Polycarbonate powder for selective laser sintering and preparation method thereof

Abstract

The invention relates to polycarbonate powder for selective laser sintering and a preparation method of the polycarbonate powder. The polycarbonate powder is prepared from a PC raw material, an antioxidant, an anti-hardening agent and a reinforcing aid. Compared with a traditional nylon powder material, the material has the advantages that the printing window is wide, the material cost is low, the powder reuse rate reaches up to 100%, and the material has a great market prospect in the field of powder materials for SLS printing.

Description

Technical Field

[0001] This invention relates to a polycarbonate powder material that enables selective laser sintering (SLS) printing, belonging to the category of special materials. It can be used to achieve printing with a selective laser sintering (SLS) 3D printer. Background Technology

[0002] 3D printing technology, as an emerging technology, is gaining increasing popularity among businesses and enthusiasts due to its mold-free and waste-free characteristics. Currently available 3D printing materials mainly include filaments, powders, and photosensitive liquids. In terms of printing methods, filaments primarily utilize Fused Deposition Modeling (FDM), powders mainly employ SLS, Multi-Jet Fusion (MJF), and Stereolithography (SLA) processes, while photosensitive liquids are printed via photopolymerization. Among these printing methods, SLS technology has not seen widespread adoption. This is partly because there are no mature applications for this printing method in the market, resulting in stagnant market demand; and partly because the high cost of materials and equipment, as well as the high technical barriers, limit its widespread adoption.

[0003] Nylon powder boasts advantages such as high compatibility with SLS equipment and ease of processing, making it the most widely used powder in SLS printing. However, its high market price, tendency to warp, and low reusability limit its widespread application. Later-developed thermoplastic polyurethane (TPU) and polypropylene (PP) powders still lag behind nylon powder in terms of printing range and practicality. TPU powder, produced through cryogenic grinding, has a relatively rough surface; PP powder, due to its warping properties, significantly limits the height of printed parts. Therefore, there is an urgent need in the market to develop a low-cost, highly reusable, and easy-to-print powder.

[0004] Polycarbonate (PC) is a common thermoplastic material with advantages such as low cost and good temperature resistance, and is widely used globally. However, due to the difficulty in crystallizing PC and the lack of a fixed melting point, it is difficult to use in SLS (Surface Mount Technology) printing equipment. If a PC powder suitable for SLS equipment could be developed, the product would show great application potential in the 3D printing market. Summary of the Invention

[0005] The purpose of this invention is to provide a PC powder for 3D printing that can be selectively laser sintered (SLS) and its preparation method. This powder can be printed using SLS equipment, with no warping during printing and a reusability rate of up to 100%, showing great promise for applications in the field of 3D printing.

[0006] A PC powder for 3D printing comprises the following reaction materials: PC raw material, antioxidant, anti-caking agent and reinforcing agent.

[0007] In this invention, the PC powder is characterized by the following composition: based on the total amount of PC raw materials, the antioxidant accounts for 0-1% by mass, the anti-caking agent accounts for 0-1% by mass, and the reinforcing agent accounts for 0-30% by mass.

[0008] In this invention, the PC powder is characterized in that: the PC raw material is one or more of the following: PC powder obtained by phosgene method and PC powder obtained by solution crystallization treatment of PC particles obtained by transesterification method.

[0009] In this invention, the PC powder is characterized in that: the antioxidant is one or more of hindered amines, cuprous iodide, potassium iodide, hindered phenols, phosphites, and inorganic phosphates; and / or, the anti-caking agent is one or more of carbon black, titanium dioxide, silicon dioxide, aluminum oxide, zinc oxide, and polymer nanocomposite materials; and the reinforcing agent is one or more of glass microspheres, glass fiber, wollastonite, barium sulfate, calcium carbonate, and mica.

[0010] In this invention, the PC raw material is characterized by: the test conditions being 320℃ and 10kg; the melt index range of the raw material being 20-80g / 10min, preferably 25-60g / 10min; and / or, the median particle size range of the PC raw material being 1-100um; and it also having a certain degree of crystallinity and a relatively narrow melting range.

[0011] In this invention, PC particles are prepared by transesterification. The good solvent used for solution treatment is one or more of chlorinated hydrocarbon liquids, dichloromethane, chloroform, and carbon tetrachloride. After dissolving the PC particles in the good solvent at room temperature, a precipitating agent is added dropwise to the system. The precipitating agent is a poor solvent such as water or ethanol. The addition of the precipitating agent is accompanied by continuous stirring at a speed of 300-800 rpm.

[0012] The positive effects of this invention are that it prepares a PC powder for 3D printing, which has lower cost, can be printed using SLS equipment, has a wider printing window, and can achieve a powder reuse rate of up to 100%. Attached Figure Description

[0013] Figure 1 The DSC curve of PC powder in Example 1; Figure 2 The DSC curve of PC powder in Example 3; Figure 3 The DSC curves for PC powder are shown as a comparative example. Depend on Figure 1 , Figure 2 It is known that PC powder used in laser sintering exhibits a significant melting peak during the first stage of heating, which provides a basis for the shaping control of laser sintering. Figure 3The comparative PC powder has no melting peak, making it difficult to sinter and form. Detailed Implementation

[0014] The technical solution of the present invention will be described in detail below with reference to specific embodiments. The embodiments described herein are only for illustrative purposes, but the scope of protection of the present invention is not limited to the following description.

[0015] The PC raw materials were purchased from Wanhua Chemical Co., Ltd., while the antioxidants, anti-caking agents, and reinforcing additives were purchased from Yantai Runwei New Materials Co., Ltd.

[0016]

Example 1

[0017] 10 kg of phosgene PC powder with a melt index of 25 g / 10 min, 100 g of antioxidant 1010, 100 g of titanium dioxide, and 3 kg of glass microspheres were physically mixed using a high-speed mixer to obtain a PC powder with a median particle size of 89 μm and a melting point of 240 °C. This powder can be used for printing at molding temperatures of 145-170 °C and has a 100% reusability rate.

[0018]

Example 2

[0019] 10 kg of phosgene-based PC powder with a melt index of 40 g / 10 min, 50 g of antioxidant 1098, 50 g of fumed silica, and 1.5 kg of wollastonite were physically mixed using a high-speed mixer to obtain a PC powder with a median particle size of 55 μm and a melting point of 240 °C. This powder can be used for printing at molding temperatures of 145-165 °C, and has a 100% reusability rate.

[0020]

Example 3

[0021] 10 kg of transesterified PC particles with a melt index of 60 g / 10 min were dissolved in 100 L of dichloromethane. Water was then added dropwise to the system titrally at 800 rpm. The precipitated powder was collected, centrifuged, and dried to obtain a PC powder with a median particle size of 30 μm. This powder can be printed at molding temperatures of 145-155 °C with a 100% reusability rate.

[0022]

Example 4

[0023] 10 kg of transesterified PC particles with a melt index of 50 g / 10 min were dissolved in 100 L of chloroform. Ethanol was then added dropwise to the system titrated at 300 rpm. The precipitated powder was collected, centrifuged, and dried to obtain a PC powder with a median particle size of 60 μm. This PC powder was then physically mixed with 80 g of antioxidant H10, 30 g of alumina, and 1 kg of barium sulfate using a high-speed mixer to obtain a PC powder with a median particle size of 60 μm and a melting point of 240 °C. This powder can be printed at molding temperatures of 145-160 °C with a 100% reusability rate.

[0024] [Comparative Example]

[0025] 10 kg of transesterified PC particles with a melt index of 50 g / 10 min were cryogenically pulverized to obtain a PC powder with a median particle size of 60 μm. The obtained PC powder was then physically mixed with 80 g of antioxidant H10, 30 g of alumina, and 1 kg of barium sulfate using a high-speed mixer to obtain a PC powder with a median particle size of 60 μm and no obvious melting point. This powder could not be printed.

[0026] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A polycarbonate (PC) powder for selective laser sintering, characterized in that: It contains the following reaction raw materials: PC raw materials, antioxidants, anti-caking agents and reinforcing additives.

2. The PC powder according to claim 1, characterized in that: Based on the total amount of PC raw materials, antioxidants account for 0-1% of the mass, anti-caking agents account for 0-1% of the mass, and reinforcing additives account for 0-30% of the mass.

3. The PC powder according to claim 1 or 2, characterized in that: The PC raw material is one or more of the following: PC powder obtained by phosgene method and PC powder obtained by solution crystallization treatment of PC particles obtained by transesterification method.

4. The PC powder according to any one of claims 1-3, characterized in that: The antioxidant is one or more of hindered amines, cuprous iodide, potassium iodide, hindered phenols, phosphites, and inorganic phosphates; and / or the anti-caking agent is one or more of carbon black, titanium dioxide, silicon dioxide, aluminum oxide, zinc oxide, and polymer nanocomposites; the reinforcing agent is one or more of glass microspheres, glass fiber, wollastonite, barium sulfate, calcium carbonate, talc, and mica.

5. The PC raw material according to claim 3, characterized in that: The test conditions are 320℃ and 10kg. The melt index of the raw material is 20-80g / 10min, preferably 25-60g / 10min; and / or the median particle size of the PC raw material is 1-100um. It also has a certain degree of crystallinity and a narrow melting range.

6. The PC particles obtained by the transesterification method according to claim 3, wherein the good solvent used for solution treatment is one or more of chlorinated hydrocarbon liquids, dichloromethane, chloroform, and carbon tetrachloride; after dissolving the PC particles in the good solvent at room temperature, a precipitating agent is added dropwise to the system, wherein the precipitating agent is a poor solvent such as water or ethanol; the addition of the precipitating agent is accompanied by continuous stirring at a stirring rate of 300-800 rpm.

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