Highly-phase-separated polyurethane emulsion as well as preparation method and application thereof

Abstract

The invention provides a high-phase-separation polyurethane emulsion as well as a preparation method and application thereof, and belongs to the technical field of polymer materials, the high-phase-separation polyurethane emulsion comprises the following components in parts by weight: 18-42 parts of linear polyurethane oligomer, 30-50 parts of polymer dihydric alcohol, 3-7 parts of hydrophilic chain extender, 2-5.5 parts of neutralizer and 0.1-0.5 part of catalyst, the linear polyurethane oligomer is prepared from the following raw materials: a diisocyanate monomer and micromolecular dihydric alcohol, and the molar ratio of the micromolecular dihydric alcohol to the diisocyanate monomer is (0.50-0.69): 1. A polyurethane adhesive film prepared from the polyurethane emulsion provided by the invention has high phase separation property and excellent mechanical property, water resistance and thermal stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and specifically relates to a highly phase-separated polyurethane emulsion, a preparation method and application thereof, and in particular to a highly phase-separated polyurethane emulsion, a preparation method and application thereof, and a polyurethane film with a phase-separated structure. Background Art

[0002] Waterborne polyurethane (WPU) is a type of polyurethane dispersion using water as the dispersion medium. It combines the excellent flexibility, adhesion, and abrasion resistance of polyurethane materials with the environmental friendliness, low toxicity, and low VOC (Volatile Organic Compound) emissions of waterborne systems. It is widely used in a variety of applications, including coatings, adhesives, textile coatings, synthetic leather, and inks. With increasingly stringent environmental regulations and the growing demand for sustainable materials, WPU has become a key alternative to solvent-based polyurethane, and its market demand and technological value continue to grow.

[0003] The ultimate performance of WPU depends largely on its microphase structure, particularly the degree of microphase separation between the soft and hard segments. This microphase separation directly impacts key performance indicators of the coating, such as mechanical strength, elasticity, water resistance, and heat resistance. An ideal WPU should possess a distinct phase separation structure, forming a continuous, flexible soft segment phase and highly aggregated hard segment microdomains. This enhances rigidity and durability while maintaining flexibility.

[0004] However, the traditional WPU synthesis process primarily utilizes a two-step process: first, an isocyanate reacts with a polyether or polyester polyol to form an NCO-terminated prepolymer. A small molecule chain extender is then added to extend the chain and introduce hydrophilic groups to achieve dispersion in water. During this process, the small molecule chain extender can only connect two or a limited number of prepolymer segments. The resulting hard segment structure is typically composed of a difunctional isocyanate and a low-molecular-weight chain extender (such as 1,4-butanediol or ethylenediamine). These hard segments are short and poorly regularized, making it difficult to form ordered, aggregated microdomains. Consequently, hydrogen bonding and van der Waals forces between the hard segments are not fully utilized, resulting in insufficient microphase separation.

[0005] Therefore, there is an urgent need to develop a phase-separated polyurethane material that can effectively improve the hard segment chain length and aggregation ability, thereby enhancing the degree of WPU phase separation, so as to further improve the comprehensive performance of waterborne polyurethane materials and meet the dual needs of environmental protection and functionality in high-end application fields. Summary of the Invention

[0006] In view of the deficiencies in the prior art, the present invention aims to provide a highly phase-separated polyurethane emulsion and a preparation method and application thereof.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In one aspect, the present invention provides a highly phase-separated polyurethane emulsion comprising, in parts by weight:

[0009] 18-42 parts of linear polyurethane oligomer, 30-50 parts of polymer diol, 3-7 parts of hydrophilic chain extender, 2-5.5 parts of neutralizer and 0.1-0.5 parts of catalyst, wherein:

[0010] The raw materials for preparing the linear polyurethane oligomer include diisocyanate monomers and small molecule diols, and the molar ratio of the small molecule diols to the diisocyanate monomers is (0.50-0.69):1, for example, 0.50:1, 0.52:1, 0.54:1, 0.55:1, 0.56:1, 0.58:1, 0.60:1, 0.62:1, 0.64:1, 0.65:1, 0.67:1, 0.69:1, etc.

[0011] Compared to the existing technology that uses small molecule chain extenders to connect NCO-terminated prepolymers, the hard segment can only be composed of short chain extenders and difunctional isocyanates, making it difficult to form continuous, regular hard segment microdomains with strong aggregation ability. The polyurethane emulsion provided by the present invention can make the resulting polyurethane film have a high degree of phase separation. Specifically:

[0012] The present invention uses linear polyurethane oligomers as hard segments. The molecular chains of linear polyurethane oligomers are long and regular, and have strong aggregation ability, thereby improving the microphase separation degree of the polyurethane material, so that the final polyurethane film has excellent mechanical properties and water resistance.

[0013] In the present invention, the linear polyurethane oligomer 18-42 parts can be 18 parts, 20 parts, 22 parts, 25 parts, 28 parts, 30 parts, 32 parts, 35 parts, 38 parts, 40 parts, 42 parts, etc., the polymer diol 30-50 parts can be 30 parts, 32 parts, 35 parts, 38 parts, 40 parts, 42 parts, 45 parts, 48 ​​parts, 50 parts, etc., the hydrophilic chain extender 3-7 parts can be 3 parts, 3. The above-mentioned 0.1-0.5 parts can be 0.1 part, 0.15 part, 0.2 part, 0.25 part, 0.3 part, 0.35 part, 0.4 part, 0.45 part, 0.5 part, etc. The above-mentioned 0.1-0.5 parts can be 0.1 part, 0.15 part, 0.2 part, 0.25 part, 0.3 part, 0.35 part, 0.4 part, 0.45 part, 0.5 part, etc. The above-mentioned 0.1-0.5 parts can be 0.1 part, 0.15 part, 0.2 part, 0.25 part, 0.3 part, 0.35 part, 0.4 part, 0.45 part, 0.5 part, etc.

[0014] Preferably, the average degree of polymerization of the linear polyurethane oligomer is 3-5.5, for example, 3, 3.5, 4, 4.5, 5, 5.5, etc.

[0015] When the molar ratio of the small molecule diol and the diisocyanate monomer provided by the present invention is within the specified range of the present invention, the linear polyurethane oligomer can be NCO-terminated, and the average degree of polymerization is 3-5.5, the molecular chain length is relatively suitable, and the final phase separation polyurethane film has better tensile strength and elongation at break, and excellent water resistance.

[0016] If the addition amount of small molecule diol is too low, the degree of polymerization of the obtained linear polyurethane oligomer will be low and the molecular chain length will be short, which will reduce the degree of phase separation of the polyurethane film; if the addition amount of small molecule diol is too high, the molecular chain of the linear polyurethane oligomer will be long, which will increase the brittleness of the polyurethane film and may even cause the end group of the linear polyurethane oligomer to be an OH group, which is not conducive to the subsequent synthesis of polyurethane materials.

[0017] The polyurethane material provided by the present invention provides a new synthetic route, which constructs linear polyurethane oligomers with regular structures in advance as long hard segment structures, and introduces soft segment structures and hydrophilic groups, so that the obtained water-based polyurethane film finally has high phase separation properties.

[0018] Preferably, the diisocyanate monomer includes any one or a combination of at least two of 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, hexamethylene diisocyanate or diphenylmethane diisocyanate.

[0019] Preferably, the small molecule polyol includes any one of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol or 1,6-hexanediol, or a combination of at least two thereof.

[0020] Preferably, the method for preparing the linear polyurethane oligomer comprises:

[0021] The small molecule diol and the diisocyanate monomer are mixed in a molar ratio of (0.50-0.69):1, and a polymerization reaction is carried out under the catalysis of a catalyst to obtain the linear polyurethane oligomer.

[0022] Preferably, the polymerization reaction temperature is 75-80°C, for example, 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, etc., and the polymerization time is 1.5-2 h, for example, 1.5 h, 1.6 h, 1.7 h, 1.8 h, 1.9 h, 2 h, etc.

[0023] Preferably, the relative molecular weight of the polymer diol is 2000-3000, for example, 2000, 2100, 2200, 2300, 2400, 2500, 2600, 2700, 2800, 2900, 3000, etc.

[0024] Preferably, the hydrophilic chain extender comprises 2,2-dimethylolpropionic acid (DMPA) and / or 2-dimethylolbutanoic acid (DMBA).

[0025] Preferably, the neutralizing agent comprises triethylamine.

[0026] Preferably, the catalyst comprises an organometallic catalyst, preferably an organotin catalyst.

[0027] Preferably, the highly phase-separated polyurethane material further comprises 10-50 parts of an organic solvent, which may be 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, etc., and / or 100-300 parts of deionized water, which may be 100 parts, 120 parts, 140 parts, 150 parts, 160 parts, 180 parts, 200 parts, 220 parts, 250 parts, 280 parts, 300 parts, etc.

[0028] Preferably, the organic solvent includes any one of N-methylpyrrolidone (NMP), dimethylformamide (DMF) or acetone, or a combination of at least two thereof.

[0029] In a second aspect, the present invention provides a method for preparing the highly phase-separated polyurethane emulsion according to the first aspect, the preparation method comprising:

[0030] S1. A polymer diol and a linear polyurethane oligomer are polymerized under a catalyst to obtain a prepolymer;

[0031] S2. The prepolymer is subjected to a chain extension reaction with a hydrophilic chain extender. After the reaction, a neutralizing agent and optionally deionized water are added to obtain the highly phase-separated polyurethane emulsion.

[0032] Preferably, in step S1, the polymerization reaction temperature is 70-80°C, for example, 70°C, 71°C, 72°C, 74°C, 75°C, 76°C, 78°C, 80°C, etc., and the time is 1-1.5 h, for example, 1 h, 1.1 h, 1.2 h, 1.3 h, 1.4 h, 1.5 h, etc.

[0033] Preferably, in step S2, the chain extension reaction temperature is 70-80°C, for example, 70°C, 71°C, 72°C, 74°C, 75°C, 76°C, 78°C, 80°C, etc., and the time is 2-3 h, for example, 2 h, 2.1 h, 2.2 h, 2.4 h, 2.5 h, 2.6 h, 2.8 h, 3 h, etc.

[0034] Preferably, in step S2, the temperature for adding the neutralizing agent is 35-45°C, for example, 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 42°C, 44°C, 45°C, etc.

[0035] In some embodiments of the present invention, the method for preparing the highly phase-separated polyurethane emulsion comprises:

[0036] S1. Under a protective atmosphere, polymer diol and linear polyurethane oligomer are polymerized in the presence of a catalyst at 70-80°C for 1-1.5 hours to obtain an NCO-terminated prepolymer.

[0037] S2. After the polymerization reaction, a hydrophilic chain extender pre-dissolved in a solvent is added and the reaction is carried out at 70-80°C for 2-3 hours. After the reaction is completed, the temperature is lowered to 35-45°C and a neutralizing agent is added for neutralization.

[0038] S3. Optionally, after the neutralization reaction is completed, the reaction product is added to deionized water for emulsification and dispersion, preferably the emulsification and dispersion speed is 1500-3000 rpm, for example, 1500 rpm, 1600 rpm, 1800 rpm, 2000 rpm, 2200 rpm, 2500 rpm, 2800 rpm, 3000 rpm, etc., and preferably the emulsification and dispersion time is 20-30 min, for example, 20 min, 22 min, 24 min, 25 min, 26 min, 28 min, 30 min, etc., to obtain a stable emulsified aqueous polyurethane emulsion.

[0039] In a third aspect, the present invention provides a polyurethane film having a phase separation structure, wherein the polyurethane film is prepared by coating and drying the highly phase-separated polyurethane emulsion described in the first aspect.

[0040] The invention dries the emulsion to form a film, and the hard segment and the soft segment can undergo obvious microphase separation, and the obtained polyurethane material has excellent mechanical properties and water resistance.

[0041] In a fourth aspect, the present invention provides a use of the highly phase-separated polyurethane emulsion as described in the first aspect in the preparation of a water-based coating.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The polyurethane film obtained from the polyurethane emulsion provided by the present invention has high phase separation and excellent mechanical properties, water resistance and thermal stability. DETAILED DESCRIPTION

[0044] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0045] Unless otherwise specified, the raw materials involved in the following specific embodiments of the present invention are all conventional materials in the art and can be purchased from commercial products. Some raw material information is as follows:

[0046] Polymer diol 1: PTMG2000, purchased from Mitsubishi;

[0047] Polymer diol 2: polypropylene glycol PPG3000, purchased from Nantong Yixun Chemical;

[0048] Polymer diol 3: polycarbonate diol PCDL 2000, purchased from Shanghai Shuyu Chemical;

[0049] Preparation Example 1

[0050] This preparation example provides a method for preparing a linear polyurethane oligomer, as follows:

[0051] In a four-necked flask equipped with a stirring device, a temperature control system and a nitrogen atmosphere, 45 parts of 1,4-butanediol and 222.3 parts of isophorone diisocyanate (molar ratio of 0.50:1) were mixed, heated to 75°C, and reacted for 2 h under the catalysis of 0.3 parts of dibutyltin dilaurate to obtain a linear polyurethane oligomer with an average degree of polymerization of 3.

[0052] Preparation Example 2

[0053] This preparation example provides a method for preparing a linear polyurethane oligomer.

[0054] The difference from Preparation Example 1 is that in this Preparation Example, the molar ratio of the small molecule diol to the diisocyanate is 0.60:1 by changing the addition amount of 1,4-butanediol, and the average polymerization degree of the obtained linear polyurethane oligomer is 4.

[0055] Preparation Example 3

[0056] This preparation example provides a method for preparing a linear polyurethane oligomer.

[0057] The difference from Preparation Example 1 is that in this Preparation Example, the molar ratio of the small molecule diol to the diisocyanate is 0.67:1 by changing the addition amount of 1,4-butanediol, and the average polymerization degree of the obtained linear polyurethane oligomer is 5.

[0058] Preparation Example 4

[0059] The difference from Preparation Example 1 is that in this comparative preparation example, the molar ratio of the small molecule diol and the diisocyanate is 0.69:1 by changing the addition amount of 1,4-butanediol, and the average polymerization degree of the obtained linear polyurethane oligomer is 5.5.

[0060] Preparation Example 5

[0061] This preparation example provides a method for preparing a linear polyurethane oligomer, as follows:

[0062] In a four-necked flask equipped with a stirring device, a temperature control system and nitrogen protection, 31 parts of ethylene glycol and 262.4 parts of 4,4'-dicyclohexylmethane diisocyanate (H 12 The mixture was mixed with 1,2-dimethyl-2-nitropropene (DMSO) (with a molar ratio of 0.50:1), heated to 75°C, and reacted for 2 h under the catalysis of 0.3 parts of dibutyltin dilaurate to obtain a linear polyurethane oligomer with an average degree of polymerization of 3.

[0063] Comparative Preparation Example 1

[0064] This preparation example provides a method for preparing a linear polyurethane oligomer.

[0065] The difference from Preparation Example 1 is that in this comparative preparation example, the molar ratio of the small molecule diol and the diisocyanate is 0.33:1 by changing the addition amount of 1,4-butanediol, and the average polymerization degree of the obtained linear polyurethane oligomer is 2.

[0066] Comparative Preparation Example 2

[0067] The difference from Preparation Example 1 is that in this comparative preparation example, the molar ratio of the small molecule diol and the diisocyanate is 0.71:1 by changing the addition amount of 1,4-butanediol, and the average polymerization degree of the obtained linear polyurethane oligomer is 6.

[0068] Examples 1-3

[0069] This embodiment provides a highly phase-separated polyurethane emulsion, the composition of which is shown in Table 1:

[0070] Table 1

[0071]

[0072] Note: The linear polyurethane oligomer is provided by Preparation Example 1, and the organotin catalyst is dibutyltin dilaurate.

[0073] The preparation method is:

[0074] S1. Under a protective atmosphere, a polymer diol and a linear polyurethane oligomer are polymerized in the presence of a catalyst to obtain an NCO-terminated prepolymer;

[0075] S2 After the polymerization reaction, a hydrophilic chain extender pre-dissolved in an organic solvent was added for heat preservation. After the reaction was completed, the temperature was lowered to 40 ° C and a neutralizing agent was added for neutralization;

[0076] S3. After the neutralization reaction is completed, the reaction product is added to deionized water for emulsification and dispersion to obtain a highly phase-separated polyurethane emulsion.

[0077] Examples 4-7

[0078] This embodiment provides a highly phase-separated polyurethane emulsion.

[0079] The difference from Example 1 is that, in this example, the linear polyurethane oligomer is provided by Preparation Example 2-5, wherein the molar number of the linear polyurethane oligomer is the same as that of the linear polyurethane oligomer used in Example 1.

[0080] Comparative Example 1-2

[0081] This comparative example provides a highly phase-separated polyurethane emulsion.

[0082] The difference from Example 1 is that in this comparative example, the linear polyurethane oligomer is provided by Comparative Preparation Example 1-2, wherein the molar number of the linear polyurethane oligomer is the same as that of the linear polyurethane oligomer used in Example 1.

[0083] Comparative Example 3

[0084] This comparative example provides a phase-separated polyurethane emulsion.

[0085] The difference from Example 1 is that in this comparative example, the linear polyurethane oligomer is replaced by an equal molar amount of isophorone diisocyanate.

[0086] Performance Testing

[0087] The sample emulsions provided in the examples and comparative examples were added dropwise to a clean glass vessel to a thickness of about 1 mm. After a uniform film was formed at room temperature, the following performance tests were performed on the film as follows:

[0088] (1) Degree of phase separation:

[0089] FT-IR (Fourier transform infrared spectroscopy) was used to detect and calculate the degree of phase separation. Specifically, the characteristic peaks of the sample in the ester carbonyl absorption region were separated and fitted using the Gaussian method. The hydrogen bonding index (HBI) was calculated based on the absorption peak areas of free carbonyls, disordered hydrogen-bonded carbonyls, and ordered hydrogen-bonded carbonyls. The larger the HBI value, the higher the degree of hydrogen bonding, indicating a higher degree of microphase separation. The HBI value was calculated as follows:

[0090]

[0091] Where: S A is the peak area of ​​hydrogen-bonded C=O, S B is the peak area of ​​free C=O.

[0092] (2) Tensile strength and elongation at break: The samples were cut into dumbbell shapes and tested according to GB / T 528-2009 at a tensile rate of 100 mm / min.

[0093] (3) Water absorption: Cut the film into 3 cm × 3 cm specimens, refer to T / CWA 206-2021, weigh the specimens and record their mass as m0, soak them in deionized water for 24 h, remove them and dry the surface moisture with filter paper, weigh the mass and record it as m1, and calculate the water absorption as follows:

[0094]

[0095] The test results are shown in Table 2:

[0096] Table 2

[0097]

[0098] As can be seen from the examples and performance tests, the present invention can obtain a polyurethane material with a high degree of phase separation by introducing linear polyurethane oligomers and other components. The resulting coating film has excellent mechanical properties and water resistance, among which the HBI is above 0.9, and optimally can reach above 1, the tensile strength is above 50 MPa, the elongation at break is above 420%, and the water absorption rate is below 7%.

[0099] A comparison of Examples 1 and 4-6 shows that in the linear polyurethane oligomer defined in the present invention, as the molar ratio of small molecule diol to diisocyanate increases from 0.50 to 0.67 (the average degree of polymerization increases from 3 to 5), the growth of the oligomer chain segment enhances the regularity of the hard segment and the degree of hydrogen bonding, the HBI significantly increases, the tensile strength simultaneously increases, the elongation at break decreases, the water absorption decreases, and the microphase separation is significantly enhanced; when the molar ratio further reaches 0.69, the hard segment aggregation tends to saturation and stacking frustration / increases free carbonyl groups, the HBI and tensile strength no longer increase and instead decrease, and the water absorption recovers from the minimum value, but the degree of phase separation of the resulting film remains high, and its performance can still meet application requirements.

[0100] From the comparison between Example 1 and Comparative Examples 1-2, it can be seen that in the linear polyurethane oligomer defined by the present invention, when the molar ratio of small molecule polyol to diisocyanate is in the range of (0.5-0.69):1, the obtained polyurethane material has a higher degree of phase separation and excellent mechanical properties and water resistance.

[0101] From the comparison of Example 1 and Comparative Example 3, it can be seen that when linear polyurethane oligomers are not introduced into the polyurethane material as hard segment building units, but isocyanate and polyether polyol are directly reacted to form a prepolymer, the hard segment chains in the structure are short, disordered, and lack effective aggregation; from the comparison of the test results, it can be seen that the HBI of Comparative Example 3 is 0.78, which is significantly lower than 0.95 of Example 1, indicating that its microphase separation degree is low and the hard segment aggregation ability is insufficient; at the same time, the tensile strength drops to 44.6 MPa and the water absorption rate increases to 8.2%, indicating that its structural density and water resistance are poor. Although the elongation at break is slightly higher, the overall performance is not as good as Example 1, verifying the significant effect of the pre-constructed linear hard segment structure on improving the performance of polyurethane.

[0102] The applicant declares that the present invention is illustrated by the above-described embodiments, but the present invention is not limited to the above-described embodiments. This does not mean that the present invention must rely on the above-described embodiments in order to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for the raw materials of the present invention, the addition of auxiliary ingredients, and the selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A highly phase-separated polyurethane emulsion, characterized in that: In parts by weight, it comprises: 18-42 parts of linear polyurethane oligomer, 30-50 parts of polymer diol, 3-7 parts of hydrophilic chain extender, 2-5.5 parts of neutralizer and 0.1-0.5 parts of catalyst, wherein: The raw materials for preparing the linear polyurethane oligomer include diisocyanate monomers and small molecule diols, and the molar ratio of the small molecule diols to the diisocyanate monomers is (0.50-0.69):

1.

2. The highly phase-separated polyurethane emulsion according to claim 1, characterized in that The average polymerization degree of the linear polyurethane oligomer is 3-5.

5.

3. The highly phase-separated polyurethane emulsion according to claim 1, characterized in that The diisocyanate monomer includes any one of 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, hexamethylene diisocyanate or diphenylmethane diisocyanate, or a combination of at least two thereof.

4. The highly phase-separated polyurethane emulsion according to claim 1, characterized in that The small molecule polyol includes any one of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol or 1,6-hexanediol, or a combination of at least two thereof.

5. The highly phase-separated polyurethane emulsion according to any one of claims 1 to 4, characterized in that The relative molecular weight of the polymer diol is 2000-3000; And / or, the hydrophilic chain extender includes 2,2-dimethylol propionic acid and / or 2-dimethylol butyric acid; and / or, the neutralizing agent comprises triethylamine; And / or, the catalyst comprises an organometallic catalyst.

6. The highly phase-separated polyurethane emulsion according to any one of claims 1 to 4, characterized in that The highly phase-separated polyurethane material further comprises 10-50 parts of an organic solvent and / or 100-300 parts of deionized water.

7. A method for preparing a highly phase-separated polyurethane emulsion according to any one of claims 1 to 6, characterized in that: The preparation method comprises: S1. A polymer diol and a linear polyurethane oligomer are polymerized under a catalyst to obtain a prepolymer; S2. The prepolymer is subjected to a chain extension reaction with a hydrophilic chain extender. After the reaction, a neutralizing agent and optionally deionized water are added to obtain the highly phase-separated polyurethane emulsion.

8. The preparation method according to claim 7, characterized in that In step S1, the polymerization reaction temperature is 70-80°C and the time is 1-1.5 hours; and / or, in step S2, the chain extension reaction is carried out at a temperature of 70-80° C. and for a time of 2-3 h; And / or, in step S2, the temperature of adding the neutralizing agent is 35-45°C.

9. A polyurethane film having a phase separation structure, characterized in that: The polyurethane film is prepared by coating and drying the highly phase-separated polyurethane emulsion according to any one of claims 1 to 6.

10. Use of the highly phase-separated polyurethane emulsion according to any one of claims 1 to 6 in the preparation of water-based coatings.

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