The role of hydroxypropyl methylcellulose (HPMC) in putty

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

1.Hydroxypropyl content and viscosity, most users are concerned about these two indicators. 

The higher the hydroxypropyl content, the better the water retention. The higher the viscosity, the better the water retention,

and the higher the viscosity, the better it is to use in cement mortar.

2. What is the main role of HPMC in putty powder? 

HPMC has three functions in putty powder: thickening, water retention and construction.

Thickening: Cellulose can thicken and suspend, keep the solution uniform and consistent, and resist sagging. 

Water retention: Make the putty powder dry slower and assist the reaction of lime calcium under the action of water. 

Construction: Cellulose has a lubricating effect, which can make the putty powder have good construction properties.

3. Is the powdering of putty powder related to HPMC?

The powdering of putty powder is mainly related to the quality of lime calcium, and has little to do with HPMC. 

The calcium content of lime and the inappropriate ratio of CaO and Ca(OH)2 in lime will cause powder loss. 

If it has something to do with HPMC, then the poor water retention of HPMC will also cause powder loss.

4. How much hydroxypropyl methylcellulose (HPMC) should be added to putty powder?

The amount of HPMC used in actual applications varies depending on the climate, 

temperature, local lime quality, putty powder formula and "quality required by customers". Generally speaking, 

it is between 4 kg and 5 kg. For example: most putty powders in Beijing are 5 kg; 

most of them in Guizhou are 5 kg in summer and 4.5 kg in winter; the amount in Yunnan is smaller, generally 3 kg to 4 kg, etc.

5. What is the appropriate viscosity of hydroxypropyl methylcellulose (HPMC)?

Putty powder is generally 100,000, and the requirement in mortar is higher, 150,000 is good for 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, the viscosity is lower (70,000-80,000), it is also acceptable.

Of course, the higher the viscosity, the better the water retention. When the viscosity exceeds 100,000, the viscosity has little effect on water retention.

6. How to choose the right hydroxypropyl methylcellulose (HPMC) for different uses?

Application of putty powder: the requirements are relatively low, and the viscosity of 100,000 is enough. 

The important thing is to have good water retention. Application of mortar: the requirements are higher,

requiring high viscosity, 150,000 is better. Application of glue: requiring instant products with high viscosity.

7. Application of HPMC in putty powder, what is the reason for bubbles in putty powder?

HPMC plays three roles in putty powder: thickening, water retention and construction. 

It does not participate in any reaction. Reasons for bubbles:

(1) Too much water is added.

(2) The bottom layer is not dry, and another layer is scraped on it, which is also easy to bubble.

Name:Charles Deng  

E-mail:charles.deng@jtdf-rdp.com

Whatsapp:(86)150-6919-9138