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EP-4739839-A1 - DIALDEHYDE POLYMER PRODUCTION PROCESS

EP4739839A1EP 4739839 A1EP4739839 A1EP 4739839A1EP-4739839-A1

Abstract

The invention relates to a production process of dialdehyde polymer and its use in the paper industry and particularly in papermaking.

Inventors

  • The designation of the inventor has not yet been filed

Assignees

  • SNF Group

Dates

Publication Date
20260513
Application Date
20250917

Claims (14)

  1. 1. Process for preparing a dialdehyde polymer comprising at least the following successive steps: 1) mixing a base polymer with an aqueous solution comprising at least 10% by weight of process water, in order to form a solution SI of the base polymer; the base polymer comprising at least one non-ionic hydrophilic monomer selected from the group consisting of: acrylamide, methacrylamide, dimethylaminopropyl acrylamide, dimethylaminopropyl methacrylamide and mixture thereof; wherein the amount of base polymer in the solution SI is between 0.5 and 15% by weight; wherein the process water is any one of the followings, or a mixture thereof: - white water, - clarified water which corresponds to white water that has been filtered to remove solid particles having a particle size above 1 000 pm; 2) mixing at least one dialdehyde with the solution SI to form a solution S2; wherein the dialdehyde is selected from the group consisting of: glyoxal, glutaraldehyde, 2,5-furandicarboxaldehyde, adipaldehyde, succinaldehyde, starch dialdehyde, 2,2 dimethoxy ethanal and mixtures thereof; wherein the solution S2 has an amount of dialdehyde of between 5 and 40% by weight relative to the weight of the base polymer; 3) adjusting the pH of the solution S2 to at least 8 and reacting the base polymer with the at least one dialdehyde, for between 2 minutes and 90 minutes at a temperature comprised between 17°C and 40°C, to form a solution S3 comprising a dialdehyde polymer; 4) optionally, acidifying the solution S3 to a pH of between 2 and 4.
  2. 2. Process according to claim 1, wherein the base polymer comprises at least one cationic hydrophilic monomer.
  3. 3. Process according to any of the preceding claims, wherein the base polymer comprises at least: - between 40 and 99 mol% of non-ionic hydrophilic monomer(s), and; - between 1 and 60 mol% of hydrophilic cationic monomer(s).
  4. 4. Process according to any of the preceding claims, wherein the aqueous solution of step 1) consists of process water and fresh water.
  5. 5. Process according to any of the preceding claims, wherein the base polymer has a carbon content from renewable and non-fossil origin of between 5% by weight and 100% by weight, based on the total carbon weight of the base polymer.
  6. 6. Process according to any of the preceding claims, wherein the base polymer is a polymer of acrylamide and D ADM AC.
  7. 7. Process according to any of the preceding claims, wherein the base polymer is a polymer of 40 to 99 mol% acrylamide and 1 to 60 mol% DADMAC.
  8. 8. Process according to any of the preceding claims, wherein the dialdehyde is glyoxal.
  9. 9. Process according to any of the preceding claims, wherein the aqueous solution of step 1) comprises at least 10 % by weight of process water.
  10. 10. Process according to any of the preceding claims, wherein the aqueous solution of step 1) comprises at least 20 % by weight of process water.
  11. 11. Process according to any of the preceding claims, wherein the aqueous solution of step 1) comprises at least 50 % by weight of process water.
  12. 12. Process according to any of the preceding claims, wherein the aqueous solution of step 1) comprises at least 70 % by weight of process water.
  13. 13. Process according to any of the preceding claims, wherein the aqueous solution of step 1) comprises at least 90 % by weight of process water.
  14. 14. Process according to any of the preceding claims without claim 4, wherein the aqueous solution of step 1) consists of process water.

Description

DIALDEHYDE POLYMER PRODUCTION PROCESS TECHNICAL FIELD OF THE INVENTION The invention relates to a production process of dialdehyde polymer and its use in the paper industry and particularly in papermaking. TECHNICAL BACKGROUND The paper industry is in constant search for improvements of its manufacturing processes for paper, cardboard or the like, in particular with regard to costs reduction, yield, productivity and even the end-product properties. The papermaking process typically involves the dispersion of dry market pulp obtained from cellulosic material to form a thick stock corresponding to a suspension of a cellulosic fibers having a concentration generally comprised between 2 and 5% by weight. The thick stock is then diluted to form a thin stock, with a fiber concentration comprised between 0.5 and 1% by weight before passing through the headbox and being homogeneously placed on a wire in the form of a fiber mat corresponding to the paper sheet before water removal. The water elimination is made through three successive steps, i) natural drainage of the water on the wire during transport to the mechanical pressing area, ii) mechanical pressing of the sheet by roller and iii) drying of the paper sheet to obtain the final product, all this water constitutes the white water. During the preparation of the thick stock and the thin stock, various additives and polymers are added to the pulp suspension in order to give to the final product the desired properties, for example fillers which impart opacity, brightness, surface smoothness and printability. One problem faced by papermakers is that some of the additives, in particular fillers, are removed from the paper sheet during the water elimination steps and end up in the white water. The white water also contains some cellulose fibers and cellulose fines (short cellulose fibers). To minimize the cost and wastes generated, papermakers generally recycle these white water to form the thick and the thin stock and complete with fresh water. Glyoxalated polyacrylamides have been used for many years in the paper industry to impart wet and dry strength to the final papers. They are prepared by addition of glyoxal to a polyacrylamide. The double functionality of the glyoxal allows the polyacrylamide to create covalent bonds with cellulose fibers and the reversibility of the reaction make glyoxalated polyacrylamides perfect for temporary wet strength applications. EP 2 820 188 Bl and US 9,873,986 B2 disclose aldehyde modified polyacrylamide-type polymers. The Applicant has found a new way to reduce water consumption by preparing directly glyoxalated polyacrylamide using process water. The quantity of fresh water needed to produce the glyoxalated polyacrylamide is thus reduced without negatively impacting the wet and dry strength. It was unexpected to not negatively impact the properties of glyoxalated polyacrylamide as process water is known to contain large amount of dissolved compound and colloidal substances, for example fillers, which have been shown to interfere with many added chemicals. The invention is especially interesting, when the glyoxalated polyacrylamides are prepared on site. The emission of greenhouse gases, such as CO2, is significantly reduced as glyoxalated polyacrylamide are transported in diluted solution due to its instability. With the process of the invention, there is a double ecological benefit in reducing the quantity of fresh water used and the greenhouse gas emissions linked to the preparation and transport of the glyoxalated polyacrylamides . The new glyoxalated polyacrylamide production process of the invention is in line with the principle of environmental consciousness and the impact of industry and man on the planet. The new glyoxalated polyacrylamide production process optimizes the use of compounds during papermaking, allowing a reduction of the wastes generated, a reduction of the fresh water consumption, improve the quality of the wastewater rejected by paper production and reduce CO2 emissions linked to the transport of glyoxalated polyacrylamides. The present invention is advantageously carried out using materials of biological origin, such as biomass, or recycled materials. The synthesis of the monomer used in the invention are advantageously a biological synthesis, for example, by enzymatic catalysis or extracted from renewable raw material. The energy used to carry out the process according to the invention is advantageously derived from a heat pump or of renewable origin, for example wind power, photovoltaic s, or, in particular for mobile installations, from fuel cells or lithium batteries. SUMMARY OF THE INVENTION The invention relates to a production process of dialdehyde polymer and its use in the paper industry and particularly in papermaking. More particularly, the invention relates to a process for preparing a dialdehyde polymer comprising at least the following successive steps: 1) mixing a base polymer with a