HPMC in Skim coat

Hydroxypropyl methyl cellulose (HPMC) viscosity for Skim coat ?

– answer: Skim coat is ok commonly HPMC 100000cps, some taller of the requirement in mortar, want 150000cps ability to use. Moreover, HPMC is the most important role of water retention, followed by thickening. In Skim coat , as long as the water retention is good, the viscosity is low (7-80000), it is also possible, of course, the viscosity is bigger, the relative water retention is better, when the viscosity is more than 100 thousand, the viscosity of water retention is not much.

What are the main technical indicators of hydroxypropyl methyl cellulose (HPMC)?

Answer: Hydroxypropyl content and viscosity, most users care about these two indicators. Hydroxypropyl content is high, water retention is generally better. Viscosity, water retention, relative (but not absolute) is also better, and viscosity, cement mortar is better to use some.

Hydroxypropyl methyl cellulose (HPMC) what are the main raw materials?

Answer: hydroxypropyl methyl cellulose (HPMC) main raw materials: refined cotton, chloromethane, propylene oxide, other raw materials, tablet alkali, acid, toluene, isopropyl alcohol and so on.

HPMC in Skim coat in the application, the main role, whether chemical?

Answer: HPMC in Skim coat , thickening, water and construction of three roles. Thickening: cellulose can be thickened to suspension, so that the solution remains uniform up and down the role of anti-flow hanging. Water retention: make Skim coat  dry slowly, auxiliary gray calcium in the action of water reaction. Construction: cellulose lubrication, can make Skim coat  has good construction. HPMC does not participate in any chemical reactions, but only plays a supporting role. Skim coat  and water, on the wall, is a chemical reaction, because of the generation of new substances, the wall of the Skim coat  down from the wall, ground into powder, and then use, not good, because has formed a new substance (calcium carbonate). The main components of grey calcium powder are: Ca(OH)2, CaO and a small amount of CaCO3 mixture, CaO+H2O=Ca(OH)2 – Ca(OH)2+CO2=CaCO3↓+H2O gray calcium in water and air under the action of CO2, the formation of calcium carbonate, and HPMC only water, auxiliary gray calcium better reaction, its own did not participate in any reaction.

HPMC is non-ionic cellulose ether, so what is non-ionic?

A: Generally speaking, non-ions are substances that do not ionize in water. Ionization is the dissociation of an electrolyte into free-moving charged ions in a specific solvent, such as water or alcohol. For example, the salt we eat every day — sodium chloride (NaCl) dissolves in water and ionizes to produce free-moving sodium ions (Na+) with a positive charge and chloride ions (Cl) with a negative charge. That is, HPMC in water does not dissociate into charged ions, but exists as molecules.

What is the gelation temperature of hydroxypropyl methyl cellulose related to?

Answer: The gel temperature of HPMC is related to the methoxyl content. The lower the methoxyl content is, the higher the gel temperature is.

Skim coat powder and HPMC there is no relationship?

Answer: Skim coat drop powder mainly and ash calcium quality has a very big relationship, and HPMC does not have too big relationship. The low calcium content of gray calcium and the improper proportion of CaO and Ca(OH)2 in gray calcium will cause powder dropping. If there is a relationship with HPMC, then the poor water retention of HPMC will also cause powder loss.

What is the difference between cold water soluble and hot soluble hydroxypropyl methyl cellulose in the production process?

– Answer :HPMC cold water instant solution type is after glyoxal surface treatment, put in cold water quickly dispersed, but not really dissolved, viscosity up, is dissolved. The thermosoluble type has not been surface treated with glyoxal. The amount of glyoxal is large, the dispersion is fast, but the viscosity is slow, the amount is small, on the contrary.

What is it about hydroxypropyl methyl cellulose (HPMC) that smells?

– Answer: HPMC produced by solvent method is made of toluene and isopropyl alcohol. If the washing is not very good, there will be some residual taste.

Different uses, how to choose the appropriate hydroxypropyl methyl cellulose (HPMC)?

– answer: be bored with the application of child powder: the requirement is inferior, viscosity 100000, ok, it is important to protect water to be close to. Mortar application: higher requirements, high viscosity requirements, 150000 to be better. Glue application: the need for instant products, high viscosity.

What’s another name for hydroxypropyl methyl cellulose?

– ANSWER: Hydroxypropyl MethylCellulose, Abbreviated as HPMC or MHPC, or Hydroxypropyl Methyl Cellulose; Cellulose hydroxypropyl methyl ether; Hypromellose, Cellulose, 2-hydroxypropyl methyl Cellulose ether.

HPMC in the application of Skim coat ,what reason Skim coat bubble ?

Answer: HPMC in Skim coat , thickening, water and construction of three roles. Not participating in any reaction. Causes of bubbles: 1, too much water. 2, the bottom is not dry, on the top of the scraping layer, also easy to blister.

Inner and outer wall Skim coat formula?

– answer: interior wall Skim coat : calcium 800KG gray calcium 150KG (starch ether, pure green, peng runtu, citric acid, polyacrylamide can be added appropriately)

Exterior wall Skim coat : cement 350KG calcium 500KG quartz sand 150KG latex powder 8-12kg cellulose ether 3KG starch ether 0.5kg wood fiber 2KG

What’s the difference between HPMC and MC?

– Answer :MC is methyl cellulose, which is made of cellulose ether through a series of reactions with methane chloride as etherifying agent after refined cotton is treated with alkali. Generally, the degree of substitution is 1.6~2.0, and the solubility varies with the degree of substitution. Belongs to nonionic cellulose ether.

(1) The water retention of methyl cellulose depends on its addition amount, viscosity, particle fineness and dissolution rate. Generally add large amount, small fineness, viscosity, water retention rate is high. Among them, the amount of additive has the greatest influence on the water retention, and the viscosity is not proportional to the water retention. The dissolution rate mainly depends on the surface modification degree and particle fineness of cellulose particles. In the above several cellulose ethers, methyl cellulose and hydroxypropyl methyl cellulose water retention rate is higher.

(2) Methyl cellulose is soluble in cold water, which is difficult to dissolve in hot water. Its aqueous solution is very stable within the pH=3~12. It has good compatibility with starch, guanidine gum and many surfactants. Gelation occurs when the temperature reaches gelation temperature.

(3) The change of temperature will seriously affect the water retention rate of methyl cellulose. Generally, the higher the temperature, the worse the water retention. If the temperature of mortar exceeds 40℃, the water retention of methyl cellulose will be significantly worse, which seriously affects the constructability of mortar.

(4) Methyl cellulose has obvious influence on the constructability and adhesion of mortar. “Adhesion” here refers to the adhesion felt by the worker between the tool and the wall substrate, namely the shear resistance of the mortar. Adhesion is large, the shear resistance of mortar is large, the strength required by workers in the process of use is also large, and the construction of mortar is poor. In cellulose ether products, the adhesion of methyl cellulose is at a moderate level.

HPMC hydroxypropyl methyl cellulose, is refined by cotton after alkali treatment, with propylene oxide and chloromethane as etherifying agent, through a series of reactions and made of non-ionic cellulose mixed ether. The degree of substitution is generally 1.2~2.0. Its properties vary with the proportion of methoxy and hydroxypropyl content.

(1) Hydroxypropyl methyl cellulose is easily soluble in cold water, which is difficult to dissolve in hot water. However, its gelation temperature in hot water is obviously higher than that of methyl cellulose. The solubility of methyl cellulose in cold water was also improved greatly.

(2) The viscosity of hydroxypropyl methyl cellulose is related to its molecular weight, and the higher the molecular weight, the higher the viscosity. Temperature also affects viscosity. Viscosity decreases as temperature increases. But its viscosity high temperature effect is lower than that of methyl cellulose. The solution is stable when stored at room temperature.

(3) Hydroxypropyl methyl cellulose is stable to acid and base, and its aqueous solution is very stable in the range of pH=2~12. Caustic soda and lime water have little effect on its properties, but alkali can accelerate its dissolution rate and improve the viscosity. Hydroxypropyl methyl cellulose is stable to general salts, but when the concentration of salt solution is high, the viscosity of hydroxypropyl methyl cellulose solution tends to increase.

(4) The water retention of hydroxypropyl methyl cellulose depends on its dosage and viscosity, and the water retention rate of hydroxypropyl methyl cellulose is higher than that of methyl cellulose at the same dosage.

(5) Hydroxypropyl methyl cellulose can be mixed with water-soluble polymer compounds to become uniform, higher viscosity solution. Such as polyvinyl alcohol, starch ether, vegetable glue and so on.

(6) The adhesion of hydroxypropyl methyl cellulose to mortar construction is higher than that of methyl cellulose.

(7) Hydroxypropyl methyl cellulose has better enzyme resistance than methyl cellulose, and its solution enzyme degradation possibility is lower than that of methyl cellulose.

What should be paid attention to in practical application about the relationship between viscosity and temperature of HPMC?

Answer: THE viscosity of HPMC is inversely proportional to temperature, that is to say, the viscosity increases with the decrease of temperature. When we talk about the viscosity of a product, we’re talking about the viscosity of 2% of the product in water at 20 degrees Celsius.

In practical application, in areas with large temperature differences between summer and winter, it should be noted that it is recommended to use relatively low viscosity in winter, which is more conducive to construction. Otherwise, when the temperature is low, the viscosity of cellulose will increase, and when scraping, the feel will be heavy.

Medium viscosity :75000-100000 mainly used for putty

Reason: Good water retention

High viscosity :HPMC 150000-200000 is mainly used for polystyrene particle insulation mortar glue powder material and vitrified beads insulation mortar.

Reason: high viscosity, mortar is not easy to drop, flow hanging, improve the construction.

But generally speaking, the higher the viscosity, the better the water retention, so many dry mortar factories, considering the cost, use medium viscosity HPMC cellulose (75000-100000) to replace medium and low viscosity HPMC cellulose (20000-40000) to reduce the amount of addition.


Post time: Jan-10-2022