Paper and paperboard production process and corresponding novel retention and drainage aids, and papers and paperboards thus obtained
First Claim
1. Process for producing a sheet of paper, paperboard or the like having improved retention and drainage properties, of the type which uses a dual system of an acrylic polymer and bentonite or a possibly treated kaolin as the primary and secondary retention aids, respectively, the introductions of which are separated by a stage for shearing the suspension or fibrous mass or paper pulp, characterized in that said polymer is a branched acrylic (co)polymer prepared in the form of a reverse phase water-in-oil emulsion, used either in emulsion inverted in water, or in a solution of the powder obtained by drying the emulsion.
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Abstract
The invention relates to an improved paper production process, according to which a branched polymer prepared in reverse phase emulsion is used as the main retention aid, and then bentonite is used as the secondary retention aid (a dual type system). The two additions are separated by a stage for shearing the fibrous suspension (or mass).
A distinctly improved retention of the fines is obtained, and also a distinct improvement in drainage. Moreover, the bentonite content in the white water is reduced.
42 Citations
23 Claims
- 1. Process for producing a sheet of paper, paperboard or the like having improved retention and drainage properties, of the type which uses a dual system of an acrylic polymer and bentonite or a possibly treated kaolin as the primary and secondary retention aids, respectively, the introductions of which are separated by a stage for shearing the suspension or fibrous mass or paper pulp, characterized in that said polymer is a branched acrylic (co)polymer prepared in the form of a reverse phase water-in-oil emulsion, used either in emulsion inverted in water, or in a solution of the powder obtained by drying the emulsion.
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14. Novel retention aid for the production of a sheet of paper, paperboard or the like, characterized in that it comprises a branched polyacrylamide (or more generally a branched acrylic (co)polymer) in reverse phase (or oil-in-water) emulsion (either in reverse phase emulsion dissolved or “
- inverted”
in water, or in a solution of the powder obtained by drying the reverse phase emulsion, especially by means of spray-drying). - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22)
- inverted”
Specification