How to use hydroxyethyl cellulose in latex paint
1. Hydroxyethyl cellulose is used to make 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 together with organic liquids to prepare porridge. Porridge-like hydroxyethyl cellulose can be directly added to latex paint. Hydroxyethyl cellulose has been fully soaked in porridge. When added to the paint, it dissolves quickly and acts as a thickener. After adding, keep stirring until the hydroxyethyl cellulose is completely dispersed and dissolved. Generally, porridge is made by mixing six parts of organic solvent or ice water with one part of hydroxyethyl cellulose. After about 5-30 minutes, the hydroxyethyl cellulose will be hydrolyzed and swell obviously. (Reminder that the humidity of general water is too high in summer, so it should not be used to equip porridge.)
2. Add hydroxyethyl cellulose directly when grinding the pigment: This method is simple and takes a short time. The detailed method is as follows:
(1) Add appropriate amount of purified water into the large bucket of high shear mixer (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 to stir until all particles are evenly dispersed and soaked
(4) Add anti-mildew additives to adjust the 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 the paint is formed.
3. Prepare hydroxyethyl cellulose with mother liquor for later use: This method is to prepare mother liquor with higher concentration first, and then add it to latex paint. The advantage of this method is that it is more flexible and can be directly added to the finished paint, but it must be properly stored. . The steps and method are similar to steps (1)-(4) in method 2, the difference is that no high-shear agitator is needed, and only some agitators with enough power to keep the hydroxyethyl fiber dispersed evenly in the solution are Can. Continue to stir continuously 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 it in water as long as the following items are paid attention to.
(1) Before and after adding hydroxyethyl cellulose, it must be stirred continuously until the solution is completely transparent and clear.
(2) It must be slowly sifted into the mixing tank, and do not directly add a large amount of hydroxyethyl cellulose that has formed lumps or balls into the mixing tank.
(3) The water temperature and the pH value in the water have a significant relationship with the dissolution of hydroxyethyl cellulose, so special attention must be paid.
(4) Do not add some alkaline substances to the mixture before the hydroxyethyl cellulose powder is soaked with water. Raising the pH after wetting out aids dissolution.
(5) As far as possible, add anti-fungal agent early.
(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) Due to excessive stirring, the humidity is overheated during dispersion.
(2) The amount of other natural thickeners in the paint formulation and the ratio of the amount to hydroxyethyl cellulose.
(3) Whether the amount of surfactant and the amount of water used in the paint formula are appropriate.
(4) When synthesizing latex, the amount of oxide content such as residual catalyst.
(5) Corrosion of thickener by microorganisms.
(6) In the paint making process, whether the step sequence of adding thickener is appropriate.
7 The more air bubbles remain in the paint, the higher the viscosity
Post time: Mar-04-2023