The grade of construction glue is an issue that bothers customers.
1. The grade of construction adhesive should take into account the raw materials. The key reason for the formation of the bonding layer is the incompatibility between acrylic emulsion and hydroxypropyl methylcellulose (HPMC).
2. Due to insufficient mixing time; construction adhesive also has the problem of poor thickening properties. In construction adhesives, it is important to use instant coffee hydroxypropyl methylcellulose (HPMC) because HPMC is just dispersed in the water and does not really dissolve. After about 2 minutes, the viscosity of the liquid slowly increases, producing a completely transparent viscous colloidal solution. Hot-melt products can quickly disperse in boiling water and disappear in boiling water when encountering cold water. When the temperature drops to a certain temperature, viscosity retardation occurs until a completely transparent viscous colloidal solution is produced. It is strongly recommended to use 2-4 kg of hydroxypropyl methylcellulose (HPMC) in construction adhesives.
3. The physical properties of hydroxypropyl methylcellulose (HPMC) in construction adhesives are stable, the anti-mildew effect is very good, and it will not be damaged by changes in pH value. The viscosity can be applied between 100,000 s and 200,000 s, but in production When manufacturing, the higher the viscosity, the better. Viscosity is inversely proportional to the compressive strength of the adhesive. The higher the viscosity, the lower the compressive strength. Generally, the viscosity is 100,000s.
Now in the decoration industry, the application of hydroxypropyl methylcellulose is more stringent.
How to manipulate this quantity? Take you through:
Immediately mix CMC with water to make a paste-like adhesive and set aside. When installing the CMC paste, use a mixer to add a certain amount of cold water to the ingredients pot. When the mixer is started, slowly and evenly sprinkle the carboxymethylcellulose into the ingredient tank, and continue stirring to fully combine the carboxymethylcellulose with water and completely dissolve the carboxymethylcellulose. When dissolving the tube board, it is often necessary to disperse it evenly and keep stirring to better “prevent the formation and formation of the tube board when it encounters water, reduce the problem of tube board dissolution” and improve the solubility of the tube board. Management committee dissolution rate.
The mixing time is different from the time it takes for CMC to completely dissolve. These are two definitions. In general, the mixing time is much shorter than the time for complete dissolution of CMC, depending on the specific situation. The mixing time is determined based on static data standards. When CMC is evenly dispersed in water without obvious agglomeration, mixing is terminated to allow CMC and water to penetrate each other.
There are several reasons for the time required to completely dissolve CMC:
(1) CMC and water are completely integrated, and there is no solid-liquid separation equipment between them;
(2) The mixture is uniform and smooth, and the surface is smooth and moist;
(3) After mixing, the paste is colorless and completely transparent, and there are no particles in the paste. It takes 10 to 20 hours from the time CMC is put into the mixture of ingredients tank and water until it is completely dissolved.