Waterproof Technology and Water Resistant Adhesive for Paper Honeycomb Products (3)

Third, paper honeycomb moisture and water resistant adhesive

As we all know, paper honeycomb is a typical adhesive material, and its bonding strength moisture resistance and other water quality features, in addition to the impact of the performance of the paper substrate, the second largest factor is the quality of the adhesive. Although the weight percentage of the adhesive in the adhesive product is small, its role is very great.

In 1998, an ordnance enterprise in Shanghai purchased a batch of paper honeycomb panels from a honeycomb factory in Beijing and plans to process and produce pallets. Due to the humid climate in Shanghai, the company applied water-proof moisture-proofing agent to the surface of the paper honeycomb panel. It was thought that this would have the effect of preventing moisture, resulting in a large area degumming of the facial paper and the core layer, resulting in a large number of products being scrapped and causing serious losses. A few years ago, we regretted seeing many similar examples. These facts tell us how important the adhesive's moisture and water resistance properties are.

The problem of the water resistance mechanism of adhesives is briefly described due to space limitations. The paper honeycomb product includes a bonding structure. Under the comprehensive action of environmental factors, particularly temperature and moisture vapor, part of the physical properties, chemical properties, and mechanical properties of the adhesive will gradually decrease and cause the bond strength to decrease. The most important factor is humidity and temperature. For example, the gel has a normal temperature shear strength of 9.8 MPa when the normal condition HR=65%. When the HR=90% (wood) water content≥17%, the wet strength is only 2.0Mpa, and the water resistance of the glue layer is not more than 4 hours. White latex afraid of water, afraid of freezing. Plant starch glues have poor water resistance. Therefore, we should follow the following principles when designing and manufacturing paper honeycomb products, especially mechanical products with stress and sub-stress products:

1. The hot and humid environment is the most harmful.

2. Forced bonded products have worse moisture resistance than unbonded products.

3. The heat-curing adhesive system has better thermal properties than the room-temperature curing system.

4. No stress adhesive moisture and heat effect.

5. Different adhesives have different water resistance and moisture resistance.

6. All adhesive systems have moisture resistance, durability limits, and the lowest normalization.

7. Chemical structure affects moisture and durability. Larger systems such as epoxy systems, phenolic systems, and recently developed Pm series AP1 systems have higher water-resistant durability.

Pm series water-resistant adhesive is the latest product successfully developed. It is a non-toxic, non-hazardous, non-fire hazard product made of vinyl unsaturated resin as the main raw material modified by TDI acid and fat. The product has good film-forming property, strong water resistance, excellent aging property and III property, and has excellent female and feminine capabilities for porous materials such as fiber, paper and wood. The film is quick-drying, easy to clean after use, and has good: able. Several domestic production lines use Pm-3 waterproof glue for honeycomb paper products with reliable quality, normal temperature and water immersion for 70 hours. Pm-2 water-resistant rubber has good self-property, and the price is only 30% of imported rubber of the same kind. The recently developed ABC (series) emulsion has a water resistance of 48 hours and excellent rheology and aging resistance.

Several production lines in Beijing, Suzhou, Xiamen, and Shandong have been exported to the United States and Japan using adhesives with good water-resistance. Their quality and moisture-proof features have been recognized by people at home and abroad, and the price is only one-third that of similar foreign products.