Questions about You Should Know about HPMCMarch 23rd 2023
Overview of cellulose ether: Cellulose ether is a non-ionic semi-synthetic high molecular polymer. It has two types of water-soluble and solvent-based. The effects caused by different industries are different, such as in chemical building materials. It has the following compound effects:
①Water retention agent
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. It is precisely because cellulose has a variety of complex effects, so its application The field is also the most extensive. Now I will focus on the application methods and functions of cellulose ethers in various building materials.
1. In latex paint: In the latex paint line, choose hydroxyethyl cellulose. The general specification for iso-viscosity is RT30000-50000cps, which corresponds to the HBR250 specification, and the reference dosage is generally about 1.5‰-2‰. The main role of hydroxyethyl in latex paint is to thicken, prevent the gelation of pigments, help the dispersion of pigments, the stability of latex, and increase the viscosity of the components, and help the leveling performance of construction: Hydroxyethyl cellulose is more convenient to use. It can be dissolved in cold or hot water, and is not affected by the pH value. It can be used with peace of mind between 2 and 12 in the PI value. There are three methods to use: I. Direct Adding in production: This method should choose hydroxyethyl cellulose delayed type hydroxyethyl cellulose with a dissolution time of more than 30 minutes, and its use steps are as follows: ①In a container equipped with a high-shear mixer Quantitative purified water ②Start stirring continuously at low speed, and slowly add the hydroxyethyl group into the solution evenly ③Continue stirring until all the granular materials are soaked ④Add other additives and alkaline additives, etc. ⑤Stir until all the hydroxyethyl The base is completely dissolved, then add other ingredients in the formula and grind until the finished product. Ⅱ. Equipped with mother liquor for use: This method can choose instant cellulose, and 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. Preparation for porridge preparation: 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), hydroxypropyl methylcellulose, and porridge hydroxyethyl fiber The vegetable can be directly added to the paint, after adding, continue to stir until it is completely dissolved.
2. In the wall putty: At present, the environmentally friendly putty that is resistant to water and scrubbing in most cities in my country has been basically valued by people. In the past few years, the putty made of construction glue emits formaldehyde gas and damages people’s bodies. Healthy, construction glue is made by acetal reaction of polyvinyl alcohol and formaldehyde. So this kind of material is gradually eliminated by people, and it is the cellulose ether series products that replace this material, which means that the development of environmentally friendly building materials, cellulose is currently the only material. Water-resistant putty is divided into dry powder putty and putty paste. Generally, two types of putty are modified methyl cellulose and hydroxypropyl methyl. The viscosity specification is generally between 30,000 and 60,000 cps. The main function of cellulose in putty is water retention, adhesion, 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 and viscosity of the cellulose and the infiltration amount of the two formulas are different. The added amount is about 2‰-3‰. In the construction of the wall 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 concrete is 3-5%), plus the external evaporation, if the putty loses water too fast , It will lead to cracks or powdering, which will weaken the strength of putty. For this reason, adding cellulose ether will solve this problem. But the quality of the filler, especially the quality of ash calcium is also extremely important. Because cellulose has a higher viscosity, it also enhances the buoyancy of the putty, avoids the sagging phenomenon during construction, and is more comfortable and labor-saving after scraping. It is that the cellulose ether in the powder putty should be added more factories. Its production and use are more convenient. The filler and the auxiliary agent can be evenly mixed with the dry powder. The construction is also more convenient. The on-site water distribution is as much as you need.