Rosin-based bio-based UV-curable resin and its preparation method and application

Abstract

The present invention relates to the technical field of polymer materials, and discloses a rosin-based bio-based UV-curable resin, a preparation method thereof, and an application thereof. The structural formula of the rosin-based bio-based UV-curable resin provided by the present invention is shown in formula (I). The UV-curable resin of the present invention has a rigid tricyclic diterpene structure and a carbon-carbon double bond. After being cured into a film, it has good cross-linking density, adhesion properties, mechanical properties, and thermal stability, and can be applied to adhesives, sealants, or UV-curable coatings. The UV-curable resin of the present invention is prepared using bio-based materials as raw materials, and the preparation method is simple and environmentally friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a rosin-based bio-based ultraviolet curing resin, a preparation method thereof, and applications thereof. Background Art

[0002] UV-curable materials are widely used in modern industry due to their advantages, such as low energy consumption, fast curing speed, and low volatile emissions. However, existing technologies produce UV-curable resins from non-renewable petroleum-based materials, which not only relies on non-renewable resources but also pollutes the environment. With the growing popularity of sustainable development, finding alternative materials to manufacture UV-curable resins from renewable resources is becoming increasingly important.

[0003] Rosin is a natural resin with a rigid tricyclic diterpene structure, which effectively increases the strength and glass transition temperature of the resin. Therefore, developing bio-based UV-curing resins using rosin-based epoxy resins as raw materials is not only green and environmentally friendly, but also meets the demand of modern industry for high-performance environmentally friendly materials. Summary of the Invention

[0004] The first object of the present invention is to provide a rosin-based bio-based UV-curable resin to solve at least one of the above technical problems.

[0005] A second object of the present invention is to provide a method for preparing the above-mentioned rosin-based bio-based UV-curable resin to solve at least one of the above-mentioned technical problems.

[0006] The third object of the present invention is to provide an application of a rosin-based bio-based UV-curable resin in adhesives, sealants or UV-curable coatings to solve at least one of the above technical problems.

[0007] A fourth object of the present invention is to provide a UV-curable composition to solve at least one of the above technical problems.

[0008] According to a first aspect of the present invention, the present invention provides a rosin-based bio-based UV-curable resin, and the structural formula of the rosin-based bio-based UV-curable resin is shown in formula (I):

[0009]

[0010] The rosin-based bio-based UV-curable resin of the present invention combines the rigid structure of tricyclic diterpenes with a chain structure and carbon-carbon double bonds, which can improve the mechanical properties, flexibility, and crosslink density of the UV-curable resin. Experimental results show that after UV-curing, the rosin-based bio-based UV-curable resin of the present invention has a high degree of crosslinking within the cured film and also exhibits good tensile strength, hardness, adhesion, and thermal stability.

[0011] According to a second aspect of the present invention, there is provided a method for preparing the above-mentioned rosin-based bio-based UV-curable resin, comprising the following steps:

[0012] 27-79 parts of maleic pine epoxy resin (MPA-ER), 15-77 parts of hydroxy acrylate, 0.05-0.75 parts of polymerization inhibitor and 0.07-1.53 ​​parts of the first catalyst are mixed, heated to 80-130° C. in a nitrogen atmosphere, and reacted until the acid value is less than 15 mgKOH / g to obtain the product;

[0013] The first catalyst is selected from at least one of N,N-dimethylbenzylamine, benzyltriethylammonium chloride, dibutyltin dilaurate, triethylamine, and triphenylphosphine; and the polymerization inhibitor is selected from at least one of a phenolic polymerization inhibitor or an amine polymerization inhibitor.

[0014] The synthetic route of the rosin-based bio-based UV-curable resin is shown in formula (II):

[0015]

[0016] The present invention provides a method for preparing a rosin-based bio-based UV-curable resin, using maleomaritime pine epoxy resin as a bio-based raw material. This method is environmentally friendly. By ring-opening the epoxy groups of the maleomaritime pine epoxy resin under attack by the hydroxyl groups of an acrylate compound and introducing the carbon-carbon double bonds and chain structure of the acrylate compound, a trifunctional UV-curable resin with both a rigid tricyclic diterpene structure and carbon-carbon double bonds is produced. This method improves the crosslinking density and rigid structure content of the UV-curable resin, while also simplifying the preparation process.

[0017] In some embodiments, when preparing a rosin-based bio-based UV-curable resin, the amount of maleic pine epoxy resin can be 31-69 parts by weight, the amount of hydroxy acrylate can be 15-65 parts by weight, the amount of inhibitor can be 0.05-0.69 parts by weight, and the amount of catalyst can be 0.15-1.33 parts by weight.

[0018] In some embodiments, the phenolic polymerization inhibitor may be selected from at least one of dinoseb, hydroquinone, and p-tert-butylcatechol, and the amine polymerization inhibitor may be diethylhydroxylamine.

[0019] In some embodiments, the maleic pinemarine epoxy resin is prepared by the following steps:

[0020] After maleopimaric anhydride (MPA) and epichlorohydrin are heated and dissolved into a homogeneous phase, a quaternary ammonium salt catalyst is added, and the reaction is carried out at 80-130°C until the acid value is less than 1 mgKOH / g. The temperature is then lowered to 50-90°C, sodium hydroxide is added, and the reaction is carried out until the pH value no longer decreases. The epichlorohydrin is removed by distillation under reduced pressure to obtain the product.

[0021] The synthetic route of maleic pine epoxy resin is shown in formula (III):

[0022]

[0023] In some embodiments, the quaternary ammonium salt catalyst may be selected from at least one of tetrabutylammonium bromide and benzyltriethylammonium chloride.

[0024] In some embodiments, when preparing maleopimaric epoxy resin, the amount of maleopimaric anhydride used can be 27-79 parts by weight, the amount of epichlorohydrin used can be 165-225 parts by weight, the amount of tetrabutylammonium bromide used can be 0.13-1.50 parts by weight, and the amount of sodium hydroxide used can be 8-33 parts by weight.

[0025] In other embodiments, when preparing maleopimaric epoxy resin, the amount of maleopimaric anhydride can be 35-69 parts, the amount of epichlorohydrin can be 175-205 parts, the amount of tetrabutylammonium bromide can be 0.15-1.25 parts, and the amount of sodium hydroxide can be 11-29 parts, based on parts by weight.

[0026] In some embodiments, the treatment method of reduced pressure distillation is to perform reduced pressure distillation at a temperature of 60-70° C. and a pressure of 120-150 Pa.

[0027] In some embodiments, the reaction time until the pH value no longer decreases can be 2-5 hours.

[0028] In some embodiments, hydroxy acrylate (HEMMA) is prepared by the following steps:

[0029] Mix hydroxyethyl methacrylate (HEMA), maleic anhydride (MA) and a polymerization inhibitor, and react in a nitrogen atmosphere at a temperature of 80-130° C. for 3.5-8.5 hours to obtain the product.

[0030] The synthetic route of hydroxy acrylate is shown in formula (IV):

[0031]

[0032] In some embodiments, when preparing hydroxyacrylate, the amount of hydroxyethyl methacrylate can be 33-77 parts by weight, the amount of maleic anhydride can be 19-59 parts, and the amount of the polymerization inhibitor can be 0.05-0.25 parts.

[0033] In other embodiments, when preparing hydroxy acrylate, the amount of hydroxyethyl methacrylate can be 39-67 parts by weight, the amount of maleic anhydride can be 25-55 parts by weight, and the amount of the polymerization inhibitor can be 0.05-0.19 parts by weight.

[0034] According to a third aspect of the present invention, there is provided a use of a rosin-based bio-based UV-curable resin in an adhesive, a sealant or a UV-curable coating.

[0035] According to a fourth aspect of the present invention, a UV-curable composition is provided, comprising, by weight, 41-191 parts of a rosin-based bio-based UV-curable resin, 11-57 parts of a reactive diluent, and 1-9 parts of a photoinitiator. The UV-curable composition of the present invention can be used in adhesives, sealants, UV-curable coatings, and other fields.

[0036] In some embodiments, the reactive diluent is selected from at least one of acrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, isobornyl acrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, and hydroxyacrylates. Hydroxyacrylates, a raw material for the rosin-based bio-based UV-curable resin reaction, can also be used as reactive diluents to reduce the raw materials required to prepare the UV-curable composition. By controlling the amount of reactive diluent, a UV-curable composition meeting the desired properties can be prepared.

[0037] In some embodiments, the photoinitiator is selected from at least one of 2-hydroxy-2-methyl-1-phenyl-1-propanone, hydroxycyclohexane phenyl ketone, 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone, 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinobenzylphenyl)butanone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and benzophenone.

[0038] In some embodiments, the amount of the photoinitiator used is 2-4% of the total weight of the reactive diluent and the rosin-based bio-based UV-curable resin.

[0039] In some embodiments, the photocuring method of the rosin-based bio-based UV-curable resin composition is to mix the rosin-based bio-based UV-curable resin with a photoinitiator and crosslink under UV light with a wavelength of 300-400 nm for 2-5 minutes.

[0040] The beneficial effects of the present invention are:

[0041] The rosin-based bio-based UV-curable resin of the present invention is a trifunctional light-curable resin having a rigid tricyclic diterpene structure and a chain structure containing carbon-carbon double bonds. The cured film thereof has good mechanical properties and a high cross-linking density.

[0042] The cured film of the rosin-based bio-based UV-curable resin of the present invention has a tensile strength of not less than 63.45 MPa, an elongation at break of not less than 4.45%, a gel fraction of up to 95.52%, an adhesion of up to 2.85 MPa, a carbon residue rate of up to 6.73%, and a pencil hardness of up to 5H. It has excellent mechanical properties, adhesion properties, and thermal stability, and can be used to prepare adhesives, sealants, or UV-curable coatings.

[0043] The rosin-based bio-based UV-curable resin of the present invention is prepared from bio-based materials, has a simple preparation method, and can also reduce dependence on non-renewable resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The Fourier transform infrared spectra of formulas (II) to (IV) of the present invention are shown. DETAILED DESCRIPTION

[0045] The present invention will be further described in detail below with reference to the accompanying drawings, but the embodiments of the present invention are not limited thereto. The raw materials and reagents involved in the following examples can all be obtained from commercial channels.

[0046] Example 1

[0047] 50.00 g of MPA and 185.00 g of epichlorohydrin were added to a three-necked flask equipped with a stirring device, a condenser, and a thermometer. After heating to dissolve into a homogeneous phase, 2.35 g of tetrabutylammonium bromide was added. The reaction system was reacted at 110° C. until the acid value was less than 1 mgKOH / g, then cooled to 70° C., 15 g of sodium hydroxide was added, and then reacted for 3 hours until the pH value of the system no longer decreased. The reaction was filtered, and the filtrate was washed with deionized water until neutral. The excess epichlorohydrin was recovered by reduced pressure distillation at a temperature of 65° C. and a pressure of 120-150 Pa to obtain a yellow transparent first reaction product weighing 58.60 g.

[0048] 52.10 g HEMA, 39.20 g MA and 0.18 g hydroquinone were added to a three-necked flask with a stirring device, a condenser and a thermometer. In a nitrogen atmosphere, the reaction system was first heated to 70°C in an oil bath and stirred until the MA solid melted. The temperature was then raised to 100°C and the reaction was carried out for 5 h to obtain a second reaction product, which was a light yellow transparent liquid, weighing 37.52 g.

[0049] The first reaction product obtained above, 18.14 g of the second reaction product, 0.76 g of N,N-dimethylbenzylamine and 0.15 g of hydroquinone were added to a three-necked flask equipped with a stirring device, a condenser and a thermometer. The mixture was stirred and reacted at 105° C. in a nitrogen atmosphere for 5 h until the acid value was lower than 15 mgKOH / g. The mixture was cooled to room temperature, and 17.58 g of the second reaction product was added and mixed uniformly to obtain the final product, which was a light orange-red transparent solid.

[0050] The maleopimaric anhydride obtained above Figure 1 MPA line in), the first reaction product ( Figure 1 MPA-ER line), hydroxyethyl methacrylate ( Figure 1 HEMA line in), the second reaction product ( Figure 1 HEMMA line in) and the final product ( Figure 1 The MPA-ER-HEMMA line in the sample was used for infrared spectroscopy detection, and the detection results were as follows: Figure 1 As shown. Figure 1 It can be seen that MPA at 1704cm -1 、1775cm -1 and 1844cm -1 The characteristic absorption peak attributed to the anhydride structure appeared; while the peak of MPA-ER was at 1704 cm -1 、1775cm -1 and 1844cm -1 The anhydride structure peak disappeared and the peak at 1735 cm -1 The characteristic absorption peak attributed to the ester group appears at 756 cm -1 、846cm -1 and 908cm -1 The characteristic peak of epoxy group (Epoxy) appears in the fingerprint area, indicating that MPA and epichlorohydrin have undergone esterification reaction to generate ester group. -1 The characteristic peaks attributed to hydroxyl groups appear around 1723 cm, which may be the hydroxyl peaks of the intermediate product of the reaction of formula (III) that did not participate in the ring closure reaction and the hydroxyl peaks of the residual carboxyl groups of MPA. -1 and 1633cm -1 The characteristic peaks of 3500 cm-1 are attributed to the ester carbonyl group and the carbon-carbon double bond, respectively. -1 The characteristic peak of HEMMA is attributed to hydroxyl groups; while the peak of HEMMA is at 816 cm -1 A new characteristic peak of carbon-carbon double bond appears at 2500-3400 cm –1 A broad carboxyl peak appeared, and at 3500 cm -1The characteristic absorption peak attributed to the hydroxyl group at 3521 cm-1 was basically disappeared, indicating that the hydroxyl group of HEMA reacted with MA to form a new carbon-carbon double bond through Diels-Alder reaction. -1 The intensity of the characteristic absorption peak attributed to hydroxyl groups at 1728 cm-1 is significantly stronger than that of MPA-ER, while the broad carboxyl peak and the characteristic peak of epoxy groups in the fingerprint region disappear. This is because the epoxy groups of MPA-ER react with the carboxyl groups of HEMMA to form hydroxyl groups. The absorption peaks of the ester carbonyl group and carbon-carbon double bond originally belonging to HEMMA move to 1728 cm-1, respectively. -1 and 1638cm -1 , 816cm -1 The characteristic peaks are attributed to the carbon-carbon double bond of HEMMA, indicating that the epoxy group of MPA-ER and the carboxyl group of HEMMA undergo a ring-opening reaction to generate hydroxyl groups, and the final product MPA-ER-HEMMA has a carbon-carbon double bond structure.

[0051] Example 2

[0052] The difference between this example and Example 1 is that 44.79 g of the prepared second reaction product was weighed, 58.60 g of the first reaction product, 27.21 g of the second reaction product, 0.76 g of N,N-dimethylbenzylamine and 0.17 g of hydroquinone were added to a three-necked flask equipped with a stirring device, a condenser and a thermometer, and the mixture was stirred at 105° C. in a nitrogen atmosphere for 5 h until the acid value was lower than 15 mgKOH / g. The mixture was cooled to room temperature, 17.58 g of HCl was added, and the mixture was mixed uniformly to obtain the final product, which was a light orange-red transparent solid.

[0053] Example 3

[0054] The difference between this example and Example 1 is that 53.86 g of the prepared second reaction product was weighed, 58.60 g of the first reaction product, 36.28 g of the second reaction product, 0.95 g of N,N-dimethylbenzylamine and 0.19 g of hydroquinone were added to a three-necked flask equipped with a stirring device, a condenser and a thermometer, and the mixture was stirred and reacted at 105° C. in a nitrogen atmosphere for 5 h until the acid value was lower than 15 mgKOH / g. The mixture was cooled to room temperature, 17.58 g of the second reaction product was added, and the mixture was mixed uniformly to obtain a final product, which was a light orange-red transparent solid.

[0055] Example 4

[0056] This embodiment provides a method for preparing a rosin-based bio-based UV-curable resin. The difference between this embodiment and Example 1 is that 60.93 g of the prepared second reaction product is weighed, 58.60 g of the first reaction product, 43.35 g of the second reaction product, 1.02 g of N,N-dimethylbenzylamine, and 0.20 g of hydroquinone are added to a three-necked flask equipped with a stirring device, a condenser, and a thermometer. The mixture is stirred and reacted at 105° C. in a nitrogen atmosphere for 5 hours until the acid value is lower than 15 mgKOH / g. The mixture is then cooled to room temperature, and 17.58 g of the second reaction product is added. The mixture is mixed uniformly to obtain a final product, which is a light orange-red transparent solid.

[0057] Example 5

[0058] The difference between this example and Example 1 is that 81.07 g of the prepared second reaction product was weighed, 58.60 g of the first reaction product, 63.49 g of the second reaction product, 1.22 g of N,N-dimethylbenzylamine and 0.24 g of hydroquinone were added to a three-necked flask equipped with a stirring device, a condenser and a thermometer, and the mixture was stirred and reacted at 105° C. in a nitrogen atmosphere for 5 h until the acid value was lower than 15 mgKOH / g. The mixture was cooled to room temperature, 17.58 g of the second reaction product was added, and the mixture was mixed uniformly to obtain a final product, which was a light orange-red transparent solid.

[0059] Examples 6 to 14

[0060] The difference between Examples 6 to 14 and Example 1 is that when preparing the first reaction product, the added catalyst and the amount are different; when preparing the final product, the final product catalyst and the amount, the active diluent and the amount are different, as shown in Table 1.

[0061] Table 1 Selection and dosage of various reagents in Example 1 and Examples 6 to 14

[0062]

[0063] Examples 15 to 19

[0064] The differences between Examples 15 to 19 and Example 1 are the weight of the first reaction product, the weight of the second reaction product, the selection of polymerization inhibitor, and the amount of polymerization inhibitor added twice, as shown in Table 2.

[0065] Table 2 The mass of the first reaction product, the mass of the second reaction product, the amount of the inhibitor and the two additions in Example 1 and Examples 15 to 19

[0066]

[0067]

[0068] Example 20

[0069] 41 g of the final product prepared in Example 1 was mixed with 5 g of 2-hydroxy-2-methyl-1-phenyl-1-propanone to obtain a UV-curable composition.

[0070] Examples 21 to 27

[0071] The difference between Examples 21 to 27 and Example 20 lies in the different amounts of the final products, the selection of photoinitiators, and the amounts of photoinitiators used, as shown in Table 3.

[0072] Table 3 Composition of the UV-curable compositions of Examples 20 to 27

[0073]

[0074] Comparative Example 1

[0075] 50.00 g of MPA and 185.00 g of epichlorohydrin were added to a three-necked flask equipped with a stirring device, a condenser, and a thermometer. After heating to dissolve into a homogeneous phase, 2.35 g of tetrabutylammonium bromide was added. The reaction system was reacted at 110° C. until the acid value reached below 1 mgKOH / g. The temperature was then lowered to 70° C., 15 g of sodium hydroxide was added, and the reaction was continued for 3 h until the pH value of the system no longer decreased. NaCl was removed by filtration, and the filtrate was washed with water until neutral. Excess epichlorohydrin was recovered by distillation under reduced pressure at 65° C. and a pressure of 120-150 Pa to obtain MAP-ER.

[0076] 58.60 g of MPA-ER, 11.46 g of acrylic acid, 0.70 g of N,N-dimethylbenzylamine, and 0.14 g of hydroquinone were added to a three-necked flask equipped with a stirring device, a condenser, and a thermometer. The mixture was reacted at 100° C. for 5 h in a nitrogen atmosphere. The mixture was cooled to room temperature, and 17.58 g of acrylic acid was added and mixed uniformly to obtain MPA-ER-AA.

[0077] After observation, MPA-ER-AA was a brown transparent solid.

[0078] Comparative Example 2

[0079] 52.10 g HEMA, 39.20 g MA and 0.18 g hydroquinone were added to a three-necked flask equipped with a stirring device, a condenser and a thermometer. In a nitrogen atmosphere, the reaction system was first heated to 70°C in an oil bath and stirred until the MA solid melted. The temperature was then raised to 100°C and the reaction was continued for 5 h to obtain HEMMA.

[0080] 50.00 g of soybean oil triglycidyl ester (ESO), 43.50 g of HEMMA, 0.94 g of N,N-dimethylbenzylamine and 0.19 g of hydroquinone were added to a three-necked flask equipped with a stirring device, a condenser and a thermometer. The mixture was stirred at 105°C for 5 h in a nitrogen atmosphere until the acid value was lower than 15 mgKOH / g. The mixture was cooled to room temperature, 15.00 g of HEMMA was added and mixed uniformly to obtain ESO-HEMMA.

[0081] Upon observation, ESO-HEMMA was a light red transparent solid.

[0082] Comparative Example 3

[0083] 52.10 g HEMA, 39.20 g MA and 0.18 g hydroquinone were added to a three-necked flask equipped with a stirring device, a condenser and a thermometer. In a nitrogen atmosphere, the reaction system was first heated to 70°C in an oil bath and stirred until the MA solid melted. The temperature was then raised to 100°C and the reaction was continued for 5 h to obtain HEMMA.

[0084] 45.40 g of epoxy resin E-44, 45.60 g of HEMMA, 0.84 g of N,N-dimethylbenzylamine and 0.17 g of hydroquinone were added to a three-necked flask equipped with a stirring device, a condenser and a thermometer. The mixture was stirred at 105° C. for 5 h in a nitrogen atmosphere until the acid value was lower than 15 mgKOH / g. The mixture was cooled to room temperature, 13.62 g of HEMMA was added, and the mixture was mixed uniformly to obtain a UV-curable resin.

[0085] Upon observation, the UV-curable resin was a light yellow transparent solid.

[0086] Experimental Example 1

[0087] In this experimental example, the cured films of the rosin-based bio-based UV-curable resins prepared in Examples 1-5 and Comparative Example 1, and the UV-curable resins prepared in Comparative Examples 2-3 were subjected to plastic tensile properties, gel fraction, adhesion, pencil hardness, and thermogravimetric tests, respectively. The results are shown in Table 4.

[0088] The cured film was prepared by mixing the rosin-based bio-based UV-curable resins prepared in Examples 1-5 and Comparative Example 1, and the UV-curable resins prepared in Comparative Examples 2-3, respectively, with a photoinitiator 1173 in an amount of 3% of the total mass of the UV-curable resins, and then UV-curing the mixture for 3 minutes under UV light with a wavelength of 365 nm.

[0089] The cured films prepared from the rosin-based, bio-based UV-curable resins of Examples 1-5 were labeled F1, F2, F3, F4, and F5, respectively. The cured film of the rosin-based, bio-based UV-curable resin of Comparative Example 1 was labeled F6. The cured films of the UV-curable resins of Comparative Examples 2 and 3 were labeled F7 and F8, respectively. F1-F8 were the samples used in the tests of this experimental example.

[0090] 1. Plastic tensile properties test

[0091] The plastic tensile properties of samples F1 to F8 were tested using a Shimadzu AGS-X 1 kN universal testing machine. The dumbbell-shaped sample specifications refer to GB / T 1040.2-2006, and the crosshead speed is 1 mm min. -1 In order to ensure the accuracy of the test results, each sample was tested three times and the test results were averaged.

[0092] 2. Gel rate test

[0093] 0.5g of each sample, F1-F8, was immersed in 10mL of acetone at room temperature for 48 hours, then dried in an oven at 60°C to constant weight. To ensure accuracy, each sample was tested three times, and the average of the results was taken. The gel fraction (GC) was calculated according to the following formula:

[0094]

[0095] Among them, W a W0 is the weight of the cured film after immersion and drying, and W0 is the original weight of the cured film.

[0096] 3. Adhesion test

[0097] Using a 250μm four-sided applicator, 2-5g of each of the rosin-based bio-based UV-curable resins from Examples 1-5 and Comparative Example 1, and the UV-curable resins from Comparative Examples 2-3, were mixed uniformly with photoinitiator 1173 at a rate of 3% of the total mass of the UV-curable resin. The mixture was then evenly coated on a galvanized iron plate and cured under UV light at a wavelength of 365nm for 3 minutes. A spindle was then secured to the cured film with glue. After standing for 24 hours, adhesion was tested using a fully automatic pull-off adhesion tester with a range of 0.7-20MPa. To ensure accuracy, each sample was tested three times, and the average of the results was calculated.

[0098] 4. Pencil hardness test

[0099] The pencil hardness of cured films F1 to F8 was tested according to GB / T 6739-2022, "Paints and varnishes - Determination of film hardness by pencil method." To ensure accuracy, each sample was tested three times, and the average of the results was taken.

[0100] 5. Thermogravimetric test

[0101] Thermogravimetric analysis of the cured films of F1 to F8 was performed using a Netzsch STA 449C thermal analyzer. The temperature range required for the thermogravimetric analysis of the samples was set to 35-800°C, and the heating rate was 10°C min -1 During the test, the nitrogen environment was maintained and the nitrogen introduction rate was 20 mL min -1 To test the accuracy of the results, each sample was measured three times and the average value was taken.

[0102] The samples were subjected to thermogravimetric analysis, and the thermal degradation temperature (T 10％ ), 50% thermal degradation temperature (T 50％ ), and the carbon residue rate at 800℃.

[0103] Table 4 Comprehensive performance test results of cured film

[0104]

[0105] As can be seen from Table 4, the tensile strength of the cured films of the rosin-based bio-based UV-curable resin of Examples 1-5 can reach up to 71.23 MPa, and the elongation at break is up to 9.55%, indicating that the cured films of the rosin-based bio-based UV-curable resin of the present invention have good mechanical properties. The best result of the adhesion test is 2.85 MPa, indicating that the rosin-based bio-based UV-curable resin of the present invention has good adhesion properties after being cured into a film. From the thermogravimetric test results, in the cured films of each example, T 10％ and T 50％ The highest temperatures can reach 308.53°C and 411.82°C, respectively, and the highest carbon residue rate can reach 6.73%, indicating that the cured films of the rosin-based bio-based UV-curable resin of the present invention have good thermal stability. The gel fraction test results show that the gel fraction of the cured films of the rosin-based bio-based UV-curable resin of Examples 1-5 can reach up to 95.52%, indicating that the crosslinking density of the cured films of the rosin-based bio-based UV-curable resin of the present invention is relatively high. In addition, the pencil hardness test results show that the pencil hardness of the cured films of the rosin-based bio-based UV-curable resin of Examples 1-5 is between 3H and 5H, indicating that the cured films of the rosin-based bio-based UV-curable resin of the present invention have good hardness.

[0106] Below, the comprehensive performance test results of the cured films of the rosin-based bio-based UV-curable resin of Examples 1-5 are used to illustrate the effect of HEMMA content on the various properties of the cured films. Specifically, at the beginning, as the HEMMA content increases, the various performance test results of the cured films of the rosin-based bio-based UV-curable resin of the present invention improve. Among them, as the HEMMA content increases, the tensile strength increases from 63.45MPa to 71.23MPa, and the elongation at break increases from 4.45% to 9.55%, indicating that the amount of HEMMA selected brings about a significant improvement in the flexibility and mechanical properties of the rosin-based bio-based UV-curable resin. This is because when MPA-ER reacts with HEMMA, a side chain structure containing carbon-carbon double bonds is introduced, which significantly improves the curing efficiency and cross-linking density during UV curing. After reaching a peak, the performance test results decreased with increasing HEMMA content. This may be because the chain structure of HEMMA reacts with the hydroxyl groups after the ring opening of MPA-ER, resulting in a decrease in the relative content of the rigid structure of the product, which leads to an unstable network structure of the rosin-based bio-based UV-curable resin. In addition, compared with the comprehensive performance test results of the cured film of the rosin-based bio-based UV-curable resin without HEMMA (Comparative Example 1), the various properties of the cured films of the rosin-based bio-based UV-curable resin of Examples 1-5 were significantly improved. Therefore, the present invention can prepare a rosin-based bio-based UV-curable resin that meets the performance requirements by selecting the amount of hydroxyacrylate.

[0107] Comparison of various performance test results of the cured films of the rosin-based bio-based UV-curable resins of Examples 1-5 with those of the UV-curable resins of Comparative Examples 2 and 3 revealed that the cured films of the rosin-based bio-based UV-curable resins of the present invention exhibited significantly better performance than the cured films of the UV-curable resin of Comparative Example 2, demonstrating that the HEMMA-modified MPA-ER of the present invention is superior to the HEMMA-modified epoxidized soybean oil (ESO). Furthermore, the mechanical performance test results of the cured films of the rosin-based bio-based UV-curable resins of the present invention were similar to those of the cured films of the UV-curable resin of Comparative Example 3. The cured films of the UV-curable resin of Comparative Example 3 exhibited superior thermal stability performance tests, which is due to the higher thermal decomposition temperature of the aromatic benzene rings in the E-44 epoxy resin and the higher thermal decomposition temperature of the aliphatic hydrophenanthrene rings in the MPA-ER. In addition, the cured films of the rosin-based bio-based UV-curable resin in some examples showed better elongation at break, gel fraction, adhesion, and pencil hardness test results than those of Comparative Example 3, indicating that the cured films of the rosin-based bio-based UV-curable resin obtained by using HEMMA-modified bio-based MPA-ER in the present invention have similar mechanical properties to those of the UV-curable resin cured films obtained by using HEMMA-modified petroleum-based epoxy resin E-44, and some performance tests showed even better results, indicating that the present invention has found a good bio-based alternative material for UV-curable resin.

[0108] In summary, the rosin-based bio-based UV-curable resin of the present invention has both the rigid structure unique to maleic maritime pine epoxy resin and a chain structure containing carbon-carbon double bonds, which not only helps to improve the rigid structure content, crosslinking density and flexibility of the cured film of the rosin-based bio-based UV-curable resin, but also enables the cured film of the rosin-based bio-based UV-curable resin of the present invention to have good mechanical properties, adhesion properties and thermal stability.

[0109] The present invention discloses a method for preparing a rosin-based bio-based UV-curable resin. First, a maleic pine epoxy resin is modified with hydroxy acrylate, and a chain structure containing carbon-carbon double bonds is introduced into the maleic pine epoxy resin. The preparation method is simple and uses bio-based materials as raw materials, making it environmentally friendly. The rosin-based bio-based UV-curable resin prepared by this method, after UV-curing to form a film, exhibits a tensile strength of 71.23 MPa, a gel fraction of 95.52%, an adhesion of 2.85 MPa, a carbon residue of 6.73%, and a pencil hardness of 5H. In addition, the comprehensive performance of the cured film of the rosin-based bio-based UV-curable resin of the present invention is significantly better than that of the cured film of the bio-based UV-curable resin obtained by acrylate-modified epoxidized soybean oil; the tensile strength of the cured film of the rosin-based bio-based UV-curable resin is close to that of the cured film of the UV-curable resin obtained by HEMMA-modified petroleum-based epoxy resin E-44, and the former can obtain better test results in adhesion, gel fraction and pencil hardness tests.

[0110] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the inventive concept of the present invention, which all fall within the scope of protection of the present invention.

Claims

1. A rosin-based bio-based UV-curable resin, characterized in that: Its structural formula is shown in formula (I):

2. The method for preparing the rosin-based bio-based UV-curable resin according to claim 1, characterized in that: 27-79 parts of maleic pine epoxy resin, 15-77 parts of hydroxy acrylate, 0.05-0.75 parts of polymerization inhibitor and 0.07-1.53 ​​parts of the first catalyst are mixed, heated to 80-130° C. in a nitrogen atmosphere, and reacted until the acid value is less than 15 mgKOH / g to obtain the product; The first catalyst is selected from at least one of N,N-dimethylbenzylamine, benzyltriethylammonium chloride, dibutyltin dilaurate, triethylamine, and triphenylphosphine; and the polymerization inhibitor is selected from at least one of a phenolic polymerization inhibitor or an amine polymerization inhibitor.

3. The method for preparing a rosin-based bio-based UV-curable resin according to claim 2, wherein: The phenolic polymerization inhibitor is selected from at least one of dinoseb, hydroquinone, and p-tert-butylcatechol, and the amine polymerization inhibitor is diethylhydroxylamine.

4. The method for preparing a rosin-based bio-based UV-curable resin according to claim 2 or 3, characterized in that: The maleic pine epoxy resin is prepared by the following steps: After heating and dissolving maleopimaric anhydride and epichlorohydrin into a homogeneous phase, a quaternary ammonium salt catalyst is added, and the mixture is reacted at 80-130°C until the acid value is less than 1 mgKOH / g. The mixture is then cooled to 50-90°C, and sodium hydroxide is added. The mixture is reacted until the pH value no longer decreases, and the epichlorohydrin is removed by reduced pressure distillation at a temperature of 60-70°C and a pressure of 150-160 Pa to obtain the product. Wherein, in parts by weight, the amount of maleopimaric anhydride is 27-79 parts, the amount of epichlorohydrin is 165-225 parts, the amount of quaternary ammonium salt catalyst is 0.13-1.50 parts, and the amount of sodium hydroxide is 8-33 parts.

5. The method for preparing a rosin-based bio-based UV-curable resin according to claim 4, wherein: The quaternary ammonium salt catalyst is selected from at least one of tetrabutylammonium bromide and benzyltriethylammonium chloride.

6. The method for preparing a rosin-based bio-based UV-curable resin according to claim 2 or 3, characterized in that: The hydroxyacrylate is prepared by the following steps: Mix hydroxyethyl methacrylate, maleic anhydride and polymerization inhibitor, and react in a nitrogen atmosphere at a temperature of 80-130°C for 3.5-8.5h to obtain; Wherein, in parts by weight, the amount of hydroxyethyl methacrylate is 33-77 parts, the amount of maleic anhydride is 19-59 parts, and the amount of the polymerization inhibitor is 0.05-0.25 parts.

7. Use of the rosin-based bio-based UV-curable resin according to claim 1 in adhesives, sealants or UV-curable coatings.

8. A UV-curable composition, characterized in that In parts by weight, comprising 41-191 parts of the rosin-based bio-based UV-curable resin according to claim 1, 11-57 parts of a reactive diluent, and 1-9 parts of a photoinitiator; Wherein, the reactive diluent is selected from at least one of acrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, isobornyl acrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, and hydroxy acrylate; The photoinitiator is selected from at least one of 2-hydroxy-2-methyl-1-phenyl-1-propanone, hydroxycyclohexane phenyl ketone, 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone, 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinobenzylphenyl)butanone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and benzophenone.

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