Cellulose ether is a non-ionic, semi-synthetic polymer that 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:
① water retention agent ② thickener ③ leveling ④ film-forming ⑤ binder
In the polyvinyl chloride industry, it is an emulsifier and dispersant; in the pharmaceutical industry, it is a binder and controlled-release matrix material. Because cellulose has a variety of complex functions, it has the widest range of applications.

The use and function of cellulose ethers in various building materials:

1. In latex paints:
In the latex paint industry, hydroxyethyl cellulose should be selected. The general specifications for viscosity are RT30000-50000cps, which corresponds to the HBR250 specification. The reference dosage is generally about 1.5‰-2‰. The main function of hydroxyethyl in latex paint is to thicken, prevent pigment gelation, help disperse the pigment, stabilise the latex, and increase the viscosity of the components, which helps the leveling properties of the paint during application. Hydroxyethyl cellulose is easy to use, dissolves in cold and hot water, and is not affected by pH. It can be used safely at a PI value of 2 to 12. There are three ways to use it:
I. Directly adding it during production: For this method, you should choose a hydroxyethyl cellulose delayed type with a dissolution time of more than 30 minutes. The steps are as follows:
①Prepare a container with a high-speed blender, add a fixed amount of purified water
②Start stirring at low speed, while slowly adding the hydroxyethyl evenly to the solution
③Continue stirring until all the granular materials are thoroughly wet
④ Add other additives and alkaline additives, etc.
⑤ Stir until all the hydroxyethyl groups are completely dissolved, then add the other components of the formula and grind until the finished product is obtained.
II. Preparation of mother liquor for later use: This method can use instant-dissolving type and has a mildew-proof effect cellulose. 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 steps ① to ④.
III. Preparation of gruel for later use: Since organic solvents are poor solvents (insoluble) for hydroxyethyl, these solvents can be used to prepare gruel. The most commonly used organic solvent is the organic liquid in the latex paint formula, such as glycol, propylene glycol and film-forming agents (such as diethylene glycol butyl acetate). The hydroxyethyl cellulose can be directly added to the paint, and the mixture should be stirred until completely dissolved.

2.In wall putty:
At present, environmentally friendly putty that is water-resistant and scrub-resistant has basically been valued by people. Water-resistant putty is divided into dry powder putty and putty cream. Among these two types of putty, modified methyl cellulose and hydroxypropyl methyl cellulose are generally selected. The viscosity specifications are generally between 30,000 and 60,000 cps, which is most suitable. The main functions of cellulose in putty are water retention, adhesion, lubrication, etc. Since the putty formulas of different manufacturers are different, some contain grey calcium, light calcium, white cement, etc., while others contain gypsum powder, grey calcium, light calcium, etc., the viscosity and amount of cellulose selected for the two formulas are also different. The general addition amount is about 2‰-3‰. In the application of wall putty, as the base surface of the wall has a certain degree of water absorption (the water absorption rate of brick walls is 13%, and that of concrete is 3-5%), coupled with evaporation from the outside, if the putty loses water too quickly, it will lead to cracking or powder loss, thereby weakening the strength of the putty. However, the quality of the filler, especially the quality of the calcium oxide, is also extremely important.
Because cellulose has a high viscosity, it also enhances the adhesion of the putty and prevents sagging during application. It is also easier and more comfortable to apply. Cellulose ether should be added in powdered putty in appropriate amounts. It is easy to produce and use. Just mix the filler and additives together with the dry powder, and it is also easy to apply. Mix the water on site and use as much as needed.

3. Concrete mortar:
In concrete mortar, the final strength can only be achieved if the cement has completely reacted with water. This is especially true during summer construction, when concrete mortar loses water too quickly. The solution is to sprinkle the surface with water to encourage complete hydration. However, this method wastes water and is inconvenient to use. The key is that the water is only on the surface, while the internal hydration is still incomplete. Therefore, the solution to this problem is to add 8 water retention agents to the mortar concrete, generally choosing hydroxypropyl methyl or methyl cellulose, with a viscosity of between 20,000 and 60,000 cps and an addition amount of 2% to 3%. The water retention rate can be increased to over 85%. The method of use in mortar concrete is to mix the dry powder evenly and then add water.

4. In plastering gypsum, cementitious plaster and jointing plaster:
With the rapid development of the construction industry, the demand for new building materials is also increasing day by day. Due to people’s increasing awareness of environmental protection and the continuous improvement of construction efficiency, gypsum products have developed rapidly. At present, the most common gypsum products are plastering gypsum, cementitious plaster, jointing plaster, tile adhesives, etc. Plastering plaster is a high-quality interior wall and ceiling plastering material. It produces a smooth, delicate finish, does not crumble or fall off, adheres firmly to the substrate, and has fire-resistant properties. Adhesive plaster is a new type of construction board adhesive. It is made from plaster as the base material and various additives and made of a viscous material. It is suitable for bonding various inorganic building wall materials. It is non-toxic, tasteless, has the characteristics of early strength and quick setting, and strong adhesion. It is a supporting material for building board and block construction. Gypsum caulk is a filler for the gaps between gypsum boards and a repair filler for walls and cracks.
These gypsum products have a range of different functions. Apart from the role played by the gypsum and related fillers, the key issue is the dominant role played by the added cellulose ether additives. As gypsum is divided into anhydrite and hemihydrate, different gypsum has a different impact on the performance of the product, so thickening, water retention and retardation determine the quality of gypsum building materials. A common problem with these materials is hollowing and cracking, and the initial strength cannot be achieved. The solution to this problem is to choose the type of cellulose and the method of using retarders in combination. In this regard, methyl or hydroxypropyl methyl 30,000-60,000 cps is generally selected, and the addition amount is between 1.5% and 2%. The focus of cellulose is to retain water and slow down the setting process and provide lubrication. However, it is not possible to rely on cellulose ether as a retarder in this case. A citric acid retarder must also be added. After mixing, it will not affect the initial strength.
The water retention rate generally refers to the amount of natural water loss in the absence of external water absorption. If the wall dries out, the base surface will lose water too quickly due to water absorption and natural evaporation, which will also lead to hollowing and cracking. This method of application uses dry powder mixing. If you want to prepare a solution, please refer to the solution preparation method.

5. Insulation mortar
Insulation mortar is a type of wall material composed of insulation material, mortar and a binder. Cellulose plays a key role in this material, bonding and increasing strength. Generally, methyl cellulose with high viscosity (around 10,000 eps) is selected, and the dosage is generally between 2‰ and 3‰. The method of application is dry powder mixing.

6. Interface agent
The interface agent is HPNC 20000 cps, and the tile adhesive is 60000 cps or higher. It is used as a thickener to improve tensile strength and impact strength. It is also used as a water retention agent in tile adhesives to prevent tiles from falling off due to excessive water loss.