Due to the coating and the surface of the workpiece, or between the old and new coating lost adhesion, the coating surface formed small pieces or scales off, if the adhesion between the coating and the surface is completely lost, the paint film whole piece drops, this phenomenon is called "off", also known as peeling off. Coating peeling is also a common major coating defect. Coating peeling is generally caused by the following reasons.

Reason one：

The surface treatment of the coated workpiece is insufficient and too smooth. Before coating, substrate without surface treatment or treatment is not complete, surface residual moisture, oil, oxidation skin, etc. The adhesion of the film usually comes from two aspects. On the one hand, it is the physical attraction and the bonding force between the tiny structure of the domain structure, such as hook, lap, tangle, and winding. On the other hand, it comes from the forces of various chemical bonds. If the substrate is too smooth, the physical binding force of the film on the substrate will become weak, resulting in the film can not adhere to the substrate and fall off.

Prevention and control methods: the smooth surface should be polished with sandpaper, and water, oil, and oxide skin should be completely removed.

Reason two：

The wrong choice of primer causes the paint to peel. If the paint film is too hard so that the surface paint is not easy to adhesion or the primer gloss is too big and other reasons. The bottom and top paint do not match, resulting in poor adhesion between layers.

Prevention and cure method: choose and primer matching intermediate paint or top paint products.

Three reasons：

If the film is too thick or the film is not dry between layers, encounters moisture, etc., the film drying condition is poor. If the coating thickness of the top coat is super thick or the solvent in the primer cannot be fully played out for other reasons, the coating interface between the layers will form a honeycomb because of the presence of the solvent, making the coating lose, the strength decreases, resulting in a decrease in adhesion, and once damaged, it will cause shedding.

Prevention and treatment: The coating should be dry and polished before coating (brush, roller, or spray) finish to increase adhesion between coatings. But also prevent the primer from drying out too much. After EXCESSIVE drying OF THE primer, the lack of active polar groups in the primer leads to the lack of binding force from chemical bonds between the top coat and the primer, which will reduce the interlayer adhesion and lead to shedding.

To prevent disbonding, also note that it is forbidden to be coated material exposure time is too long, exposure time is too long, substrate and primer easy to foreign bodies such as oil pollution, surface occurs pulverization or due to long time exposure to generate a new chemical, paint can't contact with primer or substrate fully, will also affect coating adhesion between, caused fall off.

For performance reasons resulting in peeling coating itself is rare, mostly because the substrate processing is not clean, or primer for more than the required coating intervals without cleaning in accordance with the requirements, therefore before cleaning work to ensure sufficient adhesion between the coating and avoid abuse of critical. In chemical smoke or outdoor environment, use a quick-drying coating to shorten the coating time; Avoid working in humid environments, or use wet curing paint. Operate strictly in accordance with the required temperature and time, and control in accordance with the technical procedures.

Cangzhou shenlong pipe manufacturing co., ltd. Is engaged in oil, gas, water, coal slurry mixing medium steel pipeline coating operations, anti-corrosion, insulation, piping is set in a body's specialized pipeline engineering precast construction enterprises, products used in an oil pipeline, chemical piping, electrical, pipe, gas pipe, heat pipes, sewage pipes, etc. Anti-corrosion processing of straight line and bend pipe DN40-3000 three-layer structure polyolefin (PE, PP, TPEP,3LPE) steel pipe coated with anti-corrosion, DN40-3800 steel hot stewed bend pipe and pipe fittings coated with FBE, epoxy resin coating anti-corrosion, DN40-3800 steel pipe inner wall resistance reduction, solvent-free epoxy steel pipe, epoxy paint anti-corrosion, Coated plastic steel pipe, dip plastic steel pipe. They are lined with plastic steel pipe PE, PO, PP, PTFE, HDPE, and polymer polyethylene corrosion. The company strictly follows China Petroleum and Natural Gas SY/T0413-2002, national GB/T23257-2009, German DIN 30670, American AWWA C210, and other international and domestic anti-corrosion standards.