Introduction: Cellulose ether (CelluloseEther) is made of cellulose through the etherification reaction of one or several etherification agents and dry grinding. According to the different chemical structures of ether substituents, cellulose ethers can be divided into anionic, cationic and nonionic ethers. Ionic cellulose ethers mainly include carboxymethyl cellulose ether (CMC); non-ionic cellulose ethers mainly include methyl cellulose ether (MC), hydroxypropyl methyl cellulose ether (HPMC) and hydroxyethyl cellulose ether. Chlorine ether (HC) and so on. Non-ionic ethers are divided into water-soluble ethers and oil-soluble ethers, and non-ionic water-soluble ethers are mainly used in mortar products. In the presence of calcium ions, ionic cellulose ether is unstable, so it is rarely used in dry-mixed mortar products that use cement, slaked lime, etc. as cementing materials. Nonionic water-soluble cellulose ethers are widely used in the building materials industry because of their suspension stability and water retention.
According to the different etherification agents used in the etherification process, cellulose ether products include methyl cellulose, hydroxyethyl cellulose, hydroxyethyl methyl cellulose, cyanoethyl cellulose, carboxymethyl cellulose, Ethyl cellulose, benzyl cellulose, carboxymethyl hydroxyethyl cellulose, hydroxypropyl methyl cellulose, benzyl cyanoethyl cellulose and phenyl cellulose.
Cellulose ethers used in mortar generally include methyl cellulose ether (MC), hydroxypropyl methyl cellulose (HPMC), hydroxyethyl methyl cellulose ether (HEMC) and hydroxyethyl cellulose ether (HEMC) Among them, HPMC and HEMC are the most widely used.
1. Chemical properties of cellulose ethers
Each cellulose ether has the basic structure of cellulose —anhydroglucose structure. In the process of producing cellulose ether, the cellulose fiber is first heated in an alkaline solution, and then treated with an etherifying agent. The fibrous reaction product is purified and pulverized to form a uniform powder with a certain fineness.
In the production process of MC, only methyl chloride is used as an etherification agent; in addition to methyl chloride, propylene oxide is also used to obtain hydroxypropyl substituent groups in the production of HPMC. Various cellulose ethers have different methyl and hydroxypropyl substitution ratios, which affect the organic compatibility and thermal gelation temperature of cellulose ether solutions.
The number of substituent groups on the anhydroglucose structural unit of cellulose can be expressed by mass percentage or the average number of substituent groups (ie, degree of substitution DS—Degree of Substitution). The number of substituent groups determines the properties of cellulose ether products. The influence of the average degree of substitution on the solubility of etherified products is as follows:
(1) Etherification products with a low degree of substitution are easily soluble in lye;
(2) Etherification products with a slightly higher degree of substitution are easily soluble in water;
(3) Etherification products with a high degree of substitution are easily soluble in polar organic solvents;
(4) Etherification products with a higher degree of substitution are easily soluble in non-polar organic solvents.
2. Application Scenarios of Cellulose Ether
Cellulose ether is a non-ionic semi-synthetic polymer, which is water-soluble and solvent-soluble. It has different effects in different industries. For example, in chemical building materials, it has the following composite effects:
①Water retaining agent
②Thickener
③Leveling
④Film formation
⑤ Binder
In the polyvinyl chloride industry, it is an emulsifier and dispersant; in the pharmaceutical industry, it is a binder and a slow and controlled release framework material, etc. Because cellulose has a variety of composite effects, its application The field is also the most extensive. The following focuses on the use and function of cellulose ether in various building materials.
(1) In latex paint:
In the latex paint industry, to choose hydroxyethyl cellulose, the general specification of equal viscosity is RT30000-50000cps, which corresponds to the specification of HBR250, and the reference dosage is generally about 1.5‰-2‰. The main function of hydroxyethyl in latex paint is to thicken, prevent the gelation of the pigment, help the dispersion of the pigment, the stability of the latex, and increase the viscosity of the components, which contributes to the leveling performance of the construction: Hydroxyethyl cellulose is more convenient to use. It can be dissolved in cold water and hot water, and it is not affected by the pH value. It can be used with peace of mind when the PI value is between 2 and 12. The methods of use are as follows: I. Directly Adding in production: For this method, hydroxyethyl cellulose delayed type should be selected, and the hydroxyethyl cellulose with a dissolution time of more than 30 minutes is used. The steps are as follows: ① Put it in a container equipped with a high-shear agitator. Quantitative pure water ②Start stirring continuously at low speed, and at the same time slowly add hydroxyethyl into the solution evenly ③Continue to stir until all the granular materials are soaked ④Add other additives and alkaline additives, etc. ⑤Stir until all hydroxyethyl The base is completely dissolved, then add other components in the formula, and grind until the finished product. Ⅱ. Equipped with mother liquor for later use: This method can choose instant cellulose, which has anti-mildew effect. The advantage of this method is that it has greater flexibility and can be directly added to latex paint. The preparation method is the same as the steps ①-④. Ⅲ. Prepare porridge for later use: Since organic solvents are poor solvents (insoluble) for hydroxyethyl, these solvents can be used to prepare porridge. The most commonly used organic solvents are organic liquids in latex paint formulations, such as ethylene glycol, propylene glycol, and film-forming agents (such as diethylene glycol butyl acetate). The porridge hydroxyethyl cellulose can be directly added to the paint. Continue to stir until completely dissolved.
(2) In wall scraping putty:
At present, in most cities in my country, the water-resistant and scrub-resistant environment-friendly putty has been basically valued by people. It is produced by acetal reaction of vinyl alcohol and formaldehyde. Therefore, this material is gradually eliminated by people, and the cellulose ether series products are used to replace this material. That is to say, for the development of environmentally friendly building materials, cellulose is currently the only material. In the water-resistant putty, it is divided into two types: dry powder putty and putty paste. Among these two kinds of putty, modified methyl cellulose and hydroxypropyl methyl should be selected. The viscosity specification is generally between 30000-60000cps. The main functions of cellulose in putty are water retention, bonding and lubrication. Since the putty formulas of various manufacturers are different, some are gray calcium, light calcium, white cement, etc., and some are gypsum powder, gray calcium, light calcium, etc., so the specifications, viscosity and penetration of cellulose in the two formulas are also different. The amount added is about 2‰-3‰. In the construction of wall scraping putty, since the base surface of the wall has a certain degree of water absorption (the water absorption rate of the brick wall is 13%, and the water absorption rate of the concrete is 3-5%), coupled with the evaporation of the outside world, if the putty loses water too quickly , It will lead to cracks or powder removal, which will weaken the strength of the putty. Therefore, adding cellulose ether will solve this problem. But the quality of the filler, especially the quality of ash calcium is also extremely important. Due to the high viscosity of cellulose, the buoyancy of the putty is also enhanced, and the sagging phenomenon during construction is also avoided, and it is more comfortable and labor-saving after scraping. It is more convenient to add cellulose ether in the powder putty. Its production and use are more convenient. The filler and additives can be evenly mixed in dry powder.
(3) Concrete mortar:
In concrete mortar, to achieve the ultimate strength, the cement must be fully hydrated. Especially in summer construction, the concrete mortar loses water too quickly, and the measures of complete hydration are used to maintain and sprinkle water. Waste of resources and inconvenient operation, the key is that the water is only on the surface, and the internal hydration is still incomplete, so the solution to this problem is to add eight water-retaining agents to the mortar concrete, generally choose hydroxypropyl methyl or methyl Cellulose, the viscosity specification is between 20000-60000cps, and the addition amount is 2%-3%. The water retention rate can be increased to more than 85%. The method of use in mortar concrete is to mix the dry powder evenly and pour it into the water.
(4) In plastering gypsum, bonded gypsum, caulking gypsum:
With the rapid development of the construction industry, people’s demand for new building materials is also increasing day by day. Due to the increase in people’s awareness of environmental protection and the continuous improvement of construction efficiency, cementitious gypsum products have developed rapidly. At present, the most common gypsum products are plastering gypsum, bonded gypsum, inlaid gypsum, and tile adhesive. Plastering gypsum is a high-quality plastering material for interior walls and ceilings. The wall surface plastered with it is fine and smooth. The new building light board adhesive is a sticky material made of gypsum as the base material and various additives. It is suitable for bonding between various inorganic building wall materials. It is non-toxic, Odorless, early strength and fast setting, strong bonding and other characteristics, it is a supporting material for building boards and block construction; gypsum caulking agent is a gap filler between gypsum boards and a repair filler for walls and cracks. These gypsum products have a series of different functions. In addition to the role of gypsum and related fillers, the key issue is that the added cellulose ether additives play a leading role. Since gypsum is divided into anhydrous gypsum and hemihydrate gypsum, different gypsum has different effects on the performance of the product, so thickening, water retention and retardation determine the quality of gypsum building materials. The common problem of these materials is hollowing and cracking, and the initial strength cannot be reached. To solve this problem, it is to choose the type of cellulose and the compound utilization method of the retarder. In this regard, methyl or hydroxypropyl methyl 30000 is generally selected. –60000cps, the addition amount is 1.5%–2%. Among them, cellulose focuses on water retention and retarding lubrication. However, it is impossible to rely on cellulose ether as a retarder, and it is necessary to add a citric acid retarder to mix and use without affecting the initial strength. Water retention generally refers to how much water will be lost naturally without external water absorption. If the wall is too dry, water absorption and natural evaporation on the base surface will make the material lose water too quickly, and hollowing and cracking will also occur. This method of use is mixed with dry powder. If you prepare a solution, please refer to the preparation method of the solution.
(5) Thermal insulation mortar
Insulation mortar is a new type of interior wall insulation material in the northern region. It is a wall material synthesized by insulation material, mortar and binder. In this material, cellulose plays a key role in bonding and increasing strength. Generally choose methyl cellulose with high viscosity (about 10000eps), the dosage is generally between 2‰-3‰), and the method of use is dry powder mixing.
(6) interface agent
Choose HPNC 20000cps as the interface agent, choose 60000cps or more as the tile adhesive, and use the thickener as the interface agent, which can improve the tensile strength and anti-arrow strength. Used as a water-retaining agent in the bonding of tiles to prevent tiles from dehydrating too quickly and falling off.
3. Industry chain situation
(1) Upstream industry
The main raw materials required for the production of cellulose ether include refined cotton (or wood pulp) and some common chemical solvents, such as propylene oxide, methyl chloride, liquid caustic soda, caustic soda, ethylene oxide, toluene and other auxiliary materials. The upstream industry enterprises of this industry include refined cotton, wood pulp production enterprises and some chemical enterprises. The price fluctuations of the above-mentioned main raw materials will have varying degrees of impact on the production cost and selling price of cellulose ether.
The cost of refined cotton is relatively high. Taking building material grade cellulose ether as an example, during the reporting period, the cost of refined cotton accounted for 31.74%, 28.50%, 26.59% and 26.90% of the sales cost of building material grade cellulose ether respectively. The price fluctuation of refined cotton will affect the production cost of cellulose ether. The main raw material for the production of refined cotton is cotton linters. Cotton linters are one of the by-products in the cotton production process, mainly used to produce cotton pulp, refined cotton, nitrocellulose and other products. The use value and use of cotton linters and cotton are quite different, and its price is obviously lower than that of cotton, but it has a certain correlation with the price fluctuation of cotton. Fluctuations in the price of cotton linters affect the price of refined cotton.
The sharp fluctuations in the price of refined cotton will have different degrees of impact on the control of production costs, product pricing and profitability of enterprises in this industry. When the price of refined cotton is high and the price of wood pulp is relatively cheap, in order to reduce costs, wood pulp can be used as a substitute and supplement for refined cotton, mainly for the production of cellulose ethers with low viscosity such as pharmaceutical and food grade cellulose ethers. According to the data from the website of the National Bureau of Statistics, in 2013, my country’s cotton planting area was 4.35 million hectares, and the national cotton output was 6.31 million tons. According to statistics from the China Cellulose Industry Association, in 2014, the total output of refined cotton produced by major domestic refined cotton manufacturers was 332,000 tons, and the supply of raw materials is abundant.
The main raw materials for the production of graphite chemical equipment are steel and graphite carbon. The price of steel and graphite carbon accounts for a relatively high proportion of the production cost of graphite chemical equipment. Price fluctuations of these raw materials will have a certain impact on the production cost and selling price of graphite chemical equipment.
(2) Downstream industry of cellulose ether
As “industrial monosodium glutamate”, cellulose ether has a low proportion of cellulose ether and has a wide range of applications. The downstream industries are scattered in all walks of life in the national economy.
Normally, the downstream construction industry and real estate industry will have a certain impact on the growth rate of demand for building material grade cellulose ether. When the domestic construction industry and real estate industry are growing rapidly, the domestic market demand for building material grade cellulose ether is growing rapidly. When the growth rate of the domestic construction industry and real estate industry slows down, the growth rate of demand for building material grade cellulose ether in the domestic market will slow down, which will intensify the competition in this industry and accelerate the process of survival of the fittest among enterprises in this industry.
Since 2012, in the context of the slowdown in the domestic construction industry and real estate industry, the demand for building material grade cellulose ether in the domestic market has not fluctuated significantly. The main reasons are: 1. The overall scale of the domestic construction industry and real estate industry is large, and the total market demand is relatively large; the main consumer market of building material grade cellulose ether is gradually expanding from economically developed areas and first- and second-tier cities to the central and western regions and third-tier cities , domestic demand growth potential and space expansion; 2. The amount of cellulose ether added accounts for a low proportion of the cost of building materials. The amount used by a single customer is small, and customers are scattered, which is prone to rigid demand. The total demand in the downstream market is relatively stable; 3. The change of market price is an important factor affecting the demand structure change of building material grade cellulose ether. Since 2012, the selling price of building material grade cellulose ether has dropped greatly, which has caused a large drop in the price of mid-to-high-end products and attracted more customers to purchase and choose , increasing the demand for mid-to-high-end products, and squeezing the market demand and price space for ordinary models.
The degree of development of the pharmaceutical industry and the growth rate of the pharmaceutical industry will affect the demand for pharmaceutical grade cellulose ether. The improvement of people’s living standards and the developed food industry are conducive to driving the market demand for food-grade cellulose ether.