A waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnating agent, its preparation method and application

Abstract

This invention relates to a waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnating agent, its preparation method, and its application. The impregnating agent comprises the following raw materials in parts by weight: 120-140 parts formaldehyde, 35-40 parts urea, 40-45 parts melamine, 20-25 parts modified protein hydrophobic agent, 10-15 parts filler, and 4-5 parts curing agent. This invention uses natural renewable protein meal as raw material to prepare the modified protein hydrophobic agent, replacing traditional petroleum-based hydrophobic agents and reducing environmental harm. Through protein activation in step S1, the introduction of hydrophobic triazole groups in step S2, and organosilicon grafting in step S3, the natural renewable protein meal achieves molecular-level hydrophobic modification and structural strengthening, ultimately endowing the impregnating agent with excellent waterproof performance. Simultaneously, the active amino groups contained in the modified protein hydrophobic agent can capture free formaldehyde and stabilize the resin structure to reduce formaldehyde emissions, ultimately making the impregnating agent both waterproof and environmentally friendly.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of melamine-urea-formaldehyde resin impregnant, in particular to a waterproof environment-friendly melamine-urea-formaldehyde resin impregnant and a preparation method and application thereof. BACKGROUND

[0002] Melamine-urea-formaldehyde resin (MUF) is a kind of amino resin, which is synthesized by the polycondensation reaction of melamine, urea and formaldehyde. Due to its excellent heat resistance and chemical resistance, MUF resin has been widely used in many fields, such as plastic veneer, laminated materials, tableware, decorations and adhesives, etc.

[0003] However, melamine-urea-formaldehyde resin also has some shortcomings. Firstly, its water resistance and weather resistance are relatively weak, and its performance may be affected and decreased in the environment with high humidity, ultraviolet radiation or large temperature fluctuation. Secondly, the texture of the resin after curing may be brittle, which limits its application in occasions requiring flexibility to some extent. In addition, during the production and application of melamine-urea-formaldehyde resin, formaldehyde, a harmful substance, may be released, which may pose potential risks to human health and the environment. Therefore, appropriate measures are generally taken to reduce the release of formaldehyde when using this resin. SUMMARY

[0004] The present application aims to overcome the shortcomings of the prior art and provide a waterproof environment-friendly melamine-urea-formaldehyde resin impregnant and a preparation method and application thereof.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows:

[0006] In a first aspect, the present application provides a waterproof environment-friendly melamine-urea-formaldehyde resin impregnant, which comprises the following raw materials by weight: formaldehyde 120-140 parts, urea 35-40 parts, melamine 40-45 parts, modified protein hydrophobic agent 20-25 parts, filler 10-15 parts and curing agent 4-5 parts.

[0007] The preparation method of the modified protein hydrophobic agent comprises the following steps:

[0008] S1, first dissolve the alkali and urea in water to obtain a mixed solution, then add protein meal and stir to dissolve to obtain a degradation solution; wherein the mass ratio of the protein meal, alkali and urea is (4-5) : 1 : (1.5-2), and the amount of water added is 2-3 times the total mass of the protein meal, alkali and urea;

[0009] S2, a 3, 5-diamino-1, 2, 4-triazole, dicyclohexyl carbodiimide solution is added in the degradation solution, and stirring reaction is carried out at 70-80 DEG C to obtain a first solution; wherein the solvent of the dicyclohexyl carbodiimide solution is N, N-dimethylformamide, the mass concentration of the dicyclohexyl carbodiimide solution is 60-70%, and the mass ratio of the degradation solution, 3, 5-diamino-1, 2, 4-triazole and dicyclohexyl carbodiimide solution is (3-6) : 1 : (0.8-1) ;

[0010] S3, a gamma-(2, 3-epoxypropoxy) propyl trimethoxysilane solution is added in the first solution, and stirring reaction is carried out at 90-100 DEG C to obtain the modified protein hydrophobic agent; wherein the solvent of the gamma-(2, 3-epoxypropoxy) propyl trimethoxysilane solution is anhydrous ethanol, the mass concentration of the gamma-(2, 3-epoxypropoxy) propyl trimethoxysilane solution is 60-70%, and the mass ratio of the first solution and the gamma-(2, 3-epoxypropoxy) propyl trimethoxysilane solution is (5-7) : 1.

[0011] In the preparation method of the modified protein hydrophobic agent, each step is carried out as follows:

[0012] In the basic environment, urea is mainly used as a protein denaturant to destroy hydrogen bonds and hydrophobic interaction, promote peptide bond hydrolysis, generate polypeptide fragments and free amino acids, and expose more carboxyl (-COOH) and amino (-NH2) active sites.

[0013] In step S2, dicyclohexyl carbodiimide (DCC) activates protein carboxyl to generate a highly active O-acyl isourea intermediate, and the amino group of 3, 5-diamino-1, 2, 4-triazole (DAT) is subjected to amidation reaction (-CO-NH-), so that the nitrogen-containing heterocycle is grafted to the protein chain to form a dense hydrophobic layer to block water molecules from penetrating. Moreover, the double amino groups of DAT are connected to two protein chains to form a three-dimensional network to reduce the diffusion channel of water molecules.

[0014] In step S3, the epoxy group in the gamma-(2, 3-epoxypropoxy) propyl trimethoxysilane (KH560) molecule is subjected to ring-opening addition reaction with the residual amino group (-NH2) in the first solution (the epoxy group is easy to react with the amino group at high temperature) to form a stable C-N covalent bond, so that the silane molecule is grafted to the peptide segment derivative. The other end of KH560 is a trimethoxysilane group (-Si(OCH3)3) which has hydrophilicity and can form a chemical bond with the hydroxyl group of the substrate (such as wood / fiber) to improve the adhesion and durability of the impregnant on the substrate.

[0015] Meanwhile, because the modified protein hydrophobic agent has good hydrophobicity, it not only blocks water but also reduces the contact between formaldehyde and water to prevent the release of formaldehyde by hydrolysis.

[0016] The active groups (such as amino, hydroxyl) in the modified protein hydrophobic agent of the present application react with formaldehyde in the resin to form a stable network structure, fixing free formaldehyde in the resin, thereby significantly reducing the content of unreacted formaldehyde in the resin and meeting environmental protection requirements.

[0017] Preferably, in the preparation step S1 of the modified protein hydrophobic agent, the stirring speed of the dissolved solution is 900-1000 r / min, and the time is 40-60 min.

[0018] Preferably, in the preparation step S2 of the modified protein hydrophobic agent, the mass ratio of the degradation solution, 3,5-diamino-1,2,4-triazole and dicyclohexyl carbodiimide solution is (4-5):1:(0.8-1).

[0019] Preferably, the protein meal is soybean meal and / or distiller's grains, and the base is sodium hydroxide.

[0020] Preferably, in the preparation step S2 of the modified protein hydrophobic agent, the stirring speed of the reaction is 400-600 r / min, and the time is 20-40 min.

[0021] Preferably, in the preparation step S3 of the modified protein hydrophobic agent, the stirring speed of the reaction is 400-600 r / min, and the time is 20-40 min.

[0022] Preferably, the filler is at least one of peanut shell powder, cooked glutinous rice powder and heavy calcium carbonate.

[0023] Preferably, the curing agent is ammonium chloride.

[0024] In a second aspect, the present application provides a preparation method of a waterproof and environmentally friendly melamine-urea formaldehyde resin impregnant, characterized in that it comprises the following steps:

[0025] (1) At room temperature, a formula amount of formaldehyde is added to a reaction container, the pH is adjusted to 8.5-9.0, and the temperature is raised to 50-55℃, and the first part of urea and the modified protein hydrophobic agent are added, and the reaction is kept for 30-40 min;

[0026] (2) The first part of melamine is added to the reaction container, the temperature is raised to 90-92℃, the pH is adjusted to 5.2-5.3, and the reaction is carried out until the viscosity is 90-100 mPa·s, to obtain a reaction mixture A;

[0027] (3) The pH of the reaction mixture A is adjusted to 8.0-8.5, and the temperature is adjusted to 86-88℃, and the second part of melamine is added, and the reaction is kept for 1.5-2 h;

[0028] (4) After the reaction is kept warm, the pH of the system is adjusted to 9.0-9.5, the temperature is adjusted to 42-47℃, the second part of urea is added, and the reaction is kept warm for 30-40 min to obtain the modified melamine resin;

[0029] (5) The curing agent of the formula amount is added to water to prepare a curing agent solution with a mass concentration of 20-30wt%, and then the modified melamine resin and the filler are added and stirred uniformly to obtain the waterproof and environmentally friendly melamine-urea formaldehyde resin impregnant.

[0030] Preferably, the mass ratio of the first part of urea to the second part of urea is 40:(5-10).

[0031] Preferably, the mass ratio of the first part of melamine to the second part of melamine is (5-7):35.

[0032] In a third aspect, the application provides an application of the waterproof and environmentally friendly melamine-urea formaldehyde resin impregnant in the first aspect in the preparation of plywood.

[0033] Compared with the prior art, the application has the following beneficial effects:

[0034] The modified protein hydrophobic agent is prepared by selecting natural renewable protein meal as a raw material, and is added into the melamine-urea formaldehyde resin impregnant to replace the traditional petroleum-based hydrophobic agent (such as organic silicon and fluoride), so that the environmental hazards can be reduced; the renewable protein meal is subjected to protein activation in step S1, hydrophobic triazole group introduction in step S2, and organic silicon grafting in step S3, so that molecular-level hydrophobic modification and structure strengthening are realized, and finally the impregnant is endowed with excellent waterproof performance; at the same time, the active amino groups contained in the modified protein hydrophobic agent can capture free formaldehyde and stabilize the resin structure to reduce formaldehyde emission, so that the impregnant has both waterproof performance and environmental protection performance. DETAILED DESCRIPTION

[0035] In order to better illustrate the purposes, technical solutions and advantages of the application, the application will be further described below in combination with specific examples.

[0036] The raw materials of the following examples and comparative examples are as follows:

[0037] Formaldehyde: CAS number is 50-00-0;

[0038] Urea: CAS number is 57-13-6;

[0039] Melamine: CAS number is 108-78-1;

[0040] 3,5-diamino-1,2,4-triazole: CAS number is 1455-77-2;

[0041] Dicyclohexylcarbodiimide: CAS number 538-75-0;

[0042] γ-(2,3-epoxypropoxy)propyltrimethoxysilane: CAS number 2530-85-0;

[0043] Soybean meal: Manufacturer is Guangxi Gangqing Oils Co., Ltd.;

[0044] Distillers' grains: Manufacturer is Guangxi Guibei Ecological Fermented Feed Business Department;

[0045] Peanut shell powder: Manufacturer is Nanyang Baochao Trading Co., Ltd.;

[0046] Cooked glutinous rice flour: Manufacturer: Xinghua Mingwang Food Co., Ltd., Model No. 001;

[0047] Unless otherwise specified, all other materials, reagents, etc. used in the examples and comparative examples are commercially available.

[0048] Example 1

[0049] A waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnating agent comprises the following raw materials in parts by weight: 133 parts formaldehyde, 38 parts urea, 44 parts melamine, 21 parts modified protein hydrophobic agent, 13 parts filler, and 4 parts curing agent; wherein the filler is a mixture of peanut shell powder, cooked glutinous rice flour, and heavy calcium carbonate in a mass ratio of 1:1:1, and the curing agent is ammonium chloride;

[0050] The preparation method of the modified protein hydrophobic agent includes the following steps:

[0051] S1. First, dissolve the alkali and urea in water to obtain a mixed solution, then add the protein meal, stir and dissolve to obtain a degradation solution; wherein, the protein meal is soybean meal, the alkali is sodium hydroxide, the mass ratio of the protein meal, alkali and urea is 4:1:1.6, the amount of water added is 2.5 times the total mass of the protein meal, alkali and urea, the stirring speed is 950 r / min and the time is 50 min;

[0052] S2. Add 3,5-diamino-1,2,4-triazole and dicyclohexylcarbodiimide solution to the degradation solution, and stir the reaction at 75°C to obtain the first solution; wherein, the solvent of the dicyclohexylcarbodiimide solution is N,N-dimethylformamide, the mass concentration of the dicyclohexylcarbodiimide solution is 65%, the mass ratio of the degradation solution, 3,5-diamino-1,2,4-triazole and dicyclohexylcarbodiimide solution is 4.2:1:1, the stirring speed is 500 r / min and the time is 30 min;

[0053] S3. Add γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution to the first solution and stir at 95°C to obtain the modified protein hydrophobic agent; wherein, the solvent of the γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution is anhydrous ethanol, the mass concentration of the γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution is 65%, the mass ratio of the first solution to the γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution is 6:1, the stirring speed is 500 r / min, and the stirring time is 30 min;

[0054] The preparation method of the waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnating agent includes the following steps:

[0055] (1) At room temperature, add the prescribed amount of formaldehyde to the reaction vessel, adjust the pH to 8.6, and raise the temperature to 52°C. Add the first part of urea and modified protein hydrophobic agent, and keep the reaction at 500 r / min for 35 min.

[0056] (2) Add the first part of melamine to the reaction vessel, heat to 90°C, adjust the pH to 5.2, and react under stirring at 500 r / min until the viscosity is 95 mPa·s to obtain reaction mixture A;

[0057] (3) Adjust the pH of reaction mixture A to 8.2 and the temperature to 87°C, add the second part of melamine, and keep the reaction at a constant temperature for 1.6 hours under stirring at 500 r / min.

[0058] (4) After the heat preservation reaction, the pH of the system was adjusted to 9.2 and the temperature was set to 45°C. The second part of urea was added, and the system was kept warm for 35 minutes under stirring at 500 r / min to obtain modified melamine resin.

[0059] (5) Add the curing agent of the formula amount to water to prepare a curing agent solution with a mass concentration of 25wt%, then add modified melamine resin and filler, and stir and mix at a speed of 500r / min to obtain the waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnating agent.

[0060] The mass ratio of the first part of urea to the second part of urea is 40:7, and the mass ratio of the first part of melamine to the second part of melamine is 6:35.

[0061] Example 2

[0062] A waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnating agent comprises the following raw materials in parts by weight: 120 parts formaldehyde, 35 parts urea, 40 parts melamine, 20 parts modified protein hydrophobic agent, 10 parts filler, and 4 parts curing agent; wherein the filler is a mixture of peanut shell powder, cooked glutinous rice flour, and heavy calcium carbonate in a mass ratio of 1:1:1, and the curing agent is ammonium chloride;

[0063] The preparation method of the modified protein hydrophobic agent includes the following steps:

[0064] S1. First, dissolve the alkali and urea in water to obtain a mixed solution. Then, add the protein meal and continue stirring to dissolve it to obtain a degradation solution. The protein meal is distillers' grains, the alkali is sodium hydroxide, the mass ratio of the protein meal, alkali and urea is 4:1:1.5, the amount of water added is twice the total mass of the protein meal, alkali and urea, the stirring speed is 900 r / min and the time is 60 min.

[0065] S2. Add 3,5-diamino-1,2,4-triazole and dicyclohexylcarbodiimide solution to the degradation solution, and stir the reaction at 70°C to obtain the first solution; wherein, the solvent of the dicyclohexylcarbodiimide solution is N,N-dimethylformamide, the mass concentration of the dicyclohexylcarbodiimide solution is 60%, the mass ratio of the degradation solution, 3,5-diamino-1,2,4-triazole and dicyclohexylcarbodiimide solution is 4:1:0.8, the stirring speed is 400 r / min and the stirring time is 40 min;

[0066] S3. Add γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution to the first solution and stir at 90°C to obtain the modified protein hydrophobic agent; wherein, the solvent of the γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution is anhydrous ethanol, the mass concentration of the γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution is 60%, the mass ratio of the first solution to the γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution is 5:1, the stirring speed is 400 r / min, and the stirring time is 40 min;

[0067] The preparation method of the waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnating agent includes the following steps:

[0068] (1) At room temperature, add the prescribed amount of formaldehyde to the reaction vessel, adjust the pH to 8.5, raise the temperature to 50°C, add the first part of urea and modified protein hydrophobic agent, and keep the reaction at a temperature of 40 min under stirring at a speed of 400 r / min.

[0069] (2) Add the first part of melamine to the reaction vessel, heat to 90°C, adjust the pH to 5.2, and react under stirring at 400 r / min until the viscosity is 90 mPa·s to obtain reaction mixture A;

[0070] (3) Adjust the pH of reaction mixture A to 8.0 and the temperature to 86°C, add the second part of melamine, and keep it warm for 2 hours under stirring at 400 r / min; (4) After the warm reaction, adjust the pH of the system to 9.0 and the temperature to 42°C, add the second part of urea, and keep it warm for 40 minutes under stirring at 400 r / min to obtain modified melamine resin;

[0071] (5) Add the curing agent of the formula amount to water to prepare a curing agent solution with a mass concentration of 20wt%, then add modified melamine resin and filler, and stir and mix at a speed of 400r / min to obtain the waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnating agent.

[0072] The mass ratio of the first part of urea to the second part of urea is 40:5, and the mass ratio of the first part of melamine to the second part of melamine is 5:35.

[0073] Example 3

[0074] A waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnating agent comprises the following raw materials in parts by weight: 140 parts formaldehyde, 40 parts urea, 45 parts melamine, 25 parts modified protein hydrophobic agent, 15 parts filler, and 5 parts curing agent; wherein the filler is a mixture of peanut shell powder, cooked glutinous rice flour, and heavy calcium carbonate in a mass ratio of 1:1:1, and the curing agent is ammonium chloride;

[0075] The preparation method of the modified protein hydrophobic agent includes the following steps:

[0076] S1. First, dissolve the alkali and urea in water to obtain a mixed solution. Then, add the protein meal and continue stirring to dissolve it to obtain a degradation solution. The protein meal is soybean meal, the alkali is sodium hydroxide, the mass ratio of the protein meal, alkali and urea is 5:1:2, the amount of water added is 3 times the total mass of the protein meal, alkali and urea, the stirring speed is 1000 r / min and the time is 40 min.

[0077] S2. Add 3,5-diamino-1,2,4-triazole and dicyclohexylcarbodiimide solution to the degradation solution, and stir the reaction at 70-80℃ to obtain the first solution; wherein, the solvent of the dicyclohexylcarbodiimide solution is N,N-dimethylformamide, the mass concentration of the dicyclohexylcarbodiimide solution is 70%, the mass ratio of the degradation solution, 3,5-diamino-1,2,4-triazole and dicyclohexylcarbodiimide solution is 5:1:1, the stirring speed is 600 r / min and the time is 20 min;

[0078] S3. Add γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution to the first solution and stir at 100°C to obtain the modified protein hydrophobic agent; wherein, the solvent of the γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution is anhydrous ethanol, the mass concentration of the γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution is 70%, the mass ratio of the first solution to the γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution is 7:1, the stirring speed is 600 r / min, and the stirring time is 20 min;

[0079] The preparation method of the waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnating agent includes the following steps:

[0080] (1) At room temperature, add the prescribed amount of formaldehyde to the reaction vessel, adjust the pH to 9.0, and raise the temperature to 55°C. Add the first part of urea and modified protein hydrophobic agent, and keep the reaction at 600 r / min for 30 min.

[0081] (2) Add the first part of melamine to the reaction vessel, heat to 92°C, adjust the pH to 5.3, and react under stirring at 600 r / min until the viscosity is 100 mPa·s to obtain reaction mixture A;

[0082] (3) Adjust the pH of reaction mixture A to 8.5 and the temperature to 88°C, add the second part of melamine, and keep the reaction at a constant temperature for 1.5 h under stirring at 600 r / min.

[0083] (4) After the heat preservation reaction, the pH of the system was adjusted to 9.5 and the temperature was adjusted to 47℃. The second part of urea was added, and the heat preservation reaction was carried out for 30 minutes under the stirring condition of 600r / min to obtain modified melamine resin.

[0084] (5) Add the curing agent of the formula amount to water to prepare a curing agent solution with a mass concentration of 30wt%, then add modified melamine resin and filler, and stir and mix at a speed of 500r / min to obtain the waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnating agent.

[0085] The mass ratio of the first part of urea to the second part of urea is 40:10, and the mass ratio of the first part of melamine to the second part of melamine is 7:35.

[0086] Example 4

[0087] The difference between Example 4 and Example 1 is that the total mass of the degradation solution, 3,5-diamino-1,2,4-triazole and dicyclohexylcarbodiimide solution remains unchanged, and the mass ratio of the degradation solution, 3,5-diamino-1,2,4-triazole and dicyclohexylcarbodiimide solution is 3:1:1.

[0088] Example 5

[0089] The difference between Example 5 and Example 1 is that the total mass of the degradation solution, 3,5-diamino-1,2,4-triazole and dicyclohexylcarbodiimide solution remains unchanged, and the mass ratio of the degradation solution, 3,5-diamino-1,2,4-triazole and dicyclohexylcarbodiimide solution is 6:1:1.

[0090] Comparative Example 1

[0091] The difference between Comparative Example 1 and Example 1 is that the melamine-urea-formaldehyde resin impregnating agent does not contain modified protein hydrophobic agent, and the missing amount is made up by using formaldehyde, urea, melamine, filler and curing agent in a mass ratio of 133:38:44:13:4.

[0092] Comparative Example 2

[0093] The difference between Comparative Example 2 and Example 1 is that the preparation method of the modified protein hydrophobic agent in Comparative Example 2 includes the following steps:

[0094] First, alkali and urea are dissolved in water to obtain a mixture. Then, protein meal is added and stirred to dissolve, thus obtaining the modified protein hydrophobic agent. The protein meal is soybean meal, the alkali is sodium hydroxide, the mass ratio of protein meal, alkali and urea is 4:1:1.6, the amount of water added is 2.5 times the total mass of protein meal, alkali and urea, and the stirring speed is 950 r / min for 50 min.

[0095] Comparative Example 3

[0096] The difference between Comparative Example 3 and Example 1 is that the preparation method of the modified protein hydrophobic agent includes the following steps:

[0097] S1. First, dissolve the alkali and urea in water to obtain a mixed solution, then add the protein meal, stir and dissolve to obtain a degradation solution; wherein, the protein meal is soybean meal, the alkali is sodium hydroxide, the mass ratio of the protein meal, alkali and urea is 4:1:1.6, the amount of water added is 2.5 times the total mass of the protein meal, alkali and urea, the stirring speed is 950 r / min and the time is 50 min;

[0098] S2. Add γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution to the degradation solution and stir at 95°C to obtain the modified protein hydrophobic agent; wherein, the solvent of the γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution is anhydrous ethanol, the mass concentration of the γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution is 65%, the mass ratio of the degradation solution to the γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution is 6:1, the stirring speed is 500 r / min, and the stirring time is 30 min.

[0099] Comparative Example 4

[0100] The difference between Comparative Example 4 and Example 1 is that the preparation method of the modified protein hydrophobic agent includes the following steps:

[0101] S1. First, dissolve the alkali and urea in water to obtain a mixed solution, then add the protein meal, stir and dissolve to obtain a degradation solution; wherein, the protein meal is soybean meal, the alkali is sodium hydroxide, the mass ratio of the protein meal, alkali and urea is 4:1:1.6, the amount of water added is 2.5 times the total mass of the protein meal, alkali and urea, the stirring speed is 950 r / min and the time is 50 min;

[0102] S2. Add 3,5-diamino-1,2,4-triazole to the degradation solution and stir at 75°C to obtain a first solution; wherein the mass ratio of the degradation solution to 3,5-diamino-1,2,4-triazole is 4.2:2, the stirring speed is 500 r / min, and the stirring time is 30 min.

[0103] S3. Add γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution to the first solution and stir at 95°C to obtain the modified protein hydrophobic agent; wherein, the solvent of the γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution is anhydrous ethanol, the mass concentration of the γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution is 65%, the mass ratio of the first solution to the γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution is 6:1, the stirring speed is 500 r / min, and the stirring time is 30 min.

[0104] Comparative Example 5

[0105] The difference between Comparative Example 5 and Example 1 is that the preparation method of the modified protein hydrophobic agent includes the following steps:

[0106] S1. First, dissolve the alkali and urea in water to obtain a mixed solution, then add the protein meal, stir and dissolve to obtain a degradation solution; wherein, the protein meal is soybean meal, the alkali is sodium hydroxide, the mass ratio of the protein meal, alkali and urea is 4:1:1.6, the amount of water added is 2.5 times the total mass of the protein meal, alkali and urea, the stirring speed is 950 r / min and the time is 50 min;

[0107] S2. Add dicyclohexylcarbodiimide solution to the degradation solution and stir at 75°C to obtain the first solution; wherein, the solvent of the dicyclohexylcarbodiimide solution is N,N-dimethylformamide, the mass concentration of the dicyclohexylcarbodiimide solution is 65%, the mass ratio of the degradation solution to the dicyclohexylcarbodiimide solution is 4.2:2, the stirring speed is 500 r / min, and the stirring time is 30 min;

[0108] S3. Add γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution to the first solution and stir the reaction at 90-100℃ to obtain the modified protein hydrophobic agent; wherein, the solvent of the γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution is anhydrous ethanol, the mass concentration of the γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution is 65%, the mass ratio of the first solution to the γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution is 6:1, the stirring speed is 500 r / min, and the time is 30 min.

[0109] Comparative Example 6

[0110] The difference between Comparative Example 6 and Example 1 is that the preparation method of the modified protein hydrophobic agent includes the following steps:

[0111] S1. First, dissolve the alkali and urea in water to obtain a mixed solution, then add the protein meal, stir and dissolve to obtain a degradation solution; wherein, the protein meal is soybean meal, the alkali is sodium hydroxide, the mass ratio of the protein meal, alkali and urea is 4:1:1.6, the amount of water added is 2.5 times the total mass of the protein meal, alkali and urea, the stirring speed is 950 r / min and the time is 50 min;

[0112] S2. Add 3,5-diamino-1,2,4-triazole and dicyclohexylcarbodiimide solution to the degradation solution, and stir the reaction at 75°C to obtain a modified protein hydrophobic agent; wherein, the solvent of the dicyclohexylcarbodiimide solution is N,N-dimethylformamide, the mass concentration of the dicyclohexylcarbodiimide solution is 65%, the mass ratio of the degradation solution, 3,5-diamino-1,2,4-triazole and dicyclohexylcarbodiimide solution is 4.2:1:1, the stirring speed is 500 r / min and the stirring time is 30 min.

[0113] Application Example 1-5 and Comparative Application Example 1-6

[0114] The method for preparing three-layer plywood includes the following steps: preparing three-layer plywood using the resin impregnating agents of Examples 1-6 and Comparative Examples 1-6 respectively, wherein the veneer is poplar, the thickness is 1.5 mm, the moisture content is 8-10%, and the glue application amount is 300 g / m². 2 Double-sided adhesive coating, hot-pressing process with a pressure of 1.0 MPa / m 2 The temperature was 130℃ and the time was 10 min, resulting in three-layer plywood for application examples 1-5 and comparative application examples 1-6.

[0115] Performance testing

[0116] The three-layer plywood of Application Examples 1-5 and Comparative Application Examples 1-6 were tested as follows:

[0117] 1. Tensile strength, modulus of elasticity and elongation at break were measured according to GB / T 7911-2013 thermosetting resin impregnated paper high pressure decorative laminate (HPL).

[0118] 2. Measure the formaldehyde emission in a dark room according to GB / T 17657-2022 Test Methods for Physical and Chemical Properties of Wood-based Panels and Decorative Panels;

[0119] 3. The dry and wet bond strength of plywood was tested according to GB / T 17657-2022 "Test Methods for Physical and Chemical Properties of Wood-based Panels and Decorative Wood-based Panels". The wet bond strength was tested according to the Class II plywood test method, i.e., the specimen was immersed in hot water at (63±3)℃ for 3 hours, and then cooled to room temperature for 10 minutes. The results of the above tests are shown in Table 1.

[0120] Table 1 shows the test results of three-layer plywood in Application Examples 1-5 and Comparative Application Examples 1-6.

[0121]

[0122] Table 1 shows the test results of three-layer plywood in Application Examples 1-5 and Comparative Application Examples 1-6. Combining the data of plywood in Application Examples 1 and 4-5, it can be seen that the mechanical properties, adhesion, and formaldehyde release of plywood in Application Examples 4-5 are lower than those in Application Example 1. This may be because the content of degradation solution in the modified protein hydrophobic agent in Application Example 4 is too low, resulting in too few protein segments and a reduction in free carboxyl and hydroxyl groups. This leads to a lack of active groups to react with 3,5-diamino-1,2,4-triazole and dicyclohexylcarbodiimide, thus reducing the degree of crosslinking of the system. In contrast, the content of degradation solution in Application Example 5 is higher, while the content of 3,5-diamino-1,2,4-triazole and dicyclohexylcarbodiimide solution is lower, which also reduces the crosslinking density. Therefore, when the ratio of degradation solution, 3,5-diamino-1,2,4-triazole and dicyclohexylcarbodiimide solution is (4-5):1:1, the amino group of protein degradation product in hydrophobic agent reacts more fully with the triazole ring and the epoxy group of silane, forming a denser cross-linked network, stronger interfacial bonding with resin, and optimal performance.

[0123] Combining Application Example 1 and Comparative Application Example 1, it can be seen that the impregnating agent of Comparative Application Example 1 does not contain modified protein hydrophobic agent. Its plywood will delaminate after being soaked in humid and hot conditions, and its mechanical properties will be significantly reduced. This may be because the hydrophilic groups of melamine resin are exposed, the resin crosslinking degree is low, and the filler dispersion is poor, indicating that the hydrophobic agent is the core of water resistance.

[0124] Compared to the impregnating agent in Application Example 2, which was not modified in steps S2 and S3 but only degraded in step S1, the plywood still delaminated after being soaked in humid heat and its mechanical properties were significantly reduced. This may be because the degraded protein was not grafted with hydrophobic groups (amide bonds) and only physically filled.

[0125] Compared to the impregnating agent in Application Example 3, which lacks step S2, its performance is significantly reduced. This may be because the absence of 3,5-diamino-1,2,4-triazole and dicyclohexylcarbodiimide grafting results in a lower density of the hydrophobic network formed by the silane acting alone.

[0126] In comparative applications 4-5, the absence of either 3,5-diamino-1,2,4-triazole or dicyclohexylcarbodiimide significantly reduced hydrophobicity, mechanical properties, and adhesiveness. This may be because the absence of dicyclohexylcarbodiimide leads to incomplete amidation of 3,5-diamino-1,2,4-triazole with the protein, resulting in low functional group utilization. Furthermore, the absence of 3,5-diamino-1,2,4-triazole results in insufficient hydrophobicity and crosslinking points. Therefore, cyclohexylcarbodiimide (DCC) activates the protein carboxyl group to generate a highly active O-acylisourea intermediate, which undergoes an amidation reaction (-CO-NH-) with the amino group of 3,5-diamino-1,2,4-triazole (DAT), grafting nitrogen-containing heterocycles onto the protein chain to form a dense hydrophobic layer that blocks water molecule penetration.

[0127] Compared to the impregnating agent in Application Example 6, which lacks γ-(2,3-epoxypropoxy)propyltrimethoxysilane, its hydrophobicity, mechanical properties, and adhesion are significantly reduced. This may be because the epoxy group of the lack of γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560) undergoes ring-opening aminolysis with the amino group of protein / DAT to generate a β-hydroxyamine structure. The methoxy group (-OCH3) is hydrolyzed to silanol (-SiOH), which condenses to form a Si-O-Si / Si-OC covalent network, resulting in a less dense hydrophobic network. At the same time, due to the lack of silane coupling effect, the adhesion of the impregnating agent to the substrate is reduced.

[0128] In summary, this invention uses natural renewable protein meal as a raw material to prepare a modified protein hydrophobic agent, which replaces traditional petroleum-based hydrophobic agents (such as organosilicon and fluorides) in the melamine-urea-formaldehyde resin impregnating agent, thus reducing environmental hazards. The renewable protein meal achieves molecular-level hydrophobic modification and structural reinforcement through protein activation in step S1, the introduction of hydrophobic triazole groups in step S2, and organosilicon grafting in step S3, ultimately endowing the impregnating agent with excellent waterproof properties. Simultaneously, the active amino groups contained in the modified protein hydrophobic agent can capture free formaldehyde and stabilize the resin structure to reduce formaldehyde emissions, ultimately making the impregnating agent both waterproof and environmentally friendly.

[0129] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A waterproof, environmentally friendly melamine-urea formaldehyde resin impregnant, characterized by, The raw materials include the following components by weight: formaldehyde 120-140 parts, urea 35-40 parts, melamine 40-45 parts, modified protein hydrophobic agent 20-25 parts, filler 10-15 parts, and curing agent 4-5 parts; The preparation method of the modified protein hydrophobic agent comprises the following steps: S1, first dissolve the alkali and urea in water to obtain a mixed solution, then add protein meal and stir to dissolve to obtain a degradation solution; wherein the mass ratio of the protein meal, the alkali and the urea is (4-5):1:(1.5-2), and the amount of water added is 2-3 times the total mass of the protein meal, the alkali and the urea; S2, add 3,5-diamino-1,2,4-triazole and dicyclohexyl carbodiimide solution to the degradation solution, and stir at 70-80℃ to obtain a first solution; wherein the solvent of the dicyclohexyl carbodiimide solution is N,N-dimethylformamide, the mass concentration of the dicyclohexyl carbodiimide solution is 60-70%, and the mass ratio of the degradation solution, 3,5-diamino-1,2,4-triazole and dicyclohexyl carbodiimide solution is (3-6):1:(0.8-1); S3, add γ-(2,3-epoxypropoxy) propyl trimethoxysilane solution to the first solution, and stir at 90-100℃ to obtain the modified protein hydrophobic agent; wherein the solvent of the γ-(2,3-epoxypropoxy) propyl trimethoxysilane solution is anhydrous ethanol, the mass concentration of the γ-(2,3-epoxypropoxy) propyl trimethoxysilane solution is 60-70%, and the mass ratio of the first solution and the γ-(2,3-epoxypropoxy) propyl trimethoxysilane solution is (5-7):

1.

2. The water-resistant, environmentally friendly melamine-urea formaldehyde resin impregnant according to claim 1, characterized in that, In the preparation step S1 of the modified protein hydrophobic agent, the stirring speed is 900-1000r / min, and the stirring time is 40-60min; and / or, in the preparation step S2 of the modified protein hydrophobic agent, the mass ratio of the degradation solution, 3,5-diamino-1,2,4-triazole and dicyclohexyl carbodiimide solution is (4-5):1:(0.8-1).

3. The water-resistant, environmentally friendly melamine-urea formaldehyde resin impregnant of claim 1, wherein, The protein meal is soybean meal and / or distiller's grains, and the alkali is sodium hydroxide.

4. The water-resistant, environmentally friendly melamine-urea formaldehyde resin impregnant of claim 1, wherein, In the preparation step S2 of the modified protein hydrophobic agent, the stirring speed is 400-600r / min, and the stirring time is 20-40min.

5. The water-resistant, environmentally friendly melamine-urea formaldehyde resin impregnant of claim 1, wherein, In the preparation step S3 of the modified protein hydrophobic agent, the stirring speed is 400-600r / min, and the stirring time is 20-40min.

6. The water-resistant, environmentally friendly melamine-urea formaldehyde resin impregnant of claim 1, wherein, The preparation raw materials of the impregnating agent are selected from at least one of (I)-(II): (I) the filler is at least one of peanut shell powder, cooked glutinous rice powder and heavy calcium carbonate; (II) the curing agent is ammonium chloride.

7. A process for the production of the water repellent, environmentally friendly melamine-urea-formaldehyde resin impregnant as defined in any one of claims 1 to 6, characterized in that, The preparation method comprises the following steps: (1) at room temperature, add the formula amount of formaldehyde to the reaction container, adjust the pH to 8.5-9.0, and heat to 50-55℃, then add the first part of urea and the modified protein hydrophobic agent, and react for 30-40min; (2) adding the first part of melamine into the reaction container, adjusting the temperature to 90-92℃, adjusting the pH to 5.2-5.3, and reacting until the viscosity is 90-100 mPa·s to obtain a reaction mixture A; (3) adjusting the pH of the reaction mixture A to 8.0-8.5 and the temperature to 86-88℃, adding the second part of melamine, and reacting for 1.5-2 h; (4) after the reaction, adjusting the pH of the system to 9.0-9.5 and the temperature to 42-47℃, adding the second part of urea, and reacting for 30-40 min to obtain the modified melamine resin; (5) adding the curing agent in the formula amount into water to prepare a curing agent solution with a mass concentration of 20-30 wt%, then adding the modified melamine resin and the filler, and stirring to obtain the waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnant.

8. The method for preparing a water-proof, eco-friendly melamine-urea formaldehyde resin impregnant according to claim 7, characterized by, The mass ratio of the first part of urea to the second part of urea is 40:(5-10).

9. The preparation method of the waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnating agent as described in claim 7, characterized in that, The mass ratio of the first part of melamine to the second part of melamine is (5-7):

35.

10. Use of the waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnant according to any one of claims 1-6 in the preparation of plywood.

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