Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/41—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups
  • D21H17/42—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups anionic
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/37—Polymers of unsaturated acids or derivatives thereof, e.g. polyacrylates
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/41—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups
  • D21H17/44—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups cationic
  • D21H17/45—Nitrogen-containing groups
  • D21H17/455—Nitrogen-containing groups comprising tertiary amine or being at least partially quaternised
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
  • D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
  • D21H21/18—Reinforcing agents
  • D21H21/20—Wet strength agents
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
  • D21H23/76—Processes or apparatus for adding material to the pulp or to the paper characterised by choice of auxiliary compounds which are added separately from at least one other compound, e.g. to improve the incorporation of the latter or to obtain an enhanced combined effect
  • D21H23/765—Addition of all compounds to the pulp

Definitions

• the present invention relates to the manufacture of a sheet of paper, and more particularly to the addition of agents for improving the wet strength.
• Wet strength is not a natural property of paper: untreated paper made from an assembly of cellulose fibers sees its strength decrease by 95% when it is saturated with water. It is however a sought-after property for many types of paper which will come into contact with water during their use, such as paper towels, handkerchiefs, "paper towels", disposable paper products used in hospitals, labels, etc.
• the resistance of the paper is mainly attributed to the hydrogen fiber interfaces. Water destroys most of the hydrogen bonds, resulting in a decrease in wet strength.
• the improvement of the wet resistance of papers has been carried out according to two approaches. The first is to apply a hydrophobing layer on the surface of the paper which will prevent water from reaching and destroying the hydrogen bonds, which can be achieved, for example, by coating the paper.
• the other approach consists in adding to the pulp, at the headbox, that is to say at a point where the paper machine works in a humid zone, chemical agents capable of protecting the hydrogen bonds and / or creating water resistant connections.
• the present invention relates to the second approach.
• the process according to the invention described in claim 1 overcomes these drawbacks: it does not generate AOX, formaldehyde or epichlorohydrin. It consists in successively introducing into the suspension of cellulose fibers entering the headbox a cationic polyelectrolyte carrying a quaternary ammonium group, then an anionic polyelectrolyte carrying sulfonate groups.
• the overall amount of cationic and anionic polyelectrolytes used is between 0.02 to 2.5% by weight, relative to the cellulosic composition, counted by dry weight, entering the headbox.
• the weight ratios between the cationic agent and the anionic agent are not indifferent.
• the cationic polyelectrolytes necessary for the implementation of the invention are copolymers resulting from the copolymerization of n molecules of an uncharged vinyl monomer (A) and of m molecules of a vinyl monomer (B) carrying a group quaternary ammonium, the molar ratio n / m being between 25 and 0.2, preferably between 5 and 0.5, the mass molecular of the copolymer being between 40,000 and 2.10 6 , preferably between 100,000 and 1.10 6 .
• cationic polyelectrolytes may result from the copolymerization of styrene as an uncharged monomer (A) with, as monomer (B) carrying a quaternary ammonium group, substituted maleimides of formula where R1, R2, R3, R4 and X - have the above meanings.
• copolymers of acrylamide and of acryloxyethyltrimethylammonium chloride are cationic polyelectrolytes preferred for the invention. These products are obtained in a manner well known to those skilled in the art (see inter alia F. Mabire, POLYMER, Sept 1984, vol. 25, or FR-A-2390983 or US-A-4319013 or EP-A -150933).
• the anionic polyelectrolytes carrying sulfonate groups which constitute the other associated chemical means of the invention are copolymers resulting from the copolymerization of m 'molecules of an uncharged vinyl monomer (A') and n 'molecules of a monomer vinyl (B ') carrying a sulfonate group, the m' / n 'molar ratio being between 25 and 0.2, preferably between 5 and 0.5, the molecular weight of the copolymer being between 40,000 and 2.10 6 , preferably between 100,000 and 1.10 6 .
• anionic polyelectrolytes can in particular result from the copolymerization of an uncharged monomer (A ′) consisting of acrylamide, methacrylamide or maleic anhydride of 2-acrylamido-2-methylpropane sulfonate (AMPS), or of an anionic monomer (B ') where R 'is a benzene sulfonate, naphthalene sulfonate, ethylene sulfonate or propene sulfonate residue.
• a ′ uncharged monomer
• AMPS 2-acrylamido-2-methylpropane sulfonate
• B ' anionic monomer
• monomer (B ') is a styrene sulfonate
• monomer (A') can simply be styrene
• anionic polyelectrolytes are obtained in a manner known to those skilled in the art according to the same general methods as those which have been reported above for cationic polyelectrolytes.
• Preferred copolymers for the invention are copolymers of acrylamide and 2-acrylamido-2-methylpropane sulfonate (AMPS).
• the implementation of the invention offers no major difficulty, since it consists simply in the process well known to those skilled in the art skilled in the manufacture of paper, to be added successively to the fibrous composition entering the headbox the cationic agent, then the anionic agent as defined above.
• the formulas were produced on a FRANCK device from a Kraft type chemical paste (ALICEL), unless otherwise indicated.
• the dough is refined to 27 degrees Shopper. (For the Shopper degree, see the book by Pierre Valette and Christian de Choudens: Wood, Pulp, Paper, p.84).
• the pH of the fiber suspension is adjusted to 8.3 with dilute sodium hydroxide.
• the reagents are added to the suspension of cellulose fibers maintained with stirring.
• the contact time between an agent and the fibers is 3 minutes.
• the average grammage obtained is of the order of 80 g / m 2 .
• the formulas are conditioned for at least 24 hours in a room thermostatically controlled at 22 ° C with a humidity level of 50% before the tensile tests are carried out.
• the tensile strength tests are carried out in accordance with standard NF Q 03-056. Strips (test pieces) of paper 180 mm long and 15 mm wide are cut from the formettes. The tensile tests are carried out with an ADAMEL Lhomargy device, set at a speed of 50 mm / min.
• the paper is immersed for one hour in tap water at a constant temperature of 25 ° C. the paper strips are then wrung out according to a rigorous procedure described in the standard. Ten tensile tests are carried out on 10 wet specimens. The tensile strength F is measured in Newtons.
• This value is a characteristic of paper. To characterize an additive, you need a relative characteristic. We chose it, not compared to a paper obtained without additive, because the LRH is in this case, both too weak and very poorly reproducible. It is evaluated with respect to the standard which corresponds to the addition of 1% of active material with respect to the fiber in PAE.
• the PAE used is a commercial product (R4944 from CECA SA) formulated with 12.5% active ingredient. With the conditions defined above, when using PAE at 1% in MA (ie about 8% in commercial solution), a wet rupture length LRH of the order of 600 m is measured.
• a PRH of 100% corresponds to the performance of the PAE at 1% in MA This is an ordinary result, but obtained with a polluting product. HRPs ⁇ 50% are already considered acceptable, provided that they are obtained with clean products; 85% of HRPs are regarded as very interesting. The results are given at more or less 10%.
• a cationic acrylic copolymer composed of acrylamide (54% by moles, or approximately 30% by weight) and chloride of acryloxyethyltrimethylammonium (46 mol%, or approximately 70% by weight) of high molecular mass (Mw greater than 500,000).
• the untreated paper has a PRH of the order of 10%.
• Example 1 The same procedure and the same products are used as in Example 1.
• the cationic copolymer is added at 1% of active material relative to the fiber.
• the sulfonated anionic copolymer is then added at different dosages.
• the results are collated in the following table.
• the results corresponding to Example 1 and Example 3 were recalled there.
• the example illustrates the fact that, for given conditions (type of paste, pH, etc.), there is an optimum of the concentrations of the two products to be used, in the present case, between 1 / 0.6 and 1/1 , with a fairly pronounced maximum around 1 / 0.8.
• An overdose of anionic agent reduces the gain in wet strength.
• Example 7 (acrylamide-acryloxyethyltriltuethylammonium chloride copolymer system / styrene-sulfonate-maleic anhydride copolymer)
• Example 8 (acrylamide-acryloxyethyltrimethylammonium chloride / polystyrenesulfonate copolymer system)
• Example 9 (against example: acrylamide-acryloxyethyltrimethylammonium chloride / polyacrylate copolymer system)

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Paper (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)

Applications Claiming Priority (3)

Publications (2)

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Family Applications (1)

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• 1993
  • 1993-06-09 FR FR9306904A patent/FR2706496B1/fr not_active Expired - Fee Related
• 1994
  • 1994-05-27 EP EP94917691A patent/EP0704007B1/fr not_active Expired - Lifetime
  • 1994-05-27 AU AU69313/94A patent/AU6931394A/en not_active Abandoned
  • 1994-05-27 ES ES94917691T patent/ES2110759T3/es not_active Expired - Lifetime
  • 1994-05-27 AT AT94917691T patent/ATE160193T1/de not_active IP Right Cessation
  • 1994-05-27 PL PL94311873A patent/PL172968B1/pl unknown
  • 1994-05-27 DE DE69406787T patent/DE69406787T2/de not_active Expired - Fee Related
  • 1994-05-27 WO PCT/FR1994/000626 patent/WO1994029523A1/fr active IP Right Grant

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