Lubricant plays an important role in improving the coating structure of coated paper. The paper coating layer should have enough plasticity during calendering so that the coating can be plasticized and fluid when pressed, thereby making the coating surface smooth and preventing the internal structure of the paper from being damaged.
The main function of the lubricant is to improve the smoothness and fluidity of the wet coating surface by reducing the interfacial tension, making it easy to flow and spread on the paper, improving The coating adaptability of the coating is improved by giving the dry coating a certain degree of plasticity and slippage to better adapt to the matt finish, and efforts are made to reduce or remove fluff and powder loss to improve the finished performance of the coating. (Such as improving the smoothness and gloss of the finished paper, etc.).
First of all, coating lubricants can be divided into the following types: 1. Water-soluble metal soaps, 2. Water-insoluble metal soaps, 3. Synthetic esters Category, 4. Fatty ammonium and its derivatives, 5. Wax emulsion category, 6. Bean-lecithin/oleic acid, etc. Among them, the two most commonly used lubricants for coated paperboard are water-insoluble metal soap (calcium stearate) and wax emulsion (polyoxyethylene wax).
Today the supplier of calcium stearate will take you to know about the calcium stearate:
Calcium stearate is a good non-toxic heat stabilizer and lubricant. It is also a flattening agent and water-resistant agent for adhesives and coatings. It is used in chemical production such as plastics and rubber. widely used in the process. But it is cheap and easy to obtain, has low toxicity and good processing performance. It has a synergistic effect when used together with zinc soap and epoxy compounds to improve thermal stability.
Calcium stearate lubricants are still a widely used type of conventional coating lubricants. Commonly used calcium stearate lubricants are solid The content can reach more than 50%, the particle size is mainly distributed between 5μm-10μm, and the conventional dosage is between 0.5% and 1% (absolutely dry to absolutely dry). The advantage of calcium stearate is that it can significantly improve the powder shedding problem of coated paper; the disadvantage is that the most common problems are abnormalities such as excessive sieve residue, wide particle size distribution, and poor stability.
When calcium stearate has high impurity content and poor stability, flocculated waxy substances will appear in the coating pipe and material cavity after use. It absorbs the pigments and latex in the paint and sticks to the inner wall of the metal. This mixture will rush out in the form of lumps during pressure fluctuations or when the machine is started and shut down, seriously affecting the coating operation, especially on coating machines that use spray feeding, it may block the spray nozzle and cause local leakage of coated paper. sick.
Once this kind of problem occurs, it will cause occasional missed coatings, quantity inspection workload and degradation losses, or it will be due to its random and irregular characteristics. This results in refunds, returns, lost orders, and huge claims for the entire batch of goods. Therefore, it is very important to detect calcium stearate (especially domestic chemicals) before putting it on the machine and to track problems after they occur.
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