Moisture-proof technology and water-resistant adhesive for paper honeycomb products

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Paper honeycomb products should have certain moisture-proof functions, but how to define the moisture-proof grade of paper honeycomb products, how to produce qualified moisture-proof products, and how to determine the moisture-proof and water-resistant properties of substrates are a series of deep-seated problems. Improve product quality, enhance product competitiveness and promote the development of the industry.

1. Why should paper honeycomb products be protected from moisture?

The so-called moisture-proof is the ability of the bonding structure to adapt to environmental factors. To be exact, the ability of the product to withstand moisture, moisture and temperature. Paper is the substrate of honeycomb products, and its main components are cellulose and hemicellulose. According to the structure of cellulose, the surface tension of cellulose was calculated by the method of Fedors and the Lee formula to be rc = 72.4 dynes/cm, which is almost equal to the surface tension of water, so that cellulose is easily wetted by water. The surface of the paper is porous, and the moisture easily penetrates into the interior of the paper and reaches the adhesive surface of the adhesive and the fiber, which gradually causes the bonding interface to be broken to form a weak interface layer.

The porosity, wettability, and permeability of the paper substrate exhibit a weak interface in a humid environment, resulting in a decrease in rigidity of the honeycomb structure, a decrease in strength, and such a decrease as the humidity increases. When cellulose absorbs moisture and expands its volume, its expansion ratio is longitudinal: transverse: thickness is 1:2:50, which results in loss of structural strength. There is no strength in the honeycomb paperboard or the rain-dried honeycomb products that are not dried, and of course there is no use value.

Tests have shown that moisture damage is more serious than water to bond strength, especially in coastal areas where salt water and salt spray are more pronounced, because the molecules of water in moisture are smaller and easily penetrate into the paper.

The decline in structural strength is also proportional to the ambient temperature, high temperature, high and bad, so that the product's environmental resistance is greatly enhanced.

Second, paper honeycomb moisture-proof technology

The first is the scientific selection of moisture-proof paper as a substrate. Most of China: a few paper honeycomb products use boxboard paper, corrugated paper, wood pulp liner paper. The national standard GB5034 and GBl3024-91 only provide the provisions for the delivery of water 7-11% and 6-1%, and there is no regulation in the relevant standards for moisture prevention. Some domestic enterprises, such as Beijing Pivot Company and Suzhou Shengbao Company, have set standards for the water absorption rate of paper honeycomb for the company, and have determined the supplier of fixed-point paper.

In the GBl3024-91 boxboard technical standard, there is a requirement for A grade paper: (export boxboard paper) to have a water absorption of no more than 35/50 (g/m2). B, C grade paper water absorption index only specifies the front: 40 / - 60 /, there is no requirement for the reverse side.