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Introduction of organic pigments in coatings

Organic pigments have the characteristics of bright shades, high color strength, and complete color spectrum. They are widely used in many industrial fields. Main uses: industrial architectural coatings, general paints and high-end automotive paints, printing inks, plastic resins, rubber products, printing paint colors Pulp, cultural and educational supplies, cosmetic oil color and food industry, etc.

1. The main types and composition of coatings

The paint is applied on the surface of the object to form a paint film, which gives protection, beautification and other effects. The functions of coatings can be summarized as decoration and beautification, signs (advertising, warning, safety, attention, etc.) and special functions: such as moisture, heat, mold, shielding, corrosion inhibition, electrochemical protection, etc.

The main types of coatings can be divided into low-grade categories (such as natural resins, phenolic resins, asphalt and oils) and high-grade categories (alkyd resins, amino resins, acrylic resins, polyester resins, epoxy resins and silicone resins, etc.).

Composition of paint:

Film-forming substance: oil-dry oil, semi-dry oil;

Resin: natural resin and artificial synthetic resin;

Coloring substances: pigments-coloring pigments (inorganic pigments and organic pigments), antirust and body pigments;

Auxiliary materials: solvents or thinners (solvents such as aromatic hydrocarbons, toluene, xylene, co-solvents), driers, emulsifiers, wetting agents, stabilizers, etc.

① Oil: one of the film-forming substances. Derived from plant seeds and animal fats, mainly fatty acid triglycerides. Vegetable oils can be divided into three types, namely, dry oils: can be quickly dried to form a strong film, such as tung oil, linseed oil, etc .; semi-dry oils: dry slowly, forming a sticky film after ten days, such as sunflower seeds Oil, soybean oil, etc .; Non-drying oil: Does not form a film, such as peanut oil, sesame oil, etc. Grease paints, usually based on vegetable oils, have good toughness, air tightness, strong adhesion and good weather fastness.

②Resin: Improve the film-forming properties of the above-mentioned paints prepared with oil alone. A variety of synthetic resins are widely used to combine resin and oil; Resins can be divided into three categories.

Natural resin: such as rosin, animal glue (shellac, dry cool element), asphalt;

Artificial resin: modified rosin derivatives, pentaerythritol rosin resin, cellulose acetate, rubber and chlorinated rubber, etc .;

Synthetic resin: Based on different types of polymers, it can be divided into condensation type and polymer type resins.

③Solvent: It is an important component to make the paint have a specific viscosity and fluidity, mainly including: mineral oil, the main component is hydrocarbons (alkanes, naphthenes, aromatic hydrocarbons) is a petroleum fractionation solvent, typical varieties such as gasoline (bp30 ~ 200 ℃), light gasoline, petroleum ether, medium gasoline, heavy gasoline and kerosene. Organic solvents, aromatic hydrocarbons (such as benzene, toluene, xylene); alcohols (such as ethanol, butanol); ketones (such as acetone, butanone) and esters (such as ethyl acetate, butyl acetate), etc.

④Coloring agent: mainly includes coloring pigments, anti-rust pigments and extender pigments. It has important coloring, anti-rust, covering, blocking light and other properties. It can improve weather resistance, water resistance and wear resistance.

In recent years, various new coatings have been developed, which can be divided according to their forms: water-based coatings, powder coatings, radiation-curing coatings, high-solids coatings, etc.

2. Characteristics, types and varieties of paint colorants

With the continuous advancement and development of coatings industry technology, according to different types of coatings, such as general oil-based coatings, water-based coatings, latex paints, scoop exterior wall coatings and automotive paints, the application performance of its colorants is improved. Claim. Paint colorants include inorganic pigments and organic pigments, which should have the following main characteristics:

①Durability, light resistance and weather fastness, especially for colored objects used in outdoor applications;

②High hiding power or specific transparency, high tinting strength and glossiness;

③It has good matching and easy dispersing performance in different types of color development materials;

④Solvent-based paint colorants should have solvent resistance, anti-crystallization and anti-flocculation properties, and the color and tint strength should not change.

⑤Water-based paint coloring agent has good water resistance and does not swell;

⑥ Chemical resistance, acid and alkali resistance;

⑦Good storage stability, without delamination or precipitation;

⑧Excellent heat resistance and stability.

Because inorganic pigments have better durability, weather fastness and heat stability than organic pigments, and low cost, they are still an important class of colorants in the coatings industry, and can usually be used directly or after surface treatment for solvent-based , Water-based paint coloring.

Mica pearlescent pigments that have been developed and applied in recent years include silver-white series pearlescent pigments prepared by depositing titanium dioxide with different thicknesses on the surface of mica crystals, gold series and new varieties of rainbow and color pearlescent pigments, which have excellent durability, heat resistance and weather resistance Degree, and non-toxic. Widely used in automotive coatings, powder coatings, pearlescent printing ink, etc.

In view of organic pigments having higher coloring strength, bright colors, and complete color spectrum, in recent years, they have continuously developed new heterocyclic yellow, orange, red, and purple spectrum pigment varieties, and have applications similar to phthalocyanine blue and green pigments. Performance, widely used in the coloring of metal surface coatings and architectural coatings.

The pigments used for coloring early and low-end paints are mostly insoluble azo pigments. The production process is simple, the cost is low, and they have good application properties. For example, Hansa yellow (CI pigment yellow 1, CI pigment yellow 3 and CL Pigment Yellow 5 etc.), Orange Spectrum (CI Pigment Orange 5, CI Pigment Orange 13 etc.), Red Spectrum: Toluidine Red (CL Pigment Red 3), Toluidine Violet Red (CI Pigment Red 13) and Scarlet Powder, Blue, The green spectrum is phthalocyanine blue (CI Pigment Blue 15:], CI Pigment Blue 15: 3) and phthalocyanine green (CI Pigment Green 7). It is worth noting that in recent years, inorganic pigments have been developed as cores to prepare composite lake pigments, such as composite red powder, whose composition can be shown as follows:

PbCrO4 • PbMoO • PbSO4 / azo red lake pigment

The performance of this product is better than that of classic red powder in some applications, and the cost is low. It has been widely used in the coloring of mid-range coatings.

Coatings mainly include three major categories: architectural coatings (such as interior walls, exterior walls, wood furniture coatings) industrial coatings (such as automotive, aviation, marine, high-speed railway, bridge coatings, etc.); special coatings (such as road marking coatings, nuclear power station coatings , Wind energy coatings, etc.), especially high-end coatings such as automotive paints and architectural coatings, require organic pigments as colorants to have more excellent application properties, such as durability, weather fastness, surface heat resistance, anti-crystallization, anti-flocculation and Resistance to migration. Therefore, it is required to choose azo-type, azo-condensation-type, heterocyclic and fused-ring ketone pigments with more complicated structures:

Yellow spectrum: CI Pigment Yellow 13, CI Pigment Yellow 83, CI Pigment Yellow 93, C. I, Pigment Yellow 94, CI Pigment Yellow 95, C. L Pigment Yellow 109, CI Pigment Yellow 147 etc .; Red Spectrum: CI Pigment Red 112, CI Pigment Red 177, CI Pigment Red 190, CI Pigment Red 210, CI Pigment Red 254, CI Pigment Red 255, etc .; Purple spectrum: CI Pigment Violet 19, CI Pigment Violet 23, etc.

Organic pigments recommended for coloring high-end coatings (such as automotive paints), mainly yellow pigments of heterocycles or metal complexes, such as CI Pigment Yellow 139, Pigment Yellow 150; red spectrum varieties are perylene and quinac Based on pyridone, CI Pigment Red 122, CI Pigment Red 123, CI Pigment Red 179, CI Pigment Red 190, CI Pigment Red 202, CI Pigment Red 224; purple varieties are quinacridone, dioxazine violet and perylene Based on pigments, CI Pigment Violet 19 (r-type and 0-type), CI Pigment Violet 23. C. I-Pigment Violet 29; blue, green spectrum is still copper phthalocyanine derivatives, such as CL Pigment Blue 15: 1, C. 1. Pigment Blue 15: 2, CI Pigment Blue 15: 3, CI Pigment Blue 15: 4, and C. L Pigment Green 7, C. I, Pigment Green 36.

The types of pigments recommended for high-end automotive paint coloring also belong to heterocyclics, azo condensation, fused ring ketones and phthalocyanines.

Yellow spectrum Cromophtal Yellow 8GN (P. Y. 128), Irgazin Yellow 3R (P. Y. 179), Irgazin Yellow 3RLIN (Pigment yellow 110)

Orange Spectrum Cinquasia Fast Gold YT-915 -D (P. 0. 49)

Red spectrum Cinquasia Magenta RT-243 -D (P. R. 202), Cinquasia Maroon RT-792 -D (P. R. 206), Cinquasia Scarlet RT 787-D (P. R. 207), Oomophtal Red A3B (P. R. 177)

Purple Spectrum Cinquasia Red BRT -742-D (Pigment violet19)

Blue spectrum Irgalite Blue GLSM (P. B. 15: 3), Cromophtal Blue A3R (Pigment blue 60)

Green spectrum Irgalite Green GLN (P. G. 7), Irgalite Green 6G (P. G. 36)

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