CN1160398C - Polymer microspheres with uniform particle size, needle-like particles and forming method - Google Patents

Abstract

The invention belongs to polymer processing. Add a precipitant dropwise to the polymer solution to promote the phase separation of the solution and produce polymer-rich and uniformly sized droplets. Under the protection of another non-precipitating polymer, the stirring speed and temperature are controlled, and the liquid beads are transformed into uniform polymer microspheres or needle-like particles. Protective polymers are added when preparing polymer solutions and precipitants. The solvent for preparing the polymer solution is formic acid, dimethylacetamide, etc., the precipitant is water, and the protective polymer is polyvinyl alcohol, etc. The invention can form dozens of macromolecules such as polyamide, polyether ketone, polyvinylidene fluoride, and cellulose acetate into uniform microspheres or needle-like particles.

Description

Polymer microspheres with uniform particle size, needle-like particles and forming method

The field of the invention is polymer processing.

Polymer microspheres (including natural polymer microspheres) have a wide range of applications. They are used to make various functional coatings such as flame retardant, waterproof, reflective, absorbing ultraviolet or infrared rays, radiation protection, etc. Used in the manufacture of advanced inks and copy toners. Used as an additive in the food, pharmaceutical and cosmetic industries. Used as a catalyst carrier in chemical synthesis. In bioengineering and biotechnology, it is also used as a carrier or adsorbent for biological substances such as proteins, enzymes, cells, etc. They can also be used to prepare various gas and liquid chromatography column supports. It can also prepare immune microspheres and targeted drugs for medical diagnosis and treatment. Due to the specific shape of polymer needle-like particles, replacing polymer microspheres in applications will receive unexpected effects, such as the ability to manufacture directional reflective coatings, high-density chromatographic column supports, anisotropic composite materials, etc.

Apply existing natural polymers, and then process them into microspheres, there are some patent reports, such as JP11181147A (1999), EP075000A1 (1996), US5064949A (1991) and JP3028241A (1991) reported the application of cellulose and derivatives Method for making microspheres. WO9119746A (1991) and EP0087786A (1983) have reported the forming technology of agar and agarose microspheres. CN1105369A (1995) and JP62100534A (1987) reported methods for manufacturing chitin microspheres. Synthetic polymer microspheres are generally produced by using monomers in the polymer synthesis process such as suspension polymerization, emulsion polymerization or dispersion polymerization. It is rare to apply the existing synthetic polymers and then process them into microspheres. There is only one report on the preparation of polyamide microspheres with monodisperse particle size (W.-H.Hou, T.B.Lloyd, J.Appl . Polym. Sci. 45(1992) 1783). There is no report on the application of existing polymer materials to form polymer needle-like particles. Looking at the forming technology of polymer microspheres made of existing polymer materials in the past, it is mainly to prepare polymer solutions, spray them in high-temperature airflow, or perform water/oil dispersion, or form liquid beads in a coagulation bath Solidify, or heat the frozen polymer solution to separate the polymer into spheres. The particle size distribution of microspheres obtained by the first three spheroidizing techniques is wide; the last spheroidizing technique encounters equipment problems to ensure uniform heating or freezing, otherwise microspheres with uniform particle sizes will not be obtained. The aforementioned monodisperse polyamide microspheres are prepared by a freezing method, because rapid and uniform freezing can only be carried out in a 10 ml test tube, and only 0.1 gram of microspheres can be prepared each time.

The purpose of the present invention is to propose a method to manufacture microspheres or needle-shaped particles with uniform particle size by using existing synthetic polymer materials. We hope that this is a generally applicable method that can produce microspheres or needle-like particles of as many synthetic polymers as possible, even including natural polymers.

The uniformity of the size of microspheres and needle-like particles is defined by the dispersion coefficient ε. ε=σ/d, where d is the average diameter of microspheres, or the average long diameter of needle-shaped particles. σ is the standard deviation of the diameter of the microspheres, or the standard deviation of the major diameter of the needle-like particles. For microspheres, ε<0.1 is called monodisperse microspheres, and ε=0.1-0.5 is called uniform microspheres. For needle-shaped particles, ε<1.0 can still be considered as needle-shaped particles with uniform long diameter.

The principle of the invention is to firstly prepare a polymer solution, and then drop a precipitant into the solution to promote the phase separation of the polymer solution to produce liquid beads rich in polymer and uniform in size. Under the protection of another non-precipitating polymer, the stirring speed and temperature are controlled so that the liquid beads do not collide with each other to maintain dimensional stability, and finally the liquid beads are transformed into polymer uniform microspheres or needle-like particles. The polymer that plays a protective role is added when preparing the polymer solution and precipitating agent.

For the convenience of description, the polymer to be processed into microspheres or needle-like particles is called polymer A; the polymer that plays a protective role is called polymer B; the solvent of polymer A is called solvent A , polymer B is also dissolved in solvent A; the precipitant of polymer A but also the solvent of polymer B is called solvent B.

The process of forming polymer uniform microspheres is:

(1) Prepare a mixed polymer solution of polymers A and B in solvent A. The concentration range of polymer A is 0.001-0.1 g/ml, and the concentration of polymer B is 0.1-10 times that of polymer A. This solution is named solution A.

(2) Prepare a polymer solution of polymer B in solvent B. The concentration range of polymer B is 0.001-0.2 g/ml, and solvent B and solvent A are completely miscible. This solution is named solution B.

(3) Solution B is dripped into solution A under stirring to promote phase separation of solution A. Firstly, liquid beads rich in polymer formazan are produced, which gradually transform into swelling microspheres of polymer formazan. The amount of solution B is 1-10 times that of solution A to ensure that polymer A is fully precipitated. When adding solution B dropwise, the stirring speed is 5-500 rpm. The temperature is lower than the boiling point of solvents A and B.

(4) Separating the swollen microspheres of polymer formazan by means of filtration, centrifugation or precipitation. Soak and wash repeatedly with solvent B, and constantly replace solvent B to wash away solvent A and a small amount of co-precipitated polymer B. At this time, the swollen microspheres shrink gradually, and finally polymer (A) microspheres with uniform particle size are obtained.

The process of forming polymer uniform needle-shaped particles is:

(1) Prepare a mixed polymer solution of polymers A and B in solvent A. The concentration range of polymer A is 0.001-0.1 g/ml. The concentration of polymer B is 0.1-10 times that of polymer A. This solution is named solution A.

(2) Prepare a polymer solution of polymer B in solvent B. The concentration range of polymer B is 0.001-0.2 g/ml. Solvent B is completely miscible with solvent A. This solution is named solution B.

(3) Solution B is dripped into solution A under stirring to promote phase separation of solution A. Firstly, liquid droplets rich in polymer formazan are produced, and gradually transformed into swollen needle-like particles of polymer formazan. The amount of solution B is 1-10 times that of solution A to ensure that polymer A is fully precipitated. When solution B is added dropwise, the stirring speed is 100-10000 rpm. The temperature can be close to the boiling point of solvents A and B.

(4) Separating the swollen acicular particles of the polymer formazan by means of filtration, centrifugation or precipitation. Soak and wash repeatedly with solvent B, and constantly replace solvent B to wash away solvent A and a small amount of co-precipitated polymer B. At this time, the swollen needle-shaped particles gradually shrink, and finally the polymer (formazan) needle-shaped particles with uniform particle size are obtained.

The invention produces two groups of polymer microspheres or needle-like particles. The first group of polymers (A) is characterized by being soluble in formic acid or acetic acid or their mixture (solvent A), and all precipitated in water (solvent B). This group of polymers (A) includes polyvinyl formal, polyvinyl butyral, polyvinyl acetate, polyvinyl methyl ketone, polymethyl methacrylate, polyethyl methacrylate, polyformaldehyde N-propyl acrylate, poly-n-butyl methacrylate, polycaprolactam, polyhexamethylene adipate, polyurea, polyurethane, polycarbodiimide, polybenzimidazole, polyquinoxaline, cellulose tricarboxylate , cellulose acetate, nitrocellulose, chitin or a mixture of the above polymers. The second group of polymers (A) is characterized by being soluble in dimethylformamide or dimethylacetamide or their mixture (solvent A), and all precipitated in water (solvent B). This group of polymers (A) includes chlorosulfonated polyethylene, polyacetylene, polyvinyl formal, polyvinyl butyral, polyvinyl chloride, polyvinylidene chloride, polyvinylidene fluoride, polyvinyl methyl Ketone, polythiofluoroethylene, polyacrylonitrile, polymethacrylonitrile, polyacrylaldehyde, polybisacrylmethane, polyacrylic anhydride, polymethacrylic anhydride, polyoxymethylene, polypropionaldehyde, polyacrylaldehyde, polyphenylene ether , polyetherketone, polysulfone, chloromethylated polysulfone, polyethersulfone, polyarylethersulfone, polycarbonate, polysulfoneamide, polyimide, polyetherimide, polybenzoxazole, poly Quinoxaline, methyl cellulose, cellulose acetate, cyanoethyl cellulose acetate, cellulose tricaproate, cellulose tricaprylate or a mixture of the above polymers. In addition, there are also some copolymers, as long as they meet the corresponding solvent and precipitant requirements, they can also be used to make microspheres or needle-shaped particles. The protective polymer (b) used in the present invention is polyvinyl alcohol, polyacrylamide, polyvinylpyrrolidone, polyethylene glycol or their mixtures.

Description of drawings:

Figure 1: Polycaprolactam microspheres.

Figure 2: Polyetherketone needle-like particles.

Figure 3: Polyvinylidene fluoride microspheres.

Figure 4: Cellulose acetate microspheres.

Example 1: 1000 ml of a solution of polycaprolactam and 0.01 g/ml of polyvinyl formic acid with a concentration of 0.01 g/ml was placed in a 5000 ml three-necked bottle. Add polyvinyl alcohol aqueous solution with a concentration of 0.04 g/ml dropwise under stirring. When adding dropwise, pay attention to wait until the precipitation caused by the previous drop has basically disappeared before adding the next drop. The solution was permanently turbid when the dropwise addition reached 650 ml. Continue to add dropwise until the total amount of the added solution reaches 2000 ml. During the dropwise addition, the stirring speed was 250 rpm, and the temperature was 25°C. Stir overnight. On the second day, the microspheres were filtered out, washed repeatedly with water, and finally dried, with a yield of 60%. Microsphere diameter d = 7.63 microns, dispersion coefficient ε = 0.16, see Figure 1.

Example 2: 1000 ml of a solution of polyether ketone and 0.02 g/ml polyvinyl alcohol dimethylacetamide with a concentration of 0.01 g/ml was placed in a 5000 ml three-necked bottle. Add a polyvinyl alcohol aqueous solution with a concentration of 0.02 g/ml dropwise under stirring. When dropping, pay attention to wait until the precipitation caused by the previous drop has basically disappeared before adding the next drop. When the dropwise addition reaches 30 milliliters, the solution appears turbid, and the turbidity reaches the highest after 80 milliliters. Continue to add dropwise until the total amount of the added solution reaches 2000 ml. During the dropwise addition, the stirring speed was 500 rpm, and the temperature was 80°C. Stir overnight. On the second day, the needle-like particles were filtered out, washed repeatedly with water, and finally dried, with a yield of 65%. The long diameter of the particle d=19.6 microns, the dispersion coefficient ε=0.60, see Figure 2.

Example 3: 1000 ml of a solution of polyvinylidene fluoride and 0.02 g/ml of polyvinyl alcohol dimethylacetamide with a concentration of 0.04 g/ml was placed in a 5000 ml three-necked bottle. Add polyvinyl alcohol aqueous solution with a concentration of 0.04 g/ml dropwise under stirring. When adding dropwise, pay attention to wait until the precipitation caused by the previous drop has basically disappeared before adding the next drop. When the dropwise addition reaches 2000 milliliters, the solution becomes turbid. Continue to add dropwise until the total amount of the added solution reaches 3000 milliliters. During the dropwise addition, the stirring speed was 500 rpm, and the temperature was 95°C. Stir overnight. On the second day, the microsphere precipitate was collected with a centrifuge at 3000 rpm, washed with water continuously, and dried. The yield was 82%. Microsphere diameter d=2.97 microns, dispersion coefficient ε=0.23, see Figure 3.

Example 4: 1000 ml of a solution of 0.02 g/ml cellulose diacetate and 0.04 g/ml polyvinyl alcohol dimethylacetamide was placed in a 5000 ml three-necked flask. Add polyvinyl alcohol aqueous solution with a concentration of 0.04 g/ml dropwise under stirring. When adding dropwise, pay attention to wait until the precipitation caused by the previous drop has basically disappeared before adding the next drop. When the dropwise addition reached 230 milliliters, the solution was turbid, and when it reached 400 milliliters, it was completely turbid. Continue to add dropwise until the total amount of the added solution reaches 2000 ml. During the dropwise addition, the stirring speed was 250 rpm, and the temperature was 40°C. Stir overnight. On the second day, the microspheres were filtered out, washed repeatedly with water, and dried, with a yield of 53%. Microsphere diameter d = 8.65 microns, dispersion coefficient ε = 0.25, see Figure 4.

Claims (4)

1. the manufacturing process of the polymer microsphere of uniform granularity is characterized in that:

(1) in desire is shaped high molecular solution and precipitation agent, all dissolved a kind of can sedimentary protection polymer, to keep the microballoon size stability: the high molecular concentration range that is shaped in the solution is the 0.001-0.1 grams per milliliter, protect high molecular concentration be the shaping polymer concentration 0.1-10 doubly; The high molecular concentration range of protection is the 0.001-0.2 grams per milliliter in the precipitation agent;

When (2) dripping precipitation agent, stirring velocity is 5-500 rev/min, and temperature is lower than the solvent that is mixed with the form height molecular solution and the boiling point of precipitation agent.

2. the manufacturing process of the polymer acicular microparticles of uniform granularity is characterized in that:

(1) in desire is shaped high molecular solution and precipitation agent, all dissolved a kind of can sedimentary protection polymer, to keep the acicular microparticles size stability: the high molecular concentration range that is shaped in the solution is the 0.001-0.1 grams per milliliter, protect high molecular concentration be the shaping polymer concentration 0.1-10 doubly; The high molecular concentration range of protection is the 0.001-0.2 grams per milliliter in the precipitation agent;

When (2) dripping precipitation agent, stirring velocity is 100-10000 rev/min, and temperature can approach to be mixed with the solvent of form height molecular solution and the boiling point of precipitation agent.

3. the uniform microsphere and the acicular microparticles of polyvinyl formal, polyvinyl butyral acetal, polyvinyl acetate, polyvinyl methyl ketone, polymethylmethacrylate, polyethyl methacrylate, poly-n-propyl methacrylate, Vinalac 5920, polycaprolactam, PA 66, polyureas, urethane, polycarbodiimide, polybenzimidazole, Ju quinoxaline, tricarboxylic acid Mierocrystalline cellulose, rhodia, soluble cotton, chitin or above-mentioned macromolecule mixture is characterized in that:

(1) it is made by claim 1 or 2 described methods with existing macromolecular material;

(2) solvent that is mixed with the form height molecular solution is formic acid, acetate or their mixture, and precipitation agent is a water, and the protection polymer is polyvinyl alcohol, polyacrylamide, polyvinylpyrrolidone, polyoxyethylene glycol or their mixture.

4. chlorosulfonated polyethylene, polyacetylene, polyvinyl formal, polyvinyl butyral acetal, polyvinyl chloride, polyvinylidene chloride, polyvinylidene difluoride (PVDF), polyvinyl methyl ketone, poly-sulphur vinyl fluoride, polyacrylonitrile, polymethacrylonitrile, polyacrolein, poly-two acryloyl methane, poly acrylic anhydride, polymethacrylic acid anhydride, polyoxymethylene, poly-propionic aldehyde, polyacrolein, polyphenylene oxide, polyetherketone, polysulfones, chloromethyl polysulphone, polyethersulfone, polyether sulphone, polycarbonate, polysulfonamides, polyimide, polyetherimide, polybenzoxazole Ju quinoxaline, methylcellulose gum, rhodia, the cyanoethyl rhodia, three cellulose caproates, the uniform microsphere and the acicular microparticles of three sad Mierocrystalline celluloses or above-mentioned macromolecule mixture is characterized in that:

(1) they all are to make by claim 1 or 2 described methods with existing macromolecular material;

(2) solvent that is mixed with the form height molecular solution is dimethyl formamide, N,N-DIMETHYLACETAMIDE or their mixture, and precipitation agent is a water, and the protection polymer is polyvinyl alcohol, polyacrylamide, polyvinylpyrrolidone, polyoxyethylene glycol or their mixture.

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