Analysis of the relationship between the viscosity of hydroxypropyl methylcellulose and the water retention of cellulose: the viscosity of cellulose is generally between 50,000 and 200,000, and the production of discrete kettles In the production of the kettle, the viscosity of the vertical kettle production is relatively low, generally between 50,000 and 150,000, and there are also 200,000, but not too much. The annual production of the kettle is generally between 150,000 and 200,000, and there are also 100,000. Not rare.
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Although the viscosity of the vertical kettle production is low, after 12 hours of reaction, there are still more raw materials to be added, so the water retention is better. The viscosity of the production of the kettle is high, but after 8 hours of reaction, The reaction time of the stand-up kettle is 4 hours less, and the added raw materials are relatively simple, so the water retention is less, and the corresponding cost will be lower.
HPMC can be divided into fast-dissolving and hot-dissolving, fast-dissolving products, which are rapidly dispersed in cold water and disappear into water. At this time, the liquid has no viscosity because HPMC is only dispersed in water and has 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. Instant type, wide range of applications, can be used in putty powder and mortar, as well as liquid glue and paint.
The different viscosities of HPMC correspond to different properties. Putty powder is generally 100,000 viscosity HPMC, which plays the role of thickening, water retention and construction. 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 CO2 Under the action of the formation of calcium carbonate, and HPMC only retains water, assists the better reaction of ash calcium, and does not participate in any reaction itself.
The mortar is required to be higher, and it is better to use HPMC with a viscosity of more than 150,000. Moreover, the most important role of HPMC is to retain water, followed by thickening.
In the putty powder, as long as the water retention is good, the HPMC with a viscosity of 70,000 to 80,000 can be used. Of course, the viscosity is larger, and the relative water retention is better. When the viscosity exceeds 100,000, the viscosity has little effect on the water retention. And the viscosity is large, it is better to use some in cement mortar.
Application of HPMC in glue which requires an instant type product with high viscosity.
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: - Mainly used for putty. Reason: Water retention is good. High viscosity: - Mainly used for polystyrene granule insulation mortar rubber powder and vitrified microbead insulation mortar. Reason: The viscosity is high, the mortar is not easy to fall, sag, and the construction is improved.
The water retention of hydroxypropyl methylcellulose depends on the content of hydroxypropyl group. Under the same conditions, hydroxypropyl methylcellulose with high hydroxypropyl content has good water retention effect. The content of the methoxypropyl group having a high methoxy group is appropriately lowered. The methoxy group content is high and the viscosity of hydroxypropyl methylcellulose becomes high. Therefore, when choosing a product, you must choose the product that suits you according to the application. The type that meets the needs of the company is the best.
What is the difference between hydroxypropyl methylcellulose (HPMC) with or without S?
1. HPMC is divided into instant type and rapid dispersion type
HPMC fast dispersing type is suffixed with the letter S. During the production process, glyoxal should be added.
HPMC instant type does not add any letters, such as “″ is “ viscosity fast dispersion type HPMC”.
2. With or without S, the characteristics are different
Rapidly dispersing HPMC disperses rapidly in cold water and disappears into water. At this time, the liquid has no viscosity, because HPMC is only dispersed in water, and there is no real dissolution. After about two minutes, the viscosity of the liquid gradually increases, forming a transparent sticky liquid. Thick colloid.
Instant HPMC can disperse rapidly in hot water at about 70°C. When the temperature drops to a certain temperature, the viscosity slowly appears until a transparent viscous colloid is formed.
3. With or without S, the purpose is different
Instant HPMC can only be used in putty powder and mortar. In liquid glues, coatings and cleaning supplies, clumping will occur and cannot be used.
If you want to learn more, please visit our website Hydroxypropyl Methyl Cellulose (HPMC).
Rapidly dispersing HPMC has a wide range of applications. It can be used in putty powder, mortar, liquid glue, paint, and washing products without any contraindications.
Dissolution method
1. Take the required amount of hot water, put it into a container and heat it to above 80°C, and gradually add this product under slow stirring. The cellulose floats on the water at first, but is gradually dispersed to form a uniform slurry. Cool the solution with stirring.
2. Or heat 1/3 or 2/3 of the hot water to above 85°C, add cellulose to obtain a hot water slurry, then add the remaining amount of cold water, keep stirring, and cool the resulting mixture.
3. Cellulose has a relatively fine mesh number, and exists as a single small particle in the uniformly stirred powder, and it dissolves rapidly when it encounters water to form the required viscosity.
4. Add cellulose slowly and evenly at room temperature, and keep stirring during the adding process until a transparent solution is formed.
What factors affect the water retention of hydroxypropyl methylcellulose?
The water retention of hydroxypropyl methylcellulose HPMC product itself is often affected by the following factors:
1. Cellulose ether HPMC homogeneity
The uniformly reacted HPMC has uniform distribution of methoxy and hydroxypropoxy groups and high water retention.
2. Cellulose ether HPMC thermal gel temperature
The higher the thermal gel temperature, the higher the water retention rate; otherwise, the lower the water retention rate.
3. Cellulose ether HPMC viscosity
When the viscosity of HPMC increases, the water retention rate also increases; when the viscosity reaches a certain level, the increase of the water retention rate tends to be gentle.
Cellulose ether HPMC addition amount
The larger the added amount of cellulose ether HPMC, the higher the water retention rate and the better the water retention effect.
In the range of 0.25-0.6%, the water retention rate increases rapidly with the increase of the addition amount; when the addition amount further increases, the increasing trend of the water retention rate becomes slower.
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Post time: Oct-17-