A multi-hydrogen bond aqueous elastic polyurethane emulsion and a preparation method thereof

Abstract

The application belongs to the technical field of high polymer materials, and particularly relates to a multi-hydrogen bond water-based elastic polyurethane emulsion and a preparation method thereof. The multi-hydrogen bond water-based elastic polyurethane emulsion is obtained by self-emulsifying dispersion of multi-hydrogen bond water-based elastic polyurethane monomers; the multi-hydrogen bond water-based elastic polyurethane is composed of units containing (a) hydrophilic polyethylene glycol, (b) hydrophobic polyether, (c) dihydrazide and (d) acryloyl glycine amide multi-hydrogen bond groups in side chains, and the mass of each unit is (a) 15-40%, (b) 30-50%, (c) 5-25% and (d) 5-20%; and the preparation process comprises the following steps: reacting polyethylene glycol, hydrophobic polyether dihydric alcohol and isophorone diisocyanate in a solvent, then adding acryloyl glycine amide to react, adding dihydrazide monomers to react to obtain a polyurethane solution, and finally adding water to self-emulsify, and then removing the solvent to obtain the emulsion. The emulsion is completely solvent-free, has good mechanical properties and water resistance after drying at room temperature, and can be used for coatings, adhesives and skin coating products.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a multi-hydrogen-bonded aqueous elastic polyurethane emulsion and its preparation method. Background Technology

[0002] Waterborne polyurethane has the advantage of being environmentally friendly and is gradually replacing traditional solvent-based polyurethane, finding wide application in coatings, adhesives, elastomers, and functional protective materials.

[0003] Existing waterborne polyurethanes mostly employ ionic emulsification to achieve aqueous phase dispersion. This typically involves introducing anionic hydrophilic groups (carboxylic acids or sulfonic acids) or cationic hydrophilic groups (tertiary amine salts) into the molecular structure. During preparation, organic bases (such as ethylenediamine) or organic acids (such as acetic acid) are used to neutralize the hydrophilic groups, thereby achieving stable dispersion of the polyurethane emulsion in water. For example, Chinese invention patent CN120607686A reports a waterborne polyurethane emulsion using dimethylolpropionic acid as a hydrophilic group and triethylamine as a neutralizing agent. Chinese invention patent CN120795280A reports an oleic acid sorbitol-modified castor oil-based waterborne polyurethane emulsion using N-methyldiethanolamine as a cationic hydrophilic chain extender and acetic acid as a neutralizing agent. Chinese patent CN120904424A discloses a waterborne polyurethane emulsion with a synergistic effect of hydrophilic chain extension. This polyurethane emulsion emulsifies polyurethane molecules through the synergistic effect of anionic hydrophilic groups and nonionic groups (polyether segments / hydroxyl groups), using triethylamine or ammonia as a neutralizing agent. However, this waterborne polyurethane emulsion prepared by emulsification relying on ionic groups has significant limitations in practical applications. Ionic polyurethane emulsions are sensitive to environmental ionic conditions. When positively charged ions, cationic functional components, or electrolytes are present in the system, electrostatic attraction and charge neutralization easily occur between anions and cations, weakening the electrostatic repulsion between emulsion particles. This induces particle aggregation, flocculation, and even precipitation, leading to a significant decrease in emulsion dispersion stability. Furthermore, the ionic hydrophilic structure formed by acid / base neutralization, while imparting water dispersibility, also weakens the hydrogen bonding between polyurethane molecular chains and the stability of the microphase structure, which is detrimental to the improvement of material mechanical properties and elastic recovery properties. Therefore, traditional ionic waterborne polyurethanes, while relying on alkali neutralization to achieve emulsification and dispersion, generally suffer from problems such as limited system stability, sensitivity to environmental conditions, and difficulty in balancing high elasticity and long-term durability, which limit their further application in high-performance waterborne elastic materials and complex systems.

[0004] Therefore, developing a waterborne polyurethane material that does not require alkali neutralization and still has good dispersion stability in complex ionic environments, as well as its preparation method, is of great significance for overcoming the technical limitations of traditional ionic waterborne polyurethane and expanding the application of waterborne polyurethane in the fields of high-performance elastomers and functional materials. Summary of the Invention

[0005] In view of the shortcomings of existing waterborne polyurethane emulsions, the present invention aims to provide a multi-hydrogen-bonded waterborne elastic polyurethane emulsion with mechanical properties and water resistance, and a method for preparing the same.

[0006] This invention introduces a multi-hydrogen-bonded hydrophilic monomer into the polyurethane molecular structure, achieving self-emulsifying dispersion of polyurethane without introducing any alkali neutralizing agent. The resulting polyurethane film exhibits excellent mechanical properties, water resistance, and adhesion to various substrates.

[0007] The multi-hydrogen-bonded waterborne elastic polyurethane emulsion provided by this invention is obtained by self-emulsification and dispersion of multi-hydrogen-bonded waterborne elastic polyurethane monomers. The multi-hydrogen-bonded waterborne elastic polyurethane is composed of units whose main chain contains (a) hydrophilic polyethylene glycol, (b) hydrophobic polyether (R1), and (c) diacylhydrazide (R3), and whose side chain contains (d) acryloylglycine multi-hydrogen-bonded groups. The mass percentages of each unit are: (a) 15-40%, (b) 30-50%, (c) 5-25%, and (d) 5-20%; a, b, c, and d total 100%.

[0008] R1 = -(O-CH(CH3)-CH2) m -、-(O-CH2CH2CH2CH2) m -or-(CH2CH2OCH2CH2) m -;

[0009] R2= , , or ;

[0010] R3=-(CH2) 0-8 -

[0011] Its structure can be represented as:

[0012]

[0013] The present invention also provides a method for preparing the above-mentioned multi-hydrogen-bonded aqueous elastic polyurethane emulsion, comprising the following steps (the raw materials involved are in parts by mass):

[0014] Step 1: Mix 4-10 parts of isophorone diisocyanate, 5-20 parts of polyethylene glycol, 3-20 parts of hydrophobic polyether diol, 0.01-0.05 parts of catalyst, and 10-30 parts of solvent evenly, and react at 50-70 ℃ (preferably 60-65 ℃) under a nitrogen atmosphere for 2-4 h to obtain prepolymer solution A;

[0015] Step 2: Add 0.5-3 parts of multi-hydrogen bond monomer chain extender to prepolymer solution A, and continue the reaction at 50-70 ℃ (preferably 60-65 ℃) for 2-4 h to obtain prepolymer solution B;

[0016] Step 3: Add 0.1-2 parts of dihydrazide chain extender to prepolymer solution B, and continue the reaction at 50-70 ℃ (preferably 60-65 ℃) for 2-4 h to obtain polyurethane solution;

[0017] Step 4: Cool the polyurethane solution to room temperature, add 30-60 parts of deionized water, emulsify, remove organic solvent, and obtain the waterborne elastic polyurethane emulsion.

[0018] In step one:

[0019] The molecular weight of the polyethylene glycol is 500-4000 g / mol.

[0020] The hydrophobic polyether diol is one or more of polypropylene glycol, polytetrahydrofuran ether diol, and polycaprolactone diol.

[0021] The hydrophobic polyether diol has a molecular weight of 1000-4000 g / mol.

[0022] The catalyst is an organic bismuth catalyst.

[0023] The solvent is one of acetone, butanone, ethyl acetate, and tetrahydrofuran.

[0024] In step two, the multi-hydrogen bond monomer chain extender is an acryloylglycine amide derivative, which has the following molecular structure:

[0025]

[0026] 1-[2-[3-[(2,3-dihydroxypropyl)thio]propionylamino]acetyl]-3-ethylurea

[0027]

[0028] 1-[2-[3-[(2,3-dihydroxypropyl)amino]propionylamino]acetyl]-3-ethylurea

[0029]

[0030] 1-[2-[4-[(1,3-dihydroxypropyl-2-yl)amino]butyrylamino]acetyl]-3-ethylurea

[0031]

[0032] 1-[2-[3-[[2-[bis(2-aminoethyl)amino]ethyl]amino]propionylamino]acetyl]-3-ethylurea;

[0033] In step three, the diacylhydrazine chain extender is selected from one or more of oxalic acid diacylhydrazine, adipic acid diacylhydrazine, succinic acid diacylhydrazine, and sebacyl hydrazine. Oxalic acid diacylhydrazine.

[0034] The multi-hydrogen-bonded aqueous elastic polyurethane emulsion prepared by this invention can be rapidly dried at room temperature to obtain an elastic polyurethane coating film.

[0035] The present invention relates to a multi-hydrogen bonded waterborne elastic polyurethane emulsion, which can be used as an environmentally friendly coating, adhesive, or film-forming resin or binder in skin coating products (such as cosmetics and medical aesthetic products).

[0036] Compared with the prior art, the beneficial effects of the present invention are:

[0037] (1) The present invention uses a multi-hydrogen bond hydrophilic monomer as the hydrophilic group in the molecular chain of waterborne polyurethane, and achieves the self-emulsification dispersion of polyurethane in water without introducing ionic hydrophilic chain extenders, without alkali neutralization and without relying on external emulsifiers.

[0038] (2) The main chain and side chain of the multi-hydrogen bond waterborne polyurethane of the present invention contain abundant hydrogen bonds, which can form a multi-hydrogen bond crosslinking network. This physical crosslinking can further improve the mechanical properties of the material and also endow it with good self-healing properties.

[0039] (3) The multi-hydrogen bond waterborne polyurethane emulsion of the present invention does not contain organic solvents, is pH neutral, and is suitable for closed environments, environmental protection requirements, or pH sensitive occasions. Attached Figure Description

[0040] Figure 1 This is a reaction route diagram of the multi-hydrogen-bonded waterborne elastic polyurethane in an embodiment of the present invention.

[0041] Figure 2 This is a water absorption rate diagram of the multi-hydrogen bond elastic polyurethane film in the embodiments and comparative examples of the present invention.

[0042] Figure 3 These are stress-strain diagrams of the multi-hydrogen-bonded elastic polyurethane films in the embodiments and comparative examples of the present invention.

[0043] Figure 4 This is an example of the application of the multi-hydrogen-bonded aqueous elastic polyurethane emulsion in a concealer simulant according to Embodiment 1 of the present invention. Detailed Implementation

[0044] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0045] The specific test method involved in this invention is as follows:

[0046] (1) Emulsion particle size test

[0047] At room temperature, 1-2 drops of polyurethane emulsion were added to 10 mL of deionized water and ultrasonically mixed. The average particle size of the emulsion was measured using a Zetasizer Nano-ZS90 instrument from Malvern, UK.

[0048] (2) Mechanical property testing

[0049] The prepared multi-hydrogen-bonded aqueous elastic polyurethane emulsion was cast into a tetrafluoroethylene mold and dried at room temperature for 24 hours to obtain a polyurethane film with a thickness of approximately 0.2 mm. The mechanical properties of the polyurethane film were tested using an Instron 5943 universal testing machine at a tensile speed of 50 mm / min.

[0050] (3) Water resistance test

[0051] The polyurethane film obtained by drying at room temperature was immersed in water for 48 hours, and its appearance was observed and its water absorption rate was recorded.

[0052] Example 1: Preparation of a multi-hydrogen-bonded waterborne elastic polyurethane emulsion (WPU-1).

[0053] 7.5 g of polyethylene glycol (molecular weight 1500 g / mol), 10 g of polytetrahydrofuran glycol (molecular weight 2000 g / mol), 4.8 g of isophorone diisocyanate, 0.01 g of organic bismuth catalyst, and 15 g of acetone were mixed and reacted at 60 °C for 2 h under a nitrogen atmosphere to obtain prepolymer solution A. 1.2 g of 1-[2-[3-[(2,3-dihydroxypropyl)thio]propionamide]acetyl]-3-ethylurea was added to prepolymer solution A, and the reaction was continued at 60 °C for 2 h to obtain prepolymer solution B. 1 g of oxalic acid dihydrazide was added to prepolymer solution B, and the reaction was continued at 60 °C for 4 h. After the reaction was completed, the mixture was cooled to room temperature, emulsified with 60 g of deionized water, and acetone was removed to obtain a multi-hydrogen-bonded waterborne elastic polyurethane emulsion (denoted as WPU-1). The emulsifying ability and water resistance of this multi-hydrogen-bonded polyurethane are shown in Table 1 and [Table 2 missing]. Figure 2 After drying and film formation, the film has an elastic modulus of 39.3 MPa, an elongation at break of 365.8%, and a tensile strength of 9.1 MPa. (See attached image.) Figure 3 .

[0054] Example 2: Preparation of a multi-hydrogen-bonded waterborne elastic polyurethane emulsion (WPU-2).

[0055] 7.5 g of polyethylene glycol (molecular weight 1500 g / mol), 10 g of polytetrahydrofuran glycol (molecular weight 2000 g / mol), 4.8 g of isophorone diisocyanate, 0.01 g of organic bismuth catalyst, and 15 g of acetone were mixed and reacted at 60 °C for 2 h under a nitrogen atmosphere to obtain prepolymer solution A. 1.84 g of 1-[2-[3-[(2,3-dihydroxypropyl)thio]propionamide]acetyl]-3-ethylurea was added to prepolymer solution A, and the reaction was continued at 60 °C for 4 h to obtain prepolymer solution B. 0.71 g of oxalic acid dihydrazide was added to prepolymer solution B, and the reaction was continued at 60 °C for 4 h. After the reaction was completed, the mixture was cooled to room temperature, emulsified with 50 g of deionized water, and acetone was removed to obtain a multi-hydrogen-bonded waterborne elastic polyurethane emulsion (denoted as WPU-2). The emulsifying ability and water resistance of this multi-hydrogen-bonded polyurethane are shown in Table 1 and [Table data missing]. Figure 2 After drying and film formation, the film has an elastic modulus of 22.0 MPa, an elongation at break of 439.1%, and a tensile strength of 11.3 MPa. (See attached image.) Figure 3 .

[0056] Example 3: Preparation of a multi-hydrogen-bonded waterborne elastic polyurethane emulsion (WPU-3).

[0057] 3 g of polyethylene glycol (molecular weight 1000 g / mol), 7 g of polypropylene glycol (molecular weight 1000 g / mol), 4.5 g of isophorone diisocyanate, 0.01 g of organobismuth catalyst, and 10 g of tetrahydrofuran were mixed and reacted at 60 °C for 2 h under a nitrogen atmosphere to obtain prepolymer solution A. 1.5 g of 1-[2-[3-[(2,3-dihydroxypropyl)amino]propionylamino]acetyl]-3-ethylurea was added to prepolymer solution A, and the reaction was continued at 60 °C for 4 h to obtain prepolymer solution B. 1.2 g of sebacic acid dihydrazide was added to prepolymer solution B, and the reaction was continued at 60 °C for 4 h. After the reaction was completed, the mixture was cooled to room temperature, and 60 g of deionized water was added for emulsification to remove tetrahydrofuran, yielding a multi-hydrogen-bonded waterborne elastic polyurethane emulsion (denoted as WPU-3). The emulsifying ability and water resistance of this multi-hydrogen-bonded polyurethane are shown in Table 1 and [Table data missing]. Figure 2 After drying and film formation, the film's elastic modulus was 27.9 MPa, its elongation at break was 531.2%, and its tensile strength was 16.5 MPa. (See attached image.) Figure 3 .

[0058] Example 4: Preparation of a multi-hydrogen-bonded waterborne elastic polyurethane emulsion (WPU-4).

[0059] 12 g of polyethylene glycol (molecular weight 2000 g / mol), 16 g of polycaprolactone diol (molecular weight 4000 g / mol), 5.7 g of isophorone diisocyanate, 0.03 g of organic bismuth catalyst, and 20 g of tetrahydrofuran were mixed and reacted at 60 °C for 2 h under a nitrogen atmosphere to obtain prepolymer solution A. 1.2 g of 1-[2-[3-[(2,3-dihydroxypropyl)amino]propionylamino]acetyl]-3-ethylurea was added to prepolymer solution A, and the reaction was continued at 60 °C for 4 h to obtain prepolymer solution B. 1.4 g of oxalic acid dihydrazide was added to prepolymer solution B, and the reaction was continued at 60 °C for 4 h. After the reaction was completed, the mixture was cooled to room temperature, and 40 g of deionized water was added for emulsification to remove the tetrahydrofuran, yielding a multi-hydrogen-bonded waterborne elastic polyurethane emulsion (denoted as WPU-4). The emulsifying ability and water resistance of this multi-hydrogen-bonded polyurethane are shown in Table 1 and [Table data missing]. Figure 2 After drying and film formation, the film's elastic modulus was 41.7 MPa, its elongation at break was 617.3%, and its tensile strength was 19.3 MPa. (See attached image.) Figure 3 .

[0060] Example 5: Preparation of a multi-hydrogen-bonded waterborne elastic polyurethane emulsion (WPU-5).

[0061] 4 g of polyethylene glycol (molecular weight 1000 g / mol), 6 g of polytetrahydrofuran glycol (molecular weight 1000 g / mol), 5.2 g of isophorone diisocyanate, 0.03 g of organobismuth catalyst, and 20 g of ethyl acetate were mixed and reacted at 60 °C for 2 h under a nitrogen atmosphere to obtain prepolymer solution A. 0.7 g of 1-[2-[3-[[2-[bis(2-aminoethyl)amino]ethyl]amino]propionylamino]acetyl]-3-ethylurea was added to prepolymer solution A, and the reaction was continued at 60 °C for 4 h to obtain prepolymer solution B. 1.4 g of oxalic acid dihydrazide was added to prepolymer solution B, and the reaction was continued at 60 °C for 4 h. After the reaction was completed, the mixture was cooled to room temperature, emulsified with 40 g of deionized water, and the ethyl acetate was removed to obtain a multi-hydrogen-bonded waterborne elastic polyurethane emulsion (denoted as WPU-5). The emulsifying ability and water resistance of this multi-hydrogen-bonded polyurethane are shown in Table 1 and [Table 2 missing]. Figure 2 After drying and film formation, the film has an elastic modulus of 5.5 MPa, an elongation at break of 712.5%, and a tensile strength of 4.3 MPa. (See attached image.) Figure 3 .

[0062] Example 6: Preparation of a multi-hydrogen-bonded waterborne elastic polyurethane emulsion (WPU-6).

[0063] 5 g of polyethylene glycol (molecular weight 1000 g / mol), 5 g of polytetrahydrofuran glycol (molecular weight 1000 g / mol), 5.0 g of isophorone diisocyanate, 0.03 g of organobismuth catalyst, and 20 g of ethyl acetate were mixed and reacted at 60 °C for 2 h under a nitrogen atmosphere to obtain prepolymer solution A. 1.5 g of 1-[2-[3-[(2,3-dihydroxypropyl)amino]propionylamino]acetyl]-3-ethylurea was added to prepolymer solution A, and the reaction was continued at 60 °C for 4 h to obtain prepolymer solution B. 0.9 g of oxalic acid dihydrazide was added to prepolymer solution B, and the reaction was continued at 60 °C for 4 h. After the reaction was completed, the mixture was cooled to room temperature, emulsified with 40 g of deionized water, and the ethyl acetate was removed to obtain a multi-hydrogen-bonded waterborne elastic polyurethane emulsion (denoted as WPU-6). The emulsifying ability and water resistance of this multi-hydrogen-bonded polyurethane are shown in Table 1 and [Table 2 missing]. Figure 2 After drying and film formation, the film has an elastic modulus of 3.7 MPa, an elongation at break of 695.7%, and a tensile strength of 11.6 MPa. (See attached image.) Figure 3 .

[0064] Comparative Example 1, preparation of a multi-hydrogen-bonded waterborne elastic polyurethane emulsion (CWPU-1).

[0065] 7.5 g of polyethylene glycol (molecular weight 1500 g / mol), 5 g of polytetrahydrofuran glycol (molecular weight 2000 g / mol), 4.2 g of isophorone diisocyanate, 0.03 g of organic bismuth catalyst, and 15 g of acetone were mixed and reacted at 60 °C for 2 h under a nitrogen atmosphere to obtain a prepolymer. 2.8 g of 1-[2-[3-[(2,3-dihydroxypropyl)thio]propionamide]acetyl]-3-ethylurea was added to the prepolymer, and the reaction was continued at 60 °C for 4 h to obtain prepolymer solution B. 0.35 g of oxalic acid dihydrazide was added to prepolymer solution B, and the reaction was continued at 60 °C for 4 h. After the reaction was completed, the mixture was cooled to room temperature, emulsified with 40 g of deionized water, and acetone was removed to obtain a multi-hydrogen-bonded waterborne elastic polyurethane emulsion (denoted as CWPU-1). The emulsifying ability and water resistance of this multi-hydrogen-bonded polyurethane are shown in Table 1 and [Table data missing]. Figure 2 After drying and film formation, the film has an elastic modulus of 6.0 MPa, an elongation at break of 261.5%, and a tensile strength of 0.04 MPa. (See attached image.) Figure 3 .

[0066] Comparative Example 2, preparation of a multi-hydrogen-bonded waterborne elastic polyurethane emulsion (CWPU-2).

[0067] 8 g of polyethylene glycol (molecular weight 1500 g / mol), 4 g of polypropylene glycol (molecular weight 2000 g / mol), 4.5 g of isophorone diisocyanate, 0.03 g of organic bismuth catalyst, and 15 g of acetone were mixed and reacted at 60 °C for 2 h under a nitrogen atmosphere to obtain a prepolymer. 1.5 g of 1-[2-[3-[(2,3-dihydroxypropyl)thio]propionamide]acetyl]-3-ethylurea was added to the prepolymer, and the reaction was continued at 60 °C for 4 h to obtain prepolymer solution B. 0.9 g of oxalic acid dihydrazide was added to the prepolymer solution B, and the reaction was continued at 60 °C for 4 h to obtain reaction solution A. After the reaction was completed, 60 g of deionized water was added for emulsification to remove acetone, yielding a multi-hydrogen-bonded waterborne elastic polyurethane emulsion (denoted as CWPU-2). The emulsifying ability and water resistance of this multi-hydrogen-bonded polyurethane are shown in Table 1 and [Table data missing]. Figure 2 After drying and film formation, the film has an elastic modulus of 6.1 MPa, an elongation at break of 354.5%, and a tensile strength of 0.02 MPa. (See attached image.) Figure 3 .

[0068] Comparative Example 3, preparation of a multi-hydrogen-bonded waterborne elastic polyurethane emulsion (CWPU-3).

[0069] 10 g of polypropylene glycol with a molecular weight of 1000 g / mol, 5.0 g of isophorone diisocyanate, 0.03 g of organic bismuth catalyst, and 15 g of acetone were mixed and reacted at 60 °C for 2 h under a nitrogen atmosphere to obtain a prepolymer. 1.2 g of 1-[2-[3-[(2,3-dihydroxypropyl)thio]propionamide]acetyl]-3-ethylurea was added to the prepolymer, and the reaction was continued at 60 °C for 2 h to obtain prepolymer solution B. 1 g of oxalic acid dihydrazide was added to prepolymer solution B, and the reaction was continued at 60 °C for 4 h. After the reaction was completed, the mixture was cooled to room temperature, emulsified with 60 g of deionized water, and acetone was removed to obtain a multi-hydrogen-bonded waterborne elastic polyurethane emulsion (denoted as CWPU-3). The emulsifying ability and water resistance of this multi-hydrogen-bonded polyurethane are shown in Table 1 and [Table data missing]. Figure 2 After drying and film formation, the film has an elastic modulus of 5.5 MPa, an elongation at break of 920.9%, and a tensile strength of 6.33 MPa. (See attached image.) Figure 3 .

[0070] Table 1. Emulsification and water resistance of multi-hydrogen-bonded waterborne polyurethanes in Examples and Control Examples

[0071] .

[0072] Note: Testing was conducted after direct film formation using the polyurethane solution.

[0073] As shown in Table 1, the multi-hydrogen-bonded polyurethanes (WPU-1~6) in Examples 1-6 all exhibit excellent emulsification capabilities in water, with the obtained emulsion particle sizes within the submicron range. Furthermore, after drying the emulsion at room temperature, the resulting films remained transparent after immersion in water, showing no swelling. The water absorption rate of the films was below 0.5%, demonstrating outstanding water resistance. While the multi-hydrogen-bonded polyurethanes in Comparative Examples 1 and 2 (CWPU-1~2) possessed good emulsification capabilities, they exhibited whitening and swelling during water immersion, indicating poor water resistance. The multi-hydrogen-bonded polyurethane in Comparative Example 3 (CWPU-3) showed good water resistance but lacked water emulsification capabilities.

[0074] A concealer simulant was prepared by mixing the multi-hydrogen-bonded polyurethane emulsion from Example 1 with titanium dioxide. This simulant was applied to the skin of the hand, and after 3 minutes, the coating dried into a film that completely covered the green markings on the skin. Further immersion of the hand in water for 10 minutes showed no change in the appearance of the film, demonstrating good water resistance. The experimental procedure is detailed below. Figure 4 This indicates that the aqueous elastic multi-hydrogen bond polyurethane emulsion of the present invention can be applied to the preparation of skin-coated products.

Claims

1. A multi-hydrogen-bonded aqueous elastic polyurethane emulsion, characterized in that, It is obtained by self-emulsification and dispersion of multi-hydrogen-bonded waterborne elastic polyurethane monomers; the multi-hydrogen-bonded waterborne elastic polyurethane is composed of units with a main chain containing (a) hydrophilic polyethylene glycol, (b) hydrophobic polyether (R1), and (c) diacylhydrazine (R3), and side chains containing (d) acryloylglycine multi-hydrogen-bonded groups, with the following mass percentages for each unit: (a) 15-40%, (b) 30-50%, (c) 5-25%, (d) 5-20%; a, b, c, and d total 100%; wherein: R1 = -(O-CH(CH3)-CH2) m -,-(O-CH2CH2CH2CH2) m -or-(CH2CH2OCH2CH2) m -; R2= , , or ; R3=-(CH2) 0-8 -。 2. The method for preparing the multi-hydrogen-bonded aqueous elastic polyurethane emulsion as described in claim 1, characterized in that, The specific steps are as follows: Step 1: Mix 4-10 parts of isophorone diisocyanate, 5-20 parts of polyethylene glycol, 3-20 parts of hydrophobic polyether diol, 0.01-0.05 parts of catalyst, and 10-30 parts of solvent evenly, and react at 50-70 ℃ for 2-4 h under a nitrogen atmosphere to obtain prepolymer solution A; Step 2: Add 0.5-3 parts of multi-hydrogen bond monomer chain extender to prepolymer solution A, and continue the reaction at 50-70 °C for 2-4 h to obtain prepolymer solution B; Step 3: Add 0.1-2 parts of dihydrazide chain extender to prepolymer solution B, and continue the reaction at 50-70 ℃ for 2-4 h to obtain polyurethane solution; Step 4: Cool the polyurethane solution to room temperature, add 30-60 parts of deionized water to emulsify, and remove the solvent to obtain the waterborne elastic polyurethane emulsion.

3. The preparation method according to claim 2, characterized in that, The molecular weight of the polyethylene glycol mentioned in step one is 500-4000 g / mol.

4. The preparation method according to claim 2, characterized in that, The hydrophobic polyether diol mentioned in step one is one or more of polypropylene glycol, polytetrahydrofuran ether diol, and polycaprolactone diol.

5. The preparation method according to claim 2, characterized in that, The macromolecular diol mentioned in step one has a molecular weight of 1000-4000 g / mol.

6. The preparation method according to claim 2, characterized in that, The catalyst mentioned in step one is an organic bismuth catalyst.

7. The preparation method according to claim 2, characterized in that, The solvent mentioned in step one is one of acetone, butanone, ethyl acetate, and tetrahydrofuran.

8. The preparation method according to claim 2, characterized in that, The multi-hydrogen bond monomer chain extender mentioned in step two is an acryloylglycine derivative.

9. The preparation method according to claim 2, characterized in that, The dihydrazide chain extender mentioned in step three is selected from one of oxalic acid dihydrazide, adipic acid dihydrazide, succinic acid dihydrazide, and sebacic acid dihydrazide.

10. The application of the multi-hydrogen bonded aqueous elastic polyurethane emulsion as described in claim 1 as a film-forming resin or binder in coatings, adhesives, cosmetics, and medical aesthetic products.

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