1 Overview
As an important part of latex paint, pigment mainly plays the role of covering, decoration and protection, and has an important impact on the weather resistance, water resistance, alkali resistance, washing resistance and pollution resistance . In order to obtain relatively stable latex paints, good dispersion of pigments is the primary issue in production.
In the traditional refining method, in the process of making paint, especially when preparing recolor paint, the pigment used should be dispersed in the base material, and evenly dispersed particle size. However, the degree of difficulty of pigment dispersion is different . Difficult to disperse pigments affect the dispersion of easily dispersible pigments, which will inevitably cause problems such as prolonged working hours, increased energy consumption, unstable paint quality, and poor compatibility of pigments. Moreover, the hydrophobicity of organic pigments causes great inconvenience to the coloring of latex paints. In fact, it is impossible to directly add pigments into emulsions. The pigments added to the emulsion cannot be fully wetted or not wetted at all, and the balance of the emulsion is easily destroyed, resulting in the separation of part of the water, which eventually leads to co-precipitation of polymer particles and demulsification.
From the technical point of view, to obtain excellent pigment compatibility, the appropriate method is to fully disperse and wet the organic or inorganic pigments, make a color paste, and add it to the base material . Pigments exist in liquid form, making paint production simple and easy to operate. "On-site configuration, self-configuration and self-use" has become a development trend.
2 Basic situation of color paste for latex paint
Color pastes for latex paints play a decorative role in architectural coatings, and require excellent dispersion stability, light resistance, weather resistance, and compatibility with paints. Foreign color pastes for latex paints produced by specialized companies, such as BASF in Germany, Hurst, Finland's Tikkurila and Switzerland's Ciba Specialty Chemicals, etc. CHINA has also carried out fruitful , such as the special series of pigment pastes for exterior wall latex paints developed and produced by Changzhou Paint Chemical Research Institute of the Ministry of Chemical Industry . There are also some companies that provide good toner , and provide basic technology for domestic manufacturers to produce color paste. According to the light fastness the latex paint color paste can be divided into internal use and external use. Usually external use can be used for internal use, but the color paste for internal use must not be used externally. The latex paint for internal use is light in color and the amount of color paste is small; the color paste for external use is mainly considered from the aspects of light resistance, weather resistance, alkali resistance, tinting strength, storage stability, and compatibility with latex paint. The compatibility between color paste and latex paint mainly refers to the color development of color paste in latex paint, and the influence of color paste on the viscosity and storage of latex paint. The color paste for latex paint needs to be easy to disperse and stable in dispersion.
If the color paste is unstable in latex paint, delamination and floating colors will occur. Exterior wall latex paint mainly uses iron-based pigments and high-grade organic pigments with excellent weather resistance, commonly used are phthalocyanines, condensed azos, quinacridones, etc. The United States has also developed an inhibited metal powder pigment paste containing molybdate pigments suitable for water-based paints . Inorganic pigments are often coated to improve their dispersibility, such as coating carbonyl iron powder with SiO 2 and then TiO 2 to obtain a purple pigment with good dispersibility; iron-aluminum composite oxide hydroxide coating iron oxide hydroxide core Iron oxide yellow hydroxide particles produced by particles , etc. At present, the wetting and dispersing agent for color paste is mainly a polymer dispersant, and the smaller There are mainly polyurethane and acrylic polymers, such as polyurethane or polyacrylate copolymers with amine functional groups developed in Italy. A general-purpose coloring polymer compound of a dispersant , acrylic-styrene copolymer and alkali neutralization can produce a narrow particle size distribution and good stability of the pigment dispersion, which can be prepared with vinyl ether, acrylate and amorphous silica Cationic system can be used as matting color paste, etc., and alkali metal salt dispersant can also be used to disperse carbon black.
The average particle size of the pigment in the color paste is about 0.1-0.2 μm, and the performance is better. There is a problem with the maximum amount of color paste in latex paint: the maximum amount 6% to 8%; the maximum amount of color paste for inorganic pigments is 10% to 15%. Adding more than this amount will destroy the stability of the whole system. The production of each color paste should only use one kind of pigment, do not use two or more pigments to produce a color paste, which will help the compatibility and stability of the color paste. Various color pastes need to be compatible with each other, and the coloring power of the color paste should be controlled within 95% to 103%, which is helpful for computer color matching. The color light of the same color paste needs to be consistent between batches. Good performance can ensure stable color matching. The viscosity of the organic pigment paste is preferably 0.3-1.3 Pa s, and the density is preferably controlled at 1.15-1.45 g/cm3 ; the viscosity of the inorganic pigment paste is 2.0-3.5 Pa s, and the density is 2-2.45 g/cm3 is more suitable. Under the premise of ensuring that the pigment in the color paste is in a stable dispersed state, the higher the pigment content in the color paste, the more professional the formula of the color paste. The guarantee period of latex paint color is generally 5 to 10 years without fading. The production of color paste requires bright colors, accuracy, uniformity and long-term consistency between batches, and also meets the requirements of mechanical volume injection of color mixing and the requirements of weather resistance and environmental protection. High-quality general-purpose color paste with strictly controlled color fast computer color matching, and professional integrated color matching system have become the development trend of color paste production.
3 Production of color paste
3.1 Characteristics of color paste color matching
Color paste is used to produce color paint, which not only meets the market's requirements , but also greatly reduces the cumbersome and complicated production of color paint. Toning with color paste is an inevitable trend in the development of modern toning technology, and its characteristics are as follows :
(1) For factories, the use of colorants with excellent dispersion and storage stability can reduce the inventory of 20 to 30 matching colors required by manufacturers and stores to a few , and paint manufacturers only need to produce more than a dozen colors. If it is mixed with several basic paints , the color paint with very accurate color [color accuracy can reach ■ E (total color difference) <0.7] can be produced completely according to the customer's requirements. By using a set of color system in the factory or even in the store, it reduces the complexity of production, simplifies the production process, and saves operating costs; at the same time, it can greatly reduce the amount of color paste and greatly reduce the cost of finished products in the warehouse. Backlog, reducing the occupation of working capital, can greatly improve the production efficiency of the factory.
(2) Due to its extremely fast production cycle, it can supply . Customers can choose their favorite paints with accurate colors as they like, and can provide customers with very satisfactory services.
(3) For the paint industry, the adoption of the delayed color mixing process makes it possible to change the color without causing fundamental changes in the components, which greatly facilitates the color mixing process of industrial reproduction, and makes it easier to adjust the color far away from the factory. become possible. The specialized production of color paste makes the division of labor in the production of paint and paint more reasonable, and enables the transition . The change in the division of labor improves labor productivity and ensures product quality, which will promote the development of the industry.
3.2 Production process of color paste
色浆中研磨树脂相当少 ,当然也可生产无树脂的色浆 ,这样调色时与树脂没有相容性问题 ,同时对涂料性能无负面影响 。对于日益专业化的色浆生产来说 ,色浆的广泛适应性必然要求采取无树脂研磨方式 。
3.3 色浆用助剂
色浆用助剂包括以下几个方面 :
(1)乳化剂 :需要是性能稳定 、不会破坏乳胶体系的非离子型表面活性剂 ,可以复配使用 ,以便颜料粒子能充分乳化且能形成稳定的水溶体系 。
(2)分散剂 :需要能充分分散和润湿颜料固体颗粒表面 ,促进固体粒子在液体中的悬浮 ,以防止颜料絮凝和聚集 。
(3)消泡剂 :消除颜料在高速分散及研磨过程中产生的气泡 。
(4)扩散剂 :帮助色浆在涂料中渗透和扩散 ,防止涂料浮色 、发花。
助剂用量可粗略According to颜料的吸油量或颜料表面积 BET值计算 。一般来说 ,低分子量的传统分散剂为 0.5%～ 2.0%(以无机颜料量计),或 1 .0 %～ 5.0%(以有机颜料量计);而高分子助剂 ,其用量需适当调大 ,特别是在颜料颗粒较小的情况下 。
4 颜色混合规律及配色
4.1 颜色混合规律
颜色体系有两种类型:一种是用色卡作特定的排列 ;另一种是用数字的 。色卡体系中使用广泛很有名的是M unsell 颜色体系 ,用色调 、饱和度和明度三要素来表述颜
Another widely used color system is the CIE (International Commission on Illumination, Commission Internationale de I' Eclairage) system, which is based on the digital research . Here we use the Munsell system to describe colors . The three parameters of color can be used to distinguish the difference of color, that is, only when the three characteristic values of hue, lightness and saturation of the two colors are the same, the two colors are exactly the same. Otherwise, as long as one of the parameters is not equal, the two colors are not the same. What we get from copying Color Charts and matching paints is metamerism, that is, we can only get visual consistency, but not spectral consistency. The color mixing is different from the additive color mixing of visible light, but follows the principle of subtractive color mixing, which means that the white light is irradiated on the mixed colored object, and the part absorbed , and the remaining part of the light is processed. Method of additive color mixing. If it is red and green that are reduced , then the lightness is obtained by mixing the colors, and it becomes yellow. The three primary colors of additive color mixing are red, yellow, and blue. The three primary colors of subtractive color mixing are magenta , yellow, and cyan. These three colors are independent of each other. They cannot be combined to obtain a third color. Moreover, magenta, yellow, and cyan absorb red, green, and blue light respectively. The range of color matching is the widest. Width.
The mixing of colors follows the law of substitution, that is, as long as the colors are similar in feeling , the visual effects of mutual substitution are the same. The mixing of colors also follows the intermediate color law (the mixing of non-complementary colors produces intermediate colors, and its hue and saturation are determined by the proximity of the two in the order of hues, and the color of one of the components is continuously changed, and the mixed colors are also continuously changed. , the hue is biased towards the color with a larger proportion) and complementary color law (a color and its complementary color are mixed in an appropriate proportion to produce white or gray , and mixed in other proportions to produce an unsaturated color with an approximately large proportion of the color component), such as The complementary colors yellow and blue, red and green can be mixed in certain proportions to obtain white or gray.
4.2 Color paste color matching
When using color paste for color matching, it is necessary to stir the color paste evenly before use, and then add it to the paint. Rapid addition of undiluted colorants to any base may lead to flocculation. It needs to be diluted under the condition of uniform stirring, and slowly add water to the color paste. If the addition is too fast, or the color paste is added to the water in reverse, it may cause pigment flocculation. Stirring speed should be appropriate to avoid foaming.
Since the pH value of architectural latex paint is greater than 8, it belongs to the alkaline category, and most of the painted substrates are cement mortar, which is more alkaline, so inorganic (such as iron blue and lead chrome yellow) Can not be used, inorganic color pigments are mainly iron red and iron yellow. Dark colors are often used in exterior paints, red, blue, and green are more common, so the light fastness of the color paste is required to be high. The red color is mainly iron oxide, and the iron red with a and good light fastness is available. If you require a very bright red, you can only use expensive high-grade organic red. For the color of the exterior wall, it is recommended to use inorganic and organic colorants for compounding to ensure the color durability of the coating. The selected organic pigments need to have high light resistance and good weather resistance. However, organic pigments and carbon black are lipophilic pigments that are difficult to disperse, so they have high requirements for dispersants and dispersion processes. Generally, the pigments selected for the color paste provide a wide range of hues, good stability, light resistance and alkali resistance, but the light resistance, alkali resistance and weather largely depend on the paint, coating Surface and construction conditions, if conditions permit , it is recommended to do artificial accelerated aging and aging tests under actual climate conditions to obtain more accurate data.
In the process of toning, if you want to lighten the color, you can directly add color paste to adjust the color, and the performance of the color paste is required to be excellent. Because when the color is diluted, various performances decrease. If the color is diluted between white and natural color, the amount of titanium dioxide should be reduced, and further adjustments should be made, and the grade of color paste can be slightly lower. Under the premise of meeting the performance requirements, reducing the grade of color paste can help reduce costs. Light-colored paints should use color pastes with high weather resistance grades, and dark-colored paints can use color pastes with slightly lower weather resistance grades.
配色时应先调深浅 ,后调色调 。深浅和亮度可以在原色或复色基础上用白色或黑色调整 。在保证颜色符合要求的前提下 ,所用色浆的品种应尽可能的少 ,因为加入的颜色品种越多 ,明度越低 ,色彩越暗 。同时品种越多 ,配色的工作量也越大 。配色时要少加多比 。
用于配色的色浆在施工前需要充分分散均匀 ,否则涂料涂刷到墙面后颜色深浅不一致 。对色浆的细度要求较高 ,象铁红 、碳黑等颜料 ,需要用砂磨机或三辊机研磨 ,使颜料粒子充分分散 ,以避免涂在墙上时出现一丝丝的深颜色 。
4.3 颜色的选择
选择颜色时应注意以下几点 :(1)实际设计所需的颜色要求 ;(2)选配颜色时 ,尽量用复色 ,忌用单色 。因为用几种颜色拼配的色浆 ,色调才生动 、活泼 、饱满 、鲜艳 ,而单色色浆配得的颜色色调呆滞 、死板 ;(3)建筑乳胶涂料除了考虑颜色的情感效应 、心理效应 ,还需考虑房间用途 、个人爱好和情趣 、室外环境 、房间的朝向及家具的颜色等因素。此外各种颜色漆膜的抗粉化能力 ,颜料的耐光 、耐候 、色光和价格等因素也是需要在选择颜色时作参考的 。
4.4 颜色的测量
颜色测量分人工目测和仪器测量两大类 。人工目测是将被测试涂料制成样板 ,在规定的自然光线下与标准样板或色卡进行比较 。仪器测量是建立在 CIE 颜色系统的数字描述的基础上 ,用可见光分光光度计来测量的 。色差的测量一般采用分光测色法。
4.5 调色系统
调色分人工调色和电脑调色 。人工调色对配色页的要求较高 ,因为人工调色目前只能依靠经验进行 ,调色对配色员配色经验的依赖性较大 ,并要求配色员在开始配色前充分了解各种影响因素 ,配色时要耐心细致 。能快而准确地调配出符合要求的颜色 ,要靠长期实践经验的积累和总结提高 ,这使得人工配色受到很大局限 。
电脑配色系统配色速度较快 、重现性较好的优点使其得到广泛的应用 。电脑自动配色采用两种方法 :一种是选用几种常用的颜料作为基本颜料 ,然后用统计和回归分析技术 ,通过大量试验获得各种常用颜色的配色配方并存入计算机 ,使用时直接从计算机中检索出有关配方 ;另一种是计算配色 ,该方法首先需要找出配方与按配方混合后颜料光谱反射律间的关系 ,经过简单的色度计算 ,找出颜料配方与其颜色之间的关系 。计算配色理论反映了颜料色度变化的内在规律 ,借助计算机 ,通过特定的方法可方便地获取有关数据。电脑配色的理论基础是库布尔卡 —芒克(Kubelka -M unk)理论 。崔宝生提出并完善了该理论 ,解决了快速获取有关基础数据的途径 ,并用实验证明了其提出的理论配方的精确度满足了实用要求 。调色系统一般包括测色系统 、调色系统 、色浆及计算机等 。国内也有人用颜色三刺激值研制出电脑配色仪,但当前国内使用较多的调色系统主要有以下几种 :(1)希必思色彩公司的一体化调色系统[ 原芬兰迪古里拉(T IKKU RILA)一体化调色系统] ;(2)瑞典 LARGO 公司的 LA RGO -Match2000 配色系统 ;(3)CHROM OM ATCH 计算机测色配色系统;(4)美国爱色丽配色系统 。
5 发展趋势
With the advent of high-quality, high-performance pigments and the continuous development and research of various will be more perfect in color brightness, light resistance, chemical resistance, and weather resistance; its dispersion stability And the compatibility with various paints will be more satisfactory; computer color matching will be more widely used; low and no VOC (Volatile Organic Content) colorants will have better performance, more cost-effective, and may even find There are some ingredients that improve performance beyond what is achievable with today's traditional VOC technologies.
