Aqueous polymer dispersion for hot air sealing of a paper packaging

Abstract

Described is an aqueous polymer dispersion obtained or obtainable from a first aqueous polymer dispersion A comprising an acid-free copolymer prepared in the presence of an acid-rich copolymer and a second aqueous polymer dispersion B comprising a polyurethane. The aqueous polymer dispersion can be used for hot air sealing of a paper packaging, wherein the paper packaging preferably is a folding box for food or a paper cup for hot or cold drinks.

Description

[0001] 240838W001

[0002] Aqueous polymer dispersion for hot air sealing of a paper packaging

[0003] Description

[0004] The invention relates to an aqueous polymer dispersion obtained or obtainable from a first aqueous polymer dispersion A comprising an acid-free copolymer prepared in the presence of an acid-rich copolymer, and a second aqueous polymer dispersion B comprising a polyurethane. The invention also relates to a method of making water-barrier coated paper packaging, to water-barrier coated paper packaging and to the use the aqueous polymer dispersion for hot air sealing of a paper packaging, wherein the paper packaging preferably is a folding box for food or a paper cup for hot or cold drinks.

[0005] In an effort to provide more sustainable packaging solutions, it is desirable to substitute plastic packaging by packaging based on renewable sources such as paper packaging. Packaging for food needs to have sufficient barrier properties such as low moisture vapor transition rates (MVTR) and low COBB values (low water absorptiveness). Barrier properties of paper packaging substrates can be achieved by suitable coating of paper packaging substrates.

[0006] WO 2017 / 210606 describes compositions and the process for producing styrene-acrylate dispersions for heat-seal- able water barrier paper coatings. Typical applications are folding boxes for food and paper cups for hot and cold drinks. Paper packaging coatings such as paper cup coatings do require a combination technical features such as water barrier, heat-sealability, low odor and recyclability. While traditionally (e.g. as described in WO 2017 / 210606) the heat-sealing step is performed with heated metal bars, which is currently the standard way of working in the market. It appeared that new high speed paper cup forming machines in the market are using different heat generating techniques namely by hot air. The styrene-acrylate dispersions as described in WO 2017 / 210606 are well suited for heated metal bar sealing, but they require very high temperatures for hot air sealing. These high temperatures lead to unwanted discoloration of the paper substrate. Therefore, it is an object of the invention to provide a coating composition for paper packaging materials with good water barrier effect, good heat-sealability by hot air at sufficiently low temperatures to minimize discoloration of the paper substrate, low odor and good recyclability.

[0007] It has now been found the use of aqueous polymer dispersions as described herein below provides the technical requirements mentioned above when used for barrier coating and hot sealing of paper packaging such as paper folding boxes or paper cups

[0008] The invention provides an aqueous polymer dispersion obtained or obtainable from a first aqueous polymer dispersion A and a second aqueous polymer dispersion B; wherein

[0009] (A) the first aqueous polymer dispersion A comprises

[0010] (A.1) an acid-rich styrene-acrylate copolymer made by free-radical polymerization of 240838W001

[0011] 2

[0012] (A.1 .a) from 40 to 80% by weight, preferably from 45 to 70% by weight, based on the total amount of monomers of copolymer (A.1 ), of at least one monomer selected from the group consisting of 01- to C12-alkyl (meth)acrylates; and

[0013] (A.1 ,b) from 15 to 40% by weight, preferably from 20 to 40% by weight, based on the total amount of monomers of copolymer (A.1), of styrene; and

[0014] (A.1 .c) from 5 to 20% by weight, preferably from 5 to 15% by weight, based on the total amount of monomers of copolymer (A.1), of at least one carboxylic acid functional monomer, preferably selected from the group consisting of acrylic acid and methacrylic acid; and

[0015] (A.1.d) optionally further monomers, different from monomers (A.1. a), (A.1 b) and (A.1.c); and

[0016] (A.2) an acid-free styrene-acrylate copolymer made by free-radical emulsion polymerization of

[0017] (A.2. a) from 40 to 85% by weight, preferably from 50 to 80% by weight, based on the total amount of monomers of copolymer (A.2), of at least one monomer selected from the group consisting of C1- to C12-alkyl (meth)acrylates; and

[0018] (A.2.b) from 15 to 50% by weight, preferably from 20 to 40% by weight, based on the total amount of monomers of copolymer (A.2), of styrene; and

[0019] (A.2.c) optionally further monomers, different from monomers (A.2. a), (A.2.b) and acid-functional monomers; and wherein the acid-free copolymer (A.2) is prepared in the presence of the acid-rich copolymer (A.1); and

[0020] (B) the second aqueous polymer dispersion B comprises at least one polyurethane.

[0021] The invention also provides a method of making water-barrier coated paper packaging wherein a) a paper or cardboard substrate is provided, and b) the paper or cardboard substrate is coated with the aqueous polymer dispersion as described herein below; wherein the paper packaging preferably is a folding box for food or a paper cup for hot or cold drinks.

[0022] The coated paper packaging can be hot air sealed after the coating step.

[0023] The invention also provides a paper packaging comprising a paper or cardboard substrate, wherein the paper or cardboard substrate is coated with the aqueous polymer dispersion as described herein below, wherein the COBB value of the paper packaging preferably is less than 20 g / m2 / 30 min, more preferably less than 15 g / m2 / 30 min, more preferably less than 13 g / m2 / 30 min, measured at 90°C according to ISO 535 and / or wherein the COBB value of the paper packaging preferably is less than 20 g / m2 / 30 min, preferably less than 15 g / m2 / 30 min, more preferably less than 12 g / m2 / 30 min, measured at 60°C according to ISO 535 and / or wherein the COBB value of the paper packaging preferably is less than 10 g / m2 / 30 min, more preferably less than 7 g / m2 / 30 min, measured at 20°C according to ISO 535; and wherein the paper packaging preferably is a folding box for food or a paper cup for hot or cold drinks. 240838W001

[0024] 3

[0025] The invention also provides the use of the aqueous polymer dispersion as described herein below for hot air sealing of a paper packaging, the paper packaging comprising a paper or cardboard substrate, wherein the paper or cardboard substrate is coated with the aqueous polymer dispersion as described herein below, and wherein the paper packaging preferably is a folding box for food or a paper cup, e.g. for hot or cold drinks.

[0026] The term "paper” as used herein includes paper and (card)board.

[0027] The text below occasionally uses the designation "(meth)acrylic” or "(meth)acrylate” and similar as an abbreviating notation for "acrylic or methacrylic” or "acrylate or methacrylate”. In the designation Cx-alkyl (meth)acrylate and analogous designations, x denotes the number of carbon atoms in the alkyl group.

[0028] The glass transition temperature is determined by differential scanning calorimetry (ASTM D 3418-08, so-called midpoint temperature). The glass transition temperature of the polymer in the polymer dispersion is the glass transition temperature obtained when evaluating the second heating curve (heating rate 20°C / min).

[0029] Acid number is measured according to DIN EN ISO 1241

[0030] The invention provides an aqueous polymer dispersion obtained or obtainable from a first aqueous polymer dispersion A and a second aqueous polymer dispersion B. The weight ratio of first aqueous polymer dispersion A to second aqueous polymer dispersion B is preferably from 40:60 to 80:20, more preferably from 55:45 to 80:20, more preferably from 55:45 to 70:30, based on the total weight of the aqueous dispersions.

[0031] The first aqueous polymer dispersion A comprises an acid-rich styrene-acrylate copolymer (A.1) made by free-radical polymerization and an acid-free styrene-acrylate copolymer (A.2), made by free-radical emulsion polymerization. The acid-free copolymer (A.2) is prepared in the presence of the acid-rich copolymer (A.1).

[0032] The acid-rich styrene-acrylate copolymer (A.1) is a high Tg polymer and has a glass transition temperature preferably from 50 to 130 °C. The glass transition temperature can be adjusted by using the appropriate types and amounts of monomers as is known by the person skilled in the art.

[0033] The acid-rich styrene-acrylate copolymer (A.1) has an acid number preferably from 50 to 250 mg KOH / g.

[0034] The acid-rich styrene-acrylate copolymer (A.1) can be prepared using emulsion polymerization in the presence of a free radical initiator, for example ammonium persulfate (APS) and an anionically charged surface active agent (surfactant), for example sodium lauryl sulfate. Alternatively, the acid-rich styrene-acrylate copolymer (A.1) can be prepared using free radical solution polymerization, isolated and dispersed into water. The acid-free styrene-acrylate copolymer (A.2) can be is prepared in the presence of the acid-rich styrene-acrylate copolymer (A.1), which provides colloidal stability to the polymer dispersion. 240838W001

[0035] 4

[0036] In some embodiments, the polymers of the first aqueous polymer dispersion A contain a shell and a core. The shell then contains the acid-rich styrene-acry lie copolymer, and the core contains the acid-free sty rene-acry lie copolymer. In some embodiments, the shell consists of the acid- rich styrene-acrylic copolymer, and the core consists of the acid-free styrene-acrylic copolymer.

[0037] Monomers (A.1. a)

[0038] The acid-rich styrene-acrylate copolymer (A.1) is made of from 40 to 80% by weight, preferably from 45 to 70% by weight, based on the total amount of monomers of copolymer (A.1), of at least one monomer (A.1. a) selected from the group consisting of C1- to C12-alkyl (meth)acrylates. Preferred monomers (A.1 .a) are C1- to C8-alkyl acrylates, C1- to C8-alky I methacrylates and mixtures of two or more thereof.

[0039] Preferred monomers (A.1. a) are one or multiple monomers selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-hexyl acrylate, cyclohexyl (meth)acrylate, 2-octyl acrylate, 2-ethylhexyl acrylate and 2- propylheptyl acrylate. In particular, mixtures of the (meth)acrylic acid alkyl esters are also suitable. Especially particularly preferred are methyl acrylate, methyl methacrylate, ethyl acrylate, n-butyl acrylate, n-butyl methacrylate, n-hexyl acrylate, 2-octyl acrylate and 2-ethylhexyl acrylate.

[0040] Monomers (A.1.b)

[0041] The acid-rich styrene-acrylate copolymer (A.1) is made of from 15 to 40% by weight, preferably from 20 to 40% by weight, based on the total amount of monomers of copolymer (A.1), of styrene.

[0042] Monomers (A.1.c)

[0043] The acid-rich styrene-acrylate copolymer (A.1) is made of from 5 to 20% by weight, preferably from 5 to 15% by weight, based on the total amount of monomers of copolymer (A.1), of at least one carboxylic acid functional monomer (A.1.c).

[0044] The monomers (A.1.c) with acid groups comprise not only monomers comprising at least one acid group but also anhydrides thereof and salts thereof. The monomers (A.1.c) include alpha, beta-monoethylenically unsaturated monocarboxylic and dicarboxylic acids, half-esters of alpha, beta-monoethylenically unsaturated dicarboxylic acids, the anhydrides of the abovementioned alpha, beta-monoethylenically unsaturated carboxylic acids. In addition, ethylenically unsaturated sulfonic acids, phosphonic acids or dihydrogenphosphates and water-soluble salts thereof, for example alkali metal salts thereof can be used. Examples of carboxylic acid-functional monomers (A.1 .c) are acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, vinylacetic acid and vinyllactic acid. Monomers (A.1 .c) with at least one carboxylic acid group are preferably selected from the group consisting of alpha, beta-monoethylenically unsaturated C3-C8-carboxylic acids and C4-C8-dicarboxylic acids, for example itaconic acid, crotonic acid, vinylacetic acid, aery lamidoglycolic acid, acrylic acid and methacrylic acid and also anhydrides 240838W001

[0045] 5 thereof. More preferred monomers (A.1.c) are acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, cratonic acid, vinylacetic acid, vi nyl lactic acid and mixtures of two or more of these monomers. Particularly preferred monomers (c) (A.1 .c) are itaconic acid, acrylic acid, methacrylic acid and mixtures of two or more thereof. Most preferred is acrylic acid, methacrylic acid and their mixture.

[0046] The acid groups of the monomer (A.1 .c) may be present in unneutralized form at the beginning of the polymerization and may be fully or partially neutralized by feeding of a base during or after the emulsion or solution polymerization, wherein for example the feeding of the base commences during the emulsion polymerization (i.e. after commencement of the polymerization reaction) once at least 5% by weight, preferably 10% to 70% by weight, of the total monomer mixture is present in the reaction vessel under polymerization conditions. The neutralizing agent may be added for example in a separate feed simultaneously with the feeding of the monomer mixture. After feeding of all of the monomers, the polymerization vessel preferably contains the amount of neutralizing agent required for neutralizing at least 10%, preferably 10% to 100% or 25% to 90%, of acid equivalents. Suitable bases are, for example, sodium hydroxide solution, potassium hydroxide solution, ammonia (preferably in aqueous solution) or organic amines, preferably tertiary amines, in particular trialkylamines preferably having 1 to 4 carbon atoms in the alkyl group, such as for example triethylamine.

[0047] Monomers (A.1.d)

[0048] The acid-rich styrene-acrylate copolymer (A.1) is optionally made of further monomers (A.1.d), different from monomers (A.1. a), (A.1b) and (A.1.c) in amounts of for example 0 to 10% by weight, or 0 to 5% by weight, or 0.1 to 10% by weight, or 0.1 to 5% by weight, or 0.5 to 10% by weight, or 0.5 to 5% by weight, based on the total amount of monomers of copolymer (A.1).

[0049] The monomers (A.1.d) are preferably selected from the group consisting of vinyl esters of carboxylic acids comprising up to 20 carbon atoms, vinylaromatics other than styrene having up to 20 carbon atoms, vinyl halides, vinyl ethers of alcohols comprising 1 to 10 carbon atoms, aliphatic hydrocarbons having 2 to 8 carbon atoms and one or two double bonds, acrylamide, methacrylamide, C1-C10 aminoalkyl(meth)acrylates, nitriles of alpha-, beta-monoeth- ylenically unsaturated C3-C8 carboxylic acids, bifunctional monomers which as well as an ethylenically unsaturated double bond have at least one group selected from the group consisting of glycidyl group, oxazoline group, ureido group and ureido-analogous group, crosslinking monomers which have more than one radically polymerizable group, more particularly two or more (meth)acrylate groups, ethylenically unsaturated monomers with at least one hydroxy group, and mixtures of two or more of these monomers.

[0050] Monomers with at least one hydroxy group include, for example, the hydroxyalkyl esters of the abovementioned alpha, beta-monoethylenically unsaturated carboxylic acids, preferably hydroxyalkyl (meth)acrylates with 1 to 10 carbon atoms in the alkyl group. The monomers with at least one hydroxy group are preferably selected from the group consisting of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, 4- hydroxybutyl acrylate, 4-hydroxybutyl methacrylate and mixtures of two or more thereof. 240838W001

[0051] 6

[0052] Vinyl esters of carboxylic acids having 1 to 20 carbon atoms are, for example, vinyl laurate, vinyl stearate, vinyl propionate, versatic acid vinyl esters, and vinyl acetate. Vinylaromatic compounds different from styrene include vinyltolu- ene, alpha- and para-methylstyrene, alpha-butylstyrene, 4-n-butylstyrene and 4-n-decylstyrene. The vinyl halides are ethylenically unsaturated compounds substituted by chlorine, fluorine or bromine, preferably vinyl chloride and vinylidene chloride. Examples of vinyl ethers include for example vinyl methyl ether or vinyl isobutyl ether. Vinyl ethers of alcohols comprising 1 to 4 carbon atoms are preferred. Hydrocarbons having 4 to 8 carbon atoms and two olefinic double bonds include butadiene, isoprene and chloroprene. Preferred monomers which have more than one free- radically polymerizable group are butanediol di(meth)acrylate or allyl methacrylate.

[0053] Examples of oxazoline group monomers are those of the formula: wherein the radicals are defined as follows:

[0054] R is a C2-2o-alkeny I radical comprising at least one ethy lenically unsaturated group;

[0055] R3, R4, R5and R6are independently of one another selected from the group consisting of H, halogen, and Ci.2o-alkyl, C2-2o-alkenyl, Ce-2o-aryl, Cz-32-arylalkyl, Ci-20-hydroxyalkyl, Ci-20-aminoalkyl and Ci-20-haloalkyl, preferably selected from the group consisting of H, halogen and Ci-20-alkyl. The oxazoline monomers are especially preferably at least one monomer selected from the group consisting of 2-viny l-2-oxazoli ne, 2-viny l-4-methy l-2-oxazoline, 2-vinyl-5-me- thyl-2-oxazoline, 2-vinyl-4-ethyl-2-oxazoline, 2-vinyl-4,4-dimethyl-2-oxazoline, 2-vinyl-5,5-dimethyl-2-oxazoline, 2- vinyl-4,4,5,5-teramethyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5- methyl-2-oxazoline, 2-isopropenyl-4-ethyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, 2-isopropenyl-4,4-dimethyl- 2-oxazoline, 2- isopropenyl-5,5-dimethyl-2-oxazoline and 2-isopropenyl-4,4,5,5-tetramethyl-2-oxazoline. The use of 2-vinyl-2-oxazoline and / or 2-isopropenyl-2-oxazoline is particularly preferred; 2-isopropenyl-2-oxazoline (IPOx) is especially preferred.

[0056] Examples of ureido group or ureido-analogous group monomers are, for example, those of the formula wherein X is CH2, 0, NH or NR1and R1is a C1- to C4-alkyl group, R is hydrogen or methyl, and A is a divalent linking group, preferably a C1- to C10-alkyl group or a C2- to C4-alkyl group. "Ureido-analogous” means monomers in 240838W001

[0057] 7 which X in the above structure is CH2 or 0 instead of NH or NR1. Particularly preferred are ureidoalkyl (meth)acry- lates having 1 to 10 carbon atoms, preferably 2 to 4 carbon atoms, in the alkyl group, in particular ureidoethyl methacrylate (UMA).

[0058] Acid-free styrene-acrylate copolymer A.2,

[0059] The acid-free styrene-acrylate copolymer (A.2) is a low Tg polymer and has a glass transition temperature preferably from -40 to +40 °C. The glass transition temperature can be adjusted by using the appropriate types and amounts of monomers as is known by the person skilled in the art. The acid-free styrene-acrylate copolymer (A.2) can be prepared using emulsion polymerization in the presence of a free radical initiator, for example ammonium persulfate (APS) and an anionically charged surface active agent (surfactant), for example sodium lauryl sulfate. The acid-free styrene-acrylate copolymer (A.2) can be is prepared in the presence of the acid-rich styrene-acrylate copolymer (A.1), which provides colloidal stability to the polymer dispersion.

[0060] Monomers (A.2. a)

[0061] The acid-free styrene-acrylate copolymer (A.2) is made of from 40 to 85% by weight, preferably from 50 to 80% by weight, based on the total amount of monomers of copolymer (A.2), of at least one monomer (A.2.a) selected from the group consisting of C1- to C12-alkyl (meth)acrylates. Preferred monomers (A.2. a) are C1- to C8-alkyl acrylates, C1- to C8-alkyl methacrylates and mixtures of two or more thereof. Suitable and preferred monomers (A.2. a) are the same as described above for monomer (A.1. a). Preferably, monomer (A.1. a) and monomer (A.2. a) are independently each at least one monomer selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-hexyl acrylate, cyclohexyl (meth)acrylate, 2-octyl acrylate, 2-ethylhexyl acrylate and 2-propylheptyl acrylate.

[0062] Monomers (A.2.b)

[0063] The acid-free styrene-acrylate copolymer (A.2) is made of from 15 to 50% by weight, preferably from 20 to 40% by weight, based on the total amount of monomers of copolymer (A.2), of styrene.

[0064] Monomers (A.2.c)

[0065] The acid-free styrene-acrylate copolymer (A.2) is optionally made of further monomers (A.2.c), different from monomers (A.2. a), (A.2.b) and acid-functional monomers in amounts of for example 0 to 10% by weight, or 0 to 5% by weight, or 0.1 to 10% by weight, or 0.1 to 5% by weight, or 0.5 to 10% by weight, or 0.5 to 5% by weight, based on the total amount of monomers of copolymer (A.2).

[0066] Suitable and preferred monomers (A.2.c) are the same as described above for monomer (A.1.d). Preferably, monomer (A.1.d) and monomer (A.2.c) are independently each at least one monomer selected from the group consisting of vinyl esters of carboxylic acids comprising up to 20 carbon atoms, vinylaromatics other than styrene having up to 20 carbon atoms, vinyl halides, vinyl ethers of alcohols comprising 1 to 10 carbon atoms, aliphatic hydrocarbons hav- 240838W001

[0067] 8 ing 2 to 8 carbon atoms and one or two double bonds, acrylamide, methacrylamide, C1-C10 aminoalkyl(meth)acry- lates, nitriles of alpha-, beta-monoethylenically unsaturated C3-C8 carboxylic acids, bifunctional monomers which as well as an ethylen ical ly unsaturated double bond have at least one group selected from the group consisting of glyc- idyl group, oxazoline group, ureido group and ureido-analogous group, crosslinking monomers which have more than one radically polymerizable group, more particularly two or more (meth)acrylate groups, and ethylenically unsaturated monomers with at least one hydroxy group preferably selected from the group consisting of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, 4-hydroxybutyl acrylate and 4- hydroxybutyl methacrylate.

[0068] In a preferred aqueous polymer dispersion the first aqueous polymer dispersion A comprises (A.1) an acid-rich styrene-acrylate copolymer made by free-radical polymerization of

[0069] (A.1. a) from 45 to 70% by weight, based on the total amount of monomers of copolymer (A.1), of at least one monomer selected from the group consisting of methyl (meth)acrylate, ethyl acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl acrylate, 2-octyl acrylate, 2-ethylhexyl acrylate and 2- propylheptyl acrylate; and

[0070] (A.1.b) from 20 to 40% by weight, based on the total amount of monomers of copolymer (A.1), of styrene; and (A.1 .c) from 5 to 15% by weight, based on the total amount of monomers of copolymer (A.1), of acrylic acid, methacrylic acid or their mixture; and

[0071] (A.2) an acid-free styrene-acrylate copolymer made by free-radical emulsion polymerization of

[0072] (A.2. a) from 50 to 80% by weight, based on the total amount of monomers of copolymer (A.2), of at least one monomer selected from the group consisting of methyl (meth)acrylate, ethyl acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl acrylate, 2-octyl acrylate, 2-ethylhexyl acrylate and 2- propylheptyl acrylate; and

[0073] (A.2.b) from 20 to 40% by weight, based on the total amount of monomers of copolymer (A.2), of styrene; wherein the acid-free copolymer (A.2) is prepared in the presence of the acid-rich copolymer (A.1), and wherein the amount of acid-rich copolymer (A.1) is from 10 to 40 wt.%, based on the total amount of polymers in the first polymer dispersion A; and the amount of acid-free copolymer (A.2) is from 60 to 90 wt.%, based on the total amount of polymers in the first polymer dispersion A; and wherein the weight ratio of first aqueous polymer dispersion A to second aqueous polymer dispersion B is from 40:60 to 80:20, preferably from 55:45 to 80:20, more preferably from 55:45 to 70:30, based on the total weight of the aqueous dispersions; and wherein the acid-rich styrene-acrylate copolymer (A.1) has a glass transition temperature from 50 to 130 °C and an acid number from 50 to 250 mg KOH / g; and wherein the acid-free styrene-acrylate copolymer has a glass transition temperature from -40 to +40 °C, the glass transition temperature is measured by differential scanning calorimetry according to ASTM D 3418-08 as the midpoint temperature when evaluating the second heating curve at a heating rate of 20°C / min; the acid number is measured according to DIN EN ISO 1241. 240838W001

[0074] 9

[0075] The amount of acid-rich styrene-acrylate copolymer (A.1) in the first polymer dispersion A is from 5 to 50 wt.%, preferably from 10 to 40 wt.%, based on the total amount of polymers in the first polymer dispersion A; and the amount of acid-free styrene-acrylate copolymer (A.2) in the first polymer dispersion A is from 50 to 95 wt.%, preferably from 60 to 90 wt.%, based on the total amount of polymers in the first polymer dispersion A. Preferably, the amount of acidrich styrene-acrylate copolymer (A.1) in the first polymer dispersion A is from 10 to 40 wt.%, based on the total amount of polymers in the first polymer dispersion A; and the amount of acid-free styrene-acrylate copolymer (A.2) in the first polymer dispersion A is from 60 to 90 wt.%, based on the total amount of polymers in the first polymer dispersion A.

[0076] The monomers of the polymerization for the acid-rich styrene-acrylate copolymer (A.1) and for the acid-free styrene- acrylate copolymer (A.2) are selected such that the measured glass transition temperature of the polymers are as described above. Through targeted variation of monomer type and quantity, those skilled in the art are able according to the invention to produce aqueous polymer compositions whose polymers have a glass transition temperature in the desired range. Orientation is possible using the Fox equation. According to Fox (T.G. Fox, Bull. Am. Phys. Soc. 1956 [Ser. II] 1, page 123 and according to Ullmann's Encyclopedia of Industrial Chemistry, vol. 19, page 18, 4th edition, Verlag Chemie, Weinheim, 1980), the glass transition temperature of copolymers is given to a good approximation by:

[0077] 1 / Tg = X1 / Tg1+ X2 / Tg2+ .... Xn / Tgn, wherein x1, x2, .... xnare the mass fractions of the monomers 1, 2, .... n and Tg1, Tg2, .... Tgnare the glass transition temperatures in degrees kelvin of the polymers constructed from only one of the monomers 1, 2, .... n at a time. The Tgvalues for the homopolymers of the majority of monomers are known and are listed for example in Ullmann's Encyclopedia of Industrial Chemistry, vol. 5, vol. A21, page 169, VCH Weinheim, 1992; further sources for glass transition temperatures of homopolymers are, for example, J. Brandrup, E.H. Immergut, Polymer Handbook, 1stEd., J. Wiley, New York 1966, 2ndEd. J. Wiley, New York 1975, and 3rdEd. J. Wiley, New York 1989.

[0078] In one embodiment of the invention the free-radical polymerization employs at least one chain transfer agent. This makes it possible to reduce the molar mass and the gel content of the emulsion polymer through a chain termination reaction. The chain transfer agents are bonded to the polymer in this procedure, generally to the chain end. The amount of the chain transfer agents can be for example 0.05 to 4 parts by weight, preferably 0.05 to 0.8 parts by weight and more preferably 0.1 to 0.6 parts by weight, based on 100 parts by weight of the monomers to be polymerized. Suitable chain transfer agents are, for example, compounds having a thiol group such as tert-butyl mercaptan, thioglycolic acid ethyl acryl ester, mercaptoethanol, mercaptopropyl trimethoxysilane or tert-dodecyl mercaptan. The chain transfer agents are generally compounds of low molecular mass, having a molar weight of less than 2000, in particular less than 1000 g / mol. Exemplary chain transfer agents include, but are not limited to, isooctyl mercapto- 240838W001

[0079] 10 propionate (IOMPA), butylmercaptopropionate, 2-ethyl hexylmercaptopropionate, tertiary dodecylmercaptan, and thioglycerol. Preferred are 2-ethylhexyl thioglycolate (EHTG), isooctyl 3-mercaptopropionate (IOMPA) and tert-dodecyl mercaptan (tDMK).

[0080] The emulsion polymerization comprises polymerizing ethylenically unsaturated compounds (monomers) in water using usually ionic and / or nonionic emulsifiers and / or protective colloids or stabilizers as surface-active compounds to stabilize the monomer droplets and the polymer particles subsequently formed from the monomers. Regarding emulsifiers, the surface-active substances are typically used in amounts of 0.1 to 10 parts by weight, preferably 0.2 to 5 parts by weight, based on 100 parts by weight of the monomers to be polymerized. Regarding protective colloids, the surface-active substances are typically used in amounts of 5 to 50 parts by weight, preferably 10 to 40 parts by weight, based on 100 parts by weight of the monomers to be polymerized.

[0081] In this invention, the acid-rich styrene-acrylate copolymer (A.1) can act as stabilizer during and after the polymerization of the of the acid-free styrene-acrylate copolymer (A.2)

[0082] A detailed description of suitable further protective colloids can be found in Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], volume XIV / 1, Makromolekulare Stoffe [Macromolecular Materials], Georg- Thieme-Verlag, Stuttgart, 1961 , p. 411 to 420. Useful emulsifiers include anionic, cationic and also nonionic emulsifiers. As surface-active substances it is preferable to employ emulsifiers whose molecular weight is typically below 2000 g / mol in contrast with the protective colloids. When mixtures of surface-active substances are used, the individual components must of course be compatible with one another; in case of doubt, this may be checked on the basis of a few preliminary experiments. Preference is given to using anionic and nonionic emulsifiers as surface-active substances. Customary accompanying emulsifiers are for example ethoxylated fatty alcohols (EC degree: 3 to 50, alkyl radical: Cs to C36), ethoxylated mono-, di- and trialkylphenols (EC degree: 3 to 50, alkyl radical: C4 to C9), alkali metal salts of dialkyl esters of sulfosuccinic acid and alkali metal and ammonium salts of alkyl sulfates (alkyl radical: Cs to C12), of ethoxylated alkanols (EC degree: 4 to 30, alkyl radical: C12 to G ), of ethoxylated alkylphenols (EC degree: 3 to 50, alkyl radical: C4 to C9), of alkylsulfonic acids (alkyl radical: C12 to G ) and of alkylarylsulfonic acids (alkyl radical: C9 to G ).

[0083] Further suitable emulsifiers are compounds of the general formula 240838W001

[0084] 11 wherein R5and R6are hydrogen or C4- to C14-alkyl and are not simultaneously hydrogen, and X and Y may be alkali metal ions and / or ammonium ions. R5and R6are preferably linear or branched alkyl radicals having 6 to 18 carbon atoms or hydrogen and in particular having 6, 12 and 16 carbon atoms, wherein R5and R6are not both simultaneously hydrogen. X and Y are preferably sodium, potassium or ammonium ions, wherein sodium is particularly preferred. Compounds in which X and Y are sodium, R5is a branched alkyl radical having 12 carbon atoms and R6is hydrogen or R5are particularly advantageous. Often employed are industrial mixtures comprising a proportion of 50% to 90% by weight of the monoalkylated product. Commercially available products of suitable emulsifiers are for example Dowfax® 2 A1 , Emulan® NP 50, Dextrol® OC 50, Emulgator 825, Emulgator 825 S, Emulan® OG, Texapon® NSC, Nekanil® 904 S, Lumiten® l-RA, Lumiten® E 3065, Disponil® FES 77, Lutensol® AT 18, Steinapol® VSL, Emulphor® NPS 25. Ionic emulsifiers or protective colloids are preferred for the present invention. Particular preference is given to ionic emulsifiers, in particular salts and acids, such as carboxylic acids, sulfonic acids and sulfates, sulfonates or carboxylates. Also employable in particular are mixtures of ionic and nonionic emulsifiers.

[0085] The emulsion polymerization may be initiated using water-soluble initiators. Water-soluble initiators are for example ammonium salts and alkali metal salts of peroxodisulfuric acid, for example sodium peroxodisulfate, hydrogen peroxide or organic peroxides, for example tert-butyl hydroperoxide. Also suitable as initiators are so-called reduction-oxidation (redox) initiator systems. Redox initiator systems consist of at least one generally inorganic reducing agent and an inorganic or organic oxidizing agent. The oxidant component is for example the emulsion polymerization initiators previously recited hereinabove. The reductant components are for example alkali metal salts of sulfurous acid, such as for example sodium sulfite, sodium hydrogensulfite, alkali metal salts of disulfurous acid such as sodium disulfite, bisulfite addition compounds of aliphatic aldehydes and ketones, such as acetone bisulfite or reducing agents such as hydroxymethanesulfinic acid and the salts thereof, or ascorbic acid. The redox initiator systems may be employed with co-use of soluble metal compounds whose metallic component may appear in a plurality of valence states. Typical redox initiator systems are, for example, ascorbic acid / iron(l I) sulfate / sodium peroxydisulfate, tert-bu- tyl hydroperoxide / sodium disulfite, tert-butyl hydroperoxide / sodium hydroxymethanesulfinic acid. The individual components, for example the reductant component, may also be mixtures, for example a mixture of the sodium salt of hydroxymethanesulfinic acid and sodium disulfite.

[0086] The recited initiators are generally employed in the form of aqueous solutions, the lower concentration limit being determined by the amount of water acceptable in the dispersion and the upper concentration limit being determined by the solubility in water of the particular compound. The concentration of the initiators is generally 0.1 % to 30% by weight, preferably 0.3% to 20% by weight, particularly preferably 0.5% to 10% by weight, based on the monomers to be polymerized. It is also possible to use two or more different initiators in the emulsion polymerization.

[0087] The emulsion polymerization is preferably carried out at 30°C to 130°C, preferably at 50°C to 90°C. The polymerization medium may consist either only of water or of mixtures of water and liquids miscible therewith such as methanol. 240838W001

[0088] 12

[0089] Preference is given to using solely water. The emulsion polymerization may be carried out in the form of a feed process, including staged or gradient process modes. In the polymerization a polymer seed may be initially charged for more effective adjustment of particle size.

[0090] The manner in which the initiator is added to the polymerization vessel over the course of the free-radical aqueous emulsion polymerization is known to those of ordinary skill in the art. It may be either initially charged to the polymerization vessel in its entirety or employed continuously or in a staged manner at the rate of its consumption over the course of the free-radical aqueous emulsion polymerization. This specifically depends on the chemical nature of the initiator system and on the polymerization temperature. Preference is given to initially charging a portion and supplying the remainder to the polymerization zone at the rate of its consumption. In order to remove the residual monomers, it is common after the end of the emulsion polymerization proper, i.e., after a monomer conversion of at least 95%, to add initiator as well. In the feed process, the individual components may be added to the reactor from above, from the side or from below through the reactor floor.

[0091] The emulsion polymerization generally affords aqueous dispersions of the polymer having solids contents of from 15% to 75% by weight, preferably from 40% to 60% by weight, particularly preferably not less than 50% by weight.

[0092] The polymer thus produced is preferably used in the form of its aqueous dispersion. The size distribution of the dispersion particles may be monomodal, bimodal or polymodal and is preferably monomodal.

[0093] The weight average particle diameter of the polymer particles of the first aqueous polymer dispersion A preferably is from 70 to 150 nm.

[0094] Average particle diameters XPCS and particle size distribution can be measured by photon correlation spectroscopy (ISO standard 13321 :1996). The size distribution of the dispersion particles is monomodal when measurement of the particle size distribution contains only one single maximum.

[0095] The second aqueous polymer dispersion B comprises at least one polyurethane.

[0096] Suitable polyurethane dispersions are in principle obtainable by reaction of at least one polyisocyanate with at least one compound having at least two isocyanate-reactive groups and dispersion in water. Suitable polyurethanes also include so-called polyurethane-polyureas comprising not only polyurethane groups but also urea groups. The polyurethane dispersion preferably comprises at least one polyurethane which comprises at least one polyisocyanate and at least one polymeric polyol in copolymerized form. The polyurethane may in particular be formed from at least one polyisocyanate and at least one polymeric polyol. Suitable polymeric polyols are preferably selected from the group consisting of polyester diols, polyether diols, polycarbonate diols and mixtures of two or more thereof. The polymeric polyol preferably has a number-average molecular weight in the range from about 500 to 5000 g / mol. The molecular weight of the polymeric polyols can be determined from their OH-number which can be measured according to DIN 53 240. Polymeric diols are preferred. The polyurethane dispersion preferably comprises at least one polyurethane which comprises at least one polyisocyanate and a diol component in copolymerized form, of which a) 10-100 mol% 240838W001

[0097] 13 based on the total amount of the diols have a molecular weight of 500 to 5000 g / mol and b) 0-90 mol% based on the total amount of the diols have a molecular weight of 60 to 500 g / mol.

[0098] The polyurethane is preferably constructed to an extent of at least 40% by weight, particularly preferably to an extent of at least 60% by weight and very particularly preferably to an extent of at least 80% by weight, based on the total weight of the monomers used for producing the polyurethane, from at least one diisocyanate and at least one polyether diol and / or at least one polyester diol. Suitable further synthesis components to 100% by weight include for example the polyisocyanates recited below having at least three NCO groups and compounds distinct from the polymeric polyols having at least two isocyanate-reactive groups. These include for example diols; diamines; polymers distinct from polymeric polyols having at least two active hydrogen atoms per molecule; compounds having two active hydrogen atoms and at least one ionogenic / ionic group per molecule; and mixtures of two or more thereof.

[0099] Preferred polyurethanes are constructed from: a) at least one monomeric diisocyanate, b) at least one diol, of which b1) 10 to 100 mol%, based on the total amount of the diols (b), have a molecular weight of 500 to 5000 g / mol and b2) 0 to 90 mol%, based on the total amount of the diols (b), have a molecular weight of 60 to 500 g / mol, c) at least one monomer distinct from the monomers (a) and (b) having at least one isocyanate group or at least one isocyanate-reactive group which further bears at least one hydrophilic group or a potentially hydrophilic group, d) optionally at least one further compound distinct from the monomers (a) to (c) having at least two reactive groups selected from the group consisting of alcoholic hydroxyl groups, primary or secondary amino groups or isocyanate groups, and e) optionally at least one monofunctional compound distinct from the monomers (a) to (d) having a reactive group which is an alcoholic hydroxyl group, a primary or secondary amino group or an isocyanate group.

[0100] It is particularly preferable when the ratio of the diols bi) to the diols b2) is 0.1 :1 to 5: 1 , particularly preferably 0.2:1 to 2:1. The diol b) is in particular selected from the group consisting of polytetrahydrofuran, polypropylene oxide, polyesterdiols selected from reaction products of dihydric alcohols with dibasic carboxylic acids, and lactone-based polyesterdiols.

[0101] Compounds suitable as monomers (a) include in particular diisocyanates X(NCO)2, wherein X is an acyclic aliphatic hydrocarbon radical having 4 to 15 carbon atoms, a cycloaliphatic or aromatic hydrocarbon radical having 6 to 15 carbon atoms or an araliphatic hydrocarbon radical having 7 to 15 carbon atoms.

[0102] Examples of such diisocyanates are tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, 1 ,4-diisocyanatocyclohexane, 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethylcyclohexane (IPDI), 2,2-bis(4-isocyanatocyclohexyl)propane, trimethylhexane diisocyanate, 1,4-diisocyanatobenzene, 2,4-diisocyanato- toluene, 2,6-diisocyanatotoluene, 4,4'-diisocyanatodiphenylmethane, 2,4'-diisocyanatodiphenylmethane, p-xylylene 240838W001

[0103] 14 diisocyanate, tetramethylxylylene diisocyanate (TMXDI), the isomers of bis(4-isocyanatocyclohexyl)methane (HMDI), such as the trans / trans, the cis / cis and the cis / trans isomers, and mixtures composed of these compounds.

[0104] Such diisocyanates are commercially available. Mixtures of these isocyanates of particular importance are the mixtures of the respective structural isomers of diisocyanatotoluene and diisocyanatodiphenylmethane, the mixture of 80 mol% of 2,4-diisocyanatotoluene and 20 mol% of 2,6-diisocyanatotoluene being particularly suitable and preferred. In addition, the mixtures of aromatic isocyanates such as 2,4-diisocyanatotoluene and / or 2,6-diisocyanatotoluene with aliphatic or cycloaliphatic isocyanates, such as hexamethylene diisocyanate or IPDI, are particularly advantageous, the preferred quantitative ratio of the aliphatic isocyanates to aromatic isocyanates being 1 :9 to 9:1 , in particular 4: 1 to 1 :4.

[0105] Preferred diisocyanates (a) are selected from the group consisting of hexamethylene diisocyanate, 5-isocyanato-1- (isocyanatomethyl)-l , 3,3-trimethy Icy clohexane, 2,6-diisocyanatotoluene, 2,4-diisocyanatotoluene, tetramethylxylylene diisocyanate, oligocarbodiimide-diisocyanate based on meta-tetramethylxylylendiisocyanate, 4,4-methylene dicyclohexyl diisocyanate and a mixture of two or more thereof.

[0106] The diols (b1) may be polyester polyols and these are known for example from Ullmann's Encyclopedia of Industrial Chemistry, 4th edition, volume 19, pp. 62 to 65. Preference is given to using polyester polyols obtained by reaction of dihydric alcohols with dibasic carboxylic acids. Instead of using the free polycarboxylic acids, the polyester polyols may also be produced using the corresponding polycarboxylic anhydrides or corresponding polycarboxylic esters of lower alcohols or mixtures of two or more thereof. The polycarboxylic acids may be aliphatic, cycloaliphatic, araliphatic, aromatic or heterocyclic and may optionally be substituted, for example by halogen atoms, and / or unsaturated. Examples thereof include: suberic acid, azelaic acid, phthalic acid, isophthalic acid, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrachlorophthalic anhydride, endomethylene tetrahydrophthalic anhydride, glutaric anhydride, maleic acid, maleic anhydride, fumaric acid, dimeric fatty acids. Preference is given to dicarboxylic acids of the general formula HOOC-(CH2)y-COOH, wherein y is a number from 1 to 20, preferably an even number from 2 to 20, for example succinic acid, adipic acid, sebacic acid and dodecane dicarboxylic acid. Suitable dihydric alcohols are, for example, ethylene glycol, propane-1 , 2-diol, propane-1 , 3-diol, butane-1 ,3-diol, butene-1 ,4-diol, butyne- 1 ,4-diol, pentane-1 ,5-diol, neopentyl glycol, bis(hydroxymethyl)cyclohexanes such as 1,4-bis(hydroxymethyl)cyclohex- ane, 2-methylpropane-1 , 3-diol, methylpentanediols, furthermore diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, dibutylene glycol and polybutylene glycols. Preferred alcohols are those of the general formula HO-(CH2)X-OH, wherein x is a number from 1 to 20, preferably an even number from 2 to 20. Examples thereof are ethylene glycol, butane-1 ,4-diol, hexane-1 ,6-diol, octane-1 ,8-diol and do- decane-1 ,12-diol. Neopentyl glycol is also preferred.

[0107] The diols (b1) may also be polycarbonate diols such as are obtainable for example by reaction of phosgene with an excess of the low molecular weight alcohols recited as synthesis components for the polyester polyols. 240838W001

[0108] 15

[0109] The diols (b1) may also be lactone-based polyester diols, specifically homopolymers or copolymers of lactones, preferably terminal hydroxyl-comprising addition products of lactones onto suitable difunctional starter molecules. Contemplated lactones preferably include those derived from compounds of the general formula HO-(CH2)Z-COOH, wherein z is a number from 1 to 20 and one hydrogen atom of a methylene unit may also be substituted by a Ci- to C4-alkyl radical. Examples include epsilon-caprolactone, beta-propiolactone, gamma-butyrolactone and / or methyl-gamma-ca- prolactone and mixtures of two or more thereof. Suitable starter components are, for example, the low-molecular weight-dihydric alcohols recited hereinabove as synthesis components for the polyester polyols. The corresponding polymers of epsilon-caprolactone are particularly preferred. Lower polyester diols or polyether diols may also be employed as starters for producing the lactone polymers. Instead of the polymers of lactones, the corresponding, chemically equivalent polycondensates of the hydroxycarboxylic acids corresponding to the lactones may also be employed.

[0110] The diols (b1) may also be polyether diols. Polyether diols are obtainable in particular by homopolymerization of ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, styrene oxide or epichlorohydrin, for example in the presence of BF3, or by addition of these compounds optionally in admixture or in succession onto starting components having reactive hydrogen atoms, such as alcohols or amines, for example water, ethylene glycol, propane-1 , 2- diol, propane-1 ,3-diol, 2,2-bis(4-hydroxyphenyl)propane or aniline. Polyether diols having a molecular weight of 500 to 5000 and especially 600 to 4500 are particularly preferred. Particularly preferred polyether diols are polypropylene oxide and polytetrahydrofuran. Suitable polytetrahydrofurans may be produced by cationic polymerization of tetrahydrofuran in the presence of acidic catalysts, such as for example sulfuric acid or fluorosulfuric acid. Such methods of production are known to those skilled in the art. Suitable compounds b1) further include alpha, omega-diaminopoly- ethers producible by amination of polyalkylene oxides with ammonia. bi) only includes polyether diols formed to an extent of less than 20% by weight, based on their total weight, of ethylene oxide. Polyether diols comprising at least 20% by weight of incorporated ethylene oxide units are hydrophilic polyether diols that are included among the monomers c).

[0111] Optionally co-usable as monomers bi) are also polyhydroxyolefins, preferably those having 2 terminal hydroxyl groups, for example alpha-omega-dihydroxypolybutadiene, alpha-omega-dihydroxypolymethacrylate esters or alpha- omega-dihydroxypolyacrylate esters as monomers. Such compounds are disclosed in EP-A 622 378 for example. Further suitable polyols are polyacetals, polysiloxanes and alkyd resins.

[0112] It is preferable that at least 95 mol% of the diols bi) are polyether diols, in particular polypropylene glycol.

[0113] The hardness and the modulus of elasticity of the polyurethanes can be increased when as diols (b) not only the diols bi) but also low-molecular-weight diols 62) having a molecular weight of about 60 to 500, preferably of 62 to 200 g / ml, are employed. Employed monomers 62) especially include the synthesis components of the short-chain alkanediols recited for the production of polyester polyols, wherein the unbranched diols having 2 to 12 carbon atoms and an even number of carbon atoms and also pentane-1 ,5-diol and neopentyl glycol are preferred. Contemplated 240838W001

[0114] 16 diols b2) include for example ethylene glycol, propane-1 , 2-diol, propane-1 , 3-diol, butane-1 ,3-diol, butene-1 ,4-diol, butyne-1 ,4-diol, pentane-1 ,5-diol, neopentyl glycol, bis(hydroxymethyl)cyclohexanes such as 1,4-bis(hydroxyme- thyl)cyclohexane, 2-methylpropane-1 , 3-diol, methylpentanediols, furthermore diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, dibutylene glycol and polybutylene glycols. Preferred alcohols are those of the general formula HO-(CH2)X-OH, wherein x is a number from 1 to 20, preferably an even number from 2 to 20. Examples thereof are ethylene glycol, butane-1 , 4-diol, hexane-1 ,6-diol, octane- 1 ,8-diol and dodecane-1 ,12-diol. Neopentyl glycol is also preferred.

[0115] Preferred diols b1) are at least one diol selected from the group consisting of polyester diols, polycarbonate diols and polyether diols, more preferably at least one diol selected from the group consisting of polyester diols and polyether diols.

[0116] In order to ensure that the polyurethanes are water-dispersible, the polyurethanes comprise as a synthesis component monomers (c) which are distinct from the components (a) and (b) and bear at least one isocyanate group or at least one isocyanate-reactive group and moreover bear at least one hydrophilic group or a group which can be converted into a hydrophilic group. Hereinbelow, the term "hydrophilic groups or potentially hydrophilic groups" is abbreviated to "(potentially) hydrophilic groups". The (potentially) hydrophilic groups react with isocyanates substantially more slowly than the functional groups of the monomers used to construct the polymer main chain. The proportion of components comprising (potentially) hydrophilic groups in the total amount of components (a) to (f) is generally measured such that the molar amount of the (potentially) hydrophilic groups (preferably anionic or potentially anionic groups) based on the amount by weight of all monomers (a) to (e) is 30 to 1000, preferably 50 to 500 and particularly preferably 80 to 300 mmol / kg. The (potentially) hydrophilic groups may be nonionic or preferably (potentially) ionic hydrophilic groups.

[0117] Contemplated nonionic hydrophilic groups include in particular polyethylene glycol ethers composed of preferably 5 to 100, preferably 10 to 80, ethylene oxide repeating units. The content of polyethylene oxide units is generally 0% to 10% by weight, preferably 0% to 6% by weight, based on the amount by weight of all monomers (a) to (e). Preferred monomers comprising nonionic hydrophilic groups are polyethylene oxide diols comprising at least 20% by weight of ethylene oxide, polyethylene oxide monools and the reaction products of a polyethylene glycol and a diisocyanate which bear a terminally etherified polyethylene glycol radical. Such diisocyanates and processes for their production are recited in patent documents US-A 3,905,929 and US-A 3,920,598.

[0118] Ionic hydrophilic groups are especially anionic groups, such as the sulfonate, carboxylate and the phosphate group in the form of their alkali metal or ammonium salts, and cationic groups, such as ammonium groups, in particular protonated tertiary amino groups or quaternary ammonium groups. Potentially ionic hydrophilic groups are especially those which may be converted into the abovementioned ionic hydrophilic groups by simple neutralization, hydrolysis 240838W001

[0119] 17 or quaternization reactions, i.e. carboxylic acid groups or tertiary amino groups for example. (Potentially) ionic monomers (c) are described in detail for example in Ullmann's Encyclopedia of Industrial Chemistry, 4th edition, volume 19, pp. 311-313 and for example in DE-A 1 495 745.

[0120] (Potentially) cationic monomers (c) of particular practical importance are especially monomers comprising tertiary amino groups, for example: tris(hydroxyalkyl)amines, N,N'-bis(hydroxyalkyl)alkylamines, N-hydroxyalkyl dialkylamines, tris(aminoalkyl)amines, N, N'-bis(aminoalkyl)alkylamines, N-aminoalkyl dialkylamines, wherein the alkyl radicals and alkanediyl units of these tertiary amines are independently of one another composed of 1 to 6 carbon atoms. Also contemplated are polyethers comprising tertiary nitrogen atoms and preferably two terminal hydroxyl groups, such as are obtainable in a manner customary per se for example by alkoxylation of amines comprising two hydrogen atoms attached to amine nitrogen, for example methylamine, aniline or N,N'-dimethylhydrazine. Such polyethers generally have a molar weight of between 500 and 6000 g / mol. These tertiary amines are converted into the ammonium salts either with acids, preferably strong mineral acids such as phosphoric acid, sulfuric acid, hydrohalic acids, or strong organic acids or by conversion with suitable quaternization agents such as Ci- to Ce-alky I halides or benzyl halides, for example bromides or chlorides.

[0121] Contemplated monomers comprising (potentially) anionic groups typically include aliphatic, cycloaliphatic, araliphatic or aromatic carboxylic acids and sulfonic acids bearing at least one alcoholic hydroxyl group or at least one primary or secondary amino group. Preference is given to dihydroxyalkylcarboxylic acids, especially comprising 3 to 10 carbon atoms, as also described in US 3,412,054. Preferred compounds include in particular compounds of the general formula (ci) in which R1and R2represent a Ci- to C4-alkanediyl (unit) and R3represents a Ci- to C4-alkyl (unit), especially dimethylolpropionic acid (DMPA). Corresponding dihydroxysulfonic acids and dihydroxyphosphonic acids such as 2,3- dihydroxypropanephosphonic acid are also suitable. Also suitable are dihydroxy compounds having a molecular weight of more than 500 to 10 000 g / mol and comprising at least 2 carboxylate groups, as disclosed in DE-A 39 11 827. These are obtainable by reacting dihydroxy compounds with tetracarboxylic dianhydrides, such as pyromellitic dianhydride or cyclopentanetetracarboxylic dianhydride in a molar ratio of 2: 1 to 1.05: 1 in a polyaddition reaction. Suitable dihydroxy compounds are in particular the monomers (b2) cited as chain extenders and the diols (b1).

[0122] Contemplated monomers (c) comprising isocyanate-reactive amino groups also include aminocarboxylic acids such as lysine, beta-alanine or the adducts, cited in DE-A 20 34 479, of aliphatic diprimary diamines onto alpha, beta-un- saturated carboxylic or sulfonic acids. Such compounds for example conform to the formula (C2) 240838W001

[0123] 18

[0124] H2N-R4-NH-R5-X (C2) in which R4and R5independently of one another represent a Ci- to Ce-alkanediy I unit, preferably ethylene; and X represents COOH or SO3H. Particularly preferred compounds of formula (c2) are N-(2-aminoethyl)-2-aminoethane- carboxylic acid and N-(2-aminoethyl)-2-aminoethanesulfonic acid and the corresponding alkali metal salts, wherein sodium is a particularly preferred counterion. Also particularly preferred are the adducts of the abovementioned aliphatic diprimary diamines onto 2-acrylamido-2-methylpropanesulfonic acid, as described for example in DE-B 1 954 090.

[0125] Where monomers containing potentially ionic groups are employed, their conversion into the ionic form may take place before, during, but preferably after the isocyanate polyaddition, since the solubility of the ionic monomers in the reaction mixture is frequently no more than poor. Neutralizing agents are for example ammonia, NaOH, triethanolamine (TEA), triisopropylamine (TIPA) or morpholine, and derivatives thereof. The sulfonate or carboxylate groups are especially preferably present in the form of their salts with an alkali metal ion or with an ammonium ion as the counterion.

[0126] Preferred compound c) is at least one compound selected from the group consisting of dihydroxycarboxylic acids, diaminocarboxylic acids and diaminosulfonic acids, more preferably at least one compound selected from the group consisting of dihydroxycarboxylic acids and diaminocarboxylic acids.

[0127] The monomers (d) which are distinct from the monomers (a) to (c), and which are optionally also constituents of the polyurethane are generally used for crosslinking or chain extension. They are generally more than dihydric nonphenolic alcohols, amines comprising 2 or more primary and / or secondary amino groups and compounds bearing one or more primary and / or secondary amino groups in addition to one or more alcoholic hydroxyl groups. Alcohols having a hydricity greater than 2 and which may be used to establish a certain degree of branching or crosslinking are, for example, trimethylolpropane, glycerol and sugar.

[0128] Also contemplated are monoalcohols which carry not only the hydroxyl group but also a further isocyanate-reactive group such as monoalcohols having one or more primary and / or secondary amino groups, for example monoethanolamine. Polyamines having 2 or more primary and / or secondary amino groups are primarily used when the chain extension and / or crosslinking is to take place in the presence of water since amines generally react with isocyanates more rapidly than alcohols or water. This is often necessary when aqueous dispersions of crosslinked polyurethanes or polyurethanes of high molecular weight are desired. The procedure in such cases comprises producing prepolymers comprising isocyanate groups, rapidly dispersing said prepolymers in water and subsequently chain-extending or crosslinking said prepolymers by adding compounds comprising a plurality of isocyanate-reactive amino groups.

[0129] Amines suitable for this purpose are generally polyfunctional amines in the molecular weight range from 32 to 500 g / mol, preferably from 60 to 300 g / mol, which comprise at least two amino groups selected from the group consisting 240838W001

[0130] 19 of the primary and secondary amino groups. Examples thereof are diamines such as diaminoethane, diaminopropanes, diaminobutanes, diaminohexanes, piperazine, 2,5-dimethylpiperazine, amino-3-aminomethyl-3,5,5-trimethyl- cyclohexane (isophoronediamine, IPDA), 4,4'-diaminodicyclohexylmethane, 1,4-diaminocyclohexane, aminoethyl ethanolamine, hydrazine, hydrazine hydrate or triamines such as diethylenetriamine or 1,8-diamino-4-ami- nomethyloctane. The amines may also be employed in blocked form, for example in the form of the corresponding ketimines (see, for example, CA-A 1 129 128), ketazines (cf. , for example, US-A 4,269,748) or amine salts (see US- A 4,292,226). Oxazolidines, as are used, for example, in US-A 4,192,937, also represent capped polyamines which can be used for producing the polyurethanes according to the invention for chain extension of the prepolymers. Use of such capped polyamines generally comprises mixing said polyamines with the prepolymers in the absence of water and subsequently mixing this mixture with the dispersion water or a portion of the dispersion water, thus releasing the corresponding polyamines hydrolytically. It is preferable to use mixtures of di- and triamines, particularly preferably mixtures of isophorone diamine (IPDA) and diethylene triamine (DETA).

[0131] The polyurethanes preferably comprise 1 to 30 mol%, particularly preferably 4 to 25 mol%, based on the total amount of the components (b) and (d) of a polyamine comprising at least 2 isocyanate-reactive amino groups as monomers (d). Higher than difunctional isocyanates may also be used as monomers (d) for the same purpose. Commercially available compounds are, for example, the isocyanurate or the biuret of hexamethylene diisocyanate.

[0132] Monomers (e) that are optionally co-used are monoisocyanates, monoalcohols and monoprimary and -secondary amines. The proportion thereof is generally not more than 10 mol%, based on the total molar amount of the monomers. These monofunctional compounds typically bear further functional groups such as olefinic groups or carbonyl groups and serve to introduce functional groups into the polyurethane which make the dispersal or crosslinking or further polymer-analogous reaction of the polyurethane possible. Contemplated therefor are monomers such as iso- propenyl-a,a'-dimethylbenzyl isocyanate (TMI) and esters of acrylic or methacrylic acid such as hydroxyethyl acrylate or hydroxyethyl methacrylate.

[0133] Preferred are polyurethanes, wherein the at least one diisocyanate a) is at least one diisocyanate selected from diisocyanates of the formula X(NCO)2, wherein X represents an acyclic aliphatic hydrocarbon radical having 4 to 15 carbon atoms, a cycloaliphatic hydrocarbon radical having 6 to 15 carbon atoms, an aromatic hydrocarbon radical having 6 to 15 carbon atoms or an araliphatic hydrocarbon radical having 7 to 15 carbon atoms, preferably selected from the group consisting of hexamethylene diisocyanate, 5-isocyanato-1-(isocyanatomethyl)-1 ,3,3-trimethylcyclo- hexane, 2,6-diisocyanatotoluene, 2,4-diisocyanatotoluene and tetramethylxylylene diisocyanate and a mixture of two or more thereof; the diols b1) are selected from the group consisting of polyester diols, polycarbonate diols, polyether diols ans mixtures of two or more thereof; and the compound c) is selected from the group consisting of dihydroxycarboxylic acids, diaminocarboxylic acids, diaminosulfonic acids, and mixtures of two or more thereof. 240838W001

[0134] 20

[0135] The way in which the molecular weight of the polyurethanes may be adjusted through choice of the proportions of the mutually reactive monomers and of the arithmetic mean of the number of reactive functional groups per molecule is common general knowledge in the field of polyurethane chemistry. The components (a) to (e) and their respective molar amounts are normally chosen such that the ratio A : B where A is the molar amount of isocyanate groups and

[0136] B is the sum of the molar amount of hydroxyl groups and the molar amount of functional groups which are capable of reacting with isocyanates in an addition reaction, is 0.5:1 to 2:1, preferably 0.8:1 to 1.5:1, particularly preferably 0.9:1 to 1.2:1. It is very particularly preferable when the ratio A: B is very close to 1 : 1 .

[0137] The monomers (a) to (e) employed bear on average typically from 1 .5 to 2.5, preferably from 1 .9 to 2.1 and particularly preferably 2.0 isocyanate groups or functional groups capable of reacting with isocyanates in an addition reaction.

[0138] The polyurethane preferably has a glass transition temperature of minus 60 °C to minus 10 °C, more preferably from -50 to -10 °C, more preferably from -50 to -40°C„ measured by differential scanning calorimetry according to ASTM D 3418-08 as the midpoint temperature when evaluating the second heating curve at a heating rate of 20°C / min.

[0139] The polyaddition of the components (a) to (e) to produce the polyurethane is preferably carried out at reaction temperatures of up to 180°C, preferably up to 150°C, under standard pressure or under autogenous pressure. The production of polyurethanes and of aqueous polyurethane dispersions is known to those skilled in the art.

[0140] In the context of the present invention an aqueous polyurethane dispersion is to be understood as meaning a dispersion which has an aqueous solvent as the continuous phase. Suitable aqueous solvents are water and mixtures of water with water-miscible solvents, for example alcohols, such as methanol, ethanol, n-propanol, isopropanol, n-bu- tanol, sec-butanol, tert-butanol, n-hexanol and cyclohexanol; glycols, such as ethylene glycol, propylene glycol and butylene glycol; the methyl or ethyl ethers of dihydric alcohols, diethylene glycol, triethylene glycol, polyethylene glycols having number-average molecular weights up to about 3000, glycerol and dioxane, and ketones, such as acetone in particular. In one specific embodiment the polyurethane dispersion is substantially free from organic solvents. "Substantially free from organic solvents” is to be understood as meaning that the proportion of organic solvents is not more than 5% by weight, particularly preferably not more than 1% by weight, in particular not more than 0.1% by weight, based on the total weight of the solvent.

[0141] In a preferred embodiment the production of the polyurethanes is carried out in the presence of at least one organic solvent. Preferred organic solvents for production of the polyurethanes are ketones, such as acetone and methyl ethyl ketone, and N-methylpyrrolidone. Particular preference is given to using acetone. If an at least partially water- miscible solvent is used to produce the polyurethanes, the polyurethane dispersion according to the invention may contain not only water but also the organic solvent used for production. It will be appreciated that the production of 240838W001

[0142] 21 the polyurethane dispersions according to the invention may be carried out in the presence of at least one organic solvent, with said solvent subsequently being partially or completely replaced with water to produce the aqueous polyurethane dispersion.

[0143] The pH of the aqueous polymer dispersion, is preferably adjusted to a pH greater than 5, in particular to a pH between 5.5 and 8.

[0144] The aqueous polymer dispersions may be employed as such or after formulating with customary further auxiliaries (additives). Typical auxiliaries are, for example, defoamers, preservatives, UV stabilizers, catalysts, drying agents, antistatic agents, flame retardants, thickeners (preferably associative thickeners), thixotropic agents, surface-active agents, viscosity modifiers, plasticizers, levelling agents, tackifiers, wetting agents or chelating agents. For better wetting of surfaces the polymer dispersions may include in particular wetting agents, for example fatty alcohol ethoxylates, alkylphenol ethoxylates, nonylphenol ethoxylates or sodium dodecyl sulfonates. The amount of further auxiliaries is preferably 0.05% to 5% by weight, especially 0.25% to 3% by weight, based on the total weight of the aqueous polymer dispersion.

[0145] For sustainability reasons it is preferred to use bio-based materials for producing the polymer of the first polymer dispersion and / or the polymer of the second polymer dispersion. The term "bio-based” indicates that the material is of biological origin and comes from a biomaterial / renewable resource. A material of renewable origin or biomaterial is an organic material wherein the carbon comes from the CO2 fixed recently (on a human scale) by photosynthesis from the atmosphere. A biomaterial (carbon of 100% natural origin) has an isotopic ratio14C / 12C greater than 10-12, typically about 1.2x10-12, while a fossil material has a zero ratio. Indeed, the isotopic14C is formed in the atmosphere and is then integrated via photosynthesis, according to a time scale of a few tens of years at most. The half-life of the14C is 5,730 years. Thus, the materials coming from photosynthesis, namely plants in general, necessarily have a maximum content in isotope14C. The determination of the content of biomaterial or of bio-carbon can be carried out in accordance with the standards ASTM D 6866-12, the method B (ASTM D 6866-06) and ASTM D 7026 (ASTM D 7026-04). The polymers of the first component of the two-component lamination adhesive preferably consists to an extent of at least 5 weight%, more preferably at least 10 weight% of bio-based materials, based on the sum total of all polymers of the first and second polymer dispersions.

[0146] Suitable bio-based materials for producing the first polymer by emulsion polymerization are for example (meth)acrylic esters, wherein the (meth)acrylic acid component or the alcohol component or both are bio-based. Various methods of producing bio-based acrylic acid from renewable plant materials are mentioned in EP 2626397 A1. Suitable biobased alcohols are for example bio-based iso-butanol, bio-based n-butanol, bio-based ethanol, bio-based iso-penta- nol (3-methylbutan-1-ol), bio-based 2-octanol, bio-based 1 -octanol and bio-based n-heptanol. Preferred partly biobased monomers are esters of (meth)acry lie acid and bio-based alcohols, preferably bio-based 2-octanol, bio-based 1 -octanol, bio-based ethanol, bio-based iso-butanol, bio-based n-butanol, bio-based iso-pentanol (3-methylbutan-1- ol), bio-based and bio-based n-heptanol. Preferred fully biobased monomers are esters of bio-based acrylic acid and 240838W001

[0147] 22 bio-based alcohols as mentioned above. Preferably at least the carbon atoms of the alkyl group of at least one of the monomers 2-octyl acrylate, 1 -octyl acrylate, isobutyl acrylate and ethyl acrylate is of biological origin. Preferably, at least 50 wt.%, more preferred 100 wt.% of 2-octyl acrylate monomer is made from bio-based 2-octanol and non-bio- based or bio-based acrylic acid, i.e. preferably at least the carbon atoms of the 2-octyl group of 2-octyl acrylate are of biological origin. Preferably, monomers comprise iso butyl acrylate wherein at least the carbon atoms of the iso butyl group are of biological origin.

[0148] Suitable bio-based materials for producing polyurethanes are for example alcohols (in particular diols and polyols) and organic acids (in particular diacids) derived from natural materials such as starch, saccharose, glucose, lignocellulose, natural rubber or plant oils. Suitable alcohols and organic acids derived from natural materials are for example ethanol, monoethylene glycol, polyethylene glycol, isosorbide, 1,3-propanediol, 1 ,4-butanediol, glycerol, adipic acid or succinic acid. Preferably at least part of the polyurethane is made of bio-based materials.

[0149] For sustainability reasons it is preferred to use recycled raw materials for producing the polymers of at least one first polymer dispersion and / or of the at least one second polymer dispersion. Polyurethanes can be found in many products, for example, in soft foams (mattresses, sponges, upholstered furniture), hard foams (insulation materials, building materials), thermoplastics (sports shoes), coatings (varnishes, paints) or adhesives. There is a need for sustainable recycling of polyurethane waste, which allows the building blocks of polyurethane polymers to be reused. To do this, the bonds in the polyurethanes are split in order to be able to obtain defined degradation products and thus make them recyclable and reusable in the production of new polyurethanes. The polyurethane adhesive preferably consists to an extent of at least 5 weight%, more preferably at least 10 weight% of recycled materials, based on the sum total of all polyurethane adhesive synthesis components. One method of recycling of polyurethanes is thermal recycling. This process takes place at high temperatures, as well as with the use of catalysts to recover monomers or building blocks. For example, thermal glycolysis, which is currently the most common chemolysis for recycling of polyurethanes has already been implemented industrially. It allows the recovery of polyols. DE 102004014165 describes a method for the production of polyols from waste polyurethane by reacting a mixture of waste polyurethane, glycols or oligo-ester mixture (from polyester production) and primary and / or secondary aliphatic amines. EP 0733669 A2 describes a method for the utilization of plastic waste containing mixtures of polyurethanes and other plastics, comprising (a) reacting the waste with a mixture of low-molecular weight, at least difunctional alcohols (I) and polyether- polyol(s) (II), and (b) separating the polyol glycolysis products from the rest of the waste by mechanical methods. The glycolysis polyols obtained by this process can be used to manufacture new polyurethanes. Low-amine glycolysis products from polyurethane waste is preferably used as the recycled polyol. For economic reasons, preferably at least 5% by weight, more preferably at least 10% by weight, of recycled polyol, based on the total amount of isocyanate-reactive compounds are used for producing new polyurethanes.

[0150] The recycled polyols can be obtained by glycolysis of polyurethane waste with short-chain, hydroxyl-containing compounds, such as for example ethylene oxide-propylene oxide copolymers, OH-functionalized polybutadienes), ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, oligoethylene glycols, propylene glycol, dipropylene glycol, tripropylene glycol, oligopropylene glycols, ethylene oxide-propylene oxide copolymers, butanediol, 240838W001

[0151] 23

[0152] OH-functionalized polybutadienes, neopentyl glycol, glycerol, diethanolamine and triethanolamine, optionally obtained in the presence of organometallic catalysts at higher temperatures. Non-enzymatic hydrolysis at high temperature and high pressures allows recovery of both polyols and amines as re-usable products.

[0153] Another method is enzymatic degradation of polyurethanes into defined monomers which can be reused for production of new polyurethanes, for example by urethanases as described in WO 2019 / 243293. The recycled raw materials from enzymatic degradation for producing new polyurethanes preferably are low molecular weight degradation products, preferably of polyester-based polyurethanes, preferably with a molecular weight of at most 1,000 g / mol. Suitable recycled raw materials are for example

[0154] (i) polyols and polycarboxylic acids which were used to synthesize the polyester polyols used for the synthesis of the polyurethane in question; and

[0155] (ii) amines which are derived from the isocyanates used in the production of the polyurethane in question, for example in the case of 2,4-tolylene diisocyanate, 2, 4-toly lene diamine.

[0156] A "polyol” is understood to mean any compound having at least two hydroxyl groups.

[0157] Said low molecular weight polyol preferably has a molecular weight of at most 300 g / mol. Preferred recycled low molecular weight polyols are selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1 ,2-di-propylene glycol, neopentyl glycol, glycerol, 1,1,1 -trimethylolpropane, sucrose, sorbitol. Pentaerythritol and mixtures of two or more thereof.

[0158] A "polycarboxylic acid” is understood to mean any compound which contains at least two carboxyl groups. Said low molecular weight polycarboxylic acid preferably has a molecular weight of at most 300 g / mol. Preferred recycled low molecular weight polycarboxylic acids, are selected from the group consisting of succinic acid, glutaric acid, adipic acid, phthalic acid, terephthalic acid, benzene tricarboxylic acid, oleic acid, ricinoleic acid and mixtures of two or more thereof.

[0159] A "polyamine'' is understood to mean any compound which contains at least two amino groups. Said low molecular weight polyamine preferably has a molecular weight of at most 300 g / mol. Preferred low molecular weight recycled polyamines, are selected from the group consisting of 4,4'-methylenediamine, 2,4'-methylenediamine, 2,2'-meth- ylenediamine, 2,4-tolylenediamine, 2,6-tolylenediamine, hexamethylenediamine, isophoronediamine, xylylenedia- mine, pentamethylenediamine, para-phenylenediamine, butylenediamine, H12-methylenediamine, and mixtures of two or more thereof. The polyamines are particularly preferably selected from the group consisting of 4,4'-methylene- diamine, 2,4'-methylenediamine, 2,2'-methylenediamine, 2,4-tolylenediamine 2,6-tolylenediamine, and mixtures of two or more thereof.

[0160] In one aspect of the invention at least one of the polymers of the first polymer dispersion and / or at least one polymer of the second polymer dispersion is at least partly made of bio based or recycled material.

[0161] The invention provides a method of making water-barrier coated paper packaging wherein a) a paper or cardboard substrate is provided, and b) the paper or cardboard substrate is coated with the aqueous polymer dispersion described herein 240838W001

[0162] 24 wherein the paper packaging preferably is a folding box for food or a paper cup for hot or cold drinks.

[0163] In the process of coating, the aqueous polymer dispersion is applied to the paper substrates by means, for example, of knife coating, spreading, etc. Customary coating techniques may be employed, examples being roller coating, reverse roller coating, gravure roller coating, reverse gravure roller coating or flexo coating.

[0164] The aqueous polymer dispersion is applied to the paper substrate at a layer thickness of preferably 5 to 30 g / m2, more preferably 5 to 20 g / m2more preferably 5 to 15 g / m2(final dry coating weight). After a short time for evaporation of the dispersion water (preferably after 1 to 120 seconds at temperatures of preferably from 40 to 80 °C) the coated substrate may then be heat sealed by contacting the coated surfaces of one part of the substrate with another part of coated substrates and application of heat and pressure. Heat application can be done by heated bars or preferably by hot air.

[0165] The coated substrate may then be heat sealed by application of elevated temperatures and application of pressure. For that purpose, the coated substrate is first heated with hot air for a period of time in the range of from 0.5 to 1.5 seconds at a temperature in the range of from 100 to 500 °C. Then, two coated substrates are brought together for a period of time in the range of from 0.1 to 1.0 seconds. In a third step, pressure is applied in the range of from 100 to 2000 kN / m2, preferably from 150 to 1000 kN / m2more preferably from 150 to 500 kN / m2at a temperature in the range of 20 °C (room temperature, RT).

[0166] It is a special benefit of the invention that, the coated paper packaging substrates can be sealed by application of hot air at moderate temperatures. Sealing means that the paper packaging substrate can be folded and sealed onto itself without use of any additional adhesive or sealing material. Sealing onto itself means that the surface of one part of coated paper packaging substrate is contacted with the surface of another part of coated paper packaging material.

[0167] Therefore, the invention provides a method of making water-barrier coated paper packaging wherein a) a paper or cardboard substrate is provided, b) the paper or cardboard substrate is coated with the aqueous polymer dispersion described herein, c) the coated paper packaging is hot air sealed after the coating step, wherein the paper packaging preferably is a folding box for food or a paper cup for hot or cold drinks.

[0168] Preferred hot air sealing temperatures are from 150°C to 350°C, preferably from 170 to 340 °C

[0169] The substrates coated with the aqueous coating composition exhibit good water barrier effects. Water barrier effects can be expressed by the COBB value. The COBB value provides information about the water absorption capacity of paper and solid board or corrugated.

[0170] The aqueous polymer dispersion as described herein provides a COBB value of a paper substrate coated with the aqueous polymer dispersion of preferably less than 20 g / m2 / 30 min, more preferably less than 15 g / m2 / 30 min, more 240838W001

[0171] 25 preferably less than 13 g / m2 / 30 min, when tested with 90°C tap water for 30 minutes and / or wherein the COBB value of a paper substrate coated with the aqueous polymer dispersion of preferably less than 20 g / m2 / 30 min, preferably less than 15 g / m2 / 30 min, more preferably less than 12 g / m2 / 30 min, when tested with 60°C tap water for 30 minutes.

[0172] The aqueous polymer dispersion as described herein provides a COBB value of a paper substrate coated with the aqueous polymer dispersion of preferably less than 10 g / m2 / 30 min, more preferably less than 7 g / m2 / 30 min, when tested with tap water at room temperature (20 °C) for 30 minutes. The COBB measurements are performed according to ISO 535.

[0173] The invention also provides a paper packaging comprising a paper or cardboard substrate, wherein the paper or cardboard substrate is coated with the aqueous polymer dispersion as described herein, wherein the COBB value of the paper packaging preferably is less than 20 g / m2 / 30 min, more preferably less than 15 g / m2 / 30 min, more preferably less than 13 g / m2 / 30 min, when tested with 90°C tap water for 30 minutes and / or wherein the COBB value of the paper packaging preferably is less than 20 g / m2 / 30 min, preferably less than 15 g / m2 / 30 min, more preferably less than 12 g / m2 / 30 min, when tested with 60°C tap water for 30 minutes. The COBB value of the paper packaging preferably is less than 10 g / m2 / 30 min, more preferably less than 7 g / m2 / 30 min, when tested with tap water at room temperature (20 °C) for 30 minutes.

[0174] The paper packaging preferably is a folding box for food or a paper cup for hot or cold drinks.

[0175] The invention also provides the use of the aqueous polymer dispersion as described herein for hot air sealing of a paper packaging, the paper packaging comprising a paper or cardboard substrate, wherein the paper or cardboard substrate is coated with the aqueous polymer dispersion as described herein, and wherein the paper packaging preferably is a folding box for food or a paper cup for hot or cold drinks.

[0176] Examples

[0177] Materials:

[0178] Paper substrate 260 grs CupForma Natura board (Stora Enso)

[0179] Coating:

[0180] The coatings are applied by wire bar technology, the coatings are dried 1 minute at 60°C, final dry coating weight is 12 - 15 gr / m2

[0181] Heated bars heat sealing:

[0182] Heat sealing is done with heated bars according to ASTM F2029: 240838W001

[0183] 26 steel bars; 0.5 seconds dwell time, 3 bar pressure

[0184] The seal strength is the maximum force of the heat bar sealed coated substrates measured in a tensile tester and expressed as N / 15 mm.

[0185] Sealing is done either "coating-to-coating”, i.e. sealing a coated surface to another coated surface, or sealing is done "coating-to-board”, i.e. sealing a coated surface to an uncoated surface.

[0186] Hot air sealing

[0187] 1 .2 seconds pre-heating, 0.5 seconds sheet transportation, 1 .9 bar pressure

[0188] The minimum required temperature for full fiber tear is reported.

[0189] Sealing is done "coating-to-coating”, i.e. sealing a coated surface to another coated surface

[0190] Odor testing

[0191] Coated strips are stored in a closed bottle for 2 hours at 50 °C.

[0192] The odor is assessed by a trained odor panel on a scale from 1 = good to 5 = poor.

[0193] COBB Measurements

[0194] Water barrier performance is tested by COBB measurements according to ISO 535;

[0195] 30 minutes in water at room temperature (RT; 20 °C) and at 90°C.

[0196] DSC Measurements heating I cooling speed is 10°C / min (Tm = melting temperature, Tc = crystallization temperature and Ec = crystallization enthalpy)

[0197] DMTA Measurements heating I cooling speed = 3°C / min (listed are the storage modulus G' at room temperature (RT; 20 °C) (= related to coated and dried coating) and 150°C (= related to the surface temperature of the coating

[0198] Example 1 (comparison)

[0199] Aqueous polymer dispersion comprising styrene-acrylate polymers

[0200] An aqueous polymer dispersion was prepared as described in example 4 of WO 2017 / 210606 using the following types and amounts of monomers.

[0201] First stage, acid-rich styrene-acrylate copolymer

[0202] 13.96 wt.-parts n-butyl acrylate

[0203] 48.92 wt.-parts methyl methacrylate

[0204] 27.34 wt.-parts styrene

[0205] 9.78 wt.-parts acrylic acid 240838W001

[0206] 27

[0207] Second stage, acid-free styrene-acrylate copolymer, polymerized in the presence of the first stage acid-rich polymer: 25.49 wt.-parts 2-ethylhexyl acrylate 25.49 wt.-parts n-butyl acrylate

[0208] 17.01 wt.-parts iso-butyl methacrylate

[0209] 17.01 wt.-parts styrene

[0210] 15.00 wt.-parts of the first stage polymer

[0211] Example 2 (comparison)

[0212] Aqueous polymer dispersion comprising styrene-acrylate polymers

[0213] An aqueous polymer dispersion was prepared as described in example 4 of WO 2017 / 210606 using the following types and amounts of monomers.

[0214] First stage, acid-rich styrene-acrylate copolymer

[0215] 13.96 wt.-parts n-butyl acrylate

[0216] 48.92 wt.-parts methyl methacrylate

[0217] 27.34 wt.-parts styrene

[0218] 9.78 wt.-parts acrylic acid

[0219] Second stage, acid-free styrene-acrylate copolymer, polymerized in the presence of the first stage acid-rich polymer:

[0220] 33.97 wt.-parts n-butyl acrylate

[0221] 23.71 wt.-parts iso-butyl acrylate

[0222] 25.94 wt.-parts styrene

[0223] 16.38 wt.-parts of the first stage polymer

[0224] Example 3a (comparison) polyurethane dispersion: polyurethane made of a polyesterdiol of adipic acid and 1 ,4-butanediol (Mn 2400 g / mol) and toluene diisocyanate (80% 2,4-isomer, 20% 2,6-isomer) and hexamethylene diisocyanate as polyisocyanates, 2'- aminoethyl-2-aminoethancarboxylic acid Na salt and C Cis (CF CF OJisH as emulsifier, final solids content (DIN EN ISO 3251) of 40 wt.-%, pH (DIN ISO 976) 8. The polyurethane had a viscosity (DIN EN ISO 3219) of 40 mPas and a glass transition temperature Tg (ASTM D 3418-08) of -46°C. 240838W001

[0225] 28

[0226] Example 3b (comparison)

[0227] Polyurethane dispersion: polyurethane made of a polyesterdiol of adipic acid and 1 ,4-butanediol (Mn 2400 g / mol) and 5-isocyanato-1-(isocyanatomethyl)-1 ,3,3-trimethylcyclohexane (isophorone diisocyanate) and hexamethylene diisocyanate as polyisocyanates, 2'-aminoethyl-2-aminoethancarboxylic acid Na salt and C-ieC-is (CH2CH2O)ISH as emulsifier, final solids content (DIN EN ISO 3251) of 50 wt.-%, pH (DIN ISO 976) in the range of from 6 to 8. The polyurethane had a viscosity (DIN EN ISO 3219) in the range of from 50 to 250 mPas and a glass transition temperature Tg (ASTM D 3418-08) of -46°C.

[0228] Example 3c (comparison)

[0229] Polyurethane dispersion (PUD): polyurethane made of polyether diol polypropylene glycol (OH number 56) and toluene diisocyanate (80% 2,4-isomer, 20% 2,6-isomer) as polyisocyanate and dimethylolpropionic acid, neutralized with triethyl amine, final solids content (DIN EN ISO 3251) of 40 wt.-%, pH (DIN ISO 976) in the range of from 6 to 7. The polyurethane had a viscosity (DIN EN ISO 3219) in the range of from 20 to 120 mPas and a glass transition temperature Tg (ASTM D 3418-08) of about -45°C.

[0230] Example 3d (comparison)

[0231] Polyurethane dispersion: polyurethane made of a polyesterdiol of adipic acid and 1 ,4-butanediol (Mn 2400 g / mol) and toluene diisocyanate (80% 2,4-isomer, 20% 2,6-isomer) and hexamethylene diisocyanate as polyisocyanates, as well as 1 ,4-butanediol, 2'-aminoethyl-2-aminoethancarboxylic acid Na salt, NaOH and Ci3Ci2(CH2CH2O)5H as emulsifier and final solids content (DIN EN ISO 3251) of 45 wt.-%, pH (DIN ISO 976) about 7. The polyurethane had a 240838W001

[0232] 29 viscosity (DIN EN ISO 3219) in the range of from 50-180 mPas and a glass transition temperature Tg (ASTM D 3418-08) of about -48°C.

[0233] Example 4 to 6

[0234] Examples 4 to 6 are blends of examples 2 and 3a in weight amounts as listed in table 1 , Examples 7 to 9 are blends of example 2 with the examples 3b to 3d as indicated in table 1 in weight amounts as listed in table 1 . Tablel : Examples 4 to 6

[0235] The results of the odor test and the COBB test are summarized in Table 2.

[0236] Table 2: Test results of odor test and COBB test 240838W001

[0237] 30 x> Comparative example

[0238] The results of the heat sealing tests are summarized in Table 3.

[0239] Table 3: Test results of heat sealing tests x> Comparative example

[0240] Comparative examples 1 and 2 (styrene-acrylate copolymer dispersions) provide good water barrier effects of below 5 g / m2 / 30 min at room temperature and of below 15 g / m2 / 30 min at 90 °C, but lead to poor odor and high minimum temperatures for hot air sealing of above 400 °C.

[0241] Comparative example 3 (polyurethane dispersion) provides insufficient water barrier effects.

[0242] Inventive examples 4 to 6 provide sufficiently good odor (< 3), good water barrier effects (below 10, preferably below 5 g / m2 / 30 min at room temperature; and below 20, preferably below 15 g / m2 / 30 min at 90 °C) as well as reduced minimum temperatures for hot air sealing of below 400 °C, preferably below 350 °C. Inventive examples 7 to 9 provide good water barrier effects (below 10, preferably below 7 g / m2 / 30 min at room temperature; and below 20, preferably below 15, more preferably below 12 g / m2 / 30 min at 60 °C) as well as reduced minimum temperatures for hot air sealing of below 400 °C, preferably below 350 °C.

Claims

240838W00131Claims1 . Aqueous polymer dispersion obtained or obtainable from a first aqueous polymer dispersion A and a second aqueous polymer dispersion B; wherein(A) the first aqueous polymer dispersion A comprises(A.1) an acid-rich styrene-acrylate copolymer made by free-radical polymerization of(A.1 .a) from 40 to 80% by weight, preferably from 45 to 70% by weight, based on the total amount of monomers of copolymer (A.1), of at least one monomer selected from the group consisting of C1- to C12-alkyl (meth)acrylates; and(A.1 .b) from 15 to 40% by weight, preferably from 20 to 40% by weight, based on the total amount of monomers of copolymer (A.1), of styrene; and(A.1 .c) from 5 to 20% by weight, preferably from 5 to 15% by weight, based on the total amount of monomers of copolymer (A.1), of at least one carboxylic acid functional monomer, preferably selected from the group consisting of acrylic acid and methacrylic acid; and(A.1.d) optionally further monomers, different from monomers (A.

1. a), (A.1b) and (A.1.c); and (A.2) an acid-free styrene-acrylate copolymer made by free-radical emulsion polymerization of(A.

2. a) from 40 to 85% by weight, preferably from 50 to 80% by weight, based on the total amount of monomers of copolymer (A.2), of at least one monomer selected from the group consisting of C1- to C12-alkyl (meth)acrylates; and(A.2.b) from 15 to 50% by weight, preferably from 20 to 40% by weight, based on the total amount of monomers of copolymer (A.2), of styrene; and(A.2.c) optionally further monomers, different from monomers (A.

2. a), (A.2.b) and acid-functional monomers; and wherein the acid-free copolymer (A.2) is prepared in the presence of the acid-rich copolymer (A.1); and(B) the second aqueous polymer dispersion B comprises at least one polyurethane.

2. The aqueous polymer dispersion according to claim 1, wherein the acid-rich styrene-acrylate copolymer (A.1) has a glass transition temperature from 50 to 130 °C and an acid number from 50 to 250 mg KOH / g; and wherein the acid-free styrene-acrylate copolymer has a glass transition temperature from -40 to +40 °C, the glass transition temperature is measured by differential scanning calorimetry according to ASTM D 3418-08 as the midpoint temperature when evaluating the second heating curve at a heating rate of 20°C / min; the acid number is measured according to DIN EN ISO 1241.

3. The aqueous polymer dispersion according to claim 1 or claim 2, wherein the amount of acid-rich styrene-acrylate copolymer (A.1) in the first polymer dispersion A is from 5 to 50 wt.%, preferably from 10 to 40 wt.%, based on the total amount of polymers in the first polymer dispersion A; and the amount of acid-free styrene-acrylate copolymer (A.2) in the first polymer dispersion A is from 50 to 95 wt.%, preferably from 60 to 90 wt.%, based on the total amount of polymers in the first polymer dispersion A.240838W001324. The aqueous polymer dispersion according to any of claims 1 to 3, wherein the weight ratio of first aqueous polymer dispersion A to second aqueous polymer dispersion B is from 40:60 to 80:20, preferably from 55:45 to 80:20, more preferably from 55:45 to 70:30, based on the total weight of the aqueous dispersions.

5. The aqueous polymer dispersion according to any of claims 1 to 4, wherein each of monomer (A.

1. a) and monomer (A.2.a) is independently each at least one monomer selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tertbutyl (meth)acrylate, n-hexyl acrylate, cyclohexyl (meth)acrylate, 2-octyl acrylate, 2-ethylhexyl acrylate and 2- propylheptyl acrylate; and / or wherein the carboxylic acid functional monomer (A.1.c) is an ethylenically unsaturated monomer with at least one carboxylic acid group and is at least one monomer selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, cratonic acid, vinylacetic acid and vinyllactic acid, preferably acrylic acid, methacrylic acid or their mixture.

6. The aqueous polymer dispersion according to any of claims 1 to 5, wherein the first copolymer (A.1) is made of at least one further monomer (A.1 .d) and / or wherein the second copolymer (A.2) is made of at least one further monomer (A.2.c), and wherein each of monomer (A.1.d) and monomer (A.2.c) is independently at least one monomer selected from the group consisting of vinyl esters of carboxylic acids comprising up to 20 carbon atoms, vinylaromatics other than styrene having up to 20 carbon atoms, vinyl halides, vinyl ethers of alcohols comprising 1 to 10 carbon atoms, aliphatic hydrocarbons having 2 to 8 carbon atoms and one or two double bonds, acrylamide, methacrylamide, C1-C10 aminoalkyl(meth)acrylates, nitriles of alpha-, beta-monoethylenically unsaturated C3-C8 carboxylic acids, bifunctional monomers which as well as an ethylenically unsaturated double bond have at least one group selected from the group consisting of glycidyl group, oxazoline group, ureido group and ureido-analogous group, crosslinking monomers which have more than one radically polymerizable group, more particularly two or more (meth)acrylate groups, and ethylenically unsaturated monomers with at least one hydroxy group preferably selected from the group consisting of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate or hydroxypropyl methacrylate, 4-hydroxybutyl acrylate and 4-hydroxy- butyl methacrylate.

7. The aqueous polymer dispersion according to any of claims 1 to 6, wherein(A) the first aqueous polymer dispersion A comprises(A.1) an acid-rich styrene-acrylate copolymer made by free-radical polymerization of(A.1 .a) from 45 to 70% by weight, based on the total amount of monomers of copolymer (A.1), of at least one monomer selected from the group consisting of methyl (meth)acrylate, ethyl acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl acrylate, 2-octyl acrylate, 2-ethylhexyl acrylate and 2-propylheptyl acrylate; and240838W00133(A.1 ,b) from 20 to 40% by weight, based on the total amount of monomers of copolymer (A.1), of styrene; and(A.1 ,c) from 5 to 15% by weight, based on the total amount of monomers of copolymer (A.1 ), of acrylic acid, methacrylic acid or their mixture; and(A.2) an acid-free styrene-acrylate copolymer made by free-radical emulsion polymerization of(A.2.a) from 50 to 80% by weight, based on the total amount of monomers of copolymer (A.2), of at least one monomer selected from the group consisting of methyl (meth)acrylate, ethyl acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl acrylate, 2-octyl acrylate, 2- ethylhexyl acrylate and 2-propylheptyl acrylate; and(A.2.b) from 20 to 40% by weight, based on the total amount of monomers of copolymer (A.2), of styrene; wherein the acid-free copolymer (A.2) is prepared in the presence of the acid-rich copolymer (A.1), and wherein the amount of acid-rich copolymer (A.1) is from 10 to 40 wt.%, based on the total amount of polymers in the first polymer dispersion A; and the amount of acid-free copolymer (A.2) is from 60 to 90 wt.%, based on the total amount of polymers in the first polymer dispersion A; and wherein the weight ratio of first aqueous polymer dispersion A to second aqueous polymer dispersion B is from 40:60 to 80:20, preferably from 55:45 to 80:20, more preferably from 55:45 to 70:30, based on the total weight of the aqueous dispersions; and wherein the acid-rich styrene-acrylate copolymer (A.1) has a glass transition temperature from 50 to 130 °C and an acid number from 50 to 250 mg KOH / g; and wherein the acid-free styrene-acrylate copolymer has a glass transition temperature from -40 to +40 °C, the glass transition temperature is measured by differential scanning calorimetry according to ASTM D 3418-08 as the midpoint temperature when evaluating the second heating curve at a heating rate of 20°C / min; the acid number is measured according to DIN EN ISO 1241.

8. The aqueous polymer dispersion according to any of claims 1 to 7, wherein the polyurethane is constructed from a) at least one monomeric diisocyanate, b) at least one diol, of which b1) 10 to 100 mol%, based on the total amount of the diols (b), have a molecular weight of 500 to 5000 g / mol and b2) 0 to 90 mol%, based on the total amount of the diols (b), have a molecular weight of 60 to 500 g / mol, c) at least one monomer distinct from the monomers (a) and (b) having at least one isocyanate group or at least one isocyanate-reactive group which further bears at least one hydrophilic group or a potentially hydrophilic group, and d) optionally at least one further compound distinct from the monomers (a) to (c) having at least two reactive groups selected from the group consisting of alcoholic hydroxyl groups, primary or secondary amino groups and isocyanate groups, and240838W00134 e) optionally at least one monofunctional compound distinct from the monomers (a) to (d) having a reactive group which is an alcoholic hydroxyl group, a primary or secondary amino group or an isocyanate group.

9. The aqueous polymer dispersion according to claim 8, wherein the at least one diisocyanate a) is at least one diisocyanate selected from diisocyanates of the formula X(NCO)2, wherein X represents an acyclic aliphatic hydrocarbon radical having 4 to 15 carbon atoms, a cycloaliphatic hydrocarbon radical having 6 to 15 carbon atoms, an aromatic hydrocarbon radical having 6 to 15 carbon atoms or an araliphatic hydrocarbon radical having 7 to 15 carbon atoms, preferably selected from the group consisting of hexamethylene diisocyanate, 5-isocya- nato-1-(isocyanatomethyl)-1,3,3-trimethylcyclohexane, 2,6-diisocyanatotoluene, 2,4-diisocyanatotoluene, tetramethylxylylene diisocyanate, oligocarbodiimide-diisocyanate based on meta-tetramethylxylylendiisocyanate, 4,4-methylene dicyclohexyl diisocyanate and mixtures of two or more thereof; the diols b1) are at least one diol selected from the group consisting of polyester diols, polycarbonate diols, polyether diols and mixtures of two or more thereof, preferably at least one diol selected from the group consisting of polyester diols, polyether diols, and mixtures of two or more thereof; the optional diols b2) are at least one diol selected from the group consisting of ethylene glycol, butane-1 ,4-diol, hexane-1 ,6-diol, octane-1 , 8-diol, do- decane-1 , 12-diol, neopentyl glycol, and mixtures of two or more thereof; and the compound c) is at least one compound selected from the group consisting of dihydroxycarboxylic acids, diaminocarboxylic acids, diaminosulfonic acids, and mixtures of two or more thereof, preferably at least one compound selected from the group consisting of dihydroxycarboxylic acids, diaminocarboxylic acids, and mixtures of two or more thereof.

10. The aqueous polymer dispersion according to any of claims 1 to 9, wherein the polyurethane of the second aqueous polymer dispersion B has a glass transition temperature from -50 to -10 °C, preferably from -50 to - 40°C, the glass transition temperature is measured by differential scanning calorimetry according to ASTM D 3418-08 as the midpoint temperature when evaluating the second heating curve at a heating rate of 20°C / min.11 . The aqueous polymer dispersion according to any of claims 1 to 10, wherein at least one of the polymers of the first polymer dispersion and / or at least one polymer of the second polymer dispersion is at least partly made of bio based or recycled material.

12. The aqueous polymer dispersion according to any of claims 1 to 11 , wherein the COBB value of a paper substrate coated with the aqueous polymer dispersion is less than 20 g / m2 / 30 min, preferably less than 15 g / m2 / 30 min, more preferably less than 13 g / m2 / 30 min, measured at 90°C according to ISO 535 and / or wherein the COBB value of a paper substrate coated with the aqueous polymer dispersion is less than 20 g / m2 / 30 min, preferably less than 15 g / m2 / 30 min, more preferably less than 12 g / m2 / 30 min, measured at 60°C according to ISO 535 and / or wherein the COBB value of a paper substrate coated with the aqueous polymer dispersion is less than 10 g / m2 / 30 min, preferably less than 7 g / m2 / 30 min, measured at 20°C according to ISO 535.240838W0013513. Method of making water-barrier coated paper packaging wherein a) a paper or cardboard substrate is provided, and b) the paper or cardboard substrate is coated with the aqueous polymer dispersion according to any of claims 1 to 12; wherein the paper packaging preferably is a folding box for food or a paper cup for hot or cold drinks; wherein the coated paper packaging is preferably hot air sealed after the coating step.

14. Paper packaging comprising a paper or cardboard substrate, wherein the paper or cardboard substrate is coated with the aqueous polymer dispersion according to any of claims 1 to 12, wherein the COBB value of the paper packaging preferably is less than 20 g / m2 / 30 min, more preferably less than 15 g / m2 / 30 min, more preferably less than 13 g / m2 / 30 min, measured at 90°C according to ISO 535 and / or wherein the COBB value of the paper packaging preferably is less than 20 g / m2 / 30 min, preferably less than 15 g / m2 / 30 min, more preferably less than 12 g / m2 / 30 min, measured at 60°C according to ISO 535 and / or wherein the COBB value of the paper packaging preferably is less than 10 g / m2 / 30 min, more preferably less than 7 g / m2 / 30 min, measured at 20°C according to ISO 535; and wherein the paper packaging preferably is a folding box for food or a paper cup for hot or cold drinks.

15. Use of the aqueous polymer dispersion of any of claims 1 to 12 for hot air sealing of a paper packaging, the paper packaging comprising a paper or cardboard substrate, wherein the paper or cardboard substrate is coated with the aqueous polymer dispersion according to any of claims 1 to 12, and wherein the paper packaging preferably is a folding box for food or a paper cup for hot or cold drinks.

Images