Characteristics, preparation and application of cellulose ether in industry

The types, preparation methods, properties and characteristics of cellulose ether were reviewed, as well as the applications of cellulose ether in petroleum, construction, papermaking, textile, medicine, food, photoelectric materials and daily chemical industry. Some new varieties of cellulose ether derivatives with development prospects were introduced and their application prospects were prospeced.

Key words: cellulose ether; Performance; Application; Cellulose derivatives

Cellulose is a kind of natural polymer compound. Its chemical structure is a polysaccharide macromolecule with anhydrous β-glucose as the base ring, with one primary hydroxyl group and two secondary hydroxyl groups on each base ring. By chemical modification, a series of cellulose derivatives can be obtained, cellulose ether is one of them. Cellulose ether is obtained by the reaction of cellulose and NaOH, and then etherize with various functional monomers such as methane chloride, ethylene oxide, propylene oxide, etc., by washing the by-product salt and sodium cellulose. Cellulose ether is an important derivative of cellulose, can be widely used in medicine and health, daily chemical, paper, food, medicine, construction, materials and other industries. Therefore, the development and utilization of cellulose ether has positive significance for the comprehensive utilization of renewable biomass resources, the development of new materials and new technologies.

1. Classification and preparation of cellulose ether

The classification of cellulose ethers is generally divided into four categories according to their ionic properties.

1.1 Nonionic cellulose ether

Non-ionic cellulose ether is mainly cellulose alkyl ether, the preparation method is by cellulose and NaOH reaction, and then with a variety of functional monomers such as methane chloride, ethylene oxide, propylene oxide etherification reaction, and then by washing the by-product salt and sodium cellulose to get. The main methyl cellulose ether, methyl hydroxyethyl cellulose ether, methyl hydroxypropyl cellulose ether, hydroxyethyl cellulose ether, cyanoethyl cellulose ether, hydroxybutyl cellulose ether. Its application is very wide.

1.2 Anionic cellulose ether

Anionic cellulose ether is mainly carboxymethyl cellulose sodium, carboxymethyl hydroxyethyl cellulose sodium. The preparation method is by the reaction of cellulose and NaOH, and then etherify with monochloroacetic acid or ethylene oxide, propylene oxide, and then wash the by-product salt and sodium cellulose to get.

1.3 cationic cellulose ether

Cationic cellulose ether is mainly 3 – chlorine – 2 – hydroxypropyl trimethyl ammonium chloride cellulose ether. The preparation method is by the reaction of cellulose and NaOH, and then the cationic etherifying agent 3 – chlorine – 2 – hydroxypropyl trimethyl ammonium chloride or ethylene oxide, propylene oxide together with etherifying reaction, and then by washing the by-product salt and sodium cellulose to get.

1.4 Zwitterionic cellulose ether

Zwitterionic cellulose ether has both anionic groups and cationic groups on the molecular chain, the preparation method is by cellulose and NaOH reaction, and then with a chloroacetic acid and cationic etherifying agent 3 – chlorine – 2 hydroxypropyl trimethyl ammonium chloride etherification reaction, and then washed by by-product salt and sodium cellulose and obtained.

2.the properties and characteristics of cellulose ether

2.1 Appearance Features

Cellulose ether is generally white or milky white, tasteless, non-toxic, with fluidity of fibrous powder, easy to absorb moisture, dissolved in water into a transparent viscous stable colloid.

2.2 Film formation and adhesion

The etherification of cellulose ether has great influence on its properties, such as solubility, film forming ability, bond strength and salt tolerance. Cellulose ether has high mechanical strength, flexibility, heat resistance and cold resistance, and has good compatibility with a variety of resins and plasticizers, can be used to manufacture plastics, films, varnishes, adhesives, latex and pharmaceutical coating materials.

2.3 Solubility

Methyl cellulose soluble in cold water, insoluble in hot water, but also soluble in some organic solvents; Methyl hydroxyethyl cellulose soluble in cold water, insoluble in hot water and organic solvents. But when the aqueous solution of methyl cellulose and methyl hydroxyethyl cellulose is heated, the methyl cellulose and methyl hydroxyethyl cellulose will precipitate out. Methyl cellulose precipitated at 45 ~ 60℃, while mixed etherized methyl hydroxyethyl cellulose precipitated at 65 ~ 80℃. When the temperature drops, the precipitates redissolve.

Sodium hydroxyethyl cellulose and carboxymethyl hydroxyethyl cellulose are soluble in water at any temperature, but insoluble in organic solvents (with a few exceptions).

2.4 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 macromolecules of hydration. Due to the entanglement of macromolecules, the flow behavior of the solution is different from that of Newtonian fluids, but exhibits a behavior that varies with the change of shear forces. Due to the macromolecular structure of cellulose ether, the viscosity of solution increases rapidly with increasing concentration and decreases rapidly with increasing temperature.

2.5 Degradability

Cellulose ether is used in the aqueous phase. As long as water is present, bacteria will grow. The growth of bacteria leads to the production of enzyme bacteria. The enzyme bacteria made the unsubstituted dehydrated glucose unit bond adjacent to cellulose ether break and the molecular weight of polymer decreased. Therefore, if an aqueous solution of cellulose ether is to be preserved for a longer period of time, a preservative should be added to it, even if antibacterial cellulose ether is used.

3.the application of cellulose ether in industry

3.1 Petroleum Industry

Sodium carboxymethyl cellulose is mainly used in petroleum exploitation. It is used in the manufacture of mud to increase viscosity and reduce water loss. It can resist various soluble salt pollution and improve oil recovery rate.

Sodium carboxymethyl hydroxypropyl cellulose and sodium carboxymethyl hydroxyethyl cellulose are a kind of better drilling mud treatment agent and preparation of completion fluid materials, high pulping rate, salt resistance, calcium resistance, good viscosification ability, temperature resistance (160℃). Suitable for preparation of fresh water, sea water and saturated salt water drilling fluid, under the weight of calcium chloride can be mixed into a variety of densities (103 ~ 1279 / cm3) drilling fluid, and make it has a certain viscosity and low filtration capacity, its viscosity and filtration capacity are better than hydroxyethyl cellulose, is a good oil production additives. Sodium carboxymethyl cellulose is widely used in the process of petroleum exploitation of cellulose derivatives, in drilling fluid, cementing fluid, fracturing fluid and improve oil production are used, especially in the drilling fluid consumption is larger, the main takeoff and landing filtration and viscosification.

Hydroxyethyl cellulose is used in the process of drilling, completion and cementing as a mud thickening stabilizer. Because hydroxyethyl cellulose and sodium carboxymethyl cellulose, guar gum compared with good thickening effect, suspension sand, high salt content, good heat resistance, and small resistance, less liquid loss, broken rubber block, low residue characteristics, has been widely used.

3.2 Construction and coating industry

Building building and plastering mortar admixture: sodium carboxymethyl cellulose can be used as retarding agent, water retention agent, thickener and binder, can be used as gypsum bottom and cement bottom plaster, mortar and ground leveling material dispersant, water retention agent, thickener. It is a kind of special masonry and plastering mortar admixture for aerated concrete blocks made of carboxymethyl cellulose, which can improve the workability, water retention and crack resistance of mortar and avoid the cracking and hollow of the block wall.

Building surface decoration materials: Cao Mingqian and other methyl cellulose made of a kind of environmental protection building surface decoration materials, its production process is simple, clean, can be used for high-grade wall, stone tile surface, can also be used for column, tablet surface decoration. Huang Jianping made of carboxymethyl cellulose is a kind of ceramic tile sealant, which has strong bonding force, good deformation ability, does not produce cracks and fall off, good waterproof effect, bright and colorful color, with excellent decorative effect.

Application in coatings: Methyl cellulose and hydroxyethyl cellulose can be used as stabilizer, thickener and water retaining agent for latex coatings, in addition, can also be used as dispersant, viscosifier and film forming agent for colored cement coatings. Adding cellulose ether with appropriate specifications and viscosity to latex paint can improve the construction performance of latex paint, prevent spatter, improve storage stability and cover power. The main consumer field abroad is latex coatings, therefore, cellulose ether products often become the first choice of latex paint thickener. For example, the modified methyl hydroxyethyl cellulose ether can keep the leading position in the thickener of latex paint because of its good comprehensive properties. For example, because cellulose ether has unique thermal gel characteristics and solubility, salt resistance, heat resistance, and has appropriate surface activity, can be used as a water retention agent, suspension agent, emulsifier, film forming agent, lubricant, binder and rheological amendment.

3.3 Paper Industry

Paper wet additives: CMC can be used as a fiber dispersant and paper enhancer, can be added to the pulp, because sodium carboxymethyl cellulose and pulp and packing particles have the same charge, can increase the evenness of the fiber, improve the strength of the paper. As a reinforcer added inside the paper, it increases the bond cooperation between the fibers, and can improve the tensile strength, break resistance, paper evenness and other physical indexes. Sodium carboxymethyl cellulose can also be used as sizing agent in the pulp. In addition to its own sizing degree, it can also be used as a protective agent of rosin, AKD and other sizing agents. Cationic cellulose ether can also be used as paper retention aid filter, improve the retention rate of fine fiber and filler, can also be used as paper reinforcement.

Coating adhesive: Used for coating processing paper coating adhesive, can replace cheese, part of the latex, so that printing ink easy to penetrate, clear edge. It can also be used as pigment dispersant, viscosifier and stabilizer.

Surface sizing agent: Sodium carboxymethyl cellulose can be used as paper surface sizing agent, improve the surface strength of paper, compared with the current use of polyvinyl alcohol, modified starch after the surface strength can be increased by about 10%, the dosage is reduced by about 30%. It is a promising surface sizing agent for papermaking, and its series of new varieties should be developed actively. Cationic cellulose ether has better surface sizing performance than cationic starch, not only can improve the surface strength of paper, but also can improve the ink absorption of paper, increase the dyeing effect, is also a promising surface sizing agent.

3.4 Textile industry

In textile industry, cellulose ether can be used as sizing agent, levelling agent and thickening agent for textile pulp.

Sizing agent: cellulose ether such as sodium carboxymethyl cellulose, hydroxyethyl carboxymethyl cellulose ether, hydroxypropyl carboxymethyl cellulose ether and other varieties can be used as sizing agent, and not easy to deteriorate and mold, printing and dyeing, without desizing, promote dye can obtain uniform colloid in water.

Levelling agent: can enhance the hydrophilic and osmotic power of dye, because the viscosity change is small, easy to adjust the color difference; Cationic cellulose ether also has dyeing and coloring effect.

Thickening agent: sodium carboxymethyl cellulose, hydroxyethyl carboxymethyl cellulose ether, hydroxypropyl carboxymethyl cellulose ether can be used as a printing and dyeing slurry thickening agent, with small residue, high color rate characteristics, is a class of very potential textile additives.

3.5 Household chemicals industry

Stable viscosifier: Sodium methylcellulose in solid powder raw material paste products play a dispersion suspension stability, in liquid or emulsion cosmetics thickening, dispersing, homogenizing and other roles. It can be used as stabilizer and viscosifier.

Emulsifying stabilizer: do ointment, shampoo emulsifier, thickening agent and stabilizer. Sodium carboxymethyl hydroxypropyl cellulose can be used as a toothpaste adhesive stabilizer, with good thixotropic properties, so that the toothpaste has good formability, long-term deformation, uniform and delicate taste. Sodium carboxymethyl hydroxypropyl cellulose salt resistance, acid resistance is superior, the effect is far better than carboxymethyl cellulose, can be used as detergent in the viscosifier, dirt attachment prevention agent.

Dispersion thickener: In detergent production, the general use of sodium carboxymethyl cellulose as detergent detergent dirt dispersant, liquid detergent thickener and dispersant.

3.6 Pharmaceutical and food industries

In the pharmaceutical industry, hydroxypropyl carboxymethyl cellulose can be used as drug excipients, widely used in oral drug skeleton controlled release and sustained release preparations, as a release blocking material to regulate the release of drugs, as coating material sustained release agent, sustained release pellets, sustained release capsules. The most widely used is methyl carboxymethyl cellulose, ethyl carboxymethyl cellulose, such as MC is often used in the manufacture of tablets and capsules, or coated sugar-coated tablets.

Quality grade of cellulose ether can be used in the food industry, in a variety of food is an effective thickening agent, emulsifier, stabilizer, excipient, water retaining agent and mechanical foaming agent. Methyl cellulose and hydroxypropyl methyl cellulose have been recognized as non-harmful metabolic inert substances. High purity (99.5% or more purity) carboxymethyl cellulose can be added to foods, such as milk and cream products, condiments, jams, jelly, cans, table syrups and beverages. Purity of more than 90% carboxymethyl cellulose can be used in food-related aspects, such as applied to the transportation and storage of fresh fruit, the plastic wrap has good preservation effect, less pollution, no damage, easy to mechanized production advantages.

3.7 Optical and electrical functional materials

Electrolyte thickening stabilizer: due to the high purity of cellulose ether, good acid resistance, salt resistance, especially iron and heavy metal content is low, so the colloid is very stable, suitable for alkaline battery, zinc manganese battery electrolyte thickening stabilizer.

Liquid crystal materials: Since 1976, the first discovery of hydroxypropyl cellulose – water system liquid crystal ask phase, has been found in suitable organic solution, many cellulose derivatives in high concentration can form anisotropic solution, for example, hydroxypropyl cellulose and its acetate, propionate, benzoate, phthalate, acetyxyethyl cellulose, hydroxyethyl cellulose, etc. In addition to forming colloidal ionic liquid crystal solution, some esters of hydroxypropyl cellulose also show this property.

Many cellulose ethers show thermotropic liquid crystal properties. Acetyl hydroxypropyl cellulose formed thermogenic cholesteric liquid crystal below 164℃. Acetoacetate hydroxypropyl cellulose, trifluoroacetate hydroxypropyl cellulose, hydroxypropyl cellulose and its derivatives, ethyl hydroxypropyl cellulose, trimethylsiliccellulose and butyldimethylsiliccellulose, heptyl cellulose and butoxylethyl cellulose, hydroxyethyl cellulose acetate, etc., all showed thermogenic cholesteric liquid crystal. Some cellulose esters such as cellulose benzoate, p-methoxybenzoate and p-methylbenzoate, cellulose heptanate can form thermogenic cholesteric liquid crystals.

Electrical insulation material: cyanoethyl cellulose etherifying agent for acrylonitrile, its high dielectric constant, low loss coefficient, can be used as phosphorus and electroluminescent lamps resin matrix and transformer insulation.

4. Closing Remarks

Using chemical modification to obtain cellulose derivatives with special functions is an effective way to find new uses for cellulose, the largest natural organic matter in the world. As one of cellulose derivatives, cellulose ether such as physiological harmless, pollution-free water-soluble polymer materials because of its excellent properties, has been used in many industries, and will have a broader prospect for development.