Coating process: how to determine the calcium stability of emulsions

Core tip: in the preparation of various interior and exterior wall building coatings, it is necessary to add pigments, fillers, organic and inorganic additives, salts and other additives These additives may form a certain amount of electrolyte in water, and the dispersion state of polymer emulsion is damaged to varying degrees In order to evaluate whether styrene acrylic emulsion can withstand the destruction of these electrolytes, the "calcium stability" is used as a performance index to indicate the "mixed stability" of styrene acrylic emulsion and various additives, also known as "Chemistry" Application scope and advantages of roller ceramic coating Recommended introduction: the surface of ceramic rubber plate used for roller ceramic coating is cast into durable rubber plate by hundreds of independent small ceramic pieces Each ceramic piece has raised characteristics Under general conveyor belt pressure, thousands of unique cast bumps can produce positive traction, prevent slipping and extend the service life of conveyor belt roller At the same time, the bottom layer adopts high-quality rubber, which has strong elasticity and can play a good impact resistance role The scope of application of roller ceramic coating is one three six 83857180 (the same as V) 1 Roller coating in extremely harsh working environment 2 The belt joint is not suitable for fixing with iron buckle; 3 It is suitable for leather Paint Home News: in the preparation of a variety of interior and exterior wall building coatings, we need to add pigments, fillers, organic and inorganic additives and salts and other additives These additives may form a certain amount of electrolyte in water, and the dispersion state of polymer emulsion is damaged to varying degrees In order to evaluate whether styrene acrylic emulsion can withstand the destruction of these electrolytes, the "calcium stability" is used as a performance index to indicate the "mixed stability" of styrene acrylic emulsion and various additives, also known as "chemical stability" 1 when using styrene acrylic emulsion to prepare composite coatings, if used together with silica sol, the coating will soon become bloated until the rubber minister scrapped 2 when using some low temperature sintered sand and styrene acrylic emulsion to prepare colored sand coating, it is easy to appear bloating, demulsification and gelling because of the amount of water-soluble salts in low-temperature sintered sand 3 styrene acrylic emulsion is usually used to crosslink metal ions at room temperature to improve its performance But when the metal ion crosslinking agent is added, styrene acrylic emulsion will be agglomerated and agglomerated 4 when using styrene acrylic emulsion to prepare calcium carbonate as filler for internal and external wall coatings, it is easy to divide, expand and precipitate in the storage period In short, heavy metal ions can cause emulsion flocculation or demulsification Calcium carbonate (mainly referred to as light calcium), will produce a large number of free calcium, which will damage the stability of emulsion However, for the use of light calcium, it is not recommended (especially for the exterior wall) The large use of light calcium in the formula will destroy the water resistance of the paint film However, the excellent "dry covering" effect of light calcium will make many engineers use a lot in the low cost interior wall (latex paint accounts for the biggest cost is latex, Tai Bai), so the stability of calcium ions also appears There are usually two ways to determine the calcium stability of emulsions First, prepare 5% calcium chloride aqueous solution: weigh 5g anhydrous calcium chloride with 1% balance, add 95ml water, shake well, and reserve In the 10ml test tube with calibration, the 5ml emulsion was added with a dropper and then added with 1ml5% CaCl2 solution It should be added slowly, fully shaken and placed on the test tube rack, and observed after 1h, 24h and 48h respectively If stratification, sedimentation, flocculation and other phenomena occur, it is considered as unqualified Because the emulsion is added first in the test tube and then added with calcium chloride solution, there will be excessive local concentration on the two fluid contact surface Therefore, it can be weighed according to the above proportion, and after mixing evenly, it is placed in the test tube If the 5% calcium chloride solution fails, 0.5% calcium chloride solution is usually prepared and tested according to the above method Home of coatings is specialized in coatings, diatom mud, paint coating, coating technology, fire retardant coating news and coating, diatom mud, paint coating, coating technology, fire retardant coating decoration knowledge and decoration renderings,