Waterproof environment-friendly melamine-urea resin impregnant as well as preparation method and application thereof

Abstract

The invention relates to a waterproof environment-friendly melamine-urea resin impregnant as well as a preparation method and application thereof. The impregnant is prepared from the following raw materials in parts by weight: 120 to 140 parts of formaldehyde, 35 to 40 parts of urea, 40 to 45 parts of melamine, 20 to 25 parts of modified protein water repellent agent, 10 to 15 parts of filler and 4 to 5 parts of curing agent. Natural renewable protein meal is selected as a raw material to prepare the modified protein hydrophobing agent, a traditional petroleum-based hydrophobing agent is replaced, and environmental harm is reduced; according to the natural renewable protein meal, through protein activation in the step S1, hydrophobic triazole group introduction in the step S2 and organic silicon grafting in the step S3, molecular-level hydrophobic modification and structure strengthening are achieved, and finally the impregnant is endowed with excellent waterproof performance; meanwhile, active amino contained in the modified protein water repellent agent can capture free formaldehyde and stabilize a resin structure to reduce formaldehyde emission, and finally, the impregnant has waterproofness and environmental friendliness.

Description

Technical Field

[0001] This invention relates to the field of melamine-urea-formaldehyde resin impregnating agent technology, specifically to a waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnating agent, its preparation method, and its application. Background Technology

[0002] Melamine-Urea-Formaldehyde (MUF) resin is an amino resin synthesized through the condensation reaction of melamine, urea, and formaldehyde. Due to its excellent heat and chemical resistance, MUF resin has been widely used in various fields, such as plastic veneer panels, laminates, tableware, decorations, and adhesives.

[0003] However, melamine-urea-formaldehyde resin also has several drawbacks. Firstly, its water resistance and weather resistance are relatively weak; its performance may be affected and degraded in environments with high humidity, ultraviolet radiation, or large temperature fluctuations. Secondly, the cured resin may be brittle, which limits its application in situations requiring flexibility. Furthermore, the production and application of melamine-urea-formaldehyde resin releases formaldehyde, a harmful substance that may pose potential risks to human health and the environment. Therefore, appropriate measures are generally required to reduce formaldehyde release when using this resin. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnating agent, its preparation method, and its application.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, the present invention provides a waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnating agent, comprising 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.

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

[0008] S1. First, dissolve the alkali and urea in water to obtain a mixture, then add the protein meal, stir and 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. Add 3,5-diamino-1,2,4-triazole and dicyclohexylcarbodiimide solution to the degradation solution, and stir the reaction at 70-80℃ to obtain a first solution; wherein, the solvent of the dicyclohexylcarbodiimide solution is N,N-dimethylformamide, the mass concentration of the dicyclohexylcarbodiimide solution is 60-70%, and the mass ratio of the degradation solution, 3,5-diamino-1,2,4-triazole and dicyclohexylcarbodiimide solution is (3-6):1:(0.8-1);

[0010] 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 60-70%, and the mass ratio of the first solution to the γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution is (5-7):1.

[0011] In the preparation method of the modified protein hydrophobic agent of the present invention, each step involves the following reaction:

[0012] Step S1: Under alkaline conditions, urea mainly acts as a protein denaturant, breaking hydrogen bonds and hydrophobic interactions, promoting peptide bond hydrolysis, generating polypeptide fragments and free amino acids, and exposing more carboxyl (-COOH) and amino (-NH2) active sites.

[0013] Step S2: Dicyclohexylcarbodiimide (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 a nitrogen-containing heterocycle onto the protein chain to form a dense hydrophobic layer that blocks water molecule permeation. Furthermore, the two amino groups of DAT simultaneously connect to two protein chains, forming a three-dimensional network that reduces water molecule diffusion channels.

[0014] Step S3: The epoxy group in the γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH560) molecule undergoes a ring-opening addition reaction with the residual amino group (-NH2) in the first solution (epoxy groups readily react with amino groups at high temperatures), forming a stable CN covalent bond, thus grafting the silane molecule onto the peptide derivative. The other end of KH560 is a trimethoxysilyl group (-Si(OCH3)3), which is hydrophilic and can form chemical bonds with the hydroxyl groups of the substrate (such as wood / fiber), improving the adhesion and durability of the impregnating agent on the substrate.

[0015] At the same time, because modified protein hydrophobic agents have good hydrophobicity, they not only block moisture but also reduce the contact between formaldehyde and water, preventing its hydrolytic release.

[0016] In the modified protein hydrophobic agent of the present invention, the active groups (such as amino and hydroxyl groups) undergo a condensation reaction with formaldehyde in the resin to form a stable network structure, which fixes the free formaldehyde in the resin, thereby significantly reducing the content of unreacted formaldehyde in the resin and meeting environmental protection requirements.

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

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

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

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

[0021] Preferably, in step S3 of the preparation of the modified protein hydrophobic agent, the stirring speed 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 flour, and heavy calcium carbonate.

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

[0024] Secondly, the present invention provides a method for preparing a waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnating agent, characterized by comprising the following steps:

[0025] (1) Add the prescribed amount of formaldehyde to the reaction vessel at room temperature, adjust the pH to 8.5-9.0, and raise the temperature to 50-55℃. Add the first part of urea and modified protein hydrophobic agent, and keep the reaction at the temperature for 30-40 minutes.

[0026] (2) Add the first part of melamine to the reaction vessel, heat to 90-92℃, adjust the pH to 5.2-5.3, and react until the viscosity is 90-100mPa·s to obtain reaction mixture A;

[0027] (3) Adjust the pH of reaction mixture A to 8.0-8.5 and the temperature to 86-88℃, add the second part of melamine, and keep the reaction at the temperature for 1.5-2 hours;

[0028] (4) After the heat preservation reaction, adjust the pH of the system to 9.0-9.5 and the temperature to 42-47℃, add the second part of urea, and keep the reaction for 30-40 minutes to obtain the modified melamine resin.

[0029] (5) Add the curing agent of the formula amount to water to prepare a curing agent solution with a mass concentration of 20-30wt%, then add modified melamine resin and filler, stir and mix well to obtain the waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnating agent.

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

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

[0032] Thirdly, the present invention provides the application of the waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnating agent of the first aspect in the preparation of plywood.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] This invention uses natural renewable protein meal as raw material to prepare a modified protein hydrophobic agent, which replaces traditional petroleum-based hydrophobic agents (such as organosilicon and fluorides) in melamine-urea-formaldehyde resin impregnating agents, thereby reducing environmental hazards. The renewable protein meal achieves molecular-level hydrophobic modification and structural reinforcement through protein activation in step S1, introduction of hydrophobic triazole groups in step S2, and organosilicon grafting in step S3, ultimately endowing the impregnating agent 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 emissions, ultimately making the impregnating agent both waterproof and environmentally friendly. Detailed Implementation

[0035] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

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

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

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

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

[0040] 3,5-Diamino-1,2,4-triazole: CAS number 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 stirring 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 and environmentally friendly melamine-urea-formaldehyde resin impregnating agent, characterized in that, The raw materials include the following 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; The preparation method of the modified protein hydrophobic agent includes the following steps: S1. First, dissolve the alkali and urea in water to obtain a mixture, then add the protein meal, stir and 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; 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 a first solution; wherein, the solvent of the dicyclohexylcarbodiimide solution is N,N-dimethylformamide, the mass concentration of the dicyclohexylcarbodiimide solution is 60-70%, and the mass ratio of the degradation solution, 3,5-diamino-1,2,4-triazole and dicyclohexylcarbodiimide solution is (3-6):1:(0.8-1); 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 60-70%, and the mass ratio of the first solution to the γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution is (5-7):

1.

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

3. The waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnating agent as described in claim 1, characterized in that, The protein meal is soybean meal and / or distiller's grains, and the alkali is sodium hydroxide.

4. The waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnating agent as described in claim 1, characterized in that, In step S2 of the preparation of the modified protein hydrophobic agent, the stirring speed is 400-600 r / min and the time is 20-40 min.

5. The waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnating agent as described in claim 1, characterized in that, In step S3 of the preparation of the modified protein hydrophobic agent, the stirring speed is 400-600 r / min and the time is 20-40 min.

6. The waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnating agent as described in claim 1, characterized in that, The raw materials for preparing 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. The method for preparing the waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnating agent according to any one of claims 1-6, characterized in that, Includes the following steps: (1) Add the prescribed amount of formaldehyde to the reaction vessel at room temperature, adjust the pH to 8.5-9.0, and raise the temperature to 50-55℃. Add the first part of urea and modified protein hydrophobic agent, and keep the reaction at the temperature for 30-40 minutes. (2) Add the first part of melamine to the reaction vessel, heat to 90-92℃, adjust the pH to 5.2-5.3, and react until the viscosity is 90-100mPa·s to obtain reaction mixture A; (3) Adjust the pH of reaction mixture A to 8.0-8.5 and the temperature to 86-88℃, add the second part of melamine, and keep the reaction at the temperature for 1.5-2 hours; (4) After the heat preservation reaction, adjust the pH of the system to 9.0-9.5 and the temperature to 42-47℃, add the second part of urea, and keep the reaction for 30-40 minutes to obtain the modified melamine resin. (5) Add the curing agent of the formula amount to water to prepare a curing agent solution with a mass concentration of 20-30wt%, then add modified melamine resin and filler, stir and mix well to obtain the waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnating agent.

8. 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 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 melamine to the second melamine is (5-7):

35.

10. The application of the waterproof and environmentally friendly melamine-urea-formaldehyde resin impregnating agent according to any one of claims 1-6 in the preparation of plywood.

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