Direct-writing printing method with controllable film-forming thickness for ink with spreading behavior

Abstract

The invention discloses a direct-writing printing method with controllable film-forming thickness for ink with spreading behavior. The direct-writing printing method comprises the following steps: (1) determining the target thickness of a fiber to be printed; (2) constructing a multi-fiber fusion geometric model for predicting the overall film thickness after fiber fusion, and determining a target value range of a control parameter corresponding to a target thickness; wherein the control parameters comprise a multi-fiber arrangement parameter and a printing parameter, and the multi-fiber arrangement parameter is the ratio of the center distance between adjacent fibers to the width after spreading; (3) target printing parameters are determined according to the target value range of the control parameters; and (4) printing on the printing substrate according to the target printing parameters and the multi-fiber arrangement parameters to form fibers with target thickness. The method can be suitable for different material systems and different structure design requirements, and accurate prediction, regulation and control and reverse design of the film layer thickness are achieved.

Description

Technical Field

[0001] This invention relates to the fields of soft material additive manufacturing and fiber direct writing printing technology, and in particular to a direct writing printing method for inks with controllable film thickness. Background Technology

[0002] Direct Ink Writing (DIW) is widely used in the fabrication of flexible devices, shape-programmable structures, and biomedical interfaces because it is applicable to a variety of soft material systems, including silicone rubber, hydrogels, photocurable resins, and liquid metal composites.

[0003] For example, Chinese patent document CN111370217A discloses a method for preparing permanent magnets by photopolymerization-assisted direct writing 3D printing; Chinese patent document CN120326929A discloses a water-soluble core material and its preparation method based on direct writing photopolymerization 3D printing.

[0004] In the soft material DIW process, the material is usually deposited in a fibrous manner, and a continuous thin film or multilayer structure is formed by the partial or complete fusion of the fibers.

[0005] However, the existing fiber film thickness has the following shortcomings: 1. Thickness is difficult to predict Film thickness is affected by nozzle diameter, extrusion speed, printing path spacing, fiber spreading degree and multi-fiber fusion behavior. Existing processes usually rely on empirical parameter tuning and lack a unified prediction method.

[0006] 2. Lack of multi-fiber fusion models After deposition, fibers spread laterally to varying degrees, and the fusion morphology between adjacent fibers changes with the path spacing and fiber width. Existing technologies lack a universal model that can describe the cross-sectional geometry changes after multi-fiber fusion.

[0007] 3. Film thickness is not designable. The lack of a quantitative model for fusion geometry makes it impossible to calculate the printing parameters in reverse from theory to obtain the target film thickness, which limits the development of high-precision thin film manufacturing.

[0008] Therefore, there is an urgent need for a general method to predict film thickness based on measurable or known single-fiber cross-sectional information through a multi-fiber fusion geometric model, so as to achieve predictability, controllability and designability of the film formation process. Summary of the Invention

[0009] This invention provides a direct-write printing method for inks with spreadable behavior that allows for controllable film thickness. It does not rely on a single-fiber spread dynamics model and can be applied to different material systems and structural design requirements, enabling accurate prediction, control, and reverse design of film thickness.

[0010] A direct-write printing method for inks with controllable film thickness, comprising the following steps: (1) Determine the target thickness of the fiber to be printed; (2) Construct a multi-fiber fusion geometric model to predict the overall membrane thickness after fiber fusion, and determine the target value range of the control parameters corresponding to the target thickness; The control parameters include multi-fiber arrangement parameters and printing parameters. The multi-fiber arrangement parameters are the center-to-center distance between adjacent fibers. Width of the fiber when it is first deposited on the platform The ratio; (3) Determine the target printing parameters based on the target value range of the control parameters; (4) Print fibers with the target thickness on the printing substrate according to the target printing parameters and multi-fiber arrangement parameters.

[0011] The specific process of step (2) is as follows: (2-1) Based on the experimentally measured data, the cross-sectional parameters of a single fiber corresponding to the printing parameters and the width of the fiber when it is just deposited on the platform are obtained. Cross-sectional parameters include effective width. ,high and cross-sectional area ; (2-2) Based on the center distance between adjacent fibers The cross-sectional parameters of a single fiber and the width of the fiber immediately after deposition onto the platform. Construct a multi-fiber fusion geometric model to predict the thickness of the membrane layer after fiber fusion; (2-3) Input the experimental data from step (2-1) into the multi-fiber fusion geometric model to obtain a table of the thickness range of the fiber fusion membrane layer under the conditions allowed by the printing parameters; (2-4) The center distance between adjacent fibers Width of the fiber when it is first deposited on the platform The ratio is used as the multi-fiber arrangement parameter; the multi-fiber arrangement parameter and the printing parameter are used as control parameters, and the target value range of the control parameter corresponding to the target thickness feature is determined according to the table.

[0012] In step (2-1), the printing parameters include the printing nozzle specification, printing temperature, printing height, printing speed, and printing air pressure.

[0013] In step (2-2), the center distance between adjacent fibers Width of the fiber when it is first deposited on the platform The ratio determines the degree of fiber fusion, and the thickness of the film layer after fiber fusion is calculated using the principle of equal height, equal area, or minimum cross-sectional energy.

[0014] In step (2-2), the multi-fiber fusion geometric model predicts the film thickness after fiber fusion using the following formula: ; in, The total width of the fibers after they have fused and cured. This refers to the width of the fiber when it is first deposited onto the platform. The contact angle when the fiber is first deposited on the platform. The contact angle is the result of fiber fusion and curing.

[0015] The total thickness of the multilayer film is obtained by summing the thicknesses of the films after the fibers of each layer are fused, taking into account the effect of cross-layer fiber misalignment.

[0016] In steps (2-4), the target thickness features are divided into uniform and non-uniform. Non-uniform thickness features include gradual thickness gradient and abrupt thickness change.

[0017] The fibers to be printed can be: silicone rubber, hydrogel, photocurable resin, polyurethane, liquid metal composite material or other curable soft material system.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. Applicable to multi-material and multi-substrate systems: As long as the initial final morphology of the fiber is input, the film thickness under different material systems can be predicted.

[0019] 2. High film thickness prediction accuracy, enabling reverse design: By integrating the geometric relationships of the model, a thickness prediction accuracy of ±5% can be achieved, and process parameters such as printing speed, extrusion speed, and path spacing can be reversed. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a flowchart of a direct-write printing method for inks with spreadable film thickness according to an embodiment of the present invention.

[0022] Figure 2 The morphology of a single fiber after it has been laid out and stabilized for various shape factors at a specific temperature.

[0023] Figure 3 This is a schematic diagram of the cross-sectional parameters of a single fiber.

[0024] Figure 4 This is a schematic diagram showing the deposition locations of multifibers with different multifiber arrangement parameters.

[0025] Figure 5 A simplified schematic diagram of the complex fiber fusion process.

[0026] Figure 6 This is a thickness prediction diagram for ultra-soft silicone on an unheated metal substrate.

[0027] Figure 7 The images show physical examples of gradual and abrupt thickness changes in silicone.

[0028] Figure 8 The actual film thickness at each stage was obtained for different multifiber arrangement parameters and temperatures. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] It should be noted that, unless otherwise specified, the features in the following embodiments and implementation methods can be combined with each other.

[0031] like Figure 1 As shown, a direct-write printing method with controllable film thickness for inks with spreading behavior includes the following steps: S1, determine the target thickness of the fiber to be printed.

[0032] S2, determine the target range of values ​​for the control parameters corresponding to the target thickness.

[0033] (1) Obtain the deposition morphology parameters of a single fiber.

[0034] Based on known experimental data, the cross-sectional parameters of a single fiber and the width of the fiber immediately deposited on the platform were obtained corresponding to the process parameters (printing nozzle specifications, printing temperature, printing height, printing speed, and printing air pressure). Cross-sectional parameters include effective width, height, and cross-sectional area, such as... Figure 3 As shown.

[0035] Based on the shape factors (such as) after a single fiber has stabilized at a specific temperature. Figure 2 As shown in the figure, the interlayer multifiber fusion morphology at this temperature is derived.

[0036] (2) Determine the arrangement of multiple fibers.

[0037] The fiber arrangement structure in the same layer is determined based on the spacing of the printing path.

[0038] like Figure 4 As shown, based on the spacing of the central generatrices between fibers Width of the fiber when it is first deposited on the platform The degree of fiber fusion can be distinguished by the difference between the two. Based on the different degrees of fiber fusion, the same layer fiber arrangement structure model can be divided into three types: (a) small spacing, (b) equal spacing, and (c) large spacing.

[0039] (3) Establish a multi-fiber fusion geometric model.

[0040] Based on the center distance between adjacent fibers The cross-sectional parameters of a single fiber and the width of the fiber immediately after deposition onto the platform. A multi-fiber fusion geometric model was constructed to predict the thickness of the membrane layer after fiber fusion.

[0041] The degree of fiber fusion is determined by the ratio of the center distance between adjacent fibers to the width of a single fiber, and a geometric description model is established for the fused cross-section with equal height, equal area, or minimum energy.

[0042] The model simplifies the complex fiber fusion process into four stages (such as...). Figure 4 (As shown).

[0043] Phase 1 model, Figure 5 Images (a) and (b) show the original appearance of the fiber-printed material before it has spread out on the substrate plane. Figure 5 In (a), based on the known initial fiber morphology parameters , , ,get: equivalent circumcircle radius of unspread fibers ; Initial fiber height ; Initial cross-sectional area of ​​a single unspread fiber ; Multiple fibers fuse into a stage two single large fiber model. Figure 5 As shown in (c) and (d), for Figure 4 (a), (b), (c) Medium-small spacing ( ), equal spacing ( Large spacing () The situations described will be discussed separately.

[0044] In the case of small pitch, considering Compared to single fibers, large fibers are more... , , The changes in the cross-sections of multiple fibers must be taken into account. ) and the empty part ( The difference in area, such as Figure 5 As shown in (b), we have: Height of overlapping section of multiple fiber cross-sections ; Height of the empty portion of the multi-fiber cross section ; Length of overlapping section of multiple fiber cross-sections ; Area of ​​unused portion of cross-section of multiple fibers ; Area of ​​overlapping sections of multiple fibers .

[0045] This leads to the determination of various parameters of the single large fiber model, such as... Figure 5 As shown in (c) and (d): Total length of a single large fiber ; Single large fiber area .

[0046] right Find the angle The partial derivative yields the fiber area change with respect to relational formula Small pitch ; Equal spacing ; Large pitch .

[0047] Similarly, we can derive the following from the conclusions regarding... Find the angle The partial derivative yields the fiber height variation with respect to relational formula ; Small pitch when hour, It will not change; when hour, It will shrink, making ; ; Substitution The relation is: ; ; when hour, It will get bigger, making ; ; Substitution The relational expression is ; ; Equal spacing ; Substitution The relational expression is ; ; Large pitch ; Substitution The relational expression is ; .

[0048] Entering Phase 3 model, such as Figure 5 As shown in (e), a single large fiber is kept in contact. Transforming the plane invariantly into an approximate trapezoid, we have: ; when When the above expression takes the minus sign, When the above expression is in the plus sign, take the plus sign.

[0049] ; ; According to the principle of constant volume, let ; get: Small pitch ( ②Equal spacing ( ③ Large spacing ( ); ; parameter It can be used to estimate the maximum height that can be achieved after the fibers are fused and leveled (this can be achieved through heating).

[0050] Finally, we enter the fourth stage model, such as Figure 5 As shown in (f), the trapezoidal plane gradually unfolds until it stabilizes, which is the final state of fiber fusion that can be seen in reality.

[0051] ; According to the principle of constant volume, let ; get ; This allows us to predict the thickness of the thin film.

[0052] (4) Output the film thickness prediction results.

[0053] Combine the various printing parameters, cross-sectional parameters, and multi-fiber arrangement parameters ( Input the above model to obtain a table of fiber cross-section film thickness ranges under the conditions allowed by the printing parameters.

[0054] (5) Output the predicted film thickness value The center distance between adjacent fibers Width of the fiber when it is first deposited on the platform The ratio is used as the multi-fiber arrangement parameter; the multi-fiber arrangement parameter and the printing parameter are used as control parameters, and the target value range of the control parameter corresponding to the target thickness feature is determined according to the table.

[0055] Based on the model output, the average thickness and local thickness distribution of the film layer ( Figure 6 Furthermore, it can determine the target value range of control parameters and printing parameters corresponding to the target film thickness characteristics based on the target film thickness.

[0056] S3, determine the target printing parameters based on the target value range of the control parameters.

[0057] S4, prints fibers with the target thickness on the printing substrate according to the target printing parameters and multi-fiber arrangement parameters.

[0058] According to printing parameters and multi-fiber arrangement parameters, ink lines with target morphological characteristics are printed on the printing substrate. The target thickness characteristics can be divided into uniform and non-uniform, among which, non-uniform thickness characteristics ( Figure 5) including thickness gradient ( Figure 7 (i) and thickness step change ( Figure 7 (ii).

[0059] By controlling and The ratio between them and the temperature are used to obtain the actual film thickness at each stage. Figure 8 The model's reliability was demonstrated by comparing it with the prediction model.

[0060] The embodiments described above provide a detailed explanation of the technical solutions and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, and equivalent substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A direct-write printing method for inks with controllable film thickness, characterized in that, Includes the following steps: (1) Determine the target thickness of the fiber to be printed; (2) Construct a multi-fiber fusion geometric model to predict the overall membrane thickness after fiber fusion, and determine the target value range of the control parameters corresponding to the target thickness; The control parameters include multi-fiber arrangement parameters and printing parameters. The multi-fiber arrangement parameters are the center-to-center distance between adjacent fibers. Width of the fiber when it is first deposited on the platform The ratio; (3) Determine the target printing parameters based on the target value range of the control parameters; (4) Print fibers with the target thickness on the printing substrate according to the target printing parameters and multi-fiber arrangement parameters.

2. The direct-write printing method for inks with controllable film thickness according to claim 1, characterized in that, The specific process of step (2) is as follows: (2-1) Based on the experimentally measured data, the cross-sectional parameters of a single fiber corresponding to the printing parameters and the width of the fiber when it is just deposited on the platform are obtained. ; Section parameters include effective width ,high and cross-sectional area ; (2-2) Based on the center distance between adjacent fibers The cross-sectional parameters of a single fiber and the width of the fiber immediately after deposition onto the platform. Construct a multi-fiber fusion geometric model to predict the thickness of the membrane layer after fiber fusion; (2-3) Input the experimental data from step (2-1) into the multi-fiber fusion geometric model to obtain a table of the thickness range of the fiber fusion membrane layer under the conditions allowed by the printing parameters; (2-4) The center distance between adjacent fibers Width of the fiber when it is first deposited on the platform The ratio is used as the multi-fiber arrangement parameter; the multi-fiber arrangement parameter and the printing parameter are used as control parameters, and the target value range of the control parameter corresponding to the target thickness feature is determined according to the table.

3. The direct-write printing method for inks with controllable film thickness according to claim 2, characterized in that, In step (2-1), the printing parameters include the printing nozzle specification, printing temperature, printing height, printing speed, and printing air pressure.

4. The direct-write printing method for inks with controllable film thickness according to claim 2, characterized in that, In step (2-2), the center distance between adjacent fibers Width of the fiber when it is first deposited on the platform The ratio determines the degree of fiber fusion, and the thickness of the film layer after fiber fusion is calculated using the principle of equal height, equal area, or minimum cross-sectional energy.

5. The direct-write printing method for inks with controllable film thickness according to claim 2, characterized in that, In step (2-2), the multi-fiber fusion geometric model predicts the film thickness after fiber fusion using the following formula: ； in, The total width of the fibers after they have fused and cured. This refers to the width of the fiber when it is first deposited onto the platform. The contact angle when the fiber is first deposited on the platform. The contact angle is the result of fiber fusion and curing.

6. The direct-write printing method for inks with controllable film thickness according to claim 5, characterized in that, The total thickness of the multilayer film is obtained by summing the thicknesses of the films after the fibers of each layer are fused, taking into account the effect of cross-layer fiber misalignment.

7. The direct-write printing method for inks with controllable film thickness according to claim 2, characterized in that, In steps (2-4), the target thickness features are divided into uniform and non-uniform. Non-uniform thickness features include gradual thickness gradient and abrupt thickness change.

8. The direct-write printing method for inks with controllable film thickness according to claim 1, characterized in that, The fibers to be printed are: silicone rubber, hydrogel, photocurable resin, polyurethane, or liquid metal composite material.

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