Photocurable epoxy / polyurethane anticorrosive coating containing cardanol

Abstract

The application discloses a kind of containing cashew phenol's photocuring epoxy resin / polyurethane anticorrosive paint;Paint is formed by four kinds of film-forming substances and photo initiator complex, four kinds of film-forming substances are respectively photocurable epoxy resin, photocurable polyurethane, cashew phenol-based polyurethane and active diluent, its mass ratio is photocuring epoxy resin 40~60%, photocuring polyurethane 0~40%, cashew phenol-based polyurethane 5~40%, the mass of active diluent is 10~30% of the mass of three kinds of resin, the mass of photo initiator is 1.0~5.0% of four kinds of film-forming substances.The cashew phenol-based polyurethane is prepared by reacting cashew phenol with diisocyanate, and then reacting with polyol;The cashew phenol-containing photocuring epoxy resin / polyurethane anticorrosive paint is prepared.The introduction of cashew phenol can provide good anticorrosive effect, and at the same time realize the goal of replacing petrochemical raw materials with natural raw materials.

Description

Technical Field

[0001] This invention relates to the field of anti-corrosion coating technology, specifically to an environmentally friendly light-curing metal anti-corrosion coating containing the natural raw material cashew phenol. Background Technology

[0002] Metal corrosion is the process by which metals, under the influence of corrosive media such as air and water molecules, undergo chemical changes, electrochemical changes, or physical dissolution, leading to a deterioration in the overall properties of the material. Applying an anti-corrosion coating to the metal surface is the most effective and widely used anti-corrosion measure to date. After coating, the metal surface is effectively slowed down or prevented from reaching corrosive media, thereby resisting or weakening the corrosion reaction and significantly extending the service life of the metal.

[0003] Epoxy resin is a typical base resin for anti-corrosion coatings, characterized by high strength, hardness, good adhesion, and excellent chemical resistance. However, its brittleness is its biggest drawback. Polyurethane is also a typical coating resin. Polyurethane possesses excellent low-temperature resistance, and its high regularity enhances the material's toughness. The steric hindrance of the urethane groups in the hard segments of the polyurethane molecule within the molecular chain increases the material's tensile strength and modulus. The intermolecular cross-linking structure improves the mechanical properties of polyurethane materials and imparts excellent water resistance and weather resistance. Polyurethane also exhibits excellent low-temperature resistance, toughness, impact resistance, and abrasion resistance. Therefore, combining epoxy resin and polyurethane can yield a coating resin with superior overall performance.

[0004] Currently, the raw materials for coating resins mainly come from non-renewable resources and rapidly depleting fossil resources. There is a growing emphasis on obtaining usable raw materials from natural products to replace non-renewable and fossil materials. Cashew nut shell extract, an agricultural byproduct extracted from cashew nut shell liquid, possesses a unique structure, excellent water resistance, good toughness, long service life, and excellent anti-corrosion properties. Therefore, cashew nut shell extract is considered 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, often referred to as a "green technology." Currently, UV curing technology is receiving increasing attention in the fields of coatings and adhesives. Summary of the Invention

[0006] The purpose of this invention is to provide a photocurable epoxy resin / polyurethane anticorrosive coating containing cashew phenol. The anticorrosive coating prepared by this invention has both excellent anticorrosive performance and environmental friendliness.

[0007] This invention discloses a high-performance anti-corrosion coating, which has the following three features: (1) combining epoxy resin and polyurethane, two main coating resins, to obtain comprehensive performance; (2) introducing natural raw material cashew phenol during the preparation of polyurethane to reduce the use of traditional fossil raw materials and make the product more "green"; (3) using photocuring technology to achieve room temperature crosslinking of the coating, resulting in better coating performance and being more environmentally friendly and energy-saving.

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

[0009] To achieve the above objectives, the present invention proposes a photocurable epoxy resin / polyurethane anticorrosive coating containing cashew phenol:

[0010] The coating is composed of four film-forming substances and a photoinitiator. The four film-forming substances are a photocurable epoxy resin, a photocurable polyurethane, a cashew nut polyurethane, and a reactive diluent. The mass ratio of the film-forming substances is 40-60% for the photocurable epoxy resin, 0-40% for the photocurable polyurethane, and 5-40% for the cashew nut 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 formed by esterification of epoxy resin and unsaturated carboxylic acid, and the content of unsaturated bonds is (2.0~4.5)×10. -3 mol / g

[0012] The coating is characterized in that the photocurable polyurethane is a polyurethane prepolymer with unsaturated bond ends, and the unsaturated bond content is (0.5~2.0)×10⁻⁶. -3 mol / g.

[0013] The coating is characterized in that the cashew phenol-based polyurethane is prepared by reacting cashew phenol, polyol and polyisocyanate.

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

[0015] Preferably, in the preparation of the cashew phenol-based polyurethane, the isocyanate monomer is selected from at least one of toluene diisocyanate (TDI), terephthalic diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), phenylmethylene diisocyanate, tetramethyl isophthalic diisocyanate, cyclohexane-1,4-diisocyanate, 1,4-cyclohexane dimethyl diisocyanate, and dicyclohexylmethane-4,4'-diisocyanate, preferably a liquid diisocyanate monomer. In particular, the polyisocyanate may be selected from at least one of IPDI, HDI, and TDI.

[0016] Preferably, in the preparation of the cashew phenol-based polyurethane, the molar ratio of isocyanate monomer to cashew phenol is controlled between 0.9 and 1.0, while 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 general-purpose photoinitiator, such as 2-hydroxy-2-methyl-1-phenyl-1-propanone (initiator 1173) or 1-hydroxycyclohexylphenyl ketone (initiator 184).

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

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

[0021] (1) The preparation method of this invention uses cashew phenol as raw material. Cashew phenol 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 gives the coating excellent water resistance, good toughness, 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. This invention combines epoxy resin and polyurethane to give full play to the excellent properties of the two resins.

[0023] (3) The present invention uses photocuring technology, which can achieve room temperature crosslinking and curing to obtain a paint film with excellent performance, which is more energy-saving and more environmentally friendly. Attached Figure Description

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

[0025] Figure 1 Tafel curves of electrochemical corrosion resistance test for 301 stainless steel and six coating samples Detailed Implementation

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

[0027] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application should have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

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

[0029] Examples 3 to 7 are examples of UV-cured polyurethane (UVPU). The UV-cured polyurethane is not limited to the preparation method of this example; products prepared by general methods or purchased can also be used.

[0030] Examples 8 to 10 are examples of the preparation of cashew phenol-containing polyurethane (CIPU). The preparation method of cashew phenol-containing polyurethane in these examples is not limited to that of these examples; products prepared by general methods are also acceptable.

[0031] Examples 11 to 16 are examples of UV-curable coatings formulated with UVPER / UVPU / CIPU / reactive diluent, and Experimental Examples 1 to 6 are tests on the anti-corrosion performance of UV-curable 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 (a polymerization inhibitor to prevent acrylic acid self-polymerization) were weighed into a reactor. The temperature was raised to 85°C, and the reaction was stirred for 7 hours. Then, triethylamine and dioxane were removed under reduced pressure to obtain UVPER1 epoxy resin with unsaturated C=C double bonds. The unsaturated double bond content of UVPER1 is approximately 2.0 × 10⁻⁶. - 3 mol / g.

[0034] Example 2

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

[0036] Example 3

[0037] This embodiment provides a photocurable polyurethane UVPU1.

[0038] 46.68 g of isophorone diisocyanate IPDI (-NCO content 0.42 mol) and 40 g of polyether diol PPG-400 (-OH content 0.2 mol) were added to a reactor. The mixture was heated to 80 °C with stirring. After the reactants were homogeneously mixed, 0.05% dibutyltin dilaurate (DBTDL) was added as a catalyst, and the reaction was maintained at this temperature for 1.5 h to obtain an -NCO-terminated polyurethane prepolymer. The temperature was then lowered to 65 °C, and 26.22 g of hydroxyethyl acrylate (HEA) (hydroxyl content 0.22 mol) was added. The reaction was maintained at this temperature for 1.5 h to obtain a photocurable polyurethane UVPU1. The unsaturated double bond content of UVPU1 is approximately 2.0 × 10⁻⁶. -3 mol / g.

[0039] Example 4

[0040] This embodiment provides a photocurable polyurethane UVPU2.

[0041] 52.245 g of toluene diisocyanate (TDI) (0.6 mol -NCO content) and 50 g of polyether diol (PTMEG-250) (0.4 mol -OH content) were added to a reactor. The mixture was heated to 80°C with stirring. After the reactants were homogeneously mixed, 0.05% DBTDL was added as a catalyst, and the reaction was maintained at this temperature for 1.5 h to obtain an -NCO-terminated polyurethane prepolymer. The temperature was then lowered to 65°C, and 28.63 g of hydroxyethyl methacrylate (HEMA) (0.22 mol hydroxyl content) was added. The reaction was maintained at this temperature for 1.5 h to obtain a photocurable polyurethane (UVPU2). The unsaturated double bond content of UVPU2 is approximately 1.68 × 10⁻⁶. -3 mol / g.

[0042] Example 5

[0043] This embodiment provides a photocurable polyurethane UVPU3.

[0044] 30.275 g of hexamethylene diisocyanate (HDI) (0.36 mol -NCO content) and 100 g of polyether diol (PPG-1000) (0.2 mol -OH content) were added to a reactor. The mixture was heated to 80 °C with stirring. After the reactants were homogeneously mixed, 0.05% DBTDL was added as a catalyst, and the reaction was maintained at this temperature for 2.0 h to obtain an -NCO-terminated polyurethane prepolymer. The temperature was then lowered to 65 °C, and 20.82 g of hydroxypropyl acrylate (HPA) (0.16 mol hydroxyl content) was added. The reaction was maintained at this temperature for 1.5 h to obtain a photocurable polyurethane (UVPU3). The unsaturated double bond content of UVPU3 is approximately 1.06 × 10⁻⁶. -3 mol / g.

[0045] Example 6

[0046] This embodiment provides a photocurable polyurethane UVPU4.

[0047] 76.69 g of IPDI (0.69 mol -NCO content) and 75 g of polyether diol PTMEG-250 (0.6 mol -OH content) were added to a reactor. The mixture was heated to 80°C with stirring. After the reactants were homogeneously mixed, 0.1% DBTDL was added as a catalyst, and the reaction was maintained at this temperature for 1.5 h to obtain an -NCO-terminated polyurethane prepolymer. The temperature was then lowered to 65°C, and 10.45 g of hydroxyethyl acrylate (HEA) (0.09 mol hydroxyl content) was added. The reaction was maintained at this temperature for 1.5 h to obtain a photocurable polyurethane UVPU4. The unsaturated double bond content of UVPU4 is approximately 0.56 × 10⁻⁶. -3 mol / g.

[0048] Example 7

[0049] This embodiment provides a photocurable polyurethane UVPU5.

[0050] 18.29 g of TDI (0.21 mol -NCO content) and 100 g of polyether diol PPG-2000 (0.1 mol -OH content) were added to a reactor. The mixture was heated to 80°C with stirring. After the reactants were homogeneously mixed, 0.05% DBTDL was added as a catalyst, and the reaction was maintained at this temperature for 1.5 h to obtain an -NCO-terminated polyurethane prepolymer. The temperature was then lowered to 65°C, and 13.41 g of hydroxyethyl acrylate (HEA) (0.1155 mol hydroxyl content) was added. The reaction was maintained at this temperature for 1.5 h to obtain a photocurable polyurethane UVPU5. The unsaturated double bond content of UVPU5 is approximately 0.88 × 10⁻⁶. -3 mol / g.

[0051] Example 8

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

[0053] 44.458 g (0.2 mol) of isophorone diisocyanate (IPDI) was added to the reactor, and the temperature was raised to 40 °C. Then, 60.6 g (approximately 0.2 mol) of cashew nut shellac and 0.1 g of catalyst DBTDL (approximately 0.095% of the total monomer mass) were slowly added dropwise. The addition rate was controlled and completed within 2 hours. After the cashew nut shellac was added, the temperature was raised to 45 °C, and the reaction was continued for 4 hours to obtain cashew nut shellac (CI) containing isocyanate groups.

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

[0055] Example 9

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

[0057] 37.843 g (0.225 mol) of hexamethylene diisocyanate (HDI) was added to the reactor, and the temperature was raised to 40 °C. Then, 75.75 g (approximately 0.25 mol) of cashew nut shellac and 0.09 g of catalyst DBTDL (approximately 0.08% of the total monomer mass) were slowly added dropwise. The addition rate was controlled and completed within 2 hours. After the cashew nut shellac was added, the temperature was raised to 45 °C, and the reaction was continued for 4 hours to obtain cashew nut shellac (CI) containing isocyanate groups.

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

[0059] Example 10

[0060] This embodiment prepares a cashew nut phenol-based polyurethane CIPU3. CIPU3 is made from cashew nut phenol, TDI and PTMEG-250, with a molar ratio of TDI to cashew nut phenol of 1.0 and a molar ratio of PTMEG-250 to TDI of 0.5.

[0061] 43.54 g (0.25 mol) of toluene diisocyanate (TDI) was added to the reactor. Under nitrogen protection, the mixture was stirred and heated to 40°C. Then, 75.75 g (approximately 0.25 mol) of cashew nut shellac and 0.095 g of catalyst DBTDL (approximately 0.08% of the total monomer mass) were slowly added dropwise. The addition rate was controlled, and the addition was completed within 2 hours. After the cashew nut shellac was completely added, the temperature was raised to 45°C, and the reaction was continued for 3 hours to obtain cashew nut shellac (CI) containing isocyanate groups.

[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, controlling the feeding rate, and the addition was completed within 1 hour. The reaction was then continued for 2.5 hours to obtain cashew phenol-based polyurethane prepolymer CIPU3.

[0063] Example 11

[0064] In this embodiment, UVPER1, UVPU1, CIPU1, Trimethylolpropane Trimethacrylate (TMPTMA), and 1173 are combined to form a UV-curable anti-corrosion coating. The sample of this anti-corrosion coating is named UVCoating1, and its formulation ratio can be found in Table 1.

[0065] Add 50g UVPER1, 37.5g UVPU1, 12.5g CIPU1 and 20g TMPTMA to a beaker and stir until well mixed. Then add 3.6g photoinitiator 1173 and stir thoroughly to obtain cashew phenol-based photocurable anticorrosive coating. Collect the coating in a black sample bottle for later use.

[0066] Examples 12 to 16

[0067] Using the same method as in Example 11, different types of UVPER, UVPU, CIPU and reactive diluents were combined to form a UV-curable coating. For detailed formulations, please refer to Table 1.

[0068] Table 1 Formulation of UV-curable coatings

[0069]

[0070]

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

[0072] Experimental Example 1

[0073] In this experimental example, a UV-cured coating was prepared using UVCoating1, and the anti-corrosion performance of the coating was tested.

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

[0075] A 301 stainless steel plate coated with a photocurable layer was used as the working electrode in a three-electrode system. A platinum electrode was used as the counter electrode, and a calomel electrode as the reference electrode. Impedance testing of the coating was performed using a CHI600E electrochemical workstation. The open-circuit potential (OCP) was kept constant, the perturbation voltage was 20 mV, and the frequency range was 0.1–105 Hz. The electrochemical cell was filled with 65 mL of 3.5% NaCl solution. The cell consisted of three electrode units: a saturated calomel electrode (SCE) and a platinum sheet, serving as the reference and auxiliary electrodes, respectively. The working electrode was the surface of the steel plate, isolated by a glass transition cell.

[0076] By analyzing the arc radius of the Nyquist plot and the resistance modulus at the lowest frequency of the Bode plot obtained from electrochemical impedance spectroscopy, the corrosion resistance of the coating can be accurately determined. If V... c The corrosion rate is represented by equation (1), and the protection efficiency IE of the coating can be calculated by equation (2).

[0077]

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

[0079] The chemical valence of n-Fe

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

[0081] d—Density of stainless steel 301, g·cm³ -3

[0082] F — Faraday constant, C·mol -1

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

[0084] Tafel curves for the electrochemical corrosion resistance test of the UVCoating1 coating are shown in the attached figure. Figure 1 The graph shows the corrosion current I of the coating. c The corrosion rate and protection efficiency of the coating on the substrate can be calculated using equations (1) and (2) (Table 2). Electrochemical tests show that the corrosion rate of bare 301 stainless steel is 1594 μm / a, while after applying UVCoating1, the corrosion rate is reduced to 1.23 μm / a. The calculated protection efficiency of the UVCoating1 coating on 301 stainless steel reaches 99.92%.

[0085] Experimental Examples 2 to 6

[0086] The anti-corrosion performance of each coating was tested using UV-curable coatings (UVCoating2 to UVCoating6) listed in Table 1, following the procedure described in Experimental Example 1. The Tafel curves for each coating are also shown in the appendix. Figure 1 The corrosion current and protection efficiency of each coating are shown in Table 2. The corrosion current in Table 2 is matched with the Tafel curves, and the Tafel curves of 301 stainless steel and the six coating samples are plotted in one graph; the vertical axis of the graph is the corrosion current (expressed in "A / cm"). 2The common logarithm (i.e., log[Ic]) in units of 1 / 2; the corrosion current of 301 stainless steel is 748.2 μA / cm. 2 That 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 for 301 stainless steel in the figure. It can be seen that all coatings can provide good protection for 301 stainless steel.

[0087] Table 2. Test results of the anti-corrosion effect of various composite coatings 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, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A photocured cashew phenolic epoxy / polyurethane anticorrosive coating, characterized by, The coating is compounded by four film-forming substances and a photoinitiator, the four film-forming substances are photocurable epoxy resin, photocurable polyurethane, cardanol-based polyurethane and reactive diluent, the mass ratio of the photocurable epoxy resin is 40-60%, the mass ratio of the photocurable polyurethane is 0-40%, the mass ratio of the cardanol-based polyurethane is 5-40%, and the mass of the reactive 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. The photo-curable epoxy resin is a resin with unsaturated bonds formed by esterification of an epoxy resin with an unsaturated carboxylic acid, and has an unsaturated bond content of (2.0-4.5) x 10 -3 mol / g. The cardanol-based polyurethane is prepared by reacting cardanol, polyol and polyisocyanate.

2. The cardanol-containing photocurable epoxy / polyurethane anticorrosive coating according to claim 1, characterized by, The photocurable polyurethane is a polyurethane prepolymer terminated with unsaturated bonds, and the content of the unsaturated bonds is (0.5-2.0) x 10 -3 mol / g.

3. The cardanol-containing photocurable epoxy / polyurethane anticorrosive coating according to claim 1, characterized by, In the preparation of the cardanol-based polyurethane, the polyol is at least one selected from polypropylene glycol, polytetrahydrofuran ether glycol and polyester glycol.

4. The cardanol-containing photocurable epoxy / polyurethane anticorrosive coating according to claim 1, characterized by, The polyol is a polyether diol.

5. The cardanol-containing photocurable epoxy / polyurethane anticorrosive coating according to claim 1, wherein the cardanol is present in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the total amount of the epoxy resin and the polyol. The polyisocyanate monomer is at least one selected from toluene diisocyanate, p-phenylene diisocyanate, diphenyl methane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, tetramethyl m-xylylene diisocyanate, cyclohexane-1,4-diisocyanate, 1,4-cyclohexane dimethyl diisocyanate and dicyclohexyl methane-4,4'-diisocyanate.

6. The cardanol-containing photocurable epoxy / polyurethane anticorrosive coating of claim 1, wherein the cardanol is present in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the total amount of the epoxy resin and the polyol. In the preparation of the cardanol-based polyurethane, the molar ratio of the isocyanate monomer to the cardanol is 0.9-1.0, and the molar ratio of the polyol to the isocyanate monomer is 0.5-0.

8.

7. The cardanol-containing photocurable epoxy / polyurethane anticorrosive coating of claim 1, wherein the cardanol is present in an amount of 0.1 to 10 wt%. The reactive diluent is a liquid monomer with multiple unsaturated C=C double bonds, typical reactive diluents include multifunctional acrylate and methacrylate monomers, and are selected from one or more of trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, 1,6-hexanediol diacrylate, dipropylene glycol diacrylate and tripropylene glycol diacrylate.

8. The cardanol-containing photocurable epoxy / polyurethane anticorrosive coating of claim 1, wherein, The photoinitiator is a general-purpose photoinitiator, and is selected from one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone and 1-hydroxycyclohexyl phenyl ketone.

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