3D Printed Polypropylene Parts Resistant to Warping and Shrinking Deformation and Their Manufacturing Processes

Abstract

The present invention provides a 3D printed polypropylene part resistant to warping and shrinkage deformation and its manufacturing process. In this process, syndiotactic polypropylene (sPP) and isotactic polypropylene (iPP) are mixed in a mass ratio of (38 - 42):(58 - 62), and then processed into filaments for 3D printing through melt extrusion molding. Subsequently, a 3D printed polypropylene part is obtained using a fused deposition modeling 3D printing device. By adding a specific proportion of syndiotactic polypropylene to isotactic polypropylene, this method can significantly reduce the warping and shrinkage deformation of 3D printed parts during 3D printing. On the basis of this process scheme, a 3D printed polypropylene part with a chemically etched surface is further prepared through selective chemical etching, thereby forming a relatively dense mottled morphology on the surface of the 3D printed polypropylene part at the micro level, which is applicable to the biomedical field.

Description

Technical Field

[0001] The present invention relates to the field of materials for 3D printing, and particularly to a 3D printed polypropylene part resistant to warping and shrinkage deformation and its processing method. Background Art

[0002] Since the discovery of stereoselective olefin polymerization in 1954, people have entered a new era of polyolefin synthesis. Thanks to this, polypropylene (PP) has been industrially produced and applied on a large scale since 1957, and related research has been continuously carried out and deepened, making PP products last forever. There are various processing methods for PP products, including injection molding, extrusion, etc., enabling them to be processed into various products with different forms and uses. All kinds of spare parts, pipes, plastic woven products, film products, etc. prepared from PP have been extremely widely used. Currently, PP has become the second largest polymer material in terms of global production. Moreover, as a versatile polymer material, its special crystallization, controlled polymerization of polyolefins, and the influence of processing conditions on polymorphic structures, etc., have attracted the attention of many researchers.

[0003] Although syndiotactic polypropylene (sPP) and isotactic polypropylene (iPP) are both polypropylene-based materials, due to the differences in their structures, there are differences in their properties. Compared with iPP, the molecular chain flexibility of sPP is poor, and it is relatively less likely to crystallize, which also brings many differences in properties. This difference directly results in that the melting point, glass transition temperature, crystallization temperature, and crystallinity of sPP are all lower than those of iPP. Compared with iPP products, sPP products have higher transparency, impact strength, toughness, and elasticity. However, the density, hardness, tensile strength, and rigidity of sPP are all lower than those of iPP. Moreover, as the degree of polymerization and syndiotacticity of sPP increase, the melting point, crystallization temperature, etc. of sPP all increase.

[0004] Through the research on the blends of sPP and iPP, it is found that the iPP / sPP blends are phase-separated. The evaluation shows that the Flory-Huggins interaction parameter of the sPP / iPP mixture is almost zero, indicating that the interaction in the mixture is very weak. Thus, a mixture state close to phase separation is proposed. In other words, the iPP / sPP mixture is immiscible. For the blends mainly composed of iPP, sPP is dispersed in the iPP matrix in an island structure.

[0005] Rapid prototyping using 3D printing, also known as additive manufacturing, can produce parts layer by layer from a digital model, completely without tools. In the past few years, many 3D printing technologies have been developed, each with its own specific advantages, to shorten the production development cycle and produce customized parts with defined functions and personalities. For most 3D printing technologies, the concept is summarized as additive manufacturing by sequential material deposition, and its basic principle is: layer by layer. Among 3D printing technologies, extrusion-based additive manufacturing, also known as fused deposition modeling (FDM) or fused filament fabrication (FFF), is one of the most widely used processes. Here, a simplified thermoplastic extrusion process is combined with computer numerical control (CNC) technology to provide cost-effective layered processing for 3D printed parts.

[0006] However, the inventors of the present invention found in the actual production practice process that when polypropylene materials, especially isotactic polypropylene, are applied to the fused deposition modeling 3D printing technology, the typical semi-crystalline commercial thermoplastic (iPP) shows relatively high volumetric shrinkage and warpage deformation after extrusion-based 3D printing, thus significantly affecting the dimensional calibration of the 3D printed finished product. Summary of the Invention

[0007] In view of the problems raised by the above-mentioned prior art, the present invention provides a 3D printed polypropylene part and its process method for preventing warping and shrinkage deformation. The method is to add a specific proportion of syndiotactic polypropylene to isotactic polypropylene, which can significantly reduce the warping and shrinkage deformation phenomenon of 3D printed parts during 3D printing.

[0008] To achieve the above object, the present invention is implemented by a technical solution composed of the following technical measures.

[0009] On the one hand, the present invention provides a process method for a 3D printed polypropylene part for preventing warping and shrinkage deformation, mainly including the following steps:

[0010] (1) Select syndiotactic polypropylene (sPP) and isotactic polypropylene (iPP), mix them according to a mass ratio of (38 - 42):(58 - 62) for standby, as the mixed material;

[0011] (2) Process the mixed material in step (1) into a 3D printing filament through melt extrusion molding;

[0012] (3) Use the 3D printing filament obtained in step (2) through a fused deposition modeling 3D printing device to produce a 3D printed polypropylene part.

[0013] The main inventive point of the present invention is that when the inventor was developing a polypropylene material for 3D printing that resists warping and shrinkage deformation, it was found that by adding a specific proportion of syndiotactic polypropylene to isotactic polypropylene, the warping and shrinkage deformation phenomenon of 3D printed parts can be significantly reduced when used for 3D printing.

[0014] It should be added that polypropylene materials, especially isotactic polypropylene, usually do not have the phenomenon of warping and shrinkage deformation in traditional molding processes, such as compression molding processes. However, in 3D printing technology, especially in fused deposition modeling 3D printing technology, the semi-crystalline materials of the prepared 3D printed parts have a large shrinkage deformation phenomenon during cooling, which in turn leads to warping.

[0015] In addition, through actual printing tests, pure syndiotactic polypropylene usually cannot be used as the raw material for fused deposition modeling 3D printing because the 3D printing filament made of sPP material is too soft and cannot effectively extrude the molten raw material from the nozzle during the conventional fused deposition modeling 3D printing process. Therefore, it is usually not selected as the raw material for fused deposition modeling 3D printing.

[0016] In this article, the "syndiotactic polypropylene (sPP)" mentioned in step (1) is the conventional syndiotactic polypropylene in the art, which can be obtained from commercial sources or prepared by oneself.

[0017] In this article, the "isotactic polypropylene (iPP)" mentioned in step (1) is the conventional isotactic polypropylene in the art, which can be obtained from commercial sources or prepared by oneself.

[0018] In one embodiment, the raw material forms of the syndiotactic polypropylene (sPP) and isotactic polypropylene (iPP) mentioned in step (1) can include but are not limited to powder materials and pellet materials, and can also be determined according to the applicable raw material forms for the melt extrusion molding process described in step (2). When mixing and preparing for use, it can also include the pretreatment processes or other technical means applicable to polypropylene materials recorded in the prior art, such as washing and drying. However, it should be noted that the selection of the above embodiments should not affect the mass ratio of sPP and iPP.

[0019] In this article, the "melt extrusion molding process" mentioned in step (2) is a conventional process for preparing 3D printing filaments and can be a conventional process in the art, such as melt extrusion molding through equipment such as a screw extruder or a torque rheometer.

[0020] In a preferred embodiment, the melt extrusion molding process mentioned in step (2) is melt extrusion molding through a torque rheometer, and the process parameters are: the screw temperature is set at 178 - 185 °C, the nozzle temperature is set at 180 - 190 °C, and the screw speed is set at 15 - 30 rpm.

[0021] In one embodiment, the size specification of the melt-extruded 3D printing filament described in step (2) can be the conventional size standard in the technical field; it can also be adjusted according to the standard parameters of the fused deposition modeling 3D printing equipment used in step (3).

[0022] In this article, the "fused deposition modeling 3D printing equipment" described in step (3) refers to a 3D printing equipment that uses the fused deposition modeling 3D printing technology. It can be a commercially available 3D printing equipment on the market or assembled by self-research and development. In the process of manufacturing a 3D printed polypropylene part through the fused deposition modeling 3D printing equipment, the setting of 3D printing parameters can directly follow the parameters of conventional polypropylene materials in 3D printing in this field.

[0023] In one embodiment, for the 3D printed polypropylene part prepared through the fused deposition modeling 3D printing equipment described in step (3), the preferred 3D printing parameters are: the printer head temperature is set at 190 - 210 °C, the hot bed temperature is set at 70 - 90 °C, and the printing speed is set at 150 - 180 mm / min.

[0024] On the other hand, the present invention provides a 3D printed polypropylene part obtained by the above preparation method.

[0025] Based on the above preparation method, in yet another aspect, the present invention also provides a preparation method for a 3D printed polypropylene part with a chemically etched surface, mainly including the following steps:

[0026] (1) Select syndiotactic polypropylene (sPP) and isotactic polypropylene (iPP), mix them according to a mass ratio of (38 - 42):(58 - 62) and set aside as a mixture.

[0027] (2) Process the mixture in step (1) into a 3D printing filament through melt extrusion molding.

[0028] (3) Use the 3D printing filament obtained in step (2) through a fused deposition modeling 3D printing equipment to manufacture a 3D printed polypropylene part.

[0029] (4) Immerse the 3D printed polypropylene part obtained in step (3) in cyclohexane, and prepare a 3D printed polypropylene part with a chemically etched surface through the selective chemical etching of cyclohexane.

[0030] In the above technical solution, the main principle of chemical etching is based on the accidental discovery of the inventor. Based on the blend composed of sPP and iPP, cyclohexane can selectively dissolve sPP under certain conditions, capable of dissolving the sPP on the material surface, thereby forming a relatively dense mottled morphology on the surface of the 3D printed polypropylene parts at the microscopic level, further increasing the surface area of the material. Especially in the field of biomedical implant parts, the mottled morphology is more suitable for the adsorption and attachment of biological cell tissues.

[0031] In a preferred embodiment, the selective chemical etching with cyclohexane in step (4) is carried out at a temperature of 40 - 60 °C for 30 - 90 minutes.

[0032] On the other hand, the present invention provides the 3D printed polypropylene parts obtained by the above preparation method.

[0033] In an application scenario, the above 3D printed polypropylene parts can utilize their 3D printing advantages and the microscopic mottled morphology formed on the surface of the parts by chemical etching, and be applied to the field of biomedical implant parts, especially biomedical implants with complex configurations or bionic structures, such as biological scaffolds, biological fillers (especially gastric fillers).

[0034] Furthermore, by further utilizing the above selective chemical etching with cyclohexane and the objective fact that in the iPP / sPP mixture material mainly composed of iPP, sPP is dispersed in the iPP matrix in an island structure, the present invention also provides a preparation method for functional 3D printed polypropylene parts, mainly including the following steps:

[0035] (Ⅰ) Select syndiotactic polypropylene (sPP) and isotactic polypropylene (iPP), proportion them according to a mass ratio of (38 - 42):(58 - 62), and add functional additives / fillers, and mix them evenly as the mixture;

[0036] Among them, the functional additives / fillers are insoluble in cyclohexane and can be dispersed in syndiotactic polypropylene and isotactic polypropylene as a dispersed phase after the melt extrusion process;

[0037] Or, the functional additives / fillers are insoluble in cyclohexane and can accumulate at the interface of syndiotactic polypropylene and isotactic polypropylene after the melt extrusion process;

[0038] (Ⅱ) Process the mixture in step (Ⅰ) into a 3D printing filament through melt extrusion molding;

[0039] (Ⅲ) Use the 3D printing filament obtained in step (Ⅱ) through a fused deposition modeling 3D printing device to obtain 3D printed polypropylene parts;

[0040] (Ⅳ) Immerse the 3D printed polypropylene part obtained in step (Ⅲ) in cyclohexane, and prepare a functional 3D printed polypropylene part with a chemically etched surface through selective chemical etching of cyclohexane.

[0041] In the above technical solution, after the sPP on the material surface is dissolved by selective chemical etching, a relatively dense mottled morphology is formed on the surface of the 3D printed part. When the functional additive / filler is dispersed as a dispersed phase in syndiotactic polypropylene and isotactic polypropylene, the probability of its exposure to the outer surface of the part can be increased, and its functional effect can be enhanced. For example, in one embodiment, the functional additive / filler is silver nanoparticles. After selective chemical etching, the density of silver nanoparticles exposed on the outer surface of the part is significantly increased. When the functional additive / filler accumulates at the interface of syndiotactic polypropylene and isotactic polypropylene after the melt extrusion process, selective chemical etching can make the functional additive / filler more exposed on the outer surface of the part, greatly increasing its functional effect.

[0042] In one embodiment, the functional additive / filler includes but is not limited to silver nanoparticles.

[0043] On the other hand, the present invention provides a functional 3D printed polypropylene part obtained by the above preparation method.

[0044] On the other hand, the present invention provides the application of the above functional 3D printed polypropylene part in the biomedical field.

[0045] The present invention has the following beneficial effects:

[0046] 1. The 3D printed filament prepared by the present invention through the defined ratio can be smoothly printed into a part with a complete shape structure and no warping or shrinkage deformation by a fused deposition modeling device, and can be widely applied to fused deposition modeling 3D printing devices.

[0047] 2. In one of the technical solutions of the present invention, through selective chemical etching of cyclohexane, the surface of the 3D printed product is given a relatively dense mottled morphology under the microscope, further increasing the surface area of the material. Especially in the field of biomedical implant parts, the mottled morphology is more suitable for the adsorption and attachment of biological cell tissues.

[0048] 3. In one of the technical solutions of the present invention, this mottled morphology provides an idea for us to prepare multifunctional parts by 3D printing, which is beneficial to further expand the functionality of 3D printed products. Description of the Drawings

[0049] Figure 1 It is a sample photo of the 3D printed polypropylene part prepared in Example 1 of the present invention. No warping or shrinkage deformation is observed with the naked eye.

[0050] Figure 2 This is a photo of the 3D printed polypropylene part sample prepared in Comparative Example 1 of the present invention. Obvious warping and shrinkage deformation can be observed with the naked eye.

[0051] Figure 3 This is an SEM image of the outer surface of the 3D printed polypropylene part with a chemically etched surface prepared in Example 2 of the present invention. It can be clearly seen from the figure that a relatively dense mottled morphology is formed after chemical etching, including the formation of some shallow pit structures, which is beneficial to cell adsorption.

[0052] Figure 4 This is an SEM image of the outer surface of the 3D printed polypropylene part with a chemically etched surface prepared in Example 2 of the present invention. By further magnifying, it can also be observed that there are tiny holes in the mottled morphology. Detailed implementation manners

[0053] To further understand the present invention, the preferred implementation manners of the present invention will be described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the invention. Those skilled in the art can draw on the content of this article and appropriately modify the process parameters to achieve. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art, and they are all regarded as included in the present invention. The methods and applications of the present invention have been described through preferred examples, and those skilled in the art can obviously make changes or appropriate modifications and combinations to the methods and applications described herein without departing from the content, spirit and scope of the present invention to implement and apply the technical solution of the present invention. Although it is believed that those of ordinary skill in the art are fully aware of the following terms, the following definitions are still stated to help illustrate the subject matter disclosed by the present invention.

[0054] As used herein, the term "comprising" is synonymous with "primarily comprising", and is inclusive of endpoints or open-ended, and does not exclude additional unrecited elements or method steps. "Including" is a technical term used in claim language, meaning that the elements exist, but other elements can also be added and still form elements or methods within the scope of the claim.

[0055] In one aspect, the present invention provides a process method for a 3D printed polypropylene part that prevents warping and shrinkage deformation, mainly including the following steps:

[0056] (1) Select syndiotactic polypropylene (sPP) and isotactic polypropylene (iPP), mix them according to a mass ratio of (38 - 42):(58 - 62) for standby, and use them as the mixed material;

[0057] (2) Process the mixed material in step (1) into a 3D printing filament through melt extrusion molding;

[0058] (3) The 3D printing filament obtained in step (2) is processed by a fused deposition modeling 3D printing device to obtain a 3D printed polypropylene part.

[0059] In this article, the "syndiotactic polypropylene (sPP)" described in step (1) is a conventional syndiotactic polypropylene in the art, which can be obtained from commercial sources or prepared by oneself.

[0060] In a preferred embodiment, the "syndiotactic polypropylene (sPP)" described in step (1) is preferably a syndiotactic polypropylene with a crystallinity of 6% - 16%, such as LW0120 (Hunan Liwei), LW0109 (Hunan Liwei).

[0061] In this article, the "isotactic polypropylene (iPP)" described in step (1) is a conventional isotactic polypropylene in the art, which can be obtained from commercial sources or prepared by oneself.

[0062] In a preferred embodiment, the "isotactic polypropylene (iPP)" described in step (1) is preferably an isotactic polypropylene with a crystallinity of 36% - 46%, such as T30S (Dushanzi Petrochemical).

[0063] In an embodiment, the raw material forms of the syndiotactic polypropylene (sPP) and isotactic polypropylene (iPP) described in step (1) can include but are not limited to powder and pellet, and can also be determined according to the applicable raw material forms for the melt extrusion molding process described in step (2). When mixing and preparing for use, it can also include pretreatment processes or other technical means described in the prior art applicable to polypropylene materials, such as washing and drying. However, it should be noted that the selection of the above embodiments should not affect the mass ratio of sPP and iPP.

[0064] In an embodiment, the mass ratio of syndiotactic polypropylene (sPP) to isotactic polypropylene (iPP) is (38 - 42):(58 - 62), such as 38.5:61.5, 39:61, 40:60, 41:59, 41.5:58.5 or any range or point value between them.

[0065] In this article, the "melt extrusion molding process" described in step (2) is a conventional process for preparing 3D printing filaments, which can be a conventional process in the art, such as melt extrusion molding through equipment such as a screw extruder or a torque rheometer.

[0066] In a preferred embodiment, the melt extrusion molding process in step (2) is a melt extrusion molding process via a torque rheometer, and the process parameters are as follows: the screw temperature is set to 178 - 185 °C, the extrusion head is set to 180 - 190 °C, and the screw speed is set to 15 - 30 rpm. Among them, the screw temperature can be arbitrarily set within the range of 178 - 185 °C, such as 179 °C, 180 °C, 181 °C, 182 °C, 183 °C, 184 °C, or any range or point value between them; the extrusion head temperature can be arbitrarily set within the range of 180 - 190 °C, such as 181 °C, 182 °C, 183 °C, 184 °C, 185 °C, 186 °C, 187 °C, 188 °C, 189 °C, or any range or point value between them; the screw speed can be arbitrarily set within the range of 15 - 30 rpm, such as 16 rpm, 18 rpm, 20 rpm, 22 rpm, 25 rpm, 27 rpm, 29 rpm, or any range or point value between them.

[0067] In one embodiment, for the filament for melt extrusion 3D printing in step (2), the size specifications of the prepared 3D printing filament can be the conventional size standards in the technical field, such as standard sizes of 1.75 mm and 3.00 mm; or they can be adjusted according to the standard parameters of the fused deposition modeling 3D printing equipment used in step (3).

[0068] In this article, the "fused deposition modeling 3D printing equipment" in step (3) refers to a 3D printing equipment that uses the fused deposition modeling 3D printing technology, which can be a commercially available 3D printing equipment on the market or can be self-developed and assembled. In the process of manufacturing 3D printed polypropylene parts via the fused deposition modeling 3D printing equipment, the settings of the 3D printing parameters can directly follow the parameters for conventional polypropylene materials in 3D printing in this field.

[0069] In one embodiment, in step (3), the 3D printing polypropylene part is prepared via a fused deposition modeling 3D printing device, and its preferred 3D printing parameters are as follows: the printer head temperature is set to 190 - 210 °C, the hot bed temperature is set to 70 - 90 °C, and the printing speed is set to 150 - 180 mm / min. Among them, the printer head temperature can be arbitrarily set within the range of 190 - 210 °C, such as 192 °C, 195 °C, 200 °C, 205 °C, 208 °C, or any range or point value between them; the hot bed temperature can be arbitrarily set within the range of 70 - 90 °C, such as 72 °C, 75 °C, 80 °C, 85 °C, 88 °C, or any range or point value between them; the printing speed can be arbitrarily set within the range of 150 - 180 mm / min, such as 152 mm / min, 155 mm / min, 158 mm / min, 160 mm / min, 165 mm / min, 170 mm / min, 175 mm / min, 178 mm / min, or any range or point value between them.

[0070] On the other hand, the present invention provides the 3D printing polypropylene part obtained by the above preparation method.

[0071] Based on the above preparation method, in yet another aspect, the present invention further provides a preparation method for a 3D printing polypropylene part with a chemically etched surface, mainly including the following steps:

[0072] (1) Select syndiotactic polypropylene (sPP) and isotactic polypropylene (iPP), mix them in a mass ratio of (38 - 42):(58 - 62) for standby as the mixture.

[0073] (2) Process the mixture in step (1) into a 3D printing filament via melt extrusion molding.

[0074] (3) Use the 3D printing filament obtained in step (2) to prepare a 3D printing polypropylene part via a fused deposition modeling 3D printing device.

[0075] (4) Immerse the 3D printing polypropylene part obtained in step (3) in cyclohexane, and prepare a 3D printing polypropylene part with a chemically etched surface through the selective chemical etching of cyclohexane.

[0076] In a preferred embodiment, the selective chemical etching by cyclohexane in step (4) is carried out at a temperature of 40-60°C for 30-90 min. This condition is to meet the selective chemical etching of cyclohexane. If the temperature is lower than 40°C (for example, room temperature of 20-30°C), the sPP will swell in the cyclohexane instead of dissolving. At the same time, too high a temperature may easily cause safety risks during the use of cyclohexane. The etching time is to ensure that the etched part is only the sPP. If the etching time is too long (more than 90 min), the iPP in the sample will also swell, resulting in changes in the size of the workpiece.

[0077] On the other hand, the present invention provides a 3D printed polypropylene part obtained by the above preparation method.

[0078] In one application scenario, the above-mentioned 3D printed polypropylene parts can be applied to the field of biomedical implant parts by utilizing their 3D printing advantages and the microscopic mottled morphology of the surface of the parts formed by chemical etching, especially biological implants with complex configurations or biomimetic structures, such as biological scaffolds and biological fillers (especially gastric fillers).

[0079] Furthermore, by utilizing the selective chemical etching of cyclohexane and the objective fact that in an iPP / sPP mixture material mainly composed of iPP, sPP is dispersed in the iPP matrix in an island structure, and by further utilizing the above technical solution, the present invention also provides a method for preparing a functional 3D printed polypropylene part, which mainly includes the following steps:

[0080] (I) selecting syndiotactic polypropylene (sPP) and isotactic polypropylene (iPP), preparing the materials in a mass ratio of (38-42):(58-62), adding functional additives / fillers, and mixing them uniformly to obtain a mixed material;

[0081] The functional additive / filler is insoluble in cyclohexane and can be dispersed in the syndiotactic polypropylene and isotactic polypropylene as dispersed phase after the melt extrusion process;

[0082] Alternatively, the functional additive / filler is insoluble in cyclohexane and can accumulate at the interface of syndiotactic polypropylene and isotactic polypropylene after the melt extrusion process;

[0083] (II) processing the mixture of step (I) into filaments for 3D printing by melt extrusion;

[0084] (III) processing the 3D printing filament obtained in step (II) through a fused deposition modeling 3D printing device to produce a 3D printed polypropylene part;

[0085] (Ⅳ) Immerse the 3D printed polypropylene part obtained in step (Ⅲ) in cyclohexane, and prepare a functional 3D printed polypropylene part with a chemically etched surface through selective chemical etching with cyclohexane.

[0086] In the above technical solution, after the sPP on the material surface is dissolved by selective chemical etching, a relatively dense mottled morphology is formed on the surface of the 3D printed part. When the functional additive / filler is dispersed as a dispersed phase in syndiotactic polypropylene and isotactic polypropylene, the probability of its exposure to the outer surface of the part can be increased, and its functional effect can be enhanced. For example, in one embodiment, the functional additive / filler is silver nanoparticles, and after selective chemical etching, the density of silver nanoparticles exposed on the outer surface of the part is significantly increased. When the functional additive / filler accumulates at the interface between syndiotactic polypropylene and isotactic polypropylene after the melt extrusion process, selective chemical etching can make the functional additive / filler more exposed on the outer surface of the part, greatly increasing its functional effect.

[0087] In one embodiment, the functional additive / filler includes, but is not limited to, silver nanoparticles.

[0088] On the other hand, the present invention provides a functional 3D printed polypropylene part obtained by the above preparation method.

[0089] On the other hand, the present invention provides the application of the above functional 3D printed polypropylene part in the biomedical field.

[0090] The following will further explain the present application with reference to the examples. However, those skilled in the art should understand that these examples are provided only for the purpose of illustration and are not intended to limit the present application.

[0091] Examples

[0092] The following will describe in detail the embodiments of the present application in conjunction with the examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. For those not specified in the examples, the operations are carried out under conventional conditions or conditions recommended by the manufacturer. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase. The present application should not be construed as being limited to the specific examples described.

[0093] The parts in the following examples were observed by a FEI Inspect F-SEM instrument at an acceleration voltage of 20 kV.

[0094] Example 1

[0095] The process method of a 3D printed polypropylene part for preventing warping and shrinkage deformation in this example mainly includes the following steps:

[0096] (1) Select syndiotactic polypropylene pellets and isotactic polypropylene pellets, mix them according to a mass ratio of 40:60 for standby, and use them as the mixed material;

[0097] (2) Process the mixed material in step (1) through a torque rheometer for melt extrusion molding into filaments for 3D printing; The process parameters are: the screw temperature is set at 178 - 185 °C, the extrusion head is set at 180 - 190 °C, and the screw speed is set at 15 - 30 rpm;

[0098] (3) Process the filaments for 3D printing obtained in step (2) through a fused deposition modeling 3D printing device (German RepRapX350pro) to obtain 3D printed polypropylene parts; The process parameters are: the printer head temperature is set at 190 - 210 °C, the hot bed temperature is set at 70 - 90 °C, and the printing speed is set at 150 - 180 mm / min.

[0099] The sample photo of the obtained 3D printed polypropylene part is as shown in the attached Figure 1 instructions. Visually observed, there is no warping, shrinkage or deformation.

[0100] Comparative Example 1

[0101] A process method for 3D printed polypropylene parts in this comparative example mainly includes the following steps:

[0102] (1) Select the same isotactic polypropylene pellets as in Example 1 for material preparation;

[0103] (2) Process the isotactic polypropylene pellets in step (1) through a torque rheometer for melt extrusion molding into filaments for 3D printing; The process parameters are: the screw temperature is set at 178 - 185 °C, the extrusion head is set at 180 - 190 °C, and the screw speed is set at 15 - 30 rpm;

[0104] (3) Process the filaments for 3D printing obtained in step (2) through a fused deposition modeling 3D printing device (German RepRapX350pro) to obtain 3D printed polypropylene parts; The process parameters are: the printer head temperature is set at 190 - 210 °C, the hot bed temperature is set at 70 - 90 °C, and the printing speed is set at 150 - 180 mm / min.

[0105] The sample photo of the obtained 3D printed polypropylene part is as shown in the attached Figure 2 instructions. Visually observed, there is obvious warping, shrinkage and deformation.

[0106] Comparative Example 2

[0107] A process method for 3D printed polypropylene parts in this comparative example mainly includes the following steps:

[0108] (1) Select the same syndiotactic polypropylene pellets as in Example 1 for material preparation;

[0109] (2) Melt and extrude the syndiotactic polypropylene pellets in step (1) through a torque rheometer to form filaments for 3D printing; the process parameters are: the screw temperature is set at 178 - 185 °C, the extrusion head is set at 180 - 190 °C, and the screw speed is set at 15 - 30 rpm;

[0110] (3) Use the filaments for 3D printing obtained in step (2) through a fused deposition modeling 3D printing device (German RepRapX350pro) to produce 3D printed polypropylene parts; the process parameters are: the printer head temperature is set at 190 - 210 °C, the hot bed temperature is set at 70 - 90 °C, and the printing speed is set at 150 - 180 mm / min.

[0111] During the 3D printing process, the already melted raw materials cannot be effectively extruded from the extrusion head, and the printing preparation cannot be successfully completed.

[0112] Example 2

[0113] A preparation method for a 3D printed polypropylene part with a chemically etched surface in this example mainly includes the following steps:

[0114] (1) Select syndiotactic polypropylene pellets and isotactic polypropylene pellets, mix them according to a mass ratio of 40:60 for standby as the mixture;

[0115] (2) Melt and extrude the mixture in step (1) through a torque rheometer to form filaments for 3D printing; the process parameters are: the screw temperature is set at 178 - 185 °C, the extrusion head is set at 180 - 190 °C, and the screw speed is set at 15 - 30 rpm;

[0116] (3) Use the filaments for 3D printing obtained in step (2) through a fused deposition modeling 3D printing device (German RepRapX350pro) to produce 3D printed polypropylene parts; the process parameters are: the printer head temperature is set at 190 - 210 °C, the hot bed temperature is set at 70 - 90 °C, and the printing speed is set at 150 - 180 mm / min.

[0117] (4) Immerse the 3D printed polypropylene part obtained in step (3) in cyclohexane and etch it at 40 °C for 60 min to prepare a 3D printed polypropylene part with a chemically etched surface through the selective chemical etching of cyclohexane.

[0118] The sample of the 3D printed polypropylene part with a chemically etched surface prepared has a microscopic mottled morphology under SEM observation.

[0119] The 3D printed polypropylene parts obtained by the preparation method of this embodiment are applied to the field of biomedical implant parts, especially biomedical implants with complex configurations or bionic structures, such as biological scaffolds, biological fillers (especially gastric fillers).

[0120] Example 3

[0121] A preparation method of a 3D printed polypropylene part with a chemically etched surface in this embodiment mainly includes the following steps:

[0122] (1) Select syndiotactic polypropylene pellets and isotactic polypropylene pellets, mix them according to a mass ratio of 40:60 and reserve them as a mixed material;

[0123] (2) Process the mixed material in step (1) through a torque rheometer to melt and extrude it into a wire for 3D printing; the process parameters are: the screw temperature is set at 178 - 185 °C, the extrusion head is set at 180 - 190 °C, and the screw speed is set at 15 - 30 rpm;

[0124] (3) Use the 3D printing wire obtained in step (2) through a fused deposition modeling 3D printing device (German RepRapX350pro) to obtain 3D printed polypropylene parts; the process parameters are: the printer head temperature is set at 190 - 210 °C, the hot bed temperature is set at 70 - 90 °C, and the printing speed is set at 150 - 180 mm / min.

[0125] (4) Immerse the 3D printed polypropylene parts obtained in step (3) in cyclohexane and etch them at 50 °C for 90 min to prepare 3D printed polypropylene parts with a chemically etched surface through the selective chemical etching of cyclohexane.

[0126] The sample of the 3D printed polypropylene part with a chemically etched surface prepared has a microscopic mottled morphology under SEM observation.

[0127] The 3D printed polypropylene parts obtained by the preparation method of this embodiment are applied to the field of biomedical implant parts, especially biomedical implants with complex configurations or bionic structures, such as biological scaffolds, biological fillers (especially gastric fillers).

[0128] Example 4

[0129] A preparation method of a 3D printed polypropylene part with a chemically etched surface in this embodiment mainly includes the following steps:

[0130] (1) Select syndiotactic polypropylene powder and isotactic polypropylene powder, mix them according to a mass ratio of 40:60 and reserve them as a mixed material;

[0131] (2) The mixture in step (1) is melt-extruded and formed into filaments for 3D printing via a torque rheometer; the process parameters are: the screw temperature is set to 178 - 185 °C, the extrusion head is set to 180 - 190 °C, and the screw speed is set to 15 - 30 rpm;

[0132] (3) The filaments for 3D printing obtained in step (2) are processed by a fused deposition modeling 3D printing device to obtain 3D printed polypropylene parts; the process parameters are: the printer head temperature is set to 190 - 210 °C, the hot bed temperature is set to 70 - 90 °C, and the printing speed is set to 150 - 180 mm / min.

[0133] (4) The 3D printed polypropylene parts obtained in step (3) are immersed in cyclohexane and etched for 30 min at a temperature of 60 °C to prepare 3D printed polypropylene parts with a chemically etched surface through the selective chemical etching of cyclohexane.

[0134] The samples of the 3D printed polypropylene parts with a chemically etched surface prepared have a microscopic mottled morphology under SEM observation.

[0135] The 3D printed polypropylene parts prepared by the preparation method of this example are applied to the field of biomedical implant parts, especially biomedical implants with complex configurations or bionic structures, such as biological scaffolds, biological fillers (especially gastric fillers).

[0136] Example 5

[0137] A preparation method of 3D printed polypropylene parts with a chemically etched surface in this example mainly includes the following steps:

[0138] (1) Select syndiotactic polypropylene pellets and isotactic polypropylene pellets, mix them in a mass ratio of 40:60 for standby as the mixture;

[0139] (2) The mixture in step (1) is melt-extruded and formed into filaments for 3D printing via a screw extruder; the process parameters are: the screw temperature is set to 178 - 185 °C, the extrusion head is set to 180 - 190 °C, and the screw speed is set to 15 - 30 rpm;

[0140] (3) The filaments for 3D printing obtained in step (2) are processed by a fused deposition modeling 3D printing device to obtain 3D printed polypropylene parts; the process parameters are: the printer head temperature is set to 190 - 210 °C, the hot bed temperature is set to 70 - 90 °C, and the printing speed is set to 150 - 180 mm / min.

[0141] (4) Immerse the 3D printed polypropylene part obtained in step (3) in cyclohexane and etch it at 40 °C for 90 min to prepare a 3D printed polypropylene part with a chemically etched surface through the selective chemical etching of cyclohexane.

[0142] The sample of the 3D printed polypropylene part with a chemically etched surface prepared has a microscopic mottled morphology under SEM observation.

[0143] The 3D printed polypropylene part prepared by the preparation method of this example is applied to the field of biomedical implant parts, especially biomedical implants with complex configurations or bionic structures, such as biological scaffolds and biological fillers (especially gastric fillers).

[0144] Comparative Example 3

[0145] A preparation method of a 3D printed polypropylene part in this comparative example mainly includes the following steps:

[0146] (1) Select syndiotactic polypropylene pellets and isotactic polypropylene pellets, mix them in a mass ratio of 40:60 for standby as the mixed material.

[0147] (2) Process the mixed material in step (1) through a torque rheometer to melt and extrude it into a filament for 3D printing; the process parameters are: the screw temperature is set at 178 - 185 °C, the extrusion head is set at 180 - 190 °C, and the screw speed is set at 15 - 30 rpm.

[0148] (3) Process the filament for 3D printing obtained in step (2) through a fused deposition modeling 3D printing device (German RepRapX350pro) to obtain a 3D printed polypropylene part; the process parameters are: the printer head temperature is set at 190 - 210 °C, the hot bed temperature is set at 70 - 90 °C, and the printing speed is set at 150 - 180 mm / min.

[0149] (4) Immerse the 3D printed polypropylene part obtained in step (3) in cyclohexane and etch it at 25 °C for 60 min.

[0150] The sample of the 3D printed polypropylene part prepared does not have a microscopic mottled morphology under SEM observation, and sPP is not dissolved.

[0151] Comparative Example 4

[0152] A preparation method of a 3D printed polypropylene part with a chemically etched surface in this comparative example mainly includes the following steps:

[0153] (1) Select syndiotactic polypropylene pellets and isotactic polypropylene pellets, mix them in a mass ratio of 40:60 for standby as the mixed material.

[0154] (2) The mixed material of step (1) is melt-extruded into filaments for 3D printing through a torque rheometer; the process parameters are: the screw temperature is set to 178-185° C., the extruder head is set to 180-190° C., and the screw speed is set to 15-30 rpm;

[0155] (3) The 3D printing filament obtained in step (2) is subjected to a fused deposition modeling 3D printing device (German RepRapX350pro) to obtain a 3D printed polypropylene part; the process parameters are: the printer head temperature is set to 190-210°C, the hot bed temperature is set to 70-90°C, and the printing speed is set to 150-180 mm / min.

[0156] (4) Immersing the 3D printed polypropylene product obtained in step (3) in cyclohexane, etching at 40° C. for 120 min, and preparing a 3D printed polypropylene product with a chemically etched surface by selective chemical etching of cyclohexane.

[0157] The 3D printed polypropylene sample with the chemically etched surface prepared had a microscopic mottled morphology under SEM observation, but due to the swelling of iPP, the size of the part was deformed, which was visible to the naked eye.

[0158] Example 6

[0159] The present embodiment provides a method for preparing a functional 3D printed polypropylene product, which mainly includes the following steps:

[0160] (I) selecting syndiotactic polypropylene pellets and isotactic polypropylene pellets, mixing them in a mass ratio of 40:60, and adding 1 wt% of silver nanoparticle filler as a mixed material;

[0161] (II) melt-extruding the mixture of step (I) into filaments for 3D printing through a torque rheometer; the process parameters are: the screw temperature is set to 178-185° C., the extruder head is set to 180-190° C., and the screw speed is set to 15-30 rpm;

[0162] (III) The 3D printing filament obtained in step (II) is subjected to a fused deposition modeling 3D printing device (GermanRepRap X350pro) to produce a 3D printed polypropylene part; the process parameters are: the temperature of the printer head is set to 190-210°C, the temperature of the hot bed is set to 70-90°C, and the printing speed is set to 150-180 mm / min;

[0163] (IV) Immersing the 3D printed polypropylene article obtained in step (III) in cyclohexane, etching at 40° C. for 60 minutes, and preparing a 3D printed polypropylene article with a chemically etched surface by selective chemical etching of cyclohexane.

[0164] The 3D printed polypropylene part sample with a chemically etched surface obtained by preparation has a microscopic mottled morphology under SEM observation.

[0165] Through further observation and analysis, the probability of silver nanoparticles exposed on the outer surface of the sample per unit area under microscopic conditions increases significantly.

[0166] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A method for preparing a 3D printed polypropylene part with a chemically etched surface, Features The main steps include: (1) Select syndiotactic polypropylene and isotactic polypropylene, mix them in a mass ratio of (38-42):(58-62) and set aside as a mixed material; (2) processing the mixed material of step (1) into filaments for 3D printing by melt extrusion; (3) Processing the 3D printing filament obtained in step (2) through a fused deposition modeling 3D printing device to produce a 3D printed polypropylene part; (4) Immersing the 3D printed polypropylene product obtained in step (3) in cyclohexane, and preparing a 3D printed polypropylene product with a chemically etched surface by selective chemical etching of cyclohexane.

2. The method for preparing a 3D printed polypropylene product with a chemically etched surface according to claim 1, Features: The selective chemical etching using cyclohexane in step (4) is carried out at a temperature of 40 to 60° C. for 30 to 90 minutes.

3. A 3D printed polypropylene product with a chemically etched surface prepared by the method for preparing a 3D printed polypropylene product with a chemically etched surface as claimed in claim 1.

4. An application of the 3D printed polypropylene product with a chemically etched surface as claimed in claim 3 in the preparation of materials in the field of biomedical implants.

5. A method for preparing a functional 3D printed polypropylene part, Features The main steps include: (I) selecting syndiotactic polypropylene and isotactic polypropylene, mixing them in a mass ratio of (38-42):(58-62), adding functional additives / fillers, and mixing them uniformly to obtain a mixed material; The functional additive / filler is insoluble in cyclohexane and can be dispersed in the syndiotactic polypropylene and isotactic polypropylene as a dispersed phase after the melt extrusion process; Alternatively, the functional additive / filler is insoluble in cyclohexane and can accumulate at the interface of syndiotactic polypropylene and isotactic polypropylene after the melt extrusion process; (II) processing the mixed material of step (I) into filaments for 3D printing by melt extrusion; (III) processing the 3D printing filament obtained in step (II) through a fused deposition modeling 3D printing device to produce a 3D printed polypropylene part; (IV) Immersing the 3D printed polypropylene article obtained in step (III) in cyclohexane, and preparing a functional 3D printed polypropylene article with a chemically etched surface by selective chemical etching of cyclohexane.

6. A functional 3D printed polypropylene part with a chemically etched surface prepared by the method for preparing a functional 3D printed polypropylene part as claimed in claim 5.

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