Differences in the Effects of Infrared Radiation Heating and Hot Air Circulation Heating Curing Methods on the Uniformity of Cross-Linked Structure of Organosilicon Adhesive Layers

Heat Transfer Mechanism and Application Differences of Teflon Cloth in Curing Process

I. Heat Transfer Mechanism and Temperature Field Differences of Teflon Cloth

1. Hot Air Circulation Heating

Relying on thermal convection and thermal conduction, heat transfers gradually from the surface to the interior. This heating method features gentle temperature rise, a small temperature difference inside and outside the adhesive layer, and uniform temperature distribution.

2. Infrared Radiation Heating

Infrared energy has a limited penetration depth and is strongly absorbed by the surface layer at a depth of tens to hundreds of micrometers, resulting in instantaneous high temperature on the material surface. The interior can only be heated through slow thermal conduction, forming a steep temperature gradient with high surface temperature and low internal temperature.

II. Core Influence of Teflon Cloth on the Uniformity of Cross-linked Structure

1. Cross-linking Density Distribution: Uniform for Hot Air Heating, Gradient for Infrared Heating

Hot air heating enables basically synchronous curing reactions inside and outside the adhesive layer, allowing the cross-linked network to grow uniformly with consistent overall density. Under infrared heating, the surface layer undergoes rapid cross-linking to form a dense "skin film". This film not only hinders inward heat conduction but also restricts the movement of internal molecular chains, resulting in a decreasing cross-linking density from the surface to the interior and forming a gradient structure with higher density on the outside and lower density on the inside.

2. Curing Process and Skin Film Effect: Infrared Heating Prone to Defects

The curing process of hot air heating is coordinated. By-products of condensation reactions such as alcohol and water can escape fully from the interior of the adhesive layer, forming a dense adhesive layer with few defects. In contrast, the surface layer is instantly cured and film-formed during infrared heating. If vaporized internal by-products break through the surface skin, pinholes and bubbles will be left; if not, a weak interface layer will be formed, which seriously damages the structural uniformity and bonding strength of the adhesive layer.

3. Integrity of Microscopic Network Structure: Infrared Heating May Introduce Internal Stress

Molecular chains have sufficient relaxation time during hot air heating, forming a complete cross-linked network with low residual internal stress. For infrared heating, the surface layer is shaped first. When the internal material shrinks during subsequent curing, it is constrained by the rigid outer layer, generating significant residual internal stress. This leads to warping of the adhesive layer, reduced bonding performance and uneven mechanical properties.

III. Key Performance Differences of Teflon Adhesive Tape

Hot Air Circulation Heating: Uniform temperature field, consistent cross-linking density, few structural defects and low internal stress, forming an integral and uniform cross-linked network.

Infrared Radiation Heating: Large temperature gradient, cross-linking density decreasing from surface to interior, prone to defects such as bubbles and pinholes, high internal stress, presenting a "hard shell and soft core" structural characteristic. The above differences essentially stem from the different heat transfer mechanisms of the two heating methods.

IV. Application Selection and Suggestions for Teflon Adhesive Tape

For scenarios with strict uniformity requirements such as thick-layer potting and precision electronic insulation, hot air circulation curing is the preferred process due to its superior uniformity. For thin-coat rapid curing applications such as release film coating, the high-efficiency advantage of infrared heating can be adopted. To balance production efficiency and product quality, a combined "infrared + hot air" process is recommended: infrared heating is used for rapid surface drying or preheating, and hot air heating is applied to complete uniform deep curing.

The above content is provided by Jiangsu Aokai New Material Technology Co., Ltd., a professional manufacturer of high-temperature Teflon cloth.

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