3D printing universal coloring post-processing method

Abstract

The present application relates to the technical field of 3D printing part post-processing, in particular to a general coloring post-processing method for 3D printing. The method comprises the following steps: (a) preparing an organic solvent mixed dyeing solution; (b) preparing a 3D printing part with a rough dyeing surface; (c) immersing the 3D printing part in the organic solvent mixed dyeing solution to promote coloring through physical and chemical effects; (d) using the organic solvent to slightly dissolve the surface of the 3D printing part to promote the closure of the surface micropores to fix the dye. The present application proposes a general coloring post-processing method with low cost and high efficiency, which has no requirements on the geometry of the part and is more suitable for high-molecular 3D printing parts with various complex structures. The method can not only improve the uneven coloring problem of fine structures, but also improve the surface finish, mechanical properties and aesthetic appearance of the product.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of 3D printing part post-processing, in particular to a 3D printing universal coloring post-processing method. BACKGROUND

[0002] 3D printing technology, also known as additive manufacturing (AM) technology, is a way of building three-dimensional entities by layering materials. With the rapid development of science and technology, 3D printing technology is continuously applied in printing parts. According to the types of raw materials, 3D printing parts can be divided into three categories: powder, wire (filament) material and resin.

[0003] Powder type printing parts are often printed by powder bed fusion technology, and the parts have rough surfaces and high porosity. Moreover, the powder itself does not have a colorful selection, and the printing process cannot meet the appearance color requirements. In the filament type printing part, the filament raw material with multi-color function is not only expensive, but also cannot realize the color function of specific positions through precise cooperation design. While the resin material can realize multi-color printing with its equipment, but the resin is expensive and not universal, only suitable for specific models and brands.

[0004] Therefore, in order to realize multi-color printing, traditional 3D printing parts often use paint spraying method for coloring post-processing. However, this method is only suitable for the production of 3D printing parts with planar structure or large pore structure with strong support. It has high requirements for the compatibility of materials and the matching of spraying process, and it is not good for processing fine pore structure and complex structure, which limits its application. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a 3D printing universal coloring post-processing method, which aims to provide a universal coloring post-processing method with low cost, high efficiency, no requirement for geometric shape, and high applicability to complex structure printing parts.

[0006] In order to achieve the above purpose, the present application provides a 3D printing universal coloring post-processing method, comprising the following steps:

[0007] (a) preparing an organic solvent mixed dye solution; the organic solvent mixed dye solution contains organic solvent, ethanol and dye;

[0008] (b) preparing a 3D printing part; the 3D printing part is a part made of high molecular material by 3D printing, and the surface has a rough dye adhesion surface;

[0009] (c) universal coloring of the 3D printing part; the printing part is immersed in the organic solvent mixed dye solution, and the organic solvent absorbs the dye into the micro-pore structure on the surface of the printing part to complete the coloring;

[0010] (d) 3D printed part fixing treatment; using organic solvent to slightly dissolve the surface of 3D printed part to promote the closure of surface micropores to fix the dye; removing the residual organic solvent after fixing, obtaining the 3D printed part after coloring and post-processing enhancement.

[0011] Further, the material of the 3D printed part is selected from any one of PLA, TPU of the filament material, PA11, PA12, ABS, PEEK, PP, TPA, TPU of the powder material, and EPU44, EPU46, epoxy resin, and various light-curing and thermoplastic resins of the resin material.

[0012] Further, the dye adhering surface micropores or layer lines, and support traces of the 3D printed part in step (b) are removed.

[0013] Further, the dye in step (a) is one or more of fluorescent dye, direct dye, vat dye, sulfur dye, acid dye, and reactive dye; the 3D printed part prepared in step (b) is a TPA printed part of selective laser sintering (SLS); and the organic solvent mixed solution used for fixing in step (d) is one or more of ethanol, acetone, chloroform, dichloromethane, hexafluoroisopropanol, dimethylacetamide (DMA), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO).

[0014] Further, in step (a), the organic solvent is mixed with ethanol at room temperature to obtain an organic solvent mixed solution for fixing at a ratio of (1-20):1, and the dye is mixed with the organic solvent mixed solution at a mass ratio of (1-10):(100-600) to obtain an organic solvent mixed dye solution; the TPA printed part is immersed in the organic solvent mixed dye solution for 30-300s, the organic solvent mixed solution slightly dissolves the surface of the part to fix the dye, and then the TPA printed part treated with the organic solvent is air dried at a temperature of 50℃ for 24h to obtain the TPA printed part after coloring and post-processing enhancement.

[0015] Further, the dye in step (a) is one or more of direct dye, insoluble azo dye, vat dye, sulfur dye, and acid dye; the 3D printed part prepared in step (b) is a PLA printed part of fused deposition (FDM); and the organic solvent mixed solution used for 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.

[0016] Further, in step (a), the organic solvent and ethanol are mixed in a ratio of (5-20):1 at room temperature to obtain an organic solvent mixed solution for dye fixation, and the dye and the organic solvent mixed solution are mixed in a mass ratio of (1-10):(100-500) to obtain an organic solvent mixed dye solution; the PLA printed part is placed in the organic solvent mixed dye solution and soaked for 60-300 s, the organic solvent mixed solution slightly dissolves the surface of the part to fix the dye, and then the PLA printed part treated with the organic solvent is air dried at a temperature of 50 DEG C for 24 h to obtain a PLA printed part treated with coloring and post-processing.

[0017] Further, in step (a), the dye is one or more of direct dye, acid dye and reactive dye; in step (b), the prepared 3D printed part is an EPU44 part of stereolithography (DLP); and in step (d), the organic solvent mixed solution used for dye fixation is two or more of methanol, ethanol, butanol, dimethylbenzene, benzene, ethyl acetate, acetone, dichloromethane, chloroform and hexafluoroisopropanol.

[0018] Further, in step (a), the organic solvent and ethanol are mixed in a ratio of (1-20):1 at room temperature to obtain an organic solvent mixed solution for dye fixation, and the dye and the organic solvent mixed solution are mixed in a mass ratio of (1-10):(100-500) to obtain an organic solvent mixed dye solution; the EPU44 printed part is placed in the organic solvent mixed dye solution and soaked for 60-300 s, and the dye is colored by adsorption and wrapping on the surface of the part, and then the EPU44 printed part treated with the organic solvent is air dried at a temperature of 50 DEG C for 48 h to obtain an EPU44 printed part treated with coloring and post-processing.

[0019] Further, in step (a), the organic solvent and ethanol are mixed in a ratio of 5:1 at room temperature to prepare an organic solvent mixed solution.

[0020] Beneficial effects

[0021] The 3D printing universal coloring post-processing method is used for coloring post-processing of various polymer printed parts, and the coloring process is simple, convenient and efficient, and the cost is saved compared to the traditional post-processing method, which is suitable for most 3D printed parts, the mixed solution of the organic solvent and the dye can be recycled, the amount of the organic solvent used is small and the environmental impact is small, there is no requirement for the shape of the part, the applicability of the 3D printed part with complex structure is higher, the coloring of the planar structure and the complex structure is facilitated, the color fastness is good, the mechanical properties are significantly improved, and the surface roughness is improved. DETAILED DESCRIPTION

[0022] Embodiments of the present application are described in detail below, the following embodiments are exemplary, and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0023] First part, the general coloring post-processing of TPA printed parts formed by selective laser sintering technology (SLS).

[0024] Preparation of dye solution: prepare the materials needed to prepare the dye solution, mix the organic solvent with ethanol at room temperature in a ratio of (1-20):1 to obtain an organic solvent mixed solution for solidification; after the dye and the organic solvent mixed solution are prepared in a mass ratio of (1-10):(100-600), they are placed in a container and stirred evenly to obtain the required organic solvent mixed dye solution. Among them, the dye is one or several of fluorescent dye, direct dye, vat dye, sulfur dye, acid dye and reactive dye.

[0025] Preparation of TPA printed parts: the surface of the TPA printed parts is rough and contains micron-sized pores, the raw material is TPA powder, and the processing technology is selective laser sintering process; such parts can be used in the field of elastic materials such as shoe sole cushion, seat, and liner.

[0026] General coloring of TPA printed parts: place the TPA printed parts in the organic solvent mixed dye solution and soak for 30-300 seconds. The dye molecules are introduced into the surface and microporous structure of the TPA printed parts by solvent penetration, and the coloring process is completed by physical adsorption and weak chemical bond action.

[0027] Fixing treatment of TPA printed parts: the colored organic solvent mixed solution is used to fix the TPA printed parts, the organic solvent dissolves the surface of the TPA printed parts, the surface pores are closed and smoothed, and the dyed material in the pores is further fixed. Then put the TPA printed parts treated with solvent into the air drying machine, adjust the temperature to 50℃, and dry for 24 hours. After removing the residual solvent, take out and cool to room temperature naturally to obtain the TPA printed parts with enhanced coloring post-processing. Among them, the organic solvent mixed solution is one or several of ethanol, acetone, chloroform, dichloromethane, hexafluoroisopropyl alcohol, dimethylacetamide (DMA), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO).

[0028] Example 1

[0029] The organic solvent DMA and ethanol are mixed uniformly at a ratio of 5:1 at room temperature to obtain a mixed solution. Direct dye (direct yellow R) is placed in a container at a ratio of 1:100 (dye:mixed solution) and stirred uniformly to obtain an organic solvent mixed dye solution (1 in terms of the mass of the product). The TPA sample bar and round block (GB / T 528-2009, IOS 868:2003 GB / T 2411-2003) to be colored are placed in the organic solvent mixed dye solution, immersed for 60 s, and then the TPA printed product is taken out of the container using a special fixture, drained at room temperature, and then placed in a forced air drying machine, with the temperature adjusted to 50°C and the time set to 24 h, to fully dry, remove residual solvent, and then naturally cooled to room temperature to obtain a TPA printed product that has been colored and post-processed to enhance the product.

[0030] The organic solvent DMA and ethanol are mixed uniformly at a ratio of 5:1 at room temperature to obtain a mixed solution. Direct dye (direct orange S) is placed in a container at a ratio of 2:150 (dye:mixed solution) and stirred uniformly to obtain an organic solvent mixed dye solution (1 in terms of the mass of the product). The TPA sample bar and round block (GB / T 528-2009, IOS 868:2003 GB / T 2411-2003) to be colored are placed in the organic solvent mixed dye solution, immersed for 60 s, and then the product is taken out of the container using a special fixture, drained at room temperature, and then placed in a forced air drying machine, with the temperature adjusted to 50°C and the time set to 24 h, to fully dry, remove residual solvent, and then naturally cooled to room temperature to obtain a TPA printed product that has been colored and post-processed to enhance the product.

[0031] The organic solvent DMA and ethanol are mixed uniformly at a ratio of 5:1 at room temperature to obtain a mixed solution. Direct dye (direct black EX) is placed in a container at a ratio of 3:400 (dye:mixed solution) and stirred uniformly to obtain an organic solvent mixed dye solution (1 in terms of the mass of the product). The TPA sample bar and round block (GB / T 528-2009, IOS 868:2003 GB / T 2411-2003) to be colored are placed in the organic solvent mixed dye solution, immersed for 60 s, and then the product is taken out of the container using a special fixture, drained at room temperature, and then placed in a forced air drying machine, with the temperature adjusted to 50°C and the time set to 24 h, to fully dry, remove residual solvent, and then naturally cooled to room temperature to obtain a TPA printed product that has been colored and post-processed to enhance the product.

[0032] The organic solvent DMA is mixed with ethanol at a ratio of 5:1 at room temperature to obtain a mixed solution. The green fluorescent dye BDP is placed in a container at a ratio of 2:100 (BDP:mixed solution) and stirred uniformly to obtain an organic solvent mixed dye solution (1 in terms of product mass). The TPA sample and round block (GB / T 528-2009, IOS 868:2003 GB / T 2411-2003) to be colored are placed in the organic solvent mixed dye solution and soaked for 60 s. The product is taken out of the container using a special fixture, drained at room temperature, and then placed in a forced air drying machine with a temperature of 50°C and a time of 24 h for sufficient drying to remove residual solvent. The TPA printed product is naturally cooled to room temperature to obtain a TPA printed product after coloring and processing enhancement.

[0033] The samples (IOS 868:2003 GB / T 2411-2003) are tested for fluorescent agent, acid light yellow 2G, acid red B, acid black 10B, and the roughness and color fastness of the base color group according to GB / T 10610, IOS 105-B02, EN ISO 15701, and SATRA CM44 standards. The results are shown in Table 1.

[0034] Table 1

[0035]

[0036] The tensile strength, elongation at break, and physical and mechanical properties of the sample GB / T 528-2009 are tested according to GB / T 528-2009, IOS 868:2003 / GB / T 2411-2008 standards. The results are shown in Table 2.

[0037] Table 2

[0038]

[0039] In Example 1, the printed part case is used as a comparison. After BDP, direct yellow R, direct orange S, and direct black EX dyeing, the roughness, color spots, color fastness, tensile strength, elongation at break, and shore hardness of the finished product are significantly improved. The roughness of the finished product after BDP dyeing is improved from 8.6 pm to 2.2 pm, with a decrease of 74%. The tensile strength, elongation at break, and shore hardness are increased by 52%, 53%, and 9%, respectively. No color spots appear on the finished product after dyeing, and the color fastness is good, all of which are higher than the conventional fabric and plastic standards (3-4 / 4 level). The roughness of the finished product after direct yellow R dyeing is improved from 8.6 pm to 2.3 pm, with a decrease of 73%. The tensile strength, elongation at break, and shore hardness are increased by 48%, 42%, and 7%, respectively. No color spots appear on the finished product after dyeing, and the color fastness is good, all of which are higher than the conventional fabric and plastic standards (3-4 / 4 level). The roughness of the finished product after direct orange S dyeing is improved from 8.6 pm to 2.1 pm, with a decrease of 76%. The tensile strength, elongation at break, and shore hardness are increased by 50%, 46%, and 8%, respectively. No color spots appear on the finished product after dyeing, and the color fastness is good, all of which are higher than the conventional fabric and plastic standards (3-4 / 4 level). The roughness of the finished product after direct black EX dyeing is improved from 8.6 pm to 2.0 pm, with a decrease of 77%. The tensile strength, elongation at break, and shore hardness are increased by 55%, 58%, and 9%, respectively. No color spots appear on the finished product after dyeing, and the color fastness is good, all of which are higher than the conventional fabric and plastic standards (3-4 / 4 level). Based on the experimental results, after dyeing and post-treatment of TPA printed parts, the dye penetrates and combines uniformly and completely in the printed parts, achieving high dye uptake and improving the uneven coloring problem of the fine structure. The surface finish of the product is improved, and the mechanical properties and aesthetics are also improved.

[0040] The second part is the general post-treatment of PLA printed parts by fused deposition technology (FDM).

[0041] Preparation of dyeing solution: Prepare the materials needed for preparing the dyeing solution, mix the organic solvent and ethanol at room temperature in a ratio of (5-20):1 to obtain an organic solvent mixed solution for solidification; mix the dye and organic solvent mixed solution in a mass ratio of (1-10):(100-500) and place it in a container for thorough stirring to obtain the required organic solvent mixed dyeing solution. The dye is one or more of direct dye, insoluble azo dye, vat dye, sulfur dye, and acid dye.

[0042] Preparation of PLA printed parts: The PLA printed parts have obvious layer lines on the rough surface. The raw material is PLA filament, and the processing technology is fused deposition modeling.

[0043] General coloring of PLA printed parts: PLA printed parts are placed in organic solvent mixed dyeing solution, and soaked for 60-300 seconds. The dye is adsorbed and wrapped onto the surface of the PLA printed parts by soaking, and the coloring is completed by physical adsorption.

[0044] Fixing treatment of PLA printed parts: after coloring, the printed parts are placed in an organic solvent mixed solution, the organic solvent slightly dissolves the surface of the PLA printed parts, the surface layer is smoothed, and the surface dye is further fixed. The PLA printed parts treated with the organic solvent are placed in a forced air drying machine, the temperature is adjusted to 50°C, and the time is 24 hours. After sufficient drying, the residual solvent is removed, and the PLA printed parts are naturally cooled to room temperature to obtain the PLA printed parts after coloring and treatment enhancement. The organic solvent mixed solution is two or more of N,N-dimethylformamide (DMF), ethanol, 1,4-dioxane, tetrahydrofuran, acetone, dichloromethane, chloroform, toluene, hexafluoroisopropanol, and n-hexane.

[0045] Example 2

[0046] The organic solvent DMF and ethanol are mixed uniformly at a ratio of 5:1 at room temperature to obtain a mixed solution. Acid dye (acid yellow 17) is placed in a container at a ratio of 1:100 (dye:mixed solution) and stirred uniformly to obtain an organic solvent mixed dyeing solution (1 in terms of the mass of the parts). The PLA bars and round blocks (GB / T 1040.2-2006, IOS 868:2003 GB / T 2411-2003) to be colored are placed in the organic solvent mixed dyeing solution and soaked for 210 seconds. The parts are taken out of the container with a special clamp, drained at room temperature, and then placed in a forced air drying machine. The temperature is adjusted to 50°C, and the time is 24 hours. After sufficient drying, the residual solvent is removed, and the PLA printed parts are naturally cooled to room temperature to obtain the PLA printed parts after coloring and treatment enhancement.

[0047] The organic solvent DMF and ethanol are mixed uniformly at a ratio of 5:1 at room temperature to obtain a mixed solution. Acid dye (acid yellow 17) is placed in a container at a ratio of 1:100 (dye:mixed solution) and stirred uniformly to obtain an organic solvent mixed dyeing solution (1 in terms of the mass of the parts). The PLA bars and round blocks (GB / T 1040.2-2006, IOS 868:2003 GB / T 2411-2003) to be colored are placed in the organic solvent mixed dyeing solution and soaked for 210 seconds. The parts are taken out of the container with a special clamp, drained at room temperature, and then placed in a forced air drying machine. The temperature is adjusted to 50°C, and the time is 24 hours. After sufficient drying, the residual solvent is removed, and the PLA printed parts are naturally cooled to room temperature to obtain the PLA printed parts after coloring and treatment enhancement.

[0048] The organic solvent DMF and ethanol are mixed uniformly at room temperature in a ratio of 5:1 to obtain a mixed solution. The acid dye (acid black LD) is placed in a container in a ratio of 3:200 (dye:mixed solution) and stirred uniformly to obtain an organic solvent mixed dye solution (1 by mass of the product). The PLA sample and round block (GB / T 1040.2-2006, IOS 868:2003 GB / T 2411-2003) to be colored are placed in the organic solvent mixed dye solution, immersed for 150 s, and then taken out of the container using a special fixture. The PLA printed product is then drained at room temperature, placed in a forced air drying machine, adjusted to a temperature of 50°C, and dried for 24 h to remove residual solvent. The PLA printed product is then naturally cooled to room temperature to obtain a PLA printed product that has been colored and post-processed to enhance the product.

[0049] The roughness and abrasion resistance of the samples (IOS 868:2003 GB / T 2411-2003) of the acid yellow 17, acid red 18, and acid black LD groups were tested according to the GB / T 10610, IOS 105-B02, EN ISO 15701, and SATRA CM44 standards, and the results are shown in Table 3.

[0050] Table 3

[0051]

[0052] The tensile strength and elongation at break of the samples were tested according to the ISO 527 standard GB / T 1040.2-2006, and the results are shown in Table 4.

[0053] Table 4

[0054]

[0055] In Example 2, the printed parts are used as a comparative example. The roughness, color fastness, tensile strength, elongation at break, and Shore hardness of the parts dyed with Acid Light Yellow 17, Acid Red 18, and Acid Black LD are significantly improved. The roughness of the part dyed with Acid Light Yellow 17 is improved from 9.38 pm to 2.7 pm, a decrease of 71%, the tensile strength, elongation at break, and Shore hardness are increased by 36%, 4%, and 4%, respectively, no color spots appear on the dyed part, and the color fastness is good, all of which are higher than the conventional and plastic standards (3-4 / 4 level). The roughness of the part dyed with Acid Red 18 is improved from 9.38 pm to 2.5 pm, a decrease of 73%, the tensile strength, elongation at break, and Shore hardness are increased by 35%, 5%, and 5%, respectively, no color spots appear on the dyed part, and the color fastness is good, all of which are higher than the conventional and plastic standards (3-4 / 4 level). The roughness of the part dyed with Acid Black LD is improved from 9.38 pm to 2.6 pm, a decrease of 72%, the tensile strength, elongation at break, and Shore hardness are increased by 32%, 6%, and 6%, respectively, no color spots appear on the dyed part, and the color fastness is good, all of which are higher than the conventional and plastic standards (3-4 / 4 level). Based on the experimental results, the dye penetrates and combines uniformly and completely in the printed part after dyeing and post-processing, achieving high dye uptake, improving the uneven color problem on the fine structure, and improving the surface finish, mechanical properties, and aesthetics of the product.

[0056] The third part is the general coloring post-processing of EPU44 printed parts by stereolithography (DLP).

[0057] Preparation of dyeing solution: Prepare the materials needed for preparing the dyeing solution, mix the organic solvent and ethanol at room temperature in a ratio of (1-20): 1 to obtain an organic solvent mixed solution for solidification; mix the reactive polyurethane dye and the organic solvent mixed solution in a mass ratio of (1-10):(100-500) and place them in a container for thorough stirring to obtain the required organic solvent mixed dyeing solution. The dye is one or more of direct dye, acid dye, and reactive dye.

[0058] Preparation of EPU44 printed parts: The raw material is EPU44, and the processing technology is a photosensitive resin selective curing process.

[0059] General coloring of EPU44 parts: Place the EPU44 printed parts to be colored in the mixed dyeing solution of organic solvents and immerse them for 60-300 seconds. The dye is adsorbed and wrapped onto the surface of the EPU44 printed parts through immersion, and the coloring is completed through physical adsorption.

[0060] The fixing treatment of the printed EPU44 parts: the colored printed parts are placed in an organic solvent mixed solution, the organic solvent slightly dissolves the surface of the printed EPU44 parts, smoothes the surface of the printed EPU44 parts, and further fixes the surface dye. The printed EPU44 parts treated with the organic solvent are placed in a forced air drying machine, the temperature is adjusted to 50°C, and the time is 48 hours. The printed EPU44 parts are fully dried, the residual solvent is removed, and the printed EPU44 parts are naturally cooled to room temperature. The colored and treated EPU44 parts are obtained. The organic solvent mixed solution is two or more of methanol, ethanol, butanol, dimethylbenzene, benzene, ethyl acetate, acetone, dichloromethane, chloroform, and hexafluoroisopropanol.

[0061] Example 3

[0062] The organic solvents chloroform and ethanol are mixed in a ratio of 5:1 at room temperature to obtain a mixed solution. The medium temperature active dye (C.I. 5# black) is placed in a container in a ratio of 1:100 (dye:mixed solution) and stirred uniformly to obtain an organic solvent mixed dye solution (1 in terms of part mass). The EPU44 samples and round blocks (GB / T 1040.2–2006, IOS 868:2003 GB / T 2411-2003) to be colored are placed in the organic solvent mixed dye solution and soaked for 210 seconds. The parts are taken out of the container with a special clamp, drained at room temperature, and then placed in a forced air drying machine. The temperature is adjusted to 50°C, and the time is 48 hours. The printed EPU44 parts are fully dried, the residual solvent is removed, and the printed EPU44 parts are naturally cooled to room temperature. The colored and treated EPU44 parts are obtained.

[0063] The organic solvents chloroform and ethanol are mixed in a ratio of 5:1 at room temperature to obtain a mixed solution. The medium temperature active dye (C.I. 21# turquoise blue) is placed in a container in a ratio of 2:150 (dye:mixed solution) and stirred uniformly to obtain an organic solvent mixed dye solution (1 in terms of part mass). The EPU44 samples and round blocks (GB / T 1040.2–2006, IOS 868:2003 GB / T 2411-2003) to be colored are placed in the organic solvent mixed dye solution and soaked for 150 seconds. The parts are taken out of the container with a special clamp, drained at room temperature, and then placed in a forced air drying machine. The temperature is adjusted to 50°C, and the time is 48 hours. The printed EPU44 parts are fully dried, the residual solvent is removed, and the printed EPU44 parts are naturally cooled to room temperature. The colored and treated EPU44 parts are obtained.

[0064] The organic solvent chloroform and ethanol are mixed uniformly at room temperature in a ratio of 5:1 to obtain a mixed solution. The medium-temperature active dye (C.I. 19# Brilliant Blue) is placed in a container in a ratio of 3:200 (dye:mixed solution) and stirred uniformly to obtain an organic solvent mixed dye solution (the mass of the product is 1). The EPU44 sample and the round block (GB / T 1040.2-2006, IOS 868:2003 GB / T 2411-2003) to be colored are placed in the organic solvent mixed dye solution and soaked for 90 s. The product is taken out of the container with a special clamp, drained at room temperature, and then placed in a drum dryer. The temperature is adjusted to 50°C, and the time is 48 h. The product is dried sufficiently to remove residual solvent, cooled to room temperature naturally, and obtained as the EPU44 printed product after coloring and processing enhancement.

[0065] The roughness and rubbing fastness of the samples of the medium-temperature active dye (C.I. 5# Black, C.I. 21 # Turquoise Blue, C.I. 19 # Brilliant Blue) are tested according to the GB / T 10610, IOS 105-B02, EN ISO 15701, SATRA CM44 standards (IOS 868:2003 GB / T 2411-2003). The results are shown in Table 5.

[0066] Table 5

[0067]

[0068] The tensile strength and elongation at break of the samples are tested according to the ISO 527 standard GB / T 1040.2-2006. The results are shown in Table 6.

[0069] Table 6

[0070] Item Printed piece C.I. 5# black C.I. 21# turquoise blue C.I. 19# brilliant blue Tensile strength 19 MPa 27 MPa 25 MPa 26 MPa Elongation at break 205% 254% 248% 250% Shore hardness 85A 81A 79A 80A

[0071] In Example 3, the printed parts are used as comparative cases. After dyeing with CI5# black, CI21# turquoise blue, and CI19# brilliant blue, the roughness, color spots, color fastness, tensile strength, elongation at break, and Shore hardness of the parts are significantly improved. After dyeing with CI5# black, the roughness of the parts is improved, decreasing from 5µm to 2.7µm, a decrease of 46%. The tensile strength, elongation at break, and Shore hardness are increased by 42%, 24%, and 5%, respectively. No color spots appear on the parts after dyeing. The color fastness of each part is good, all of which are higher than the standards for conventional fabrics and plastics (grade 3-4 / 4). After dyeing with CI21# turquoise blue, the roughness of the parts is improved, decreasing from 5µm to 2.5µm, a decrease of 50%. The tensile strength, elongation at break, and Shore hardness are respectively Improvements of 32%, 21%, and 7.1% were achieved. No color spots appeared on the dyed parts, and all color fastnesses were excellent, exceeding the standards for conventional fabrics and plastics (grades 3-4 / 4). After dyeing with CI19# Brilliant Blue, the roughness of the parts improved, decreasing from 5µm to 2.6µm, a 48% decrease. Tensile strength, elongation at break, and Shore hardness increased by 37%, 22%, and 6%, respectively. No color spots appeared on the dyed parts, and all color fastnesses were excellent, exceeding the standards for conventional fabrics and plastics (grades 3-4 / 4). These experimental results indicate that after dye post-treatment, EPU44-printed parts achieve uniform and thorough dye penetration and bonding within the printed parts, achieving a high dye uptake rate and improving the problem of uneven coloring of fine structures. This improves the product's surface finish while also enhancing mechanical properties and aesthetics.

Claims

1. A general coloring post-processing method for 3D printing, characterized by: The following steps are involved: (a) preparing an organic solvent mixed dye solution; the organic solvent mixed dye solution contains an organic solvent, ethanol and a dye; (b) preparing a 3D printed part; the 3D printed part is a part made of a polymer material by 3D printing, and has a rough dye attachment surface; (c) Universal coloring of 3D printed parts: the printed part is immersed in the organic solvent mixed dye solution, and the organic solvent absorbs the dye into the microporous structure on the surface of the printed part to complete the coloring; (d) Fixing the color of the 3D printed part; using an organic solvent to slightly dissolve the surface of the 3D printed part to promote the sealing of the surface micropores to fix the dye; after fixing the color, removing the residual organic solvent to obtain a 3D printed part that has been enhanced by post-coloring treatment; The dye in step (a) is one or more of a fluorescent dye, a direct dye, a vat dye, a sulfur dye, an acid dye, and a reactive dye; the 3D printed part prepared in step (b) is a TPA printed part produced by selective laser sintering (SLS); the organic solvent mixed solution used for color fixation in step (d) is one or more of ethanol, acetone, chloroform, dichloromethane, hexafluoroisopropanol, dimethylacetamide (DMA), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO); In step (a), an organic solvent and ethanol are mixed at a ratio of (1-20):1 at room temperature to obtain an organic solvent mixed solution for color fixation, and a dye and the organic solvent mixed solution are mixed at a mass ratio of (1-10):(100-600) to obtain an organic solvent mixed dye solution; a TPA printed part is placed in the organic solvent mixed dye solution and immersed for 30-300 seconds, and the organic solvent mixed solution slightly dissolves and fixes the dye on the surface of the part; then the organic solvent-treated TPA printed part is dried with air at a temperature of 50°C for 24 hours to obtain a TPA printed part enhanced by coloring post-treatment.

2. The 3D printing universal coloring post-processing method according to claim 1, characterized in that: The dye-attached surface of the 3D-printed part in step (b) has micropores or layer patterns and support removal marks.

3. The 3D printing general coloring post-processing method according to claim 1 or 2, characterized in that: In step (a), the organic solvent and ethanol are mixed at a ratio of 5:1 at room temperature to prepare an organic solvent mixed solution.

4. A general coloring post-processing method for 3D printing, characterized by: The following steps are involved: (a) preparing an organic solvent mixed dye solution; the organic solvent mixed dye solution contains an organic solvent, ethanol and a dye; (b) preparing a 3D printed part; the 3D printed part is a part made of a polymer material by 3D printing, and has a rough dye attachment surface; (c) Universal coloring of 3D printed parts: the printed part is immersed in the organic solvent mixed dye solution, and the organic solvent absorbs the dye into the microporous structure on the surface of the printed part to complete the coloring; (d) Fixing the color of the 3D printed part; using an organic solvent to slightly dissolve the surface of the 3D printed part to promote the sealing of the surface micropores to fix the dye; after fixing the color, removing the residual organic solvent to obtain a 3D printed part that has been enhanced by post-coloring treatment; The dye in step (a) is one or more of a direct dye, an insoluble azo dye, a vat dye, a sulfur dye, and an acid dye; the 3D printed part prepared in step (b) is a PLA printed part produced by a fused deposition model (FDM); the organic solvent mixed solution 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; In step (a), an organic solvent and ethanol are mixed at a ratio of (5-20):1 at room temperature to obtain an organic solvent mixed solution for color fixation, and a dye and the organic solvent mixed solution are mixed at a mass ratio of (1-10):(100-500) to obtain an organic solvent mixed dye solution; a PLA printed part is placed in the organic solvent mixed dye solution and immersed for 60-300 seconds, wherein the organic solvent mixed solution slightly dissolves and fixes the dye on the surface of the part; and the organic solvent-treated PLA printed part is then dried at a temperature of 50° C. for 24 hours to obtain a PLA printed part enhanced by post-coloring treatment.

5. The 3D printing universal coloring post-processing method according to claim 4, characterized in that: The dye-attached surface of the 3D-printed part in step (b) has micropores or layer patterns and support removal marks.

6. The 3D printing universal coloring post-processing method according to claim 4 or 5, characterized in that: In step (a), the organic solvent and ethanol are mixed at a ratio of 5:1 at room temperature to prepare an organic solvent mixed solution.

7. A general coloring post-processing method for 3D printing, characterized by: The following steps are involved: (a) preparing an organic solvent mixed dye solution; the organic solvent mixed dye solution contains an organic solvent, ethanol and a dye; (b) preparing a 3D printed part; the 3D printed part is a part made of a polymer material by 3D printing, and has a rough dye attachment surface; (c) Universal coloring of 3D printed parts: the printed part is immersed in the organic solvent mixed dye solution, and the organic solvent absorbs the dye into the microporous structure on the surface of the printed part to complete the coloring; (d) Fixing the color of the 3D printed part; using an organic solvent to slightly dissolve the surface of the 3D printed part to promote the sealing of the surface micropores to fix the dye; after fixing the color, removing the residual organic solvent to obtain a 3D printed part that has been enhanced by post-coloring treatment; The dye in step (a) is one or more of direct dyes, acid dyes, and reactive dyes; the 3D printed part prepared in step (b) is an EPU44 part of stereolithography (DLP); the organic solvent mixed solution used for color fixation in step (d) is two or more of methanol, ethanol, butanol, xylene, benzene, ethyl acetate, acetone, dichloromethane, chloroform, and hexafluoroisopropanol; In step (a), an organic solvent and ethanol are mixed at a ratio of (1-20):1 at room temperature to obtain an organic solvent mixed solution for color fixation, and a dye and the organic solvent mixed solution are mixed at a mass ratio of (1-10):(100-500) to obtain an organic solvent mixed dye solution; an EPU44 printed part is placed in the organic solvent mixed dye solution and immersed for 60-300 seconds, and the dye is adsorbed and wrapped on the surface of the part through immersion to complete coloring, and then the organic solvent-treated EPU44 printed part is blown and dried at a temperature of 50°C for 48 hours to obtain an EPU44 printed part enhanced by coloring post-treatment.

8. The 3D printing universal coloring post-processing method according to claim 7, characterized in that: The dye-attached surface of the 3D-printed part in step (b) has micropores or layer patterns and support removal marks.

9. The 3D printing universal coloring post-processing method according to claim 7 or 8, characterized in that: In step (a), the organic solvent and ethanol are mixed at a ratio of 5:1 at room temperature to prepare an organic solvent mixed solution.

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