Effects of Too High or Too Low Sintering Temperatures on PTFE High-Temperature Cloth

Jiangsu Aokai New Materials, a professional manufacturer of PTFE high-temperature cloth, explains the performance defects caused by improper sintering temperatures for PTFE high-temperature cloth.

1. Coating Compactness and Microstructure

· Low sintering temperature: PTFE particles fail to fully melt and diffuse, leaving intact boundaries between particles. A large number of micro-pores form inside the coating, and visible cracks may emerge in severe cases, resulting in poor overall compactness.

· Excessively high sintering temperature: PTFE suffers thermal degradation with broken molecular chains. Small molecular substances generated by decomposition escape outwards, creating pinholes, bubbles and orange-peel rough surfaces. The integrity of the coating is destroyed, and the fiberglass substrate may also be damaged.

2. Adhesion Between Coating and Substrate

· Low sintering temperature: No effective molten mechanical anchoring forms between PTFE resin and fiberglass fabric, leading to extremely weak bonding force. The coating tends to blister, delaminate or peel off in large sheets during service.

· Excessively high sintering temperature: Overheated and degraded PTFE turns the coating brittle, drastically reducing adhesion strength and causing delamination and peeling. Meanwhile, the sizing agent on the substrate is destroyed, further aggravating coating shedding.

3. Surface Condition and Non-Stick Performance

· Low sintering temperature: The coating surface is microscopically rough and uneven with a high friction coefficient. Its non-stick property declines sharply, and materials easily stick to the surface, losing the core advantage of PTFE.

· Excessively high sintering temperature: Escaping decomposition gas creates surface defects such as pinholes, bubbles and orange peel texture, which severely damage surface flatness and non-stick performance.

4. Mechanical Properties and Flexibility

· Low sintering temperature: The coating cannot form a continuous tough film, resulting in poor tensile strength, tear resistance and flex resistance. The fabric feels soft, and the coating may crack and peel off under slight rubbing.

· Excessively high sintering temperature: Degraded PTFE loses flexibility and becomes brittle, prone to cracking and rupturing when folded or stretched. The damaged fiberglass substrate also turns brittle, leading to a sharp drop in overall mechanical strength.

5. Protective and Insulating Properties

· Low sintering temperature: The porous and incompact coating greatly reduces resistance to chemical penetration, dielectric strength and barrier performance.

· Excessively high sintering temperature: Coating degradation destroys compactness and protective performance. Moreover, toxic gas release indicates complete failure of the material.

6. Appearance, Color and Gloss

· Low sintering temperature: The coating is opaque milky white without gloss, lacking the semi-transparent texture of fully sintered products.

· Excessively high sintering temperature: The coating first turns yellow, then brown and even charred black, losing its standard color and transparency.

7. Dimensional Stability

· Low sintering temperature: Without reaching full melting temperature, PTFE cannot shrink completely. The finished product may be oversized with unstable dimensions, yet no severe deformation generally occurs.

· Excessively high sintering temperature: Both PTFE and fiberglass fabric undergo excessive irreversible thermal shrinkage, causing dimensional distortion that fails precision application requirements.

8. Optimal Sintering Temperature Window & Quick Visual Inspection Criteria

· Optimal temperature range: Normally controlled at 370°C ~ 400°C with matched holding time, to achieve full fusion of PTFE particles without thermal degradation.

· Visual judgment standard: Fully sintered coating is semi-transparent with a smooth surface in light tan or natural color; under-sintered cloth is matte and white; over-sintered cloth turns yellow and brittle, with darker color standing for more severe degradation.

The above technical content is provided by Jiangsu Aokai New Materials Technology Co., Ltd.

If you want to learn detailed specifications, application scenarios and customized solutions for our full product line including PTFE high-temperature cloth, PTFE high-temperature adhesive tape, PTFE high-temperature mesh belt, seamless heat press belt, single-sided PTFE fabric, high-temperature resistant conveyor belt and heat-resistant fiberglass cloth, please contact us via the information below:

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