Manufacture of moisture-proof carton-making method (I)

Corrugated boxes are green packaging, which not only has value in use but also has recycling value for recycling. With the increasing emphasis on environmental protection by the whole society, the consumer groups of corrugated cartons are increasing day by day. Faced with a broad development trend, the corrugated box industry should seize this favorable opportunity to improve the traditional corrugated boxes and develop new products and new varieties, and actively expand service targets.

Thus, the most urgent problem for corrugated cartons lies in front of us: How do corrugated cartons resist wet attack? As we all know, the biggest weakness of conventional corrugated cartons is poor strength. In wet environments, corrugated cartons Easy to absorb moisture and reduce strength. Therefore, how to define the moisture-proof level of corrugated boxes, how to produce qualified moisture-proof products, and how to measure the moisture resistance and water resistance of substrates, etc., have become a series of deep-seated problems, and it has become a corrugated box industry to improve product quality, enhance product competitiveness and promote One of the important topics in the development of the industry.

First, the characteristics of waterproof corrugated cardboard and production methods

In recent years, with the improvement of people's living standards, the requirements for the packaging of goods have become higher and higher. Corrugated cartons as commodity packaging containers must not only ensure the safety of the transportation of goods, but also have the effect of beautifying the goods, increasing the added value, and promoting sales. In particular, various kinds of beautifully printed new moisture-proof coatings appear on the market in recent years. Carton boxes, to a large extent, improve the quality of the packaging cartons, and fundamentally solve the carton packaging susceptible to moisture, easy to mold, vulnerable to problems.

The current market demand for carton boxes with waterproof performance is continuously increasing, especially in the areas of packaging for vegetables, food, household appliances and industrial products. In particular, the rapid increase in the use of water-resistant cartons for export products has greatly promoted the development of the corrugated box manufacturing industry.

(A) Introduction of waterproof cardboard features and waterproof coating

Waterproof paperboard refers to a generic name for paperboard that has resistance to water destroying its strength. It is generally coated with a waterproof coating on corrugated board and dried. After the waterproof coating is brushed on the carton and dried quickly, the film has high transparency and good gloss, and the coating is smooth and non-adhesive, which has no effect on the carton printing ink. After the general corrugated carton has been coated with a waterproof coating, the surface of the carton can have enhanced abrasion resistance, scratch resistance, and high strength, and has strong water resistance and good moisture resistance, and can beautify and protect the carton for a long time. effect.

At present, the domestic waterproof coatings mainly include: oil-soluble, alcohol-soluble and water-soluble waterproof coatings. Compared with these three types of waterproof coatings, the water-soluble waterproof coatings have better gloss and moisture resistance than oil-soluble and alcohol-soluble waterproof coatings. Water-soluble carton waterproof coating is usually based on paraffin wax, oxidized polyethylene as the main film-forming substance and with a dispersant, stabilizer, thickener, brightener, conditioner, water and Other additives to form a water-based emulsion.

Its outstanding advantages are: non-toxic and odorless, good resistance to water permeability, not easy to burn, good stability, good adaptability of temperature difference between hot and cold. It is safe to use, low in price, waterproof and moisture-proof, excellent in performance and easy to use (spray, paint, brush can be used

The following table is a technical indicator of a water-soluble carton waterproof coating.

Oxidized polyethylene waterproof coating main indicators

(II) Types of waterproof cardboard

Waterproof cardboard can be roughly divided into three types based on its water resistance:
Water-repellent corrugated cardboard - prevents water penetration when it is affected by water for a short time;
Water-resistant paperboard - When the water is soaked for a long time, the strength of the paperboard will not drop much;
Strong water-resistant paperboard - long-term contact with water, but also almost impermeable.

(to be continued)