Discussion on Safety Technology of Coatings and Coating Operation (1)

1 Introduction

Most of the raw materials used in the paint production and painting operations contain volatile organic solvents, resins, and pigments that are easy to catch fire and are harmful to human health. Therefore, there is always a fire in the paint production and painting operations, and it may even cause explosion.

Fire: 1, gas fire; 2, oil ignition; 3, flammable fire; 4, electrical fire; 5, metal fire; 6, excess oxygen fire;

Explosion: 1. Explosion of mixed gas; 2. Explosion of gas decomposition; 3. Explosion of dust; 4. Explosion caused by mixed hazardous material; 5. Explosion of explosive compound; 6. Explosion of vapor;

Hazardous substances: 1, combustible gases; 2, flammable liquids; 3, flammable substances; 4, combustible dust; 5, the nature of explosives; 6, pyrophoric substances; 7, bogey water substances; 8, mixed dangerous substances;

Fire source: 1, impact friction; 2, open flame; 3, high temperature surface; 4, optional heating; 5, adiabatic compression; 6, electrical spark; 7, static spark; 8, light, radiation;

When a dangerous substance meets a fire source, it can cause a fire or explosion.

Because of this, the use of solvents, pigments, and resins in the world is also stricter than a year. The United States has evolved from "66 regulations" to "1113 regulations." The US Environmental Protection Agency (EPA) has also repeatedly A list of chemicals that warns people. The EPA is very concerned about some special industries. They are working hard to study the composition of waste generated during the manufacturing process of some organic pigments, to study the toxicity of these chemicals, and to include some pigment intermediates in the harmful 2800 species. In the list of chemicals, the Chinese government has also issued a series of regulations on the safety of coatings and paintings.

Therefore, it is a very significant event to study and understand the safety technology in the process of paint production and painting construction and to make safe production. It should be highly valued by all parties concerned.

2 coating is the main film forming material

The general coating composition is as follows:

General coating composition: 1, the main film forming substance A, natural resin; B, synthetic resin; C, vegetable oil; D, other;

2. Secondary film-forming substance A, pigment; B, extender pigment;

3. Additive A, solvent, cosolvent, and diluent for coating film; B. Additives (toughener, driers, solids, leveling agents, etc.)

The resin and vegetable oil in the main film-forming substance are generally harmless or less harmful, but some of the free monomers are toxic, and the isocyanates are more serious. These compounds are mainly found in polyurethane coatings. Mucosa and upper respiratory tract have stimulatory effects.

There are many toxic materials in the raw materials of synthetic resins. For example, phenolic resins are formed by the condensation of phenol, cresol, xylenol, and formaldehyde with heating and condensation. Phenolics can be used as a disinfectant, but inhalation of phenol vapors from the respiratory tract can cause poisoning. High concentrations of phenols can cause acute poisoning, and can even cause coma and death. When the concentration of phenol in the water is high, it will cause the death of fish. When the concentration of phenol-containing wastewater is more than 100 mg/l, it will cause crops to die or reduce production. Formaldehyde has a destructive protein and bactericidal effect, can cause inflammation of the respiratory tract, contact dermatitis and damage to the eyes and cornea, its irritating odor, but also cause people's resentment, in recent years, the restrictions on formaldehyde in interior decoration, but also gradually strict . Second, amino resin (also use formaldehyde) alkyd resin, polyester resin (to use phthalic anhydride, etc., phthalic anhydride can cause bronchitis, ophthalmia, emphysema and other symptoms also have skin irritation), Epoxy resins use phenols and epichlorohydrin, and they also use aliphatic amines for curing. Polyurethanes, vinyl chloride resins, acrylic resins, etc., can cause harm to the human body. In particular, when the application of paints in construction and industry has increased substantially, people’s living standards have improved, the heat of home decoration has risen repeatedly, and the adverse effects on the human body due to decoration have increased. As a result, the toxicity and application of paints have also been proposed. More stringent requirements. In many foreign countries, the requirements for paints have also shifted from general technical standards to technical standards and biological toxicity, that is, to people's good health standards. This standard has greatly limited the application of many toxic compounds. China has issued a series of mandatory standards to strictly limit the exhaust gas of interior decoration.

3 minor film forming substances

Pigments can be classified into natural pigments and synthetic pigments according to their production methods.

Among the pigments that are harmful to humans are Pb (lead) Cr (chromium) substances such as red rust-proof pigments (Lead Dan) and chrome yellow are some toxic substances. In fact, there are many substances that are toxic in pigments. The list of harmful 2,800 chemicals listed by the US Environmental Protection Agency (EPA) contains a number of intermediates of inorganic or natural pigments and synthetic pigments. For paints used in spaces and objects that are in constant contact with people, there are clear limits for lead, chromium, mercury, and cadmium. Red, yellow, yellow, yellow, yellow, orange The restrictions on the use of yellow, complex green (a mixture of lead chrome yellow and iron blue), cadmium red, cadmium yellow, cinnabar, etc., otherwise it will bring people man-made disasters and unpredictable serious consequences.

(to be continued)