Hydroxyethyl cellulose (HEC), chemical formula (C2H6O2)n, is a white or light yellow, odorless, non-toxic fibrous or powdered solid, composed of alkaline cellulose and ethylene oxide (or chloroethanol) It is prepared by etherification reaction and belongs to non-ionic soluble cellulose ethers. Because HEC has good characteristics of thickening, suspending, dispersing, emulsifying, bonding, filming, protecting moisture and providing protective colloid, it has been widely used in petroleum exploration, coatings, construction, medicine and food, textiles, papermaking, and macromolecules. Polymerization and other fields. 40 mesh sieving rate ≥99%.
Preparation
1. Alkaline cellulose is a natural polymer. Each fiber base ring contains three hydroxyl groups. The most active hydroxyl groups react to produce hydroxyethyl cellulose. Soak the raw cotton linters or refined pulp in 30% liquid caustic soda, take it out and squeeze after half an hour. Squeeze until the ratio of alkaline water reaches 1:2.8, then crush. The pulverized alkali cellulose is put into the reaction kettle, sealed, evacuated, filled with nitrogen, and vacuum filled with nitrogen is repeated to completely replace the air in the kettle. Press into the pre-cooled ethylene oxide liquid, and pass cooling water into the jacket of the reactor, and control the reaction at about 25°C for 2 hours to obtain crude hydroxyethyl cellulose. The crude product is washed with alcohol, neutralized with acetic acid to pH 4-6, and then cross-linked with glyoxal for aging. Then it is washed with water, dewatered by centrifugation, dried and pulverized to obtain hydroxyethyl cellulose. Raw material consumption (kg/t): cotton linters or low pulp: 730-780, liquid caustic soda (30%): 2400, ethylene oxide: 900, alcohol (95%): 4500, acetic acid: 240, ethylene two Aldehydes (40%): 100-300.
2. Gas phase method: In the gas phase method, additives or diluents are added during the reaction, and the alkali fiber and EO react in the gas phase. The cotton fiber is immersed in 18.5% NaOH solution, activated, squeezed, crushed, and placed in the reactor. The reactor is evacuated into a vacuum, nitrogen is filled twice, EO is added, and the reaction is carried out at a vacuum of 90.64 kPa and 27-32°C for 3 to 3.5 hours.
3. Liquid phase method: The liquid phase method is to carry out etherification reaction in the presence of diluent. After being alkalized and squeezed, the cotton linters are reacted with EO at 20-60°C for 1 to 3 hours in the presence of a diluent to obtain crude hydroxyethyl cellulose. Commonly used diluents are acetone, isopropanol, tert-butanol or their mixtures. The product remains insoluble in the diluent.
The two production processes of gas phase method and liquid phase method need to prepare alkali cellulose in advance, that is, the cellulose is immersed in 18% NaOH solution at about 20°C for degreasing, after etherification, it is neutralized, washed, dried, and pulverized to obtain Final product.
Application
Application field
Used as adhesive, surface active agent, colloidal protective agent, dispersant, emulsifier and dispersion stabilizer, etc. It has a wide range of applications in the fields of coatings, inks, fibers, dyeing, papermaking, cosmetics, pesticides, mineral processing, oil extraction and medicine.
1. Generally used as thickeners, protective agents, adhesives, stabilizers and additives for the preparation of emulsions, gels, ointments, lotions, eye clearing agents, suppositories and tablets, and also used as hydrophilic gels and skeletons Materials, preparation of matrix-type sustained-release preparations, and can also be used as stabilizers in food.
2. Used as sizing agent in textile industry, bonding, thickening, emulsifying, stabilizing and other additives in electronics and light industry.
3. It is used as a thickener and fluid loss reducer for water-based drilling fluids and completion fluids. The thickening effect is obvious in brine drilling fluids. It can also be used as a fluid loss control agent for oil well cement. It can be cross-linked with multivalent metal ions to form a gel.
4. This product is used for fracturing petroleum water-based gel fracturing fluid, polystyrene and polyvinyl chloride and other polymeric dispersants. It can also be used as a latex thickener in the paint industry, a humidity-sensitive resistor in the electronics industry, a cement anticoagulant and a moisture retention agent in the construction industry. Ceramic industry glaze and toothpaste adhesive. It is also widely used in printing and dyeing, textile, papermaking, medicine, hygiene, food, cigarettes, pesticides and fire extinguishing agents.
5. Used as surface active agent, colloidal protective agent, emulsion stabilizer for vinyl chloride, vinyl acetate and other emulsions, as well as latex thickener, dispersant, dispersion stabilizer, etc. It is widely used in coatings, fibers, dyeing, papermaking, cosmetics, medicine, pesticides, etc. It also has many uses in oil exploration and machinery industry.
6. Hydroxyethyl cellulose has surface activity, thickening, suspension, adhesion, emulsification, film formation, dispersion, water retention and protection in solid and liquid pharmaceutical preparations.
7. It is used as a polymer dispersant for the exploitation of petroleum water-based gel fracturing fluid, polyvinyl chloride and polystyrene. It can also be used as a latex thickener in the paint industry, a cement retarder and moisture retention agent in the construction industry, a glazing agent and toothpaste adhesive in the ceramic industry. It is also widely used in industrial fields such as printing and dyeing, textile, papermaking, medicine, hygiene, food, cigarettes and pesticides.
Product performance
1. HEC is soluble in hot or cold water, and does not precipitate at high temperature or boiling, making it have a wide range of solubility and viscosity characteristics, and non-thermal gelation;
2. It is non-ionic and can coexist with a wide range of other water-soluble polymers, surfactants, and salts. It is an excellent colloidal thickener containing high-concentration dielectric solutions;
3. The water retention capacity is twice as high as that of methyl cellulose, and it has better flow regulation;
4. Compared with the recognized methyl cellulose and hydroxypropyl methyl cellulose, the dispersing ability of HEC is the worst, but the protective colloid ability is the strongest.
Instructions
Add directly during production
1. Pour clean water into a large bucket equipped with a high-grade agitator.
2. Start stirring continuously at low speed and slowly sift the hydroxyethyl cellulose into the solution evenly.
3. Continue to stir until all the particles are soaked.
4. Then add anti-fungal agents, alkaline additives, such as pigments, dispersing aids, and ammonia.
5. Stir until all the hydroxyethyl cellulose is completely dissolved (the viscosity of the solution increases significantly) before adding other ingredients in the formula, and grind until the finished product.
Equipped with mother liquor
This method is to prepare a higher concentration mother liquor first, and then add it to the latex paint. The advantage of this method is that it has greater flexibility and can be directly added to the finished paint, but it should be stored appropriately. The steps are similar to parts 1-4 in Method 1, except that it does not need to be stirred until it is completely dissolved into a viscous solution.
Make porridge for later use
Since organic solvents are poor solvents for hydroxyethyl cellulose, these organic solvents can be used to prepare 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 used with organic liquids to prepare porridge. The hydroxyethyl cellulose of the porridge can be directly added to the lacquer, and the hydroxyethyl cellulose has been soaked in the porridge. When added to the paint, it will immediately dissolve and act as a thickening agent. After adding, continue to stir until the hydroxyethyl cellulose is completely dissolved and uniform. Generally, the porridge is made by mixing six parts of organic solvent or ice water with one part of hydroxyethyl cellulose. After about 6-30 minutes, the hydroxyethyl cellulose is hydrolyzed and swells obviously. In summer, the water temperature is generally too high, so it is not suitable to equip with porridge.
Use attention
Since the surface-treated hydroxyethyl cellulose is powder or cellulose solid, it is easy to handle and dissolve in water as long as the following matters are noted.
1. Before and after adding hydroxyethyl cellulose, stirring must be kept until the solution is completely transparent and clear.
2. It must be sifted into the mixing tank slowly. Do not directly add the hydroxyethyl cellulose that has formed into lumps or balls into the mixing tank in large quantities or directly.
3. The water temperature and the pH value of the water have an obvious relationship with the dissolution of hydroxyethyl cellulose, so special attention must be paid.
4. Never add some alkaline substances to the mixture before the hydroxyethyl cellulose powder is warmed by water. Raising the PH value after warming up will help dissolve.
5. Add the anti-mold agent as early as possible within the range.
6. When using high-viscosity hydroxyethyl cellulose, the concentration of the mother liquor should not be higher than 2.5-3%, otherwise the mother liquor is difficult to operate. After post-treatment, hydroxyethyl cellulose is generally not easy to form lumps or spheres, and it will not form insoluble spherical colloids after adding water.
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