Introduction of color paste products and production process
As we all know, the concept of color paste was introduced to China by Chromaflo Company of the United States, and it was firstly applied in the field of water-based coatings. The color paste we are talking about now should be color paste in the strict sense.
The following is the equipment used in the black paste workshop of the factory – twin-screw. The products produced by the twin-screw are not only evenly dispersed, but also have good gloss.
Because of the same direction of rotation of the twin screw in the engagement of the speed of the opposite, a screw to pull the material into the engagement gap, and another screw to push out the material from the gap, the result is that the material from one screw to another screw, was “∞” shape forward. Due to the engagement area gap is very small, the engagement of threads and grooves in the opposite direction of the speed, so it has a very high shear speed, has a good self-cleaning effect, that is, it can scrape off the adherence in the screw on any accumulation of material, thus making the material residence time is very short, so the engagement of the same type of twin-screw extruder is mainly used for mixing and pelletizing.
This is the hydraulic three-roll grinder used in the color paste workshop, which can ensure high fineness, good gloss and strong coloring power.
Hydraulic three-roller grinder is mainly used to grind the color paste by double vane pump. The hydraulic pressure not only controls the double vane pump, but also regulates the in and out of the coloring paste. In the process of grinding color paste, and the fineness of the color paste, also need hydraulic pressure to regulate. In short, the hydraulic three-roller mill is mainly through the hydraulic means to realize the automation of grinding color paste.
In addition, the company has its own R & D team, equipped with experimental sand mill, experimental mixer and experimental three-roller mill, in order to do experimental research.
Color Paste Introduction
First of all, our black color pastes are divided into color pastes for traditional equipment, special color pastes for static machines and special color pastes for automatic lines according to the equipment used. In addition, we also have two-component special color pastes as well as special color pastes for industrial adhesives.
The following are our color pastes. At present, the sunlight resistance grade of the big red has reached the highest grade, and the newly introduced environmentally friendly yellow is free of heavy metal ions, so it can be used with peace of mind. In addition, the red color also contains the commonly used iron red, the yellow color has orange chrome yellow, iron yellow and medium chrome yellow, the white color has porcelain white and titanium white for you to choose from, and then there are also phthalocyanine green and phthalocyanine blue, all of which are ground by the grinder to ensure that the products are free of particles.
We have passed the SGS environmental protection monitoring to ensure the green environmental protection of the products. Meanwhile, in order to ensure the stability of the products, each batch of products have been sampled and tested, mainly on the product appearance, fineness, color, volatile matter, consistency and other 5 tests. The volatile matter, we are committed to within 0.8%, the fineness is below 25μm, and the color difference of each batch of products is less than 0.7.
For the color paste, a key concern is its coloring power, the following is a comparison chart, with the same amount of color paste plus the same amount of base material and peer color paste comparison, you can see here the left side of the color is obviously deeper than the right side of the color, which the left side of the products are made of Karol color paste, the amount of color paste to add a small amount of color paste to achieve the same effect of coloring.
The selling point of color change film is rich in color, but at the same time, it needs stable performance, and nano-color paste is an important coloring agent. Nano color paste refers to a new type of colorant with high transparency and high vividness by grinding ordinary pigment particles to nano level through advanced technology and precise equipment and rationalized control. This article counts some nano color paste enterprises, ranked in no particular order, for industry reference.
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Comprehensive overview of color paste
Water-based color paste refers to organic or inorganic pigments in the surfactant wetting, dispersion effect (can also be added to water-soluble resins), the formation of uniform, stable, with a certain degree of mobility or thixotropic mobility, strong coloring strength of the concentrated pigment paste. There are two kinds of water-based color paste system: one is high pigment content without resin system; the other is low pigment content with resin (general-purpose resin, other single resin) system. The former has high pigment concentration, strong coloring power, good color spreading performance, good compatibility, thixotropic fluidity, generally does not cause floating color and blossom, and reasonable choice of additives, and has generality. The latter pigment concentration is relatively low, but with good coloring power, good color development, mobility and viscosity is more stable, the system contains resin, compatibility needs to do the test, otherwise it is easy to lead to the paint floating color bloom. The technical indexes of color paste are mainly composed of the following aspects:
International pigment number of color powder
Simply understood as the pigment code formulated uniformly according to the different molecular structure of the color powder, the pigment number determines the light resistance (weathering performance) and chemical resistance (acid and alkaline resistance) of the color paste, and also determines the general color phase of the color paste, due to the different production processes of the color paste companies, there may be slight differences in the color phase of the color paste.
Color strength of color paste (coloring power)
The coloring strength refers to the titanium dioxide containing 100 grams of white latex paint, adjusted to 1/25 standard color depth, the number of grams of a certain color paste used, the lower the amount of color paste, the stronger the coloring strength. For the comparison of water-based color paste, coloring strength is an important indicator, which reflects the color concentration of color paste, color spreading performance and pigment dispersion flocculation. The stronger the coloring strength of the color paste, the lower the dosage of color paste in color mixing, the smaller the impact on the performance of the coating film, and the lower the cost of color mixing at the same time.
Color difference ΔE
The stability and color reproducibility of the color paste is mainly reflected in the two aspects of coloring power and color difference. The color difference of color paste includes the color difference between different production batches of the same color paste and the color difference between different packages of the same batch. The size of the color difference is expressed by ΔE, including color hue, lightness and darkness, saturation. Its calculation formula is as follows:
ΔE = (Δa2 + Δb2 + ΔL2)
1/2 The color difference of the color paste affects the accuracy of color mixing and the stability of the color mixing formula.
Light resistance and weather resistance of color paste
Color paste light resistance and weatherability test is through outdoor exposure (such as the United States of America, Florida, Turpan and other places in China have exposure field), but the actual outdoor exposure time is too long, and now most of the general performance testing of color paste through the simulation of instrumentation and other tests. Light resistance test: exposure to xenon light, measured by the blue woolen ruler, to 1-8 levels, 8 levels of the best, 1 level is the worst. Weathering test: ATLAS aging instrument, timed exposure to xenon light and water spraying, exposure to 500 hours, color difference according to ISO gray ruler 1-5 levels to indicate that level 5 is the best, level 1 is the worst. The color paste for exterior wall needs more than 7 levels of light resistance and more than 4 levels of weather resistance to achieve both conditions.
Pigment content of color paste
The pigment content is only for reference, and cannot be used as the index for evaluating the performance of color paste. The coloring power of color paste is not simply proportional to the pigment content. For the same pigment content, there is a big difference in coloring power with different fineness. In order to ensure the stability of the coloring power of the color paste, the pigment content of the color paste is within a certain range of changes in the value of the color paste information provided by the value is a typical reference value.
Fineness of color paste
Fineness is an intuitive index reflecting the coloring power dispersion effect and storage stability of the color paste. Generally for the same pigment color paste, the smaller the particle size, the larger the specific surface area, and thus the covering ability is also increased, the higher the coloring power; the finer the fineness, the higher the luster, the better the dispersion effect and storage stability. Of course, the fineness of the color paste is not the finer the better, because when the particles become smaller, its specific surface area increases, the absorbed light energy increases, the degree of destruction also increases, resulting in a decrease in weather resistance; and particle size is too small in the paint film drying, along with the precipitation of water, the color paste together with the migration of the surface, easy to cause the color is not allowed to match the color and the wall color difference.
Compatibility between color paste and paint (finger study method)
Take 100 grams of white paint, add 2-3 grams of color paste to be tested, fully stirred, coated on the surface of the coated object, to be about to condense, with a finger to grind the surface layer of the film part of the paint film to be dry, and observe the finger to study the rubbed and un-studied place whether there is a color difference, such as the difference is large, then the color paste is not good with the compatibility of the tested paint, the color paste of this paint mixing out of the paint is prone to produce floating color phenomenon. If the color is the same, generally will not produce floating phenomenon. Selection of color paste should focus on the above factors, other conditions of each brand of color paste can basically achieve and not much difference.
Process:
1, put (1) into the pull cylinder, turn on the mixing, in low-speed mixing, add 2, 3, 4, 5, in turn, stirring to add (7), adjust PH = 7 ~ 9, dispersed uniformly on the blue sand mill, to the fineness of ≤ 30μm can be;
2、After the fineness is qualified, notify the analysis to measure the solid content, after meeting the index, filter, discharge and package.
3. Water-based color paste production and testing of the main equipment
Production equipment
1, high-speed disperser, 1, FL22, Jiangyin Fine Chemical Machinery Co.
2, laboratory basket sand mill, 1, Millennium Micromill EEX, Spain Oliver + batlle company
3、Basket sand mill, 1 set, HCP-5, Oliver+batlle, Spain.
4、Pulling cylinder (with jacket), 1 each of 100L and 200L
Testing equipment
1, scraper fineness meter, 100um, 50um each 1 set, Tianjin Jingke material testing machine factory
2、Electronic balance, XP2002S, METTLER TOLEDO
3、Electric blast drying oven, GHG-9076A, Shanghai Junzhu Instrument Manufacturing Co.
4、Artificial aging instrument (xenon lamp test chamber), Xe-3HS, USA
4.Other notes on the production of water-based color paste
Requirements for technicians
Due to the differences between different batches of pigments and other raw materials, it is necessary to make timely adjustments to the production formula to ensure the stability of color paste production. Therefore, in the production of color pastes, technicians are required to have a wealth of relevant professional knowledge.
Color paste stability
Different varieties or different batches of color paste production, due to the quality of raw materials and production process there are certain differences, so it may cause the color paste in the storage process of thickening, water separation, back to the coarse and other phenomena, the color paste needs to be regrinded and dispersed qualified before use.
High price of raw materials to avoid waste
In order to ensure the quality of color paste, some pigments, dispersants and other imported products, raw material prices are very high, so in the production of waste should be eliminated, otherwise it will result in the growth of the cost of color paste.
Grinding equipment
Because it is difficult to disperse and stabilize the pigment in the production of color paste, so we choose the basket sand mill with high grinding efficiency.
In addition, the imported equipment is much better than the domestic manufacturers in terms of grinding efficiency, stability and service life, so the imported equipment is used. The main foreign companies producing this equipment are: 1. Singapore Rishi 2. Spain O+B 3. Germany NETZSCH. Spain O + B company’s products after the Changzhou Coating Research and Design Institute bidding selection proved that its efficiency and wear resistance, are significantly other imported and domestic equipment, so we also choose Spain O + B company’s products.
