I. Introduction
Hydroxyethyl Cellulose (HEC) is a non-ionic water-soluble polymer widely used in oil extraction, coatings, construction, daily chemicals, papermaking and other fields. HEC is obtained by chemical modification of cellulose, and its properties and uses are mainly determined by the hydroxyethyl substituents on the cellulose molecules.
II. Production process
The production process of HEC mainly includes the following steps: cellulose etherification, washing, dehydration, drying and grinding. The following is a detailed introduction to each step:
Cellulose etherification
Cellulose is first treated with alkali to form alkali cellulose (Cellulose Alkali). This process is usually carried out in a reactor, using sodium hydroxide solution to treat natural cellulose to form alkali cellulose. The chemical reaction is as follows:
Cell-OH+NaOH→Cell-O-Na+H2OCell-OH+NaOH→Cell-O-Na+H 2O
Then, alkali cellulose reacts with ethylene oxide to form hydroxyethyl cellulose. The reaction is carried out under high pressure, usually 30-100°C, and the specific reaction is as follows:
Cell-O-Na+CH2CH2O→Cell-O-CH2CH2OHCell-O-Na+CH 2CH 2O→Cell-O-CH 2CH 2OH
This reaction requires precise control of temperature, pressure and the amount of ethylene oxide added to ensure the uniformity and quality of the product.
Washing
The resulting crude HEC usually contains unreacted alkali, ethylene oxide and other by-products, which need to be removed by multiple water washings or organic solvent washings. A large amount of water is required during the water washing process, and the wastewater after washing needs to be treated and discharged.
Dehydration
The wet HEC after washing needs to be dehydrated, usually by vacuum filtration or centrifugal separation to reduce the moisture content.
Drying
The dehydrated HEC is dried, usually by spray drying or flash drying. The temperature and time must be strictly controlled during the drying process to avoid high temperature degradation or agglomeration.
Grinding
The dried HEC block needs to be ground and sieved to achieve a uniform particle size distribution, and finally form a powder or granular product.
III. Performance characteristics
Water solubility
HEC has good water solubility and can dissolve quickly in both cold and hot water to form a transparent or translucent solution. This solubility property makes it widely used as a thickener and stabilizer in coatings and daily chemical products.
Thickening
HEC shows a strong thickening effect in aqueous solution, and its viscosity increases with the increase of molecular weight. This thickening property enables it to play a role in thickening, water retention and improving construction performance in water-based coatings and building mortars.
Rheology
HEC aqueous solution has unique rheological properties, and its viscosity changes with the change of shear rate, showing shear thinning or pseudoplasticity. This rheological property enables it to adjust fluidity and construction performance in coatings and oilfield drilling fluids.
Emulsification and suspension
HEC has good emulsification and suspension properties, which can stabilize suspended particles or droplets in the dispersion system to prevent stratification and sedimentation. Therefore, HEC is often used in products such as emulsion coatings and drug suspensions.
Biodegradability
HEC is a natural cellulose derivative with good biodegradability, no pollution to the environment, and meets the requirements of green environmental protection.
IV. Application Fields
Coatings
In water-based coatings, HEC is used as a thickener and stabilizer to improve the fluidity, construction performance and anti-sagging properties of coatings.
Construction
In building materials, HEC is used in cement-based mortar and putty powder to improve construction performance and water retention.
Daily Chemicals
In detergents, shampoos, and toothpastes, HEC is used as a thickener and stabilizer to improve the feel and stability of the product.
Oilfields
In oilfield drilling and fracturing fluids, HEC is used to adjust the rheology and suspension properties of drilling fluids and improve drilling efficiency and safety.
Papermaking
In the papermaking process, HEC is used to control pulp fluidity and improve the uniformity and surface properties of paper.
Hydroxyethyl cellulose (HEC) has been widely used in many industrial fields due to its excellent water solubility, thickening, rheological properties, emulsification and suspension properties, as well as good biodegradability. Its production process is relatively mature. Through the steps of cellulose etherification, washing, dehydration, drying and grinding, HEC products with stable performance and good quality can be prepared. In the future, with the improvement of environmental protection requirements and the advancement of technology, the application prospects of HEC will be broader.
Post time: Jul-02-2024