Internal Release Agent

Internal Release Agent

Internal release agents are polymer processing aids added internally to polymer material systems. Their primary function is to reduce the adhesion of molded products to the mold cavity walls, facilitating demolding, thereby improving product yield and production efficiency‌1. Internal release agents are typically incorporated into the compound through mixing in the form of additives and dispersed within. During vulcanization, they partially migrate to the surface, forming a thin barrier film, eliminating the need to apply release agents individually to the mold cavity surface.

Chemical Composition and Mechanism of Action

Internal release agents commonly include components such as phosphate esters, lecithin, stearates, and triethanolamine oleate. For example, zinc stearate is a widely used internal release agent that has no significant impact on the color, curing speed, or resin viscosity of the product‌3. Internal release agents are compatible with liquid resins but incompatible with cured resins. Under specific processing temperatures, they exude from the resin matrix and diffuse to the surface of the cured product, forming a barrier film.

Application Scenarios and Effects

Internal release agents are widely used in plastic processing, particularly in injection molding, extrusion, blow molding, and other processes. They facilitate the smooth release of plastic products from molds, reduce mold damage, extend mold service life, and ensure products are smooth, dimensionally compliant, and reduce waste. Additionally, internal release agents play a crucial role in the pultrusion process of fiberglass-reinforced plastics. By adding internal release agents to the resin, a barrier film is formed, ensuring smooth demolding, maintaining product surface quality, and preserving the integrity of the mold.

Industry Status and Development Trends

Currently, the domestic release agent market suffers from an unreasonable product structure, with slow development of high-end release agent products. Communication channels between R&D and production units and end-users are insufficient, making it challenging to promote and adopt new, highly efficient release agents‌. In the future, with the development of the plastic and rubber industries, the demand for environmentally friendly and high-performance release agents will further increase, driving the industry toward higher-end and more efficient development.