utilize the above-disclosed technical content to make many possible changes and modifications to the technical solution of the present invention, or to modify it into equivalent embodiments with equivalent changes, without departing from the scope of the technical solution of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention that do not depart from the content of the technical solution of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a polypropylene nucleating agent with controllable morphology, characterized in that: The method comprises the following steps: dissolving an organic phosphate in an organic solvent and adding a surfactant; controlling different flow rate ratios, introducing the organic solvent containing the organic phosphate and anti-solvent water whose temperature is controlled by a microheat exchanger into a planar oscillating reactor respectively, so that the two phases are fully mixed, and placing the entire reactor in an ultrasonic environment; receiving the liquid flowing out of the reactor, performing solid-liquid separation, and drying to obtain organic phosphate crystals of various shapes and sizes, namely, polypropylene nucleating agents; the polypropylene nucleating agents have different sizes and shapes such as rods and hexagons; Wherein, the concentration of the organic phosphate is 0.01 to 6 g / mL; The amount of the surfactant is 0-5% of the total weight of the system; The flow rate ratio of the organic solvent to water is 0.1 to 10; The temperature of the anti-solvent after temperature control is 0°C to 80°C; The ultrasonic power of the ultrasonic environment does not exceed 100W.

2. The preparation method according to claim 1, characterized in that The organic phosphate is made from a crude product of bis[methylenebis(2,4-dialkylphenoxy)]phosphate, and the molecular formula of the organic phosphate is: Among them, R1 and R2 represent hydrogen atoms or C1~C 12 alkyl, nitro, halogen, or aryl; R3 represents a C1-C4 alkyl, oxygen, or sulfur; M is an alkali metal or an alkaline earth metal, wherein the alkali metal is lithium, sodium, or potassium, and the alkaline earth metal is calcium, magnesium, or barium; and n is 1 or 2.

3. The preparation method according to claim 1, characterized in that The concentration of the organic phosphate dissolved in the organic solvent is 3-6 g / mL.

4. The preparation method according to claim 1, characterized in that The organic solvent is at least one of methanol, ethanol, propanol, butanol, ethyl acetate, tetrahydrofuran, dimethyl sulfoxide, N-dimethylformamide, N-dimethylacetamide or 1,4-dioxane.

5. The preparation method according to claim 1, characterized in that The surfactant is at least one of sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium dodecylbenzenesulfonate, octadecyltrimethylammonium chloride, octadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, polyethylene glycol, Pluronic F-127, N-vinylamide polymers or fatty polyoxyethylene ethers; the amount of the surfactant used is 0.1% to 3% of the total weight of the system.

6. The preparation method according to claim 1, characterized in that The flow rate ratio of the organic solvent to water is 0.1-1.

7. The preparation method according to claim 1, characterized in that The anti-solvent temperature is 2°C to 30°C.

8. The preparation method according to claim 1, characterized in that The ultrasonic power of the ultrasonic environment is less than 30W.

9. The preparation method according to claim 1, characterized in that The drying method is oven drying, vacuum drying, or freeze drying; the drying temperature is -60°C to 150°C.

Images