Composite adhesive curing is not complete

The rainy season in the south will come again, and the “incomplete cure” phenomenon of two-component polyurethane adhesives will occur frequently. This article gives an introduction to the causes, problems and countermeasures of the "prone areas" phenomenon in the prone areas.

In the south of the Yangtze River, Meiyu entered the summer, and the climate is characterized by high temperature and high humidity, with an average maximum temperature of 31-34°C and an average relative humidity of 80-83%. We list the cities in the south of the Yangtze River with an average humidity of more than 80% in the summer and in the coastal areas.

In high-temperature and high-humidity areas, these cities can be connected in series to form a clear area: coastal cities from the mouth of the Yangtze River to Beibu Gulf, they are Shanghai, Hangzhou, Taichung, Fuzhou, Shantou, Zhanjiang Haikou, and Nanning. Jiangnan's riverside cities also start from Shanghai, passing Nanchang, Changsha, and Chongqing to Chengdu. The areas connected by these cities include almost all of the land south of Changchun. The warmest and most humid summer in these cities is steamed bread: the average maximum temperature is 37.9°C and the average humidity is 84%.

Japanese description: When the humidity exceeds 80%, the composite operation should be stopped to avoid quality accidents. Although Japan is an island nation, it has a relatively high latitude. The climate is equivalent to our country's Shandong Peninsula and the ten islands of Liaodong. The weather with more than 80% humidity is not much, and it can be shut down for one or two days. The highest humidity in summer in north China, northwest and northeast China is below 70% (see Table 2). It can also be stopped during high-humidity weather. However, there are many days of high humidity in the south of the Yangtze River in the summer, and it is impossible to stop for a long time. We must try to solve it.

Ethyl acetate is divided into several grades in the industrial grade ethyl acetate GB3728-9l, superior grade moisture content is less than 1000ppm (0.1%), first grade moisture content is less than 2000ppm (0.2%), we generally Use excellent products. However, excellent products cannot guarantee perfection. We also need to pay attention to packaging and storage. The chemical plant transports the ethyl ester brakes. The best case is point-to-point and it is sent directly to the storage tank of the unit. However, most color printing plants do not have such conditions. The ethyl esters are shipped in solvent drums, and the residual solvents in the empty solvent drums are not easily removed.
(to be continued)