UV Cured 3D Printing Materials: Differences between Water Wash Resin and Ordinary Resin
Resin 3D printing is not a simple process, unlike common FDM 3D printing technology, which often requires a large number of post-processing steps to obtain the true printed product. Generally speaking, to clean resin 3D printing components, isopropanol (IPA) with a concentration of 90% or higher is usually required. However, IPA at this concentration can incur high costs. To address this issue, material engineers have developed a water wash resin, which is a new and special type of resin that can be effectively cleaned using water as a solvent without the need to handle large amounts of IPA or other solvents.
What are washed resins and how do they compare to standard resins? Resins may vary greatly depending on brand:
Standard resin is any 3D printing resin that does not have any special properties (i.e. flexible, biomedical, or castable) and needs to be cleaned in isopropanol or other organic solvents after printing. These are the most commonly used 3D printing resins in the desktop 3D printing market today, and almost every 3D printing resin supplier sells standard resins.
Washing resin is a relatively new innovation, where users only need to immerse the resin printing components in water or low concentration IPA to remove excess resin. This resin was invented in 2016, but has since been widely used for desktop resin 3D printing.
The most significant difference between the two lies in the type of solvent required for post-processing of printed products, while other differences also manifest in the characteristics of the finished components.
The resin formulations of different resin manufacturers may vary greatly, even for the same type of resin. Therefore, it is difficult to make a statement about the general differences in material properties between washed resins and standard resins. However, this does not mean that the material properties of the resin are the same. In the same brand, water washed resin and standard resin will have different properties due to different chemical compositions, which may affect tensile strength, Flexural modulus and available colors. For example, the standard and washed resin of Anyubic have tensile strengths of 36-45 and 30-45 MPa, respectively. Anycubic's water washed resin has a higher range of Flexural modulus than standard resin and is harder.
The printing method of washable resin and standard resin may be identical, and standard resin and washable resin may have similar layer curing times for the same model of 3D printer. As mentioned above, the biggest difference lies in the cleaning process that occurs after the printed piece is removed from the printing board of the 3D printer. Depending on the brand, washable resin 3D prints can be immersed in a 0-10% IPA aqueous solution. Some brands of resin only require a little IPA, while other brands of resin are truly washable and can remove residual liquid resin without the need for IPA. For standard resins, the post-treatment solvent contains 90-99.9% isopropanol. Regardless of the type of resin, the cleaning time is specified by the manufacturer.
Regarding solvent treatment, it should be noted that clean water containing uncured resin cannot be poured into the sewer! It must be treated like a used IPA, placed in sunlight, waiting for it to evaporate and leave residual resin, and then discarded. Another method is to dispose of contaminated water in accordance with local regulations regarding hazardous waste in the region.
Water washed resins are usually slightly more expensive than standard resins produced by the same resin manufacturer. In addition, the color of washable resins is usually different from standard resins, sometimes even less. For example, Sunlu's standard resin price is approximately $27 per kilogram, with eight colors to choose from; The price of washable resin is about $31, and there are only 5 colors available for selection. There is also Anyubic's product, whose standard resin is priced at about $20 and comes in seven colors to choose from, while their washed resin is priced at $34 and only has six colors to choose from.
Washable resin will avoid the hassle of purchasing, damaging, and handling more expensive organic solvents. If you are an enthusiast, washable resin is definitely a very useful material, and you can use your home faucet to rinse printed products. However, washable components are highly susceptible to moisture and water damage, which requires special attention.
In addition, a major drawback of both washed resin and standard resin is that they are both very brittle, while washed resin is slightly more brittle than standard resin. When the applied stress exceeds the yield stress of the cured resin, the component will rupture like glass. There is also a risk of residual resin in hollow printed products, which can lead to cracks during the post curing process.
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