General knowledge of paint: introduction to manufacturing process of color paint (2)

Key tips: Section II pigment dispersion process T C Patton divided the dispersion process of pigment into three stages: wetting, depolymerization and stabilization 1、 Wetting process Replace the adsorbed air and water on the surface of pigment particles with paint, wet the pigment, and further attach the pigment surface Average infiltration rate: where: u: Average penetration rate of liquid cm3 / S Cos θ: cosine value of contact angle γ: Surface tension of paint n / M η: Paint viscosity p R: Capillary radius cm 50: Length of pore CMRL: surface tension of liquid; RS Paint knowledge how about Akzo Nobel Powder Coating Recommended introduction: powder coating is a kind of coating with different form from general coating, which is in powder form It is a new type of coating, because of its own advantages and more and more known by people Let's introduce Akzo Nobel Powder coating Akzo Nobel Powder coating is a cost-effective coating solution, which can be applied to different kinds of products After the treatment of static electricity and fire baking, a tough and durable coating surface will be formed, with the least impact on the environment Since the introduction of this technology, powder coating has been able to continue to maintain the In the second section, T.C Patton divided the dispersion process into three stages: wetting, depolymerization and stabilization 1、 In the wetting process, the paint is used to replace the air and water adsorbed on the surface of pigment particles, wet the pigment and attach the pigment surface Average penetration rate: where: u: average penetration rate of liquid cm 3 / s cos θ: cosine value of contact angle γ: surface tension of paint n / m η: viscosity of paint P R: capillary radius cm L: length of pores cm r l: surface tension of liquid; r s: surface tension of solid; R SL: surface tension between solid and liquid; θ: contact angle (1) try to use paint with low surface tension (2) Select the paint with low solid content to grind and disperse (3) Choose some wetting agent (4) Choose the right dispersant (5) Select the surface treated pigment with small particle size (6) The paint slurry is premixed and heated to 50 ℃, then it is allowed to stand overnight, and then it is ground and dispersed 2、 During the depolymerization process, the pigment particles are mechanically opened and separated into isolated original particles Depolymerization is the main and most energy consuming process in the process of color paint manufacturing In the process of depolymerization of pigment particles, not only can the surface of pigment (filler) particles be fully wetted by the liquid paint, but also can the stability of paint paste be improved With the increase of pigment dispersion, the coloring power and covering power of pigment will be increased accordingly, and the luster and other properties of paint film will be improved In order to produce as many and stable abrasive pastes as possible in the shortest time and with as little energy as possible, the following conditions are usually required: (1) there is a well-designed standard formula of color paint It includes the selection of pigments (fillers) with good dispersing performance, the scientific formulation of pigments and paints, the selection of suitable solvents and additives such as wetting and dispersing; (2) the selection of high-efficiency grinding and dispersing equipment combined with the characteristics of paint varieties to provide the best parameters and scientific operation methods of the equipment; (3) The dispersion of the slurry was carried out with a reasonable composition of the slurry (i.e the appropriate proportion of paint, pigment and solvent); and (4) the evaluation of the depolymerization process Fineness: the maximum size of pigment particle allowed in the paint It is usually measured with a scraper fineness meter, expressed in μ M Primer: 60 μ m; common enamel: 20 μ M 3、 The process of stabilizing wet pigment particles and moving them into the liquid paint to be permanently separated from the continuous, non-volatile film-forming material The dispersion system of pigment in paint can be stabilized by two mechanisms That is, charge stabilization and space potential resistance or entropy stabilization (1) Charge stabilization the charge stabilization is the result of electric repulsion The electric repulsion force is generated by a double electric layer surrounding the pigment particles Because all particles are surrounded by the same charge, they repel each other when they are close together In general, in the aqueous dispersion system, because of the high dielectric constant of pigment particles, the stabilizing effect of electric charge is more prominent In the solvent coating, because the polarity of the organic solvent is weak, the stabilizing effect of electric charge is not important The stabilizing effect of the dispersion system mainly depends on the effect of space potential resistance (2) Steric resistance stabilization When large pigment particles are depolymerized into a number of smaller particles, a new surface is usually formed The new surface is timely wetted by the paint, so that the surface of pigment particles is covered by a resin with sufficient thickness Because the general paint materials have polar groups such as - Oh, - COOH, etc., it is easy to adsorb on the paint to form a protective barrier with a certain thickness, so as to give the moving pigment particles contact and collide with each other Resistance That is, once two pigment particles are close to each other due to movement, the surrounding resin layer will be squeezed to reduce the entropy, but the entropy has the trend of natural enhancement, so there is an entropy repulsion force, the opposite force relative to the extrusion, so that the approaching pigment particles are separated from each other, which is the so-called steric resistance stabilization (or entropy stabilization) Table 12.1 relationship between pigment dispersion process and technological process paint house focuses on news information and coatings of coatings, diatom mud, paint coating, coating process, fire retardant coating, diatom mud, paint coating, coating process, decoration knowledge and decoration effect map of fire retardant coating,