The main process parameters of sizing include: sizing rate, moisture regain, extrusion moisture regain, elongation, sizing reinforcement rate, sizing elongation reduction rate, and total solid content of the sizing liquid.
1. Sizing rate: the percentage of the dry sizing weight of the warp yarn after sizing to the dry weight of the original warp yarn before sizing.
Sizing rate (%) = dry weight of sizing * 100% / dry weight of original warp yarn
In actual production, the fluctuation of sizing rate should be controlled within 1%. The sizing pass rate should be greater than 95%.
2. Moisture regain: The moisture regain of sizing yarn refers to the percentage of moisture content to the dry weight of sizing yarn.
Moisture regain%=(wet weight of sizing-dry weight of sizing)*100%/dry weight of sizing
Excessive moisture regain will cause unclear weaving openings, and too small a moisture regain will cause brittle ends. In actual production, the moisture regain fluctuation should be less than ±0.5%, and the moisture regain qualification rate should be controlled at 90%.
3. Extrusion moisture regain: the percentage of the weight of water contained in the sizing yarn to the dry weight of the sizing yarn after it exits the pressing roller and before entering the drying room.
4. Elongation: the percentage of the yarn elongation after warp sizing to the original warp length.
Sizing elongation % = (sizing length – original warp length) * 100% / original warp length
Generally, the elongation of sizing yarn should be controlled at 0.5-1.5%.
5. Sizing enhancement rate: the percentage of the difference between the breaking strength of the sizing yarn and the breaking strength of the original yarn to the breaking strength of the original yarn.
Sizing reinforcement rate % = (breaking strength of sizing – breaking strength of original yarn) * 100% / breaking strength of original yarn
6. Elongation reduction rate of sizing yarn: the percentage of the difference in the breaking elongation of the original warp yarn before sizing to the breaking elongation of the original yarn.
The elongation reduction rate of the sizing yarn % = (the breaking elongation of the original yarn – the breaking elongation of the sizing yarn) * 100% / the breaking elongation of the original yarn
7. Total solid content of slurry: The total content of dry slurry in the slurry after the volume, viscosity, and temperature are determined at the end of slurry mixing.
Total solids rate of slurry % = dry weight of slurry * 100% / (weight of water in slurry + dry weight of slurry)
8. Slurry components: Various slurries contained in the slurry are mixed into slurry according to the proportions designed by the process. It includes three parts: water, main slurry and auxiliary slurry. Main slurry: mainly adhesive. Auxiliary sizing: In order to make the sizing quality better after sizing and the performance of the sizing film to be intact, relevant auxiliary sizing is added. Such as: decomposers, lubricants, preservatives, penetrants, defoaming agents, antistatic agents, softeners, moisture absorbers, anti-wear agents, etc.
9. Three determinations of the pulp mixing process: constant concentration, constant viscosity, and constant temperature.
Concentration: In the slurry, the total dry weight content of the slurry. When other conditions remain unchanged, the concentration directly affects the sizing rate. If the concentration is higher, the sizing rate will be higher.
Methods for measuring concentration include: (1) Concentration meter: such as Baume meter, sugar meter, etc. (2) Baking test method. (3) Calculation method. In actual production operations, concentration is often expressed by the volume of slurry, also known as the constant volume method.
Viscosity: The viscosity of the slurry is related to the penetration of the slurry. It has low viscosity, high fluidity and good penetration, which can lead to better adhesion and cohesion between fibers and less relative slippage between fibers, which is beneficial to sizing reinforcement and reducing end breakage.
Methods for measuring viscosity: (1) NDJ-79 rotary viscometer is commonly used in laboratories. (2) Funnel viscometer is commonly used in production operations.
Temperature: It is the temperature when the concentration and viscosity are specified. The slurry temperature is related to the slurry viscosity.
10. Serum penetration, covering and serous membrane integrity:
The penetration, approval and integrity of the slurry directly affect the quality of the sizing yarn. Soaking is related to sizing strength. The approval is related to the smoothness and wear resistance of the sizing yarn. The integrity of the sizing film is related to the wear resistance and hairiness of the sizing yarn.
Slurry penetration: During the sizing process, the slurry enters the inside of the yarn, bonding the fibers to each other and increasing the strength.
Sizing approval: The sizing coats a layer of sizing film on the surface of the yarn to make the surface of the sizing yarn smooth, reduce hairiness, and make it wear-resistant during weaving. The size of the batch will affect the quality of the sizing. If the batch is too large, the penetration will be less, resulting in surface sizing, more sizing, and brittle fracture during weaving. If the batch is too small, it will be incomplete and prone to fluffing. Sizing film integrity: the integrity of the sizing film covered by the sizing material on the yarn surface.
11. Slurry consumption quota: The amount of main slurry used in one ton of dry warp yarn (kg/ton) is one of the economic indicators for calculating product costs. Enterprises also often calculate the slurry cost per meter of gray fabric when assessing the pulp consumption quota. (yuan/meter).
12. Sizing efficiency: the percentage of the sizing rate measured in the laboratory that meets the process design requirements.
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