Thermoplastic printing material for material stacking type color 3D printing and optical parameter regulation and control method thereof

Abstract

The invention discloses a thermoplastic printing material for material stacking type color 3D printing and an optical parameter regulation and control method thereof.The thermoplastic printing material uses PLA and / or PETG as a matrix, the transparency, the light scattering characteristic and the coloring absorption characteristic are cooperatively regulated and controlled, and the target color overlapping effect of the color overlapping behavior of multiple layers of materials is combined; reverse optimization is carried out on optical parameters of the material, so that the material has limited but sufficient light transmissivity under the single-layer printing thickness, complete color development can be realized under limited-layer stacking, meanwhile, an upper-layer material cannot completely shield a lower-layer material, and color desaturation caused by too high haze is avoided, so that a stable and predictable multi-layer color stacking effect is formed; the method can be used for constructing a material stacking scheme database, and high-color quasi-color 3D printing is achieved.

Description

A thermoplastic printing material for material stacking color 3D printing and a method for controlling its optical parameters. Technical Field

[0001] This invention relates to the field of 3D printing materials technology, and in particular to an optically stackable thermoplastic printing material for material stacking color 3D printing and a method for controlling its optical parameters. Background Technology

[0002] Current FDM (Fused Deposition Modeling) 3D printing mainly achieves color effects by changing different colored consumables or surface coatings, making it difficult to form continuous and controllable color changes in the thickness direction.

[0003] In material stacking color printing, multiple layers of materials form colors through optical superposition. However, ordinary PLA or PETG materials have the following problems: 1. Uncontrollable occlusion effect: Due to the high pigment concentration or opaque substrate, the upper printing material will completely block the color of the lower material, making it impossible to form mixed colors.

[0004] 2. Color rendering threshold is too high: Some transparent materials are too transparent and cannot show obvious colors within a limited number of printing layers (such as 3-5 layers). They need to be stacked very thickly to show color, which does not meet the requirements of printing efficiency.

[0005] 3. Haze leads to desaturation: Some translucent materials are usually accompanied by high haze. As the number of layers increases, light scattering increases sharply, causing the mixed color to turn white or gray (desaturation). This makes the contribution of deep color superposition nonlinearly decay, making it difficult to form a predictable color superposition relationship.

[0006] Furthermore, existing technologies lack a unified method for predicting and verifying the color overlay effect of multi-layer materials during the material design stage. The inconsistency in the color overlay behavior of different batches of materials further limits the feasibility of achieving high color accuracy color 3D printing based on material stacking methods. Therefore, it is necessary to propose a new printing material and its optical parameter control method to enable the material to form a stable, predictable, and verifiable color overlay relationship under multi-layer stacking conditions. Summary of the Invention

[0007] The purpose of this invention is to provide a PLA / PETG-based printing material and its optical parameter control method, which enables it to fully develop color when printing with a limited number of stacked layers. At the same time, in the case of multiple stacked layers, the upper layer material will not completely block the lower layer material, and the color will not be desaturated due to excessive haze. This results in a stable and predictable color superposition relationship, which can be used to build a material stacking scheme database.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: providing a thermoplastic printing material based on PLA and / or PETG, by synergistically regulating the transmission characteristics, scattering characteristics and color absorption characteristics of the material.

[0009] The optical properties of this material are designed to meet the following balance: 1. Single-layer transmittance control: It exhibits a semi-transparent state at a single-layer printing thickness (e.g., 0.1 mm), neither fully transparent nor fully opaque; 2. Color rendering ability: It can fully render colors at a limited number of layers (e.g., 3-5 layers) and achieve a preset saturation that is visible to the naked eye; 3. Low haze retention: It exhibits stable optical overlay behavior when printing multiple layers and does not desaturate due to excessive haze.

[0010] This invention also provides a reverse control method: by pre-setting a target layering effect and printing test samples to collect optical data, the optical parameters of the material can be iteratively controlled. This method takes "color predictability" as the core constraint of the material formulation, ensuring that the material is adapted to the 3D printing layering process at the optical-physical level.

[0011] In summary, the beneficial effects of the present invention are as follows: 1. Achieving optical color mixing: Achieving optical color mixing in the thickness direction, rather than just surface coloring, thus expanding the color expression capabilities of FDM printing.

[0012] 2. Balance light transmission and color rendering: Avoid excessive transparency that leads to insufficient color rendering, while avoiding high haze that causes colors to appear white or desaturated, thus ensuring the color purity of the printed parts.

[0013] 3. Predictable color overlay: The upper layer material will not completely cover the lower layer material, ensuring a stable mapping relationship between the result of multiple color overlays and the number of stacked layers, thus improving the accuracy of color control.

[0014] 4. Supports digital solutions: Materials can be calibrated and used to build a material stacking solution database, supporting the algorithm implementation of high color accuracy color 3D printing systems. Attached Figure Description

[0015] Figure 1 is a schematic diagram of the light path transmission and color rendering principle of the printing material of the present invention in single-layer and multi-layer stacked states. It shows the process that light can still reach the lower layer after passing through the upper layer material and be reflected back to the human eye to form mixed colors; Figure 2 is a flowchart of the optical parameter control method of the printing material of the present invention; it shows the closed-loop process from setting the target to iterative control until qualified materials are obtained; Figure 3 shows the simulation of the superposition effect of eight colors from left to right, followed by the superposition structure, which is the first layer (outermost layer), the second layer, the third layer and the fourth layer in sequence; Figure 4 shows the scanning result of the printed color card; Figure 5 shows the difference between the color superposition simulation result and the scanning result, showing the color deviation. Detailed Implementation

[0017] The present invention will now be described in detail with reference to specific embodiments.

[0018] Example 1: Preparation of Optically Overprintable PLA Printing Material In this example, transparent or semi-transparent modified PLA is selected as the matrix resin.

[0019] 1. Parameter control objective: To enable the material to have limited transmittance (e.g., transmittance of 40%-60%) while exhibiting obvious material color and maintaining extremely low haze, even with a single layer thickness of 0.1 mm.

[0020] 2. Control measures in this embodiment: 1) Substrate selection: Select PLA slices with high light transmittance.

[0021] 2) Coloring components: Add nano-sized highly dispersed color powder or dye, control the amount added, and ensure that the absorbance meets the requirements at a thin layer thickness.

[0022] 3) Light scattering adjustment: Strictly control the particle size and refractive index of the filler to avoid strong light scattering (high haze) caused by excessive difference in refractive index between the filler and the matrix.

[0023] 3. Results verification: The prepared red PLA filament is semi-transparent red when printed in a single layer (0.1mm); when stacked to 4 layers, the color is bright and deep, without any whitening; when stacked to 8 layers, the color is further deepened but still maintains a sense of transparency.

[0024] Example 2: Reverse control method of optical parameters of printing material. This example describes the specific method flow for obtaining the above material: 1. Set target: Set the target color overlay effect as "the color deepens layer by layer in the stacking state of 2, 3, 4 and 5 layers, and the overall hue angle remains consistent, and the brightness decreases linearly or quasi-linearly", while requiring that the upper layer does not completely block the lower layer, and that the color does not desaturate due to excessive haze.

[0025] 2. Sample preparation and collection: Stepped test samples (containing 1 to 10 layers of thickness) were printed using the PETG material formulation to be controlled. Under natural light conditions, the transmittance, comprehensive color value (Lab*) and haze data of each step were collected using a spectrophotometer or a high-precision color sensor.

[0026] 3. Deviation analysis and control: 1) If the color of a single layer is too light, increase the concentration of the colorant.

[0027] 2) If the color of the lower layer is not visible after multiple layers are stacked, reduce the concentration of the colorant or increase the transparency of the substrate.

[0028] 3) If the color is grayish or not bright after multiple layers are stacked, it indicates that the haze is too high. It is necessary to replace the filler with one that has better light scattering properties or reduce the amount of filler used.

[0029] 4. Iterative optimization: Adjust the color absorption and scattering parameters according to the deviation, repeat printing and testing until a printing material that meets the target color overlay rule is obtained.

[0030] Example 3: Photogrammetry-based verification method for material stacking color consistency. This example uses thermoplastic printing materials for material stacking color 3D printing as the object to verify the consistency of its multi-layer color. The specific steps include: 1. Selection of base materials: Eight thermoplastic printing materials are selected: cyan, magenta, yellow, black, white, red, green and blue. The materials are based on PLA or PETG and have controllable limited transmittance at the single-layer printing thickness.

[0031] 2. Overlay Model Construction and Desired Color Calculation: Using a white background as the standard reflective substrate, and taking a 4-layer material stack as an example, a model containing 8 layers is constructed. 4 A color verification matrix for different material stacking combinations was generated, and the expected color values ​​for each stacking combination were pre-calculated using a computer. An example of the best results and its stacking order is shown in Figure 33. Sample printing and color data acquisition: Multi-layer color test samples were printed according to the material stacking combinations, and the corresponding color data were acquired using photogrammetry, as shown in Figure 4.

[0032] 4. Offset Analysis and Consistency Judgment: A color offset map is generated based on the collected color data, as shown in Figure 5. By analyzing the deviation range between the actual printing result and the expected color value in the color offset map, the color consistency and material qualification of the printing material under multi-layer stacking conditions are determined.

[0033] The materials obtained by the above method maintain a preset optical tolerance range in terms of single-layer transmittance and multi-layer color stacking characteristics across different batches, thereby ensuring the accuracy and universality of the "material stacking scheme database" built based on the material.

[0034] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A thermoplastic printing material for material stacking color 3D printing, characterized in that: 1) The printing material comprises a resin system based on PLA and / or PETG, wherein the resin system contains colorants and light scattering modifiers; 2) By synergistically regulating the material's transmittance, light scattering characteristics and color absorption characteristics, the material is configured to have limited but sufficient light transmittance at a single-layer printing thickness, and to not fail to display colors properly due to excessive transparency. 3) The printing material is configured such that, in a multi-layer stacked printing state, its optical properties ensure that the upper layer material does not completely block the lower layer material and that the optical conditions do not cause color desaturation due to excessive haze, thereby enabling the multi-layer material to make a stable superposition contribution to the final visible color and present a predictable color superposition relationship.

2. The printing material according to claim 1, characterized in that, The predictable color superposition relationship refers to the fact that the color changes formed under different combinations of stacking layers have optical monotonicity and repeatability, so that a corresponding or approximately corresponding mapping relationship can be established between the color and the combination of stacking layers, which can be used to construct a digital material stacking scheme database.

3. The printing material according to claim 1, characterized in that, The matrix resin is a modified transparent or translucent PLA (polylactic acid) material.

4. The printing material according to claim 1, characterized in that, The matrix resin is a modified transparent or translucent PETG (polyethylene terephthalate-1,4-cyclohexanediol ester) material.

5. The printing material according to claim 1, characterized in that, Different batches of this printing material maintain the preset optical tolerance range in terms of single-layer transmittance and multi-layer overlay characteristics.

6. A method for obtaining the printing material according to any one of claims 1 to 5, characterized in that, include: a) Determine the target color overlay effect under multi-layer material stacking conditions; b) Print multi-layer stacked test samples and collect their color, light transmittance, and haze data at different stacking numbers; c) Adjust the color absorption, transmission, or scattering characteristics of the printing material based on the deviation between the collected data and the target color superposition effect; d) Repeat steps b) and c) until a printing material is obtained that can fully display colors, with the upper layer not completely obscuring the lower layer, and without color desaturation due to excessive haze at a limited number of stacked layers.

7. The method according to claim 6, characterized in that, The target color overlay effect makes the color changes under different combinations of stacking layers monotonous and predictable.

8. The method according to claim 6, characterized in that, The collected data includes the visible light transmittance, overall color value, and haze of multi-layer stacked samples measured under natural lighting conditions.

9. The printing material according to claim 1, characterized in that, The basic color system of the printing material includes eight colors: cyan (C), magenta (M), yellow (Y), black (K), white (W), red (R), green (G), and blue (B). The predictable color overlay relationship means that, on a white background, the color changes formed by the above eight materials under different stacking layer combinations are consistent with the preset target overlay effect, and the color changes possess optical monotonicity and repeatability. Monotonicity refers to the unidirectional trend of brightness or saturation of the overall color as the number of stacking layers increases.

10. The method according to claim 6, characterized in that, In step a, taking a 4-layer material stack as an example, a structure containing 8... 4 Color verification matrix for different material stacking combinations; The corresponding multi-layer color overlay results are obtained by photogrammetry, and a color offset map is generated based on the obtained color data. This map is used to characterize the deviation between the actual printed sample and the expected color result pre-calculated by the computer. The deviation range of the color offset map is used as the criterion for determining whether the printing material is qualified.

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