Common knowledge of coating: basic composition of coating (4)

Core tips: Section 4: auxiliary membrane forming substances Generally, the amount of auxiliary film-forming materials is not much, some of them are little, but they have a great influence on the quality of the coating, the film-forming process and the quality and performance of the final film, and some of them play a key role With the increasing demand for coatings, the development of additives has become a key factor restricting the quality of coating industry, which has become a consensus in the coating industry in China Paint additives are divided into: Driers; bioactive additives; rheological improvers; pigment dispersants There are defoamers, matting agents, leveling agents, anti settling agents, anti skinning agents, anti UV agents and so on 1、 Driers oxidation Which is the price of Dajin diatom mud Recommended brief introduction: which is the price of Dajin diatom mud? How to buy genuine diatom mud? Guangdong diatom mud agent suggests placing a basin of cold water in the air conditioning room, so that the diatom mud wall can breathe effectively The feature of the breathing wall is obvious When the indoor air is dry, the diatom mud wall will release the absorbed water quickly Put it out to help regulate the indoor dry humidity It is suggested to place a basin of cold water in the air conditioning room, so that the wall of diatom mud can breathe effectively The feature of the wall that can breathe is obvious When the indoor air is relatively dry, the wall of diatom mud will absorb the water Coating home news: Section IV auxiliary film forming materials auxiliary film forming materials, generally the amount is not much, some of them are little, but they have a great impact on the coating quality, film forming process and the quality and performance of the final film, some of them play a key role With the increasing demand for coatings, the development of additives has become a key factor restricting the quality of coating industry, which has become a consensus in the coating industry in China Paint additives are divided into: driers; bioactive additives; rheological modifiers; pigment dispersants and defoamers, matting agents, leveling agents, anti settling agents, anti skinning agents, anti UV agents, etc 1、 It is used in the oxidation drying type coating Function: it can significantly improve the curing speed and shorten the drying time of the coating There are many compounds that can accelerate drying, but lead, cobalt and manganese salts of naphthenic acid, octanoic acid, rosin acid and linoleic acid are widely used Due to the toxicity of lead salt, there have been some low toxic and non-toxic driers, such as zirconium driers, which are characterized by light color and non-toxic They can replace lead driers to improve the adhesion, hardness, luster and light retention of the film, and will not fade in case of sulfide The disadvantage is the high price It is generally believed that the desiccant can promote the oxidation of the double bonds on the main chain of the dry oil, form peroxides, decompose the peroxide bonds to produce free radicals, and accelerate the crosslinking and curing 1 Characteristics of cobalt drier: surface drier When used alone, it is easy to form conjunctiva on the surface and keep the inner layer dry for a long time It is often used in combination with Pb drier The dosage is less than 0.1% of metal Most common: cobalt naphthenate 2 The surface driers of manganese driers, but the driers ability is not as good as cobalt, so it is conducive to the drying of the inner layer of the paint film Disadvantages: the color is deep and tends to turn yellow, so it is not suitable for white or light colored paint Commonly used: Manganese naphthenate The dosage is less than 0.3% of metal 3 The inner layer drier of lead drier is often combined with CO or Mn drier, and the ratio of Pb to CO, Mn is 10:1 Main: lead naphthenate, 0.5% - 1% of which can be replaced by zirconium salt 4 The rare earth drier has both surface and bottom dryness The main component is cerium carboxylate The amount of CO was reduced and Pb was replaced 2、 In marine antifouling coatings, mercury oxide, cuprous oxide and tributyltin oxide self polishing antifouling coatings are used The polymer organotin compounds, which are copolymerized with unsaturated monomers, are not only very volatile, but also have self polishing effect 2 Most of the emulsion paint used for water-based emulsion paint is added with cellulose as thickener, which is easy to grow mold during storage or under wet conditions The commonly used fungicides and fungicides are: phenols: pentachlorophenol sodium organic mercury: phenylmercury acetate; organotin: tributyltin; now there are biological active additives 3、 Rheological modifiers are commonly used in solvent based coatings called thixotropic agents, and thickeners in latex paints 1 Common thixotropic agent: gas phase SiO2; organic bentonite 2 Common thickeners: (1) cellulose ethers: sodium carboxymethylcellulose, ethyl, hydroxyethyl cellulose; (2) alkali sensitive acrylic polymer thickener (3) associating thickener of polyepoxyethane framework; 4 Pigment dispersant pigment dispersant is a kind of surfactant, which is used to help promote the wetting of pigments and fillers Even if they are well dispersed and wetted, dispersants are often used to ensure even dispersion, because when they are adsorbed on the surface of pigments and fillers, the electric repulsion effect and steric resistance effect can prevent re agglomeration Polyelectrolyte: mainly used in water-based coatings There are: sodium polyacrylate, ammonium salt of styrene maleic acid copolymer 2 Low viscosity silicone oil: used for solvent coating Such as: amino baking paint 3 Polyamines and alcoholamines: propanediamine, suitable for dispersion of clay 2-amino-2-methyl-1-propanol (AMP-95) tenlo 70 from Henkel company is a good carbon black dispersant 4 Polyphosphate: used for emulsion paint Potassium tripolyphosphate, tetrapotassium pyrophosphate 5 A-B block copolymers: suitable for a variety of pigments Segment a: containing multiple polar groups, combined with chemical groups on the surface of pigment particles; segment B: suitable molecular weight, low polar or non-polar polymer chain, soluble in organic solvents or base materials 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,