Compositions and methods for manufacturing starch-based compositions
First Claim
1. A starch-bound sheet having a thickness less than about 1 cm and a density greater than about 0.5 g/cm3 and comprising:
- (a) a binding matrix including starch and an auxiliary water-dispersible organic polymer, wherein the starch has a concentration greater than about 5% by weight of total solids in the sheet;
(b) fibers substantially homogeneously dispersed throughout the starch-bound sheet; and
(c) an inorganic mineral filler included in a range from 0% to about 90% by weight of total solids in the sheet.
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Accused Products
Abstract
Compositions and methods for manufacturing sheets having a starch-bound matrix reinforced with fibers and optionally including an inorganic mineral filler. Suitable mixtures for forming the sheets are prepared by mixing together water, unmodified and ungelatinized starch granules, an auxiliary water-dispersible organic polymer, fibers, and optionally an inorganic mineral filler in the correct proportions to form a sheet having desired properties. The mixtures are formed into sheets by passing them between one or more sets of heated rollers to form green sheets. The heated rollers cause the auxiliary polymer to form a skin on the outer surfaces of the sheet that prevents the starch granules from causing the sheet to adhere to the rollers upon gelation of the starch. The green sheets are passed between heated rollers to gelatinize the starch granules, and then to dry the sheet by removing a substantial portion of the water by evaporation. The starch and auxiliary polymer form the binding matrix of the sheets with the fibers and optional inorganic filler dispersed throughout the binding matrix. The starch-bound sheets can be cut, rolled, pressed, scored, perforated, folded, and glued to fashion articles from the sheets much like paper or paperboard. The sheets are particularly useful in the mass production of containers, such as food and beverage containers.
353 Citations
59 Claims
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1. A starch-bound sheet having a thickness less than about 1 cm and a density greater than about 0.5 g/cm3 and comprising:
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(a) a binding matrix including starch and an auxiliary water-dispersible organic polymer, wherein the starch has a concentration greater than about 5% by weight of total solids in the sheet;
(b) fibers substantially homogeneously dispersed throughout the starch-bound sheet; and
(c) an inorganic mineral filler included in a range from 0% to about 90% by weight of total solids in the sheet. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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43. An inorganically filled starch-bound sheet having a thickness less than about 1 cm and comprising:
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(a) a binding matrix including starch and an auxiliary water-dispersible organic polymer, wherein the starch has a concentration greater than about 5% by weight of solids in the sheet;
(b) fibers included in an amount in a range from about 1% to about 50% by weight of solids in the sheet, being substantially homogeneously dispersed throughout the binding matrix, having an average length greater than about 1.5 mm and having an average aspect ratio greater than about 10;
1; and
(c) an inorganic mineral filler included in an amount greater than about 10% by weight of solids in the sheet.
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44. An inorganically filled starch-bound sheet having a thickness less than about 1 cm and comprising:
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(a) a binding matrix including starch and an auxiliary water-dispersible organic polymer, wherein the binding matrix has a concentration of at least about 20% by weight of solids in the sheet;
(b) optionally fibers substantially homogeneously dispersed throughout the binding matrix and having an aspect ratio greater than about 10;
1; and
(c) an inorganic mineral filler included an amount greater than about 20% by weight of solids in the sheet.
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45. A starch-bound sheet formed by passing a starch-based composition between at least one set of heated forming rollers, the starch-bound sheet having a thickness less than about 1 cm and a density greater than about 0.5 g/cm3, the starch-based composition comprising:
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(a) water;
(b) substantially ungelatinized starch granules having a concentration greater than about 5% by weight of total solids in the starch-based composition, the starch granules having a gelation temperature;
(c) an auxiliary water-dispersible organic polymer having a thermal precipitation temperature that is less than the gelation temperature of the starch granules;
(d) an inorganic mineral filler having a concentration in a range from about 0% to about 90% by weight of total solids in the starch-based composition; and
(e) fibers substantially homogeneously dispersed throughout the starch-based composition. - View Dependent Claims (46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56)
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57. An inorganically filled starch-bound sheet formed bypassing a starch-based composition between at least one set of heated rollers, the starch-bound sheet having a thickness less than about 1 cm, the starch-based composition comprising:
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(a) water;
(b) substantially ungelatinized starch granules having a gelation temperature;
(c) an auxiliary water-dispersible organic polymer having a thermal precipitation temperature that is less than the gelation temperature of the substantially ungelatinized starch granules, wherein the substantially ungelatinized starch granules and auxiliary water-dispersible organic polymer have a combined concentration greater than about 20% by weight of total solids in the starch-based composition;
(d) an inorganic mineral filler having a concentration greater than about 20% by weight of total solids in the starch-based composition; and
(e) optionally fibers substantially homogeneously dispersed throughout the starch-based composition.
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58. An inorganically filled starch-bound sheet formed by passing a starch-based composition between at least one set of heated rollers, the starch-bound sheet having a thickness less than about 1 cm, the starch-based composition comprising:
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(a) water;
(b) substantially ungelatinized starch granules having a concentration greater than about 5% by weight of total solids in the starch-based composition and having a gelation temperature;
(c) an auxiliary water-dispersible organic polymer having a thermal precipitation temperature that is less than the gelation temperature of the substantially ungelatinized starch granules;
(d) an inorganic mineral filler having a concentration greater than about 10% by weight of total solids in the starch-based composition; and
(e) fibers included in an amount in a range from about 1% to about 50% by weight of total solids in the starch-based composition, wherein the fibers are substantially homogeneously dispersed throughout the starch-based composition, have an average length greater than about 1.5 mm, and have an average aspect ratio greater than about 10;
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59. A starch-bound sheet formed by a process comprising the steps of:
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(a) providing a starch-based mixture including water, substantially ungelatinized starch granules, fibers, optionally an inorganic mineral filler, and an auxiliary water-dispersible organic polymer that is capable of reducing adhesion between the starch-based mixture and heated forming rollers upon gelatinization of the starch granules;
(b) forming the starch-based mixture into an initial green sheet by passing the mixture between at least one set of heated forming rollers having a temperature such that a portion of the auxiliary water-dispersible organic polymer forms a layer of reduced adhesion on the outer surfaces of the initial green sheet in order to prevent substantially adhesion of the starch-based mixture to the forming rollers upon gelatinization of the starch granules;
(c) heating the initial green sheet to cause at least a portion of the starch granules to become substantially gelatinized in order to form an intermediate green sheet; and
(d) removing at least a portion of the water from the intermediate green sheet by evaporation so as to form a substantially hardened starch-bound sheet having a binding matrix that includes a mixture of substantially dried starch and auxiliary water-dispersible organic polymer, wherein the starch-bound sheet has a thickness less than about 1 cm and a density greater than about 0.5 g/cm3, wherein the substantially dried starch has a concentration greater than about 5% by weight of total solids in the starch-bound sheet wherein the fibers are substantially homogeneously dispersed throughout the starch-bound sheet, and wherein the inorganic mineral filler has a concentration in a range from about 0% to about 90% by weight of total solids in the sheet.
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Specification