HPMC is widely used in construction materials, coatings, synthetic resins, ceramics, medicine, food, textiles, agriculture, cosmetics, tobacco and other industries. HPMC can be divided into industrial grade, food grade and pharmaceutical grade according to the application.
What is the dosage of HPMC in putty powder?
The amount of HPMC used in practical applications is affected by the climate, temperature, quality of local ash calcium, the formula of putty powder and the quality required by customers. There are differences in different places, generally speaking, it is between 4-5 kg.
What is the appropriate viscosity of hydroxypropyl methylcellulose?
Generally, 100,000 putty powder is enough, and the requirement in mortar is higher, and it needs 150,000 to be easy to use. Moreover, the most important function of HPMC is water retention, followed by thickening. In putty powder, as long as the water retention is good and the viscosity is low (7-8), it is also possible. Of course, the higher the viscosity, the better the relative water retention. When the viscosity exceeds 100,000, the viscosity has no effect on water retention. big.
What are the main technical indicators of hydroxypropyl methylcellulose?
Hydroxypropyl content
Methyl content
viscosity
Ash
Loss on drying
What are the main raw materials of hydroxypropyl methylcellulose?
The main raw materials of HPMC: refined cotton, methyl chloride, propylene oxide, other raw materials, caustic soda, acid toluene.
What is the main function of the application of hydroxypropyl methylcellulose in putty powder, and does it happen chemically?
Among the putty powder, it plays three roles of thickening, water retention and construction. Thickening, cellulose can thicken to suspend, keep the solution uniform up and down, and resist sagging. Water retention: make the putty powder dry slowly, and assist the ash calcium to react under the action of water. Construction: Cellulose has a lubricating effect, which can make the putty powder have good construction. HPMC does not participate in any chemical reactions, but only plays an auxiliary role.
Hydroxypropyl methylcellulose is a non-ionic cellulose ether, so what is non-ionic?
In layman’s terms, inert substances do not participate in chemical reactions.
CMC (carboxymethyl cellulose) is a cationic cellulose, so it will turn into bean curd when it encounters ash calcium.
What is the gel temperature of hydroxypropyl methylcellulose related to?
The gel temperature of HPMC is related to its methoxy content, the lower the methoxy content, the higher the gel temperature.
Is there any relationship between the drop of putty powder and hydroxypropyl methylcellulose?
There are relationships! ! ! It is the poor water retention of HPMC, which will cause powder loss.
What is the difference between the cold water instant and hot soluble types of hydroxypropyl methylcellulose in the production process?
The cold water instant type of HPMC is surface-treated with glyoxal, and it disperses quickly in cold water, but it does not really dissolve. It only dissolves when the viscosity increases. Hot melt types are not surface treated with glyoxal. If the amount of glyoxal is large, the dispersion will be fast, but the viscosity will increase slowly, and if the amount is small, the opposite will be true.
What is the smell of hydroxypropyl methylcellulose?
The HPMC produced by the solvent method uses toluene and isopropanol as solvents. If the washing is not very good, there will be some residual smell. (Neutralization recovery is the key process of odor)
how to choose the right hydroxypropyl methylcellulose?
Putty powder: requires high water retention, good construction ease
Ordinary cement-based mortar: requires high water retention, high temperature resistance, and instant viscosity (
Application of construction glue: instant products with high viscosity.
Gypsum mortar: high water retention, medium and low viscosity, instant viscosity increase
What is the alias of 16 hydroxypropyl methylcellulose?
Referred to as HPMC or MHPC alias hypromellose, cellulose hydroxypropyl methyl ether.
The application of hydroxypropyl methylcellulose in putty powder, what is the reason for the air bubbles in the putty powder?
In the putty powder, HPMC plays three roles of thickening, water retention and construction. The reasons for the bubbles are:
(1) Too much water is added.
(2) When the bottom layer is not dry, scrape another layer on top, and it is easy to foam.
What is the difference between hydroxypropyl methylcellulose and MC:
MC is methyl cellulose, which is made of cellulose ether by treating refined cotton with alkali, using methane chloride as etherification agent, and undergoing a series of reactions. Generally, the degree of substitution is 1.6-2.0, and the solubility varies with different degrees of substitution. Different, it belongs to non-ionic cellulose ether.
(1) The water retention of methylcellulose depends on its addition amount, viscosity, particle fineness and dissolution rate. Generally, if the addition amount is large, the fineness is small, and the viscosity is large, the water retention rate is high. Among them, the addition amount has a greater impact on the human water retention rate. The viscosity is not proportional to the water retention rate. The dissolution rate mainly depends on the surface of cellulose particles. Degree of modification and particle fineness. Among the above cellulose ethers, methyl cellulose and hydroxypropyl methyl cellulose have higher water retention rates.
(2) Methylcellulose is soluble in cold water, and it will be difficult to dissolve in hot water. Its aqueous solution is very stable in the range of ph=3-12. It has good compatibility with starch, etc. and many surfactants. When the temperature When the gelation temperature is reached, gelation will occur.
(3) Changes in temperature will seriously affect the water retention rate of methyl cellulose. Generally, the higher the temperature, the worse the water retention rate. If the mortar temperature exceeds 40 degrees, the water retention of methyl cellulose will be significantly reduced, which will seriously affect the construction of the mortar.
(4) Methyl cellulose has a significant effect on the construction and adhesion of mortar. Adhesion here refers to the adhesive force felt between the worker’s applicator tool and the wall substrate, that is, the shear resistance of the mortar. The adhesiveness is high, the shear resistance of the mortar is large, and the strength required by the workers in the process of use is also large, and the construction of the mortar is poor.
Hydroxypropyl methylcellulose is divided into several types, and what are the differences in their uses?
HPMC can be divided into instant type (brand name suffix “S”) and hot-melt type. Instant-type products disperse quickly in cold water and disappear into the water. At this time, the liquid has no viscosity because HPMC is only dispersed in water without real dissolution. About (stirring) for 2 minutes, the viscosity of the liquid gradually increases, forming a transparent white viscous colloid. Hot-melt products, when encountering cold water, can disperse quickly in hot water and disappear in hot water. When the temperature drops to a certain temperature (according to the gel temperature of the product), the viscosity will slowly appear until it forms a transparent viscous colloid.
What are the dissolution methods of hydroxypropyl methylcellulose?
1) All models can be added to the material by dry mixing method;
2) When it needs to be directly added to the normal temperature aqueous solution, it is better to use cold water dispersion type, and it usually takes 10-90 minutes to thicken after adding (stir and stir)
3) The ordinary model is stirred and dispersed with hot water first, then it can be dissolved after adding cold water to stir and cool;
4) If agglomeration and wrapping occur during dissolution, it is because the stirring is insufficient or the ordinary model is directly added to cold water. At this time, it should be stirred quickly. the
5) If bubbles are generated during dissolution, they can be left to stand for 2-12 hours (the specific time is determined by the consistency of the solution) or removed by vacuuming, pressurizing, etc., or an appropriate amount of defoaming agent can be added. the
How to judge the quality of hydroxypropyl methylcellulose simply and intuitively?
1) Whiteness, although whiteness cannot determine whether HPMC is easy to use, and if whitening agents are added in the production process, it will affect its quality, but most of the good products have good whiteness.
2) Fineness: The fineness of HPMC generally has 80 mesh and 100 mesh, 120 mesh is less, the finer the finer the better.
3) Light transmittance: After HPMC is placed in water to form a transparent colloid, look at its light transmittance. The greater the light transmittance, the better, indicating that there are less insolubles in it, and the transmittance of vertical reactors is generally good. , The horizontal reactor is worse, but it does not mean that the quality of the vertical reactor is better than that of the horizontal reactor, and there are many factors to determine the product quality.
4) Specific gravity: The larger the specific gravity, the heavier the better. The higher the specific gravity, the higher the hydroxypropyl content in the product. The higher the hydroxypropyl content, the better the water retention.
Post time: Nov-24-2022