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: ① water retention agent ② thickener ③ leveling property ④ film-forming property ⑤ binder; in the polyvinyl chloride industry, it is an emulsifier and dispersant; in the pharmaceutical industry, it is a binder and buffering agent Release skeleton materials, etc., because cellulose has a variety of composite effects, so its application fields are also the most extensive. Next, I will focus on the use and function of cellulose ether in environmental protection 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 the gelation of the pigment, help the dispersion, latex, and stability of the pigment, and increase the viscosity of the component, which is helpful for the leveling performance of the 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 three methods of use:
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 steps are as follows: ① Add a certain amount of pure water to a container equipped with a high-shear agitator ② Start to stir continuously at low speed, and at the same time slowly add the hydroxyethyl group into the solution evenly ③Continue to stir until all the granular materials are soaked ④Add other auxiliaries and basic additives, etc. ⑤Stir 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 type, and has anti-mildew 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 the steps ①-④.
Ⅲ. Prepare it into porridge for later use:
Since organic solvents are poor solvents (insoluble) for hydroxyethyl, these solvents can be used to formulate 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 the 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 function of cellulose in putty is water retention, bonding, lubrication and so on.
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.
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 hydroxypropyl methylcellulose or methylcellulose 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 method of use in mortar concrete is to add water after the dry powder is evenly mixed.
4. In plastering gypsum, bonding 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, does not drop powder, is firmly bonded to the base, has no cracking and falling off, and has a fireproof function; bonded gypsum is a 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, Features such as early strength, fast setting, and firm bonding, it is a supporting material for building panels and block construction; gypsum caulking agent is a gap filler between gypsum panels 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. Because 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 added amount is between 1.5‰–2‰, the cellulose is mainly used for 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
The tile adhesive should be above 60,000cps, and it should be used as a thickener in the interface agent, which can improve the tensile strength and anti-arrow strength.