Interpretation of HPMC Problems of Hydroxypropyl Methyl Cellulose (Part 1)

 1, Hydroxypropyl methyl cellulose HPMC is divided into several kinds, what is the difference between its use?

A: Construction Grade HPMC can be divided into quick-dissolving type and hot-dissolving type. Quick-dissolving type products disperse quickly in cold water and disappear in water. At this time, the liquid has no viscosity, because HPMC is only dispersed in water and does not really dissolve.After about 2 minutes, the viscosity of the liquid gradually increases to form a clear, viscous gel.Hot dissolve product, in cold water, can be in hot water, quickly disperse, disappear in hot water, when the temperature drops to a certain temperature, viscosity slowly appear, until the formation of a transparent viscous gel.The hot dissolve type can only be used in putty powder and mortar, in liquid glue and paint, there will be clumping phenomenon, can not be used.Instant type, a wide range of applications, in putty powder and mortar, as well as liquid glue and paint, can be used, there is no taboo.

2, hydroxypropyl methyl cellulose HPMC) what is the main use?

A :HPMC is widely used in construction materials, coatings, synthetic resins, ceramics, medicine, food, textile, agriculture, cosmetics, tobacco and other industries.According to the use of HPMC can be divided into: construction grade, food grade and medical grade.At present domestic is mostly building grade, in building grade, the dosage of putty powder is very big, about 90% is used to make putty powder, the rest is used for cement mortar and glue.

3, Hydroxypropyl methyl cellulose HPMC dissolution methods have those?

A: Hot-water solution: As Hydroxypropyl Methyl Cellulose does not dissolve in hot water, at the initial stage, HPMC can be dispersed uniformly in hot water and then dissolved rapidly when cooled. Two typical methods are described as follows:

1) Add 1/3 or 2/3 of the required water into the container and heat it to 70℃. Disperse HPMC to prepare hot water slurry according to 1) method;Then add the remaining amount of cold water to the hot water slurry and stir to cool the mixture.

Powder mixing method: Mix HPMC powder with a large number of other powder ingredients, fully mix with a blender, and then add water to dissolve, then HPMC can be dissolved, but not agglomerate, because every tiny corner, only a little HPMC powder, will immediately dissolve in water.-- This is the method used by putty powder and mortar manufacturers.Hydroxypropyl methyl cellulose (HPMC) is used as thickener and water-retaining agent in putty mortar.

2) Put the required amount of hot water into the container and heat it to about 70℃.In the slow stirring gradually add hydroxypropyl methyl cellulose, HPMC began to float on the surface of the water, and then gradually form a slurry, under the stirring cooling slurry.

Construction Grade HPMC

4. How to simply and intuitively determine the quality of hydroxypropyl methyl cellulose (HPMC)?

Answer :(1) specific gravity: specific gravity is bigger, heavier want to be better.

(2) Whiteness: Whiteness does not determine whether HPMC is easy to use, and if whitening agent is added in the production process, its quality will be affected.However, good products are mostly whiter.

(3) Fineness: The fineness of HPMC is generally 80 mesh and 100 mesh, with less 120 purposes. Most HPMC produced in Hebei is 80 mesh. The finer the fineness is, the better it is in general.

(4) Transmittance: Put HPMC for putty powder into water to form a transparent gel and observe its transmittance. The greater the transmittance, the better, indicating less insoluble matter.The transmittance of the vertical reactor is generally good, while that of the horizontal reactor is worse, but it does not mean that the quality produced by the vertical reactor is better than that produced by the horizontal reactor. There are many factors that determine the quality of the product.The content of hydroxypropyl inside is high, the content of hydroxypropyl is high, it is better to keep water.

The Role of HPMC in Putty Powder

 In the putty powder, HPMC plays three roles of thickening, water retention and construction. Do not participate in any reaction.

1. Thickening: Cellulose can be thickened to suspend and keep the solution uniform, and resist sag.

2. Water retention: make the putty powder dry slowly, and assist the gray calcium to react under the action of water.

3. Construction: Cellulose has a lubricating effect, which can make the putty powder have good construction properties. HPMC does not participate in any chemical reaction, only plays a supporting role. The putty powder is added with water, and the wall is chemically reacted. Because of the formation of new substances, the putty powder on the wall is removed from the wall and ground into powder. Then it will not 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 The role of gray calcium in water and air CO2 Calcium carbonate is formed under HPMC, while HPMC only retains water and assists the better reaction of gray calcium. It does not participate in any reaction.

 HPMC For Putty 

HPMC for putty powder can be divided into instant type and hot-melt type. The instant product disperses quickly in cold water and disappears in the water. At this time, the liquid has no viscosity, because HPMC is only dispersed in water without real dissolution. In about 2 minutes, the viscosity of the liquid gradually increased, forming a transparent viscous colloid. It has a wide range of applications. It can be used in putty powder and mortar, as well as in liquid glue and paint. There are no contraindications. Hot-melt type products, when they come together in cold water, they can quickly disperse in hot water and disappear in hot water. When the temperature drops to a certain temperature, the viscosity slowly appears until a transparent viscous colloid is formed. Hot-melt type can only be used in putty powder and mortar. In liquid glue and paint, clumping will occur and cannot be used.

The viscosity of HPMC For Putty is inversely proportional to temperature, that is, the viscosity increases as the temperature decreases. We usually say that the viscosity of a product refers to 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 the cellulose will increase, and the hand will feel heavy when scraped.

The Development Trend of Cellulose Ether

 Cellulose Ether has the basic structure of cellulose-anhydroglucose structure. In the process of producing cellulose ether, the cellulose fiber is first heated in an alkaline solution, and then treated with an etherifying agent. The fibrous reaction product is purified and ground to form a uniform powder with a certain fineness.

In the production process of MC, only methyl chloride is used as an etherifying agent; in addition to methyl chloride, propylene oxide is also used to obtain hydroxypropyl substituents in the production of HPMC. Various cellulose ethers have different methyl and hydroxypropyl substitution rates, which affect the organic compatibility and thermal gel temperature of the cellulose ether solution.

Due to the structural differences in market demand for cellulose ethers, a situation where companies with different strengths can coexist. In view of the obvious characteristics of structural differentiation of market demand, domestic cellulose ether manufacturers have adopted a differentiated competitive strategy based on their own strengths, and at the same time, they have a good grasp of the development trend and direction of the market.

(1) Ensuring product quality stability will still be the core competitiveness of cellulose ether companies.

Cellulose ether accounts for a relatively small part of the production cost of most downstream enterprises in this industry, but it has a greater impact on product quality. Before using a certain brand of cellulose ether, the mid-to-high-end customer groups must go through formulation experiments. After a stable formula is formed, it is usually not easy to replace products of other brands. At the same time, higher requirements are placed on the quality stability of cellulose ether. This phenomenon is more prominent in high-end fields such as large domestic and foreign building materials manufacturers, pharmaceutical excipients, food additives, and PVC. In order to improve the competitiveness of products, manufacturers must ensure that the different batches of cellulose ether supplied can maintain quality stability for a long time, in order to form a better market reputation.

Cellulose Ether

(2) Improving the level of product application technology is the development direction of cellulose ether enterprises

With the increasingly mature production technology of Cellulose Ether HPMC, a higher level of application technology is conducive to enterprises to enhance their comprehensive competitiveness and form stable customer relationships. Well-known cellulose ether companies in developed countries mainly adopt the competitive strategy of "facing large-scale high-end customers + developing downstream uses and usage", develop cellulose ether uses and use formulas, and configure series of products according to different sub-application areas to facilitate customer use , And to cultivate downstream market demand. The competition of cellulose ether enterprises in developed countries has moved from product to application technology competition.

Cellulose ether is known as "industrial monosodium glutamate". It has the advantages of wide use, small unit consumption, good modification effect, and environmental friendliness. It is widely used in building materials, medicine, food, textiles, daily chemicals, petroleum extraction, and mining. , Papermaking, polymerization, aerospace and many other fields.

 

What Is the Difference Between Hpmc and Mc?

 MC is methyl cellulose, which is made into cellulose ether by a series of reactions after the refined cotton is treated with alkali, using methyl chloride as the etherification agent. Generally, the degree of substitution is 1.6~2.0, and the solubility varies with the degree of substitution. Belongs to non-ionic cellulose ether.

(1) The water retention of methyl cellulose depends on its addition, 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 the greatest influence on the water retention rate, and the viscosity is not proportional to the water retention rate. The dissolution rate mainly depends on the degree of surface modification of the cellulose particles and the particle fineness. Among the above cellulose ethers, methyl cellulose and hydroxypropyl methyl cellulose have higher water retention rates.

(2) Methyl cellulose 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, guar gum, etc. and many surfactants. When the temperature reaches the gelation temperature, 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. If the mortar temperature exceeds 40°C, the water retention of methyl cellulose will be significantly worsened, which will seriously affect the workability of the mortar.

(4) Methyl cellulose has a significant effect on the workability and adhesion of the mortar. The "adhesion" here 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, and the force required by the workers in the use process is also large, and the workability of the mortar is poor. In cellulose ether products, the adhesion of methyl cellulose is at a medium level.

Hydroxypropyl Methylcellulose

HPMC is hydroxypropyl methylcellulose, which is a mixture of non-ionic cellulose made from refined cotton after alkalization, using propylene oxide and methyl chloride as etherification agents, through a series of reactions ether. The degree of substitution is generally 1.2 to 2.0. Its properties are different by the ratio of methoxy content and hydroxypropyl content.

(1) Hydroxypropyl methylcellulose is easily soluble in cold water, and it will be difficult to dissolve in hot water. But its gelation temperature in hot water is significantly higher than that of methyl cellulose. The dissolution in cold water is also greatly improved compared to methyl cellulose.

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

(3) Hydroxypropyl methylcellulose is stable to acid and alkali, 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 its performance, but alkali can speed up its dissolution rate and increase viscosity. Hydroxypropyl methylcellulose is stable 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 its addition amount, viscosity, etc. The water retention rate under the same addition amount is higher than that of methyl cellulose.

(5) Hydroxypropyl Methyl Cellulose can be mixed with water-soluble polymer compounds to form a uniform and higher viscosity solution. Such as polyvinyl alcohol, starch ether, vegetable glue, etc.

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

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