General coloring post-processing method for 3D printing

Abstract

The invention relates to the technical field of post-processing of 3D printed parts, in particular to a universal 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 printed piece with a rough dye attachment surface on the surface; (c) dipping the 3D printed piece in an organic solvent mixed dye solution, and promoting coloring through physical and chemical effects; and (d) slightly dissolving the surface of the 3D printed piece by using an organic solvent to promote the sealing of surface micropores so as to fix the dye. The invention provides a general coloring post-processing method which is low in cost, high in efficiency, free of requirements on geometrical shapes of workpieces, higher in applicability to high-molecular 3D printed workpieces with various complex structures, and capable of improving the problem of uneven coloring of fine structures, improving the surface smoothness of products and improving the mechanical property and attractiveness.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing product post-processing, and in particular to a general 3D printing coloring post-processing method. Background Art

[0002] 3D printing technology, also known as Additive Manufacturing (AM) technology, is to build a three-dimensional entity by adding materials layer by layer. With the rapid development of science and technology, 3D printing technology is constantly being applied to printed parts. According to the type of raw materials, 3D printed parts can be divided into three categories: powder, wire (filament) and resin.

[0003] Powder-printed parts are often printed using powder bed fusion technology. The surface of the parts is rough and the porosity is high. The powder itself does not have a variety of options, and the printing process cannot meet the color requirements of the appearance. For filament-printed parts, filament raw materials with multi-color functions are not only expensive, but also cannot achieve the color function of a specific position through precise matching design. Resin materials can be used with their equipment to achieve colorful printing, but the resin is expensive and not universal, and is only suitable for specific models and brands.

[0004] Therefore, in order to achieve colorful printing, traditional 3D printed parts are often treated with spray painting for post-coloring. However, since this method is only suitable for the production of 3D printed parts with planar structures or large pore structures with strong support, it has high requirements on the compatibility of materials and the matching of spraying processes, and is poor at handling fine pore structures and complex structures, resulting in limited application. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a universal coloring post-processing method for 3D printing, aiming to provide a universal coloring post-processing method with low cost, high efficiency, no requirements on geometric shapes, and high applicability to printed parts with complex structures.

[0006] In order to achieve the above object, the present invention provides a general coloring post-processing method for 3D printing, comprising the following steps: (a) preparing an organic solvent mixed dye solution; the organic solvent mixed dye solution contains an organic solvent, ethanol and a dye; (b) preparing 3D printed parts; 3D printed parts are parts made of polymer materials by 3D printing, and have a rough dye attachment surface; (c) Universal coloring of 3D printed parts: the printed parts are immersed in a mixed dye solution of an organic solvent, and the organic solvent absorbs the dye into the microporous structure on the surface of the printed parts to complete the coloring; (d) Color fixation treatment of 3D printed parts: using organic solvents to slightly dissolve the surface of 3D printed parts to promote the closure of surface micropores to fix the dye; after color fixation, the residual organic solvent is removed to obtain a 3D printed part that has been enhanced by post-coloring treatment.

[0007] Furthermore, the material of the 3D printed parts is selected from PLA, TPU of the filament material category, PA11, PA12, ABS, PEEK, PP, TPA, TPU of the powder material category, and EPU44, EPU46, epoxy resin and any one of various photocurable and thermoplastic resins of the resin material category.

[0008] Furthermore, in step (b), the dye attachment surface of the 3D printed part has micropores or layer patterns and support removal marks.

[0009] Furthermore, the dye in step (a) is one or more of fluorescent dyes, direct dyes, vat dyes, sulfur dyes, acid dyes, and reactive dyes; the 3D printed parts prepared in step (b) are TPA printed parts of selective laser sintering (SLS); and 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).

[0010] Furthermore, 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 product is placed in the organic solvent mixed dye solution and immersed for 30-300 seconds, the organic solvent mixed solution slightly dissolves and fixes the dye on the surface of the product, and then the organic solvent-treated TPA printed product is dried by air at a temperature of 50°C for 24 hours to obtain a TPA printed product enhanced by post-coloring treatment.

[0011] Furthermore, the dye in step (a) is one or more of direct dyes, insoluble azo dyes, vat dyes, sulfur dyes, and acid dyes; the 3D printed parts prepared in step (b) are PLA printed parts by fused deposition modeling (FDM); and 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.

[0012] Furthermore, 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 product is placed in the organic solvent mixed dye solution and immersed for 60-300 seconds, the organic solvent mixed solution slightly dissolves and fixes the dye on the surface of the product, and then the organic solvent-treated PLA printed product is dried by blast drying at a temperature of 50°C for 24 hours to obtain a PLA printed product enhanced by post-coloring treatment.

[0013] Furthermore, the dye in step (a) is one or more of direct dyes, acid dyes, and reactive dyes; the 3D printed product prepared in step (b) is an EPU44 product of stereolithography (DLP); and 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.

[0014] Furthermore, 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 product 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 product through immersion to complete coloring, and then the organic solvent-treated EPU44 printed product is dried by blast drying at a temperature of 50°C for 48 hours to obtain an EPU44 printed product enhanced by post-coloring treatment.

[0015] Furthermore, in step (a), an organic solvent and ethanol are mixed at a ratio of 5:1 at room temperature to prepare an organic solvent mixed solution.

[0016] Beneficial Effects The present invention uses a universal 3D printing coloring post-processing method to perform coloring post-processing on various types of polymer printed parts. Compared with traditional post-processing methods, this method has a simple coloring process, convenient operation, high efficiency, and cost savings. It is suitable for most 3D printed parts. The mixed liquid of the organic solvent and the dye used can be recycled. During use, the amount of organic solvent used is small and the environmental impact factors are small. There is no requirement for the shape of the part. 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 improved mechanical properties, and improved surface roughness. DETAILED DESCRIPTION

[0017] Embodiments of the present invention are described in detail below. The embodiments described below are illustrative and intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0018] Part 1: General coloring post-processing of TPA printed parts using selective laser sintering (SLS).

[0019] Preparation of dye solution: prepare the materials required for dye solution preparation, mix the organic solvent and ethanol at a ratio of (1-20):1 at room temperature to obtain an organic solvent mixed solution for color fixation; prepare the dye and organic solvent mixed solution at a mass ratio of (1-10):(100-600) and place them in a container and stir them thoroughly to obtain the required organic solvent mixed dye solution. The dye is one or more of fluorescent dye, direct dye, vat dye, sulfur dye, acid dye, and reactive dye.

[0020] Preparation of TPA printed parts: The surface of TPA printed parts is rough and contains micron-level pores. The raw material is TPA powder and the processing technology is selective laser sintering. This type of parts can be used in the fields of elastomeric materials such as sole cushioning, seats, and protective linings.

[0021] Universal coloring of TPA printed parts: Place the TPA printed parts in a mixed dye solution of organic solvents and immerse them for 30 to 300 seconds. The dye molecules are introduced into the surface and microporous structure of the TPA printed parts through solvent penetration, and the coloring process is completed through physical adsorption and weak chemical bonds.

[0022] Color fixation treatment of TPA printed parts: The colored organic solvent mixed solution is used to fix the color of the TPA printed parts. The organic solvent dissolves the surface of the TPA printed parts, so that the surface pores are sealed and smoothed, and the dyeing materials in the pores are further fixed. Then, the solvent-treated TPA printed parts are placed in a blast dryer, the temperature is adjusted to 50°C, the time is 24 hours, and the parts are fully dried to remove the residual solvent, and then taken out and naturally cooled to room temperature to obtain TPA printed parts enhanced by coloring post-treatment. Among them, the organic solvent mixed solution is one or more of ethanol, acetone, chloroform, dichloromethane, hexafluoroisopropanol, dimethylacetamide (DMA), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO).

[0023] Example 1 The organic solvent DMA and ethanol are mixed at a ratio of 5:1 at room temperature to obtain a mixed solution. The direct dye (direct yellow R) is placed in a container at a ratio of 1:100 (dye: mixed solution) and stirred thoroughly to obtain an organic solvent mixed dye solution (the mass of the product is 1). The TPA specimens and round blocks to be colored (GB / T528-2009, IOS 868:2003 GB / T 2411-2003) are placed in the organic solvent mixed dye solution and immersed for 60 seconds. The TPA printed product is taken out of the container with a special fixture and drained at room temperature. The TPA printed product is then placed in a blast dryer, the temperature is adjusted to 50°C, the time is 24 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 printed product enhanced by coloring post-treatment.

[0024] The organic solvent DMA and ethanol are mixed 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 fully stirred to obtain an organic solvent mixed dye solution (the mass of the product is 1). The TPA specimens and round blocks (GB / T528-2009, IOS 868:2003 GB / T 2411-2003) to be colored are placed in the organic solvent mixed dye solution and immersed for 60 seconds. The product is taken out of the container with a special clamp and drained at room temperature. Subsequently, the TPA printed product is placed in a blast dryer, the temperature is adjusted to 50°C, the time is 24 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 printed product enhanced by coloring post-treatment.

[0025] The organic solvent DMA and ethanol are mixed 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 fully stirred to obtain an organic solvent mixed dye solution (the mass of the product is 1). The TPA specimens and round blocks to be colored (GB / T528-2009, IOS 868:2003GB / T 2411-2003) are placed in the organic solvent mixed dye solution and immersed for 60 seconds. The product is taken out of the container with a special clamp and drained at room temperature. Subsequently, the TPA printed product is placed in a blast dryer, the temperature is adjusted to 50°C, the time is 24 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 printed product enhanced by coloring post-treatment.

[0026] The organic solvent DMA and ethanol are mixed 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 thoroughly to obtain an organic solvent mixed dye solution (the mass of the product is 1). The TPA specimens and blocks to be colored (GB / T528-2009, IOS 868:2003 GB / T2411-2003) are placed in the organic solvent mixed dye solution and immersed for 60 seconds. The products are taken out of the container with a special clamp and drained at room temperature. Subsequently, the TPA printed products are placed in a blast dryer, the temperature is adjusted to 50°C, the time is 24 hours, and they are fully dried to remove the residual solvent. The products are taken out and naturally cooled to room temperature to obtain TPA printed products enhanced by coloring post-treatment.

[0027] According to GB / T 10610, IOS105-B02, EN ISO 15701 and SATRA CM44 standards, the roughness and color fastness of the samples (IOS868:2003GB / T 2411-2003) fluorescent agent, acid yellow 2G, acid red B, acid black 10B and natural color group were tested respectively. The results are shown in Table 1.

[0028] Table 1 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 Table 2.

[0029] Table 2 In Example 1, the printed case is used as a comparison. The roughness, color spots, color fastness, tensile strength, elongation at break, and Shore hardness of the parts after dyeing with BDP, direct yellow R, direct orange S, and direct black EX are significantly improved. The roughness of the parts after BDP dyeing is improved, decreasing from 8.6µm to 2.2µm, 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 parts after dyeing. The color fastness of each item is good, all of which are higher than the conventional fabric and plastic standards (3-4 / 4 grade); the roughness of the parts after direct yellow R dyeing is improved, decreasing from 8.6µm to 2.3µm, 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 parts after dyeing. The color fastness of each item is good, all of which are higher than the conventional fabric and plastic standards (3-4 / 4 grade); After the orange S dyeing, the roughness of the parts was improved, from 8.6µm to 2.1µm, a decrease of 76%. The tensile strength, elongation at break, and Shore hardness increased by 50%, 46%, and 8% respectively. No 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); the roughness of the parts was improved after the direct black EX dyeing, from 8.6µm to 2.0µm, a decrease of 77%. The tensile strength, elongation at break, and Shore hardness increased by 55%, 58%, and 9% respectively. No 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). In summary, the experimental results show that after the TPA printed parts are post-treated with dye coloring, the dye is evenly and thoroughly penetrated and combined in the printed parts, achieving a high dyeing rate of the dye, improving the problem of uneven coloring of fine structures, and improving the surface finish of the product while also improving the mechanical properties and aesthetics.

[0030] Part 2: General coloring post-processing of PLA printed parts using fused deposition modeling (FDM).

[0031] Preparation of dye solution: prepare the materials required for dye solution preparation, mix the organic solvent and ethanol at a ratio of (5-20) : 1 at room temperature to obtain an organic solvent mixed solution for color fixation; prepare the dye and organic solvent mixed solution at a mass ratio of (1-10) : (100-500) and place them in a container and stir them thoroughly to obtain the required organic solvent mixed dye solution. The dye is one or more of direct dye, insoluble azo dye, vat dye, sulfur dye, and acid dye.

[0032] Preparation of PLA printed parts: PLA printed parts have a rough surface with obvious layer patterns. The raw material is PLA filament, and the processing technology is melt lamination molding process.

[0033] Universal coloring of PLA printed parts: Place the PLA printed parts in a mixed dye solution of organic solvents and immerse them for 60 to 300 seconds. The dye is adsorbed and wrapped onto the surface of the PLA printed parts by immersion, and the coloring is completed by physical adsorption.

[0034] Color fixation treatment of PLA printed parts: the colored printed parts are placed in a mixed solution of organic solvents, the organic solvent slightly dissolves the surface of the PLA printed parts, so that the surface layers are reduced and smoothed, and the surface dye is further fixed. The PLA printed parts treated with organic solvents are placed in a blast dryer, the temperature is adjusted to 50°C, the time is 24 hours, fully dried, the residual solvent is removed, and the PLA printed parts are naturally cooled to room temperature to obtain the PLA printed parts enhanced by post-coloring treatment. 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.

[0035] Example 2 The organic solvent DMF and ethanol were mixed at a ratio of 5:1 at room temperature to obtain a mixed solution. Acid dye (acid yellow 17) was placed in a container at a ratio of 1:100 (dye: mixed solution) and stirred thoroughly to obtain an organic solvent mixed dye solution (the mass of the product was 1). PLA strips and round blocks to be colored (GB / T 1040.2-2006, IOS 868:2003 GB / T 2411-2003) were placed in the organic solvent mixed dye solution and immersed for 210 seconds. The product was taken out of the container with a special fixture and drained at room temperature. The PLA printed product was then placed in a blast dryer and the temperature was adjusted to 50°C for 24 hours. It was fully dried to remove the residual solvent, and then taken out and naturally cooled to room temperature to obtain a PLA printed product enhanced by post-coloring treatment.

[0036] The organic solvent DMF and ethanol were mixed at a ratio of 5:1 at room temperature to obtain a mixed solution. Acid dye (acid red 18) was placed in a container at a ratio of 2:150 (dye: mixed solution) and stirred thoroughly to obtain an organic solvent mixed dye solution (the mass of the product was 1). PLA strips and round blocks to be colored (GB / T 1040.2-2006, IOS 868:2003 GB / T 2411-2003) were placed in the organic solvent mixed dye solution and immersed for 180 seconds. The product was taken out of the container with a special fixture and drained at room temperature. The PLA printed product was then placed in a blast dryer and the temperature was adjusted to 50°C for 24 hours. It was fully dried to remove the residual solvent, and then taken out and naturally cooled to room temperature to obtain a PLA printed product enhanced by post-coloring treatment.

[0037] The organic solvent DMF and ethanol were mixed at a ratio of 5:1 at room temperature to obtain a mixed solution. Acid dye (acid black LD) was placed in a container at a ratio of 3:200 (dye: mixed solution) and fully stirred to obtain an organic solvent mixed dye solution (the mass of the product was 1). PLA strips and round blocks to be colored (GB / T 1040.2-2006, IOS 868:2003 GB / T 2411-2003) were placed in the organic solvent mixed dye solution and immersed for 150 seconds. The product was taken out of the container with a special fixture and drained at room temperature. Then, the PLA printed product was placed in a blast dryer, the temperature was adjusted to 50°C, the time was 24 hours, and it was fully dried to remove the residual solvent. The product was taken out and naturally cooled to room temperature to obtain a PLA printed product enhanced by coloring post-treatment.

[0038] According to GB / T 10610, IOS105-B02, EN ISO 15701 and SATRA CM44 standards, the roughness and abrasion fastness of samples (IOS868:2003GB / T 2411-2003) of acid yellow 17, acid red 18 and acid black LD group were tested respectively. The results are shown in Table 3.

[0039] Table 3 The tensile strength and elongation at break of the sample GB / T 1040.2-2006 were tested according to ISO 527 standard. The results are shown in Table 4.

[0040] Table 4 In Example 2, the printed parts are used as comparative cases. The roughness, color fastness, tensile strength, elongation at break, and Shore hardness of the parts are significantly improved after dyeing with Acid Light Yellow 17, Acid Red 18, and Acid Black LD. The roughness of the parts is improved after dyeing with Acid Light Yellow 17, decreasing from 9.38µm to 2.7µm, 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 parts after dyeing. The color fastness of each item is good, all of which are higher than the conventional and plastic standards (grade 3-4 / 4). The roughness of the parts is improved after dyeing with Acid Red 18, decreasing from 9.38µm to 2.5µm, a decrease of 73%. The tensile strength, elongation at break, and Shore hardness are also improved. The hardness increased by 35%, 5%, and 5% respectively. No color spots appeared on the parts after dyeing. The color fastness of various items was good, all of which were higher than the conventional fabric and plastic standards (3-4 / 4 grade). The roughness of the parts was improved after acid black LD dyeing, from 9.38µm to 2.6µm, a decrease of 72%. The tensile strength, elongation at break, and Shore hardness increased by 32%, 6%, and 6% respectively. No color spots appeared on the parts after dyeing. The color fastness of various items was good, all of which were higher than the conventional plastic standards (3-4 / 4 grade). Based on the above experimental results, it can be concluded that after the PLA printed parts are post-treated with dye coloring, the dye is evenly and thoroughly penetrated and combined in the printed parts, achieving a high dyeing rate of the dye, improving the problem of uneven coloring of fine structures, and improving the surface finish of the product while also improving the mechanical properties and aesthetics.

[0041] Part III: General coloring post-processing of EPU44 printed parts using stereolithography (DLP).

[0042] Preparation of dye solution: prepare the materials required for dye solution preparation, mix the organic solvent and ethanol at a ratio of (1-20):1 at room temperature to obtain an organic solvent mixed solution for color fixation; prepare the reactive polyurethane dye and the organic solvent mixed solution at a mass ratio of (1-10):(100-500) and place them in a container and stir them thoroughly to obtain the required organic solvent mixed dye solution. The dye is one or more of direct dye, acid dye and reactive dye.

[0043] Preparation of EPU44 printed parts: The raw material is EPU44, and the processing technology is photosensitive resin selective curing process.

[0044] Universal coloring of EPU44 parts: Place the EPU44 printed parts to be colored in a mixed dye solution of organic solvents and immerse for 60 to 300 seconds. The dye is adsorbed and wrapped onto the surface of the EPU44 printed parts by immersion, and the coloring is completed by physical adsorption.

[0045] Color fixation treatment of EPU44 printed parts: the colored printed parts are placed in a mixed solution of organic solvents. The organic solvent slightly dissolves the surface of the EPU44 printed parts, making the surface of the EPU44 printed parts smooth and further fixing the surface dye. The EPU44 parts treated with organic solvents are placed in a blast dryer, the temperature is adjusted to 50°C, the time is 48 hours, fully dried, the residual solvent is removed, and the parts are taken out and naturally cooled to room temperature to obtain EPU44 printed parts enhanced by post-coloring treatment. The mixed solution of organic solvents is two or more of methanol, ethanol, butanol, xylene, benzene, ethyl acetate, acetone, dichloromethane, chloroform, and hexafluoroisopropanol.

[0046] Example 3 The organic solvent chloroform and ethanol are mixed at a ratio of 5:1 at room temperature to obtain a mixed solution. The medium-temperature reactive dye (CI5# black) is placed in a container at a ratio of 1:100 (dye: mixed solution) and fully stirred to obtain an organic solvent mixed dye solution (the mass of the product is 1). The EPU44 specimens 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 immersed for 210 seconds. The product is taken out of the container with a special clamp and drained at room temperature. Subsequently, the EPU44 printed product is placed in a blast dryer, the temperature is adjusted to 50°C, the time is 48 hours, and it is fully dried to remove the residual solvent. The product is taken out and naturally cooled to room temperature to obtain an EPU44 printed product enhanced by post-coloring treatment.

[0047] The organic solvent chloroform and ethanol are mixed at a ratio of 5:1 at room temperature to obtain a mixed solution. The medium-temperature reactive dye (CI21# turquoise blue) is placed in a container at a ratio of 2:150 (dye: mixed solution) and fully stirred to obtain an organic solvent mixed dye solution (the mass of the product is 1). The EPU44 specimens 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 immersed for 150 seconds. The product is taken out of the container with a special clamp and drained at room temperature. Subsequently, the EPU44 printed product is placed in a blast dryer, the temperature is adjusted to 50°C, the time is 48 hours, and it is fully dried to remove the residual solvent. The product is taken out and naturally cooled to room temperature to obtain an EPU44 printed product enhanced by post-coloring treatment.

[0048] The organic solvent chloroform and ethanol are mixed at a ratio of 5:1 at room temperature to obtain a mixed solution. The medium-temperature reactive dye (CI19# brilliant blue) is placed in a container at a ratio of 3:200 (dye: mixed solution) and fully stirred to obtain an organic solvent mixed dye solution (the mass of the product is 1). The EPU44 specimens 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 immersed for 90 seconds. The product is taken out of the container with a special clamp and drained at room temperature. Subsequently, the EPU44 printed product is placed in a blast dryer, the temperature is adjusted to 50°C, the time is 48 hours, and it is fully dried to remove the residual solvent. The product is taken out and naturally cooled to room temperature to obtain an EPU44 printed product enhanced by post-coloring treatment.

[0049] According to GB / T 10610, IOS105-B02, EN ISO 15701, SATRA CM44 standards, the roughness and abrasion fastness of the samples (IOS868:2003GB / T 2411-2003) of medium-temperature reactive dyes (CI5# black, CI21# turquoise blue, CI19# brilliant blue) were tested. The results are shown in Table 5.

[0050] Table 5 The tensile strength and elongation at break of the sample GB / T 1040.2-2006 were tested according to ISO 527 standard. The results are shown in Table 6.

[0051] Table 6 project Print CI5#Black CI21#Turquoise Blue CI19#Brilliant Blue Tensile Strength 19MPa 27MPa 25MPa 26MPa Elongation at break 205% 254% 248% 250% Shore Hardness 85A 81A 79A 80A In Example 3, the printed parts are used as comparative cases. The roughness, color spots, color fastness, tensile strength, elongation at break, and Shore hardness of the parts after dyeing with CI5# black, CI21# turquoise blue, and CI19# brilliant blue are significantly improved. The roughness of the parts after dyeing with CI5# black 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 conventional fabric and plastic standards (3-4 / 4 grades). The roughness of the parts after dyeing with CI21# turquoise blue is improved, decreasing from 5µm to 2.5µm, a decrease of 50%. The tensile strength, elongation at break, and Shore hardness are respectively The roughness of the parts after dyeing with CI19# Brilliant Blue was improved by 32%, 21%, and 7.1%, and no spots appeared on the parts after dyeing. The color fastness of various items was good, all of which were higher than the standards of conventional fabrics and plastics (grade 3-4 / 4). The roughness of the parts after dyeing with CI19# Brilliant Blue was improved, from 5µm to 2.6µm, a decrease of 48%. The tensile strength, elongation at break, and Shore hardness were increased by 37%, 22%, and 6%, respectively. No spots appeared on the parts after dyeing. The color fastness of various items was good, all of which were higher than the standards of conventional fabrics and plastics (grade 3-4 / 4). Based on the above experimental results, it can be concluded that after the EPU44 printed parts are post-treated with dye coloring, the dye is evenly and thoroughly penetrated and combined in the printed parts, achieving a high dyeing rate of the dye, improving the problem of uneven coloring of fine structures, and improving the surface finish of the product while also improving the mechanical properties and aesthetics.

Claims

1. A general coloring post-processing method for 3D printing, characterized in that: 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 parts are 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 parts to complete the coloring; (d) Color fixation treatment of 3D printed parts: using organic solvents to slightly dissolve the surface of 3D printed parts to promote the closure of surface micropores to fix the dye; after color fixation, the residual organic solvent is removed to obtain a 3D printed part that has been enhanced by post-coloring treatment.

2. The 3D printing general coloring post-processing method according to claim 1, characterized in that: The material of the 3D printed parts is selected from any one of PLA and TPU in the wire material category, PA11, PA12, ABS, PEEK, PP, TPA, TPU in the powder material category, and EPU44, EPU46, epoxy resin and various types of light-curing and thermoplastic resins in the resin material category.

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

4. The 3D printing general coloring post-processing method according to claim 1, characterized in that: The dye in step (a) is one or more of fluorescent dyes, direct dyes, vat dyes, sulfur dyes, acid dyes, and reactive dyes; the 3D printed parts prepared in step (b) are TPA printed parts of 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).

5. The 3D printing general coloring post-processing method according to claim 4, characterized in that: 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 product is placed in the organic solvent mixed dye solution and immersed for 30-300 seconds, the organic solvent mixed solution slightly dissolves and fixes the dye on the surface of the product, and then the organic solvent-treated TPA printed product is dried at a temperature of 50°C for 24 hours to obtain a TPA printed product enhanced by post-coloring treatment.

6. The 3D printing general coloring post-processing method according to claim 1, characterized in that: The dye in step (a) is one or more of direct dyes, insoluble azo dyes, vat dyes, sulfur dyes, and acid dyes; the 3D printed parts prepared in step (b) are PLA printed parts by fused deposition modeling (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.

7. The 3D printing general coloring post-processing method according to claim 6, characterized in that: 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 product is placed in the organic solvent mixed dye solution and immersed for 60-300 seconds, the organic solvent mixed solution slightly dissolves and fixes the dye on the surface of the product, and then the organic solvent-treated PLA printed product is dried by blast drying at a temperature of 50° C. for 24 hours to obtain a PLA printed product enhanced by post-coloring treatment.

8. The 3D printing universal coloring post-processing method according to claim 1, characterized in that: The dye in step (a) is one or more of direct dyes, acid dyes, and reactive dyes; the 3D printed product prepared in step (b) is an EPU44 product of stereolithography (DLP); and 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.

9. The 3D printing general coloring post-processing method according to claim 8, characterized in that: 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 product 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 product through immersion to complete coloring, and then the organic solvent-treated EPU44 printed product is dried by blast drying at a temperature of 50°C for 48 hours to obtain an EPU44 printed product enhanced by post-coloring treatment.

10. The 3D printing general coloring post-processing method according to claims 4 to 9, 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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