WO2023284585A1 - Polyamide microparticle and preparation method therefor - Google Patents

Abstract

The present invention aims to provide a method for producing polyamide microparticles, the obtained microparticles having controllable particle size, narrow particle size distribution and high sphericity. The main technical features are as follows: a polyamide monomer A is polymerized in the presence of a polymer B, a boric acid compound is added at any time before the end of polymerization, and, in the state in which the polyamide is dissolved in the polymer B or droplets formed by the polyamide are dispersed in the polymer B, microparticles containing the polyamide are precipitated. The present invention also provides a polyamide microparticle containing boron and having narrow particle size distribution and high sphericity.

Description

A kind of polyamide particle and preparation method thereof technical field

The invention belongs to the field of polymer materials, and in particular relates to a polyamide particle and a preparation method thereof.

Background technique

Polyamide microparticles are characterized by high toughness, flexibility, and high heat resistance, so they are used in various applications such as powders and coatings. For example, in recent years, with the development of 3D printing technology, polyamide particles with spherical shape, solid and smooth surface made of polyamide 12 and other polyamides as raw materials are beneficial to the flatness of powder coating in laser sintering molding technology, The surface of the molding is smooth. In addition, polyamide microparticles are also used in high-quality cosmetics and paints due to their smooth surface and good skin feel.

In addition, polyamide resins such as polyamide 6 and polyamide 66 have a higher melting point than polyamide 12, so they can be widely used in applications requiring higher heat resistance.

In contrast, Patent Documents 1 and 2 disclose a method of dissolving polyamide in a solvent and then adding a non-solvent and water to produce porous polyamide fine particles. Patent Documents 3 and 4 disclose a method in which polyamide is vigorously stirred at a temperature above the melting point in a medium such as polyethylene glycol, and a method in which polyamide raw materials are subjected to polycondensation reaction in a silicone oil medium. Polyamide is mechanically stirred and dispersed in the polymer to produce particles, so only fine particles with a wide particle size distribution can be produced.

Patent Document 5 discloses anionic polymerization in a paraffin medium to provide amorphous polyamide microparticles. Patent Document 6 further discloses a method for producing polyamide microparticles by anionic polymerization in ethylbenzene or chlorobenzene. However, as far as the technology of anionic polymerization is concerned, because the initiator is flammable, and a flammable medium and solvent are used, it is difficult to polymerize at a high temperature, and the polyamide is precipitated in the solvent due to the decrease in solubility, so the production The particles are of indeterminate shape. Furthermore, in order to remove various media and solvents, a large amount of organic solvents and various complicated steps are required.

prior art literature

patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2002-80629

Patent Document 2: Japanese Patent Laid-Open No. 2010-053272

Patent Document 3: Japanese Patent Application Laid-Open No. 60-040134

Patent Document 4: Japanese Patent Application Laid-Open No. 10-316750

Patent Document 5: Japanese Patent Laid-Open No. 61-181826

Patent Document 6: Japanese Patent Application Laid-Open No. 08-073602

Contents of the invention

The problem to be solved by the invention

In view of the above-mentioned problems, the object of the present invention is to provide a method for producing polyamide microparticles, which can polymerize and precipitate polyamide microparticles in a polymer solvent, and the particle diameter of the microparticles is easy to adjust, the particle size distribution is narrow, and the degree of sphericity is high. It is not easy to agglomerate, and the polymerization speed of the microparticle polyamide is improved, and the molecular weight of the microparticle polyamide is high. Another object of the present invention is to provide a polyamide having a narrow particle size distribution, a high sphericity, and a high molecular weight.

After repeated in-depth studies, the present inventors found that by polymerizing the monomer A of the polyamide in the presence of the polymer B, adding a boric acid compound at any time before the end of the polymerization, and dissolving the polyamide in the polymer B Under the condition that the droplets formed by the polyamide are dispersed in the polymer B, the fine particles containing the polyamide are precipitated, thereby, the particle size and particle size distribution can be easily adjusted, the polymerization reaction can be promoted, and the polymer with high sphericity can be precipitated. Amide particles and polyamide particles are not easy to aggregate.

The inventors also found that the polyamide microparticles containing boron and having a volume-based average particle size/number-based average particle size in a specific range can achieve narrow particle size distribution, high sphericity and high number-average molecular weight.

The present invention consists of the following contents:

1. A method for preparing polyamide microparticles, characterized in that the monomer A of the polyamide is polymerized in the presence of the polymer B, and a boric acid compound is added at any time before the end of the polymerization, and the polyamide is dissolved in the polymer In the state of B or in the state in which droplets formed of polyamide are dispersed in the polymer B, fine particles containing polyamide are deposited.

2. The method for producing polyamide microparticles according to the above 1, wherein the boric acid compound is added in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the polyamide monomer A.

3. The method for producing polyamide microparticles according to the above 2, wherein the boric acid compound is added in an amount of 0.4 to 5 parts by weight based on 100 parts by weight of the polyamide monomer A.

4. The method for preparing polyamide microparticles according to the above 1, wherein the boric acid compound includes at least one of boric acid, borate, and organic boric acid compound.

5. The method for preparing polyamide microparticles according to the above 1, wherein the monomer A of the polyamide is selected from diamines having 2-20 carbon atoms and dibasic amines having 2-20 carbon atoms. At least one of combinations of acids, aliphatic aminoalkanoic acids having 6-12 carbon atoms, lactams having 6-12 carbon atoms, mixtures of the above monomers, and salts thereof.

6. The method for producing polyamide microparticles according to the above 1, wherein the ratio of the molar weight of total amino groups to the total molar weight of carboxyl groups in the monomer A of the polyamide, that is, total amino groups/total carboxyl groups, is 0.990 to 1.035.

7. The method for producing polyamide microparticles according to 1 above, wherein the weight ratio of the monomer A to the polymer B in the polyamide, that is, monomer A/polymer B, is 0.1 to 9.0.

8. The method for preparing polyamide microparticles according to the above 1, wherein the melting point of the polymer B is 30°C to 200°C.

9. The method for producing polyamide microparticles according to the above 1, wherein the number average molecular weight of the polymer B is 500-500,000.

10. The method for preparing polyamide microparticles according to the above 1, wherein the polymer B is polyethylene glycol, polypropylene glycol, poly-1,4-butylene glycol, polyethylene glycol-polypropylene glycol copolymer, and at least one of polymers whose hydroxyl terminal -OH is hydroxyalkylated.

11. The method for producing polyamide fine particles according to the above 1, wherein the polymerization is carried out by adding a solvent C.

12. The method for producing polyamide fine particles according to the above 11, wherein the solvent C is water.

13. Polyamide microparticles, characterized by containing boron element and having a volume-based average particle diameter/number-based average particle diameter of 1.00 to 2.50.

14. The polyamide fine particles according to the above 13, characterized in that the content of the boron element is 5 ppm to 20000 ppm relative to the weight of the polyamide fine particles.

15. The polyamide fine particles according to the above 13, characterized in that the content of the boron element is 5 ppm to 600 ppm relative to the weight of the polyamide fine particles.

16. The polyamide microparticles according to 13 above, wherein the volume-based average particle diameter/number-based average particle diameter is 1.00 to 2.00.

17. The polyamide microparticles according to the above 13, which have a sphericity of 70-100.

18. The polyamide fine particles according to the above 13, wherein the molar concentration of amino groups/molar concentration of carboxyl groups in the polyamide fine particles is 0.06 to 2.00.

19. The polyamide microparticles according to the above 13, wherein the volume-based average particle diameter MV is 10 micrometers to 150 micrometers.

20. The polyamide fine particles according to the above 13, wherein (D90-D10)/D50 is 2.0 or less.

21. The polyamide fine particles according to the above 13, wherein the polyamide fine particles have a number average molecular weight of 5,000 to 50,000.

The effect of the invention

In the present invention, by polymerizing the monomer A of the polyamide in the presence of the polymer B, a boric acid compound is added at any time before the end of the polymerization, and the polymerized polyamide is dissolved in the polymer B or the polyamide Polyamide microparticles were obtained by separating the formed droplets in a state where the polymer B was dispersed. Through the production method of the present invention, the droplets formed by the polyamide can be inhibited from coagulating in the polymer B, and the polymerization reaction can be promoted, the degree of polymerization of the polyamide can be improved, and the particle size range can be easily adjusted, the particle size distribution is narrow, and the spherical Polyamide particles with high density and high molecular weight.

The above-mentioned content of the invention is described in detail below:

The present invention is a method for obtaining polyamide microparticles, wherein polyamide microparticles are obtained by polymerizing polyamide monomer A in the presence of polymer B and adding a boric acid compound at any time before the end of the polymerization.

The inventors of the present application found in experiments that, in the absence of boric acid compound, during the polymerization of polyamide monomer A, as the polymerization reaction proceeds, the molecular weight of polyamide increases, and droplets separated from polymer B will be formed After a suitable polymerization time, the mixture of polyamide and polymer B is cooled down, for example, immersed in water, and the polyamide droplets will form solid polyamide particles due to cooling. Since polyamide and polymer B have been separated, polyamide microparticles can be isolated by removing polymer B. However, in the polymerization process, whether polyamide and polymer B can be separated is affected by many factors, and the separation of polyamide and polymer B to form droplets is a key step in the final formation of polyamide particles, which affects the final polyamide particle size. Particle size, particle size distribution and other characteristics. Affected by the ratio of polyamide monomer A to polymer B, the compatibility of different types of polyamides and polymer B, etc., the following situations often occur: polyamide cannot be separated from polymer B; or, although polyamide The droplets separated from polymer B, but the polyamide droplets coagulated with each other, and even polymer B was encapsulated in it due to the coagulation of polyamide. These conditions will cause the polyamide particles to stick to each other, the particle size of the formed particles is difficult to control and the particle size distribution is wide, and the sphericity of the polyamide particles is greatly reduced, and even the polyamide particles cannot be separated at all.

In order to solve this problem, the inventors of the present application screened boric acid compounds through a large number of experiments, and found that under the conditions that polyamide could not be separated and obtained, by adding boric acid compounds, polyamide droplets can be prevented from agglomerating, making polyamide droplets smooth. Separation from Polymer B forms polyamide microparticles. At the same time, it is found that the addition of boric acid compound can promote the polymerization reaction, thereby obtaining polyamide particles with high molecular weight. It is also unexpectedly found that under the condition of adding boric acid compounds, the particle size distribution of polyamide particles can always maintain a narrow distribution, and the polyamide particles are spherical and can always maintain a high degree of sphericity. Therefore, by uniformly dissolving polyamide monomer A and polymer B at the beginning of polymerization, and adding a boric acid compound at any time before the end of polymerization, polyamide particles are precipitated after polymerization, which can solve the problems caused by polymerization in conventional methods. Due to the problems of irregular shape and wide particle size distribution caused by the aggregation of amide particles, polyamide particles with high sphericity, smooth surface, fineness and narrow particle size distribution were obtained.

Regarding the addition of the boric acid compound, it can be added at any time before the end of the polymerization. That is, the boric acid compound may be added to the reaction system together with the polyamide monomer A and polymer B at the beginning of the polymerization, or may be added to the reaction system at any time during the polymerization.

The inventors of the present application found through further experiments that the particle size of polyamide particles can be controlled and adjusted by changing the amount of boric acid compound added. Therefore, from the viewpoint of adjusting the particle size of the polyamide microparticles, it is preferable to add the boric acid compound in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the polyamide monomer A. From the viewpoint of further accelerating the dispersion of the polyamide droplets in the polymer B, the added amount of the boric acid compound is preferably 0.4 parts by weight or more, more preferably 1.0 parts by weight or more. Too much boric acid compound hinders the polymerization of polyamide, so the added amount of boric acid compound is preferably 5 parts by weight or less, more preferably 4 parts by weight or less.

As the boric acid compound, including but not limited to boric acid (B(OH) ₃ ), metaboric acid (HBO ₂ ), boric acid anhydride (B ₂ O ₃ ), sodium tetraborate (Na ₂ B ₄ O ₇ ) and its crystalline Water compounds such as borates, or organic boric acid compounds. The organic boronic acid compound can include alkyl boronic acid (RB(OH) ₂ ), aryl boronic acid (ArB(OH) ₂ ) and its esters, wherein alkyl (-R) includes but not limited to methyl (-CH ₃ ), propenyl (-CH=CHCH ₃ ), aryl (-Ar) includes but not limited to phenyl, thienyl . Considering that the added boric acid compound is well compatible with the polyamide monomer A and the polymer B, the boric acid compound is preferably boric acid, metaboric acid, or organic boric acid compound. Particular preference is given to boronic acids, alkylboronic acids and their esters.

The polyamide constituting the polyamide microparticles of the present invention refers to a polymer having a structure including an amide group. The monomer A forming the amide structure may be at least one selected from mixtures of dibasic acids and diamines, aminoalkanoic acids, lactams, and salts of these monomers. Where monomer A is selected from aminoalkanoic acids or lactams, preference is given to aminoalkanoic acids having 6 to 12 carbon atoms, or lactams having 6 to 12 carbon atoms. In the case where monomer A is selected from a mixture of dibasic acids and diamines, diamines having 2-20 carbon atoms and dibasic acids having 2-20 carbon atoms are preferred. The above-mentioned monomers may be polymerized alone (homopolymer), or two or more of them may be copolymerized in combination (copolymer). In addition, it can also be copolymerized with other components within the range that does not impair the present invention.

Examples of the aminoalkanoic acid include aminoalkanoic acids such as aminocaproic acid, aminoundecanoic acid, and aminododecanoic acid.

Examples of the lactam include lactams such as ε-caprolactam, ω-undecalactam, and ω-laurolactam.

Examples of the above dibasic acid include aliphatic dicarboxylic acids such as oxalic acid, succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, or dodecanedioic acid, terephthalic acid, isophthalic acid, etc. Formic acid, 2-chloro-1,4-benzenedicarboxylic acid, 2-methyl-1,4-benzenedicarboxylic acid or 5-methylisophthalic acid, 5-sulfonate sodium isophthalic acid and other aromatic dicarboxylic acids acid, cyclohexanedicarboxylic acid and other alicyclic dicarboxylic acids. Alkyl diesters and diacid chlorides derived from dibasic acids can also be exemplified as polyamide monomers.

Examples of the above-mentioned diamines include ethylenediamine, propylenediamine, butylenediamine, pentamethylenediamine, hexamethylenediamine, heptanediamine, octyldiamine, nonanediamine, decanediamine, and undecanediamine. , dodecanediamine, tridecanediamine, tetradecanediamine, pentadecanediamine, hexadecanediamine, heptadecanediamine, octadecanediamine, nonadecanediamine, two Aliphatic diamines such as decanediamine, 2-methyl-1,5-pentanediamine or 2-methyl-1,8-octanediamine; cyclohexanediamine or 4,4'-diaminobicyclic Alicyclic diamines such as hexylmethane and 4,4'-methylenebis(2-methylcyclohexylamine); aromatic diamines such as xylylenediamine, etc.

From the viewpoint of improving the solubility of monomer A and polymer B, and the particle size of the obtained polyamide microparticles is fine and the particle size distribution is narrowed, 6-aminocaproic acid, 11-aminoundecanoic acid, 12- Aminododecanoic acid, ε-caprolactam, ω-undecalactam, ω-laurolactam, butylenediamine, pentamethylenediamine, hexamethylenediaminedecanediamineundecanediamine, dodecanediamine, Adipic acid, sebacic acid, dodecanedioic acid, more preferably ε-caprolactam, butylenediamine, hexamethylenediamine, decanediamine, adipic acid, sebacic acid, dodecanedioic acid.

Specific examples of the polyamide produced by polymerizing the monomer A include, but are not limited to, the following examples. Polycaprolactam (nylon 6), polyundecylactam (nylon 11), polylaurolactam (nylon 12), polyhexamethylene adipamide (nylon 66), polybutylene adipamide (nylon 46) , Polypentamethylene adipamide (nylon 56), polybutylene sebacamide (nylon 410), polypentamethylene sebacamide (nylon 510), polyhexamethylene sebacamide (nylon 610), poly Hexamethylene lauramide (nylon 612), polydecanediamide sebacyl (nylon 1010), polydecanediamide (nylon 1012), polycaprolactam/polyhexamethylene adipamide copolymer (nylon 6 /66), poly-m-xylylene adipamide (MXD6), poly-m-xylylene sebacylamide (MXD10), poly-p-xylylene sebacamide (PXD10), polyterephthaloyl nonylamide Diamine (nylon 9T), polydecyl terephthalamide (nylon 10T), polyundecyl terephthalamide (nylon 11T), polydodecyl terephthalamide (nylon 12T), poly Pentamethylene terephthalamide/polyhexamethylene terephthalamide copolymer (nylon 5T/6T), poly(2-methylpentamethylene terephthalamide)/polyhexamethylene terephthalamide Amine copolymer (nylon M5T/6T), polyhexamethylene adipamide/polyhexamethylene terephthalamide copolymer (nylon 66/6T), polyhexamethylene adipamide/polyisophthalamide Hexamethylenediamine copolymer (nylon 66/6I), polyhexamethylene adipamide/polyhexamethylene terephthalamide/polyhexamethylene isophthalamide copolymer (nylon 66/6T/6I), Polyterephthaloyl 4,4'-methylenebis(2-methylcyclohexylamine) (nylon MACMT), polyisophthaloyl 4,4'-methylenebis(2-methylcyclohexylamine) Hexylamine) (nylon MACMI), polydodecanoyl 4,4'-methylenebis(2-methylcyclohexylamine) (nylon MACM12), polyterephthaloyl 4,4'-methylenebicyclo Hexylamine (Nylon PACMT), Polyisophthaloyl 4,4'-Methylenebiscyclohexylamine (Nylon PACMI), Polydodecanoyl 4,4'-Methylenebiscyclohexylamine (Nylon PACM12) or above Copolymers of polymers.

The polyamide monomer A contains carboxyl and amino groups. The molar weight of the amino group and the carboxyl group of the above-mentioned monomer A can be calculated based on the mass of the monomer A of the polyamide and the relative molecular weight of the monomer A of the polyamide. Calculate the molar amount and the molar amount of carboxyl group/amino group in 1 molecule of monomer A. However, when the monomer A of the polyamide is a lactam, the molar ratio is calculated using the amounts of amino groups and carboxyl groups obtained by hydrolyzing amide groups. From the viewpoint of increasing the polymerization rate and increasing the molecular weight, the molar ratio of the total amino groups to the total carboxyl groups of the monomers A of the polyamide is preferably 0.990 to 1.035. In addition, when using the polyamide monomer A, the diamine is easy to volatilize out of the polymerization system during polymerization. In order to keep the molar ratio of the diamine and the dibasic acid in balance, the monomer of the polyamide is more preferably The molar ratio of the total amount of amino groups to the total amount of carboxyl groups in A is 0.995 or more, more preferably 1.000 or more. More preferably, the molar ratio of the total amino groups to the total carboxyl groups of the monomers A of the polyamide is 1.020 or less, further preferably 1.010 or less.

In the present invention, in order to dissolve the polyamide monomer A in the polymer B more uniformly, the weight ratio of the monomer A to the polymer B is preferably in the range of 0.1-9. The lower limit of the weight ratio of monomer A/polymer B is more preferably 0.25 or more, still more preferably 0.67 or more. On the other hand, the upper limit of the monomer A/polymer B weight ratio is more preferably 1.5 or less, and still more preferably 1 or less.

In the present invention, in order to dissolve the polyamide monomer A in the polymer B more uniformly, the melting point of the polymer B is preferably between 30°C and 200°C. In this temperature range, polymer B can be prevented from deteriorating during polymerization, and the solubility of polyamide monomer A can also be improved. From this viewpoint, the melting point of the polymer B is more preferably 40 degrees Celsius or higher, and still more preferably 50 degrees Celsius or higher. The melting point of the polymer B is more preferably not higher than 150 degrees Celsius, still more preferably not higher than 100 degrees Celsius.

Likewise, the number average molecular weight of the polymer B is preferably 500 to 500,000 from the viewpoint that the polyamide monomer A is uniformly dissolved in the polymer B. Polymer B within this molecular weight range can facilitate the dissolution of polyamide monomer A while preventing deterioration. The molecular weight of the polymer B is more preferably 1,000 or more, still more preferably 5,000 or more. More preferably, it is 100,000 or less, and still more preferably, it is 50,000 or less. Alternatively, polymer B may be a mixture of polymers of different number average molecular weights.

The polyamide microparticles of the present invention are produced by precipitating polyamide in a state in which the polymer B is dissolved or in a state where the polyamide forms droplets in the polymer B. From this viewpoint, it is preferable that the polymer B does not react with the polyamide monomer and that the polymer B easily dissolves the polyamide monomer A.

Specific examples of such a polymer B include polyethylene glycol, polypropylene glycol, poly-1,4-butylene glycol, poly-1,5-pentanediol, poly-1,6-hexanediol, polyethylene glycol, Glycol-polypropylene glycol copolymer, polyethylene glycol-poly-1,4-butanediol copolymerization, and their single-terminal or both-terminal hydroxyl groups are replaced with methyl, ethyl, propyl, isopropyl, butyl , hexyl, octyl, decyl, dodecyl, hexadecyl, octadecyl and other alkyl groups hydroxyalkylated polymers, polymers obtained by hydroxyalkylated octylphenyl, etc. things etc. In particular, from the viewpoint of excellent compatibility with the polyamide monomer A, polyethylene glycol, polyethylene glycol-polypropylene glycol copolymer, polypropylene glycol, poly-1,4-butylene glycol, and these are preferable. The polymer whose hydroxyl terminal -OH is hydroxyalkylated is more preferably polyethylene glycol, polyethylene glycol-polypropylene glycol copolymer, and most preferably polyethylene glycol. The polymer B may be used alone or in combination of two or more.

In addition, the number average molecular weight of the polymer B is a number average molecular weight obtained by converting a value measured by gel permeation chromatography using water as a solvent in terms of polyethylene glycol. When the polymer B is insoluble in water, the number average molecular weight of the polymer B is a number average molecular weight obtained by converting a value measured by gel permeation chromatography using tetrahydrofuran as a solvent in terms of polystyrene.

Regarding the polymerization of monomer A, polycondensation reaction of aminoalkanoic acid, anionic ring-opening polymerization of lactams and initiators, cationic ring-opening polymerization, polycondensation reaction of aminoalkanoic acid obtained after lactam hydrolysis, dibasic acid and Polymerization is carried out by known methods such as polycondensation reaction of diamines or their salts.

In the latter stage of the above-mentioned polymerization reaction, inert gases such as nitrogen can be circulated or the water generated by the polymerization reaction can be more efficiently excluded from the polymerization reaction system under reduced pressure, so as to promote the progress of polymerization.

In the preparation method of the present invention, in order to better form a uniform solution of polyamide monomer A, polymer B and boric acid compound, solvent C may also be added. As the solvent C, water, diethyl ether, tetrahydrofuran, dimethyl sulfoxide, ethanol, methanol, N-methylpyrrolidone and the like are preferable. The above-mentioned solvent C is more preferably water from the viewpoint of dissolving the monomer A and the polymer B and being the same as condensation water that needs to be discharged out of the system to advance the polycondensation reaction. Taking the polyamide monomer A as 100 parts by weight, the amount of solvent C added is preferably 5-900 parts by weight. The added amount of the solvent C is more preferably 10 parts by weight or more, further preferably 20 parts by weight or more. In addition, the addition amount of the solvent C is more preferably 400 parts by weight or less, and still more preferably 200 parts by weight or less. When the polyamide monomer A is a lactam and the solvent C is water, the water also has the function of hydrolyzing the lactam.

The polymerization temperature is not particularly limited as long as it is within a range in which the polymerization of polyamide can proceed, but from the viewpoint of making the polyamide fine particles closer to a perfect sphere and being able to control the shape with a smooth surface, it is preferable to set the polymerization temperature to the desired The temperature above the crystallization temperature of the polyamide. The polymerization temperature is more preferably the crystallization temperature of the polyamide to be obtained + 5° C. or higher, further preferably the crystallization temperature of the polyamide to be obtained + 15° C. or higher, particularly preferably the crystallization temperature of the polyamide to be obtained + 25° C. ℃ or more. From the viewpoint of preventing polyamide and polymer B from decomposing, the polymerization temperature is preferably the melting point of the polyamide to be obtained + 100° C. or less, more preferably the melting point of the polyamide to be obtained + 50° C. or less, and even more preferably the melting point of the polyamide to be obtained + 50° C. or less. The melting point of polyamide is below +20°C.

In addition, the crystallization temperature of the polyamide microparticles|fine-particles of this invention was measured in the following manner. Using the DSC method, in a nitrogen atmosphere, the temperature of the polyamide particles is raised from 30°C at a rate of 20°C/min until the temperature is 30°C higher than the endothermic peak of polyamide melting, and then kept for 1 minute at a rate of 20°C/min. The temperature was cooled down to 30° C., and the temperature at the apex of the exothermic peak that appeared during this process was taken as the crystallization temperature of the polyamide fine particles. In addition, regarding the melting point of the polyamide microparticles of the present invention, the temperature at the apex of the endothermic peak when the polyamide cooled to 30° C. is raised again at a heating rate of 20° C./min is defined as the melting point of the polyamide microparticles.

The polymerization time can be appropriately adjusted according to the molecular weight of the polyamide microparticles to be obtained. From the viewpoint of increasing the degree of polymerization of the polyamide and preventing the decomposition of the polyamide, it is usually preferably in the range of 0.1 to 70 hours. The lower limit of the polymerization time is more preferably 0.2 hours or more, still more preferably 0.3 hours or more, particularly preferably 0.5 hours or more. The upper limit of the polymerization time is more preferably 50 hours or less, still more preferably 25 hours or less, particularly preferably 10 hours or less.

In the present invention, since polyamide microparticles can be induced homogeneously from a homogeneous solution, fine microparticles can be produced without stirring, but stirring may be performed in order to control the particle size and make the particle size distribution more uniform. As the stirring device, well-known devices such as stirring blades, melt kneaders, homogenizers, etc. can be used. , Spiral etc. The stirring speed is determined according to the type and molecular weight of the polymer B, but it is preferably 0 to 2000 rpm from the viewpoint of uniform heat transfer even in a large-scale device, and from the viewpoint of preventing changes in the mixing ratio due to liquid adhesion to the wall surface. range. The lower limit of the stirring speed is more preferably 10 rpm or more, more preferably 30 rpm or more, particularly preferably 50 rpm or more, and the upper limit of the stirring speed is more preferably 1600 rpm or less, further preferably 1200 rpm or less, particularly preferably 800 rpm or less.

In order to isolate polyamide particles from the mixture of polyamide particles after polymerization and polymer B, after the mixture at the end of polymerization can be added to the poor solvent of polyamide particles, decompression, pressure filtration, decantation, centrifugation, The polyamide microparticles are separated from the above-mentioned mixture by any separation method among known methods such as spray drying. The above-mentioned isolation operation may be a method of isolating the mixture by discharging it into a poor solvent of polyamide fine particles, or a method of isolating after adding a poor solvent of polyamide fine particles to a reaction tank, or the like. From the viewpoint of preventing the polyamide fine particles from fusing and adhering to expand the particle size distribution, the above-mentioned isolation method is preferably performed after cooling below the melting point of the polyamide fine particles, more preferably after cooling below the crystallization temperature.

The poor solvent refers to a solvent whose interaction parameter χ with polyamide is 0.5 or more. It is sufficient as long as the monomer A and the polymer B can be dissolved and the polyamide fine particles can not be dissolved. As such a solvent, alcohols, such as methanol, ethanol, and isopropanol, and water are mentioned.

In the present invention, the polyamide microparticles can be washed by a known method after isolation to remove attachments and inclusions on the polyamide microparticles. Slurry washing etc. can be used for said washing, and it can heat suitably as needed. The solvent used for washing is not limited as long as it dissolves the monomer A and the polymer B and does not dissolve the polyamide, but methanol, ethanol, isopropanol, water, etc. are preferable from the viewpoint of economical efficiency. Most preferred is water. In addition, the washed polyamide fine particles may be dried. For example, known drying methods such as air drying, hot air drying, heat drying, reduced-pressure drying, and freeze drying can be selected.

Through the above method, polyamide microparticles with various particle sizes, narrow particle size distribution, high sphericity and high molecular weight can be produced. At the same time, due to the addition of boric acid compounds, the polyamide microparticles will characteristically contain boron element.

In the present invention, boric acid compounds are added to improve the dispersibility of polyamide droplets in polymer B, and these boric acid compounds are present in polyamide microparticles and polymer B. Therefore, the boron element derived from the boric acid compound contained in the polyamide microparticles is less than the boron element contained in the added boric acid compound. The polyamide microparticles of the present invention contain 5 ppm to 20000 ppm of boron. Within this range, dispersion of polyamide liquid droplets in polymer B can be facilitated and the degree of polymerization of polyamide microparticles can be increased. The upper limit of the boron element in the polyamide microparticles is preferably 600 ppm or less, more preferably 300 ppm or less. The lower limit of the boron element in the polyamide microparticles is preferably 10 ppm or more, more preferably 50 ppm or more.

For the content of boron element in polyamide microparticles, the measurement method is as follows: accurately weigh polyamide microparticles, dissolve them in a mixed solution of sulfuric acid and nitric acid, decompose them by microwave heating, and dilute them with water. The resulting solution was measured using an inductively coupled plasma (ICP) emission spectrometer. The device used is PS3520VDDII produced by Hitachi high-tech science.

In the present invention, the volume-based average particle size/number-based average particle size of the particle size distribution of the polyamide fine particles is 1.00 to 2.50. Within this range, the fluidity of the particles is good. If the volume-based average particle size/number-based average particle size exceeds 2.50, that is, the particle size distribution is wide, which will lead to poor fluidity of the particles and make it difficult to meet subsequent applications. For example, when polyamide particles are applied to laser sintering 3D printing, it is necessary to fill the particles evenly, and the particles in the above range have good fluidity, can be filled evenly, and melt evenly, so that the surface of the 3D printed molding is smooth. high. The volume-based average particle diameter/number-based average particle diameter is preferably 2.00 or less, more preferably 1.50 or less. In addition, its lower limit value is theoretically 1.

Regarding the particle size distribution of the above-mentioned polyamide microparticles, there is an evaluation standard of (D90-D10)/D50 in addition to the evaluation standard of volume-based average particle size/number-based average particle size. (D90-D10)/D50 of the polyamide microparticles in the present invention is preferably 2.0 or less. D50, D90, and D10 in (D90-D10)/D50 are all measured on a volume basis, and (D90-D10)/D50 is different from the volume-based average particle size/number-based average particle size. convert each other. When evaluating the particle size distribution using (D90-D10)/D50, the smaller the value of (D90-D10)/D50, the more uniform the particles. When the particles are used for laser sintering 3D printing, it is necessary to fill the particles evenly, and the particles within the above range have good fluidity, can be filled evenly, and melt evenly, so that the surface of the 3D printed molding has high smoothness. From this point of view, (D90-D10)/D50 of the polyamide fine particles is preferably 1.6 or less.

For the polyamide microparticles, considering the requirements on the particle size of the polyamide microparticles in practical applications, the volume-based average particle diameter MV is preferably 10 microns to 150 microns. The lower limit of the volume-based average particle diameter MV is more preferably 20 micrometers or more, and still more preferably 30 micrometers or more. In addition, the upper limit of the volume-based average particle diameter MV is more preferably 115 micrometers or less, and still more preferably 94 micrometers or less. In the application of particles for laser sintering 3D printing, the particle size will affect the surface smoothness of the molding. If the particle size is maintained in the above range, the particles can maintain good fluidity while the surface of the molding is smooth.

Regarding the volume-based average particle diameter MV of the polyamide fine particles, the number-based average particle diameter MN, the particle diameter D50 when the cumulative frequency is 50%, the particle diameter D90 when the cumulative frequency is 90%, and the particle size when the cumulative frequency is 10%. The particle diameter D10 can be measured by laser diffraction particle size analysis. The instrument used was Microtrace S3500 with deionized water as dispersant.

The polyamide microparticles described in the present invention have the shape of a true sphere or an approximate sphere, so they have good fluidity and sliding properties, and can satisfy the good fluidity of the microparticles in applications such as cosmetics, coatings, and 3D printing. , Sliding requirements. The polyamide microparticles of the present invention preferably have a sphericity of 70 or more. In the application of laser sintering 3D printing, the powder is required to have high fluidity, uniformity of powder spreading, good appearance of the molded product and high mechanical strength in the molding process. From this point of view, the positive sphericity is preferably above 80 , more preferably 90 or more. In addition, its upper limit value is 100. As for the measurement method of the sphericity of polyamide microparticles, 30 particles are randomly observed from scanning electron micrographs, and determined from the short and long diameters according to the following mathematical formula.

[mathematical formula 1]

Among them, S: sphericity, a: long diameter, b: short diameter, n: number of measurements 30.

In the present invention, the molar concentration of amino groups/molar concentration of carboxyl groups in the polyamide microparticles is preferably 0.06 to 2.00. For the polyamide microparticles meeting this range, the total molar weight of the amino groups and the total molar weight of the carboxyl groups of the polyamide monomer A can maintain a proper balance during the production process, so that the polyamide constituting the polyamide microparticles has a high molecular weight. The upper limit of the molar concentration of amino groups/molar concentration of carboxyl groups in the polyamide microparticles is preferably 1.50 or less, more preferably 1.20 or less. The lower limit of the molar concentration of amino groups/molar concentration of carboxyl groups in the polyamide microparticles is preferably 0.1 or more, more preferably 0.2 or more.

For the determination of the molar concentration C _NH2 of amino groups in polyamide microparticles, the polyamide microparticles are dissolved in a phenol/ethanol mixed solution and titrated with a hydrochloric acid solution of known concentration, and the molar concentration C _NH2 of the amino groups obtained has a unit of ×10 ^-5 mol/g. For the determination of the molar concentration _{CCOOH of carboxyl groups in polyamide microparticles, dissolve polyamide microparticles in benzyl alcohol and titrate with potassium hydroxide/ethanol solution of known concentration, the molar concentration C COOH of} carboxyl groups obtained has a unit of ×10 ^-5 mol/g. The number-average molecular weight Mn of the polyamide particle is calculated by the molar concentration C _NH of the amino group in the polyamide particle and the molar concentration C _COOH of the carboxyl group, and the calculation formula is as follows:

[mathematical formula 2]

The number average molecular weight of the polyamide microparticles in the present invention is preferably 5,000-50,000. Control within this range is beneficial for various subsequent uses. For example, in laser sintering 3D printing, the polyamide particles controlled in this range can melt well and uniformly, and the molded product can maintain high mechanical strength. The upper limit of the number average molecular weight of the polyamide fine particles is more preferably 30,000 or less, still more preferably 25,000 or less. In addition, the lower limit of the number average molecular weight of the polyamide microparticles is more preferably 8,000 or more, and still more preferably 10,000 or more.

Since the present invention can obtain polyamide microparticles with suitable particle size, narrow particle size distribution, high sphericity and high molecular weight, it can be applied to 3D printing, cosmetics, coatings and the like.

For example, when the polyamide particles of the present invention are applied to laser sintering 3D printing, due to the narrow particle size distribution and high positive sphericity of the particles, they can be filled evenly and have good fluidity, so that the surface smoothness of the 3D printed molding is high , due to the high molecular weight of its polyamide, it can make the final molded product have high mechanical strength.

When the polyamide microparticles of the present invention are applied to cosmetics, since the particle size distribution of the microparticles is narrow and the degree of sphericity is high, it can bring delicate touch to the cosmetics.

detailed description

The present invention will be further described below in conjunction with embodiment, but the present invention is not limited to these embodiments.

The descriptions of the tests involved in the examples and comparative examples are as follows:

(1) Determination method of amino molar concentration

Accurately weigh the polyamide microparticles obtained in each embodiment and comparative example, and dissolve them in a mixed solution with a volume ratio of phenol/ethanol of 85/15 to configure a solution of 0.01 g/ml, and use 0.02 mol/L hydrochloric acid solution titration. The molar concentration of amino groups is expressed as C _NH2 , and the unit is ×10 ^-5 mol/g.

(2) The assay method of carboxyl molar concentration:

Accurately weigh the polyamide microparticles obtained in each embodiment and comparative example, and dissolve it in benzyl alcohol to configure a 0.01g/ml solution, and use 0.02mol/L of potassium hydroxide in ethanol at 190°C Solution titration. The molar concentration of carboxyl groups is expressed as C _COOH , and the unit is ×10 ^-5 mol/g.

(3) The number-average molecular weight Mn of the polyamide microparticles is calculated by the molar concentration C _NH2- of the amino groups in the polyamide microparticles and the molar concentration _CCOOH of the carboxyl groups, and the calculation formula is as follows:

[mathematical formula 2]

(4) Measurement method of boron content in polyamide particles:

Accurately weigh the polyamide particles, dissolve them in the mixed solution of sulfuric acid and nitric acid, decompose by microwave heating and make up to volume with water. The resulting solution was measured using an inductively coupled plasma (ICP) emission spectrometer. The device used is PS3520VDDII produced by Hitachi high-tech science.

(5) Determination method of particle size and particle size distribution of polyamide particles:

Laser diffraction particle size analysis was used. The instrument used was Microtrace S3500 with deionized water as dispersant. Use this method to measure the volume-based average particle size MV, the number-based average particle size MN, the particle size D50 when the cumulative frequency is 50%, the particle size D90 when the cumulative frequency is 90%, and the particle size when the cumulative frequency is 10%. diameter D10.

(6) Determination method of positive sphericity of polyamide particles:

30 particles were randomly observed from the scanning electron micrograph, and their minor diameter and major diameter were determined according to the following mathematical formula.

[mathematical formula 1]

Among them, S: sphericity, a: long diameter, b: short diameter, n: number of measurements 30.

(7) Evaluation method for the dispersibility of polyamide droplets in polymer B:

The mixture of polyamide and polymer B after polymerization in Examples and Comparative Examples was discharged into water and stirred, polymer B was dissolved in water and polyamide fine particles were dispersed in water. If the particles are basically uniformly dispersed in water, after the dispersion passes through a sieve with a pore size of 1 mm, the mass of the solids remaining on the sieve accounts for less than 10% of the mass of the polyamide particles, and the polyamide droplets are in the polymer during the polymerization process. The dispersibility in B was good, and the evaluation was 0. If most of the particles are uniformly dispersed in water, and after the dispersion passes through a sieve with a pore size of 1 mm, the mass of solids remaining on the sieve accounts for more than 10% and less than 50% of the mass of the polyamide particles, and the polyamide during the polymerization process The dispersibility of liquid droplets in polymer B was evaluated as Δ. In addition, if the dispersion passes through a sieve with a pore size of 1 mm, the solid mass remaining on the sieve accounts for more than 50% of the mass of the polyamide microparticles, and even no microparticles can be recovered from the dispersion, the polyamide microparticles will be in the polymer B. The dispersibility in the evaluation is ×.

(8) The assay method of the number average molecular weight of polymer B:

The number average molecular weight of the polymer B was calculated by comparing it with a calibration curve obtained from polyethylene glycol using gel permeation chromatography. A measurement sample was prepared by dissolving about 3 mg of polymer B in about 6 g of water.

Device: LC-10A series manufactured by Shimadzu Corporation

Column: TSKgelG3000PWXL manufactured by Tosoh Corporation

Mobile phase: 100mmol/L sodium chloride aqueous solution

Flow rate: 0.8ml/min

Temperature: 40°C

Detection: Differential refractometer.

The raw material used in embodiment and comparative example is as follows:

Decanediamine: Wuxi Xingda Nylon Co., Ltd.

Dodecanedioic acid: Shanghai Cathay Biotechnology Co., Ltd.

12-aminododecanoic acid: TCI (Shanghai) Chemical Industry Development Co., Ltd.

Boric acid: Sigma-Aldrich (Shanghai) Trading Co., Ltd.

Phosphoric acid: TCI (Shanghai) Chemical Industry Development Co., Ltd.

Polyethylene glycol 20000 (Mn=20000): Aoki Oil Industry Co., Ltd.

Polyethylene glycol 10000 (Mn=10000): Sigma-Aldrich (Shanghai) Trading Co., Ltd.

[Example 1]

Add 154.05g decanediamine, 204.09g dodecanedioic acid, 180g polyethylene glycol 10000, 180g polyethylene glycol 20000, 0.36g boric acid, 1080g deionized water into the reactor, seal the reactor and replace it with nitrogen three times. Heating was started after the heater temperature of the reactor was set to 230°C. When the pressure in the reactor reaches 1.0MPa, the water vapor in the reactor is released through the vent valve while the pressure in the reactor is maintained at 1.0MPa until the temperature in the reactor rises to 190°C. When the temperature in the kettle reaches 190°C, the pressure in the kettle is gradually reduced from 1.0 MPa to normal pressure within 50 minutes. During this process, the temperature of the heater in the reactor is set to 200°C. Maintained at 190°C. Then, a nitrogen stream was introduced into the kettle, and melt polymerization was carried out for 120 minutes under a nitrogen stream. After the polymerization, the mixture was spit out into water from the discharge valve of the reactor. The resulting slurry was passed through a 1 mm sieve to remove aggregates. The sieved slurry is filtered, the filtrate is recovered, dispersed in water again, stirred and washed, filtered again, and the washed filtrate is recovered. The filtrate was dried at 80° C. for 12 hours to obtain 195 g of polyamide 1012 powder. In addition, 40 g of aggregates remained on the 1 mm sieve. The molar concentration of amino groups in the obtained powder was 4×10 ^-5 mol/g, and the molar concentration of carboxyl groups was 6×10 ^-5 mol/g. The calculated number average molecular weight of the polyamide 1012 powder was 20,000. According to the scanning electron microscope observation, the polyamide 1012 powder is in the shape of spherical particles, and the true sphericity is 95. The volume reference average particle diameter MV of the obtained polyamide 1012 particles measured by the laser diffraction particle size analysis method is 211.33 microns, the number reference average particle diameter MN is 121.79 microns, and the particle diameter D50 when the frequency is accumulated at 50% is 207.45 microns, and the frequency is 207.45 microns. The particle diameter D90 at the cumulative frequency of 90% is 297.44 microns, and the particle diameter D10 at the cumulative frequency of 10% is 115.57 microns. The volume-based average particle diameter/number-based average particle diameter is 1.74, and (D90-D10)/D50 is 0.88. The properties of the obtained polyamide 1012 fine particles are summarized in Table 1.

[embodiment 2-8, comparative example 1]

Change the add-on of boric acid as shown in table 1, other operation is all the same with embodiment 1 except this. The properties of the obtained polyamide 1012 microparticles are shown in Table 1.

[Comparative example 2]

As shown in Table 1, boric acid was changed to phosphoric acid, and the addition amount was as shown in Table 1. Other operations were the same as in Example 1. The properties of the obtained polyamide 1012 microparticles are shown in Table 1.

[Table 1]

Compared with Comparative Example 1 in Examples 1-8, it can be seen that under the condition of not adding a boric acid compound, the dispersion of the particles is very poor, and only a small amount of polyamide 1012 particles are recovered, so it can be seen that adding a boric acid compound is beneficial to polyamide Dispersion of amide microparticles in polymer B. In addition, it can be seen from Comparative Example 2 that although phosphoric acid and boric acid are both inorganic acids and are commonly used additives in the synthesis of polyamides, they do not have the effect of promoting the dispersion of polyamide particles in polymer B.

[Embodiment 4, Embodiment 9-13]

Except that raw materials are changed as shown in Table 2, all the other operations are the same as in Example 1. The properties of the obtained polyamide 1012 microparticles are shown in Table 2.

[Table 2]

According to Example 4 and Examples 9 to 13, it can be known that the number average molecular weight of polyamide microparticles can be increased by adjusting the molar ratio of total amino groups/total carboxyl groups of polyamide monomer A under the premise of adding boric acid compound.

[embodiment 14-17, comparative example 3]

As shown in Table 3, the polyamide monomer was changed to 12-aminododecanoic acid, the polymer B was changed to polyethylene glycol 20000, and the amount of deionized water was changed to 336 g. Heating was started after the heater temperature of the reactor was set to 230°C. When the pressure in the reactor reaches 1.0MPa, the water vapor in the reactor is released through the vent valve while the pressure in the reactor is maintained at 1.0MPa until the temperature in the reactor rises to 190°C. When the temperature in the kettle reached 190°C, the pressure in the kettle was gradually reduced from 1.0 MPa to normal pressure within 50 minutes, and the temperature in the kettle was 210°C when reaching normal pressure. After reaching normal pressure, the polymerization time was changed to 60 minutes, and the weight ratio of polyamide monomer A to polymer B was changed. Except for this, the same operation as in Example 1 was carried out. The properties of the obtained polyamide 12 microparticles are shown in Table 3.

[table 3]

Examples 14-17 are compared with Comparative Example 3, which does not contain polymer B, and as a result, polyamide 12 cannot form microparticles. By adjusting the weight ratio of the polyamide monomer A to the polymer B, the polyamide monomer A can be more uniformly dissolved in the polymer B while controlling the amount of the polymer B used and reducing the production cost of the microparticles.

Claims (21)

A method for preparing polyamide microparticles, characterized in that monomer A of polyamide is polymerized in the presence of polymer B, a boric acid compound is added at any time before the end of the polymerization, and the polyamide is dissolved in the polymer B In the state or in the state in which the droplets formed by polyamide are dispersed in the polymer B, fine particles containing polyamide are precipitated. The method for preparing polyamide microparticles according to claim 1, wherein the boric acid compound is added in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the polyamide monomer A. The method for preparing polyamide microparticles according to claim 2, wherein, taking the polyamide monomer A as 100 parts by weight, the added amount of the boric acid compound is 0.4 parts by weight to 5 parts by weight. The method for preparing polyamide microparticles according to claim 1, wherein the boric acid compound is at least one of boric acid, borate, and organic boric acid compound. The preparation method of polyamide particles according to claim 1, wherein the monomer A of the polyamide is selected from diamines with 2-20 carbon atoms and dibasic acids with 2-20 carbon atoms At least one of combinations of , aminoalkanoic acids having 6-12 carbon atoms, lactams having 6-12 carbon atoms, mixtures of the above monomers and salts thereof. The method for preparing polyamide microparticles according to claim 1, wherein the molar ratio of total amino groups to total carboxyl groups of monomer A of the polyamide, that is, total amino groups/total carboxyl groups, is 0.990˜1.035. The method for preparing polyamide microparticles according to claim 1, wherein the weight ratio of the monomer A of the polyamide to the polymer B, ie monomer A/polymer B, is 0.1-9.0. The method for preparing polyamide microparticles according to claim 1, wherein the melting point of the polymer B is 30°C to 200°C. The method for preparing polyamide microparticles according to claim 1, wherein the number average molecular weight of the polymer B is 500-500,000. The preparation method of polyamide microparticles according to claim 1, wherein, said polymer B is polyethylene glycol, polypropylene glycol, poly-1,4-butylene glycol, polyethylene glycol-polypropylene glycol copolymer, and At least one of polymers whose hydroxyl terminal -OH is hydroxyalkylated. The preparation method of polyamide microparticles according to claim 1, wherein a solvent C is added for polymerization. The method for preparing polyamide microparticles according to claim 11, wherein the solvent C is water. A polyamide microparticle characterized by containing boron element, and having a volume-based average particle diameter/number-based average particle diameter of 1.00 to 2.50. The polyamide microparticles according to claim 13, characterized in that the content of the boron element is 5 ppm to 20000 ppm relative to the weight of the polyamide microparticles. The polyamide microparticles according to claim 13, characterized in that the content of the boron element is 5 ppm to 600 ppm relative to the weight of the polyamide microparticles. The polyamide microparticles according to claim 13, wherein the volume-based average particle diameter/number-based average particle diameter is 1.00 to 2.00. The polyamide microparticles according to claim 13, which have a sphericity of 70-100. The polyamide microparticles according to claim 13, wherein the molar concentration of amino groups/molar concentration of carboxyl groups in the polyamide microparticles is 0.06 to 2.00. The polyamide microparticles according to claim 13, wherein the volume-based average particle diameter MV is 10 micrometers to 150 micrometers. The polyamide fine particles according to claim 13, wherein (D90-D10)/D50 is 2.0 or less. The polyamide microparticles according to claim 13, wherein the polyamide microparticles have a number average molecular weight of 5,000 to 50,000.