DIFF Subgroup
C01B 33/152 Preparation of hydrogels
Introduced: January 1980
Full Title
Full titles differ between systems:
IPC:
Silicon; Compounds thereof > Silicon oxides; Hydrates thereof > Silica; Hydrates thereof, e.g. lepidoic silicic acid > Colloidal silica, e.g. dispersions, gels, sols > Preparation of hydrogels
CPC:
Silicon; Compounds thereof ( C01B21/00, C01B23/00 take precedence; persilicates C01B15/14; carbides C01B32/956) > Silicon oxides; Hydrates thereof > Silica; Hydrates thereof, e.g. lepidoic silicic acid > Colloidal silica, e.g. dispersions, gels, sols > Preparation of hydrogels
Of 2 combined children, 1 exist in both systems.
1 codes are CPC-only extensions.
IPC defines codes here since 1980.
Child Classifications
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- C01B 33/154 by acidic treatment of aqueous silicate solutions since 1980 +2 CPC IPC+CPC Available in IPC and CPC