Release Agent Film-Forming Materials and Functional Introduction​

# 1. Mechanisms of Release Agents: Boundary Layer Formation and Lubrication

# 1.1 Boundary Layer Formation

The release coating must possess sufficient mechanical strength and chemical inertness to prevent mold materials from penetrating into or adhering to the mold surface under high temperature and pressure. The film’s thickness, uniformity, and integrity are the foundations of demolding efficiency.

# 1.2 Lubrication and Low Surface Energy

High-performance release agents exhibit ultra-low surface energy to effectively resist wetting by the molding compound. For example, silicone-based materials (Si–O backbone) and fluoropolymer systems (C–F bonds) provide very low friction coefficients and surface energies, enabling smooth, “slippery” release.

# 2. Film-Forming Materials

The performance and service temperature of a release agent are dictated by its core film-forming materials. Mainstream chemical systems include silicone, wax, fluoropolymer, and emerging non-silicone high-performance synthetic polymers. This article focuses on external release agents to detail the functions of different film formers.

# 2.1 Silicone-based release agents

Primary film formers include silicone oils and silicone resins. They offer long demolding life and high surface finish. Their key advantage lies in the superior high-temperature resistance and excellent release performance conferred by the Si–O framework, making them the first choice for high-temperature molding. Experimental data indicate a surface energy of 15–25 mN/m and a decomposition temperature of >200–350°C. Typical applications include automotive tires, electronic encapsulation and medical devices. However, high transferability remains the primary pain point. Residual silicone on molded parts forms a chemically inert barrier layer that can hinder subsequent secondary processing such as painting, bonding, or coating, increasing defect rates.

# 2.2 Wax-based release agents

Primary film formers include paraffin and polyethylene wax. Their main advantages are low cost, good lubricity, and generally better compatibility with post-processing than traditional silicone products. Common applications include rubber products, plastic films, and ceramic molding. However, conventional wax systems have inherent drawbacks: relatively low mechanical strength, easy loss during continuous molding, frequent reapplication, and consequent increases in mold cleaning and downtime. To address this, modern technology has moved toward functional composites. Research shows that modifying high-strength nano-silica with fluorocarbon resins can significantly mitigate wax-based agents’ susceptibility to premature failure and migration while maintaining low production cost.

# 2.3 Fluoropolymer-based release agents

Primary film formers include polytetrafluoroethylene (PTFE) and various fluorocarbon resins, noted for their ultra-low surface energy and chemical resistance. They are especially suitable for composite molding that demands high surface precision, multiple releases, or elevated temperatures, such as semiconductor encapsulation, optical lenses, and aerospace components. Fluoropolymers are often used to prepare dry-film or semi-permanent release coatings. Once the carrier volatilizes, a robust solid film forms on the mold surface, ensuring low- or zero-transfer release during demolding—a key route to resolving post-processing compatibility. Their main limitation is higher cost.

# 2.4 Water-based release agents

Primary film formers include silicone derivatives or base oils. These agents use water as the carrier, feature near-zero VOC emissions (compliant with EU REACH and RoHS), form a uniform 30–50 μm thin film after spraying, and exhibit a typical surface energy of 25–35 mN/m. For silicone-oil-based systems, the decomposition temperature range is 150–280°C. Residue impact on the adhesion of subsequent spray coatings is typically $\leq$5%. Common applications include plastic molding, concrete construction, and rubber products. Water-based release agents are the most well-balanced option overall, performing strongly in cost efficiency, overall release effect, and environmental compliance. (Table 1)

# TABLE 1

Type	Core Film-forming Material	Main Functions/Features	Typical Application Fields
Silicone Release Agent	Silicone Oil, Silicone Resin	High-temperature resistant, long release life, high surface finish, but requires secondary cleaning	Car tires, electronic packaging, medical devices
Fluorine Release Agent	Polytetrafluoroethylene (PTFE)	Extremely low surface energy, chemical corrosion resistant, suitable for high-precision anti-sticking requirements, higher cost	Semiconductor packaging, optical lenses, aerospace
Wax-based Release Agent	Paraffin Wax, Polyethylene Wax	Low cost, good lubrication, but easily contaminates molds, requires frequent reapplication	Rubber products, plastic films, ceramic molding
Water-based Release Agent	Silicone Oil Derivatives or Base Oil	Environmentally friendly, non-toxic, no VOCs emissions, high comprehensive quality	Plastic molding, concrete engineering, rubber products

# 3. Future Process Directions

As process technology advances, both the functions and manufacturing processes of release agents continue to evolve. Technological breakthroughs are addressing common industrial pain points. For example, to mitigate residue interference, developing nano-silica-modified silicone oils reduces residual particle size to <50 nm, improving surface compatibility. To address low-temperature winter application challenges, when the substrate temperature is <10°C, slow water evaporation can lead to a film cracking incidence of about 20%; adding propylene glycol as an antifreeze, combined with low-VOC coalescing agents (e.g., butyl glycol), extends usability down to -5°C. Future iterations of release agent technology will bring even greater convenience to production.