Wet coloring post-processing method for 3D printed part

Abstract

The invention belongs to the technical field of post-processing of 3D printed parts, and particularly relates to a wet coloring post-processing method of a 3D printed part. The method comprises the following steps: a) preparing dye liquor; b) preparing a 3D printed piece with micropores in the surface; c) placing the 3D printed piece in the dye liquor, heating and applying a mechanical effect to promote coloring; and d) slightly dissolving the surface of the workpiece by using an organic solvent mixed solution to promote fixation of the dyeing material. Compared with a traditional post-treatment mode, the method has the advantages that the coloring process is convenient and fast, operation is convenient, the use cost is saved, the used dye liquor and organic solvent mixed liquor can be recycled, the use amount of the organic solvent in the color fixing process is small, the environmental influence factor is small, the requirement for the shape of the workpiece is low, and the applicability to 3D printing complex-structure workpieces is higher; the coloring of a plane structure and a complex structure is facilitated, the color fastness is good, the mechanical property is obviously improved, and the surface roughness is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of 3D printed product post-processing, and in particular relates to a wet coloring post-processing method for 3D printed products. Background Art

[0002] Additive Manufacturing (AM) technology, also known as 3D Printing (3DP) technology, is a manufacturing technology that uses software and CNC system control to produce physical objects by stacking special metal materials, non-metallic materials and medical biomaterials layer by layer through extrusion, sintering, melting, photocuring, spraying, etc.

[0003] Powder Bed Fusion (PBF) is a type of additive manufacturing technology that uses heat energy to selectively fuse granular materials into solid shapes. Granular printing media such as metals, ceramics, and polymers are spread on the surface of the build platform to form a powder bed. Based on the information provided by the CAD file, the powder bed fusion machine applies heat energy to specific areas of the powder bed to combine the particles into a solid layer. Then another thin layer of powder is added, and the above process is repeated until a part with a preset three-dimensional shape is made.

[0004] With the development of 3D printing technology, there are more and more post-processing methods for PBF printed parts. The existing post-processing methods for PBF printed parts are mainly spraying or dipping water-based paint.

[0005] Water-based paint has high coloring efficiency and good coloring stability, but it is expensive, uses a large amount of water during processing, and has problems with waste liquid recycling; the fine-structured products after post-processing have uneven liquid accumulation, the product is prone to small bubbles, and has poor wear resistance and weather resistance.

[0006] The spraying or dipping process is easy to operate and color quickly. It can be operated in batches for flat structures or large-pore structures with strong supports, and has good environmental color fastness. However, it can unevenly treat fine pore structures, easily block pores, and needs to be prepared and used immediately, which has high requirements on the operating environment, equipment and operators. Summary of the invention

[0007] In view of the shortcomings of the prior art, the present invention provides a wet coloring post-processing method for 3D printed parts. The method is intended to be applied to complex 3D printed parts at a lower cost and higher efficiency, improve the surface roughness of 3D printed parts, enhance their mechanical properties, improve the processing effect of surface microstructures, and improve the overall aesthetics.

[0008] The method of the present invention disperses the dyeing material in a weakly acidic water system, puts it into a 3D printed part, infiltrates the dyeing material into the microporous structure of the part through mechanical action to cause physical and chemical combination, and then uses a selected solvent system to perform chemical surface treatment on it to achieve color fixation and enhancement of the part.

[0009] The wet coloring post-processing method of a 3D printed product provided by the present invention comprises the following steps:

[0010] a) preparing a dye liquor; the dye liquor contains a dye, a leveling agent and water, the dye is evenly dispersed in the aqueous phase, and the leveling agent promotes stable dispersion of the dye in the aqueous phase;

[0011] b) preparing 3D printed parts; the 3D printed parts are non-metallic polymer parts with micropores on the surface;

[0012] c) Coloring of 3D printed parts: placing the 3D printed parts in a dye solution, heating them, and promoting the dye material to penetrate into the micropores of the 3D printed parts through mechanical action, and then taking out the 3D printed parts and draining off excess dye solution;

[0013] d) color fixation of 3D printed parts; using an organic solvent mixture to fix the parts obtained in step c), the organic solvent mixture slightly dissolves and reshapes the surface of the parts to promote the closure of surface pores to fix the dyeing material; after color fixation, the residual organic solvent is removed to obtain a 3D printed part after wet coloring.

[0014] As a further optimization scheme for the wet coloring post-processing method of 3D printed parts, the material of the 3D printed parts is selected from any one of the hard plastics PA12, PA11, ABS, PEEK, PP and the elastic plastics TPA, TPU.

[0015] As a further optimization scheme for the wet coloring post-processing method of 3D printed parts, the 3D printed parts are powder bed fusion printed parts.

[0016] As a further optimization scheme for the wet coloring post-treatment method of 3D printed parts, the mass ratio of dye, leveling agent and water in the dye solution is (0.01-0.1):(0.01-0.05):(10-60); the dye is one or more of direct dye, insoluble azo dye, vat dye, sulfur dye and acid dye.

[0017] As a further optimization scheme for the wet coloring post-processing method of 3D printed parts, the 3D printed parts prepared in step b) are TPA parts of selective laser sintering (SLS); the organic solvent mixture used for color fixation in step d) is two or more of ethanol, acetone, chloroform, dichloromethane, hexafluoroisopropanol, dimethylacetamide (DMA), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO).

[0018] As a further optimization scheme for the wet coloring post-treatment method of 3D printed parts, in step b), the organic solvent DMA and ethanol are evenly mixed in a ratio of (1 to 20):1 at room temperature to obtain a mixed solution for color fixation; the colored TPA part is completely immersed in the mixed solution for 15 to 300 seconds, and then the TPA part treated with the organic solvent is dried by forced air at a temperature of 50°C for 48 hours to obtain a 3D printed part treated by wet coloring.

[0019] As a further optimization scheme for the wet coloring post-treatment method of 3D printed parts, the 3D printed parts prepared in step b) are PA12 parts of multi-jet melt molding (MJF); the organic solvent mixture used for color fixing in step d) is two or more of N,N-dimethylformamide (DMF), ethanol, 1,4-dioxane, tetrahydrofuran, acetone, dichloromethane, chloroform, toluene, hexafluoroisopropanol, and n-hexane.

[0020] As a further optimization scheme for the wet coloring post-treatment method of 3D printed parts, in step b), the organic solvent DMF and ethanol are evenly mixed at a ratio of (1 to 20): 1 at room temperature to obtain a mixed solution for color fixation, and the colored PA12 parts are completely immersed in the mixed solution for 15 to 180 seconds, and then the PA12 parts treated with the organic solvent are dried at a temperature of 80°C for 48 hours to obtain 3D printed parts treated with wet coloring.

[0021] As a further optimization scheme for the wet coloring post-processing method of 3D printed parts, in step c), the source of mechanical action is selected from a heating ultrasonic machine, a low-noise oscillating machine, and an infrared dyeing machine.

[0022] As a further optimization scheme for the wet coloring post-treatment method of 3D printed parts, in step c), the 3D printed parts are placed in the dye solution, and a heating ultrasonic machine, a low-noise oscillator, or an infrared dyeing machine is set to 80-95° C., and the temperature is slowly increased at 5° C. / min. After reaching the set temperature, the temperature is kept for 15-120 minutes.

[0023] Beneficial Effects

[0024] The surface of PBF printed parts is rough and has a large number of micron-level pores. By immersing the printed parts in the prepared dye solution and placing them in equipment or instruments such as ultrasonic machines / low-noise oscillators / infrared dyeing machines, the dispersed dyeing materials are infiltrated into the microporous structure of the PBF parts through the high temperature environment and mechanical action provided by the equipment, so that the printed parts and the dyeing materials are physically and chemically combined to achieve the coloring effect, thereby solving the common problem of uneven coloring of fine structures and further improving the physical and mechanical properties of the printed parts.

[0025] After coloring, a small amount of organic solvent mixture system is used to slightly dissolve the surface of the PBF printed part, so that the micropores on the surface are sealed to further fix the dye, enhance the color fastness, and smooth the surface of the part.

[0026] Compared with the traditional post-processing method, the method of the present invention has a convenient coloring process, is easy to operate, and saves use costs. The dye solution and the organic solvent mixture used can be recycled. The amount of organic solvent used in the color fixing process is small and the environmental impact factor is small. The requirements for the shape of the parts are relatively low. It is more suitable for 3D printing of complex structure parts, is conducive to the coloring of planar structures and complex structures, has good color fastness, significantly improves mechanical properties, and improves surface roughness. DETAILED DESCRIPTION

[0027] The present invention is further illustrated by specific examples below. These examples are exemplary and are intended to illustrate the problem and explain the present invention, but are not intended to be limiting.

[0028] Part 1: Post-treatment of TPA parts by wet coloring using selective laser sintering (SLS).

[0029] Preparation of dye liquor: prepare the materials required for preparing the dye liquor, add one or more dyes and leveling agents in a certain proportion to a certain amount of water and stir them fully at room temperature to make the dyes evenly dispersed to obtain the desired dye liquor. The dyes are one or more of direct dyes, insoluble azo dyes, vat dyes, sulfur dyes, and acid dyes. Specifically in the following embodiments, dyes, leveling agents and water are prepared in a mass ratio of (0.01-0.1):(0.01-0.05):(10-60) and then placed in a container and stirred to obtain a dye liquor.

[0030] Preparation of TPA parts: The raw material is TPA powder, and the processing technology is selective laser sintering. The surface of the TPA parts is rough and contains micron-level pores. This type of parts is suitable for the field of elastomer materials such as sole cushioning, seats, and linings.

[0031] Wet coloring of TPA parts: Place the dyeing liquid and the TPA parts to be colored in an ultrasonic machine / low noise oscillator / infrared dyeing machine, set the heating ultrasonic machine / low noise oscillator / infrared dyeing machine to 50-100℃, slowly increase the temperature at 5℃ / min, and after reaching the set temperature, keep it at 50-100℃ for 15-120min. The dyeing material is directly introduced into the surface and microporous structure of the TPA parts through mechanical action, and the coloring process is completed through physical adsorption. The color difference data of the obtained dyeing sample is analyzed by a colorimeter, and the subsequent color fixing step is carried out after the color quality is qualified. If the color does not meet the requirements, it can be adjusted by adding dyes, extending the dyeing time and other process methods. The colored TPA parts are taken out of the ultrasonic machine / low noise oscillator / infrared dyeing machine with a clip, cooled to room temperature, and then rinsed with clean water after cooling to room temperature. The surface of the colored TPA is washed off with residual dye and placed at room temperature for more than 4 hours for drying.

[0032] Color fixation treatment of TPA parts: The colored TPA parts are immersed in a mixed solution of organic solvents, and the organic solvents dissolve the surface of the TPA parts, so that the surface pores are closed and smoothed, and the dyeing materials in the pores are further fixed. Then, the solvent-treated TPA parts are fully dried in a blast dryer to remove the organic solvent, and the strengthened TPA parts are obtained. The organic solvent mixture is two or more of ethanol, acetone, chloroform, dichloromethane, hexafluoroisopropanol, dimethylacetamide (DMA), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO). Specifically in the following embodiments, the organic solvent DMA and ethanol are uniformly mixed at a ratio of (1-20):1 at room temperature to obtain a mixed solution for color fixation; the colored TPA article is completely immersed in the mixed solution for 15-300 seconds, and the surface of the article is slightly dissolved by the dissolving effect of the organic solvent to close the surface pores of the TPA article, thereby completing the color fixation process; the TPA article treated with the organic solvent is placed in a blast dryer, the temperature is adjusted to 50°C, the time is 48 hours, it is fully dried to remove the residual solvent, and it is taken out and naturally cooled to room temperature to obtain a TPA article enhanced by post-coloring treatment.

[0033] Example 1

[0034] Direct dye (direct yellow R) is placed in a container at a ratio of 0.01:0.01:20 (dye: leveling agent (PW, JX-5): water) and stirred evenly (the mass of the product is counted as 1). The TPA strips and round blocks to be colored (GB / T528-2009, IOS868:2003GB / T2411-2003) are placed in the dye solution. The container containing the dye solution and the TPA product is placed in an oven, and the oven is heated to 80°C. It is heated at 80°C for 20 minutes. After the heating is completed, the container is taken out, and the heated TPA product is taken out of the container with tweezers. After cooling to room temperature, the colored TPA surface is rinsed with clean water to wash off the residual dye solution, and it is placed at room temperature for more than 4 hours for drying. The organic solvent DMA and ethanol are mixed evenly at a ratio of 5:1 at room temperature to obtain a mixed solution for color fixation; the colored TPA product is immersed in the DMA solution for 30 seconds.

[0035] Direct dye (direct red 4BE) is placed in a container with a ratio of 0.04:0.02:20 (dye: leveling agent (PW, JX-5): water) and stirred evenly (the mass of the product is counted as 1). The dye solution and the TPA specimens and blocks to be colored (GB / T528-2009, IOS 868:2003GB / T 2411-2003) are placed in an ultrasonic machine for ultrasonication. The ultrasonic machine is heated to 30°C and heated at 30°C for 30 minutes. The colored TPA product is taken out of the ultrasonic machine with tweezers, cooled to room temperature, and the colored TPA surface is rinsed with clean water to wash off the residual dye solution. It is placed at room temperature for more than 4 hours for drying. The organic solvent DMA and ethanol are mixed evenly at a ratio of 5:1 at room temperature to obtain a mixed solution for color fixation; the colored TPA product is immersed in the DMA solution for 30 seconds.

[0036] Direct dye (direct black GB) is placed in a container at a ratio of 0.06:0.03:20 (dye: leveling agent (PW, JX-5): water) and stirred evenly (the mass of the product is counted as 1). The dye solution and the TPA specimens and blocks to be colored (GB / T528-2009, IOS 868:2003GB / T 2411-2003) are placed in an ultrasonic machine for ultrasonication. The ultrasonic machine is heated to 95°C and heated at 95°C for 40 minutes. The colored TPA product is taken out of the ultrasonic machine with tweezers. After cooling to room temperature, the colored TPA surface is rinsed with clean water to wash off the residual dye solution, and the product is placed at room temperature for more than 4 hours for drying.

[0037] According to GB / T 10610, IOS105-B02, EN ISO 15701, SATRA CM44 standard test samples (IOS868: 2003 GB / T 2411-2003) direct yellow R, direct red 4BE, direct black GB roughness, color fastness, the results are shown in the following table.

[0038] Table 1

[0039]

[0040] According to GB / T 528-2009 and IOS868:2003 / GB / T 2411-2008 standards, the tensile strength, elongation at break and physical and mechanical properties of the GB / T528-2009 sample were tested. The results are shown in the following table.

[0041] Table 2

[0042]

[0043]

[0044] Example 2

[0045] Direct dye (direct yellow R) is placed in a container at a ratio of 0.01:0.01:20 (dye: leveling agent (PW, JX-5): water) and stirred evenly (the mass of the product is counted as 1). The dye solution and the TPA specimens and blocks to be colored (GB / T528-2009, IOS 868:2003GB / T 2411-2003) are placed in an ultrasonic machine for ultrasonication. The ultrasonic machine is heated to 80°C and heated at 80°C for 20 minutes. The colored TPA product is taken out of the ultrasonic machine with tweezers, cooled to room temperature, and the colored TPA surface is rinsed with clean water to wash off the residual dye solution. It is placed at room temperature for more than 4 hours for drying. The organic solvent DMA and ethanol are mixed evenly at a ratio of 5:1 at room temperature to obtain a mixed solution for color fixation; the colored TPA product is immersed in the DMA solution for 30 seconds.

[0046] Direct dye (direct red 4BE) is placed in a container at a ratio of 0.04:0.02:20 (dye: leveling agent (PW, JX-5): water) and stirred evenly (the mass of the product is counted as 1). The dye solution and the TPA specimens and blocks to be colored (GB / T528-2009, IOS 868:2003GB / T 2411-2003) are placed in a low-noise oscillator, and the low-noise oscillator is heated to 90°C and heated at 90°C for 30 minutes. The colored TPA product is taken out of the low-noise oscillator with tweezers, cooled to room temperature, and the colored TPA surface is rinsed with clean water to wash off the residual dye solution. It is placed at room temperature for more than 4 hours for drying. The organic solvent DMA and ethanol are mixed evenly at a ratio of 5:1 at room temperature to obtain a mixed solution for color fixation; the colored TPA product is immersed in the DMA solution for 30 seconds.

[0047] Direct dye (direct black GB) is placed in a container at a ratio of 0.06:0.03:20 (dye: leveling agent (PW, JX-5): water) and stirred evenly (the mass of the product is counted as 1). The dye solution and the TPA specimens and round blocks to be colored (GB / T528-2009, IOS 868:2003GB / T 2411-2003) are placed in an infrared dyeing machine in an ultrasonic machine, and the infrared dyeing machine is heated to 95°C and heated at 95°C for 40 minutes. The colored TPA product is taken out of the ultrasonic machine with tweezers, cooled to room temperature, and the colored TPA surface is rinsed with clean water to wash off the residual dye solution. It is placed at room temperature for more than 4 hours for drying. The organic solvent DMA and ethanol are mixed evenly at a ratio of 5:1 at room temperature to obtain a mixed solution for color fixation; the colored TPA product is immersed in the DMA solution for 30 seconds.

[0048] For fixing the natural color sample, mix the organic solvent DMA and ethanol in a ratio of 5:1 at room temperature, and immerse the TPA sample strips and round blocks (GB / T528-2009, IOS 868:2003GB / T2411-2003) in the mixed solution for 60 seconds.

[0049] According to GB / T 10610, IOS105-B02, EN ISO 15701, SATRA CM44 standard test samples (IOS868: 2003 GB / T 2411-2003) direct yellow R, direct red 4BE, direct black GB, and natural color roughness and color fastness are shown in the following table.

[0050] Table 3

[0051]

[0052] According to GB / T 528-2009 and IOS868:2003 / GB / T 2411-2008 standards, the tensile strength, elongation at break and physical and mechanical properties of the GB / T528-2009 sample were tested. The results are shown in the following table.

[0053] Table 4

[0054]

[0055] In Example 1, the direct yellow R case is used as a comparison. No mechanical action is added during the experiment. The roughness of the dyed product is improved from 8.6 μm to 3.2 μm, a decrease of 63%. The tensile strength, elongation at break, and Shore hardness are increased by 50%, 46%, and 9%, respectively. However, the dyeing rate is only 10%, which is low. Moreover, color spots appear on the dyed product. The color fastness is poor, all of which are lower than the conventional fabric and plastic standards (3-4 / 4 grade). In summary, the dyeing rate of the direct yellow R dyed product without mechanical action during the experiment is low, and the color blocks on the product tend to be obvious. For the direct scarlet 4BE case, the experimental process uses low-temperature dyeing (lower than the range of 50-100°C required by the present invention). The roughness of the dyed parts is improved from 8.6μm to 3.0μm, a decrease of 65%. The tensile strength, elongation at break, and Shore hardness are increased by 55%, 50%, and 12%, respectively. However, the dyeing rate is only 20%, which is low. Color spots appear on the dyed parts, and the color fastness is poor, all of which are lower than the conventional fabric and plastic standards (3-4 / 4 grade). In summary, the direct scarlet 4BE dyed parts using low-temperature dyeing (lower than the range of 50-100°C required by the present invention) in the experimental process have a low dyeing rate, and the color blocks on the parts tend to be obvious. In the case of direct black GB, the color fixation treatment was not implemented during the experiment. The roughness of the dyed parts deteriorated, from 8.6μm to 9.6μm, an increase of 12%. The dyeing rate was only 22%, which was low. The color fastness was poor, all of which were lower than the conventional fabric and plastic standards (3-4 / 4 grade). The tensile strength, elongation at break, and Shore hardness decreased by 14%, 9%, and 4%, respectively. In summary, the roughness of the direct black GB dyed parts without color fixation treatment during the experiment deteriorated, and the surface roughness tended to be obvious.

[0056] In Example 2, direct yellow R, direct red 4BE, and direct black GB are all dyed and fixed by high temperature mechanical action, and the roughness, dyeing rate, color spots, color fastness, tensile strength, elongation at break, and Shore hardness of the dyed parts are significantly improved. After direct yellow R dyeing, the roughness of the parts is improved, from 8.6μm to 2.2μm, a decrease of 74%, the tensile strength, elongation at break, and Shore hardness are increased by 41%, 42%, and 8%, respectively, the dyeing rate is 82%, no color spots appear on the parts after dyeing, and the color fastness is good, all of which are higher than the conventional fabric and plastic standards (3-4 / 4 grade). After direct red 4BE dyeing, the roughness of the parts improved, from 8.6μm to 2.1μm, a decrease of 76%, the tensile strength, elongation at break, and Shore hardness increased by 48%, 46%, and 9% respectively, the dyeing rate was 86%, no spots appeared on the parts after dyeing, and the color fastness was good, all of which were higher than the conventional fabric and plastic standards (3-4 / 4 grade). After direct black GB dyeing, the roughness of the parts improved, from 8.6μm to 2.0μm, a decrease of 77%, the tensile strength, elongation at break, and Shore hardness increased by 55%, 58%, and 12% respectively, the dyeing rate was 90%, no spots appeared on the parts after dyeing, and the color fastness was good, all of which were higher than the conventional fabric and plastic standards (3-4 / 4 grade).

[0057] Based on the analysis and comparison of the experimental process and experimental results of Example 1 and Example 2, the TPA wet dyeing experiment requires the use of appropriate mechanical action and a dyeing temperature of 50-100°C, so that the dye can be evenly and thoroughly penetrated and combined in the printed parts to achieve a high dye uptake rate of the dye. Then, the parts are fixed with a mixed solvent, and the surface density of the parts is improved by slightly dissolving the surface of the parts, so that the TPA printed parts have good physical and mechanical properties, surface quality and aesthetics.

[0058] Part 2, wet coloring post-treatment of PA12 parts by multi-jet melt forming (MJF).

[0059] Preparation of dye liquor: prepare the materials required for preparing the dye liquor, add one or more dyes and leveling agents in a certain proportion to a certain amount of water and stir them fully at room temperature to make the dyes evenly dispersed to obtain the desired dye liquor. The dye is one or more of direct dyes, insoluble azo dyes, vat dyes, sulfur dyes, and acid dyes. Specifically in the following embodiments, dyes, leveling agents and water are prepared in a mass ratio of (0.01-0.1):(0.01-0.05):(10-60) and then placed in a container and stirred to obtain a dye liquor.

[0060] Preparation of PA12 parts: The raw material is PA12 powder, and the processing technology is selective laser sintering. The surface of the PA12 parts is rough and contains micron-level pores. This type of parts is suitable for automotive parts and plastic parts.

[0061] Wet coloring of PA12 parts: Place the dyeing liquid and the PA12 parts to be colored in an ultrasonic machine / low noise oscillator / infrared dyeing machine, set the heating ultrasonic machine / low noise oscillator / infrared dyeing machine to 80-95℃, slowly increase the temperature at 5℃ / min, and heat it at 50-100℃ for 15-120min after reaching the set temperature. The dyeing material is directly introduced into the surface and microporous structure of the PA12 parts through mechanical action, and the coloring process is completed through physical adsorption. The color difference data of the obtained dyeing liquid is analyzed by a colorimeter, and the subsequent coloring steps are carried out after the color quality is qualified. If the color does not meet the requirements, it can be adjusted by adding dyes, extending the dyeing time and other process methods. The colored PA12 parts are taken out of the ultrasonic machine / low noise oscillator / infrared dyeing machine with a clip, cooled to room temperature, and then rinsed with clean water after cooling to room temperature. The surface of the colored PA12 is washed off with residual dyeing liquid, and placed at room temperature for more than 4 hours for drying.

[0062] Color fixation treatment of PA12 parts: The colored PA12 parts are immersed in a mixed solution of organic solvents, and the organic solvents dissolve the surface of the PA12 parts, so that the surface pores are closed and smoothed, and the dyeing materials in the pores are further fixed. Then, the solvent-treated PA12 parts are fully dried in a blower dryer to remove the organic solvent to obtain colored PA12 parts. The organic solvent mixture is two or more of N,N-dimethylformamide (DMF), ethanol, 1,4-dioxane, tetrahydrofuran, acetone, dichloromethane, chloroform, toluene, hexafluoroisopropanol, and n-hexane. Specifically in the following embodiments, the organic solvent DMF and ethanol are uniformly mixed at a ratio of (1-20):1 at room temperature to obtain a mixed solution for color fixation; the colored PA12 workpiece is completely immersed in the mixed solution for 15-180 seconds, and the surface of the workpiece is slightly dissolved by the dissolving action of the organic solvent to close the surface pores of the PA12 workpiece, thereby completing the color fixation process; the PA12 workpiece treated with the organic solvent is placed in a blower dryer, the temperature is adjusted to 80°C, the time is 48 hours, it is fully dried to remove the residual solvent, and it is taken out and naturally cooled to room temperature to obtain a PA12 workpiece that has been strengthened by post-coloring treatment.

[0063] Example 3

[0064] Acid dye (Acid Yellow 17) is placed in a container with a ratio of 0.01:0.01:20 (dye: leveling agent (PW, JX-5): water) and stirred evenly (the mass of the product is counted as 1). PA12 strips and round blocks (GB / T528-2009, IOS868:2003GB / T2411-2003) to be colored are placed in the dye solution. The container containing the dye solution and PA12 products is placed in an oven and heated to 80°C. Heat it at 80°C for 20 minutes. After the heating is completed, take out the container, take out the heated PA12 workpiece from the container with tweezers, cool it to room temperature, rinse the colored PA12 surface with clean water, wash off the residual dye, and place it at room temperature for more than 4 hours for drying. Mix the organic solvent DMF and ethanol at a ratio of 5:1 at room temperature to obtain a mixed solution for color fixation; immerse the colored PA12 workpiece in the DMF solution for 30 seconds.

[0065] Acid dye (acid red 18) is placed in a container with a ratio of 0.04:0.02:20 (dye: leveling agent (PW, JX-5): water) and stirred evenly (the mass of the workpiece is counted as 1). The dye solution and the PA12 specimens and round blocks to be colored (GB / T528-2009, IOS 868:2003GB / T 2411-2003) are placed in an ultrasonic machine for ultrasonication, and the ultrasonic machine is heated to 30°C and heated at 30°C for 30 minutes. The colored PA12 workpiece is taken out of the ultrasonic machine with tweezers, cooled to room temperature, and the colored TPA12 surface is rinsed with clean water to wash off the residual dye solution. It is placed at room temperature for more than 4 hours for drying. The organic solvent DMF and ethanol are mixed evenly at a ratio of 5:1 at room temperature to obtain a mixed solution for color fixation; the colored PA12 workpiece is immersed in the DMF solution for 30 seconds.

[0066] Acid dye (acid black LD) is placed in a container with a ratio of 0.06:0.03:20 (dye: leveling agent (PW, JX-5): water) and stirred evenly (the mass of the product is counted as 1). The dye solution and the PA12 specimens and blocks to be colored (GB / T528-2009, IOS 868:2003GB / T 2411-2003) are placed in an ultrasonic machine for ultrasonication. The ultrasonic machine is heated to 95°C and heated at 95°C for 40 minutes. The colored PA12 product is taken out of the ultrasonic machine with tweezers. After cooling to room temperature, the colored PA12 surface is rinsed with clean water to wash off the residual dye solution, and the product is placed at room temperature for more than 4 hours for drying.

[0067] According to GB / T 10610, IOS105-B02, EN ISO 15701, SATRA CM44 standard test samples (IOS868: 2003 GB / T 2411-2003) Acid Yellow 17, Acid Red 18, Acid Black LD were tested for roughness and color fastness. The results are shown in the following table.

[0068] Table 5

[0069]

[0070] According to GB / T 528-2009 and IOS868:2003 / GB / T 2411-2008 standards, the tensile strength, elongation at break and physical and mechanical properties of the GB / T528-2009 sample were tested. The results are shown in the following table.

[0071] Table 6

[0072] project Print Acid Yellow 17 Acid Red 18 Acid Black LD Tensile Strength 27.88MPa 28.32MPa 29.17MPa 27.50MPa Elongation at break 610.47％ 668.27％ 699.35％ 601.13％ Shore Hardness 80D 78D 76D 77D

[0073] Example 4

[0074] Acid dye (acid yellow 17) is placed in a container with a ratio of 0.01:0.01:20 (dye: leveling agent (PW, JX-5): water) and stirred evenly (the mass of the product is counted as 1). The dye solution and the PA12 specimens and round blocks to be colored (GB / T528-2009, IOS 868:2003GB / T 2411-2003) are placed in an ultrasonic machine for ultrasonication, and the ultrasonic machine is heated to 80°C and heated at 80°C for 20 minutes. The colored PA12 product is taken out of the ultrasonic machine with tweezers, cooled to room temperature, and the colored PA12 surface is rinsed with clean water to wash off the residual dye solution. It is placed at room temperature for more than 4 hours for drying. The organic solvent DMF and ethanol are mixed evenly at a ratio of 5:1 at room temperature to obtain a mixed solution for color fixation; the colored TPA product is immersed in the DMF solution for 30 seconds.

[0075] Acid dye (acid red 18) is placed in a container at a ratio of 0.04:0.02:20 (dye: leveling agent (PW, JX-5): water) and stirred evenly (the mass of the product is counted as 1). The dye solution and the PA12 specimens and round blocks to be colored (GB / T528-2009, IOS 868:2003GB / T 2411-2003) are placed in a low-noise oscillator, and the low-noise oscillator is heated to 90°C and heated at 90°C for 30 minutes. The colored PA12 product is taken out of the low-noise oscillator with tweezers, cooled to room temperature, and the colored PA12 surface is rinsed with clean water to wash off the residual dye solution, and placed at room temperature for more than 4 hours for drying. The organic solvent DMF and ethanol are mixed evenly at a ratio of 5:1 at room temperature to obtain a mixed solution for color fixation; the colored PA12 product is immersed in the DMF solution for 30 seconds.

[0076] Acid dye (acid black LD) is placed in a container with a ratio of 0.06:0.03:20 (dye: leveling agent (PW, JX-5): water) and stirred evenly (the mass of the workpiece is counted as 1). The dye solution and the PA12 specimens and round blocks to be colored (GB / T528-2009, IOS 868:2003GB / T 2411-2003) are placed in an infrared dyeing machine in an ultrasonic machine, and the infrared dyeing machine is heated to 95°C and heated at 95°C for 40 minutes. The colored PA12 workpiece is taken out of the ultrasonic machine with tweezers, cooled to room temperature, and the colored PA12 surface is rinsed with clean water to wash off the residual dye solution. It is placed at room temperature for more than 4 hours for drying. The organic solvent DMF and ethanol are mixed evenly at a ratio of 5:1 at room temperature to obtain a mixed solution for color fixation; the colored PA12 workpiece is immersed in the DMF solution for 30 seconds.

[0077] For fixing the natural color sample, mix the organic solvent DMF and ethanol in a ratio of 5:1 at room temperature, and immerse the PA12 sample strips and round blocks (GB / T528-2009, IOS 868:2003GB / T2411-2003) in the mixed solution for 60 seconds.

[0078] According to GB / T 10610, IOS105-B02, EN ISO 15701, SATRA CM44 standard test samples (IOS868: 2003GB / T 2411-2003) Acid Yellow 17, Acid Red 18, Acid Black LD, and natural color roughness and abrasion fastness are tested. The results are shown in the following table.

[0079] Table 7

[0080]

[0081]

[0082] According to GB / T 528-2009 standard, the tensile strength and elongation at break of the test sample GB / T528-2009 are shown in the following table.

[0083] Table 8

[0084] project Print True Color Acid Yellow 17 Acid Red 18 Acid Black LD Tensile Strength 27.88Mpa 29.12Mpa 30.53Mpa 31.47Mpa 33.05Mpa Elongation at break 610.47％ 695.33％ 735.28％ 757.30％ 772.20％ Shore Hardness 80D 78D 76D 76D 77D

[0085] In Example 3, the Acid Yellow 17 was used to compare the printed parts. No mechanical action was added during the experiment. The roughness of the dyed parts was improved from 9.38 μm to 3.3 μm, a decrease of 65%. The tensile strength, elongation at break, and Shore hardness were increased by 2%, 9%, and -3%, respectively. However, the dyeing rate was only 10%, which was low. Moreover, color spots appeared on the dyed parts. The color fastness was poor, all of which were lower than the conventional fabric and plastic standards (3-4 / 4 grade). In summary, the dyeing rate of the Acid Yellow 17 dyed parts without mechanical action during the experiment was low, and the color blocks on the parts tended to be obvious. Acid Red 18 contrast prints, the experimental process uses low temperature dyeing (lower than the required range of 50-100°C of the present invention), the roughness of the dyed parts is improved, from 9.38μm to 3.1μm, a decrease of 67%, tensile strength, elongation at break, and Shore hardness are increased by 5%, 15%, and -5%, respectively, but the dyeing rate is only 22%, the dyeing rate is low, and color spots appear on the dyed parts, and the color fastness is poor, all of which are lower than the conventional fabric and plastic standards (3-4 / 4 grade). In summary, the dyeing rate of the Acid Red 18 dyed parts using low temperature dyeing (lower than the required range of 50-100°C of the present invention) in the experimental process is low, and the color blocks on the parts tend to be obvious. Acid black 10LD contrast print, the experimental process did not implement the color fixation treatment, the roughness of the dyed parts deteriorated, from 9.38μm to 9.8μm, an increase of 4.5%, the dyeing rate was only 24%, the dyeing rate was low, the color fastness was poor, all lower than the conventional fabric, plastic standards (3-4 / 4 grade), tensile strength, elongation at break, Shore hardness decreased by 1.4%, 2%, 4% respectively. In summary, the roughness of the acid black 10LD dyed parts without color fixation treatment deteriorated, and the surface roughness tended to be obvious.

[0086] In Example 4, acid yellow 17, acid red 18, and acid black LD were all dyed and fixed by high-temperature mechanical action, and the roughness, dyeing rate, color spots, color fastness, tensile strength, elongation at break, and Shore hardness of the dyed parts were significantly improved. After dyeing with acid yellow 17, the roughness of the parts was improved, from 9.38 μm to 2.8 μm, a decrease of 70%, and the tensile strength, elongation at break, and Shore hardness were increased by 9.5%, 20%, and 5%, respectively, and the dyeing rate was 82%. No color spots appeared on the parts after dyeing, and the color fastness of each item was good, all of which were higher than the conventional fabric and plastic standards (3-4 / 4 grade). After dyeing with acid red 18, the roughness of the parts improved, from 9.38μm to 2.6μm, a decrease of 72%. The tensile strength, elongation at break, and Shore hardness increased by 12.9%, 24%, and 5%, respectively. The dyeing rate was 86%. No spots appeared on the parts after dyeing. The color fastness of each item was good, all of which were higher than the conventional fabric and plastic standards (3-4 / 4 grade). After dyeing with acid black 10LD, the roughness of the parts improved, from 9.38μm to 2.4μm, a decrease of 74%. The tensile strength, elongation at break, and Shore hardness increased by 18.5%, 26.5%, and 4%, respectively. The dyeing rate was 90%. No spots appeared on the parts after dyeing. The color fastness of each item was good, all of which were higher than the conventional fabric and plastic standards (3-4 / 4 grade).

[0087] Based on the analysis and comparison of the experimental process and experimental results of Example 3 and Example 4, the PA12 wet dyeing experiment requires the use of appropriate mechanical action and a dyeing temperature of 50-100°C, so that the dye can be evenly and thoroughly penetrated and combined in the printed parts, and a high dye uptake rate of the dye can be achieved. Then, the mixed solvent is used to fix the parts, and the surface density of the parts is improved by slightly dissolving the surface of the parts, so that the PA printed parts have good physical and mechanical properties, surface quality and aesthetics.

[0088] The above embodiments are exemplary, and their purpose is to illustrate the technical concept and features of the present invention so that people familiar with the technology in this field can understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A wet coloring post-processing method for 3D printed parts, characterized in that: The following steps are involved: a) Prepare dye solution; The dye liquor contains a dye, a leveling agent and water, the dye is evenly dispersed in the aqueous phase, and the leveling agent promotes stable dispersion of the dye in the aqueous phase; b) preparing a 3D printed part; the 3D printed part is a non-metallic polymer part having micropores on the surface; c) coloring of 3D printed parts; placing the 3D printed parts in the dye solution, heating, and promoting the dye material to penetrate into the micropores of the 3D printed parts through mechanical action, and then taking out the 3D printed parts and draining off excess dye solution; d) color fixation of 3D printed parts; using an organic solvent mixture to fix the parts obtained in step c), wherein the organic solvent mixture slightly dissolves and reshapes the surface of the parts to promote the closure of surface pores to fix the dyeing material; after color fixation, the residual organic solvent is removed to obtain a 3D printed part after wet coloring.

2. The wet coloring post-processing method for 3D printed parts according to claim 1, characterized in that: The material of the 3D printed part is selected from any one of hard plastics PA12, PA11, ABS, PEEK, PP and elastic plastics TPA, TPU.

3. The wet coloring post-processing method of a 3D printed part according to claim 2, wherein the 3D printed part is a powder bed fusion printed part.

4. The wet coloring post-processing method for 3D printed parts according to claim 1, characterized in that: In the dye solution, the mass ratio of the dye, the leveling agent and water is (0.01-0.1):(0.01-0.05):(10-60); the dye is one or more of direct dyes, insoluble azo dyes, vat dyes, sulfur dyes and acid dyes.

5. The wet coloring post-processing method for 3D printed parts according to claim 1, characterized in that: The 3D printed part prepared in step b) is a TPA part of selective laser sintering (SLS); the organic solvent mixture used for color fixation in step d) is two or more of ethanol, acetone, chloroform, dichloromethane, hexafluoroisopropanol, dimethylacetamide (DMA), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO).

6. The wet coloring post-processing method of a 3D printed product according to claim 5, characterized in that: In step b), the organic solvent DMA and ethanol are uniformly mixed at a ratio of (1-20):1 at room temperature to obtain a mixed solution for color fixation; the colored TPA workpiece is completely immersed in the mixed solution for 15-300 seconds, and then the organic solvent-treated TPA workpiece is dried by forced air at a temperature of 50° C. for 48 hours to obtain a 3D printed workpiece after wet coloring treatment.

7. The wet coloring post-processing method for 3D printed parts according to claim 1, characterized in that: The 3D printed part prepared in step b) is a PA12 part of multi-jet melt molding (MJF); the organic solvent mixture used for color fixation in step d) is two or more of N,N-dimethylformamide (DMF), ethanol, 1,4-dioxane, tetrahydrofuran, acetone, dichloromethane, chloroform, toluene, hexafluoroisopropanol, and n-hexane.

8. The wet coloring post-processing method for 3D printed parts according to claim 7, characterized in that: In step b), the organic solvent DMF and ethanol are uniformly mixed at a ratio of (1-20):1 at room temperature to obtain a mixed solution for color fixation, the colored PA12 workpiece is completely immersed in the mixed solution for 15-180 seconds, and then the PA12 workpiece treated with the organic solvent is dried at a temperature of 80° C. for 48 hours to obtain a 3D printed workpiece treated by wet coloring.

9. The wet coloring post-processing method of a 3D printed product according to any one of claims 1 to 8, characterized in that: In step c), the mechanical action source is selected from a heating ultrasonic machine, a low-noise oscillating machine, and an infrared dyeing machine.

10. The wet coloring post-processing method of a 3D printed product according to claim 9, characterized in that: In step c), the 3D printed part is placed in the dye solution, and the temperature is set to 80-95°C by a heating ultrasonic machine, a low-noise oscillator, or an infrared dyeing machine, and the temperature is slowly increased at 5°C / min. After reaching the set temperature, the temperature is kept for 15-120 minutes.

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