Naphthalene-sulphonic-formaldehyde condensates with low free aldehyde - obtd. by immediately adjusting the condensation prod. up to specific pH at 80 deg. C., etc.

摘要

Naphthalene-sulphonic acid/formaldehyde condensates with a low free formaldehyde (F) content (I) are produced by adjusting the condensation prod., immediately after condensation, to pH above 11.5 at a temp. of at least 80 deg.C and keeping the mixt. at this temp. until the content of free (F) is at the required low level. More specifically the reaction mixt. is adjusted at 85-100 deg.C to pH above 12. USE/ADVANTAGE - (I) are useful as additives for building materials . The process enables the prodn. of (I) with free (F) contents pref. below the detection limit, i.e. below 0.004-0.005 wt.%.