A branched flow agent, a preparation method thereof, a rapid forming nylon 6 and application

Abstract

The application discloses a branched flow agent and a preparation method thereof, rapid forming nylon 6 and application, and relates to the technical field of nylon materials. The branched flow agent comprises the following steps: mixing a triamine monomer with a long carbon chain monocarboxylic acid monomer, performing reaction by using a gradient temperature rising method, and drying to obtain a product with a branched structure. The branched flow agent provided by the application is a low-viscosity flow regulator containing a branched structure and an amide bond structure, has high compatibility with a polyamide molecule, can reduce chain entanglement between molecules, realizes high melt flowability of the nylon 6 resin, and the nylon 6 resin prepared by adding the branched flow agent in a polymerization process can be rapidly formed, thereby reducing production cost.

Description

Technical Field

[0001] This invention relates to a method for preparing nylon materials, specifically to a branched flow agent and its preparation method, rapid prototyping of nylon 6, and its applications. Background Technology

[0002] Nylon (PA) is a general term for polymers whose main chain repeating units contain amide groups. It is the most produced, most diverse, and most widely used of the five major engineering plastics. Nylon 6 (PA6), as a type of nylon material, is widely used in engineering plastics, synthetic fibers, and packaging materials due to its excellent mechanical properties, wear resistance, and processability, in fields such as automotive, electronics, and textiles. However, with the rapid development of electronic and electrical products, power tool housings, and other equipment, the demand for rapid injection molding of complex structural components has surged, such as engine peripherals and electronics. Traditional nylon 6, due to its insufficient flowability, cannot meet the filling requirements of thin-walled, fine-structured products. Therefore, there is an urgent need to develop a nylon 6 material with high flowability that can improve the flowability of nylon 6 while shortening the molding cycle and reducing costs.

[0003] In existing technologies, conventional high-flow nylon 6 is generally produced through blending. This involves adding flow modifiers, nucleating agents, and release agents to the nylon 6 product, followed by extrusion granulation and injection molding. However, blending can significantly impact the fundamental properties of the nylon system.

[0004] To address the aforementioned issues, this invention provides a nylon 6 that, by introducing a relevant flow modifier during the polymerization stage and associating it with the main monomer through a chemical bonding reaction, overcomes the defects of blending in the prior art. Summary of the Invention

[0005] The main objective of this invention is to provide a rapid prototyping method for nylon 6 and its preparation method and applications, so as to overcome the shortcomings of the prior art.

[0006] As a first aspect of the invention, the present invention provides a method for preparing a branched flow agent, comprising the steps of:

[0007] After mixing the triamine monomer with the long-chain monocarboxylic acid monomer, the reaction is carried out by a gradient heating method, and finally dried to obtain the product with a branched structure, which is the branched flow agent.

[0008] Preferably, the molar ratio of the triamine monomer to the long-chain monocarboxylic acid monomer is 1:3.05.

[0009] Preferably, the triamine monomer is one of 4,4′,4″-triaminotriphenylmethane, 2,4,6-tris(4-aminophenoxy)toluene, etc.

[0010] Preferably, the long-chain monocarboxylic acid monomer includes, but is not limited to, one of stearic acid, palmitic acid, oleic acid, etc. Preferably, the gradient temperature method includes a first stage, a second stage, and a third stage.

[0011] In a preferred embodiment, the first stage includes a temperature of 60-80°C, stirring, condensation and reflux, and a reaction time of 15-60 minutes.

[0012] In a preferred embodiment, the second stage includes a reaction temperature of 150–170°C and a reaction time of 5–6 hours.

[0013] In a preferred embodiment, the third stage includes a reaction temperature of 170–190°C and a reaction time of 7–9 hours.

[0014] In a preferred embodiment, the first stage, the second stage, and the third stage are all carried out in an inert gas or nitrogen atmosphere.

[0015] In a preferred embodiment, the drying process includes vacuum drying the resulting product at 25°C for 6 to 12 hours.

[0016] As a second aspect of the invention, the present invention also provides a branched flow agent prepared by the above-described preparation method.

[0017] As a third aspect of the invention, this invention provides a method for preparing rapidly prototyping nylon 6, the specific steps of which include:

[0018] S1. Provides branched flow agent;

[0019] The branched flow agent is a branched flow agent prepared by the preparation method described above;

[0020] S2. Provides reactive nucleating agents;

[0021] The modified silica is reacted with acrylate to obtain acrylate-grafted nano-silica; then it is reacted with ethylenediamine to obtain nano-silica graft containing terminal amine groups, which is the reactive nucleating agent.

[0022] S3. Provides mixed salts of carboxylamino compounds;

[0023] A reactive nucleating agent is reacted with a dicarboxylic acid to form a salt, yielding a mixed carboxylamino salt.

[0024] S4. Polymerization reaction;

[0025] The branched flow agent, the carboxyamino mixed salt and caprolactam are mixed evenly to obtain a reaction system. Under a closed environment and nitrogen protection, the ring-opening polymerization reaction is carried out in sequence through a high pressure stage (190-240℃), an atmospheric pressure stage (250-260℃), and a negative pressure stage (260-270℃) to obtain rapidly molded nylon 6 resin.

[0026] In some specific embodiments, the dicarboxylic acid is adipic acid.

[0027] In some specific embodiments, the reactive nucleating agent is silica-grafted acrylate.

[0028] In some specific embodiments, the modified nano-silica is obtained by modification with an amino-containing silane coupling agent.

[0029] In some specific embodiments, the modified nano-silica is prepared by dispersing nano-silica in an organic solvent, adding a silane coupling agent solution, mixing and heating to 80-120°C, and reacting for 6-12 hours.

[0030] In some specific embodiments, the acrylate is either methyl acrylate or ethyl acrylate.

[0031] In some specific embodiments, the amino and dicarboxylic acids in the reactive nucleating agent described in S3 achieve acid-amine balance by adjusting the pH value, which is 7.5 to 7.9.

[0032] In some specific embodiments, the amount of the carboxyamino mixed salt added is 1 to 4 wt% of the mass of caprolactam.

[0033] In some specific embodiments, the amount of the branching flow agent added is 1 to 4 wt% of the mass of caprolactam.

[0034] In some specific embodiments, the temperature gradually increases during the high-pressure stage, atmospheric pressure stage, and negative pressure stage.

[0035] In some specific embodiments, the high-pressure stage includes raising the temperature of the reaction system to 190–240°C, maintaining the pressure at 1.2–2.0 MPa, and controlling the reaction time to 2–4 hours.

[0036] In some specific embodiments, the atmospheric pressure stage includes depressurizing the reaction system to atmospheric pressure within 1 to 2 hours, during which the material temperature rises to 250 to 260°C.

[0037] In some specific embodiments, the negative pressure stage includes a reaction system pressure of -0.05 to -0.1 MPa, and maintaining the reaction at 260 to 270°C for 1 to 3 hours.

[0038] As a fourth aspect of the invention, the present invention provides a rapidly prototyping nylon 6 prepared using the above-described technical solution.

[0039] As a fifth aspect of the invention, the present invention also provides the application of the rapid prototyping nylon 6 provided by the above-described technical solution in the fields of automotive industry, electronics and electrical engineering, and medical.

[0040] Compared with the prior art, the beneficial effects of the present invention are at least as follows:

[0041] 1) The branched flow agent provided by this invention is a low-viscosity flow regulator containing branched structure and amide bond structure. It has high compatibility with polyamide molecules and can reduce intermolecular chain entanglement, thus achieving high melt flowability of nylon 6 resin. By adding the branched flow agent during the polymerization process, the nylon 6 resin prepared can be rapidly molded, reducing production costs.

[0042] 2) In this invention, a reactive nucleating agent is used as a reactive monomer to participate in the polymerization reaction, which effectively promotes the orderly arrangement of nylon molecular chains and promotes crystallization, so that the obtained PA6 resin has the characteristics of rapid crystallization and easy demolding. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 and Figure 2 The diagrams show the reaction principles of the reactive nucleating agent and the branched flow agent of this invention. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0046] All patent and non-patent literature publications cited in this invention are incorporated herein by reference.

[0047] The terms “comprising,” “including,” “containing,” “covering,” “having,” “with,” or any other variations thereof, as used in this invention, are intended to cover non-exclusive inclusion. For example, a process, method, article of manufacture, or apparatus that includes a list of elements is not necessarily limited to those elements, but may include other elements not expressly listed or inherent to the process, method, article of manufacture, or apparatus. Furthermore, unless expressly stated otherwise, “or” means inclusive “or” rather than exclusive “or.” For example, condition A or B satisfies any of the following: A is real (or exists) and B is false (or does not exist); A is false (or does not exist) and B is real (or exists); and both A and B are real (or exist). The phrase “one or more” is intended to cover non-exclusive inclusion. For example, one or more A, B, and C means any of the following: A alone, B alone, C alone, a combination of A and B, a combination of B and C, a combination of A and C, or a combination of A, B, and C.

[0048] Furthermore, the terms "an" or "a" are used to describe the elements and components described herein. This is done not only for convenience but also to provide a general meaning regarding the scope of the invention. This description should be understood to include one or at least one, one or at least one, and the singular includes the plural unless clearly otherwise indicated.

[0049] This invention provides a branched flow agent, the preparation method of which includes:

[0050] The triamine monomer and the long-chain monocarboxylic acid monomer were weighed out at a molar ratio of 1:3.05 and placed in a four-necked flask. The flask was then transferred to a 70°C oil bath, and a reflux condenser was set up. Nitrogen gas was purged and the mixture was mechanically stirred for half an hour. Under continuous stirring and a nitrogen atmosphere, the temperature was gradually increased to 160°C and reacted for 4 hours, followed by a gradual increase to 180°C and a reaction time of 8 hours. The resulting product was dried in a vacuum oven at 25°C for 12 hours to obtain a branched product, which can be used as a branching flow agent.

[0051] Preferably, the triamine monomer is selected from 4,4′,4″-triaminotriphenylmethane and 2,4,6-tris(4-aminophenoxy)toluene.

[0052] Preferably, the long-chain monocarboxylic acid monomer is selected from stearic acid, palmitic acid, and oleic acid.

[0053] Furthermore, the present invention also provides a reactive nucleating agent, see [link to relevant documentation]. Figure 1 The figure illustrates the reaction principle, which includes: reacting surface-modified nano-silica with methyl acrylate, grafting methyl acrylate onto the surface of nano-silica to obtain nano-silica graft containing terminal amine groups, which is the reactive nucleating agent.

[0054] This invention also provides a branched flow agent, see reference. Figure 2 The figure illustrates the reaction principle, which includes: reacting a triamine monomer with a long-chain monocarboxylic acid monomer, grafting the long-chain monocarboxylic acid onto the triamine monomer to form a branched flow agent with a branched structure.

[0055] Specifically, its preparation steps include:

[0056] By mass, 10 parts of nano-silica were placed in a round-bottom flask containing 130 parts of toluene solvent and ultrasonically dispersed for 40 minutes. 3 parts of silane coupling agent KH550 (aminopropyltriethoxysilane) were weighed into 50 parts of methanol solution. The methanol mixture was slowly added dropwise to the round-bottom flask and reacted at 80°C for 6 hours.

[0057] Using methanol as a solvent, KH550 modified nano-silica was reacted with excess methyl acrylate at room temperature for 24 hours; after purification, it was reacted with excess ethylenediamine for another 24 hours at room temperature to obtain nano-silica grafts containing terminal amine groups, which can be used as reactive nucleating agents.

[0058] As one of the objectives of this invention, it also provides a method for preparing rapidly prototyping nylon 6, the specific steps of which include:

[0059] Step (1): The reactive nucleating agent and the dicarboxylic acid are reacted in water to form a salt. The reaction endpoint is to control the pH of the system to be 7.5 to 7.9. Under this pH condition, the amino group and the dicarboxylic acid in the reactive nucleating agent achieve acid-amine balance by adjusting the pH value. The reactive nucleating agent and the dicarboxylic acid undergo a salt formation reaction.

[0060] Step (2): After thoroughly mixing the above mixed salt solution with caprolactam monomer and branched flow agent, the mixture is placed into a high-pressure reactor. The reactor is then closed, and the air inside is replaced with nitrogen at least three times. The temperature and pressure are increased under a sealed environment and nitrogen protection, and the reaction is carried out for a certain period of time under pressure. Then, the pressure inside the reactor is gradually reduced to atmospheric pressure, and a vacuum reaction is performed. The reaction is completed under negative pressure to obtain rapid molding nylon 6 resin.

[0061] Preferably, in step (1) of the above preparation method, the dicarboxylic acid is adipic acid.

[0062] Preferably, the mass ratio of the reactive nucleating agent to the dicarboxylic acid is 3:2.

[0063] Preferably, in step (2) of the above preparation method, the ring-opening polymerization reaction is carried out under conditions of high pressure stage (190~240℃)-normal pressure stage (250~260℃)-negative pressure stage (260~270℃).

[0064] Preferably, the heating and pressurization refers to raising the temperature inside the reactor to 190–240°C, maintaining the pressure inside the reactor at 1.2–2.0 MPa, and controlling the reaction time to 2–4 hours.

[0065] Preferably, the gradual reduction of the pressure inside the vessel to atmospheric pressure means reducing the pressure inside the vessel to atmospheric pressure within 1 to 2 hours, during which the material temperature rises to 250 to 260°C.

[0066] Preferably, the negative pressure conditions specifically include a reaction system pressure of -0.05 to -0.1 MPa, and maintaining the reaction at 260 to 270°C for 1 to 3 hours.

[0067] The invention will be more fully understood by referring to the following detailed description and accompanying drawings; however, it should be understood that the embodiments disclosed herein are merely exemplary and may be embodied in various forms. Therefore, the specific functional details disclosed herein should not be construed as limiting, but rather as the basis for the claims and as intended to teach those skilled in the art to employ the representative basis of the invention in different ways in any suitable detailed embodiment.

[0068] Example 1

[0069] The rapid prototyping method for nylon 6 provided in this embodiment includes the following specific steps:

[0070] 1. Provide reactive nucleating agents

[0071] Ten parts by mass of nano-silica were placed in a round-bottom flask containing 130 parts by mass of toluene solvent and ultrasonically dispersed for 40 minutes. Three parts by mass of silane coupling agent KH550 (aminopropyltriethoxysilane) were added to 50 parts by mass of methanol solution. The methanol mixture was slowly added dropwise to the round-bottom flask and reacted at 80°C for 6 hours. Using methanol as solvent, KH550-modified nano-silica was reacted with excess methyl acrylate at room temperature for 24 hours. After purification, it was reacted with excess ethylenediamine at room temperature for another 24 hours to obtain nano-silica grafts containing terminal amine groups, which is the reactive nucleating agent.

[0072] 2. Salt formation reaction

[0073] The total mass fraction of the reactive nucleating agent and adipic acid provided in step 1 is 10 parts. Four parts of adipic acid are dissolved in 10 parts of deionized water to form a mixture under continuous stirring. Six parts of the reactive nucleating agent are slowly added dropwise to the mixture, and the reaction proceeds to obtain a reaction system. During the reaction, the pH value at the reaction endpoint needs to be controlled to be 7.5–7.9. Finally, a carboxylamine mixed salt solution is obtained; the mixed solution contains 50 wt% carboxylamine mixed salt.

[0074] 3. Provide branched flow agent

[0075] A triamine monomer (4,4',4”-triaminotriphenylmethane) and a long-chain monocarboxylic acid monomer (stearic acid) were weighed out at a molar ratio of 1:3.05 and placed in a four-necked flask. The flask was then transferred to a 70°C oil bath, and a reflux condenser was set up. Nitrogen gas was introduced and the mixture was mechanically stirred for half an hour. Under continuous stirring and a nitrogen atmosphere, the temperature was gradually increased to 160°C and reacted for 4 hours, followed by a gradual increase to 180°C and a reaction time of 8 hours. The resulting product was dried in a vacuum drying oven at 25°C for 12 hours to obtain the branched product, which is the branched flow agent.

[0076] 4. Synthesis of rapid prototyping nylon 6

[0077] The 10 parts of carboxyamine mixed salt solution obtained in step 2 were mixed evenly with 1000 parts of caprolactam monomer and 20 parts of branched flow agent, and then put into a high-pressure polymerization reactor. High-purity nitrogen was introduced and a vacuum was drawn, which was repeated more than three times to fully replace the air in the reactor. Stirring was turned on, the temperature in the reactor was raised to 230°C, the pressure in the reactor was maintained at 1.3 MPa, and the reaction time was controlled at 2.5 hours.

[0078] The pressure inside the reactor was then reduced to atmospheric pressure within 1.5 hours, while the material temperature was raised to 255°C.

[0079] Then, the vacuum was evacuated to -0.08 MPa, the material temperature was raised to 270℃, and the reaction was carried out for 3 hours.

[0080] Finally, nitrogen gas is introduced to raise the pressure inside the reactor to atmospheric pressure. The discharge valve at the bottom of the reactor is opened to allow the material to pass through the cooling water tank. After drawing, pelletizing, and drying, rapid molding nylon 6 resin can be obtained.

[0081] Example 2

[0082] The only difference between this embodiment and Embodiment 1 is the amount of branching flow agent added in step 4; specifically, in step 4, the amount of branching flow agent added is 30 parts, and all other steps are the same.

[0083] Example 3

[0084] The only difference between this embodiment and Embodiment 1 is the amount of carboxylamine mixed salt added in step 2. In step 2, the amount of carboxylamine mixed salt added is 40 parts, and all other steps are the same.

[0085] Example 4

[0086] The only difference between this embodiment and Example 1 is the triamine monomer in step 3. In this embodiment, the triamine monomer is 2,4,6-tris(4-aminophenoxy)toluene, and all other aspects are the same.

[0087] Example 5

[0088] The only difference between this embodiment and Example 1 is that the long-chain monocarboxylic acid monomer in step 3 is different. In this embodiment, the long-chain monocarboxylic acid monomer is palmitic acid. All other steps are the same.

[0089] Comparative Example 1

[0090] The only difference between this comparative example and Example 1 is the amount of branching flow agent added in step 4; specifically, in step 4, the amount of branching flow agent added is 60 parts, and all other steps are the same.

[0091] Comparative Example 2

[0092] The only difference between this comparative example and Example 1 is the amount of carboxylamine mixed salt added in step 2. In step 2, the amount of carboxylamine mixed salt added is 80 parts, and all other steps are the same.

[0093] Comparative Example 3

[0094] The only difference between this comparative example and Example 1 is that the mixed salt of carboxylamine is not added in step 2; all other steps are the same.

[0095] Comparative Example 4

[0096] The only difference between this comparative example and Example 1 is that no branching flow agent is added in step 4; all other aspects are the same.

[0097] Comparative Example 5

[0098] The only difference between this comparative example and Example 1 is that the carboxylamine mixed salt is not added in step 2 and the branching flow agent is not added in step 4; all other steps are the same.

[0099] The composition and amount of each raw material in Examples 1-5 and Comparative Examples 1-5 are shown in Table 1.

[0100] The test methods and standards for the performance parameters of the above embodiments and comparative examples are as follows:

[0101] (1) Relative viscosity: The relative viscosity of the product with a concentration of 0.5 g / dL was measured using an Ubbelohde viscometer in a 98% concentrated sulfuric acid solution at (25±0.01)℃.

[0102] (2) Melt flow index: Referring to GB / T 3682-2000 standard, the mass of the sample flowing out of the die of the special equipment within ten minutes was determined using a melt flow rate tester. The test conditions were as follows: temperature 235℃, weight of weight 2.16kg (235℃*2.16kg). Each sample was tested five times and the average value was taken.

[0103] (3) Melting point, crystallization temperature and time: DSC test instrument, nitrogen atmosphere, heating and cooling rate of 10℃ / min.

[0104] (4) Mechanical properties: Tensile strength is tested according to standard ISO 527-1 / -2, flexural strength and flexural modulus are tested according to standard ISO 178, and notched impact strength of simply supported beam is tested according to standard ISO 179 / 1eA.

[0105] (5) Processing performance: Nylon 6 resin was injection molded into 60mm*60mm*3mm samples at an injection temperature of 240-260℃. The injection molding cycle and demolding difficulty were compared. Based on the demolding effect, the samples were divided into two levels: easy demolding and sticking to the mold. Easy demolding means that the sample can be easily removed from the mold, while sticking to the mold means that the sample sticks to the mold.

[0106] Refer to Table 1 for the raw material composition of each embodiment and comparative example; Table 2 for the performance test results of each embodiment and comparative example.

[0107] Table 1. Composition of raw materials in each embodiment and comparative example.

[0108]

[0109] Table 2 shows the test results of various properties of nylon 6 resin in each example and comparative example.

[0110]

[0111] As shown in Table 2, the addition of reactive nucleating agents and branched flow agents can significantly improve the crystallization performance (shortening crystallization time and increasing crystallization temperature) and melt flowability of the PA6 system, thereby improving the efficiency of injection molding. This is attributed to the fact that both reactive nucleating agents and branched flow agents contain polar amide bonds, which can form stable hydrogen bonds with the PA6 system, improving their compatibility and dispersibility. Examples 1, 3, and Comparative Example 2 show that the addition of reactive nucleating agents within a certain range helps improve the crystallization performance of the system; excessive addition leads to a decrease in both the toughness and strength of the system, and a deterioration in melt flowability. Examples 1, 2, and Comparative Example 1 show that excessive addition of branched flow agents easily leads to a significant decrease in the viscosity of the system, sacrificing mechanical properties.

[0112] The above are merely preferred embodiments of the present invention and do not limit the scope of protection of the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any changes, modifications, substitutions, integrations, and parameter alterations to these embodiments within the spirit and principles of the present invention, achieved through conventional substitutions or by achieving the same function without departing from the principles and spirit of the present invention, fall within the scope of protection of the present invention.

Claims

1. A method for preparing a branched flow agent, characterized by, The application relates to a branched flow agent and a preparation method thereof. The branched flow agent is prepared by mixing a triamine monomer and a long carbon chain monocarboxylic acid monomer, and then performing a gradient temperature rising reaction, and finally drying to obtain the branched flow agent. The triamine monomer is selected from any one or a combination of 4,4',4''-triaminotriphenylmethane and 2,4,6-tris (4-aminophenoxy) toluene. The long carbon chain monocarboxylic acid monomer is selected from any one or a combination of stearic acid, palmitic acid and oleic acid.

2. The method for preparing the branched flow agent according to claim 1, characterized in that, The molar ratio of the triamine monomer to the long carbon chain monocarboxylic acid monomer is 1:3.

05.

3. The method of claim 1, wherein the branched fluid is prepared by, The gradient temperature rising method comprises a first stage, a second stage and a third stage. The first stage comprises stirring and condensation reflux at a temperature of 60-80 DEG C for 15-60 minutes. The second stage comprises a reaction temperature of 150-170 DEG C for 5-6 hours. The third stage comprises a reaction temperature of 170-190 DEG C for 7-9 hours. The temperature of the first stage, the second stage and the third stage gradually increases.

4. The method of claim 1, wherein the branched fluid is prepared by, The first stage, the second stage and the third stage are all performed under an inert gas or nitrogen atmosphere.

5. The method of claim 1, wherein the branched fluid is prepared by, The drying comprises vacuum drying the obtained product at 25 DEG C for 6-12 hours.

6. A branched flow agent prepared by the preparation method in any one of claims 1-5.

7. A preparation method of a rapid forming nylon 6, and the specific steps comprise: S1. providing a branched flow agent; The branched flow agent is prepared by the preparation method in any one of claims 1-5. Or, the branched flow agent in claim 6; S2. providing a reaction type nucleating agent; The reaction type nucleating agent is an amine end group-containing nano silicon dioxide grafting product; S3. providing a carboxyl-amino mixed salt; The reaction type nucleating agent and a dibasic acid are subjected to a salt formation reaction to obtain the carboxyl-amino mixed salt; S4. polymerization reaction; The branched flow agent, the carboxyl-amino mixed salt and caprolactam are uniformly mixed to obtain a reaction system, and the ring-opening polymerization reaction is performed under the conditions of a high-pressure stage, a normal-pressure stage and a negative-pressure stage in a closed environment and under nitrogen protection to obtain the rapid forming nylon 6 resin.

8. The method of claim 7, wherein the 3D printing of nylon 6 is performed at a temperature of 180-220°C. In S2, the modified nano silicon dioxide is reacted with an acrylate to obtain nano silicon dioxide grafted with the acrylate, and then reacted with ethylenediamine to obtain the amine end group-containing nano silicon dioxide grafting product, namely the reaction type nucleating agent.

9. The method of claim 7, wherein the nylon 6 is prepared by a rapid molding process. The modified nano silicon dioxide is obtained by modifying an amino-containing silane coupling agent.

10. The method of claim 7, wherein the nylon 6 is prepared by a rapid prototyping process. The modified nano silicon dioxide is obtained by dispersing nano silicon dioxide in an organic solvent, adding a silane coupling agent solution, mixing and heating to 80-120 DEG C for 6-12 hours.

11. The method of claim 7, wherein the nylon 6 is prepared by rapid prototyping. In S3, the amino group in the reaction type nucleating agent and the dibasic acid realize acid-amine balance by adjusting the pH value, and the pH value is 7.5-7.

9.

12. The method of claim 7, wherein the nylon 6 is prepared by rapid prototyping. The addition amount of the carboxyl-amino mixed salt is 1-4 wt% of the mass of caprolactam.

13. The method of claim 7, wherein the nylon 6 is prepared by a rapid molding process. The addition amount of the branched flow agent is 1-4 wt% of the mass of caprolactam.

14. The method of claim 7, wherein the nylon 6 is prepared by rapid prototyping. The dibasic acid is adipic acid.

15. The method of claim 7, wherein the method is a rapid prototyping method for nylon 6. The temperature of the high-pressure stage, the normal-pressure stage and the negative-pressure stage gradually increases.

16. The method of claim 7, wherein the nylon 6 is prepared by rapid prototyping. The high-pressure stage includes raising the temperature of the reaction system to 190-240 DEG C, keeping the pressure at 1.2-2.0 MPa, and controlling the reaction time at 2-4 hours.

17. The method of claim 7, wherein the nylon 6 is prepared by rapid prototyping. The normal-pressure stage includes reducing the pressure of the reaction system to normal pressure in 1-2 hours, during which the material temperature rises to 250-260 DEG C.

18. The method of claim 7, wherein the nylon 6 is prepared by rapid prototyping. The negative-pressure stage includes keeping the pressure of the reaction system at -0.05 to -0.1 MPa, and maintaining the reaction at 260-270 DEG C for 1-3 hours.

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