Light-cured epoxy resin / polyurethane anticorrosive paint containing cardanol

Abstract

The invention discloses a light-cured epoxy resin / polyurethane anticorrosive coating containing cardanol. The coating is formed by compounding four film forming matters and a photoinitiator, the four film forming matters are respectively light-curable epoxy resin, light-curable polyurethane, cardanol-based polyurethane and a reactive diluent, and the mass ratio of the light-curable epoxy resin to the light-curable polyurethane to the cardanol-based polyurethane to the reactive diluent is 40-60%: 0-40%: 5-40%. The mass of the reactive diluent is 10-30% of the mass of the three resins, and the mass of the photoinitiator is 1.0-5.0% of the mass of the four film forming substances. The preparation method comprises the following steps: reacting cardanol with diisocyanate, and then reacting with polyol to prepare cardanol-based polyurethane; the anacardol-containing light-cured epoxy resin / polyurethane anticorrosive paint is prepared. The cardanol is introduced, so that a good preservative effect can be provided, and meanwhile, the aim of replacing petrochemical raw materials with natural raw materials is fulfilled.

Description

Technical Field

[0001] The invention relates to the technical field of anti-corrosion coatings, and in particular to an environmentally friendly light-cured metal anti-corrosion coating containing natural raw material cardanol. Background Art

[0002] Metal corrosion is a process in which the overall performance of a material deteriorates due to chemical changes, electrochemical changes or physical dissolution under the action of corrosive media such as air and water molecules. The isolation method of applying an anti-corrosion coating on the metal surface is the most effective and widely used anti-corrosion measure to date. After the metal is coated with an anti-corrosion coating, it can effectively slow down or prevent the corrosive medium from reaching the metal surface, thereby resisting or weakening the corrosion reaction of the metal and greatly increasing the service life of the metal.

[0003] Epoxy resin is a typical base resin for anti-corrosion coatings. Epoxy resin has the characteristics of high strength, hardness, good adhesion, and excellent chemical resistance. However, the brittleness of epoxy resin is its biggest disadvantage. Polyurethane is also a typical coating resin. Polyurethane has excellent low-temperature resistance, and its high regularity can improve the toughness of the material; the urethane group in the hard segment of the polyurethane molecule has a large steric hindrance in the molecular chain, which can improve the tensile strength and modulus of the material. The cross-linked structure between molecules can improve the mechanical properties of polyurethane materials and give them excellent water resistance and weather resistance. Polyurethane has excellent low-temperature resistance, toughness, impact resistance and wear resistance. Therefore, compounding epoxy resin and polyurethane together can obtain a coating resin with better comprehensive performance.

[0004] At present, the raw materials of coating resins mainly come from non-renewable raw materials and rapidly consumed fossil resources. People pay more and more attention to obtaining usable raw materials from natural products to replace non-renewable raw materials and fossil raw materials. Cardanol is an agricultural by-product extracted from cashew nut shell liquid. It has a unique structure, excellent water resistance, good toughness, long service life and excellent anti-corrosion properties. Therefore, cardanol is considered to be an ideal precursor for the synthesis of a series of value-added monomers and polymers.

[0005] UV curing is an environmentally friendly and energy-saving curing method, known as "green technology". Currently, UV curing technology is gaining more and more attention in the fields of coatings and adhesives. Summary of the invention

[0006] The object of the present invention is to provide a light-cured epoxy resin / polyurethane anti-corrosion coating containing cardanol. The anti-corrosion coating prepared by the present invention has both excellent anti-corrosion performance and environmental friendliness.

[0007] The present invention discloses a high-performance anti-corrosion coating, which has the following three characteristics: (1) two main coating resins, epoxy resin and polyurethane, are compounded together to obtain comprehensive performance; (2) natural raw material cardanol is introduced into the preparation of polyurethane to reduce the use of traditional fossil raw materials and make the product more "green"; (3) light curing technology is used to achieve room temperature cross-linking of the coating, so that the coating has better performance and is more environmentally friendly and energy-saving.

[0008] In view of this, the present invention is proposed.

[0009] In order to achieve the above-mentioned object, the light-cured epoxy resin / polyurethane anti-corrosion coating containing cardanol proposed in the present invention is:

[0010] The coating is composed of four film-forming substances and a photoinitiator. The four film-forming substances are respectively a photocurable epoxy resin, a photocurable polyurethane, a cardanol-based polyurethane and a reactive diluent. The mass ratio of the four film-forming substances is 40-60% of the photocurable epoxy resin, 0-40% of the photocurable polyurethane, and 5-40% of the cardanol-based polyurethane. The mass of the reactive diluent is 10-30% of the mass of the three resins, and the mass of the photoinitiator is 1.0-5.0% of the mass of the four film-forming substances.

[0011] The coating is characterized in that the photocurable epoxy resin is a resin with unsaturated bonds generated by esterification of epoxy resin and unsaturated carboxylic acid, and the unsaturated bond content is (2.0-4.5)×10 -3 mol / g

[0012] The coating is characterized in that the light-curing polyurethane is a polyurethane prepolymer terminated with an unsaturated bond, and the unsaturated bond content is (0.5-2.0)×10 -3 mol / g.

[0013] The coating is characterized in that the cardanol-based polyurethane is prepared by the reaction of cardanol, polyol and polyisocyanate.

[0014] Preferably, in the preparation of the cardanol-based polyurethane, the polyol is selected from at least one of polypropylene glycol (PPG series), polytetramethylene ether glycol (PTMEG series), and polyester glycol (PEA series, PBA series), preferably polyether diol, and preferably a low molecular weight diol in the polyether diol, in particular, the polyol is selected from PPG-400, PTMEG-250.

[0015] Preferably, in the preparation of the cardanol-based polyurethane, the isocyanate monomer is selected from at least one of toluene diisocyanate (TDI), p-phenylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), xylene diisocyanate, tetramethyl metaxylene diisocyanate, cyclohexane-1,4-diisocyanate, 1,4-cyclohexanedimethyl diisocyanate, and dicyclohexylmethane-4,4'-diisocyanate, preferably a liquid diisocyanate monomer, and in particular, the polyisocyanate can be selected from at least one of IPDI, HDI, and TDI.

[0016] Preferably, in the preparation of the cardanol-based polyurethane, the molar ratio of isocyanate monomer to cardanol is controlled between 0.9 and 1.0, and the ratio of polyol to isocyanate monomer is controlled between 0.5 and 0.8.

[0017] The coating is characterized in that the reactive diluent is a liquid monomer with multiple unsaturated C=C double bonds. Typical reactive diluents include multifunctional acrylate and methacrylate monomers, preferably trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate (TMPTMA), 1,6-hexanediol diacrylate (HDDA), dipropylene glycol diacrylate (DPGDA), and tripropylene glycol diacrylate (TPGDA).

[0018] The coating is characterized in that the photoinitiator is a universal photoinitiator, and typical photoinitiators include 2-hydroxy-2-methyl-1-phenyl-1-propanone (initiator 1173) and 1-hydroxycyclohexyl phenyl ketone (initiator 184).

[0019] The present invention also provides an environmentally friendly light-curing anti-corrosion coating prepared by the above method.

[0020] Compared with the prior art, the beneficial effects of the present invention include at least:

[0021] (1) The preparation method of the present invention uses cardanol as a raw material. Cardanol has a unique structure, including a benzene ring, a phenolic hydroxyl group and an unsaturated 15-carbon side chain. The benzene ring structure has excellent high temperature resistance and chemical resistance, the phenolic hydroxyl group provides good reactivity and modifiability, and the long aliphatic side chain makes the coating have excellent water resistance, good toughness, a long service life and excellent anti-corrosion performance.

[0022] (2) Epoxy resin has high strength and good adhesion; while polyurethane resin has the characteristics of wear resistance, good resilience, and low temperature resistance. The present invention combines epoxy resin with polyurethane to give full play to the excellent properties of the two resins.

[0023] (3) The present invention adopts light curing technology, which can achieve room temperature cross-linking and curing to obtain a paint film with excellent performance, which is more energy-saving and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The attached figure shows the Tafel curve of the electrochemical corrosion test of the anti-corrosion coating prepared by the photocuring coating of the present invention and 301 stainless steel.

[0025] Figure 1 Tafel curves of electrochemical corrosion test of 301 stainless steel and six coating samples DETAILED DESCRIPTION

[0026] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0027] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0028] In the following examples, Examples 1 and 2 are different examples of light-curing epoxy resin UVPER. The light-curing epoxy resin is not limited to the preparation method of this example, and any product prepared or purchased by a general method can be used.

[0029] Embodiments 3 to 7 are examples of light-curing polyurethane UVPU. The preparation method of light-curing polyurethane is not limited to that of the present embodiment, and any product prepared or purchased by a general method can be used.

[0030] Examples 8 to 10 are examples of the preparation of polyurethane CIPU containing cardanol. The polyurethane examples containing cardanol are not limited to the preparation method of this example, and products prepared by general methods can be used.

[0031] Examples 11 to 16 are examples of photocurable coatings prepared with UVPER / UVPU / CIPU / active diluent, and Experimental Examples 1 to 6 are tests of the anticorrosion properties of the photocurable coatings.

[0032] Example 1

[0033] This embodiment provides a photocurable epoxy resin UVPER1. 118g of phenolic epoxy resin F-44, 20g of acrylic acid, 2g of triethylamine, 30g of dioxane and 0.05% (relative to the total mass of F-44 and acrylic acid) of phenothiazine (inhibitor to prevent acrylic acid from self-polymerization) were weighed into a reactor. The temperature was raised to 85°C, stirred for reaction for 7h, and then triethylamine and dioxane were removed under reduced pressure to obtain epoxy resin UVPER1 with unsaturated C=C double bonds. The unsaturated double bond content of UVPER1 was about 2.0×10 - 3 mol / g.

[0034] Example 2

[0035] This embodiment provides a photocurable epoxy resin UVPER2. 100 g of bisphenol A epoxy resin E-51, 46.8 g of acrylic acid, 2 g of triethylamine, 20 g of dioxane and 0.05% (relative to the total mass of E-51 and acrylic acid) of phenothiazine were weighed in a four-necked flask. The temperature was raised to 80°C, stirred for reaction for 6 h, and then triethylamine and dioxane were removed under reduced pressure to obtain a photocurable phenolic epoxy resin UVPER2. The unsaturated double bond content of UVPER2 was 4.4×10 -3 mol / g.

[0036] Example 3

[0037] This embodiment provides a photocurable polyurethane UVPU1.

[0038] 46.68g of isophorone diisocyanate IPDI (-NCO content 0.42mol) and 40g of polyether diol PPG-400 (-OH content 0.2mol) were added to the reactor, and the temperature was raised to 80°C under stirring. After the reactants were evenly mixed, 0.05% of dibutyltin dilaurate (DBTDL) was added as a catalyst, and the temperature was maintained for 1.5h to obtain a -NCO-terminated polyurethane prepolymer. Then the temperature was lowered to 65°C, 26.22g of hydroxyethyl acrylate HEA (hydroxyl content 0.22mol) was added, and the temperature was maintained for 1.5h to obtain a photocurable polyurethane UVPU1. The unsaturated double bond content of UVPU1 is about 2.0×10 -3 mol / g.

[0039] Example 4

[0040] This embodiment provides a photocurable polyurethane UVPU2.

[0041] 52.245 g of toluene diisocyanate TDI (-NCO content 0.6 mol) and 50 g of polyether diol PTMEG-250 (-OH content 0.4 mol) were added to the reactor, and the temperature was raised to 80°C under stirring. After the reactants were evenly mixed, 0.05% of DBTDL was added as a catalyst, and the temperature was maintained for 1.5 hours to obtain a -NCO-terminated polyurethane prepolymer. Then the temperature was lowered to 65°C, 28.63 g of hydroxyethyl methacrylate HEMA (hydroxyl content 0.22 mol) was added, and the temperature was maintained for 1.5 hours to obtain a photocurable polyurethane UVPU2. The unsaturated double bond content of UVPU2 is about 1.68×10 -3 mol / g.

[0042] Example 5

[0043] This embodiment provides a photocurable polyurethane UVPU3.

[0044] 30.275 g of hexamethylene diisocyanate HDI (-NCO content 0.36 mol) and 100 g of polyether diol PPG-1000 (-OH content 0.2 mol) were added to the reactor, and the temperature was raised to 80°C under stirring. After the reactants were evenly mixed, 0.05% of DBTDL was added as a catalyst, and the temperature was maintained for 2.0 h to obtain a -NCO-terminated polyurethane prepolymer. Then the temperature was lowered to 65°C, 20.82 g of hydroxypropyl acrylate HPA (hydroxyl content 0.16 mol) was added, and the temperature was maintained for 1.5 h to obtain a photocurable polyurethane UVPU3. The unsaturated double bond content of UVPU3 is about 1.06×10 -3 mol / g.

[0045] Example 6

[0046] This embodiment provides a photocurable polyurethane UVPU4.

[0047] 76.69g of IPDI (-NCO content 0.69mol) and 75g of polyether diol PTMEG-250 (-OH content 0.6mol) were added to the reactor, and the temperature was raised to 80°C under stirring. After the reactants were mixed evenly, 0.1% of DBTDL was added as a catalyst, and the temperature was maintained for 1.5h to obtain a -NCO-terminated polyurethane prepolymer. Then the temperature was lowered to 65°C, 10.45g of hydroxyethyl acrylate HEA (hydroxyl content 0.09mol) was added, and the temperature was maintained for 1.5h to obtain a photocurable polyurethane UVPU4. The unsaturated double bond content of UVPU4 is about 0.56×10 -3 mol / g.

[0048] Example 7

[0049] This embodiment provides a photocurable polyurethane UVPU5.

[0050] 18.29g of TDI (-NCO content 0.21mol) and 100g of polyether diol PPG-2000 (-OH content 0.1mol) were added to the reactor, and the temperature was raised to 80°C under stirring. After the reactants were evenly mixed, 0.05% of DBTDL was added as a catalyst, and the temperature was maintained for 1.5h to obtain a -NCO-terminated polyurethane prepolymer. Then the temperature was lowered to 65°C, 13.41g of hydroxyethyl acrylate HEA (hydroxyl content 0.1155mol) was added, and the temperature was maintained for 1.5h to obtain a photocurable polyurethane UVPU5. The unsaturated double bond content of UVPU5 is about 0.88×10 -3 mol / g.

[0051] Example 8

[0052] This embodiment prepares a cardanol-based polyurethane CIPU1. CIPU1 uses cardanol, IPDI and PPG-400 as raw materials, and the molar ratio of IPDI to cardanol is 1.0, and the molar ratio of PPG-400 to IPDI is 0.6.

[0053] Add 44.458g (0.2mol) of isophorone diisocyanate IPDI into the reactor, heat it to 40°C, then slowly drop 60.6g (about 0.2mol) of cardanol and 0.1g of catalyst DBTDL (about 0.095% of the total mass of the monomer). Control the feeding speed and add it within 2h. After the addition of cardanol is completed, heat it to 45°C and continue the reaction for 4h to obtain cardanol CI containing isocyanate groups.

[0054] 48 g (0.12 mol) of polyether diol PPG-400 was added to the reactor, stirred, and heated to 70° C. The previously synthesized CI was slowly and uniformly added to the reactor, the addition rate was controlled, and the addition was completed within 1 hour, and then the reaction was continued for 2.5 hours to obtain the cardanol-based polyurethane prepolymer CIPU1.

[0055] Example 9

[0056] This embodiment prepares a cardanol-based polyurethane CIPU2. CIPU2 uses cardanol, HDI and PTMEG-250 as raw materials, and the molar ratio of HDI to cardanol is 0.9, and the molar ratio of PTMEG-250 to HDI is 0.8.

[0057] Add 37.843g (0.225mol) of hexamethylene diisocyanate HDI into the reactor, heat it to 40°C, then slowly drop 75.75g (about 0.25mol) of cardanol and 0.09g of catalyst DBTDL (about 0.08% of the total mass of the monomer). Control the feeding speed and add it within 2h. After the addition of cardanol is completed, heat it to 45°C and continue the reaction for 4h to obtain cardanol CI containing isocyanate group.

[0058] 45 g (0.18 mol) of polyether diol PTMEG-250 was added to the reactor, stirred, and heated to 70° C. The previously synthesized CI was slowly and uniformly added to the reactor, the addition rate was controlled, and the addition was completed within 1 hour, and then the reaction was continued for 2.5 hours to obtain the cardanol-based polyurethane prepolymer CIPU2.

[0059] Example 10

[0060] This embodiment prepares a cardanol-based polyurethane CIPU3. CIPU3 uses cardanol, TDI and PTMEG-250 as raw materials, and the molar ratio of TDI to cardanol is 1.0, and the molar ratio of PTMEG-250 to TDI is 0.5.

[0061] Add 43.54g (0.25mol) of toluene diisocyanate TDI into the reactor, stir under nitrogen protection, heat to 40°C, then slowly drop 75.75g (about 0.25mol) of cardanol and 0.095g of catalyst DBTDL (about 0.08% of the total mass of the monomer). Control the feeding speed and add it within 2h. After the addition of cardanol is completed, heat to 45°C and continue the reaction for 3h to obtain cardanol CI containing isocyanate group.

[0062] 31.25 g (0.125 mol) of polyether diol PTMEG-250 was added to the reactor, stirred, and heated to 70° C. The previously synthesized CI was slowly and uniformly added to the reactor, the addition rate was controlled, and the addition was completed within 1 hour, and then the reaction was continued for 2.5 hours to obtain the cardanol-based polyurethane prepolymer CIPU3.

[0063] Embodiment 11

[0064] In this embodiment, photocurable epoxy resin UVPER1, photocurable polyurethane UVPU1, photocurable cardanol-based polyurethane CIPU1, active diluent trimethylolpropane trimethacrylate TMPTMA, and photoinitiator 1173 are compounded together to prepare a photocurable anticorrosion coating. The anticorrosion coating sample is named UVCoating1, and its formula ratio can be seen in Table 1.

[0065] Add 50g UVPER1, 37.5g UVPU1, 12.5g CIPU1 and 20g TMPTMA into a beaker, stir and mix evenly, then add 3.6g photoinitiator 1173, and stir well to obtain a cardanol-based photocurable anticorrosive coating, which is collected in a black sample bottle for later use.

[0066] Example 12 to Example 16

[0067] In the same manner as in Example 11, different types of UVPER, UVPU, CIPU and reactive diluents were compounded together to prepare a photocurable coating. The detailed formula can be found in Table 1.

[0068] Table 1 Formulation of light-curing coatings

[0069]

[0070]

[0071] Formulation principles: the base resin composition is UVPER+UVPU+CIPU=100 (parts by mass), wherein UVPER=40-60%, UVPU=0-40%, CIPU=5-40%; the mass of the active diluent is 10-30% relative to the base resin; the mass of the photoinitiator is 1.0-5.0% of the total mass of the base resin and the active diluent.

[0072] Experimental Example 1

[0073] In this experimental example, UVCoating1 coating was used to prepare a light-cured coating, and the anti-corrosion performance of the coating was tested.

[0074] Take a 301 stainless steel sample, polish it with sandpaper, then clean it with ethanol and dry it. Apply the composite light-curing coating UVCoating1 in Table 1 evenly on the clean surface of the 301 stainless steel sample with a coating rod, and then place it in a UV curing instrument for 20 seconds to obtain a light-cured coating.

[0075] The 301 steel plate coated with the photocured coating was used as the working electrode, and a three-electrode system was used. The platinum electrode was used as the counter electrode, and the calomel electrode was used as the reference electrode. The impedance test of the coating was carried out using a CHI600E electrochemical workstation. The open circuit potential (OCP) was a constant value, the perturbation voltage was 20mV, and the frequency range was 0.1-105Hz. The electrochemical cell was filled with 65mL of 3.5% NaCl solution. The cell includes three electrode units: a saturated calomel electrode (SCE) and a platinum sheet as the reference electrode and the auxiliary electrode, respectively. The working electrode is the surface of the steel plate, which is isolated by a glass cell.

[0076] By analyzing the arc radius of the Nyquist diagram of the electrochemical impedance spectroscopy test and the resistance module of the lowest frequency of the Bode diagram, the corrosion resistance of the coating can be accurately determined. c Represents the corrosion rate, which can be calculated by formula (1); the protection efficiency IE of the coating can be calculated by formula (2).

[0077]

[0078] In the formula, the relative atomic mass of A—Fe is 55.85 g·mol -1

[0079] n—Chemical valence of Fe

[0080] I c —Corrosion current of composite coating, μA·cm -2

[0081] d—density of stainless steel 301, g·cm -3

[0082] F—Faraday constant, C·mol -1

[0083] I c0 —Corrosion current of stainless steel 301, μA·cm -2

[0084] The Tafel curve of the electrochemical corrosion test of UVCoating1 is shown in the attached figure. Figure 1 From this figure, it can be seen that the corrosion current I c , the corrosion rate of the coating and the protection efficiency of the substrate can be calculated by equations (1) and (2) (Table 2). The electrochemical test shows that the corrosion rate of 301 stainless steel is 1594μm / a, and after UVCoating1 is used for protection, its corrosion rate is reduced to 1.23μm / a. The calculated protection efficiency of UVCoating1 coating for 301 stainless steel reaches 99.92%.

[0085] Experimental Examples 2 to 6

[0086] The anti-corrosion performance of the light-curing coatings UVCoating2 to UVCoating6 in Table 1 was tested according to the operating method of Experimental Example 1. The Tafel curves of the coatings are also shown in the attached figure. Figure 1 The corrosion current and protection efficiency of each coating are shown in Table 2. The corrosion current in Table 2 matches the Tafel curve. The Tafel curves of 301 stainless steel and six coating samples are concentrated in one figure; the ordinate in the figure is the corrosion current (in "A / cm 2The common logarithm of the corrosion current (i.e., log[Ic]) is 748.2μA / cm 2 , which is 7.482×10 -4 A / cm -2 , its logarithmic value is -3.12598, which is the ordinate of the lowest inflection point of the Tafel curve of 301 stainless steel in the figure. It can be seen that each coating can provide good protection for 301 stainless steel.

[0087] Table 2 Test results of the anticorrosion effect of each composite coating on 301 stainless steel

[0088]

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A light-cured epoxy resin / polyurethane anticorrosive coating containing cardanol, characterized in that: The coating is composited by four film-forming substances and a photoinitiator. The four film-forming substances are photocurable epoxy resin, photocurable polyurethane, cardanol-based polyurethane and active diluent, and the mass ratio thereof is 40-60% of the photocurable epoxy resin, 0-40% of the photocurable polyurethane, 5-40% of the cardanol-based polyurethane, and the mass of the active diluent is 10-30% of the mass of the three resins; the mass of the photoinitiator is 1.0-5.0% of the mass of the four film-forming substances.

2. The light-cured epoxy resin / polyurethane anticorrosive coating containing cardanol as claimed in claim 1, characterized in that: Photocurable epoxy resin is a resin with unsaturated bonds generated by esterification of epoxy resin and unsaturated carboxylic acid. The unsaturated bond content is (2.0~4.5)×10 -3 mol / g.

3. The light-cured epoxy resin / polyurethane anticorrosive coating containing cardanol as claimed in claim 1, characterized in that: Photocurable polyurethane is a polyurethane prepolymer terminated with unsaturated bonds, and its unsaturated bond content is (0.5~2.0)×10 -3 mol / g.

4. The light-cured epoxy resin / polyurethane anticorrosive coating containing cardanol as claimed in claim 1, characterized in that: Cardanol-based polyurethane is prepared by the reaction of cardanol, polyol and polyisocyanate.

5. The light-curing epoxy resin / polyurethane anticorrosive coating containing cardanol as claimed in claim 4, characterized in that: In the preparation of cardanol-based polyurethane, the polyol is selected from at least one of polypropylene glycol, polytetramethylene glycol, and polyester glycol.

6. The light-cured epoxy resin / polyurethane anticorrosive coating containing cardanol as claimed in claim 4, characterized in that: The polyol is a polyether diol, and the polyether diol is a diol with a low molecular weight.

7. The light-cured epoxy resin / polyurethane anticorrosive coating containing cardanol as claimed in claim 4, characterized in that: The polyisocyanate monomer is selected from at least one of toluene diisocyanate, p-phenylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, tetramethyl-m-xylylene diisocyanate, cyclohexane-1,4-diisocyanate, 1,4-cyclohexanedimethyl diisocyanate, and dicyclohexylmethane-4,4'-diisocyanate.

8. The light-curing epoxy resin / polyurethane anticorrosive coating containing cardanol as claimed in claim 4, characterized in that: In the preparation of cardanol-based polyurethane, the molar ratio of isocyanate monomer to cardanol is 0.9-1.0, and the molar ratio of polyol to isocyanate monomer is 0.5-0.

8.

9. The light-cured epoxy resin / polyurethane anticorrosive coating containing cardanol as claimed in claim 1, characterized in that: The reactive diluent is a liquid monomer with multiple unsaturated C=C double bonds. Typical reactive diluents include multifunctional acrylate and methacrylate monomers, including trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, and tripropylene glycol diacrylate.

10. The light-curing epoxy resin / polyurethane anticorrosive coating containing cardanol as claimed in claim 1, characterized in that: The photoinitiator is a universal photoinitiator, including 2-hydroxy-2-methyl-1-phenyl-1-propanone and 1-hydroxycyclohexyl phenyl ketone.

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