Engineering plastics have a wide range of applications due to their good strength, weather resistance and thermal stability, especially for the preparation of industrial products. Therefore, engineering plastics have become the most widely used 3D printing materials
, especially acrylonitrile-butadiene. -Styrenic copolymer (ABS), polyamide (PA), polycarbonate (PC), polyphenylsulfone (PPSF), polyether ether ketone (PEEK), etc. are most commonly used.
Different from traditional injection molding, 3D printing technology puts forward higher requirements for the performance and applicability of plastic materials. The most basic requirement is fluidity after melting, liquefaction or powdering. After 3D printing is formed, it is solidified, polymerized, After curing, it has good strength and special functionality.
At present, almost all general-purpose plastics can be applied to 3D printing, but due to the differences in the characteristics of each plastic, the 3D printing process and product performance are affected.
At present, the main factors affecting the application of plastic materials in 3D printing are: high printing temperature, poor material fluidity, resulting in volatile components in the working environment, easy blockage of the printing nozzle, affecting product precision; ordinary plastics have low strength and too narrow adaptation range , The plastic needs to be reinforced; the cooling uniformity is poor, the shaping is slow, and it is easy to cause shrinkage and deformation of the product; the lack of functional and intelligent applications.
The key to the 3D printing industry is materials. As the most mature material for 3D printing, plastic materials still have many problems: affected by the strength of plastics, plastic materials have limited application fields, and the physical and mechanical properties of the finished product are poor; high temperature processing and low temperature are required. Poor fluidity, slow curing, easy deformation, low precision; lack of expansion of plastics in the field of new materials.
For this reason, the development of 3D printing plastic modification technology currently mainly has the following four directions.
1. Modification of fluidity
In order to realize the flow modification of plastics, reference can be made to the modification with lubricants. However, the use of too much lubricant will increase the volatile content and weaken the rigidity and strength of the product. Therefore, by adding high-rigidity, high-fluidity spherical barium sulfate, glass beads and other inorganic materials to make up for the defect of poor fluidity of plastics . For powder plastics, the powder surface can be coated with flake inorganic powder such as talc powder and mica powder to increase fluidity. In addition, microspheres can be directly formed during plastic synthesis to ensure fluidity.
2. Enhanced modification
By enhancing the modification, the rigidity and strength of the plastic can be improved. For example, glass fiber, metal fiber, and wood fiber reinforced ABS make composite materials suitable for 3D fused deposition process; powdered plastics are usually laser sintered, and can be reinforced and modified by combining a variety of materials, including nylon powder with glass fiber, and Carbon fiber nylon powder, nylon and polyether ketone mixture, etc.
3. Fast solidification
The solidification time of plastics is closely related to crystallinity. In order to accelerate the rapid solidification and formation of plastics after 3D fusion deposition, reasonable nucleating agents can be used to speed up the shaping and solidification of the plastic, and metals with different heat capacities can also be compounded in the plastic material to speed up the solidification.
Through functional modification, the application range of plastics in the field of 3D printing manufacturing can be expanded.