The use of amine catalyst alone will present a catalytic deficiency. Organometallic substances such as T-12 catalyst can produce a synergistic effect of increased activity with amine catalyst, making it suitable for the manufacture of rigid foams that require high-speed catalytic action, even though high-density structural foams, sprayed wall insulation adhesives and rigid panels are manufactured in high-speed production lines.
For high PVC latex paint, due to the low emulsion content and the high amount of pigments and fillers, in order to ensure no delamination during storage, its low shear viscosity and thixotropy should be controlled as high as possible, so HEC and alkali swelling thickeners can be used Cooperate to adjust the viscosity. The higher the PVC, the larger the selected HEC molecular weight, so that the cost of the thickener in the formulation can be lower. Medium PVC and low PVC latex paints, due to the higher emulsion content, can increase the associative type with different viscosity curves. Thickeners are used together to achieve a better balance of storage, construction, and flow.
It is also suggested that [291, in most cases, using HAS E and HEUR together with HEC, or using HAS E with HEUR together, can achieve satisfactory results. Only use HEC and HEUR together, because the difference in hydrophilicity and lipophilicity is too large, which often leads to water separation.
For thick and napped coatings, high thixotropic cellulose thickeners or micronized polypropylene wax alkali-soluble thickeners can be used.
Use of thickener
When two cellulose thickeners of the same type are used, their mixed viscosity can be estimated as follows:
lgV AB=z lg VA+(1-z) lg VB(19-6) where VAB- the mixed viscosity of the same type of cellulose thickener;
The viscosity of VA cellulose thickener A;
Vg—Viscosity of cellulose thickener B;
X-the mass fraction of cellulose thickener A.
The performance of the hydroxyethyl cellulose thickener can be carried out in accordance with ASTM D 2364-01 “Standard Test Method for Hydroxyethyl Cellulose”. Other types of thickeners can also be formulated into a certain concentration of aqueous solution to determine the viscosity.
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