Acid-to-alkaline papermaking process

• US 5,240,561 A
• Filed: 08/20/1992
• Issued: 08/31/1993
• Est. Priority Date: 02/10/1992
• Status: Expired due to Fees

• Current Assignee: Progress Industry Company Limited
• Original Assignee: Progress Industry Company Limited
• Inventors: Kaliski, Adam E.
• Primary Examiner(s): Chin, Peter
• Application Number:
  US07/932,663
• Time in Patent Office: 376 Days
• Field of Search: 162/183, 162/138, 162/146, 162/158, 162/164.1, 162/162, 162/168.1, 162/169, 162/181.1, 162/181.2, 162/181.6, 162/181.9
• US Class Current: 162/138
• CPC Class Codes: D21H 17/07 Nitrogen-containing compounds
• CPC Class Codes: D21H 17/13 Silicon-containing compounds
• CPC Class Codes: D21H 17/66 Salts, e.g. alums
• CPC Class Codes: D21H 17/70 forming new compounds in situ, e.g. within the pulp or paper, by chemical reaction with other substances added separately

Abstract

A fundamentally new papermaking process for the manufacture of paper, board and other wet-laid products on a paper machine under conditions ranging from acidic to alkaline from aqueous furnishes treated with in-situ-synthesized complex functional microgels.

Claims

1. A process for the manufacture of paper, board and other wet-laid products under pH conditions ranging from 4.5 to 12.0, from aqueous furnishes comprising at least one kind of fibers selected from the group consisting of cellulosic fibers, synthetic organic fibers and inorganic fibers, said furnishes being treated with in-situ-synthesized complex functional microgel cements, retained in said products in proportions of from 0.4 to 10.0%, by weight, as determined by ashing, comprising the steps of:

(a) preparing, in situ, a transient chemically reactive subcolloidal hydrosol by blending with said furnishes two separate solutions, one of which comprises at least one reagent selected from the group consisting of alkali-metal silicates and quaternary ammonium silicates, employed in proportions of from 0.2% to 5.0%, by weight, of furnish solids, and the other of which comprises at least one reagent selected from the group consisting of alkali-metal aluminates and alkali-metal zincates, employed in proportions of from 0.2% to 5.0%, by weight, of furnish solids, wherein the ratio of said silicates to said aluminates, zincates or blends thereof is from 1;

10 to 10;

1, by weight;

(b) blending an aqueous solution comprising at least one cross-linking agent selected from a first group consisting of bivalent and multivalent inorganic salts, employed in proportions of from 0.4% to 10.0%, by weight, of furnish solids, said aqueous solution optionally comprising one or more additional cross-linking agent(s) selected from a second group consisting of organic, cationically active chemical compounds with at least two reactive groups in each molecule, employed in a proportion of up to 0.5%, by weight, of furnish solids, with the furnishes resulting from step (a) to cross-link said in-situ-formed transient chemically reactive subcolloidal hydrosol and synthesize in situ said complex functional microgel cements, whereupon said furnishes flocculate instantaneously, indiscriminately and completely;

(c) optionally purging said flocculated furnishes resulting from step (b) of dissolved contaminants; and

(d) recovering said flocculated furnishes resulting from steps (b) and (c) to form paper, board or other wet-laid products on a paper machine.

2. The process according to claim 1, wherein said furnishes optionally comprise one or more one of the following materials in proportions specified below in relation to furnish solids:

(a) filler pigments, up to more than 50%, by weight;

(b) color dyes, up to 5.0%, by weight;

(c) carbon black, deagglomerated by the master-batch method, up to 0.1%, by weight;

(d) latex adhesives with an average particle diameter larger than 70 nm, up to 5.0%, by weight;

(e) ultrafine acrylic polymer-emulsion adhesives with an average particle diameter smaller than 55 nm and a glass-transition temperature ranging from -60°

C. to +20°

C., up to 5.0%, by weight;

(f) waterborne acrylic rubber cements, up to 5.0%, by weight;

(g) waterborne disperse thermoplastic adhesives, up to 20.0% by weight;

(h) water-soluble adhesives, up to 2.0%, by weight;

(i) synthetic microfibrils, up to 2.0%, by weight;

(j) cellulosic microfibrils with a length of from 10 μ

m to 200 μ

m, prepared extraneously by the cascade microfibrillation process, up to 2.0%, by weight; and

(k) ultrafine electroconductive and/or magnetic ceramic and/or metallic powders with particle diameters finer than 0.2 μ

m, up to 20%, by weight.

3. The process according to claim 1, wherein aqueous solutions of said organic, cationically active chemical compounds with at least two reactive groups in each molecule are employed as an aftertreatment, by blending said aqueous solutions with furnishes already flocculated by said in-situ synthesized complex functional microgel cements.

4. The process according to claim 1, wherein said at least one reagent selected from the group consisting of sodium and potassium silicates and quaternary ammonium silicates is employed in said furnishes at a concentration of from 0.01% to 2.0% by weight.

5. The process according to claim 1, wherein said at least one reagent selected from the group consisting of sodium and potassium aluminates and sodium and potassium zincates is employed in said furnishes at a concentration of from 0.01% to 2.0% by weight.

6. The process according to claim 1, wherein said at least one bivalent or multivalent inorganic cross-linking salt selected from the group consisting of water-soluble, essentially colorless salts of calcium, magnesium, barium, aluminum, zinc and zirconium is employed in said furnishes at a concentration of from 0.02% to 4.0%, by weight.

7. The process according to claim 1, wherein said at least one organic cationically active chemical compound with at least two reactive groups in each molecule, selected from the group consisting of cationic surface active agents, organometallic Werner complexes and cationic polyelectrolytes, is employed in said furnishes at a concentration of up to 0.15%, by weight.

8. The process according to claim 2, wherein said extraneously prepared cellulosic microfibrils with a length of from μ

m to 200 μ

m are made from cellulosic fibers by the cascade microfibrillation process comprising the steps of;

(a) chopping said cellulosic fibers to a length preventing hydraulic spinning in the subsequent refining operations;

(b) refining an aqueous dispersion of said chopped fibers from step (a) at a solids concentration of up to 35%, by weight;

(c) additionally refining said aqueous disperson of fibers resulting from step (b) with the aid of centrifugal comminutors; and

(d) finalizing said cascade microfibrillation process with the aid of homogenizers in which said aqueous disperson of refined fibers resulting from step (c) is compressed at very high pressures and then rapidly decompressed, by passing through a nozzle, causing the residual bundles of fibrils to explosively separate into individual microfibrils.

9. The process for the manufacture of paper, board and other wet-laid products from aqueous furnishes according to claim 1, wherein the process is performed in a continuous mode in which

step (a) is performed by injecting two separate streams of aqueous solutions of subcolloidal-hydrosol-forming reagents into an in-line-agitated stream of said furnishes, to form said transient chemically reactive subcolloidal hydrosols, said one stream comprising at least one reagent selected from the group consisting of alkali-metal silicates and quaternary ammonium silicates and said other stream comprising at least one reagent selected from the group consisting of alkali-metal aluminates and alkali-metal zincates;

step (b) is performed by injecting into the in-line-agitated stream of said furnishes resulting from step (a) an aqueous solution of at least one cross-linking agent selected from a first group consisting of bivalent and multivalent inorganic salts, said aqueous solution optionally comprising one or more additional cross-linking agent selected from a second group consisting of organic cationically active chemical compounds with at least two reactive groups in each molecule, to cross-link said subcolloidal hydrosol and synthesize, in situ, said complex functional microgel cements, whereupon said furnishes become flocculated instantaneously, indiscriminately and completely;

optional step (c) is performed by purging said flocculated furnishes resulting from step (b) of dissolved contaminants; and

step (d) is performed by recovering said flocculated furnishes resulting from steps (b) and (c) to form paper, board and other wet-laid products on a paper machine.

10. A process for the manufacture of paper, board and other wet-laid products under pH conditions ranging from 4.5 to 12.0, from aqueous furnishes comprising fibers selected from the group consisting of cellulosic fibers, synthetic organic fibers and inorganic fibers, said furnishes being treated with in-situ-synthesized complex functional microgel cements, retained in said products in proportions of from 0.4% to 10%, by weight, as determined by ashing, comprising the steps of:

(a) blending into said furnishes an aqueous solution comprising at least one cross-linking agent selected from a first group consisting of bivalent and multivalent inorganic salts, used in proportions of from 0.4% to 10.0%, by weight, of furnish solids, said aqueous solution comprising optionally at least one additional cross-linking agent selected from a second group consisting of organic cationically active compounds with at least two reactive groups in each molecule, employed in a proportion of up to 0.5%, by weight, of furnish solids;

(b) preparing, separately, a transient chemically reactive subcolloidal hydrosol by blending an aqueous solution of at least one reagent selected from the group consisting of alkali-metal silicates and quaternary ammonium silicates, employed in a proportion of from 0.2% to 5%, by weight, of furnish solids, with an aqueous solution of at least one reagent selected from the group consisting of alkali-metal aluminates and alkali-metal zincates, employed in a proportion of from 0.2% to 5.0%, by weight, of furnish solids, wherein the ratio of said silicates to said aluminates, zincates or blends thereof is from 1;

10 to 10;

1;

(c) blending said furnishes resulting from step (a) with said transient chemically reactive subcolloidal hydrosol resulting from step (b) to synthesize, in situ, said complex functional microgel cements, whereupon said furnishes flocculate instantaneously, indiscriminately and completely;

(d) optionally purging said flocculated furnishes resulting from step (c) of dissolved contaminants; and

(e) recovering said flocculated furnishes resulting from steps (c) and (d) to form paper, board and other wet-laid products on a paper machine.