How to use hydroxyethyl cellulose in latex paint
1. Hydroxyethyl cellulose is used to prepare porridge: Since hydroxyethyl cellulose is not easy to dissolve in organic solvents, some organic solvents can be used to prepare porridge. 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 latex paint. The hydroxyethyl cellulose has been fully swollen in the porridge. When added to the paint, it dissolves quickly and plays a thickening role. After adding, it is still necessary to keep stirring until the hydroxyethyl cellulose is completely dispersed and dissolved. 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. (It is suggested that the humidity of general water is too high in summer, so it is not suitable to be used for porridge.)
2. Add hydroxyethyl cellulose directly when grinding the pigment: This method is simple and takes less time. The detailed method is as follows:
(1) Add appropriate pure water to the vat of the high-cut agitator (generally, film-forming aids and wetting agents are added at this time)
(2) Start stirring continuously at low speed and slowly and evenly add hydroxyethyl cellulose
(3) Continue stirring until all particles are dispersed evenly and soaked
(4) Add antifungal additives to adjust PH value
(5) Stir until all the hydroxyethyl cellulose is completely dissolved (the viscosity of the solution increases significantly), then add other components in the formula, and grind until it becomes a paint.
3. Prepare hydroxyethyl cellulose with mother liquor for use: This method is to prepare mother liquor with higher concentration first, and then add it to the latex paint. The advantage of this method is that it is more flexible and can be directly added to the finished paint, but it needs to be properly stored. . The steps and methods are similar to steps (1)-(4) in method 2, the difference is that there is no need for a high-shear agitator, and only some agitators with sufficient power to keep the hydroxyethyl fibers uniformly dispersed in the solution are used. Can. Continue constant stirring until completely dissolved into a viscous solution. It should be noted that the antifungal agent must be added to the paint mother liquor as soon as possible.
4 Matters needing attention when preparing hydroxyethyl cellulose mother liquor
Since hydroxyethyl cellulose is a processed powder, it is easy to handle and dissolve in water as long as the following matters are noted.
(1) Before and after adding hydroxyethyl cellulose, it must be kept 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 and balls into the mixing barrel in large quantities or directly.
(3) Water temperature and pH value in water have a significant relationship to the dissolution of hydroxyethyl cellulose, so special attention should be paid.
(4) Do not 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.
Factors affecting the viscosity of latex paint:
(1) The humidity is overheated during dispersion due to excessive stirring.
(2) The dosage of other natural thickeners and the dosage ratio of hydroxyethyl cellulose in the paint formula. )
(3) Whether the amount of surfactant and the amount of water in the paint formula are appropriate.
(4 When synthesizing latex, the amount of residual catalyst and other oxides.
5 Microbial erosion of thickeners.
6 During the paint making process, is the sequence of steps for adding thickeners appropriate?
7 The higher the content of air bubbles remaining in the paint, the higher the viscosity