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
  • D21H21/06—Paper forming aids
  • D21H21/10—Retention agents or drainage improvers
• • 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
  • D21H17/21—Macromolecular organic compounds of natural origin; Derivatives thereof
  • D21H17/24—Polysaccharides
  • D21H17/28—Starch
  • D21H17/29—Starch cationic
• • 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
• • 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
  • 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
  • D21H17/55—Polyamides; Polyaminoamides; Polyester-amides
• • 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
• • 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 invention relates to a process for the production of paper, paperboard and cardboard with high dry strength by adding cationic, anionic and / or amphoteric starch as a dry strength agent to the paper stock and dewatering of the stock under sheet formation.
• graft copolymers prepared by grafting dextran, a naturally occurring polymer having a molecular weight of 20,000 to 50 million, with cationic monomers, eg diallyldimethylammonium chloride, mixtures of diallyldimethylammonium chloride and acrylamide or mixtures of acrylamide and basic methacrylates, such as dimethylaminoethyl methacrylate become.
• the graft polymerization is preferably carried out in the presence of a redox catalyst.
• a process for cationizing starch which comprises starch cooking in an alkaline medium in the presence of water-soluble quaternary ammonium polymers and an oxidizing agent.
• Suitable quaternary ammonium polymers include, inter alia, quaternized diallyldialkylaminopolymers or quaternized polyethylenimines.
• the oxidizing agent used for example, ammonium persulfate, hydrogen peroxide, sodium hypochlorite, ozone or tert-butyl hydroperoxide.
• the modified cationic starches which can be prepared in this way are added as a dry strength agent in the production of paper to the paper stock.
• the wastewater is burdened by a very high COD (chemical oxygen demand).
• a process for producing cationic starch which is used for surface sizing and coating of paper and paper products.
• an aqueous slurry of oxidized starch is digested together with a cationic polymer in a continuous digester.
• Suitable cationic polymers are condensates of epichlorohydrin and dimethylamine, polymers of diallyldimethylammonium chloride, quaternized reaction products of ethylene chloride and ammonia and quaternized polyethyleneimine.
• a process for producing a cationic starch which comprises heating a slurry of starch in water together with a polyalkyleneimine or polyalkylenepolyamine having a molecular weight of at least 50,000 at a temperature of about 70 to 110 ° C for about 0.5 to 5 hours ,
• the mixture contains from 0.5 to 40% by weight of polyalkyleneimine or polyalkylenepolyamine and from 99.5 to 60% by weight of starch.
• a polyethyleneimine having an average molecular weight of about 200,000 in dilute aqueous solution with potato starch is heated at a temperature of 90 ° C for 2 hours.
• the modified potato starch can be precipitated in a mixture of methanol and diethyl ether.
• the in the US-A-3,467,608 described reaction products of starch and polyethyleneimine or polyalkylenepolyamines are used as flocculants.
• the dry strength agent used is reaction products obtained by heating native potato starch with cationic polymers such as polymers containing vinylamine, N-vinylimidazoline or diallyl dimethyl ammonium units or polyethyleneimines in aqueous medium to temperatures above the gelatinization temperature of the starch in the absence of oxidizing agents, Polymerization initiators and alkali are available.
• From the US-A-4,880,497 and the US-A-4,978,427 discloses a process for producing high dry and wet strength paper comprising adding to the surface of the paper or to the stock prior to sheet formation a hydrolyzed copolymerization solidifying agent which is prepared by copolymerizing N-vinylformamide and ethylenically unsaturated monomers, such as For example, vinyl acetate, vinyl propionate or alkyl vinyl ethers and hydrolyzing from 30 to 100 mol% of the formyl groups of the copolymer to form amino groups is available.
• the hydrolyzed copolymers are used in amounts of 0.1 to 5 wt .-%, based on dry fibers.
• WO-A-96/13525 is a method for the cationic modification of starch by reacting starch with polymers containing amino and / or ammonium groups in aqueous medium at temperatures of 115 to 180 ° C under elevated pressure known, wherein at most 10 wt .-% of the starch used are degraded ,
• the invention is therefore based on the object to provide a process for the production of paper, paperboard and cardboard with high dry strength, wherein one achieves an increased retention of starch in the paper and thus lower COD values in paper machine wastewater and wherein also compared to the state
• the technique achieves an acceleration of the drainage rate.
• the object is achieved according to the invention by a process for the production of paper, paperboard and cardboard with high dry strength by adding starch obtainable by reaction of native, cationic, anionic and / or amphoteric starch with synthetic cationic polymers, as a dry strength agent to the paper stock and Dewatering the stock in the presence of sheet retention aids when employing polymers containing cationic vinylamine unit starch.
• the invention further provides the use of polymers containing vinylamine units as cationic polymeric retention aids for increasing the retention of dry strength agents from starch obtainable by reacting native, cationic, anionic and / or amphoteric starch with synthetic cationic polymers in the manufacture of paper , Cardboard and cardboard.
• Particularly preferred is the use of hydrolyzed homo- or copolymers of N-vinylformamide having a degree of hydrolysis of 1 to 100% and a K value of at least 30 (determined according to H. Fikentscher in aqueous solution at a polymer concentration of 0.5% by weight). %, a temperature of 25 ° C and a pH of 7) in amounts of 0.01 to 0.3 wt .-%, based on dry pulp, as a retention aid for cationic, anionic and / or amphoteric starch.
• Suitable pulps for the production of the pulps are all qualities customary for this purpose, for example wood pulp, bleached and unbleached pulp and pulps from all annual plants.
• Wood pulp includes, for example, groundwood, thermomechanical pulp (TMP), chemothermomechanical pulp (CTMP), pressure groundwood, semi-pulp, high yield pulp and refiner mechanical pulp (RMP).
• Suitable pulps are, for example, sulphate, sulphite and soda pulps.
• Suitable annual plants for the production of paper stocks For example, rice, wheat, sugarcane and kenaf. Waste paper is also used alone or in admixture with other fibers to make the pulps.
• Waste paper also belongs to waste paper, which gives rise to the white pitch due to the content of binders for coating and printing inks.
• the reason for the formation of so-called stickies is given by adhesives derived from self-adhesive labels and envelopes, as well as glues from the backsliding of books and so-called hotmelts.
• the fibers mentioned can be used alone or mixed with one another.
• the pulps of the type described above contain varying amounts of water-soluble and water-insoluble impurities.
• the impurities can be detected quantitatively, for example, with the aid of the COD value or else with the aid of the so-called cationic requirement.
• Cationic requirement is understood to be that amount of a cationic polymer which is necessary in order to bring a defined amount of the white water to the isoelectric point.
• Example 3 of the standardization DE-B-2 434 816 obtained condensation product obtainable by grafting a polyamidoamine of adipic acid and diethylenetriamine with ethyleneimine and subsequent crosslinking with a Polyethylenglykoldichlorhydrinether.
• the pulps containing impurities have, for example, COD values of 300 to 40,000, preferably 1,000 to 30,000 mg of oxygen per kg of the aqueous phase and a cationic requirement of more than 50 mg of said cationic polymer per liter of white water.
• Thickeners used are starches which are obtainable by reaction of native cationic, anionic and / or amphoteric starch with synthetic cationic polymers.
• Cationic, anionic and amphoteric starches are known and commercially available.
• Cationic starches are prepared, for example, by reacting native starches with quaternizing agents such as 2,3- (epoxypropyl) trimethylammonium chloride.
• quaternizing agents such as 2,3- (epoxypropyl) trimethylammonium chloride.
• starches having an amylopectin content of at least 99% by weight are preferred. Such starches can be obtained, for example, by starch fractionation of conventional native starches or by plant growth techniques from plants which produce substantially pure amylopectin starch. Starches having an amylopectin content of at least 95, preferably at least 99% by weight are available on the market. They are offered, for example, as waxy maize starch, waxy potato starch or waxy wheat starch. The native starches can be modified either alone or in admixture with cationic polymers.
• the modification of the native starches and of cationic, anionic and / amphoteric starch with synthetic cationic polymers is carried out by known methods by heating starches in an aqueous medium in the presence of cationic polymers at temperatures above the gelatinization temperature of the starches. Methods of this type are, for example, from the references cited in the prior art EP-B-0 282 761 and the WO-A-96/13525 known.
• all synthetic polymers which contain amino and / or ammnium groups are suitable. These compounds are referred to below as cationic polymers.
• Suitable cationic polymers are, for example, homopolymers and copolymers containing vinylamine units.
• Polymers of this type are prepared by known processes by polymerizing N-vinylcarboxamides of the formula in which R and R 1 are identical or different and are H or C 1 - to C 6 -alkyl, alone or in the presence of other monomers copolymerizable therewith and hydrolysis of the resulting polymers with acids or bases with elimination of the grouping and forming units of the formula in which R has the meaning given in formula (I).
• Suitable as comonomers are 2) unsaturated amides such as, for example, acrylamide, methacrylamide and N-alkyl mono- and diamides with alkyl radicals of 1 to 6 carbon atoms, such as, for example, N-methylacrylamide, N, N-dimethylacrylamide, N-methylmethacrylamide, N-ethylacrylamide, N-propylacrylamide and tert-butylacrylamide and basic (meth) acrylamides, e.g.
• unsaturated amides such as, for example, acrylamide, methacrylamide and N-alkyl mono- and diamides with alkyl radicals of 1 to 6 carbon atoms, such as, for example, N-methylacrylamide, N, N-dimethylacrylamide, N-methylmethacrylamide, N-ethylacrylamide, N-propylacrylamide and tert-butylacrylamide and basic (meth) acrylamides, e.g.
• N-vinylpyrrolidone N-vinylcaprolactam
• acrylonitrile methacrylonitrile
• N-vinylimidazole and substituted N-vinylimidazoles
• N-vinyl-2-methylimidazole N-vinyl-4-methylimidazole
• N-vinyl-5-methylimidazole N-vinyl-2-ethylimidazole
• N-vinylimidazolines e.g. Vinylimidazoline, N-vinyl-2-methylimidazoline, and N-vinyl-2-ethylimidazoline.
• N-vinylimidazoles and N-vinylimidazolines are also used, except in the form of the free bases, in neutralized or quaternized form with mineral acids or organic acids, the quaternization preferably being carried out with dimethyl sulfate, diethyl sulfate, methyl chloride or benzyl chloride.
• sulfo-containing monomers such as vinyl sulfonic acid, Allylsulfonic acid, methallylsulfonic acid, styrenesulfonic acid or 3-sulfopropyl acrylate in question.
• basic comonomers 2 e.g. Basic acrylic esters and amides can often be dispensed with hydrolysis of the N-vinylcarboxamides.
• the copolymers include terpolymers and those polymers which additionally contain at least one further monomer in copolymerized form.
• hydrolysis of the ester groups occurs to form vinyl alcohol units.
• Polymerized acrylonitrile is also chemically altered on hydrolysis, e.g. Amide, cyclic amidine and / or carboxyl groups are formed.
• the hydrolyzed poly-N-vinylformamides may optionally contain up to 20 mole% of amidine structures formed by reaction of formic acid with two adjacent amino groups in the polyvinylamine or by reaction of a formamide group with an adjacent amino group.
• Suitable cationic polymers furthermore include ethyleneimine units in copolymerized form.
• these are polyethyleneimines obtainable by polymerizing ethyleneimine in the presence of acidic catalysts such as ammonium bisulfate, hydrochloric acid or chlorinated hydrocarbons such as methyl chloride, ethylene chloride, carbon tetrachloride or chloroform.
• acidic catalysts such as ammonium bisulfate, hydrochloric acid or chlorinated hydrocarbons such as methyl chloride, ethylene chloride, carbon tetrachloride or chloroform.
• Such polyethyleneimines have, for example, in 50 wt .-% aqueous solution has a viscosity of 500 to 33,000, preferably 1,000 to 31,000 mPa ⁇ s (measured according to Brookfield at 20 ° C and 20 rpm).
• the polymers of this group also include polyamidoamines grafted with ethyleneimine, which may optionally be crosslinked by reaction with an at least bifunctional crosslinker.
• Products of this type are prepared, for example, by condensing a dicarboxylic acid such as adipic acid with a polyalkylenepolyamine such as diethylenetriamine or triethylenetetramine, optionally grafting with ethyleneimine and reaction with an at least bifunctional crosslinker, eg bischlorohydrin ether of polyalkylene glycols, cf. US-A-4,144,123 and U.S.-A-3,642,572 ,
• polymers of this type are known.
• polymers of diallyldimethylammonium chloride are meant primarily homopolymers and copolymers with acrylamide and / or methacrylamide.
• the copolymerization can be carried out in any monomer ratio.
• the K value of the homo- and copolymers of diallyldimethylammonium chloride is at least 30, preferably 95 to 180.
• the substituent X - in the formulas (IV) and (V) can in principle be any desired acid radical of an inorganic and an organic acid.
• the monomers of formula (IV) are obtained by neutralizing the free bases, ie 1-vinyl-2-imidazolines, with the equivalent amount of an acid.
• the vinylimidazolines can also be neutralized with trichloroacetic acid, benzenesulfonic acid or toluenesulfonic acid, for example.
• salts of 1-vinyl-2-imidazolines quaternized 1-vinyl-2-imidazolines are also suitable.
• quaternizing agents are, for example, C 1 -C 18 -alkyl chlorides or bromides, benzyl chloride or bromide, epichlorohydrin, dimethyl sulfate and diethyl sulfate.
• epichlorohydrin benzyl chloride, dimethyl sulfate and methyl chloride.
• the compounds of the formulas (IV) or (V) are preferably polymerized in an aqueous medium.
• Suitable cationic polymers are copolymers of 1 to 99 mol%, preferably 30 to 70 mol% of acrylamide and / or methacrylamide and 99 to 1 mol%, preferably 70 to 30 mol% of dialkylaminoalkyl acrylates and / or methacrylates , eg Copolymers of acrylamide and N, N-dimethylaminoethyl acrylate or N, N-diethylaminoethyl acrylate.
• Basic acrylates are preferably present in acids neutralized or quaternized form. The quaternization can be carried out, for example, with methyl chloride or with dimethyl sulfate.
• the cationic polymers have K values of 30 to 300, preferably 100 to 180 (determined according to H. Fikentscher in 5% strength aqueous sodium chloride solution at 25 ° C. and a polymer concentration of 0.5% by weight). At a pH of 4.5, they have a charge density of at least 4 meq / g polyelectrolyte.
• the basic acrylamides and methacrylamides are also preferably present in acids neutralized or quaternized form.
• N-trimethylammoniumethylacrylamide chloride N-trimethylammoniumethylmethacrylamidechloride, trimethylammoniumethylacrylamidemethosulphate, trimethylammoniumethylmethacrylamidemethosulphate, N-ethyldimethylammoniumethylacrylamideethosulphate, N-ethyldimethylammoniumethylmethacrylamidethosulphate, trimethylammoniumpropylacrylamidechloride, trimethylammoniopropylmethacrylamidechloride, trimethylammoniopropylacrylamidemethosulphate, trimethylammoniumpropylmethacrylamidemethosulphate and N-ethyldimethylammoniumpropylacrylamidethosulphate.
• Preferred is trimethylammonium propylmethacrylamide chloride.
• cationic polymers are also polyallylamines into consideration.
• Polymers of this type are obtained by homopolymerization of allylamine, preferably in acids neutralized or in quaternized form or by copolymerizing allylamine with other monoethylenically unsaturated monomers, corresponding to the previously described copolymers with N-vinylcarboxamides.
• an aqueous suspension of at least one kind of starch with one or more of the cationic polymers is heated to temperatures above the gelatinization temperature of the native or modified starches, e.g. to temperatures of 90 to 180 ° C, preferably 115 to 145 ° C.
• the reaction is carried out under elevated pressure, the reaction being carried out in such a way that at most 10% by weight of the starch undergoes a molecular weight reduction.
• Aqueous slurries of starch contain, for example, per 100 parts by weight of water 0.1 to 10, preferably 2 to 6 parts by weight of starch.
• Suitable cationic polymers are preferably partially or completely hydrolyzed homo- or copolymers of N-vinylformamide, polyethyleneimines, ethyleneimine-grafted and crosslinked polyamidoamines and / or polydiallyldimethylammonium chlorides.
• starch digestion is meant the conversion of the solid starch granules into a water-soluble form whereby superstructures (helix formation, intramolecular hydrogen bonds, etc.) are abolished without degradation of the starch-building amylose and / or amylopectin moieties to oligosaccharides or glucose.
• the aqueous starch suspensions containing a cationic polymer dissolved are heated in the reaction to temperatures above the gelatinization temperature of the starches.
• the starch used is digested to at least 90, preferably to> 95 wt .-% and modified with the cationic polymer.
• the strength is clearly solved.
• the reaction is preferably carried out at elevated pressure. This is usually the pressure which the reaction medium has in the temperature range above the boiling points of water, e.g. developed at 115 to 180 ° C. It is for example at 1 to 10, preferably 1.2 to 7.9 bar.
• the reaction mixture is subjected to shear. If the reaction is carried out in a stirred autoclave, stirring the reaction mixture, for example, with 100 to 2,000, preferably 200 to 1,000 revolutions / minute.
• the reaction can be carried out in virtually all apparatuses in which starch is digested in the art, e.g. in a jet cooker.
• the residence times of the reaction mixture at the above-mentioned temperatures of 115 to 180 ° C, for example, 0.1 seconds to 1 hour and are preferably in the range of 0.5 seconds to 30 minutes.
• At least 90% of the starch used is digested and modified.
• the native starch types may also be subjected to a pretreatment, e.g. oxidatively, hydrolytically or enzymatically degraded or chemically modified.
• a pretreatment e.g. oxidatively, hydrolytically or enzymatically degraded or chemically modified.
• wax strengths such as waxy potato starch and waxy maize starch are of particular interest.
• the reaction products thus obtainable have, for example, at a solids concentration of 3.5% by weight, a viscosity of 50 to 10,000, preferably 80 to 4,000 mPa.s, measured in a Brookfield viscometer at 20 revolutions / minute and a temperature of 20 ° C. ,
• the pH of the reaction mixtures is, for example, in the range of 2.0 to 9.0, preferably 2.5 to 8.
• the starches modified with cationic polymers are used as dry strength agents in the amount of, for example, from 0.5 to 10, preferably from 0.5 to 3.5, and particularly preferably from 1.2 to 2.5,% by weight, based on dry paper stock , added.
• the paper stock is additionally metered with a cationic vinylamine units-containing polymer as retention aid for the above-described starches which have been modified with a polymer.
• a cationic vinylamine units-containing polymer as retention aid for the above-described starches which have been modified with a polymer.
• the retention agent Preferably, first the dry strength and then the retention agent.
• Such mixtures can be prepared, for example, by adding to the disrupted starch retention aid, after cooling to 50 ° C or below.
• the retention aid may also be added to the stock before the addition of the modified starch. This order of addition makes use of, for example, the processing of paper stocks which have a high level of impurities.
• the dry strength agent used is preferably a cationic starch which is obtainable by reacting 100 parts by weight of a native, cationic, anionic and / or amphoteric starch with 0.5 to 10 parts by weight of a polymer comprising vinylamine units with a Value of 60 to 150 at temperatures above the gelatinization temperature of the starch.
• a polymer comprising vinylamine units with a Value of 60 to 150 at temperatures above the gelatinization temperature of the starch.
• polymers containing vinylamine units e.g. hydrolyzed homopolymers and copolymers of N-vinylformamide having a degree of hydrolysis of at least 60% are preferably used. These homopolymers and copolymers are added not only to the cationization of starch but also to the paper stock as a retention aid for the cationically modified starches.
• the hydrolyzed homo- and copolymers of N-vinylformamide considered as retention aids for starch may generally have a degree of hydrolysis of from 1 to 100%.
• the starches to be used as dry strength agents are used in amounts of from 0.5 to 10, preferably from 1 to 5,% by weight, based on dry paper stock.
• the dewatering of the paper stock is carried out according to the invention always in the presence of at least one polymers containing vinylamine units as a retention aid for starch, wherein the retention agents are used in amounts of 0.01 to 0.3 wt .-%, based on dry paper pulp. This results in a considerably improved retention of the starch and an increase in the dewatering rate of the paper stock on the paper machine compared to the known methods.
• cationic polymers used are a mixture of a polymer comprising vinylamine units, for example polyvinylamine and a cationic polyacrylamide, for example a copolymer of acrylamide and dimethylaminoethyl acrylate methochloride, and bentonite after the shear stage.
• cationic polymers as retention aids for starches are mixtures of polymers containing vinylamine units and crosslinked polyamidoamines grafted with ethyleneimine and mixtures of polymers containing vinylamine units with polydiallyldimethylammonium chlorides.
• Hydrolyzed polyvinylformamide having a K value of 90 and a degree of hydrolysis of 75 mol%.
• Hydrolyzed polyvinylformamide having a K value of 90 and a degree of hydrolysis of 50 mol%.
• a paper stock having a stock consistency of 7.6 g / l was prepared from an open finished commercial wave raw material based on recovered paper.
• the pH of the stock was 8.0.
• the amounts of solidifier 1 and the polymers 1-4 indicated in Table 1 were added in succession to samples of this paper stock. After mixing the paper stock with the additives, it was filtered off with suction and the starch content was determined from the absorbance measurement of the starch-iodine complex. The results obtained are shown in Table 1.
• Another part of the paper stock was dewatered after metering solidifier 1 and the polymers indicated in Table 1 in each case with the aid of a Schopper-Riegler apparatus. The dewatering time was determined according to DIN ISO 5267 for 700 ml filtrate. The results are given in Table 1, Example 1 being a comparison.
• Example 1 was repeated with the exception that only solidifier 1 in an amount of 2%, based on dry pulp, metered to the pulp.
• Starch content of the filtrate and the dewatering time are shown in Table 1.
• Table 1 example Additive to paper stock, based on dry stock Starch content in the filtrate [mg / l] Drainage time [sec / 700 ml] 1 (comparison) 2% strength agent 1 + 0.08% polymer 1 38 92 2 2% strength agent 1 + 0.08% polymer 2 34 49 3 2% strength agent 1 + 0.08% polymer 3 30 55 4 2% strength agent 1 + 0.08% polymer 4 30 67 Comparative example 1 2% strength agent 1 50 136
• Example 5 was repeated with the changes shown in Table 2. The results are shown in Table 2.
• Table 2 example Additive to paper stock, based on dry stock COD value [mgO 2 / l] Strong retention (enzymatic method) Drainage time [sec / 500 ml] 5 2% strength agent 2 + 0.08% polymer 3 134 93 20 Comparative example 2 2% strength agent 1 313 43 72 3 2% commercial cationic starch DS 0.035 162 92 78 4 - 135 68
• Example 6 was repeated with the changes shown in Table 3, working in the absence of Polymer 3 (Comparative Example 5).
• commercial cationic starch (Comparative Example 6) was used and found to be zero (Comparative Example 7).
• Table 3 example Additive to paper stock, based on dry stock Dry breaking length [m] Dry burst pressure [kPa] CMT [N] 6 2% strength agent 1 + 0.08% polymer 3 4433 296 209 Comparative example 5 2% strength agent 1 4353 278 190 6 2% commercial cationic starch DS 0.035 4488 296 194 7 - 3757 241 160

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• 1997
  • 1997-04-04 DE DE19713755A patent/DE19713755A1/de not_active Withdrawn
• 1998
  • 1998-03-26 PT PT98921399T patent/PT972110E/pt unknown
  • 1998-03-26 NZ NZ338029A patent/NZ338029A/xx unknown
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  • 1998-03-26 AT AT98921399T patent/ATE268410T1/de active
  • 1998-03-26 DE DE59811513T patent/DE59811513D1/de not_active Expired - Lifetime
  • 1998-03-26 CA CA2284931A patent/CA2284931C/en not_active Expired - Fee Related
  • 1998-03-26 JP JP54231698A patent/JP2001518988A/ja not_active Withdrawn
  • 1998-03-26 KR KR1019997009080A patent/KR20010006002A/ko not_active Withdrawn
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  • 1998-04-03 ZA ZA982842A patent/ZA982842B/xx unknown

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