Low viscosity: 400 is mainly used for self-leveling mortar, but it is generally imported.
Reason: Low viscosity, poor water retention, but good leveling properties, high mortar density.
Medium and low viscosity: 20000-40000 is mainly used for tile adhesive, caulking agent, anti-crack mortar, thermal insulation bonding mortar, etc.
Reasons: Good workability, less water added, and high mortar density.
1. What are the main uses of hydroxypropyl methylcellulose (HPMC)?
——A: HPMC is widely used in building materials, coatings, synthetic resins, ceramics, medicine, food, textiles, agriculture, cosmetics, tobacco and other industries. HPMC can be divided into: construction grade, food grade and pharmaceutical grade according to use. At present, most domestic products are construction grade. In the construction grade, putty powder is used in a large amount, about 90% is used for putty powder, and the rest is used for cement mortar and glue.
2. How many types of hydroxypropyl methylcellulose (HPMC) are there? What are their uses?
——A: HPMC can be divided into instant type and hot melt type. Instant products disperse quickly in cold water and disappear in the water. The liquid has no viscosity at this time because the HPMC is only dispersed in the water and not really dissolved. After about 2 minutes, the viscosity of the liquid gradually increases and a transparent viscous colloid is formed. Hot-soluble products can quickly disperse in hot water and disappear in hot water when encountering cold water. When the temperature drops to a certain temperature (our company’s product is 65 degrees Celsius), the viscosity slowly appears until a transparent viscous colloid is formed. Hot melt type can only be used for putty powder and mortar. In liquid glue and paint, clumping will occur and cannot be used. The immediate type has a wider range of applications. It can be used for putty powder, mortar, liquid glue, and paint without any contraindications.
3. What are the dissolving methods of hydroxypropyl methylcellulose (HPMC)?
——Answer: Hot water dissolution method: Since HPMC is insoluble in hot water, HPMC can be evenly dispersed in hot water at the initial stage and dissolve quickly after cooling. Two typical methods are described below:
1) Put the required amount of hot water into the container and heat it to about 70℃. Gradually add hydroxypropyl methylcellulose with slow stirring. Initially HPMC floats on the water surface, then gradually forms a slurry, and cools with stirring.
2). Add 1/3 or 2/3 of the required amount of water into the container, heat it to 70°C, disperse HPMC according to the method in 1), and prepare hot water slurry; then add the remaining amount of cold water to the hot water slurry. slurry in water, stir and cool the mixture.
Powder mixing method: Mix HPMC powder with a large amount of other powdery substances, mix thoroughly with a blender, and then add water to dissolve. At this time, the HPMC can be dissolved and will not clump together, because there is only a little bit of HPMC in each portion. Little corner. The powder dissolves immediately upon contact with water. ——Putty powder and mortar manufacturers adopt this method. Hydroxypropyl methylcellulose (HPMC) is used as a thickener and water-retaining agent in putty powder mortar.
4. How to judge the quality of hydroxypropyl methylcellulose (HPMC) simply and intuitively?
——Answer: (1) Whiteness: Although whiteness does not determine whether HPMC is easy to use, if brighteners are added during the production process, it will affect its quality. However, most good products have good whiteness. (2) Fineness: The fineness of HPMC is generally 80 mesh and 100 mesh, with 120 mesh being less. Most of the HPMC produced in Hebei is 80 mesh. The finer the finer the better. (3) Light transmittance: Put hydroxypropyl methylcellulose (HPMC) into water to form a transparent colloid, and check its light transmittance. The higher the light transmittance, the better, indicating that there are less insoluble substances inside. The air permeability of vertical reactors is generally better than that of horizontal reactors, but it cannot be said that the quality of vertical reactors is better than that of horizontal reactors. There are many factors that determine product quality. (4) Specific gravity: The larger the specific gravity and the heavier, the better. The specific gravity is generally due to the high hydroxypropyl content in it. The higher the hydroxypropyl content, the better the water retention.
5. What is the dosage of hydroxypropyl methylcellulose (HPMC) in putty powder?
——Answer: The dosage of HPMC in actual applications varies according to climate, temperature, local ash calcium quality, and input formula. ty powder and “customer-required quality”. Generally speaking, it is between 4kg and 5kg. For example, most putty powder in Beijing is 5 kg; most putty powder in Guizhou is 5 kg in summer and 4.5 kg in winter;
6. What is the appropriate viscosity of hydroxypropyl methylcellulose (HPMC)?
——Answer: Putty powder generally costs 100,000 yuan, and mortar requires more, so 150,000 yuan is enough. And the most important function of HPMC is water retention, followed by thickening. In putty powder, as long as it has good water retention and a lower viscosity (70,000-80,000), it is okay. Of course, the higher the viscosity, the better the relative water retention. When the viscosity exceeds 100,000, the viscosity has little effect on water retention.
7. What are the main technical indicators of hydroxypropyl methylcellulose (HPMC)?
——A: Hydroxypropyl content and viscosity, most users are concerned about these two indicators. The higher the hydroxypropyl content, the better the water retention. With high viscosity, water retention is relatively (not absolutely) better, and with high viscosity, it is better used in cement mortar.
8. What are the main raw materials of hydroxypropyl methylcellulose (HPMC)?
—— A: The main raw materials of hydroxypropyl methylcellulose (HPMC): refined cotton, methyl chloride, propylene oxide, other raw materials include caustic soda, acid, toluene, isopropyl alcohol, etc.
9. What is the main role of HPMC in the application of putty powder? Does it have any chemical effects?
——Answer: HPMC has three major functions of thickening, water retention and construction in putty powder. Thickening: Cellulose can thicken suspension, keep the solution uniform and resist sagging. Water retention: Make the putty powder dry slowly and assist the reaction of gray calcium under the action of water. Construction: Cellulose has a lubricating effect and can make the putty powder have good workability. HPMC does not participate in any chemical reactions and only plays an auxiliary role. When putty powder is added to water and applied to the wall, a chemical reaction will occur. As a new substance is formed, the putty powder on the wall is removed from the wall and ground into powder before use. This doesn’t work because a new substance (calcium carbonate) has been formed. ) up. The main components of gray calcium powder are: a mixture of Ca(OH)2, CaO and a small amount of CaCO3, CaO+H2O=Ca(OH)2 -Ca(OH)2+CO2=CaCO3↓+H2O Gray calcium dissolves in water and air CO2 Under the action of calcium carbonate, HPMC only retains water and assists the gray calcium to react better, and does not participate in any reaction itself.
10. HPMC is a non-ionic cellulose ether, so what is a non-ionic one?
A: In layman’s terms, non-ions are substances that do not ionize in water. Ionization is the process by which electrolytes dissociate into freely moving charged ions in certain solvents (e.g., water, alcohol). For example, sodium chloride (NaCl), the salt consumed every day, dissolves in water and ionizes, producing freely mobile positively charged sodium ions (Na+) and negatively charged chloride ions (Cl). That is, when HPMC is placed in water, it does not dissociate into charged ions, but exists in molecular form.
Post time: Feb-06-2024