The amount of sodium carboxymethyl cellulose (CMC-Na) added in textile printing and dyeing needs to be flexibly adjusted according to specific application scenarios such as process type, fiber material, product requirements, etc. The following is an analysis of the common addition range and influencing factors in different application scenarios:
1. Main application scenarios and addition amounts
1.1 As a sizing agent (sizing process)
The function is to improve the wear resistance, flexibility and cohesion of the yarn and reduce the breakage during weaving. In terms of addition amount, pure cotton yarn is usually 1%~3% of the total mass of the sizing (i.e. 10~30 kg/ton sizing); polyester-cotton blended yarn has a low fiber friction coefficient, and the addition amount can be appropriately increased to 2%~5%; high-count yarn or thin fabrics can be added to enhance the sizing effect. The amount can reach 3%~6%. The influencing factors include yarn thickness. Low-count yarn (coarse yarn) requires a lower addition amount, while high-count yarn (fine yarn) requires a higher addition amount. If the slurry formula is compounded with other slurries such as starch and polyvinyl alcohol (PVA), the proportion of CMC-Na can be reduced to 1%~2%.
1.2 As a printing paste
It acts as a thickener and stabilizer for the color paste, controls the diffusion of dyes, and improves the clarity and uniformity of the printed pattern. In terms of addition amount, the content of CMC-Na in the paste is usually 2%~5% (i.e. 20~50 kg/ton of paste) during direct printing; due to the complex process of resist printing or discharge printing, the paste stability requirements are high, and the addition amount can be increased to 5%~8%; when fine patterns or high viscosity are required, the addition amount can reach 8%~10%, but it is necessary to avoid excessive viscosity resulting in insufficient color paste fluidity.
1.3 As a finishing agent (post-treatment process)
It is used for fabric softening and antistatic finishing to improve the feel and functionality of the fabric. The addition amount is generally 0.5%~2% of the mass of the softening finishing liquid; the addition amount for antistatic finishing is 1%~3%, which can be used in combination with antistatic agents; coating finishing is an auxiliary component of adhesives, and the addition amount generally does not exceed 1%~2%.
2. Key factors affecting the addition amount
In terms of fiber type, natural fibers (cotton, linen) have strong hygroscopicity and require a higher addition amount (2%~5%) to ensure the sizing effect; synthetic fibers (polyester, nylon) are smooth and easy to slip, and the amount of CMC-Na needs to be increased (3%~6%) to improve the cohesion. In terms of fabric density, high-density fabrics (such as poplin and satin) have greater friction during weaving, and the addition amount needs to be increased to 3%~6%; the addition amount of low-density fabrics (such as plain cloth) can be reduced to 1%~3%. In terms of process temperature, the viscosity of CMC-Na decreases during high-temperature sizing (90~100℃), and the addition amount needs to be appropriately increased (+1%~2%); normal temperature printing can be added according to the conventional amount. In terms of water hardness, hard water (high calcium and magnesium ion content) easily reacts with CMC-Na to form precipitation, so it is necessary to increase the addition amount (+1%~3%) or pre-soften the water. In terms of equipment type, high-speed looms require a higher addition amount (3%~5%) to enhance wear resistance due to the high yarn tension; the addition amount of low-speed looms can be appropriately reduced (1%~3%).
3. Principles and precautions for adding amount control
Before using the new formula, a small test should be carried out, and the addition amount should be adjusted according to the gradient of 0.5%~1%. Test the slurry viscosity, yarn breaking strength, printing clarity and other indicators to determine the optimal amount. A compounding and synergistic strategy can be adopted, such as compounding with starch (such as 70% starch + 30% CMC-Na) to reduce costs and improve the film-forming property of the slurry; compounding with sodium alginate (for printing) to improve the mesh permeability and water retention of the paste, and the addition amount can account for 2%~3% each. Avoid excessive addition. Excessive addition (>10%) will lead to high viscosity of the slurry, increase equipment load, and may affect the feel of the fabric (such as hardening); excessive addition during printing will lead to poor color paste penetration, increased floating color on the pattern surface, and decreased friction fastness.
4. Industry reference standards and examples
The textile industry standard FZ/T 12006-2017 (cotton natural color sewing thread) recommends that the amount of CMC-Na added to the sizing agent be 1%~3%. A printing and dyeing factory uses 5% CMC-Na and 3% sodium alginate as a paste in the printing of pure cotton plain cloth. The clarity of the printed pattern reaches level 4 (full score 5), and the color fastness meets the GB/T 3920-2008 standard.
In summary, the addition amount of sodium carboxymethyl cellulose in textile printing and dyeing usually fluctuates in the range of 0.5%~10%, and needs to be adjusted according to the fiber type, process requirements and on-site conditions. In actual production, it is recommended to determine the precise dosage through small tests to balance cost, performance and production efficiency.
