Hydroxypropyl methylcellulose, referred to as: HPMC or MHPC. The appearance is white or off-white powder; the main use is as a dispersant in the production of polyvinyl chloride, and it is the main auxiliary agent for the preparation of PVC by suspension polymerization. In the construction process of the construction industry, it is mainly used in mechanized construction such as wall building, plastering, caulking, etc.; especially in decorative construction, it is used to paste ceramic tiles, marble, and plastic decorations. It has high bonding strength and can reduce the amount of cement. . It is used as a thickener in the paint industry, which can make the layer bright and delicate, prevent powder removal, improve leveling performance, etc.

In cement mortar and gypsum-based slurry, hydroxypropyl methylcellulose mainly plays the role of water retention and thickening, which can effectively improve the cohesive force and sag resistance of the slurry.

Factors such as air temperature, temperature and wind pressure speed will affect the volatilization rate of water in cement mortar and gypsum-based products. Therefore, in different seasons, there are some differences in the water retention effect of products with the same amount of hydroxypropyl methylcellulose added.

In the specific construction, the water retention effect of the slurry can be adjusted by increasing or decreasing the amount of HPMC added. The water retention of methyl cellulose ether under high temperature conditions is an important indicator to distinguish the quality of methyl cellulose ether.

Excellent hydroxypropyl methylcellulose series products can effectively solve the problem of water retention under high temperature. In high temperature seasons, especially in hot and dry areas and thin-layer construction on the sunny side, high-quality HPMC is required to improve the water retention of the slurry.

High-quality HPMC has very good uniformity. Its methoxy and hydroxypropoxy groups are evenly distributed along the cellulose molecular chain, which can improve the ability of the oxygen atoms on the hydroxyl and ether bonds to associate with water to form hydrogen bonds. , so that free water becomes bound water, so as to effectively control the evaporation of water caused by high temperature weather, and achieve high water retention.

Water is required for hydration in order to set cementitious materials such as cement and gypsum. The correct amount of HPMC can keep the moisture in the mortar for a long enough time so that the setting and hardening process can continue.

The amount of HPMC required to obtain sufficient water retention depends on:

1. The absorbency of the base layer

2. Composition of mortar

3. Mortar layer thickness

4. Water demand of mortar

5. The setting time of the gelling material

High-quality hydroxypropyl methylcellulose can be uniformly and effectively dispersed in cement mortar and gypsum-based products, and wrap all solid particles, and form a wetting film, and the moisture in the base is gradually released over a long period of time , and the hydration reaction with the inorganic gelling material to ensure the bonding strength and compressive strength of the material.

Therefore, in high-temperature summer construction, in order to achieve the water retention effect, it is necessary to add high-quality HPMC products in sufficient quantities according to the formula, otherwise, there will be insufficient hydration, reduced strength, cracking, hollowing and shedding caused by excessive drying. problems, but also increase the construction difficulty of workers. As the temperature drops, the amount of water HPMC added can be gradually reduced, and the same water retention effect can be achieved.