Preparation method of 3D printing multi-scale layered rigid-flexible impact-resistant composite material

Abstract

The invention discloses a preparation method of a 3D printing multi-scale layered rigid-flexible impact-resistant composite material. The method comprises the following steps: designing a PLA skeleton with a multi-scale layered structure, and carrying out slicing processing to obtain an STL format file; the preparation method comprises the following steps: preparing a PLA framework through 3D printing, injecting a silicon elastomer serving as a soft material and a binder into a multi-stage layered structure of the framework, and curing to obtain the composite material. The composite material has a layered structure with three scales, the structure is realized by designing a patterned microstructure for each layer to induce a 3D printing path to stack layer by layer, and complex programming is not needed; the silicic acid gel in the gaps of each stage of layered structure is integrally formed, the composite material has the rigid-flexible coupling property, the hard PLA framework enables the composite material to have good mechanical properties, and the soft silicic acid gel provides larger deformation in the impact resisting process to achieve energy dissipation; tooth-shaped protruding interface structures which are embedded in a staggered mode are designed on the contact faces between the macroscopic layers, and the deflection direction of cracks is induced.

Description

Technical Field

[0001] The present invention relates to the field of additive manufacturing, and in particular to a method for preparing a 3D printed multi-scale layered rigid-flexible impact-resistant composite material. Background Art

[0002] 3D printing additive manufacturing technology, which has been widely used in recent years, is an advanced manufacturing technology based on digital models and formed by stacking layer by layer. 3D printing technology improves the flexibility of manufacturing production lines, produces customized products at a lower cost, and promotes the transformation of manufacturing production methods from mass production to personalized customization. 3D printing technology is used to manufacture objects with complex structures and high precision in many fields. To a certain extent, it has freed the constraints of material processing technology and provided new ideas for the design of a new generation of functional materials.

[0003] With the rapid development of machinery, vehicles, aerospace and other fields, the operating environment of some precision instruments and equipment has become more complex. Once they are subjected to extreme conditions of huge loads, they will cause irreparable losses. This has undoubtedly promoted the development of advanced protection systems and put forward higher requirements for the impact resistance of protective materials. Traditional single-material impact-resistant materials are difficult to have both strength and toughness. At the same time, they have problems such as heavy weight and high cost, which cannot meet application requirements.

[0004] In order to make the material have multiple excellent properties, a multi-material composite design is adopted, and a multi-scale layered rigid-flexible coupling impact-resistant composite material is produced. The rigid material acts as a skeleton to provide strength for the composite material as a whole, and the flexible material provides more deformation space for the composite material, thereby improving the overall toughness of the composite material. In the process of resisting loads, the hard skeleton structure is conducive to energy transfer, and the soft material embedded in the skeleton quickly dissipates energy, so that the composite material has excellent impact resistance, and its performance is greatly improved compared to traditional materials. Summary of the invention

[0005] The present invention aims to solve the technical problem of how to effectively use 3D printing technology to realize the design of multi-scale layered structures. By preparing a polymer skeleton with a multi-level layered structure, a silicone elastomer with a low viscosity before curing is injection molded into the polymer skeleton for curing, and an interlaced and inlaid tooth-like protrusion structure is designed on the contact surface of the macro layer, so that the prepared composite material has the structural characteristics of rigid-flexible coupling, excellent impact toughness and energy absorption, and provides a preparation method of a 3D printed multi-scale layered rigid-flexible impact-resistant composite material.

[0006] In order to solve the above-mentioned technical problems, the technical solution of the present invention is as follows: A method for preparing a 3D printed multi-scale layered rigid-flexible impact-resistant composite material, comprising: Step 1: Establish a polymer material library for 3D printing and a silica gel with low viscosity before curing, and preset the physical structure of the 3D printing polymer material and the assembly method of the two materials; Step 2: construct a 3D printable sample structure based on the preset in step 1, and obtain an STL format file after slicing; Step 3, import the STL format file obtained in step 2 into the 3D printer system, set the printing parameters, and complete the printing of the hard skeleton; Step 4: The silicone elastomer prepared in step 1 is injected into the hard skeleton 3D printed in step 3 and cured to form a shape. The silicone elastomer in step 1 is silica gel.

[0007] Furthermore, the main skeleton of the impact-resistant composite material is prepared by 3D printing using a polymer material that can be used for 3D printing. The polymer material is PLA, and the silicone elastomer is silica gel. The silica gel serves as a soft filler and acts as a binder for the impact-resistant composite material.

[0008] Furthermore, the main skeleton part of the impact-resistant composite material uses the smallest size of filament that can be extruded by the printer extruder as a basic unit, and a patterned microstructure is designed for each layer based on the basic unit, and printed layer by layer.

[0009] Furthermore, the basic unit spacing of the patterned microstructure is 50 μm; the minimum extrusion filament diameter of the printer is 0.4 mm, and the printing layer thickness is 2 mm.

[0010] Furthermore, the printing path of the printer extruder in each layer is completely induced by the continuity of the patterned microstructure, without the need to program the 3D printing path.

[0011] Furthermore, the main skeleton of the impact-resistant composite material is prepared, including: three macro layers are defined as first-order lamellae, the three macro layers are printed separately, each macro overall layer thickness is 4 mm, the interlayer crossing angle is 90°, each macro layer contains several second-order lamellae, the second-order lamellae are 0.4 mm thick, wherein each second-order lamellae is printed and stacked layer by layer by the printer extruder head along the same path, and each printed layer is defined as a third-order lamellae.

[0012] Furthermore, the silica gel prepared in step 4 is injected into the hard skeleton made of PLA by 3D printing while maintaining low viscosity and high pressure, so that the silica gel fully penetrates into the gaps of the layered structures of each level of the hard skeleton, and is cured for 6 hours after encapsulation.

[0013] Furthermore, the silica gel in the gaps of the layered structures at each level of the impact-resistant composite material is integrally formed, and the prepared impact-resistant composite material has the property of rigid-flexible coupling, wherein the hard PLA skeleton gives the composite material good mechanical properties, and the soft silica gel can provide greater deformation to achieve energy dissipation in the process of resisting impact.

[0014] Furthermore, an interface structure design is added to the contact surface between the three macro layers of the hard skeleton. The contact surface is a tooth-like protrusion structure that is staggered and inlaid with each other to induce the deflection direction of the crack.

[0015] The present invention has the following beneficial effects: The preparation method provided by the present invention can achieve the molding of multi-level hierarchical structures by designing a patterned microstructure to induce a 3D printing path without the need for supporting materials and programming operations.

[0016] The preparation method provided by the present invention adopts a rigid-flexible coupled material combination mode, in which the hard material serves as a skeleton to provide overall strength for the composite material, and the soft material serves as a binder and a buffer layer embedded in the gaps of the skeleton. Its good deformation ability enables the composite material to have both strength and toughness.

[0017] According to the preparation method provided by the present invention, there are crossing angles between the first-order lamellae and the second-order lamellae of the composite material. In the process of resisting impact, the cracks are continuously deflected along the direction of the structural arrangement, the extension path is more tortuous and many branch cracks are generated, the impact force is continuously unloaded, and the composite material has a good energy absorption effect.

[0018] The preparation method provided by the present invention combines 3D printing and injection molding processes to simplify the preparation method of composite materials with multi-scale layered structures, and has the advantages of low cost and high efficiency. Based on this method, it can be applied to different types of hard and soft material combinations, is not limited by size, and can meet a variety of application scenarios.

[0019] The preparation method provided by the present invention designs mutually staggered and inlaid tooth-like protrusion structures on the contact surfaces of the three macro layers, which greatly increases the interface bonding area and bonding strength. During the impact process, the tooth-like staggered protrusion structure can make the main crack deflect at a larger angle when extending to different macro layers, generate more branch cracks, and extend the effective impact resistance time of the composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0021] Figure 1 The method for inducing a microstructure printing path and a process flow chart for preparing a multi-scale layered composite material in the present invention; Figure 2A physical picture of the interlaced mosaic structure of the macroscopic layer bonding surface in the present invention; Figure 3 This is a physical picture of a multi-scale layered composite material prepared with PLA and silicone elastomer in the present invention; Figure 4 Comparison of impact cross-sectional morphologies of a multi-scale layered composite material prepared with PLA and silicone elastomer and a uniform PLA material in the present invention; Figure 5 The figure shows the comparison of the impact resistance of the multi-scale layered rigid-flexible impact-resistant composite material and the uniform PLA material in the present invention. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Therefore, the present invention combines the design of multi-scale hierarchical structure with 3D printing technology to develop a method for preparing a multi-level hierarchical rigid-flexible coupled impact-resistant composite material. By injection molding soft silica gel into a PLA skeleton with a multi-level hierarchical structure, the prepared composite material has both strength and toughness, achieving excellent impact resistance and energy absorption effect.

[0024] Combined with Figure 1-5 As shown, the specific steps of the preparation method include: Step 1: Establish a polymer material library for 3D printing and a silica gel with low viscosity before curing, and preset the physical structure of the 3D printing polymer material and the assembly method of the two materials; Step 2: construct a 3D printable sample structure based on the preset in step 1, and obtain an STL format file after slicing; Step 3, import the STL format file obtained in step 2 into the 3D printer system, set the printing parameters, and complete the printing of the hard skeleton; Step 4: The silicone elastomer prepared in step 1 is injected into the hard skeleton 3D printed in step 3 and cured to form a shape. The silicone elastomer in step 1 is silica gel.

[0025] The main skeleton of the impact-resistant composite material is prepared by 3D printing using a polymer material that can be used for 3D printing. The polymer material is PLA, and the silicone elastomer is silica gel. The silica gel serves as a soft filler and acts as a binder for the impact-resistant composite material.

[0026] The main skeleton part of the impact-resistant composite material uses the smallest size of filament that can be extruded by the printer extruder as the basic unit. The patterned microstructure of each layer is designed based on the basic unit and printed layer by layer.

[0027] The basic unit spacing of the patterned microstructure is 50 μm; the minimum extrusion filament diameter of the printer is 0.4 mm, and the printing layer thickness is 2 mm.

[0028] The printing path of the printer extruder in each layer is completely induced by the continuity of the patterned microstructure, without the need to program the 3D printing path.

[0029] The main skeleton for preparing the impact-resistant composite material includes: three macro layers are defined as first-order lamellae, the three macro layers are printed separately, each macro overall layer thickness is 4 mm, the interlayer crossing angle is 90°, each macro layer contains several second-order lamellae, and the second-order lamellae thickness is 0.4 mm, wherein each second-order lamellae is printed and stacked layer by layer by the printer extruder head along the same path, and each printed layer is defined as a third-order lamellae.

[0030] The silica gel prepared in step 4 is injected into the hard skeleton made of PLA by 3D printing under low viscosity and high pressure environment, so that the silica gel can fully penetrate into the gaps of the layered structures of each level of the hard skeleton, and then cured for 6 hours after encapsulation.

[0031] The silica gel in the gaps of each level of layered structure of the impact-resistant composite material is integrally formed, and the prepared impact-resistant composite material has the property of rigid-flexible coupling. Among them, the hard PLA skeleton gives the composite material good mechanical properties, and the soft silica gel can provide greater deformation to achieve energy dissipation in the process of resisting impact.

[0032] The interface structure design is added to the contact surface between the three macro layers of the hard skeleton. The contact surface is a tooth-like protrusion structure that is staggered and inlaid with each other to induce the deflection direction of the crack.

[0033] For the embodiments provided by this technical solution, please refer to Figure 1-5 As shown; The macroscopic skeleton (first-order lamella) with an overall size of 60mmⅹ20mmⅹ40mm is designed to have three layers. Each macroscopic layer is composed of several second-order lamellae. The three-layer structure is modeled separately using 3Dmax. After slicing, it is converted into STL files and imported into the 3D printing system. PLA is used as the printing consumables, and the extrusion wire diameter is 0.4mm. When preparing the first-order lamellae by 3D printing, Figure 1As shown in the figure, by designing the patterned microstructure of each layer when the printer is stacked layer by layer to induce the extruder head printing path, the spacing between the printing paths is controlled to be 50μm, and three first-order layers are obtained after several stacking moldings. When modeling, the contact surfaces of the three macro layers are designed with interlaced and inlaid tooth-like protrusion structures to increase the interlayer contact area and interface bonding strength. The actual picture of the preparation is shown in the figure. Figure 2 As shown; Taking the arrangement direction of the second-order lamellae as the standard, the interlayer crossing angle of the three macro layers is 90°, and the prepared silica gel is injected into the three macro layer skeletons under low viscosity and high pressure conditions, so that the silicone elastomer fully penetrates into the gap of the multi-scale layered structure and solidifies, and acts as a binder to bond the three macro layers. The prepared multi-scale layered rigid-flexible impact-resistant composite material is as follows Figure 3 As shown; For comparison, 3D printed homogeneous PLA with the same size and no structure was prepared with the same printing density and filling rate. The two samples were subjected to three-point bending tests. The moving rate of the tensile machine pressure head was set at 50 mm / min until the sample structure failed completely. The load-time curves of the two materials obtained in the experiment are as follows: Figure 4 The results show that the load of the PLA material with uniform structure increases continuously after contacting the indenter, reaching the peak load at 8s, and then breaking and failing destructively; the load curve of the multi-scale layered rigid-flexible impact-resistant composite material is undulating and sawtooth-shaped after contacting the indenter, and it is not completely broken until 24s later. This is because the complex multi-scale layered structure makes the cracks extend and deflect in multiple directions, and continuously generates branch cracks when the main crack extends, causing multiple load unloading phenomena. The material has a larger deformation space. The displacement-load curve calculation shows that the multi-scale layered rigid-flexible impact-resistant composite material has a higher energy absorption capacity and a longer impact resistance time.

[0034] In addition, by observing and analyzing the morphology of the cross section, such as Figure 5 As shown in the figure, the cross-sectional cracks of the uniform PLA material are relatively smooth, and the fracture mode is instantaneous fracture, while the fracture of the multi-scale layered rigid-flexible impact-resistant composite material has multi-directional cracks. The cracks deflect at large angles when extending to different macroscopic layers, and the cracks deflect at different angles multiple times in different directions. The multi-level layered structure and rigid-flexible coupling design make the multi-scale layered rigid-flexible impact-resistant composite material have good impact resistance.

[0035] The present invention provides a method for preparing a 3D printed multi-scale layered rigid-flexible impact-resistant composite material based on 3D printing additive manufacturing technology. A complex multi-level layered skeleton structure is prepared by designing a patterned microstructure to induce a 3D printing path, and the soft material is cleverly embedded in the hard skeleton in combination with the injection molding process to prepare a multi-scale layered rigid-flexible impact-resistant composite material with rigid-flexible coupling characteristics. The prepared multi-scale layered rigid-flexible impact-resistant composite material consists of two parts: a hard skeleton and a soft filling. The hard skeleton is formed by 3D printing using PLA as the consumable material. The skeleton structure is a multi-level layered structure, which includes three macro layers, which are defined as first-order lamellae. Each first-order lamellae contains several second-order lamellae, and each printed layer is defined as a third-order lamellae. The interlayer crossing angles are designed for each level of lamellae, and the three macro layers need to be formed separately. A soft material with low viscosity before curing is used to fill the structural gap of the hard skeleton. The injection molding process of the soft material is carried out under a high-pressure environment to achieve a 100% filling rate of the soft material. In the process of resisting impact, the hard skeleton provides overall strength for the composite material. In addition, the multi-level layered structure of the skeleton can induce large-angle deflection of the main crack and generate branch cracks. The soft material deforms to make the composite material have both strength and toughness, thereby achieving good impact resistance.

[0036] In summary, the preparation method provided by the present invention can achieve the molding of multi-level hierarchical structures by designing a patterned microstructure to induce a 3D printing path without the need for supporting materials and programming operations.

[0037] The preparation method provided by the present invention adopts a rigid-flexible coupled material combination mode, in which the hard material serves as a skeleton to provide overall strength for the composite material, and the soft material serves as a binder and a buffer layer embedded in the gaps of the skeleton. Its good deformation ability enables the composite material to have both strength and toughness.

[0038] According to the preparation method provided by the present invention, there are crossing angles between the first-order lamellae and the second-order lamellae of the composite material. In the process of resisting impact, the cracks are continuously deflected along the direction of the structural arrangement, the extension path is more tortuous and many branch cracks are generated, the impact force is continuously unloaded, and the composite material has a good energy absorption effect.

[0039] The preparation method provided by the present invention combines 3D printing and injection molding processes to simplify the preparation method of composite materials with multi-level hierarchical structures, and has the advantages of low cost and high efficiency. Based on this method, it can be applied to different types of hard and soft material combinations, is not limited by size, and can meet a variety of application scenarios.

[0040] The preparation method provided by the present invention designs mutually staggered and inlaid tooth-like protrusion structures on the contact surfaces of the three macro layers, which greatly increases the interface bonding area and bonding strength. During the impact process, the tooth-like staggered protrusion structure can make the main crack deflect at a larger angle when extending to different macro layers, generate more branch cracks, and extend the effective impact resistance time of the composite material.

[0041] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for preparing a 3D printed multi-scale layered rigid-flexible impact-resistant composite material, characterized in that: include: Step 1: Establish a polymer material library for 3D printing and a silicone elastomer with low viscosity before curing, and preset the physical structure of the 3D printing polymer material and the assembly method of the two materials; Step 2: construct a 3D printable sample structure based on the preset in step 1, and obtain an STL format file after slicing; Step 3, import the STL format file obtained in step 2 into the 3D printer system, set the printing parameters, and complete the printing of the hard skeleton; Step 4: The silicone elastomer prepared in step 1 is injected into the hard skeleton 3D printed in step 3 and cured to form a shape. The silicone elastomer in step 1 is silica gel.

2. A method for preparing a 3D printed multi-scale layered rigid-flexible impact-resistant composite material according to claim 1, characterized in that: The main skeleton of the impact-resistant composite material is prepared by 3D printing using a polymer material that can be used for 3D printing. The polymer material is PLA, and the silicone elastomer is silica gel. The silica gel serves as a soft filler and acts as a binder for the impact-resistant composite material.

3. A method for preparing a 3D printed multi-scale layered rigid-flexible impact-resistant composite material according to claim 2, characterized in that: The main skeleton part of the impact-resistant composite material uses the smallest size of filament that can be extruded by the printer extruder as the basic unit. The patterned microstructure of each layer is designed based on the basic unit and printed layer by layer.

4. A method for preparing a 3D printed multi-scale layered rigid-flexible impact-resistant composite material as claimed in claim 3, characterized in that: The basic unit spacing of the patterned microstructure is 50 μm; the minimum extrusion filament diameter of the printer is 0.4 mm, and the printing layer thickness is 2 mm.

5. A method for preparing a 3D printed multi-scale layered rigid-flexible impact-resistant composite material as claimed in claim 4, characterized in that: The printing path of the printer extruder in each layer is completely induced by the continuity of the patterned microstructure, without the need to program the 3D printing path.

6. A method for preparing a 3D printed multi-scale layered rigid-flexible impact-resistant composite material according to claim 5, characterized in that: The main skeleton for preparing the impact-resistant composite material includes: three macro layers are defined as first-order lamellae, the three macro layers are printed separately, each macro overall layer thickness is 4 mm, the interlayer crossing angle is 90°, each macro layer contains several second-order lamellae, and the second-order lamellae thickness is 0.4 mm, wherein each second-order lamellae is printed and stacked layer by layer by the printer extruder head along the same path, and each printed layer is defined as a third-order lamellae.

7. A method for preparing a 3D printed multi-scale layered rigid-flexible impact-resistant composite material according to claim 6, characterized in that: The silica gel prepared in step 4 is injected into the hard skeleton made of PLA by 3D printing under low viscosity and high pressure environment, so that the silica gel can fully penetrate into the gaps of the layered structures of each level of the hard skeleton, and then cured for 6 hours after encapsulation.

8. A method for preparing a 3D printed multi-scale layered rigid-flexible impact-resistant composite material according to claim 7, characterized in that: The silica gel in the gaps of each level of layered structure of the impact-resistant composite material is integrally formed, and the prepared impact-resistant composite material has the property of rigid-flexible coupling. Among them, the hard PLA skeleton gives the composite material good mechanical properties, and the soft silica gel can provide greater deformation to achieve energy dissipation in the process of resisting impact.

9. A method for preparing a 3D printed multi-scale layered rigid-flexible impact-resistant composite material according to claim 8, characterized in that: The interface structure design is added to the contact surface between the three macro layers of the hard skeleton. The contact surface is a tooth-like protrusion structure that is staggered and inlaid with each other to induce the deflection direction of the crack.

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