NO159492B - POLYMER DISPERSIONS WHICH ARE INPOLYMERIZED FINISHED, NITROGEN CONTAINING MONOMERS AND APPLICATION OF THE DISPERSIONS AS PAPER FOR PAPER. - Google Patents

Abstract

1. A finely divided polymer dispersion which contains polymerized units of nitrogen-containing monomers, and is obtained by a two-stage polymerization reaction, wherein, in the first polymerization stage, a low molecular weight prepolymer, which has a viscosity of from 1.06 to 1.40 (measured in an Ubbelohde viscometer) in a 1% strength solution of a mixture of 99 parts by weight of dimethyl formamide and 1 part by weight of glacial acetic acid at 20 degrees C, is prepared in a water-miscible solvent, which may contain up to 15% by weight of water, in the manner of a solution copolymerization from a monomer mixture which contains (a) per mole of a nitrogen-containing monomer of the formula see diagramm : EP0051144,P13,F1 or see diagramm : EP0051144,P13,F3 where A is O or NH, B is Cn H2n , n being from 1 to 8, R**1 and R**2 are each Cm H2m+1 , m being from 1 to 4, R**3 is H or CH3 , X4 **- is OH**- , Cl**- , Br**- or CH3 -OSO3 H**- , and R**4 is Cm H2m+1 , m being from 1 to 4, (b) 2.5 to 10 moles of at least one nonionic, hydrophobic, ethylenically unsaturated monomer which, if it is polymerized on its own, forms a hydrophobic polymer, (c) 0.5 to 1.5 moles of an ethylenically unsaturated carboxylic acid or maleic anhydride, and (d) 0 to 7 moles of a nonionic, hydrophilic, ethylenically unsaturated monomer, the solution of the prepolymer is diluted with water in a weight ratio of from 1:3 to 1:50 and, in the second polymerization stage, 1 to 32 parts by weight of at least one nonionic, hydrophobic, ethylenically unsaturated monomer, which is the same as monomer (b) of the prepolymer, are polymerized per part by weight of the solution polymer in this polymer solution in the manner of an emulsion polymerization in the presence of a usual amount of a water-soluble polymerization initiator.

Description

From BRD-off. document no. 25 48 393 there are known adhesives

for mass and surface gluing of paper on the basis of anionic polymers in the form of dispersions, which are produced in two stages. In the first step, 30 to 90% by weight of a non-ionic, ethylenically unsaturated monomer is polymerized in aqueous solution together with 70 to 10% by weight of an ethylenically unsaturated C 1 to G carboxylic acid by solution polymerization. In this polymer solution, 90 to 40% by weight, based on 10 to 60% by weight of the solution copolymer, is polymerized by emulsion polymerization of a mixture of ethylenically unsaturated, mutually copolymerizable monomers, which when polymerized alone form hydrophobic copolymers with a glass transition temperature between +60 and -40°C. Dispersions with a high solids content and a relatively low viscosity are obtained. The dispersions provide alkali-stable adhesives, but they are only sufficiently shear-stable in an alkaline medium for use in the adhesive press.

From BRD-off.skrift no. 24 52 585, a method is known for producing shear-stable aqueous copolymer dispersions by copolymerizing ethylenically unsaturated compounds, whereby nitrogen-containing monomers are also incorporated into the polymer.' The polymerization takes place in two stages, whereby the nitrogen-containing monomers are first copolymerized with carboxyl-group-containing monomers in the aqueous phase, and then an emulsion polymerization is carried out in the polymer solution with non-polar monomers, possibly after the addition of low molecular weight emulsifiers. These dispersions can of course be produced in the absence of aqueous emulsifiers in the second polymerization step. However, they then have a lower LD value and a lower stability than the emulsifier-containing aqueous dispersions.

From BRD-off. document no. 24 54 397, a method for the production of cationic aqueous copolymer dispersions is known, whereby in a first polymerization step in an aqueous solution, or dispersion, a copolymer is produced with a K-value from 20 to 60, from 70 to 90% by weight of styrene and/or a (meth)acrylic acid ester and 10 to 30% by weight of monoolefinically unsaturated monomers with tertiary, protonated tertiary or quaternary nitrogen atoms, and then in another polymerization step polymerizes, during simultaneous copolymerization, acrylic acid ester and/or butadiene, styrene and/or acrylonitrile and/or methacrylic acid methyl ester as essential monomers, as well as possibly small amounts of α,3-monoolefinically unsaturated carboxylic acids. The monomers are thereby selected so that a copolymer with a glass transition temperature of -15 to +60°C is obtained. The copolymer dispersions produced according to this method are used, for example, as a coating agent for paper, leather or textiles and also as an adhesive for paper. However, the effect of this adhesive still needs to be improved.

The present invention provides polymer dispersions in which finely divided, nitrogen-containing monomers, produced by a 2-stage polymerization, have been polymerized.

The invention also relates to the use of the aforementioned polymer dispersions as pulp and surface adhesives for paper.

The polymer dispersions according to the invention are characterized by the fact that they are formed by, in the first polymerization step, by solution copolymerization, a low-molecular-weight prepolymer is produced, in a water-miscible solvent that can contain up to 15% by weight of water, from a monomer mixture, which per . 1 mole contains

a) a nitrogenous monomer of formula

in which

A = 0, NH,

B = <C>nH2n, n = 1 to 8,

R1, R<2> = Cm<H>2m+1, m = 1 to 4,

R<3> = H, CH3 ,

X" = OH", Cl", Br", CH3-OSO3H" and

r<4> = cm<H>2m<+>l' m = 1 to 4,

b) 2.5 to 10 mol of at least one non-ionic, hydrophobic, ethylenically unsaturated monomer, whereby these monomers, when

they polymerize alone, forming hydrophobic polymers, c) 0.5 to 1.5 moles of an ethylenically unsaturated carboxylic acid or maleic anhydride and

d) 0 to 7 moles of a nonionic, hydrophilic, ethylenic

unsaturated monomer,

since the prepolymer in a 1 percent solution of a mixture of 99 parts by weight of dimethylformamide and 1 part by weight of glacial acetic acid at a temperature of 20°C has a viscosity of 1.06-1.40 (measured with an Ubbelohde Viscometer), dilute the solution of the prepolymer with water in a weight ratio of 1:3 to 1:50, and polymerizes in this polymer solution, in the second stage of the polymerization, based on 1 part by weight of the solution polymer, 1 to 32 parts by weight of at least one non-ionic, hydrophobic, ethylenically unsaturated monomer, whereby these monomers correspond to the monomer b) in the prepolymer, by emulsion polymerization in the presence of usual amounts of water-soluble polymerization initiators.

The monomer mixture preferably contains compounds of formula I as component (a).

The compounds with formula II are usually called cationic monomers, and those with formula I basic. Basic, ethylenically unsaturated monomers are, for example, acrylic acid and methacrylic acid esters of amino alcohols, e.g. diethylaminodiethyl acrylate, diethylaminoethyl methacrylate, dimethylaminopropyl acrylate, dimethylaminopropyl methacrylate, dibutylaminopropyl acrylate, dibutylaminopropyl methacrylate, dimethylaminoeopentyl acrylate, amino group-containing derivatives of acrylamide or methacrylamide, such as acrylamidodimethylpropylamine, methacrylamidodimethylpropylamine and methacrylamidodimethylpropylamine.

The quaternary compounds of formula II are obtained by reacting the basic monomers of formula I with known quaternization agents, e.g. with benzyl chloride, ethyl chloride, butyl bromide, dimethyl sulfate and diethyl sulfate. These monomers lose their basic character in the quaternized form.

The monomers in group (b) for the production of prepolymer

isate are such monomers that are not noticeably soluble in

water and which form hydrophobic polymers. Such monomers are, for example, vinyl aromatic monomers, such as styrene and substituted styrenes, e.g. methylstyrene or ethylstyrene, carboxylic acid esters of ethylenically unsaturated C 1 to C 2 mono- and di-carboxylic acids and monohydric alcohols with 1 to 18, preferably 4 to 12, carbon atoms, nitriles of the aforementioned carboxylic acids and also vinyl esters of aliphatic carboxylic acids containing 1 to 1.2 carbon atoms, alkenes with 2 to 10 carbon atoms, preferably those having terminal double bonds, such as ethylene or diolefins, especially butadiene and isoprene. Of this group of monomers, styrene, acrylic acid ester, methacrylic acid ester, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl propionate and butadiene are preferably used. Certain compounds are methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, ethylhexyl acrylate, lauryl acrylate and the corresponding esters of methacrylic acid.

It is of course also possible to use mixtures of the mentioned monomers, e.g. mixtures of styrene and ethylhexyl acrylate, styrene and n- or isobutyl acrylate, styrene, isobutyl acrylate and acrylonitrile or vinyl isobutyl ether. This group of monomers is non-ionizable and, when polymerized alone, forms hydrophobic polymers, i.e. polymers that do not dissolve in water. The monomers in group (b) of the prepolymer are contained in the monomer mixture in an amount of, based on 1 mol of the monomers in group (a), 2.5 to 10, preferably 3 to 8, mol.

Ethylenically unsaturated carboxylic acids are used as monomers in group (c). With this group of monomers, it is essentially about C1- to C8-mono- and -di-carboxylic acids, e.g. acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic anhydride, styrene carboxylic acids and half-esters of maleic acid with alcohols having C 1 to C 8 carbon atoms. Acrylic acid and methacrylic acid are preferably used. The monomers in group (c) are, based on 1 mol of the monomers in group (a), present in the monomer mixture in an amount of 0.5 to 1.5, preferably 0.7 to 1.4, mol.

As monomers (d), which can optionally be used to modify the properties of the prepolymer, non-ionic, hydrophilic, ethylenically unsaturated monomers are used, e.g. amides or substituted amides of ethylenically unsaturated mono- or dicarboxylic acids, e.g. acrylamide, methacrylamide, N-methylolacrylamide, N-methylol methacrylamide, and also the N-methylol acrylamides and N-methylol methacrylamides etherified with C^- to C^-monohydric alcohols. The monomers in group (d) are, based on 1 mol of the monomers in group (a), present in the monomer mixture in an amount of 0 to 7, preferably 0 to 3, mol.

The mentioned monomers are polymerized in a water-miscible organic solvent, which can contain up to 15% by weight of water, to a low molecular weight product. In the preferred embodiment of the method according to the invention, the solvent must dissolve the monomers homogeneously, and also the copolymer formed during the prepolymerization in the first step. For example, formic acid, acetic acid, propionic acid, alcohols such as methanol, ethanol and isopropanol, ketones such as acetone and methyl ethyl ketone, or amides such as dimethylformamide are used as solvents. Mixtures of solvents can also be used, e.g. mixtures of acetic acid and dimethylformamide, acetic acid and isopropanol. Mixtures of acetic acid and acetone are particularly advantageous, because the polymerization initiator is mostly added to the reaction mixture dissolved in acetone. If alcohols, ketones or amides are used as solvents, it is necessary to neutralize the basic monomers. Acetic acid is preferably used as a solvent, and work is carried out to the large exclusion of water.

In the first step of the polymerization, amphoteric is produced. 'solution copolymers. The amphoteric copolymers contain the monomers in group (a) and in group (c) preferably in stoichiometric amounts, respectively the monomers in group (c) in deficit. The weight ratio between hydrophobic (monomers in group (b)) and hydrophilic components in the prepolymer (monomers in groups (a), (c) and (d)) is preferably in the range from 2:1 to 7:1. The preparation of the prepolymer in the first stage of the polymerization takes place at temperatures of 20 to 160, preferably 60 to 140°C. Low molecular weight, statistical copolymers are produced, which have a degree of polymerization of 5" to 100, preferably 10 to 50. The viscosity of this low molecular weight prepolymer is, in a 1% solution, a mixture of 99 parts by weight of dimethylformamide and 1 part by weight of glacial acetic acid at a temperature at 20°C, 1.06 to 1.40 (\ el measured with an Ubbelohde viscometer).

The low-molecular amphoteric prepolymers are in principle produced according to known methods, polymerizing in the presence of large amounts of chain transfer agents (concentrations from 0.1 to 15% by weight, and the chain transfer agents are e.g. thioglycolic acid, dodecyl mercaptan or carbon tetrabromide), or use very high initiator concentrations. It is particularly advantageous to use large initiator concentrations, e.g. 1 mole of initiator per 17 to 160 moles of the monomers being polymerized. The rate of fission--4 to the initiator is in the order of 10

_2

to 10 mol/sec. These initiators are soluble in organic, water-miscible solvents. This is a separate issue here

about azoisobutyric acid dinitrile, tert.butyl perbenzoate, benzoyl peroxide, tert.butyl hydroperoxide and also hydrogen peroxide in the presence of iron salts. In this way, copolymer solutions are obtained which contain 20 to 70, preferably 30 to 65, wt% of the low molecular weight prepolymer in solution.

In connection with the first polymerization step, the copolymer solution is diluted with water in a weight ratio of 1:3 to 1:50. If an acid is not used as solvent, it is necessary to acidify the solution. Due to the content of basic amino groups, respectively quaternary ammonium groups in the polymer, it is soluble in water. The concentration of the solution polymer in the water-diluted solution is in the range from 2 to 25% by weight. The aqueous polymer solution, which can optionally be distilled from the organic solvent, serves as the basis for the second polymerization step in which predominantly non-ionic, hydrophobic, ethylenically unsaturated monomers are polymerized by emulsion polymerization. Based on 1 part by weight of the solution polymer, 1 to 4 parts by weight of the non-ionic, hydrophobic, ethylenically unsaturated monomers or a mixture from this group of monomers are used. Hereby, such monomers are taken into account which, in the preparation of the prepolymer in the first step, were designated as monomers in group (b). Preferably, from this group, styrene, C₁- to Cg-alkyl acrylates and methacrylates are used, such as butyl ester of acrylic acid and methacrylic acid, hexyl acrylates and 2-ethylhexyl acrylate, acrylonitrile, methacrylonitrile, vinyl acetate or vinyl propionate.

The emulsion polymerization takes place in the temperature range from 40 to 150, preferably 60 to 100°C, using usual amounts of water-soluble polymerization initiators. The upper limit for these initiators is 4% by weight, based on the monomers that are polymerized. Suitable initiators for the emulsion polymerization are, for example, organic peroxides, hydroperoxides, hydrogen peroxide and inorganic peroxides, and also redox systems, e.g. hydrogen peroxide/ascorbic acid or tert.butyl hydroxide/ascorbic acid. In the second polymerization step, the monomers are added either undiluted or in the form of an aqueous emulsion to the polymerization batch. To emulsify the monomers in water, one can, for example, use part of the aqueous solution of the prepolymer in the first polymerization step or also common emulsifiers. The emulsion polymerization in the second step is preferably carried out in the absence of usual emulsifiers. However, added emulsifiers can be used in an amount of up to 3% by weight, based on the polymer in the first and second stages. The usual emulsifiers hardly have any effect on the particle size of the dispersions according to the invention. Suitable emulsifiers, which can be used in the polymerization, are products obtained by ethoxylation of phenol or phenol derivatives. Such emulsifiers contain 4 to 30 mol of ethylene oxide per moles of phenol. Cationic and amphoteric emulsifiers are also suitable, for example dimethyl-C^2H24-^etta^yl~ benzylammonium chloride or the compound with the formula

It is of course also possible to use non-ionic and anionic emulsifiers in a mixture. Emulsifiers can also be added to the dispersion after the emulsion polymerization in the second step, in order to modify the properties of the dispersion. Based on the dispersed polymer, 0.05 to 3% by weight of an emulsifier or emulsifier mixture is used.

In the second polymerization step, the pH value of the reaction mixture is set to a value from 2 to 5.

After the two-stage polymerization process, one obtains

polymer dispersions in which finely divided, nitrogen-containing monomers are polymerized, and the particle size is in the range from 25 to 250 nm. This range for particle size therefore lies below the ranges for polymer dispersions such as e.g. is obtained by the method in BRD-off.skrift no. 24 52 585. A measure of the particle size of the dispersion is the LD value.

To determine the LD value (light transmission), the dispersion is measured with light of wavelength 546 nm in a 0.01% aqueous solution in a cuvette with an edge length of 2.5 cm. Using the "Mie theory" the particle diameter can be calculated from it (see B. Verner, M. Bårta, B. Sedlåcek, Tables of Scattering Functions for Spherical Particles, Praha 1976, Edice Marco, Rada D-DATA, SVAZEK D-l).

Films of dried amphoteric dispersions are clearly more water-fast than films of similar cationic dispersions. The films have good adhesion to glass and metals. The amphoteric dispersions have, if they do not contain any quaternary aminophobe compounds, a pH-dependent range in which they coagulate (isoelectric point). At lower or higher pH values, they are stable dispersions. The isoelectric point can by the ratio of the monomers in group (a)

: (c) in the solution polymer is shifted by 2 to 3 pH units. At a molar ratio for the monomers (a) : (c) of 1, it is at approx. pH 8.

The dispersions according to the invention have a number of areas of application, for example, for coating or impregnating paper and building materials and also as a pulp and surface adhesive for paper. When surface gluing paper, the dispersions according to the invention are brought to a common polymer concentration by adding water, which is common for preparation solutions in general, e.g. a polymer content of from 0.05 to 3.0% by weight. The amount of copolymer that is applied to the paper to glue it is usually between 0.02 and 1.5, preferably between 0.3 and 0.8% by weight, based on dry fiber material. For the preparation of preparation solutions, the dispersions, whose solids content amounts to 10 to 50% by weight, are diluted with water. The preparation solutions can also contain additional excipients, e.g. starch, dyes and wax emulsions.

The dispersions according to the invention can also be used as mass sizing agents. They are then effective in all acidic pH ranges as an adhesive.

The use of the dispersions according to the invention as a surface adhesive takes place in the usual way, i.e. mostly in combination with starch or synthetic dry fixing agents, whereby the preparation solutions are usually applied to the paper with the help of a glue press. It is of course also possible to apply the preparation solution to the paper web by spraying or dipping. ing or e.g. using a water scraper. The paper which has been treated with the preparation solution is then dried. After drying the paper web, the gluing is already completely finished.

The parts given in the examples are parts by weight, and the percentages are also based on the weight of the substance. The degree of gluing of the paper was determined using the Cobb values according to DIN 53 132 and the ink floating time in minutes up to 50% penetration with a normal ink according to DIN 53 126. To test the gluing effect of the dispersions according to the invention, two different test papers were used . Sample paper A had the following material composition:

50% bleached sulphite cellulose

50% bleached sulfate cellulose

25% kaolin, based on dry cellulose

2% alum, based on dry paper

Paper B:

50% bleached sulphite cellulose

50% bleached sulfate cellulose

25% kaolin, based on dry cellulose

4% alum, based on dry paper.

The test papers were unglued in the mass, had a basis weight of 70 g/m^, the ground level was 25°SR and the ash content was 14%. The preparation solutions contained, when not otherwise stated, each 1.5 g/l of the copolymer, based on the solids content of the dispersion, and 60 g/l of an oxidatively degraded starch. The foam ceiling was in all cases 90%, based on dry paper.

Example 1

In a stirred vessel, 60 parts of acetic acid, 60 parts (5.77 mol) of styrene and 33 parts (1.94 mol) of dimethylaminopropyl methacrylamide and 15 parts (2.08 mol) of acrylic acid were mixed with 1 part of azoisobutyric acid dinitrile and heated to a temperature of 85°C. After the reaction participants had been heated for \ hour at 85°C, it was over

. of one hour added a solution of 1.25 parts of azoisobutyric acid dinitrile in 5 parts of acetone and the temperature of the reaction mixture was maintained at 85 to 90°C. After a further 30 minutes, the first stage of the polymerization was finished. A homogeneous polymer solution was obtained which was dissolved in 590 parts by weight of water to a clear solution and heated to a temperature of 85°C. After adding 20 parts

6% hydrogen peroxide and 0.04 parts by weight FeSO4.7H20, in the second stage of the polymerization, 80 parts by weight of 6% hydrogen peroxide and a mixture of 126 parts isobutyl acrylate and 66 parts styrene were added separately over the course of 2 hours. During the polymerization in the second stage, the temperature was 84 to 87°C. It was maintained for another 1 hour after the end of the monomer feed and the initiator feed. A finely divided dispersion was obtained with a solids content of 32% and an LD value of 98. The dispersion was used for surface sizing of paper. It gave for sample paper A a Cobb value of 21 and an ink float time of 23 minutes and for sample paper B a Cobb value of 21 and an ink float time of 13 minutes.

Example 2.

In a stirred vessel, 60 parts of acetic acid, 60 parts (5.77 mol) of styrene, 33 parts (1.94 mol) of dimethylaminopropyl methacrylamide, 15 parts (2.08 mol) of acrylic acid and 1 part of azoisobutyric acid dinitrile were mixed and heated to a temperature at 85°C. After the monomer mixture had been heated for % hour at a temperature of 85° C., a solution of 1 part azoisobutyric acid dinitrile in 5 parts acetone was added in the course of 1 hour. 30 minutes after the initiator addition was finished, the solution of prepolymer was dissolved in 300 parts of water to a homogeneous solution. , The solution was heated to a temperature of 85°C, and then a redox initiator consisting of 20 parts of a 6% hydrogen peroxide solution and 0.04 part FeSO^ was added. 7^0. To the solution heated to 85°C, 80 parts of 6% hydrogen peroxide from one and from the other an emulsion of 126 parts of isobutyl acrylate, 66 parts of styrene and 3 parts of dimethyldodecylbenzylammonium chloride were added over the course of 2 hours from two separate vessels (emulsifier) in 300 parts water. For post-polymerisation, the temperature in the reaction mixture after finishing the monomer addition was kept at 85°C for another 1 hour. A finely divided aqueous dispersion was obtained with a solids content of 30.3% and an LD value of 99.

Example 3

In a stirred vessel, 60 parts of acetic acid, .60 parts (5.77 moles) of styrene, 33 parts (1.94 moles) of dimethylaminopropyl methacrylamide, 15 parts (2.08 moles) of acrylic acid, and 1 part of azoisobutyric acid dinitrile were mixed and heated to a temperature at 85°C. After the mixture had been kept at 85°C for 30 minutes, over the course of 1 hour a

solution of 1.25 parts of azoisobutyric acid dinitrile in 5 parts of acetone.

30 minutes after the addition of the initiator solution, the prepolymer was dissolved in 440 parts of water to a homogeneous solution (viscosity of the prepolymer 7| =1.14). 40 parts of the prepolymer solution were taken out of the vessel and used as an emulsifier for the preparation of the emulsion feed in 2, polymerization stage. The remainder of the prepolymer solution was back into the stirrer and was heated to a temperature of 85°C.

After adding 20 parts 6% hydrogen peroxide solution and

0.04 part FeS04.7H20, 80 parts of 6% hydrogen peroxide and an emulsion of 126 parts isobutyl acrylate and 66 parts styrene in 300

parts water and 40 parts of the prepolymer solution. One hour after finishing the initiator and monomer addition, a finely divided dispersion was obtained with a solids content of 26.5% and an LD value of 99.

Example 4

In a stirred vessel, 60 parts of glacial acetic acid, 60 parts (5.77 mol) of styrene, 33 parts (1.94 mol) of dimethylaminopropyl methacrylamide, 15 parts (2.08 mol) of acrylic acid and 3 parts of azoisobutyric acid dinitrile were mixed, and the was heated to 85°C. After 30 minutes, 6 parts of azoisobutyric acid dinitrile were added over the course of 1 hour. After a further 30 minutes, the prepolymer was dissolved in 590 parts of water and the solution heated to 85°C. Then 20 parts of a 6% hydrogen peroxide solution and 0.04 part FeSO^^P^O were added. IN

over the course of 2 hours, 80 parts of a 6% aqueous hydrogen peroxide solution and, secondly, a mixture of 126 parts of isobutyl acrylate and 66 parts of styrene were added continuously and simultaneously from two separate vessels. After post-reaction for 1 hour, a finely divided dispersion with a solids content of 30.8% was obtained

and an LD value of 99.

Example 5

In a vessel with stirrers, 60 parts of acetic acid, 60

parts (5.77 moles) of styrene, 21 parts (1.9<*> moles) of dimethylaminopropyl methacrylamide, 11 parts (2.08 moles) of acrylic acid and 3 parts of azoisobutyric acid dinitrile, and it was heated to 85°C. After 30 minutes, 6 parts of azoisobutyric acid dinitrile were added over the course of 1 hour. After a further 30 minutes, the prepolymer under

heating to 85°C dissolved in 590 parts water. Then it was added

20 parts of a 6% hydrogen peroxide solution and 0.04 part FeSO^. 7^0. In the course of 2 hours, one then added, simultaneously from two different devices, firstly 80 parts of 6% hydrogen peroxide as initiator and secondly a mixture of 99 parts isobutyl acrylate and 99 parts styrene. After post-reaction for 1 hour, a finely divided dispersion with a solids content of 28.5% and an LD value of 99 was obtained.

Example 6.

In a mixing vessel, 60 parts of acetic acid, 33 parts (2.58 mol) of butyl acrylate, 33 parts (3.17 mol) of styrene, 18 parts (1.06 mol) of dimethylaminopropyl methacrylamide, 9 parts (1.25 mol) of acrylic acid were mixed together , 9 parts (1.27 moles) of acrylamide and 3 parts of azoisobutyric acid dinitrile, and it was heated to 85°C. After 35 minutes, 6 parts of azoisobutyric acid dinitrile were added. The initiator addition was finished after 1 hour, 30 minutes after finishing the initiator addition, the prepolymer was homogeneously dissolved in 590 parts of water by heating to 85°C. Then 20 parts of an aqueous 6% hydrogen peroxide solution and 0.04 part FeSO4.7H20 were added. It was then added over the course of 2 hours

from separate additive containers for the first 80 parts of a 6

% aqueous hydrogen peroxide solution and, secondly, a mixture of 156 parts acrylonitrile and 36 parts isobutyl acrylate. For post-reaction, the mixture was heated for another 1 hour at a temperature of 85°C. A dispersion with a solids content of 30.5% and an LD value of 95 was obtained.

Example 7

In a stirring vessel, 60 parts of acetic acid, 60 parts (5.77 mol) of styrene, 33 parts (1.94 mol) of dimethylaminopropyl methacrylamide, 15 parts (2.08 mol) of acrylic acid, 1 part of azoisobutyric acid dinitrile and 2 parts ( 0.22 mol) of thioglycolic acid, and it was heated to 85°C. This temperature was maintained for 30 minutes, and then a solution of 1.25 parts of azoisobutyric acid dinitrile and 2 parts of thioglycolic acid in 5 parts of acetone was added continuously over the course of 1 hour. 30 minutes after the addition of the latter solution was finished, 590 parts of water were added to the prepolymer, and the mixture was heated to 85°C and at this temperature 20 parts of an aqueous 6% hydrogen peroxide solution and 0.04 part of FeSO4.7H20 were added. Then, in 2 stages of the polymerization, 80 parts of a 6% aqueous hydrogen peroxide solution were added in the same manner over the course of 2 hours, and separately from there a mixture of 126 parts of isobutyl acrylate and 66 parts of styrene. After post-reaction for 1 hour, a dispersion was obtained with an LD value of 99 and a solids content of 30.6%.

Example 8

In a stirring vessel, 60 parts of acetic acid, 60 parts (5.77 mol) of styrene, 33 parts (1.94 mol) of dimethylaminopropyl methacrylamide, 15 parts (2.08 mol) of acrylic acid, 2 parts of thioglycolic acid (as a chain transfer agent) and 1 part of azoisobutyric acid dinitrile and heated to 85°C. The mixture was held for 30 minutes at 85°C and then, over the course of 1 hour, a solution of 1.25 parts of azoisobutyric acid dinitrile in 2 parts of thioglycolic acid and 5 parts of acetone was added. 30 minutes after the addition of the latter solution, the prepolymer was dissolved in 590 parts of water, and at 85°C 20 parts of a 6% aqueous hydrogen peroxide solution, 1.5 parts of thioglycolic acid and 0.04 parts of FeSO^^H^O were added. In the 2nd polymerization stage, 80 parts of an aqueous 6% hydrogen peroxide solution and a mixture of 126 parts isobutyl acrylate and 66 parts styrene were added in the same way over the course of 2 hours from separate storage vessels. After finishing the addition of monomers and initiators, the reaction mixture was heated for another 1 hour at a temperature of 85°C. A dispersion with an LD value of 99 and a solids content of 30.4% was obtained. Example 9

In a mixing vessel which was fitted with a reflux condenser,

60 parts (5.77 mol) of styrene, 33 parts (1.94 mol) of dimethylaminopropyl methacrylamide, 15 parts (2.08 mol) of acrylic acid, 60 parts of acetic acid and 9 parts of tert-butyl perbenzoate were mixed together and heated to 120°C . After the mixture was heated for 2 hours at 120°C, it was cooled to 85°C, and the prepolymer from the first step was dissolved in 590 parts of water. The polymerization in the second stage was then carried out at 85°C. 0.04 part of FeSO^^P^O was added to the prepolymer solution, and 100 parts of a 6% hydrogen peroxide solution and a mixture of 126 parts of isobutyl acrylate and 66 shares sty-^.n. The post-polymerization and the main polymerization were carried out at 85°C. A finely divided dispersion with a solids content of 32% and an LD value of 99 was obtained.

Example 10

A mixture of 20 parts (1.92 mol) styrene, 7 parts (0.41 mol) dimethylaminopropyl methacrylamide, 3.5 parts (0.486 mol) acrylic acid and 10 parts acetic acid was obtained within 1 hour with the aid of a pump pumped into a vessel that was heated to 90°C. Simultaneous,

and likewise within 1 hour, 2 parts of azoisobutyric acid dinitrile and 10 parts of acetic acid were added by means of another dosing device. The mixture was heated for 30 minutes to a temperature of 90°C, and was then dissolved in 180 parts of water. Then 0.01 part iron sulfate was added and a mixture of 32 parts styrene and 32 parts isobutyl acrylate was polymerized therein at a temperature of 85°C, as separately from 33 parts of a 6% hydrogen peroxide solution, during 2 hours continuously was added to the prepolymer. After 1 hour of post-polymerization at a temperature of 85°C, a finely divided dispersion with a solids content of 31.4% and an LD value of 99 was obtained.

Examples 11 to 16

A mixture of 20 parts (1.92 mol) styrene, 20 parts acetic acid, 7 parts (0.41 mol) dimethylaminopropyl methacrylamide, 3.5 parts (0.486 mol) acrylic acid was formed each time and these mixtures were heated to different temperatures , as indicated in Table 1, and then 0.3 part of azoisobutyric acid dinitrile was added.

During "t" minutes, the portions of the initiator azoisobutyric acid dinitrile in the form of a 20% solution in acetone, indicated in Table 1, were then added. Each time 30 minutes after the end of catalyst addition, 180 parts of water and 0.01 part of iron sulphate were added. The mixture was then heated to 85°C and served as a precursor for the polymerization in the 2nd stage, whereby a mixture of 32 parts styrene and 32 parts isobutyl acrylate was polymerized each time with the simultaneous and likewise continuous addition of 33 parts of a 6% aqueous hydrogen peroxide solution within 2 hours. The post-polymerization took place at a temperature of 85°C during 1 hour. Finely divided dispersions were obtained each time, and their solids content and LD values are listed in Table 1.

To determine the '\re2_ -values indicated in the table, the aqueous solution of the prepolymer was freeze-dried at -18°C. 1 g of this product was then dissolved in 100 ml of a mixture of 99 parts by weight of dimethylformamide and 1 part by weight of glacial acetic acid, and it was measured at 20°C.

Example 17

In a stirring vessel, 60 parts of glacial acetic acid, 60 parts (5.77 mol) of styrene, 33 parts (1.93 mol) of diethylaminoethyl acrylate and 15 parts of acrylic acid (2.08 mol) were mixed with 3 parts of azoisobutyronitrile and heated to 85° C. After 30 minutes, 6 parts of azoisobutyronitrile were added over the course of 1 hour. After a further 30 minutes, the prepolymer ("^ ^ = 1.13.) was dissolved in H20, and the solution was heated to 85°C. Then 20 parts of a 6% hydrogen peroxide solution of 0.04 part FeSO4.7H20 were added. In the course of 2 hours, 80 parts of a 6% hydrogen peroxide solution and a mixture of 66 parts of styrene and 126 parts of isobutyl acrylate were added.After 1 hour of post-reaction, a finely divided dispersion with a solids content of 30.8% was obtained and an LD value of 87%.

Example 18

In a stirring pot, 60 parts of glacial acetic acid, 51.5 parts (0.5 mol) of styrene, 17 parts of butyl acrylate (0.13 mol), 27.5 parts (0.134 mol) of dimethylaminoneopentyl acrylate, 12 parts (0.167 mol) of acrylic acid and

3 parts of azoisobutyric acid dinitrile mix', and heated to 85°C. After 30 minutes, 6 parts of azoisobutyronitrile were added over the course of 30 minutes. After an additional 30 minutes, the prepolymer was dissolved in 590 parts H 2 O. Then 20 parts of 6% hydrogen peroxide and 0.04 part of FeS04.7H20 were added. During 2 hours, at 85°C, a mixture of 96 parts isobutyl acrylate, 96 parts styrene and 80 parts 6% hydrogen peroxide was added simultaneously and in the same way. After 1 hour of after-reaction it was

obtained a finely divided dispersion with solids content 29% and LD value 99%.

Example 19

In a stirring vessel, 60 parts of formic acid, 60 parts (5.77 mol) of styrene, 33 parts (1.94 mol) of dimethylaminopropyl methacrylate and 15 parts of

(2.08 moles) of acrylic acid and 9 parts of azoisobutyronitrile are mixed and heated to 85°C. The mixture heated to 100°C. After 2 hours, 540 parts of water, 20 parts of 6% hydrogen peroxide and 0.04 part of FeS04.7H20 were added. At 85°C, a mixture of 96 parts of isobutyl acrylate and 96 parts of styrene was then added simultaneously and in the same way, and by separate addition, 80 parts of 6%

hydrogen peroxide. After 1 hour of post-reaction, a dispersion with a solids content of 31.1% and an LD value of 97% was obtained.

Example 2 0

In a stirring vessel, 40 parts of formic acid, 40 parts (3.85 mol) of styrene, 22 parts (1.29 mol) of dimethylaminopropyl methacrylate and 10 parts of

(1.39 moles) of acrylic acid and 9.6 parts of azoisobutyronitrile are mixed and heated to 85°C. The mixture heated itself to 101°C. After 1 hour, it was dissolved in 540 parts of water and 20 parts of 6% hydrogen peroxide and 0.04 part of FeS04.7H20 were added. At 85°C, a mixture of 149 parts of isobutyl acrylate and 79 parts of styrene and also 80 parts of 6% hydrogen peroxide was then added simultaneously and in the same way. After 1 hour of post-reaction, a dispersion with a solids content of 30.9% and an LD value of 93% was obtained.

Preparation of comparison dispersions

in accordance with the teaching in BRD official document no. 24 52 585

Comparative dispersion 1

235 parts of water, 4 parts of dimethyl-C12-fatty alkylbenzylammonium chloride, 6.7 parts of acetic acid and 0.02 part of iron sulfate were introduced into a mixing vessel, and it was heated to 85 C. Then 8 parts of a 3% aqueous hydrogen peroxide solution were added .

A mixture of 12.5 parts (0.73 mol) of diethylaminoethyl acrylate and 1.8 parts (0.25 mol) of acrylic acid was then added. The mixture was heated to 85°C for 30 minutes. In a 2nd polymerization step, a mixture of 40 parts of butyl acrylate and 46 parts of acrylonitrile and from another storage vessel 32 parts of a 3% aqueous hydrogen peroxide solution was then continuously pumped in over the course of 4 hours. The temperature was kept at 85°C for 90 minutes after finishing the monomer addition. A dispersion with a solids content of 25% and an LD value of 81 was obtained.

Comparative dispersion 2

227 parts of water, 20 parts of acetic acid, 6.6 parts of a 6% hydrogen peroxide solution and 0.02 part of iron sulphate were added to a mixing vessel, and it was heated to 85°C. 12.5 parts (0.735 mol) of dimethylaminopropyl methacrylamide and 5 parts (0.69 mol) of acrylic acid were added to this over the course of 3 minutes. The prepolymerization was finished after 30 minutes. Subsequently, a mixture of 28.5 parts styrene and 54 parts isobutyl acrylate and from a separate storage vessel 27 parts of a 6% hydrogen peroxide solution was pumped into the prepolymer solution heated to 85°C at the same time and in the same way over the course of 4 hours. A 26.5% aqueous dispersion with an LD value of 11 was obtained.

Comparative dispersion 3

Following the prescription for comparative dispersion 2, a similar prepolymer was prepared, but a mixture of 40 parts butyl acrylate and 46 parts acrylonitrile was used in the 2nd step for the emulsion polymerization. At the same time as the monomer supply, 27 parts of a 6% aqueous hydrogen peroxide solution were pumped in over the course of 2 hours. The post-reaction lasted for 2 hours at 85°C. A dispersion with an LD value of 60 was obtained.

Comparative dispersion 4

In a stirring vessel, 60 parts of glacial acetic acid, 58 parts (5.57 mol) of styrene, 33 parts (1.94 mol) of dimethylaminopropyl methacrylamide and 26 parts (2.03 mol) of butyl acrylate were mixed with 3 parts of azoisobutyric acid nitrile and heated to 85° C. After 30 minutes, 6 parts of azoisobutyric acid nitrile were added over the course of 30 minutes. After a further 60 minutes, the prepolymer was dissolved in 540 parts of water, and mixed with 20 parts of 6 lg hydrogen peroxide solution and 0.04 part of FeSO4.7H20. During 2 hours, at 85°C, a mixture of 126 parts of isobutyronitrile and 66 parts of styrene was added simultaneously and in the same way, and next to this 80 parts of 6% hydrogen peroxide. After post-reaction for 1 hour, a dispersion with a solids content of 29.1% and an LD value of 99% was obtained.

Comparative dispersion 5

In a stirrer, 60 parts glacial acetic acid, 66 parts (6.35 moles) styrene, 25 parts (1.47 moles) dimethylaminopropyl methacrylamide, 17 parts (2.0 moles) methyl acrylate and 3 parts azoisobutyronitrile were mixed and heated to 85°. After 30 minutes, 6 parts of azoisobutyronitrile were added over the course of 30 minutes. After a further 60 minutes, the mixture was dissolved in 540 parts of t^O, and 20 parts of 5% hydrogen peroxide and 0.04 part of FeSO 4 .7H 2 O were added. At 85°C, a mixture of 126 parts of isobutyl acrylate and 66 parts of styrene and also 80 parts of 6% hydrogen peroxide was then added simultaneously and in the same way. After post-reaction for 1 hour, a dispersion was obtained with a solids content of 31.1% and an LD value of 99%. Comparison dispersion 6 (example according to BRD-off.

letter 24 54 397)

190 parts (18.2 mol) styrene, 10 parts (0.78 mol) n-butyl acrylate, 60 parts (3.8 mol) dimethylaminoethyl methacrylate, 30 parts of formic acid and 20 parts of a 20% solution of t-butyl perpivalate in acetone. After completion of polymerization, it was diluted with 1000 parts of water. 370 parts of water were added to 440 parts of the solution. It was heated to 85°C and 5 parts of a 50% hydrogen peroxide solution were added and then, over the course of 4 hours, a mixture of 125 parts of 2-ethylhexyl acrylate and 154 parts of styrene and also at the same time a further 15 parts of a 50% hydrogen peroxide solution. 2 hours after finishing the monomer addition, it was cooled. A dispersion with a solids content of 30.3% and an LD value of 42% was obtained.

Comparative dispersion 7 (example according to BRD-off.

letter 24 54 397)

190 parts (18.2 mol) of styrene, 10 parts (0.78

mol) of n-butyl acrylate, 60 parts (3.5 mol) of dimethylaminopropyl methacrylamide, 30 parts of formic acid and 20 parts of a 20% solution of t-butyl perpivalate in acetone. After completion of polymerization,

diluted with 1000 parts water. 370 parts of water were added to 440 parts of the solution. It was heated to 85°C and 5 parts of a 50% hydrogen peroxide solution were added and then in

in the course of 4 hours a mixture of 125 parts of 2-ethylhexyl acrylate and 154 parts of styrene and also at the same time a further 15 parts of a 50% aqueous hydrogen peroxide solution. 2 hours after finishing the monomer addition, it was cooled. A dispersion with a solids content of 30.6% and an LD value of 41% was obtained.

The LD values in the comparison dispersions 2 and 3 were so low that these dispersions, when used as a sizing agent for paper, gave insufficient sizing values. The polymer dispersions described in the examples were tested according to the specified prescription as a surface adhesive for paper. The results are summarized in table 2 and are there compared with the comparison dispersions 1, 4, 5, 6 and 7 as a surface adhesive.

Compared to the tested dispersions according to the invention, comparison dispersion 1, which is in accordance with BRD-off.skrift 24 52 585, is worse, while the pure cationic comparison dispersions 4 and 5 are significantly worse. The comparison dispersions 6 and 7 are also inferior, and they only give better bonding values at higher concentrations.

The dispersions can also be used as a mass sizing agent for paper, as the sizing agent is added to the paper material before the sheet is formed. Two different types of paper were tested. The starting materials for the production of papers C and D had the following composition: Paper C: 100% sulphite cellulose, 30% CaCO 3 , based on dry sulphite cellulose, 0.3%, based on dry paper, of a copolymer of acrylamide and acrylic acid, 35°SR; 80 g/m<2>;

alum-free; 12% ash (as CaCO.,) .

D: 50% recycled paper, 50% corrugated board; 80 g/m2; alum-free.

Also in the mass sizing, the tested dispersions which are in accordance with the invention are clearly better than the investigated comparison dispersions in

Claims (5)

1. Polymer dispersions in which finely divided, nitrogen-containing monomers are polymerized, which are produced by a two-stage polymerization, characterized in that the dispersions are formed by producing a low molecular weight prepolymer in the first polymerization stage by solution copolymerization, in a water-miscible solvent that can contain up to 15% water by weight, of a monomer mixture, which per 1 mol contains a) a nitrogen-containing monomer of formula in which A = 0, NH, B = <C>n<H>2n, n = 1 to 8, R1, R2 = Cm<H>2m+1, m = 1 to 4, R<3> = H, CH3, X" = 0H~, Cl", Br", CH3-OSO3H" and R<4> = cm<H>2m+l' * = 1 to 4, b) 2.5 to 10 moles of at least one nonionic, hydrophobic, ethylenically unsaturated monomer, whereby these monomers, when polymerized alone, form hydrophobic polymers, c) 0.5 to 1.5 mol of an ethylenically unsaturated carboxylic acid or maleic anhydride and d) 0 to 7 mol of a nonionic, hydrophilic, ethylenic unsaturated monomer, the prepolymer in a 1 percent solution of a mixture of 99 parts by weight of dimethylformamide and 1 part by weight of glacial acetic acid at a temperature of 20°C has a viscosity of 1.06-1.40 (measured with an Ubbelohde Viscometer), dilutes the solution of the prepolymer with water in a weight ratio of 1:3 to 1:50, and polymerizes in this polymer solution, in the second trihn of the polymerization, based on 1 part by weight of the solution polymer, 1 to 32 parts by weight of at least one nonionic, hydrophobic, ethylenically unsaturated monomer, whereby these monomers correspond to the monomer b) in the prepolymer, by emulsion polymerization in the presence of usual amounts of water-soluble polymerization initiators. 2. Polymer dispersions in which finely divided, nitrogen-containing monomers are polymerized according to claim 1, characterized in that the monomer mixture as component (a) contains compounds with the formula in which A = 0, NH, B = <C>n<H>2n, n = 1 to 8, R<1>, R<2> = C^m+i, m = 1 to 4 and R<3> = H, CH3. 3. Polymer dispersions in which finely divided, nitrogen-containing monomers are polymerized according to claims 1 to 2, characterized in that in the first polymerization step acetic acid is used as the water-miscible solvent. 4. Polymer dispersions in which finely divided, nitrogen-containing monomers are polymerized according to claims 1 to 3, characterized in that the polymerization in the second step is carried out in the absence of common emulsifiers. 5. Use of the polymer dispersions in which finely divided, nitrogen-containing monomers according to claims 1 to 4 have been polymerized as pulp and surface adhesives for paper.