[jake.n]

We blow our own HDPE bottles and we are having problems with our quart bottles when filled with light solvents and our glycol/ether hydraulic brake fluid.  The bottle is round and about 10" tall.  The bottle will "suck in" on the panel, specifically, right below the seam of the bottle where the label meets the taper on the top of the bottle.

Originally I thought this was a pressure problem, as the bottles are heat sealed.  Even when stored in an oven at 45°C the bottles are sucking in, rather than blowing out.  Now I am beginning to suspect that this is not a pressure problem, but a problem with the HDPE itself.

Has anyone had any similar issues with HDPE and very good solvents (eg mineral spirits, glycol ethers)?  We are trying to improve the structural integrity of the bottle, but would like to avoid the cost of fluorinating the bottles.

[Debugger]

Hi there,

There are several factor affect the pressure inside any polymer container containing solvents. Here are some questions :

- What is the temperature during filling and sealing?
- Is the solvent you fill in is saturated with any gas or can the solvent still dissolve any gas?
- Did you check the permeability of HDPE for the solvent?

My experience is that, incresing the wall thickness does not improve much as the container is still flex.

If HDPE is no permeable to your solvent, my recommendation is temperature should not be high during filling and liqiuid should be saturated with gas so that the air in the overhead space should not be dissolved in liquid.

If the HDPE is permeable to you solvent, you need to change the material. Flourinated HDPE is an alternative. Other alternatives are coextruded bottles (e.g. polyamide/HPDE layers) and EVOH bottkes to decrease the permeability but it costs some money.

Debugger