Water-based coating viscosity control technology---- thickening rheinant

water-based coatings to better meet the production, packaging, storage, construction needs, the formulation of the design of the coating to carry out rheumatoine control, water-based coatings in addition to resin, pigments, solvents will form the original rheumatoinproperteThe most direct and efficient way for engineers to control water-based coating rheological rheological agents is to add thickening rheological agentswhat is material rheology?rheology is a subject that studies the deformation and flow law of material molecules under external forcerheology includes Newtonian fluids and non-Newtonian fluids, Newtonian fluidpure liquid or low molecular matter in the condition of stratospheric flow, shear stress and shear rate are proportionalThe rheumatal properties of water-based coatings do not conform to the properties of Newtonian fluidsII, non-Newtonian fluidwater-based coatings have typical non-Newtonian fluid rheomorphic properties
mixtures, most liquids containing polymer or polymer do not follow Newton's law of viscosity, the flow of this substance shear speed and shear stress does not appear a line-type relationshipIt is achieved by the successive leap of the molecular chain segment, that is, the displacement of the whole macromolecular chain is completed through the gradual displacement of the chain segment1, viscosity, yield value, touch-and-decrease definitionviscosity is the internal friction altogether of the resistance flow of the fluid, and the entanglement between molecules and the force between the molecules, unitPa.s it is not a specific data value, it is corresponding to the shear rate deformation curveyield value: refers to the minimum moving stress required for a liquid to begin flowing The strength of the gel mesh structure inside the liquid is related, the yield value is too large, the fluidity will become worse, the yield value too small, easy to hang touch degeneration: refers to the phenomenon of thickening and thinning when the liquid is stirred by external forces It is related to the effect of the double-electric layer and flocculation of liquid formation shear-diluted non-Newtonian fluid: refers to the increasing shear force and the viscosity decreasing with the non-line type Such as: water-based paint shear expansion type non-Newtonian fluid: refers to the shear force increases, viscosity with non-line type increases For example: PVC suspension water-based coatings in the production, storage and transportation, construction process will produce different shear and rheumating requirements, which makes it necessary to adjust the water-based coating system according to the application requirements of different shear viscosity coatings according to their different operating conditions, there are different viscosity requirements, commonly used test viscosity can be broadly divided into the following three: 1 The viscosity in the storage state (Brookfield viscosity is tested by the Breitbart viscosity meter) the size of the coating viscosity will involve the length of its shelf life The coating is actually a solid liquid mixture, solid particles such as titanium dioxide , kaolin soil and other uniform distribution in the main resin solution, under the action of gravity, solid particles will settle to the bottom layer and layered, clumps cause disquality decline In this regard, the requires the paint in the storage state, to maintain a high viscosity to prevent settling 2 The viscosity of the coating when stirring (KU viscosity is tested by Stomer viscosity meter) the size of the coating viscosity will be related to its use performance, directly reflecting the user's ease of stirring the paint
3 The viscosity of the coating (ICI viscosity by the high shear cone plate viscosity test) the size of the coating viscosity directly reflects the performance of the paint under the conditions of coating, brushing, spray, rolling, etc The lower the viscosity, the better the performance three, water-based paint thickener rheumator definition and category
water-based paint thickener rheumator is
a kind of functional additive that can directly and efficiently change the original water-based paint rheo characteristics the commonly used thickenering rheumates in water-based coatings are divided into several major categories: polysaccharide derivatives, inorganic silicate, polyacrylates, polyurethane , gas-phase silica , polyamide wax and so on They have different thickening rheini in water-based coating systems , polysaccharides derivatives polyglycing polymers of glucose or glucose-like units connected by different glycoside bonds have significant thickening rheomorphic functions, including cellulose ether and non-cellulose ether 1, cellulose ether cellulose thickener molecular weight is generally very large Most aggregations are generally 10000-15000 The maximum molecular volume is more than 1.5 million Has a strong hydrogen bond hydration thickening capacity In water-based coatings, water thickening ability is strong cellulose thickeners are made from refined cotton through ether, the alternative base is selected different, cellulose ether types are different, there are methyl cellulose, methyl methyl cellulose, hydroxyevalulose, hydroxyl methyl cellulose, and so on, the performance is also very different But the mechanism of water phase thickening is basically similar cellulose thickener thickener thickening efficiency is high, water retention is strong, viscosity is strong, anti-deposition is superior, of which pure hydroxyl cellulose ether is mainly used in water-based coating it is not limited by surfactants, can be used pH range, thickening efficiency is high, through high-quality ether replacement after long-term storage stability Hydroxyl hydroxyl hydrophobic lalene technology can be formed with resinandand additives , which significantly improves the water resistance and splash resistance of cellulose ether in high concentration polar ethers or non-polar solvent systems, suitable replacement of base classes and replacement cellulose ether can also form good hydrogen bond effect and form its own rheology characteristics Pure hydroxyelycellulose is commonly used in water-based architectural coatings and hydrophobic modification categories are used in water-based industrial coatings The addition stake is generally 0.1-0.5% in the principle of water phase thickening: the polar group in cellulose ether and the surrounding solvent (water) molecules form a hydrogen bond, improve the fluid volume of the polymer itself, reduce the space of free movement of particles, thus improving the system viscosity and the integration of the molecular chain at the same time A cellulose ether hydroxyroxine (HEC) typical models: Rakuten
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