Swollen starch-latex compositions for use in papermaking
First Claim
1. A filler suspension for use in papermaking comprising:
- filler particles and a composition of a complex of ionic, unruptured, swollen starch granules and an ionic latex, in an aqueous vehicle, said ionic starch granules having been swollen with hot water at a temperature below the gel point of the ionic starch, without cooking of the starch, said ionic starch consisting of an unmodified starch and ionic groups on said unmodified starch.
2 Assignments
0 Petitions
Accused Products
Abstract
A novel filler treatment comprising the preparation of swollen starch-latex compositions, prepared in the presence or absence of co-additives, and the addition of the said composition to a filler suspension, has been developed. Use of the treated filler during papermaking improves filler retention and produces filled papers where addition of the filler has only a minimal negative effect on strength properties. The swollen starch-latex compositions can be prepared in a batch or jet cooker, or by mixing with hot water under controlled conditions (i.e., temperature, pH, mixing, mixing time) in order to make the starch granules swell sufficiently to improve their properties as a filler additive but avoiding excess swelling leading to their rupture. The swollen starch-latex composition is then rapidly mixed with the filler slurry, preferably in a static mixer, and added to the papermaking furnish at a point prior to the headbox of the paper machine. The starch-latex composition can be used with wood-free or wood-containing furnishes. The treated filler is easily retained in the web during papermaking, improves drainage, and gives sheets having good formation. Sheets made with the treated fillers have higher bonding and tensile strengths than sheets produced using filler treated with either swollen starch alone or latex alone. Retention and drainage are further improved when conventional retention aid chemicals are added to the furnish containing the treated filler. The use of swollen starch-latex compositions could allow the papermaker to increase the filler content of the paper without sacrificing dry strength properties or increasing the amount, and hence the cost, of the retention aid added. The combination of swollen starch and latex could be used as furnish additives in the manufacture of both filled grades and grades that contain no filler such as sack papers and paperboard products.
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Citations
18 Claims
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1. A filler suspension for use in papermaking comprising:
- filler particles and a composition of a complex of ionic, unruptured, swollen starch granules and an ionic latex, in an aqueous vehicle, said ionic starch granules having been swollen with hot water at a temperature below the gel point of the ionic starch, without cooking of the starch, said ionic starch consisting of an unmodified starch and ionic groups on said unmodified starch.
- View Dependent Claims (2, 3, 4)
- 5. A process for producing a filler suspension for papermaking comprising contacting particulate filler with a composition of a complex of ionic, unruptured, swollen starch and an ionic latex, in an aqueous vehicle, said ionic starch granules having been swollen with hot water at a temperature below the gel point of the ionic starch, without cooking of the starch, said ionic starch consisting of an unmodified starch and ionic groups on said unmodified starch.
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7. A process of making paper comprising
a) mixing an ionic starch with hot water at a temperature below the gel point of the ionic starch, without cooking the starch, to form unruptured, swollen granules from the ionic starch, said ionic starch consisting of an unmodified starch and ionic groups on said unmodified starch, b) forming an aqueous papermaking furnish comprising pulp fibers, filler particles, a composition of a complex of the ionic, unruptured, swollen starch granules formed in a) and an ionic latex, in an aqueous vehicle, c) draining the furnish through a screen to form a sheet, and d) drying the sheet.
- 11. A paper comprising a matrix of pulp fibres and filler particles, and a retention system for said filler derived from the solids content of a composition of a complex of ionic, unruptured, swollen starch granules and an ionic latex, said ionic starch granules having been swollen with hot water at a temperature below the gel point of the ionic starch, without cooking of the starch, said ionic starch consisting of an unmodified starch and ionic groups on said unmodified starch.
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13. A pulp furnish for papermaking comprising:
- pulp fibres, filler particles, and unruptured, ionic, swollen starch granules, in an aqueous vehicle, said ionic starch granules having been swollen with hot water at a temperature below the gel point of the ionic starch, without cooking of the starch, said ionic starch consisting of an unmodified starch and ionic groups on said unmodified starch.
- View Dependent Claims (14, 15, 16, 17, 18)
Specification