First of all, the grade of construction glue should take into account the raw materials. The main reason for the layering of construction glue is the incompatibility between acrylic emulsion and hydroxypropyl methylcellulose (HPMC). Secondly, due to insufficient mixing time; there is also poor thickening performance of construction glue. In construction glue, you must use instant hydroxypropyl cellulose (HPMC), because HPMC is only dispersed in water, it does not really dissolve. After about 2 minutes, the viscosity of the liquid slowly increased, producing a completely transparent viscous colloidal solution. Hot-melt products, when exposed to cold water, can quickly disperse in boiling water and disappear in boiling water. When the temperature drops to a certain temperature, the viscosity slowly appears until a completely transparent viscous colloidal solution is produced. The strongly recommended dosage of hydroxypropyl methylcellulose (HPMC) in construction glue is 2-4KG.
Hydroxypropyl methylcellulose (HPMC) has stable physical properties in construction adhesives, and has a very good effect of removing mildew and locking water, and will not be affected by changes in pH value. The viscosity can be used between 100,000 s and 200,000 s. In manufacturing, the higher the viscosity, the better. Viscosity is inversely proportional to bond compressive strength. The higher the viscosity, the lower the compressive strength. Generally, the viscosity of 100,000 s is appropriate.
Mix CMC with water and make a muddy paste for later use. When installing CMC paste, add a certain amount of cold water to the batching tank with a stirring machine. When the stirring machine is started, slowly and evenly sprinkle the carboxymethyl cellulose into the batching tank, and continue to stir, so that the carboxymethyl cellulose and water are completely fused, and the carboxymethyl cellulose is completely dissolved. When dissolving the CMC, it is often necessary to disperse evenly and mix continuously, in order to better “prevent the clumping and agglomeration of the CMC after it meets water, and reduce the problem of CMC dissolution” and increase the dissolution rate of the CMC.
The mixing time is not the same as the time for CMC to completely dissolve. are 2 definitions. Generally speaking, the mixing time is much shorter than the time for CMC to completely dissolve, it depends on the details. The basis for judging the mixing time is that when CMC is uniformly dispersed in water without obvious lumps, the mixing can be stopped, so that CMC and water can penetrate into each other under static data conditions. There are several reasons for determining the time required for complete dissolution of CMC:
(1) CMC and water are completely integrated, and there is no solid-liquid separation equipment between them;
(2) The mixed paste is well-proportioned and normal, with a smooth and smooth surface;
(3) The mixed paste has no color and is completely transparent, and there are no particles in the paste. It takes 10 to 20 hours from the time when CMC is put into the batching tank and mixed with water until it is completely dissolved.
Post time: Jan-13-2023