CN111138601A

CN111138601A - Preparation method of micro-nano wax powder-containing photosensitive resin for 3D printing

Info

Publication number: CN111138601A
Application number: CN201911327730.1A
Authority: CN
Inventors: 田雷; 张天举; 王伟侠
Original assignee: Beijing Dijia Medical Equipment Co ltd
Current assignee: Beijing Dijia Medical Equipment Co ltd
Priority date: 2019-12-20
Filing date: 2019-12-20
Publication date: 2020-05-12

Abstract

The embodiment of the invention discloses a preparation method of a photosensitive resin containing micro-nano wax powder for 3D printing, which comprises the following steps: preparing a low-viscosity primary mixed solution, preparing a low-viscosity micro-nano wax powder dispersion solution, weighing high-viscosity components, diluting the high-viscosity components, carrying out first vacuum defoaming, carrying out second high-speed dispersion and carrying out second vacuum defoaming. The method eliminates the micro air components carried and wrapped on the surface or inside of the micro-nano wax powder in the resin, and simultaneously breaks up the micro aggregates of the micro-nano particles in the system, so that the micro-nano wax powder can exist in the resin in a single particle shape for a long time and stably, the stable and uniform suspension time of the micro-nano particles in the system is greatly prolonged, the density uniformity of a printing model and the surface smoothness and surface precision of the model are ensured, and the storage quality guarantee time, the printing performance and the mechanical strength of the printing model are integrally improved.

Description

Preparation method of micro-nano wax powder-containing photosensitive resin for 3D printing

Technical Field

The invention relates to the technical field of photosensitive resin, in particular to a preparation method of micro-nano wax powder-containing photosensitive resin for 3D printing.

Background

The 3D Printing is to stack and bond special materials such as metal powder, ceramic powder, plastic, cell tissue and the like layer by using methods such as laser beams, electron beams and the like by means of a three-dimensional digital model design and a software layering dispersion and numerical control molding system, and finally to stack and mold to manufacture a solid product. Conceptually, it is synonymous with "Additive Manufacturing" in industrial terminology. It is called "additive manufacturing" because it is distinguished from traditional machining methods: the desired molded part is obtained by removing the excess material by various machining means (cutting, drilling, etching, etc.) such as a mathematical "subtraction" operation. And "" additive manufacturing "" is reversed; the product is manufactured by a specific way of material addition, much like doing an "add".

3D printing is typically achieved using digital technology material printers. The method is often used for manufacturing models in the fields of mold manufacturing, industrial design and the like, and is gradually used for directly manufacturing some products, and parts printed by the technology are already available. The technology has applications in jewelry, footwear, industrial design, construction, engineering and construction (AEC), automotive, aerospace, dental and medical industries, education, geographic information systems, civil engineering, firearms, and other fields as well.

The 3D printing job flow can be generally divided into three stages, namely pre-processing (pre-processing), forming (processing), and post-processing (post-processing). In the pre-processing stage, a computer is used for designing a three-dimensional model (CAD modeling), and the 3D model is converted into a file format which can be recognized by a printing device, such as STL, OBJ, VRML, DXF and PLY. The computer software system used by the common 3D printing equipment has a reverse engineering operation function, and the software automatically generates a manufacturing program according to corresponding parameters of product design. In the molding processing stage, the printing equipment performs hierarchical manufacturing according to a preset program to obtain a blank. In the post-treatment stage, the final product is obtained after the processes of polishing, infiltration and the like are carried out according to the needs of the product.

The 3D printing technique is actually a general term for a series of rapid prototyping techniques, and the basic principle thereof is laminate manufacturing, in which a rapid prototyping machine forms the cross-sectional shape of a workpiece by scanning in an X-Y plane, and performs displacement of the slice thickness intermittently in a Z coordinate, to finally form a three-dimensional part. The rapid prototyping technologies in the market at present are classified into fused deposition rapid prototyping (FDM), light curing prototyping (SLA, DLP), Selective Laser Sintering (SLS), three-dimensional powder bonding prototyping (3DP), layered entity fabrication (LOM), and the like according to the characteristics of a prototyping principle.

The photocuring molding technology is the earliest developed rapid molding technology and is one of the most deeply researched, mature and widely applied rapid molding technologies at present. The photocuring technology mainly uses photosensitive resin as a material, and the liquid photosensitive resin to be molded is selectively subjected to polymerization reaction hardening through irradiation of ultraviolet light or other light sources, and is cured layer by layer to finally obtain a complete product. The process comprises the following steps:

① designing a three-dimensional solid model by CAD, slicing the model by discrete program, designing scanning path, and accurately controlling the movement of laser scanner and lifting platform by the generated data;

② SLA laser beam irradiates the liquid photosensitive resin surface according to the designed scanning path through the scanner controlled by the numerical control device, or DLP surface light source single-layer exposure, after a layer of resin in the specific area of the surface is solidified, when a layer is processed, a section of the part is generated;

③ the lifting platform descends for a certain distance, the solidified layer is covered with another layer of liquid resin, then the second layer of scanning is carried out, the second solidified layer is firmly bonded on the former solidified layer, thus the three-dimensional workpiece prototype is formed by stacking layer by layer,

④ taking out the prototype from the resin, curing, polishing, electroplating, painting or coloring to obtain the desired product.

SLA and DLP technologies have the following advantages:

① solidification was the earliest rapid prototyping process with high maturity, which was time tested.

② the prototype is made directly from CAD digital model, the processing speed is fast, the production cycle is short, and no cutting tool or mould is needed.

③ allow for the fabrication of prototypes and molds having complex structural shapes or which are difficult to form using conventional means.

④ visualize the CAD digital model and reduce the cost of error recovery.

⑤ provides samples for the experiment, and can verify and check the results of computer simulation calculation.

⑥ can be operated on-line and controlled remotely, which is beneficial to automation of production.

SLA and DLP photocuring molding technology is mainly used for manufacturing various molds, models and the like; SLA or DLP master molds can also be used to replace wax molds in investment casting by adding other ingredients to the raw materials. The light curing technology has the advantages of high forming speed and high precision. With the continuous development and maturity of 3D printing equipment and process, the limitation of the raw materials for 3D printing has become an important factor restricting the development of 3D printing technology. Therefore, research and development of novel 3D printing raw materials gradually become the key of 3D printing innovation breakthrough and is a necessary way for expanding the application field of 3D printing technology.

At present, the 3D printing photosensitive resin in the dental and jewelry casting field is required to be fully combusted, no residue and ash are generated after combustion, otherwise, a plurality of defects such as holes, sand holes, rough surfaces and the like of a cast sample piece are generated in the following casting step due to the residue and the ash; meanwhile, in the sintering and temperature rising process, the expansion rate of the printing model material cannot be larger than that of the gypsum wrapped at the periphery, otherwise, the cracking of the gypsum mould shell can be caused due to the overlarge expansion rate, so that the casting failure is caused.

In the wax-containing photosensitive resin developed by the existing material manufacturers, the stability of wax powder in the resin is poor, and the wax powder can be settled after being stored for two months, so that the uniformity of the material is unbalanced. The material manufacturer is also aware of this problem and therefore advises the user to do a vigorous shaking process before use. However, the liquid resin is brought into a large amount of tiny bubbles by a manual violent shaking treatment mode, the bubbles continuously rise in the printing process, and meanwhile, part of the bubbles remain at the edge of the model in the printing process, so that the surface precision of the printing model is greatly reduced; meanwhile, the wax powder in the resin cannot be fully and uniformly suspended in the system by manual hand shaking, but the wax powder is suspended in the system in a small agglomerated particle shape in a short time. After the tiny wax powder agglomerated particles are printed in a model, a weak stress point is formed at the position due to the existence of local excessive wax powder, the weak point can cause the damage and the fracture of the model under the compression of weak external force, in the casting process, the vacuumizing and drying processes can not be separated, and the vacuumizing and drying processes can cause a large degree of compression force on the printed wax model, so the wax powder agglomerated particles can more easily cause the fracture of the model, and meanwhile, dental or jewelry models contain precise and tiny fine structures, so that the existing wax-containing 3D printing photosensitive resin printed model for casting has the defects of poor mechanical strength and easy fracture.

Disclosure of Invention

The embodiment of the invention aims to provide a preparation method of a photosensitive resin containing micro-nano wax powder for 3D printing. The method eliminates the micro air components carried and wrapped on the surface or inside of the micro-nano wax powder in the resin, and simultaneously breaks up the micro aggregates of the micro-nano particles in the system, so that the micro-nano wax powder can exist in the resin in a single particle shape for a long time and stably, the stable and uniform suspension time of the micro-nano particles in the system is greatly prolonged, the density uniformity of a printing model and the surface smoothness and surface precision of the model are ensured, and the storage quality guarantee time, the printing performance and the mechanical strength of the printing model are integrally improved.

In order to achieve the above object, an embodiment of the present invention provides a method for preparing a photosensitive resin for 3D printing, the photosensitive resin including a photoinitiator, an ultraviolet absorber, an active monomer, a dispersant, a color additive, a coupling agent, a defoaming agent, micro-nano wax powder, and an active oligomer, the method including the steps of:

(1) preparing a low-viscosity primary mixed solution: weighing the photoinitiator, the ultraviolet absorbent, the active monomer, the dispersant, the color auxiliary agent, the coupling agent and the defoaming agent in proportion, adding the weighed materials into a closed light-proof container, fully stirring and dissolving the materials, and stopping stirring after obtaining a uniform and stable mixed solution to prepare a low-viscosity primary mixed solution;

(2) preparing a low-viscosity micro-nano wax powder dispersion liquid: the low-viscosity primary mixed liquid is placed into high-speed dispersion equipment for dispersion, the micro-nano wax powder weighed according to the proportion is gradually and slowly added into the low-viscosity primary mixed liquid in the dispersion process, and when all the micro-nano wax powder is added, the dispersion rotating speed is continuously increased and the micro-nano wax powder is continuously dispersed for a certain time until the micro-nano wax powder is dispersed in the low-viscosity primary mixed liquid in a single particle state, the dispersion is stopped, and the micro-nano wax powder is taken out for later use;

(3) weighing high-viscosity components: weighing the high-viscosity active oligomer, and putting the active oligomer into another closed lightproof container for later use;

(4) high viscosity component is dilute: slowly adding the low-viscosity micro-nano wax powder dispersion liquid obtained in the step (2) into the high-viscosity component in batches at a low dispersion speed, continuing low-speed dispersion for a period of time after the addition is finished, increasing the high dispersion speed to perform first high-speed dispersion after the viscosity of the liquid in the container is uniform, continuously dispersing for a certain period of time until the appearance of the mixture is an opaque liquid containing a large number of bubbles, and stopping dispersion;

(5) first vacuum defoaming: placing the mixture obtained in the step (4) into vacuum equipment for defoaming, slowly increasing the vacuum degree to-0.1 MPa step by step from normal pressure, stably placing for a certain time under the constant vacuum degree of each step, and continuously increasing the vacuum degree after most of bubbles quickly rise to the liquid level and burst until the bubbles in the opaque liquid containing a large amount of bubbles obtained in the step (4) are completely removed;

(6) and (3) second high-speed dispersion: slowly putting the material obtained in the step (5) after the first vacuum defoamation into a high-speed disperser, starting the disperser, gradually increasing the speed from low to high until the dispersion speed is more than or equal to 300rpm, ensuring that the top end of a stirring paddle is kept below a liquid vortex while dispersing, continuously dispersing for 30min-12h, controlling the temperature of the system to be less than or equal to 95 ℃ during continuous dispersion, stopping dispersing until micro-nano particles are dispersed in a resin system in a single particle state, and taking out for later use;

(7) and (3) second vacuum defoaming: and (4) putting the material subjected to the secondary high-speed dispersion obtained in the step (6) into vacuum equipment, directly increasing the vacuum degree to a high vacuum degree and stabilizing for a certain time until all bubbles in the material float upwards to break the surface, thereby obtaining the photosensitive resin for 3D printing containing the micro-nano wax powder.

The method comprises the following steps of (5) and (3) wherein a great amount of bubbles exist in a system, in the first vacuum defoaming process, a large amount of bubbles in the system can be completely removed, in the vacuum defoaming process, the bubbles in resin can rapidly rise in vacuum, and meanwhile, the bubbles in micro-nano wax powder particle aggregates or on the surfaces of the aggregates can also float upwards due to the increase of the vacuum degree, so that the micro-nano wax powder in the system is artificially forced to be unevenly distributed vertically, and secondary high-speed dispersion is needed. In order to avoid secondary pollution of bubbles, the equipment and related accessories are wiped and cleaned before being put into the disperser, in order to avoid bubbles from being brought into materials in the putting process, the materials need to be put into the disperser as slowly as possible, and stirring slurry is put into the bottom end of the container as much as possible; to prevent entrainment of gas into the liquid resin during high speed dispersion, the tip of the paddle is ensured to remain below the liquid vortex while dispersing at high speed.

Wherein, in the second high-speed dispersing process, it is difficult to ensure that no bubble exists in the system, and in order to eliminate a very small amount of bubbles brought by carelessness in the second high-speed dispersing in the step (6) or bubbles which cannot be completely removed in the first vacuum defoaming process, the material in the step (6) is subjected to vacuum defoaming again. After all the bubbles in the resin float to the liquid surface and break, the material can not be continuously vacuumized for a long time.

In one non-limiting embodiment, the micro-nano wax powder-containing photosensitive resin for 3D printing comprises the following components in percentage by mass: 0.1 to 5 percent of photoinitiator; 0.05 to 2 percent of ultraviolet absorbent; 0.1 to 3 percent of dispersant; 0.001% -0.5% of color additive; 0.1 to 2 percent of coupling agent; 0.01 to 0.05 percent of defoaming agent; 5% -85% of active monomer; 5% -90% of micro-nano wax powder; and 10% -80% of reactive oligomer.

Further, the stirring temperature in the step (1) is 30-95 ℃, preferably 45-75 ℃; stirring for 20min-3h, preferably 30min-1 h; the stirring device used is a magnetic stirrer or a stirring paddle stirrer, and can also be other stirring devices commonly used in the field; the viscosity of the low-viscosity primary mixed liquid prepared in the step (1) is less than or equal to 1500cp, preferably less than or equal to 300 cp.

Further, the high-speed dispersing equipment in the step (2) is a high-speed disperser, a ball mill, a sand mill or a three-roll mixer, and can also be other high-speed high-efficiency mixing equipment commonly used in the field; in the step (2), after the wax powder is completely added, the dispersion rotating speed is increased to be more than or equal to 300rpm, preferably more than or equal to 750 rpm; the dispersion time is 1h-12h, preferably 2h-8 h; the integral temperature of the system is controlled to be less than or equal to 95 ℃ during the dispersion period, and preferably less than or equal to 75 ℃.

Further, the low dispersion speed in the step (4) is less than or equal to 500rpm, preferably less than or equal to 100 rpm; after the wax powder is added, continuously dispersing at a low rotating speed for a period of time less than or equal to 1h, preferably less than or equal to 30 min; the lifting to high dispersion speed is more than or equal to 200rpm, preferably more than or equal to 500 rpm; the continuous dispersion time of the first high-speed dispersion is 1h-12h, preferably 2h-8 h; the integral temperature of the system is controlled to be less than or equal to 95 ℃ during the dispersion period, and preferably less than or equal to 75 ℃.

Further, the vacuum deaeration in the step (5) is carried out in steps, and the stable standing time of each step is 1-40min, preferably 5-15 min.

Further, the dispersing speed in the step (6) is more than or equal to 500 rpm; the continuous dispersion time is 2-8 h; the integral temperature of the system is controlled to be less than or equal to 75 ℃ during the dispersion period.

Further, the second vacuum defoaming in the step (7) is to directly and rapidly increase the vacuum degree to-0.1 MPa; the stabilization time is 3-30min, preferably 5-15 min.

In one embodiment, the ingredients used in step (1) comprise a high viscosity material, and/or the ingredients used in step (3) comprise a low viscosity material; the viscosity of the low-viscosity initial mixed liquid in the step (1) after mixing is less than or equal to 300 cp.

Further, in the steps (1) to (7), when mixing and dispersing, a low-viscosity component or mixture is added to a high-viscosity component or mixture. This facilitates obtaining the photosensitive resin for 3D printing of the present invention containing stable and uniform components, and thus it is impossible to add a high-viscosity component or mixture to a low-viscosity component or mixture for dispersion.

The important reason that the micro-nano wax powder cannot exist stably in the resin system is that after the material is prepared, the micro-nano wax powder does not exist in the system in a single particle shape really, micro-nano wax powder particles exist in the liquid resin system in particle aggregates with different sizes, a large number of gas pores exist among particles in the particle aggregates, and meanwhile, bubbles are adhered to the surfaces of the particle aggregates. The bubbles are irregular and vary with the morphology of the particle aggregates; meanwhile, the size of the bubbles is far larger than the nanometer level, so the bubbles cannot exist stably in the system, and the bubbles cannot be removed by simple mechanical stirring. Therefore, the existence of the combined particle aggregate and the air bubbles in the material leads to the instability of the whole material, so that the prepared material cannot bear large temperature difference impact and mechanical vibration impact caused by bumping in long-distance transportation, and the storage stability of the prepared material is poor due to the existence of the two defects. The model printed by the inhomogeneous material has fatal defect of mechanical property, which causes the cast model with a precise structure to be damaged in the casting process, reduces the production efficiency and increases the reworking times and the production cost.

In order to solve the problems of micro-aggregates caused by poor dispersibility of micro-nano wax powder in a liquid resin body and bubbles existing among particles in the micro-aggregates and on the surfaces of the micro-aggregates, the invention discloses a preparation process of a 3D printing photosensitive resin containing the micro-nano wax powder for precision casting, which comprises the steps of slowly adding a low-viscosity substance into a high-viscosity substance dispersed at a low rotating speed according to different viscosities of materials through secondary high-speed dispersion and secondary vacuum defoaming, so as to increase the integral dispersion degree of the micro-nano particles in the materials, eliminate micro air components carried and wrapped on the surfaces or the inner parts of the micro-nano wax powder in the resin, and simultaneously scatter the micro-aggregates of the micro-nano particles in a system, so that the micro-nano wax powder can exist in a single particle shape stably for a long time in the resin, and greatly prolong the stable and uniform suspension time of the micro-nano particles in the system, the density uniformity of the printing model, the surface smoothness and the surface precision of the printing model are guaranteed, and the storage quality guarantee time, the printing performance and the mechanical strength of the printing model of the material are integrally improved.

For the existing formula of the micro-nano wax powder-containing photosensitive resin for 3D printing for precision casting, the photosensitive resin for 3D printing for dental and jewelry casting can be prepared uniformly and stably for a long time by reasonably optimizing the preparation process conditions, the micro-nano wax powder in the resin has good dispersion compatibility, can be stably dispersed in a liquid resin in a single particle state for a long time, ensures the integral stability of the material, and can be stored for a long time; meanwhile, the system cannot be unstable due to large temperature change and mechanical vibration in the long-distance transportation process. The surface precision of the printing model is ensured by the dispersion of the single particles, and meanwhile, no micro-nano particles or large or small micro-aggregates exist in the system, so that the mechanical strength of the printing model is ensured, the damage rate of the model is greatly reduced in the precision casting field of dentistry or jewelry and the like, and the casting quality and the yield are improved.

The embodiment of the invention has the following advantages:

1. compared with the traditional manual preparation process, the 3D printing technology adopted by the invention improves the production efficiency of a factory, avoids the defects caused by human factors such as uneven casting quality and the like, and reduces the labor cost;

2. compared with a 3D printing material prepared by pure resin, the technical scheme of the invention solves the defects that the existing 3D printing casting material used in the dental and jewelry fields is insufficient in combustion, high in sintered ash and residue content, large in porosity, incomplete in surface, rough, low in density and the like in a casting sample caused by the combusted ash or residue;

3. meanwhile, the defects that the existing 3D printing resin for dental and jewelry casting is high in model expansion rate in the heating and sintering process, and a casting shell is easy to crack and the like are overcome.

Detailed Description

The present invention is described in terms of particular embodiments, other advantages and features of the invention will become apparent to those skilled in the art from the following disclosure, and it is to be understood that the described embodiments are merely exemplary of the invention and that it is not intended to limit the invention to the particular embodiments disclosed. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

A preparation method of a micro-nano wax powder-containing 3D printing photosensitive resin for precision casting comprises the following raw materials:

0.1g of 1-hydroxy-cyclohexyl-phenyl-methanone (common trademark: 184; CAS No. 947-19-3),

0.1g of 2,4, 6-trimethylbenzoyl-diphenylphosphine oxide (general trade name: TPO; CAS number: 75980-60-8)

0.2g of cyclopropyldiphenylsulfonium tetrafluoroborate (CAS number: 33462-81-6),

0.05g of 1-methyl-8- (1,2,2,6, 6-pentamethyl-4-piperidine) sebacate mixture (CAS number: 41556-26-7),

2- (2' -hydroxy-3 ' -tert-butyl-5 ' -methylphenyl) -5-chlorobenzotriazole (CAS number: 3896-11-5)0.05g

Dispers6520.15g Digao,

texaphor P610.05g,

solvent Orange 62 (Milwaukee chemical Co., Ltd., index: Solvent Orange 62)0.02g,

0.1g of gamma- (2, 3-epoxypropoxy) propyltrimethylsilane,

ByK067A 0.03.03 g,

dipropylene glycol diacrylate (DPGDA, CAS number: 57472-68-1)4.15g

Tripropylene glycol diacrylate (TPGDA, CAS number: 42978-66-5)2.5g

2.5g of ethoxyethoxyethyl acrylate (EOEOEA, CAS number: 7328-17-8)

Trimethylolpropane triacrylate (TMPTA, CAS number: 15625-89-5)5g

(ethoxy) phenol acrylate (PHEA, CAS number: 48145-04-6)5g,

60g of basf AF29 spherical high-density polyethylene micro powder wax,

5g of polyaminoacrylate (sartomer; CN968),

6g of polyaminoacrylate (sartomer; CN981),

7g of aliphatic polyaminoacrylate (Sadoma; CN9006),

2g of hexafunctional urethane acrylate (Saedoma; CN975)

The preparation method comprises the following steps:

① preparation of a low-viscosity initially-mixed liquid by dissolving 0.1g of 1-hydroxy-cyclohexyl-phenyl ketone (general reference No. 184; CAS No. 947-19-3) and 0.1g of 2,4, 6-trimethylbenzoyl-diphenylphosphine oxide (general reference No. TPO; CAS No. 75980-60-8) as required in the formulation, 0.05g of cyclopropyldiphenylsulfonium tetrafluoroborate (CAS No. 33462-81-6), 0.05g of 1-methyl-8- (1,2,2,6, 6-pentamethyl-4-piperidine) sebacate mixture (CAS No. 41556-7), 0.05g of 2- (2' -hydroxy-3 ' -tert-butyl-5 ' -methylphenyl) -5-chlorobenzotriazole (CAS No. 3896-11-5) and 0.05g of high Dispers6520.5g of 1-1 g of cozino Texhor, 610.0562 g of Solvent initially-butyl-5-tolyltriazole (CAS No. 066-11-5) as well as 1.5 g of trimethylolpropane diacrylate (CAS No. 70, 2, 145 g of trimethylolpropane diacrylate, 2,2, 145 g of trimethylolpropane diacrylate (CAS No. 5-5) in a sealed stirred tank with a sealed stirred at a temperature of DPTA # 52, 52 g of propylene glycol 52, 52 g of propylene glycol under stirring, 2, 52 g of No. 70-5, 52 g of propylene glycol under stirring, 2, 52 g of propylene glycol, 2,2, 2, 53-5, 2,2, 53-6, 53, 5, 2,2, 5g of propylene glycol, 2,2, 5, 2,2, 5;

②, preparing a low-viscosity wax powder dispersion liquid, namely, putting the ① uniformly stirred primary mixed liquid into a high-speed dispersion machine, performing high-speed dispersion, adjusting the dispersion rotation speed to 350rpm, gradually and slowly adding 60g of the basf AF29 spherical high-density polyethylene micro-powder wax weighed in proportion into the low-viscosity primary mixed liquid in the high-speed dispersion process until the primary mixed liquid is completely added, increasing the dispersion rotation speed, adjusting the dispersion rotation speed to 950rpm, continuously performing high-speed dispersion for 4 hours, controlling the integral temperature of the system to be less than or equal to 55 ℃ in the continuous dispersion period until the micro-nano wax powder is dispersed in the low-viscosity primary mixed liquid in a single particle state in the system, stopping the dispersion, and taking out for later use;

③, weighing high-viscosity components, namely uniformly weighing 5g of polyurethane acrylate (sartomer; CN968), 6g of polyurethane acrylate (sartomer; CN981), 7g of aliphatic polyurethane acrylate (sartomer; CN9006) and 2g of hexafunctional polyurethane acrylate (sartomer; CN975) during the process of the step ②, and putting the weighed materials into a lightproof container 2# for later use;

④, after the micro-nano wax powder in step ② is dispersed in the primary mixed liquid in a single particle state in the system, replacing the dispersed substance with the high-viscosity component mixture (in a lightproof container 2 #) weighed in advance in step ③, simultaneously mixing at a low dispersion speed of 50rpm, starting the rotation speed, slowly adding the low-viscosity micro-wax powder dispersion liquid in the container 1# in batches, after the addition is finished, continuing to disperse at a low speed for 30min, after the viscosity of the liquid in the container is uniform, increasing the high dispersion speed to perform first high-speed dispersion at the rotation speed of 550rpm, continuing to disperse for 5h, and controlling the overall temperature of the system to be less than or equal to 65 ℃ during dispersion until the overall appearance of the material is opaque liquid containing a large amount of bubbles, and stopping stirring;

⑤, performing first vacuum defoaming, namely, putting the liquid in the step ④ into vacuum equipment for defoaming, slowly increasing the vacuum degree to-0.1 MPa from normal pressure in 5 steps, increasing the vacuum degree to 0.02MPa in each step, stably placing for a certain time of about 10min under the constant vacuum degree of each step according to the rising degree of bubbles, and continuously increasing the vacuum degree after most of the bubbles quickly rise to the liquid level and burst until the bubbles in the opaque liquid containing a large amount of bubbles after being diluted in the step ④ are completely removed;

⑥, performing secondary high-speed dispersion, namely, completely removing a great amount of bubbles in the mixed system in the step ④, completely removing a great amount of bubbles in the system in the first vacuum defoaming process of the step ⑤, quickly rising the bubbles in the resin in vacuum in the vacuum defoaming process, simultaneously enabling a small part of bubbles in micro-nano wax powder particle aggregates which are not completely scattered or bubbles on the surfaces of the aggregates to float up due to the rise of vacuum degree, replacing the existing part of original gas with liquid when the gas floats up, simultaneously infiltrating the inside of the aggregates with the liquid, and cleaning equipment and related accessories by wiping before the material is placed into a disperser, simultaneously, gradually placing the material after ⑤ into the high-speed disperser, gradually placing the material into a high-speed disperser to avoid secondary pollution of bubbles, gradually placing the material into the high-speed disperser to avoid the secondary pollution of bubbles, continuously controlling the micro-nano wax powder particles to be dispersed in a high-speed dispersion container, gradually placing the high-speed dispersion machine into a high-speed dispersion container, continuously controlling the micro-nano wax powder particles to be immersed in a high-speed dispersion container, continuously and continuously suspending the dispersion container until the micro-nano wax powder particles are suspended in the high-speed dispersion container, and the micro-speed dispersion container is maintained, and the high-speed dispersion container is maintained, and the dispersion is maintained at a high-speed dispersion medium-speed dispersion apparatus is maintained, and the high-speed dispersion is maintained at 750 ℃, and the high-speed dispersion is maintained, and the high-speed dispersion apparatus is maintained, and the high-speed dispersion is maintained, and;

⑦, secondary vacuum defoaming, namely, in the secondary high-speed dispersion process, hardly ensuring that no bubble exists in the system, and in order to eliminate a very small amount of tiny bubbles brought by carelessness in the secondary high-speed dispersion process in the step ⑥ or residual tiny bubbles which cannot be completely removed in the primary vacuum defoaming process, performing vacuum defoaming treatment on the material in the step ⑥ again, wherein the content of bubbles in the system is very small, so that the material is put into vacuum equipment, the vacuum degree can be directly increased to-0.1 MPa and stabilized for 10min until all bubbles in the resin float up to the surface, and after all bubbles in the resin float up to the liquid surface and are broken, the material can not be continuously vacuumized for a long time, and thus, the preparation of the 3D printing photosensitive resin containing the micro-nano wax powder is completed.

In the material, the whole appearance is opaque orange red slurry, the micro-nano wax powder is uniformly distributed in a system in a single particle shape, and the micro-nano wax powder is not layered or settled after being placed for a long time and has good stability. After the model printed by the 3D printer is cleaned by alcohol and solidified in a curing box, the surface precision is high, the detail reflecting degree is good, the material strength and toughness are excellent, no ash residue is left after sintering, the surface of a vacuum casting piece is smooth and has no pores or holes, and the compactness of the sample piece is high.

The embodiment of the invention discloses a preparation process for precisely casting 3D printing photosensitive resin containing micro-nano wax powder, the 3D printing photosensitive resin containing micro-nano wax powder prepared by the process eliminates micro air components carried and wrapped on the surface or inside of the micro-nano wax powder in the resin, and simultaneously scatters micro aggregates of micro-nano particles in a system, so that the micro-nano wax powder can stably exist in the resin in the form of original micro-nano single particles for a long time, the unbalance of the system is also reduced by the vacuum degassing step twice and the high-speed dispersion step twice, the stable and uniform suspension time of the micro-nano particles in the system is greatly prolonged, and the material has good overall stability, can be stored for a long time, is not layered and does not settle. Therefore, the density uniformity of the printing model, the surface smoothness and the surface precision of the model are ensured, the storage quality guarantee time and the long-distance transportation performance of the material are integrally improved, and the printing performance of the material and the mechanical strength of the printing model are greatly improved due to the good dispersion effect. The resin has high printing precision, good formability and high mechanical strength, the shrinkage rate of the material in the printing process is extremely low due to the existence of a large amount of wax powder, and meanwhile, the resin does not expand and ash during high-temperature sintering, the surface of a cast sample piece is smooth and has no air holes or holes, the compactness of the sample piece is high, and the success rate is high. The invention has simple preparation process and is suitable for mass production in factories.

This example provides a preparation process including a high-speed dispersion step and a vacuum defoaming technique, and it is impossible to omit a second high-speed dispersion process in which a mixture having a low viscosity is poured into a mixture having a high viscosity without reversing the order, and a second vacuuming process.

Although the invention has been described in detail above with reference to a general description and specific examples, it will be apparent to one skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.

Claims

1. A preparation method of photosensitive resin containing micro-nano wax powder for 3D printing is characterized in that the photosensitive resin comprises a photoinitiator, an ultraviolet absorbent, an active monomer, a dispersing agent, a color auxiliary agent, a coupling agent, a defoaming agent, micro-nano wax powder and an active oligomer, and the preparation method comprises the following steps:

2. The method according to claim 1, wherein the stirring temperature in the step (1) is 30 ℃ to 95 ℃; stirring for 20min-3 h; the stirring equipment used is a magnetic stirrer or a stirring paddle stirrer; the viscosity of the low-viscosity primary mixed liquid prepared in the step (1) is less than or equal to 1500 cp.

3. The production method according to claim 1, wherein the high-speed dispersing apparatus in the step (2) is a high-speed disperser, a ball mill, a sand mill or a three-roll mixer; in the step (2), after the wax powder is completely added, the dispersion rotating speed is increased to be more than or equal to 300 rpm; the dispersion time is 1-12 h; the integral temperature of the system is controlled to be less than or equal to 95 ℃ during the dispersion period.

4. The production method according to claim 1, wherein the low dispersion speed in step (4) is 500rpm or less; after the wax powder is added, continuously dispersing at a low rotating speed for a period of time less than or equal to 1 h; the lifting to high dispersion speed is more than or equal to 200 rpm; the continuous dispersion time of the first high-speed dispersion is 1-12 h; the integral temperature of the system is controlled to be less than or equal to 95 ℃ during the dispersion period.

5. The production method according to claim 1, wherein the vacuum defoaming in the step (5) is carried out stepwise, and the stable standing time in each step is 1 to 40 min.

6. The process according to claim 1, wherein the dispersing speed in the step (6) is not less than 500 rpm; the continuous dispersion time is 2-8 h; the integral temperature of the system is controlled to be less than or equal to 75 ℃ during the dispersion period.

7. The preparation method according to claim 1, wherein the second vacuum defoaming in the step (7) is to rapidly raise the vacuum degree to-0.1 MPa; the stabilization time is 3-30 min.

8. The method of claim 1, wherein the ingredients used in step (1) comprise a high viscosity material, and/or the ingredients used in step (3) comprise a low viscosity material; the viscosity of the low-viscosity initial mixed liquid in the step (1) after mixing is less than or equal to 300 cp.

9. The production method according to claim 1, wherein in the steps (1) to (7), when mixing and dispersing, a low-viscosity ingredient or mixture is added to a high-viscosity ingredient or mixture.