|
Textile CellOH _I_ NMMO _H2O __CellOH _II_ E, P*), H AS, PHK TCF, ECF
Non-Wovens B, E, S, H, P*) AS, (PHK), K TCF, ECF
Ethers
MC CellONa _ CH3Cl _ Cell_OCH3_x S, E, P, H, MHW,CL AS, (PHK), SO ECF
MHPC CellONa _ CH3Cl PO__
Cell__OCH2CHOCH3_x_OCH3_y_
S, E, P, H, MHW,CL AS, (PHK), SO ECF
HEC CellOH _ EO OH_ __
Cell__OCH2CH2O_x_CH2CH2O_y_
S, E, P, H, MHW,CL AS, (PHK), SO ECF
CMC CellONa _ ClCH2COO_ _
Cell__OCH2COONa_x
S, E, P, H, MHW,CL AS, (PHK), SO ECF
Pulp Properties and Applications
Tab. 11.5 Continued.
Product Simplified reaction scheme Raw material Pulping
Processes
Bleaching
Processes
Acetate
Tow CellOH _ _CH3CO_2O H_ __
Cell_OCOOCH3_2_3
MHW,H, S, E, P AS (CCE),
PHK (CCE)
ECF,
CONV
Plastics P, CL PHK-CCE, SO ECF,
CONV
Nitrocellulose (NC)
High-N-NC (x = 3) CellOH _ HNO3
H_ __Cell_ONO2_x CL SO CONV
Low-N-NC (x = 2) CL, S SO, AS CONV,
ECF
Microcrystalline
Cellulose (MCC)
CellOH H_ __CellOHcryst MHW,H, S, E, P (AS), PHK ECF
Raw Material:
B (beech), E (eucalypt), S (spruce), H (hemlock), P (pine), MHW(mixed hardwood), CK (cotton linters)
*) sulfite cooking with pine and other resinous wood requires different pH profile → two-stage
Processes, or measures to remove the resins
Pulping Purification Processes:
AC (acid sulfite), PHK (prehydrolysis kraft), CCE (cold caustic extraction), SO (soda).
Products:
EO = ethylene oxide, PO = propylene oxide
MC (methylcellulose), MHPC (methylhydroxypropylcellulose), HEC (hydroxyethylcellulose).
Chemical Properties
Chemical Composition
Organic Compounds
Hemicelluloses (short-chain alkali-soluble carbohydrates)
One of the main objectives of dissolving pulp production is the removal of noncellulosic
Carbohydrates which constitute the major part of the short-chain material
in the polymer. The available purification processes – particularly the hot and cold
caustic extraction processes – contribute to a considerable increase in production
Costs, mainly due to high yield loss and high chemical charges (see Sections 8.3
And 8.4). Therefore, the extent of purification is adjusted to the demands on the
Particular further processing. However, even small amounts of alien polysaccharides
May influence the processability and properties of the final product.
During steeping, the first step of alkaline processing of dissolving pulps for
The viscose and etherification procedures, alkali-soluble hemicelluloses are
Removed to an extent depending on pulp quality, the process conditions and the
Dissolving Grade Pulp
Equilibrium concentration level in the recycled steeping liquor. In this definition,
The hemicelluloses consist of both alkali-soluble degraded cellulose and heteropolysaccharides
Such as degraded xylan or mannan. The accumulation of hemicelluloses
Дата добавления: 2015-10-21; просмотров: 106 | Нарушение авторских прав
<== предыдущая страница | | | следующая страница ==> |
In the past, the latest forecasts reveal a slight change in this trend (see Chapter | | | In the steeping lye inhibits cellulose degradation during ageing due to the |