plastic mold

Plastic mold refers to a combined plastic mold used for compression molding, extrusion molding, injection molding, blow molding, and low-foaming molding.

It mainly consists of a concave mold assembly base plate, concave mold components, and a concave mold assembly clamping plate, which form a variable cavity. The convex mold consists of a convex mold assembly base plate, convex mold components, convex mold assembly clamping plate, cavity truncation components, and side truncation assembly plate, which form a variable core. The coordination and changes of the mold's convex and concave molds, as well as the auxiliary molding system, enable the processing of a series of plastic parts with different shapes and sizes. To improve the properties of plastics, various auxiliary materials such as fillers, plasticizers, lubricants, stabilizers, and colorants are added to the polymer to make it a well-performing plastic.

1. Synthetic resin is the main component of plastics, and its content in plastics is generally between 40% and 100%. Due to its large content and the fact that the properties of the resin often determine the properties of the plastic, people often regard resin as a synonym for plastic. For example, polyvinyl chloride resin is confused with polyvinyl chloride plastic, and phenolic resin is confused with phenolic plastic. 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 serves as a raw material for coatings, adhesives, and synthetic fibers. Except for a very small portion of plastics that contain 100% resin, most plastics require the addition of other substances besides the main component resin.

2. Fillers, also known as fillers, can improve the strength and heat resistance of plastics and reduce costs. For example, adding wood powder to phenolic resin can greatly reduce costs, making phenolic plastic one of the cheapest plastics while significantly improving mechanical strength. Fillers can be divided into organic fillers and inorganic fillers. The former includes wood powder, rags, paper, and various textile fibers, while the latter includes glass fiber, diatomaceous earth, asbestos, carbon black, etc.

3. Plasticizers can increase the plasticity and softness of plastics, reduce brittleness, and make plastics easier to process and mold. Plasticizers are generally high-boiling-point organic compounds that are miscible with resins, non-toxic, odorless, and stable to light and heat. The most commonly used plasticizers are phthalates. For example, when producing polyvinyl chloride (PVC) plastic, adding more plasticizers can produce soft PVC plastic, while adding less or no plasticizers (less than 10%) can produce hard PVC plastic.

4. Stabilizers To prevent the decomposition and damage of synthetic resins during processing and use due to exposure to light and heat, stabilizers are added to plastics to extend their service life. Commonly used stabilizers include stearates and epoxy resins.

5. Colorants Colorants can give plastics various bright and beautiful colors. Organic dyes and inorganic pigments are commonly used as colorants.

6. Lubricants The function of lubricants is to prevent plastics from sticking to metal molds during molding and to make the surface of plastics smooth and beautiful. Commonly used lubricants include stearic acid and its calcium and magnesium salts. In addition to the above additives, flame retardants, foaming agents, antistatic agents, etc. can also be added to plastics.