Coating technology: common color matching problems of emulsion paint

Core tip: the use of water-based color paste to color emulsion paint has been accepted by most coating manufacturers In the process of color matching, the color, weather resistance, covering power, physical and mechanical properties of the coating, color matching price, toxicity and other aspects must be considered It is very difficult to achieve the optimization of all aspects, and various quality problems often occur due to the consideration of one thing or the other This paper points out the problems that are easy to appear in the process of color matching of emulsion paint, analyzes the causes and solutions, and sums up the best method of color paste for color matching of emulsion paint Problem analysis and solution Shenyang steel structure fireproof coating construction expert punde Building Fire Engineering Co., Ltd Recommended introduction: since its establishment, Shenyang punde Construction Fire Engineering Co., Ltd has cultivated a group of professional construction teams with excellent equipment, rich experience and serious responsibility with advanced and scientific management methods and strict engineering quality assurance and after-sales service system It has undertaken a number of fire system installation projects, which has been praised by customers Every idea and special requirement of you will be fully considered by us and fully realized in the construction technology, which will become the cornerstone of our successful long-term development We are looking forward to your invitation, to provide you with quality services and high-quality technical support! All construction coatings have passed ISO9001 Paint Home News: the use of water-based color paste to color emulsion paint has been accepted by most paint manufacturers In the process of color matching, the color, weather resistance, covering power, physical and mechanical properties of the coating, color matching price, toxicity and other aspects must be considered It is very difficult to achieve the optimization of all aspects, and various quality problems often occur due to the consideration of one thing or the other This paper points out the problems that are easy to appear in the process of color matching of emulsion paint, analyzes the causes and solutions, and sums up the best method of color paste for color matching of emulsion paint Problem analysis and solution: compatibility of emulsion paint and water-based color paste: 1 When water-based color paste is used to color emulsion paint, it is necessary to have good compatibility between water-based color paste and emulsion paint If the compatibility is not good, flocculation, floating color, blooming, coloring force drop, color phase shift, fineness increase, gloss decrease, paint stability deterioration and other phenomena will occur 2 The best way to judge the compatibility is to do the finger grind experiment The operation method is: add the largest amount of color paste into the latex paint, mix and mix evenly, then apply it on the scraping paper, wipe it with your finger for about one minute before the surface is dry, and observe whether there is any color difference between the wiped part and the non wiped part after dry If there is no color difference, it indicates good compatibility: if there is color difference, it indicates that There is flocculation in the pigment, and the wiped part is Deflocculated due to external force 3 Other methods can be used to test the compatibility: (1) observe the change of color phase, flocculation will make the color phase red shift; (2) measure the fineness; (3) spray coating experiment There are generally two reasons for poor compatibility: first, the dispersion stability of the color paste is poor, which is prone to flocculation, floating, blooming and other defects, which requires users to choose high-performance color paste with good dispersion and stability; the other reason may be that the amount of wetting dispersant in the emulsion paint is insufficient or inappropriate, After the color paste is added, the pigment and filler particles in the emulsion paint seize the dispersant on the surface of the color paste to make the color paste pigment flocculate At this time, it is necessary to increase the amount of the dispersant or change the wetting dispersant until the compatibility test is passed It is worth mentioning that when the color paste has good compatibility with the emulsion paint, after the color paste is added to the emulsion paint, it is generally only necessary to mix evenly with the disperser or the blender, and there is no need for sanding or high-speed dispersion Under the condition of sanding or high-speed dispersion, the high shear force will further disperse the color and filler in the emulsion paint to produce a new surface The new surface needs to be stabilized by an absorbent dispersant, which may cause flocculation of the pigment in the color paste Color accuracy and reproducibility: 1 Emulsion paint color matching is to give the paint a rich color, which requires that the color must have a good accuracy and reproducibility Accuracy and reproducibility are relatively independent and interrelated, they are important to users, and reproducibility between batches may be more important to the same user 2 There are many factors that affect the accuracy and reproducibility of color, the most important of which are the stability of color paste quality, the accuracy of color formula and the stability of base paint Under the premise of stable basic inspection, latex paint uses ordinary color paste which is not supported by color matching software for color matching It is totally based on experience and needs to be corrected repeatedly, which will inevitably result in poor accuracy and reproducibility However, with high-quality color paste supported by color matching software, color matching will have good accuracy and reproducibility This is because they are essentially different in the stability of color paste quality and the accuracy of color formula From the above analysis, we can realize that the simplest and feasible way to achieve color accuracy and reproducibility is to use high-quality color paste color matching supported by color matching software Brightness of color: in the process of color matching of emulsion paint, it is often encountered that the color is not bright enough, or the saturation is poor Generally, there are several reasons for this situation: 1 The saturation of color paste is not enough; 2 The color paste system adopted cannot cover the whole color space well, and the color paste far away from the color coordinate point is used for color mixing Even if the color with similar color can be called out, the saturation will be greatly reduced; 3 Too many color pastes are used in the color formula, Even if complementary colors are used in the same formula, the saturation will be greatly reduced Because the color mixing is a subtractive mixing, the color will be dim; 4 The emulsion paint contains too much white pigment or the dry covering power generated by too high PVC will be diluted It is necessary to obtain bright colors Attention should be paid to the following problems: 1 The pigments used to make the color paste must be bright Because the structure, crystal form, size of the original pigment particles and other aspects affect the brightness of the colors, the pigments used to make the color paste should be strictly controlled 2 The color paste system used should be able to cover the whole color space well, Any color can be modulated by finding a color paste with a relatively close color space from the color paste system, so as to ensure the consistency of the color phase under the condition of not too much sacrificing saturation; 3 The color paste types selected in the color formula should be as few as possible, as long as the color paste system used is appropriate, Any kind of color can be called out as long as four kinds of color pastes at most Too many kinds of color pastes are not only dim, but also uneconomical 4 High saturation colors generally do not use white pigments, but can be modulated with varnish If there is too much white pigment or white pigment in the base paint, the saturation will be reduced or a large amount of color paste will be added to achieve sufficient saturation, which will greatly increase the cost of color matching, and may also affect other properties of the paint; 5 In latex paint, the method of "dry covering power" generated by improving PVC of the paint is often used to reduce the cost, When the color with high saturation is modulated, the "dry covering power" will dilute the color and reduce the saturation like the white pigment, so the PVC of the paint should not be too high, generally not more than 45% The high-quality color paste system supported by the color matching software can completely cover the whole color space Each color paste has strict control over its hue and color intensity, and has good brilliance In all color formulas, follow the principle that the same formula does not use complementary colors According to the color matching principle that each formula uses up to four color pastes, the brilliance of colors can be fully guaranteed Weatherability: weatherability is one of the most important properties of exterior wall emulsion paint However, due to the long testing time and expensive testing instruments, there is no good testing method so far, so it is the most difficult index for coating manufacturers to grasp and the most prone to quality problems The reasons for poor weather resistance are often the following: (1) the chemical structure and crystal form of the pigment are not suitable; (2) the coloured pastes with the same weathering resistance are selected in light colored and dark lacquer; (3) the particle size of pigment is too small; (4) the weatherability of emulsion in paint is too poor; (5) the pigment volume of pigment is too large Therefore, in order to obtain the coating with good weather resistance, the above factors must be considered comprehensively 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,