Cellulose ether is a general term for various derivatives of cellulose after etherification reaction and dry grinding. According to different ionization properties, cellulose ether can be divided into ionic type, non-ionic type and mixed type. Among them, ionic cellulose ether is the mainstream product in the market, accounting for about 60%, and the subdivided products include carboxymethyl cellulose ether; Non-ionic cellulose ether subdivided products include methyl cellulose ether, hydroxypropyl methyl cellulose ether, hydroxyethyl cellulose ether, etc. Non-ionic cellulose ether products have high added value. Salt resistance and other aspects are superior to ion type, and the market development prospect is good.
Cellulose ether is water-soluble and solvent-soluble. As a polymer, cellulose ether has a wide range of applications. It can be used as a water-retaining agent, emulsifier, dispersion Agents, thickeners, binders, etc. are used in construction materials, oil exploration, food, medicine, daily chemicals and other fields. At present, domestic cellulose ethers are mainly building material grade products, and pharmaceutical grade and food grade products account for a relatively small proportion. However, with the development of the biopharmaceutical industry and the advancement of production technology, the pharmaceutical grade cellulose ether market has greater development potential.
Cellulose ether properties and characteristics
1. Appearance features
Cellulose ether is generally white or milky white, odorless, non-toxic, fluid fibrous powder, easy to absorb moisture, and dissolves into a transparent viscous stable colloid in water .
2. Film formation and adhesion
The etherification of cellulose ether has a great influence on its characteristics and performance, such as solubility, film-forming ability, bond strength and salt resistance. Cellulose ether has high mechanical strength, flexibility, heat resistance and cold resistance, and has good compatibility with various resins and plasticizers, and can be used to make plastics, films, varnishes, adhesives, latex and Drug coating materials, etc.
3. Solubility
Methylcellulose is soluble in cold water, insoluble in hot water, and also soluble in some organic solvents; methyl hydroxyethyl cellulose is soluble in cold water, insoluble in hot water and organic solvents solvent. However, when the aqueous solution of methylcellulose and methylhydroxyethylcellulose is heated, methylcellulose and methylhydroxyethylcellulose will precipitate. Methylcellulose precipitates at 45-60°C, while the precipitation temperature of mixed etherified methyl hydroxyethyl cellulose increases to 65-80°C. When the temperature is lowered, the precipitate redissolves. Hydroxyethyl cellulose and sodium carboxymethyl hydroxyethyl cellulose are soluble in water at any temperature and insoluble in organic solvents.
4. Thickening
Cellulose ether dissolves in water in the form of colloid, and its viscosity depends on the degree of polymerization of cellulose ether. The solution contains hydrated macromolecules. Due to the entanglement of macromolecules, the flow behavior of solutions is different from that of Newtonian fluids, but exhibits a behavior that changes with changes in shear force. Due to the macromolecular structure of cellulose ether, the viscosity of the solution increases rapidly with the increase of concentration and decreases rapidly with the increase of temperature.
Cellulose ether application
1. Petroleum Industry
Sodium carboxymethyl cellulose is mainly used in oil exploration and in the manufacture of mud to increase viscosity and reduce water loss. It can resist various soluble salt pollution, Enhanced oil recovery. Sodium carboxymethyl hydroxypropyl cellulose (NaCMHPC) and sodium carboxymethyl hydroxyethyl cellulose (NaCMHEC) are good drilling mud treatment agents and materials for preparing completion fluids, with high slurrying rate and salt resistance , Good anti-calcium performance, good viscosity-increasing ability, temperature resistance (160 ℃) property. It is suitable for preparing drilling fluids for fresh water, sea water and saturated salt water. It can be formulated into drilling fluids of various densities (103-127g/cm3) under the weight of calcium chloride, and it has a certain viscosity and low fluid loss. , its viscosity-increasing ability and fluid loss reducing ability are better than hydroxyethyl cellulose, and it is a good additive for increasing oil production.
Sodium carboxymethyl cellulose is a cellulose derivative widely used in the process of oil extraction, in terms of drilling fluid, cementing fluid, fracturing fluid and improving oil recovery It is used in all applications, especially in drilling fluids, where it is mainly used for fluid loss reduction and viscosification. Hydroxyethyl cellulose (HEC) is used as a mud thickening and stabilizing agent in the process of drilling, well completion and cementing. Compared with sodium carboxymethyl cellulose and guar gum, hydroxyethyl cellulose has good thickening effect, strong sand suspension, high salt capacity, good heat resistance, small mixing resistance, less liquid loss, and gel breaking. Block, low residue and other characteristics, has been widely used.
2. Construction and paint industry
Building masonry and plaster mortar admixture sodium carboxymethyl cellulose can be used as a retarder, water retention agent, thickener and binder, and can be used as a gypsum base It can also be used as dispersant, water retaining agent and thickener for plaster, mortar and ground leveling material of cement bottom layer. A special masonry and plastering mortar admixture made of carboxymethyl cellulose, which can improve the workability, water retention and crack resistance of the mortar, and avoid cracking and voids in the block wall. drum. Building surface decoration materials Cao Minggan et al. made an environmentally friendly building surface decoration material from methyl cellulose, the production process is simple and clean, and can be used for high-grade wall and stone tile surfaces, and can also be used for surface decoration of columns and monuments.
3. Daily chemical industry
The stabilizing viscosifier sodium carboxymethyl cellulose plays the role of dispersion and suspension stabilization in the paste products of solid powder raw materials, and plays the role of thickening and emulsification in liquid or emulsion cosmetics. Dispersion, homogenization and other functions. Can be used as a stabilizer and tackifier. Emulsion stabilizers are used as emulsifiers, thickeners and stabilizers for ointments and shampoos. Sodium carboxymethyl hydroxypropyl cellulose can be used as a stabilizer for toothpaste adhesives. It has good thixotropic properties, which makes toothpaste good in formability, long-term storage without deformation, and uniform and delicate taste. Sodium carboxymethyl hydroxypropyl cellulose has superior salt resistance and acid resistance, and its effect is far superior to that of carboxymethyl cellulose. It can be used as a thickener in detergents and an anti-stain agent. Dispersion thickener In the production of detergents, sodium carboxymethylcellulose is generally used as a dirt dispersant for washing powder, a thickener and a dispersant for liquid detergents.
4. Medicine and food industry
In the pharmaceutical industry, hydroxypropyl carboxymethylcellulose (HPMC) can be used as a drug excipient, widely used in oral drug matrix controlled-release and sustained-release preparations, as a release barrier The hysteresis material regulates the release of drugs, and is used as a coating material for sustained-release agents, sustained-release pellets, and sustained-release capsules. The most widely used are methyl carboxymethyl cellulose and ethyl carboxymethyl cellulose, such as MC, which are often used to make tablets and capsules, or to coat sugar-coated tablets. Premium grade cellulose ethers can be used in the food industry, and are effective thickeners, stabilizers, excipients, water retaining agents and mechanical foaming agents in various foods. Methylcellulose and hydroxypropylmethylcellulose have been recognized
Metabolically inert substances that are harmless to physiology. High-purity (above 99.5%) carboxymethylcellulose (CMC) can be added to food, such as milk and cream products, condiments, jams, jelly, canned food, table syrup and beverages. Carboxymethyl cellulose with a purity of more than 90% can be used in food-related aspects, such as the transportation and storage of fresh fruits. This kind of plastic wrap has the advantages of good fresh-keeping effect, less pollution, no damage, and easy mechanized production.
5. Optical and electrical functional materials
Electrolyte thickener stabilizer has good acid resistance and salt resistance due to the high purity of cellulose ether, especially the low content of iron and heavy metals, so it is formulated The colloid is very stable, suitable for thickening and stabilizing the electrolyte of alkaline batteries and zinc-manganese batteries. Many cellulose ethers exhibit thermotropic liquid crystallinity. Hydroxypropyl cellulose acetate forms thermotropic cholesteric liquid crystals below 164°C.
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