Name | Fluorescent pigments |
Synonyms | Fluorescent pigments |
organic pigments | fluorescent pigments are a class of organic pigments that fluoresce after light excitation, the light source used for the excitation may be ultraviolet light or sunlight. This pigment emits light and cannot persist in the dark. Fluorescent insoluble or solvent-insoluble pigments mainly composed of oxides, sulfides, silicates and tungstates of calcium, barium, magnesium and cadmium, A mixture of a small amount of flux and a small amount of activator is added and calcined. The color of the fluorescence depends on the nature of the activator and the composition of the luminescent pigment. For example, cadmium sulfide is added to the fluorescent pigment of zinc sulfide, and silver is used as an activator to shift from blue to red. The green to red portion was transferred with copper as the activator. Commonly used in the manufacture of fluorescent coatings and plastics. The fluorescent pigment excited by sunlight is commonly known as fluorescent powder. It is a pigment made by water-soluble fluorescent dye dissolved in resin. Such dyes are mainly basic dyes, such as basic yellow O (C.I. Basic Yellow 2), basic rose essence (C.I. Basic Violet 10), etc., and individual acid dyes may also be used for this purpose. The specific preparation method is: the dye is dissolved in the mixture of melamine-p-toluenesulfonamide-formaldehyde, and the dye is contained in the resin after polymerization into the resin, the dried resin is ground to a fine powder to obtain a fluorescent pigment of the solar type. It is characterized by abnormal brilliant color light, but poor light and heat fastness. Fluorescent pigments excited by ultraviolet light are mostly water-insoluble organic compounds, such as dispersed fluorescent yellow FFL (C. I. Disperse Yellow 124), disperse fluorescent yellow D (C. I. Disperse Yellow 11), disperse fluorescent yellow S (C. I. Solvent Yellow 98), dispersed fluorescent red S (C. I. Disperse red 303), etc. The color of this type of fluorescent pigment itself is not very bright, and only when dissolved in a low concentration in the substrate shows a bright fluorescence. According to the principle of fluorescence emission, the visible fluorescent pigment is yellow, orange and red. The blue and green fluorescent pigments on the market are actually compounded by adding fluorescent whitening agents to the blue and green pigments. Fluorescent pigments are mainly used in plastics, inks, coatings, cultural and educational supplies to improve the decorative effect, recently also used in the production of solar energy gathering materials. |
fluorescence phenomenon | fluorescence phenomenon is a process of photoluminescence. In this process, short-wavelength electromagnetic waves in the ultraviolet or visible light band are absorbed and then released in the form of long-wavelength electromagnetic waves. The latter usually falls in the visible range, superimposed with the conventionally reflected light, thus exhibiting a bright fluorescent color. |
molecular structure | (1) usually fluorescent pigment molecules contain fluorescent groups, such as carbonyl, nitrogen double bond, carbon-nitrogen double bond, etc. (2) a chromophore group is contained in the molecule. Chromophore groups red shift the spectrum and increase fluorescence efficiency, such as primary amine groups, secondary amine groups, hydroxyl groups, ether bonds, amide groups, etc. (3) conjugated π bonds containing a rigid planar structure in the molecule. The larger the plane of the intramolecular conjugated system, the stronger its fluorescence intensity is. Some factors that can improve the degree of conjugation can improve the efficiency of fluorescence and shift the fluorescence wavelength to the long wave direction. |
classification | According to the chemical composition and properties of fluorescent pigments, it can be divided into two categories: Inorganic fluorescent pigments and organic fluorescent pigments. The classification and characteristics of the fluorescent pigments are shown in Table 1. The chemical composition and color phase of the inorganic fluorescent pigment are shown in Table 2. |
Anti-fluorescent pigment fading additives | to prevent fluorescent pigment fading additives mainly include wetting and dispersing agents, light stabilizers, antioxidants, etc. (1) wetting and dispersing agents improve the surface properties of fluorescent pigments, improve the compatibility of fluorescent pigments with base materials, and improve the processability of fluorescent pigments. (2) the light stabilizer provides long-lasting stability and prevents fading of the fluorescent pigment. (3) the antioxidant is generally a reducing substance, and can prevent the absorption of oxygen by the fluorescent pigment. |
organic pigments
Fluorescent pigments are a type of organic pigments that can emit fluorescence after light excitation. The light source used for excitation can be ultraviolet light or sunlight. This pigment glows and cannot last in the dark. Fluorescent insoluble or insoluble solvent-soluble pigments with oxides, sulfides, silicates, and tungstate of calcium, barium, magnesium, cadmium, etc. as the main components, plus a small amount of flux and trace amounts of activators The mixture is calcined. The color of the fluorescence depends on the nature of the activator and the composition of the luminescent pigment. For example, cadmium sulfide is added to zinc sulfide fluorescent pigment, and silver is used as activator to transfer from blue to red. Transfer from green to red with copper as activator. Commonly used in the manufacture of fluorescent coatings and plastics. Fluorescent pigments excited by sunlight are commonly known as phosphors. They are pigments made by dissolving water-soluble fluorescent dyes in resins. These dyes are mainly basic dyes, such as alkaline yellow O (C. I. basic yellow 2), alkaline rose essence (C. I. basic violet 10), etc., and individual acid dyes can also be used for this purpose. The specific preparation method is: the dye is dissolved in the mixture of melamine-p-toluenesulfonamide-formaldehyde, the dye is contained in the resin after polymerization, and the dry resin is ground into a fine powder to obtain sunlight-type fluorescent pigment. It is characterized by unusually bright color and light, but poor sun resistance and heat fastness. Most of the fluorescent pigments excited by ultraviolet light are water-insoluble organic compounds, such as dispersed fluorescent yellow FFL (C. I. dispersed yellow 124), dispersed fluorescent yellow d (C. I. dispersed yellow 11), dispersed fluorescent yellow s (C. I. solvent yellow 98), dispersed fluorescent red s (C. I. dispersed red 303), etc. The color of this kind of fluorescent pigment itself is not very bright, and only when it is dissolved in the base at a low concentration can it show dazzling fluorescence. According to the principle of fluorescence emission, the chromatography of fluorescent pigments visible to the naked eye is yellow, orange and red. The blue and green fluorescent pigments sold on the market are actually compounded after adding fluorescent whitening agents to the blue and green pigments. Fluorescent pigments are mainly used in plastics, inks, coatings, cultural and educational supplies to improve the decorative effect. Recently, they are also used to make solar energy gathering materials.
fluorescence phenomenon
Fluorescence phenomenon is a photoluminescence process. In this process, short-wavelength electromagnetic waves in the ultraviolet or visible band are absorbed and released in the form of long-wavelength electromagnetic waves. The latter usually falls within the visible light range and is superimposed with the conventionally reflected light, thus showing a dazzling fluorescent color.
Molecular structure
(1) usually fluorescent pigment molecules contain fluorescent groups, such as carbonyl, nitrogen-nitrogen double bond, carbon-nitrogen double bond, etc.
(2) The molecule contains helpful color groups. The help group makes the spectrum red shift and increases the fluorescence efficiency, such as primary amine group, secondary amine group, hydroxyl group, ether bond, amide group, etc.
(3) Conjugate & pi; bonds with rigid planar structures in the molecule. The larger the intramolecular conjugate system, the stronger the fluorescence intensity. Some factors that can improve the conjugation degree can improve the fluorescence efficiency and make the fluorescence wavelength move to the long wave direction.
auxiliary agent for preventing fading of fluorescent pigment
additives to prevent fading of fluorescent pigments mainly include wetting dispersants, light stabilizers, antioxidants, etc.
(1) Wetting dispersant improves the surface characteristics of fluorescent pigments, improves the compatibility between fluorescent pigments and base materials, and improves the processing performance of fluorescent pigments.
(2) Light stabilizers provide long-lasting stability and prevent fading of fluorescent pigments.
(3) Antioxidants are generally reducing substances, which can prevent the absorption of oxygen by fluorescent pigments.