Cellulose ether is a non-ionic semi-synthetic high molecular 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 property ④Film forming property ⑤Binder
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 safely between PI value 2 and 12. The methods of use are as follows:
I. Add directly in production: this method should choose hydroxyethyl cellulose delayed type, and the hydroxyethyl cellulose with a dissolution time of more than 30 minutes, its use steps are as follows:
①Prepare a quantitative amount of purified water in a container with a high-shear agitator
②Start to stir continuously at a low speed, and at the same time slowly add hydroxyethyl to the solution evenly
③Continue to stir until all the granular materials are soaked
④ Add other additives and basic additives, etc.
⑤ Stir until all the hydroxyethyl groups are 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 for the interface agent, choose 60000cps or more for the tile adhesive, and focus on the thickener in 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.
Post time: Feb-16-2023