Plastic molds mainly consist of a cavity mold, which includes a mold base plate, mold components, and a mold assembly card, featuring a variable cavity. The core mold, on the other hand, is composed of a core mold base plate, core mold components, core mold assembly card, cavity sectioning components, and side section assembly board, offering a variable core design.
To enhance the performance of plastics, various auxiliary materials such as fillers, plasticizers, lubricants, stabilizers, and colorants need to be added to polymers, thereby creating high-performance plastics.
1. Synthetic resins are the primary component of plastics, typically accounting for 40% to 100% of their composition. Due to their high content and the fact that the properties of resins often determine those of plastics, resins are often considered synonymous with plastics. For instance, polyvinyl chloride resin is often confused with polyvinyl chloride plastic, and phenolic resin with phenolic plastic. However, resins and plastics are distinct concepts. Resins are raw, unprocessed polymers, used not only in the production of plastics but also as raw materials for paints, adhesives, and synthetic fibers. Most plastics, however, require the addition of other substances, with only a small percentage containing 100% resin.
2. Filler, also known as a filling agent, enhances the strength and heat resistance of plastics while reducing costs. For instance, adding wood powder to phenolic resin can significantly lower costs, making phenolic plastics one of the more affordable options. It also notably improves mechanical strength. Fillers are categorized into organic and inorganic types, with organic ones including wood powder, rags, paper, and various textile fibers, and inorganic ones such as glass fibers, diatomite, asbestos, and carbon black.
3. Plasticizers enhance the plasticity and flexibility of plastics, reduce brittleness, and make plastics more easily processable for shaping. Plasticizers are typically compatible with resins, non-toxic, odorless, and high-boiling-point organic compounds that are stable to light and heat; phthalates are commonly used. For instance, when producing polyvinyl chloride (PVC) plastics, adding a significant amount of plasticizer results in soft PVC, whereas omitting or adding a small amount (less than 10%) yields rigid PVC.
4. To prevent the decomposition and damage of synthetic resins due to the effects of light and heat during processing and use, extend their service life, stabilizers must be added to the plastic. Common stabilizers include stearates and epoxies.
5. Colorants are used to impart a variety of bright and attractive colors to plastics. Organic dyes and inorganic pigments are commonly employed as colorants.
6. The role of lubricants is to prevent plastic from sticking to metal molds during molding, while also ensuring a smooth and aesthetically pleasing surface for the plastic. Common 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 the plastic.
