| (19) |
 |
|
(11) |
EP 0 355 816 A3 |
| (12) |
EUROPEAN PATENT APPLICATION |
| (88) |
Date of publication A3: |
|
09.09.1992 Bulletin 1992/37 |
| (43) |
Date of publication A2: |
|
28.02.1990 Bulletin 1990/09 |
| (22) |
Date of filing: 23.08.1989 |
|
|
| (84) |
Designated Contracting States: |
|
AT BE CH DE ES FR GB GR IT LI LU NL SE |
| (30) |
Priority: |
26.08.1988 US 236816
|
| (71) |
Applicant: NALCO CHEMICAL COMPANY |
|
Naperville
Illinois 60563-1198 (US) |
|
| (72) |
Inventor: |
|
- Smith, James H.
Lisle
Illinois 60532 (US)
|
| (74) |
Representative: Ruschke, Olaf et al |
|
Ruschke & Partner
Pienzenauerstrasse 2
81679 München
81679 München (DE) |
|
| |
|
| (54) |
Colloidal alumina as a paper retention aid |
(57) A binder which is added to a paper-making furnish comprising:
a colloidal alumina sol having a positive surface charge and a colloidal alumina concentration
in the range between 0.1-1%, the colloidal alumina having a particle size in the range
between 1-50 nanometers and is added to the furnish in an amount between about 0.025-0.5%
by weight; and
an anionic polymer flocculant which is added to the furnish in an amount between about
0.01-0.1% by weight.