Preparation process of continuous carbon fiber reinforced PLA composite material for 3D printing technology

Abstract

The invention discloses a preparation process of a continuous carbon fiber reinforced PLA composite material for a 3D printing technology, and the preparation process comprises the following steps: S100: preparing raw materials: selecting continuous carbon fibers, PLA particles containing chopped CF, an antioxidant, a coupling agent, a nucleating agent and a lubricant required by production for preparing the composite material; s200, material pretreatment: in order to remove moisture contained in the material, before preparation, taking a certain amount of PLA / chopped CF particles, placing the PLA / chopped CF particles in an electrothermal constant-temperature forced air drying oven, setting a certain temperature, and drying for a certain time. By adding the antioxidant, the coupling agent and the nucleating agent into the raw materials, the resin is modified, nucleation sites are increased, PLA is promoted to crystallize rapidly, and the stability of the material is improved; and the antioxidant and the coupling agent are added to promote effective combination of the resin and the fibers and prevent unnecessary oxidation of the resin under a high-temperature condition at the same time, so that the mechanical property of the composite material is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing composite materials, and in particular to a preparation process of a continuous carbon fiber reinforced PLA composite material for 3D printing technology. Background Art

[0002] Carbon fiber reinforced thermoplastic resin-based composite materials (CFRTP) have excellent characteristics such as high specific strength, high specific modulus, high corrosion resistance and designable performance. They have been widely used in aerospace, energy transportation, sports and other fields. The use of 3D printing technology to manufacture CFRTP parts can not only retain the excellent material properties of CFRTP, but also give full play to the technical advantages of 3D printing process flexibility and strong adaptability, and realize mold-free manufacturing of various CFRTP complex structure parts. Polylactic acid is considered to be the most market-potential biodegradable polymer. PLA can be completely degraded in the natural environment, and as an environmentally friendly material, PLA can replace traditional petroleum-based polymers. Compared with other polymer materials, PLA has many outstanding properties, which makes PLA have a broad prospect of use in the field of 3D printing.

[0003] CN110408184A discloses a preparation process of PLA carbon fiber composite material for 3D printing technology, using carbon fiber to reinforce and modify PLA, and the results show that when the mass fraction of carbon fiber is 20%, the mechanical properties of PLA / carbon fiber composite material are the best. CN106700456A discloses a reinforced PLA material suitable for 3D printing, the reinforcement material used is short-cut carbon fiber, and butadiene / butyl acrylate block copolymer is used as a toughening agent, so that the material maintains a certain toughness.

[0004] And according to the existing relevant literature, by changing the fiber volume content and printing process parameters to explore the changes in mechanical properties, it is finally concluded that the tensile strength of the laminate with a CF / PLA fiber volume fraction of 8% is about 2.5 times that of the laminate with a CF / PLA fiber volume fraction of 0%, and its Young's modulus is about 2.3 times that of the laminate with a CF / PLA fiber volume fraction of 0%. At the same time, the CCF / PLA unidirectional prepreg tape was prepared by the melt impregnation method with PLA as the resin matrix and CCF as the reinforcement. The effects of processing conditions such as heat treatment temperature, processing temperature, tension, and traction speed on the mechanical properties of composite materials were studied, and the optimal process conditions were determined. The study concluded that the stress-strain behavior of the composite material can be divided into two stages. In the first stage, the stress-strain curve of the material rises rapidly, and the tensile modulus of the composite materials with fiber content of 30wt% and 35wt% reaches 14.54GPa and 17.40GPa, respectively. In the second stage, most of the fibers in the prepreg tape break, and only a small part of the fibers can withstand the load. The tensile modulus also decreases to 10.14GPa and 16.31GPa, respectively, but it is also much higher than the maximum tensile modulus of pure PLA material of 1.32GPa.

[0005] In summary, the existing data have the following problems: 1. Low fiber content. The fiber content of PLA / CF composite materials is up to 35wt%. When using chopped carbon fibers as reinforcement, the added content is easily limited. Too much chopped carbon fibers will lead to a decrease in the mechanical properties of the composite material, which is related to internal crystallization. Due to the limitation of fiber content, the improvement of the mechanical properties (especially tensile properties) of single-form fiber-reinforced thermoplastic composite materials such as 3D printed short or continuous fibers has entered a bottleneck period; 2. According to the fiber length in the forming material, 3D printed CFRTP can be divided into short carbon fiber reinforced thermoplastic composites (S-CFRTP) and continuous carbon fiber reinforced thermoplastic composites (C-CFRTP). The continuous fiber reinforcement effect is much better than the short fiber reinforcement. However, the mechanical properties of the resin matrix between continuous fibers are poor (especially tensile strength), which makes it difficult to ensure the full transfer of the internal load of the composite material, affecting the improvement of the overall performance of the composite material. 3. The preparation process is complicated. The existing process of resin modification is complicated, which will greatly increase the difficulty and cycle of preparation. Summary of the invention

[0006] The main purpose of the present invention is to provide a preparation process of continuous carbon fiber reinforced PLA composite material for 3D printing technology, which can effectively solve the problems in the background technology.

[0007] To achieve the above object, the technical solution adopted by the present invention is: A preparation process of continuous carbon fiber reinforced PLA composite material for 3D printing technology, comprising the following steps: S100: Raw material preparation: Select the continuous carbon fiber, PLA particles containing chopped CF, antioxidant, coupling agent, nucleating agent and lubricant required for production to prepare the composite material; S200: Material pretreatment: In order to remove the moisture contained in the material itself, a certain amount of PLA / short-cut CF particles are placed in an electric constant temperature blast drying oven at a certain temperature and dried for a certain time before preparation; S300: Proportional mixing: PLA / chopped CF particles, antioxidant, coupling agent, nucleating agent and lubricant are mixed in a certain proportion; S400: Put the mixed materials into an electric stirrer, fully mix the additives in the PLA / chopped CF particles, and evenly distribute them on the resin surface by using the lubricant to obtain a mixture; S500: Preparation of composite materials: A certain amount of mixture is placed in a single-screw extruder, and a sufficient amount of fiber filaments are selected to fix the position. The single-screw extruder and the prepreg tank are heated to promote the melt extrusion of the mixture and form it through a pultrusion process. The obtained material is a continuous carbon fiber reinforced PLA 3D printing composite material.

[0008] Preferably, the components of the raw materials in S100 in parts by weight are: 100 parts of PLA / short-cut CF particles, 0.1-0.5 parts of antioxidant, 0.5-2 parts of coupling agent, 0.3-0.5 parts of nucleating agent, and 0.1-1 parts of lubricant.

[0009] Preferably, the PLA / chopped CF particles are from Superlead Intelligent, the brand of carbon fiber is HF-10, the brand of antioxidant is 1010, the brand of coupling agent is KH-550, the brand of nucleating agent is XY-6119, and the brand of surfactant is PEG600.

[0010] Preferably, in step S200, the set temperature of the electric constant temperature blast drying oven is 80° C., and the drying time is 4 hours.

[0011] Preferably, the model of the electric constant temperature drying blower is Shanghai Jinghong DHG-9076A, and the model of the electric stirrer is JJ-1H200W constant speed timing.

[0012] Preferably, the single screw extruder comprises a cooling system, an extrusion system, a transmission and control system and a heating system.

[0013] Preferably, the outer surface of the single screw is divided into three sections, namely a feeding section, a compression section, and a homogenizing section.

[0014] Preferably, the three-stage temperatures of the screw extruder are 100-150°C, 200-220°C, and 200-220°C respectively, the discharge port temperature is 200-220°C, and the screw speed is 150-300rpm.

[0015] Preferably, the equipment used in the pultrusion process includes a resin impregnation tank, a heating and curing device, a traction device and a collecting device.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. By adding antioxidants, coupling agents, and nucleating agents to the raw materials, the resin is modified, the nucleation sites are increased to promote rapid crystallization of PLA, and the mechanical properties of the resin itself are improved. Adding antioxidants and coupling agents promotes the effective combination of resin and fiber while preventing unnecessary oxidation of the resin under high temperature conditions, thereby improving the mechanical properties of the composite material itself.

[0017] 2. The fiber volume content is increased by changing the die diameter and adjusting the ratio of resin to fiber to increase the overall fiber content. The prepreg fiber content prepared by this process equipment can reach 60wt%. Compared with the existing reinforcing fibers, the mechanical properties of carbon fiber are more excellent, which greatly improves the mechanical properties of the composite wire.

[0018] 3. Adding short-cut CF during the composite process increases the spatial structure, improves the mechanical interlocking between fiber and resin, resin and resin, strengthens the interface bonding between matrix and reinforcement, and forms synchronous reinforcement with continuous carbon fiber. The tensile strength can reach 1005MPa, effectively ensuring the improvement of mechanical properties, which is significantly improved compared with the existing PLA / CF composite materials.

[0019] 4. The operation is simple. You only need to put the additives and the PLA resin containing chopped CF into the screw extruder to prepare the composite wire through the pultrusion process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a process flow chart of preparing a continuous carbon fiber reinforced PLA composite material for 3D printing technology of the present invention. DETAILED DESCRIPTION

[0021] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods. Example

[0022] like Figure 1 As shown, a preparation process of continuous carbon fiber reinforced PLA composite material using 3D printing technology includes the following steps: S100: Raw material preparation: Select the continuous carbon fiber, PLA particles containing chopped CF, antioxidant, coupling agent, nucleating agent and lubricant required for production to prepare the composite material; The weight proportions of the raw materials in S100 are: 100 parts of PLA / chopped CF particles, 0.1-0.5 parts of antioxidant, 0.5-2 parts of coupling agent, 0.3-0.5 parts of nucleating agent, and 0.1-1 parts of lubricant.

[0023] Furthermore, by increasing the fiber volume content, changing the die diameter, adjusting the ratio of resin to fiber, and increasing the overall fiber proportion, the fiber content of the prepared prepreg can reach 60wt%, and the tensile strength can reach 1005MPa.

[0024] S200: Material pretreatment: In order to remove the moisture contained in the material itself, a certain amount of PLA / short-cut CF particles are placed in an electric constant temperature blast drying oven at a certain temperature and dried for a certain time before preparation; Furthermore, in step S200, the set temperature of the electric constant temperature blast drying oven is 80° C., and the drying time is 4 hours.

[0025] Furthermore, the model of the electric constant temperature drying blower is Shanghai Jinghong DHG-9076A, and the model of the electric stirrer is JJ-1H200W constant speed timing.

[0026] S300: Proportional mixing: PLA / chopped CF particles, antioxidant, coupling agent, nucleating agent and lubricant are mixed in a certain proportion; Among them, PLA / chopped CF particles are from Superlead Intelligent, the brand of carbon fiber is HF-10, the brand of antioxidant is 1010, the brand of coupling agent is KH-550, the brand of nucleating agent is XY-6119, and the brand of surfactant is PEG600.

[0027] S400: Put the mixed materials into an electric stirrer, fully mix the additives in the PLA / chopped CF particles, and evenly distribute them on the resin surface by using the lubricant to obtain a mixture; Specifically, while using additives to modify the resin, short-cut carbon fibers are introduced to strengthen the internal spatial structure of the composite material, thereby improving the mechanical interlocking effect between the resin and the fibers, and preparing a short-continuous carbon fiber synchronously reinforced PLA composite material, thereby effectively improving its mechanical properties.

[0028] S500: Preparation of composite materials: A certain amount of mixture is placed in a single-screw extruder, and a sufficient amount of fiber filaments are selected to fix the position. The single-screw extruder and the prepreg tank are heated to promote the melt extrusion of the mixture and form it through a pultrusion process. The obtained material is a continuous carbon fiber reinforced PLA 3D printing composite material.

[0029] Specifically, in step S500, only the additives and the PLA resin containing the chopped CF need to be put into a screw extruder together to prepare the composite filament through a pultrusion process to obtain a finished composite material. In addition, the machine used in the present invention is single, and only a single screw extruder is needed. The operation process only requires simple mechanical mixing of the raw materials and additives, and the preparation cycle is short and the operation is simple.

[0030] Furthermore, the single screw extruder includes a cooling system, an extrusion system, a transmission and control system and a heating system.

[0031] Furthermore, the outer surface of the single screw is divided into three sections, namely the feeding section, the compression section, and the homogenization section.

[0032] Furthermore, the three-stage temperatures of the screw extruder are 100-150°C, 200-220°C, and 200-220°C, respectively, the outlet temperature is 200-220°C, and the screw speed is 150-300rpm.

[0033] Furthermore, Figure 1 It is a process flow chart of pultrusion, and the equipment used in the pultrusion process includes a resin impregnation tank, a heating and curing device, a traction device and a collecting device.

[0034] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A preparation process of continuous carbon fiber reinforced PLA composite material for 3D printing technology, characterized in that: The following steps are involved: S100： Raw material preparation: Select the continuous carbon fiber, PLA particles containing chopped CF, antioxidant, coupling agent, nucleating agent and lubricant required for production to prepare the composite material; S200: Material pretreatment: In order to remove the moisture contained in the material itself, a certain amount of PLA / short-cut CF particles are placed in an electric constant temperature blast drying oven at a certain temperature and dried for a certain time before preparation; S300: Proportional mixing: PLA / chopped CF particles, antioxidant, coupling agent, nucleating agent and lubricant are mixed in a certain proportion; S400: Put the mixed materials into an electric stirrer, fully mix the additives in the PLA / chopped CF particles, and evenly distribute them on the resin surface by using the lubricant to obtain a mixture; S500: Preparation of composite materials: A certain amount of mixture is placed in a single-screw extruder, and a sufficient amount of fiber filaments are selected to fix the position. The single-screw extruder and the prepreg tank are heated to promote the melt extrusion of the mixture and form it through a pultrusion process. The obtained material is a continuous carbon fiber reinforced PLA 3D printing composite material.

2. The process for preparing a continuous carbon fiber reinforced PLA composite material for 3D printing technology according to claim 1, characterized in that: The components of the raw materials in the S100 are as follows: 100 parts of PLA / short-cut CF particles, 0.1-0.5 parts of antioxidant, 0.5-2 parts of coupling agent, 0.3-0.5 parts of nucleating agent, and 0.1-1 parts of lubricant.

3. The preparation process of a continuous carbon fiber reinforced PLA composite material for 3D printing technology according to claim 1, characterized in that: The PLA / chopped CF particles are from Superlead Intelligent, the brand of carbon fiber is HF-10, the brand of antioxidant is 1010, the brand of coupling agent is KH-550, the brand of nucleating agent is XY-6119, and the brand of surfactant is PEG600.

4. The process for preparing a continuous carbon fiber reinforced PLA composite material for 3D printing technology according to claim 1, characterized in that: In step S200, the set temperature of the electric constant temperature blast drying oven is 80° C., and the drying time is 4 hours.

5. The process for preparing a continuous carbon fiber reinforced PLA composite material for 3D printing technology according to claim 1, characterized in that: The model of the electric constant temperature drying blower is Shanghai Jinghong DHG-9076A, and the model of the electric stirrer is JJ-1H200W constant speed timing.

6. The process for preparing a continuous carbon fiber reinforced PLA composite material for 3D printing technology according to claim 1, characterized in that: The single-screw extruder comprises a cooling system, an extrusion system, a transmission and control system and a heating system.

7. The process for preparing a continuous carbon fiber reinforced PLA composite material for 3D printing technology according to claim 1, characterized in that: The outer surface of the single screw is divided into three sections, namely a feeding section, a compression section and a homogenizing section.

8. The process for preparing a continuous carbon fiber reinforced PLA composite material for 3D printing technology according to claim 7, characterized in that: The three-stage temperatures of the screw extruder are 100-150° C., 200-220° C., and 200-220° C., respectively; the discharge port temperature is 200-220° C.; and the screw speed is 150-300 rpm.

9. The process for preparing a continuous carbon fiber reinforced PLA composite material for 3D printing technology according to claim 1, characterized in that: The equipment used in the pultrusion process includes a resin impregnation tank, a heating and curing device, a traction device and a collecting device.

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