Preparation of salts of naphthalene sulfonic acid-formaldehyde condensates

Claim 1

A PROCESS FOR PREPARING A SALT OF A NAPHTHALENE SULFONIC ACID-FORMALDEHYDE CONDENSATE CHARACTERIZED BY HAVING A GOOD COLOR AND BEING SALT FREE WHICH COMPRISES THE STEPS OF (1) REACTING AT TEMPERATURES BETWEEN ABOUT 100* TO 180* FROM ABOUT 0.6 TO 0.9 MOL OF SULFURIC ACID PER MOL OF NAPHTHALENE, THEREBY OBTAINING A REACTION MASS CONTAINING NAPHTHALENE SULFONIC ACID PLUS UNREACTED NAPHTHALENE, (2) INTRODUCING WATER INTO SAID REACTION MASS THEREBY FORMING AN AQUEOUS LAYER WHICH CONTAINS SAID NAPHTHALENE SULFONIC ACID AND A LAYER CONTAINING UNREACTED NAPHTHALENE, (3) SEPARATING SAID AQUEOUS LAYER CONTAINING SAID NAPHTHALENE SULFONIC ACID FROM SAID LAYER CONTAINING UNREACTED NAPHTHALENE, (4) CONDENSING SAID NAPHTHALENE SULFONIC ACID WITH FROM ABOUT 0.5 TO 1.0 MOL OF FORMALDEHYDE PER MOL OF SAID NAPHTHALENE SULFONIC ACID, SAID FORMALDEHYDE BEING SELECTED FROM THE GROUP CONSISTING OF FORMALDEHYDE AND COMPOUNDS LIBERATING FORMALDEHYDE AND THEREAFTER (5) NEUTRALIZING THE RESULTING NAPHTHALENE SULFONIC ACID-FORMALDEHYDE CONDENSATE THEREBY OBTAINING A NEUTRALIZED SALT OF SAID NAPHTHALENE SULFONIC ACID-FORMALDEHYDE CONDENSATE.