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
  • 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
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L79/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen or carbon only, not provided for in groups C08L61/00 - C08L77/00
  • C08L79/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
• • 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
• • 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
  • D21H17/42—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups anionic
  • D21H17/43—Carboxyl groups or derivatives thereof
• • 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
  • D21H17/46—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/54—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen
  • D21H17/56—Polyamines; Polyimines; Polyester-imides

Definitions

• the invention relates to the manufacture of paper and in particular to the manufacture of paper having good wet strength.
• WER wet strength of the paper
• Wet LR is the breaking length of a strip of wet paper
• LR dry is the breaking length of a strip of dry paper.
• a paper is qualified as resistant to the wet state as soon as its WER exceeds 5%.
• a person skilled in the art has long known how to improve the WER of paper. Generally, it proceeds by incorporating, into the mass of the cellulosic pulp (also called fibrous suspension or paper pulp), resins which can react with the cellulosic fibers, such as the cationic resins which are spontaneously crosslinkable on the fiber at neutral pH, such as for example resins of the polyamidopolyamine-epichlorohydrin type, hereinafter designated by PAE, of low molecular weight well known to those skilled in the art.
• PAE polyamidopolyamine-epichlorohydrin type
• wet resistance promoters generally polymers of natural origin or derived from natural polymers, of more or less pronounced anionic or amphoteric nature, among others, sodium carboxymethylcellulose (H. Espy, 1983 Papermakers Research J., pp. 191 -195 or E. Strazdins 1994, Wet Strength Resins and their applications, Ed by L. Chan, TAPPI Press pp. 78-79) and modified guar gum (patents CA 808,531 or US 5,318,669). These products are marketed in powder form. Placing them in aqueous solution is a long and delicate operation which must be carried out prior to their use in the wet part of the paper machine. These solutions are very sensitive to bacterial degradation and cannot be stored under ambient temperature conditions in production workshops.
• US 5,200,036 proposes a solution based on the use of a PAE modified by reaction with the acid function carried by a monomer polymerizable by the radical route. The free double bond of the monomer is then copolymerized with a mixture of monomers to form a crosslinked monocomponent.
• This solution may not be effective because PAE crosslinks at neutral pH and at room temperature and all the faster the higher the temperature, see for example the book “Applications of Wet End Paper Chemistry", O. Au, I. Thorn, Ed: Blackie Academy and Professional. It is therefore likely that the PAE crosslinks at the time of the copolymerization and is therefore no longer fully reactive for reacting with the cellulose fibers.
• the Applicant has now found that it is possible to improve both the wet strength and the dry strength of the paper thanks to either a special process for treating paper using a cationic resin and a wet strength promoter based on an aqueous dispersion of a polymer containing acid functions, or to a particular stable composition based on a cationic resin and a wet resistance promoter based on an aqueous dispersion of a polymer containing acid functions and stabilized with a nonionic surfactant.
• aqueous dispersion within the meaning of the invention is often designated by latex.
• One of the objects of the invention is a process for treating paper consisting in applying to the paper a cationic resin and an aqueous dispersion of particles of thermoplastic polymer with a diameter ranging from 30 to 500 nm, stabilized by a polymeric or non-polymeric surfactant.
• the aqueous dispersion of the invention contains:
• the polymer concentration of the aqueous dispersion has no influence on the process.
• the cationic resins used for the implementation of the invention are low molecular weight resins with an azetidinium structure which can be crosslinked at neutral pH on the cellulose fiber.
• Resins of polyamidopolyamine-epichlorohydrin (PAE) structure constitute a typical example of cationic resins, and are moreover commonly used by a person skilled in the art. These resins (PAE) are obtained by the condensation of adipic acid and diethylenetriamine followed by condensation on epichlorohydrin.
• the monomers (A) having the acid functions can belong indifferently, partially or entirely to the polymeric surfactant or to the dispersed thermoplastic polymer.
• the aqueous dispersion is prepared by radical emulsion polymerization within the solution of surfactant which is an anionic or amphoteric polymer of a hydrophobic monomer or of a globally hydrophobic mixture of monomers whose composition can be adjusted to obtain a polymer with a glass transition temperature Tg chosen in advance.
• these anionic or amphoteric polymers can be the natural polymers which have been mentioned above; they can also be polymers or copolymers comprising on the one hand a monomer chosen from the family of acrylic acid, methacrylic acid or maleic anhydride, and on the other hand, a monomer chosen from the family of styrenic, vinyl monomers or acrylic or methacrylic esters, for example and without limitation, a styrene / maleic anhydride copolymer, a styrene / acrylic acid copolymer, a methyl methacrylate and acrylic acid copolymer, a styrene and butyl acrylate copolymer.
• the aqueous dispersion is prepared by radical emulsion polymerization in the presence of at least one surfactant of a mixture of monomers containing:
• monomer B chosen from the group consisting of vinyl, styrenic monomers, (meth) acrylic esters of C-
• the monomer A represents from 0.5 to 5% by weight.
• the preferred monomer A of the invention is acrylic acid or methacrylic acid.
• the mixture of monomers in practice represents from 5 to 60% by weight of the aqueous solution, however, as described above, the concentration of monomers has no influence on the paper treatment process.
• the monomer (s) A and the monomer (s) B are chosen and their respective quantities defined according to the properties and characteristics which it is desired to confer on the targeted polymer. For example, the glass transition
• Tg Tg of a polymer
• Tgi is the glass transition temperature of the homopolymer obtained by polymerization of the monomer i
• WJ is the weight fraction of the monomer i.
• the Tg of the polymer is fixed and the monomers (i) chosen accordingly.
• the surfactant (s) is (are) chosen from the group consisting of:
• the ionic surfactants can be anionic, cationic or amphoteric. Most often anionic surfactants are used such as sodium dodecylbenzene sulfonate or ethoxylated fatty alcohol sulfates ...
• the nonionic surfactants are chosen from the family of ethoxylated phenol alkyls or that of ethoxylated fatty alcohols.
• - polymeric surfactants such as copolymers comprising on the one hand a monomer chosen from the family of acrylic acid, methacrylic acid or maleic anhydride, and on the other hand, a monomer chosen from the family of styrenic, vinyl monomers or acrylic or methacrylic esters, for example and without limitation, a styrene / maleic anhydride copolymer, a styrene / acrylic acid copolymer, a methyl methacrylate and acrylic acid copolymer, a styrene and acrylate copolymer butyl.
• the invention is implemented by introducing the cationic resin and the latex into the aqueous suspension of cellulose fibers often referred to as paper pulp.
• the resin and the latex can be introduced successively in no particular order, or else at the same time, which considerably simplifies the installation.
• the useful quantities according to the invention are, with regard to the resin, from 0.25 to 3% by weight of dry matter of resin relative to the mass of dry fibers and from 0.25 to 3% with regard to latex.
• the Applicant has also discovered that it is possible, under certain conditions, to prepare a stable and ready-to-use mixture containing PAE and a latex. Indeed, the Applicant has discovered that when the latex is stabilized by a nonionic surfactant or by a predominantly nonionic mixture, consisting of ionic surfactants and nonionic surfactants, it is possible to mix it with the cationic resin without the composition obtained evolving or destabilizing during storage.
• Another object of the invention is an aqueous composition for improving the wet and dry resistance of paper containing:
• thermoplastic polymer dispersed in the form of particles with a diameter between 30 and 500 nm characterized in that said polymer contains acid functions and that the particles are generally stabilized by 0.1 to 5% by weight of at least one cationic or amphoteric nonionic surfactant or of a mixture of ionic and nonionic surfactants.
• the cationic resins used for the implementation of the invention are low molecular weight resins with an azetidinium structure crosslinkable to neutral pH on the cellulosic fiber.
• Resins of polyamidopolyamine-epichlorohydrin structure constitute a typical example of cationic resins, and are moreover commonly used by a person skilled in the art.
• These resins (PAE) are obtained by the condensation of adipic acid and diethylenetriamine followed by condensation on epichlorohydrin.
• aqueous dispersions consist of a dispersion of particles with a diameter between 30 and 500 nm of thermoplastic polymers containing acid functions and stabilized by a macromolecular surfactant or not.
• These latexes are obtained by radical polymerization in emulsion in the presence of at least one ionic or nonionic surfactant or else of a mixture of predominantly nonionic surfactants of a mixture of monomers containing:
• the preferred monomer A of the invention is acrylic acid.
• the mixture of monomers generally represents from 5 to 60% by weight of the aqueous solution, however the concentration of monomers has no influence on the stability of the composition nor on the process for treating paper using such a composition.
• the monomer (s) A and the monomer (s) B are chosen and their respective quantities defined according to the properties and characteristics which it is desired to confer on the finished polymer.
• the nonionic surfactant is chosen from the group consisting of ethoxylated alkyl phenol such as ethoxylated nonyl phenol and / or ethoxylated fatty alcohols.
• compositions described above are stable over time. They can be stored and used as is in a process for improving the wet and dry strength of paper.
• One of the objects of the invention is a method for improving the wet and dry resistance of paper consisting of the introduction of the stable aqueous composition described above into the aqueous suspension of cellulose fibers.
• the remnants of the preemulsion and of the catalytic solution are added in 4 hours using metering pumps so as to maintain the constant flow rate.
• the reaction medium is then left for 1 hour at 82 ° C. in order to lower the level of residual monomers.
• the dispersion DAF 36 is obtained under analogous conditions by substituting the dodecylbenzene with a fatty alcohol C12-14 ethoxylated for 30 moles of ethylene oxide in sufficient quantities to obtain a stable dispersion without coagulum.
• the characteristics of this dispersion are as follows:
• the papers are obtained according to the general process which consists of making formettes on a FRANCK device from a paste refined to a certain degree Shopper (for the degree Shopper-Riegler - ° SR-, see the NF standard Q 50-003, determination of drainability, Schopper-Riegler method).
• the composition is added with stirring. agents of wet resistance, that is to say in a first mode the latex, then approximately one minute later, the PAE-. (the order of introduction is irrelevant: the order of introduction of the PAE and the latex can be inverted, or introduced simultaneously), or in a second mode, the stable aqueous composition containing the latex and the PAE. Whichever mode is used, agitation is continued for approximately three minutes.
• the form is then produced at an average basis weight of the order of 65 g / m 2 , by draining the suspension on a metal grid, it is wrung, and the form is dried for 5 minutes at 95 ° C.
• the PAE resin is crosslinked by placing the forms for 7 minutes in an oven at a temperature of 105 ° C.
• the displayed LR measurements by which the REH value is calculated are averages of five tensile tests carried out on five test pieces, each from these five separate formulas.
• Tensile tests on a dry paper strip are carried out after a minimum of 24 hours of conditioning, at 23 ° C and 50% humidity.
• the tensile tests on the wet paper strip are carried out according to standard NF Q 03-056 on strips which, unless otherwise indicated, have been immersed for 1 hour in tap water at a constant temperature of 25 ° C., wrung out and then tested according to a rigorous procedure described in the standard.
• the water absorption capacity of the paper is estimated according to the Cobb test, TAPPI T441 -OM90 standard, which consists of measuring the amount of water absorbed by the paper for a period of 60 seconds.
• the result, called Cobb ⁇ O " is expressed in grams of water per m 2 of paper.
• the PAE resin used is a resin with 14% dry extract, stabilized at pH 2.5 - 3.5 (CECA, R4947D).
• the latexes used are:
• latexes here tested and indicated as latex A, latex B, latex C, are latexes whose polymeric dispersant is a water-soluble styrene / maleic anhydride copolymer, commercially available under the name of SMA® Resins (ELF ATOCHEM NA / ELF ATOCHEM SA). These resins are resins with a low molecular mass of between 500 and 10,000 and an acid number at most equal to 500.
• SMA 3,000 is a resin with a styrene / maleic anhydride molar ratio equal to 3;
• SMA 2625 is a resin with a styrene / maleic anhydride molar ratio equal to 2 esterified with propanol or any other suitable alcohol mixture, at an esterification rate of between 75 and 100% of the hemiester.
• a latex D was also prepared, which is an ordinary anionic latex in which the dispersant is a surfactant, sodium dodecylsulfate (SDS). The table opposite brings together the compositions of these latexes. The components are expressed as dry matter. The extract of these latexes is close to 25%.
• Example 1 (PAE / composite latex combination on wood fibers)
• the example illustrates the limit that can be expected from a treatment with a PAE resin alone according to the prior art of a chemical cellulosic pulp made of resinous fibers chemically bleached (Cellulose from the Rhône and Aquitaine) and refined at 25 ° SR.
• the wet strength treatment according to the prior art consisted of adding PAE resin to the mass at various dosages up to 2.2% (by weight of dry product dosed relative to dry fibers).
• the table below shows wet strength values as a function of the PAE content.
• Example 1 The paste from Example 1 was taken up, treated successively with the PAE resin, with mixed latex A, and with a combination of latex A and PAE.
• the combination of PAE with standard latex D is given as a counterexample; the level of PAE and latex used are both expressed as the level of dry matter relative to the fibers.
• Example 3 PAE / mixed latex combination on cotton fibers
• the example illustrates the limit which is reached during ordinary treatment with a PAE resin alone according to the prior art of a chemical cellulosic pulp consisting of chemically bleached vegetable fibers and refined to a high degree Shopper and the possibility offered by the treatment of the invention to exceed it, a result inaccessible with the means of the prior art.
• these are refined cotton fibers at 60 ° SR.
• the wet strength treatment according to the prior art consisted of adding PAE resin to the mass in various dosages up to 3.5% (PAE dosed in dry product relative to dry fibers).
• the rate of mixed latex added is expressed as the rate of dry matter relative to the dry fibers.
• the table shows the evolution of the rupture lengths as a function of the PAE content.
• the fibrous suspension was treated only with 1% PAE.
• the fibrous suspension was treated successively with 1% PAE and with 1% DAF 25 latex.
• a stable composition of PAE and DAF 36 latex was first produced.
• the contribution of each compound in the dry matter is 50%.
• the fibrous suspension was treated with 2% of the stable composition.

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• Chemical Kinetics & Catalysis (AREA)
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• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Paper (AREA)
• Compositions Of Macromolecular Compounds (AREA)

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• 1998
  • 1998-10-14 JP JP2000517148A patent/JP2001521069A/ja not_active Withdrawn
  • 1998-10-14 CA CA002307286A patent/CA2307286A1/fr not_active Abandoned
  • 1998-10-14 KR KR1020007004348A patent/KR20010031354A/ko not_active Application Discontinuation
  • 1998-10-14 BR BR9815210-6A patent/BR9815210A/pt not_active Application Discontinuation
  • 1998-10-14 EP EP98949066A patent/EP1023496A1/fr not_active Withdrawn
  • 1998-10-14 CN CN98811896A patent/CN1281520A/zh active Pending
  • 1998-10-14 AU AU95459/98A patent/AU9545998A/en not_active Abandoned
  • 1998-10-14 WO PCT/FR1998/002210 patent/WO1999020837A1/fr not_active Application Discontinuation
• 2000
  • 2000-04-17 NO NO20002002A patent/NO20002002L/no not_active Application Discontinuation

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