Polyurethane in mold paint can improve the wear resistance of polyurethane foam materials, surface defects caused by foaming processes, reproduce mold patterns and colors, and enhance the expressiveness of product appearance. During the molding process of polyurethane foam plastic products, the mold materials used are generally high thermal conductivity materials, such as aluminum, steel, etc., which have bonding properties with polyurethane mold interior paint and will have strong bonding with metal, thus affecting the bonding of polyurethane mold interior paint and polyurethane foam parts. Therefore, appropriate release agents need to be used to prevent the bonding of polyurethane and mold.
Release agent is a functional substance between the mold and the finished product, which can prevent elastic materials such as rubber, plastic, and other materials from sticking to the surface of the mold and play an auxiliary role in demolding as a processing aid. In order to weaken the adsorption or bonding between the plastic products and the mold, release agents that can form an effective isolation film are used to form an interface facial mask layer on the surface of two objects that are easy to adhere. These release agents form a micron thick, thermally stable film layer, which forms a chemical connection with the mold surface, so as to form an isolation between the adhesive and the adherent, thus weakening the peel force, and enabling the formed parts to fall off quickly and easily.
Economy and demolding effect are important factors that cannot be ignored in the selection of release agents. Poor quality water-based release agents can cause cracks and wrinkles on the surface of the product, affecting the appearance of the product and the service life of the mold, and causing environmental pollution. At the same time, the price of release agents is also an important aspect that users must consider. From the perspective of demolding performance, an ideal demoulding agent should have the following characteristics:
1. Demoulding ability, forming uniform thin films and complex shaped molded products with precise and error free dimensions;
2. Good demolding continuity;
3. The surface of the molded product is smooth and does not adhere to dust caused by the application of release agents;
4. Stable chemical performance, no chemical reaction with molded products;
5. The secondary processing performance is superior, and when the release agent is transferred to the molded product, it has no adverse effects on the processing products such as electroplating, printing, coating, and bonding;
6. Non corrosive molds, non polluting parts, low odor and toxicity.
At present, there are three main types of commonly used external release agents: inorganic release agents (mica, clay, fluorine, talc powder, etc.), organic release agents (natural wax, fatty acid, fatty acid soap, synthetic wax, etc.), and polymer release agents (organosilicon, polyvinyl alcohol, cellulose acetate, etc.). The latter two types are mainly used in polyurethane release agents.
