Focus on Cellulose ethers

What is Hydroxypropyl Methylcellulose HPMC?

Industrial grade hydroxypropyl methylcellulose is distinguished by viscosity. Generally used are the following grades (in terms of viscosity).

Low viscosity: 400 is mainly used for self-leveling mortar, but it is generally imported. Reason: low viscosity, although the water retention is poor, but the leveling is good, the mortar density is high.

Medium and high viscosity: 20000-70000 is mainly used for tile adhesive, caulking agent, crack-resistant mortar, thermal insulation bonding mortar, etc. Reasons: good workability, less water, and high mortar density.

What is the main use of hydroxypropyl methylcellulose (HPMC)?

HPMC is widely used in construction materials, coatings, synthetic resins, ceramics, medicine, food, textile, agriculture, cosmetics, tobacco and other industries. HPMC can be divided into: building, food and pharmaceutical. At present, most of the domestically produced buildings are of the architectural grade. In the construction grade, the amount of putty powder is very large, about 90% is used for making putty powder, and the rest is used as cement mortar and glue.

There are several types of hydroxypropyl methylcellulose (HPMC). What is the difference in their use?

HPMC can be divided into instant-dissolved and hot-dissolved, fast-dissolving products. When it is rapidly dispersed in cold water, it disappears into the water. At this time, the liquid has no viscosity because HPMC is only dispersed in water and there is no real dissolution. About 2 minutes, the viscosity of the liquid gradually became larger, forming a transparent viscous colloid. The hot-melt type product, in the case of cold water, can be quickly dispersed in hot water and disappear in hot water. When the temperature drops to a certain temperature, the viscosity gradually appears until a transparent viscous colloid is formed. The hot-dissolved type can only be used in putty powder and mortar. In liquid glue and paint, there will be a phenomenon of clumping, which cannot be used. It is available in a wide range of applications, in putty powder and mortar, as well as in liquid glues and coatings. There are no contraindications.

What are the dissolution methods of hydroxypropyl methylcellulose (HPMC)?

Hot water dissolution method: Since HPMC is not dissolved in hot water, the initial HPMC can be uniformly dispersed in hot water and then quickly dissolved during cooling. Two typical methods are described as follows: 1), placed in a container Enter the required amount of hot water and heat to approximately 70°C. Hydroxypropyl methylcellulose was gradually added with slow stirring, and the HPMC floated on the surface of the water, and then a slurry was gradually formed, and the slurry was cooled with stirring. 2) Adding 1/3 or 2/3 of the required amount of water to the vessel and heating to 70°C, dispersing HPMC according to 1) to prepare a hot water slurry; then adding the remaining amount of cold water to the hot water In the slurry, the mixture was cooled after stirring. Powder mixing method: the HPMC powder is mixed with a large amount of other powdery substances, mixed thoroughly with a blender, and then dissolved with water. At this time, HPMC can be dissolved without agglomeration, because each small small corner has only a little HPMC. The powder will dissolve immediately upon contact with water. – This method is used by putty powder and mortar manufacturers. Hydroxypropyl methylcellulose (HPMC) is used as a thickener and water retaining agent in putty mortar.  

How to judge the quality of hydroxypropyl methylcellulose (HPMC) simply and intuitively?

(1) Whiteness: Although whiteness cannot determine whether HPMC is easy to use, and if it is added to the brightener during the production process, it will affect its quality. However, good products are mostly white. (2) Fineness: The fineness of HPMC generally has 80 mesh and 100 mesh, and 120 mesh is less. The finer the fineness, the better in general. (3) Transmittance: Put hydroxypropyl methylcellulose (HPMC) in water to form a transparent colloid, and look at its transparency. The better the transmittance, the less insoluble matter. . The vertical reactor has a good permeability, and the horizontal reactor is worse, but it does not mean that the quality of the vertical reactor is better than that of the kettle. The quality of the product is determined by many factors. (4) Specific gravity: The greater the specific gravity, the heavier the weight. The ratio is large, generally because the content of hydroxypropyl group is high, and the content of hydroxypropyl group is high, the water retention is better.

HPMC

What is the amount of hydroxypropyl methylcellulose (HPMC) in putty powder?

The amount of construction grade HPMC used in practical applications varies with climate, temperature, local ash calcium quality, formula of putty powder and “quality required by customers”. In general terms, between 4 kg and 5 kg. For example: cold area putty powder, most put 5 kg; Hot area is mostly 5 kg in summer and 4.5 kg in winter.  

What is the viscosity of hydroxypropyl methylcellulose (HPMC)?

The wall putty powder is generally 100,000, and the dry mortar is required to be higher. It is necessary to use 150,000. Moreover, the most important role of HPMC is to retain water, followed by thickening. In putty powder, as long as the water retention is good, the viscosity is lower (70,000-80,000), it is also possible. Of course, the viscosity is larger, the relative water retention is better. When the viscosity exceeds 100,000, the effect of viscosity on water retention is Not too big.  

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

Hydroxypropyl content and viscosity, most users are concerned about these two indicators. If the hydroxypropyl content is high, the water retention is generally better. Viscosity, water retention, relative (rather than absolute), and high viscosity, better in cement mortar.  

What are the main raw materials for hydroxypropyl methylcellulose (HPMC)?

The main raw materials of hydroxypropyl methylcellulose (HPMC): refined cotton, methyl chloride, propylene oxide, other raw materials, such as caustic soda, acid, toluene, isopropanol.

What is the main role of HPMC in the application of putty powder?

 HPMC plays the role of thickening, water retention and construction in the putty powder. Thickening: Cellulose can be thickened to suspend, keep the solution evenly uniform, and resist sag. Water retention: The putty powder is dried slowly, and the auxiliary ash calcium reacts under the action of water. Construction: Cellulose has a lubricating effect, which can make the putty powder have good workability. HPMC does not participate in any chemical reactions and only plays a supporting role. Putty powder with water, on the wall, is a chemical reaction. Because of the formation of new substances, the putty powder on the wall is removed from the wall, ground into powder, and reused, it will not work, because a new substance has been formed (calcium carbonate). ). The main components of ash calcium powder are: Ca(OH)2, a mixture of CaO and a small amount of CaCO3, CaO+H2O=Ca(OH)2-Ca(OH)2+CO2=CaCO3+H2O ash calcium in water and air Under the action of CO2, calcium carbonate is formed, and HPMC only retains water, assists the better reaction of ash calcium, and does not participate in any reaction itself. 

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

 Generally speaking, non-ion is a substance that is not in the water and is not ionized. Ionization refers to the process by which an electrolyte is dissociated into a freely moving charged ion in a specific solvent such as water or alcohol. For example, the salt that is eaten every day, sodium chloride (NaCl), is ionized to produce free-moving sodium ions (Na+) positively charged and chloride (Cl) negatively charged. That is to say, HPMC is placed in water and does not dissociate into charged ions, but exists in the form of molecules.

What is the gel temperature of hydroxypropyl methylcellulose?

The gel temperature of HPMC is related to its methoxy content. The lower the methoxy content, the higher the gel temperature.

Does the powder of putty powder have any relationship with HPMC?

The powder of putty powder is mainly related to the quality of gray calcium, and has little to do with HPMC. The low calcium content of ash calcium and the inappropriate ratio of CaO and Ca(OH)2 in ash calcium will cause powder loss. If it is related to HPMC, then if the water retention of HPMC is poor, it will also cause powder loss.

What is the difference between the cold water instant type and the hot soluble type of hydroxypropyl methylcellulose in the production process? HPMC cold water instant type is surface treated with glyoxal , and it is quickly dispersed in cold water, but it is not really dissolved. When the viscosity is up, it is dissolved. The hot soluble form is not surface treated with glyoxal. When the amount of glyoxal is large, the dispersion is fast, but the viscosity is slow. 

What is the smell of hydroxypropyl methylcellulose (HPMC)?

The HPMC produced by the solvent method uses toluene and isopropyl alcohol as solvents. If the washing is not very good, there will be some residual taste.

How to choose the right hydroxypropyl methylcellulose (HPMC) for different purposes?

 The application of putty powder: the requirement is lower, the viscosity is 100,000, it is ok, the important thing is to keep the water better. Application of mortar: high requirements, high viscosity, 150,000 is better. Glue application: Need instant type product, high viscosity.

What is the alias of hydroxypropyl methylcellulose?

Hydroxypropyl methylcellulose, HydroxypropylMethylCellulose Abbreviation: HPMC or MHPC alias: hypromellose; cellulose hydroxypropyl methyl ether; Hypromellose, Cellulose ether, 2-hydroxypropylmethyl Cellulos eether. Cellulose hydroxypropyl methyl ether ,Hyprolose.

HPMC

The application of HPMC in putty powder, what is the cause of foam in putty powder?

HPMC plays the role of thickening, water retention and construction in the putty powder. Do not participate in any reaction. The reason for the bubble: 1, the water is too much. 2, the bottom layer is not dry, just scrape a layer on the top, it is also easy to foam. 

The inner and outer wall putty powder formula?

Interior wall putty powder: heavy calcium 800KG gray calcium 150KG (starch ether, pure green, penmine soil, citric acid, polyacrylamide, etc. can be properly selected to add)

External wall putty powder: cement 350KG, heavy calcium 500KG, quartz sand 150KG, latex Powder 8-12KG, cellulose ether 3KG ,starch ether 0.5KG, wood fiber 2KG

What is the difference between HPMC and MC?

MC is methyl cellulose. After the refined cotton is treated with alkali, chloromethane is used as an etherifying agent, and a series of reactions are made to prepare cellulose ether. The degree of substitution is generally 1.6 to 2.0, and the degree of substitution differs depending on the solubility. It belongs to nonionic cellulose ether.  

(1) The water retention of methyl cellulose depends on the amount of addition, viscosity, particle fineness and dissolution rate. Generally, the amount of addition is large, the fineness is small, and the viscosity is large, and the water retention rate is high. The addition amount has the greatest influence on the water retention rate, and the viscosity level is not proportional to the water retention rate. The rate of dissolution depends mainly on the degree of surface modification of the cellulose particles and the fineness of the particles. Among the above cellulose ethers, methylcellulose and hydroxypropylmethylcellulose have a high water retention rate.  

(2) Methylcellulose is soluble in cold water, and it is difficult to dissolve in hot water. The aqueous solution is very stable in the range of pH=3~12. It has good compatibility with starch, guar gum and many other surfactants. When the temperature reaches the gelation temperature, a gelation phenomenon occurs.  

(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 the mortar exceeds 40 ° C, the water retention of methyl cellulose will be significantly deteriorated, which seriously affects the workability of the mortar.  

(4) Methyl cellulose has a significant effect on the workability and adhesion of the mortar. “Adhesiveness” herein refers to the adhesive force felt between the worker’s application tool and the wall substrate, that is, the shear resistance of the mortar. The adhesion is large, the shear resistance of the mortar is large, the force required by the worker during use is also large, and the workability of the mortar is poor.

Methylcellulose adhesion is intermediate in cellulose ether products. HPMC is hydroxypropylmethylcellulose, which is a nonionic cellulose mixed ether prepared by a series of reactions using acetal oxide and methyl chloride as an etherifying agent after alkalization of refined cotton. The degree of substitution is generally 1.2 to 2.0. Its nature is different depending on the ratio of methoxyl content and hydroxypropyl content.  

(1) Hydroxypropyl methylcellulose is easily soluble in cold water, and it may be difficult to dissolve in hot water. However, its gelation temperature in hot water is significantly higher than that of methyl cellulose. The dissolution in cold water is also much better than methyl cellulose. -

(2) The viscosity of hydroxypropylmethylcellulose is related to the molecular weight thereof, and the viscosity is high when the molecular weight is large. The temperature also affects its viscosity, the temperature rises, and the viscosity decreases. However, its viscosity has a lower temperature than methyl cellulose. Its solution is stable at room temperature.  

(3) Hydroxypropyl methylcellulose is stable to acids and bases, and its aqueous solution is very stable in the range of pH=2~12. Caustic soda and lime water do not have much effect on their properties, but alkali accelerates their dissolution rate and increases viscosity. Hydroxypropyl methylcellulose has stability to general salts, but when the concentration of the salt solution is high, the viscosity of the hydroxypropyl methylcellulose solution tends to increase.  

(4) The water retention of hydroxypropyl methylcellulose depends on the amount of addition, viscosity, etc., and the water retention rate under the same amount is higher than that of methylcellulose.  

(5) Hydroxypropyl methylcellulose can be mixed with a water-soluble polymer compound to form a uniform, higher viscosity solution. Such as polyvinyl alcohol, starch ether, vegetable gum and the like.  

(6) Hydroxypropyl methylcellulose has higher adhesion to mortar than methyl cellulose.  

(7) Hydroxypropyl methylcellulose has better enzymatic resistance than methylcellulose, and its solution is less likely to be enzymatically degraded than methylcellulose.

HPMC viscosity and temperature relationship, what should be paid attention to in practical applications?

The viscosity of HPMC is inversely proportional to temperature, that is, the viscosity increases with decreasing temperature. The viscosity of a product we usually refer to is the result of testing its 2% aqueous solution at a temperature of 20 degrees Celsius. In practical applications, in areas with large temperature differences between summer and winter, it should be noted that it is recommended to use a 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 it is scraped, the hand feel will be heavy. Medium viscosity: 75000-100000 Mainly used for putty Reason: water retention high viscosity: 150000-200000 is mainly used for polystyrene granule insulation mortar powder and vitrified microbead insulation mortar. Reason: high viscosity, mortar is not easy to fall Yes, sag, improved construction. But in general, the higher the viscosity, the better the water retention, so many dry mortar plants consider the cost, replace the medium and low viscosity cellulose with medium viscosity cellulose (75000-100000). (20000-40000) to reduce the amount added.


Post time: Jan-07-2019
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