A cationic waterborne polyurethane-based wash-resistant hydrophilic finishing agent for polyester and its preparation method

Abstract

This invention belongs to the field of hydrophilic finishing agent technology, and particularly relates to a novel cationic waterborne polyurethane-based wash-resistant hydrophilic finishing agent for polyester and its preparation method. The cationic waterborne polyurethane comprises: a first repeating unit as shown in Formula I, a second repeating unit as shown in Formula II, and a third repeating unit as shown in Formula III, connected sequentially. The cationic waterborne polyurethane of this invention, when used as a hydrophilic finishing agent for polyester, can solve the problems of poor hydrophilicity and wash resistance of existing polyester hydrophilic finishing agents. This invention can prepare cationic waterborne polyurethane-based wash-resistant hydrophilic finishing agents for polyester with different properties and structures, is easy to modify, and has simple operation in synthesis and post-treatment processes, facilitating widespread application.

Description

Technical Field

[0001] This invention belongs to the field of hydrophilic finishing agent technology, and particularly relates to a novel cationic waterborne polyurethane-based wash-resistant polyester hydrophilic finishing agent and its preparation method. Background Technology

[0002] Polyester fabrics are typical hydrophobic fabrics. The lack of hydrophilic groups in polyester (PET, polyethylene terephthalate) molecules results in poor moisture absorption and comfort during wear, easily leading to a series of problems such as static electricity, dust attraction, and staining. One industrially feasible solution to this problem is to coat or adsorb a hydrophilic finishing agent onto the surface of the polyester fibers through impregnation, thus making the polyester surface hydrophilic.

[0003] There are some polyester polyether-based hydrophilic finishing agents on the market. These polymeric finishing agents can impart good hydrophilicity to polyester, but their wash resistance needs to be improved. Therefore, developing a finishing agent to improve the hydrophilicity of polyester fibers to enhance wearing comfort and wash resistance has become one of the research hotspots in recent years. Summary of the Invention

[0004] In view of this, the present invention provides a novel cationic waterborne polyurethane-based wash-resistant polyester hydrophilic finishing agent and its preparation method. The cationic waterborne polyurethane is used as a polyester hydrophilic finishing agent, which can solve the problems of poor hydrophilicity and poor wash resistance of existing polyester hydrophilic finishing agents.

[0005] This invention provides a cationic aqueous polyurethane, comprising a first repeating unit of Formula I, a second repeating unit of Formula II, and a third repeating unit of Formula III connected in sequence.

[0006]

[0007] Wherein, R1 is selected from one or more of CONHC2H4, COOC2H4, OC2H4 and CH2; R2 is selected from defunctionalized residues of diisocyanate, and the number of carbon atoms is less than 14; R3 is CH3; R4 is H, CH2CH2OH, benzyl or (CH2). n CH3, where n is a natural number selected from 0 to 18.

[0008] This invention studies how to enhance material surface adhesion by drawing on the cationic-π interaction in the adhesive properties of marine mussels. The novel cationic waterborne polyurethane disclosed in this invention has repeating unit structures as shown in Formulas I, II, and III. This invention primarily achieves strong adhesion between the hydrophilic agent and the polyester fiber surface and enhances hydrophilic properties by introducing a hydrophilic cationic structure into the molecular chain, which can interact with polyester fibers with negatively charged aromatic ring structures through electrostatic attraction (cationic-π interaction).

[0009] The first repeating unit shown in Formula I has structures such as a benzene ring, an amino group, and an ester group; wherein R1 is selected from one or more of CONHC2H4, COOC2H4, OC2H4, and CH2 (methylene), and R2 is selected from defunctionalized residues of diisocyanates, with the number of carbon atoms C≤14. In this invention, the diisocyanate O=C=N-R2-N=C=O contains two -NCO functional groups; in the embodiments of this invention, R2 is selected from C 10 H 18 C 10 H6, C6H3CH3, C 14 H 10 C7H 12 and C9H 14 One or more of them.

[0010] The second repeating unit shown in Formula II contains an amino group, an ester group, and a quaternary ammonium cation structure; R2 is selected from defunctionalized residues of diisocyanates. R3 is methyl (-CH3); R4 is hydrogen (H), CH2CH2OH, benzyl, or (CH2). n CH3, where n is a natural number selected from 0 to 18. Furthermore, the third repeating unit shown in Formula III is a polyethylene glycol structural unit.

[0011] For example, the cationic waterborne polyurethane that can be used as a hydrophilic finishing agent provided by the first aspect of the present invention has the following general chemical structure formula, wherein x, y, and z are the number of repeating units, all of which are positive integers; the repeating units are connected sequentially.

[0012]

[0013] The present invention provides a method for preparing cationic aqueous polyurethane, comprising the following steps:

[0014] A prepolymer is prepared by mixing and reacting the diol hydroxybenzene shown in Formula 1 with a diisocyanate having 16 or fewer carbon atoms and the cationic diol shown in Formula 2.

[0015] The prepolymer was subjected to a chain extension reaction with polyethylene glycol to obtain cationic waterborne polyurethane.

[0016]

[0017] Wherein, R1 is selected from one or more of CONHC2H4, COOC2H4, OC2H4, and CH2; R3 is CH3; R4 is H, CH2CH2OH, benzyl, or (CH2). n CH3, n is a natural number from 0 to 18; R0 is a halogen atom or a hydroxyl group.

[0018] A second aspect of this application provides a method for preparing a cationic waterborne polyurethane for use as a wash-resistant hydrophilic finishing agent for polyester, comprising:

[0019] First, the glycol monomer composition and polyethylene glycol are subjected to dehydration pretreatment.

[0020] A prepolymer is prepared by mixing and reacting a diol monomer composition with a diisocyanate, preferably in the presence of a catalyst.

[0021] The prepolymer is subjected to chain extension or end-capping reaction with polyethylene glycol to obtain a cationic waterborne polyurethane-based washable hydrophilic finishing agent for polyester.

[0022] The diol monomer composition described in this embodiment of the invention comprises: diol hydroxybenzene and cationic diol, as shown in Formula 1 and Formula 2, respectively. The diol hydroxybenzene is represented by the general formula 1 below, where R1 is selected from one or more of CONHC2H4, COOC2H4, OC2H4, and CH2; it is selected from bis(2-hydroxyethyl) terephthalate, N,N-bis(2-hydroxyethyl)-terephthalamide, hydroquinone-bis(2-hydroxyethyl ether), O,O-bis(2-hydroxyethoxy)benzene, 1,4-bis(2-hydroxyethyl)benzene, 1,4-benzyldiethanol, etc.

[0023]

[0024] In another embodiment, the diol hydroxybenzene is selected from bis(2-hydroxyethyl) terephthalate, with the following chemical structural formula:

[0025]

[0026] In an embodiment of the present invention, the cationic diol has the following general formula 2 structure, which is a cationic quaternary ammonium salt diol monomer. This cationic quaternary ammonium salt structure can impart excellent hydrophilicity, washability, antibacterial and antistatic properties to the fabric.

[0027]

[0028] In Formula 2, R3 is CH3; R4 is H, CH2CH2OH, benzyl, or (CH2). n CH3, n is selected from natural numbers from 0 to 18; R0 is a halogen atom (preferably -Cl, -Br) or a hydroxyl group (-OH).

[0029] In other embodiments, the cationic diol monomer is selected from one or more of the following: hydrochloride, bromate, and hydroxide of N-ethyldiethanolamine; bis(2-hydroxyethyl)dimethylammonium chloride and its hydroxide; hydrochloride, bromate, and hydroxide of N-methyldiethanolamine; hydrochloride, bromate, and hydroxide of methyl(dihydroxyethyl)stearylamine; and more preferably bis(2-hydroxyethyl)dimethylammonium chloride, with the chemical structure shown below:

[0030]

[0031] In an embodiment of the present invention, before reacting with diisocyanate, the diol hydroxybenzene and cationic diol are respectively dehydrated under vacuum, preferably under vacuum conditions and at 70°C for 6 hours for later use.

[0032] In embodiments of the present invention, the diisocyanate is selected from one or more of isophorone diisocyanate (IPDI), 1,5-naphthalene diisocyanate, toluene diisocyanate (TDI), 4,4-diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), and dicyclohexylmethane diisocyanate. It has 16 or fewer carbon atoms and its structure can be represented as: NCOC 10 H 18 NCO, NCOC 10 H6NCO, NCOCH3C6H3NCO, NCOC 13 H 10 NCO, NCOC6H 12 NCO, NCOC 13 H 22 NCO.

[0033] The chemical structural formula of hexamethylene diisocyanate (HDI) is as follows:

[0034]

[0035] Preferably, the reaction temperature of the diol hydroxybenzene, cationic diol, and diisocyanate is room temperature, and the reaction time is 2–4 hours. In embodiments of the present invention, the molar ratio of the diol hydroxybenzene to the cationic diol is 10:1 to 1:1.

[0036] In another embodiment, the glycol monomer composition is first dissolved in an organic solvent, and then diisocyanate is slowly added dropwise at room temperature. The R value is controlled to be 1.1-1.8 during the prepolymerization reaction (R refers to the molar ratio of total NCO / OH, and OH is the sum of glycol hydroxybenzene and cationic glycol monomer).

[0037] In embodiments of the present invention, the reaction for obtaining the prepolymer is carried out under the action of a catalyst; the catalyst is selected from one or more organotin and tertiary amine catalysts, such as dibutyltin dilaurate. The amount of the catalyst is preferably 0.01-0.2 wt%, more preferably 0.02-0.15% (based on the total amount of the prepolymer reaction system).

[0038] In another embodiment, the solvent is one or more of acetone, toluene, and N,N-dimethylformamide (DMF), preferably acetone.

[0039] After obtaining the prepolymer by reacting under a nitrogen atmosphere, in this embodiment of the invention, polyethylene glycol (PEG) is added to the synthesized polyurethane prepolymer for end-capping or chain extension. After the reaction is completed, the solvent is removed by vacuum distillation to obtain the cationic waterborne polyurethane product.

[0040] In embodiments of the present invention, the polyethylene glycol is preferably dehydrated under vacuum conditions at 70°C for 6 hours before use. The polyethylene glycol is selected from one or more of a number-average molecular weight of 400-20000, such as PEG600, PEG1000, PEG1500, etc.

[0041] In another embodiment, the synthesized cationic aqueous polyurethane prepolymer is chain-extended or end-capped with polyethylene glycol at a temperature of 60-70°C for 3 hours. After the reaction, acetone is removed by vacuum distillation. Preferably, the reaction temperature between the prepolymer and polyethylene glycol is 65°C; the molar ratio of the prepolymer to polyethylene glycol can be 10:1 to 2:1.

[0042] Specifically, the synthesis steps of the preparation method in this application embodiment include:

[0043] (1) Dehydration pretreatment of raw materials: Dehydrate glycol hydroxybenzene, cationic glycol and polyethylene glycol at 70-90℃ and 0.08-0.1Mpa vacuum for 6-8 hours and set aside.

[0044] (2) Cationic waterborne polyurethane prepolymer reaction: First, the amount of diol hydroxybenzene and cationic diol in a molar ratio of (10:1 to 1:1) is dissolved in acetone and stirred until uniform. Then, 0.01 to 0.2 wt% of catalyst is added to the mixed solution. Finally, diisocyanate in a molar ratio of (1:1 to 1:1.2) is slowly added dropwise at room temperature. After reacting for 2-4 hours, cationic waterborne polyurethane prepolymer is obtained.

[0045] (3) Chain extension or end-capping reaction: Polyethylene glycol with a number average molecular weight of 600 in a molar ratio of (10:1 to 2:1) is added to the synthesized cationic waterborne polyurethane prepolymer for chain extension or end-capping. The temperature is gradually increased to 65°C and the reaction is carried out for 3 hours. After the reaction is completed, the solvent is removed by vacuum distillation to obtain cationic waterborne polyurethane washable polyester hydrophilic finishing agent.

[0046] That is, the present invention also provides the application of the cationic waterborne polyurethane as described above or the cationic waterborne polyurethane obtained by the preparation method described above as a hydrophilic finishing agent for wash-resistant polyester.

[0047] The specific application method includes: preparing 50 ml of a 4 wt% hydrophilic agent solution (0.5-8 wt%) of the cationic waterborne polyurethane washable polyester hydrophilic finishing agent, and adding it to a 25×3cm polyester fabric (190g / m²). 2 For knitted fabrics (160D / 48F), immerse for 10 minutes, then perform two immersions and two squeezings, followed by natural air drying. Preferably, bake at 170℃ for 60 seconds to obtain the corresponding finished polyester fabric. The applicable fabrics can be extended to all polyester-containing fabrics.

[0048] This invention draws inspiration from the cation-π interaction, which exhibits adhesive properties underwater in mussels. It leverages the negative potential of polyester fibers containing numerous benzene rings in aqueous solutions, allowing cations to adsorb onto the fiber surface through electrostatic attraction (cation-π interaction), resulting in strong affinity and adhesion. Based on this, this invention introduces hydrophilic cationic glycol and polyethylene glycol components through prepolymerization of alcohol hydroxyl groups and diisocyanates, followed by chain extension or end-capping reactions. The introduction of cationic components allows the hydrophilic agent to firmly adhere to the polyester fabric surface in aqueous solution, with hydrophilic segments arranging on the fiber surface to form a hydrophilic surface layer, thus giving the polyester fabric excellent hydrophilic properties. Simultaneously, during finishing, the introduced benzene ring components, under baking conditions, can undergo a co-melting and co-crystallization effect with the polyester fibers, fixing them to the fiber surface, thereby further enhancing the wash resistance of the cationic waterborne polyurethane hydrophilic finishing agent.

[0049] Waterborne polyurethane exhibits excellent adhesion and permeability in various substrates, making it an ideal green and environmentally friendly material. It also possesses good mechanical properties and compatibility, and has been widely used in coatings, leather, and foam industries in recent years. This invention presents a novel cationic waterborne polyurethane synthesized using this method, which, as a wash-resistant hydrophilic finishing agent for polyester, solves the problems of poor hydrophilicity and wash resistance of existing polyester hydrophilic finishing agents.

[0050] Furthermore, this invention allows for precise control of reaction conditions (pretreatment, reaction time, temperature, etc.) during synthesis by altering the selection of the three raw materials: diol hydroxybenzene, diisocyanate, and cationic diol, thus enabling the preparation of cationic waterborne polyurethane-based wash-resistant hydrophilic finishing agents for polyester with varying properties and structures. This invention is easy to modify, simple to operate during synthesis and finishing, yields high output, produces minimal pollution, and operates at relatively low reaction temperatures, facilitating large-scale application. Attached Figure Description

[0051] To more clearly illustrate the embodiments and technical solutions of this application, the accompanying drawings required in the embodiments are briefly introduced below.

[0052] Figure 1 The infrared spectrum (FT-IR) of the cationic aqueous polyurethane prepared in Example 1 of this application;

[0053] Figure 2 This is a physical image of the cationic waterborne polyurethane-based washable polyester hydrophilic finishing agent provided in Example 1 of this application. Detailed Implementation

[0054] The technical solutions in the embodiments of this application are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0055] To better understand the technical content of this invention, specific embodiments are provided below to further illustrate the invention. In the following embodiments, all raw materials are commercially available.

[0056] Example 1

[0057] Di(2-hydroxyethyl) terephthalate, bis(2-hydroxyethyl)dimethylammonium chloride, and PEG600 were dehydrated under vacuum at 70°C and 0.08 MPa for 6 hours, and then placed in a desiccator for later use. Subsequently, 12.71 g (0.05 mol) of bis(2-hydroxyethyl) terephthalate and 8.48 g (0.05 mol) of bis(2-hydroxyethyl)dimethylammonium chloride were dissolved in 200 ml of acetone and mixed thoroughly in a reaction vessel. Then, 0.5 wt% of an organotin catalyst, dibutyltin dilaurate (the same in the following examples), was added. Finally, 20.18 g (0.12 mol) of HDI was slowly added dropwise at room temperature, and the reaction was carried out under nitrogen protection for 2 hours to obtain the prepolymer. 12g of PEG600 polyethylene glycol was added to the synthesized polyurethane prepolymer for end-capping or chain extension. The reaction was carried out at 65℃ for 3h. After the reaction was completed, the solvent was removed by vacuum distillation to obtain a cationic waterborne polyurethane-based washable polyester hydrophilic finishing agent.

[0058] The following is the chemical structural formula of the cationic waterborne polyurethane-based wash-resistant polyester hydrophilic finishing agent synthesized in Example 1:

[0059]

[0060] The characteristic groups of the prepared cationic waterborne polyurethane-based wash-resistant hydrophilic polyester finishing agent were characterized, as shown in the attached figure. Figure 1 As shown: 3377cm -1 The vibrational absorption peak of NH is 2929 cm⁻¹. -1 ~3000cm -1 The absorption peak for the stretching vibration of CH is 1669 cm⁻¹. -1 The peak is the vibrational absorption peak of amide C=O, at 1450 cm⁻¹. -1 and 1509cm -1 This is the vibrational absorption peak of the benzene ring C=C skeleton, 1106 cm⁻¹. -1 and 1419cm -1 The vibrational absorption peak of CN is 1249 cm⁻¹. -1 The peaks represent the vibrational absorption peaks of CO. In summary, the absorption peaks corresponding to each characteristic group are consistent with the molecular structure of the target product.

[0061] Figure 2 The image shows the actual product. The left side is a 4wt% polymer aqueous solution, and the right side is a white solid after solvent removal (other products include liquid, gel and solid powder, with a preferred solubility of 50-200 g / L). It can be seen that it can be uniformly dissolved in water; the molecular weight of the synthesized polyurethane is in the range of 8k-200k.

[0062] Example 2

[0063] N,N-bis(2-hydroxyethyl)-terephthalamide, bis(2-hydroxyethyl)dimethylammonium chloride, and PEG1000 were dehydrated under vacuum at 70°C and 0.08 MPa for 6 hours and then stored in a desiccator for later use. Subsequently, 12.61 g (0.05 mol) of N,N-bis(2-hydroxyethyl)-terephthalamide and 8.48 g (0.05 mol) of bis(2-hydroxyethyl)dimethylammonium chloride were dissolved in 200 ml of acetone and mixed thoroughly in a reaction vessel. Then, 0.5 wt% of dibutyltin dilaurate was added, and finally, 20.18 g (0.12 mol) of HDI was slowly added dropwise at room temperature. The reaction was carried out under nitrogen protection for 2 hours to obtain the prepolymer. 20g of polyethylene glycol PEG1000 was added to the synthesized polyurethane prepolymer for end-capping or chain extension. The reaction was carried out at 65℃ for 3h. After the reaction was completed, the solvent was removed by vacuum distillation to obtain a cationic waterborne polyurethane-based washable hydrophilic finishing agent for polyester.

[0064] Example 3

[0065] 1,4-Benzenediethanol, bis(2-hydroxyethyl)dimethylammonium chloride, and PEG1500 were dehydrated under vacuum at 70°C and 0.08 MPa for 6 hours and then stored in a desiccator for later use. Subsequently, 6.91 g (0.05 mol) of 1,4-Benzenediethanol and 8.48 g (0.05 mol) of bis(2-hydroxyethyl)dimethylammonium chloride were dissolved in 200 ml of acetone and mixed thoroughly in a reaction vessel. Then, 0.5 wt% of dibutyltin dilaurate was added, followed by the slow addition of 20.18 g (0.12 mol) of HDI at room temperature. The reaction was carried out under nitrogen protection for 2 hours to obtain a prepolymer. 30 g of polyethylene glycol containing PEG1500 was added to the synthesized polyurethane prepolymer for end-capping or chain extension. The reaction was carried out at 65°C for 3 hours. After the reaction, the solvent was removed by vacuum distillation to obtain a cationic waterborne polyurethane-based washable hydrophilic finishing agent for polyester.

[0066] Application method:

[0067] For the cationic waterborne polyurethane wash-resistant polyester hydrophilic finishing agents of Examples 1 to 3, 50 ml of 4 wt% hydrophilic agent solution was prepared and added to 25×3 cm polyester fabrics (190 g / m²). 2 The knitted fabric (160D / 48F) was immersed for 10 minutes, then dipped and rolled twice, air-dried naturally, and baked at 170℃ for 60 seconds to obtain the corresponding treated polyester fabric, which were marked as experimental samples of Examples 1 to 3.

[0068] The control group consisted of polyester fabrics not treated with cationic waterborne polyurethane-based washable hydrophilic polyester finishing agents.

[0069] Performance Tests (Table 1):

[0070] Hydrophilicity: In this application, the hydrophilicity of polyester fabrics treated with cationic waterborne polyurethane washable polyester hydrophilic finishing agents without cationic waterborne polyurethane and polyester fabrics treated with cationic waterborne polyurethane washable polyester hydrophilic finishing agents of Examples 1 to 3 was evaluated by capillary effect test method. The evaluation method refers to FZ / T 01071-2008, and the height of liquid rising along the textile material through capillary action within 10 minutes was recorded.

[0071] Washability: Referring to the AATCC-61 standard, 46g of steel balls and 150ml of 1.5% detergent were added to each tank and washed at 49°C for 45 minutes at a time (one wash is equivalent to 5 household machine washes). The washability of the polyester fabrics treated with cationic waterborne polyurethane washable polyester hydrophilic finishing agents and the polyester fabrics treated with cationic waterborne polyurethane washable polyester hydrophilic finishing agents of Examples 1 to 3 were measured.

[0072] Table 1 Performance Results

[0073]

[0074] Note: PET is the control group polyester fabric; W0 represents the liquid core absorption height of the polyester fabric before washing (cm); W5 represents the liquid core absorption height of the polyester fabric after 5 washes (cm), and so on.

[0075] As can be seen from the results in Table 1, the liquid wicking height of polyester fabrics without hydrophilic finishing is very low, ranging from 0.3cm to 0.8cm.

[0076] The capillary effect (e.g., liquid wicking height between 8.1-9.3 cm before washing) of polyester fabric treated with a hydrophilic agent is superior to that of polyester fabric without the hydrophilic agent treatment, indicating that the hydrophilicity of the fabric is greatly improved after treatment with a cationic waterborne polyurethane-based wash-resistant polyester hydrophilic finishing agent. Furthermore, even after 30 quick washes, the liquid wicking height of the fabric remains higher than that of the polyester fabric without the hydrophilic agent treatment, indicating that the polyester fabric treated with the cationic waterborne polyurethane-based wash-resistant polyester hydrophilic finishing agent has excellent wash resistance.

[0077] The above results collectively demonstrate that the present invention, through the synthesis of a cationic waterborne polyurethane-based wash-resistant hydrophilic finishing agent for polyester using a specific four-component system of cationic diol, diol hydroxybenzene, diisocyanate, and polyethylene glycol, achieves the aforementioned structure. This agent utilizes the electrostatic attraction between the cationic -π-particles and the negatively charged surface of the polyester fabric, as well as the co-melting and blending of the polyester fabric and the hydrophilic agent during the finishing process, to impart good hydrophilicity and wash resistance to the polyester fabric, thereby improving wearing comfort to a certain extent. Furthermore, the present invention features simple preparation, low pollution, high yield, low reaction temperature, good hydrophilicity, and excellent wash resistance during synthesis and finishing.

[0078] It should be noted that the above embodiments are only for better demonstrating the technical effects of the present invention, and are not intended to limit the scope of protection of the present invention. Any person skilled in the art should understand that any modifications or changes, or equivalent substitutions made without departing from the scope of the technical solution of the present invention should fall within the scope of protection of the present invention.

Claims

1. A cationic waterborne polyurethane, characterized in that, It includes the first repeating unit shown in Equation I, the second repeating unit shown in Equation II, and the third repeating unit shown in Equation III, which are connected in sequence. R1 is selected from CONHC2H4, COOC2H4 or CH2; R2 is selected from defunctionalized residues of hexamethylene diisocyanate. R3 is CH3; R4 is (CH2). n CH3, n is selected from 0.

2. A method for preparing cationic waterborne polyurethane, characterized in that, Includes the following steps: The prepolymer was prepared by mixing and reacting the diol hydroxybenzene and hexamethylene diisocyanate shown in Formula 1 with the cationic diol shown in Formula 2. The prepolymer was subjected to a chain extension reaction with polyethylene glycol to obtain cationic waterborne polyurethane. In this configuration, R1 is selected from CONHC2H4, COOC2H4, or CH2; R3 is CH3; and R4 is (CH2). n CH3, n is selected from 0; R0 is a chlorine atom; The cationic diol is bis(2-hydroxyethyl)dimethylammonium chloride.

3. The preparation method according to claim 2, characterized in that, The polyethylene glycol is selected from one or more polyethylene glycols with a number average molecular weight of 400-20000.

4. The preparation method according to claim 2, characterized in that, The molar ratio of the diol hydroxybenzene to the cationic diol is 10:1 to 1:1, and the molar ratio of the prepolymer to polyethylene glycol is 10:1 to 2:

1.

5. The preparation method according to any one of claims 2-4, characterized in that, The reaction for obtaining the prepolymer is carried out in the presence of a catalyst; the catalyst is selected from one or more organotin and tertiary amine catalysts.

6. The preparation method according to claim 5, characterized in that, Before reacting with diisocyanate, the diol hydroxybenzene and cationic diol are dehydrated under vacuum; the reaction temperature of the diol hydroxybenzene, cationic diol and diisocyanate is room temperature, and the reaction time is 2-4 h; the reaction temperature of the prepolymer with polyethylene glycol is 60-70 °C.

7. The application of the cationic waterborne polyurethane as described in claim 1 or the cationic waterborne polyurethane obtained by the preparation method according to any one of claims 2-6 as a wash-resistant hydrophilic finishing agent for polyester.

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