Process for producing aqueous polymer dispersions

Abstract

This invention relates to a method for producing an aqueous polymer dispersion by free radical-initiated aqueous emulsion polymerization of a monomer composition comprising 50% to 99.9% by weight of at least one (meth)acrylic acid C1 to C2. 10 Alkyl esters and / or vinyl aromatic compounds (Class I), or at least one vinyl aromatic compound and conjugated aliphatic diene by weight of 50% to 99.9% (Class II), or vinyl acetate, vinyl propionate, vinyl tert-carbonate, long-chain fatty acid vinyl esters and / or ethylene by weight of 50% to 99.9% (Class III), these amounts being based on total monomers in each case, the method being carried out by polymerizing the composition in the presence of an oligosaccharide having 1.5 to 10 β-1,4-glycosidic bonds linking pyranose units; relating to the dispersion obtained accordingly; and relating to the use of the dispersion as a binder, adhesive, sizing agent for fibers, for the production of coatings or for the production of paper coating formulations.

Description

[0001] This invention relates to a method for producing an aqueous polymer dispersion by free radical-initiated aqueous emulsion polymerization of a monomer composition comprising...

[0002] At least one vinyl aromatic compound and / or (meth)acrylic acid C1 to C10 alkyl ester, by weight, comprising 50% to 99.9% of the total amount;

[0003] At least one vinyl aromatic compound and a conjugated aliphatic diene, by weight, comprising 50% to 99.9% of the following:

[0004] Vinyl acetate, vinyl propionate, vinyl tert-carbonate, long-chain fatty acid vinyl esters and / or ethylene, by weight, from 50% to 99.9%.

[0005] These quantities are based on total monomers in each case;

[0006] The invention relates to an aqueous polymer dispersion produced by the method; and to the use of the aqueous polymer dispersion as a binder in adhesives, sizing agents, fibers, coating materials and paper coating pulps.

[0007] Binders for paper coating pulps based on copolymers of vinyl aromatic compounds and aliphatic dienes are selected for a wide variety of paper applications. The ever-increasing speeds of paper machines are accompanied by increasingly stringent requirements for the rheology of coating pulps. Besides pigments, binders make a decisive contribution to the rheology of coating pulps. The prerequisites for modern paper coating dispersants and binders are high solids content with moderate viscosity and high running speed.

[0008] From EP-A 0 536 597, it is known that aqueous polymer dispersions are produced by using unsaturated monomers in at least one having a weight-average molecular weight M of 2500 to 25000. w Free radical emulsion polymerization in the presence of starch degradation products is possible. The unsaturated monomers used are, for example, a monomer mixture comprising, by weight, 50% to 100% esters of acrylic acid and / or methacrylic acid with alcohols containing 1 to 12 carbon atoms and / or styrene, and by weight, 70% to 100% styrene and / or butadiene.

[0009] WO 2011 / 157679 teaches the production of polymer dispersions by free radical emulsion polymerization of styrene, acrylates and acrylic acid in the presence of seed latex and degraded starch (such as maltodextrin or glucose syrup), and the use of such polymer dispersions as binders for paper coating pulps.

[0010] Both degraded starch and glucose syrup are based on raw materials that are also food-grade. To avoid competition with food products, the fundamental goal is to find alternative polymerization methods to produce aqueous polymer dispersions with good binding properties and mechanical strength.

[0011] According to the present invention, this objective is achieved by a method for producing an aqueous polymer dispersion by free radical-initiated aqueous emulsion polymerization of a monomer composition comprising:

[0012] At least one (meth)acrylic acid C1 to C1, comprising 50% to 99.9% by weight. 10 Alkyl esters and / or vinyl aromatic compounds (Class I), or

[0013] At least one vinyl aromatic compound and a conjugated aliphatic diene (Class II) by weight, comprising 50% to 99.9% of the total weight, or

[0014] Vinyl acetate, vinyl propionate, vinyl tert-carbonate, long-chain fatty acid vinyl esters and / or ethylene (Class III) by weight, ranging from 50% to 99.9%.

[0015] These quantities are based on total monomers in each case.

[0016] The method is carried out by polymerizing the composition in the presence of an oligosaccharide having 1.5 to 10 β-1,4-glycosidic bonds linking pyranose units.

[0017] The present invention further relates to dispersions obtained by the method of the present invention, and to the use of such dispersions as binders, adhesives, sizing agents for fibers, for the production of coatings, or for the production of paper coating pulp.

[0018] Some compounds derived from acrylic acid and methacrylic acid are referred to below as abbreviations by inserting the syllable "(meth)" into the names of compounds derived from acrylic acid.

[0019] "Total amount of monomers" refers to the total amount of all monomers used in the polymerization, which are added together to 100% by weight.

[0020] Regarding the solids content (by weight %) of the aqueous dispersion, this is based on the weight of the aqueous dispersion.

[0021] "Gluconopyranose unit" in this context refers to a glutamate residue linked by its 1-hydroxy and 4-hydroxy glycosidic bonds, or having a glycosidic bond formed by a 1-hydroxy bond at the beginning of the chain and a 4-hydroxy bond at the end of the chain. The term "β-1,4-glycosidic linked glutamate" corresponds here to the equally common prefix "cello". Cellobiose therefore refers to two β-1,4-glycosidic linked glutamate units; cellotriose represents three, cellotetraose represents four, cellopentaose represents five, and cellohexaose represents six correspondingly linked units.

[0022] According to the invention, polymerization is carried out in the presence of oligosaccharides consisting essentially of β-1,4-glycosidic bonds linking pyranose units. "consistent essentially of" means that at least 90% by weight, preferably at least 95% by weight, and more particularly at least 99% by weight, of the oligosaccharide contains β-1,4-glycosidic bonds linking pyranose units.

[0023] Because of their production method, the oligosaccharides used are typically compositions of two or more oligosaccharides, thus producing an average number of pyranose units. According to the invention, they have an average number of 1.5 to 10, preferably 2 to 6, and more particularly 4 to 5 pyranose units. This number is also referred to in the technical literature as the degree of polymerization (DP). For cellobiose, DP = 2, and for cellotriose, DP = 3, and so on.

[0024] Suitable oligosaccharides are, for example, degradation products of cellulose (which are commonly referred to as cellulosic dextrins). Examples of cellulose sources include plant fibers from wood, bamboo, cotton, kenaf, wheat, rice, and ramie. These fibers are typically used in mechanically processed forms as bagasse, pulp, or other fibers (such as fine powder) from the paper production process. The production of the corresponding oligosaccharides is known and can be carried out in an aqueous environment i) enzymatically, ii) acid-catalyzed, or iii) thermally (“Synthesis of cello-oligosaccharides by depolymerization of cellulose: A Review”, Pengru Chen, Abhijit Shrotri, Atsushi Fukuoka, Applied Catalysis A, General 621 (2021)). Cellulose is preferably degraded by enzymatic hydrolysis.

[0025] The enzymatic hydrolysis of cellulose is accomplished by cellulase. Examples of cellulase sources include microorganisms such as Trichoderma, Acremonium, Aspergillus, Bacillus, Pseudomonas, Penicillium, Aeromonus, Irpex, Sporotrichum, Humicola, and Cellevibrio, as described in "Cellulase" (published by Kodansha Scientific

[1987] ) and "Encyclopedia of Cellulose" (published by Asakura Publishing Co., Ltd.

[2000] ).

[0026] According to the same preferred embodiment, oligosaccharides are produced by acid-catalyzed hydrolysis of cellulose. Hydrolysis via phosphoric acid is preferred in the case of acid-catalyzed degradation of cellulose. Therefore, the resulting oligosaccharides are also the subject of this invention. This invention also relates to a method for producing oligosaccharides by acid-catalyzed degradation of cellulose in phosphoric acid, these oligosaccharides having an average number of 1.5 to 10 β-1,4-glycosidic bonds linking pyranose units. The oligosaccharides are then separated and enriched, wherein DP ≤ 8, preferably ≤ 6, more particularly ≤ 4. Such separation methods are known and are based on the different solubility and crystallization characteristics of individual oligosaccharides in water and in water-miscible solvents (e.g., acetone or tetrahydrofuran). Acid-catalyzed degradation of cellulose is described, for example, by Liebert, Marit Seifert, and Thomas Heinze in Macromolecular Symposia, 2008, 262, pp. 140-149, Wiley.

[0027] Oligosaccharides (often also known as cellulose dextrins) are generally known from the literature and are commercially available. An example is cellobiose from Savanna Ingredients Ltd.

[0028] According to a particularly preferred embodiment, polymerization is carried out in the presence of cellobiose (D-glucosyl-β-(1→4)-D-glucopyranose) as an oligosaccharide. The production of cellobiose is known and can be carried out biotechnically, for example by enzymatic hydrolysis of cellulose or via the enzymatic conversion of sucrose.

[0029] The polymerization is preferably carried out in the presence of an oligosaccharide having a cellobiose fraction of ≥ 90%, preferably ≥ 95%, and more particularly ≥ 99% by weight. Preferably, the cellobiose is selected as an oligosaccharide.

[0030] In a preferred method, polymerization is carried out in the presence of oligosaccharides, preferably 5% to 50% by weight, based on the total monomers.

[0031] According to the present invention, the polymerized monomer composition comprises

[0032] At least one (meth)acrylic acid C1 to C1, comprising 50% to 99.9% by weight. 10 Alkyl esters and / or vinyl aromatic compounds (Class I), or

[0033] At least one vinyl aromatic compound and a conjugated aliphatic diene (Class II) by weight, comprising 50% to 99.9% of the total weight, or

[0034] Vinyl acetate, vinyl propionate, vinyl tert-carbonate, long-chain fatty acid vinyl esters and / or ethylene (Class III) by weight, ranging from 50% to 99.9%.

[0035] These quantities are based on total monomers in each case.

[0036] Preferred monomer compositions are those of types I and II. Particularly preferred are polymerizations of monomer compositions comprising:

[0037] (a) at least one vinyl aromatic compound, in amounts of 19.9% ​​to 80% by weight.

[0038] (b) 19.9% ​​to 80% by weight of at least one conjugated aliphatic diene and / or (meth)acrylic acid C1 to C10 alkyl ester;

[0039] (c) 0.1% to 10% by weight of at least one olefinic unsaturated acid,

[0040] (d) 0% to 20% by weight of one or more olefinically unsaturated monomers different from monomers (a), (b) and (c),

[0041] These quantities are based on total monomers in each case.

[0042] The polymerization is carried out in the presence of oligosaccharides having an average number of 1.5 to 10, preferably 2 to 6, β-1,4-glycosidic bonds linking pyranose units.

[0043] Particularly preferred are polymers of monomer compositions comprising the following:

[0044] (a) at least one vinyl aromatic compound, in amounts of 19.9% ​​to 80% by weight.

[0045] (b) 19.9% ​​to 80% by weight of at least one conjugated aliphatic diene and / or (meth)acrylic acid C1 to C10 alkyl ester;

[0046] (c) 0.1% to 10% by weight of at least one olefinic unsaturated acid,

[0047] (d) 0% to 20% by weight of one or more olefinically unsaturated monomers different from monomers (a), (b) and (c),

[0048] These quantities are based on total monomers in each case.

[0049] The polymerization is carried out in the presence of oligosaccharides, more particularly cellobioses, having an average number of 1.8 to 2.2 β-1,4-glycosidic bonds linking pyranose units.

[0050] According to another preferred embodiment, the polymerized monomer composition comprises the following:

[0051] (b) at least one C1 to C10 alkyl ester of (meth)acrylic acid, in amounts of 50% to 99.9% by weight.

[0052] (c) 0.1% to 10% by weight of at least one olefinic unsaturated acid,

[0053] (d) 0% to 40% by weight of one or more olefinically unsaturated monomers different from monomers (a), (b) and (c),

[0054] These quantities are based on total monomers in each case.

[0055] The polymerization is carried out in the presence of oligosaccharides, more particularly cellobioses, having an average number of 1.8 to 2.2 β-1,4-glycosidic bonds linking pyranose units.

[0056] Vinyl aromatic compounds are used as monomers (a) in an amount of 19.9% ​​to 80% by weight, preferably 25% to 70% by weight, and more particularly 25% to 60% by weight, based on 100% of the monomer. Examples of vinyl aromatic compounds include styrene, α-methylstyrene, and vinyltoluene. Styrene, methylstyrene, and mixtures thereof are preferred. Styrene is particularly preferred.

[0057] Exemplary conjugated aliphatic dienes (b) include 1,3-butadiene, isoprene, 1,3-pentadiene, dimethyl-1,3-butadiene, and cyclopentadiene. From this group of monomers, 1,3-butadiene and / or isoprene are preferred.

[0058] Acrylate monomer (b) is selected from acrylic acid C1 to C1. 10 Alkyl esters and C1 to C1 methacrylic acid 10 Alkyl esters. These are acrylic acid and methacrylic acid with monocalcium C1 to C2 atoms. 10 Esters of alcohols, such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, sec-butyl acrylate, sec-butyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, amyl acrylate, amyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, or propylheptaacrylate. The acrylate monomers are preferably selected from C1 to C8 alkyl acrylates and C1 to C8 alkyl methacrylates, and more particularly from methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, 2-octyl acrylate, and mixtures thereof.

[0059] In the case of esters of bio-derived alcohols, the "biocarbon fraction" of the polymer can be increased. Suitable alcohols for acrylates are, for example, isobutanol, isoamyl alcohol, and 2-octanol. The biocarbon fraction increased in this way reduces the fossil carbon fraction and reduces the CO2 requirement in the production of polymer dispersions.

[0060] The term "biocarbon" indicates that the carbon is of biological origin and comes from biomaterials / renewable raw materials. Renewable raw materials or biomaterials are organic materials in which the carbon originates from CO2 recently (on a human scale) fixed from the atmosphere through photosynthesis. Biomaterials (100% naturally derived carbon) have a carbon content greater than 10⁻⁶. -12 Typically about 1.2 × 10 -12 isotope ratio 14 C / 12 C, while fossil material has a zero ratio. In fact, 14 C isotopes are formed in the atmosphere and then combined through photosynthesis over a period of several decades. 14 The half-life of carbon is 5730 years. Therefore, materials derived from photosynthesis (usually plants) must have the highest content of carbon. 14C isotopes. The content of biomaterials or biocarbon can be determined according to standard ASTM D6866-12, method B (ASTM D 6866-06) and ASTM D 7026 (ASTM D 7026-04).

[0061] Monomer (b) is used in an amount of 19.9% ​​to 80% by weight of total monomers, preferably 25% to 70% by weight and more particularly 25% to 60% by weight.

[0062] The olefinic unsaturated acid is used as monomer (c) in an amount of 0.1% to 10%, preferably 0.2% to 8% or 1% to 6% by weight, based on 100% of the monomer by weight. Examples of olefinic unsaturated acids include olefinic unsaturated carboxylic acids, olefinic unsaturated sulfonic acids, and vinylphosphonic acids. The olefinic unsaturated carboxylic acids used are preferably α,β-monoolefinic unsaturated monocarboxylic acids and dicarboxylic acids having 3 to 6 carbon atoms in the molecule. Examples of these are acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, vinylacetic acid, and vinyllactic acid. Examples of suitable olefinic unsaturated sulfonic acids include vinylsulfonic acid, styrenesulfonic acid, acrylamide methylpropanesulfonic acid, sulfonyl acrylate, and sulfonyl methacrylate. The olefinic unsaturated acid can be used in polymerization in the form of a free acid as well as in the form of partially or completely neutralized with a suitable base. Sodium hydroxide solution, potassium hydroxide solution, or ammonia are preferably used as neutralizing agents.

[0063] Alternatively, other olefinically unsaturated compounds different from the monomers described above may be used. These additional monomers may be used in amounts of 0% to 20% by weight, for example, 0.1% to 15% by weight or 0.5% to 10% by weight, based on a 100% monomer mixture. Examples of these additional monomers include unsaturated nitriles (such as acrylonitrile and methacrylonitrile), olefinically unsaturated carboxamides (such as acrylamide, methacrylamide, N-hydroxymethylacrylamide and N-hydroxymethylmethacrylamide, N,N-dialkylaminoalkylacrylamide, N,N-dialkylaminoalkylmethylacrylamide), vinyl esters of saturated C1 to C18 carboxylic acids (such as vinyl acetate), allyl esters of saturated carboxylic acids, vinyl ethers, vinyl ketones, dialkyl esters of olefinically unsaturated dicarboxylic acids, N-vinylpyrrolidone, N-vinylpyrrolidine, N-vinylformamide, N,N-dialkylaminoalkyl acrylate, N,N-dialkylaminoalkyl methacrylate, vinyl chloride, and vinylidene chloride.

[0064] The other monomer is preferably mono-olefinically unsaturated. However, polyunsaturated monomers, and more particularly crosslinked monomers having two or more olefinic double bonds, such as alkyl diacrylates, for example, butanediol diacrylate.

[0065] Preferred use

[0066] (a) 25% to 70% by weight of styrene and / or methylstyrene,

[0067] (b) 25% to 70% by weight of at least one acrylic acid C1 to C 10 Alkyl esters

[0068] (c) 1% to 10% by weight, preferably 1% to 6% by weight, of at least one olefinic unsaturated acid, preferably selected from acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, vinylacetic acid, vinyl lactic acid, vinyl sulfonic acid, styrene sulfonic acid, acrylamide methylpropane sulfonic acid, propyl acrylate, and propyl methacrylate.

[0069] (d) 0% to 20% by weight of one or more olefinically unsaturated monomers different from monomers (a), (b) and (c),

[0070] These quantities are based on total monomers in each case.

[0071] In a preferred embodiment, using

[0072] (a) 25% to 60% styrene by weight,

[0073] (b) 25% to 60% by weight of n-butyl acrylate,

[0074] (c) 1% to 10% by weight, preferably 1% to 6% by weight, of acrylic acid, and

[0075] (d) 0% to 20% by weight of one or more olefinically unsaturated monomers different from monomers (a), (b) and (c),

[0076] These quantities are based on total monomers in each case.

[0077] Emulsion polymerization is carried out in an aqueous medium. This can be, for example, completely deionized water, or a mixture of water and a solvent miscible therewith (such as methanol, ethanol, ethylene glycol, glycerol, sugar alcohols such as sorbitol, or tetrahydrofuran). Preferably, the medium is water.

[0078] The total amount of the aqueous medium is proportional to such that the obtained aqueous polymer dispersion has a solid content of preferably ≥ 40% by weight, more preferably 50% to 60% by weight, and more particularly ≥ 50% by weight based on the weight of the aqueous dispersion.

[0079] Polymerization conditions should generally be understood to refer to the amounts of free radical initiator, temperatures, and pressures under which free radical-initiated aqueous emulsion polymerization will not cease. The relationship between temperature and decomposition rate for commonly used polymerization initiators is well known to those skilled in the art or can be determined through routine experiments.

[0080] It should be understood that, for the production of polymer dispersions, the scope of this document is also intended to include seed patterns familiar to those skilled in the art, as well as, for example, staged and gradient patterns of monomer feeding methods and their mixing forms.

[0081] According to a preferred embodiment, emulsion polymerization is carried out using a monomer-feed method. In other words, the monomer and, optionally, the emulsifier are metered in a continuous volumetric flow. According to one embodiment, a portion of 1% to 10% by weight may be included in the initial charge to initiate polymerization therein.

[0082] In the context of the methods of this invention, "emulsifier" means an emulsifying aid. Those skilled in the art will typically understand this to mean an emulsifying aid that maintains both monomer droplets and polymer particles dispersed in the aqueous phase and thus ensures the stability of the produced aqueous polymer dispersion. Useful emulsifiers of this kind are typically used for free radical aqueous emulsion polymerization.

[0083] Useful emulsifiers include surface-active substances having a number-average molecular weight typically below 2000 g / mol or preferably below 1500 g / mol.

[0084] Suitable emulsifiers include not only anionic and cationic emulsifiers, but also nonionic emulsifiers. The surfactants used are preferably emulsifiers with a relative molecular weight typically lower than that of the protective colloid.

[0085] Suitable anionic emulsifiers are, for example, alkali metal salts and ammonium salts of the following: alkyl sulfates (alkyl: C8-C). 22 ), ethoxylated alkanols (EO level: 2 to 50, alkyl: C 12 -C 18 Monosulfate of alkylphenols and ethoxylated alkylphenols (EO levels: 3 to 50, alkyl: C4-C9) monosulfate, alkyl sulfonic acids (alkyl: C4-C9) monosulfate 12 -C 18 ), alkyl aryl sulfonic acid (alkyl: C9-C) 18 ) and sulfosuccinic acid and C4-C 18Diesters of alkanols. Other suitable emulsifiers can be found in Houben-Weyl, Methoden derorganischen Chemie [Methods of Organic Chemistry], Vol. XIV / 1, Makromolekulare Stoffe [Macromolecular Compounds], Georg-Thieme-Verlag, Stuttgart, 1961, pp. 192-208. Also suitable as anionic emulsifiers are those with C4-C5 atoms on one or both aromatic rings. 24 Alkyl bis(phenylsulfonic acid) ethers and their alkali metal or ammonium salts. These compounds are generally known, for example, from US-A-4,269,749, and are commercially available, for example as Dowfax® 2A1 (Dow Chemical Company).

[0086] Suitable nonionic emulsifiers are aryl or aliphatic nonionic emulsifiers, such as ethoxylated mono, di, and trialkylphenols (EO level: 3 to 50, alkyl: C4-C). 10 ), ethoxylated long-chain alcohols (EO level: 3 to 100, alkyl: C8-C) 36 ) and poly(ethylene oxide) / poly(propylene oxide) homopolymers and copolymers. These may contain alkyl oxide units copolymerized randomly or in block form. A very suitable example is an EO / PO block copolymer. Ethoxylated long-chain alkanols (alkyl: C1-C) are preferred. 30 (average ethoxylation level of 5 to 100), and among these, those with straight-chain C are particularly preferred. 12 -C 20 Alkyl groups and those with average ethoxylation levels of 10 to 50, as well as ethoxylated monoalkylphenols.

[0087] It is preferred to use at least one anionic and / or at least one nonionic emulsifier.

[0088] Preferably, the emulsifier is selected from the alkali metal salts and ammonium salts of the following: C8-C 22 Alkyl sulfates and ethoxylated alkanols (EO levels: 2 to 40, alkyl: C) 12 -C 18 Monosulfate esters of alkylphenols (EO levels: 10 to 40, alkyl: C4-C9); and monosulfate esters of alkylphenols (EO levels: 10 to 40, alkyl: C4-C9); and monosulfate esters of alkylphenols with C4-C9 on one or both aromatic rings. 24 Alkyl bis(phenylsulfonic acid) ethers and their alkali metal or ammonium salts.

[0089] Emulsifiers are particularly preferred – mixtures used in each case in the form of their alkali metal salts and ammonium salts, especially alkyl sulfates (alkyl: C8-C). 22 ) and ethoxylated alkanols (EO level: 2 to 40, alkyl: C 12 -C 18 Monosulfate of alkyl phenol (EO level: 10 to 40, alkyl: C4-C9) or a mixture of alkyl phenol (EO level: 10 to 40, alkyl: C4-C9) sulfate or alkyl phenol (EO ... 24 A mixture of alkyl bis(phenylsulfonic acid) ethers or their alkali metal or ammonium salts (e.g., Dowfax 2A1 from Dow Chemical Company).

[0090] The method according to the invention uses free radical initiators (also known as free radical polymerization initiators), which are initiators that form free radicals under reaction conditions. These can include both peroxides and azo compounds. Redox initiator systems are also suitable.

[0091] The peroxides used can be inorganic and / or organic. Examples of suitable inorganic peroxides include hydrogen peroxide and peroxydisulfate, such as mono- or dialkali metal salts or ammonium salts of peroxydisulfate, for example, their mono- and disodium, mono- and dipotassium, or ammonium salts. Examples of suitable organic peroxides are alkyl hydrogen peroxides such as tert-butyl hydrogen peroxide, aryl hydrogen peroxides such as p-menthyl or cumene hydrogen peroxide, and dialkyl or diaryl peroxides such as di-tert-butyl peroxide, dibenzoyl peroxide, or dicumene peroxide.

[0092] A redox initiator system is a combination system consisting of at least one organic or inorganic reducing agent and at least one peroxide. Suitable oxidants for redox initiator systems are essentially the peroxides mentioned above. The appropriate reducing agents that can be used are sulfur compounds with low oxidation states, such as alkali metal sulfites, for example, potassium sulfite and / or sodium sulfite; alkali metal bisulfites, for example, potassium bisulfite and / or sodium bisulfite; alkali metal metabisulfites, for example, potassium metabisulfite and / or sodium metabisulfite; acetone bisulfite, formaldehyde sulfite, for example, potassium formaldehyde sulfide and / or sodium formaldehyde sulfide; alkali metal salts of aliphatic sulfinic acids, especially potassium and / or sodium salts; and alkali metal hydrosulfides, for example, potassium hydrosulfide and / or sodium hydrosulfide; salts of polyvalent metals, such as ferric(II) sulfate, ammonium ferric(II) sulfate, ferric(II) phosphate; ethylene glycols, such as dihydroxymaleic acid, benzoin and / or ascorbic acid; and reducing sugars, such as sorbitol, glucose, fructose and / or dihydroxyacetone.

[0093] Preferred free radical initiators are inorganic and organic peroxides, preferably ammonium or alkali metal salts of peroxysulfate or peroxydisulfate, and tert-butyl hydroperoxide, p-menthyl hydroperoxide, and cumyl hydroperoxide, particularly selected from sodium peroxydisulfate and potassium peroxydisulfate, tert-butyl hydroperoxide, and cumyl hydroperoxide. Particularly preferred herein is the use of at least one inorganic peroxide, preferably a peroxydisulfate, more particularly sodium peroxydisulfate, and an organic peroxide, preferably an alkyl hydroperoxide, more particularly both tert-butyl hydroperoxide.

[0094] The polymerization is typically carried out using 100% total monomer by weight, 0.1% to 5% free radical initiator by weight, preferably 0.5% to 4% free radical initiator by weight, and preferably at least one inorganic and / or organic peroxide.

[0095] Initiation of a polymerization reaction should be understood as the polymerization of monomers present in the polymerization vessel beginning due to the decomposition of a free radical initiator. For example, polymerization is initiated when the polymerization mixture contains monomers and inorganic peroxides and reaches a temperature in the range of ≥ 80°C to ≤ 95°C.

[0096] For example, to initiate polymerization, an aqueous mixture comprising a portion of a protective colloid and / or emulsifier in dissolved form, a portion of monomer, and seed latex is first prepared. This mixture is heated to a temperature above the decomposition temperature of the free radical initiator, and a portion of the free radical initiator is metered in. After a few minutes, the monomer is metered in. Advantageously, a further portion of the free radical initiator, preferably an inorganic peroxide, is metered in simultaneously with the monomer.

[0097] In all free radical polymerization reactions, it is advantageous if the initial charge, metering / polymerization, and post-reaction of the reactants are carried out in a reaction vessel under an inert gas atmosphere (e.g., nitrogen or argon).

[0098] Preferred polymerization conditions are temperatures in the range of ≥ 75°C to ≤ 115°C, preferably ≥ 85°C to ≤ 110°C, and more particularly ≥ 90°C to ≤ 105°C.

[0099] Polymerization can occur in the presence of seed latex. Seed latex is typically understood by those skilled in the art to mean a polymer dispersion in which seed particles act as particle-forming centers during polymerization.

[0100] In a preferred variation of the method, the seed latex used has a weight-average particle size D in the range of 20 to 60 nm. w 50 and ≤ 2 of D w 50 / D nA 50-fold ratio of aqueous polymer dispersion. In this text, weight-average particle size should be understood as the weight-average D as determined by analytical ultracentrifugation. w 50, and the number-average particle size should be understood as the number-average D measured by the same method. N 50 (See SE. Harding et al., Analytical Ultracentrifugation in Biochemistry 5, and Polymer Science, Royal Society of Chemistry, Cambridge, UK, 1992, Chapter 10, Analysis of Polymer Dispersions with an Eight-Cell AUC Multiplexer: High Resolution Particle Size Distribution and Density Gradient Techniques, W. Mächtle, pp. 147–175). In the context of this text, a narrow particle size distribution should be understood as the weight-average particle size D, as determined by analytical ultracentrifugation. w 50 and number-average particle size D N 50% ratio [D] w 50 / D N 50] A particle size distribution of not more than 2.0, preferably not more than 1.5, and especially preferably not more than 1.2 or not more than 1.1.

[0101] The production of seed latex is known to those skilled in the art and is typically carried out in the presence of a large amount of emulsifier, resulting in small particle size and narrow particle size distribution. It is generally observed that polymerization in the presence of such exogenous seed latex is characterized by uniform particle growth compared to in-situ seed latex. Seed latex, as its name suggests, is typically used in the form of aqueous dispersions.

[0102] The seed latex is preferably a styrene polymer and / or a methyl methacrylate polymer having a glass transition temperature of ≥ 50°C, ≥ 60°C, ≥ 70°C, ≥ 80°C or ≥ 90°C as measured according to DIN EN ISO 11357-2 (2013-09).

[0103] It is preferred to use seed latex (in solids) based on 0.01% to 4% by weight of total monomers, and particularly 0.02% to 2% by weight.

[0104] The polymerization is preferably initiated in an initial charge containing an aqueous dispersion of polystyrene seed latex based on 100% by weight of total monomers up to 2% by weight, and then the monomers and emulsifiers are added continuously by metering.

[0105] To modify the properties of the polymer, emulsion polymerization can optionally be carried out in the presence of at least one chain transfer agent. These chain transfer agents are typically used to reduce or control the molecular weight of polymers obtainable through free radical aqueous emulsion polymerization.

[0106] Free radical chain transfer compounds (chain transfer agents) can be used to adjust the weight-average molecular weight of the formed polymer. The compounds used here are primarily aliphatic and / or aryliphatic halogen compounds, such as n-butyl chloride, n-butyl bromide, n-butyl iodide, dichloromethane, dichloroethane, chloroform, bromoform, bromotrichloromethane, dibromodichloromethane, carbon tetrachloride, carbon tetrabromide, benzyl chloride, benzyl bromide; and organothioides, such as primary, secondary, or tertiary aliphatic thiols, such as ethanethiol, n-propanethiol, 2-propanethiol, n-butanethiol, 2-butanethiol, 2-methyl-2-propanethiol, n-pentanethiol, 2-pentanethiol, 3-pentanethiol, 2-methyl-2-butanethiol, 3-methyl-2-butanethiol, n-hexanethiol, 2-hexanethiol, 3-hexanethiol, 2-methyl-2-pentanethiol, 3-methyl-2-pentanethiol. 4-Methyl-2-pentanethiol, 2-methyl-3-pentanethiol, 3-methyl-3-pentanethiol, 2-ethylbutanethiol, 2-ethyl-2-butanethiol, n-heptanethiol and its isomers, n-octanethiol and its isomers, n-nonanethiol and its isomers, n-decanethiol and its isomers, n-undecanethiol and its isomers, n-dodecanethiol and its isomers, n-tridecanethiol and its isomers, substituted thiols, such as 2-hydroxyethylthiol, aromatic thiols, such as benzenethiol, ortho-, meta-, or p-methylbenzenethiol, mercaptoalkyl acids and their derivatives (such as 6-methylheptyl 3-mercaptopropionic acid, 2-ethylhexyl 2-mercaptoacetic acid), and in Polymer All other sulfur compounds described in the *Handbook of Polymers*, 3rd edition, 1989, J. Brandrup and E. Himmergut, John Wiley & Sons, Section II, pp. 133-141, and also aliphatic and / or aromatic aldehydes such as acetaldehyde, propionaldehyde, and / or benzaldehyde; unsaturated fatty acids such as oleic acid; dienes with non-conjugated double bonds such as divinylmethane, vinylcyclohexane, or isoprene; or hydrocarbons with readily abstractable hydrogen atoms, such as toluene. However, mixtures of the above-mentioned chain transfer agents that do not interfere with each other may also be used.

[0107] If a chain transfer compound is used in the polymerization, the corresponding amount used is, for example, 0.01% to 5% by weight, and preferably 0.1% to 3% by weight, based on 100% of the monomers used for polymerization.

[0108] According to the invention, the total amount of chain transfer agent may be included in the initial charge in the aqueous reaction medium prior to the initiation of the polymerization reaction. Alternatively, it may be possible to include only a portion of the chain transfer agent in the initial charge in the aqueous reaction medium prior to the initiation of the polymerization reaction, and then, under polymerization conditions, add the total amount or any remaining residual amount in a continuous or discontinuous manner during radical-initiated emulsion polymerization as needed.

[0109] To complete the polymerization reaction, in most cases, after the monomer addition has ended, it is sufficient to stir the reaction mixture at the polymerization temperature for, for example, 0.5 to 3 hours. Typically, a conversion rate of approximately 95% is then achieved.

[0110] To further improve the conversion and thus reduce the residual monomer content, additional radical initiators from the group of initiators described above can be added to the reaction mixture or their addition can be extended and so-called "post-polymerization" can be carried out, which is polymerization that achieves a conversion of >95% to 99%.

[0111] This post-polymerization can be carried out at the same, lower, or higher temperature as the primary polymerization. For example, in this stage, 0.1% to 1.5% by weight of an inorganic peroxide, preferably sodium persulfate, is added based on 100% of the monomers used in the polymerization, and the polymerization temperature is set in the range of 80°C to 120°C.

[0112] During polymerization, the pH can be, for example, between 1 and 5. After polymerization is completed with a conversion rate of >95%, the pH is adjusted, for example, to a value between 6 and 9.

[0113] Alternatively, chemical deodorization can be performed. If trace amounts of residual monomers still need to be removed, this can also be done chemically using the redox initiator systems described above, as well as those specified in DE-A 44 35 423, DE-A 44 19 518, and DE-A 44 35 422.

[0114] The treatment using the redox initiator system is carried out in a temperature range of 60°C to 115°C, preferably 80°C to 100°C. Redox pairs can be added independently, in whole, in batches, or continuously over a period of 10 minutes to 4 hours. To improve the post-polymerization effect of the redox initiator system, a soluble salt of a metal with variable valence, such as an iron salt, copper salt, or vanadium salt, can also be added to the dispersion. A complexing agent that keeps the metal salt in a soluble state under reaction conditions is also typically added.

[0115] Following the polymerization reaction (primary polymerization + post-polymerization) and optional chemical deodorization, it may be necessary to render the aqueous polymer dispersion substantially free of odor carriers, such as residual monomers and other volatile organic components, which is also known as physical deodorization. This can be achieved physically by distillation (particularly via steam distillation) or by stripping with an inert gas, in ways known per se.

[0116] The method of the present invention is an advantageous production method for aqueous dispersions because it is not based on starch derivatives and therefore is not "food-based". Furthermore, a broader base of raw materials is available, and therefore it can be used more universally.

[0117] The present invention also relates to dispersions obtainable by the method according to the invention. These preferably have a solids content of ≥ 45% by weight. Their Brookfield viscosity is preferably < 1000 mPas at 100 rpm, as measured using rotor 3 at 23°C.

[0118] These are noteworthy because they are essentially aqueous dispersions free of condensates. The amount of condensate is in the ppm range and preferably less than 2000 ppm, particularly less than 1000 ppm.

[0119] The aqueous polymer dispersions according to the invention are used as binders, adhesives, and sizing agents for fibers, in the production of coatings, or in the production of paper coating pulp. The aqueous polymer dispersions according to the invention are suitable for sizing both textile fibers and mineral fibers, especially glass fibers. Due to their good peel adhesion, particularly when using comonomers that result in low glass transition temperatures (e.g., less than 20°C) in the copolymer, they can also be used as adhesives, for example, in the production of laminates and in the production of coatings such as barrier coatings. The aqueous polymer dispersions according to the invention are preferably used as binders in paper coating formulations.

[0120] Therefore, another subject of the present invention is a paper coating compound having a solids content in the range of 50% to 85% by weight, the paper coating compound comprising

[0121] (i) Inorganic pigments, and

[0122] (ii) The above-mentioned aqueous polymer dispersion that can be obtained by the method of the present invention

[0123] (iii) and optionally additional adjuvants.

[0124] Besides water, paper coating pulp typically contains pigments, binders, and additives (such as thickeners) to establish the desired rheological properties. Pigments are typically dispersed in water. Paper coating pulp contains pigments in an amount preferably at least 80% by weight, for example, 80% to 95% by weight or 80% to 90% by weight, based on the solids content.

[0125] White pigments are specific candidates. Examples of suitable pigments are metal salt pigments, such as calcium sulfate, calcium aluminate sulfate, barium sulfate, magnesium carbonate, and calcium carbonate, among which carbonate pigments, and especially calcium carbonate, are preferred. Calcium carbonate can be ground calcium carbonate (GCC, naturally ground calcium carbonate), precipitated calcium carbonate (PCC), lime, or chalk. Suitable calcium carbonate pigments are, for example, Covercarb. ® 60. Hydrocarb ® 60 or Hydrocarb ® 90 ME is available. Other suitable pigments include, for example, silica, aluminum oxide, aluminum hydroxide, silicates, titanium dioxide, zinc oxide, kaolin, alumina, talc, or silicon dioxide. Other suitable pigments include, for example, Capim. ® MP 50 (Clay), Hydragloss ® It can be obtained with 90 (clay) or Talcum C10.

[0126] The paper coating pulp contains a polymer dispersion produced according to the present invention as the sole binder or in combination with other binders. The most important function of the binder in the paper coating pulp is to bind the pigment to the paper and to bind the pigments to each other, as well as to fill the cavities between the pigment particles to a certain extent.

[0127] For example, based on 100% by weight of pigment, use 1% to 50% by weight, preferably 1% to 25% by weight, or 5% to 20% by weight of the polymer (solid / solid) according to the invention.

[0128] Preferred paper coating pulp comprises a polymer of an aqueous polymer dispersion in an amount of 5% to 50% by weight based on the total amount of pigment, and pigment in an amount of 80% to 95% by weight based on the solid content, and additives, wherein the pigment is preferably selected from the group consisting of: calcium sulfate, calcium aluminate sulfate, barium sulfate, magnesium carbonate, calcium carbonate, silica, aluminum oxide, aluminum hydroxide, silicate, titanium dioxide, zinc oxide, kaolin, alumina, talc, and silicon dioxide, and wherein the additives are selected from the group consisting of: thickeners, additional polymer binders, co-binders, optical brighteners, fillers, leveling aids, dispersants, surfactants, lubricants, neutralizers, defoamers, degassing agents, preservatives, and dyes.

[0129] Other synthetic binders, unlike those produced by the polymers according to the present invention, are common knowledge and are described, for example, in D. Urban and K. Takamura, Polymer Dispersions and Their Industrial Applications, 2002, Wiley-VCH Verlag GmbH, Weinheim, Chapter 4.4.4, page 90 and thereafter, the disclosure of which is expressly incorporated by reference.

[0130] Other useful binders include binders with natural bases, especially starch-based binders, and synthetic binders different from polymers produced according to the invention, especially emulsion polymers that can be produced by emulsion polymerization. In this context, "starch-based binder" should be understood to mean any natural, modified, or degraded starch. Natural starch can consist of amylose, amylopectin, or mixtures thereof. Modified starch can be oxidized starch, starch esters, or starch ethers. The molar weight of starch can be reduced by hydrolysis (degrading starch). Oligosaccharides or dextrins are possible degradation products. Preferred starches are cereal starch, corn starch, and potato starch. Cereal starch and corn starch are particularly preferred; corn starch is very particularly preferred.

[0131] The paper coating pulp according to the invention may additionally contain additional additives, examples of which are fillers, co-binders, and thickeners for further optimizing viscosity and water retention, optical brighteners, dispersants, surfactants, lubricants (e.g., calcium stearate and waxes), neutralizers for adjusting pH (e.g., NaOH or ammonium hydroxide), defoamers, degassing agents, preservatives (e.g., biocides), leveling aids, dyes (especially soluble dyes), etc. Useful thickeners include not only synthetic polymers (e.g., cross-linked polyacrylates), but also, in particular, cellulose, preferably carboxymethyl cellulose. Optical brighteners are, for example, fluorescent or phosphorescent dyes, especially piracetam.

[0132] The paper coating pulp is preferably an aqueous pulp; it contains water, especially since the formulation of the components (aqueous polymer dispersions, aqueous pigment pastes) already contains water; the desired viscosity can be set by adding additional water. The conventional solids content of the paper coating pulp is in the range of 30% to 80% by weight. The pH of the paper coating pulp is preferably set to a value of 6 to 11, especially 7 to 10.

[0133] Another subject of the present invention is paper or board coated with the paper coating pulp of the present invention, and a method for coating paper or board, wherein,

[0134] - To produce an aqueous polymer dispersion according to the present invention; and

[0135] - To produce paper coating pulp using this polymer dispersion, at least one pigment and optional additional additives; and to apply the paper coating pulp to at least one surface of paper or board.

[0136] Preferably, the paper coating slurry is applied to uncoated base paper or uncoated board. The amount is typically 1 to 50 g per square meter, preferably 5 to 30 g (in solids, i.e., without water or other solvents that are liquid at 21°C and 1 bar). Coating can be carried out by conventional application methods, such as by sizing press, film pressing, doctor blade coating, air brush, knife coating, curtain coating, or spray coating. Depending on the pigment system, aqueous dispersions of water-soluble copolymers can be used in the paper coating slurry for use as a base coat and / or for use as a top coat.

[0137] The paper coating pulps of this invention possess excellent performance characteristics. They exhibit good flow characteristics and high adhesion in paper coating methods. The coated paper and board have good surface strength, especially very high wet and dry fuzzing resistance. They are readily printable using conventional printing methods such as relief printing, gravure printing, offset printing, digital printing, inkjet printing, flexographic printing, newsprint printing, letterpress printing, sublimation printing, laser printing, electrostatic copying, or combinations thereof. Example

[0138] Unless the context otherwise indicates otherwise, percentages always represent weight percentages.

[0139] The reported content refers to the content in aqueous solutions or dispersions. Unless otherwise stated, solutions / dispersions by weight % are always aqueous solutions / dispersions.

[0140] When water is used in the context of an instance, demineralized water is used.

[0141] Measurement methods

[0142] Determination of the viscosity of dispersions:

[0143] The viscosity of the dispersion was determined according to ASTM D2196 using a Brookfield viscometer with an RV 3 rotor at 100 rpm and at a temperature of 23°C.

[0144] Solid content:

[0145] The solids content of the dispersion was determined using an IR moisture analyzer. This is a thermogravimetric analysis method in which an analytical balance is combined with an infrared lamp. 1–2 g of the dispersion was finely distributed over a glass filter and dried at 100°C to constant mass. Constant mass is defined as a weight loss of less than 2 mg within 45 s.

[0146] The following starting materials are used in the example:

[0147] Emulsifier A: Sodium dodecylbenzenesulfonate

[0148] Seed latex: Polystyrene seeds in the form of a 32.4% by weight dispersion with a particle size of approximately 30 nm (determined by analytical ultracentrifugation).

[0149] Initiator A: 5% sodium persulfate (NaPS) solution by weight

[0150] Initiator B: 3% by weight tert-butyl hydrogen peroxide solution

[0151] Reducing agent: 14% acetone bisulfite solution by weight

[0152] Cellobiose manufacturer: Savanna Ingredients Ltd., food grade

[0153] Lamperts maltodextrin 19DE (dextrose equivalent) is a degraded starch with a content of 19 (from Lamperts).

[0154] Example 1: Oligosaccharide Production

[0155] To synthesize the oligosaccharide, 5 g of microcrystalline cellulose with an average particle size of 50 µm was added to 60 ml of 85% phosphoric acid by weight, and dissolved while stirring, with the temperature not exceeding 55°C during the mixing process. The mixture was then heated at 55°C for 20 hours.

[0156] Add the mixture to an excess of acetone (7-10 times) to precipitate the cellulose oligomers as a crude product. Decant the suspension and discard the liquid phase.

[0157] For purification, the precipitate was dispersed in approximately 5 ml of water, centrifuged and decanted, and the extract was collected. This process was repeated twice more, dispersing the precipitate in 5 ml of water, centrifuging and decanting, and combining the aqueous extracts. The aqueous phase (approximately 10 ml) was concentrated to 3 ml under reduced pressure at room temperature. The oligosaccharides were precipitated by adding acetone (approximately 100 ml) and separated by centrifugation and decanting. The oligosaccharides obtained in this manner (approximately 2–3 g) were washed with acetone and air-dried at room temperature.

[0158] Determination of oligosaccharide composition:

[0159] The oligosaccharides obtained according to Example 1 were dissolved in water (concentration 0.25 to 2 mg / ml H2O) and analyzed by HPLC (a Eurokat Na column from Knauer) with a connected RI detector. The eluent used was ultrapure water containing 0.1 mM NaN3. Calibration was performed using identified cellulosic oligosaccharides from Megazyme.

[0160] For the oligosaccharide from Example 1, the following composition was determined: 1% glucose by weight, 5% cellobiose by weight, 15% cellotriose by weight, 20% cellotetraose by weight, and 59% water-soluble cellulose oligomers having 5 to 10 pyranose units by weight.

[0161] Production of emulsion polymers

[0162] The following quantities, expressed in pphm (parts per hundred parts of monomer), are based on 100 parts by weight (= 100% by weight) of total monomer.

[0163] Example 2: Emulsion polymerization of styrene / n-butyl acrylate / acrylic acid / cellulose oligosaccharide

[0164] Initial loading:

[0165] 223 g water

[0166] 39 g of fiber oligosaccharides from Example 1 (8% water content by weight) (20 pphm)

[0167] 7.22 g of 32.4% aqueous polystyrene latex dispersion by weight (average particle size = 30 nm; 1.3 pphm)

[0168] Additive 1:

[0169] 10.8 g of 5% sodium persulfate aqueous solution (0.3 pphm)

[0170] Feed 1:

[0171] 6.6 g acrylic acid (3.5 pphm)

[0172] 1.95 g sodium dodecyl benzyl sulfonate (1 pphm) 97% by weight

[0173] 78 g styrene (41.5 pphm)

[0174] 104 g n-Butyl acrylate (55 pphm)

[0175] 43 g water

[0176] Feed 2:

[0177] 29.16 g of 5% sodium persulfate aqueous solution (0.81 pphm) by weight

[0178] Additive 2:

[0179] 9.6 g of 15% sodium hydroxide solution (by weight)

[0180] Feed 3:

[0181] 7.8 g of 3% tert-butyl hydrogen peroxide solution (0.13 pphm) by weight

[0182] Feed 4:

[0183] 9.05 g of 14.10% acetone bisulfite solution (0.7 pphm) by weight

[0184] Additive 3:

[0185] 3.6 g of 15% sodium hydroxide solution (by weight)

[0186] The initial charge components were placed in a 2 L glass reactor pre-purged with nitrogen and mixed. The initial charge was heated to 93°C. When the temperature reached 80°C, the initiator (additive 1) was slowly added and polymerization began.

[0187] Feeding 1 and 2 were then started immediately thereafter. Feed 1 was carried out over a 3-hour period, and feed 2 was carried out over a 3.5-hour period. Feed 1, in emulsion form, was loaded into the reactor.

[0188] After feed 2 is metered, the mixture is stirred at 93°C for another 30 minutes. Then additive 2 is added and the polymerization mixture is stirred for another 30 minutes. Subsequently, feeds 3 and 4 are metered in parallel over 1 hour at 80°C. After the reaction mixture is cooled to room temperature, additive 3 is added.

[0189] The solids content of the dispersion is 38% by weight.

[0190] Study of polymer dispersions using an analytical ultracentrifuge:

[0191] The obtained dispersion is monodisperse and has an average particle size of 169 nm, wherein 10% of the particles have a mass fraction of not less than 142 nm and 90% of the particles have a mass fraction of not more than 192 nm.

[0192] Example 3: Emulsion polymerization of styrene / n-butyl acrylate / acrylic acid / cellulose bisaccharide

[0193] Example 3 was carried out in a similar manner to Example 2, except that 20 pphm of cellobiose powder was used in the initial charge.

[0194] The solids content of the dispersion is 39% by weight.

[0195] Study of polymer dispersions using an analytical ultracentrifuge:

[0196] The obtained dispersion is monodisperse and has an average particle size of 118 nm, wherein 10% of the particles have a mass fraction of not less than 112 nm and 90% of the particles have a mass fraction of not more than 126 nm.

[0197] Example 4 (not according to the present invention) Emulsion polymerization of styrene / n-butyl acrylate / acrylic acid

[0198] Example 4 was carried out in a similar manner to Example 3, except that 20 pphm of maltodextrin powder (Lamperts maltodextrin 19) was used in the initial charge.

[0199] The solids content of the dispersion is 38% by weight.

[0200] Study of polymer dispersions using analytical ultracentrifuges:

[0201] The obtained dispersion is monodisperse and has an average particle size of 112 nm, wherein 10% of the particles have a mass fraction of not less than 92 nm and 90% of the particles have a mass fraction of not more than 141 nm.

[0202] Example 5 - Styrene / Butadiene / Acrylic Acid / Cellobiose

[0203] Initial loading:

[0204] 1637.41 g demineralized water (113 pphm)

[0205] 295.92 g of 98% cellobiose powder (20 pphm) by weight

[0206] 7.25 g of 2.0% Trilon BX solution (0.01 pphm) by weight

[0207] 2.59 g of 28% Texapon NSO P solution (0.05 pphm) by weight

[0208] Additive 1:

[0209] 103.57 g of 7% sodium persulfate solution (initiator) (0.5 pphm)

[0210] Feed 1:

[0211] 2.59 g of 28% Texapon NSO P solution (0.05 pphm) by weight

[0212] 433.0 g water (30 pphm)

[0213] Feed 2:

[0214] 58.0 g acrylic acid (4.0 pphm)

[0215] 826.5 g styrene (57 pphm)

[0216] 13.05 g tert-dodecyl mercaptan (0.9 pphm)

[0217] Feed 3:

[0218] 565.5 g 1,3-Butadiene (39 pphm)

[0219] Feed 4:

[0220] 103.57 g of 7% sodium persulfate solution (0.5 pphm) by weight

[0221] Feed 5:

[0222] 29.0 g of 10% tert-butyl hydrogen peroxide solution (0.2 pphm)

[0223] Feed 6:

[0224] 35.0 g of 14.10% acetone bisulfite solution (0.34 pphm) by weight

[0225] Additive 2:

[0226] 61.0 g of 15% sodium hydroxide solution (0.63 pphm) by weight

[0227] The initial charge components were placed in a 6 L pressure reactor and mixed. The reactor was purged with nitrogen. The initial charge was heated to 95°C. When 90°C was reached, the initiator (additive 1) was slowly added, and feeds 1, 2, 3, and 4 were started and carried out over a period of 2.5 h. After feeds 1, 2, 3, and 4 were completed, the mixture was maintained at 95°C with stirring for 30 minutes to terminate the polymerization. 117 g of demineralized water was then added. The reaction mixture was then cooled to 90°C. Feeds 5 and 6 were then supplied in parallel over 1.5 h. The reactor was cooled to room temperature and additive 2 was introduced into the reactor. The solids content of the dispersion was 38% by weight.

[0228] Study of polymer dispersions using analytical ultracentrifuges:

[0229] The obtained dispersion is monodisperse and has an average particle size of 173 nm, wherein 10% of the particles have a mass fraction of not less than 164 nm and 90% of the particles have a mass fraction of not more than 187 nm.

[0230] Example 6 - Styrene / Butadiene / Acrylic Acid / Maltodextrin (not according to the present invention)

[0231] Example 6 was carried out in a similar manner to Example 5, except that 20 pphm of maltodextrin (Lamperts maltodextrin 19) was used in the initial charge.

[0232] The solids content of the dispersion is 38.7% by weight.

[0233] Study of polymer dispersions using analytical ultracentrifuges:

[0234] The obtained dispersion is monodisperse and has an average particle size of 97 nm, wherein 10% of the particles have a mass fraction of not less than 74 nm and 90% of the particles have a mass fraction of not more than 119 nm.

[0235] Example 7 - Styrene / acrylate / acrylic acid / maltose (not according to the present invention)

[0236] Example 7 was performed similarly to Example 3, except that 20 pphm of maltose was used in the initial charge.

[0237] The solids content of the dispersion is 38.7% by weight.

[0238] Study of polymer dispersions using analytical ultracentrifuges:

[0239] The obtained dispersion is monodisperse and has an average particle size of 109 nm, wherein 10% of the particles have a mass fraction of not less than 103 nm and 90% of the particles have a mass fraction of not more than 142 nm.

[0240] Example 8 (not based on the present invention)

[0241] Emulsion polymerization of styrene / n-butyl acrylate / acrylic acid / glucose

[0242] Example 8 was carried out similarly to Example 2, except that 20 pphm of glucose was used instead of polysaccharide in the initial charge.

[0243] The solids content of the dispersion is 38.9% by weight.

[0244] Study of polymer dispersions using analytical ultracentrifuges:

[0245] The obtained dispersion is monodisperse and has an average particle size of 114 nm, wherein 10% of the particles have a mass fraction of not less than 109 nm and 90% of the particles have a mass fraction of not more than 126 nm.

[0246] Example 9: Glucose syrup (not according to the present invention)

[0247] Emulsion polymerization of styrene / n-butyl acrylate / acrylic acid / glucose syrup

[0248] Example 9 was conducted similarly to Example 2, except that 20 pphm of dried glucose (anhydrous glucose syrup, DE = 28-32) was used instead of the cellulosic sugar in the initial charge. The dried glucose used had a DE much lower than LP 19 (Example 4) and higher fractions of glucose, maltose, and maltotriose.

[0249] The solids content of the dispersion is 39.3% by weight.

[0250] Study of polymer dispersions using analytical ultracentrifuges:

[0251] The obtained dispersion is monodisperse and has an average particle size of 125 nm, wherein 10% of the particles have a mass fraction of not less than 119 nm and 90% of the particles have a mass fraction of not more than 134 nm.

[0252] Table 1: Case Overview

[0253]

[0254] The example generated in Example 1

[0255] ni: Not based on this invention

[0256] Characterization of the mechanical properties of polymer dispersions

[0257] Storage modulus G' (deformation) is measured via dynamic-mechanical-thermal analysis (DMTA). The G' value is considered a measure of the deformation energy stored in the sample material during a shearing process. Materials that fully store deformation energy exhibit reversible deformation behavior; they remain in an invariant form after loading / unloading cycles. G' is a measure of the elastic behavior of polymer films.

[0258] The dynamic-mechanical properties of the membranes were analyzed under torsion using a rheometer. For this purpose, membranes were produced from polymer dispersions and dried. The membranes were dried in a drying oven at 30°C for at least 4 days until they appeared completely transparent. Subsequently, the membranes were heated at 40°C for 3 hours. Prior to testing, the membranes were conditioned in a climate chamber at 23°C and 50% relative humidity for at least 48 hours. The obtained membrane thicknesses were between 1 mm and 2 mm. For measurements, strips 10 mm wide and 30–40 mm long were punched from the membranes.

[0259] The membrane strips were subjected to vibrational loads under torsion. The measured parameters are listed in the following tabular form.

[0260] Measurement parameters:

[0261] Application: RHEOPLUS / 32 V3.40 21004578-33024

[0262] Instrument: MCR501

[0263] Manufacturer: Anton Paar

[0264] Measurement System: SRF12-SN19150

[0265] The measurements were performed isothermally at 30°C with a frequency of 0.1 Hz and a deformation rate of 0.01% to 20% under vibration.

[0266] The result of the mechanical characteristics of polymer films

[0267] In DMTA measurements, quartiles are statistical measures that represent the proportion of a data point within four quartiles. The first quartile (Q1) represents the value below which 25% of the data points fall, the second quartile (Q2) is the median, and the third quartile (Q3) represents the value below which 75% of the data points fall. These quartiles are used to analyze the scattering and distribution of storage modulus measurements. The higher the storage modulus, the more deformation energy the membrane can store.

[0268] Table 2:

[0269]

[0270] ni: Not based on this invention

[0271] 5.0e8 = 5.0 . 10 8

[0272] The results showed that the dispersion produced in the presence of cellobiose (Example 3, according to the invention) had a significantly higher storage modulus than the dispersion produced in the presence of maltose (Example 7, not according to the invention). Similarly, the dispersion of Example 2 according to the invention (produced in the presence of β-1,4-glycosidic linked pyranose units) had a higher storage modulus than the non-inventive dispersions of Examples 4 and 9 (produced in the presence of α-1,4-glycosidic linked pyranose units). This indicates that the membrane of the polymer dispersion according to the invention is more resistant to deformation by external forces.

[0273] Production of paper coating pulp:

[0274] The reported quantities are based on solids content in each case.

[0275] 100% calcium carbonate by weight (Hydrocarb from Omya) ® 60)

[0276] 5% emulsion polymer of the corresponding example by weight

[0277] 0.25% rheological aid (Sterocoll) by weight ® FS, BASF SE

[0278] Paper coating pulp is produced in a mixing device by feeding individual components into the mixing device sequentially.

[0279] Add the pigment (calcium carbonate) in a pre-dispersed form (slurry). Add the other components in the order listed above. Set the final solids content by adding water.

[0280] Paper coating pulp:

[0281] Solid content = 64% by weight

[0282] pH = 9

[0283] Viscosity (Brookfield RVT, rotor 4, 100 rpm): 500-1500 mPas

[0284] Paper coating:

[0285] Magnostar standard wood-free base paper coating pulp at approximately 58 g / m 2 Coating. Apply the coating paste to one side of the paper using a laboratory coating machine at a pressure of approximately 1.45 bar and a speed of 25 cm / min. Dry the coating using three 650 W radiant heaters. Apply by doctor blade coating method. The coating weight is 10-12 g / m² (solids).

[0286] Dry fuzz resistance was measured using an IGT test printing press (IGT dry type):

[0287] Strips were cut from the coated plate to be tested and printed using an IGT test printer. The printing ink used included Lorilleux 3807 Rouge test ink. The test strips were guided through the printer at a continuously rising speed (maximum speed 100 cm / s). The contact pressure was 70 kN / m.

[0288] Clamp the paper strip onto the circular section. Mount the 20 mm wide inking roller onto the upper shaft and apply the set pressure, then begin the printing process.

[0289] Observe the printed test strip under oblique light and mark the position where the printed surface begins to fuzz with a line. The measurement for dry fuzz resistance is the velocity (in cm / s) present during printing and the test ink used.

[0290] Table 3: Performance data of coated paper

[0291]

[0292] ni: Not based on this invention

[0293] These examples demonstrate that paper coated with a paper coating pulp containing a dispersion according to the invention has binding strength comparable to that of a paper coating pulp using a dispersion produced in the presence of degraded starch.

Claims

1. A method for producing an aqueous polymer dispersion by free radical-initiated aqueous emulsion polymerization of a monomer composition comprising... At least one vinyl aromatic compound and / or (meth)acrylic acid C1 to C10 alkyl ester, by weight, comprising 50% to 99.9% of the total amount; At least one vinyl aromatic compound and a conjugated aliphatic diene, by weight, comprising 50% to 99.9% of the following: Vinyl acetate, vinyl propionate, vinyl tert-carbonate, long-chain fatty acid vinyl esters and / or ethylene, by weight, from 50% to 99.9%. These quantities are based on total monomers in each case. The method is carried out by polymerizing the composition in the presence of an oligosaccharide having 1.5 to 10 β-1,4-glycosidic bonds linking pyranose units.

2. The method according to claim 1, wherein, The average number of pyranose units is 2 to 6, more specifically 4 to 5.

3. The method according to claim 1 or 2, wherein, Polymerization is carried out in the presence of oligosaccharides obtained by acid-catalyzed hydrolysis of cellulose and / or in the presence of oligosaccharides obtained by enzymatic hydrolysis of cellulose.

4. The method according to claim 1 or 2, wherein, Polymerization is carried out in the presence of oligosaccharides obtained via enzymatic hydrolysis of cellulose.

5. The method according to any one of claims 1 to 4, wherein, Cellobiose was selected as an oligosaccharide.

6. The method according to any one of claims 1 to 5, wherein, The polymerization is carried out in the presence of oligosaccharides based on 5% to 100% by weight of total monomers, and more particularly 5% to 50% by weight.

7. The method according to any one of claims 1 to 6, wherein, The polymerized monomer composition consists of the following (a) at least one vinyl aromatic compound, in amounts of 19.9% ​​to 80% by weight. (b) 19.9% ​​to 80% by weight of at least one conjugated aliphatic diene and / or (meth)acrylic acid C1 to C2. 10 Alkyl esters (c) 0.1% to 10% by weight of at least one olefinic unsaturated acid, (d) 0% to 20% by weight of one or more olefinic unsaturated monomers different from those monomers (a), (b) and (c), These quantities are based on total monomers in each case.

8. The method according to any one of claims 1 to 7, wherein, The polymerized monomer composition consists of the following (a) 25% to 70% by weight of styrene and / or methylstyrene, (b) 25% to 70% by weight of at least one acrylic acid C1 to C 10 Alkyl esters (c) 1% to 10% by weight of at least one olefinic unsaturated acid, preferably selected from acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, vinyl acetic acid, vinyl lactic acid, vinyl sulfonic acid, styrene sulfonic acid, acrylamide methylpropanesulfonic acid, propyl acrylate, and propyl methacrylate. (d) 0% to 20% by weight of one or more olefinic unsaturated monomers different from those monomers (a), (b) and (c), These quantities are based on total monomers in each case.

9. The method according to any one of claims 1 to 8, wherein, Polymerization is carried out at temperatures ranging from ≥ 75°C to ≤ 115°C.

10. An aqueous polymer dispersion obtainable by free radical-initiated emulsion polymerization according to any one of claims 1 to 9.

11. Use of the aqueous polymer dispersion according to claim 10 as a binder, adhesive, sizing agent for fibers, for the production of coatings, or for the production of paper coating blends.

12. A paper coating compound having a solids content in the range of 50% to 85% by weight, the paper coating compound comprising (i) an inorganic pigment and (ii) an aqueous polymer dispersion according to claim 10, and optionally additional additives.

13. The paper coating compound according to the preceding claim, wherein, The polymer dispersion (solid) is used in an amount of 5% to 50% by weight based on the total amount of pigments, and wherein these pigments are present in an amount of 80% to 95% by weight based on the total solids content and are selected from the group consisting of: calcium sulfate, calcium aluminate sulfate, barium sulfate, magnesium carbonate, calcium carbonate, silica, aluminum oxide, aluminum hydroxide, silicates, titanium dioxide, zinc oxide, kaolin, alumina, talc, and silica, and wherein the paper coating compound additionally contains at least one additive selected from the group consisting of: thickeners, additional polymer binders, co-binders, optical brighteners, fillers, leveling aids, dispersants, surfactants, lubricants, neutralizers, defoamers, degassing agents, preservatives, and dyes.

14. A paper or board coated with a paper coating compound according to any one of the preceding two claims.

15. A method for coating paper or board, wherein, - Provides an aqueous polymer dispersion according to claim 10; and - Use this aqueous polymer dispersion, at least one pigment, and optional additional additives to produce paper coating formulations; as well as - and applying the paper coating compound to at least one surface of paper or board.

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