For carbonated drink packaging, syrup glass bottle and aluminum ropp cap with TPE liner is the best option. As we all know, the carbonated drink has pressure, so the aluminum ropp cap can be sealed onto the syrup glass bottle tightly, which can stop the pressure out of the bottle. Also, the capper machine is necessary. As to the inner gasket, TPE is the best material.
Why the DIN 28 syrup glass bottle is the best choice? Not the DIN 18 glass dropper bottle?
I am sure you can find the neck difference as below photes. The key point is due to the nethermost stop ring(the red highlighted). The Ropp cap should cover the nethermost stop ring and secured by the stop ring. For the syrup bottle, the ring diameter is almost the same as the upper screw thread. So the ropp cap can be secured very tightly. While for the DIN 18 glass dropper bottle, the nethermost stop ring is wider than the upper thread. So when the ropp cap was secured onto the bottle, there is still some space inside the ropp cap, which can be impossible to secure the bottle very tightly.
Neck drawing for DIN 28 syrup glass bottle:
Neck drawing for DIN 18 glass dropper bottle:
250ml DIN 28 syrup glass bottle
Aluminum Ropp Cap with TPE inner gasket
Semi-automatic capper machine