With the rapid development of China's petroleum and chemical industries, the total demand for the steel barrel market has steadily increased. However, the market share of this form of packaging is being encroached on by new packaging containers, such as plastic barrels. For the steel barrel industry, the plastic barrel industry is still in a stage of gradual growth. However, due to its unique advantages, plastic barrels are showing up.
As a traditional form of packaging, the manufacturing process of steel drums and their application standards have become more mature. It is widely used as a packaging container for petroleum products, food and light industry, and chemical products. The newly developed plastic buckets and steel buckets are basically in the same application area. Only the former is more suitable for the transportation of petroleum products. The latter has advantages in packaging of food and light industry and chemical products with relatively small capacity requirements.
First, the material requirements
The main raw material of the steel drum is the steel plate. Generally, the steel plate is required to have a smooth surface, a low rigidity, a small carbon content, and a uniform thickness. The manufacturing of steel drums requires auxiliary materials including oil sealants, gaskets, buckets, and paints. The curling sealant requires good elasticity, large adhesive force, multiple curing components, good chemical resistance and good processability.
The raw materials for the manufacture of plastic buckets mainly include polyethylene, polyvinyl chloride and modification requirements. For example, due to the long material flow in injection vats, in addition to higher injection pressures, plastic grades with a slightly higher melt index are generally used, while those for blown vats should take into account their density values, which are rigid and resistant to creep. High-molecular-weight HDPE that is resistant to abrasion and environmental stress cracking.
Compared with steel, plastic materials have the advantages of light weight, water resistance and moisture resistance, but their barrier properties, heat resistance and impact resistance are far inferior to steel.
Second, the production process
1, forming
The technical field involved in the manufacturing process of steel drums is very extensive. The following processes are usually required: sheet decoiling leveling, welding edge treatment, barrel welding, barrel body flange, barrel body up type, roll package, barrel bottom cover forming and pre-rolling, surface treatment, inner surface spraying and outside Spray paint on the surface.
Compared to steel drums, the plastic drum barrels have a simpler molding process. It can be made by injection molding or blow molding. Like ordinary plastic products, it only needs plasticization, injection molding, cooling and solidification, and demoulding to complete the injection molding of the barrel. The lid is also made by injection molding. There is a general cover and a closed cover. When designing the cover, full consideration should be given to the elasticity of the plastic. There is also a convenient insert injection molding method that allows the handle ring and barrel to be molded at one time. It does not need to use the injection method to form the L-ring, and the obtained integral vat has a high sealing performance, and the adhesion between the handle and the barrel is high.
Due to the relatively complex forming process of steel drums, the production cost of the steel drums is much higher than that of plastic drums. In addition, steel drums are more likely to have leakage problems. Except for the possibility of leakage at the mouth of the barrel, the bad sealing of the barrel weld and the top of the barrel can cause the same problems. According to statistics, the location and proportion of leakage of steel drums are roughly 85% for beading and welding triangles, 10% for barrels and 5% for barrels. Since the plastic barrel is formed once, there is no seam in the barrel, which greatly reduces the chance of leakage.
2, appearance processing
As the outer packaging of goods, the appearance of the barrel is particularly important. From the perspective of publicity, plastic barrels performed even better.
Prior to printing, the drums were primed. The surface of the drum is usually coated with a white paint or a clear colorless paint to be used as a background color for printing full-text graphics. As for the plastic buckets, except for some colorless and transparent plastic buckets, most of them have been added to the plastic masterbatch when molding, and they are colored once they are molded. If you want to advertise specific products, just print directly on the surface of the barrel.
Because the barrel has a certain volume, it is directly printed on the surface of the barrel, and only screen printing can be used. Due to different materials. The printing inks used for the two barrels are also different. Steel drums mainly use two-component reactive inks, and plastic drums use more volatile dry inks. The printing performance of steel drums is relatively poor. The surface coating, or the uncleaned grease and dust will affect the adhesion of the ink to the steel drums. There may be irregular edges and burrs and incomplete phenomena on characters and patterns. The plastic material has a smooth texture and is easy to remove dust on the surface. It is very convenient for printing. The appearance of the plastic barrel is clean, the edge of the print is clean, the mesh is clear and uniform, and it has the functions of sales and display.
Third, the application market
There are two types of drums: full-open barrels and closed-end models. 200L steel barrels are their mainstream products, and they also have convenient buckets as small as 4L. The capacity of plastic buckets varies from 5L to 200L, even as large as 10,000 liters. Plastic buckets and steel buckets have common application fields and have their own advantages.
1, petroleum products
At present, although the number of oil pipelines and oil tanks is gradually increasing, steel drums are still the main packaging form of petroleum products, and most of them are closed steel drums of 200L.
When the drums are filled with oil, they cannot be filled. They can only reach 80-90% of their capacity. During the injection and pouring process, the gas space in the barrel will be reduced or increased accordingly. The dedicated breathing valve is designed to keep the pressure inside and outside the barrel balanced so as to prevent the steel barrel from bursting and leaking. In the harsh transport environment, steel drums perform better than plastic buckets. For example, its high temperature resistance performance is not as easily deformed or even melted at high temperatures as in plastic barrels. It is estimated that the demand for 200L steel drums exceeds 10 million.
200L plastic barrels were introduced in China in 1988, and businesses have just begun to question whether they can be used as packaging for petroleum products. Later, as plastic barrels also have certain advantages in this regard, for example, can withstand greater mechanical pressure, low cleaning costs and reusable. Its market demand is increasing. The current annual demand for 200L plastic buckets may be more than 1 million. In addition, in recent years, a composite medium-sized bulk container (IBC) has become popular. It is commonly referred to as a ton-packed plastic container barrel with specifications of 820L, 1000L, and 1250L, and generally has a steel frame and a tray. Large capacity is its most important feature. This is currently not available for steel drums.
In addition, plastic buckets are also subject to some restrictions in application, such as can not be used to hold gasoline, trichloroethylene, benzene, toluene and thinner. They are flammable and explosive dangerous goods. Impact with a non-conducting plastic barrel can easily cause electrostatic accumulation, which can lead to an explosion.
2, light industry, chemical products, food
The development of China's light industry and chemical industry has provided a vast market for steel drums, of which the medium and small steel drums are the main demand objects, with an estimated market capacity of more than 10 million. Small steel drums generally use tinplate as a raw material for holding paints, coatings, and lubricating oil, while medium steel drums are used for paint, calcium carbide, and yellow phosphorus. Especially the 4L rectangular barrels and convenient keg are very popular.
The market share of plastic barrels in this area is expanding. Its largest potential market is the paint industry.
The demand for steel barrels in the food industry is also further expanding. It is estimated that the annual demand in this part of the market is more than 500,000 per year.
The steel drums used for food packaging are mostly open buckets, with a capacity of 200L or slightly larger. The current larger consumption targets are products such as tomato sauce, apple sauce and honey.
All kinds of seasonings, baking fats, fruit juice concentrates, beans, etc. will be used as plastic packaging barrels.
However, it is best not to use plastic barrels for long-term consumption of cooking oil. It should not be too long for wine or aromatic items.