This paper explains in detail the main properties of pigments, such as coloring power, hiding power, light and weather resistance, and differentiation. In addition, in the classification of pigments, coloring pigments, antirust, extender pigments, etc. are also explained in detail. Those who are not clear about the properties of pigments or the classification of pigments can read in detail.
The main properties of pigments
Pigment refers to a substance that has a certain color (or white) and is insoluble in the medium used. It is divided into two parts, one part comes from natural minerals, and the other part is synthetic organic or inorganic pigments.
Pigment is an important part of ink and an important film-forming substance of ink layer. It not only provides the ink with the decorative color that people need, covers the bottom layer to be printed, but also improves the performance of the ink layer, improves the mechanical strength and anti-corrosion performance of the ink layer, reduces the air permeability and water permeability of the ink layer, and some It exhibits special properties and plays a key role in the functionalization of inks.
express. Generally, tinting strength, hiding power, light resistance and weather resistance, pulverization, heat resistance, acid and alkali resistance, etc. are often used to express.
1. Tinting power
The ability of a pigment to form a color intensity when mixed with another pigment is called tinting strength. The stronger the coloring power, the less material is used, and vice versa. For example, ultramarine blue pigments are often used in white inks to remove their yellow marks. The greater the tinting strength of the ultramarine blue pigment, the less it should be used.
2. Hiding power
The quality of the pigment is mainly determined by its several main properties. When the ink is printed on the surface of the substrate, the ability to hide the color penetration of the surface of the substrate is called the covering power of the ink. The hiding power of the pigment is the ability of the pigment in the ink layer to cover the printed surface so that it cannot pass through the ink layer to expose the background color. The hiding power of a pigment is expressed in grams of pigment required to cover an area of 1 m2.
3. Light fastness and weather resistance
Under the action of sunlight and the atmosphere, the color and performance of the pigment will change, and the ability to prevent or slow down this change is called the light resistance and weather resistance of the pigment. The quality of this performance is an important factor that marks the quality of the pigment. Exterior inks in particular are an element to consider. For example, both mica iron oxide and metal aluminum powder have the ability to absorb ultraviolet light, which helps to improve the weather resistance of the ink layer.
4. chalking
During the use of the ink, the binder in the ink layer is destroyed, and the pigment in it cannot continue to stay in the ink layer, but comes out to form a layer of powder. This phenomenon is called pulverization. Chalking is caused by photochemical decomposition of the binder.
5. heat resistance
During the use of the ink, the pigment in the ink layer maintains the ability to maintain the color without being affected by the temperature rise of the use environment. This property is called the heat resistance of the pigment. For products using baking varnish, the heat resistance of the ink is an important quality indicator.
6. Acid and alkali resistance
During the use of the ink, the ability of the pigment in the ink layer to maintain the same color when it is attacked by acid and alkali is called the acid and alkali resistance of the pigment. For example, water-soluble pigments need to be alkali-resistant.
Classification of pigments
There are many kinds of pigments, which can be divided into four categories according to their different functions in inks: coloring pigments, antirust pigments, body pigments and special pigments.
coloring pigment
There are many kinds of coloring pigments with different colors, which play the role of coloring and covering in the ink, and can also improve the durability and wear resistance of the coating film. According to different coloring pigments, the colors can be divided into 9 categories of yellow, red, orange, purple, blue, green, white, black and metallic luster. The brief performance and characteristics of each pigment (main varieties) are briefly introduced as follows:
1) Chrome yellow
2) iron yellow
3) Fast yellow
4) antimony red
5) Toluidine red
6) Iron blue
7) Phthalo bronze
8) Zinc oxide
9) Titanium dioxide
10) Carbon black
11) Chrome oxide green
12) Aluminum powder
13) Copper powder
Antirust Pigment
There are many kinds of antirust pigments, which can be divided into two types: physical performance antirust pigments and chemical performance antirust pigments according to their properties. Antirust pigments are an important part of antirust inks. physics
Anti-rust pigments are a kind of pigments with relatively stable chemical properties. They rely on their own physical and chemical properties, hard texture, fine particles, and excellent filling properties. By increasing the density of the ink layer, it reduces the ink layer. Permeability acts as a rust preventer. Iron oxide red is one such substance. The rust resistance of metal aluminum powder is due to the fact that aluminum powder has a scaly structure, forms a tight ink layer, and has a strong ability to reflect ultraviolet rays, which can improve the anti-aging ability of the ink layer. Chemical antirust pigments, such as red lead, zinc chrome yellow, calcium lead acid, zinc powder, aluminum powder, etc., all belong to this type of antirust pigment.
Extender pigment
Extender pigments are also called filler pigments. Most of them are natural mineral products or industrial by-products. They are cheap. Because the refractive index is similar to oil and synthetic resins, they do not have tinting power and hiding power. They are mixed with other coloring pigments in inks. Its function is to strengthen the constitution of the ink layer, increase the thickness of the ink layer, and make the ink layer hard and wear-resistant. Some body pigments have light density and good suspension force, which can prevent the pigments with high density from settling; Improve the smoothness of the ink layer; some extender pigments can form a compact structure , which can improve the anti-aging ability of the ink layer. Due to the use of extender pigments, some coloring pigments with redundant functions can be saved to ensure the ink quality and reduce the ink cost. Thus, it can be concluded that the effect of using extender pigments is to reduce ink costs and improve ink performance and quality.
Specialty Pigments
Effect Pigments
Effect pigment is the abbreviation of color-dependent effect pigment, which refers to the pigment that can produce color-dependent effect in its application system such as ink layer. Inks that contain effect pigments that can produce a color-dependent effect are called effect inks. The so-called angle-dependent effect refers to an optical phenomenon that the ink layer containing effect pigments and other transparent color pigments can flash different lightness, saturation, hue and even color with different viewing angles. Caused by the different ways in which effect pigments scatter and reflect incident light. When viewed almost perpendicular to the ink layer, the ink layer shows a stronger color, also known as the positive color. When viewed almost parallel to the ink layer, the ink layer shows a flashing color, which is usually the complementary color of the face color; when the viewing angle is at any angle between the above two extreme positions, the ink layer shows a flashing color.
fluorescent pigment
Fluorescent pigments refer to substances that can emit strong fluorescence and have the function of pigments or colorants. Fluorescent pigments can be divided into inorganic fluorescent pigments and organic fluorescent pigments.
Anti-static filler
As polymer materials are widely used in various fields of industrial production and daily life, more and more people pay more and more attention to their electrostatic hazards. Compared with other materials, antistatic ink has the advantages of low cost, simple equipment, and convenient construction, so it is widely used.
This article mainly excerpts Qin Youxue's "Identification of Common Ink and Pigment Types" in materials and equipment. Those who are interested can read this article in detail.
