Comprehensive analysis of 3D printed materials

3D printing is a technology for manufacturing three-dimensional products by adding materials layer by layer through a 3D printing device according to the designed 3D model. This layer-by-layer stacking forming technique is also called additive manufacturing. 3D printing integrates cutting-edge technologies in many fields such as digital modeling technology, electromechanical control technology, information technology, materials science and chemistry. It is a kind of rapid prototyping technology and is known as the core technology of the "third industrial revolution."

3D printing manufacturing technology is mainly composed of 3 key elements:

First, the product needs accurate three-dimensional design, using computer-aided design (CAD) tools to accurately position the product in all directions;

The second is the need for powerful molding equipment;

The third is the materials that need to meet product performance and molding processes.

As 3D printing manufacturing technology completely changes the traditional manufacturing industry's methods and principles, it is a subversion of traditional manufacturing models. Therefore, 3D printing materials have become the main bottleneck that restricts the development of 3D printing. It is also the key and difficult point of 3D printing breakthrough innovation. Only by developing more new materials can we expand the application field of 3D printing technology. At present, 3D printing materials mainly include polymer materials, metal materials, ceramic materials and composite materials.

1.Engineering plastics

Engineering plastics refer to industrial plastics used as industrial parts or housing materials. They are plastics with excellent strength, impact resistance, heat resistance, hardness and aging resistance. Engineering plastics are currently the most widely used type of 3D printing materials. Common examples include acrylonitrile-butadiene-styrene copolymer (ABS), polyamide (PA), polycarbonate (PC), and polyphenylsulfone (PPSF). ), Polyetheretherketone (PEEK), etc.

1) ABS

ABS material is the first choice engineering plastic for 3D printing through fusion deposition due to its good hot melt and impact strength. At present, ABS is mainly used in the form of pre-made silk and powder, and the application scope covers almost all daily necessities, engineering supplies and some mechanical supplies. In recent years, ABS has not only gradually expanded in the application field, but also continuously improved its performance. With the strong adhesion and strength of ABS, ABS has been modified to make it a wider range of applications as a 3D printing material.

In 2014, the International Space Station used ABS plastic 3D printers to print its parts; the latest ABS material ABS-M30, developed by Stratasys, the world's largest 3D printer material company, is designed for 3D printing manufacturing, and its mechanical properties are 67% higher than traditional ABS materials. %, Thus expanding the scope of application of ABS.

2) PA

PA is high in strength and flexible at the same time, so 3D printing can be used directly to manufacture equipment parts. PA carbon fiber composite plastic resin parts manufactured by 3D printing have high strength and toughness, and can be used for mechanical tools instead of metal tools. In addition, due to the adhesiveness and powder characteristics of PA, it can be mixed with ceramic powder, glass powder, metal powder, etc., and low-temperature 3D printing of ceramic powder, glass powder, and metal powder can be achieved by bonding. Solvay, as a global expert in PA engineering plastics, performs 3D printed prototypes based on PA engineering plastics for engine peripheral parts, door handle kits, brake pedals, etc. Replacing traditional metal materials with engineering plastics finally solves the problem of lightweight vehicles.

3) PC

PC has excellent strength, its strength is about 60% higher than ABS material, so it is suitable for the application of super-strength engineering products. Solvay, as a global expert in PA engineering plastics, performs 3D printed prototypes based on PA engineering plastics for engine peripheral parts, door handle kits, brake pedals, etc. PC2605 developed by Bayer, Germany can be used for 3D printing and manufacturing of special-shaped components such as bullet-proof glass, resin lenses, headlight covers, astronaut helmet masks, smartphone bodies, mechanical gears, and other special components.

4) PPFS

PPSF has the highest heat resistance, toughness and chemical resistance. It has the best performance among various rapid-prototyping engineering plastic materials. Through the composite treatment of carbon fiber and graphite, PPSF shows extremely high strength and can be used for 3D printing. Manufacture of high load-bearing products has become the material of choice for replacing metals and ceramics.

5) PEEK

PEEK has the advantages of excellent abrasion resistance, biocompatibility, chemical stability, and Young's modulus closest to human bones. It is an ideal artificial bone replacement material, suitable for long-term implantation into the human body. The 3D printing technology based on the principle of fused deposition molding is safe and convenient, does not require the use of a laser, and has simple post-processing. The bionic artificial bone is manufactured by combining with PEEK material.

6) EP

EP (Elasto Plastic) is elastic plastic, which is a 3D printing raw material newly developed by Shapeways. It can avoid the brittleness problem of wearable items or deformable products printed with ABS. As the name suggests, Elasto Plastic is a new type of soft 3D printing material. It uses the same principle of "sintering layer by layer" as ABS, but the printed product has quite good elasticity and is easy to recover from deformation. This material can be used to make products like 3D printed shoes, phone cases and 3D printed clothing.

7) Endur

Stratasys has introduced a new 3D printing material, Endur, which is an advanced imitation polypropylene material that can meet the application needs of various fields. Endur material has high strength, good flexibility and high temperature resistance. The surface quality of products printed with it is good, and the dimensional stability is good, and it is not easy to shrink. Endur has excellent polypropylene-like properties and can be used to print moving parts, bite-engagement parts, and small boxes and containers.

2.Bioplastics

3D printed bioplastics mainly include polylactic acid (PLA), polyethylene terephthalate-1,4-cyclohexanedimethanol (PETG), poly-hydroxybutyrate (PHB), poly-hydroxypentyl Acid ester (PHBV), polysuccinate-butanediol (PBS), polycaprolactone (PCL), etc., have good biodegradability.

1) PLA

PLA (Poly Lactic Acid), or polylactic acid, is probably the best raw material for 3D printing at first, and it has a variety of translucent colors and glossy textures. As an environmentally friendly plastic, polylactic acid can be biodegraded into active compost. It is derived from renewable resources-corn starch and sugar cane, rather than non-renewable resources-fossil fuels. Tan KH and others at Nanyang Technological University in Singapore used PLA to manufacture tissue engineering scaffolds. They used 3D technology to mold biodegradable polymer materials to produce high-porosity PLA tissue engineering scaffolds. Tissue analysis was performed on the scaffolds. And found that it has the ability to grow.

2) PETG

PETG is a bio-based plastic synthesized from bio-based ethylene glycol produced from sugar cane ethylene. It has outstanding thermoformability, toughness and weather resistance, short thermoforming cycle, low temperature and high yield. As a new type of 3D printing material, PETG has the advantages of both PLA and ABS. In 3D printing, the shrinkage of the material is very small, and it has good hydrophobicity, so it does not need to be stored in a closed space. Due to the low shrinkage and low temperature of PETG, there is almost no odor during the printing process, which makes PETG products have a wider prospect for development and application in the field of 3D printing.

3) PCL

PCL is a biodegradable polyester with a low melting point, only around 60 ° C. Like most biological materials, it is often used for special purposes such as drug delivery devices, sutures, etc. At the same time, PCL has shape memory. In 3D printing, because it has a low melting point, it does not require a high printing temperature, thereby achieving the purpose of energy saving. In the medical field, it can be used to print heart stents, etc.

3. Thermoset plastic

Thermosetting resins such as epoxy resins, unsaturated polyesters, phenolic resins, amino resins, polyurethane resins, silicone resins, aromatic heterocyclic resins, etc. have high strength and fire resistance characteristics, which are very suitable for 3D printed powder laser sintering molding processes. Materials scientists at the Harvard School of Engineering and Applied Sciences and the Wyss Institute of Bioengineering have jointly developed a 3D-printable epoxy-based thermosetting resin material. This epoxy resin can be 3D-printed into building structures and used in lightweight buildings. .

4.Photosensitive resin

Photosensitive resin is composed of polymer monomer and prepolymer. Due to its good liquid flow and instant photo-curing characteristics, liquid photosensitive resin is the first choice for 3D printing consumables for high-precision product printing. The photosensitive resin has a fast curing speed, excellent surface drying performance, and the appearance of the product after molding is smooth, and it can be transparent to translucent matte. In particular, photosensitive resins have low odor and low irritant components, which is very suitable for personal desktop 3D printing systems.

5.Polymer gel

Polymer gel has good intelligence. Polymer gel materials such as sodium alginate, cellulose, animal and plant glue, peptone, polyacrylic acid are used for 3D printing. Under a certain temperature and the role of initiator and cross-linking agent After polymerization, a special network polymer gel product is formed. For example, when subject to changes in ionic strength, temperature, electric field, and chemicals, the volume of the gel will change accordingly. It is used for shape memory materials; the gel undergoes a volume change when it swells or contracts; Controllability can be used for smart drug release materials.