Polyamide 12 powder with high sphericity degree and preparation method thereof

Abstract

The invention discloses polyamide 12 powder with high sphericity degree and a preparation method thereof, and belongs to the technical field of polymer powder materials. The preparation method comprises the following steps: adding a modifier, a compatibilizer, a filler and a first solvent into a container, and ultrasonically dispersing uniformly at a certain temperature to obtain a mixed solution A; fully washing the mixed solution A with deionized water, and then drying to obtain modified filler particles; weighing polyamide 12 granules, modified filler particles and a second solvent, adding into a reaction kettle, heating at a certain temperature, and uniformly stirring to fully dissolve polyamide 12, so as to obtain a mixed solution B; cooling the mixed solution B at a certain rate to form a turbid liquid; and carrying out suction filtration on the turbid liquid, fully washing with deionized water, and then drying to obtain polyamide 12 powder with high sphericity degree. The preparation method has the beneficial effects that the good sphericity degree of the powder can be ensured, and the uniform dispersion of the filling agent can also be ensured; the preparation process is simple and easy to industrialize.

Description

Technical Field

[0001] The invention relates to the technical field of polymer powder materials, and in particular to a polyamide 12 powder with high sphericity and a preparation method thereof. Background Art

[0002] Polyamide 12 powder has become the most widely used material in the field of 3D printing due to its excellent chemical and thermal stability and printing quality. With the further application of polyamide 12 powder in aerospace, automobile and other fields, the requirements for 3D printed parts made of polyamide 12 powder are getting higher and higher. Single polyamide 12 powder can no longer meet the requirements, and fillers need to be added to improve the performance of polyamide 12 powder.

[0003] In the related art, solvent precipitation is a commonly used method for preparing polyamide 12 powder, which can be used to prepare powder with good sphericity. However, blending fillers during the preparation process will cause the sphericity of the powder to decrease, thereby affecting the processing performance of the powder.

[0004] Chinese patents CN106146864 A and CN106633373 A respectively disclose functional modification of graphene oxide and carbon nanotubes and then blending with polypropylene powder. However, the reinforcing effect is inferior to that of the one-step preparation of the polymer-filler system. Summary of the invention

[0005] The object of the present invention is to provide a polyamide 12 powder with high sphericity and a preparation method thereof, which introduces groups on the surface of carbon black in a non-covalent modification manner to achieve simple and efficient carbon black modification, and then prepares polyamide 12 powder based on the modified carbon black, thereby solving at least one technical problem involved in the background technology.

[0006] In order to solve the above-mentioned technical problems, the present invention is achieved as follows:

[0007] The present invention provides a method for preparing polyamide 12 powder with high sphericity, comprising the following steps:

[0008] Step S1: Add 3-8 parts of a modifier, 3-8 parts of a compatibilizer, 2-6 parts of a filler, and 78-92 parts of a first solvent into a container by weight, and disperse them uniformly by ultrasonication at a certain temperature to obtain a mixed solution A;

[0009] Step S2: washing the mixed solution A with deionized water, and then drying to obtain modified filler particles;

[0010] Step S3: 5-15 parts of polyamide 12 pellets, 0.5-3 parts of modified filler particles, and 82-94.5 parts of the second solvent are weighed by mass and added into a reaction kettle, and heated and stirred at a certain temperature to fully dissolve the polyamide 12 to obtain a mixed solution B;

[0011] Step S4: Cooling the mixed solution B at a certain rate to form a suspension;

[0012] Step S5: The suspension is filtered and washed with deionized water, and then dried to obtain polyamide 12 powder with high sphericity.

[0013] Optionally, in step S1, the modifier is polyvinyl pyrrolidone; the compatibilizer is ethylene-acrylic acid copolymer; the filler is carbon black; and the first solvent is any one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0014] Optionally, in step S1, the ultrasonic temperature is 20-50°C, and the ultrasonic dispersion time is 5-12h.

[0015] Optionally, in step S2, the drying temperature is 40-60°C.

[0016] Optionally, in step S3, the second solvent is any one of N,N-dimethylformamide and N,N-dimethylacetamide, the heating temperature is 140-160° C., the stirring rate is 400-1000 rpm, and the stirring time is 1-2 h.

[0017] Optionally, in step S4, the cooling rate is 8-15°C / min.

[0018] Optionally, in step S5, the drying temperature is 60-80°C.

[0019] The invention also provides a polyamide 12 powder with high sphericity, which is prepared by adopting the preparation method.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention utilizes ultrasonic vibration and cavitation effects to synergistically modify carbon black with a modifier, polyvinyl pyrrolidone, and a compatibilizer, ethylene-acrylic acid copolymer. The addition of the modifier, on the one hand, causes charge adsorption with the carboxyl group in the compatibilizer, so that the compatibilizer and the modifier chain segments are entangled together; on the other hand, the active polymer chain in the modifier modifies the surface of carbon black through non-covalent bonds, thereby increasing the surface activity of carbon black and improving the dispersibility of carbon black in the solvent; the carboxylic acid group in the compatibilizer forms a hydrogen bond with the terminal amino group in the polyamide 12 molecule, thereby reducing the interfacial energy between the two and further ensuring that the carbon black particles as the dispersed phase are evenly distributed in the matrix; in the process of preparing polyamide 12 powder, polyamide 12 droplets are more inclined to perform liquid-liquid phase separation in the area with low interfacial energy, thereby achieving coating of the modified carbon black.

[0022] 2. The powder prepared by the present invention can ensure both good sphericity of the powder and uniform dispersion of the filler; the preparation method provided by the present invention has a simple preparation process and is easy to realize industrialization. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, among which:

[0024] Figure 1 is a SEM image of spherical polyamide 12 powder prepared by the method provided by the present invention;

[0025] Figure 2 is a SEM image of the polyamide 12 powder prepared in Comparative Example 1;

[0026] Figure 3 This is the SEM image of the polyamide 12 powder prepared in Comparative Example 2. DETAILED DESCRIPTION

[0027] The technical solutions in the present invention will be described clearly and completely below in combination with the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] The present invention provides a method for preparing a polyamide 12 powder with high sphericity, comprising the following steps:

[0029] Step S1: Add 3-8 parts of a modifier, 3-8 parts of a compatibilizer, 2-6 parts of a filler, and 78-92 parts of a first solvent into a flask by mass, and perform ultrasonic dispersion at 20-50° C. for 5-12 hours to obtain a uniform mixed solution A;

[0030] Specifically, the modifier is polyvinyl pyrrolidone; the compatibilizer is ethylene-acrylic acid copolymer; the filler is carbon black; and the first solvent is any one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0031] Step S2: The mixed solution A is fully washed with deionized water and dried at a temperature of 40-60° C. to obtain modified filler particles;

[0032] Step S3: weighing 5-15 parts of polyamide 12 pellets, 0.5-3 parts of modified filler particles, and 82-94.5 parts of the second solvent by mass, adding them into a reaction kettle, heating at a temperature of 140-160° C. and stirring at a stirring rate of 400-1000 rpm for 1-2 hours until uniform, so that the polyamide 12 is fully dissolved, to obtain a mixed solution B;

[0033] Specifically, the second solvent is any one of N,N-dimethylformamide and N,N-dimethylacetamide.

[0034] Step S4: cooling the mixed solution B at a cooling rate of 8-15°C / min to form a suspension;

[0035] Step S5: The suspension is filtered and washed with deionized water, and dried at 60-80° C. to obtain polyamide 12 powder with high sphericity.

[0036] Combination Figure 1 As shown, it can be seen that the polyamide 12 powder prepared by the method provided by the present invention has high sphericity.

[0037] The polyamide 12 powder with high sphericity provided by the present invention and the preparation method thereof are described in detail below with reference to specific embodiments and comparative examples.

[0038] Example 1

[0039] Embodiment 1 provides a method for preparing polyamide 12 powder with high sphericity, comprising the following steps:

[0040] Step S1: Add 4 parts of ethylene-acrylic acid copolymer, 4 parts of polyvinyl pyrrolidone, 3 parts of carbon black, and 89 parts of N,N-dimethylpyrrolidone into a flask by mass, and perform ultrasonic treatment at 30° C. for 8 h to obtain a uniform mixed solution A;

[0041] Step S2: After the mixed solution A is fully washed with deionized water, it is dried at 45° C. to remove moisture, thereby obtaining modified carbon black particles;

[0042] Step S3: 7 parts of polyamide 12 pellets, 1 part of modified carbon black particles, and 92 parts of N,N-dimethylformamide were weighed by mass and added into a reaction kettle, and stirred at 800 rpm for 1 hour at a temperature of 150° C. to fully dissolve the polyamide 12, thereby obtaining a mixed solution B;

[0043] Step S4: cooling the mixed solution B to 80° C. at a cooling rate of 8° C. / min to form a suspension;

[0044] Step S5: The suspension is filtered and washed with deionized water, and dried at 70° C. to obtain a highly spherical polyamide 12 powder.

[0045] Example 2

[0046] Embodiment 2 provides a method for preparing polyamide 12 powder with high sphericity, comprising the following steps:

[0047] Step S1: Add 5 parts of ethylene-acrylic acid copolymer, 5 parts of polyvinyl pyrrolidone, 2 parts of carbon black and 88 parts of N,N-dimethylformamide into a reaction kettle by mass, and perform ultrasonic treatment at 35° C. for 8 hours to obtain a uniform mixed solution A;

[0048] Step S2: After the mixed solution A is fully washed with deionized water, it is dried at 45° C. to obtain modified carbon black particles;

[0049] Step S3: 6 parts of polyamide 12 pellets, 1 part of modified carbon black particles, and 93 parts of N,N-dimethylformamide were weighed by mass and added into a reaction kettle, and stirred at 700 rpm for 1 hour at a temperature of 145° C. to fully dissolve the polyamide 12, thereby obtaining a mixed solution B;

[0050] Step S4: cooling the mixed solution B to 80° C. at a cooling rate of 10° C. / min to obtain a suspension;

[0051] Step S5: The suspension is filtered and washed with deionized water, and dried at 70° C. to obtain polyamide 12 powder with high sphericity.

[0052] Example 3

[0053] Embodiment 3 provides a method for preparing polyamide 12 powder with high sphericity, comprising the following steps:

[0054] Step S1: Add 6 parts of ethylene-acrylic acid copolymer, 6 parts of polyvinyl pyrrolidone, 2 parts of carbon black and 86 parts of dimethyl sulfoxide into a reaction kettle by mass, and perform ultrasonic treatment at 40° C. for 12 hours to obtain a uniform mixed solution A;

[0055] Step S2: washing the obtained mixed solution A with deionized water, and drying it at 50° C. to obtain modified carbon black particles;

[0056] Step S3: 8 parts of polyamide 12 pellets, 1.5 parts of modified carbon black particles, and 90.5 parts of N,N-dimethylacetamide were weighed by mass and added into a reaction kettle, and stirred at 900 rpm for 2 hours at a temperature of 155° C. to fully dissolve the polyamide 12, thereby obtaining a mixed solution B;

[0057] Step S4: cooling the mixed solution B to 80° C. at a cooling rate of 10° C. / min to obtain a suspension;

[0058] Step S5: The suspension is filtered and washed with deionized water, and dried at 70° C. to obtain polyamide 12 powder with high sphericity.

[0059] Comparative Example 1

[0060] Comparative Example 1 provides a method for preparing polyamide 12 powder, comprising the following steps:

[0061] Step S1: Add 3 parts of carbon black and 97 parts of N,N-dimethylacetamide into a reaction kettle by mass, and perform ultrasonic treatment at 40° C. for 12 hours to obtain a mixed solution A;

[0062] Step S2: After the mixed solution A is fully washed with deionized water, it is dried at 50° C. to obtain dry carbon black;

[0063] Step S3: 8 parts of polyamide 12 pellets, 1.5 parts of dried carbon black, and 90.5 parts of N,N-dimethylacetamide were weighed by mass and added into a reaction kettle, and stirred at 900 rpm for 2 hours at a temperature of 155° C. to fully dissolve the polyamide 12, thereby obtaining a mixed solution B;

[0064] Step S4: cooling the mixed solution B to 80° C. at a cooling rate of 10° C. / min to obtain a suspension;

[0065] Step S5: The suspension is filtered and washed with deionized water, and dried at 70° C. to obtain polyamide 12 powder.

[0066] Recombination Figure 2As shown, it can be seen that the preparation method provided in Comparative Example 1 only ultrasonically disperses the carbon black and does not modify the carbon black. Therefore, the effect is poor and the sphericity of the obtained polyamide 12 powder is poor.

[0067] Comparative Example 2

[0068] Comparative Example 1 provides a method for preparing polyamide 12 powder, comprising the following steps:

[0069] Step S1: adding 1.5 parts of carbon black, 8 parts of polyamide 12 pellets, and 90.5 parts of N,N-dimethylacetamide into a reaction kettle, stirring at 900 rpm for 2 hours at a temperature of 155° C. to fully dissolve the polyamide 12, and obtaining a mixed solution;

[0070] Step S2: cooling the mixed solution to 80° C. at a cooling rate of 10° C. / min to obtain a suspension;

[0071] Step S3: The suspension is filtered and washed with deionized water, and dried at 70° C. to obtain polyamide 12 powder.

[0072] Recombination Figure 3 As shown, it can be seen that the preparation method provided in Comparative Example 2 directly adds carbon black, which has poor effect, and the obtained polyamide 12 powder also has poor sphericity.

[0073] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0074] In addition, it should be noted that the scope of the methods and preparation methods in the embodiments of the present invention is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved. For example, the described methods may be performed in an order different from that described, and various steps may be added, omitted, or combined. In addition, features described with reference to certain examples may be combined in other examples.

[0075] The embodiments of the present invention are described above, but the present invention is not limited to the above-mentioned specific implementation modes. The above-mentioned specific implementation modes are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, all of which are protected by the present invention.

Claims

1. A method for preparing polyamide 12 powder with high sphericity, characterized in that: The steps include: Step S1: Add 3-8 parts of a modifier, 3-8 parts of a compatibilizer, 2-6 parts of a filler, and 78-92 parts of a first solvent into a container by weight, and disperse them uniformly by ultrasonication at a certain temperature to obtain a mixed solution A; Step S2: washing the mixed solution A with deionized water, and then drying to obtain modified filler particles; Step S3: 5-15 parts of polyamide 12 pellets, 0.5-3 parts of modified filler particles, and 82-94.5 parts of the second solvent are weighed by mass and added into a reaction kettle, and heated and stirred at a certain temperature to fully dissolve the polyamide 12 to obtain a mixed solution B; Step S4: Cooling the mixed solution B at a certain rate to form a suspension; Step S5: The suspension is filtered and washed with deionized water, and then dried to obtain polyamide 12 powder with high sphericity.

2. The preparation method according to claim 1, characterized in that: In step S1, the modifier is polyvinyl pyrrolidone; the compatibilizer is ethylene-acrylic acid copolymer; the filler is carbon black; and the first solvent is any one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

3. The preparation method according to claim 1 or 2, characterized in that: In step S1, the ultrasonic temperature is 20-50°C, and the ultrasonic dispersion time is 5-12h.

4. The preparation method according to claim 1, characterized in that: In step S2, the drying temperature is 40-60°C.

5. The preparation method according to claim 1, characterized in that: In step S3, the second solvent is any one of N,N-dimethylformamide and N,N-dimethylacetamide, the heating temperature is 140-160°C, the stirring rate is 400-1000 rpm, and the stirring time is 1-2h.

6. The preparation method according to claim 1, characterized in that: In step S4, the cooling rate is 8-15°C / min.

7. The preparation method according to claim 1, characterized in that: In step S5, the drying temperature is 60-80°C.

8. A polyamide 12 powder with high sphericity, characterized in that: The preparation method is described in any one of claims 1 to 7.

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