 | Walocel® HM is produced by chemically converting the naturally renewable cellulose macromolecule. We only use high-grade chemical pulp as our raw material. Alkali cellulose is in turn converted with methyl chloride and propylene oxide to produce the desired products under controlled reaction conditions.
Cellulose is a naturally occurring biopolymer which can be altered chemically in many different ways. Glucose units linked in a linear chain formation make up its structure. For each glucose unit there are three hydroxyl groups (OH groups) which provide reactive centres where chemical reactions can take place.
Cellulose is insoluble in water. By etherifying the reactive centres, Dow Wolff Cellulosics transforms the raw material into the hydroxypropylmethyl cellulose products -Walocel® HM - which are soluble in hot or cold water.
By controlling the reaction conditions it is possible to regulate the degree of etherification very precisely.
The characteristic value for the degree of conversion is the percentage by weight of the substituents “hydroxypropoxyl” and “methoxyl”. Under its brand name Walocel® HM, Dow Wolff Cellulosics offers HPMC types Hypromellose 2910, Hypromellose 2208 and Hypromellose 2906 in accordance with USP nomenclature:
Substitution | Methoxyl groups
(% by weight) | Hydroxypropoxyl groups
(% by weight) |
2910 | 28 - 30 | 7- 12 |
2208 | 19 - 24 | 4 - 12 |
2906 | 27 - 30 | 4 - 7,5 |
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