A low-shrinkage ABS material for high-speed 3D printing, its preparation method and application

Abstract

The present invention relates to the technical field of 3D printing materials, and discloses a low-shrinkage ABS material for high-speed 3D printing, a preparation method thereof, and an application thereof. The low-shrinkage ABS material comprises the following raw material components, calculated by weight: 74-93.8 parts of ABS, 5-20 parts of an anti-shrinkage agent, 1-10 parts of a plasticizer, 0.1-0.5 parts of an antioxidant, and 0.1-0.5 parts of a lubricant. The plasticizer is a styrene and acrylonitrile copolymer with a molecular weight of 1000-4000, which is similar to the composition of ABS and has good compatibility. It can significantly improve the fluidity of ABS, reduce the glass transition temperature, and have little effect on the mechanical properties of ABS, thereby achieving a high-speed printing effect and obtaining a high-speed printing ABS material with low shrinkage, low warping, and good mechanical properties.

Description

Technical Field

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

[0002] Since its inception, 3D printing technology has been widely used in electronics, machinery, molds, and sculpture to create models and parts. Fused deposition modeling (FDM) is the most widely used 3D printing technology. Polymers are the most widely used materials in FDM, with PLA, ABS, PC, and PA being the most widely used. Currently, PLA is the most widely used material in the 3D printing industry. However, PLA suffers from low temperature resistance and poor impact resistance, making it unsuitable for applications requiring high heat resistance and high performance. Other engineering materials, such as PA and PC, also face challenges with high printing temperatures and molding difficulties. Polyolefins, such as PP, shrink significantly when printing and have limited heat resistance. ABS, on the other hand, is widely used in FDM printing because it is easier to print than PA and PC, shrinks much less than PP, and has superior heat resistance and impact resistance compared to PLA.

[0003] With the development of 3D printing technology, its applications are expanding, models are becoming more complex, and material requirements are becoming increasingly demanding. Conventional ABS has the disadvantages of slow printing and poor molding. For printing large models, the slow printing speed seriously restricts production efficiency. Furthermore, it is prone to shrinkage and deformation. Therefore, the market urgently needs an ABS material that can meet high-speed printing requirements, has good moldability, and is cost-effective.

[0004] Currently, there are few improvements on the printing speed and formability of ABS on the market. Most of the modifications focus on improving ABS's mechanical properties and reducing odor. For example, patent CN105482355A discloses a reinforcing and 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 mechanical properties and does not mention data on printing and forming.

[0005] Patent CN111073208A discloses a low-warpage, low-odor 3D printing ABS material and its preparation method. The odor of the ABS is reduced by adding a deodorizer and using extraction methods, and the warpage is reduced by adding various fillers. Although a small amount of plasticizer is added to the formula to improve fluidity and increase printing speed, the added small molecule plasticizer has poor compatibility with ABS, easily precipitating and generating smoke during printing, and significantly affecting impact resistance. Therefore, both mechanical and printing properties are not taken into account. Summary of the Invention

[0006] In response to 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. This 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 stable output during high-speed printing.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A low-shrinkage ABS material for high-speed 3D printing, comprising the following raw material components, calculated by weight: 74-93.8 parts of ABS, 5-20 parts of an anti-shrinkage agent, 1-10 parts of a plasticizer, 0.1-0.5 parts of an antioxidant, and 0.1-0.5 parts of a lubricant.

[0009] The plasticizer is a polymer with a molecular weight of 1000-4000. The preparation process includes the following steps: mixing styrene and acrylonitrile in a solvent, adding an activated clay initiator to the mixed solution to carry out a polymerization reaction, adding a terminator after the reaction is completed, and purifying the product to obtain the plasticizer.

[0010] In the present invention, a self-made low-molecular-weight polymer is used as a plasticizer. The plasticizer has similar composition to ABS and 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 high-speed printing.

[0011] 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.

[0012] During the preparation of the plasticizer, the mass ratio of styrene to acrylonitrile is 2:8-8:2;

[0013] The mass ratio of the total mass of styrene and acrylonitrile to the activated clay initiator is 10-30:1.

[0014] The activated clay initiator is added in 3-10 times, with an interval of 1-5 minutes between each addition.

[0015] The temperature of the mixing and polymerization of styrene and acrylonitrile is 0-10°C; the polymerization reaction time is 2-6h;

[0016] The entire preparation process is carried out under the protection of inert gas; the terminator comprises 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.

[0017] The ABS is produced by either bulk or emulsion methods, or a mixture thereof, and has a melt index of 5-50 g / 10 min. Preferably, the melt index is 10-30 g / 10 min. A low melt index for ABS results in slow printing, while a high melt index results in significant shrinkage and deformation. The melt index refers to the value at 220°C and a load of 10 kg.

[0018] The anti-shrinkage agent is one or more of styrene-butadiene-acrylonitrile grafts, ethylene-propylene-diene terpolymers, and acrylic ester core-shell copolymers;

[0019] The antioxidant includes one or more of hindered amine antioxidants, hindered phenol antioxidants, phosphite antioxidants, and polymer antioxidants;

[0020] The lubricant is one or more of calcium stearate, zinc stearate, stearamide, ethylene bisstearamide, and paraffin.

[0021] The present invention also provides a method for preparing the low-shrinkage ABS material for high-speed 3D printing, comprising the steps of: mixing dried ABS, an anti-shrinkage agent, a plasticizer, an antioxidant, and a lubricant according to a mass ratio, and melt-blending, extruding, and granulating at 210-230° C. to obtain the low-shrinkage ABS material for high-speed 3D printing.

[0022] The present invention also provides the use of the low-shrinkage ABS material for high-speed 3D printing in the preparation of 3D printed products, wherein the shrinkage rate of the 3D printed products is below 0.6%; and the printing speed during the application process can be above 600 mm / s.

[0023] To improve the layer adhesion of ABS materials in FDM printing, a low molecular weight polymer (styrene-acrylonitrile copolymer) is added to the modified ABS, lowering the ABS material's glass transition temperature (Tg) and softening point. Lower Tg and softening point mean the material can melt at a lower temperature during FDM printing. Under the same heating conditions, it has better fluidity, thereby increasing printing speed. A lower Tg also helps improve the direct adhesion between layers.

[0024] While increasing printing speed, material shrinkage must be considered. Excessively fast printing speeds can easily lead to shrinkage and warping. Therefore, anti-shrinkage agents were selected during ABS modification to reduce the material's shrinkage. Controlling the size and distribution of rubber particles within the material significantly reduces shrinkage. The addition of low-molecular-weight polymers facilitates lubrication between molecular chains, allowing the anti-shrinkage agent to be more evenly dispersed within the ABS matrix. Therefore, by adding a homemade plasticizer and adjusting the type and ratio of the anti-shrinkage agent, a low-shrinkage, high-speed ABS material for 3D printing was prepared.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) While ensuring the mechanical properties of the 3D printed product, the printing speed of the material is greatly improved, reaching a maximum of 900 mm / s; while maintaining a high printing speed, the synergistic effect of the plasticizer and the anti-shrinkage agent makes the product shrinkage rate low and less prone to warping;

[0027] (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. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the 3D printed test product model in the application example.

[0029] Figure 2 The molecular weight distribution diagram of plasticizers A1, A2 and A3 prepared in Examples 1-3.

[0030] Figure 3 The DSC graphs of B1 and B4 in the application examples are shown in FIG.

[0031] Figure 4 TEM images of B1, B2, and B4 in the application example. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiment. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Those skilled in the art will make modifications or equivalent substitutions based on understanding the technical solution of the present invention, without departing from the spirit and scope of the technical solution of the present invention, and all should be encompassed within the protection scope of the present invention.

[0033] The raw materials used in the following specific embodiments were all purchased from the market. Styrene, acrylonitrile, dichloromethane, activated clay initiator, ethanol aqueous solution (95% concentration), and methanol solution were all purchased from Sinopharm. Chimei PA-757 was used as ABS resin, Kumho HR181 as anti-shrinkage agent, BASF 1010 and 168 as antioxidants, and HA as lubricant.

[0034] 3D printing test material 3D printing effect and finished product performance:

[0035] 1. Use the collected filament to print on a 3D printer. Figure 1 For the model shown, the printer head temperature is set to 260°C, the base plate temperature is 80°C, and the maximum printing speed is set to 1000 mm / s.

[0036] 2. After printing is completed, the interlayer bonding strength is determined, and the stretching rate is 5mm / min;

[0037] 3. Shrinkage test: Based on the geometric center of the printed test model, test the degree of inward shrinkage.

[0038] 4. Impact performance test: GB / T 1843 is used, and the pendulum is 1J;

[0039] 5. Melt index test: temperature 220℃, load 10kg;

[0040] 6. Phase morphology test: After the particles are frozen and sectioned, the phase morphology is examined using TEM.

[0041] Example 1

[0042] Step 1: nitrogen was introduced into a three-necked flask equipped with a drying tube, a thermometer, and an electric stirrer for 15 minutes to displace the air;

[0043] Step 2, add styrene, acrylonitrile and dichloromethane in sequence and stir evenly, adjust the low-temperature water bath constant temperature to 6°C. After stirring for 5 minutes, add the activated clay initiator in 8 times, with an interval of 2 minutes each time. After the catalyst is added, the mixture is reacted at 6°C for 200 minutes, and an ethanol aqueous solution is added to terminate the reaction. The ratio of the amount of ethanol aqueous solution added to the total mass of the monomer, catalyst and solvent is 1:10. The mass ratio of styrene, acrylonitrile and activated clay initiator is 10:10:1, the mass ratio of the sum of the mass of styrene and acrylonitrile to dichloromethane is 1:1.2, and the ratio of styrene to acrylonitrile is 5:5;

[0044] Step 3: After the reaction is completed, the initiator is filtered off under reduced pressure, and the reaction solution is slowly introduced into methanol with a mass ten times that of the reaction solution for precipitation. After the product precipitates, it is filtered to obtain a white solid product, which is recorded as A1.

[0045] Example 2

[0046] Step 1: nitrogen was introduced into a three-necked flask equipped with a drying tube, a thermometer, and an electric stirrer for 15 minutes to displace the air;

[0047] Step 2, add styrene, acrylonitrile and dichloromethane in sequence and stir evenly, adjust the low-temperature water bath constant temperature to 6°C. After stirring for 5 minutes, add the activated clay initiator in 8 times, with an interval of 2 minutes each time. After the catalyst is added, react at 6°C for 250 minutes, and add ethanol aqueous solution to terminate the reaction. The ratio of the amount of ethanol aqueous solution added to the total mass of monomer, catalyst and solvent is 1:10. The mass ratio of styrene, acrylonitrile and activated clay initiator is 12:12:1, the mass ratio of the sum of the mass of styrene and acrylonitrile to dichloromethane is 1:1.2, and the ratio of styrene to acrylonitrile is 5:5;

[0048] Step 3: After the reaction is completed, the initiator is filtered off under reduced pressure, and the reaction solution is slowly introduced into methanol with a mass ten times that of the reaction solution to precipitate the product. After the product precipitates, it is filtered to obtain a white solid product, which is recorded as A2.

[0049] Example 3

[0050] Step 1: nitrogen was introduced into a three-necked flask equipped with a drying tube, a thermometer, and an electric stirrer for 15 minutes to displace the air;

[0051] Step 2, add styrene, acrylonitrile and dichloromethane in sequence and stir evenly, adjust the low-temperature water bath constant temperature to 6°C. After stirring for 5 minutes, add the activated clay initiator in 8 times, with an interval of 2 minutes each time. After the catalyst is added, react at 6°C for 300 minutes, and add ethanol aqueous solution to terminate the reaction. The ratio of the amount of ethanol aqueous solution added to the total mass of monomer, catalyst and solvent is 1:10. The mass ratio of styrene, acrylonitrile and activated clay initiator is 12:12:1, the mass ratio of the sum of the mass of styrene and acrylonitrile to dichloromethane is 1:1.2, and the ratio of styrene to acrylonitrile is 5:5;

[0052] Step 3: After the reaction is completed, the initiator is filtered off under reduced pressure, and the reaction solution is slowly introduced into methanol with a mass ten times that of the reaction solution to precipitate the product. After the product precipitates, it is filtered to obtain a white solid product, which is recorded as A3.

[0053] Figure 2 This is the molecular weight distribution diagram 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.

[0054] Application Examples

[0055] The ABS resin and antishrinkage agent were dried in an oven. The dried ABS, antishrinkage agent, plasticizer, antioxidant, and lubricant were weighed according to the mass ratio in Table 1 and then put into a high-speed mixer for uniform mixing. The mixed materials were added to a twin-screw extruder for melt extrusion at 210-230°C and granulation at a speed of 300 rpm. The obtained granules were then dried and stretched to produce 1.75 mm wire.

[0056] Table 1 Mass fraction of raw materials in each application example

[0057]

[0058] Table 2 3D printing test results of wire materials in various application examples

[0059]

[0060] Table 2 shows the 3D printing test results of the filaments obtained from various application examples. As can be seen from Table 2, when adding the same anti-shrinkage agent, the homemade plasticizer significantly improves the maximum printing speed of B1-B5 compared to commercially available plasticizers. Specifically, compared with B1, the addition of the homemade plasticizer not only increases the maximum printing speed, but also synergistically reduces product shrinkage with the anti-shrinkage agent, and improves the bonding strength between layers.

[0061] As can be seen from B3-B5, the molecular weight of the homemade plasticizer also has a significant impact on the maximum printing speed of the filament. A1 has the lowest molecular weight and can reach a printing speed of 900 mm / s.

[0062] Compared with B4, B8 and B9, if the other components are fixed and the anti-shrinkage agent is increased to 20 parts, the shrinkage rate can be reduced from 0.8% to 0.4%. Too high an anti-shrinkage agent content will affect the printing speed.

[0063] B4, B10 and B11 increase the plasticizer content from 5 parts to 15 parts, and their maximum printing speed increases from 600mm / s to 850mm / s, but the notched impact strength decreases significantly. Therefore, it is generally preferred to add 10 parts.

[0064] Figure 3 The DSC graphs of filament B4 prepared with homemade plasticizer A2 and filament B1 without plasticizer are shown. As can be seen from the graph, the addition of homemade plasticizer can significantly reduce the glass transition temperature, which is beneficial to improving product fluidity, thereby significantly improving 3D printing speed.

[0065] Figure 4TEM images of B1, B2, and B4 show that adding a commercially available plasticizer significantly reduces the size of the anti-shrinkage agent. Adding a homemade plasticizer further reduces the size of the phases and makes them more uniform. While the homemade plasticizer increases ABS printing speed, it also helps to evenly distribute the anti-shrinkage agent, creating a synergistic effect with the anti-shrinkage agent and contributing to its non-impact performance.

Claims

1. A low shrinkage ABS material for high-speed 3D printing, characterized in that: The raw material components are as follows: 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, and the preparation process includes the following steps: mixing styrene and acrylonitrile in a solvent, adding an activated clay initiator to the mixed solution to carry out a polymerization reaction, adding a terminator after the reaction is completed, and purifying the product to obtain the plasticizer; The anti-shrinkage agent is one or more of styrene-butadiene-acrylonitrile grafts, ethylene-propylene-diene terpolymers, and acrylic ester core-shell copolymers; The low shrinkage ABS material can be used in a 3D printing process at a printing speed of more than 600 mm / s.

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 reaction 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 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 bisstearamide, 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. 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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