JP2015531032A - Paper, paperboard and cardboard manufacturing method - Google Patents

Abstract

The present invention relates to a method for producing paper, board and cardboard comprising dehydration of a filler-containing stock comprising at least one water-soluble polymer under sheet formation in a wire part and paper press in a subsequent press part, At least one water soluble polymer is metered into a stock having a fibrous material concentration in the range of 20-40 g / l, and then the stock is diluted to a fibrous material concentration in the range of 5-15 g / l The diluted stock is dehydrated under sheet formation, and the sheet is pressed to a solid content of G (x)% by mass or more in the press part, and G (x) is G (x) = 48 + ( x-15)? 0.4, where x represents the numerical value of the filler content (mass%) of the dried paper, paperboard or cardboard and G (x) is the lowest solids (% By mass) The sheet is pressed into form, wherein the water-soluble polymer relates to the process, obtained by Hoffmann degradation of acrylamide-containing polymers and / or methacrylamide-containing polymers, optionally followed by postcrosslinking.

Description

  The present invention provides a filler-containing stock comprising at least one water-soluble polymer obtained by Hofmann degradation of an acrylamide-containing polymer and / or a methacrylamide-containing polymer under sheet formation in a wire part and subsequent paper pressing in a press part. The present invention relates to a method for producing paper, paperboard and cardboard, including dehydration.

  New papermaking methods are being developed at various points in the process. New papers used and modified metering methods result in improved paper. Although paper machines are becoming faster and faster, new demands are placed on manufacturing methods.

  The limiting factor in further increasing the speed of the paper machine is the initial wet paper strength. The maximum applicable force that can be applied to a sheet that has just been formed in a paper machine (which passes through the wire part and press part of the paper machine to the dry part) is the initial wet force. Limited by paper strength. In this regard, it is necessary to remove this sheet from the press roll. In order to be able to guarantee uninterrupted operation of the paper machine, the removal force applied at this point must be clearly less than the initial wet paper strength of the wet paper. By increasing the initial wet paper strength, it is possible to apply a higher removal force, and thus the paper machine can be operated at a higher speed (see EP-B-0780513).

  The initial wet web strength is taken as the strength of wet paper that has never been dried. This strength is that of wet paper as it exists after passing through the wire part and press part of the paper machine during papermaking.

  In the press part, the wet fiber web is transferred onto the press felt by a suction pick-up device (suction roll or static vacuum element). The role of the press felt is to transport the fiber web through various modified press nips. The absolute dry rate of this web is up to 55% depending on the design of the press part and the composition of the stock. The rate of dryness then increases with the pressure applied to the paper web passing in the press. The pressure, and thus the dry rate of the paper web, can vary over a relatively wide range in many paper machines.

  It is known that the initial wet paper strength can be improved by increasing the solids content of the paper at a location between the press and dry parts of the manufacturing process. It is also conceivable to improve the solids at these points in the process with a filler to improve dehydration. However, this possibility is limited.

  WO 2009/156274 describes a paper for improving the initial wet paper strength of an amphoteric copolymer obtained by copolymerization of N-vinylcarboxylic acid amide with an anionic comonomer and subsequent hydrolysis of vinylcarboxylic acid amide. It is taught for use as a filler. In the papermaking process, for example, processing is performed on high-concentration paper stock or low-concentration paper stock.

  An earlier application WO 2012/175392 teaches the use of acrylamide-based amphoteric copolymers obtained by copolymerization of acrylamide and anionic comonomers as a paper filler to improve the initial wet paper strength of paper. doing. In the papermaking process, processing is performed on high-concentration stock. Furthermore, the press part of the paper machine needs to be adjusted so that the dry rate of the wet paper web after leaving this press part exceeds the minimum value according to the stock composition.

  Furthermore, the use for reinforcement of polymers obtained, for example, by Hoffmann degradation of acrylamide-containing polymers and / or methacrylamide-containing polymers is known.

  The present invention is based on the problem of improving the initial wet paper strength of a paper web that is still wet prior to the transition to the dry part during paper making in order to achieve a higher machine speed than known methods in the paper making process. ing.

により算出され、
ここで、ｘは、乾燥された紙、板紙又は厚紙の填料含有率（質量％）の数値を表し、かつ、
Ｇ（ｘ）は、最低固形分（質量％）の数値を表し、この最低固形分にシートがプレスされるものとし、
その際、前記水溶性ポリマーは、アクリルアミド含有ポリマー及び／又はメタクリルアミド含有ポリマーをホフマン分解し、任意に次いで後架橋することにより得られる前記方法が見出された。 Accordingly, in a process for producing paper, paperboard and cardboard comprising dehydration of a filler-containing stock comprising at least one water-soluble polymer under sheet formation in a wire part and paper press in a subsequent press part, At least one water soluble polymer is metered into a stock having a fibrous material concentration in the range of 20-40 g / l, and then the stock is diluted to a fibrous material concentration in the range of 5-15 g / l The diluted stock is dehydrated under sheet formation, and the sheet is pressed to a solid content of G (x) mass% or more in the press part, and G (x) is

Calculated by
Where x represents the numerical value of the filler content (% by weight) of the dried paper, paperboard or cardboard, and
G (x) represents the numerical value of the minimum solid content (mass%), and the sheet is pressed to this minimum solid content,
In that case, it has been found that the water-soluble polymer is obtained by Hofmann decomposition of an acrylamide-containing polymer and / or a methacrylamide-containing polymer, optionally followed by postcrosslinking.

  The invention further relates to a method for producing paper, paperboard and cardboard comprising the dewatering of a filler-containing stock comprising at least one water-soluble polymer under sheet formation in a wire part and paper press in a subsequent press part. At least one water-soluble polymer is metered into the stock at a fibrous material concentration in the range of 20-40 g / l, and then the stock is brought to a fibrous material concentration in the range of 5-15 g / l. The diluted stock is dehydrated under sheet formation, and the sheet is pressed to a solid content of 48% by mass or more, preferably 49 to 53% by mass in the press part. Relates to said process obtained by Hofmann degradation of acrylamide-containing polymers and / or methacrylamide-containing polymers and then post-crosslinking.

  Paper stock is hereinafter understood to be a mixture of water and fibrous material, where the fibrous material is further water-soluble polymer depending on the stage in the paper, board or cardboard manufacturing process. , Containing fillers and optionally papermaking aids.

  The absolute dry rate of paper is taken as the solid content of paper, paperboard, cardboard and fibrous materials using an oven drying method as measured, for example, by DIN EN ISO 638 DE.

  Within the scope of the present application, the concept of pigment is used synonymously with the concept of filler because it is used as a filler during papermaking. In this case, the filler is interpreted as an inorganic pigment as usual in papermaking.

  The process according to the invention relates to the production of paper, paperboard and cardboard, including the dehydration of filler-containing stocks. At that time, the filler content (x) of the paper, paperboard and cardboard may be 5 to 40% by mass with respect to the paper, paperboard or cardboard.

  According to a preferred embodiment, a paper production method with a filler content of 20-30% by weight is preferred. Such paper is, for example, high-quality paper.

  According to a further preferred embodiment, a paper production method with a filler content of 10 to 20% by weight is preferred. Such paper is used in particular as wrapping paper.

  According to a further preferred embodiment, a paper production method with a filler content of 5 to 15% by weight is preferred. Such paper is used in particular as newsprint.

  According to a further preferred embodiment, a method for producing paper, for example SC paper, with a filler content of 25-40% by weight is preferred.

に従って、

と算出される。 The aqueous stock containing at least one water-soluble polymer, fibrous material and filler according to the invention is dewatered under sheet formation in the wire part, and the sheet is pressed in the press part, ie further dewatered. At that time, dehydration in the press part is performed up to the minimum solid content, but may be performed beyond this. These lower limits of solids that must be pressed so far are also referred to below as the critical dryness and minimum solids G (x), which relates to pressed sheets that are a mixture of stock and water. is there. At that time, such a critical dry rate of at least dehydration depends on the amount of filler. For example, the critical dry rate G (x) for paper having a filler content of 30 or 15% by weight is given by

According to

Is calculated.

  That is, when producing paper with a filler content of 30% by weight, according to the present invention, in order to obtain a paper with good initial wet paper strength, the press part is pressed to a solids content of at least 54% by weight. Is done.

  On the other hand, according to the present invention, when producing a paper having a filler content of 15 or less, in order to obtain a paper having a good initial wet paper strength, the press part has a solid content of at least 48% by weight. Pressed.

  According to one embodiment of the invention, to produce paper, paperboard and cardboard having a filler content of 17-32% by weight, the press part is pressed to a solids content in the range of at least 49-55% by weight. Is done.

  According to a further embodiment of the invention, to produce paper, paperboard and cardboard having a filler content of 15% by weight or less, the press part is pressed to a solids content of at least 48% by weight.

  According to the invention, the fiber treatment is carried out by metering a water-soluble polymer into the stock at a fibrous material concentration in the range of 20-40 g / l. A fibrous substance concentration of 20 to 40 g / l (corresponding to a fibrous substance concentration of 2 to 4% by mass with respect to the aqueous fibrous substance) is usually interpreted as a high-concentration stock in papermaking. This high-concentration stock is distinguished from the low-concentration stock, where the low-concentration stock is to be interpreted below as a fibrous material concentration in the range of 5-15 g / l. Following treatment with the water-soluble polymer, the stock is diluted with water to a fibrous concentration in the range of 5-15 g / l.

  According to the invention, virgin fibers and / or regenerated fibers may be used as the fibrous material. All fibers from conifers and hardwoods commonly used in the paper industry can be used, for example, using mechanical pulp, bleached chemical pulp, unbleached chemical pulp and fibrous materials from all annual plants. it can. Mechanical pulp includes, for example, groundwood pulp, thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), pressurized groundwood pulp, semi-chemical pulp, high yield pulp and refiner mechanical pulp (RMP). As chemical pulp, for example, sulfate pulp, sulfite pulp and soda chemical pulp are considered. Preferably, unbleached chemical pulp, also called unbleached kraft pulp, is used. Suitable annual plants for the production of fibrous materials are, for example, rice, wheat, sugar cane and kenaf. Waste paper can also be used in the manufacture of the pulp, which is used alone or mixed with other fibrous materials. The waste paper may be derived from, for example, a deinking process. However, the used paper to be used does not necessarily have to be processed in such a process. Furthermore, it is also possible to start with a fiber mixture obtained from primary paper stock or recycled coated waste paper.

  In the case of bleached chemical pulp or unbleached chemical pulp, a fibrous material having a freeness of 20 to 30 SR can be used. Usually, a fibrous material having a freeness of about 30 SR is used, which is beaten during pulp production. Preferably, a fibrous material having a freeness of less than 30 SR is used. Preferably, a fibrous material having a freeness of 30 SR or less is used.

  Treatment of the fibrous material with the water-soluble polymer is carried out in an aqueous suspension, preferably in the absence of other process chemicals usually used in papermaking. This is done by adding at least one water-soluble polymer to an aqueous stock having a fibrous material concentration of 20-40 g / l in the papermaking process. Particularly preferred is a modification in which the water-soluble polymer is added to the aqueous paper stock prior to the addition of the filler. Very particularly preferably, this addition takes place after the addition of a dry strength agent such as starch.

  The water-soluble polymer is preferably added in an amount of 0.05 to 5.00% by weight with respect to the fibrous material (solid).

  Typical usage is, for example, 0.5 to 50 kg, preferably 0.6 to 10 kg of at least one water-soluble polymer per ton of dry fibrous material. Particularly preferably, the amount of water-soluble polymer used is 0.6 to 3 kg (solid) per ton of dry fibrous material.

  The time for the water-soluble polymer to act on the pure fibrous material or paper stock from the metering to the sheet formation is, for example, 0.5 seconds to 2 hours, preferably 1.0 seconds to 15 minutes, particularly preferably. 2 to 20 seconds.

  In addition to the water-soluble polymer, an inorganic pigment is added as a filler to the fibrous material. Inorganic pigments include all metal oxide, silicate and / or carbonate based pigments commonly used in the paper industry, in particular ground (GCC) lime, chalk, marble or precipitated calcium carbonate (PCC). And pigments from the group consisting of calcium carbonate, talc, kaolin, bentonite, satin white, calcium sulfate, barium sulfate and titanium dioxide. Mixtures of two or more pigments can also be used.

  According to the invention, inorganic pigments having an average particle size (volume average) of 10 μm or less, preferably 0.3 to 5 μm, in particular 0.5 to 2 μm are used. The measurement of the average particle diameter (volume average) of the particles of the inorganic pigment and the powder composition is comprehensive within the scope of the present specification, for example, a quasielastic light scattering method using a Mastersizer 2000 manufactured by Malvern Instruments Ltd. ( DIN-ISO 13320-1).

  The inorganic pigment is preferably metered in after the addition of the aqueous polymer. In this case, according to a preferred embodiment, this addition takes place at a stage where the fibrous material is already present as a low-concentration stock, i.e. at a fibrous material concentration of 5 to 15 g / l.

  According to a further preferred embodiment, the inorganic pigment is metered into the low and high concentration papers, with the ratio of both additions (addition high concentration paper / additional low The density paper stock is preferably 5/1 to 1/5.

  Furthermore, in addition to the water-soluble polymer, a conventional paper-making auxiliary can be optionally added to the paper stock at a fibrous substance concentration of usually 5 to 15 g / l. Conventional papermaking aids include, for example, sizing agents, wet paper strength enhancers, cationic or anionic retention agents based on synthetic polymers and dual systems, filtering agents, other dry paper strength enhancers, fluorescence enhancing agents. Whitening agents, antifoaming agents, biocides and dyes for papermaking. These conventional papermaking fillers may be used in conventional amounts.

  Sizing agents include alkyl ketene dimers (AKD), alkenyl succinic anhydride (ASA), and rosin sizing agents.

  As a retention agent, for example, inorganic microparticles (colloidal silica, bentonite), inorganic polyacrylamide, cationic polyacrylamide, cationic starch, cationic polyethyleneimine or cationic polyvinylamine are considered. Furthermore, arbitrary combinations thereof are conceivable, for example, a dual system composed of a cationic polymer and an anionic microparticle or an anionic polymer and a cationic microparticle is conceivable. In order to achieve a high filler yield, for example, it is recommended to add a retention agent that can be added not only to a high-concentration stock but also to a low-concentration stock.

  A dry paper strength enhancer is understood as a synthetic dry strength enhancer such as polyvinylamine, polyethyleneimine, glyoxylated polyacrylamide (PAM), amphoteric polyacrylamide or a natural dry strength enhancer such as starch. Should.

  In the paper machine, the absolute drying rate is adjusted when passing through the press part. In the press part, the wet fiber web is transferred onto the press felt by a suction pick-up device (suction roll or static vacuum element). The role of the press felt is to transport the fiber web through various modified press nips. The absolute dry rate of this web is up to 55% depending on the design of the press part and the composition of the stock. The rate of dryness then increases with the pressure applied to the paper web passing in the press. The pressure, and thus the dry rate of the paper web, can vary over a relatively wide range in many paper machines.

  The water-soluble polymer used according to the invention is obtained by Hofmann degradation of an acrylamide-containing polymer and / or a methacrylamide-containing polymer, optionally followed by postcrosslinking.

Prepolymers These acrylamide-containing polymers and / or methacrylamide-containing polymers (hereinafter also referred to as prepolymers) are obtained by radical copolymerization of monomer mixtures containing acrylamide and / or methacrylamide.

  Monomeric acrylamide and methacrylamide are particularly preferably based on the monomer composition of this prepolymer alone or in a proportion of 10 mol% to 100 mol%, preferably in a proportion of 20 to 90 mol%. As a mixture at a ratio of 30 to 80 mol%, it is contained in a form introduced by polymerization.

Preferably, the monomer mixture has the following composition, including:
a) acrylamide and / or methacrylamide (monomer a),
b) optionally one or more monoethylenically unsaturated monomers, wherein the corresponding structural units of the monomers in the polymer are stable under the Hofmann decomposition reaction conditions, and / or DADMAC (diallyldimethyl) Ammonium chloride) (monomer b),
(C) optionally one or more compounds having two or more ethylenically unsaturated groups, wherein the corresponding structural units of said compounds in said polymer are stable under Hofmann decomposition reaction conditions, In this case, DADMAC is not included (monomer c).

Monoethylenically unsaturated monomers, in which the corresponding structural units of the monomers in the polymer are stable under the Hofmann decomposition reaction conditions, are, for example, α, β-ethylenically unsaturated mono- and dicarboxylic acids. Nitriles, such as amides of acrylonitrile and methacrylonitrile, α, β-ethylenically unsaturated monocarboxylic acids and their N-alkyl- and N, N-dialkyl derivatives, N-vinyl lactams, nitrogen-containing heterocycles, vinyl aromatic compounds , C ₂ -C ₈ monoolefins, α, β-ethylenically unsaturated mono- and dicarboxylic acids and salts thereof, α, β-ethylenically unsaturated mono- and dicarboxylic acid anhydrides, ethylenically unsaturated sulfonic acids and Salts thereof, ethylenically unsaturated phosphonic acids and salts thereof.

  Examples of representatives of this group (b) are N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, n-propyl (meth) acrylamide, N- (n-butyl) (meth) acrylamide, tert. -Butyl (meth) acrylamide, n-octyl (meth) acrylamide, 1,1,3,3-tetramethylbutyl (meth) acrylamide, ethylhexyl (meth) acrylamide, N, N-dimethylacrylamide, Ν, Ν-dimethylmethacryl Amides, N-vinylformamide, N-vinylacetamide, N-methyl-N-vinylacetamide and mixtures thereof. Further suitable as the monomer (b) are N- [2- (dimethylamino) ethyl] acrylamide, N- [2- (dimethylamino) ethyl] methacrylamide, N- [3- (dimethylamino) propyl. ] Acrylamide, N- [3- (dimethylamino) propyl] methacrylamide, N- [4- (dimethylamino) butyl] acrylamide, N- [4- (dimethylamino) butyl] methacrylamide, N- [2- ( Diethylamino) ethyl] acrylamide, N- [2- (diethylamino) ethyl] methacrylamide and mixtures thereof.

Suitable monomers (b) are furthermore N-vinyl lactams and derivatives thereof, which can have, for example, one or more C ₁ -C ₆ alkyl substituents (as defined above). .

  This includes N-vinylpyrrolidone, N-vinylpiperidone, N-vinylcaprolactam, N-vinyl-5-methyl-2-pyrrolidone, N-vinyl-5-ethyl-2-pyrrolidone, N-vinyl-6-methyl- 2-piperidone, N-vinyl-6-ethyl-2-piperidone, N-vinyl-7-methyl-2-caprolactam, N-vinyl-7-ethyl-2-caprolactam and mixtures thereof are included.

  Furthermore, N-vinylimidazole and alkylvinylimidazole are suitable as the monomer (b), and in particular, methylvinylimidazole such as 1-vinyl-2-methylimidazole, 3-vinylimidazole-N-oxide, 2-vinyl. Pyridine-N-oxide, 4-vinylpyridine-N-oxide and betaine derivatives and quaternized products of these monomers are suitable.

  Furthermore, diallyldimethylammonium chloride (DADMAC) is suitable.

  Further suitable monomers are furthermore ethylene, propylene, isobutylene, butadiene, styrene, α-methylstyrene, vinyl acetate, vinyl propionate, vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride and mixtures thereof.

Furthermore, monomers having at least one acid functional group, ie having at least one sulfonic acid group, phosphonic acid group or carboxylic acid group are suitable. Furthermore, salts of the above compounds are suitable. Illustrative examples include:
Vinylsulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, styrene sulfonic acid, acrylamido methylene phosphonic acid, 2-acrylamido-2-methylpropanesulfonic acid, vinylphosphonic _{acid, CH 2 = CH-NH-} CH 2 -PO 3 H Vinylphosphonic acid monomethyl ester, allylphosphonic acid, allylphosphonic acid monomethyl ester, acrylamidomethylpropylphosphonic acid.

  Similarly, monoethylenically unsaturated carboxylic acids having 3 to 8 C atoms, and water-soluble salts of these carboxylic acids, such as alkali metal, alkaline earth metal or ammonium salts, and monoethylenically unsaturated Carboxylic anhydride is suitable. Examples of such monomers include acrylic acid, methacrylic acid, dimethacrylic acid, ethacrylic acid, α-chloroacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, mesaconic acid, citraconic acid, glutaconic acid, aconite. Acids, methylenemalonic acid, allylic acetic acid, vinyl acetic acid and crotonic acid are included.

  These monomers with acid groups may be present in an unneutralized, partially neutralized or fully neutralized form, in which the phosphonic acid has 1 or 2 protons May be neutralized with a suitable base.

  Suitable bases for partial or complete neutralization of the acid groups of the monomers are, for example, alkali metal salts, alkaline earth metal salts, ammonia, amines and / or alkanolamines. Examples of this are sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, magnesium hydroxide, magnesium oxide, calcium hydroxide, calcium oxide, triethanolamine, ethanolamine and morpholine. It is.

  The monomers of this group (b) can be used alone or in admixture.

  Preferred monoethylenically unsaturated monomers, in which the corresponding structural units of the monomers in the polymer are stable under the Hofmann decomposition reaction conditions, are for example α, β-ethylenically unsaturated mono- and dicarboxylic acids Nitriles such as acrylonitrile and methacrylonitrile, amides of α, β-ethylenically unsaturated monocarboxylic acids and their N-alkyl- and N, N-dialkyl derivatives, N-vinyl lactam and DADMAC.

  The prepolymer is one or more monoethylenically unsaturated monomers, wherein the monomer (monomer b) in which the corresponding structural unit of the monomer in the polymer is stable under the Hofmann decomposition reaction conditions, Preferably at least 5 mol%, preferably at least 10 mol% and preferably at most 90 mol%, preferably at most 70 mol%, in particular preferred forms at most, relative to the total number of moles (a and b) 50 mol% is contained after polymerization.

  In addition, the prepolymer is a compound having two or more ethylenically unsaturated groups, wherein the corresponding structural unit of the compound in the polymer is stable under the Hofmann decomposition reaction conditions, Up to 5% by weight, preferably up to 3% by weight, in particular up to 1% by weight, very particularly preferably up to 1% by weight and at least 0.0001% by weight, based on the total weight of monomers a and b used in the polymerization, In particular, at least 0.001% by weight can be contained in a polymerized form, without DADMAC (monomer c).

  Such a prepolymer by copolymerization of a compound having two or more ethylenically unsaturated groups, wherein the corresponding structural unit of the compound in the polymer is stable under the Hofmann decomposition reaction conditions. The transformation is achieved using, for example, methylene bisacrylamide, triallylamine, tetraallylammonium chloride or N, N′-divinylpropylene urea.

Particularly preferably, the monomer mixture used in the preparation of the prepolymer has the following composition:
30 to 95 mol% of acrylamide and / or methacrylamide (monomer a), and one or more monoethylenically unsaturated monomers, the corresponding structural units of the monomers in the polymer being reaction conditions for Hofmann decomposition 5 to 70 mol% of a monomer that is stable below and / or diallyldimethylammonium chloride (monomer b),
And one or more compounds having two or more ethylenically unsaturated groups, wherein the corresponding structural unit of the compound in the polymer is stable under Hofmann decomposition reaction conditions, the monomer a and Up to 1.0 mass% with respect to the total mass of b.

In a further preferred embodiment, the monomer mixture used for the preparation of the prepolymer has the following composition:
Acrylamide and / or methacrylamide is 50-90 mol% and one or more monoethylenically unsaturated monomers, the corresponding structural units of the monomers in the polymer being stable under the Hoffmann decomposition reaction conditions. 10 to 50 mol% of a certain monomer and / or diallyldimethylammonium chloride (monomer b),
And one or more compounds having two or more ethylenically unsaturated groups, wherein the corresponding structural unit of the compound in the polymer is stable under Hofmann decomposition reaction conditions, the monomer a and Up to 1.0 mass% with respect to the total mass of b.

In particular, a monomer mixture having the following composition is preferred for the production of the prepolymer:
Acrylamide and / or methacrylamide (monomer a), 60-80 mol%,
Diallyldimethylammonium chloride (monomer b), 20-40 mol%,
And optionally, one or more compounds selected from methylene bisacrylamide, triallylamine, tetraallylammonium chloride, N, N′-divinylpropyleneurea are added in an amount of 0.001 to 0.001 based on the total amount of monomer a and monomer b. 0.1% by mass.

  The prepolymer can be produced by a solution polymerization method, a precipitation polymerization method, a suspension polymerization method, a gel polymerization method or an emulsion polymerization method. A solution polymerization method in an aqueous medium is preferred. Suitable aqueous media are water and mixtures of water and at least one water-miscible solvent such as alcohols such as methanol, ethanol, n-propanol, isopropanol.

  The polymerization temperature is preferably in the range of about 30 to 200 ° C, particularly preferably in the range of 40 to 110 ° C. The polymerization is usually carried out at atmospheric pressure, but can proceed under reduced pressure or elevated pressure. A suitable pressure range is 0.1 to 10 bar.

  The monomer (b) having an acid group is preferably used in a salt form.

  For the production of the polymer, the monomer can be polymerized with a radical-forming initiator.

As initiators for radical polymerization, conventional peroxo compounds and / or azo compounds can be used for this purpose, such as alkali metal peroxodisulfates, ammonium peroxodisulfates, diacetyl peroxide, dibenzoyl peroxide, succinyl peroxide, Tert-butyl peroxide, tert-butyl perbenzoate, tert-butyl perpivalate, tert-butyl peroxy-2-ethylhexanoate, tert-butyl permaleate, cumyl hydroperoxide, diisopropyl peroxodicarbamate, bis- (O-toluoyl) peroxide, didecanoyl peroxide, dioctanoyl peroxide, dilauroyl peroxide, tert-butyl perisobutyrate, tert-butyl Peracetate, di-tert-amyl peroxide, tert-butyl hydroperoxide, azo-bis-isobutyronitrile, azo-bis- (2-amidinopropane) dihydrochloride or 2-2'-azo-bis- (2- Methylbutyronitrile) can be used. Initiator mixtures or redox, such as ascorbic acid / iron (II) sulfate / sodium peroxodisulfate, tert-butyl hydroperoxide / sodium disulfite, tert-butyl hydroperoxide / sodium hydroxymethanesulfinate, H ₂ O ₂ / CuI Initiator systems are also suitable.

  In order to adjust the molecular weight, the polymerization can be carried out in the presence of at least one regulator. As modifiers customary compounds known to the person skilled in the art, for example sulfur compounds such as mercaptoethanol, 2-ethylhexyl thioglycolate, thioglycolic acid, sodium hypophosphite, formic acid or dodecyl mercaptan, and tribromochloromethane, or Other compounds having a regulating effect on the molecular weight of the resulting polymer can be used.

  The molar mass of the water-soluble prepolymer is, for example, at least 50,000 daltons, preferably at least 100,000 daltons, in particular at least 500,000 daltons. Therefore, the molar mass of the prepolymer is, for example, 50,000 to 10,000,000, preferably 100,000 to 5,000,000 (for example, measured by a light scattering method). This molar mass range corresponds, for example, to a K value of 50 to 300, preferably 70 to 250 (measured by H. Fikentscher in a 5% strength saline solution at 25 ° C. and a polymer concentration of 0.1% by weight. ).

Hoffman decomposition Hoffman decomposition (also called Hoffman rearrangement) is interpreted by those skilled in the art as decomposition of primary acid amides to amines with consumption of carbon atoms (Roempp Online, Version 3.12). In Hofmann decomposition, the amide group of the prepolymer reacts with hypohalite under alkaline conditions, and then the carbamate formed is decarboxylated by acidification to yield an amino group.

  Such polymers are known for example from EP-A-0377313 and WO-A-2006 / 075115. The production of polymers containing vinylamine groups is dealt with in detail, for example in the examples of WO-A-2006 / 075115, page 4, line 25 to page 10, line 22, and pages 13 and 14. The content is clearly quoted.

  The Hoffman decomposition is preferably performed in an aqueous solution. 0.1 to 2.0, preferably 0.8 to 1.1, particularly preferably 1.0 molar equivalent of hypohalite is used per mole equivalent of amide group. The strong base is used in an amount of 1.0 to 4.0 molar equivalents, preferably 1.5 to 3.0 molar equivalents, particularly preferably 2.0 to 2.5 molar equivalents per molar equivalent of the amide group. .

  As hypohalite, for example, sodium hypochlorite (NaOCl) and sodium hypobromite (NaOBr) are used, with NaOCl being preferred. Alkali metal hydroxides, alkaline earth metal hydroxides and alkaline earth metal oxides are used as strong bases.

  The Hofmann decomposition of the polymer is, for example, as a stabilizer in order to prevent side reactions between the resulting amino group and the amide group of the starting polymer, optionally within a temperature range of -15 to 90 ° C, preferably -5 to 40 ° C. In the presence of a quaternized ammonium salt. After completion of the reaction with the alkali / alkali metal hypochlorite, this aqueous reaction solution is introduced into a reactor charged with acid for decarboxylation of the reaction product. The pH value of the reaction product containing vinylamine units is adjusted to a value of 2-7.

  Water-soluble polymers obtained by Hofmann degradation of acrylamide-containing polymers and / or methacrylamide-containing polymers can be used in the process according to the invention.

  According to a further variant, the polymer obtained by Hofmann degradation of an acrylamide-containing polymer and / or a methacrylamide-containing polymer is further postcrosslinked.

Post-crosslinking To increase the molecular weight of the Hoffman-decomposed polymer and to obtain a branched polymer structure, the Hoffman-decomposed polymer can be subsequently reacted with a cross-linking agent. In this case, the crosslinking agent may be interpreted as a compound having at least two reactive groups capable of reacting with the primary amino group of the Hoffman product.

  Cross-linking agents such as polyfunctional epoxides such as bisglycidyl ethers of oligoethylene oxide, bisglycidyl ethers of polyethylene oxide, or bisglycidyl ethers of other polyfunctional alcohols such as glycerin or sugars, polyfunctional carboxylic acid esters , Multifunctional isocyanate, multifunctional acrylic ester, multifunctional methacrylate ester, multifunctional acrylic amide, multifunctional methacrylate, epichlorohydrin, multifunctional acid halide, multifunctional nitrile Α, ω-chlorohydrin ethers of oligoethylene oxide, α, ω-chlorohydrin ethers of polyethylene oxide, or α, ω-chlorohydrin ethers of other polyfunctional alcohols such as glycerin or sugars, divinyl Sulfo , Maleic acid or .omega.-halocarboxylic acid chlorides anhydrides, polyfunctional haloalkanes, particularly alpha, .omega.-dichloro alkanes and carbonates, such as ethylene carbonate or propylene carbonate is applicable. Other crosslinking agents are described in WO-A-97 / 25367, pages 8-16.

  As cross-linking agents, polyfunctional epoxides such as bisglycidyl ethers of oligoethylene oxide, bisglycidyl ethers of polyethylene oxide or other polyfunctional alcohols such as glycerin or sugars are preferred.

  The crosslinking agent is optionally used in an amount of up to 5.0% by weight, preferably 20 ppm to 2% by weight, based on the polymer obtained by Hofmann decomposition.

  The method according to the invention allows a more seamless operation of the paper machine. The paper web or paper sheet produced by this method clearly shows a higher initial wet paper strength.

  The following examples illustrate the invention. The percentages in these examples are percentages by weight unless otherwise noted.

Polymer production takes place in three consecutive steps:
a) production of prepolymers,
b) Hoffmann decomposition of the prepolymer,
And optionally postcrosslinking.

Production of polymer I a) Production of prepolymer I (acrylamide 70 mol% and DADMAC (diallyldimethylammonium chloride) 30 mol%, unbranched) with anchor stirrer, reflux condenser, internal thermometer and nitrogen feed tube Further, 295.5 g of distilled water, 189.6 g of a 65 mass% aqueous solution of DADMAC and 1.0 g of 75 mass% phosphoric acid were charged into a 2 L glass apparatus. The pH was adjusted to 3 by the addition of 0.4 g sodium hydroxide. Oxygen was removed from the initial charge by introducing nitrogen while the initial charge was heated to a polymerization temperature of 75 ° C. At the same time, the following feeds were produced:
Feed 1: Mixture from 253.0 g of 50% by weight acrylamide solution, 60.0 g of distilled water and 0.9 g of sodium hydroxide.
Feed 2: 100 g of 0.6% by weight aqueous bisulfite solution.
Feed 3: 100 g of 0.88 mass% sodium persulfate aqueous solution.

  These three feeds were started simultaneously. Feed 1 was fed over a 2 hour period, while feeds 2 and 3 were fed over a 5 hour period. The temperature of the mixture was then raised to 85 ° C. After the end of feeds 2 and 3, the batch was held at 85 ° C. for an additional hour and then cooled.

  A clear viscous prepolymer solution having a solids content of 25.6% by weight and a viscosity of 50000 mPas (Brookfield LV viscosity, spindle 4, 6 rpm, RT) was obtained.

b) Hoffmann decomposition of the prepolymer 250.0 g of the prepolymer I obtained after a) is placed in a three-necked flask equipped with an internal thermometer and a blade stirrer and is always stirred with an ice / salt mixture. While cooling to 8 ° C.

  The following feeds were produced: 234.5 g of 14.1 wt% NaOCl aqueous solution and 20.5 g of distilled water were charged into a glass beaker and cooled to 5 ° C. using an ice bath. With constant stirring, 71.1 g of 50% by weight caustic soda solution was slowly added dropwise so that the temperature could be kept below 10 ° C.

  This feed was added dropwise from a cooled addition funnel (below 10 ° C.) over 80 minutes into the cooled prepolymer initial charge such that the temperature was maintained at 8-10 ° C. during the addition. The reaction mixture was then heated to 20 ° C. within 10 minutes and held at 20 ° C. for 30 minutes. Subsequently, 558.1 g of this mixture was added dropwise to 135 g of 37% hydrochloric acid with constant stirring, and strong gas evolution was observed. Subsequently, the pH of the obtained solution was adjusted to pH 3.5 using 10.0 g of 25 mass% sodium hydroxide solution.

  A clear and slightly viscous solution of polymer I having a polymer content of 8.6% by weight and a viscosity of 39 mPas (Brookfield LV viscosity, spindle 1, 60 rpm, RT) was obtained.

Production of polymer II (post-crosslinking)
309.8 g of Polymer I was charged into a 500 mL three-necked flask equipped with a blade stirrer and adjusted to pH 8.5 by addition of 6.8 g of 50% by weight sodium hydroxide solution. The mixture was then heated to 45 ° C. and 0.29 g of Grillbond G 1701 (EMS) was added. After stirring for 30 minutes at 45 ° C., the temperature was increased to 55 ° C. and a batch was obtained at 55 ° C. for 2 hours. Within this time, an increase in viscosity was observed. After 2 hours, the batch was cooled to room temperature and the pH value was adjusted to 3.0 by the addition of 8.0 g of 37% hydrochloric acid.

  A clear and slightly viscous solution of polymer II with a polymer content of 8.2% by weight and a viscosity of 190 mPas (Brookfield LV viscosity, spindle 2, 60 rpm, RT) was obtained.

Preparation of Polymer III a) Preparation of Prepolymer III (70 mol% acrylamide and 30 mol% DADMAC, triallylamine as monomer c) 2 L glass with anchor stirrer, reflux condenser, internal thermometer and nitrogen inlet tube In the apparatus, 155.8 g of distilled water, 189.6 g of a 65% by mass aqueous solution of DADMAC and 1.0 g of 75% by mass phosphoric acid were charged. The pH was adjusted to 3 by the addition of 0.4 g NaOH. Oxygen was removed from the initial charge by introducing nitrogen while the initial charge was heated to a polymerization temperature of 75 ° C.

The following feeds were prepared:
Feed 1: 0.5 g triallylamine was dissolved in 160.0 g distilled water with the addition of 0.75 g 75% by weight phosphoric acid. Subsequently, 253.0 g of 50 mass% acrylamide solution was added, and pH was adjusted to 4.0 using 0.4 g of 25 mass% sodium hydroxide solution.
Feed 2: 0.6 g% by weight aqueous bisulfite solution 120 g.
Feed 3: 0.86 mass% sodium persulfate aqueous solution 120.6 g.

  These three feeds were started simultaneously. Feed 1 was added in 3 hours, while feeds 2 and 3 were fed in 6 hours. After the end of feed 2 addition, the temperature was increased to 85 ° C., held at this temperature for an additional hour, and then cooled.

  A clear and viscous prepolymer solution having a solids content of 25.5% and a viscosity of 15800 mPas (Brookfield LV viscosity, spindle 4, 6 rpm, RT) was obtained.

b) Hoffmann decomposition of prepolymer III 250.0 g of prepolymer III from a) was charged into a three-necked flask equipped with a blade stirrer and an internal thermometer and constantly stirred with an ice / salt mixture at 8 ° C. Cooled to.

  At the same time, the following feed was produced: For that purpose, 234.5 g of 14.1% by weight NaOCl aqueous solution and 20.5 g of distilled water were charged into a glass beaker and cooled to 5 ° C. using an ice bath. With constant stirring, 71.1 g of 50% by weight caustic soda solution was slowly added dropwise so that the temperature could be kept below 10 ° C.

  This feed was added dropwise from a cooled addition funnel (below 10 ° C.) in the initial charge over 80 minutes such that the temperature could be kept within the range of 8-10 ° C. during the addition. The reaction mixture was then heated to 20 ° C. within 10 minutes and held at 20 ° C. for 60 minutes. Next, 566.2 g of this mixture was added dropwise to 135 g of 37% hydrochloric acid with constant stirring, with strong gas evolution observed. Subsequently, the pH value of the obtained solution was adjusted to pH 3.5 using 12.2 g of 25 mass% sodium hydroxide solution. A clear and slightly viscous solution of Prepolymer III having a polymer content of 8.6% by weight and a viscosity of 23 mPas (Brookfield LV viscosity, spindle 1, 60 rpm, RT) was obtained.

Polymer IV (post-crosslinking)
301.8 g of Polymer III was charged into a 500 mL three-necked flask equipped with a blade stirrer and adjusted to pH 8.5 by the addition of 6.2 g of 50% by weight caustic soda solution. The mixture was then heated to 45 ° C. and 0.43 g of Grillbond G 1701 (EMS) was added. After stirring for 30 minutes at 45 ° C., the temperature was raised to 55 ° C. and a batch was obtained at 55 ° C. for 3 hours. Within this time, an increase in viscosity was observed. After 3 hours, the batch was cooled to room temperature and the pH value was adjusted to 3.0 by adding 7.4 g of 37% hydrochloric acid. A clear and slightly viscous solution of polymer IV with a polymer content of 8.2% by weight and a viscosity of 419 mPas (Brookfield LV viscosity, spindle 2, 60 rpm, RT) was obtained.

Production of polymer V a) Production of prepolymer V (70 mol% acrylamide and 30 mol% DADMAC, triallylamine as monomer c) 2 L glass with anchor stirrer, reflux condenser, internal thermometer and nitrogen feed tube In the apparatus, 155.8 g of distilled water, 189.6 g of a 65% by mass aqueous solution of DADMAC and 1.0 g of 75% by mass phosphoric acid were charged. The pH was adjusted to 3 by the addition of 0.4 g NaOH. Oxygen was removed from the initial charge by introducing nitrogen while the initial charge was heated to a polymerization temperature of 75 ° C. At the same time, the following feeds were prepared:
Feed 1: 0.25 g triallylamine was dissolved in 160.0 g distilled water with the addition of 0.75 g 75% by weight phosphoric acid. Subsequently, 253.0 g of 50 mass% acrylamide solution was added, and pH was adjusted to 4.0 using 0.6 g of 25 mass% sodium hydroxide solution.
Feed 2: 0.6 g% by weight aqueous bisulfite solution 120 g.
Feed 3: 0.86 mass% sodium persulfate aqueous solution 120.6 g.

  These three feeds were started simultaneously. Feed 1 was added in 3 hours, while feeds 2 and 3 were fed in 6 hours. The temperature was raised to 85 ° C. after the end of Feed 2. After the end of feeds 2 and 3, the batch was held at 85 ° C. for an additional hour and then cooled. A clear and viscous prepolymer solution having a solids content of 25.5% and a viscosity of 12400 mPas (Brookfield LV viscosity, spindle 4, 6 rpm, RT) was obtained.

b) Hoffmann decomposition of the prepolymer 250.0 g of prepolymer V from a) is placed in a three-necked flask equipped with a blade stirrer and an internal thermometer and kept at 8 ° C. with constant stirring using an ice / salt mixture. Cooled down.

At the same time, the following feeds were produced:
14.4.5% NaOCl aqueous solution (234.5 g) and distilled water (20.5 g) were charged into a glass beaker and cooled to 5 ° C. using an ice bath. With constant stirring, 71.1 g of 50% by weight NaOH solution was slowly added dropwise so that the temperature could be kept below 10 ° C.

  This feed was added dropwise from a cooled addition funnel (below 10 ° C.) in the initial charge over 80 minutes such that the temperature could be kept within the range of 8-10 ° C. during the addition. The reaction mixture was then heated to 20 ° C. within 10 minutes and held at 20 ° C. for 60 minutes. Next, 566.2 g of this mixture was added dropwise to 135 g of 37% hydrochloric acid with constant stirring, with strong gas evolution observed. Subsequently, the pH of the obtained solution was adjusted to pH 3.5 using 16.0 g of 25 mass% sodium hydroxide solution. A clear and slightly viscous solution of Prepolymer V having a polymer content of 8.5% and a viscosity of 22 mPas (Brookfield LV viscosity, spindle 1, 60 rpm, RT) was obtained.

Polymer VI (post-crosslinking)
314.4 g of polymer V was charged into a 500 mL three-necked flask equipped with a blade stirrer and adjusted to pH 8.5 by addition of 6.4 g of 50% by weight caustic soda solution. The mixture was then heated to 45 ° C. and 0.44 g of Grillbond G 1701 (EMS) was added. After stirring for 30 minutes at 45 ° C., the temperature was raised to 55 ° C. and a batch was obtained at 55 ° C. for 3 hours. Within this time, an increase in viscosity was observed. After 3 hours, the batch was cooled to room temperature and the pH was adjusted to 3.0 by addition of 7.6 g of 37% hydrochloric acid.

  A clear and slightly viscous solution of polymer VI having a polymer content of 8.1% and a viscosity of 190 mPas (Brookfield LV viscosity, spindle 2, 60 rpm, RT) was obtained.

Polymer VII (acrylamide 85 mol% and acrylic acid 15 mol%)
The Hoffman product C-4 was reproduced in accordance with JP 63042998 (see table on page 624).

Polymer VIII (not according to the invention) (comparative example corresponds to polymer I from EP application number 11170740.2)
400 g of deionized water was charged into a 2 L five-necked flask equipped with an anchor stirrer, thermometer, down cooler, and nitrogen feed tube. In addition, the following feeds were prepared:
Feed 1: The following ingredients were mixed in a glass beaker:
250 g of deionized water,
95.6 g of a 50% by weight aqueous solution of acrylamide,
121.9 g of an 80% by weight aqueous solution of acryloyloxyethyltrimethylammonium chloride,
148.1 g of a 32% by weight aqueous solution of sodium acrylate,
0.2 g of a 1% by weight aqueous solution of diethylenetriaminepentaacetic acid.
The pH was adjusted to 4.1 by adding about 32 g of 37% hydrochloric acid.
Feed 2: 60.0 g of a 1% by weight aqueous solution of 2,2′-azobis (2-amidinopropane) -dihydrochloride.
Feed 3: 16.5 g of a 1% by weight aqueous solution of 2,2′-azobis (2-amidinopropane) -dihydrochloride.

  The initial charge was heated to 63 ° C. and the pressure was reduced using a water jet pump until the water just started to boil. Feeds 1 and 2 were started simultaneously, feed 1 was added to the initial charge at a constant internal temperature for 2 hours and feed 2 for 3 hours. After the end of feed 2, the reaction was held at 63 ° C. for an additional hour and then heated to 72 ° C., correspondingly reducing the vacuum. The reaction mixture was held at 72 ° C. for an additional 2 hours, after which Feed 3 was added in one portion and post-polymerized at 72 ° C. for an additional 2 hours. The vacuum was then released and the batch was diluted with 500 g of deionized water and cooled to room temperature. During the entire polymerization, 208 g of water was distilled off.

A colorless, clear and viscous solution of polymer VIII having a composition of 40 mol% acrylamide, 30 mol% acryloyloxyethyltrimethylammonium chloride and 30 mol% sodium acrylate was obtained.
Solid content: 14.5% by mass
Viscosity: 10600 mPas (Brookfield, spindle 7, 50 rpm, room temperature)
K value: 120 (0.1% solution of polymer in 5% by weight saline solution).

Polymer IX (not according to the invention): (Comparative example corresponds to polymer II from EP application number 11170740.2)
400 g of deionized water was charged into a 2 L five-necked flask equipped with an anchor stirrer, thermometer, down cooler, and nitrogen feed tube. In addition, the following feeds were prepared:
Feed 1: The following ingredients were mixed in a glass beaker:
250 g of deionized water,
119.5 g of a 50% by weight aqueous solution of acrylamide,
113.8 g of an 80% by weight aqueous solution of acryloyloxyethyltrimethylammonium chloride,
108.6 g of a 32% by weight aqueous solution of sodium acrylate,
0.2 g of a 1% by weight aqueous solution of diethylenetriaminepentaacetic acid.
The pH was adjusted to 4.1 by adding about 38 g of 37% hydrochloric acid.
Feed 2: 63.5 g of a 1% aqueous solution of 2,2′-azobis (2-amidinopropane) -dihydrochloride.
Feed 3: 17.0 g of a 1% aqueous solution of 2,2′-azobis (2-amidinopropane) -dihydrochloride.

  The initial charge was heated to 66 ° C. and the pressure was reduced using a water jet pump until the water just started to boil. Feeds 1 and 2 were started simultaneously, feed 1 was added to the initial charge at a constant internal temperature for 2 hours and feed 2 for 3 hours. After the end of feed 2, the reaction was held at 66 ° C. for an additional hour and then heated to 78 ° C., correspondingly reducing the vacuum. The reaction mixture was held at 78 ° C for an additional 2 hours, after which Feed 3 was added in one portion and post-polymerized at 78 ° C for an additional 2 hours. The vacuum was then released and the batch was diluted with 500 g of deionized water and cooled to room temperature. During the entire polymerization, 200 g of water was distilled off.

A colorless clear viscous solution of polymer IX having a composition of 50 mol% acrylamide, 28 mol% acryloyloxyethyltrimethylammonium chloride and 22 mol% sodium acrylate was obtained.
Solid content: 14.1% by mass
Viscosity: 42000 mPas (Brookfield, spindle 7, 50 rpm, room temperature)
K value: 125 (0.1% solution of polymer in 5% saline solution).

Polymer X (not according to the invention): (corresponds to polymer III from EP application number 11170740.2)
400 g of deionized water was charged into a 2 L five-necked flask equipped with an anchor stirrer, thermometer, down cooler, and nitrogen feed tube. In addition, the following feeds were prepared:
Feed 1: The following ingredients were mixed in a glass beaker:
250 g of deionized water,
71.7 g of a 50% by weight aqueous solution of acrylamide,
130.1 g of an 80% by weight aqueous solution of acryloyloxyethyltrimethylammonium chloride,
187.8 g of a 32% by weight aqueous solution of sodium acrylate,
0.2 g of a 1% by weight aqueous solution of diethylenetriaminepentaacetic acid.
The pH was adjusted to 4.1 by adding about 34 g of 37% hydrochloric acid.
Feed 2: 60.3 g of a 1% by weight aqueous solution of 2,2′-azobis (2-amidinopropane) -dihydrochloride.
Feed 3: 16.0 g of a 1% by weight aqueous solution of 2,2′-azobis (2-amidinopropane) -dihydrochloride.

  The initial charge was heated to 63 ° C. and the pressure was reduced using a water jet pump until the water just started to boil. Feeds 1 and 2 were started simultaneously, feed 1 was added to the initial charge at a constant internal temperature for 2 hours and feed 2 for 3 hours. After the end of feed 2, the reaction was held at 63 ° C. for an additional hour and then heated to 72 ° C., correspondingly reducing the vacuum. The reaction mixture was held at 72 ° C. for an additional 2 hours, after which Feed 3 was added in one portion and post-polymerized at 72 ° C. for an additional 2 hours. The vacuum was then released and the batch was diluted with 500 g of deionized water and cooled to room temperature. During the entire polymerization, 200 g of water was distilled off.

A colorless clear viscous solution of polymer X having a composition of 30 mol% acrylamide, 32 mol% acryloyloxyethyltrimethylammonium chloride and 38 mol% sodium acrylate was obtained.
Solid content: 14.8% by mass
Viscosity: 12000 mPas (Brookfield, Spindle 7, 50 rpm, room temperature)
K value: 117 (0.1% solution of polymer in 5% by weight saline solution).

Testing of the above polymers I to X to improve the initial wet paper strength of the paper In order to simulate the sheet forming process on a laboratory scale, the fibrous material concentration of the low-concentration stock in the examples is 3.5 g. It is necessary to adjust to / l.

Pretreatment of the fibrous material suspension Bleached birchwood sulfate was beaten in a laboratory pulper at a fibrous material concentration of 4% so as to be free of floc until a freeness of 30 ° SR was reached. . Then, this beaten stock, optical brightener ^{(Blankophor (R) PSG)} and fully cooked cationic starch ^{(HiCat (R) 5163A)} was added, allowed to act for 5 minutes. The cationic starch was cooked in advance as a 10% starch slurry in a jet digester at 130 ° C. for a residence time of 1 minute. The metering amount of the optical brightener was 0.5% by mass of the commercial product with respect to the dry rate of the fibrous substance suspension. The metering amount of the cationic starch was 0.8% (solid) of starch with respect to the absolute dry rate of the fibrous material suspension. The fibrous material content of the fibrous material suspension after addition of starch and optical brightener was 3.5% (35 g / l).

Examples 1-7
Seven glass beakers were filled with 50 g of each of the above pretreated fibrous material suspensions. To each of the glass beakers, 1.75 g of each 1% by mass aqueous solution of each of the above polymers I to VII was metered in while slightly stirring the fibrous material suspension (based on the fibrous material (solid)). Equivalent to 1% polymer (solid)). The fibrous material suspension was then diluted to a fibrous material concentration of 0.35% by adding water. Thereafter, 20% by mass carbonate pigment slurry (PCC, Syncarb F474 from Omya) was added. The amount of pigment suspension (corresponding to the filler suspension) added was adjusted in several preliminary tests so that the pigment content in the laboratory sheet subsequently formed was about 20%. Two minutes after the pigment addition, this fibrous material suspension was processed according to ISO 5269/2 on a Rapid-Corsen sheet making machine to obtain a sheet having a basis weight of 100 g / m ² . The wet sheet was then removed from the wire frame and placed between two suction felts. The suction felt and the wet paper were then compressed together in a static press with a pressing pressure of 6 bar. In that case, it compressed until the solid content of the wet sheet | seat became 50 mass% each time.

Examples 8, 9 and 10 (not according to the invention)
Three glass beakers were each filled with 50 g of the pretreated fibrous material suspension. To each of these glass beakers, 1.75 g of each 1% by weight aqueous solution of the above polymers I to III was metered in while slightly stirring the fibrous material suspension (to the fibrous material (solid)). Equivalent to 1% polymer (solid)). The fibrous material suspension was then diluted to a fibrous material concentration of 0.35% by adding water. Thereafter, 20% by mass carbonate pigment slurry (PCC, Syncarb F474 from Omya) was added. The amount of pigment suspension added was adjusted in several preliminary tests so that the pigment content in the laboratory sheet subsequently formed was about 20%. Two minutes after the pigment addition, this fibrous material suspension was processed according to ISO 5269/2 on a Rapid-Corsen sheet making machine to obtain a sheet having a basis weight of 100 g / m ² . The wet sheet was then removed from the wire frame and placed between two suction felts. The suction felt and the wet paper were then compressed together in a static press with a pressing pressure of 6 bar. At that time, by adjusting the residence time in the press apparatus, the wet sheet was compressed to the solid content that can be cited from Table 1 each time.

Examples 11, 12, and 13
Three glass beakers were each filled with 50 g of the pretreated fibrous material suspension. To each of these glass beakers, 1.75 g of each 1% by mass aqueous solution of one of the above polymers VIII to X was metered in while slightly stirring the fibrous material suspension (to the fibrous material (solid)). Equivalent to 1% polymer (solid)). The fibrous material suspension was then diluted to a fibrous material concentration of 0.35% by adding water. Thereafter, 20% by mass carbonate pigment slurry (PCC, Syncarb F474 from Omya) was added. The amount of pigment suspension (corresponding to the filler suspension) added was adjusted in several preliminary tests so that the pigment content in the laboratory sheet subsequently formed was about 20%. Two minutes after the pigment addition, this fibrous material suspension was processed according to ISO 5269/2 on a Rapid-Corsen sheet making machine to obtain a sheet having a basis weight of 100 g / m ² . The wet sheet was then removed from the wire frame and placed between two suction felts. The suction felt and the wet paper were then compressed together in a static press with a pressing pressure of 6 bar. In that case, it compressed until the solid content of the wet sheet | seat became 50 mass% each time.

Examples 14, 15 and 16 (not in accordance with the invention, metering in low concentration stock)
Three glass beakers containing 50 g of pretreated fibrous material suspension (high-concentration stock) are diluted to a fibrous material concentration of 0.35% (corresponding to 3.5 g / l) by adding 450 g of water. did.

  1.75 g of each 1% by mass aqueous solution of polymer I, II or III was added per 500 g of this diluted fibrous substance suspension (low concentration paper stock) (1% by mass relative to the fibrous substance (solid)) Equivalent to polymer (solid)).

  Thereafter, each 20% by weight carbonate pigment slurry (PCC, Syncarb F474 from Omya) was added to the mixture. The amount of pigment suspension added was adjusted in several preliminary tests so that the pigment content in the laboratory sheet subsequently formed was about 20%.

Two minutes after the pigment addition, this fibrous material suspension was processed according to ISO 5269/2 on a Rapid-Corsen sheet making machine to obtain a sheet having a basis weight of 100 g / m ² . The wet sheet was then removed from the wire frame and placed between two suction felts. The suction felt and the wet paper were then compressed together in a static press with a pressing pressure of 6 bar. At that time, the paper was compressed until the solid content of the wet sheet reached 50% by mass by adjusting the residence time of the paper in the press apparatus.

Examples 17, 18 (control)
Three glass beakers were each filled with 50 g of the pretreated fibrous material suspension. The fibrous material suspension was then diluted to a fibrous material concentration of 0.35% by adding water. Thereafter, 20% by mass carbonate pigment slurry (PCC, Syncarb F474 from Omya) was added. The amount of pigment suspension (corresponding to the filler suspension) added was adjusted in several preliminary tests so that the pigment content in the laboratory sheet subsequently formed was about 20%. Two minutes after the pigment addition, this fibrous material suspension was processed according to ISO 5269/2 on a Rapid-Corsen sheet making machine to obtain a sheet having a basis weight of 100 g / m ² . The wet sheet was then removed from the wire frame and placed between two suction felts. The suction felt and the wet paper were then compressed together in a static press with a pressing pressure of 6 bar. Varying the compression time produced sheets with various dry rates (see Table 1).

Applied technology test: measurement of initial wet paper strength Initial wet paper strength must be distinguished from paper wet strength and initial wet strength, because these two properties are again determined to be a predetermined water content after drying. This is because it is measured on paper that has been wet. Initial wet paper strength is one of the important parameters when evaluating paper that does not have permanent wet strength. Paper that has been dried and then re-wet has a wet strength that is completely different from the wet paper immediately after passing through the wire and press parts of the paper machine.

  Initial wet paper strength measurements on wet paper are carried out by the Voith method (M. Schwarz and K. Bechtel, “Initiale Gefuegefestigkeit bei der Blattbildung”, Wochenblatt fuer Papierfabrikation 131, p.950-957 (2003) No. .16). For this purpose, the wet sheet was knocked down on a plastic substrate after pressing in a static press and transferred onto a cutting substrate. A test strip having a predetermined length and width was then cut from the sheet. The test strip was pressed under constant pressure until the desired dry rate was reached. For the experiments with paper sheets obtained according to the examples given above, each was adjusted to four dry rates in the range of 42% to 58%. From these values, the initial wet paper web strength at 50% dryness was determined using the approximation method described in the above publication. The actual measurement of initial wet paper strength was carried out in a vertical tensile tester equipped with a special clamping device. The force measured by this tensile tester was converted into a so-called INF index that does not depend on the basis weight. Reference may be made to the above publications for a detailed description of the clamping device, the measurement procedure, the measurement of the dry rate of the paper and the data processing.

  The test results are summarized in Table 1.

Table 1. Results of applied technology tests for producing paper with a filler content of 20% by weight. According to the calculation of the critical dry rate G (x) = G (20), according to the invention, it must be pressed to a solids content of at least 50% by weight:

Claims (10)

In a process for producing paper, board and cardboard comprising dehydration of a filler-containing stock comprising at least one water-soluble polymer under sheet forming in a wire part and paper pressing in a subsequent press part, 20-40 g / at least one water-soluble polymer is metered into a stock having a fibrous material concentration in the range of l, and the stock is then diluted to a fibrous material concentration in the range of 5-15 g / l. The formed stock is dehydrated under sheet formation, and this sheet is pressed to a solid content of G (x)% by mass or more in the press part, and G (x) is

Calculated by
Where x represents the numerical value of the filler content (% by weight) of the dried paper, paperboard or cardboard, and
G (x) represents the numerical value of the minimum solid content (mass%), and the sheet is pressed to this minimum solid content,
In this case, the water-soluble polymer is obtained by subjecting an acrylamide-containing polymer and / or a methacrylamide-containing polymer to Hofmann decomposition and optionally then post-crosslinking.   In a process for producing paper, board and cardboard comprising dehydration of a filler-containing stock comprising at least one water-soluble polymer under sheet forming in a wire part and paper pressing in a subsequent press part, 20-40 g / at least one water-soluble polymer is metered into a stock having a fibrous material concentration in the range of l, and the stock is then diluted to a fibrous material concentration in the range of 5-15 g / l. The formed stock is dehydrated while forming a sheet, and the sheet is pressed to a solid content of 48% by mass or more in a press part. In this case, the water-soluble polymer is an acrylamide-containing polymer and / or a methacrylamide-containing polymer. Said process obtained by Hoffmann decomposition and then post-crosslinking.   The method according to claim 1, wherein the stock contains only a fibrous material having a freeness of 30 ° SR or less as the fibrous material.   4. The method according to claim 1, wherein the water-soluble polymer is added to a paper material having a fibrous substance concentration within a range of 20 to 40 g / l before addition of a filler. 5. The method described.   The method according to any one of claims 1 to 4, wherein the water-soluble polymer is added in an amount of 0.05 to 5.00% by mass with respect to the fibrous substance. The acrylamide-containing polymer and / or methacrylamide-containing polymer is:
a) acrylamide and / or methacrylamide,
b) optionally one or more monoethylenically unsaturated monomers, monomers in which the corresponding structural units of said monomers in the polymer are stable under the Hofmann decomposition reaction conditions, and / or diallyldimethylammonium chloride ,
(C) optionally one or more compounds having two or more ethylenically unsaturated groups, wherein the corresponding structural units of the compounds in the polymer are stable under the Hofmann decomposition reaction conditions 6. Process according to any one of claims 1 to 5, characterized in that it is obtained by radical polymerization of a monomer mixture comprising. The acrylamide-containing polymer and / or methacrylamide-containing polymer is:
Acrylamide and / or methacrylamide is 50-90 mol% and one or more monoethylenically unsaturated monomers, the corresponding structural units of the monomers in the polymer being stable under the Hoffmann decomposition reaction conditions. 10 to 50 mol% of a certain monomer and / or diallyldimethylammonium chloride,
And one or more compounds having two or more ethylenically unsaturated groups, wherein the corresponding structural unit of the compound in the polymer is stable under Hofmann decomposition reaction conditions, the monomer a and The process according to any one of claims 1 to 6, characterized in that it is obtained by radical polymerization of a monomer mixture comprising up to 1.0% by weight with respect to the total weight of b.   The water-soluble polymer decomposes the acrylamide-containing polymer and / or the methacrylamide-containing polymer by Hofmann, and then multi-functional epoxide, polyfunctional carboxylic acid ester, polyfunctional isocyanate, polyfunctional acrylate ester, polyfunctional Methacrylic acid ester, polyfunctional acrylic amide, polyfunctional methacrylic amide, epichlorohydrin, polyfunctional acid halide, polyfunctional nitrile, α, ω-chlorohydrin ether of oligoethylene oxide, polyethylene oxide Selected from α, ω-chlorohydrin ethers, α, ω-chlorohydrin ethers of other multifunctional alcohols, divinyl sulfone, maleic anhydride or ω-halocarboxylic acid chlorides, multifunctional halogen alkanes and carbonates Obtained by post-crosslinking with a cross-linking agent Wherein the method according to any one of claims 1 to 7.   A process according to any one of claims 2 to 8 for producing paper, board and cardboard having a filler content of 17 to 32, wherein the solids content in the press part is at least in the range of 49 to 55. And pressing the method.   9. A method according to any one of claims 2 to 8 for producing paper, board and cardboard having a filler content of 15 or less, wherein the pressing part is pressed to a solids content of at least 48% by weight. Characterized by the above.