Ten solutions of waterproof and moistureproof for corrugated box

Corrugated boxes have been criticized by the market for their poor water and moisture resistance. Especially in recent years, the market scale of cold chain packaging such as fresh ice meat, fruits and vegetables, medicine and so on has become larger and larger. The corrugated packaging industry urgently needs to fundamentally solve the problem that the box packaging is easy to collapse after being damped.

01. Heavy sizing box board

In the paper-making process of box board paper, the surface of the box board paper is heavily sized to ensure that the water drop is not penetrated within 5 minutes. Usually a large number of water-resistant additives are added to starch paste, such as urea formaldehyde resin, melamine formaldehyde resin, polyvinyl butyral, etc. But the cost of the water-resistant agent is high, and it is easy to cause problems such as uncoating in the production process of corrugated board.

02. Coated paper

Coated paper is a kind of composite material that coated plastic particles on the surface of paper by tape casting machine. Its main characteristics are oil proof, water-proof (relative) and heat sealing. However, due to the high cost, it is not conducive to widespread use in the packaging industry.

03. Drain corrugated board

It refers to the process of coating low surface energy substances such as polylactic acid (PLA), polyolefin, polycarbonate, polyamide, polyester, molten paraffin on the surface of paperboard to change the surface roughness and surface morphology of the material. When the hydrophobic corrugated board is subjected to water drenching, a state of water drop on the lotus leaf is formed, and the water becomes water drop to slide down, without seeping into the inside of the board. The cost is very low, suitable for packing dry powder goods, especially the powder which is easy to agglomerate after absorbing water. It is also suitable for packing the goods that often go in and out of the cold storage. It is easy to condense on the box wall after being taken out of the cold storage. After hydrophobic processing, the paper board will not significantly reduce the compressive strength before the dew evaporation, which can effectively protect the goods.

04. Waterproof corrugated board

Also known as waterproof or water retaining corrugated board, its surface is almost impervious to water for a long time, but it cannot be immersed in water, otherwise it will lose its waterproof performance. Water blocking corrugated board is often used curtain coating method. The melted synthetic resin or paraffin mixture is coated on the surface of corrugated board to form a layer of resin film or wax film. If necessary, double-sided coating can also be carried out.

Water blocking corrugated board is mainly used for packaging salted products, frozen food and fruits and vegetables. Because of the soft paraffin layer on the surface of corrugated board, it is also suitable for packaging high finish furniture, piano, safe and precision machinery, which are easy to scratch.www.chinacartonmachine.com

05. Water resistant corrugated board

Water resistant corrugated board is a kind of paper whose strength is not obviously reduced after long-term immersion in water. There are two kinds of equipment and technology for producing water-resistant corrugated board. Its processing principle is similar to that of impregnation. Water resistant corrugated board can be measured by instrument. The so-called water resistance is that the corrugated board is immersed in water (20 ± 2 ℃ tap water) for 30mm, soaked for 1h, and then tested for its breaking resistance and edge pressure strength. The residual strength is required to be no less than 75% of the standard strength (before immersion).

Water resistant corrugated boxes are used to carry live fish, seafood and a class of commodities with high water content. However, the recycling of such cartons is difficult, and the EU has restricted their use.

06. Surface polish corrugated box

Polishing is a common process for post press processing of packaging products. After the product surface is polished and coated, it can enhance the water resistance, sun resistance, friction resistance and pollution resistance of the printed products. At the same time, it can also improve the surface brightness of the products and greatly improve the quality of the products.

The polishing process of the corrugated box is usually that the surface paper is pre printed and polished, and then mounted into the corrugated board, and then die-cut into the carton. It can also polish the surface of corrugated board directly, but the waterproof effect is not good, and it may damage the compression resistance of the carton.

07. Surface coated corrugated box

Laminating is the process of covering plastic film such as polypropylene on the surface of printed matter, and using adhesive to make it stick together after heating and pressure. Lamination technology is divided into pre coating and instant coating. After the color box is covered with film, the surface is bright, resistant to friction, with certain waterproof effect, and the folding box is not easy to crack. However, it is difficult to recycle and use the products, and the United States, Europe and other countries have restricted their use.

08. Aluminum coated kraft board

Toyo Steel Co., Ltd. has developed a 0.02mm ~ 0.05mm thick pure iron foil, which is treated by galvanizing, nickel or tin antirust, and extruded together with kraft paper and polyethylene film to make composite paperboard. It is used for making cartons, not only waterproof and moisture-proof, but also shielding electromagnetic wave and static electricity. It is especially suitable for packaging of aquatic products, fruits and vegetables, electronic instruments, semiconductor devices and electromechanical products 。 After compounding the aluminized PVC film and kraft paper, the cartons are made, which also have the functions of waterproof and moisture-proof.

09. Corrugated paste added with water-resistant agent carton

In the production process of corrugated board, a proper amount of high molecular polymer (also known as crosslinking agent or bridging agent) is added into the starch adhesive, which will replace the hydroxyl group in the starch molecule, making the corrugated paste line have better waterproof and moisture-proof effect. When the carton enters the cold storage or humid environment, it can prevent the collapse of the carton due to the moisture absorption and emulsification of the corrugated paste line.

As for the often publicized products that can improve the bonding effect of cardboard and enhance the stability of bonding, there are some exaggerations.

10. Carton vent is moisture-proof

For the products with heat degree in the packaging of beer, a certain amount of hot steam formed in the box may be absorbed by the box, and then the compressive strength will decrease. In view of these situations, the common practice is to punch two 18 mm diameter air holes respectively on the proper position of the side mark of the carton.

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