Paraformaldehyde – Product description
Identification
ALDER paraformaldehyde is a white solid low molecular weight polymer of formaldehyde available in the form of free flowing flakes.
It contains 89-91% of formaldehyde and 9-11% of water.
Like formaldehyde in aqueous solution, it is very reactive and depolimerizes readily under conventional processing conditions. It is easy to obtain a formaldehyde solution by simply dissolving paraformaldehyde in hot water.
A pH adjustment consistent with the subsequent use of the solution may be made to speed up the process, as at the extreme values of pH the dissolving rate is increased.
The pH of a 37% solution obtained form ALDER paraformaldehyde without any addition is 3.5. The solution rate is rather high, as working at 55°C with normal agitation and pH adjustment to 8, such solution is ready in only 20 minutes.
However, paraformaldehyde needs not to be previously dissolved in water in order to take part in a chemical reaction.
Easy to store and use, it can replace the formaldehyde solution in most reactions, offering outstanding advantages.
In the manufacture of resins the low water content allows for the shortening of reaction time, the increase of the charge size in a given reactor, and the complete or partial elimination of the dehydration stage.
For avoiding the pollution arising at the disposal of the distillate obtained in the thermosetting resin production which is contaminated with organic matter, it is advisable to substitute the aqueous formaldehyde with paraformaldehyde up to the quantity necessary to reach the desired product concentration without any distillation.
Paraformaldehyde storage is less expensive than the storage of formaldehyde solution, which requires expensive tanks and which may be stabilized or kept warm.
Its typical properties are:
| Appearance: | free flowing, white solid flakes with pungent typical formaldehyde odour |
| Flammability: | combustible, with flash point (tag open cup) of about 95°C |
| Vapour pressure: | varies with air humidity, being between 1 and 3 mmHg at 30°C |
| Melting point: | about 150°C in sealed tube; in the open it sublimes rapidly before melting at 130°C to 140°C |
| Bulk density: | varies with degree of compactness: free flowing, about 0.7 kg/lt; packed about 0.75 kg/lt |
Sale specifications
| Guaranteed | Typical | |
| Assay, as formaldehyde: | 91±1 wt% | 90.5 wt% |
| Water content: | 9.00±1 wt% | 9.5 wt% |
| Acidity, as formic acid: | max 0.07 wt% | 0.005 wt% |
| Ash content: | max 0.04 wt%. | 0.003 wt% |
| Iron content: | max 0.0003 wt% | 0.0001 wt% |
| Form: | flakes | |
| Particle size: | most of the flakes with dimensions of about 5×10 mm, thickness 2 mm |
Packaging
ALDER paraformaldehyde is supplied in 25 Kg polyethylene bags on 1000 Kg polyethylene film shrinkwrapped pallets, and in 500 or 1000 Kg big bags, palletized. Other types of containers may also be employed or shipments may be made in bulk after special agreement has been made.