Advantages and problems of release agents in the extrusion process of fiberglass profiles

Firstly, liquid internal release agents have many advantages in the pultrusion process:

1. Easy to disperse in resin;

2. Has the function of cleaning molds;

3. Improve production efficiency while reducing extrusion resistance and mold loss;

4. It can reduce the surface tension of resin mixtures, lower resin viscosity, improve the resin's wettability with reinforcing materials and fillers, and enhance the resin's flowability;

5. Assist in defoaming and improve the surface quality of components to make the product surface smooth;

6. Does not affect the curing characteristics of the resin, does not alter the shelf life of the mixed resin, does not affect the physical and mechanical properties of the product, does not affect the weather resistance of the product, etc.

However, most of the liquid release agents currently available on the market use solid pentoxide as a phosphorylation reagent to react with fatty alcohols to prepare alkyl phosphate esters. This esterification reaction is a heterogeneous solid-liquid reaction, and the reaction is incomplete, with a small amount of pentoxide residue, so they are all acidic with a pH value of about 1-3. Therefore, the following problems may occur during use

1. The use of acid sensitive pigments can cause color changes;

2. When using alkaline fillers such as calcium carbonate, acidic release agents will react with them, causing an increase in the viscosity of the mixture, but it will not affect the release effect;

3. If the filler is aluminum hydroxide, the acidic release agent will not only increase the viscosity of the mixture, but also release water during the curing process, causing problems such as bubbles and cracks.