How to prevent the yellowing and aging of hot melt adhesives.

Hot melt adhesive is a relatively common bonding product on the current market, which can directly bond two separated objects together to form a good effect. In order to ensure the quality of hot melt adhesives, it is necessary to add an appropriate amount of antioxidants during the production process. Antioxidant is a common compound that can prevent or inhibit the oxidation process, so it is also called "anti-aging agent". Its main function is to prevent the aging of hot melt adhesive and prolong its service life. I believe that many people have encountered it occasionally when using hot melt adhesive. When two items are connected together, the bonding effect at the beginning is very good, and they are firmly connected together. Over time, the two products that were originally stuck together began to loosen and even separate. This is because the oxidation of the hot melt adhesive polymer causes the macromolecular chain to break, cross-link, deteriorate the performance, and reduce the internal adhesion effect, which can no longer function. Therefore, adding antioxidants to hot melt adhesives is to delay or inhibit the oxidation process of hot melt adhesives, so that the effect of hot melt adhesives can be greatly exerted and the time of aging phenomenon can be prolonged.

 

An ideal antioxidant should have the following conditions:

1. Has high antioxidant capacity;

2. Good compatibility with resin, no precipitation;

3. Good processing performance, non-volatile and insoluble at the processing temperature of the polymer;

4. Good resistance to extraction, insoluble in water and oil;

5. The color itself is colorless or light, and does not pollute the product;

6. Non-toxic and harmless;

 

In fact, none of the antioxidants can fully meet these conditions. Therefore, in actual use, the advantages of various additives are often used in combination to produce synergistic effects according to the type, application and processing method of the Hot melt adhesive.