Bio-based flame retardant UV-curable prepolymer and preparation method and application thereof

Abstract

The present invention belongs to the technical field of UV curing materials, and specifically relates to a bio-based flame retardant ultraviolet light curing prepolymer and its preparation method and application. The present invention uses vegetable oil acid as a bio-based raw material and hydroxy acrylate to prepare vegetable oil-based acrylate through esterification reaction, uses triethyl phosphonoacetate, alcohol amine compounds, and methacrylic anhydride to react to prepare a phosphorus-containing monomer, and then uses anhydride, silane and hydroxy acrylate to react to prepare a silicon-containing monomer, and then the vegetable oil-based acrylate, phosphorus-containing monomer, and silicon-containing monomer are uniformly mixed in a certain proportion to prepare a bio-based flame retardant ultraviolet light curing prepolymer. The present invention uses bio-based raw materials to reduce the use of petrochemical resources; at the same time, the present invention prepares phosphorus-containing monomers and silicon-containing monomers containing flame retardant elements, so that the prepared cured film has excellent flame retardant properties and has a wide range of applications in the field of UV curing materials.

Description

Technical Field

[0001] The invention belongs to the technical field of UV curing materials, and in particular relates to a bio-based flame retardant ultraviolet curing prepolymer and a preparation method and application thereof. Background Art

[0002] UV curing technology refers to a fast and effective method that converts oligomers and active diluents into cross-linked polymer networks at room temperature under the initiation of photoinitiators. It has the advantages of energy saving and low curing temperature. Currently, the photocurable prepolymers on the market are mainly prepared by polymerization of traditional chemical products. These products are derived from non-renewable petroleum resources and have problems such as difficulty in degradation and environmental pollution. Therefore, it is necessary to develop low-cost, renewable and green photocurable prepolymers.

[0003] Vegetable oil has become a raw material source for photocurable prepolymers due to its high yield and renewable nature. Traditional vegetable oil-based materials are generally highly flammable, and flame retardants are often added to vegetable oil-based materials to improve the flammability of the materials. Traditional flame retardants are generally additive flame retardants and reactive flame retardants. Additive flame retardants will affect the mechanical properties of vegetable oil-based materials after compounding, and halogen-containing flame retardants will release toxic gases during combustion, causing adverse effects on the environment and human health; reactive flame retardants mainly participate in the polymerization reaction of materials as monomers containing flame retardant ingredients, and have little effect on the performance of materials, but reactive flame retardants have a narrow application range, few varieties, and high prices. Therefore, when preparing photocurable prepolymers with bio-based raw materials, how to improve the flame retardant and mechanical properties of the cured film obtained by curing the prepolymer to obtain a cured film with excellent flame retardant and mechanical properties needs further study. Summary of the invention

[0004] The first object of the present invention is to provide a bio-based flame retardant UV-curable prepolymer. The second object of the present invention is to provide a method for preparing the bio-based flame retardant UV-curable prepolymer. The third object of the present invention is to provide an application of the bio-based flame retardant UV-curable prepolymer.

[0005] According to a first aspect of the present invention, a bio-based flame retardant UV-curable prepolymer is provided, wherein the raw materials thereof include: a plant oil-based acrylate, a phosphorus-containing monomer, a silicon-containing monomer, and a photoinitiator, wherein the mass ratio of the plant oil-based acrylate, the phosphorus-containing monomer, and the silicon-containing monomer is (2-4): (1-2): (1-2), and the amount of the photoinitiator is 1-5wt% of the total amount of the reactants. The reactants herein refer to the plant oil-based acrylate, the phosphorus-containing monomer, and the silicon-containing monomer.

[0006] In some embodiments, the method for preparing the vegetable oil-based acrylate comprises the following steps:

[0007] The vegetable oil acid, the first hydroxy acrylate, the first catalyst, the first inhibitor and the solvent are mixed, and reacted at 100-130° C. for 4-8 hours. After the reaction is completed, the reaction product is washed, dried, and then the solvent is removed by rotary evaporation to obtain the product.

[0008] In some embodiments, the vegetable oleic acid is at least one of ricinoleic acid, eleostearic acid, and oleic acid.

[0009] In some embodiments, the first hydroxy acrylate is at least one of hydroxyethyl methacrylate, hydroxyethyl acrylate, 4-hydroxybutyl acrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, and hydroxybutyl acrylate.

[0010] In some embodiments, the first catalyst is p-toluenesulfonic acid.

[0011] In some embodiments, the first inhibitor is at least one of hydroquinone, p-hydroxyanisole, and tert-butylcatechol.

[0012] In some embodiments, the solvent is at least one of toluene, cyclohexane, ethyl acetate, and acetone.

[0013] In some embodiments, the amount of vegetable oleic acid used is 5-15 parts by weight, and the amount of the first hydroxy acrylate used is 2-8 parts by weight.

[0014] In some embodiments, the first catalyst is used in an amount of 1 to 4 wt % of the total amount of reactants, wherein the reactants refer to vegetable oleic acid and the first hydroxy acrylate.

[0015] In some embodiments, the first polymerization inhibitor is used in an amount of 0.01 to 3 wt % of the total amount of reactants, wherein the reactants refer to vegetable oleic acid and the first hydroxy acrylate.

[0016] In some embodiments, the amount of the solvent is 0.5 to 1.5 times the total amount of the reactants. The reactants here refer to vegetable oleic acid and the first hydroxy acrylate.

[0017] In some embodiments, the method for preparing the phosphorus-containing monomer comprises the following steps:

[0018] The phosphonoacetic acid triethyl ester, the alcohol amine compound and the second catalyst are mixed, and reacted at 100-130°C for 1-3h. After the reaction is completed, the temperature is cooled to room temperature, and the reaction product is washed. Then, methacrylic anhydride and the second polymerization inhibitor are added, and the reaction is carried out at 25-45°C for 13-18h. After the reaction is completed, the heating is stopped, and an appropriate amount of saturated sodium bicarbonate aqueous solution is added and stirred for 30-60min to react the sodium bicarbonate with the by-product methacrylic acid generated in the previous reaction to generate volatile methyl methacrylate, and then the methyl methacrylate is removed by rotary evaporation to obtain the phosphorus-containing monomer.

[0019] In some embodiments, the alcoholamine compound is at least one of ethanolamine, 3-amino-1,2-propylene glycol, isopropanolamine, 3-amino-1-propanol, and 6-amino-1-hexanol.

[0020] In some embodiments, the second catalyst is at least one of sodium methoxide, sodium hydroxide, potassium hydroxide, triethylamine, triphenylphosphine, 4-dimethylaminopyridine, pyridine, and p-toluenesulfonic acid.

[0021] In some embodiments, the second polymerization inhibitor is at least one of hydroquinone, tert-butylcatechol, and p-methoxyphenol.

[0022] In some embodiments, based on parts by mass, the amount of triethyl phosphonoacetate used is 5-15 parts, the amount of the alcoholamine compound used is 2-10 parts, and the amount of methacrylic anhydride used is 2.5-12 parts.

[0023] In some embodiments, the amount of the second catalyst added is 1-4 wt % of the total amount of the reactants, wherein the reactants refer to triethyl phosphonoacetate and alcoholamine compounds.

[0024] In some embodiments, the amount of the second polymerization inhibitor added is 0.01 to 4 wt % of the mass of methacrylic anhydride.

[0025] In some embodiments, the method for preparing the silicon-containing monomer comprises the following steps:

[0026] The acid anhydride and the silane are mixed, reacted at 60-80° C. for 2-4 hours, and then the second hydroxy acrylate, the third catalyst and the third polymerization inhibitor are added, and reacted at 90-110° C. for 4-6 hours to obtain a silicon-containing monomer.

[0027] In some embodiments, the anhydride is itaconic anhydride and / or maleic anhydride.

[0028] In some embodiments, the silane is at least one of 3-aminopropylmethyldimethoxysilane, N-aminoethyl-3-aminopropyltriethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane.

[0029] In some embodiments, the second hydroxy acrylate is at least one of hydroxyethyl methacrylate, hydroxyethyl acrylate, 4-hydroxybutyl acrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, and hydroxybutyl acrylate.

[0030] In some embodiments, the third catalyst is at least one of 4-dimethylaminopyridine, sodium methoxide, and p-toluenesulfonic acid.

[0031] In some embodiments, the third polymerization inhibitor is at least one of hydroquinone, tert-butylcatechol, and p-methoxyphenol.

[0032] In some embodiments, the amount of the acid anhydride is 5-15 parts, the amount of the silane is 9-33 parts, and the amount of the second hydroxy acrylate is 5-20 parts, calculated by weight.

[0033] In some embodiments, the third catalyst is used in an amount of 1 to 4 wt % of the total amount of reactants, wherein the reactants refer to anhydride, silane and the second hydroxy acrylate.

[0034] In some embodiments, the third polymerization inhibitor is used in an amount of 0.01 to 5 wt % of the mass of the second hydroxy acrylate.

[0035] In some embodiments, the photoinitiator is at least one of 2-hydroxy-2-methylpropiophenone, diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide, 1-hydroxycyclohexylphenyl ketone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, α,α-dimethoxy-α-phenylacetophenone, and diphenyl-(4-phenylthio)phenylsulfonium hexafluorophosphate.

[0036] According to a second aspect of the present invention, there is provided a method for preparing the above-mentioned bio-based flame retardant UV-curable prepolymer, comprising the following steps:

[0037] The vegetable oil-based acrylate, phosphorus-containing monomer, silicon-containing monomer and photoinitiator are uniformly mixed.

[0038] According to a third aspect of the present invention, there is provided a use of the above-mentioned bio-based flame retardant UV-curable prepolymer in the preparation of UV-curable coatings, UV-curable inks, UV-curable adhesives or 3D printing materials.

[0039] The beneficial effects of the present invention include:

[0040] (1) The present invention uses vegetable oil acid as a bio-based raw material and hydroxy acrylate to prepare vegetable oil-based acrylate through an esterification reaction, uses triethyl phosphonoacetate, an alcohol amine compound, and methacrylic anhydride to react to prepare a phosphorus-containing monomer, and then uses anhydride, silane and hydroxy acrylate to react to prepare a silicon-containing monomer, and then the vegetable oil-based acrylate, the phosphorus-containing monomer, and the silicon-containing monomer are uniformly mixed in a certain proportion to prepare a bio-based flame-retardant UV-curable prepolymer. On the one hand, phosphorus and silicon are effective flame retardant components. Introducing phosphorus and silicon into the prepolymer can make the cured film effectively flame retardant; on the other hand, using renewable and cheap biomass materials as the main raw materials reduces the utilization of non-renewable petrochemical resources. Vegetable oleic acid has a long fatty acid chain. Introducing vegetable oleic acid to synthesize vegetable oil-based acrylates can enhance the flexibility of the cured film. At the same time, the extremely high functionality can enhance the cross-linking density of the cured film, thereby enhancing the tensile strength of the cured film and improving the pencil hardness of the cured film. In addition, when preparing phosphorus-containing monomers and silicon-containing monomers, acid anhydrides are used as raw materials. The acid anhydrides contain active double bonds, can be photocured, and have a chain extension effect on the monomers, thereby increasing the cross-linking density of the photocured film, thereby improving the flexibility and tensile strength of the photocured film and other properties.

[0041] (2) On the one hand, the present invention uses a simple method to synthesize plant oil-based acrylate in one step. The preparation process is green and environmentally friendly, and bio-based raw materials are used to reduce the use of petrochemical resources. On the other hand, phosphorus-containing monomers and silicon-containing monomers containing flame retardant elements are prepared, so that the cured film prepared from the bio-based flame retardant UV-curable prepolymer of the present invention has excellent flame retardant properties and has a wide range of applications in the field of UV-curable materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a synthetic route of tung oil-based acrylate (EAH), phosphorus-containing monomer (TMAM), and silicon-containing monomer (TAPH) in Example 1 of the present invention.

[0043] Figure 2 These are the infrared spectrum test results of tung oil-based acrylate (EAH), phosphorus-containing monomer (TMAM), and silicon-containing monomer (TAPH) in Example 1 of the present invention.

[0044] Figure 3 Graph showing stress-strain curves of photocured films made from prepolymers of Examples 1-3 of the present invention.

[0045] Figure 4 This is a thermal decomposition curve of the photocured film made from the prepolymer of Examples 1-3 of the present invention. DETAILED DESCRIPTION

[0046] The present invention is further described in detail below in conjunction with specific examples, but the embodiments of the present invention are not limited thereto. The raw materials involved in the following examples can all be obtained from commercial channels.

[0047] In the following examples, the stirring speed is 200 rpm.

[0048] Example 1

[0049] The method for preparing the bio-based flame retardant UV-curable prepolymer of this embodiment comprises the following steps:

[0050] (1) In a three-necked flask, 10 g of tung oil acid, 6 g of hydroxyethyl acrylate, 0.3 g of p-toluenesulfonic acid as a catalyst, and 0.2 g of hydroquinone as an inhibitor were added, diluted with 20 mL of toluene, and stirred for reaction at 120° C. for 6 h. After the reaction was completed, the reaction product was washed 5 times with a saturated sodium chloride solution, dried with anhydrous magnesium sulfate for 12 h, filtered, and then rotary evaporated to remove toluene to obtain tung oil-based acrylate (abbreviated as EAH).

[0051] (2) In another three-necked flask, 10 g of triethyl phosphonoacetate, 4.5 g of ethanolamine, and 0.35 g of sodium methoxide catalyst were added, and the mixture was stirred at 120° C. for 2 h. After the reaction was completed, the mixture was cooled to room temperature, and the reaction product was washed with acetone 5 times. Then, 10 g of methacrylic anhydride and 0.4 g of hydroquinone as an inhibitor were added, and the mixture was stirred at 35° C. for 14 h. After the reaction was completed, heating was stopped, and about 65 mL of saturated sodium bicarbonate aqueous solution was added and stirred vigorously for 30 minutes, and then rotary evaporated to obtain a phosphorus-containing monomer (abbreviated as TMAM).

[0052] (3) In another three-necked flask, 10 g of itaconic anhydride and 20 g of 3-aminopropyltriethoxysilane were added, and the mixture was stirred at 70° C. for 3 h. Then, 11.6 g of hydroxyethyl methacrylate, 1 g of p-toluenesulfonic acid as a catalyst, and 0.4 g of hydroquinone as an inhibitor were added, and the mixture was stirred at 100° C. for 6 h to obtain a silicon-containing monomer (abbreviated as TAPH).

[0053] (4) In another three-necked flask, add 3 g of tung oil-based acrylate obtained in step (1), 2 g of the phosphorus-containing monomer obtained in step (2), 1 g of the silicon-containing monomer obtained in step (3), and 0.3 g of photoinitiator bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and mix well to obtain a bio-based flame-retardant UV-curable prepolymer.

[0054] The synthetic route of tung oil-based acrylate (EAH), phosphorus-containing monomer (TMAM), and silicon-containing monomer (TAPH) in this embodiment is as follows: Figure 1 shown.

[0055] Example 2

[0056] The preparation method of the bio-based flame retardant UV-curable prepolymer of this embodiment is basically the same as that of Example 1, except that in step (4), the amount of tung oil-based acrylate added is 2 g, and the amount of silicon-containing monomer added is 2 g.

[0057] Example 3

[0058] The preparation method of the bio-based flame retardant UV-curable prepolymer of this embodiment is basically the same as that of Example 1, except that in step (4), the amount of phosphorus-containing monomer added is 1 g, and the amount of silicon-containing monomer added is 2 g.

[0059] Example 4

[0060] The method for preparing the bio-based flame retardant UV-curable prepolymer of this embodiment comprises the following steps:

[0061] (1) In a three-necked flask, 9 g of ricinoleic acid, 4 g of hydroxyethyl acrylate, 0.25 g of p-toluenesulfonic acid as a catalyst, and 0.25 g of hydroquinone as an inhibitor were added, diluted with 20 mL of toluene, and stirred for reaction at 120° C. for 6 h. After the reaction was completed, the reaction product was washed 5 times with a saturated sodium chloride solution, dried with anhydrous magnesium sulfate for 12 h, filtered, and then rotary evaporated to remove toluene to obtain castor oil-based acrylate.

[0062] (2) In another three-necked flask, 10 g of triethyl phosphonoacetate, 10 g of 6-amino-1-hexanol, and 0.4 g of sodium methoxide catalyst were added, and the mixture was stirred at 120° C. for 2 h. After the reaction was completed, the mixture was cooled to room temperature, and the reaction product was washed with acetone 5 times. Then, 10 g of methacrylic anhydride and 0.4 g of hydroquinone as an inhibitor were added, and the mixture was stirred at 35° C. for 14 h. After the reaction was completed, heating was stopped, and about 65 mL of saturated sodium bicarbonate aqueous solution was added and stirred vigorously for 30 minutes, and then rotary evaporated to obtain a phosphorus-containing monomer.

[0063] (3) In another three-necked flask, 10 g of maleic anhydride and 23 g of 3-aminopropyltriethoxysilane were added, and the mixture was stirred at 70° C. for 3 h. Then, 11.8 g of hydroxyethyl acrylate, 1.2 g of p-toluenesulfonic acid as a catalyst, and 0.4 g of hydroquinone as an inhibitor were added, and the mixture was stirred at 100° C. for 6 h to obtain a silicon-containing monomer.

[0064] (4) In another three-necked flask, add 3 g of castor oil-based acrylate obtained in step (1), 2 g of phosphorus-containing monomer obtained in step (2), 1 g of silicon-containing monomer obtained in step (3), and 0.3 g of photoinitiator bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and mix well to obtain a bio-based flame-retardant UV-curable prepolymer.

[0065] Example 5

[0066] The method for preparing the bio-based flame retardant UV-curable prepolymer of this embodiment comprises the following steps:

[0067] (1) In a three-necked flask, 9 g of ricinoleic acid, 5 g of hydroxyethyl methacrylate, 0.25 g of p-toluenesulfonic acid as a catalyst, and 0.25 g of hydroquinone as an inhibitor were added, diluted with 20 mL of toluene, and stirred for reaction at 120° C. for 6 h. After the reaction was completed, the reaction product was washed 5 times with a saturated sodium chloride solution, dried with anhydrous magnesium sulfate for 12 h, filtered, and then rotary evaporated to remove toluene to obtain castor oil-based acrylate.

[0068] (2) In another three-necked flask, 10 g of triethyl phosphonoacetate, 6 g of 3-amino-1-propanol, and 0.3 g of sodium methoxide as a catalyst were added, and the mixture was stirred at 120° C. for 2 h. After the reaction was completed, the mixture was cooled to room temperature, and the reaction product was washed with acetone 5 times. Then, 10 g of methacrylic anhydride and 0.4 g of hydroquinone as an inhibitor were added, and the mixture was stirred at 35° C. for 14 h. After the reaction was completed, heating was stopped, and about 65 mL of saturated sodium bicarbonate aqueous solution was added and stirred vigorously for 30 minutes, and then rotary evaporated to obtain a phosphorus-containing monomer.

[0069] (3) In another three-necked flask, 10 g of maleic anhydride and 27 g of N-aminoethyl-3-aminopropyltriethoxysilane were added, and the mixture was stirred at 70° C. for 3 h. Then, 11.8 g of hydroxyethyl acrylate, 1.5 g of p-toluenesulfonic acid as a catalyst, and 0.5 g of hydroquinone as an inhibitor were added, and the mixture was stirred at 100° C. for 6 h to obtain a silicon-containing monomer.

[0070] (4) In another three-necked flask, add 3 g of castor oil-based acrylate obtained in step (1), 2 g of phosphorus-containing monomer obtained in step (2), 1 g of silicon-containing monomer obtained in step (3), and 0.3 g of photoinitiator bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and mix well to obtain a bio-based flame-retardant UV-curable prepolymer.

[0071] Next, the performance tests were conducted on the intermediate products and bio-based flame retardant UV-curable prepolymers obtained in Examples 1-5:

[0072] 1. The tung oil-based acrylate (EAH), phosphorus-containing monomer (TMAM), and silicon-containing monomer (TAPH) of Example 1 were tested by infrared spectroscopy. Figure 2 .

[0073] from Figure 2 It can be seen that in tung oil-based acrylate (EAH), 1177 cm -1 It refers to the COC bond in the ester group, and tung oil acid has no COC bond, indicating that tung oil-based acrylate was successfully prepared;

[0074] In phosphorus-containing monomers (TMAM), 1704 cm-1 Refers to C=O bond, 1656cm -1 It refers to the C=O bond in the amide group, indicating that the phosphorus-containing monomer was successfully prepared;

[0075] In silicon-containing monomers (TAPH), 1710 cm -1 Refers to C=O bond, 1640cm -1 refers to the C=O bond in the amide group, while 1870 cm -1 ~1750cm -1 The absence of a peak indicates that the anhydride has reacted completely, indicating that the silicon-containing monomer was successfully prepared.

[0076] 2. The bio-based flame-retardant UV-curable prepolymer prepared in Examples 1-5 was coated on a glass plate with an applicator, and then irradiated with UV light at a wavelength of 365 nm for 30-60 seconds to obtain a photocured film. The photocured film was cut into strips and the following performance tests were performed:

[0077] (1) Mechanical properties test

[0078] The tensile properties of the photocured film were tested using a UTM5000 electronic universal testing machine.

[0079] (2) Oxygen index test

[0080] The test was performed according to the method of ASTM D2863.

[0081] (3) Thermogravimetric analysis test

[0082] The photocurable film was tested using a NETZSCH TG 209F1 Libra analyzer at a flow rate of 60 ml min -1 In a nitrogen atmosphere, the temperature range is 30~800℃, and the heating rate is 10℃·min -1 .

[0083] (4) Hardness test

[0084] The test was carried out according to the method of national standard GB / T6739-1996.

[0085] (5) Acid and alkali resistance test

[0086] The photocured film was immersed in a 10% sodium hydroxide aqueous solution or a 10% hydrochloric acid aqueous solution at room temperature for 48 hours, and the dissolution of the photocured film was observed.

[0087] 3. Test results

[0088] (1) General performance

[0089] The general performance test results of the photocured films prepared from the prepolymers of Examples 1-5 are shown in Table 1.

[0090] Table 1 General properties of photocurable films

[0091] sample Pencil hardness Limiting oxygen index Acid resistance (10%) Alkali resistance (10%) Example 1 5H 22.8％ No change No change Example 2 5H 22.7％ No change No change Example 3 5H 20.4％ No change No change Example 4 6H 22.9％ No change No change Example 5 4H 22.5％ No change No change

[0092] It can be seen from Table 1 that the limiting oxygen index of the photocured films obtained by curing the prepolymers of Examples 1-2 and 4-5 is above 22%, and they have relatively excellent flame retardant properties.

[0093] The photocured films made from the prepolymers of Examples 1-5 were immersed in a 10% hydrochloric acid solution and a 10% sodium hydroxide solution for 48 hours, respectively, without any changes, which proves that the photocured films obtained by curing the prepolymers of the present invention have good acid and alkali resistance.

[0094] The pencil hardness of the photocured films prepared from the prepolymers of Examples 1 to 5 is between 4H and 6H, indicating that the photocured films obtained by curing the prepolymers of the present invention have relatively high hardness.

[0095] (2) Mechanical properties test results

[0096] The stress-strain curves of the photocured films prepared from the prepolymers of Examples 1-3 are as follows: Figure 3 As shown in the figure, F1 represents the photocured film made from the prepolymer of Example 1, F2 represents the photocured film made from the prepolymer of Example 2, and F3 represents the photocured film made from the prepolymer of Example 3.

[0097] from Figure 3 It can be seen that the tensile strength of the photocured film made from the prepolymer of Example 3 is the largest, while the fracture growth rate of the photocured film is the opposite, that of Example 3 is the weakest.

[0098] From Example 1 to Example 3, the amount of silicon-containing monomer used is 1g, 2g, and 2g respectively. Figure 3 It can be seen that the tensile strength of the photocured film obtained from the prepolymers of Examples 2-3 is significantly higher than that of Example 1. It can be seen that with the increase of silicon content, the tensile strength of the cured film increases. This is because the silicon-containing monomer has hydrogen bond force and multifunctionality, which can increase the crosslinking density of the cured film. The fracture growth rates of the photocured films obtained from the prepolymers of Examples 1-3 are 5.41%, 4.78%, and 1.82%, respectively. The fracture growth rate is related to factors such as crosslinking density and intermolecular forces such as hydrogen bonds. Among them, the silicon-oxygen bonds of the silicon-containing monomer can participate in crosslinking and increase the crosslinking density of the cured film; in addition, phosphorus-containing monomers and silicon-containing monomers contain hydrogen bonds. When the viscosity of the prepolymer is low, the effect of hydrogen bonds is enhanced, which can reduce the fracture growth rate of the cured film. Among the prepolymers of Examples 1-3, the viscosity of the prepolymer of Example 3 is the lowest, so the hydrogen bond effect is more obvious. Under multiple effects, the fracture growth rate of the photocured film obtained from the prepolymer of Example 3 is relatively low.

[0099] (3) Thermogravimetric analysis test results

[0100] The thermal decomposition curves of the photocured films prepared from the prepolymers of Examples 1-3 are as follows: Figure 4 As shown in the figure, F1 represents the photocured film made from the prepolymer of Example 1, F2 represents the photocured film made from the prepolymer of Example 2, and F3 represents the photocured film made from the prepolymer of Example 3.

[0101] from Figure 4 It can be seen that the prepared photocurable film is mainly divided into two degradation stages. The degradation temperature of the first degradation stage is mainly between 50-300°C. This stage is mainly the decomposition of catalysts, residual raw materials, phosphorus-containing compounds, etc. in the cured film. The decomposition of the second degradation stage mainly occurs between 300-500°C. This stage is mainly the decomposition of vegetable oil molecular chains and cross-linked polymers, as well as the carbonization decomposition of silicon-containing compounds at high temperatures, releasing carbon dioxide and forming silicon oxides.

[0102] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. Bio-based flame retardant UV-curable prepolymer, characterized in that: The raw material composition includes: vegetable oil-based acrylate, phosphorus-containing monomer, silicon-containing monomer, and photoinitiator, wherein the mass ratio of vegetable oil-based acrylate, phosphorus-containing monomer, and silicon-containing monomer is (2-4): (1-2): (1-2), and the amount of photoinitiator is 1-5wt% of the total amount of reactants; The preparation method of the phosphorus-containing monomer comprises the following steps: The phosphonoacetic acid triethyl ester, the alcohol amine compound and the second catalyst are mixed, reacted at 100-130° C. for 1-3 hours, cooled to room temperature after the reaction is completed, the reaction product is washed, and then methacrylic anhydride and the second polymerization inhibitor are added, reacted at 25-45° C. for 13-18 hours, and heating is stopped after the reaction is completed to obtain a phosphorus-containing monomer; The method for preparing the silicon-containing monomer comprises the following steps: The acid anhydride and the silane are mixed, reacted at 60-80° C. for 2-4 hours, and then the second acrylic monomer, the third catalyst and the third polymerization inhibitor are added, and the reaction is carried out at 90-110° C. for 4-6 hours to obtain a silicon-containing monomer; the acid anhydride is itaconic anhydride and / or maleic anhydride; the silane is at least one of 3-aminopropylmethyldimethoxysilane, N-aminoethyl-3-aminopropyltriethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane; the second acrylic monomer is at least one of hydroxyethyl methacrylate, hydroxyethyl acrylate, 4-hydroxybutyl acrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, and hydroxybutyl acrylate.

2. The bio-based flame retardant UV-curable prepolymer according to claim 1, characterized in that: The preparation method of the vegetable oil-based acrylate comprises the following steps: The vegetable oil acid, the first acrylic acid monomer, the first catalyst, the first inhibitor and the solvent are mixed, and the mixture is reacted at 100-130° C. for 4-8 hours. After the reaction is completed, the reaction product is washed, dried, and then the solvent is removed by rotary evaporation to obtain the first acrylic acid monomer, which is at least one of hydroxyethyl methacrylate, hydroxyethyl acrylate, 4-hydroxybutyl acrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate and hydroxybutyl acrylate.

3. The bio-based flame retardant UV-curable prepolymer according to claim 2, characterized in that: The vegetable oleic acid is at least one of ricinoleic acid, eleostearic acid and oleic acid; The first catalyst is p-toluenesulfonic acid; The first polymerization inhibitor is at least one of hydroquinone, p-hydroxyanisole, and tert-butylcatechol; The solvent is at least one of toluene, cyclohexane, ethyl acetate and acetone.

4. The bio-based flame retardant UV-curable prepolymer according to claim 2 or 3, characterized in that: In parts by mass, the amount of vegetable oleic acid is 5-15 parts, and the amount of the first acrylic acid monomer is 2-8 parts; The amount of the first catalyst is 1 to 4 wt % of the total amount of reactants; The first polymerization inhibitor is used in an amount of 0.01 to 3 wt % of the total amount of reactants; The amount of the solvent used is 0.5 to 1.5 times the total amount of the reactants.

5. The bio-based flame retardant UV-curable prepolymer according to claim 1, characterized in that: The alcoholamine compound is at least one of ethanolamine, 3-amino-1,2-propylene glycol, isopropanolamine, 3-amino-1-propanol, and 6-amino-1-hexanol; The second catalyst is at least one of sodium methoxide, sodium hydroxide, potassium hydroxide, triethylamine, triphenylphosphine, 4-dimethylaminopyridine, pyridine, and p-toluenesulfonic acid; The second polymerization inhibitor is at least one of hydroquinone, tert-butylcatechol, and p-methoxyphenol.

6. The bio-based flame retardant UV-curable prepolymer according to claim 1, characterized in that: In parts by mass, the amount of triethyl phosphonoacetate is 5-15 parts, the amount of the alcoholamine compound is 2-10 parts, and the amount of methacrylic anhydride is 2.5-12 parts; The amount of the second catalyst added is 1 to 4 wt % of the total amount of reactants; The amount of the second polymerization inhibitor added is 0.01 to 4 wt % of the mass of methacrylic anhydride.

7. The bio-based flame retardant UV-curable prepolymer according to claim 1, characterized in that: The third catalyst is at least one of 4-dimethylaminopyridine, sodium methoxide, and p-toluenesulfonic acid; The third polymerization inhibitor is at least one of hydroquinone, tert-butylcatechol and p-methoxyphenol.

8. The bio-based flame retardant UV-curable prepolymer according to claim 1, characterized in that: In parts by mass, the amount of the acid anhydride is 5-15 parts, the amount of the silane is 9-33 parts, and the amount of the second acrylic monomer is 5-20 parts; The amount of the third catalyst is 1 to 4 wt% of the total amount of reactants; The third polymerization inhibitor is used in an amount of 0.01 to 5 wt % of the mass of the second acrylic acid monomer.

9. The bio-based flame retardant UV-curable prepolymer according to claim 1 or 2, characterized in that: The photoinitiator is at least one of 2-hydroxy-2-methylpropiophenone, diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide, 1-hydroxycyclohexylphenyl ketone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, α,α-dimethoxy-α-phenylacetophenone, and diphenyl-(4-phenylthio)phenylsulfonium hexafluorophosphate.

10. The method for preparing the bio-based flame retardant UV-curable prepolymer according to any one of claims 1 to 9, characterized in that: The steps include: The vegetable oil-based acrylate, phosphorus-containing monomer, silicon-containing monomer and photoinitiator are uniformly mixed.

11. Use of the bio-based flame retardant ultraviolet curing prepolymer according to any one of claims 1 to 9 in the preparation of UV curing coatings, UV curing inks, UV curing adhesives or 3D printing materials.

Images