INTRODUCTION TO RELEVANT KNOWLEDGE OF POLYUREA SPRAYING EQUIPMENT ⑷

At present, the advantages of rigid polyurea with its excellent physical and chemical properties and advanced and convenient construction technology in the anti-corrosion application of the outer wall of the pipeline have been highlighted. Compared with 3PE, the rigid polyurea spraying equipment has occupied the anti-corrosion of the outer wall of the buried steel pipeline. Increasing market share.

Technical use of polyurea spraying equipment in anti-corrosion of pipeline outer wall

The famous German MANNESMANN steel pipe company has launched a three-layer structure polyethylene anticorrosive coating (3PE), which is a new type of anticorrosive steel pipe coating that organically combines the European 2PE anticorrosive coating and the North American epoxy powder coating (FBE) Layers, the first layer is epoxy powder (FBE), the second layer is adhesive (AD), and the third layer is polyethylene (PE). 3PE is widely used because of its excellent physical and chemical properties. But at the same time, the problems of the 3PE coating itself have gradually emerged, mainly manifested in the peeling and peeling of the coating and the steel pipe.

Polyurea spray equipment adhesive and epoxy powder detached, causing warping, stress defects at welds, and inconsistencies between the treatment of elbows, tees and other joints and the main pipeline, which are hidden dangers of coating detachment. Therefore, in view of the shortcomings of the 3PE material itself and the molding process, the new material and new process of rigid polyurea greatly solve the problems of 3PE, thereby greatly reducing the original coating and steel pipe The separation phenomenon extends the service life of the buried steel pipe.

The coating of the elastomer material of the polyurea spraying equipment is continuous, dense, no pinholes, no joints, and a large film thickness at one time, so it exhibits excellent heavy-duty corrosion under harsh environmental conditions such as acid, alkali, salt, underground and ocean performance. With advanced construction technology, the material has broad application prospects in the fields of chemical storage tank lining, tunnel, marine steel structure and concrete structure.

Polyurea spray equipment is often used in construction, mainly because polyurea has a strong anti-corrosion effect. It has a certain adhesion and strength. In order to improve the adhesion of the layer, you need to strictly control the selected base material and improve it if necessary. Then there are several types of anticorrosive coatings for polyurea spraying equipment. The form of attachment.

1. Chemical bond adhesion: The chemical bond produced by the chemical reaction is the most effective way for polyurea spray equipment paint to adhere to the surface of the object. One example is metal hot dip coating, which produces the mixing and mutual melting of steel and metallic zinc on the surface of the steel. The silicate molecules in the inorganic zinc-rich primer also form chemical bonds with the steel surface. These bonds are the actual reaction between the chemical functional groups of the coating and the components of the substrate to form chemical bonds.

2. Mechanical adhesion: Mechanical adhesion is related to the roughness of the surface of the object. In fact, the surface area of a rough surface is larger than that of a smooth surface, and the adhesion area between the coating and the substrate is also increased; coupled with a certain rough shape, the coating and the rough substrate surface form a "tracing solid" combination , The adhesion will increase.

3. Polar adhesion: The adhesion caused by polarity is more common in organic coatings than the adhesion caused by chemical bonds. Polar adhesion is the attraction of resin molecules to the surface of the substrate. In this case, the resin acts like a weak magnet's north and south poles attracting the opposite groups of the substrate. This is the meaning of "polar". In fact, the polar group is the positive or negative charge in the coating molecule that attracts the opposite charge of the substrate.

The air permeability and water permeability of the anticorrosive coating of polyurea spraying equipment are relatively low. You can use less air-permeable base materials as filler materials. If spalling occurs during construction, it is due to the surface of the building, so you need to analyze the specific conditions of the construction in detail.