The role and application of cellulose ether in environmental protection building materials（1)
Cellulose ether is a non-ionic semi-synthetic polymer. It has two kinds of water-soluble and solvent-base, the effects caused in different industries are different.
For example, in chemical building materials, it has the following compound effects: ① water-retaining 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 a slow-release matrix material. Because cellulose has a variety of complex effects, its application fields are also the most extensive.
I will focus on the use and role of cellulose ether in environmentally friendly building materials.
1.In latex paint
In the latex paint line, hydroxyethyl cellulose should be selecte. The general specification of viscosity is 30,000-50000cps, and the reference dosage is generally about 1.5 ‰ -2 ‰.
The main role of hydroxyethyl in latex paint is to thicken and prevent gelation of pigments. Contributes to pigment dispersion, latex, stability, and can increase the viscosity of the components, and helps leveling performance of construction: hydroxyethyl cellulose is more convenient to use.
Both cold and hot water can be dissolve, and it is not affecte by pH. It can be use between pH 2 and 12. There are three methods to use:
I. Add directly to 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 equipped with a high-resistance agitator.
② Start stirring continuously at a low speed, while slowly adding hydroxyethyl to the solution evenly.
③ Continue stirring until all particulate materials are wet through.
④ Add other additives and alkaline additives.
⑤ Stir until all the hydroxyethyl groups are completely dissolve, then add the other components in the formula. Grind until finished.
Ⅱ. For use with mother liquor:
This method can choose instant-type cellulose with anti-mold effect. The advantage of this method is greater flexibility, which can be add directly to latex paint. The preparation method is the same as ①–④.
Ⅲ. For congee preparation:
Since organic solvents are poor solvents (insoluble) to hydroxyethyl, porridge can be formulated with these solvents.
The most common 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). Porridge hydroxyethyl cellulose can be directly add to the lacquer. After adding, continue to stir until completely dissolved.
2. In wall scraping putty
I.
At present, environmentally-friendly putty that is resistant to water and scrubbing in most cities in China has been valued by people. In the past few years, the putty made with construction glue radiated formaldehyde gas and harmed people’s health.
Construction glue is made by the acetal reaction of polyvinyl alcohol and formaldehyde. Therefore, this material is gradually eliminat by people, and the cellulose ether series products are replace by this material. In other words, the development of environmentally friendly building materials, cellulose is currently the only material.
In water-resistant putty, it is divid into two types: dry powder putty and putty cream. Among these two types of putty, modified methyl cellulose and hydroxypropylmethyl are generally selecte. The viscosity specification is generally between 30000-60000cps. The main role of cellulose in putty is to retain water, bond, and lubricate.
Ⅱ.
Due to the different formulations of putty from various manufacturers, some are gray calcium, light calcium, white cement and so on. Some are gypsum powder, gray calcium, light calcium and so on. Therefore, the specification viscosity and the infiltration amount of cellulose for the two formulations are different, and the general addition amount is about 2 ‰ -3 ‰.
In the wall scraping putty construction, the base surface of the wall has a certain amount of water absorption. (The water absorption of the brick wall is 13%, and the concrete is 3-5%). Coupled with external evaporation, if the putty loses water too quickly, it will cause cracks or powdering. As a result, the strength of the putty is weakened. For this reason, the problem will be solve after adding cellulose ether.
But the quality of the filler, especially the quality of ash calcium, is also extremely important. Because cellulose has a higher viscosity, the buoyancy of putty is also enhanced. It also avoids the sagging phenomenon during construction, and it is more comfortable and labor-saving after scraping.
If you have any questions, you can send them to my email : tanyatao@qinahaochem.com
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