Bio-based polyurethane acrylic resin with low water absorption rate and preparation method thereof

Abstract

The invention relates to the technical field of synthetic resin, in particular to low-water-absorption bio-based polyurethane acrylic resin, which is prepared from the following raw materials in parts by weight: 55 to 70 parts of silane modified bio-based polyol, 8 to 18 parts of aliphatic diisocyanate, 5 to 10 parts of end-capping reagent, 0.1 to 0.4 part of catalyst, 0.2 to 0.5 part of antioxidant and 10 to 15 parts of viscosity modifier. The invention also discloses a preparation method of the bio-based polyurethane acrylic resin with low water absorption. By introducing the hydrophobic modified bio-based polyol, the synthetic resin disclosed by the invention has excellent low water absorption performance; the bio-based dihydric alcohol with a flexible long alkyl chain structure is introduced, so that the synthetic resin has the advantages of good compatibility, rapid photocuring, excellent mechanical property, flexibility, super-hydrophobic property and the like, and can be widely applied to the fields of electronic packaging, waterproof coatings, adhesives, high-end printing ink and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of synthetic resins, and particularly to a bio-based polyurethane acrylate resin with low water absorption rate. Background Art

[0002] Polyurethane acrylate is a high-performance photocurable material that combines the dual characteristics of polyurethane (PU) and acrylate. Among them, the low water absorption rate polyurethane acrylate resin has excellent water resistance, mechanical properties and chemical stability, and its low water absorption characteristics make it have important applications in the fields of electronic packaging, waterproof coatings, adhesives, high-end inks, etc.

[0003] However, the photocurable raw materials of polyurethane acrylate have their own limitations. In the case of high water resistance requirements, the water absorption rate needs to be less than 0.5% or lower. Ordinary polyurethane acrylate is difficult to meet the requirements: the water absorption rate of conventional polyether-based polyurethane acrylate is greater than 1%, and the water absorption rate of polybutadiene-based polyurethane acrylate is about 0.5%, but its raw material price is expensive, and its compatibility with other polyester / ether-based polyurethane systems is very poor, which limits its wide application. In addition, polyols, as one of the important raw materials for synthesizing polyurethane acrylate, conventional polyether polyols, polyester polyols, polybutadiene polyols mainly come from petroleum-based resources, and a large amount of carbon emissions will be generated during the production process, putting pressure on the environment. In the bio-based system, the water absorption rate of ordinary polylactic acid-based polyurethane acrylate is greater than 2%, and the water absorption rate of polyester-based polyurethane acrylate is greater than 2%, which is difficult to meet the high water resistance requirements. Therefore, it is of great significance and broad application prospects to develop a high-toughness bio-based polyurethane acrylate with low water absorption rate. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a bio-based polyurethane acrylate resin with low water absorption rate, which solves the problems of high water absorption rate and insufficient flexibility of the bio-based polyurethane acrylate resin in the prior art.

[0005] The solution adopted by the present invention to solve its technical problem is: a bio-based polyurethane acrylate resin with low water absorption rate, including 100 parts by weight of the following raw materials: 55 - 70 parts of silane-modified bio-based polyol, 8 - 18 parts of aliphatic diisocyanate, 5 - 10 parts of capping agent, 0.1 - 0.4 part of catalyst, 0.2 - 0.5 part of antioxidant, 10 - 15 parts of viscosity regulator, wherein the silane-modified bio-based polyol is prepared from aromatic diisocyanate, highly hydrophobic bio-based polyol, high-toughness polyol, catalyst, antioxidant according to precise measurement and the following steps:

[0006] a. Set the dosage of the aromatic diisocyanate to 100 moles. Charge 100 moles of the aromatic diisocyanate into the reaction kettle, and then add 0.01 - 0.05 moles of catalyst and 0.01 - 0.05 moles of antioxidant into the reaction kettle. Heat to 30°C and stir to mix evenly;

[0007] b. Then, slowly and uniformly drip 85 - 95 moles of highly hydrophobic bio - based polyol into the reaction kettle, and slowly heat to raise the material temperature to 40 - 50°C, and react for 2 h;

[0008] c. When the NCO value in the system drops to the theoretical value, add 5 - 15 moles of high - toughness polyol, react for 3 - 5 h, and control the final NCO value of the system to be lower than 0.06%;

[0009] Among them, the highly hydrophobic bio - based polyol is one or more of castor oil polyol, soybean oil polyol, palm oil polyol, and rapeseed oil polyol; the high - toughness polyol is one or more of mono - terminal dihydroxy siloxane and linear dihydroxy siloxane; the antioxidant is a phenolic antioxidant; the catalyst is a tin - based catalyst.

[0010] As a preferred technical solution of the present invention, the aromatic diisocyanate is selected from at least one of 3,3'-dimethyl diphenylmethane - 4,4'-diisocyanate, diphenylmethane - 4,4'-diisocyanate, dimethylbiphenyl diisocyanate, 2,6 - toluene diisocyanate, 2,4 - toluene diisocyanate, p - phenylene diisocyanate, m - phenylene diisocyanate, and 1,3 - diisocyanatomethylbenzene.

[0011] As a preferred technical solution of the present invention, the aliphatic diisocyanate is selected from at least one of isophorone diisocyanate, hexamethylene diisocyanate, and 4,4 - diisocyanate dicyclohexylmethane.

[0012] As a preferred technical solution of the present invention, the high - toughness bio - based polyol is one or more of mono - terminal dihydroxy siloxane and linear dihydroxy siloxane, and the molecular weight of the high - toughness bio - based polyol is 300 - 1500 g / mol.

[0013] As a preferred technical solution of the present invention, the blocking agent is selected from at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and pentaerythritol triacrylate.

[0014] As a preferred technical solution of the present invention, the viscosity regulator is selected from at least one of polyethylene wax, oxidized polyethylene wax, and polypropylene wax.

[0015] As a preferred technical solution of the present invention, the antioxidant is selected from at least one of pentaerythritol tetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], thiodiethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl 3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate, N,N'-hexane-1,6-diylbis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide), 3,3',3'',5,5',5''-hexakis(tert-butyl)-α,α',α''-(mesitylene-2,4,6-triyl)tris-p-cresol, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, ethylene bis(oxyethylene) bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate], 3,5-bis(1,1-dimethylethyl)-4-hydroxy-C7-C9 branched alkyl ester, 3,5-di-tert-butyl-4-hydroxycinnamic acid, hexamethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and 4,6-bis(octylthiomethyl)-o-cresol.

[0016] A preparation method of a bio-based polyurethane acrylate resin with low water absorption includes the following steps:

[0017] S1. Add 8-18 parts of aliphatic diisocyanate, 0.1-0.4 part of catalyst, and 0.2-0.5 part of antioxidant into a flask, pump dry air into the flask, and dropwise add 5-10 parts of capping agent at room temperature. After the dropping is completed, react for 10-30 min to prepare a prepolymer.

[0018] S2. Add 55-70 parts of self-made bio-based polyol to the prepolymer obtained in step S1 above, and react at 60°C - 90°C for 1-8 h to prepare a bio-based polyurethane acrylate resin with low water absorption.

[0019] As a preferred technical solution of the present invention, the dropping rate of the capping agent in S1 is 10-20 drops / min, and the reaction time is 10-20 min.

[0020] As a preferred technical solution of the present invention, the reaction temperature in S2 is 70°C - 80°C, and the reaction time is 2-4 h.

[0021] The technical effects of the present invention are as follows: Using vegetable oil-based polyols instead of petroleum-based polyols is green and environmentally friendly. By introducing hydrophobic bio-based polyols (such as castor oil, soybean oil, palm oil, rapeseed oil polyols, etc.), the bio-based polyurethane acrylate resin prepared by the present invention has excellent low water absorption performance; by introducing bio-based diols with flexible long alkyl chain structures, the bio-based polyurethane acrylate prepared by the present invention has advantages such as good compatibility, fast photocuring, excellent mechanical properties, flexibility, and superhydrophobic properties, and can be widely used in fields such as electronic packaging, waterproof coatings, adhesives, and high-end inks.

[0022] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly, it can be implemented according to the content of the description. And in order to make the above and other purposes, features, and advantages of the present invention more obvious and understandable, the following preferred embodiments are specifically given and described in detail as follows. Detailed implementation manners

[0023] In order to make the content of the present invention easier to be clearly understood, the present invention will be further described below according to specific embodiments.

[0024] It should be noted that unless otherwise specified, the meaning of "a plurality" is two or more.

[0025] A bio-based polyurethane acrylate resin with low water absorption includes the following raw materials in 100 parts by weight: 55 - 70 parts of silane-modified bio-based polyol, 8 - 18 parts of aliphatic diisocyanate, 5 - 10 parts of capping agent, 0.1 - 0.4 part of catalyst, 0.2 - 0.5 part of antioxidant, 10 - 15 parts of viscosity regulator, wherein the silane-modified bio-based polyol is prepared from aromatic diisocyanate, highly hydrophobic bio-based polyol, highly tough polyol, catalyst, and antioxidant by precise measurement according to the following steps:

[0026] a. Set the amount of aromatic diisocyanate to 100 moles, put 100 moles of aromatic diisocyanate into the reaction kettle, and then add 0.01 - 0.05 mole of catalyst and 0.01 - 0.05 mole of antioxidant into the reaction kettle, heat to 30 °C and stir to mix evenly;

[0027] b. Then uniformly drop 85 - 95 moles of highly hydrophobic bio-based polyol into the reaction kettle, and slowly heat to raise the material temperature to 40 - 50 °C, and react for 2 h;

[0028] c. When the NCO value in the system drops to the theoretical value, then add 5 - 15 moles of a small amount of highly tough polyol, react for 3 - 5 h, and control the final NCO value of the system to be lower than 0.06%;

[0029] Among them, the highly hydrophobic bio-based polyol is one or more of castor oil polyol, soybean oil polyol, palm oil polyol, and rapeseed oil polyol; the highly tough polyol is one or more of mono-terminal dihydroxy siloxane and linear dihydroxy siloxane; the antioxidant is a phenolic antioxidant; the catalyst is a tin-based catalyst.

[0030] Further, the aromatic diisocyanate is selected from at least one of 3,3'-dimethyl diphenylmethane-4,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, dimethylbiphenyl diisocyanate, 2,6-toluene diisocyanate, 2,4-toluene diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, and 1,3-diisocyanatomethylbenzene.

[0031] Further, the aliphatic diisocyanate is selected from at least one of isophorone diisocyanate, hexamethylene diisocyanate, and 4,4-diisocyanate dicyclohexylmethane.

[0032] Further, the highly tough polyol is one or more of mono-terminal dihydroxy siloxane and linear dihydroxy siloxane, and the molecular weight is 300-1500 g / mol.

[0033] Further, the capping agent is selected from at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and pentaerythritol triacrylate.

[0034] Further, the viscosity regulator is selected from at least one of polyethylene wax, oxidized polyethylene wax, and polypropylene wax.

[0035] Further, the antioxidant is selected from at least one of pentaerythritol tetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Irganox 1010), thiodiethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Irganox 1035), octadecyl 3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate (Irganox 1076), N,N'-hexane-1,6-diylbis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide) (Irganox 1098), 3,3',3'',5,5',5''-hexa-tert-butyl-a,a',a'-(mesitylene-2,4,6-triyl)triscresol (Irganox 1330), 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (Irganox 3114), ethylene bis(oxyethylene) bis-(3-(5-tert-butyl-4-hydroxy-m-tolyl)-propionate) (Irganox 245), 3,5-bis(1,1-dimethylethyl)-4-hydroxy-C7-C9 branched alkyl ester (Irganox 1135), 3,5-di-tert-butyl-4-hydroxycinnamic acid (Irganox 3125), hexamethylenebis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (Irganox 259), and 4,6-bis(octylthiomethyl)-o-cresol (Irganox 1520L).

[0036] Further, the catalyst is selected from at least one of dibutyltin dilaurate, stannous octoate, triethylenediamine, and bis(morpholino)diethyl ether.

[0037] A method for preparing a bio-based polyurethane acrylate resin with low water absorption, comprising the following steps:

[0038] S1. Add 8 - 18 parts of aliphatic diisocyanate, 0.1 - 0.4 parts of catalyst, and 0.2 - 0.5 parts of antioxidant into a flask, pump dry air into the flask, and dropwise add 5 - 10 parts of a terminator at room temperature. After the dropping is completed, react for 10 - 30 min to prepare a prepolymer;

[0039] S2. Add 55 - 70 parts of a self-made bio-based polyol to the prepolymer obtained in the above step S1, and react at 60°C - 90°C for 1 - 8 h to prepare a bio-based polyurethane acrylate resin with low water absorption.

[0040] Further, the dropping rate of the terminator in S1 is 10 - 20 drops / min, and the reaction time is 10 - 20 min.

[0041] Further, in S2, the reaction temperature is 70°C - 80°C, and the reaction time is 2 - 4 h.

[0042] Preparation Example 1

[0043] The modified bio - based polyol is prepared through the following steps:

[0044] The aromatic diisocyanate is selected as isophorone diisocyanate. Add 110 g of isophorone diisocyanate, 0.75 g of dibutyltin dilaurate, and 2.9 g of antioxidant 1035 into the reaction kettle, heat to 30°C and stir to mix evenly. Then, slowly drop 556 g of castor oil into the reaction kettle at a constant speed while introducing dry air, and slowly heat to raise the material temperature to 40 - 50°C. React for 2 h. When the NCO value drops to the theoretical value, add 93 g of mono - terminal dihydroxy siloxane, continue to heat up to 60 - 80°C, and react for 3 - 5 h. Control the final NCO value of the system to be lower than 0.06%. The highly hydrophobic bio - based polyol is castor oil, and the highly tough polyol is mono - terminal dihydroxy siloxane. The molar ratio of castor oil to mono - terminal dihydroxy siloxane is 6:1.

[0045] Preparation Example 2:

[0046] The modified bio - based polyol is prepared through the following steps:

[0047] Add 110 g of isophorone diisocyanate, 0.58 g of dibutyltin dilaurate, and 2.3 g of antioxidant 1035 into the reaction kettle, heat to 30°C and stir to mix evenly. Then, slowly drop 668 g of castor oil into the reaction kettle at a constant speed while introducing dry air, and slowly heat to raise the material temperature to 40 - 50°C. React for 2 h. When the NCO value drops to the theoretical value, add 37 g of mono - terminal dihydroxy siloxane, continue to heat up to 60 - 80°C, and react for 3 - 5 h. Control the final NCO value of the system to be lower than 0.06%. The highly hydrophobic bio - based polyol is castor oil, and the highly tough polyol is mono - terminal dihydroxy siloxane. The difference from Preparation Example 1 is that the molar ratio of castor oil to mono - terminal dihydroxy siloxane changes from 6:1 to 9:1.

[0048] Preparation Example 3:

[0049] The modified bio - based polyol is prepared through the following steps:

[0050] Add 110 g of isophorone diisocyanate, 0.45 g of dibutyltin dilaurate, and 1.8 g of antioxidant 1035 to a reaction kettle, heat to 30 °C and stir to mix evenly. Then, slowly add 556 g of castor oil to the reaction kettle while introducing dry air, and slowly heat to raise the material temperature to 40 - 50 °C. React for 2 h. When the NCO value drops to the theoretical value, add 149 g of polyester-based cashew shell oil, continue to heat up to 60 - 80 °C, and react for 3 - 5 h. Control the NCO value of the final system to be less than 0.06%. The highly hydrophobic bio-based polyol is castor oil, and the highly tough polyol is linear dihydroxysiloxane. The difference from Preparation Example 1 is that in Preparation Examples 3 and 4, the highly tough polyol selected is linear dihydroxysiloxane.

[0051] Preparation Example 4:

[0052] Add 110 g of isophorone diisocyanate, 0.55 g of dibutyltin dilaurate, and 2.2 g of antioxidant 1035 to a reaction kettle, heat to 30 °C and stir to mix evenly. Then, slowly add 668 g of castor oil to the reaction kettle while introducing dry air, and slowly heat to raise the material temperature to 40 - 50 °C. React for 2 h. When the NCO value drops to the theoretical value, add 59 g of linear dihydroxysiloxane, continue to heat up to 60 - 80 °C, and react for 3 - 5 h. Control the NCO value of the final system to be less than 0.06%. The highly hydrophobic bio-based polyol is castor oil, and the highly tough bio-based polyol is linear dihydroxysiloxane. The difference from Preparation Example 3 is that in Preparation Example 4, the molar ratio of castor oil to linear dihydroxysiloxane used changes from 6:1 to 9:1.

[0053] Example 1

[0054] A preparation method of a bio-based polyurethane acrylate resin with low water absorption, specifically including the following steps:

[0055] S1. Add 8 - 18 parts of isocyanate, 0.1 - 0.4 parts of dibutyltin dilaurate, and 0.2 - 0.5 parts of antioxidant 1035 to a flask, pump dry air into the flask, and add 5 - 10 parts of hydroxyethyl acrylate dropwise to prepare a prepolymer at 30 °C.

[0056] S2. Add 55 - 70 parts of the bio-based polyol prepared in Preparation Example 1 to the prepolymer in the above step S1, and react at 80 °C for 2 h to prepare a bio-based polyurethane acrylate resin with low water absorption.

[0057] Example 2

[0058] A preparation method of a bio-based polyurethane acrylate resin with low water absorption, different from Example 1 in that:

[0059] Add the bio-based polyol prepared in Preparation Example 2 to S2.

[0060] Example 3

[0061] A method for preparing a bio-based polyurethane acrylate resin with low water absorption rate, which is different from Example 1 in that:

[0062] Add the bio-based polyol prepared in Preparation Example 3 to S2.

[0063] Example 4

[0064] A method for preparing a bio-based polyurethane acrylate resin with low water absorption rate, which is different from Example 1 in that:

[0065] Add the bio-based polyol prepared in Preparation Example 4 to S2.

[0066] Comparative Example 1

[0067] A method for preparing a bio-based polyurethane acrylate resin, which is different from Example 1 in that:

[0068] Add bio-based polylactic acid polyol to S2.

[0069] Comparative Example 2

[0070] A method for preparing a polyurethane acrylate resin, which is different from Example 1 in that:

[0071] Add polybutadiene polyol to S2.

[0072] Test the dumbbell-shaped specimen strips (national standard type 2, 75×12.5×2 mm) of the same size prepared from the bio-based polyurethane acrylate resins prepared in Example 1, Example 2, Example 3, Example 4, Comparative Example 1, and Comparative Example 2, and obtain the data in the following table:

[0073]

[0074] It can be seen from the table that:

[0075] The water absorption rate of the specimen with bio-based polylactic acid polyol introduced is much greater than that of the modified bio-based polyol prepared by the present invention;

[0076] When the proportion of the highly hydrophobic bio-based polyol in the modified bio-based polyol prepared by the present invention is large, its water absorption rate gradually decreases, the elongation at break significantly decreases, the contact angle significantly decreases, the hardness increases, and the tensile strength increases;

[0077] The elongation at break of the specimen with polybutadiene polyol introduced is much smaller than that of the modified bio-based polyol prepared by the present invention;

[0078] When the proportion of high - toughness bio - based polyol in the self - made modified bio - based polyol of the present invention is large, its elongation at break increases significantly, the contact angle increases significantly, the hardness decreases, and the tensile strength decreases.

[0079] The present invention uses vegetable - oil - based polyol to replace petroleum - based polyol, which is green and environmentally friendly. By introducing hydrophobic bio - based polyols (such as castor oil, soybean oil, palm oil, rapeseed oil polyol, etc.), the bio - based polyurethane acrylate resin prepared by the present invention has excellent low - water - absorption performance; by introducing bio - based diols with flexible long alkyl - chain structures, the bio - based polyurethane acrylate prepared by the present invention has advantages such as good compatibility, rapid photocuring, excellent mechanical properties, flexibility, and super - hydrophobic properties, and can be widely used in fields such as electronic packaging, waterproof coatings, adhesives, and high - end inks.

[0080] Specifically, it has the following beneficial effects:

[0081] 1. By introducing the self - made silane - modified bio - based polyol structure, the present invention improves the hydrophobicity of the chain segment and provides a class of photocurable polyurethane acrylates with ultra - low water absorption.

[0082] 2. The self - made polyol of the present invention is prepared with plant - based oil as the main raw material, which is green and environmentally friendly.

[0083] 3. The synthesis process of the present invention is simple. During the synthesis process, no organic solvents are used, no special equipment is required, it is environmentally friendly, easy to control, has good experimental repeatability, and the resin has stable storage.

[0084] 4. The bio - based polyurethane acrylate resin prepared by the present invention has good mechanical properties and super - hydrophobic properties after photocuring. Its elongation at break is between 108 - 210%, and the contact angle is greater than or equal to 130°.

[0085] 5. Compared with butadiene - based polyurethane acrylate resin, the bio - based polyurethane acrylate resin provided by the present invention has better compatibility with conventional polyester / ether - type polyurethane acrylate systems, providing a basis for compounding with other polyurethane materials to improve the comprehensive performance of the formulated materials.

[0086] 6. Polyurethane acrylate resin is prone to hydrolysis. By introducing hydrophobic bio - based polyols, its water absorption rate is lower than 0.5%, and the degree of hydrolysis is small, which is conducive to maintaining the performance of polyurethane acrylate resin.

[0087] The above embodiments are only the preferred embodiments of the present invention and cannot be used to limit the protection scope of the present invention. Any non - substantial changes and modifications made by those skilled in the art on the basis of the invention belong to the protection scope of the present invention.

Claims

1. A bio-based polyurethane acrylic resin with low water absorption, characterized in that: The invention comprises 100 parts by weight of the following raw materials: 55-70 parts by weight of silane-modified bio-based polyol, 8-18 parts by weight of aliphatic diisocyanate, 5-10 parts by weight of end-capping agent, 0.1-0.4 parts by weight of catalyst, 0.2-0.5 parts by weight of antioxidant, and 10-15 parts by weight of viscosity modifier, wherein the silane-modified bio-based polyol is prepared by accurately measuring aromatic diisocyanate, highly hydrophobic bio-based polyol, highly tough polyol, catalyst, and antioxidant according to the following steps: a. Setting the amount of the aromatic diisocyanate to 100 mol, adding 100 mol of the aromatic diisocyanate into a reactor, adding 0.01-0.05 mol of the catalyst and 0.01-0.05 mol of the antioxidant to the reactor, heating to 30 ° C and stirring to mix evenly; b. Then, 85-95 mol of the highly hydrophobic bio-based polyol is added dropwise to the reactor at a uniform rate, and the material temperature is slowly heated to 40-50° C. and reacted for 2 h; c. When the NCO value in the system drops to the theoretical value, 5-15 mol of the high toughness polyol is added and reacted for 3-5 hours to control the NCO value of the final system to be less than 0.06%; The highly hydrophobic bio-based polyol is one or more of castor oil polyol, soybean oil polyol, palm oil polyol, and rapeseed oil polyol; the high-toughness polyol is one or more of single-end dihydroxy siloxane and linear dihydroxy siloxane; the antioxidant is a phenolic antioxidant; and the catalyst is a tin catalyst.

2. The bio-based polyurethane acrylic resin according to claim 1, characterized in that: The aromatic diisocyanate is at least one selected from 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, dimethylbiphenyl diisocyanate, 2,6-toluene diisocyanate, 2,4-toluene diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate and 1,3-diisocyanatotoluene.

3. The bio-based polyurethane acrylic resin according to claim 1, characterized in that: The aliphatic diisocyanate is selected from at least one of isophorone diisocyanate, hexamethylene diisocyanate and 4,4-diisocyanate dicyclohexylmethane.

4. The bio-based polyurethane acrylic resin according to claim 1, characterized in that: The high-toughness polyol is one or more of single-end dihydroxy siloxane and linear dihydroxy siloxane, and the molecular weight of the high-toughness bio-based polyol is 300-1500 g / mol.

5. The bio-based polyurethane acrylic resin according to claim 1, characterized in that: The end-capping agent is selected from at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate and pentaerythritol triacrylate.

6. The bio-based polyurethane acrylic resin according to claim 1, characterized in that: The viscosity modifier is selected from at least one of polyethylene wax, oxidized polyethylene wax and polypropylene wax.

7. The bio-based polyurethane acrylic resin according to claim 1, characterized in that: The antioxidant is selected from pentaerythritol tetrakis[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate, thiodiethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate], N,N'-hexane-1,6-diylbis(3-(3,5-di-tert-butyl-4-hydroxyphenylpropionamide)), 3,3',3',5,5',5'-hexa-tert-butyl-a,a',a'-(mesitylene-2,4,6-triyl)tri-p-cresol, 1,3 , 5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, ethylenebis(oxyethylene)bis-(3-(5-tert-butyl-4-hydroxy-m-tolyl)-propionate), 3,5-bis(1,1-dimethylethyl)-4-hydroxy-C7-C9 branched alkyl ester, 3,5-di-tert-butyl-4-hydroxycinnamic acid, hexamethylenebis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) and 4,6-bis(octylthiomethyl)-o-cresol.

8. A method for preparing a bio-based polyurethane acrylic resin with low water absorption, characterized in that: The following steps are involved: S1. 8-18 parts of aliphatic diisocyanate, 0.1-0.4 parts of catalyst, and 0.2-0.5 parts of antioxidant are added to a flask, dry air is pumped into the flask, 5-10 parts of the end-capping agent are added dropwise at room temperature, and the reaction is carried out for 10-30 minutes after the addition is completed to prepare a prepolymer; S2. Add 55-70 parts of homemade bio-based polyol to the prepolymer in step S1, react at 60° C.-90° C. for 1-8 hours, and prepare a bio-based polyurethane acrylic resin with low water absorption.

9. The preparation method according to claim 8, characterized in that: The dripping speed of the capping agent in S1 is 10-20 drops / min, and the reaction time is 10-20 min.

10. The preparation method according to claim 8, characterized in that: The reaction temperature in S2 is 70°C-80°C, and the reaction time is 2-4h.

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