Vapour-phase antirust packaging technology

The survey shows that China’s annual loss due to corrosion is as high as 280 billion yuan. How to effectively prevent metal corrosion has become a very critical factor in the transportation of various metal related products. Vapor-phase rust-proof packaging, as an emerging technology, has received more and more attention due to its simplicity, practicality, safety and effectiveness.

Improper preservation is the root cause of mold corrosion. VCI can effectively solve the problem of metal rust.

Metals are prone to rusting due to oxidation in wet environments, and various contaminants in the atmosphere can also corrode metallic materials. Once the mechanical equipment, parts and components made of metal materials rust, it will affect the normal operation of machinery and equipment. Therefore, research on rust prevention of metal materials has always been a topic of concern to the industrial community.

Metal materials often need to be packed twice during storage and transportation, namely inner packaging and outer packaging. In metal packaging, the inner packaging is also called rust-proof packaging, and the outer packaging is also called transportation packaging. They are inseparable components.

The outer packaging (large and medium-sized products) is to create necessary conditions for the lifting, transportation and storage of the package to prevent rainwater from immersing, protect the rust inhibitor and the inner package from being damaged, so as to ensure the overall rust-proof effect of the package.

At present, the most commonly used anti-corrosion method in the industry is to apply anti-rust oil (commonly known as butter) on the surface of metal, but this method may cause failure of the anti-rust oil itself due to oxidation, and it takes time and effort to remove the protective layer. Not hygienic or safe. The desiccant has low rust prevention cost, simple operation, safety and environmental protection, and is easy to remove and protect the packaging, but the effective time is short and is greatly affected by the ambient temperature. As for the use of special dehumidifying equipment for packaging and processing metal materials, although the anti-rust effect is good, it is costly, time-consuming and labor-intensive, and the operation is complicated. VCI, which is both simple and practical and safe and effective, has attracted more and more attention.

Vapor-phase rust-proof packaging materials, as a technology and concept of high-tech rust preservation packaging products, originated from the military application experiments in the latter part of the Second World War. Because of its rapid, simple and low-cost features in the preservation of industrial equipment, especially in line with environmental protection requirements, it has received more attention in recent years, and conducted in-depth research and improvement on issues such as rust prevention ability and safety. Vapour-phase rust-proof packaging materials have achieved commercialization and application.

VCI Antirust Mechanism and Features

The vapor phase rust prevention material exerts a rust preventing effect by a vapor phase corrosion inhibitor impregnated therein. The vapor phase corrosion inhibitor can be continuously and slowly vaporized and volatilized at normal temperature, and the vapor of the vaporized corrosion inhibitor can be adsorbed on the exposed metal surface to form a stable protective film with a thickness of two molecules, and the protective film can Effectively prevent the corrosion of metals such as oxygen and moisture in the atmosphere, resulting in excellent rust prevention. Since the vapor phase inhibitor molecule is continuously volatilized, it can always be in a "saturated" state in the sealed space, and it can achieve a long-term, stable rust prevention effect. Since the corrosion inhibitor molecule is in a gas state, it does not penetrate into pores, and no matter how complicated the shape of the metal product is, an ideal rust prevention effect can still be obtained.

This new antirust mechanism has many unparalleled advantages compared to traditional rust prevention methods. After the metal material is packaged or sprayed, the vapor phase corrosion inhibitor molecules begin to diverge. The vapor phase corrosion inhibitor molecules can penetrate into the corner space that conventional antirust oil can not cover, preventing rust and no dead corner; the vapor phase corrosion inhibitor molecular active ingredient has a long retention time. , can achieve the rust protection period of more than 10 years; even if there is moisture on the metal surface or the outside air is very moist, the rust inhibitor can also form a protective film on the metal surface to prevent the metal from being rusted; the rust-proof packaging material made of Its air permeability and moisture permeability are extremely low, and it is waterproof, moisture-proof, oil-resistant and chemical-resistant. Especially in the packaging of metal materials, mechanical equipment and parts, the use of vapor phase anti-rust agent does not need to apply anti-rust oil, and no additional treatment, greatly simplifying the cumbersome steps of anti-corrosion, compared with vacuum packaging, not only achieve a special defense Corrosion function, but also reduce packaging costs, save labor and materials, improve efficiency.

In addition, the special advantage of this rust prevention method is that different methods can be adopted to achieve flexible operations for different rust-proof target materials and different rust-proof period requirements. For example, for a material with a rust-prevention period of only one week to one month, a rust-preventive liquid spray method may be used to facilitate rust-proof treatment, and even without packaging the material, the rust-prevention purpose can be achieved; For devices with a rust-proof period of 1 year to 2 years, general sealed packages can be used. For devices with a rust-proof period of up to 10 years, special rust inhibitor formulations can be used and aluminum foil laminated film bags can be used for sealed packages. . When using materials that require rust-proof treatment, the traditional method must first remove the rust-preventing oil on the surface of the material before using it. With this method, no matter which of the above methods is used, the package can be immediately removed and used, and it can be easily cleaned. Safe, non-polluting, can also be used repeatedly after rust-proof packaging.

It is because of the advantages of vapor phase rust-proof packaging materials that they have been increasingly used.

Selection of vapor phase rust-proof packaging materials

At present, vapor phase anti-rust materials and rust prevention processes have been widely used in rust prevention and anti-corrosion treatment of industrial equipment in foreign countries. In particular, with the rise of the information industry in recent years, this technology has shown unique advantages in the packaging of IT and electronic products. Domestic companies have also successively developed a variety of different vapor phase anti-rust products, and now have formed anti-rust liquid, anti-rust powder, anti-rust plastic film, anti-rust aluminum foil composite film, anti-rust paper and other product lines. According to different requirements can be applied to metal products, precision instruments, electronic equipment, petrochemical machinery, pipelines, marine instruments and equipment, transmission equipment, aerospace instruments and military products rust, corrosion and so on. In the prevention of oxidation of high-precision equipment and preservation of marine products and salt corrosion, moisture treatment, more good results.

VCI products can be used in the following areas:

- Military use: light weapons, heavy weapons, tank engines and accessories, bullets, missiles, etc.
- Automobiles, ships, aircrafts: Engines and parts, generators, clutch parts, etc.
- Machinery: Various castings, boiler systems, machinery and spare parts.
- Electronics: computer, television, communications equipment parts.
- Other categories: Hand tools, cutting tools, bearings and other metal parts.

Due to the special rust prevention mechanism of vapor phase rust prevention, different factors need to be taken into account when selecting specific materials, such as:

Metal products and their own corrosion resistance: For the metal to be protected, use suitable VCI packaging materials.

Transport and storage deadlines: Determine the specific packaging form, seal or quasi-seal.

Environmental conditions for transportation and storage (relative humidity, temperature, contaminants, etc.).

The humidity of the general storage environment should not exceed 85%; the ambient temperature should not exceed 65 °C, and long-term direct sunlight should be avoided at the same time, it is best stored in a cool and ventilated place; vapour phase rustproof materials in the transport, storage process, Care should be taken to maintain the integrity of the packaging; avoid contact with acids, alkalis, salts and other contaminants during storage and transportation; in the presence of strong air flow, the packaging should be shielded in addition to the seal; not stored in HCL, H2S, SO2 or other Acid steam in industrial smoke.

The structure and method of packaging and transportation: Avoid destroying rust-proof packaging or generating high temperatures.

Customer's other special requirements.

When using vapour phase rust prevention materials, the following points should also be noted:

There should be no spacer between the VCI packaging material and the metal, and the distance between the VCI material and the metal surface should be less than 300mm;

VCI materials are designed for metal protection and are not recommended for other uses; if not stated or verified, they cannot be used for packaging of products with high explosive substances and high finish requirements; Zinc, cadmium, zinc-based alloys, magnesium-based alloys, and aluminum Alloys and other products containing more than 30% zinc or more than 9% lead alloys should be tested for suitability before they are qualified, and should be adapted before packaging products containing non-metallic materials such as plastics, rubber, oils, and coatings. test;

Before the metal products are rust-proofed and packaged, they should be cleaned and dried to ensure that they are clean; during the packaging process, bare hands are not allowed to touch the metal to prevent hand sweat or moisture from corroding the metal;

When the package is used again, the exposure time of the corrosion inhibitor surface in the air shall be no more than 4 hours; the VCI packaging material shall be used as it is, once in use, it shall be repacked.

Products that have exceeded the storage period should be tested again for rust-prevention performance. After passing the test, they can be used.

The “China Corrosion Survey Report” shows that China’s annual economic loss caused by corrosion is about RMB280 billion. How to apply emerging anti-corrosion technologies and minimize economic losses has become a top priority. The experience of many countries in the world shows that after decades of peak investment in infrastructure, it is the peak of corrosion. If you do not take effective anti-corrosion measures, the consequences can be disastrous.

Although the vapour-phase anti-corrosion technology has entered China for only a few years, it has developed rapidly and is now used in many industries and fields such as steel, automobiles, and machinery manufacturing. However, compared with advanced countries, China's vapour phase rust prevention technology still has the problem of less product variety and less application coverage. The anti-corrosion of the outer surface of large-scale equipment and the anti-rust corrosion on the surface of large-scale open-air chemical plants have yet to be developed.

Experts predict that in the coming period, China’s corrosion losses will continue to increase. Therefore, we should increase the promotion of advanced technologies, promote the popularization of the application industry and the popularization of the region, and at the same time strengthen the research and development of gas phase rust inhibitors, especially large-scale devices. Surface anti-corrosion product development.