A kind of water-based polyurethane for inkjet and preparation method thereof

Abstract

The present application relates to the technical field of printing coatings, and specifically discloses a water-based polyurethane for inkjet and a preparation method thereof. The water-based polyurethane for inkjet includes polycarbonate polyol, polyisocyanate, organic fluorine-modified cardanol, acrylate monomer, dimethylol propionic acid, acetone, chain extender, neutralizer, catalyst, and deionized water; wherein, the raw materials for preparing organic fluorine-modified cardanol include fluorine-containing acrylate, cardanol, and initiator. Through the polymerization reaction between the unsaturated carbon-carbon double bonds in the cardanol molecule and the unsaturated carbon-carbon double bonds in the fluorine-containing acrylate, the phenolic hydroxyl group in the cardanol molecule is combined with the polyisocyanate to improve the water resistance of the water-based polyurethane, and through the synergistic effect of the acrylate monomer and the organic fluorine-modified cardanol, the water resistance of the water-based polyurethane is further improved.

Description

Technical Field

[0001] The invention relates to the technical field of printing coatings, and in particular to an inkjet water-based polyurethane and a preparation method thereof. Background Art

[0002] Waterborne polyurethane uses water instead of organic solvents as the dispersion medium. It is a green and environmentally friendly polymer material that is non-flammable, has little odor, is easy to modify, and has excellent mechanical properties. It is widely used in adhesives, inks, leather finishing agents and other industries.

[0003] The composition of waterborne polyurethane mainly includes polyols, polyisocyanates, hydrophilic chain extenders, salt formers, catalysts, etc. Among them, polyols and polyisocyanates are the basic components of waterborne polyurethane, forming the flexible segments and rigid segments of polyurethane respectively. There are many combinations of alternating arrangement between flexible segments and rigid segments, which leads to differences in material properties and can be applied to different usage scenarios. Chain extenders are important raw materials for waterborne polyurethane. By introducing chain extenders, certain characteristics of chain extender molecules can be introduced into the main chain of polyurethane, thereby improving the performance of polyurethane.

[0004] Although waterborne polyurethane has many advantages, its performance and application areas are still limited compared with traditional solvent-based polyurethane. Due to the linear structure of the overall molecular chain of waterborne polyurethane and the introduction of hydrophilic chain extenders, the water-borne polyurethane has poor water resistance, causing the product to become blurred or faded when exposed to water during use, affecting the product's aesthetics and clarity. Summary of the invention

[0005] In order to improve the water resistance of waterborne polyurethane, the present application provides a waterborne polyurethane for inkjet and a preparation method thereof.

[0006] In the first aspect, the present application provides an inkjet water-based polyurethane, which adopts the following technical solution:

[0007] A water-based polyurethane for inkjet, comprising the following raw materials in parts by weight:

[0008] 40-50 parts of polycarbonate polyol;

[0009] 50-60 parts of polyisocyanate;

[0010] 4-6 parts of organic fluorine-modified cardanol;

[0011] 3-5 parts of acrylate monomer;

[0012] 3-5 parts of dimethylolpropionic acid;

[0013] 25-35 parts of acetone;

[0014] 2 to 5 parts of chain extender;

[0015] 0.5-1.5 parts of neutralizing agent;

[0016] Catalyst 0.1-0.3 parts;

[0017] 50-60 parts of deionized water;

[0018] The raw materials for preparing the organic fluorine-modified cardanol include fluorine-containing acrylate, cardanol and an initiator, and the weight ratio of the fluorine-containing acrylate to cardanol is 3:(1.4-1.8).

[0019] By adopting the above device, polycarbonate polyol is used as the soft segment in waterborne polyurethane, and the carbonate group in its molecule has good hydrolysis resistance. Fluorinated acrylate is combined with part of isocyanate groups to modify the waterborne polyurethane, which is beneficial to improve the water resistance of the waterborne polyurethane. The unsaturated carbon-carbon double bonds in the cardanol molecule are polymerized with the unsaturated carbon-carbon double bonds in the fluorinated acrylate. The phenolic hydroxyl groups in the cardanol molecule are combined with polyisocyanates, which is helpful to improve the dispersibility and stability of the waterborne polyurethane. Through the synergistic effect of the acrylate monomer, the water resistance and adhesion of the waterborne polyurethane are significantly improved. At the same time, the long side chain of cardanol provides flexibility, so that the ink coating formed by the waterborne polyurethane is not easy to crack. In addition, dimethylolpropionic acid acts as a hydrophilic chain extender, and the hydroxyl group in the molecule reacts with the isocyanate group to be embedded in the molecular skeleton of the polyurethane. However, the carboxyl group in the dimethylolpropionic acid molecule basically does not participate in the reaction due to the steric effect. After the prepolymerization reaction is completed, a salt is generated through a neutralization reaction, which makes the synthesized polyurethane hydrophilic, reduces the mutual entanglement between molecular chains, and also reduces the cross-sectional tension of the system, which is beneficial to the fine dispersion of the polymer phase, increases the number of emulsion particles, and reduces the particle size accordingly.

[0020] Preferably, the fluorine-containing acrylate includes one or both of hexafluorobutyl methacrylate and octafluoropentyl methacrylate.

[0021] By adopting the above-mentioned device, fluorinated acrylate is introduced into waterborne polyurethane, which can eliminate the problem of decreased water resistance caused by improving the hydrophilicity of polyurethane. Among them, the organic fluorine unit migrates to the surface of the film, and the internal pressure of the polymer as a whole is significantly reduced, giving the waterborne polyurethane low surface energy, compatibility, and stability, thereby improving the water-borne polyurethane's water resistance.

[0022] Preferably, the polyisocyanate includes one or both of dicyclohexylmethane diisocyanate and isophorone diisocyanate.

[0023] By adopting the above device, the reaction activity of -NCO in methylcyclohexane diisocyanate and isophorone diisocyanate is lower than that of aromatic -NCO, and the stability is good. In addition, the molecule has a cycloalkane structure, and the cured network structure has good strength.

[0024] Preferably, the acrylic acid ester monomer includes one or both of hydroxyethyl methacrylate and hydroxyethyl acrylate.

[0025] By adopting the above device, hydroxyethyl methacrylate, hydroxyethyl acrylate and organic fluorine-modified cardanol work together to make the waterborne polyurethane have good adhesion and make the waterborne polyurethane emulsion have a suitable curing time. Among them, the hydroxyl groups contained in hydroxyethyl methacrylate and hydroxyethyl acrylate can cross-link with polyurethane, and the increase in the degree of cross-linking improves the viscosity of the waterborne polyurethane to a certain extent, thereby improving the adhesion of the waterborne polyurethane.

[0026] Preferably, the catalyst is one or both of organic zirconium and organic bismuth.

[0027] By adopting the above-mentioned device, organic zirconium and organic bismuth have higher catalytic activity for -NCO / -OH reaction, reduce the side reaction of -NCO and water, reduce the generation of CO2, thereby reducing the generation of bubbles in the product and improving the mechanical properties. In addition, organic zirconium and organic bismuth are both environmentally friendly catalysts, which are safer during handling and use, and are conducive to reducing the impact on the environment.

[0028] Preferably, the chain extender includes one or more of ethylenediamine, ethanolamine and diethanolamine.

[0029] By adopting the above device, since the excess isocyanate groups will react with water to form polyurea, using an appropriate amount of ethylenediamine to react with the excess isocyanate groups can maintain a suitable cross-linking degree in the polyurethane molecules, improve the flexibility of the polyurethane chain segments, and reduce the particle size; ethanolamine and diethanolamine have two functional groups, hydroxyl and amino, and have dual reactivity, which can better adjust the ratio of soft segments to hard segments in the polyurethane, so that the water-based polyurethane maintains suitable hardness and flexibility.

[0030] Preferably, the neutralizing agent is one or more of triethylamine, sodium hydroxide and sodium carbonate.

[0031] By adopting the above device, triethylamine, sodium hydroxide and sodium carbonate react with the acidic groups in the polyurethane to generate water-soluble salts, which are helpful to improve the stability of the water-based polyurethane emulsion.

[0032] In the second aspect, the present application provides a method for preparing water-based polyurethane for inkjet using the following technical solution:

[0033] A method for preparing water-based polyurethane for inkjet, comprising the following steps:

[0034] (1) weighing the raw materials according to the composition ratio, adding the polyisocyanate and the catalyst under the protection of nitrogen after the polycarbonate polyol is dehydrated, heating and stirring, slowly raising the temperature to, and reacting for 2-3 hours;

[0035] (2) adding dimethylolpropionic acid and organic fluorine-modified cardanol and reacting for 3-4 hours;

[0036] (3) adding a neutralizing agent to react for 10 to 15 minutes, and then adding deionized water for high-speed dispersion;

[0037] (4) Add chain extender and acrylate monomer, maintain the temperature at 80-90°C, react for 1-2 hours, and obtain waterborne polyurethane.

[0038] Preferably, acetone is added in both steps (2) and (3), and the acetone is removed by vacuum in step (4).

[0039] Preferably, the preparation method of the organic fluorine-modified cardanol is:

[0040] The fluorinated acrylate is heated to 50-60° C., cardanol is added, followed by methyl ether, and reacted for 1.5-3 hours under the catalytic action of the initiator. The methyl ether is finally removed by distillation, and after the reaction is complete, it is cooled to room temperature to obtain organic fluorine-modified cardanol; the initiator is AIBN.

[0041] By adopting the above-mentioned device, the water-based polyurethane prepared in the present application is used in ink, which helps to improve the water resistance of the ink, reduce the problem of blurring or fading of the product when it encounters water during use, and improve the aesthetics and clarity of the product. In addition, the introduction of nitrogen during the preparation of the water-based polyurethane can reduce the oxidation of unsaturated bonds, and acetone allows the reaction system to maintain a suitable viscosity, so as to better control the prepolymer viscosity and dispersion viscosity, thereby controlling the reaction rate. In addition, since acetone has a low boiling point, it is easy to remove in subsequent treatments.

[0042] This application has the following beneficial effects:

[0043] 1. In the present application, polycarbonate polyol is used as the soft segment in waterborne polyurethane, and the carbonate group in its molecule has good hydrolysis resistance. Fluorinated acrylate is combined with part of isocyanate group to modify waterborne polyurethane, which is beneficial to improve the water resistance of waterborne polyurethane. The unsaturated carbon-carbon double bond in the cardanol molecule is polymerized with the unsaturated carbon-carbon double bond in the fluorinated acrylate. The phenolic hydroxyl group in the cardanol molecule is combined with polyisocyanate, which is helpful to improve the dispersibility and stability of waterborne polyurethane. Through the synergistic effect of acrylate monomer, the water resistance and adhesion of waterborne polyurethane are significantly improved. At the same time, the long side chain of cardanol provides flexibility, so that the ink coating formed by waterborne polyurethane is not easy to crack. In addition, dimethylolpropionic acid acts as a hydrophilic chain extender, and the hydroxyl group in the molecule reacts with the isocyanate group to be embedded in the molecular skeleton of the polyurethane. However, the carboxyl group in the dimethylolpropionic acid molecule basically does not participate in the reaction due to the steric effect. After the prepolymerization reaction is completed, a salt is generated through a neutralization reaction, which makes the synthesized polyurethane hydrophilic, reduces the mutual entanglement between molecular chains, and also reduces the cross-sectional tension of the system, which is beneficial to the fine dispersion of the polymer phase, increases the number of emulsion particles, and reduces the particle size accordingly.

[0044] 2. In the present application, the synergistic effect of hydroxyethyl methacrylate, hydroxyethyl acrylate and organic fluorine-modified cardanol makes the waterborne polyurethane have good adhesion and makes the waterborne polyurethane emulsion have a suitable curing time. Among them, the hydroxyl groups contained in hydroxyethyl methacrylate and hydroxyethyl acrylate can cross-link with polyurethane, and the increase in the degree of cross-linking improves the viscosity of the waterborne polyurethane to a certain extent, thereby improving the adhesion of the waterborne polyurethane. DETAILED DESCRIPTION

[0045] Preparation Example

[0046] Preparation Example 1

[0047] Preparation of organic fluorine-modified cardanol:

[0048] 30 g of hexafluorobutyl methacrylate was heated to 50°C, 14 g of cardanol was added, followed by 10 g of methyl ether, and reacted for 1.5 h under the catalysis of 0.5 g of AIBN. The methyl ether was finally removed by distillation, and after the reaction was complete, the mixture was cooled to room temperature to obtain organic fluorine-modified cardanol.

[0049] Preparation Example 2

[0050] Preparation of organic fluorine-modified cardanol:

[0051] 30 g of hexafluorobutyl methacrylate was heated to 55°C, 16 g of cardanol was added, followed by 10 g of methyl ether, and reacted for 2 h under the catalysis of 0.5 g of AIBN. The methyl ether was finally removed by distillation, and after the reaction was complete, it was cooled to room temperature to obtain organic fluorine-modified cardanol.

[0052] Preparation Example 3

[0053] Preparation of organic fluorine-modified cardanol:

[0054] Heat 30 g of octafluoropentyl methacrylate to 60°C, add 18 g of cardanol, then add 10 g of methyl ether, and react for 3 hours under the catalysis of 0.5 g of AIBN. Finally, remove the methyl ether by distillation, and cool to room temperature after the reaction is complete to obtain organic fluorine-modified cardanol.

[0055] Preparation Example 4

[0056] Preparation of organic fluorine-modified cardanol:

[0057] Heat 30 g of trifluoroethyl methacrylate to 55° C., add 16 g of cardanol, then add 10 g of methyl ether, and react for 2 h under the catalysis of 0.5 g of AIBN. Finally, remove the methyl ether by distillation, and cool to room temperature after the reaction is complete to obtain organic fluorine-modified cardanol.

[0058] Example

[0059] Example 1

[0060] A water-based polyurethane for inkjet, comprising the following raw materials:

[0061] Polycarbonate polyol: 400g;

[0062] Isophorone diisocyanate: 500g;

[0063] Organic fluorine-modified cardanol: 40 g, wherein the organic fluorine-modified cardanol is the organic fluorine-modified cardanol prepared in Preparation Example 1;

[0064] Hydroxyethyl methacrylate: 30g;

[0065] Dimethylolpropionic acid: 30g;

[0066] Acetone: 250g;

[0067] Ethanolamine: 20g;

[0068] Triethylamine: 5g;

[0069] Organic zirconium: 1g;

[0070] Deionized water: 500g.

[0071] The molecular weight of the polycarbonate polyol was 2000, and the hydroxyl value was 58 mgKOH / g.

[0072] The preparation method of waterborne polyurethane in this embodiment includes the following steps:

[0073] (1) weighing the raw materials according to the composition ratio, adding isophorone diisocyanate and organic zirconium to the dehydrated polycarbonate polyol under the protection of nitrogen, heating and stirring, slowly raising the temperature to, and reacting for 2 hours;

[0074] (2) adding dimethylolpropionic acid and organic fluorine-modified cardanol and reacting for 3 hours;

[0075] (3) adding triethylamine to neutralize for 10 min, and then adding deionized water for high-speed dispersion;

[0076] (4) Add ethanolamine and hydroxyethyl methacrylate, maintain the temperature at 80°C, and react for 1 hour to obtain waterborne polyurethane.

[0077] Example 2

[0078] Polycarbonate polyol: 450g;

[0079] Isophorone diisocyanate: 550g;

[0080] Organic fluorine-modified cardanol: 50 g, wherein the organic fluorine-modified cardanol is the organic fluorine-modified cardanol prepared in Preparation Example 1; Hydroxyethyl methacrylate: 30 g;

[0081] Dimethylolpropionic acid: 40g;

[0082] Acetone: 300g;

[0083] Ethylenediamine: 30g;

[0084] Sodium hydroxide: 10g;

[0085] Organic bismuth: 2g;

[0086] Deionized water: 550g.

[0087] The molecular weight of the polycarbonate polyol was 2000, and the hydroxyl value was 58 mgKOH / g.

[0088] (1) weighing the raw materials according to the composition ratio, adding isophorone diisocyanate and organic bismuth to the dehydrated polycarbonate polyol under the protection of nitrogen, heating and stirring, slowly raising the temperature to, and reacting for 2.5 hours;

[0089] (2) adding dimethylolpropionic acid and organic fluorine-modified cardanol and reacting for 3.5 hours;

[0090] (3) adding sodium hydroxide to neutralize and react for 13 min, and then adding deionized water for high-speed dispersion;

[0091] (4) Add ethylenediamine and hydroxyethyl methacrylate, maintain the temperature at 85°C, and react for 1.5 hours to obtain waterborne polyurethane.

[0092] Example 3

[0093] Polycarbonate polyol: 500g;

[0094] Isophorone diisocyanate: 600g;

[0095] Organic fluorine-modified cardanol: 60 g, wherein the organic fluorine-modified cardanol is the organic fluorine-modified cardanol prepared in Preparation Example 1; Hydroxyethyl methacrylate: 30 g;

[0096] Dimethylolpropionic acid: 50g;

[0097] Acetone: 350g;

[0098] Diethanolamine: 50g;

[0099] Sodium carbonate: 15g;

[0100] Organic zirconium: 3g;

[0101] Deionized water: 600g.

[0102] The molecular weight of the polycarbonate polyol was 2000, and the hydroxyl value was 58 mgKOH / g.

[0103] (1) weighing the raw materials according to the composition ratio, adding isophorone diisocyanate and organic zirconium to the dehydrated polycarbonate polyol under the protection of nitrogen, heating and stirring, slowly raising the temperature to, and reacting for 3 hours;

[0104] (2) adding dimethylolpropionic acid and organic fluorine-modified cardanol and reacting for 4 hours;

[0105] (3) adding sodium carbonate to neutralize and react for 15 min, and then adding deionized water for high-speed dispersion;

[0106] (4) Add diethanolamine and hydroxyethyl methacrylate, maintain the temperature at 90°C, and react for 2 hours to obtain waterborne polyurethane.

[0107] Example 4

[0108] The difference between this embodiment and embodiment 2 is that the organic fluorine-modified cardanol adopts an equal amount of the organic fluorine-modified cardanol prepared in preparation example 2.

[0109] Example 5

[0110] The difference between this embodiment and embodiment 2 is that the organic fluorine-modified cardanol adopts an equal amount of the organic fluorine-modified cardanol prepared in preparation example 3.

[0111] Example 6

[0112] The difference between this embodiment and embodiment 2 is that the organic fluorine-modified cardanol adopts an equal amount of the organic fluorine-modified cardanol prepared in preparation example 4.

[0113] Comparative Example

[0114] Comparative Example 1

[0115] A waterborne polyurethane, which differs from Example 2 in that an equal amount of polycarbonate polyol is used instead of organic fluorine-modified cardanol.

[0116] Comparative Example 2

[0117] A waterborne polyurethane, which differs from Example 2 in that an equal amount of cardanol is used instead of organic fluorine-modified cardanol.

[0118] Comparative Example 3

[0119] A waterborne polyurethane, which differs from Example 2 in that an equal amount of hexafluorobutyl methacrylate is used to replace the organic fluorine-modified cardanol.

[0120] Comparative Example 4

[0121] A waterborne polyurethane, which is different from Example 2 in that hydroxyethyl methacrylate is not added.

[0122] Performance testing

[0123] 1. Water resistance test

[0124] The effects of organic fluorine-modified cardanol on the water resistance of ink in Examples 1 to 6 and Comparative Examples 1 to 4 were tested. Water-based polyurethane was printed on cloth by inkjet, and then the cloth was immersed in water for 24 hours to observe whether the coating film fell off.

[0125] 2.Solvent resistance test

[0126] The effects of organic fluorine-modified cardanol on the solvent resistance of ink in Examples 1 to 6 and Comparative Examples 1 to 4 were tested. Water-based polyurethane was printed on cloth by inkjet, and then the cloth was immersed in ethanol for 24 hours to observe whether the coating film fell off.

[0127] 3. Adhesion test

[0128] The effect of organic fluorine-modified cardanol on ink adhesion in test examples 1 to 6 and comparative examples 1 to 4 was tested. The test was carried out with reference to GB / T9286-2021 "Scratch test for paints and varnishes", and the test results were divided into 0-5 levels, the lower the level, the better the adhesion; in this application, the adhesion of 0-1 level is qualified.

[0129] 4. Emulsion stability test

[0130] The effects of organic fluorine-modified cardanol on the stability of aqueous polyurethane emulsions in Examples 1 to 6 and Comparative Examples 1 to 4 were tested. The stability of polyurethane was simulated by a centrifuge accelerated sedimentation test. The samples of each example and comparative example were placed in a centrifuge and centrifuged at a speed of 3000 r / min. The samples were observed every 15 minutes and the time when precipitation occurred was recorded. Note: When precipitation occurs, the time when precipitation occurs is not counted as the stability time.

[0131] 5. Flexibility test

[0132] According to GB / T6742-2007 "Bending test for paints and varnishes (cylindrical mandrel)", the flexibility of the coating films formed after curing the waterborne polyurethane in the above Examples 1 to 6 and Comparative Examples 1 to 4 was tested, and the minimum radius of the mandrel that the coating films could withstand was recorded. The smaller the radius of the mandrel, the better the flexibility of the coating film. At room temperature (25°C), the flexibility of the coating film is qualified by the mandrel radius ≤ 3mm.

[0133] 6. Emulsion particle size test

[0134] The effect of organic fluorine-modified cardanol on the particle size of aqueous polyurethane emulsion in Examples 1 to 6 and Comparative Examples 1 to 4 was tested. Under a 26° C. environment, a laser scattering angle of 90° was selected and the analysis was performed using a corresponding instrument.

[0135] Table 1: Performance test data

[0136]

[0137] Combining the description of Example 2 and Example 6 of this application and the data in Table 1, it can be seen that the length and structure of the fluorocarbon chain in the molecular structure of the fluorine-containing acrylate in the organic fluorine-modified cardanol have an impact on the water resistance and solvent resistance of the waterborne polyurethane. Among them, the shorter the length of the fluorocarbon chain, the greater the impact on the water resistance and solvent resistance of the waterborne polyurethane. On the contrary, the longer the length of the fluorocarbon chain, the more it helps to improve the water resistance and solvent resistance of the waterborne polyurethane and improve the adhesion.

[0138] Combining the present application's Example 2 and Comparative Example 1 and the data in Table 1, it can be seen that when preparing the waterborne polyurethane of the present application, if organic fluorine cardanol is not added, the water resistance, solvent resistance and adhesion of the waterborne polyurethane will decrease, and the stability of the waterborne polyurethane emulsion will be affected, and the flexibility of the waterborne polyurethane will decrease. On the contrary, adding organic fluorine-modified cardanol will significantly improve the water resistance and adhesion of the waterborne polyurethane, and at the same time improve the stability of the waterborne polyurethane emulsion.

[0139] Combining the present application's Example 2 and Comparative Example 2 and the data in Table 1, it can be seen that when preparing the waterborne polyurethane of the present application, cardanol is used alone in combination with polyisocyanate, and cardanol is not modified by organic fluorine. The waterborne polyurethane has no obvious effect on improving water resistance, solvent resistance and adhesion, and also affects the stability of the waterborne polyurethane emulsion, causing the flexibility of the waterborne polyurethane to decrease. On the contrary, modifying cardanol by organic fluorine can significantly improve the water resistance and adhesion of the waterborne polyurethane, while improving the stability of the waterborne polyurethane emulsion.

[0140] Combining the present invention's Example 2 and Comparative Example 3 with the data in Table 1, it can be seen that when the waterborne polyurethane of the present invention is prepared, the waterborne polyurethane is modified by combining hexafluorobutyl methacrylate with isocyanate groups alone, and the effect after modification is not obvious. Therefore, the lack of cardanol will affect the water resistance and solvent resistance of the waterborne polyurethane and the adhesion of the waterborne polyurethane coating.

[0141] Combining Example 2 and Comparative Example 4 of the present application with the data in Table 1, it can be seen that the acrylate monomer will affect the water resistance, solvent resistance, adhesion, emulsion stability, flexibility and emulsion particle size of the waterborne polyurethane. Therefore, the acrylate monomer and the organic fluorine-modified cardanol need to work together to improve the performance of the waterborne polyurethane and make the waterborne polyurethane emulsion have a suitable curing time, and the hydroxyl groups in the acrylate monomer molecules cross-link with the waterborne polyurethane to maintain a suitable viscosity in the reaction system and improve the adhesion of the waterborne polyurethane.

[0142] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A water-based polyurethane for inkjet, characterized in that: By weight, it contains the following components: 40-50 parts of polycarbonate polyol; 50-60 parts of polyisocyanate; 4-6 parts of organic fluorine-modified cardanol; 3-5 parts of acrylate monomer; 3-5 parts of dimethylol propionic acid; 25-35 parts of acetone; Chain extender 2~5 parts; Neutralizer 0.5~1.5 parts; Catalyst 0.1~0.3 parts; 50~60 parts of deionized water; The acrylic acid ester monomer includes one or two of hydroxyethyl methacrylate and hydroxyethyl acrylate; The raw materials for preparing the organic fluorine-modified cardanol include fluorine-containing acrylate, cardanol and an initiator, and the weight ratio of the fluorine-containing acrylate to cardanol is 3: (1.4-1.8); The preparation method of the organic fluorine-modified cardanol is: The fluorinated acrylate is heated to 50-60°C, cardanol is added, and then methyl ether is added, and the reaction is carried out for 1.5-3 hours under the catalytic action of the initiator, and the methyl ether is finally removed by distillation. After the reaction is complete, the methyl ether is cooled to room temperature to obtain organic fluorine-modified cardanol; The initiator is AIBN.

2. The water-based polyurethane for inkjet according to claim 1, characterized in that: The fluorine-containing acrylate includes one or both of hexafluorobutyl methacrylate and octafluoropentyl methacrylate.

3. The water-based polyurethane for inkjet according to claim 1, characterized in that: The polyisocyanate includes one or both of dicyclohexylmethane diisocyanate and isophorone diisocyanate.

4. The water-based polyurethane for inkjet according to claim 1, characterized in that: The catalyst is one or both of organic zirconium and organic bismuth.

5. The water-based polyurethane for inkjet according to claim 1, characterized in that: The chain extender includes one or more of ethylenediamine, ethanolamine and diethanolamine.

6. The water-based polyurethane for inkjet according to claim 1, characterized in that: The neutralizing agent is one or more of triethylamine, sodium hydroxide and sodium carbonate.

7. The method for preparing water-based polyurethane for inkjet according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) Weighing the raw materials according to the composition ratio, adding polyisocyanate and catalyst under nitrogen protection after dehydration of polycarbonate polyol, heating and stirring, slowly raising the temperature to 80-90°C, and reacting for 2-3h; (2) Add dimethylolpropionic acid and organic fluorine-modified cardanol and react for 3-4 hours; (3) Add neutralizer and react for 10-15 minutes, then add deionized water for high-speed dispersion; (4) Add chain extender and acrylate monomer, maintain the temperature at 80-90°C, and react for 1-2 hours to obtain waterborne polyurethane.

8. The method for preparing water-based polyurethane for inkjet according to claim 7, characterized in that: Acetone is added in both steps (2) and (3), and the acetone is removed by vacuum in step (4).

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