11 Nov, 2020 By Johny 2 Comments

Mill Base, as the name implies, it is a pigment concentrate, which is developed through rigorous processing techniques through the use of different pigments, through the surface treatment and surface wrapping of the pigments. According to the different solvents used in color pastes, color pastes are divided into water-based color pastes, oily color pastes, water-oil universal color pastes, etc.; according to different uses of color pastes, they are divided into paint color pastes, tape color pastes, paper color pastes, Textile color pastes, mechanical color pastes, toy color pastes, latex product color pastes, etc.; according to different tools used for color pastes, people simply divide color pastes into factory color pastes and machine color pastes. Color pastes in nature dress up the whole world in coordination, ranging from dressing, daily use, toys, etc., to bridges, buildings, etc., all showing colorful colors.

Traditional paint coloring is to use pigment powder directly into the paint, or some paint manufacturers simply make the pigment into a slurry and then add it to the paint to color the paint. There are certain disadvantages in doing so: such as poor color reproducibility, uneven coloring, because there is no professional technology and technology, the pigment particles are relatively thick, the coloring power is not high, and the pollution is serious. When added to the paint, after the paint is filmed It has poor light resistance and weather resistance, easy to fade, and chalk.

With the fierce market competition, the division of labor has become more and more refined, and the voice of high-end coatings has become higher and higher. In the 1990s, domestic color paste manufacturers emerged, and at the beginning, there were one or two manufacturers specializing in color pastes. ; In fact, in foreign countries, there were special color paste manufacturers in the 1960s.

Nevertheless, the quality of color paste products has improved a lot from the beginning, and the varieties have also been improved. There are also one or two color paste manufacturers at the beginning. There are now 20 or 30 companies, mainly distributed in Jiangsu, Zhejiang, Shanghai, Guangdong and other places.

So far, domestic paint manufacturers have basically popularized the use of colorants. In general small paint factories, the amount of color paste used in a year should be conservatively estimated to be around 2000-5000 yuan (calculated based on the amount), medium-sized paint factory is 50,000-100,000 yuan, and large-scale paint factory color paste uses 500,000-100 yuan. Around ten thousand yuan. The amount of color paste used by different paint factories varies greatly. There are about 12,000 large and small paint factories in my country, mainly distributed in the Yangtze River Delta. Based on the average use of color paste of 20,000 yuan per year for each paint shop, the amount of color paste is about 240 million yuan. In 2006, the total amount of paint in my country exceeded the 5 million tons mark, reaching 5.0784 million tons. Based on 30% of the amount of paint, the amount of paint color paste per ton was about 157.53 yuan, which is a very conservative figure. At present, there are less than 30 domestic color paste factories, and there are more than 30 imported brand color pastes. Due to the limitations of equipment, technology and capital, there are not many real large-scale color paste manufacturers in China, and the demand for color pastes in the domestic market is far greater than the output of these manufacturers (in addition to color pastes for architectural coatings, there are also colors for rubber products. For civil and industrial color pastes, such as color pastes for PVC products, the demand for color pastes is much greater than that of paints). The quality of the products varies, and the quality needs to be further improved.

Application and development of water-based colorants:

With the rapid development of architecture and industry, areas that are rarely designed in the color paste fields including hotels, commerce, landscape, and transportation have entered the development range of the color paste market by a large margin, and are moving towards the development trend of integration and energy saving. Of course, this is mainly manifested in the rapid rise of color paste manufacturers, which has driven the entire color paste industry towards efficient and low-carbon development. As an important branch of the coating industry, water-based color pastes have rapidly grown into the mainstream of consumption driven by industry, real estate, furniture, home appliances, and building materials. Water-based color pastes play an increasingly important role in modern home decoration and home decoration life. Roles.

Water-based colorants are used for coloring, and their application fields are very broad, including coatings, leather, printing, papermaking, latex, textiles and other industries. The main service object is the coating industry.

1.The color strength of the color paste (coloring power):

For comparison of water-based color pastes, color strength is an important indicator, which reflects the color concentration, color development performance and flocculation of pigment dispersions. The data is measured by the number of parts of pigment paste required to reach 1/25 of the International Standard Depth (ISD). The smaller the value, the higher the tinting power. The value represents the number of grams of color paste that needs to be added to the white base paint: in the latex paint-the white base paint has a titanium dioxide content of 25% (1/25ST)

2. Compatibility of color paste (color development performance—refers to research method):

The compatibility of the color paste with the use system is the key to affect the floating color, flocculation and some surface defects of the paint film. Before using the color paste to match colors, a compatibility experiment must be done. Additives can often be used to solve the compatibility problem of the color paste and the coating.

Add the color paste to the white paint, usually in a medium or light color, and smear it on the surface of the coated object or imitate the surface of the coated object. When it is about to condense, use your fingers to grind the surface of the coating film and observe whether there is obvious color difference after drying. (Visual inspection). If the fineness of the color paste is not enough, poor dispersion performance will lead to poor color development of the color paste, which will affect the reproducibility of the color paint.

3. Dispersion performance of color paste (flocculation degree):

The degree of deflocculation of the pigment particles by the additives determines the size and stability of the color paste dispersion. Generally speaking, it is impossible to achieve complete deflocculation (that is, the pigments exist uniformly and stably as primary particles in the system), but they are uniformly distributed in the system in the form of agglomerates of pigment particles. A good color paste has a high degree of deflocculation, that is, the agglomerates are as small as possible, so that they have good tinting strength, excellent color development and storage stability. Due to the poor dispersion performance of the color paste, the difference in migration between the pigment floccules in the color paste and the white pigment and filler particles in the base material is easier to reflect. This difference often makes the pigment flocs no longer uniformly distributed, which is used as the cause of film formation. There are small differences in temperature, density and surface tension inside the paint film. The pigment floccules and the paint base naturally participate in this movement, and the pigment floccules separate with it, resulting in floating and blooming. If the dispersion performance of the color paste is good, the occurrence of floating and blooming can be avoided. In addition, the dispersion of the paint itself directly affects the floating and blooming of the paint.

4.One of the structural properties of color paste (light resistance, weather resistance):

The light and weather resistance test of color paste is through outdoor exposure, but the actual outdoor exposure time is too long. Generally, color paste performance testing is mostly through equipment simulation test.

Light resistance: Use outdoor acrylic latex paint to make 1/3ISD and 1/25ISD standard color samples for exposure. Use xenon light source (1000W) to expose for 72 hours, and use 1-8 grade blue wool ruler and standard color sample to expose at the same time. Grade 1 is the worst and grade 8 is the best. (It has been assessed by color measurement software )

Weather resistance: Use outdoor acrylic latex paint to make 1/3ISD and 1/25ISD standard color samples for exposure. Use ATLAS artificial weathering instrument to expose for 500 hours, and use ISD gray card for color difference rating, level 1 is the worst, and level 5 is the best. (Evaluated by color measurement software)

5.Pigment content of color paste:

The pigment content is for reference only and cannot be used as an index to evaluate the performance of the color paste. The tinting strength of the color paste is not directly proportional to the pigment content. With the same pigment content, the tinting strength varies greatly depending on the fineness. In order to ensure the stability of the tinting strength of the color paste, the pigment content of the color paste is a variable value within a certain range. The value provided on the color paste data is a typical reference value.

6. Fineness of color paste:

Fineness is an intuitive indicator that reflects the tinting strength dispersion effect and storage stability of the colorant. Generally, for the same pigment paste, the smaller the particle size, the larger the specific surface area, so the hiding power is increased, and the tinting power is also higher; the smaller the fineness, the higher the gloss, and the dispersion effect and storage stability. The better. Of course, the fineness of the color paste is not as fine as possible, because when the particle becomes smaller and its specific surface area increases, the absorbed light energy increases, and the degree of damage also increases, resulting in a decrease in its weather resistance; and the particle size is too large. When the paint is filmed and dried, with the precipitation of water, the color paste migrates to the surface together, which is easy to cause inaccurate color matching and color difference of the wall.

7. Compatibility of color paste and coating:

Take 100 grams of white paint with finger grinding method, add 2-3 grams of color paste to be tested, and after fully mixing, apply on the surface of the coating. When it is about to condense, use your fingers to grind the surface of the coating until the paint is dry After that, observe whether there is a color difference between the areas rubbed with fingers and those that have not been rubbed. If the difference is large, the compatibility of the color paste with the tested paint is not good, and the paint prepared from this color paste is easy to cause floating Color phenomenon. If the color is the same, the floating phenomenon will not generally occur.

8.The second structural performance of color paste (chemical medium resistance):

The chemical resistance of water-based color paste is mainly acid resistance and alkali resistance, that is, resistance to chemical migration. This performance basically depends on the pigment itself, which must be considered in outdoor color pastes. Generally, water-based coatings also require acid and alkali resistance, and do not require resistance to organic solvents and other chemicals.

Acid and alkali resistance: According to DIN16524 standard, dry the color paste (105℃) in 1% sulfuric acid and 2.5% sodium hydroxide solution for 24 hours, then take it out and wash to determine its acid and alkali resistance . According to the bleeding and color change, it is evaluated according to the level 5 standard. A level 5 indicates excellent acid and alkali resistance, and a level 1 indicates extremely poor acid and alkali resistance.

9. Other physical and chemical parameters of color paste:

Density: The unit is gram/cubic centimeter, and the measurement method is carried out in accordance with the provisions of GB/T1756.

Viscosity: an important indicator reflecting the storage stability of color paste. (STM- Ⅲ Stormer Viscometer)

PH value: PHB-2 portable PH meter measures the pH value (PH value) of water-based high-quality color paste system generally between 7-10, so the color retention and tinting strength of the color paste in a coating system with a PH value of 7-10 Excellent performance such as color development.

Fineness and gloss: an intuitive indicator reflecting the dispersion effect and storage stability of the color paste. Generally for the same pigment paste, the smaller the fineness, the higher the gloss, the better the dispersion effect and storage stability.

10. Quality stability of color paste:

Generally, through strict control of production formula-raw materials-production process-finished products, the consistency of solid content, fineness, viscosity, tinting strength, color development, light and weather resistance of the color paste is ensured. (Use color measurement and matching software to evaluate, Lab value and color difference control DE ﹤ 1.0) 　The storage stability of general water-based color paste is stored for one year at room temperature of 25 ℃ without obvious defects such as delamination, agglomeration, coarsening, precipitation, and the tinting strength, color development and other physical and chemical properties are not significantly reduced. It is usually possible to accelerate the aging determination through heat storage and freezing experiments, and to evaluate the effect of can opening and color measurement and matching software.

When choosing a color paste, the above factors should be considered. Other conditions can be basically achieved by the color paste of each brand and there is little difference. Of course, the choice of color paste should also be considered from the perspectives of economy and environmental protection. For example, color pastes with poor weather resistance should be selected for color pastes for interior walls. At the same time, try not to choose color pastes containing heavy metals such as chrome yellow for interior walls, but azo type , Amines, etc.

According to the coloring object and environmental requirements, color pastes are mainly divided into two types: light fastness and light fastness. Generally, when the system does not have compatibility for internal use, it is based on the principle of achieving the lowest cost of color requirements and does not require light fastness. For external use, the following factors must be considered:

a.Light and weather resistance; b. Chemical resistance (mainly acid and alkali resistance); c. Compatibility with the use system; d. Color strength, hiding power and color development; e. Color paste and color paste Matchability between f. Storage stability of color paste;

Generally, exterior coatings have strict requirements on the color retention of colors. Therefore, when choosing color pastes, special attention should be paid to the light and weather resistance and acid and alkali resistance of the color paste. On the premise of good compatibility, tinting power, hiding power, color development and storage stability, the mutual matching of color pastes is also very important. It is necessary to choose as much as possible a single color paste with excellent light and weather resistance, but in fact they are often composite colors, so it is best to follow the performance of inorganic and inorganic, organic and organic or light and weather resistance (1/25ST dilute , The light resistance should be 7~8 or 8, and the weather resistance should be 4~5 or 5) as the principle, so that the outdoor color retention can be ensured, and the obvious difference in the weather resistance of the colored paste can be avoided, which may lead to a long time. Causes coating film defects such as fading or uneven color.