Low-shrinkage ABS (Acrylonitrile Butadiene Styrene) material for high-speed 3D printing as well as preparation method and application thereof

Abstract

The invention relates to the technical field of 3D printing materials, and discloses a high-speed 3D printing low-shrinkage ABS material and a preparation method and application thereof.The high-speed 3D printing low-shrinkage ABS material is prepared from, by mass, 74-93.8 parts of ABS, 5-20 parts of an anti-shrinkage agent, 1-10 parts of a plasticizer and 0.1-0.5 part of an antioxidant; 0.1 to 0.5 part of a lubricant; the plasticizer is a styrene and acrylonitrile copolymer with the molecular weight of 1000-4000, is similar to ABS in component and good in compatibility, can obviously improve the fluidity of ABS and reduce the glass transition temperature, and basically has no influence on the mechanical property of ABS, so that the high-speed printing effect is achieved, and the high-speed printing ABS material which is low in shrinkage rate, not prone to warping and good in mechanical property is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing materials, and particularly relates to a low-shrinkage ABS material for high-speed 3D printing, a preparation method thereof, and an application thereof. Background Art

[0002] Since the advent of 3D printing technology, it has been widely used in fields such as electronic appliances, mechanical manufacturing, mold sculpture, etc. for manufacturing models and components. Among them, the fused deposition modeling (FDM) technology is one of the most widely used 3D printing technologies. Polymer materials are the most widely used materials in FDM, among which PLA, ABS, PC, and PA are the most widely used. Currently, the most widely used material in the 3D printing industry is the PLA material, but the PLA has the disadvantages of low heat resistance and poor impact performance, and cannot be used in some occasions that require heat resistance and high performance requirements. Some other engineering materials such as PA, PC, etc. have problems such as high printing temperature and difficult forming. Polyolefins such as PP have large shrinkage during printing and not very high heat resistance. And because ABS is more convenient to print compared with PA and PC, the shrinkage is much lower than that of PP, and the heat resistance and impact performance are better than those of PLA, so ABS is widely used in FDM printing.

[0003] With the development of 3D printing technology, the application range is getting wider and wider, the models are getting more and more complex, and the requirements for materials are getting higher and higher. Ordinary ABS has the disadvantages of slow printing and poor forming. For printing large models, the printing speed is relatively slow, which seriously restricts the production efficiency. Moreover, it is easy to shrink, deform, etc. Therefore, there is an urgent need in the market for a high-speed printing ABS that can meet high-speed printing, good formability, and low cost.

[0004] At present, there are few modifications to the printing speed and formability of ABS in the market. Most of them focus on the modification of the mechanical properties of ABS and the reduction of odor. For example, Patent CN105482355A discloses a toughening agent for 3D printing ABS materials and an ABS composite material prepared therefrom. By adding halloysite nanotubes and SBS toughening agents to ABS, the strength and toughness of ABS are improved. The patent only conducts detailed experiments on the mechanical properties, but does not mention data on printing and forming.

[0005] Patent CN111073208A discloses a low-warpage, low-odor 3D printing ABS material and a preparation method thereof. By adding deodorants and using extraction and other means to reduce the odor of ABS, and by adding various fillers to reduce its warpage degree. Although a small amount of plasticizer is added to the formula to improve fluidity and increase the printing speed, because the added is a small molecule plasticizer, it has poor compatibility with ABS, is easy to precipitate and smoke during printing, and will have a greater impact on the impact resistance. It does not take into account both mechanical properties and printing properties at the same time. Summary of the invention

[0006] In view of the common problems of large shrinkage, slow printing speed and easy warping of ABS used in 3D printing technology, the present invention provides a low-shrinkage ABS material for high-speed 3D printing. The material has a low shrinkage rate, can achieve high-speed 3D printing effects, is less likely to crack when subjected to external forces, and has excellent fluidity to ensure the stability of material output during high-speed printing.

[0007] To achieve the above object, the technical solution adopted by the present invention is: A low-shrinkage ABS material for high-speed 3D printing, comprising the following raw material components by weight: 74-93.8 parts of ABS, 5-20 parts of anti-shrinkage agent, 1-10 parts of plasticizer, 0.1-0.5 parts of antioxidant; 0.1-0.5 parts of lubricant; The plasticizer is a polymer with a molecular weight of 1000-4000. The preparation process includes the steps of mixing styrene and acrylonitrile in a solvent, adding an activated clay initiator to the mixed solution for polymerization, adding a terminator after the reaction is completed, and purifying the product to obtain the plasticizer.

[0008] In the present invention, a self-made low molecular weight polymer is used as a plasticizer, which is similar to ABS components and has good compatibility. It can significantly improve the fluidity of ABS and reduce the glass transition temperature while having little effect on the mechanical properties of ABS, thereby achieving a high-speed printing effect.

[0009] Preferably, the molecular weight of the plasticizer is 1000-3500, and more preferably, the molecular weight of the plasticizer is 1000-3000. Plasticizers with low molecular weight have a more obvious effect on improving the printing speed.

[0010] During the preparation of the plasticizer, the mass ratio of styrene to acrylonitrile is 2:8-8:2; The mass ratio of the total mass of styrene and acrylonitrile to the activated clay initiator is 10-30:1.

[0011] The activated clay initiator is added in 3-10 times, with an interval of 1-5 minutes between each addition.

[0012] The temperature of the mixing and polymerization of styrene and acrylonitrile is 0-10°C; the polymerization time is 2-6h; The whole preparation process is carried out under the protection of inert gas; the terminator comprises one or more of ethanol aqueous solution, acetic acid and water, and the mass ratio of the terminator to the total mass of the reaction system is 8-15:100.

[0013] The ABS described above is one kind or a mixture of those produced by the bulk method or the emulsion method, and its melt index is 5-50 g / 10 min. Preferably, the melt index is 10-30 g / 10 min. If the melt index of the ABS is too low, the printing speed will be too slow; if the melt index is too high, the shrinkage deformation will be relatively large. The melt index refers to the value at a temperature of 220 °C and a load of 10 kg.

[0014] The anti-shrinkage agent is one or more of styrene-butadiene-acrylonitrile graft copolymer, ethylene-propylene-diene terpolymer, and acrylate core-shell copolymer; The antioxidant includes one or several of hindered amine antioxidants, hindered phenol antioxidants, phosphite antioxidants, and polymer antioxidants; The lubricant is one or more of calcium stearate, zinc stearate, stearamide, ethylene bisstearamide, and paraffin.

[0015] The present invention also provides a method for preparing the low-shrinkage ABS material for high-speed 3D printing, including the steps of: mixing the dried ABS, anti-shrinkage agent, plasticizer, antioxidant, and lubricant according to a mass ratio, and melt-blending and extruding granulation at 210-230 °C to obtain the low-shrinkage ABS material for high-speed 3D printing.

[0016] The present invention also provides the application of the low-shrinkage ABS material for high-speed 3D printing in the preparation of 3D printing finished products, and the shrinkage rate of the 3D printing finished products is below 0.6%; the printing speed during the application process can be above 600 mm / s.

[0017] In order to make the ABS material show better layer adhesion in FDM printing, a low-molecular-weight polymer (styrene-acrylonitrile copolymer) is added in the ABS modification, which reduces the glass transition temperature (Tg) and softening point of the ABS material. A lower Tg temperature and softening point mean that the material can be melted at a lower temperature during FDM printing, and under the same heating conditions, the fluidity will be better, thus improving the printing speed. At the same time, the lower Tg also helps to enhance the adhesion between layers.

[0018] While the printing speed is increased, the shrinkage problem of the material needs to be considered. Too fast printing speed is likely to cause shrinkage and warping of the material. Therefore, an anti-shrinkage agent is selected in the ABS modification to reduce the shrinkage rate of the material. By controlling the size and distribution of rubber particles in the material, the shrinkage rate of the material can be greatly reduced. The addition of the low-molecular-weight polymer is beneficial to the lubrication between molecular chains, so that the anti-shrinkage agent is more evenly dispersed in the ABS matrix. Therefore, by adding a self-made plasticizer and regulating the type and proportion of the anti-shrinkage agent, a low-shrinkage 3D printing high-speed ABS material is prepared.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) While ensuring the mechanical properties of the 3D printed finished product, the printing speed of the material is greatly improved, and the highest can reach 900 mm / s; while maintaining a high printing speed, the synergistic effect of the plasticizer and the anti-shrinkage agent results in a low shrinkage rate of the product and is not prone to warping; (2) The product is safe and environmentally friendly. Different from other small molecule plasticizers, the plasticizer in the present invention is a polymer, which is not easy to precipitate and has strong stability. Description of the Drawings

[0020] Figure 1 It is a schematic diagram of the 3D printed test finished product model in the application example.

[0021] Figure 2 It is the molecular weight distribution diagram of plasticizers A1, A2 and A3 prepared in Examples 1-3.

[0022] Figure 3 It is the DSC diagram of B1 and B4 in the application example.

[0023] Figure 4 It is the TEM diagram of B1, B2 and B4 in the application example. Detailed Embodiments

[0024] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Those skilled in the art make modifications or equivalent replacements on the basis of understanding the technical solutions of the present invention, and without departing from the spirit and scope of the technical solutions of the present invention, they should all be covered within the protection scope of the present invention.

[0025] The raw materials used in the following detailed embodiments are all purchased from the market. Among them, styrene, acrylonitrile, dichloromethane, activated clay initiator, ethanol aqueous solution (concentration 95%), and methanol solution are all purchased from Sinopharm. The ABS resin is selected as Chi Mei PA-757, the anti-shrinkage agent is selected as Kumho HR181, the antioxidant is selected as BASF 1010 and 168, and the lubricant is selected as HA.

[0026] 3D printing test material 3D printing effect and finished product performance: 1. Use the collected wire to print the model as shown in Figure 1 on a 3D printer. The head temperature of the printer is set to 260 °C, the bottom plate temperature is 80 °C, and the printing speed is set to a maximum of 1000 mm / s.

[0027] 2. After printing is completed, judge the interlayer bonding force, and the tensile rate is 5 mm / min; 3. Shrinkage rate test: Taking the geometric center of the printed test model as the reference, test the degree of inward shrinkage.

[0028] 4. Impact performance test: Adopt GB / T 1843, with a pendulum hammer of 1 J; 5. Melt index test: The temperature is 220 °C and the load is 10 kg; 6. Phase morphology test: After cryosectioning the particles, use TEM to view the phase morphology.

[0029] Example 1 Step 1: First, introduce nitrogen into a three-necked flask equipped with a drying tube, a thermometer, and an electric stirrer for 15 min to displace the air. Step 2: Sequentially add styrene, acrylonitrile, and dichloromethane and stir evenly. Adjust the low-temperature water bath to a constant temperature of 6 °C. After stirring for 5 min, add the activated clay initiator in 8 portions at intervals of 2 min each. After the catalyst is added, the mixture reacts at 6 °C for 200 min, and then an ethanol aqueous solution is added to terminate the reaction. The addition amount of the ethanol aqueous solution is in a ratio of 1:10 to the total mass of the monomer, catalyst, and solvent. The mass ratio of styrene, acrylonitrile to the activated clay initiator is 10:10:1, the mass ratio of the sum of the masses of styrene and acrylonitrile to dichloromethane is 1:1.2, and the ratio of styrene to acrylonitrile is 5:5. Step 3: After the reaction is completed, filter out the initiator by vacuum filtration, slowly pour the reaction solution into methanol with a mass ten times that of the reaction solution for precipitation, and after the product precipitates, obtain a white solid product by suction filtration, denoted as A1.

[0030] Example 2 Step 1: First, introduce nitrogen into a three-necked flask equipped with a drying tube, a thermometer, and an electric stirrer for 15 min to displace the air. Step 2: Sequentially add styrene, acrylonitrile, and dichloromethane and stir evenly. Adjust the low-temperature water bath to a constant temperature of 6 °C. After stirring for 5 min, add the activated clay initiator in 8 portions at intervals of 2 min each. After the catalyst is added, the mixture reacts at 6 °C for 250 min, and then an ethanol aqueous solution is added to terminate the reaction. The addition amount of the ethanol aqueous solution is in a ratio of 1:10 to the total mass of the monomer, catalyst, and solvent. The mass ratio of styrene, acrylonitrile to the activated clay initiator is 12:12:1, the mass ratio of the sum of the masses of styrene and acrylonitrile to dichloromethane is 1:1.2, and the ratio of styrene to acrylonitrile is 5:5. Step 3: After the reaction is completed, filter out the initiator by vacuum filtration, slowly pour the reaction solution into methanol with a mass ten times that of the reaction solution for precipitation, and after the product precipitates, obtain a white solid product by suction filtration, denoted as A2.

[0031] Example 3 Step 1: First, introduce nitrogen into a three-necked flask equipped with a drying tube, a thermometer, and an electric stirrer for 15 minutes to displace the air. Step 2: Add styrene, acrylonitrile, and dichloromethane in sequence and stir evenly. Adjust the low-temperature water bath to a constant temperature of 6°C. After stirring for 5 minutes, add the activated clay initiator in 8 portions at intervals of 2 minutes each. After the addition of the catalyst is complete, react at 6°C for 300 minutes, and then add an ethanol aqueous solution to terminate the reaction. The addition amount of the ethanol aqueous solution is in a ratio of 1:10 to the total mass of the monomers, the catalyst, and the solvent. The mass ratio of styrene, acrylonitrile, and the activated clay initiator is 12:12:1. The mass ratio of the sum of the masses of styrene and acrylonitrile to dichloromethane is 1:1.2, and the ratio of styrene to acrylonitrile is 5:5. Step 3: After the reaction is completed, filter out the initiator by vacuum filtration. Slowly pour the reaction solution into methanol with a mass ten times that of the reaction solution for precipitation. After the product precipitates, filter it to obtain a white solid product, denoted as A3.

[0032] Figure 2 Figures for the molecular weight distributions of A1, A2, and A3, where the molecular weight of A1 is 1084, the molecular weight of A2 is 2813, and the molecular weight of A3 is 4754.

[0033] Application Example Dry the ABS resin and the anti-shrinkage agent in an oven. After drying, weigh the dried ABS, anti-shrinkage agent, plasticizer, antioxidant, and lubricant according to the mass ratios in Table 1 and put them into a high-speed mixer to mix evenly. Add the mixed material to a twin-screw extruder and melt-extrude at 210 - 230°C. Granulate at a rotational speed of 300 rpm, and then dry the obtained pellets and draw them into 1.75 mm wires.

[0034] Table 1 Mass portions of raw materials for each application example

[0035] Table 2 3D printing test results of wires for each application example

[0036] Table 2 shows the 3D printing test results of the wires obtained in each application example. It can be seen from Table 2 that when the same anti-shrinkage agent is added in B1 - B5, compared with the commercially available plasticizer, the self-made plasticizer shows a more obvious increase in the maximum printing speed. Among them, compared with B1, for B3 - B5, after adding the self-made plasticizer, not only can the maximum printing speed be increased, but also it can cooperate with the anti-shrinkage agent to reduce the product shrinkage rate, and the interlayer bonding force is also improved.

[0037] As can be seen from B3 - B5, the molecular weight of the self - made plasticizer also has a relatively obvious effect on the maximum printing speed of the wire. The low molecular weight of A1 is the lowest, and the printing speed can reach 900 mm / s.

[0038] Comparing B4, B8, and B9, with other components fixed, when the anti - shrinkage agent is increased to 20 parts, the shrinkage rate can be reduced from 0.8% to 0.4%. However, if the content of the anti - shrinkage agent is too high, it will affect the printing speed.

[0039] When the plasticizer content in B4, B10, and B11 is increased from 5 parts to 15 parts, its maximum printing speed is increased from 600 mm / s to 850 mm / s. However, the notch impact strength decreases significantly. Therefore, it is comprehensively preferred to add 10 parts.

[0040] Figure 3 Figure for DSC of wire B4 prepared by adding self - made plasticizer A2 and wire B1 without adding plasticizer. It can be seen from the figure that adding self - made plasticizer can significantly reduce the glass transition temperature, which is beneficial to improving the product fluidity and thus significantly improving the 3D printing speed.

[0041] Figure 4 Figure for TEM of B1, B2, and B4. It can be seen from the figure that adding commercially available plasticizer can significantly reduce the size of the anti - shrinkage agent. While adding self - made plasticizer, the phase size can be further reduced and is more uniform. The self - made plasticizer not only improves the ABS printing speed but also helps the anti - shrinkage agent to be more evenly distributed, playing a certain synergistic effect with the anti - shrinkage agent, which is also the reason why it does not affect the impact resistance performance.

Claims

1. A low shrinkage ABS material for high-speed 3D printing, characterized in that: According to the weight percentage, the raw material components include: ABS 74-93.8 parts, anti-shrinkage agent 5-20 parts, plasticizer 1-10 parts, antioxidant 0.1-0.5 parts; lubricant 0.1-0.5 parts; The plasticizer is a polymer with a molecular weight of 1000-4000. The preparation process includes the steps of mixing styrene and acrylonitrile in a solvent, adding an activated clay initiator to the mixed solution for polymerization, adding a terminator after the reaction is completed, and purifying the product to obtain the plasticizer.

2. The low shrinkage ABS material for high-speed 3D printing according to claim 1, characterized in that: During the preparation of the plasticizer, the mass ratio of styrene to acrylonitrile is 2:8-8:

2.

3. The low shrinkage ABS material for high-speed 3D printing according to claim 1, characterized in that: The mass ratio of the total mass of styrene and acrylonitrile to the activated clay initiator is 10-30:

1.

4. The low shrinkage ABS material for high-speed 3D printing according to claim 1, characterized in that: The activated clay initiator is added in 3-10 times, with an interval of 1-5 minutes between each addition.

5. The low shrinkage ABS material for high-speed 3D printing according to claim 1, characterized in that: The temperature of the mixing and polymerization of styrene and acrylonitrile is 0-10°C; the polymerization time is 2-6h; And / or, the entire preparation process is carried out under the protection of inert gas; the terminator includes one or more of an aqueous solution of ethanol, acetic acid, and water, and the mass ratio of the terminator to the total mass of the reaction system is 8-15:

100.

6. The low shrinkage ABS material for high-speed 3D printing according to claim 1, characterized in that: The ABS is produced by bulk method or emulsion method or a mixture thereof, and has a melt index of 5-50 g / 10 min.

7. The low shrinkage ABS material for high-speed 3D printing according to claim 1, characterized in that: The anti-shrinkage agent is one or more of styrene-butadiene-acrylonitrile grafts, ethylene-propylene-diene terpolymers, and acrylic ester core-shell copolymers; The antioxidant includes one or more of hindered amine antioxidants, hindered phenol antioxidants, phosphite antioxidants, and polymer antioxidants; The lubricant is one or more of calcium stearate, zinc stearate, stearamide, ethylene bis stearamide, and paraffin.

8. The method for preparing a low shrinkage ABS material for high-speed 3D printing according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: mixing dried ABS, an anti-shrinkage agent, a plasticizer, an antioxidant and a lubricant according to a mass ratio, and subjecting the mixture to melt-blending, extruding and granulating at 210-230° C. to obtain the low-shrinkage ABS material for high-speed 3D printing.

9. The use of the low shrinkage ABS material for high-speed 3D printing according to any one of claims 1 to 7 in preparing 3D printed products, characterized in that: The shrinkage rate of the 3D printed product is below 0.6%.

10. The use of the low shrinkage ABS material for high-speed 3D printing according to claim 9 in preparing 3D printed products, characterized in that: During the application process, the printing speed can reach over 600 mm / s.

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