Cellulose ether is a general name for a variety of derivatives made from cellulose through etherification reaction and drying and grinding. According to different ionization properties, cellulose ethers can be divided into ionic, non-ionic and mixed types. Among them, ionic cellulose ethers are the mainstream products in the market, accounting for about 60%. Subdivided products include carboxymethyl cellulose ethers; 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 and are excellent in temperature resistance, It is better than the ionic type in terms of salt tolerance and other aspects, and has good market development prospects.
Cellulose ether has two types: water-soluble and solvent-based. As a high molecular polymer, cellulose ether has a wide range of applications. It can be used as a water-retaining agent, emulsifier, dispersant, etc. Agents, thickeners, binders, etc. are used in construction and building materials, oil exploration, food, medicine, daily chemicals and other fields. At present, domestic cellulose ethers are mainly building material grade products, with pharmaceutical grade and food grade products accounting for a lower proportion. However, with the development of the biomedical industry and the advancement of production technology, the market development potential of pharmaceutical grade cellulose ethers is greater.
Performance and characteristics of cellulose ether
1.Appearance features
Cellulose ether is generally a white or milky white, odorless, non-toxic, fluid fibrous powder that absorbs moisture easily and dissolves in water into a transparent, viscous and stable colloid. .
2. Film-forming and adhesive properties
The etherification of cellulose ether has a great impact on its properties and properties, such as solubility, film-forming ability, bonding 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. It can be used to manufacture plastics, films, varnishes, adhesives, latex and Drug coating materials, etc.
3.Solubility
Methyl cellulose is soluble in cold water, insoluble in hot water, and also soluble in some organic solvents; methyl hydroxyethyl cellulose is soluble in cold water, but insoluble in hot water and organic solvents. Solvent. However, when the aqueous solution of methylcellulose and methylhydroxyethylcellulose is heated, methylcellulose and methylhydroxyethylcellulose will precipitate. Methyl cellulose precipitates at 45-60°C, while the precipitation temperature of mixed etherified methyl hydroxyethyl cellulose increases to 65-80°C. When the temperature decreases, the precipitates redissolve. Hydroxyethyl cellulose and sodium carboxymethyl hydroxyethyl cellulose are soluble in water at any temperature and insoluble in organic solvents.
4. Thickening
Cellulose ether is dissolved in water in colloidal form, 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 the solution is different from that of Newtonian fluids, but shows a behavior that changes with the change of 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 carboxymethylcellulose is mainly used in petroleum mining. It is used when making mud to increase viscosity and reduce water loss. It can resist various soluble salt pollution. Improve 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 pulping rate and salt resistance. , Good anti-calcium properties, good viscosity-increasing ability, and temperature resistance (160°C). It is suitable for preparing fresh water, seawater and saturated salt water drilling fluids. It can be made into drilling fluids with various densities (103~127g/cm3) under the aggravation of calcium chloride, and has a certain viscosity and low filter loss. , its viscosity-increasing ability and filter 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 oil extraction process. It is used in drilling fluids, cementing fluids, fracturing fluids and increasing oil production. They are all used in drilling fluids, especially in drilling fluids where they are used in large amounts to reduce fluid loss and increase viscosity. Hydroxyethyl cellulose (HEC) is used as a mud thickening stabilizer in the drilling, completion, and cementing processes. Compared with carboxymethyl cellulose sodium, guar gum, etc., hydroxyethyl cellulose has good thickening effect, strong sand suspension, high salt capacity, good heat resistance, small mixing resistance, less liquid loss, and gel breaking. It has the characteristics of low lumps and residue and has been widely used.
2. Construction and coating industry
Sodium carboxymethyl cellulose, a mortar admixture for building masonry and plastering, can be used as a retardant, water-retaining agent, thickener and binder, and can be used as a gypsum base layer It can also be used as a dispersant, water retaining agent and thickening agent for plaster, mortar and floor screed materials on the cement base. A special masonry and plastering mortar admixture for aerated concrete blocks made of carboxymethyl cellulose. It 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 Mingqian and others used methylcellulose to make an environmentally friendly building surface decoration material, the production process is simple and clean, and can be used for high-end walls and stone tile surfaces, as well as for surface decoration of columns and monuments.
3. Daily chemicals industry
The stabilizing thickener sodium carboxymethyl cellulose plays a role in dispersion and suspension stabilization in pasty products made of solid powder materials, and plays a thickening and stabilizing role in liquid or emulsion cosmetics. Dispersion, homogenization and other functions. Can be used as stabilizer and tackifier. Emulsion stabilizer is used as emulsifier, tackifier and stabilizer for ointments and shampoos. Sodium carboxymethyl hydroxypropyl cellulose can be used as a toothpaste adhesive stabilizer. It has good thixotropic properties, making the toothpaste good in formability, stable in shape for a long time, and has a uniform and delicate taste. Sodium carboxymethyl hydroxypropyl cellulose has excellent salt resistance and acid resistance, and its effect is far better than that of carboxymethyl cellulose. It can be used as a tackifier in detergents and an anti-fouling agent. Dispersing Thickening Agent In the production of detergents, sodium carboxymethyl cellulose is generally used as a dirt dispersing agent for washing powder and a thickening agent and dispersing agent for liquid detergents.
4. Medicine and food industry
In the pharmaceutical industry, hydroxypropylcarboxymethylcellulose (HPMC) can be used as a pharmaceutical excipient and is widely used in oral drug matrix controlled-release and sustained-release preparations as a release barrier. Hysteresis materials regulate the release of drugs and are used as coating materials for sustained-release agents, sustained-release pellets, and sustained-release capsules. The most commonly used ones are methylcarboxymethylcellulose and ethylcarboxymethylcellulose. MC, for example, is often used to make tablets and capsules, or to coat sugar-coated tablets. High-quality 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. Methyl cellulose and hydroxypropyl methyl cellulose are already recognized
A metabolically inert substance that is physiologically harmless. High-purity (purity above 99.5%) carboxymethylcellulose (CMC) can be added to food products, such as milk and cream products, condiments, jams, jelly, cans, table syrups 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 preservation effect, less pollution, no damage, and easy mechanized production.
5. Optical and electrical functional materials
Electrolyte thickening stabilizer is formulated due to the high purity of cellulose ether, good acid resistance and salt resistance, especially the low content of iron and heavy metals. The colloid is very stable and is suitable as an electrolyte thickening stabilizer for alkaline batteries and zinc-manganese batteries. Many cellulose ethers exhibit thermotropic liquid crystallinity. Hydroxypropylcellulose acetate forms thermotropic cholesteric liquid crystal below 164°C.
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