There are many types of resins but the industry production confines itself only to two kinds: the epoxy and the polyester one. Both of them are used in the production of moulds and composites, but there are some significant differences between them that are worth being aware of.
The epoxy resin is a chemically hardened molecule having at least two epoxy groups. It is a kind of adhesive created on the basis of synthetic resins used in the production of water-insoluble plastics with a high temperature resistance. Depending on the molecular weight it might have a form of a solid or rather thin, viscous mass. The epoxy resins are the most frequently used in the manufacturing of moulds, various kinds of glues and as an adhesive in laminates. Moreover, thanks to their electroisolating abilities, the epoxy resins are used in the electrical engineering.
The polyester resins also belong to the group of synthetic resins, however they have different composition and applicability. The major component of the polyester resins are polyesters. The resins are used in the hand lay-up of various elements and they stand for ingredients of glues or spatulas. The polyester resins are cheaper than the epoxy ones but one has to pay for annealing of the product so one may achieve all the required features of a laminate.
Gelcoats are worth mentioning because they remain in a constant relation with resins and the production of moulds. For a better understanding of the definition we will first explain what the gelcoat is, and what kinds of it we can encounter.
The general definition is quite complicated and not fully understandable for everyone, that is why we will simplify it a little. Gelcoat, in other words, is the gel resin created on the basis of polyesters or epoxes which give ready products the required resistance, durability and moreover: the colour and the gloss. Depending on a kind of surface one wants to gain, different kinds of gelcoats are used. On the one hand, in the production of moulds one uses hard, and chemical/attrition resistant gelcoats. On the other hand, in the production of gelcoat top coatings in composite elements the most important features are: UV resistance, polishability and weather conditions resistance.
Other kinds of gelcoats are the silicone ones which are good for the production of irregular-shaped elements such as: figurines, sculptures, and wherever we have negative angles and the dividing line should not be visible.
- injection moulds,
- moulds for products made of integral foam,
- open moulds,
- composite moulds and laminate products.