Hydroxyethyl Cellulose (HEC) It has many functions, including: thickening, suspending, binding, emulsifying, film-forming, stabilizing, dispersing, retaining water, and forming protective colloids. It is extremely soluble in hot or cold water, can be formulated into solutions in a wide range of viscosities, and has excellent resistance to dissolved electrolytes.
method one)
Add directly when grinding the pigment:
1. Add appropriate purified water to a large bucket equipped with a high-cut agitator (generally, ethylene glycol, wetting agent and film-forming agent are added in this step).
2. Start stirring continuously at low speed and slowly sieve the hydroxyethyl cellulose evenly into the solution.
3. Continue stirring until all particles are soaked through.
4. Then add antifungal agent, alkaline additives such as pigment dispersing aids, ammonia water.
5. Stir until all the hydroxyethyl cellulose is completely dissolved (the viscosity of the solution increases significantly) before adding other components in the formula, and grind until it becomes paint.
Method Two)
Equipped with mother liquor for use:
This method is to first prepare a mother liquor with a higher concentration, and then add it to the latex paint. The advantage of this method is that it has greater flexibility and can be directly added to the finished paint, but proper storage is required. The steps are similar to steps 1-4 in method (1), the difference is that there is no need for a high-shear agitator, and only some agitators with sufficient power to keep the hydroxyethyl cellulose uniformly dispersed in the solution can be used. Continue constant stirring until completely dissolved into a viscous solution. It should be noted that the antifungal agent must be added to the mother liquor as soon as possible.
Method (3)
For porridge-like phenology:
Since organic solvents are poor solvents for hydroxyethyl cellulose, these organic solvents can be used to prepare porridge. The most commonly used organic solvents are organic liquids such as ethylene glycol, propylene glycol, and film formers (eg, hexanediol or Butyl CARBITOL acetate) in paint formulations. Ice water is also a poor solvent, so ice water is often used with organic liquids to prepare porridge.
The porridge-like hydroxyethyl cellulose can be directly added to the paint. The hydroxyethyl cellulose has been sufficiently swollen in the porridge state. When added to the paint, it dissolves immediately and thickens. After adding, it is still necessary to keep stirring until the hydroxyethyl cellulose is completely dissolved and uniform.
Generally, the porridge is mixed with six parts of organic solvent or ice water and one part of hydroxyethyl cellulose. After about 5-30 minutes, the hydroxyethyl cellulose will be hydrolyzed and swelled obviously. In summer, the temperature of the water is too high, and it is not suitable for porridge.
Matters needing attention when preparing hydroxyethyl cellulose mother liquor:
Hydroxyethyl cellulose is generally a processed powder and granular material. As long as the following matters are noted, it is easy to handle and dissolve in water.
1. Before and after adding hydroxyethyl cellulose, keep stirring until the solution is completely transparent and clear.
2. It must be sieved into the mixing barrel slowly. Do not directly add the hydroxyethyl cellulose that has been formed into lumps or balls into the mixing barrel.
3. The water temperature and the pH value of the water have an obvious relationship with the dissolution of hydroxyethyl cellulose, so special attention should be paid to it.
4. Never add some alkaline substances to the mixture before the hydroxyethyl cellulose powder is soaked with water. Raising the pH only after wetting will aid in dissolution.
5. As far as possible, add antifungal agent as early as possible.
6. When using high-viscosity hydroxyethyl cellulose, the concentration of the mother liquor should not be higher than 2.5-3% (by weight), otherwise the mother liquor will be difficult to handle.
Post time: Nov-15-2022