How Much Pressure Does the High Barrier Pesticide Bottle Need When Blowing? Process Parameter Analysis

What is a high barrier pesticide bottle?

High barrier pesticide bottles are usually made of multi-layer co-extrusion (such as PE/EVOH/PE) or pet material coated with silicon oxide, which aims to block moisture, oxygen and volatile components of pesticides and ensure the stability and storage safety of pesticides.

Key role of blowing pressure

in the process of blow molding, “blowing” means injecting compressed air into the premolded blank (parison) to shape its inner wall laminated mold. The pressure of this link directly affects the uniformity of bottle wall thickness, the integrity of barrier layer and the sealing performance of bottle mouth.

Typical blowing pressure range

• general scope:0.8–1.6 MPa (About 8- 16 bar), depending on the bottle type, capacity and material structure;
• high barrier multi-layer bottle:due to the strong rigidity of barrier layers such as EVOH and low melt strength, more precise control is often needed-recommended initial pressure 1. 0–1.3 MPa, supplemented by segmented supercharging (such as low-voltage charging first, then medium-pressure setting);
• note:too high pressure will easily lead to barrier layer offset, interlayer stripping or bottle bottom thinning; If it is too low, the molding is insufficient, which will affect barrier performance and dimensional accuracy.

Supporting process suggestions

in addition to the main blowing pressure, the pre-blowing pressure needs to be optimized cooperatively (0.2–0.4 MPa), blowing time (1.5-4.0 seconds), Mold temperature (10–25℃) and cooling rate to ensure that the high barrier structure does not undergo phase separation or stress cracking during molding.

Schematic of high barrier structure (EVOH layer centered)
→ blowing direction