Polymer-modified daidzein adhesive, and preparation method therefor and use thereof

Abstract

Disclosed in the present invention is a polymer-modified daidzein adhesive, which mainly comprises hydroxyl-carboxyl-terminated compound-modified daidzein and a curing agent which are independently packaged. The hydroxyl-carboxyl-terminated compound-modified daidzein is mainly prepared by subjecting carboxyl in the terminal position of a hydroxyl-carboxyl-terminated compound and the epoxy group in epoxy daidzein to ring-opening crosslinking. The curing agent can be a diisocyanate. When the curing agent is used, the curing agent is added to the hydroxyl-carboxyl-terminated compound-modified daidzein, and a certain amount of an organic solvent is added thereto until the solid content in the system is 40-50%; and same is uniformly mixed to obtain the adhesive. The polymer-modified daidzein adhesive provided in the present invention has the advantages of a high crosslinking density, good stability, good wettability on the surface of wood, a high curing speed, good hydrophobicity, etc., and can be used for the preparation of artificial boards.

Description

Polymer modified soybean flavonoid adhesive and its preparation method and application Technical Field

[0001] The present invention belongs to the technical field of fine chemical industry, relates to an adhesive and a preparation method and application thereof, and specifically relates to a polymer-modified soybean flavone adhesive and a preparation method and application thereof. Background Art

[0002] Traditional wood-based panels are primarily made from wood or other non-wood plant materials. After undergoing mechanical processing to separate the individual components, they are bonded together with adhesives and molded using a specific method. These panels or molded products are widely used in architectural decoration, furniture, flooring, and other fields. Currently, the adhesives used in the wood-based panel industry are mostly urea-formaldehyde resins, phenol-formaldehyde resins, and melamine-formaldehyde resins. These adhesives release formaldehyde during the production and pressing processes, as well as during the subsequent use of the panels, polluting the air and endangering human health.

[0003] At present, the main types of formaldehyde-free adhesives disclosed are as follows: (1) polyvinyl acetate adhesives, which are made by emulsion polymerization of acetic acid and ethylene in water. They have high bonding strength, but have poor water resistance and cold resistance, poor creep resistance of the film, easy sliding of the adhesive layer, and poor storage stability. (2) isocyanate adhesives, which have high bonding strength and good water resistance, but are expensive, highly active, have too fast reaction speed, and have high requirements for production process control. Materials will stick to pipes during transportation. (3) soy protein adhesives, although they have good environmental performance and renewable raw materials, have poor bonding strength and water resistance, high hot pressing temperature, long hot pressing time, and are prone to bubbling. (4) starch adhesives, which have the advantages of wide sources, low price, renewable and biodegradable, but starch adhesives have many shortcomings during use, such as poor water resistance, poor fluidity, easy mildew, and poor storage stability.

[0004] Summary of the Invention

[0005] The main purpose of the present invention is to provide a polymer-modified soybean flavonoid adhesive to solve at least one of the above technical problems.

[0006] According to one aspect of the present invention, a polymer-modified soybean flavonoid adhesive is provided, which is mainly composed of independently packaged terminal hydroxycarboxyl compound-modified soybean flavonoid and a curing agent. It is a two-component adhesive with terminal hydroxycarboxyl compound-modified soybean flavonoid as the main agent.

[0007] In some embodiments, the curing agent may be selected from at least one of isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexyl diisocyanate, and hexamethylene diisocyanate.

[0008] When in use, a curing agent is added to the terminal hydroxycarboxyl compound modified soybean flavonoids, and a certain amount of organic solvent is added to make the solid content of the system 40% to 50%, and mixed evenly to obtain a polymer modified soybean flavonoids adhesive working fluid.

[0009] In some embodiments, the organic solvent may be selected from at least one of ethyl acetate, acetone, butanone, dimethyl sulfoxide, and dichloromethane.

[0010] In some embodiments, the amount of the curing agent used can be 5% to 16% of the mass of the terminal hydroxycarboxyl compound modified soybean flavonoid.

[0011] The polymer-modified soybean flavonoid adhesive provided by the present invention has the advantages of high cross-linking density, good stability, good wettability on the wood surface, fast curing speed, good hydrophobicity, etc., and can be used in the preparation of artificial boards.

[0012] When used in the preparation of artificial boards, the polymer modified soybean flavonoid adhesive working liquid is evenly applied on the veneer, and the board is closed and placed for 10 to 13 minutes at room temperature before molding to obtain the artificial board. The amount of adhesive applied can be 200g / m 3 ~240g / m 3 , the hot pressing pressure can be 0.9-1.1MPa, and the hot pressing temperature can be 120℃-140℃.

[0013] According to another aspect of the present invention, a method for preparing the polymer-modified soybean flavonoid adhesive is provided, comprising the following steps:

[0014] Mixing a terminal hydroxycarboxyl compound, epoxy daidzein, a first phase transfer catalyst, and a first organic solvent, and reacting the mixture at a temperature of 75 to 85° C. for 1 to 3 hours to obtain a terminal hydroxycarboxyl compound-modified daidzein;

[0015] The terminal hydroxycarboxyl compound modified soybean flavonoid and the curing agent are packaged separately to obtain the product.

[0016] The present invention firstly performs ring-opening crosslinking between the carboxyl group at the end of the terminal hydroxycarboxyl compound and the epoxy group in the epoxy daidzein to obtain the terminal hydroxycarboxyl compound modified daidzein; then the terminal hydroxycarboxyl compound modified daidzein and the curing agent are independently packaged to obtain the polymer modified daidzein adhesive of the present invention.

[0017] In some embodiments, the hydroxy-carboxyl-terminated compound may be selected from at least one of hydroxy-carboxyl-terminated polybutadiene and hydroxy-carboxyl-terminated polybutadiene acrylonitrile.

[0018] In some embodiments, the molar ratio of epoxydized soybean flavonoids to the terminal hydroxycarboxyl compound is 1:(0.4-1.3).

[0019] In some embodiments, the first phase transfer catalyst can be selected from at least one of triethylamine, trioctylmethylammonium chloride, tetramethylammonium bromide, tetrapropylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium iodide, triethylbenzylammonium bromide, triethylhexylammonium bromide, and triethyloctylammonium bromide.

[0020] In some embodiments, the amount of the first phase transfer catalyst used may be 0.8% to 1.2% of the mass of the hydroxy-terminated carboxyl compound.

[0021] In some embodiments, the first organic solvent may be selected from at least one of ethyl acetate, acetone, butanone, dimethyl sulfoxide, and dichloromethane.

[0022] In some embodiments, the mass ratio of the first organic solvent to the total mass of the terminal hydroxycarboxyl compound and the epoxydized soy flavonoid is (0.7-1.2):1.

[0023] In some embodiments, the preparation method of epoxy daidzein may include the following steps:

[0024] Mixing soybean flavonoids, a first modifier, and a second phase transfer catalyst, and reacting them at a temperature of 100 to 110° C. for 1 to 3 hours to obtain a reaction mixture;

[0025] The reaction mixture, sodium hydroxide aqueous solution and the second organic solvent are mixed and reacted at room temperature for 4 to 6 hours. The obtained reaction product is separated, purified and dried to obtain epoxydized soy flavonoids.

[0026] In some embodiments, the first modifier may be selected from one of epichlorohydrin and epibromohydrin.

[0027] In some embodiments, the molar ratio of soybean flavonoids to the first modifier may be 1:(10-15).

[0028] In some embodiments, the second phase transfer catalyst can be selected from at least one of triethylamine, trioctylmethylammonium chloride, tetramethylammonium bromide, tetrapropylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium iodide, triethylbenzylammonium bromide, triethylhexylammonium bromide, and triethyloctylammonium bromide.

[0029] In some embodiments, the amount of the second phase transfer catalyst may be 5% to 8% of the mass of the daidzein.

[0030] In some embodiments, the mass ratio of daidzein to sodium hydroxide solution can be 1:(0.8-1.5). By using a certain concentration of sodium hydroxide solution as an alkaline treatment agent, the functional groups of the daidzein molecules can be exposed, which facilitates the smooth access of more epoxy groups during the reaction.

[0031] In some embodiments, the concentration of sodium hydroxide in the sodium hydroxide aqueous solution may be 45 wt % to 55 wt %.

[0032] In some embodiments, the second organic solvent is selected from at least one of ethyl acetate, acetone, butanone, dimethyl sulfoxide, and dichloromethane.

[0033] In some embodiments, the mass ratio of the second organic solvent to the total mass of daidzein and the first modifier is (1.0-1.5):1.

[0034] In some embodiments, the preparation method of the hydroxy-terminated carboxyl compound may include the following steps:

[0035] The terminal hydroxyl compound, maleic anhydride, a third phase transfer catalyst and a third organic solvent are mixed and reacted at a temperature of 100-110° C. for 1-3 hours to obtain the terminal hydroxyl carboxyl compound.

[0036] In some embodiments, the terminal hydroxyl compound may be selected from at least one of terminal hydroxyl polybutadiene and terminal hydroxyl polybutadiene acrylonitrile.

[0037] In some embodiments, the molar ratio of the terminal hydroxy compound to maleic anhydride may be 1:(0.75-2.5).

[0038] In some embodiments, the third phase transfer catalyst can be selected from at least one of triethylamine, trioctylmethylammonium chloride, tetramethylammonium bromide, tetrapropylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium iodide, triethylbenzylammonium bromide, triethylhexylammonium bromide, and triethyloctylammonium bromide.

[0039] In some embodiments, the amount of the third phase transfer catalyst used may be 1% to 3% of the mass of the terminal hydroxyl compound.

[0040] In some embodiments, the third organic solvent may be selected from at least one of ethyl acetate, acetone, butanone, dimethyl sulfoxide, and dichloromethane.

[0041] In some embodiments, the mass ratio of the third organic solvent to the total mass of the terminal hydroxy compound and the maleic anhydride is (1.0-1.5):1.

[0042] The beneficial effects of the present invention include:

[0043] (1) The polymer-modified soybean flavonoid adhesive provided by the present invention does not contain formaldehyde, has a high bio-based content, and is environmentally friendly and safe;

[0044] (2) The polymer-modified soybean flavonoid adhesive provided by the present invention has good water resistance, fast curing speed, high cross-linking density, good wettability and high bonding strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] FIG1 is a schematic diagram of the synthesis route of hydroxy-carboxyl-terminated polybutadiene-modified soybean flavonoids according to Example 1 of the present invention;

[0046] FIG2 is an infrared spectrum of hydroxy-terminated polybutadiene, hydroxy-carboxyl-terminated polybutadiene synthesized in Example 1 of the present invention, and hydroxy-carboxyl-terminated polybutadiene-modified soybean flavone;

[0047] FIG3 is a rheological diagram of hydroxy-carboxyl-terminated polybutadiene prepared in Examples 1 to 6 of the present invention;

[0048] FIG4 is an infrared spectra of hydroxy-terminated polybutadiene (comparative example) and hydroxy-carboxyl-terminated polybutadiene prepared in Examples 1 to 6 of the present invention;

[0049] FIG5 is a TG curve (under nitrogen atmosphere) of the cured film obtained after curing the polymer-modified soybean flavonoid adhesive prepared in Examples 1 to 6 of the present invention;

[0050] FIG6 is a DTG curve (under nitrogen atmosphere) of the cured film obtained after curing the polymer-modified soybean flavonoid adhesive prepared in Examples 1 to 6 of the present invention;

[0051] FIG7 is a schematic diagram of plywood sample preparation and force loading direction in the bonding strength test;

[0052] FIG8 is a test result of the bonding strength of the polymer-modified soybean flavonoid adhesives prepared in Examples 1 to 6 of the present invention;

[0053] FIG9 shows the water contact angle of the cured film obtained after curing of the polymer-modified soybean flavonoid adhesive prepared in Examples 1 to 6 of the present invention;

[0054] FIG10 is a fracture scanning electron micrograph of a cross section of a cured film obtained after curing the polymer-modified soybean flavonoid adhesive prepared in Examples 1 to 6 of the present invention. DETAILED DESCRIPTION

[0055] The present invention will be further described in detail below with reference to the following embodiments. The examples are provided for illustrative purposes only and are not intended to limit the present invention in any way. Unless otherwise specified, the raw materials and reagents used in the examples are commercially available conventional products. Experimental procedures in the examples where specific conditions are not specified are generally performed in accordance with conventional conditions in the art or the conditions recommended by the manufacturer.

[0056] In the embodiment, the number average molecular weight of the hydroxyl-terminated polybutadiene and the hydroxyl-terminated polybutadiene acrylonitrile is 2000-3000.

[0057] Example 1 Preparation of polymer-modified soybean flavonoid adhesive

[0058] (1) 20 g (0.08 mol) of daidzein, 1.2 g of tetrabutylammonium bromide, and 74 g (0.8 mol) of epichlorohydrin were added to a three-necked flask and reacted at 105° C. for 1 hour. 20 g of NaOH solution (50 wt% aqueous solution) and 100 g of dichloromethane were added as solvent and reacted at room temperature for 5 hours. The mixture was extracted with deionized water, filtered, washed, and dried in an oven to obtain epoxydized daidzein.

[0059] (2) Add 25 g (about 0.01 mol) of hydroxyl-terminated polybutadiene, 0.98 g (0.01 mol) of maleic anhydride, 30 g of ethyl acetate, and 0.25 g of triethylamine to a three-necked flask and react at 100° C. for 2 hours to obtain hydroxyl-terminated carboxyl polybutadiene;

[0060] (3) 3.6 g (0.01 mol) of epoxydized soybean flavonoids, 0.25 g of triethylamine, and 30 g of ethyl acetate were added to 26 g (about 0.01 mol) of hydroxy-terminated carboxyl polybutadiene and reacted at 80° C. for 2 hours to obtain hydroxy-terminated carboxyl polybutadiene-modified soybean flavonoids;

[0061] (4) The terminal hydroxycarboxyl polybutadiene modified soybean flavonoid and the curing agent isophorone diisocyanate are packaged separately to obtain a polymer modified soybean flavonoid adhesive.

[0062] When in use, 3g of isophorone diisocyanate can be added dropwise to 25g of terminal hydroxycarboxyl polybutadiene modified soybean flavonoids, and 30g of ethyl acetate can be added to make the solid content of the system 40% to 50%, thereby obtaining the polymer modified soybean flavonoids adhesive working solution.

[0063] The schematic diagram of the synthesis route of the hydroxy-terminated carboxyl-modified soybean flavonoids in this embodiment is shown in FIG1 .

[0064] Thermo-Nicolet Nexus 670 FT-IR spectrometer was used to record the FT-IR of the hydroxy-terminated polybutadiene, the hydroxy-carboxyl-terminated polybutadiene synthesized in step (2), and the hydroxy-carboxyl-terminated polybutadiene modified soybean flavonoids synthesized in step (3) at 4000-500 cm -1 Fourier transform infrared spectroscopy (FT-IR) analysis was performed within the range of 10 nm, with 32 scans. The results are shown in Figure 2.

[0065] Example 2 Preparation of polymer-modified soybean flavonoid adhesive

[0066] (1) 20 g (0.08 mol) of daidzein, 1.2 g of tetrabutylammonium bromide, and 74 g (0.8 mol) of epichlorohydrin were added to a three-necked flask and reacted at 105° C. for 1 hour. 20 g of NaOH solution (50 wt% aqueous solution) and 100 g of dichloromethane were added as solvent and reacted at room temperature for 5 hours. The mixture was extracted with deionized water, filtered, washed, and dried in an oven to obtain epoxydized daidzein.

[0067] (2) Add 25 g (about 0.01 mol) of hydroxyl-terminated polybutadiene, 1.47 g (0.015 mol) of maleic anhydride, 30 g of ethyl acetate, and 0.5 g of triethylamine to a three-necked flask and react at 105° C. for 2.5 hours to obtain hydroxyl-terminated carboxyl polybutadiene;

[0068] (3) 3.6 g (0.01 mol) of epoxydized soybean flavonoids, 0.25 g of triethylamine, and 30 g of ethyl acetate were added to 26 g (about 0.01 mol) of hydroxy-terminated carboxyl polybutadiene and reacted at 80° C. for 2 hours to obtain hydroxy-terminated carboxyl polybutadiene-modified soybean flavonoids;

[0069] (4) The terminal hydroxycarboxyl polybutadiene modified soybean flavonoid and the curing agent isophorone diisocyanate are packaged separately to obtain a polymer modified soybean flavonoid adhesive.

[0070] When in use, 3.5 g of isophorone diisocyanate can be added dropwise to 25 g of terminal hydroxycarboxyl polybutadiene modified soybean flavonoids, and 30 g of ethyl acetate can be added to make the solid content of the system 40% to 50%, thereby obtaining a polymer-modified soybean flavonoids adhesive working solution.

[0071] Example 3 Preparation of polymer-modified soybean flavonoid adhesive

[0072] (1) 20 g (0.08 mol) of daidzein, 1.2 g of tetrabutylammonium bromide, and 74 g (0.8 mol) of epichlorohydrin were added to a three-necked flask and reacted at 105° C. for 1 hour. 20 g of NaOH solution (50 wt% aqueous solution) and 100 g of dichloromethane were added as solvent and reacted at room temperature for 5 hours. The mixture was extracted with deionized water, filtered, washed, and dried in an oven to obtain epoxydized daidzein.

[0073] (2) Add 25 g (about 0.01 mol) of hydroxyl-terminated polybutadiene, 1.96 g (0.02 mol) of maleic anhydride, 30 g of ethyl acetate, and 0.75 g of triethylamine to a three-necked flask and react at 110° C. for 3 hours to obtain hydroxyl-terminated carboxyl polybutadiene;

[0074] (3) 3.6 g (0.01 mol) of epoxydized soybean flavonoids, 0.25 g of triethylamine, and 30 g of ethyl acetate were added to 26 g (about 0.01 mol) of hydroxy-terminated carboxyl polybutadiene and reacted at 80° C. for 2 hours to obtain hydroxy-terminated carboxyl polybutadiene-modified soybean flavonoids;

[0075] (4) The terminal hydroxycarboxyl polybutadiene modified soybean flavonoid and the curing agent isophorone diisocyanate are packaged separately to obtain a polymer modified soybean flavonoid adhesive.

[0076] When in use, 4 g of isophorone diisocyanate can be added dropwise to 25 g of terminal hydroxycarboxyl polybutadiene modified soybean flavonoids, and 30 g of ethyl acetate is added to make the solid content of the system 40% to 50%, thereby obtaining a polymer-modified soybean flavonoids adhesive working solution.

[0077] Example 4 Preparation of polymer-modified soybean flavonoid adhesive

[0078] (1) 20 g (0.08 mol) of daidzein, 1.2 g of tetrabutylammonium bromide, and 74 g (0.8 mol) of epichlorohydrin were added to a three-necked flask and reacted at 105° C. for 1 hour. 20 g of NaOH solution (50 wt% aqueous solution) and 100 g of dichloromethane were added as solvent and reacted at room temperature for 5 hours. The mixture was extracted with deionized water, filtered, washed, and dried in an oven to obtain epoxydized daidzein.

[0079] (2) Add 25 g (about 0.01 mol) of hydroxyl-terminated polybutadiene, 0.98 g (0.01 mol) of maleic anhydride, 30 g of ethyl acetate, and 0.25 g of triethylamine to a three-necked flask and react at 100° C. for 2 hours to obtain hydroxyl-terminated carboxyl polybutadiene;

[0080] (3) Add 7.2 g (0.02 mol) of epoxydized soybean flavonoids, 0.25 g of triethylamine, and 30 g of ethyl acetate to 26 g (about 0.01 mol) of hydroxy-terminated carboxyl polybutadiene and fully react at 80° C. for 2 hours to obtain hydroxy-terminated carboxyl polybutadiene-modified soybean flavonoids;

[0081] (4) The terminal hydroxycarboxyl polybutadiene modified soybean flavonoids and the curing agent toluene diisocyanate are packaged separately to obtain a polymer modified soybean flavonoids adhesive.

[0082] When in use, 3g of toluene diisocyanate can be added dropwise to 25g of terminal hydroxycarboxyl polybutadiene modified soybean flavonoids, and 30g of ethyl acetate is added to make the solid content of the system 40% to 50%, thereby obtaining the polymer modified soybean flavonoids adhesive working solution.

[0083] Example 5 Preparation of polymer-modified soybean flavonoid adhesive

[0084] (1) 20 g (0.08 mol) of daidzein, 1.2 g of tetrabutylammonium bromide, and 74 g (0.8 mol) of epichlorohydrin were added to a three-necked flask and reacted at 105° C. for 1 hour. 20 g of NaOH solution (50 wt% aqueous solution) and 100 g of dichloromethane were added as solvent and reacted at room temperature for 5 hours. The mixture was extracted with deionized water, filtered, washed, and dried in an oven to obtain epoxydized daidzein.

[0085] (2) Add 25 g (about 0.01 mol) of hydroxyl-terminated polybutadiene, 1.47 g (0.015 mol) of maleic anhydride, 30 g of ethyl acetate, and 0.25 g of triethylamine to a three-necked flask and react at 100° C. for 2 hours to obtain hydroxyl-terminated carboxyl polybutadiene;

[0086] (3) 7.2 g (0.02 mol) of epoxydized soybean flavonoids, 0.25 g of triethylamine, and 30 g of ethyl acetate were added to 26 g (about 0.01 mol) of hydroxy-terminated carboxyl polybutadiene and reacted at 80° C. for 2.5 hours to obtain hydroxy-terminated carboxyl polybutadiene-modified soybean flavonoids;

[0087] (4) The terminal hydroxycarboxyl polybutadiene modified soybean flavonoids and the curing agent toluene diisocyanate are packaged separately to obtain a polymer modified soybean flavonoids adhesive.

[0088] When in use, 3.5 g of toluene diisocyanate can be added dropwise to 25 g of terminal hydroxycarboxyl polybutadiene modified soybean flavonoids, and 30 g of ethyl acetate can be added to make the solid content of the system 40% to 50%, thereby obtaining the polymer modified soybean flavonoids adhesive working solution.

[0089] Example 6 Preparation of polymer-modified soybean flavonoid adhesive

[0090] (1) 20 g (0.08 mol) of daidzein, 1.2 g of tetrabutylammonium bromide, and 74 g (0.8 mol) of epichlorohydrin were added to a three-necked flask and reacted at 105° C. for 1 hour. 20 g of NaOH solution (50 wt% aqueous solution) and 100 g of dichloromethane were added as solvent and reacted at room temperature for 5 hours. The mixture was extracted with deionized water, filtered, washed, and dried in an oven to obtain epoxydized daidzein.

[0091] (2) Add 25 g (about 0.01 mol) of hydroxyl-terminated polybutadiene, 1.47 g (0.02 mol) of maleic anhydride, 30 g of ethyl acetate, and 0.25 g of triethylamine to a three-necked flask and react at 100° C. for 2 hours to obtain hydroxyl-terminated carboxyl polybutadiene;

[0092] (3) 7.2 g (0.02 mol) of epoxydized soybean flavonoids, 0.25 g of triethylamine, and 30 g of ethyl acetate were added to 26 g (about 0.01 mol) of hydroxy-terminated carboxyl polybutadiene and reacted at 80° C. for 3 hours to obtain hydroxy-terminated carboxyl polybutadiene-modified soybean flavonoids;

[0093] (4) The terminal hydroxycarboxyl polybutadiene modified soybean flavonoids and the curing agent toluene diisocyanate are packaged separately to obtain a polymer modified soybean flavonoids adhesive.

[0094] When in use, 4g of toluene diisocyanate can be added dropwise to 25g of terminal hydroxycarboxyl polybutadiene modified soybean flavonoids, and 30g of ethyl acetate is added to make the solid content of the system 40% to 50%, thereby obtaining the polymer modified soybean flavonoids adhesive working solution.

[0095] Example 7 Preparation of polymer-modified soybean flavonoid adhesive

[0096] (1) 20 g (0.08 mol) of daidzein, 1.2 g of tetrabutylammonium bromide, and 74 g (0.8 mol) of epichlorohydrin were added to a three-necked flask and reacted at 105° C. for 1 hour. 20 g of NaOH solution (50 wt% aqueous solution) and 100 g of dichloromethane were added as solvent and reacted at room temperature for 5 hours. The mixture was extracted with deionized water, filtered, washed, and dried in an oven to obtain epoxydized daidzein.

[0097] (2) Add 25 g (about 0.01 mol) of hydroxy-terminated polybutadiene acrylonitrile, 1.96 g (0.02 mol) of maleic anhydride, 30 g of ethyl acetate, and 0.75 g of triethylamine into a three-necked flask and react at 110° C. for 3 hours to obtain hydroxy-terminated carboxyl polybutadiene acrylonitrile;

[0098] (3) 7.2 g (0.02 mol) of epoxydized soybean flavonoids, 0.25 g of triethylamine, and 30 g of ethyl acetate were added to 26 g (about 0.01 mol) of hydroxy-terminated carboxyl polybutadiene acrylonitrile and reacted at 80° C. for 2 hours to obtain hydroxy-terminated carboxyl polybutadiene acrylonitrile-modified soybean flavonoids;

[0099] (4) The terminal hydroxycarboxyl polybutadiene acrylonitrile modified soybean flavonoid and the curing agent isophorone diisocyanate are packaged separately to obtain a polymer modified soybean flavonoid adhesive.

[0100] When in use, 4g of isophorone diisocyanate can be added dropwise to 25g of terminal hydroxycarboxyl polybutadiene acrylonitrile modified soybean flavonoids, and 30g of ethyl acetate is added to make the solid content of the system 40% to 50%, thereby obtaining a polymer modified soybean flavonoids adhesive working solution.

[0101] Test Example 1 Rheological Test

[0102] The hydroxy-terminated carboxyl polybutadiene prepared in Examples 1-6 was tested using an MCR 502 modular intelligent advanced rheometer. A CP25-2 rotor was used, and a measurement-viscosity curve was configured. The number of data points was set to 25, with a 10-second interval between each data point. At least three parallel runs were performed for each example to ensure accuracy.

[0103] The results are shown in Figure 3.

[0104] As shown in Figure 3, the hydroxycarboxyl-terminated polybutadiene prepared in Example 1 has the lowest viscosity, ranging from 34,490 to 35,980 MPa·s, while the hydroxycarboxyl-terminated polybutadiene prepared in Example 6 has the highest viscosity, ranging from 51,200 to 51,260 MPa·s. Hydroxyl-terminated compounds have poor fluidity, so an organic solvent must be added when reacting them with epoxydized soy flavonoids to prepare hydroxycarboxyl-terminated polybutadiene-modified soy flavonoids.

[0105] Test Example 2 Fourier Transform Infrared Spectroscopy Test

[0106] Thermo-Nicolet Nexus 670 FT-IR spectrometer was used to record the FT-IR of the hydroxy-terminated polybutadiene (control example) and the hydroxy-carboxyl-terminated polybutadiene prepared in Examples 1 to 6 at 4000 to 500 cm -1 Fourier transform infrared spectroscopy (FT-IR) analysis was performed within the range of 10 nm, with 32 scans. The results are shown in Figure 4.

[0107] The results in Figure 4 show that compared with the control example hydroxy-terminated polybutadiene, the hydroxy-terminated polybutadiene prepared by the reaction of maleic anhydride with hydroxy-terminated polybutadiene has a -1 There is obvious stretching vibration of ester carbonyl group. It is speculated that the hydroxyl group and the acid anhydride undergo cross-linking and ring opening to form carboxyl group and ester group.

[0108] Test Example 3 Thermogravimetric test

[0109] The polymer-modified soy flavonoid adhesive prepared in Examples 1 to 6 was prepared into a polymer-modified soy flavonoid adhesive working solution, which was then poured into a polytetrafluoroethylene mold and heated in a 120°C oven under vacuum for 5 hours to form a cured film. The cured film was subjected to thermogravimetric analysis (TGA) using a thermal analyzer (Netzsch STA449C) under a nitrogen atmosphere. The nitrogen flow rate was set to 20 g / min, the test temperature range was 30-800°C, and the heating rate was 10°C / min. The results are shown in Figures 5 and 6.

[0110] As can be seen from Figures 5 and 6, the TG decomposition temperature curves of the polymer-modified soybean flavonoid adhesive cured films obtained in Examples 1-6 are between 30 and 800°C. The carbon residue rate of the cured films of Examples 1 to 3 increased from 1.06% to 6.38%, and the carbon residue rate of the cured films of Examples 4 to 6 increased from 2.13% to 6.69%. Similarly, the DTG maximum degradation temperature of the cured film is around 464°C, which is consistent with the TG degradation trend. The modified soybean flavonoid adhesive provided by the present invention has a better thermal stability structure due to the increased cross-linking density, the generation of hydrogen bonds or other effects.

[0111] Test Example 4: Bonding Strength Test

[0112] The test is carried out according to the method "4.17 Determination of Gluing Strength" in "GB / T17657-2013 Test Methods for Physical and Chemical Properties of Artificial Boards and Veneer Artificial Boards", including the following steps:

[0113] Take a 30cm*30cm poplar veneer, place the poplar veneer on both sides of the glued veneer with the wood grain perpendicular to each other, and apply the same amount of the working solution of the polymer modified soybean flavonoid adhesive prepared in Examples 1 to 6 on both sides of the poplar veneer (the amount of glue applied is 220g / m 2 ), under the conditions of 130℃ and 1.0MPa, it was pressed into three-layer plywood, and after pressing, it was placed at room temperature for 1 day to obtain plywood. The plywood was sawed into wooden blocks with a length and width of 100mm*25mm, and the gluing area at the gluing center was 25mm*25mm long and wide. The schematic diagram of plywood sample preparation and force loading direction is shown in Figure 7. The dry bonding strength is directly tested without boiling in water; the wet bonding strength test is based on GB / T17657-2013, and the specimen is placed at 30℃ for one hour after being boiled in boiling water for (72±1h) to obtain the bonding strength. At least three sets of parallel experiments are performed for each embodiment to ensure the accuracy of the test. The results are shown in Figure 8.

[0114] The results in Figure 8 show that the maximum dry bonding strength of the polymer-modified soy flavonoid adhesives prepared in Examples 1 to 6 is 2.03 MPa, and the maximum wet bonding strength is 1.05 MPa. The wet bonding strength of the polymer-modified soy flavonoid adhesives prepared in Examples 1 to 6 all meet the GB / T17657-2013 Grade I standard.

[0115] Test Example 5 Water Contact Angle Test

[0116] The polymer-modified daidzein adhesives prepared in Examples 1-6 were prepared into a polymer-modified daidzein adhesive working solution, which was then poured into a polytetrafluoroethylene mold. Cured films were then heated in a 120°C oven under vacuum for 5 hours. The water contact angles of the cured films were measured using a Powereach JC2000C1 instrument. At least three parallel experiments were performed for each example to ensure accuracy. The results are shown in Figure 9.

[0117] After 10 seconds of testing, it can be seen from the results in Figure 9 that the water contact angles of the cured films obtained after curing of the polymer-modified soy flavonoid adhesives prepared in Examples 1 to 6 gradually increase with the increasing amount of epoxy soy flavonoids used in the preparation process, reaching a maximum of 103.46°. In addition, the water contact angles of the cured films obtained after curing of the polymer-modified soy flavonoid adhesives in Examples 1 to 6 are all greater than 90°, indicating good hydrophobicity.

[0118] Test Example 6 Scanning Electron Microscope Test

[0119] The polymer-modified daidzein adhesives prepared in Examples 1-6 were prepared into a polymer-modified daidzein adhesive working solution, which was then poured into a polytetrafluoroethylene mold and heated in a vacuum oven at 120°C for 5 hours to form a cured film. The cured film was subjected to low-temperature fracture treatment using liquid nitrogen before testing. The fractured cross-section was gold-sprayed before testing, and the morphology of the fracture interface of the cured adhesive was observed using an EVOma15 (ZEISS, Germany) at a voltage of 10.0 kV. The results are shown in Figure 10.

[0120] As shown in the results of Figure 10, the polymer-modified soy flavonoid adhesives prepared in Examples 1 to 6 all contain soy flavonoid particles as fillers. As the amount of soy flavonoid added increases, the surface becomes slightly rough, but the overall polymer-modified soy flavonoid adhesive has a neat fracture cross-section without holes or gaps, showing good cross-linking properties.

[0121] 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. Polymer-modified daidzein adhesive, characterized in that, The polymer-modified daidzein adhesive mainly consists of daidzein modified by a terminal hydroxycarboxyl compound and a curing agent, which are independently packaged. Among them, the preparation method of the daidzein modified by the terminal hydroxycarboxyl compound includes the following steps: Mix the terminal hydroxycarboxyl compound, epoxy daidzein, the first phase transfer catalyst and the first organic solvent, and react at a temperature of 75-85 °C for 1-3 hours to obtain daidzein modified by the terminal hydroxycarboxyl compound; The terminal hydroxycarboxyl compound is selected from at least one of terminal hydroxycarboxyl polybutadiene and terminal hydroxycarboxyl polybutadiene acrylonitrile.

2. The polymer-modified daidzein adhesive according to claim 1, wherein, The molar ratio of the epoxy daidzein to the terminal hydroxycarboxyl compound is 1:(0.4-1.3).

3. The polymer-modified daidzein adhesive according to claim 2, wherein The first phase transfer catalyst is selected from at least one of triethylamine, trimethyloctylammonium chloride, tetramethylammonium bromide, tetrapropylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium iodide, triethylbenzylammonium bromide, triethylhexylammonium bromide, and triethyloctylammonium bromide; the dosage of the first phase transfer catalyst is 0.8%-1.2% of the mass of the terminal hydroxycarboxyl compound.

4. The polymer-modified daidzein adhesive according to any one of claims 1 to 3, characterized in that, The first organic solvent is selected from at least one of ethyl acetate, acetone, methyl ethyl ketone, dimethyl sulfoxide, and dichloromethane.

5. The polymer-modified daidzein adhesive according to claim 4, wherein The curing agent is selected from at least one of isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexyl diisocyanate, and hexamethylene diisocyanate; when in use, the dosage of the curing agent is 5%-16% of the mass of the daidzein modified by the terminal hydroxycarboxyl compound.

6. The polymer-modified daidzein adhesive according to claim 1, wherein The preparation method of the epoxy daidzein includes the following steps: Mix daidzein, the first modifier, and the second phase transfer catalyst, and react at a temperature of 100-110 °C for 1-3 hours to obtain a reaction mixture; Mix the reaction mixture, an aqueous sodium hydroxide solution, and the second organic solvent, and react at room temperature for 4-6 hours. The obtained reaction product is separated, purified, and dried to obtain epoxy daidzein; The first modifier is selected from one of epichlorohydrin and epibromohydrin; The molar ratio of the daidzein to the first modifier is 1:(10-15); the dosage of the second phase transfer catalyst is 5%-8% of the mass of the daidzein; the mass ratio of the daidzein to the aqueous sodium hydroxide solution is 1:(0.8-1.5).

7. The polymer-modified daidzein adhesive according to claim 6, wherein The second phase transfer catalyst is selected from at least one of triethylamine, trimethyloctylammonium chloride, tetramethylammonium bromide, tetrapropylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium iodide, triethylbenzylammonium bromide, triethylhexylammonium bromide, and triethyloctylammonium bromide; the second organic solvent is selected from at least one of ethyl acetate, acetone, methyl ethyl ketone, dimethyl sulfoxide, and dichloromethane; the concentration of sodium hydroxide in the aqueous sodium hydroxide solution is 45wt%-55wt%.

8. The polymer-modified daidzein adhesive according to claim 1, wherein The preparation method of the terminal hydroxycarboxyl compound includes the following steps: Mix the terminal hydroxy compound, maleic anhydride, the third phase transfer catalyst, and the third organic solvent, and react at a temperature of 100-110 °C for 1-3 hours to obtain the terminal hydroxycarboxyl compound; The terminal hydroxy compound is selected from at least one of terminal hydroxy polybutadiene and terminal hydroxy polybutadiene acrylonitrile; The third phase transfer catalyst is selected from at least one of triethylamine, trimethyloctylammonium chloride, tetramethylammonium bromide, tetrapropylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium iodide, triethylbenzylammonium bromide, triethylhexylammonium bromide, and triethyloctylammonium bromide; The third organic solvent is selected from at least one of ethyl acetate, acetone, methyl ethyl ketone, dimethyl sulfoxide, and dichloromethane; The molar ratio of the hydroxyl-terminated compound to maleic anhydride is 1:(0.75 - 2.5); the dosage of the third phase transfer catalyst is 1% - 3% of the mass of the hydroxyl-terminated compound.

9. The preparation method of the polymer-modified daidzein adhesive according to any one of claims 1 to 8, characterized in that, It includes the following steps: Mix the hydroxyl-terminated compound, maleic anhydride, the third phase transfer catalyst, and the third organic solvent, and react at a temperature of 100 - 110 °C for 1 - 3 hours to obtain a hydroxyl-carboxyl-terminated compound; Mix the hydroxyl-carboxyl-terminated compound, epoxy soyflavone, the first phase transfer catalyst, and the first organic solvent, and react at a temperature of 75 - 85 °C for 1 - 3 hours to obtain a modified soyflavone with hydroxyl-carboxyl termini; Independently package the modified soyflavone with hydroxyl-carboxyl termini and the curing agent respectively to obtain the product; The hydroxyl-terminated compound is selected from at least one of hydroxyl-terminated polybutadiene and hydroxyl-terminated polybutadiene acrylonitrile; The curing agent is selected from at least one of isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexyl diisocyanate, and hexamethylene diisocyanate.

10. Use of the polymer-modified soyflavone adhesive according to any one of claims 1 - 8 in the preparation of wood-based panels.

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