Method for using hydroxyethyl cellulose HEC in waterborne coatings

Method of using hydroxyethyl cellulose in latex paint

1. Add directly to the grinding pigment: This method is the simplest and takes a short time. The detailed steps are as follows:

(1) Add appropriate purified water to the vat of the high-cutting agitator (in general, ethylene glycol, wetting agent and film-forming agent are add at this time)
(2) Start stirring at low speed and slowly add hydroxyethyl cellulose
(3) Continue to stir until all particles are wet
(4) Add mold inhibitor, pH adjuster, etc.
(5) Stir until all the hydroxyethyl cellulose is completely dissolve (the viscosity of the solution is significantly increase) before adding the other components in the formulation and grinding until the lacquer is form.

2. Equipped with mother liquor:

This method is first equip with a higher concentration of mother liquor and then add to the latex paint. The advantage of this method is that it has greater flexibility and can be directly add to the finished paint, but it must be stored properly. The steps and methods are similar to steps (1)-(4) in Method 1.

The difference is that there is no need for a high-cut agitator, and only a stirrer with sufficient power to keep the hydroxyethyl fibers uniformly disperse in the solution can be use. Continue stirring until completely dissolve into a viscous solution. It should be note that the mold inhibitor must be add to the mother liquor as soon as possible.

3. Formulated as porridge:

Since the organic solvent is a poor solvent for hydroxyethyl cellulose, these organic solvents can be use to provide porridge. The most commonly use organic solvents such as ethylene glycol, propylene glycol, and film formers (such as hexane or diethylene glycol butyl acetate), ice water is also a poor solvent, so ice water is often use together with organic liquids. It is equip with porridge.

The porridge-like hydroxyethyl cellulose can be directly add to the paint. Hydroxyethyl cellulose has been sufficiently swelled in porridge. When it is add, it dissolves immediately and thickens. Stirring must continue after the addition until the hydroxyethyl cellulose is completely dissolve and homogeneous.

Generally, the porridge is mix with a portion of an organic solvent or ice water and a portion of hydroxyethyl cellulose. After about 5 to 30 minutes, the hydroxyethyl cellulose is hydrolyzed and remarkably rises. In general, the humidity of water in summer is too high and should not be used for porridge.

4 Precautions when using hydroxyethyl cellulose mother liquor

Since hydroxyethyl cellulose is a treated granule, it is easy to handle and dissolve in water as long as the following matters are note.

1 Stirring must be continued before and after the addition of hydroxyethylcellulose until the solution is completely clear and clear.
2 It must be slowly sieved into the mixing tank. Do not add the hydroxyethyl cellulose which has been formed into a block and a sphere directly into the mixing tank.
3 The temperature of water and the pH of water have a significant relationship with the dissolution of hydroxyethyl cellulose, which requires special attention.
4 Do not add some alkaline substances to the mixture before the hydroxyethyl cellulose powder is wetted by water. Increasing the pH after soaking helps to dissolve.
5 Add mold inhibitors as soon as possible.

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

Factors affecting the viscosity of latex paint

1 The more the air vesicles remain in the paint, the higher the viscosity.
2 The amount of surfactant used in the paint formulation and the amount of water used are appropriate.
3 The amount of oxides such as residual catalyst when the latex is synthesize.
4 The amount of other natural thickeners in the paint formulation and the proportion of hydroxyethylcellulose. )
5 In the painting process, the order of the steps to add the thickener is appropriate.
6 Due to excessive agitation, the humidity is overheat during dispersion.
7 Microbial attack on thickeners.

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