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How to ensure the organic silicone adhesive achieves the target curing degree by matching the line speed of the coating machine and oven length for high-temperature PTFE tape?
Views: 0 Author: Site Editor Publish Time: 2026-07-23 Origin: Site
The essence of matching is that the total residence time t_{total} of the adhesive layer within the effective heating length L of the oven shall be no less than the minimum curing time required by the process. Line speed v=L/t shall be determined according to the oven temperature profile and the curing kinetics of the adhesive.
2. Acquisition of Curing Characteristics
Conduct measurements via DSC or adhesive layer curing tests to obtain the required curing time tcure(T) for reaching the target crosslinking degree (e.g. ≥90%) at different constant temperatures T, and establish the relationship of "Temperature – Minimum Curing Time". Adhesive suppliers often provide reference conditions, such as 150 °C × 3 min.
3. Equivalent Cumulative Curing Model
Divide the oven into zones by temperature and adopt the equivalent cumulative curing time method for judgment:titcureTi≥1 Where ti = residence time in Zone i; tcure(Ti) = required curing time at temperature Ti of this zone. The target curing degree is achieved when the sum is ≥ 1.
II. Calculation Procedures for Matching Line Speed and Oven Length
1. Temperature Zone Division and Parameter Setting
Divide the oven into n segments along its length. Each segment has length Li and temperature Ti (hot air temperature can be directly adopted for thin substrates).
2. Calculation of Intra-Zone Residence Time and Contribution Ratio
Set line speed v, then ti=Li/v. Look up tcure(Ti) corresponding to Ti, and calculate the curing contribution ratio of each segment: ti/tcureTi.
3. Iterative Adjustment to Meet Requirements
Sum up the contribution ratios of all zones. If the total value ＜ 1, reduce line speed or raise temperature; if far greater than 1, line speed can be increased to boost output. The final condition to satisfy: Liv·tcureTi≥1If temperature lag exists, the integral formula 1tcure[T(t)]dt≥1 can be applied for correction.
III. Measures to Ensure Organic Silicone Adhesive Reaches Target Curing Degree
1. Optimize Oven Temperature Gradient
Low temperature in the front section (80~100 °C) to fully evaporate solvents and avoid surface skinning; medium and rear sections adopt high temperature (140~180 °C) for crosslinking and curing; the final section serves for post-curing. The solvent evaporation section accounts for approximately 1/4 of the oven, and the curing section occupies more than 3/4.
2. Precisely Control Coating Thickness
Wet adhesive thickness determines heat transfer and solvent diffusion rate. Curing time must be measured based on actual production thickness. Stable control shall be realized via coating heads; test data of thinner coatings cannot be borrowed.
3. Establish Curing Degree Inspection System
· Residual solvent: Tested by gas chromatography; residual toluene and other solvents shall be less than 0.1%.
· Crosslinking degree: Measure gel content via swelling method, target value >85%~90%.
· Adhesion strength and DSC residual enthalpy: Low adhesion or observable residual exothermic peak indicates under-curing.
4. Real-Time Monitoring and Safety Margin
Strictly control temperature of each zone (±3 °C) and line speed, and guarantee uniform hot air and smooth exhaust. A cumulative contribution ratio of ≥1.1~1.2 can be set during calculation to compensate for process fluctuations.
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