Application of Silicone Release Coating in Baking Paper:

Synergistic Advancements in Technology and Food Safety

Baking paper, a crucial consumable in modern baking operations, derives its functionality from anti-stick properties and high-temperature resistance, both of which are significantly affected by the silicone release coating. Utilizing their distinctive chemical structures and technological advantages, silicone release coatings have become the predominant solution for coating baking paper. This article delves into their application value across three dimensions: technological principles, process innovation, and market trends.

The primary component of silicone release coating is reactive silicone polymers, whose molecular chains feature Si-O-Si bonds with significantly higher bond energy than traditional carbon-chain polymers. This characteristic bestows exceptional thermal stability and chemical resistance. In baking paper coatings, silicone release coatings function through the following mechanisms:

Low Surface Energy: With a critical surface tension of 19–24 dyn/cm (substantially lower than that of grease, which is approximately 30 dyn/cm), they minimize the adhesion of high-sugar or high-fat doughs, ensuring automatic separation between food and paper during baking.

Thermal Resistance: Capable of withstanding temperatures ranging from −55°C to 300°C, they maintain stability at 220°C for 20 minutes without decomposing, meeting the demands of cake, bread, and pastry baking.

Controllable Release Force: Adjustable through crosslinking density and molecular weight, the release force can be tailored to 5–500 g/25mm, accommodating applications from delicate cookies to thick layer cakes.

Chemical Inertness: Non-reactive with food components, they meet food safety standards (e.g., FDA, EU 10/2011).

Physical Barrier: They create a uniform hydrophobic layer on paper surfaces, which reduces direct food contact.

Durability: After the curing process, coatings exhibit stability and reusability. (e.g., silicone baking mats).

The evolution of baking paper coating processes mirrors technological advancements in silicone release coatings:

Solvent-Based Coatings (Phase-Out Stage)

Characteristics: Use organic solvents (e.g., toluene, acetone, gasoline) to dilute silicone oil, followed by high-temperature curing post-application.

Applications: Suitable for high-grammage baking paper with strong anti-stick properties, their VOC emissions and solvent residues, however, conflict with modern environmental regulations, prompting the need for replacement by eco-friendly alternatives.

Solventless Coatings (Mainstream Process)

Characteristics: 100% solids content with no VOCs, cured via platinum catalysis, yet necessitating advanced multi-roll precision coating equipment, which increases production costs.

Applications: The preferred choice for modern baking paper, in compliance with food-contact material regulations (e.g., FDA 21 CFR 175.300).

Emulsion-Based Coatings (Future Direction)

Characteristics: Water-dispersed formulations, such as Wacker's DEHESIVE® EM 490 CN (Topwin’s Siemtcoat®EM5502) emulsion with 45% solids, facilitate low-temperature curing at approximately 120–150°C. This supports various coating methods, including roll and gravure, to achieve zero-solvent-residue, high-efficiency production.

Applications: Ideal for low-temperature baking scenarios, such as cookies or chocolate liners.

Learning More: Application Processes for Silicone Release Coatings in Baking Paper

Substrate Selection

Base Paper: Food-grade kraft or glassine paper must be able to withstand high temperatures, exhibit high strength, and be free from fluorescent whitening agents.

Pre-treatment: Surface cleaning to remove dust or grease improves the adhesion of silicone release coatings.

Coating Methods

Dip Coating: Immersion in silicone emulsion for uniform thin coatings.

Spray Coating: Precise control of coating weight for high-grammage papers.

Knife Coating: Ideal for high-viscosity silicones, ensuring uniform coatings.

Curing Processes

Thermal Curing: Baking at 120–150°C to crosslink silicone layers (e.g., platinum-catalyzed addition curing).

Electron Beam (EB) Curing: Solvent-free and eco-friendly (at a higher cost).

III. Food Safety: Comprehensive Safeguards from Raw Materials to Regulations

As a direct food-contact material, baking paper must undergo rigorous safety validation:

Substrate Selection: Specialty papers made from virgin wood or bamboo pulp must undergo immersion tests (no disintegration in water for 24 hours) to prevent heavy metal migration.

Coating Certification: Compliance with the GB 9685-2016 Standard for Additives in Food Contact Materials prohibits carcinogens such as PFAS, prioritizing FDA and BfR certified food-grade silicones.

Migration Testing: Under simulated baking conditions (220°C/20 min), the migration of silicone oil must remain below 0.01 mg/dm² to ensure there are no toxic residues.

UV Curing Technology: Companies such as Evonik (Germany) and Bluestar (China) have developed UV-curable silicone release coatings that cure in seconds, reducing energy consumption by 70% and allowing compatibility with low-heat-resistance substrates such as polypropylene (PP) and polyethylene (PE).

Nano-Modified Coatings:By incorporating nano-silica, the coating's abrasion resistance was enhanced, allowing it to withstand 100,000 friction cycles without damage and ensuring a release force attenuation rate of less than 5%;

Waterborne Silicone Popularization:Elkem SILCOLEASE™ 902 series (Topwin’s Siemtcoat® EM5502), a water-based emulsion silicone release coating, enhances curing speed by 30% and adheres to the FSC forest certification, thereby promoting the development of green packaging.

Silicone release coatings are expanding their scope:

Microwave-Heating Coatings: Develop silicone release coatings that are resistant to microwave radiation at 120°C, suitable for the packaging of instant pizzas and frozen desserts;

Composite Packaging Materials: When combined with aluminum foil and PET, they create multi-layer structures that are oil and moisture-resistant and easy to peel, thereby extending the shelf life of food.

Smart Labels: Thermochromic coatings on baking paper aid in temperature sensing and traceability. For example, thermochromic silicone-coated paper offers a visual indication of when baking is complete.

Conclusion

The application of silicone release coatings in the baking paper industry exemplifies the deep integration of materials science with the food industry. As environmental regulations become increasingly stringent and consumption continues to evolve, water-based, nano, and functional technologies are set to become mainstream.In the future, silicone release coatings, balancing production efficiency and food safety, will continue to drive the baking industry towards greener and more intelligent innovation.