The nature of hydroxyethyl cellulose
I. Overview
Hydroxyethyl cellulose (HEC) is a white or light yellow, odorless, non-toxic fibrous or powdery solid. That is prepared by etherification reaction of alkaline cellulose and ethylene oxide (or chlorohydrin). It is a non-ionic soluble cellulose ether.
It has good properties of thickening, suspending, dispersing, emulsifying, bonding, film forming, protecting moisture and providing protective colloids. So has been widely used in oil extraction, coatings, construction, textile, paper and polymer polymerization.
II.The nature
40 mesh screening rate ≥ 99%; softening temperature: 135-140 ° C. Performance density: 0.35-0.61g/ml; decomposition temperature: 205-210 °C. The burning rate is slow; the equilibrium temperature is 23 °C. 6% at 50% rh and 29% at 84% rh.
It is soluble in cold water and soluble in hot water. Generally, it is insoluble in most organic solvents. The pH value changes little in the range of 2-12, but the viscosity decreases beyond this range.
Hydroxyethyl cellulose acts as a nonionic surfactant. In addition to thickening, suspending, bonding, bubbling, film forming, dispersion, water retention and providing protective colloid, it also has the following properties:
1. HEC is soluble in hot or cold water, and does not precipitate at high temperature or boiling. It has a wide range of solubility and viscosity properties, and non-thermal gel properties;
2. The non-ionic type itself can coexist with other water-soluble polymers, surfactants and salts in a wide range, which is an excellent colloid thickener containing a high concentration of electrolyte solution;
3. The water retention capacity is twice as high as that of methyl cellulose, and it has good flow regulation.
4. The ability of HEC to disperse is the strongest to protect colloids compared to the recognized hydroxypropyl methylcellulose.
III. How to use
Different uses have different methods of use, which are broadly divided into the following ways:
(1), directly in production
1. Add purified water to the vat with a high-cutting agitator.
2. Start stirring at low speed and slowly sift the hydroxy Z-based cellulose into the solution.
3. Continue stirring until all particles are wet.
4. Then add a lightning protection agent, an alkaline additive such as a pigment, a dispersing aid, and ammonia water.
5. Stir until all of the hydroxy Z-based cellulose is completely dissolved (the viscosity of the solution is significantly increased) before adding the other components of the formulation and grinding to the finished product.
(2), equipped with mother liquor
This method is first equipped 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. Can be directly add to the finished paint, but should be stored properly. The procedure is similar to the one or four parts of the method 1, except that it is not necessary to mix high to completely dissolve into a viscous solution.
(3), used as a porridge
Since the organic solvent is a poor solvent for the hydroxyethyl group-based cellulose, these organic solvents can be used to provide a porridge.
The most commonly used organic solvents are organic liquids in paint formulations such as ethylene glycol, propylene glycol and film formers such as ethylene glycol or diethylene glycol butyl acetate. Ice water is also a poor solvent, so ice water is often use together with organic liquids for porridge.
The porphyrin hydroxyethyl cellulose can be directly added to the lacquer, and the hydroxyethyl cellulose has been swelled in the porridge. When added to the paint, it dissolves immediately and thickens.
Stirring must continue after the addition until the hydroxy Z-base cellulose is completely dissolve and homogeneous.
The porridge is usually prepare by mixing six parts of an organic solvent or ice water with a portion of hydroxyZ-based cellulose, after about 6 to 30 minutes. Hydroxyethyl cellulose hydrolyzes and rises markedly. Generally, the water temperature is too high in summer, and it is not suitable to use porridge.
