Detailed introduction:

The poor waterproof and moisture resistance of corrugated boxes has always been a defect that has been criticized by the market。Especially in recent years, the cold chain packaging market such as chilled meat, fruits and vegetables, and medicine is getting larger and larger, and the corrugated packaging industry urgently needs to fundamentally solve the problem that the carton packaging is easy to collapse after moisture。

01, heavy sizing box board paper

In the papermaking process of box board paper, heavy sizing on the surface of box board paper can ensure that water droplets on the surface within 5 minutes of no penetration。Usually, a large number of water-resistant additives are added to the starch paste, such as urea formaldehyde resin, melamine formaldehyde resin, polyvinyl butyral and so on。However, the cost of the water-resistant agent is high, and it is easy to cause problems such as the opening of the corrugated board in the production process。

02, coated paper

Coated paper is a composite material that is coated with plastic particles on the surface of the paper by the casting machine, which is mainly characterized by oil resistance, water resistance (relative) and heat sealing。However, due to the high cost, it is not conducive to widely promoting the use of packaging industry。

03, hydrophobic 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 the board paper to change the roughness and surface shape of the material surface。When the hydrophobic corrugated cardboard is subjected to water, it forms a state of water droplets on the lotus leaf, and the water becomes a water drop, and it will not penetrate the inside of the cardboard。The cost is very low, suitable for packaging dry powder items, especially the powder that is easy to caking after water absorption (Shenzhen Puyun PY-H615 COBB absorption tester)。It is also suitable for packaging goods that often enter and leave the cold storage, and it is easy to condense on the wall of the box after being removed from the cold storage。The paperboard after hydrophobic processing will not significantly reduce the compressive strength before the dew evaporates, which can effectively protect the commodity。

04, waterproof corrugated board

Also known as waterproof or waterproof corrugated cardboard, its surface is almost impervious to water contact for a long time, but it can not be immersed in water, otherwise it will lose its waterproof performance。Corrugated board is commonly used in curtain coating method, the molten 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 performed。

Corrugated cardboard is mostly used to package salted products, frozen foods and fruit and vegetable products, because the surface of corrugated cardboard has a soft paraffin layer, it is also suitable for packaging high-finish furniture, piano, safe and precision machines that are easy to scratch。

05, water-resistant corrugated board

Corrugated board paper whose strength is not significantly reduced after a long time in water is called water-resistant corrugated board。There are two kinds of equipment and processes for the production of water-resistant corrugated cardboard, and its processing principle is similar to dip processing。Water resistant corrugated board can be measured by an instrument to measure its water resistance。The so-called water resistance is to put the corrugated cardboard into the water (20±2℃ tap water)30mm，Soak for 1h，Then test its break resistance (PY-H601 break strength tester) and edge pressure strength (PY-H603 compression strength tester)，The residual strength should not be less than 75% of the standard strength (before immersion)，Shenzhen Puyun PY-E628 halogen moisture tester is recommended。

Water-resistant corrugated boxes are used to carry live fish, seafood and goods with very high water content。However, such cartons are difficult to recycle and the EU has restricted their use。

06, the surface of the corrugated box

Glazing is a common process for post-press processing of packaging products，After finishing the surface of the product，It can enhance the performance of water resistance, sun resistance (Shenzhen Puyun PY-E506 Xenon lamp weathering test chamber), friction resistance (Shenzhen Puyun PY-H618 ink printing wear test instrument) and pollution resistance，It can also improve the surface brightness of the product，The grade of the product is greatly improved。

The glazing process of the corrugated box is usually the face paper pre-printed and polished, then the composite corrugated cardboard is mounted, and the carton is processed by die-cutting。It can also be directly glazed on the surface of corrugated cardboard, but the waterproof effect is not good, and it may also damage the carton compressive strength tester (Shenzhen Puyun PY-H620 microcomputer compressive strength tester)。

07, the surface covered corrugated box

Laminating is a process in which plastic films such as polypropylene are covered on the surface of the printed product, and adhesive is heated and pressurized to bond them together。The film coating process is divided into pre-coated film and immediate coated film two kinds。The surface of the color box after the film is bright, friction-resistant, has a certain waterproof effect, and the folding box is not easy to crack。However, the recycling of products is difficult, and the use of the United States and Europe has been restricted。

08, aluminized kraft paper plate

Japan Toyo Steel Co., Ltd. has developed 0.02mm~0.05mm thick pure iron foil，Anti-rust treatment with zinc, nickel or tin，Extruded with kraft paper and polyethylene film to form composite paperboard，For making cartons，Not only waterproof, moisture-proof，It can also shield electromagnetic waves and anti-static electricity，Especially suitable for aquatic products, fruits and vegetables, electronic instruments, semiconductor devices and mechanical and electrical products packaging。The paper box is made of aluminized PVC film and kraft paper, which also has the function of waterproof and moisture-proof。

09, corrugated paste add water resistant agent carton

In the production process of corrugated cardboard, adding an appropriate amount of high polymer (also known as crosslinking agent or bridging agent) to the starch adhesive, the high polymer will replace the hydroxyl in the starch molecule, so that the corrugated paste line has a better waterproof and moisture-proof effect。When the carton is in cold storage or humid environment, it can prevent the collapse of the carton due to moisture absorption emulsification of the corrugated paste line。

As for the often advertised such products can improve the adhesion effect of cardboard, improve the stability of adhesion, etc., it is exaggerated。

10, the carton air holes moisture-proof

For products with hot packaging such as beer, a certain amount of hot steam formed in the box after packing may be absorbed by the carton, and then the compressive strength (Shenzhen Puyun PY-H620 carton compressive strength testing machine) will decline。In view of these situations, the usual practice is to play 2 air holes with a diameter of 18mm on the side mark of the carton in the appropriate position。