EP0193111B1 - Process for producing paper with a high dry strength - Google Patents

Process for producing paper with a high dry strength Download PDF

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Publication number
EP0193111B1
EP0193111B1 EP86102199A EP86102199A EP0193111B1 EP 0193111 B1 EP0193111 B1 EP 0193111B1 EP 86102199 A EP86102199 A EP 86102199A EP 86102199 A EP86102199 A EP 86102199A EP 0193111 B1 EP0193111 B1 EP 0193111B1
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EP
European Patent Office
Prior art keywords
weight
component
copolymer
paper
ethylenically unsaturated
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EP86102199A
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German (de)
French (fr)
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EP0193111A3 (en
EP0193111A2 (en
Inventor
Sigberg Dr. Pfohl
Heinrich Dr. Hartmann
Guenter Dr. Frey
Michael Dr. Kroener
Klaus Guth
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BASF SE
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BASF SE
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Priority to AT86102199T priority Critical patent/ATE48667T1/en
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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
    • 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
    • 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
    • D21H17/375—Poly(meth)acrylamide
    • 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
    • D21H17/34—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

Definitions

  • the sheet is then formed from the resulting pulp with drying and dried.
  • An essential aspect of this process is that a substantial amount of binder latex (2) is used, namely 10 to 50% by weight of binder solids excluding other polymeric additives.
  • DE-B-11 76 990 discloses a process for increasing the dry strength of fibrous webs, in which the pulp pulp is mixed with an aqueous dispersion of a nonionic dispersant and one or more linear polymers of vinyl compounds containing carbonxyl groups and / or salts thereof, is treated in the presence of one or more polycationic nitrogen compounds. Preferably 10 to 50% by weight of carboxyl group-containing resin is used.
  • a process for the production of paper with high dry strength in which a water-soluble cationic polymer, for. B. polyethyleneimine, and then a water-soluble anionic polymer, for. B. adds a hydrolyzed polyacrylamide and dewatered the paper stock on a paper machine with sheet formation.
  • the anionic polymers contain up to 30 mol% of acrylic acid copolymerized. Since the dry strength agent is already added to the paper stock, a surface application is no longer necessary, but after a certain time the anionic polyacrylamides lead to poorer dewatering of the stock suspension and to a sticking of the felts of the paper machine.
  • the present invention has for its object to provide a process for the production of paper with high dry strength and the lowest possible wet strength, in which compared to the process known from CA-PS 1 110 019 papers with improved dry strength and in the case of use bleached fabrics get papers with higher whiteness.
  • the cationic polymers are added to the fabric in order to transfer the negatively charged cellulose fibers.
  • the following classes of compounds are suitable as water-soluble cationic polymers (A): polyethyleneimines which, in 10% strength aqueous solution at a pH of 7, have a viscosity in the range from 5 to 100, preferably 10 to 40 mPas (measured at 20 ° C, rotational viscometer, 20 rpm).
  • the polymers can be neutralized with organic acids such as formic acid, acetic acid or propionic acid or with inorganic acids such as hydrochloric acid, sulfuric acid or phosphoric acid.
  • component (A) Partially to fully hydrolyzed homo- and copolymers of N-vinylformamide are also suitable as component (A).
  • the degree of hydrolysis of the N-vinylformamide in these polymers is at least 30 mol% and is preferably in the range from 50 to 100 mol%. For example, if one starts from a homopolymer of N-vinylformamide and hydrolyzes 100%, a polyvinylamine is obtained.
  • Copolymers of N-vinylformamide with other monomers e.g. B. vinyl acetate, acrylonitrile, methacrylniytil, acrylamide and methacrylamide can also be hydrolyzed by the action of acids or bases.
  • the degree of hydrolysis stated above always relates to the N-vinylformamide content of the copolymer in the copolymers of N-vinylformamide.
  • Saponification of copolymers of N-vinylformamide and vinyl acetate gives polymers which, in addition to the units of the monomers on which these polymers are based, also have units of vinylamine and vinyl alcohol.
  • Suitable homopolymers of N-vinylformamide and copolymers of N-vinylformamide with other ethylenically unsaturated monomers have a K value (according to H. Fikentscher) from 50 to 250 and preferably from 100 to 150.
  • the K value of the unsaponified and the saponified "N -Vinylformamidpolymerisate agrees within the limits of error.
  • component (A) are homopolymers and copolymers of N-vinylimidazole and N-vinylimidazoline and their derivatives.
  • the copolymers contain at least 30% by weight of N-vinylimidazole or N-vinylimidazoline or their derivatives in copolymerized form.
  • suitable comonomers are acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, vinyl propionate, vinyl lactate and vinyl C 1 -C 4 -alkyl ethers (e.g. vinyl methyl ether or vinyl ethyl ether).
  • suitable derivatives of N-vinylimidazole and N-vinylimidazoline are, for example, the C 1 - to C 3 -alkyl-substituted or phenyl-substituted compounds.
  • the polymers of N-vinylimidazole and N-vinylimidazoline have K values (determined according to H. Fikentscher) from 50 to 250 and preferably 100 to 150.
  • water-soluble cationic polymers are polyamidoamines which are crosslinked with epichlorohydrin. Suitable products of this type are known, for example, from US Pat. No. 2,926,116. They are made by using a dicarboxylic acid such as adipic acid with a polyamine e.g. B. condensed diethylene triamine or tetraethylene pentamine and the resulting resin cross-linked with epichlorohydrin to the extent that water-soluble reaction products are still obtained. These polymers have a viscosity of 20 to 200 mPas in a 10% by weight aqueous solution at a temperature of 20 ° C. (measured with a rotary viscometer at 20 rpm).
  • This group of cationic polymers also includes polyamidoamines grafted with ethyleneimine, which are crosslinked with epichlorohydrin or, according to DE-PS2434816, with reaction products which are reacted with at least equivalent amounts by reacting the terminal OH groups of polyalkylene oxides with 8 to 100 alkylene oxide units (preferably polyethylene oxides) Epichlorohydrin can be obtained.
  • the viscosity of the water-soluble products grafted and crosslinked with ethyleneimine measured with a rotary viscometer at 20 rpm and 20 ° C., is 300 to 2500 mPas.
  • cationic polymers (A) are homopolymers of diallyldi-C 1 -C 3 -alkylammonium compounds and diallyl mono-C i -C 3 -amines. Either the free bases or the halides, in particular the chlorides, can be used. Homopolymers of diallyldimethylammonium chloride and diallyldiethylammonium chloride are particularly suitable.
  • the polymers of this class of substances have K values (measured according to H. Fikentscher) from 50 to 150, preferably from 100 to 150.
  • polyethyleneimines polyvinylamines which are prepared by hydrolysis of homopolymers of N-vinylformamide or of copolymers of N-vinylformamide and vinyl acetate, acrylamide or acrylonitrile, the degree of hydrolysis, in each case based on polymerized N- Vinylformamide, at least 50 to 100 mol.%, And polyvinylimidazole.
  • 0.01 to 3 preferably 0.1 to 0.5% by weight of a cationic compound (A) is used. It is of course also possible to have one Use mixture of 2 or 3 different cationic compounds in the process according to the invention. If the cationic compounds (A) are strongly basic, they can be used in a form partially or completely neutralized with an acid. The pH of these solutions is then 6 to 8, preferably 7 to 7.5.
  • the water-soluble anionic polymers - component (B) - are, for example, homopolymers of ethylenically unsaturated C 3 to C 5 carboxylic acids. These include, for example, homopolymers of acrylic acid, methacrylic acid, maleic acid, hydrolyzed homopolymers of maleic anhydride and itanconic acid.
  • the ethylenically unsaturated carboxylic acids mentioned can be copolymerized with other monomers.
  • Suitable as component (B) are copolymers of (a) 35 to 99% by weight of ethylenically unsaturated C 3 to C s carboxylic acids, (b) 65 to 1% by weight of an amide, nitrile and / or an ester of an ethylenic unsaturated C 3 to C 5 carboxylic acid and (c) 0 to 15% by weight of styrene or a C 1 to C 4 alkyl vinyl ether.
  • the copolymers preferably contain (a) 40 to 70% by weight of an ethylenically unsaturated C 3 to C 5 carboxylic acid, (b) 60 to 30% by weight of an amide, nitrile and / or an ester of an ethylenically unsaturated carboxylic acid and (c ) 0 to 15 wt .-% styrene or a C 1 - to C 4 alkyl vinyl ether.
  • the sum of the percentages by weight in the copolymer is 100 in each case.
  • the esters of ethylenically unsaturated C s to C s carboxylic acids of component (b) of the copolymers are preferably derived from alcohols having 1 to 4 carbon atoms.
  • component (B) Particularly preferred as component (B) are terpolymers made of (a) 40 to 70% by weight of acrylic acid, (b 1 ) 10 to 50% by weight of acrylamide and (b 2 ) 10 to 50% by weight of acrylonitrile.
  • the anionic water-soluble polymers (B) have a K value (according to H. Fikentscher) from 50 to 250 and preferably from 100 to 150.
  • the K value for the copolymers is determined at 20 ° C. in 5% strength aqueous sodium chloride solution and one Polymer concentration of 0.5% by weight.
  • the pH when determining the K values is 7.
  • the anionic component (B) is used in an amount of 0.05 to 3, preferably 0.1 to 1.0,% by weight, based on the dry fiber material.
  • the weight ratio of components (A) to (B) is 1: 0.5 to 10 and is preferably in the range from 1: 2 to 4.
  • the anionic component can be neutralized in the form of the free acids or partially or completely with bases Form apply. It is only important here that the partially or completely neutralized polymers are soluble in water.
  • bases are alkali and alkaline earths as well as ammonia and amines, for. B. sodium hydroxide solution, potassium hydroxide solution, calcium hydroxide, barium hydroxide, ammonia, trimethylamine, ethanolamine and morpholine.
  • All known paper and cardboard qualities can be produced by the method according to the invention, e.g. B.
  • the papers can be made from a variety of different types of fiber materials, for example from sulfite or sulfate pulp in the bleached or unbleached state, wood, ground or waste paper.
  • the papermaking takes place in the pH range from 4.5 to 8, preferably at pH values from 6 to 7.
  • sulfuric acid or aluminum sulfate can be used.
  • the process according to the invention is preferably carried out in the presence of only small amounts of aluminum sulfate.
  • the cationic component (A) which is responsible for the recharge of the cellulose fibers, is first added to the substance.
  • Component (A) is very quickly fixed on the fibers.
  • a certain dwell time e.g. B. after 1 to 10 minutes, one or more compounds according to (B) are added to the substance, the mixture is homogenized and, if appropriate, other conventional auxiliaries are added, such as retention aids, drainage agents, fillers, sizing agents, optical brighteners, defoamers, dyes, starch, Polyvinyl alcohol, carboxymethyl cellulose or mannogalactane - and then forms the sheet on a paper machine.
  • other conventional auxiliaries such as retention aids, drainage agents, fillers, sizing agents, optical brighteners, defoamers, dyes, starch, Polyvinyl alcohol, carboxymethyl cellulose or mannogalactane - and then forms the sheet on a paper machine.
  • the anionic components (B) when using the anionic components (B), an improvement in the retention of fibers and fillers and also conventional auxiliaries, such as starch or carboxymethyl cellulose, is observed in all paper grades.
  • Another advantage of using the anionic compounds (B) is an improvement in the dewatering of the stock suspension and the fact that the felts of the paper machine do not stick together even over a long period of time. Because of these advantageous properties, the method according to the invention is of particular importance for the production of paper from waste paper. In the production of bleached paper grades, there is a significantly higher whiteness of the paper compared to the methods of the prior art.
  • the parts given in the following examples are parts by weight, the percentages relate to the weight of the substances.
  • the sheets were produced in a Rapid-Köthen laboratory sheet former.
  • the dry tear length was determined in accordance with DIN 53 112, sheet 1 and the wet tear length in accordance with DIN 53 113, sheet 2.
  • the whiteness of the paper sheets was determined with the aid of a reflection photometer (Elrefo device) in accordance with DIN 53 145.
  • the CMT value was determined in accordance with DIN 53 143, the dry burst pressure was determined in accordance with DIN 53 141.
  • a 0.5% aqueous stock suspension was prepared from 100% mixed waste paper.
  • the pH of the suspension was 7.2, the degree of grinding of the material was 50 ° Schopper-Riegler (SR).
  • the stock suspension was then divided into five equal parts and processed into sheets with a mass per unit area of 120 g / m 2 under the following conditions:
  • a sheet was formed from the stock suspension without further additives.
  • a 70% bleached wood pulp and 30% bleached beech sulfite pulp were used to produce a 0.5% aqueous suspension which had a pH of 7.5 and a freeness of 45 ° SR.
  • the suspension was divided into five equal parts and processed into sheets with a mass per unit area of 100 g / m 2 under the following conditions:
  • the stock suspension described above was processed directly into a sheet.
  • a 70% bleached pine sulphate pulp and 30% bleached birch sulphate pulp were used to produce a 0.5% aqueous pulp suspension which had a pH of 6.5 and a freeness of 30 ° SR. This suspension was divided into 5 equal parts and processed into sheets with a mass per unit area of 80 g / m 2 as described below:
  • the stock suspension was dewatered without any further addition, with leaf formation.
  • a resin was added, based on dry fiber stock, which was obtained by condensing adipic acid with diethylenetriamine and crosslinking the polyamidoamine with epichlorohydrin according to Example 1 of US Pat. No. 2,926,116. After a residence time of 2 minutes, 0.5% of a copolymer of 80% acrylamide, 10% acrylonitrile and 10% acrylic acid was added. The copolymer was in the form of the sodium salt and had a K value of 130. After an exposure time of 2 minutes, the stock suspension was dewatered to form sheets.
  • aqueous pulp suspension 0.25% of a polyvinylamine with a K value of 140 was added, based on dry pulp and, after an exposure time of 2 minutes, 0.5%, based on dry pulp, of same polymer from 80% acrylamide, 10% acrylonitrile and 10% acrylic acid according to b). After an exposure time of 2 minutes, the stock suspension was dewatered with the formation of leaves.
  • a polyvinylamine with a K value of 140 was added, based on dry pulp and, after an exposure time of 2 minutes, 0.5%, based on dry pulp, of same polymer from 80% acrylamide, 10% acrylonitrile and 10% acrylic acid according to b). After an exposure time of 2 minutes, the stock suspension was dewatered with the formation of leaves.
  • a 0.5% aqueous suspension was prepared from a mixed waste paper, which had a pH of 7.5 and a freeness of 45 ° SR. The stock suspension was then divided into five equal parts and processed into sheets with a basis weight of 120 g / m 2 under the conditions specified below.
  • a sheet was formed from the stock suspension without further addition.

Abstract

1. A process for making paper having a high dry strength by adding (A) a water-soluble cationic polymer and (B) a water-soluble anionic polymer in succession to the paper stock and draining the latter with sheet formation by using component (A) in an amount of from 0.01 to 3% by weight and component (B) in an amount of from 0.05 to 3% by weight, based on dry paper stock in each case, component (B) being a homopolymer of an ethylenically unsaturated C3 -C5 -carboxylic acid or a copolymer having a K value of from 50 to 250 (determined according to H. Fikentscher at 20 degrees C in 5% strength aqueous sodium chloride solution and at a polymer concentration of 0.5% by weight) and having been formed from (a) from 35 to 99% by weight of an ethylenically unsaturated C3 -C5 -carboxylic acid, (b) from 65 to 1% by weight of an amide, nitrile and/or ester of an ethylenically unsaturated C3 -C5 -carboxylic acid and (c) from 0 to 15% by weight of styrene or of a C1 -C4 -alkyl vinyl ether, the sum of the percentages by weight in the copolymer being 100 in each case.

Description

Zur Herstellung von Papier mit hoher Trockenfestigkeit und niedriger Naßfestigkeit ist es bekannt, auf die Oberfläche von Papier verdünnte wäßrige Lösungen von synthetischen Polymerisaten, die als Trockenverfestigungsmittel wirken, aufzutragen und das so imprägnierte Papier zu trocknen. Die Mengen an Trockenverfestigungsmittel, die möglichst gleichmäßig auf die Oberfläche des Papiers aufgebracht werden sollen, betragen in der Regel 0,1 bis 4 Gew.%, bezogen auf trockenes Papier. Geeignete Trockenverfestigungsmittel sind beispielsweise aus der DE-PS 27 41 753 und den EP-Patentschriften 13969 und 36993 bekannt. Da die Trockenverfestigungsmittel auf einer verdünnten wäßrigen Polymerlösung aufgetragen werden - im allgemeinen beträgt die Polymerkonzentration der Präparationslösungen 1 bis 10 Gew.% - ist beim folgenden Trocknungsprozeß eine beträchtliche Menge an Wasser zu verdampfen. Der Trocknungsschritt ist daher sehr energieaufwendig. Die Kapazität der üblichen Trocknungseinrichtungen an Papiermaschinen ist aber nicht so groß, daß man bei der maximal möglichen Produktionsgeschwindigkeit der Papiermaschinen durch Auftrag von wäßrigen Polymerlösungen Papiere mit verbesserter Trockenfestigkeit herstellen kann. Die Produktionsgeschwindigkeit der Papiermaschinen muß vielmehr zurückgenommen werden, damit das Papier in ausreichendem Maße getrocknet wird.For the production of paper with high dry strength and low wet strength, it is known to apply to the surface of paper dilute aqueous solutions of synthetic polymers, which act as dry strength agents, and to dry the paper thus impregnated. The amounts of dry strength agent that are to be applied as uniformly as possible to the surface of the paper are generally 0.1 to 4% by weight, based on dry paper. Suitable dry strength agents are known, for example, from DE-PS 27 41 753 and EP Patents 13969 and 36993. Since the dry strength agents are applied to a dilute aqueous polymer solution - in general the polymer concentration of the preparation solutions is 1 to 10% by weight - a considerable amount of water must be evaporated in the following drying process. The drying step is therefore very energy intensive. However, the capacity of the usual drying devices on paper machines is not so great that, with the maximum possible production speed of the paper machines, papers with improved dry strength can be produced by applying aqueous polymer solutions. The production speed of the paper machines must rather be reduced so that the paper is dried to a sufficient extent.

Eine Möglichkeit, die Produktionsgeschwindigkeit der Papierherstellung zu erhöhen, besteht zwar darin, höher konzentrierte wäßrige Polymerlösungen auf die Oberfläche des Papiers aufzutragen. In diesem Fall enthält das Papier jedoch auch eine höhere Menge an Polymerisat, die aber nicht zu einer weiteren Verbesserung der Eigenschaften des Papiers führt. Dieser Weg zur Herstellung von Papier mit hoher Trockenfestigkeit ist daher schon aus wirtschaftlichen Gründen nicht gangbar. Eine andere Möglichkeit ist darin zu sehen, die wäßrigen Polymerlösungen zu verschäumen und dann den Schaum auf die Oberfläche des Papiers aufzutragen und den üblichen Trocknungsschritt anzuschließen. Diese Verfahrensweise erfordert aber einen zusätzlichen Arbeitsgang und führt zu Papieren, die das Polymerisat nicht homogen genug verteilt enthalten und die somit nicht die optimale, mit einer bestimmten Polymerisatmenge erreichbare Festigkeit besitzen.One way to increase the production speed of papermaking is to apply more concentrated aqueous polymer solutions to the surface of the paper. In this case, however, the paper also contains a higher amount of polymer, but this does not lead to a further improvement in the properties of the paper. This way of producing paper with high dry strength is therefore not feasible for economic reasons alone. Another possibility is to foam the aqueous polymer solutions and then apply the foam to the surface of the paper and to follow the usual drying step. However, this procedure requires an additional operation and leads to papers which do not contain the polymer distributed homogeneously enough and which therefore do not have the optimum strength which can be achieved with a certain amount of polymer.

Aus der DE-A-28 43 612 ist ein Verfahren zur Herstellung von Papier nach dem Naßlegeverfahren bekannt, bei dem man wenigstens 3 polymere Zusatzstoffe in der folgenden Reihenfolge einem Papierstoff zusetzt :

  • (1) eine wäßrige Lösung oder Dispersion eines polykationischen wasserlöslichen oder in Wasser dispergierbaren quatemären Salzes eines Polymerisats,
  • (2) einen Binderlatex und
  • (3) eine wäßrige Lösung eines polyanionischen hydrophilen wasserlöslichen Polymerisats, wie beispielsweise Acrylsäurepolymerisate.
DE-A-28 43 612 discloses a process for the production of paper by the wet-laying process, in which at least 3 polymeric additives are added to a paper stock in the following order:
  • (1) an aqueous solution or dispersion of a polycationic water-soluble or water-dispersible quaternary salt of a polymer,
  • (2) a binder latex and
  • (3) an aqueous solution of a polyanionic hydrophilic water-soluble polymer, such as, for example, acrylic acid polymers.

Aus dem so erhaltenen Papierstoff wird anschließend unter Entwässerung das Blatt gebildet und getrocknet. Wesentlicher Gesichtspunkt bei diesem Verfahren ist, daß man eine betächtliche Menge an Binderlatex (2) einsetzt, nämlich 10 bis 50 Gew.% an Binderfeststoffen ausschließlich anderer polymerer Zusatzstoffe.The sheet is then formed from the resulting pulp with drying and dried. An essential aspect of this process is that a substantial amount of binder latex (2) is used, namely 10 to 50% by weight of binder solids excluding other polymeric additives.

Aus der DE-B-11 76 990 ist ein Verfahren zur Erhöhung der Trockenfestigkeit von Faserstoffbahnen bekannt, bei dem der Faserstoffbrei mit einer wäßrigen Dispersion eines nicht ionischen Dispergiermittels und eines oder mehrerer linearer Polymerisate von Vinylverbindungen, die Carbonxylgruppen und/oder Salze dieser enthalten, in Gegenwart einer oder mehrerer polykationischer Stickstoffverbindungen behandelt wird. Vorzugsweise verwendet man dabei 10 bis 50 Gew.% an carboxylgruppenhaligem Harz.DE-B-11 76 990 discloses a process for increasing the dry strength of fibrous webs, in which the pulp pulp is mixed with an aqueous dispersion of a nonionic dispersant and one or more linear polymers of vinyl compounds containing carbonxyl groups and / or salts thereof, is treated in the presence of one or more polycationic nitrogen compounds. Preferably 10 to 50% by weight of carboxyl group-containing resin is used.

Aus der CA-PS 1 110 019 ist ein Verfahren zur Herstellung von Papier mit hoher Trockenfestigkeit bekannt, bei dem man zum Papierstoff zunächst ein wasserlösliches kationisches Polymerisat, z. B. Polyethylenimin, zugibt und danach ein wasserlösliches anionisches Polymerisat, z. B. ein hydrolysiertes Polyacrylamid zufügt und den Papierstoff auf einer Papiermaschine unter Blattbildung entwässert. Die anionischen Polymerisate enthalten bis zu 30 Mol.% Acrylsäure einpolymerisiert. Da man das Trockenverfestigungsmittel bereits zum Papierstoff zugibt, ist ein Oberflächenauftrag nicht mehr erforderlich, allerdings führen die anionischen Polyacrylamide nach einer gewissen Laufzeit zu einer schlechteren Entwässerung der Stoffsuspension und zu einem Verkleben der Filze der Papiermaschine.From CA-PS 1 110 019 a process for the production of paper with high dry strength is known, in which a water-soluble cationic polymer, for. B. polyethyleneimine, and then a water-soluble anionic polymer, for. B. adds a hydrolyzed polyacrylamide and dewatered the paper stock on a paper machine with sheet formation. The anionic polymers contain up to 30 mol% of acrylic acid copolymerized. Since the dry strength agent is already added to the paper stock, a surface application is no longer necessary, but after a certain time the anionic polyacrylamides lead to poorer dewatering of the stock suspension and to a sticking of the felts of the paper machine.

Der vorliegenden Erfindung liegt die Aufgabe zugrunde, ein Verfahren zur Herstellung von Papier mit hoher Trockenfestigkeit und möglichst niedriger Naßfestigkeit zur Verfügung zu stellen, bei dem man gegenüber dem aus der CA-PS 1 110 019 bekannten Verfahren Papiere mit verbesserter Trockenfestigkeit und im Fall des Einsatzes gebleichter Stoffe Papiere mit höherer Weiße erhält.The present invention has for its object to provide a process for the production of paper with high dry strength and the lowest possible wet strength, in which compared to the process known from CA-PS 1 110 019 papers with improved dry strength and in the case of use bleached fabrics get papers with higher whiteness.

Die Aufgabe wird erfindungsgemäß gelöst mit einem Verfahren zur Herstellung von Papier mit hoher Trockenfestigkeit durch nacheinander erfolgende Zugabe von (A) wasserlöslichen kationischen Polymerisaten und (B) wasserlöslichen anionischen Polymerisaten zum Papierstoff und Entwässern des Papierstoffs unter Blattbildung, wenn man die Komponente (A) in einer Menge von 0,01 bis 3 Gew.% und die Komponente (B) in einer Menge von 0,05 bis 3 Gew.%, jeweils bezogen auf trockenen Papierstoff, anwendet und daß man als Komponente (B) Homopolymerisate von ethylenisch ungesättigten C3- bis C5-Carbonsäuren und/oder Copolymerisate mit einem K-Wert von jeweils 50 bis 250 (bestimmt nach H. Fikentscher bei 20 °C in 5 %-iger wäßriger Kochsalzlösung und einer Polymerkonzentration von 0,5 Gew.%) aus

  • (a) 35 bis 99 Gew.% ethylenisch ungesättigten C3- bis Cs-Carbonsäuren,
  • (b) 65 bis 1 Gew.% eines Aminds, Nitrils und/oder Esters einer ethylenisch ungesättigten C3- bis C5-Carbonsäure
  • (c) 0 bis 15 Gew.% Styrol oder eines C1- bis C4-Alkylvinylethers, wobei die Summe der Gew.% im Copolymerisat jeweils 100 beträgt, einsetzt.
The object is achieved according to the invention with a process for the production of paper with high dry strength by successively adding (A) water-soluble cationic polymers and (B) water-soluble anionic polymers to the paper stock and dewatering the paper stock with sheet formation if component (A) is added an amount of 0.01 to 3% by weight and component (B) in an amount of 0.05 to 3% by weight, based in each case on dry paper stock, and that component (B) is a homopolymer of ethylenically unsaturated C. 3 - to C 5 - Carboxylic acids and / or copolymers with a K value of 50 to 250 in each case (determined according to H. Fikentscher at 20 ° C. in 5% aqueous sodium chloride solution and a polymer concentration of 0.5% by weight)
  • (a) 35 to 99% by weight of ethylenically unsaturated C 3 to C s carboxylic acids,
  • (b) 65 to 1% by weight of an amine, nitrile and / or ester of an ethylenically unsaturated C 3 to C 5 carboxylic acid
  • (c) 0 to 15% by weight of styrene or a C 1 -C 4 -alkyl vinyl ether, the sum of the% by weight in the copolymer being 100 in each case.

Die kationischen Polymerisate werden dem Stoff zugesetzt, um die negativ geladenen Cellulosefasern umzuladen. Als wasserlösliche kationische Polymerisate (A) kommen beispielsweise folgende Verbindungsklassen in Betracht : Polyethylenimine, die in 10 %iger wäßriger Lösung bei einem pH-Wert von 7 eine Viskosität in dem Bereich von 5 bis 100, vorzugsweise 10 bis 40 mPas aufweisen (gemessen bei 20 °C, Rotationsviskosimeter, 20 U/min). Die Polymerisate können mit organischen Säuren wie Ameisensäure, Essigsäure oder Propionsäure oder mit anorganischen Säuren, wie Salzsäure, Schwefelsäure oder Phosphorsäure neutralisiert sein.The cationic polymers are added to the fabric in order to transfer the negatively charged cellulose fibers. The following classes of compounds are suitable as water-soluble cationic polymers (A): polyethyleneimines which, in 10% strength aqueous solution at a pH of 7, have a viscosity in the range from 5 to 100, preferably 10 to 40 mPas (measured at 20 ° C, rotational viscometer, 20 rpm). The polymers can be neutralized with organic acids such as formic acid, acetic acid or propionic acid or with inorganic acids such as hydrochloric acid, sulfuric acid or phosphoric acid.

Als Komponente (A) eignen sich außerdem partiell bis vollständig hydrolysierte Homo- und Copolymerisate des N-Vinylformamids. Der Hydrolysegrad des N-Vinylformamids in diesen Polymerisaten beträgt mindestens 30 Mol.% und liegt vorzugsweise in dem Bereich von 50 bis 100 Mol.%. Geht man beispielsweise von einem Homopolymerisat des N-Vinylformamids aus und hydrolysiert zu 100 %, so erhält man ein Polyvinylamin. Copolymerisate des N-Vinylformamids mit anderen Monomeren, z. B. Vinylacetat, Acrylnitril, Methacrylniytil, Acrylamid und Methacrylamid können ebenfalls durch Einwirkung von Säuren oder Basen hydrolysiert werden. Der Hydrolysegrad, der oben angegeben wurde, bezieht sich bei den Copolymerisaten des N-Vinylformamids immer auf den Gehalt an N-Vinylformamid im Copolymerisat. Bei der Verseifung von Copolymerisaten aus N-Vinylformamid und Vinylacetat erhält man Polymerisate, die neben den Einheiten der diesen Polymerisaten zugrundeliegenden Monomeren noch Einheiten von Vinylamin und Vinylalkohol aufweisen. Geeignete Homopolymerisate des N-Vinylformamids und Copolymerisate des N-Vinylformamids mit anderen ethylenisch ungesättigten Monomeren haben einen K-Wert (nach H. Fikentscher) von 50 bis 250 und vorzugsweise von 100 bis 150. Der K-Wert der nichtverseiften und der verseiften" N-Vinylformamidpolymerisate stimmt im Rahmen der Fehlergrenzen überein.Partially to fully hydrolyzed homo- and copolymers of N-vinylformamide are also suitable as component (A). The degree of hydrolysis of the N-vinylformamide in these polymers is at least 30 mol% and is preferably in the range from 50 to 100 mol%. For example, if one starts from a homopolymer of N-vinylformamide and hydrolyzes 100%, a polyvinylamine is obtained. Copolymers of N-vinylformamide with other monomers, e.g. B. vinyl acetate, acrylonitrile, methacrylniytil, acrylamide and methacrylamide can also be hydrolyzed by the action of acids or bases. The degree of hydrolysis stated above always relates to the N-vinylformamide content of the copolymer in the copolymers of N-vinylformamide. Saponification of copolymers of N-vinylformamide and vinyl acetate gives polymers which, in addition to the units of the monomers on which these polymers are based, also have units of vinylamine and vinyl alcohol. Suitable homopolymers of N-vinylformamide and copolymers of N-vinylformamide with other ethylenically unsaturated monomers have a K value (according to H. Fikentscher) from 50 to 250 and preferably from 100 to 150. The K value of the unsaponified and the saponified "N -Vinylformamidpolymerisate agrees within the limits of error.

Als Komponente (A) eignen sich außerdem Homo- und Copolymerisate von N-Vinylimidazol und N-Vinylimidazolin sowie deren Derivate. Die Copolymerisate enthalten mindestens 30 Gew.% N-Vinylimidazol oder N-Vinylimidazolin oder deren Derivate einpolymerisiert. Als Comonomer eignen sich beispielsweise Acrylamid, Methacrylamid, Acrylnitril, Methacrylnitril, Vinylpropionat, Vinylactat und Vinyl-C1- bis C4-alkylether (z. B. Vinylmethylether oder Vinylethylether). Als Derivate von N-Vinylimidazol und N-Vinylimidazolin kommen beispielsweise jeweils die C1- bis C3-alkylsubstituierten bzw. phenylsubstituierten Verbindungen in Betracht.Also suitable as component (A) are homopolymers and copolymers of N-vinylimidazole and N-vinylimidazoline and their derivatives. The copolymers contain at least 30% by weight of N-vinylimidazole or N-vinylimidazoline or their derivatives in copolymerized form. Examples of suitable comonomers are acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, vinyl propionate, vinyl lactate and vinyl C 1 -C 4 -alkyl ethers (e.g. vinyl methyl ether or vinyl ethyl ether). Examples of suitable derivatives of N-vinylimidazole and N-vinylimidazoline are, for example, the C 1 - to C 3 -alkyl-substituted or phenyl-substituted compounds.

Die Polymerisate des N-Vinylimidazols und des N-Vinylimidazolins haben K-Werte (bestimmt nach H. Fikentscher) von 50 bis 250 und vorzugsweise 100 bis 150.The polymers of N-vinylimidazole and N-vinylimidazoline have K values (determined according to H. Fikentscher) from 50 to 250 and preferably 100 to 150.

Weitere wasserlösliche kationische Polymerisate (A) sind Polyamidoamine, die mit Epichlorhydrin vernetzt sind. Geeignete Produkte dieser Art sind beispielsweise aus der US-PS 2 926 116 bekannt. Sie werden hergestellt, indem man eine Dicarbonsäure, wie Adipinsäure, mit einem Polyamin z. B. Diethylentriamin oder Tetraethylenpentamin kondensiert und das dabei erhaltene Harz soweit mit Epichlorhydrin vernetzt, daß man noch wasserlösliche Reaktionsprodukte erhält. Diese Polymeren haben in 10 Gew.%iger wäßriger Lösung bei einer Temperatur von 20 °C eine Viskosität von 20 bis 200 mPas (gemessen mit einem Rotations-Viskosimeter bei 20 U/min).Other water-soluble cationic polymers (A) are polyamidoamines which are crosslinked with epichlorohydrin. Suitable products of this type are known, for example, from US Pat. No. 2,926,116. They are made by using a dicarboxylic acid such as adipic acid with a polyamine e.g. B. condensed diethylene triamine or tetraethylene pentamine and the resulting resin cross-linked with epichlorohydrin to the extent that water-soluble reaction products are still obtained. These polymers have a viscosity of 20 to 200 mPas in a 10% by weight aqueous solution at a temperature of 20 ° C. (measured with a rotary viscometer at 20 rpm).

Zu dieser Gruppe von kationischen Polymeren gehören auch mit Ethylenimin gepfropfte Polyamidoamine, die mit Epichlorhydrin oder gemäß der DE-PS2434816 mit Reaktionsprodukten vernetzt sind, die durch Umsetzung der endständigen OH-Gruppen von Pölyalkylenoxiden mit 8 bis 100 AlkylenoxidEinheiten (vorzugsweise Polyethylenoxiden) mit mindestens äquivalenten Mengen Epichlorhydrin erhalten werden. Die Viskosität der mit Ethylenimin gepfropften und vernetzten, wasserlöslichen Produkte beträgt - gemessen mit einem Rotationsviskosimeter bei 20 U/min und 20 °C - 300 bis 2 500 mPas.This group of cationic polymers also includes polyamidoamines grafted with ethyleneimine, which are crosslinked with epichlorohydrin or, according to DE-PS2434816, with reaction products which are reacted with at least equivalent amounts by reacting the terminal OH groups of polyalkylene oxides with 8 to 100 alkylene oxide units (preferably polyethylene oxides) Epichlorohydrin can be obtained. The viscosity of the water-soluble products grafted and crosslinked with ethyleneimine, measured with a rotary viscometer at 20 rpm and 20 ° C., is 300 to 2500 mPas.

Außerdem eignen sich als kationische Polymerisate (A) Homopolymerisate von Diallyldi-C1- bis C3- alkylammoniumverbindungen und Diallylmono-Ci- bis C3-aminen. Man kann entweder die freien Basen bzw. die Halogenide, insbesondere die Chloride verwenden. Besonders geeignet sind Homopolymerisate von Diallyldimethylammoniumchlorid und Diallyldiethylammoniumchlorid. Die Polymerisate dieser Stoffklasse haben K-Werte (gemessen nach H. Fikentscher) von 50 bis 150, vorzugsweise von 100 bis 150.Also suitable as cationic polymers (A) are homopolymers of diallyldi-C 1 -C 3 -alkylammonium compounds and diallyl mono-C i -C 3 -amines. Either the free bases or the halides, in particular the chlorides, can be used. Homopolymers of diallyldimethylammonium chloride and diallyldiethylammonium chloride are particularly suitable. The polymers of this class of substances have K values (measured according to H. Fikentscher) from 50 to 150, preferably from 100 to 150.

Von den Verbindungen der Komponente (A) verwendet man vorzugsweise Polyethylenimine, Polyvinylamine, die durch Hydrolyse von Homopolymerisaten des N-Vinylformamids oder von Copolymerisaten aus N-Vinylformamid und Vinylacetat, Acrylamid oder Acrylnitril hergestellt werden, wobei der Hydrolysegrad, jeweils bezogen auf einpolymerisiertes N-Vinylformamid, mindestens 50 bis 100 Mol.% beträgt, und Polyvinylimidazol. Bezogen auf trockenen Papierstoff setzt man 0,01 bis 3, vorzugsweise 0,1 bis 0,5 Gew.% einer kationischen Verbindungen (A) ein. Es ist selbstverständlich auch möglich, eine Mischung von 2 oder 3 verschiedenen kationischen Verbindungen bei dem erfindungsgemäßen Verfahren einzusetzen. Sofern die kationischen Verbindungen (A) stark basisch sind, können sie in teilweise oder vollständig mit einer Säure neutralisierten Form eingesetzt werden. Der pH-Wert dieser Lösungen beträgt dann 6 bis 8, vorzugsweise 7 bis 7,5.Of the compounds of component (A), preference is given to using polyethyleneimines, polyvinylamines which are prepared by hydrolysis of homopolymers of N-vinylformamide or of copolymers of N-vinylformamide and vinyl acetate, acrylamide or acrylonitrile, the degree of hydrolysis, in each case based on polymerized N- Vinylformamide, at least 50 to 100 mol.%, And polyvinylimidazole. Based on dry paper stock, 0.01 to 3, preferably 0.1 to 0.5% by weight of a cationic compound (A) is used. It is of course also possible to have one Use mixture of 2 or 3 different cationic compounds in the process according to the invention. If the cationic compounds (A) are strongly basic, they can be used in a form partially or completely neutralized with an acid. The pH of these solutions is then 6 to 8, preferably 7 to 7.5.

Als wasserlösliche anionische Polymerisate - Komponente (B) - verwendet man beispielsweise Homopolymerisate von ethylenisch ungesättigten C3- bis C5-Carbonsaüren. Hierunter beispielsweise Homopolymerisate der Acrylsäure, Methacrylsäure, Maleinsäure, hydrolysierte Homopolymerisate von Maleinsäureanhydrid und Itanconsäure. Die genannten ethylenisch ungesättigten Carbonsäuren können mit anderen Monomeren copolymerisiert werden. So eignen sich als Komponente (B) Copolymerisate aus (a) 35 bis 99 Gew.% ethylenisch ungesättigten C3- bis Cs-Carbonsäuren, (b) 65 bis 1 Gew.% eines Amids, Nitrils und/oder eines Esters einer ethylenisch ungesättigten C3- bis C5-Carbonsäure und (c) 0 bis 15 Gew.% Styrol oder eines C1- bis C4-Alkylvinylethers. Die Copolymerisate enthalten vorzugsweise (a) 40 bis 70 Gew.% einer ethylenisch ungesättigten C3- bis C5-Carbonsäure, (b) 60 bis 30 Gew.% eines Amids, Nitrils und/oder eines Esters einer ethylenisch ungesättigten Carbonsäure und (c) 0 bis 15 Gew.% Styrol oder eines C1- bis C4-Alkylvinylethers. Die Summe der Gewichtsprozente im Copolymerisat beträgt jeweils 100. Die Ester von ethylenisch ungesättigten Cs- bis Cs-Carbonsäuren der Komponente (b) der Copolymerisate leiten sich vorzugsweise von Alkoholen mit 1 bis 4 Kohlenstoffatomen ab. Besonders bevorzugt als Komponente (B) sind Terpolymerisate aus (a) 40 bis 70 Gew.% Acrylsaüre, (b1) 10 bis 50 Gew.% Acrylamid und (b2) 10 bis 50 Gew.% Acrylnitril. Die anionischen wasserlöslichen Polymerisate (B) haben einen K-Wert (nach H. Fikentscher) von 50 bis 250 und vorzugsweise von 100 bis 150. Der K-Wert für die Copolymerisate wird bestimmt bei 20 °C in 5 %iger wäßriger Kochsalzlösung und einer Polymerkonzentration von 0,5 Gew.%. Der pH-Wert bei der Bestimmung der K-Werte beträgt 7. Die anionische Komponente (B) wird in einer Menge von 0,05 bis 3, vorzugsweise 0,1 bis 1,0 Gew.%, bezogen auf trockenen Faserstoff angewendet. Das Gewichtsverhältnis der Komponenten (A) zu (B) beträgt 1 : 0,5 bis 10 und liegt vorzugsweise in dem Bereich von 1:2 bis 4. Die anionische Komponente kann in Form der freien Säuren bzw. in partiell oder vollständig mit Basen neutralisierter Form zur Anwendung gelangen. Wichtig ist hierbei lediglich, daß die partiell oder vollständig neutralisierten Polymerisate in Wasser löslich sind. Als Basen kommen Alkali- und Erdalkalilaugen sowie Ammoniak und Amine in Betracht, z. B. Natronlauge, Kalilauge, Calciumhydroxyd, Bariumhydroxid, Ammoniak, Trimethylamin, Ethanolamin und Morpholin.The water-soluble anionic polymers - component (B) - are, for example, homopolymers of ethylenically unsaturated C 3 to C 5 carboxylic acids. These include, for example, homopolymers of acrylic acid, methacrylic acid, maleic acid, hydrolyzed homopolymers of maleic anhydride and itanconic acid. The ethylenically unsaturated carboxylic acids mentioned can be copolymerized with other monomers. Suitable as component (B) are copolymers of (a) 35 to 99% by weight of ethylenically unsaturated C 3 to C s carboxylic acids, (b) 65 to 1% by weight of an amide, nitrile and / or an ester of an ethylenic unsaturated C 3 to C 5 carboxylic acid and (c) 0 to 15% by weight of styrene or a C 1 to C 4 alkyl vinyl ether. The copolymers preferably contain (a) 40 to 70% by weight of an ethylenically unsaturated C 3 to C 5 carboxylic acid, (b) 60 to 30% by weight of an amide, nitrile and / or an ester of an ethylenically unsaturated carboxylic acid and (c ) 0 to 15 wt .-% styrene or a C 1 - to C 4 alkyl vinyl ether. The sum of the percentages by weight in the copolymer is 100 in each case. The esters of ethylenically unsaturated C s to C s carboxylic acids of component (b) of the copolymers are preferably derived from alcohols having 1 to 4 carbon atoms. Particularly preferred as component (B) are terpolymers made of (a) 40 to 70% by weight of acrylic acid, (b 1 ) 10 to 50% by weight of acrylamide and (b 2 ) 10 to 50% by weight of acrylonitrile. The anionic water-soluble polymers (B) have a K value (according to H. Fikentscher) from 50 to 250 and preferably from 100 to 150. The K value for the copolymers is determined at 20 ° C. in 5% strength aqueous sodium chloride solution and one Polymer concentration of 0.5% by weight. The pH when determining the K values is 7. The anionic component (B) is used in an amount of 0.05 to 3, preferably 0.1 to 1.0,% by weight, based on the dry fiber material. The weight ratio of components (A) to (B) is 1: 0.5 to 10 and is preferably in the range from 1: 2 to 4. The anionic component can be neutralized in the form of the free acids or partially or completely with bases Form apply. It is only important here that the partially or completely neutralized polymers are soluble in water. As bases are alkali and alkaline earths as well as ammonia and amines, for. B. sodium hydroxide solution, potassium hydroxide solution, calcium hydroxide, barium hydroxide, ammonia, trimethylamine, ethanolamine and morpholine.

Nach dem erfindungsgemäßen Verfahren können alle bekannten Papier- und Kartonqualitäten hergestellt werden, z. B. Schreib, Druck- und Verpackungspapiere. Die Papiere können aus einer Vielzahl verschiedenartiger Fasermaterialien hergestellt werden, beispielsweise aus Sulfit- oder Sulfat-Zellstoff in gebleichtem oder ungebleichtem Zustand, Holz-, Schliff- oder Altpapier. Die Papierherstellung erfolgt in dem pH-Bereich von 4,5 bis 8, vorzugsweise bei pH-Werten von 6 bis 7. Zur Einstellung des pH-Wertes der Stoffsuspension kann man Schwefelsäure oder Aluminiumsulfat verwenden. Vorzugsweise führt man das erfindungsgemäße Verfahren in Gegenwart von nur geringen Aluminiumsulfatmengen durch. Erfindungsgemäß gibt man zum Stoff zunächst die kationische Komponente (A), die für eine Umladung der Cellulosefasern verantwortlich ist. Die Komponente (A) wird sehr rasch auf den Fasern fixiert. Direkt danach oder auch nach einer gewissen Verweilzeit, z. B. nach 1 bis 10 Minuten, fügt man eine oder mehrere Verbindungen gemäß (B) zum Stoff, homogenisiert die Mischung und setzt gegebenenfalls weitere übliche Hilfsmittel zu, wie Retentionsmittel, Entwässerungsmittel, Füllstoffe, Leimungsmittel, optische Aufheller, Entschäumer, Farbstoffe, Stärke, Polyvinylalkohol, Carboxymethylcellulose oder Mannogalactane - und bildet daran anschließend das Blatt auf einer Papiermaschine.All known paper and cardboard qualities can be produced by the method according to the invention, e.g. B. Writing, printing and packaging papers. The papers can be made from a variety of different types of fiber materials, for example from sulfite or sulfate pulp in the bleached or unbleached state, wood, ground or waste paper. The papermaking takes place in the pH range from 4.5 to 8, preferably at pH values from 6 to 7. To adjust the pH value of the stock suspension, sulfuric acid or aluminum sulfate can be used. The process according to the invention is preferably carried out in the presence of only small amounts of aluminum sulfate. According to the invention, the cationic component (A), which is responsible for the recharge of the cellulose fibers, is first added to the substance. Component (A) is very quickly fixed on the fibers. Immediately afterwards or after a certain dwell time, e.g. B. after 1 to 10 minutes, one or more compounds according to (B) are added to the substance, the mixture is homogenized and, if appropriate, other conventional auxiliaries are added, such as retention aids, drainage agents, fillers, sizing agents, optical brighteners, defoamers, dyes, starch, Polyvinyl alcohol, carboxymethyl cellulose or mannogalactane - and then forms the sheet on a paper machine.

Gegenüber dem bekannten Verfahren beobachtet man bei Verwendung der anionischen Komponenten (B) eine Verbesserung der Retention von Faser- und Füllstoffen sowie üblicher Hilfsmittel, wie Stärke oder Carboxymethylcellulose bei allen Papierqualitäten. Ein weiterer Vorteil bei Einsatz der anionischen Verbindungen (B) besteht in einer Verbeserung der Entwässerung der Stoffsuspension und darin, daß die Filze der Papiermaschine auch bei längerer Laufzeit nicht verkleben. Aufgrund dieser vorteilhaften Eigenschaften hat das erfindungsgemäße Verfahren besondere Bedeutung für die Herstellung von Papier aus Altpapier. Bei der Herstellung von gebleichten Papierqualitäten findet man eine deutlich höhere Weiße des Papiers gegenüber den Verfahren des Standes der Technik.Compared to the known method, when using the anionic components (B), an improvement in the retention of fibers and fillers and also conventional auxiliaries, such as starch or carboxymethyl cellulose, is observed in all paper grades. Another advantage of using the anionic compounds (B) is an improvement in the dewatering of the stock suspension and the fact that the felts of the paper machine do not stick together even over a long period of time. Because of these advantageous properties, the method according to the invention is of particular importance for the production of paper from waste paper. In the production of bleached paper grades, there is a significantly higher whiteness of the paper compared to the methods of the prior art.

Die in den folgenden Beispielen angegebenen Teile sind Gewichtsteile, die Prozentangaben beziehen sich auf das Gewicht der Stoffe. Der K-Wert der Polymerisate wurde nach H. Fikentscher, Cellulosechemie 13, 58-64 und 71-74 (1932) bei einer Temperatur von 200C in 5 %igen wäßrigen Kochsalzlösungen bei einem pH-Wert von 7 und einer Polymerkonzentration von 0,5 % bestimmt ; dabei bedeutet K = k. 103.The parts given in the following examples are parts by weight, the percentages relate to the weight of the substances. The K value of the polymers was determined according to H. Fikentscher, Cellulosechemie 13, 58-64 and 71-74 (1932) at a temperature of 200C in 5% aqueous saline solutions at a pH of 7 and a polymer concentration of 0.5 % certainly ; where K = k. 103.

In den Laborversuchen wurden die Blätter in einem Rapid-Köthen Laborblattbildner hergestellt. Die Trockenreißlänge wurde gemäß DIN 53 112, Blatt 1 und die Naßreißlänge gemäß DIN 53 113, Blatt 2 bestimmt. Die Weiße der Papierblätter wurde mit Hilfe eines Reflektionsfotometers (Elrefo-Gerät) nach DIN 53 145 bestimmt. Die Ermittlung des CMT-Wertes erfolgte nach DIN 53 143, der Trockenberstdruck wurde nach DIN 53 141 ermittelt.In the laboratory tests, the sheets were produced in a Rapid-Köthen laboratory sheet former. The dry tear length was determined in accordance with DIN 53 112, sheet 1 and the wet tear length in accordance with DIN 53 113, sheet 2. The whiteness of the paper sheets was determined with the aid of a reflection photometer (Elrefo device) in accordance with DIN 53 145. The CMT value was determined in accordance with DIN 53 143, the dry burst pressure was determined in accordance with DIN 53 141.

(Siehe Beispiel 1 Seite 5 f.)(See example 1 page 5 f.) Beispiel 1example 1

Aus 100 % gemischtem Altpapier wurde eine 0,5%ige wäßrige Stoffsuspension hergestellt. Der pH-Wert der Suspension betrug 7,2, der Mahlgrad des Stoffs 50° Schopper-Riegler (SR). Die Stoffsuspension wurde dann in fünf gleiche Teile geteilt und unter den folgenden Bedingungen zu Blättern einer Flächenmasse von 120 g/m2 verarbeitet:A 0.5% aqueous stock suspension was prepared from 100% mixed waste paper. The pH of the suspension was 7.2, the degree of grinding of the material was 50 ° Schopper-Riegler (SR). The stock suspension was then divided into five equal parts and processed into sheets with a mass per unit area of 120 g / m 2 under the following conditions:

a) Vergleicha) Comparison

Aus der Stoffsuspension wurde ohne weitere Zusätze ein Blatt gebildet.A sheet was formed from the stock suspension without further additives.

b) Vergleichb) comparison

Zur Stoffsuspension gab man zunächst, bezogen auf trockenen Faserstoff, 0,25 % Polyethylenimin, das in 10 %iger wäßriger Lösung eine Viskosität von 30 mPas hatte. 5 Minuten später fügte man, bezogen auf trockenen Faserstoff, 0,5 % eines Copolymerisates aus 80 % Acrylamid und 20 % Acrylsäure zu. Das Copolymerisat lag in Form des Natriumsalzes vor und hatte einen K-Wert von 120. Nach einem guten Durchmischen und einer Verweilzeit von 5 Minuten wurde das Blatt gebildet.0.25% of polyethyleneimine, which had a viscosity of 30 mPas in 10% strength aqueous solution, was initially added to the stock suspension, based on dry fiber stock. 5 minutes later, based on dry fiber, 0.5% of a copolymer of 80% acrylamide and 20% acrylic acid was added. The copolymer was in the form of the sodium salt and had a K value of 120. After thorough mixing and a residence time of 5 minutes, the sheet was formed.

c) Vergleichc) comparison

Zu der oben beschriebenen Stoffsuspension gab man, bezogen auf trockenen Faserstoff, 0,3 % Polyethylenimin wie bei b) und nach einer Verweilzeit von 5 Minuten 1,0 % des anionischen Polyacrylamids gemäß b). Die Mischung wurde 5 Minuten gerührt und dann unter Blattbildung entwässert.To the stock suspension described above, based on dry fiber stock, 0.3% of polyethyleneimine as in b) and after a residence time of 5 minutes, 1.0% of the anionic polyacrylamide in b). The mixture was stirred for 5 minutes and then dewatered to form leaves.

d) Beispiel gemäß Erfindungd) Example according to the invention

Zu einem weiteren Teil der oben angegebenen Stoffsuspension gab man, bezogen auf trockenen Faserstoff, 0,25 % des Polyethylenimins, das gemäß b) verwendet wurde und fügte nach einer Verweilzeit von 5 Minuten 0,5 %, bezogen auf trockenen Faserstoff, eines Mischpolymerisats aus 50 % Acrylsäure und 50 % Acrylnitril in Form des Natriumsalzes zu. Das Copolymerisat hatte einen K-Wert von 120. Nach einer Mischungszeit von 5 Minuten wurde ein Papierblatt gebildet.0.25% of the polyethyleneimine, which was used in accordance with b), was added to a further part of the pulp suspension mentioned, based on dry pulp, and 0.5%, based on dry pulp, of a copolymer was added after a residence time of 5 minutes 50% acrylic acid and 50% acrylonitrile in the form of the sodium salt. The copolymer had a K value of 120. A paper sheet was formed after a mixing time of 5 minutes.

e) Beispiel gemäß Erfindung <e) Example according to the invention <

Zu einer Probe der oben beschriebenen Stoffsuspension gab man, bezogen auf trockenen Faserstoff, 0,5 % des unter b) beschriebenen Polyethylenimins und fügte nach einer Verweilzeit von 5 Minuten 1,0 % eines Copolymerisates aus 50 % Acrylsäure und 50 % Acrylnitril zu. Nach einem Durchmischen von 5 Minuten wurde die so erhaltene Stoffsuspension unter Blattbildung entwässert. Die Ergebnisse von Prüfungen, die an den jeweils gebildeten Blättern vorgenommen wurden, sind in Tabelle 1 angegeben.

Figure imgb0001
0.5% of the polyethyleneimine described under b) was added to a sample of the stock suspension described above, and 1.0% of a copolymer of 50% acrylic acid and 50% acrylonitrile was added after a residence time of 5 minutes. After mixing for 5 minutes, the stock suspension obtained in this way was dewatered with the formation of leaves. The results of tests carried out on the sheets formed are shown in Table 1.
Figure imgb0001

Beispiel 2Example 2

Aus 70 % gebleichtem Holzschliff und 30 % gebleichtem Buchensulfitzellstoff wurde eine 0,5%ige wäßrige Stoffsuspension hergestellt, die einen pH-Wert von 7,5 und einen Mahlgrad von 45° SR hatte. Die Suspension wurde in fünf gleiche Teile geteilt und unter den nachstehenden Bedingungen zu Blättern mit einer Flächenmasse von 100 g/m2 verarbeitet:A 70% bleached wood pulp and 30% bleached beech sulfite pulp were used to produce a 0.5% aqueous suspension which had a pH of 7.5 and a freeness of 45 ° SR. The suspension was divided into five equal parts and processed into sheets with a mass per unit area of 100 g / m 2 under the following conditions:

a) Vergleicha) Comparison

Die oben beschriebene Stoffsuspension wurde direkt zu einem Blatt verarbeitet.The stock suspension described above was processed directly into a sheet.

b) Vergleichb) comparison

Eine Probe der oben beschriebenen Stoffsuspension wurde, bezogen auf trockenen Faserstoff, mit 0,3 % eines Polyethylenimins einer Viskosität von 50 mPas (gemessen bei einem Feststoffgehalt von 10 % in wäßriger Lösung bei einem pH-Wert von 7) versetzt. Dadurch erfolgte eine Umladung der Cellulosefasern. Nach einer Verweilzeit von 1 Minute fügte man 0,9 % eines Copolymerisates aus 90 % Acrylamid und 10 % Acrylsäure zu. Das Copolymerisat lag in Form des Ammoniumsalzes vor und hatte einen K-Wert von 90. Die Stoffsuspension wurde noch 10 Minuten gerührt und anschließend unter Blattbildung entwässert.A sample of the stock suspension described above, based on dry fiber stock, was mixed with 0.3% of a polyethyleneimine with a viscosity of 50 mPas (measured at a solids content of 10% in aqueous solution at a pH of 7). As a result, the cellulose fibers were reloaded. After a residence time of 1 minute, 0.9% of a copolymer of 90% acrylamide and 10% acrylic acid was added. The copolymer was in the form of the ammonium salt and had a K value of 90. The stock suspension was stirred for a further 10 minutes and then dewatered to form sheets.

c) Vergleichc) comparison

Zu einer Probe der oben beschriebenen Stoffsuspension gab man, bezogen auf trockenen Faserstoff, 0,3 % eine Homopolymerisates aus Dimethyldiallylammoniumchlorid mit einem K-Wert von 90 und nach einer Verweilzeit von 1 Minute 0,9 %, bezogen auf trockenen Faserstoff, des anionischen Polymerisats gemäß b) aus 90 % Acrylamid und 10 % Acrylsäure. Nach einer Verweilzeit von 10 Minuten entwässerte man den so behaldelten Stoff unter Blattbildung.To a sample of the stock suspension described above, based on dry fiber, 0.3% of a homopolymer of dimethyldiallylammonium chloride with a K value of 90 and after a residence time of 1 minute 0.9%, based on dry fiber, of the anionic polymer according to b) from 90% acrylamide and 10% acrylic acid. After a dwell time of 10 minutes, the material treated in this way was dewatered to form sheets.

d) Beispiel gemäß Erfindungd) Example according to the invention

Zu einer Probe der oben beschriebenen Stoffs gab man, bezogen auf trockenen Faserstoff, 0,3 % des oben unter b) beschriebenen Polyethylenimins und nach einer Verweilzeit von 1 Minute 0,9 % eines Copolymerisats aus 50 % Acrylsäure, 30 % Acrylamid und 20 % Acrylnitril. Das Copolymerisat lag in Form des Ammoniumsalzes vor und hatte einen K-Wert von 90. 10 Minuten nach Zugabe des anionischen Copolymerisates und nach einem Durchmischen wurde der so behandelte Stoff unter Blattbildung entwässert.To a sample of the material described above, based on dry fiber material, 0.3% of the polyethyleneimine described under b) and after a residence time of 1 minute 0.9% of a copolymer of 50% acrylic acid, 30% acrylamide and 20% Acrylonitrile. The copolymer was in the form of the ammonium salt and had a K value of 90. 10 minutes after the addition of the anionic copolymer and after mixing, the material treated in this way was dewatered to form sheets.

e) Beispiel gemäß Erfindunge) Example according to the invention

Zu einer anderen Probe des oben beschriebenen Stoffs gab man 0,3 %, bezogen auf trockenen Faserstoff des gleichen Dimethyldiallylammonium chloridpolymerisates, wie im Versuch c) hinzu und anschließend nach einer Minute Verweilzeit 0,9 %, bezogen auf trockenen Faserstoff, des Copolymerisats aus 50 % Acrylsäure, 30 % Acrylamid und 20 % Acrylnitril gemäß d). Die Mischung wurde dann 10 Minuten gerührt und anschließend sofort unter Blattbildung entwässert. Von allen Blättern wurden die Festigkeitseigenschaften bestimmt. Die dabei erhaltenen Ergebnisse sind in Tabelle 2 angegeben.

Figure imgb0002
Another sample of the material described above was added with 0.3%, based on dry fibrous material of the same dimethyldiallylammonium chloride polymer as in experiment c), and then after one minute of residence time 0.9%, based on dry fibrous material, of the copolymer of 50 % Acrylic acid, 30% acrylamide and 20% acrylonitrile according to d). The mixture was then stirred for 10 minutes and then immediately drained to form leaves. The strength properties of all sheets were determined. The results obtained are shown in Table 2.
Figure imgb0002

Beispiel 3Example 3

Aus 70 % gebleichtem Kiefernsulfatzellstoff und 30 % gebleichtem Birkensulfatzellstoff wurde eine 0,5 %ige wäßrige Stoffsuspension hergestellt, die einen pH-Wert von 6,5 und einen Mahlgrad von 30 °SR aufwies. Diese Suspension wurde in 5 gleiche Teile geteilt und jeweils wie folgt beschrieben zu Blättern mit einer Flächenmasse von 80 g/m2 verarbeitet:A 70% bleached pine sulphate pulp and 30% bleached birch sulphate pulp were used to produce a 0.5% aqueous pulp suspension which had a pH of 6.5 and a freeness of 30 ° SR. This suspension was divided into 5 equal parts and processed into sheets with a mass per unit area of 80 g / m 2 as described below:

a) Vergleicha) Comparison

Die Stoffsuspension wurde ohne jeden weiteren Zusatz unter Blattbildung entwässert.The stock suspension was dewatered without any further addition, with leaf formation.

b) Vergleichb) comparison

Zu einer Probe der oben beschriebenen Stoffsuspension wurde, bezogen auf trockenen Faserstoff, 0,25 % eines Harzes zugesetzt, das durch Kondensation von Adipinsäure mit Diethylentriamin und Vernetzen des Polyamidoamins mit Epichlorhydrin gemäß Beispiel 1 der US-PS 2 926 116 erhalten wurde. Nach einer Verweilzeit von 2 Minuten setzte man 0,5 % eines Copolymerisats aus 80 % Acrylamid, 10 % Acrylnitril und 10 % Acrylsäure zu. Das Copolymerisat lag in Form des Natriumsalzes vor und hatte einen K-Wert von 130. Nach einer Einwirkungszeit von 2 Minuten wurde die Stoffsuspension unter Blattbildung entwässert.To a sample of the stock suspension described above, 0.25% of a resin was added, based on dry fiber stock, which was obtained by condensing adipic acid with diethylenetriamine and crosslinking the polyamidoamine with epichlorohydrin according to Example 1 of US Pat. No. 2,926,116. After a residence time of 2 minutes, 0.5% of a copolymer of 80% acrylamide, 10% acrylonitrile and 10% acrylic acid was added. The copolymer was in the form of the sodium salt and had a K value of 130. After an exposure time of 2 minutes, the stock suspension was dewatered to form sheets.

c) Vergleichc) comparison

Zu einem anderen Teil der oben beschriebenen wäßrigen Stoffsuspension fügte man, bezogen auf trockenen Faserstoff, 0,25 % eines Polyvinylamins mit einem K-Wert von 140 und nach einer Einwirkungszeit von 2 Minuten außerdem noch 0,5 %, bezogen auf trockenen Faserstoff, des gleichen Polymerisats aus 80 % Acrylamid, 10 % Acrylnitril und 10 % Acrylsäure gemäß b). Nach einer Einwirkungszeit von 2 Minuten wurde die Stoffsuspension unter Blattbildung entwässert.To another part of the aqueous pulp suspension described above, 0.25% of a polyvinylamine with a K value of 140 was added, based on dry pulp and, after an exposure time of 2 minutes, 0.5%, based on dry pulp, of same polymer from 80% acrylamide, 10% acrylonitrile and 10% acrylic acid according to b). After an exposure time of 2 minutes, the stock suspension was dewatered with the formation of leaves.

d) Beispiel gemäß Erfindungd) Example according to the invention

Zu einer Probe der oben beschriebenen wäßrigen Stoffsuspension fügte man, bezogen auf trockenen Faserstoff 0,25 % des oben unter b) beschriebenen Epichlorhydrinharzes und nach einer Verweilzeit von 2 Minuten außerdem noch 0,5 %, bezogen auf trockenen Faserstoff, eines Copolymerisates aus 60 % Acrylsäure, 15 % Acrylnitril und 15 % Acrylamid. Das Copolymerisat lag in Form des Natriumsalzes vor und hatte einen K-Wert von 130. Nach einer Einwirkungszeit von 2 Minuten wurde auch diese Stoffsuspension unter Blattbildung entwässert.0.25% of the epichlorohydrin resin described in b) above was added to a sample of the aqueous pulp suspension described above and, after a residence time of 2 minutes, a further 0.5%, based on dry pulp, of a copolymer of 60% was added. Acrylic acid, 15% acrylonitrile and 15% acrylamide. The copolymer was in the form of the sodium salt and had a K value of 130. After an exposure time of 2 minutes, this stock suspension was also dewatered with the formation of leaves.

e) Beispiel gemäß Erfindunge) Example according to the invention

Zu einer Proben der oben beschriebenen wäßrigen Stoffsuspension fügte man, bezogen auf trockenen Faserstoff 0,25 % des oben unter c) beschriebenen Polyvinylamins und nach einer Verweilzeit von 2 Minuten außerdem noch 0,5 %, bezogen auf trockenen Faserstoff, des unter d) angegebenen Copolymerisats aus 60 % Acrylsäure, 15 % Acrylnitril und 15 % Acrylamid. Nach einer Einwirkungszeit von 2 Minuten wurde auch dieser Stoff unter Blattbildung entwässert. Von allen oben hergestellten Papierblättem wurden die in Tabelle 3 angegebenen Eigenschaften bestimmt.

Figure imgb0003
0.25% of the polyvinylamine described above under c) was added to a sample of the aqueous pulp suspension described above and, after a residence time of 2 minutes, a further 0.5%, based on dry pulp, of that given under d) was added Copolymers of 60% acrylic acid, 15% acrylonitrile and 15% acrylamide. After an exposure time of 2 minutes, this substance was dewatered with the formation of leaves. The properties given in Table 3 were determined for all paper sheets produced above.
Figure imgb0003

Beispiel 4Example 4

Aus einem gemischten Altpapier wurde eine 0,5 %ige wäßrige Stoffsuspension hergestellt, die einen pH-Wert von 7,5 und einen Mahlgrad von 45° SR hatte. Die Stoffsuspension wurde dann in fünf gleiche Teile geteilt und unter den nachstehend angegebenen Bedingungen zu Blättern eines Flächengewichts von 120 g/m2 verarbeitet.A 0.5% aqueous suspension was prepared from a mixed waste paper, which had a pH of 7.5 and a freeness of 45 ° SR. The stock suspension was then divided into five equal parts and processed into sheets with a basis weight of 120 g / m 2 under the conditions specified below.

a) Vergleicha) Comparison

Aus der Stoffsuspension wurde ohne weiteren Zusatz ein Blatt gebildet.A sheet was formed from the stock suspension without further addition.

b) Vergleichb) comparison

Zu einer der oben beschriebenen Probe einer wäßrigen Stoffsuspension gab man zunächst 0,5 %, bezogen auf trockenen Faserstoff, eines Homopolymerisates von Vinylimidazol mit einem K-Wert von 90 und nach einer Verweilzeit von 5 Minuten außerdem noch 1,0 %, bezogen auf trockenen Faserstoff eines Copolymerisates aus 85 % Acrylamid und 15 % Acrylsäure. Das Copolymerisat lag als Natriumsalz vor und hatte einen K-Wert von 130. Nach einer Einwirkungszeit von 1 Minute wurde diese Stoffmischung unter Blattbildung entwässert.0.5%, based on dry fiber, of a homopolymer of vinylimidazole with a K value of 90 was first added to one of the above-described samples of an aqueous stock suspension and after a dwell time of 5 minutes also 1.0%, based on dry fiber of a copolymer of 85% acrylamide and 15% acrylic acid. The copolymer was in the form of the sodium salt and had a K value of 130. After an exposure time of 1 minute, this mixture of substances was dewatered to form sheets.

c) Vergleichc) comparison

Zu einer weiteren Probe der oben angegebenen Stoffsuspension fügte man, bezogen auf trockenen Faserstoff, 0,5 % eines Polyvinylamins mit einem K-Wert von 110 und gab nach einer Verweilzeit von 5 Minuten anschließend noch 1,0 %, bezogen auf trockenen Faserstoff des Copolymerisats aus 85 % Acrylamid und 15 Acrylsäure gemäß Versuch b) hinzu. Nach einer Einwirkungszeit von 1 Minute erfolgte die Entwässerung dieses Papierstoffs unter Blattbildung.0.5% of a polyvinylamine with a K value of 110, based on dry fibrous material, was added to a further sample of the pulp suspension mentioned above, and after a residence time of 5 minutes, 1.0%, based on dry fibrous material of the copolymer, was then added from 85% acrylamide and 15 acrylic acid according to experiment b). After an exposure time of 1 minute, this paper stock was drained to form sheets.

d) Beispiel gemäß Erdindungd) Example according to earth connection

Zu einer weiteren Probe der oben beschriebenen Stoffsuspension gab man, jeweils bezogen auf trockenen Faserstoff, 0,5 % des Vinylimidazolpolymerisats gemäß Versuch b) und nach einer Verweilzeit von 5 Minuten, 1,0 % eines Copolymerisats aus 60 % Acrylsäure und 40 % Acrylnitril zu. Das Copolymerisat lag in Form des Natriumsalzes vor und hatte einen K-Wert von 130. Nach einer Einwirkungszeit von 1 Minute wurde auch der in dieser Weise behandelte Papierstoff unter Blattbildung entwässert.To a further sample of the stock suspension described above, 0.5% of the vinylimidazole polymer according to experiment b), based on dry fiber, was added and after a residence time of 5 minutes, 1.0% of a copolymer of 60% acrylic acid and 40% acrylonitrile . The copolymer was in the form of the sodium salt and had a K value of 130. After an exposure time of 1 minute, the paper stock treated in this way was also dewatered to form sheets.

e) Beispiel gemäß Erdindunge) Example according to earth connection

Zu der verbliebenen Probe der oben beschriebenen Stoffsuspension gab man, jeweils bezogen auf trockenen Faserstoff, 0,5 % des Polyvinylamins gemäß c) und nach einer Einwirkungszeit von 5 Minuten 1,0 % des Copolymerisates auf 60 % Acrylsäure und 40 % Acrylnitril gemäß d) hinzu und entwässerte den Stoff nach einer Einwirkungszeit von 1 Minute unter Blattbildung.0.5% of the polyvinylamine according to c) and, after an exposure time of 5 minutes, 1.0% of the copolymer onto 60% acrylic acid and 40% acrylonitrile according to d) were added to the remaining sample of the stock suspension described above, based in each case on dry fiber stock added and drained the material after a contact time of 1 minute with leaf formation.

Die gemäß a) bis d) hergestellten Papierblätter wurden anschließend geprüft. Die Meßergebnisse sind in Tabelle 4 angegeben.

Figure imgb0004
The paper sheets produced according to a) to d) were then tested. The measurement results are shown in Table 4.
Figure imgb0004

Claims (5)

1. A process for making paper having a high dry strength by adding (A) a water-soluble cationic polymer and (B) a water-soluble anionic polymer in succession to the paper stock and draining the latter with sheet formation by using component (A) in an amount of from 0.01 to 3 % by weight and component (B) in an amount of from 0.05 to 3 % by weight, based on dry paper stock in each case, component (B) being a homopolymer of an ethylenically unsaturated C3-C5-carboxylic acid or a copolymer having a K value of from 50 to 250 (determined according to H. Fikentscher at 20 °C in 5 % strength aqueous sodium chloride solution and at a polymer concentration of 0.5 % by weight) and having been formed from
(a) from 35 to 99 % by weight of an ethylenically unsaturated C3-CS-carboxylic acid,
(b) from 65 to 1 % by weight of an amide, nitrile and/or ester of an ethylenically unsaturated C3-Cs- carboxylic acid and
(c) from 0 to 15 % by weight of styrene or of a C1-C4-alkyl vinyl ether, the sum of the percentages by weight in the copolymer being 100 in each case.
2. A process as claimed in claim 1, wherein a homopolymer of acrylic acid is used as component (B).
3. A process as claimed in claim 1, wherein a copolymer of
(a) from 40 to 70 % by weight of an ethylenically unsaturated C3-C5-carboxylic acid,
(b) from 60 to 30 % by weight of an amide, nitrile and/or ester of an ethylenically unsaturated C3-Cs-carboxylic acid and
(c) from 0 to 15 % by weight of styrene or of a C1-C4-alkyl vinyl ether is used as component (B).
4. A process as claimed in claim 1, wherein a terpolymer of
(a) from 40 to 70 % by weight of acrylic acid,
(bi) from 10 to 50 % by weight of acrylamide and
(b2) from 10 to 50 % by weight of acrylonitrile is used as component (B).
5. A process as claimed in claim 1, wherein polyethyleneimine, an N-vinylformamide polymer which has a degree of hydrolysis of from not less than 30 to 100 % or an N-vinylimidazole polymer is used as component (A) and a copolymer of (a) from 40 to 70 % by weight of acrylic acid and (bi) from 10 to 50 % by weight of acrylamide and (b2) from 10 to 50 % by weight of acrylonitrile is used as component (B).
EP86102199A 1985-02-27 1986-02-20 Process for producing paper with a high dry strength Expired EP0193111B1 (en)

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