CLOSURES are devices by means of which containers can be opened and closed.
TYPES OF CLOSURES WITH EXAMPLES:
1. Plug type – It is a push-fit into the neck of the container. E.g. cork or glass stopper.
Nowadays plastic stoppers being flexible and unbreakable are used to ensure a good fit into the container.
2. Crown cap – The cap is commonly used as crimped closure for beverage bottles.
E.g.Cap of glass beverage bottle.
3. Push-fit cap – These are simple slide fit over the neck of the container. These are made of plastic and are shaped in such a way that these must be stretched over the neck to fit on the container. It provides tight fit.
4. Screw closures – It consists of three components – i) Cap: It is made of tin plate of aluminium. The container is simply closed by screwing the cap on the container. Ii)
Wad: it is a seal which prevents contamination of the product. Made of rubber or silicone rubber, however cork or cardboard wads are also used. Iii) Liner: It is made of metal foils, rubber, plastic films, and paper impregnated with a suitable resin, wax or plastic.
E.g. Caps of pharmaceutical liquid dosage forms.