Alcotex B78 is polyvinyl alcohol which has been specially developed for use as a primary suspending agent for vinyl chloride suspension polymerisation. It is manufactured by Synthomer using our exclusive batch process which has advantages over other manufacturing methods,in that it allows more efficient control over the degree of hydrolysis and particle size of the product.
NMR measurements have shown that Alcotex B78 has a block distribution of acetate groups.
In listing the advantages of using Alcotex B78, it must be noted that differences in the PVC grade, polymerisation recipe and plant design influence the extent to which any of these benefits are obtained.
The use of Alcotex suspending agents requires no significant plant modification.
Alcotex B78 gives a PVC which is rather more dense and slightly less porous than that obtained using Alcotex 72.5. It confers other advantages, namely:-
A) PVC Plant Output and Operating Cost
1. The polymer build-up in the reactor is low,reducing down-time for cleaning.
2. The desired grain size can be achieved using low levels of Alcotex B78.
3. PVC grains of good porosity are produced, which facilitates free monomer removal.
4. Alcotex 78 is not prone to dusting.
5. Alcotex 78 is less prone to changes in VCM quality than other Polyvinyl Alcohols.
B) PVC Polymer Quality
1. Alcotex B78 is used to make PVC with a wide range of porosities and bulk densities.
2. The PVC grains made with Alcotex B78 tend to be more spherical such that slightly higher bulk density may be combined with minimum reduction in porosity and with optimum flow characteristics.
3. The PVC grain size distribution is narrow, and the levels of over-sized rejects are low.
4. Plasticiser absorption properties can be adjusted to give fast dry-up times.
5. The “fish-eye” count is low, reducing the reject level in critical applications.
1.Alcotex B78 should be stored away from wet areas. Ingress of moisture should be avoided to maintain product quality.
2. As supplied, the product should remain fit for use for 24 months from the date of production. Beyond that date, the material may still be fit for use, but we would advise that it is good practice to test the material. As such, we advise that material stored for 12 months or more after delivery should be tested before use.
3. Aqueous solutions of Alcotex B78 if stored for long periods at elevated temperatures are prone to mould and bacterial attack.
Alcotex B78 is supplied in 25kg (nominal) papersacks. Each sack carries the grade number, batch number and net weight. Deliveries are palletised with each pallet being stretch wrapped and labelled with the relevant shipping marks.
Synthomer Limited Head Office
Phone: +44 (0)1279 436 211
FAX: +44 (0)1279 444 025
|Total Solids||>= 95.0||%|
|Degree of Hydrolysis||76.0-79.0||mole%|
|Viscosity @ 20ºC, 4% solution||5.5-6.5||mPa.s|
|Ash Content||0.5%||max. as Na2O|
|Appearance||Off white to pale yellow granules|
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