[Chinese Packaging News] Corrugated board will rapidly decrease its strength under humid conditions. This is a worldwide problem. The developed countries have conducted long-term research and exploration in this area and achieved remarkable results. Currently, they are effective and recognized. There are three ways:
1. Improve the water resistance of corrugated board adhesive (commonly known as paste or glue).
2. Improvement of inorganic fillers in papermaking.
3. The board surface is coated with waterproof or moistureproof agent.
In the latter two schemes, a special waterproof material (such as wax, silicon, etc.) is added or painted on the surface of the paperboard so that the fibers of the paper have a low surface tension when they contact with water or water vapor, forming no water. The wetting layer allows the board to be waterproof, but it has no effect on the moisture in the interior of the corrugated board.
In China, almost all corrugated board production lines use water-soluble corn starch (or tapioca starch) as an adhesive. The diameter of starch granules is generally 4 to 50 μm, and the main component is carbohydrates (glucose compounds), which are insoluble in themselves. Water, which swells in water as the temperature rises, then breaks and gelatinizes, becoming a very viscous translucent liquid, resulting in strong adhesion.
Corn starch adhesive has the advantages of non-toxic, non-corrosive, non-polluting environment, wide source of raw materials, low cost, and simple manufacturing process, but its poor water resistance is a very fatal flaw.
There is an important international standard to evaluate and measure the water resistance of corrugated paperboard, namely ISO 3038:1975 "Determination of water repellency of corrugated paperboard (water immersion method)", which originated from the original West German industrial standard DIN 53133 After more than 30 years, China only converted the ISO 3038:1975 standard to GB/T, and took effect on September 1, 2009.
As soon as the new national standard is released, there are too few third-party institutions that can do this formal inspection in China. According to the requirements of some high-end customers, our R&D center spent a few months on trial production, test experiments, and finally successfully developed the domestic first. Taiwan based on the latest national standard requirements of corrugated board adhesive water resistance tester, this new product is successfully developed, and put into the market, will surely enter the global market for high-end corrugated boxes, to participate in international competition and provide strong technical support .