Re: Lump (Grums) Formation After Final Packaging
Is your product warm when it is packed or is it subject to thermal cycling after packaging?
I would be very surprised if it was an electrostatic effect. What you describe sounds very similar to what happens when a hot moisture sensitive product is packaged. The outer surface of the package cools first which sets up gas circulation within the package. The gas is warmed in the centre and moisture evaporates, when the gas reaches the cooler areas it cools and the moisture condenses forming lumps. When the whole packages reaches equilibrium, the moisture levels even out again making this very difficult to find experimentally.
It is obviously more of an issue with materials which are soluble in water but can also effect some materials which are not normally considered soluble. Best guess for the cause with non-soluble materials is that depending upon the the processing method, they can have high levels of soluble contaminants in a very thin surface layer.
If this is the problem cooling before packing, storing packages at constant temperature or a bag material which allow moisture migration out to the environment may help. ■
Re: Lump (Grums) Formation After Final Packaging
Dear sir:
Your answer was very helpful to understand the problem. We´ll check temperatura conditions at the moment of packaging.
Thanks you very much. ■
Formation Of Lumps
The air that accompanies product from a drier often has a high relative humidity and, if packed before cooling, will condense the moisture content from the air in the voidage as the mass cools. As pointed out by RPD, some of this moisture will tend to migrate to the cooler boundaries but that trapped in the bulk will form on cusps of particle contact to increase the cohesive effect. The bulk strength of fine particulates will also grow due to time consolidation as excess air expresses from the voids and the reduction of void pressure allows more contact pressure to develop on th epoints of co-ordination. If the material is moisture soluable or hygroscopic, the situation could be excacabated by storage in a condition of high humidity and/of fluctiuating temperatures that cause 'thermal ratcheting' of the contents.
If it is practical to blow warm dry air through the bed before packing to displace the humid gas, most of the problems should disappear. ■
Re: Lump (Grums) Formation After Final Packaging
Mr. Bates:
You have been very clear. I really haven´t known about some topics that you mention. We´ll take into account them.
thanks you very much. ■
Lump (grums) formation after final packaging
Dear sir:
We have had problems due to the formation of lumps of product inside the containers after the packaging. These lumps are easily broken between fingers, but they are not desirable in order to a good presentation to our clients. In some cases the whole product inside the container becomes "a big lump".
The phenomenon takes place one or two days after the packaging but not in every batch.
The product is an active pharmacuetical ingredient. The last proscess operations before packaging are drying under vacuum in a rotary bicone at about 40ºC and milling by a hammer mill at 4600 rpm. All equipment are earth grounded. The container is a polyethilene bag inside a polyethilene drum. The weight is about 15 - 25 kg per drum.
We couldn´t relate this phenomenon to any reason. The product meets its loss on driying and water content specifications.
Somebody supossed som problem about static electricity, but I think that it is not (we are going to meassure it soon).
I´ll appreciate If you have any experience about this or if you can recomend any literature.
Thanks in advance. ■