Cellulose ether is a kind of non-ionic semi-synthetic high molecular polymer. It has two kinds of water-soluble and solvent-based properties. 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-forming ⑤Binder; in the PVC industry, it is an emulsifier and dispersant; in the pharmaceutical industry, it is a binder and Because cellulose has a variety of composite effects, it is also the most widely used. Below I will focus on the use and function of cellulose ethers in environmentally friendly building materials.
1. In latex paint
In the latex paint industry, hydroxyethyl cellulose should be selected. The general specification of viscosity is RT30000-50000cps, and the reference dosage is generally about 1.5‰-2‰. The main function of hydroxyethyl in latex paint is to thicken, prevent pigment gelation, help pigment dispersion, latex, and stability, and can improve the viscosity of components and contribute to the leveling performance of construction: Hydroxyethyl Ethyl 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 between the pH value of 2 and 12. There are the following three methods:
I. Add directly in production:
This method should choose hydroxyethyl cellulose delayed type – hydroxyethyl cellulose with a dissolution time of more than 30 minutes. The use steps are as follows: ① Add a certain amount of pure water to a container with a high-shear agitator ② Start stirring continuously at low speed, and at the same time slowly and evenly add the hydroxyethyl group into the solution ③ Continue stirring until all the granular materials are soaked through ④ Add other additives and alkaline additives, etc. ⑤ Stir until all the hydroxyethyl groups are completely dissolved, Add the rest of the ingredients in the recipe and grind until finished.
Ⅱ. Equipped with mother liquor:
This method can choose instant type, and has the effect of anti-mildew cellulose. The advantage of this method is that it has greater flexibility and can be directly added to the latex paint. The preparation method is the same as the steps of ①–④.
Ⅲ. For preparing porridge-like properties:
Since organic solvents are poor solvents (insoluble) for hydroxyethyl groups, porridges can be formulated with these solvents. The most commonly used organic solvents are organic liquids in latex paint formulations, such as ethylene glycol, propylene glycol and film formers (such as diethylene glycol butyl acetate). The porridge hydroxyethyl cellulose can be directly added to the paint. Continue to stir until completely dissolved.
2, scraping wall putty
At present, environmentally friendly putty that is water-resistant and scrub-resistant in most cities in my country has been basically valued by people. In the past few years, because the putty made of construction glue emits formaldehyde gas and damages people’s health, construction glue is made of polymer It is prepared by the acetal reaction of vinyl alcohol and formaldehyde. Therefore, this material is gradually eliminated by people, and the cellulose ether series products are replaced by this material, that is to say, the development of environmentally friendly building materials, cellulose is the only material at present.
In the water-resistant putty, it is divided into dry powder putty and putty paste. Among these two kinds of putty, modified methyl cellulose and hydroxypropyl methyl are generally 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 two formulas choose cellulose specifications, viscosity and penetration. The addition amount is about 2‰-3‰.
In the construction of scraping wall putty, because the base surface of the wall has a certain 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 fast , it will lead to cracks or powder removal and other phenomena, thereby weakening the strength of the putty. For this reason, adding cellulose ether will solve this problem. But the quality of the filler, especially the quality of lime calcium, is also extremely important. Because cellulose has a high viscosity, it also enhances the buoyancy of the putty, avoids sagging during construction, and is more comfortable and labor-saving after scraping.
3. Concrete mortar
In concrete mortar, to really achieve the final strength, the cement must be completely hydrated, especially in summer construction, the concrete mortar loses water too quickly, and the measures of complete hydration are taken 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 hydroxypropyl methyl cellulose or methyl cellulose to the mortar concrete. The viscosity specification is between 20000–60000cps, the addition amount is about 2‰–3‰, and the water retention rate can be increased to more than 85%. The use method in mortar concrete is to mix the dry powder evenly and then add water.
4. In plastering plaster, bonding plaster and caulking plaster
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, bonding gypsum, inlaying gypsum, tile adhesive and so on.
Stucco plaster is a kind of high-quality plastering material for interior walls and roofs. The walls plastered with it are fine and smooth, do not drop powder, bond firmly to the substrate, have no cracking and fall off, and have fire resistance; bonding plaster is a kind of plaster. A new type of building light board adhesive is a sticky material made of gypsum as the base material and adding various additives. It is suitable for bonding between various inorganic building wall materials. It is non-toxic, tasteless, It has the characteristics of early strength, fast setting and strong bonding, and is a supporting material for construction of building boards and blocks;
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 auxiliary plays a leading role. Since gypsum is divided into anhydrite and hemihydrate gypsum, different gypsum have different effects on product performance, so thickening, water retention and retardation determine the quality of gypsum building materials. The common problem of these materials is hollow cracking, and the initial strength cannot be reached. To solve this problem, it is the problem of choosing the type of cellulose and the composite utilization method of the retarder. In this regard, methyl or hydroxypropyl methyl 30000 is generally selected. –60000cps, the addition amount is between 1.5‰–2‰, the focus of cellulose is water retention, retardation and lubrication.
However, it is not possible to rely on cellulose ether as a retarder, and it is necessary to add a citric acid retarder to mix and use it so that the initial strength will not be affected.
Water retention rate generally refers to the natural loss of water in the absence of external water absorption. If the wall is very dry, water absorption and natural evaporation on the base surface will cause the material to lose water too quickly, and hollowing and cracking will also occur.
This method of use is mixed with dry powder. If a solution is prepared, please refer to the preparation method of the solution.
5. Insulation mortar
Thermal insulation mortar is a new type of interior wall thermal insulation material in the northern region. It is a wall material composed of thermal 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 use method is dry powder mixing method.
6. Interface agent
The interface agent is HPNC20000cps, and the tile adhesive is more than 60000cps. In the interface agent, it is mainly used as a thickener, which can improve the tensile strength and arrow resistance.
Post time: Nov-02-2022