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.
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