The present invention relates to a process for manufacturing an aqueous polyurethane dispersion. Further, the present invention relates to an aqueous polyurethane dispersion which is obtained by the before-mentioned process, and a use of said aqueous polyurethane dispersion.

Polyurethane prepolymers are known in many ways. Urethane polymers such as polyurethanes and polyurethane/urea elastomers form a very significant part of the synthetic polymer industry worldwide. In the formation of such products it is common to prepare a prepolymer by reacting a polyisocyanate with a polyol, generally in a ratio of two mole of diisocyanate to one mole of diol. In preparing the product for its ultimate use, this prepolymer is reacted with a chain extending agent, such as a short chain diol or aromatic diamine to produce the final product in the form of a polyurethane or urethane/urea polymer. These urethane polymers are useful in a variety of applications such as in protective coatings and molded articles.

EP 1 685 172 Bl discloses a polyurethane dispersion with improved isopropanol resistance, flexibility and softness. A functionality of one of the polyols is three (3), and, consequently, the viscosity of the prepolymer is high and a solvent, namely acetone, must be used. The polyurethane formed from the prepolymer is a covalently bonded elastomer, not a thermoplastic elastomer. This is a disadvantage. There is a need to form a polyurethane, with good properties, like high elasticity and high tear strength, preferably without solvent, and that should form a stable dispersion of this polymer.

The object of the present invention is to provide for a process for manufacturing an aqueous polyurethane dispersion which has better properties than known dispersions.

This problem is solved according to the invention by a process for manufacturing an aqueous polyurethane dispersion, the process comprising

- forming an at least one isocyanate-terminated polyurethane prepolymer, wherein a composition is provided comprising at least one compound selected from a group of at least one polyol, wherein the composition has an ethylene oxide content of approximately 2 wt.-% to approximately 20 wt.%, referred to the total amount of the composition, and wherein a mixture is obtained by mixing the composition with at least one difunctional isocyanate,

- dispersing the at least one isocyanate-terminated polyurethane prepolymer obtained in an aqueous phase or adding water to the at least one isocyanate-terminated polyurethane prepolymer, and

- reacting the at least one isocyanate-terminated polyurethane prepolymer mixture with at least one chain extension agent to obtain the aqueous polyurethane dispersion.

The ethylene oxide content provides stability of the aqueous polyurethane dispersion forming from the at least one isocyanate-terminated polyurethane prepolymer. An ethylene oxide content in the composition, and then in the prepolymer, increases the stability of the aqueous polyurethane dispersion. This avoids the isocyanate-terminated polyurethane prepolymer to precipitate when it is in dispersion. The ethylene oxide content in the prepolymer is preferably in a range between approximately 3 wt.% and approximately 13 wt.-%, and further preferably in a range between approximately 5 wt.% and approximately 10 wt.-%, in each case referred to the total amount of the prepolymer.

The mixture is obtained by mixing the composition with at least one difunctional isocyanate, so that the isocyanate-terminated polyurethane prepolymer can be formed. The mixture obtained by mixing the composition with at least one difunctional isocyanate may preferably comprise in addition at least a modifier added, and/or at least one neutralization agent added, the latter being defined below. The compounds are added in the mixture and react in order to obtain the isocyanate-terminated polyurethane prepolymer.

In the context of the invention, the expressions "about" and "approximately" in connection with numerical values or ranges are to be understood as a tolerance range, which a person skilled in the art would consider as common or reasonable based on his or her general knowledge and in view of the invention as a whole. In particular, the expressions "about" and "approximately" refer to a tolerance range of ±20 %, preferred ±10 % and further preferred ±5 % with respect to the designated value. For example, the above-mentioned range for the ethylene oxide content may be rewritten with a tolerance of ±10 % as "an ethylene oxide content of 1,8 wt.-% to 22 wt.-%", thereby deleting the term "approximately". The lower end values and the upper end values of the various ranges, including the preferred, further preferred, especially preferred ranges and even more preferred ranges, used in the present invention, especially the weight percent ranges, but not restricted thereto, may be combined with each other in order to define new ranges, as far as said ranges have an identical reference like a physical or a chemical parameter or a substance or composition, e.g. refer to an identical physical parameter such as the temperature or to a substance such as the at least one polyol, the composition, the mixture , or the at least one difunctional isocyanate. For example, the ethylene oxide content may be defined to be between approximately 2 wt.-% and approximately 15 wt.-%, referred to the total amount of the composition, based on the definitions of the ranges given above.

The expression "wt.-%" is used throughout the present invention as an abbreviation for weight percent if not indicated otherwise.

The composition according to the invention provided comprises at least one compound selected from a group of at least one polyol. The at least one polyol is described in the following with respect to two embodiments.

In one embodiment the at least one polyol provides the ethylene oxide content. The at least one polyol providing the ethylene oxide content has preferably a weight average molecular weight M _w in a range of approximately 4000 g/mol to approximately 25000 g/mol, further preferably in a range of approximately 8000 g/mol to approximately 22000 g/mol, especially preferably in a range of approximately 12000 g/mol to approximately 20000 g/mol, and further preferably in a range of approximately 6000 g/mol to approximately 25000 g/mol. The weight average molecular weight depends not only on the number of molecules present, but also on the weight of each molecule. The at least one polyol providing the ethylene oxide content has preferably a polydispersity index in a range of approximately 1,0 to approximately 4,0, further preferred in a range of approximately 1,01 to approximately 2,0, and especially preferably in a range of approximately 1,05 to approximately 1,2. The polydispersity index (PDI) is a measure of the heterogeneity of a sample based on size. PDI = M _w /M _n , where M _w is the weight average molar mass and M _n is the number average molar mass. The at least one polyol providing the ethylene oxide content is preferably a DMC-polyol. The at least one polyol providing the ethylene oxide content is preferably produced with so-called double metal cyanide complex (DMC) catalysts. The at least one polyol providing the ethylene oxide content has preferably a degree of unsaturation in a range of approximately 0,001 mEq/g to approximately 0,05 mEq/g, measured according to ASTM D4671-16, method A, further preferred in a range of approximately 0,005 mEq/g to approximately 0,04 mEq/g, and especially preferably in a range of approximately 0,01 mEq/g to approximately 0,03 mEq/g. The at least one polyol providing the ethylene oxide content is preferably a long chain polyol. Long polyol chains allow for a more elastic prepolymer than prepolymers with short polyol chains. Preferably, the at least one polyol providing the ethylene oxide content is a difunctional polyol. The difunctionality of the polyol allows the prepolymer to grow linearly when polyols react with diisocyanate. Preferably, the at least one polyol is selected from a group comprising polyether diols, polyester diols, dimer diols, dimerized fatty acid-based diols, polyester based diols, or a mixture of at least two of the before-mentioned polyols. Preferably, the at least one polyol is a linear polymer. Preferably, the at least one polyol is substantially linear. A linear polymer is produced when each monomer is capable of bonding to two others. An essentially linear polymer is produced when about 95% of the monomers are capable of bonding to two others. The at least one polyol is unbranched. The branching of a polymer in the sense of the present invention is the regular or irregular attachment of side chains to a polymer's backbone chain. The at least one polyol providing the ethylene oxide content has preferably a dynamic viscosity in a range of approximately 2000 mPas to approximately 30000 mPas, further preferably in a range of approximately 2500 mPas to approximately 27000 mPas, and even more preferably in a range of approximately 5000 mPas to approximately 20000 mPas, measured with a Brookfield DV2T EXTRA™ Viscometer at 30 °C according to DIN EN ISO 2884-2, dated September2006.The at least one polyol providing the ethylene oxide content is preferably added in an amount in a range between approximately 15 wt.-% and approximately 80 wt.-%, referring to the total amount of the mixture, further preferably in a range between approximately 20 wt.-% and approximately 70 wt.-%, and even more preferably in a range between approximately 25 wt.-% and approximately 60 wt.-%. The at least one polyol providing the ethylene oxide content is preferably added in an amount in a range between approximately 50 wt.-% and approximately 100 wt.-%, referring to the total amount of the composition , further preferably in a range between approximately 55 wt.-% and approximately 95 wt.-%, and even more preferably in a range between approximately 60 wt.-% and approximately 90 wt.-%. The at least one polyol providing the ethylene oxide content has an ethylene oxide content of approximately 2 wt.-%, preferably of approximately 8 wt.-%, to approximately 20 wt.%, referred to the total amount of the composition, preferably of approximately 5 wt.-% to approximately 18 wt.%, further preferably of approximately 7 wt.-% to approximately 15 wt.%, and further preferably of approximately 12 wt.-% to approximately 20 wt.-%. The at least one polyol providing the ethylene oxide content is preferably a copolymer selected from a group comprising block copolymers, statistical copolymers or sequential copolymers. The polyol providing the ethylene oxide content comprises preferably at least two types of constituent units, namely a first constituent unit without any ethylene oxide group, and a second constituent unit comprising at least one ethylene oxide group. The first constituent unit of the polyol of the composition is selected from a group comprising propylene oxide, ether, ester, dimerized fatty acid or a mixture of at least two of the before mentioned compounds. Preferably, the at least one polyol providing the ethylene oxide content is a polyol block copolymer. The polyol block copolymer is preferably a block polyethylene oxide-b-propylene oxide). The at least one polyol providing the ethylene oxide content is preferably an ethylene oxide endcapped polyol. Ethylene oxide endcapped polyol in the sense of the present invention is also called ethylene oxide tipped polyol. Ethylene oxide-capped polyols are advantageously used because of the favourable reactivity of their primary hydroxyl groups with polyisocyanates. The synthesis of ethylene oxide endcapped polyols is generally known by persons skilled in the art. Ethylene oxidecapped polyols are usually prepared in two steps. First, propylene oxide (or a mixture of propylene oxide and ethylene oxide) is polymerized in the presence of a basic catalyst (usually potassium hydroxide) to produce a polyol that contains mostly or exclusively secondary hydroxyl groups. Second, ethylene oxide is added to the catalyst-containing mixture to convert some or most of the secondary hydroxyl groups to primary hydroxyl groups. The use of ethoxylated ethylene oxide polyols, preferably endcapped polyols, providing the ethylene oxide content improve advantageously the stability of the polyurethane dispersion. The polyol, being endcapped with ethylene oxide, is preferably a block polyethylene oxide-b-propylene oxide-b-ethylene oxide). Preferably the at least one polyol providing the ethylene oxide content comprises ethylene oxide in its inside chains. The block of second units of the polyol copolymer is comprised between two blocks of first units. The at least one polyol providing the ethylene oxide content is preferably a block polypropylene oxide-b- ethylene oxide-b-propy- lene oxide). Preferably the at least one polyol providing the ethylene oxide content is a polyol alternating copolymer. The at least one polyol providing the ethylene oxide content is preferably an alternating poly( ethylene oxide-o/t-propylene oxide). Preferably, the at least one polyol providing the ethylene oxide content is a polyol statistical copolymer. The at least one polyol providing the ethylene oxide content is preferably a statistical poly( ethylene ox- ide-sto-propylene oxide). Preferably, the at least one polyol comprising the ethylene oxide content is a polyol sequential copolymer. The at least one polyol providing the ethylene oxide content is preferably a sequential polyethylene oxide-seq-propylene oxide). The at least one polyol providing the ethylene oxide content is preferably not a grafted copolymer. A grafted copolymer would increase the viscosity of the prepolymer.

In another embodiment the at least one polyol does not provide the ethylene oxide content. The at least one polyol without any ethylene oxide content has preferably a weight average molecular weight M _w in a range of approximately 4000 g/mol to approximately 25000 g/mol, further preferably in a range of approximately 10000 g/mol to approximately 22000 g/mol, especially preferably in a range of approximately 12000 g/mol to approximately 20000 g/mol, and further preferably in a range of approximately 6000 g/mol to approximately 25000 g/mol. The at least one polyol without any ethylene oxide content has preferably a polydispersity index (PDI) in a range of approximately 1,0 to approximately 4,0, further preferably in a range of approximately 1,01 to approximately 2,0, especially preferably in a range of approximately 1,05 to approximately 1,2. The at least one polyol without any ethylene oxide content is preferably a DMC-polyol. The at least one polyol without any ethylene oxide content is preferably produced with so-called double metal cyanide complex (DMC) catalysts. The at least one polyol without any ethylene oxide content has preferably a degree of unsaturation in a range of approximately 0,001 mEq/g to approximately 0,05 mEq/g, measured according to ASTM D4671-16, method A, further preferably in a range of approximately 0,005 mEq/g to approximately 0,04 mEq/g, especially preferably in a range of approximately 0,01 mEq/g to approximately 0,03 mEq/g. Preferably, the at least one polyol without any ethylene oxide content is a difunctional polyol. Preferably, the at least one polyol without any ethylene oxide is selected from a group comprising polyether diols, polyester diols, dimer diols, dimerized fatty acid-based diols, polyester based diols, or a mix- ture of at least two of the before-mentioned polyols. Preferably, the at least one polyol without any ethylene oxide content is a linear polymer. Further preferably, the at least one polyol without any ethylene oxide is substantially linear. The at least one polyol without any ethylene oxide is preferably unbranched. The at least one polyol without any ethylene oxide content has preferably a dynamic viscosity, in a range of approximately 2000 mPas to approximately 30000 mPas, further preferably in a range of approximately 2500 mPas to approximately 27000 mPas, and even more preferably in a range of approximately 5000 mPas to approximately 20000 mPas, measured with a Brookfield DV2T EXTRA™ Viscometer at 30 °C according to DIN EN ISO 2884-2, dated September 2006. The amount of the at least one polyol without any ethylene oxide content is preferably in a range between approximately 15 wt.-% and approximately 80 wt.-%, referring to the total amount of the mixture, further preferably in a range between approximately 20 wt.-% and approximately 70 wt.-%, and even more preferably in a range between approximately 25 wt.-% and approximately 60 wt.- %. The at least one polyol without any ethylene oxide content is preferably present in the composition in an amount in a range between approximately 25 wt.-% and approximately 65 wt.-%, referring to the total amount of the composition, further preferably in a range between approximately 30 wt.-% and approximately 60 wt.-%, and even more preferably in a range between approximately 35 wt.-% and approximately 55 wt.-%. For clarification purposes, the at least one polyol without any ethylene oxide content is, of course, not an ethylene oxide endcapped polyol.

In this embodiment, a second polyol may provide the ethylene oxide content. The second polyol providing the ethylene oxide content has preferably a weight average molecular weight M _w in a range of approximately 1000 g/mol to approximately 25000 g/mol, further preferably in a range of approximately 2000 g/mol to approximately 22000 g/mol, especially preferably in a range of approximately 3000 g/mol to approximately 20000 g/mol, and even further preferably in a range of approximately 3000 g/mol to approximately 8000 g/mol or to approximately 6000g/mol. The second polyol providing the ethylene oxide content has preferably a polydispersity index (PDI) in a range of approximately 1,0 to approximately 4,0, further preferably in a range of approximately 1,01 to approximately 2, especially preferably in a range of approximately 1,05 to approximately 1,2. The second polyol providing the ethylene oxide content can be a short chain polyol or a long chain polyol. Preferably, the sec- ond polyol providing the ethylene oxide content is a difunctional polyol. Preferably, the second polyol is selected from a group comprising polyethylene oxide), polyether diols, polyester diols, dimer diols, dimerized fatty acid based diols, polyester based diols, or a mixture of at least two of the before-mentioned polyols. Preferably, the second polyol is a linear polymer. Preferably is the second polyol substantially linear. The second polyol is preferably unbranched. The second polyol providing the ethylene oxide content has preferably a dynamic viscosity, in a range of approximately 500 mPas to approximately 30000 mPas, further preferably in a range of approximately 750 mPas to approximately 27000 mPas, and even more preferably in a range of approximately 1000 mPas to approximately 20000 mPas, measured with a Brookfield DV2T EXTRA™ Viscometer at 30 °C according to DIN EN ISO 2884-2, dated September2006. The second polyol providing the ethylene oxide content is preferably added in an amount in a range between approximately 15 wt.-% and approximately 55 wt.- %, referring to the total amount of the mixture, further preferably in a range between approximately 20 wt.-% and approximately 50 wt.-%, and even more preferably in a range between approximately 25 wt.-% and approximately 45 wt.-%. The second polyol providing the ethylene oxide content is preferably added in an amount in a range between approximately 25 wt.-% and approximately 65 wt.-%, referring to the total amount of the composition, further preferably in a range between approximately 30 wt.-% and approximately 60 wt.-%, and even more preferably in a range between approximately 35 wt.-% and approximately 55 wt.-%. The second polyol providing the ethylene oxide content has an ethylene oxide content of approximately 2 wt.-% to approximately 50 wt.%, referred to the total amount of the composition, preferably of approximately 5 wt.-% to approximately 45 wt.%, further preferably of approximately 7 wt.-% to approximately 40 wt.%, and further preferably 12 wt.-% to approximately 25 wt.-%. The second polyol providing the ethylene oxide content is preferably a copolymer selected from a group comprising block copolymers, alternating copolymers, statistical copolymers or sequential copolymers. The second polyol providing the ethylene oxide content comprises preferably at least two types of constituent units, namely a first constituent unit without any ethylene oxide group, and a second constituent unit providing at least one ethylene oxide group. The first constituent unit of the second polyol without any ethylene oxide content is preferably selected in a group comprising propylene oxide, ether, ester, dimerized fatty acid or a mixture of at least two of the before mentioned compounds. Preferably the second polyol providing the ethylene oxide con- tent is a polyol block copolymer. The second polyol providing the ethylene oxide content is preferably a block poly( ethylene oxide-b-propylene oxide). The second polyol providing the ethylene oxide content is preferably an ethylene oxide endcapped polyol. The use of such a second, ethoxylated ethylene oxide polyol, preferably endcapped polyol, improves advantageously the stability of the polyurethane dispersion. In this embodiment, the composition of the at least one first polyol without any ethylene oxide content, and the at least one second polyol providing the ethylene oxide content, has an ethylene oxide content of approximately 2 wt.-%, preferably of approximately 8 wt.-%, to approximately 20 wt.%, referred to the total amount of the composition, preferably of approximately 5 wt.-% to approximately 18 wt.%, further preferably of approximately 7 wt.-% to approximately 15 wt.%, and further preferably of approximately 12 wt.-% to approximately 20 wt.-%. The polyol, being endcapped with ethylene oxide, is preferably a block polyethylene oxide-b-propylene oxide-b- ethylene oxide). The second polyol providing the ethylene oxide content is preferably a copolymer with a polysiloxane middle block and ethylene oxide and propylene oxide copolymer side blocks or a copolymer with a polysiloxane middle block and ethylene oxide and butylene oxide copolymer side blocks or a copolymer with a polysiloxane middle block and ethylene oxide and propylene oxide and butylene oxide copolymer side blocks. Preferably the second polyol providing the ethylene oxide content comprises ethylene oxide in its inside chains. The block of second units of the polyol copolymer is comprised between two blocks of the first units. The second polyol providing the ethylene oxide content is preferably a block polypropylene oxide-b- ethylene oxide-b-propylene oxide). Preferably the second polyol providing the ethylene oxide content is a polyol alternating copolymer. The second polyol providing the ethylene oxide content is preferably an alternating polyethylene oxide- o/t-propylene oxide). Preferably the second one polyol providing the ethylene oxide content is a polyol statistical copolymer. The second polyol providing the ethylene oxide content is preferably a statistical polyethylene oxide-sto-propylene oxide). Preferably the second polyol providing the ethylene oxide content is a polyol sequential copolymer. The second polyol providing the ethylene oxide content is preferably a sequential polyethylene oxide- seq-propylene oxide). The second polyol providing the ethylene oxide content is preferably not a grafted copolymer. A grafted copolymer would increase the viscosity of the prepolymer. The second polyol providing the ethylene oxide content is preferably polyethylene oxide). Poly( ethylene oxide)is named poly(oxyethylene) or polyethylene glycol, too. Poly(ethyl- ene oxide) is a hydrophilic molecule and is stable in water.

The at least one difunctional isocyanate is preferably selected from a group comprising aliphatic isocyanate, cycloaliphatic isocyanate, aromatic isocyanate or a mixture of at least two of the before-mentioned isocyanates. Further, the at least one difunctional isocyanate is preferably a diisocyanate selected from the group comprising aliphatic diisocyanates, cycloaliphatic diisocyanates and aromatic diisocyanates such as toluene diisocyanate (TDI), p- phenylene diisocyanate (PPDI), 4,4'-diphenylmethane diisocyanate (MDI), p,p'-bisphenyl di- isocyanate(BPDI), isophorone diisocyanate (IPDI), 1,6-hexamethylene diisocyanate (HDI), dicyclohexylmethane, hydrogenate di-phenylmethane-4,4'-diisoyanate (H ₁₂ MDI), metatetramethylxylene diisocyanate (TMXDI) and a mixture thereof. Examples of suitable diisocyanates are diphenylmethane diisocyanate (MDI), preferably diphenylmethane-4,4'-diiso- cyanate (4,4'-MDI), diphenylmethane-2,4'-diisocyanate (2,4'-MDI), diphenylmethane-2,4'-di- isocyanate (2,2'-MDI), 4,4'-diisocyanatodicyclohexylmethane (H ₁₂ MDI), 2-methylpen- tamethylene-l,5-diisocyanate, 2,2,4- and 2,44-trimethyl-l,6-hexamethylene diisocyanate (TMDI), 1,12 dodecamethylene diisocyanate, lysine and lysine ester diisocyanate, cyclohexane 1,3-diisocyanate, cyclohexane 1,4-diisocyanate, 3-isocyanate-methyl-3,5,5-trimethylcy- clohexylisocyanate (= isophorone diisocyanate or IPDI), perhydro-2,4'-diphenylmethane diisocyanate and perhydro-4,4'-diphenylmethane diisocyanate l,4-diisocyanato-2,2,6- trimethylcyclohexane (TMCDI), 1,6 hexamethylene diisocyanate (HDI) or the trimer thereof (HDI trimer), l,4-bis(isocyanate)cyclohexane, 1, 4-bis(isocyanate)benzene (PPDI), 1,3- and/or l,4-bis(isocyanatomethyl)cyclohexane, m- and/or p-xylylene diisocyanate (m- and/or p-XDI), m- and/or p-tetramethyl-1, 3-xylylene diisocyanate, bis-(l-isocyanato-l-methylethyl)-naph- thalene, 2,4- and 2,6-toluene diisocyanate (TDI), 1,3- and 1,4-phenylene diisocyanate, 2,4- dioxo-l,3-diazetidine-l, 3-bis(methyl-m-phenylene)diisocyanate, 2,3,5,6-tetramethyl-l,4-di- isocyanatobenzene, naphthalene-l,5-diisocyanate (NDI), 3,3'3'-dimethyl-4,4'4'-diisocyana- todiphenyl (TODI), or mixtures thereof. Further preferred isophorone diisocyanate (IPDI), diphenylmethane-2,4'-diisocyanate (2,4'-MDI) and diphenylmethane-4,4'-diisocyanate (4,4'- MDI), as well as their mixtures in combination with other isocyanate-containing compounds. More preferred diisocyanates are diphenylmethane-4,4'-diisocyanate (4,4'-MDI), diphenyl- methane-2,4'-diisocyanate (2,4'-MDI) or isophorone diisocyanate (IPDI), 1,6 hexamethylene diisocyanate (HDI) or the trimer thereof (HDI-trimer), or mixtures thereof. Most preferred diisocyanates are diphenylmethane-4,4'-diisocyanate (4,4'-MDI), diphenylmethane-2,4'-di- isocyanate (2,4'-MD) and/or isophorone diisocyanate (IPDI), oligomers and polymers of the above isocyanates, as well as any mixtures of said isocyanates. Preferred cycloaliphatic diisocyanates are, for example, l-isocyanatomethyl-3-isocyanato-l,5,5-trimethyl-cyclohexane (isophorone diisocyanate, IPDI), l-methyl-2,4-diisocyanato-cyclohexane. Preferred aliphatic diisocyanates are l,6-diisocyanato-2,2,4-trimethylhexane, l,6-diisocyanato-2,4,4-trimethyl- hexane and lysine diisocyanate. The difunctionality of the isocyanate allows the prepolymer to grow linearly when polyols react with diisocyanate. The at least one difunctional isocyanate is added to the composition in an amount in a range between approximately 10 wt.-% and approximately 30 wt.-%, referring to the total amount of the mixture, further preferably in a range between approximately 12 wt.-% and approximately 27 wt.-%, and even more preferably in a range between approximately 15 wt.-% and approximately 25 wt.-%. The isocyanate is bifunctional in order to form a linear prepolymer. The active hydrogen in at least one polyol reacts with the at least one isocyanate, so that the at least one isocyanate is chemically bonded via covalent bonds to the at least one. The at least one isocyanate has preferably a viscosity at 25°C, measured in accordance with DIN EN ISO 3219/A.3 - 1994:10, in a range of approximately 1 mPas to approximately 1000 mPas, and further preferably in a range of approximately 1 mPas to approximately 900 mPas. The density of the at least one isocyanate at 20°C, measured in accordance with DIN EN ISO 2811 - 2016:1, is preferably in a range of approximately 0,8 g/ cm ³ to approximately 1,2 g/ cm ³ , and further preferably in a range of approximately 1,0 g/ cm ³ to approximately 1,1 g/ cm ³ . The used excess of the at least one isocyanate depends on the calculated free isocyanate-value calculated via the theoretical NCO value as set forth before. The theoretical NCO value of the at least one isocyanate is in a range of approximately 7,5 wt.-% to approximately 55 wt.-%, and preferably in a range of approximately 10,5 wt.-% to approximately 50 wt.-%, in each case referred to the total amount of the at least one isocyanate molecule.

The theoretical NCO value is calculated by the following formula: wherein the sum of all equivalents of OH containing components Equ _0H are subtracted from the sum of all equivalents of NCO containing components Equ _NC o- The mass _pr ep _O iymer is the mass of the isocyanate-terminated polyurethane prepolymer. M _NC0 is the molecular weight of the isocyanate functional group.

At least one modifier is preferably added in the composition. The at least one modifier is preferably added in an amount in a range between approximately 2 wt.-% and approximately 9 wt.-%, referring to the total amount of the mixture, further preferably in a range between approximately 3 wt.-% and approximately 8 wt.-%, and even more preferably in a range between approximately 4 wt.-% and approximately 7 wt.-%. The at least one modifier is preferably added in an amount in a range between approximately 2,5 wt.-% and approximately 11 wt.-%, referring to the total amount of the composition further preferably in a range between approximately 3 wt.-% and approximately 8 wt.-%, and even more preferably in a range between approximately 9 wt.-% and approximately 10 wt.-%. The at least one modifier preferably comprises at least two hydroxy groups and at least one carboxy acid group. The at least one modifier is preferably dimethylol propionic acid (also called Bis-MPA or DMPA). The dimethylol propionic acid contains two hydroxy groups and a carboxylic acid group. The hydroxy groups react with the isocyanate groups and a functional carboxy acid group stay available. The at least one functional group carboxy acid groups is negatively charged by at least one neutralization agent in the further treatment, as defined below.

At least one neutralization agent is preferably added to the mixture. The at least one neutralization agent can react with the at least one modifier. Preferably, the at least one neutralization agent is selected from a group comprising tertiary amines, amino alcohols, metal hydroxides, ammonia or a mixture thereof. Examples of neutralizing agents are trialkyl amines such as trimethylamine, triethyl amine and tributyl amine; amino alcohols such as dimethyl ethanolamine; tertiary amine compounds such as N-alkyl-N,N-dialkanol amines and tri- ethanol amine; basic compounds such as ammonia, trimethyl ammonium hydroxide, sodium hydroxide, potassium hydroxide and lithium hydroxide. The at least one neutralization agent is preferably triethylamine. Triethylamine reacts with the carboxylic acid of the modifier. The at least one neutralization agent is preferably added in an amount in a range between approximately 1 wt.-% and approximately 8 wt.-%, referring to the total amount of the mixture, further preferably in a range between approximately 2 wt.-% and approximately 7 wt.- %, and even more preferably in a range between approximately 3 wt.-% and approximately 6 wt.-%.

The composition is preferably heated to a first temperature in a range between approximately 60°C and approximately 180°C, further preferably in a range between approximately 70°C and approximately 160°C, and even more preferably in a range between approximately 80°C and approximately 120°C.

The mixture is preferably heated to a second temperature in a range between approximately 60°C and approximately 180°C, further preferably in a range between approximately 70°C and approximately 160°C, and even more preferably in a range between approximately 80°C and approximately 120°C.

The addition of at least one neutralization agent is preferably realised after cooling of the mixture. The addition of at least one is preferably heated to a third temperature in a range between approximately 60°C and approximately 100°C, further preferably in a range between approximately 70°C and approximately 90°C.

The forming of the polyurethane is preferably realized under agitation, further preferably under stirring. The forming of the polyurethane is preferably realized in a round bottom flask. The forming of the polyurethane is preferably realized with a dropwise addition of compounds.

Steps of the forming of the polyurethane can be repeated completely or partially.

The isocyanate-terminated polyurethane prepolymer is preferably obtained by a solvent- free reaction. Solvent free reaction is favorable to avoid secondary reactions, e.g. the reaction of an isocyanate group with water with an emission of CO ₂ . Preferably, the compounds of the mixture are all solvent free.

The reaction is preferably carried out at normal pressure. The reaction is preferably carried out without an inert atmosphere.

The isocyanate-terminated polyurethane prepolymer is preferably linear. The isocyanate-ter- minated polyurethane prepolymer is preferably unbranched. The isocyanate-terminated polyurethane prepolymer is preferably linear and unbranched. The linearity of the prepolymer is advantageously for the process for manufacturing an isocyanate-terminated polyurethane prepolymer. The viscosity of linear polymers is not so high than the viscosity of drafted, branched or crosslinked polymers having a similar molecular weight. A polymerisation cannot happen without solvent if the viscosity is too high. The isocyanate-terminated polyurethane prepolymer has an ethylene oxide content in a range between approximately 1 wt.-% and approximately 15 wt.-%, referring to the total amount of the prepolymer, preferably in a range between approximately 4 wt.-% and approximately 10 wt.-%. The isocyanate- terminated polyurethane prepolymer has preferably a ratio NCO/OH in a range between approximately 1,1:1 and approximately 2:1, further preferably in a range between approximately 1,2:1 and approximately 1,9:1, and even more preferably in a range between approximately 1,3:1 and approximately 1,8:1. This means that more terminations of the prepolymer are isocyanate groups than alcohol groups. The term "NCO/ OH ratio" defines the ratio between the sum up of isocyanate functional groups (NCO) of all used components to the sum up of hydroxy functional groups (OH) of all used components in the synthesis of the isocyanate-terminated polyurethane prepolymer. The ratio of NCO/ OH indicates the excess of free NCO groups after the synthesis of the isocyanate-terminated polyurethane prepolymer, which indicates if an isocyanate-terminated polyurethane is formed in the following synthesis. The ratio NCO/ OH is defined by the sum of all equivalents of isocyanate-containing compounds per the sum of all equivalents of hydroxy-containing compounds. The equivalent weight (EquW) defines the weight of a compound per reactive site: Molecular weight (M )

Equivalent Weiqht {EquW ) = - - - - - - (2) v Functionality wherein x is the compound containing the reactive site. Since polyols have a molecular weight distribution, an average equivalent weight is calculated. These calculations are done by using the product analyzed hydroxyl (OH) content and acid number:

M _x x 1000 Equivalent Weiqht [ \Eq -1uW _X ) = 7 Q77 — _ - - _um b : -er + - - _aci 7 _c 7i - numb : —er (3)

For most polyols in use, the acid number is very low and may be omitted. If the acid number is larger than about 1.0, it should be factored into the above equation (2). The equivalents (Equ) are defined by the mass per equivalent weight (3).

A prepolymer to water weight ratio between approximately 1:4 and approximately 2:1 is preferably applied, further preferably between approximately 1:3 and approximately 1,5:1. The water can preferably be tap water or deionized water. Deionized water is water without the salts found in spring and tap water, dissolved as anions and cations, and is used in chemistry and biology as a solvent and sometimes also as a cleaning agent. In water the iso- cyanate-terminated polyurethane is dispersed. Preferably the at least one modifier and the at least one neutralization agent, which reacted, form a salt which is water soluble. The prepolymer is used in a range of approximately 19 wt-% to approximately 66 wt-%, referring to the total amount of the polyurethane dispersion, further preferably in a range of approximately 24 wt-% to approximately 61 wt-%, and even more preferably in a range of approximately 29 wt-% to approximately 56 wt-%. Water is used in a range of approximately 33 wt-% to approximately 80 wt-%, referring to the total amount of the polyurethane dispersion, further preferably in a range of approximately 38 wt-% to approximately 75 wt-%, and even more in a range of approximately 43 wt-% to approximately 70 wt-%.

The at least one isocyanate-terminated polyurethane prepolymer mixture reacts with the at least one chain extension agent. Chain extension agents are low molecular weight multifunctional compounds that react with the isocyanate groups of diisocyanates. The at least one chain extension agent is further preferably selected from a group comprising alcohols and amines. Amines contain the reactive amino group, which, upon reaction with the isocyanate group, yield an urea. The at least one chain extension agent is preferably selected from a group comprising diamines. The at least one chain extension agent is further preferably selected from a group comprising primary and secondary diamines. The at least one chain extension agent is further preferably selected from a group comprising, ethylenediamine, butanediamine, hexamethylenediamine, hydrazine, hydrazine hydrate, hexamethylen-l,6-di- amin, 2,4-diaminotoluol, diphenylmethan-4,4'-diamin, isophorondiamin, but is not restricted to the mentioned agents. The reaction between the at least one chain extension agent and the at least one difunctional isocyanate creates a linear chain. The purity of the at least one chain extension agent is preferably above 97 %. The at least one chain extension agent is used in a range of approximately 0,3 wt-% to approximately 5 wt-%, referring to the total amount of the polyurethane dispersion, further preferably in a range of approximately 0,5 wt-% to approximately 4,5 wt-%, and more preferably in a range of approximately 0,8 wt-% to approximately 4 wt-%.

The process for manufacturing an aqueous polyurethane dispersion is preferably realized without any surfactant.

The process for manufacturing an aqueous polyurethane dispersion is preferably realized under agitation, further preferably under stirring. The dispersing of the at least of polyurethane prepolymer in an aqueous phase, preferably in water, or the adding water to the at least one polyurethane prepolymer is preferably realized at a temperature in a range between approximately 20°C and approximately 100°C, further preferably in a range between approximately 25°C and approximately 80°C. The adding of the at least one polyurethane prepolymer mixture with at least one chain extension agent is preferably realized at a temperature in a range between approximately 20°C and approximately 100°C, further preferably in a range between approximately 25°C and approximately 80°C.

The present invention further relates to an aqueous polyurethane dispersion obtained in ac- cordance with the process as described above.

The polyurethane dispersion has preferably a non-volatile content in a range between approximately 10 wt.-% and approximately 40wt.-%, further preferably in a range between approximately 15 wt.-% and approximately 35 wt.-%. The non-volatile content gives the wt.-% of the inventive isocyanate-terminated polyurethane prepolymer. The non-volative content is calculated as follows: mdry non - volatile content [wt - %] ■ 100% (5) mwet wherein m _wet is the weight before and m _dry is the weight after heating the sample of the inventive polyurethane dispersion.

The polyurethane dispersion has preferably a viscosity at 20°C, when measured with a Brookfield DV2T EXTRA™ Viscosimeter with a rotational frequency of 5 to 150 rpm and a spindle 2 and spindle 7 of RV EZ-Lock Spindle Set, according to DIN EN ISO 2884-2, dated September2006, in a range between approximately 80 mPas and approximately 140 mPas, further preferably between approximately 87 mPas and approximately 128 Pas.

The present invention further relates to an use of an aqueous polyurethane dispersion obtained in accordance with the process as described above in paints, lacquers, intumescent coatings, on wood, leather, and/or paper.

The present invention further relates to a polyurethane film obtained from an aqueous polyurethane dispersion. The film is preferably obtained by drying of the dispersion.

The polyurethane film has preferably an elongation according to DIN 53504:2017-03 in a range between approximately 900 % and approximately 2000%, further preferably in a range between approximately 1100 % and approximately 1800%, and more preferably in a range between approximately 1300 % and approximately 1600%. The elongation of the isocyanate terminates polyurethane prepolymer shows the elasticity of the prepolymer. It can be explained by the long und linear chains of the prepolymer.

The polyurethane film has preferably a tensile strength according to DIN 53504:2017-03 in a range between approximately 5 MPa and approximately 20 MPa, further preferably in a range between approximately 8 MPa and approximately 17 MPa, and more preferably in a range between approximately 10 MPa and approximately 15 MPa. The tensile strength is the maximum stress that a material can withstand while being stretched or pulled before breaking. The isocyanate-terminated polyurethane prepolymer shows a good withstand. It can be explained by the possibility of plastic deformation of the long chains of the prepolymer.

The polyurethane film is preferably a thermoplastic elastomers (TPE).

In a preferred embodiment of the present invention, the process for manufacturing an aqueous polyurethane dispersion, the process comprising

- forming an at least one isocyanate-terminated polyurethane prepolymer, wherein a composition is provided comprising at least one compound selected from a group of at least one polyol, wherein the composition has an ethylene oxide content of approximately 2 wt.-%, preferably of approximately 8 wt.-%, further preferably of approximately 12 wt.-%, to approximately 20 wt.%, referred to the total amount of the composition, and wherein a mixture is obtained by mixing the composition with at least one difunctional isocyanate,

- dispersing the at least one isocyanate-terminated polyurethane prepolymer obtained in an aqueous phase or adding water to the at least one isocyanate-terminated polyurethane prepolymer, and

- reacting the at least one isocyanate-terminated polyurethane prepolymer mixture with at least one chain extension agent to obtain the aqueous polyurethane dispersion, wherein a prepolymer to water weight ratio between approximately 1:4 and approximately 2:1 is applied.

In a preferred embodiment of the present invention, the process for manufacturing an aqueous polyurethane dispersion, the process comprising

- forming an at least one isocyanate-terminated polyurethane prepolymer, wherein a com- position is provided comprising at least one compound selected from a group of at least one polyol, wherein the composition has an ethylene oxide content of approximately 2 wt.-%, preferably of approximately 8 wt.-%, further preferably of approximately 12 wt.-%, to approximately 20 wt.%, referred to the total amount of the composition, and wherein a mixture is obtained by mixing the composition with at least one difunctional isocyanate,

- dispersing the at least one isocyanate-terminated polyurethane prepolymer obtained in an aqueous phase or adding water to the at least one isocyanate-terminated polyurethane prepolymer, and

- reacting the at least one isocyanate-terminated polyurethane prepolymer mixture with at least one chain extension agent to obtain the aqueous polyurethane dispersion, wherein a prepolymer to water weight ratio between approximately 1:4 and approximately 2:1 is applied, and wherein at least one polyol providing the ethylene oxide content has preferably a degree of unsaturation in a range of approximately 0,001 mEq/g to approximately 0,05 mEq/g, measured according to ASTM D4671-16, method A, further preferred in a range of approximately 0,005 mEq/g to approximately 0,04 mEq/g, and especially preferably in a range of approximately 0,01 mEq/g to approximately 0,03 mEq/g.

In a further preferred embodiment of the present invention, the process for manufacturing an aqueous polyurethane dispersion, the process comprising

- forming an at least one isocyanate-terminated polyurethane prepolymer, wherein a composition is provided comprising at least one compound selected from a group of at least one polyol, wherein the composition has an ethylene oxide content of approximately 2 wt.-%, preferably of approximately 8 wt.-%, further preferably of approximately 12 wt.-%, to approximately 20 wt.%, referred to the total amount of the composition, and wherein a mixture is obtained by mixing the composition with at least one difunctional isocyanate,

- dispersing the at least one isocyanate-terminated polyurethane prepolymer obtained in an aqueous phase or adding water to the at least one isocyanate-terminated polyurethane prepolymer, and

- reacting the at least one isocyanate-terminated polyurethane prepolymer mixture with at least one chain extension agent to obtain the aqueous polyurethane dispersion, wherein the at least one chain extension agent is selected from a group comprising di- amines.

In a further preferred embodiment of the present invention, the process for manufacturing an aqueous polyurethane dispersion, the process comprising

- forming an at least one isocyanate-terminated polyurethane prepolymer, wherein a composition is provided comprising at least one compound selected from a group of at least one polyol, wherein the composition has an ethylene oxide content of approximately 2 wt.-%, preferably of approximately 8 wt.-%, further preferably of approximately 12 wt.-%, to approximately 20 wt.%, referred to the total amount of the composition, and wherein a mixture is obtained by mixing the composition with at least one difunctional isocyanate,

- dispersing the at least one isocyanate-terminated polyurethane prepolymer obtained in an aqueous phase or adding water to the at least one isocyanate-terminated polyurethane prepolymer, and

- reacting the at least one isocyanate-terminated polyurethane prepolymer mixture with at least one chain extension agent to obtain the aqueous polyurethane dispersion, wherein the at least one polyol has a weight average molecular weight M _w in a range of approximately 4000 g/mol, preferably of approximately 6000 g/mol, to approximately 25.000 g/mol.

In a further preferred embodiment of the present invention, the process for manufacturing an aqueous polyurethane dispersion, the process comprising

- forming an at least one isocyanate-terminated polyurethane prepolymer, wherein a composition is provided comprising at least one compound selected from a group of at least one polyol, wherein the composition has an ethylene oxide content of approximately 2 wt.-%, preferably of approximately 8 wt.-%, further preferably of approximately 12 wt.-%, to approximately 20 wt.%, referred to the total amount of the composition, and wherein a mixture is obtained by mixing the composition with at least one difunctional isocyanate,

- dispersing the at least one isocyanate-terminated polyurethane prepolymer obtained in an aqueous phase or adding water to the at least one isocyanate-terminated polyurethane prepolymer, and

- reacting the at least one isocyanate-terminated polyurethane prepolymer mixture with at least one chain extension agent to obtain the aqueous polyurethane dispersion, wherein at least one polyol has a weight average molecular weight M _w in a range of approxi- mately 4000 g/mol, preferably of approximately 6000 g/mol, to approximately 25.000 g/mol, and wherein at least one polyol providing the ethylene oxide content has preferably a degree of unsaturation in a range of approximately 0,001 mEq/g to approximately 0,05 mEq/g, measured according to ASTM D4671-16, method A, further preferred in a range of approximately 0,005 mEq/g to approximately 0,04 mEq/g, and especially preferably in a range of approximately 0,01 mEq/g to approximately 0,03 mEq/g.

In a further preferred embodiment of the present invention, the process for manufacturing an aqueous polyurethane dispersion, the process comprising

- forming an at least one isocyanate-terminated polyurethane prepolymer, wherein a composition is provided comprising at least one compound selected from a group of at least one polyol, wherein the composition has an ethylene oxide content of approximately 2 wt.-%, preferably of approximately 8 wt.-%, further preferably of approximately 12 wt.-%, to approximately 20 wt.%, referred to the total amount of the composition, and wherein a mixture is obtained by mixing the composition with at least one difunctional isocyanate,

- dispersing the at least one isocyanate-terminated polyurethane prepolymer obtained in an aqueous phase or adding water to the at least one isocyanate-terminated polyurethane prepolymer, and

- reacting the at least one isocyanate-terminated polyurethane prepolymer mixture with at least one chain extension agent to obtain the aqueous polyurethane dispersion, wherein at least one polyol providing the ethylene oxide content has preferably a degree of unsaturation in a range of approximately 0,001 mEq/g to approximately 0,05 mEq/g, measured according to ASTM D4671-16, method A, further preferred in a range of approximately 0,005 mEq/g to approximately 0,04 mEq/g, and especially preferably in a range of approximately 0,01 mEq/g to approximately 0,03 mEq/g.

In a further preferred embodiment of the present invention, the process for manufacturing an aqueous polyurethane dispersion, the process comprising

- forming an at least one isocyanate-terminated polyurethane prepolymer, wherein a composition is provided comprising at least one compound selected from a group of at least one polyol, wherein the composition has an ethylene oxide content of approximately 2 wt.-%, preferably of approximately 8 wt.-%, further preferably of approximately 12 wt.-%, to approximately 20 wt.%, referred to the total amount of the composition, and wherein a mixture is obtained by mixing the composition with at least one difunctional isocyanate,

- dispersing the at least one isocyanate-terminated polyurethane prepolymer obtained in an aqueous phase or adding water to the at least one isocyanate-terminated polyurethane prepolymer, and

- reacting the at least one isocyanate-terminated polyurethane prepolymer mixture with at least one chain extension agent to obtain the aqueous polyurethane dispersion, wherein the at least one polyol is a difunctional polyol.

In a further preferred embodiment of the present invention, the process for manufacturing an aqueous polyurethane dispersion, the process comprising

- forming an at least one isocyanate-terminated polyurethane prepolymer, wherein a composition is provided comprising at least one compound selected from a group of at least one polyol, wherein the composition has an ethylene oxide content of approximately 2 wt.-%, preferably of approximately 8 wt.-%, further preferably of approximately 12 wt.-%, to approximately 20 wt.%, referred to the total amount of the composition, and wherein a mixture is obtained by mixing the composition with at least one difunctional isocyanate,

- dispersing the at least one isocyanate-terminated polyurethane prepolymer obtained in an aqueous phase or adding water to the at least one isocyanate-terminated polyurethane prepolymer, and

- reacting the at least one isocyanate-terminated polyurethane prepolymer mixture with at least one chain extension agent to obtain the aqueous polyurethane dispersion, wherein the at least one polyol provide the ethylene oxide content.

In a further preferred embodiment of the present invention, the process for manufacturing an aqueous polyurethane dispersion, the process comprising

- forming an at least one isocyanate-terminated polyurethane prepolymer, wherein a composition is provided comprising at least one compound selected from a group of at least one polyol, wherein the composition has an ethylene oxide content of approximately 2 wt.-%, preferably of approximately 8 wt.-%, further preferably of approximately 12 wt.-%, to approximately 20 wt.%, referred to the total amount of the composition, and wherein a mix- ture is obtained by mixing the composition with at least one difunctional isocyanate,

- dispersing the at least one isocyanate-terminated polyurethane prepolymer obtained in an aqueous phase or adding water to the at least one isocyanate-terminated polyurethane prepolymer, and

- reacting the at least one isocyanate-terminated polyurethane prepolymer mixture with at least one chain extension agent to obtain the aqueous polyurethane dispersion, wherein the at least one polyol is an ethylene oxide endcapped polyol.

In a further preferred embodiment of the present invention, the process for manufacturing an aqueous polyurethane dispersion, the process comprising

- forming an at least one isocyanate-terminated polyurethane prepolymer, wherein a composition is provided comprising at least one compound selected from a group of at least one polyol, wherein the composition has an ethylene oxide content of approximately 2 wt.-%, preferably of approximately 8 wt.-%, further preferably of approximately 12 wt.-%, to approximately 20 wt.%, referred to the total amount of the composition, and wherein a mixture is obtained by mixing the composition with at least one difunctional isocyanate,

- dispersing the at least one isocyanate-terminated polyurethane prepolymer obtained in an aqueous phase or adding water to the at least one isocyanate-terminated polyurethane prepolymer, and

- reacting the at least one isocyanate-terminated polyurethane prepolymer mixture with at least one chain extension agent to obtain the aqueous polyurethane dispersion, wherein the at least one polyol is an ethylene oxide endcapped polyol and wherein at least one polyol providing the ethylene oxide content has preferably a degree of unsaturation in a range of approximately 0,001 mEq/g to approximately 0,05 mEq/g, measured according to ASTM D4671-16, method A, further preferred in a range of approximately 0,005 mEq/g to approximately 0,04 mEq/g, and especially preferably in a range of approximately 0,01 mEq/g to approximately 0,03 mEq/g.

In a further preferred embodiment of the present invention, the process for manufacturing an aqueous polyurethane dispersion, the process comprising

- forming an at least one isocyanate-terminated polyurethane prepolymer, wherein a composition is provided comprising at least one compound selected from a group of at least one polyol, wherein the composition has an ethylene oxide content of approximately 2 wt.-%, preferably of approximately 8 wt.-%, further preferably of approximately 12 wt.-%, to approximately 20 wt.%, referred to the total amount of the composition, and wherein a mixture is obtained by mixing the composition with at least one di-functional isocyanate,

- dispersing the at least one isocyanate-terminated polyurethane prepolymer obtained in an aqueous phase or adding water to the at least one isocyanate-terminated polyurethane prepolymer, and

- reacting the at least one isocyanate-terminated polyurethane prepolymer mixture with at least one chain extension agent to obtain the aqueous polyurethane dispersion, wherein the composition comprises at least one poly(ethylene oxide).

In a further preferred embodiment of the present invention, the process for manufacturing an aqueous polyurethane dispersion, the process comprising

- forming an at least one isocyanate-terminated polyurethane prepolymer, wherein a composition is provided comprising at least one compound selected from a group of at least one polyol, wherein the composition has an ethylene oxide content of approximately 2 wt.-%, preferably of approximately 8 wt.-%, further preferably of approximately 12 wt.-%, to approximately 20 wt.%, referred to the total amount of the composition, and wherein a mixture is obtained by mixing the composition with at least one difunctional isocyanate,

- dispersing the at least one isocyanate-terminated polyurethane prepolymer obtained in an aqueous phase or adding water to the at least one isocyanate-terminated polyurethane prepolymer, and

- reacting the at least one isocyanate-terminated polyurethane prepolymer mixture with at least one chain extension agent to obtain the aqueous polyurethane dispersion, wherein a second polyol provides the ethylene oxide content.

In a further preferred embodiment of the present invention, the process for manufacturing an aqueous polyurethane dispersion, the process comprising

- forming an at least one isocyanate-terminated polyurethane prepolymer, wherein a composition is provided comprising at least one compound selected from a group of at least one polyol, wherein the composition has an ethylene oxide content of approximately 2 wt.-%, preferably of approximately 8 wt.-%, further preferably of approximately 12 wt.-%, to ap- proximately 20 wt.%, referred to the total amount of the composition, and wherein a mixture is obtained by mixing the composition with at least one difunctional isocyanate,

- dispersing the at least one isocyanate-terminated polyurethane prepolymer obtained in an aqueous phase or adding water to the at least one isocyanate-terminated polyurethane prepolymer, and

- reacting the at least one isocyanate-terminated polyurethane prepolymer mixture with at least one chain extension agent to obtain the aqueous polyurethane dispersion, wherein a second polyol is an ethylene oxide endcapped polyol.

In a further preferred embodiment of the present invention, the process for manufacturing an aqueous polyurethane dispersion, the process comprising

- forming an at least one isocyanate-terminated polyurethane prepolymer, wherein a composition is provided comprising at least one compound selected from a group of at least one polyol, wherein the composition has an ethylene oxide content of approximately 2 wt.-%, preferably of approximately 8 wt.-%, further preferably of approximately 12 wt.-%, to approximately 20 wt.%, referred to the total amount of the composition, and wherein a mixture is obtained by mixing the composition with at least one difunctional isocyanate,

- dispersing the at least one isocyanate-terminated polyurethane prepolymer obtained in an aqueous phase or adding water to the at least one isocyanate-terminated polyurethane prepolymer, and

- reacting the at least one isocyanate-terminated polyurethane prepolymer mixture with at least one chain extension agent to obtain the aqueous polyurethane dispersion, wherein at least one first polyol without an ethylene oxide content has a weight average molecular weight M _w in a range of approximately 4000 g/mol, preferably of approximately 6000 g/mol, to approximately 25.000 g/mol, and/or has preferably a degree of unsaturation in a range of approximately 0,001 mEq/g to approximately 0,05 mEq/g, measured according to ASTM D4671-16, method A, further prefered in a range of approximately 0,005 mEq/g to approximately 0,04 mEq/g, and especially preferably in a range of approximately 0,01 mEq/g to approximately 0,03 mEq/g, and wherein a second polyol, being preferably ethylene oxide endcapped, provides the ethylene oxide content. In a further preferred embodiment of the present invention, the process for manufacturing an aqueous polyurethane dispersion, the process comprising

- forming an at least one isocyanate-terminated polyurethane prepolymer, wherein a composition is provided comprising at least one compound selected from a group of at least one polyol, wherein the composition has an ethylene oxide content of approximately 2 wt.-%, preferably of approximately 8 wt.-%, further preferably of approximately 12 wt.-%, to approximately 20 wt.%, referred to the total amount of the composition, and wherein a mixture is obtained by mixing the composition with at least one difunctional isocyanate,

- dispersing the at least one isocyanate-terminated polyurethane prepolymer obtained in an aqueous phase or adding water to the at least one isocyanate-terminated polyurethane prepolymer, and

- reacting the at least one isocyanate-terminated polyurethane prepolymer mixture with at least one chain extension agent to obtain the aqueous polyurethane dispersion, wherein a second polyol, being preferably ethylene oxide endcapped, provides the ethylene oxide content, and wherein at least one first polyol also provides the ethylene oxide content, and has preferably a degree of unsaturation in a range of approximately 0,001 mEq/g to approximately 0,05 mEq/g, measured according to ASTM D4671-16, method A, further prefered in a range of approximately 0,005 mEq/g to approximately 0,04 mEq/g, and especially preferably in a range of approximately 0,01 mEq/g to approximately 0,03 mEq/g.

In a preferred embodiment of the present invention, the process for manufacturing an aqueous polyurethane dispersion, the process comprising

- forming an at least one isocyanate-terminated polyurethane prepolymer, wherein a composition is provided comprising at least one compound selected from a group of at least one polyol, wherein the composition has an ethylene oxide content of approximately 2 wt.-%, preferably of approximately 8 wt.-%, further preferably of approximately 12 wt.-%, to approximately 20 wt.%, referred to the total amount of the composition, and wherein a mixture is obtained by mixing the composition with at least one difunctional isocyanate,

- dispersing the at least one isocyanate-terminated polyurethane prepolymer obtained in an aqueous phase or adding water to the at least one isocyanate-terminated polyurethane pre- 1 polymer, and

- reacting the at least one isocyanate-terminated polyurethane prepolymer mixture with at least one chain extension agent to obtain the aqueous polyurethane dispersion, wherein at least one first polyol without an ethylene oxide content is provided, that has preferably a weight average molecular weight M _w in a range of approximately 4000 g/mol to approximately 25000 g/mol, further preferably in a range of approximately 10000 g/mol to approximately 22000 g/mol, especially preferably in a range of approximately 12000 g/mol to approximately 20000 g/mol, and further preferably in a range of approximately 6000 g/mol to approximately 25000 g/mol, and wherein at least one second polyol with the ethylene oxide content is provided.

In a preferred embodiment of the present invention, the process for manufacturing an aqueous polyurethane dispersion, the process comprising

- forming an at least one isocyanate-terminated polyurethane prepolymer, wherein a composition is provided comprising at least one compound selected from a group of at least one polyol, wherein the composition has an ethylene oxide content of approximately 2 wt.-%, preferably of approximately 8 wt.-%, further preferably of approximately 12 wt.-%, to approximately 20 wt.%, referred to the total amount of the composition, and wherein a mixture is obtained by mixing the composition with at least one difunctional isocyanate,

- dispersing the at least one isocyanate-terminated polyurethane prepolymer obtained in an aqueous phase or adding water to the at least one isocyanate-terminated polyurethane prepolymer, and

- reacting the at least one isocyanate-terminated polyurethane prepolymer mixture with at least one chain extension agent to obtain the aqueous polyurethane dispersion, wherein at least one first polyol without an ethylene oxide content is provided having preferably a degree of unsaturation in a range of approximately 0,001 mEq/g to approximately 0,05 mEq/g, measured according to ASTM D4671-16, method A, further preferred in a range of approximately 0,005 mEq/g to approximately 0,04 mEq/g, and especially preferably in a range of approximately 0,01 mEq/g to approximately 0,03 mEq/g, and wherein at least one second polyol with the ethylene oxide content is provided.

In a preferred embodiment of the present invention, the process for manufacturing an aqueous polyurethane dispersion, the process comprising

- forming an at least one isocyanate-terminated polyurethane prepolymer, wherein a composition is provided comprising at least one compound selected from a group of at least one polyol, wherein the composition has an ethylene oxide content of approximately 2 wt.-%, preferably of approximately 8 wt.-%, further preferably of approximately 12 wt.-%, to approximately 20 wt.%, referred to the total amount of the composition, and wherein a mixture is obtained by mixing the composition with at least one difunctional isocyanate,

- dispersing the at least one isocyanate-terminated polyurethane prepolymer obtained in an aqueous phase or adding water to the at least one isocyanate-terminated polyurethane prepolymer, and

- reacting the at least one isocyanate-terminated polyurethane prepolymer mixture with at least one chain extension agent to obtain the aqueous polyurethane dispersion, wherein at least one first polyol without an ethylene oxide content is provided having preferably a degree of unsaturation in a range of approximately 0,001 mEq/g to approximately 0,05 mEq/g, measured according to ASTM D4671-16, method A, further preferred in a range of approximately 0,005 mEq/g to approximately 0,04 mEq/g, and especially preferably in a range of approximately 0,01 mEq/g to approximately 0,03 mEq/g, and, further, having a weight average molecular weight M _w in a range of approximately 4000 g/mol to approximately 25000 g/mol, further preferably in a range of approximately 10000 g/mol to approximately 22000 g/mol, especially preferably in a range of approximately 12000 g/mol to approximately 20000 g/mol, and further preferably in a range of approximately 6000 g/mol to approximately 25000 g/mol, and wherein at least one second polyol with the ethylene oxide content is provided.

The above-mentioned preferred embodiments of the process for manufacturing an aqueous polyurethane dispersion are non-limitative preferred examples whereby different combination of the said ranges and additives are also possible.

The present invention will be hereunder described in more detail with reference to the following non-limiting example in accordance with the present invention of the isocyanate- terminated polyurethane prepolymer and the aqueous polyurethane dispersion, the use of the isocyanate- terminated polyurethane prepolymer in the inventive process to manufacture the aqueous polyurethane dispersion and the use of the aqueous polyurethane dispersion as an example.

The following compounds were used in the preparation of the composition of example 1 to example 3 and the comparative example A. The methods for the tests are described below. Test results of these shown in Table 1.

A non-ethoxylated polyether diol with an average molecular weight of approximately 4000 g/mol, with a maximum unsaturation of 0,05 meq/g according to ASTM D4671-16, method A, and a hydroxy number of approximately 26-29 obtainable as Rokopol LDB Delta 4000, available from PCC Rokita, 56-120 Brzeg Dolny, Sienkiewicza 4, Poland, was used. A nonethoxylated polyether diol with an average molecular weight of approximately 8000 g/mol, with a maximum unsaturation of 0,05 meq/g according to ASTM D4671-16, method A, and a hydroxy number of approximately 13-15 obtainable as Rokopol LDB8000D, available from PCC Rokita, 56-120 Brzeg Dolny, Sienkiewicza 4, Poland, was used. A non-ethoxylated polyether diol with an average molecular weight of approximately 12000 g/mol, with a maximum unsaturation of 0,05 meq/g according to ASTM D4671-16, method A, and a hydroxy number of approximately 9-11 obtainable as Rokopol LDB Delta 12000, available from PCC Rokita, 56-120 Brzeg Dolny, Sienkiewicza 4, Poland, was used. A non-ethoxylated polyether diol with an average molecular weight of approximately 18000 g/mol, a maximum unsaturation of 0,01 meq/g according to ASTM D4671-16, method A, and a hydroxy number of approximately 5-7 obtainable as Rokopol LDB18000D, available from PCC Rokita, 56-120 Brzeg Dolny, Sienkiewicza 4, Poland, was used. Polyethoxylated propyleneglycol diol, being ethylene oxide-endcapped, with an average molecular weight of approximately 4000 g/mol, an ethylene oxide content of 20 wt.-%, referred to the total amount of the diol, and a hydroxy number of approximately 29 obtainable as Rokopol DE4020 available from PCC Rokita, 56- 120 Brzeg Dolny, Sienkiewicza 4, Poland, was used. Dimethylol propionic acid powder having a purity of approximately 95-100% and with a molecular weight of 134 g/mol from Perstrop Specialty Chemicals AB, Industriparken, 284 80 Perstorp, Sweden, was used. Triethylamine with a purity of approximately 99 % from Taminco Germany GmbH, Am Haupttor 8314, 06237 Leunal, Germany, was used. Ethylene diamine with a purity of approximately 99 % from Akzo Nobel was used. Isophorone diisocyanate obtainable as Vestanat IPDI from Evonik Resource Efficiency GmbH, Paul-Baumann- Str. 1, 45764 Marl, Germany, was used. Isophorone diisocyanate with a NCO value of >37,8% and a molecular weight of 222,28 g/mol obtainable as Desmodur® I from Covestro AG, Kaiser-Wilhelm-Allee 60, 51373 Leverkusen, Germany, was used.

Example 1

60,56 g of Rokopol DE4020, 59,8 g Rokopol LDB Delta 12000, and 9,19 g of dimethylol propionic acid (Bis-MPA) were charged into a round bottom flask equipped with a thermometer, a mechanical stirrer and a condenser. The composition of the polyols, namely of 60,56 g of Rokopol DE4020, and of 59,8 g Rokopol LDB Delta 12000, had an ethylene oxide content of approximately 10 wt.-%, referred to the total amount of the composition. The mixture was heated up to 120°C under good agitation. 33,47g of isophorone diisocyante were added at 120°C under stirring. The reaction mixture was stirred for 10 minutes. After cooling down to 80°C, 7,66 g of triethylamine was added dropwise at 80°C for neutralization of the reaction mixture and the temperature was maintained for 10 minutes. 290 g water was added to the warm prepolymer to obtain a dispersion 25/75 of prepolymer/water. A white, low viscous dispersion was formed and stirred for 10 min with a mechanical stirrer. The chain extension was performed by adding 2,94 g EDA (diluted in 31,2 g water) dropwise with mechanical stirrer. After stirring for three hours at 40°C, the dispersion was filtrated through a filter cloth with a mesh size of approximately 400 pm. No coagulum was observed on the filter.

The aqueous polyurethane dispersion was filled in a shallow vessel with rim and dried at normal conditions (23°C, 50% humidity) for seven days. A film was formed and then removed from the vessel.

Example 2

30,11 g of Rokopol DE4020, 60,46 g Rokopol LDB Delta 12000, and 4,61 g of dimethylol propionic acid (Bis-MPA) were charged into a round bottom flask equipped with a thermometer, a mechanical stirrer and a condenser. The mixture was heated up to 80°C under good agitation. 33,41 g of isophorone diisocyante were added at 80°C under stirring. The reaction mixture was stirred for one hour. The desired theoretical NCO value of 6,715 wt.-% was determined by the di-n-butylamine titration according ISO 14896: 2009-07 method A. The experi- mental NCO value of the reaction mixture was 7,694 wt.-% measured by the previous described method. Additional 30,91 g of Rokopol DE4020 and 4,62 g of dimethylol propionic acid (Bis-MPA) were added to the reaction mixture. The composition of the polyols, namely of 30,11 g plus 30,91g of Rokopol DE4020, and of 60,46 g Rokopol LDB Delta 12000, had an ethylene oxide content of approximately 10 wt.-%, referred to the total amount of the composition. The reaction mixture was stirred for one additional 90 minutes. The desired theoretical NCO value of 3,162 wt.-% was determined by the di-n-butylamine titration according ISO 14896: 2009-07 method A. The experimental NCO value of the reaction mixture was 3,457 wt.-% measured by the previous described method. After reaching the desired NCO value, 7,72 g of triethylamine was added dropwise at 80°C for neutralization of the reaction mixture and the temperature was maintained for 10 minutes. 462,1 g water was added to the warm prepolymer to obtain a dispersion 25/75 of prepolymer/water. A white, low viscous dispersion was formed and stirred for 10 min with a mechanical stirrer. The chain extension was performed by adding 2,94 g EDA (diluted in 31,2 g water) dropwise with mechanical stirrer. After stirring for three hours at 40°C, the dispersion was filtrated through a filter cloth with a mesh size of approximately 400 pm. No coagulum was observed on the filter.

The aqueous polyurethane dispersion was filled in a shallow vessel with rim and dried at normal conditions (23°C, 50% humidity) for seven days. A film was formed and then removed from the vessel.

Example 3

60,15 g of Rokopol DE4020, 61,36 g Rokopol LDB Delta 4000, and 9,18 g of dimethylol propionic acid (Bis-MPA) were charged into a round bottom flask equipped with a thermometer, a mechanical stirrer and a condenser. The composition of the polyols, namely of 60,15 g of Rokopol DE4020, and of 61,36 g Rokopol LDB Delta 12000, had an ethylene oxide content of approximately 10 wt.-%, referred to the total amount of the composition. The mixture was heated up to 120°C under good agitation. 33,37 g of isophorone diisocyante were added at 120°C under stirring. The reaction mixture was stirred for 10 minutes. The desired theoretical NCO value of 2,64 % was determined by the di-n-butylamine titration according ISO 14896: 2009-07 method A. The experimental NCO value of the reaction mixture was 2,74 % measured by the previous described method. After cooling down to 80°C, 7,65 g of triethyl- amine was added dropwise at 80°C for neutralization of the reaction mixture and the temperature was maintained for 10 minutes. 321 g water was added to the warm prepolymer to obtain a dispersion 30/70 of Prepolymer/water. A white, low viscous dispersion was formed and stirred for 10 min with a mechanical stirrer. The chain extension was performed by adding 2,52 g EDA (diluted in 31,2 g water) dropwise with mechanical stirrer. After stirring for three hours at 40°C, the dispersion was filtrated through a filter cloth with a mesh size of approximately 400 pm. No coagulum was observed on the filter.

The aqueous polyurethane dispersion was filled in a shallow vessel with rim and dried at normal conditions (23°C, 50% humidity) for seven days. A film was formed and then removed from the vessel.

Comparative Example A

60,0 g of Rokopol LDB 4000D, 60,0 g Rokopol LDB Delta 12000, and 9,2 g of dimethylol propionic acid (Bis-MPA) were charged into a round bottom flask equipped with a thermometer, a mechanical stirrer and a condenser. The composition of the polyols, namely of 60,0 g of Rokopol LDB 4000D, and of 60,0 g Rokopol LDB Delta 12000 had no ethylene oxide content. The mixture was heated up to 120°C under good agitation. 33,4 g of isophorone diisocyante were added at 120°C under stirring. The reaction mixture was stirred for 10 minutes. After cooling down to 80°C, 7,64 g of triethylamine was added dropwise at 80°C for neutralization of the reaction mixture and the temperature was maintained for 10 minutes. 290 g water was added to the warm prepolymer to obtain a dispersion 25/75 of prepolymer/water. The prepolymer was not stable in water and precipitates (two phase separation).

The following methods were used for testing of the composition of example 1 to example 3, and of comparative example A.

The pH value was detected with a pH meter set model pH50+DHS - COND51+ - PC52+DHS at 50°C. The products ware measured with a dilution of 1:9 in water. The Calibration standards were a pH buffer solution with a pH of 4,01 ± 0,02 at 25°C and a pH buffer solution with a pH of 7, 00 ± 0,02 at 25°C. The viscosity was measured with a Brookfield DV2T EXTRA™ Viscometer according to DIN EN ISO 2884-2, dated September2006. The viscosity was measured between 20°C and 30°C (depending on PP or PUD) with rotational frequency of 5 to 150 rpm and the spindle 2 and spindle 7 of the RV EZ-Lock. The non-volatile content, also known as active content, was measured with a Sartorius balance. 0,5 to 2,0 g of the inventive prepolymer was poured on a filter paper made of Fiber Glass Filter and a diameter of 90mm in a disposable aluminum Sample Pan with a diameter of 90 mm and a height of 7 mm and heated to 120°C for 30 min. The weight before m _wet and the weight after heating m _dry was detected. Elongation and tensile strength of polyurethane films were measured according to DIN 53504:2017-03 with Shimatzu universal testing machine AG-X plus (Extensiometer for determination of elongation at break, pneumatic clamping jaws with rubber coating, lkN load cell, S2 test rod).

Test results of these shown in Table 1.

Table 1 : Experimental results

The prepolymer of the comparative example A did not have an ethylene oxide content, contrary to the prepolymers of examples 1, 2 and 3, which have an ethylene oxide content of approximately 7,38 wt.-%, referred to the total amount of the prepolymer. The prepolymer of the comparative example A was not stable in water and precipitates. An ethylene oxide content of approximately 2 wt.-% to approximately 20 wt.%, referred to the total amount of the composition of polyols, provides stability. This stability is due to hydrogen bonds that the oxygen of the ethylene oxide groups can build with water.

The combination of polyols providing an ethylene oxide content, long-chain polyols and/or low unsaturation leads to high elasticity and tear strength of the polyurethane film without the use of higher-functional polyols or the use of other additives.