About to enter the rainy season, what are the moisture-proof measures for corrugated cardboard boxes?

When the rainy season arrives every year, the problem of soft and soft cartons will trouble everyone. When encountering such a problem, everyone's first reaction may be attributed to the weather, because the fiber used in the carton base paper is a naturally absorbent material. The weather in various places will also be in the rainy season from May to August. When it is in the rainy season, the moisture (relative humidity) in the air will basically be higher than 65%. Strength has a big impact.

The following will comprehensively analyze the reasons for the softness of the carton and the corresponding solutions.

First, the improvement method to prevent the cardboard from getting wet

It is recommended to replace high-weight, high-strength corrugated paper, which can reduce or reduce the phenomenon of corrugated cardboard or carton regaining moisture and softening.

Changing the starch glue formula of corrugated cardboard production line can reduce the moisture and softening of cardboard or carton.

When stacking after production, it is recommended to use wooden or moisture-absorbing pads, which can replace cardboard or cartons to absorb some ground moisture, and the size is suitable for cardboard cartons.

When stacking, it is recommended to use "well" shape stacking, and the stacking height should not be too high;

If the moisture is too large, it is recommended to use an exhaust fan to extract the moisture from the cardboard or carton.

During the production process, the production speed should be controlled according to the environment, temperature and material.

The storage environment should be ventilated and ventilated; at the same time, the product can be protected by the outer layer of the wrapping film, which can reduce or isolate the moisture regain caused by the environmental impact. When the relative humidity of the storage environment exceeds 65%, quicklime powder can also be used to spread the ground to absorb moisture.

In the production process, the glue is reduced while the product quality is guaranteed, thereby reducing the moisture in the corrugated board.

Second, Common reasons for the softening of cardboard (carton)

In addition to the above methods, it is also an important means to start from the reason why the source cardboard (carton) becomes soft again and prevent it in advance. Common causes of dampness are:

1. Weather factor

During the rainy season, when the weather is humid and the humidity exceeds 65%, the phenomenon that the cardboard or carton will regain moisture and soften will often occur.

2. Cardboard material

All paper quality of corrugated cardboard, including lining paper, face paper and corrugated paper; especially the material with poor material and strong water absorption, it is more likely to cause the phenomenon of cardboard or carton to regain moisture and soften.

3. Production process

The production process mainly includes preheating, sizing, and dehumidification of the paper during the production process; especially in the aspect of glue, a waterproof reinforced adhesive should be added.

4. Storage conditions (environment)

Whether the storage warehouse of cardboard or carton is properly ventilated, whether the product is wrapped with stretch film, and whether the ground is moisture-proof.

5. Transportation Conditions (Environment)

After the cardboard or carton is processed, when the humidity of the product itself is high, what transport vehicle is used for delivery, whether it is covered with tarpaulin, etc.

6. Processing technology of carton

After the corrugated cardboard is produced, it needs to be processed within the specified time, and the production process needs to be paid attention to during processing.

Third, Several solutions to help corrugated boxes from the root cause waterproof and moisture-proof

1. Heavy sizing container board

In the papermaking process of containerboard paper, heavy sizing on the surface of containerboard paper can ensure that water droplets do not penetrate on the surface within 5 minutes. Usually, a large amount of water-resistant additives, such as urea-formaldehyde resin, melamine-formaldehyde resin, polyvinyl butyral, etc., are added to the starch paste. However, the cost of the water-resistant agent is relatively high, and it is easy to cause problems such as debonding of corrugated cardboard during the production process of corrugated cardboard.

2. Coated paper

Coated paper is a composite material in which plastic particles are coated on the surface of the paper through a casting machine. The main features are that it can be oil-proof, waterproof (relative), and can be heat-sealed. However, due to the high cost, it is not conducive to widespread use in the packaging industry.

3. Hydrophobic corrugated cardboard

Also known as water-repellent corrugated cardboard, it refers to the coating of low surface energy substances such as polylactic acid (PLA), polyolefin, polycarbonate, polyamide, polyester, molten paraffin, etc. on the surface of the cardboard paper to change the roughness of the material surface. degree and surface morphology. When the hydrophobic corrugated cardboard is subjected to water drenching, it forms a state of water droplets on the lotus leaf, and the water turns into water droplets and slides down without infiltrating the inside of the cardboard. The cost of hydrophobic corrugated cardboard is very low. It is suitable for packaging dry powdery goods, especially powders that are easy to agglomerate after absorbing water. It is also suitable for packaging goods that often go in and out of cold storage.

4. Waterproof corrugated cardboard

Also known as waterproof or water-retaining corrugated cardboard, its surface is almost impermeable in contact with water for a long time, but it cannot be immersed in water, otherwise it will lose its waterproof performance. Water-shielding corrugated cardboard is commonly used in curtain coating method, and the molten synthetic resin or paraffin mixture is coated on the surface of corrugated cardboard to form a layer of resin film or wax film. Double-sided coating is also possible if necessary.

5. Water-resistant corrugated cardboard

Corrugated cardboard whose strength is not significantly reduced after being immersed in water for a long time is called water-resistant corrugated cardboard. There are two kinds of equipment and processes to produce water-resistant corrugated board, and its processing principle is similar to that of impregnation processing. Water-resistant corrugated cardboard can be used to measure its water resistance. The so-called water resistance is to immerse the corrugated cardboard in water (20±2°C tap water) for 30mm, soak it for 1 hour, and then test its bursting strength and edge compressive strength. It is required that the residual strength should not be lower than 75% of the standard strength (before immersion).

6. Surface glazing corrugated box

Glazing is a common process for post-press processing of packaging products. After the surface of the product is coated with glazing, it can enhance the properties of the printed matter such as water resistance, light resistance, friction resistance and pollution resistance, and at the same time, it can also improve the surface brightness of the product. The grade of the product has been greatly improved.

7. Surface-coated corrugated boxes

Lamination is a process in which a plastic film such as polypropylene is covered on the surface of the printed product, and the adhesive is heated and pressurized to bond it together. The film coating process is divided into two types: pre-coating film and instant coating film. After the color box is coated, the surface is bright, friction-resistant, and has a certain waterproof effect, and the folding box is not easy to crack. However, it is difficult to recycle the product, and the United States and Europe have restricted its use.

8. Aluminized kraft paperboard

Japan Toyo Steel Co., Ltd. has developed a pure iron foil with a thickness of 0.02mm to 0.05mm, which is galvanized, nickel or tin anti-rust treatment, and extruded together with kraft paper and polyethylene film to form a composite cardboard for making The carton is not only waterproof and moisture-proof, but also shields electromagnetic waves and anti-static. It is especially suitable for the packaging of aquatic products, fruits and vegetables, electronic instruments, semiconductor devices and electromechanical products.

9. Corrugated paste with water resistant agent carton

In the production process of corrugated board, an appropriate amount of high molecular polymer (also known as cross-linking agent or bridging agent) is added to the starch adhesive, and the high molecular polymer will replace the hydroxyl group in the starch molecule, so that the corrugated paste line has better quality. waterproof and moisture-proof effect. When the carton enters a cold storage or humid environment, it can prevent the carton from collapsing due to moisture absorption and emulsification of the corrugated paste line.

10. Carton ventilation holes are moisture-proof

For products such as beer that have heat during packaging, a certain amount of hot steam formed in the box after packing may be absorbed by the carton, thereby reducing the compressive strength. In view of these situations, the usual practice is to make two ventilation holes with a diameter of 18mm on the appropriate position of the side label of the carton.