The structure of plastic molds mainly includes a cavity mold with a variable cavity, composed of a cavity mold base plate, cavity mold components, and a cavity mold combination plate; and a core mold with a variable core, composed of a core mold base plate, core mold components, core mold combination plate, cavity cut-off components, and side cut-off combination plates.
To improve the performance of plastics, various auxiliary materials, such as fillers, plasticizers, lubricants, stabilizers, and colorants, are added to the polymer to create high-performance plastics.
1. Synthetic resin is the main component of plastic, and its content in plastic is generally 40% to 100%. Due to its high content, and because the properties of the resin often determine the properties of the plastic, people often consider resin and plastic to be synonymous. For example, polyvinyl chloride resin and polyvinyl chloride plastic, and phenolic resin and phenolic plastic are often confused. In fact, resin and plastic are two different concepts. Resin is an unprocessed raw polymer, which is not only used to manufacture plastics, but also as a raw material for coatings, adhesives, and synthetic fibers. Except for a very small number of plastics containing 100% resin, most plastics require the addition of other substances besides the main component resin.
2. Fillers, also called fillers, can improve the strength and heat resistance of plastics and reduce costs. For example, adding wood flour to phenolic resin can greatly reduce costs, making phenolic plastic one of the inexpensive plastics, while also significantly improving mechanical strength. Fillers can be divided into two categories: organic fillers and inorganic fillers. The former includes wood flour, shredded cloth, paper, and various textile fibers, while
the latter includes glass fiber, diatomaceous earth, asbestos, and carbon black.
3. Plasticizers increase the plasticity and flexibility of plastics, reduce brittleness, and make plastics easier to process and mold. Plasticizers are generally high-boiling point organic compounds that are miscible with the resin, non-toxic, odorless, and stable to light and heat. Phthalate esters are commonly used. For example, when producing polyvinyl chloride (PVC) plastic, adding a larger amount of plasticizer results in soft PVC plastic, while adding little or no plasticizer (less than 10%) results in rigid PVC plastic.
4. Stabilizers: To prevent synthetic resins from decomposing and degrading due to light and heat during processing and use, and to extend their service life, stabilizers are added to plastics. Commonly used stabilizers include stearates and epoxy resins.
5. Colorants: Colorants give plastics various bright and attractive colors. Organic dyes and inorganic pigments are commonly used as colorants.
6. Lubricants: Lubricants prevent plastics from sticking to metal molds during molding and also make the surface of the plastic smooth and aesthetically pleasing. Commonly used lubricants include stearic acid and its calcium and magnesium salts. In addition to the above additives, flame retardants, foaming agents, and antistatic agents can also be added to plastics.
