Application of hydroxyethyl cellulose in emulsion paint

1. Adding directly when grinding pigment: this method is the simplest and takes a short time. The detailed steps are as follows:

(1) Add proper purified water into the bucket of the high stress shear mixer (generally, ethylene glycol, wetting agent and film-forming agent are added at this time);

(2) Start stirring at low speed and slowly add hydroxyethyl cellulose;

(3) Continue stirring until all particles are wet;

(4) Add mildew inhibitor, pH regulator, etc;

(5) Stir until all hydroxyethyl cellulose is completely dissolved (solution viscosity increases significantly), then add other components in the formula, and grind until paint is formed.

2. Prepare mother liquor for standby use: this method is to prepare mother liquor with high concentration first, and then add it to latex paint. The advantage of this method is that it has great flexibility and can be directly added to finished paint, but it must be stored properly. The steps and methods are similar to steps (1) - (4) in method 1, except that there is no need for a high shear stirrer, and only some stirrers with sufficient power to keep the hydroxyethyl fiber evenly dispersed in the solution can be used. Continue stirring until it is completely dissolved into a viscous solution. It should be noted that the mildew inhibitor must be added to the mother liquor as soon as possible.

3. For preparing porridge like phenology: since organic solvents are bad solvents for hydroxyethyl cellulose, these organic solvents can be used to prepare porridge like phenology. The most commonly used organic solvents are ethylene glycol, propylene glycol, and film-forming agents (such as hexanediol or diethylene glycol butyl acetate). Ice water is also a bad solvent, so ice water is often used with organic liquids to prepare porridge.

Congee like hydroxyethyl cellulose can be directly added to the paint. In the porridge, hydroxyethyl cellulose has been fully foamed. When the paint is added, it will immediately dissolve and thicken. After addition, keep stirring until the hydroxyethyl cellulose is completely dissolved and uniform. Generally, porridge is mixed with six parts of organic solvent or ice water and one part of hydroxyethyl cellulose. After about 5-30 minutes, hydroxyethyl cellulose will hydrolyze and rise obviously. In summer, the humidity of general water is too high to be used for porridge.

4. Precautions when preparing hydroxyethyl cellulose mother liquor

Since hydroxyethyl cellulose is a treated powder particle, it is easy to operate and dissolve in water as long as the following matters are paid attention to.

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 drum slowly. Do not add a large amount of or spherical hydroxyethyl cellulose directly into the mixing drum.

3) The water temperature and pH value of water have an obvious relationship with the dissolution of hydroxyethyl cellulose, which should be paid special attention.

4) Do not add some alkaline substances to the mixture before the hydroxyethyl cellulose powder is soaked with water. Increasing the pH value after soaking helps to dissolve.

5) Add mold inhibitor as early as possible.

6) When using high viscosity hydroxyethyl cellulose, the mother liquor concentration shall not be higher than 2.5-3% (by weight), otherwise the mother liquor is difficult to operate.