Urea-formaldehyde resin blended guanazole-phytic acid-copper flame-retardant resin coating as well as preparation method and application thereof

Abstract

The invention discloses a urea-formaldehyde resin blended guanazole-phytic acid-copper flame-retardant resin coating which is prepared by taking a GZ / PA / Cu flame retardant, combined urea and formaldehyde as main raw materials, taking DOP as a plasticizer and taking TA as a curing agent through three-stage reaction; the raw materials of the GZ / PA / Cu flame retardant comprise GZ, PA and a copper source which are bio-based flame-retardant components; the UF-GZ / PA / Cu decomposition temperature is 195.5 + / -2.1 DEG C, the temperature of the maximum decomposition rate is 300.6 + / -1.5 DEG C, and the carbon residue amount is 29.8 + / -2.5 wt.%; and a compact carbon residue layer can be formed. The preparation method comprises the following steps: 1, preparing the GZ / PA / Cu flame retardant; 2, preparing a modified urea-formaldehyde resin emulsion UF; when being used as a wood flame-retardant coating, the flame-retardant coating passes a UL-94V-0 grade test; and the heat release rate HRR is 25.38 + / -1.25 kW / m < 2 >.

Description

Technical Field

[0001] The invention relates to the field of flame retardant materials, and in particular to a urea-formaldehyde resin blended guanazole-phytic acid-copper flame retardant resin coating and a preparation method and application thereof. Background Art

[0002] Wood is widely used in our daily life, but wood is highly flammable. In order to solve the problem of wood flammability, flame retardant coating can be applied on the surface of wood to heat the surface of wood to produce a dense carbon layer, thereby achieving the purpose of flame retardancy. At present, common flame retardants are divided into two categories: additive flame retardants and reactive flame retardants. Among them, additive flame retardants have the advantages of being simple and easy to use and having a wide range of applications due to the method of directly adding flame retardants. Among the commonly used additive flame retardants, halogen-containing flame retardants have good flame retardant effects, but such flame retardants have the problem of producing toxic substances when heated, thus causing environmental pollution problems. A common solution is to use phosphorus-containing flame retardants to replace halogen-containing flame retardants. Bio-based flame retardants in phosphorus-containing flame retardants, such as bio-based flame retardants based on phytic acid, although their flame retardant properties cannot yet achieve the flame retardant effects of halogen-containing flame retardants, have the characteristics of low toxicity and green environmental protection.

[0003] In order to improve the flame retardant properties of bio-based flame retardants, the flame retardant properties can be improved by introducing metal elements into phytic acid. For example, the existing document 1 (Experimental study on the synergistic flame retardant effect of bio-based magnesium phytate and rice husk ash on epoxy resins [J]. Journal of Thermal Analysis and Calorimetry, 2021, 146 (1): 153-164) synthesizes magnesium phytate flame retardant by simple complex reaction, and the peak heat release rate of 5% magnesium phytate flame retardant is only reduced by 28.6%, the LOI value is only 22.2%, and the residual carbon amount at 800 ° C is 19.69wt.%. The problem with this technical solution is that there are many holes on the surface of the carbon layer formed after combustion, that is, it is impossible to form a dense residual carbon layer. The reason is that the complex formed by magnesium and phytic acid has poor compatibility and dispersibility, resulting in poor quality of the formed carbon layer.

[0004] This type of Mg-based flame retardant also has existing literature 2 (A novel bio-based charcoal-forming agent based on chitosan and phytate@mg to improve the flameretardancy of poly(lactic acid[J].Journal of Applied Polymer Science, 2024, 141(11):e55074) which synthesizes Mg@PA-CS flame retardant, and the carbon residue rate at 800°C is only 11.48wt.%, and the LOI value is 34%. This technical solution also has the technical problem of being unable to form a dense residual carbon layer.

[0005] It can be confirmed from the existing documents 1 and 2 that the introduction of metal elements into phytic acid can improve the flame retardancy. However, the type of metal elements may have problems of poor compatibility and dispersibility due to the properties of the obtained phytic acid complex itself.

[0006] In order to solve the above-mentioned problems of Mg-based flame retardants, flame retardancy can be improved by introducing other metal elements. For example, existing document 3 (Rigid polyurethane foam composites based on bivalent metal phytate: thermal stability, flame retardancy, and fire toxicity [J]. Polymer-Plastics Technology and Materials, 2022, 61 (11): 1204-1222) synthesized phytic acid metal salt flame retardants such as copper phytate, and the residual carbon content of the copper phytate flame retardant at 700 ° C reached 26.2 wt.%. The carbon layer formed after the copper phytate flame retardant is burned is dense and has almost no holes, so it obtains better flame retardant properties than existing documents 2 and existing documents 3. The reason is that compared with magnesium, the Cu element has a stronger binding force with the PA functional group, which is specifically reflected in Cu 2+ Ions have stronger binding affinity, biocompatibility and ion dispersibility. However, the problem with this technical solution is that the amount of copper phytate flame retardant added needs to reach 30wt.% to obtain flame retardant properties that meet application requirements, that is, the amount added is too large. Summary of the invention

[0007] The purpose of the present invention is to provide a urea-formaldehyde resin blended guanazole-phytic acid-copper flame retardant resin coating and its preparation method and application. According to the inventor's research, the problem of excessive addition of copper phytate flame retardant in the prior art is that although the copper phytate flame retardant promotes the formation of a dense residual carbon layer in the carbon layer during the combustion process, the flame retardant performance of the copper phytate flame retardant itself is poor, so it is impossible to effectively improve the final flame retardant effect. Based on the above reasons, the inventor has found that by introducing a nitrogen source, a synergistic effect is formed with the copper phytate flame retardant, and the flame retardant performance can be significantly improved, thereby achieving a significant reduction in the amount of flame retardant added while maintaining the flame retardant performance.

[0008] The specific idea of ​​the invention is to introduce 3,5-diamino-1,2,4-triazole GZ containing amino group as nitrogen source, combine with phytic acid PA and copper hydroxide Cu(OH)2, and prepare GZ / PA / Cu flame retardant through reaction; then, add GZ / PA / Cu flame retardant into urea-formaldehyde resin, cooperate with tannic acid TA as curing agent, and dioctyl phthalate as plasticizer to prepare bio-based flame retardant resin coating. The role of each component in the technical solution is as follows:

[0009] 1. By introducing nitrogen-based compounds, the flame retardant properties of copper phytate are significantly improved;

[0010] 2. By adjusting the preparation process, that is, adding GZ / PA / Cu flame retardant in the acidic stage of synthetic resin, the compatibility and dispersibility of flame retardant are significantly improved;

[0011] 3. Using tannic acid TA as a curing agent not only has the function of adjusting the curing speed of urea-formaldehyde resin, but also has the function of improving the flame retardant performance of the matrix, and improving the thermal insulation and heat preservation performance of the substrate;

[0012] 4. Using dioctyl phthalate as a plasticizer can effectively prevent the cracking of urea-formaldehyde resin during the curing process and provide a uniform and dense matrix for the subsequent acquisition of a dense residual carbon layer.

[0013] In order to achieve the above invention object, the technical solution adopted by the present invention is:

[0014] A urea-formaldehyde resin blended guanazole-phytic acid-copper flame retardant resin coating, which is prepared from guanazole-phytic acid-copper flame retardant GZ / PA / Cu, urea and formaldehyde as main raw materials, dioctyl phthalate DOP as plasticizer, and tannic acid TA as curing agent, and undergoes three-stage reaction to obtain the urea-formaldehyde resin blended guanazole-phytic acid-copper flame retardant resin coating UF-GZ / PA / Cu;

[0015] The GZ / PA / Cu is prepared by complexing reaction using 3,5-diamino-1,2,4-triazole GZ, phytic acid PA and copper source as bio-based flame retardant ingredients as raw materials;

[0016] The obtained GZ / PA / Cu contains Cu4O(PO4)2, CuO, -NH2, P=O and OPC;

[0017] The temperature at which the UF-GZ / PA / Cu decomposes to 5% by mass is 195.5±2.1°C, the temperature at which the maximum decomposition rate is reached is 300.6±1.5°C, and the residual carbon content at 800°C is 29.8±2.5wt.%;

[0018] When the addition amount of GZ / PA / Cu is 1wt.%, a dense residual carbon layer is formed.

[0019] A method for preparing a urea-formaldehyde resin-blended guanazole-phytic acid-copper flame-retardant resin coating comprises the following steps:

[0020] Step 1, preparation of GZ / PA / Cu flame retardant, first, dissolving 3,5-diamino-1,2,4-triazole GZ in water to obtain a GZ solution, then, under certain conditions, adding a phytic acid PA solution dropwise to the GZ solution to obtain a GZ / PA solution, and finally, under certain conditions, adding copper hydroxide to the GZ / PA solution to react, after the reaction is completed, filtering, washing, drying, and grinding the obtained product into powder to obtain a guanazole-phytic acid-copper flame retardant, referred to as GZ / PA / Cu;

[0021] The washing condition is that the pH of the washing solution is 5.0-6.0;

[0022] The drying conditions are as follows: drying temperature is 80°C and drying time is 24h;

[0023] In the step 1, the mass ratio of GZ, PA and Cu(OH)2 is 1:6:1;

[0024] In step 1, the conditions for preparing the GZ / PA solution are: stirring temperature of 70° C., stirring speed of 500-600 rpm, stirring time of 30 min, and drop rate of 0.5 drops / s;

[0025] In step 1, the reaction conditions are: reaction temperature is 90° C., and reaction time is 3 h;

[0026] Step 2, preparation of modified urea-formaldehyde resin emulsion UF, first, adding a certain amount of sodium hydroxide solution to formaldehyde solution to adjust the pH value of the solution to obtain solution A, then, under certain conditions, adding urea, GZ / PA / Cu and other raw materials in three stages to prepare urea-formaldehyde resin blended guanazole-phytic acid-copper flame retardant resin coating, referred to as UF-GZ / PA / Cu,

[0027] In the step 2, the mass ratio of the total added amount of GZ / PA / Cu, formaldehyde and urea obtained in step 1 is 1:100:57;

[0028] In step 2, the conditions for preparing solution A are to adjust the pH value of the solution to 8.0-8.5;

[0029] In step 2, the conditions for adding urea are: a stirring speed of 400-500 rpm and a reaction temperature of 90° C.;

[0030] In step 2, the three stages of adding urea are specifically:

[0031] Step 2.1 is to add the first stage urea under a certain temperature condition, and continue stirring for a certain stirring time after the addition is completed;

[0032] In the step 2.1, the amount of urea added is 64.9% of the total amount of urea, the temperature in step 2.1 is 90° C., and the stirring time is continued for 30 minutes;

[0033] Step 2.2 is, under a certain temperature condition, firstly add acetic acid solution to adjust the pH value of the solution, then add the second stage urea, and finally add GZ / PA / Cu. After the addition is completed, continue stirring for a certain stirring time until the reaction end point is reached;

[0034] The endpoint of the second stage reaction is determined by the following sign: a drop of the solution is dropped into 30°C water, and the dropped solution condenses in the water without dispersing;

[0035] In the step 2.2, the amount of urea added is 21.6% of the total amount of urea, the pH value of the solution is adjusted to 4.5-5.0, the temperature of step 2.2 is 90° C., and the stirring time is continued for 15 minutes;

[0036] Step 2.3 is to first add sodium hydroxide solution to adjust the pH value under a certain temperature condition, and then add urea from the third stage. After the addition is completed, stir under the conditions to obtain UF-GZ / PA / Cu;

[0037] In the step 2.3, the amount of urea added is 13.3% of the total amount of urea, the pH value of the solution is adjusted to 7.5-8.0, the temperature of step 2.2 is 90° C. when adjusting the pH value, and after the pH value is adjusted, the temperature is adjusted to 70° C., and the stirring time is 30-40 minutes.

[0038] A urea-formaldehyde resin blended guanazole-phytic acid-copper flame-retardant resin coating, when used as a wood flame-retardant coating, has flame-retardant properties and can form a continuous and dense residual carbon layer after combustion; in the UL-94 grade test, it passes the UL-94V-0 grade test; in the cone calorimetry test, the heat release rate HRR is 25.38±1.25kW / m 2 .

[0039] The technical effect of the urea-formaldehyde resin blended guanazole-phytic acid-copper flame retardant resin coating obtained by the present invention is tested as follows:

[0040] The TG test results show that when the decomposition mass of UF-GZ / PA / Cu is 5%, the temperature is 195.5±2.1℃, the temperature when the maximum decomposition rate is reached is 300.6±1.5℃, and the residual carbon content at 800℃ is 29.8±2.5wt.%. Adding GZ / PA / Cu can increase the residual carbon rate of the material and produce a more stable residual carbon layer in the high temperature area.

[0041] The expanded carbon layer formed on the surface of NW coated with UF-GZ / PA / Cu flame retardant coating after combustion was further tested by SEM. UF-GZ / PA / Cu can form a dense carbon layer with almost no holes. The test results show that UF-GZ / PA / Cu can form a high-quality residual carbon layer after combustion, which can isolate oxygen and heat, thereby improving the flame retardant properties of NW.

[0042] The vertical burning test showed that coating with UF-GZ / PA / Cu flame retardant coating enabled NW to pass the UL-94V-0 rating.

[0043] The limiting oxygen index test shows that coating UF-GZ / PA / Cu flame retardant coating can improve its limiting oxygen index, LOI reaching 32.0%.

[0044] The results of cone calorimetry tests show that the heat release rate of wood coated with UF-GZ / PA / Cu flame retardant coating is 25.38±1.25%, which can significantly reduce the heat release rate of NW.

[0045] Therefore, the bio-based flame retardant urea-formaldehyde resin of the present invention has the following advantages over the prior art:

[0046] 1. The bio-based flame retardant resin coating of the present invention significantly improves the flame retardant performance while greatly reducing the addition amount. Specifically, the addition amount of the GZ / PA / Cu flame retardant of the present invention is only 1wt.%, while the addition amount of the prior art (existing document 3) is 30wt.%;

[0047] 2. The raw materials involved in the present invention are all commercially available and are low-cost raw materials, that is, they meet the application requirements of large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 The XRD patterns of Example 1, Comparative Example 4, Comparative Example 5 and Comparative Example 6 are shown in FIG.

[0049] Figure 2 FT-IR images of Example 1, Comparative Example 4, Comparative Example 5 and Comparative Example 6;

[0050] Figure 3 FT-IR images of Example 1, Comparative Example 4, Comparative Example 5 and Comparative Example 6;

[0051] Figure 4 is the EDS diagram of Example 1;

[0052] Figure 5 TG diagrams of Example 1, Comparative Example 4, Comparative Example 5 and Comparative Example 6;

[0053] Figure 6 is the SEM image of Example 1;

[0054] Figure 7 It is a vertical combustion test diagram of Example 1, Comparative Example 2 and Example 2;

[0055] Figure 8 It is the HRR diagram of Example 1, Comparative Example 4, Comparative Example 5 and Comparative Example 6;

[0056] Fig. 9 It is the SEM picture of comparative example 1;

[0057] Fig.10 It is the SEM picture of comparative example 2;

[0058] Fig.11 It is the TG diagram of Comparative Example 3;

[0059] Fig.12 It is the EDS diagram of Comparative Example 4;

[0060] Fig.13 It is the SEN diagram of Comparative Example 4;

[0061] Fig.14 is the EDS diagram of Comparative Example 5;

[0062] Fig.15 It is the SEM picture of comparative example 5;

[0063] Fig.16 is the EDS diagram of Comparative Example 6;

[0064] Fig.17 This is the SEM image of Comparative Example 6. DETAILED DESCRIPTION

[0065] The present invention is further described in detail through embodiments and in conjunction with the accompanying drawings, but the present invention is not limited thereto.

[0066] Example 1

[0067] A method for preparing a urea-formaldehyde resin-blended guanazole-phytic acid-copper flame retardant resin coating comprises the following steps:

[0068] Step 1, preparation of GZ / PA / Cu flame retardant, first, dissolving 4.459g 3,5-diamino-1,2,4-triazole GZ in 150mL water to obtain a GZ solution, then, under the conditions of a stirring temperature of 70°C, a stirring speed of 600rpm, a stirring time of 30min, and a dropping rate of 0.5 drops / s, 14.25mL 37wt.% phytic acid PA solution is added dropwise to the GZ solution to obtain a GZ / PA solution, finally, under the conditions of a reaction temperature of 90°C and a reaction time of 3h, 8.664g copper hydroxide is added to the GZ / PA solution for reaction, and after the reaction is completed, the obtained product is filtered, washed, dried, and ground into powder to obtain a guanazole-phytic acid-copper flame retardant, referred to as GZ / PA / Cu;

[0069] The washing condition is that the pH of the washing solution is 5-6;

[0070] The drying conditions are as follows: drying temperature is 80°C and drying time is 24h;

[0071] In order to prove the GZ / PA / Cu composition, that is, the successful synthesis, XRD test was carried out. The test results are as follows Figure 1 As shown, GZ / PA / Cu contains characteristic peaks of Cu4O(PO4)2 and CuO. The test results show that the Cu element is successfully complexed with PA.

[0072] In order to prove the composition of GZ / PA / Cu, i.e. the successful synthesis, FT-IR test was performed. The test results are as follows Figure 2 As shown, GZ / PA / Cu contains the characteristic peaks of -NH2, P=O and OPC at the same time, among which the characteristic peak of -NH2 belongs to GZ, and the characteristic peaks of P=O and OPC belong to PA.

[0073] The XRD and FT-IR test results proved that the GZ / PA / Mg flame retardant was successfully synthesized.

[0074] Step 2, preparation of UF-GZ / PA / Cu, first, 20wt.% sodium hydroxide solution is added to 100g 37wt.% formaldehyde solution, and the pH value of the solution is adjusted to 8.0-8.5 to obtain solution A, then, under the conditions of stirring speed of 400rpm and reaction temperature of 90°C, urea, GZ / PA / Cu and other raw materials are added in three stages to prepare urea-formaldehyde resin blended guanazole-phytic acid-copper flame retardant resin coating, referred to as UF-GZ / PA / Cu,

[0075] The three stages are:

[0076] Step 2.1 is to add 37 g of the first-stage urea while maintaining the temperature at 90°C. After the addition is completed, continue stirring for 30 minutes;

[0077] Step 2.2 is to add 20wt.% acetic acid solution at 90°C, adjust the pH value of the solution to 4.5-5.0, add 12.4g of the second stage urea, and finally add 1g of GZ / PA / Cu. After the addition is completed, continue stirring for 15min until the reaction end point is reached;

[0078] The endpoint of the second stage reaction is determined by dropping a drop of the solution into 30°C water, and the dropped solution condenses in the water without dispersing;

[0079] Step 2.3 is to add 20wt.% sodium hydroxide solution while maintaining the temperature at 90°C, adjust the pH value to 7.5-8.0, and then add 7.6g of urea from the third stage. After the addition is completed, adjust the temperature and stir at a stirring temperature of 70°C for 30 minutes to obtain UF-GZ / PA / Cu.

[0080] Since subsequent tests need to be performed after UF-GZ / PA / Cu is cured, a specific curing method is provided. The curing method is, first, under the conditions of a stirring rate of 400rpm and a stirring time of 30min, dioctyl phthalate, tannic acid and UF-GZ / PA / Cu satisfy a mass ratio of 0.1:0.1:10, that is, 0.3g of dioctyl phthalate and 0.3g of tannic acid are added to 30g of UF-GZ / PA / Cu to obtain a GZ / PA / Cu flame retardant resin coating, and then, according to experimental needs, the GZ / PA / Cu flame retardant resin coating is placed in a mold for direct curing or applied to the surface of wood, and cured for 72h to obtain a flame retardant resin coating based on GZ / PA / Cu. Since there is no need to distinguish, the cured material is still referred to as UF-GZ / PA / Cu;

[0081] The specific method for coating the wood surface is to evenly coat UF-GZ / PA / Cu on the wood surface with a coating thickness of 0.3 mm, and then dry it for 24 hours after coating.

[0082] In order to prove the composition of UF-GZ / PA / Cu, i.e., the successful synthesis, FT-IR test was carried out. At the same time, since FT-IR test cannot prove the existence of metal elements, EDS test was carried out on the UF-GZ / PA / Cu after combustion.

[0083] FT-IR test results are as follows Figure 3 As shown, there is no substantial difference between UF-GZ / PA / Cu and GZ / PA / Cu. That is, they all contain characteristic peaks of -NH2, P=O and OPC, among which the characteristic peak of -NH2 belongs to GZ, and the characteristic peaks of P=O and OPC belong to PA;

[0084] EDS test results are as follows Figure 4 As shown, the surface of the carbon layer of UF-GZ / PA / Cu after combustion contains not only N and P elements, but also Cu elements, among which N elements come from GZ, P elements come from PA, and Cu elements come from Cu(OH)2;

[0085] The results of FT-IR and EDS tests showed that UF-GZ / PA / Cu flame retardant coating was composed of GZ, PA and Cu elements, that is, UF-GZ / PA / Cu was successfully synthesized.

[0086] In order to prove the technical effect of UF-GZ / PA / Cu as a wood flame retardant coating, TG test was carried out. The test results are as follows Figure 5 As shown in Table 1, the temperature when the decomposition mass of UF-GZ / PA / Cu is 5% is 195.5°C, the temperature when the maximum decomposition rate is reached is 300.6°C, and the residual carbon amount at 800°C is 29.8wt.%.

[0087] Table 1 TG test results summary

[0088]

[0089] In order to further verify the microstructure of the residual carbon layer, SEM test was performed on the surface of UF-GZ / PA / Cu after TG test. Figure 6 As shown, UF-GZ / PA / Cu can form a dense carbon residue layer with almost no holes, which is referred to as a dense structure. The test results show that UF-GZ / PA / Cu can form a high-quality carbon residue layer after combustion, which can isolate oxygen and heat, thereby improving the flame retardant properties of wood.

[0090] In order to further demonstrate the flame retardancy of UF-GZ / PA / Cu, vertical burning test and limiting oxygen index test were performed.

[0091] Vertical burning test results are as follows Figure 7 As shown in Table 2, the open flame time after the first ignition of UF-GZ / PA / Cu is 0.9s, and the open flame and flameless combustion time after the second ignition is 1.4s, with no dripping, indicating that UF-GZ / PA / Cu passes the UL-94V-0 grade;

[0092] The limiting oxygen index test results are shown in Table 2. The limiting oxygen index of UF-GZ / PA / Cu is 32.0%.

[0093] Table 2 Vertical combustion test and oxygen index test results

[0094]

[0095]

[0096] In order to further quantify the flame retardancy of UF-GZ / PA / Cu, cone calorimetry tests were performed. The test results are shown in Figure 8 As shown in Figure 2, the heat release rate HHR of UF-GZ / PA / Cu is 25.38kW / m 2 .

[0097] In order to demonstrate the effect of UF-GZ / PA / Cu on the flame retardant properties of wood, comparative example 1 is provided, wood without flame retardant coating is used as a basic reference sample, and comparative example 2 is provided, pure urea-formaldehyde resin UF without adding GZ / PA / Cu flame retardant.

[0098] Comparative Example 1

[0099] A type of wood that is not coated with flame retardant, referred to as NW.

[0100] In order to verify the microstructure of the residual carbon layer, SEM test was performed on the NW after complete combustion. Fig. 9 As shown, the carbon layer after burning NW is almost completely broken, referred to as broken structure. Compared with Example 1, coating UF-GZ / PA / Cu can form a dense residual carbon layer, that is, improve the flame retardant performance.

[0101] To further demonstrate the flame retardancy of NW, vertical burning test and limiting oxygen index test were performed.

[0102] Vertical burning test results are as follows Figure 7As shown in Table 2, the open flame time of NW after the first ignition is greater than 60s, and there is dripping, which indicates that NW does not pass the UL-94 V-0 grade. Compared with Example 1, it can be seen that coating UF-GZ / PA / Cu can make NW pass the UL-94 grade test.

[0103] The limiting oxygen index test results are shown in Table 2. The limiting oxygen index of NW is 20.3%. Compared with Example 1, it can be seen that coating UF-GZ / PA / Cu can increase the limiting oxygen index from 20.0% to 32.0%.

[0104] To further quantify the flame retardancy of NWs, cone calorimetry tests were performed. Figure 8 As shown, the HRR of NW is 206.73kW / m 2 Compared with Example 1, it can be seen that coating UF-GZ / PA / Cu can reduce the HRR by 87.70%, that is, significantly reduce the heat release rate, thereby significantly improving the flame retardancy.

[0105] Comparative Example 2

[0106] A method for preparing pure urea-formaldehyde resin UF without adding GZ / PA / Cu flame retardant, wherein the steps not specifically stated are the same as those in Example 1, except that: step 1 is not required, and in step 2, step 2.2 does not add GZ / PA / Cu, so as to obtain pure urea-formaldehyde resin UF without adding GZ / PA / Cu flame retardant, referred to as UF.

[0107] In order to prove the technical effect of UF as a wood flame retardant coating, TG test was carried out. The test results are as follows Figure 5 As shown in Table 1, the temperature at which the UF decomposition mass is 5% is 204.2°C, the temperature at which the maximum decomposition rate is reached is 304.2°C, and the residual carbon amount at 800°C is 10.0wt.%. Compared with Example 1, the addition of UF-GZ / PA / Cu can increase the residual carbon amount from 10.0wt.% to 29.8wt.%, and the increase is 198.0%, that is, the addition of UF-GZ / PA / Cu can significantly increase the residual carbon amount.

[0108] In order to further verify the microscopic morphology of the residual carbon layer, SEM test was performed on the UF surface after TG test. Fig. 9 As shown in the figure, the residual carbon layer formed after the combustion of UF has serious fragmentation, that is, a fragmented structure.

[0109] Compared with Comparative Example 1, it can be seen that although coating with UF can slightly reduce the degree of fragmentation of the residual carbon layer and slightly improve the flame retardancy, the residual carbon layer formed has no substantial change compared with NW and is also a fragmented structure;

[0110] Compared with Example 1, it can be seen that adding the GZ / PA / Cu flame retardant can transform the residual carbon layer from a broken structure to a dense structure.

[0111] In order to further prove the flame retardancy of UF, vertical burning test and limiting oxygen index test were performed.

[0112] Vertical burning test results are as follows Figure 7 As shown in Table 2, the open flame time after the first ignition of UF is 10.2s, and the open flame and flameless combustion time after the second ignition is 12.6s, with no dripping, indicating that UF passes the UL-94V-1 grade.

[0113] Compared with Comparative Example 1, it can be seen that coating with UF can improve the NW from no grade to UL-94V-1 grade, that is, coating with UF can improve the flame retardancy;

[0114] Compared with Example 1, it can be seen that adding GZ / PA / Cu flame retardant can improve the UL-94 grade from V-1 to V-0.

[0115] The limiting oxygen index test results are shown in Table 2. The limiting oxygen index of UF is 27.8%.

[0116] Compared with Comparative Example 1, it can be seen that coating with UF can increase the limiting oxygen index from 20.0% to 27.8%, that is, coating with UF can improve the flame retardancy;

[0117] Compared with Example 1, it can be seen that adding the GZ / PA / Cu flame retardant can increase the limiting oxygen index from 27.8% to 32.0%.

[0118] To further quantify the flame retardancy of NWs, cone calorimetry tests were performed. Figure 8 As shown, the HRR of UF reaches 70.90kW / m 2 ,

[0119] Compared with comparative example 1, the reduction in HRR achieved by coating with UF is 65.70%, that is, the heat release rate is reduced and the flame retardancy is improved;

[0120] Compared with Example 1, it can be seen that adding GZ / PA / Cu flame retardant can further reduce the HRR amplitude by 61.65%.

[0121] It can be seen from Example 1, Comparative Example 1 and Comparative Example 2 that the improvement of flame retardancy by coating with UF is essentially derived from the flame retardancy of UF itself, which is specifically manifested in that adding UF can only obtain an extremely low amount of residual carbon, and the obtained residual carbon layer is broken, that is, the quality is poor, which leads to the inability to effectively improve the flame retardancy;

[0122] The addition of GZ / PA / Cu flame retardants can significantly increase the amount of residual carbon and form a dense residual carbon layer at the same time, ultimately achieving the effect of significantly improving flame retardancy.

[0123] In order to demonstrate the effect of GZ / PA / Cu addition conditions, namely, the preparation process, on flame retardant properties, comparative example 3 is provided, in which GZ / PA / Cu is added by a conventional method to prepare a urea-formaldehyde resin blended guanazole-phytic acid-copper flame retardant resin coating.

[0124] It is explained that the addition of urea in step 2 is divided into three stages, wherein the adding method of Example 1 is to add GZ / PA / Cu flame retardant in step 2.2,

[0125] The conventional method is to add the flame retardant after the urea is added, that is, in step 2.3.

[0126] Comparative Example 3

[0127] A method for preparing a urea-formaldehyde resin blended guanazole-phytic acid-copper flame retardant resin coating in which GZ / PA / Cu is added in step 2.3. The steps not specifically stated are the same as those in Example 1, except that: in step 2, GZ / PA / Cu is not added in step 2.2, but GZ / PA / Cu is added in step 2.3. The obtained urea-formaldehyde resin blended guanazole-phytic acid-copper flame retardant resin coating is referred to as UF-GZ / PA / Cu-2.3.

[0128] In order to prove the technical effect of UF-GZ / PA / Cu-2.3 as a wood flame retardant coating, TG test was carried out. The test results are as follows Fig.11 As shown, the carbon residue of UF-GZ / PA / Cu-2.3 at 800.0°C is 13.2wt.%.

[0129] Compared with Comparative Example 1, it can be seen that the addition of UF-GZ / PA / Cu flame retardant in step 2.3 can only slightly increase the residual carbon content, with an increase of only 32.0%;

[0130] Compared with Example 1, it can be seen that the amount of residual carbon can be significantly increased when added in step 2.2.

[0131] The reason is that in the process of preparing GZ / PA / Cu, the pH value of GZ / PA / Cu is weakly acidic, and the acid-base environment of the solution in the three stages of step 2 is alkaline, acidic and alkaline respectively. Therefore, the technical scheme of Example 1, adding the weakly acidic GZ / PA / Cu in step 2.2 where the reaction environment is acidic, can improve the compatibility of the reactants, that is, improve the dispersibility of GZ / PA / Cu in the emulsion; on the contrary, the technical scheme of comparative example 3 will lead to a reduction in the dispersibility of GZ / PA / Cu in the emulsion, thereby directly affecting the final flame retardant properties.

[0132] In order to demonstrate the influence of metal elements on flame retardant properties, namely the role of Cu element, Comparative Examples 4, 5 and 6 are provided, in which guanazole-phytic acid metal salt flame retardant resin coatings are prepared by introducing Mg element, Ca element and Mn element into GZ / PA respectively.

[0133] Comparative Example 4

[0134] A guanazole-phytic acid metal salt flame retardant resin coating based on the Mg element. The steps not specifically stated are the same as those in Example 1, except that: in the step 1, the Mg element is introduced instead of the Cu element, specifically, 3.954g of magnesium hydroxide is added instead of 8.664g of copper hydroxide, and the material obtained in the step 1 is referred to as GZ / PA / Mg. In the subsequent step 2, GZ / PA / Mg is added instead of GZ / PA / Cu, and the material obtained in the step 2 is referred to as UF-GZ / PA / Mg.

[0135] In order to prove the GZ / PA / Mg composition, that is, the successful synthesis, XRD test was carried out. The test results are as follows Figure 1 As shown in Figure 2, GZ / PA / Mg contains the characteristic peaks of both Mg3P2 and Mg2P2O7. The test results show that the Mg element is successfully complexed with PA.

[0136] In order to prove the composition of GZ / PA / Mg, i.e., successful synthesis, FT-IR test was performed. The test results are shown in Figure 2 As shown, there is no substantial difference between GZ / PA / Mg and GZ / PA / Cu, that is, they both contain the characteristic peaks of -NH2, P=O and OPC, among which the characteristic peak of -NH2 belongs to GZ, and the characteristic peaks of P=O and OPC belong to PA.

[0137] The XRD and FT-IR test results proved that the GZ / PA / Mg flame retardant was successfully synthesized.

[0138] In order to prove the composition of UF-GZ / PA / Mg, i.e. the successful synthesis, FT-IR test was carried out. At the same time, since FT-IR test could not prove the existence of metal elements, EDS test was carried out on the UF-GZ / PA / Mg after combustion.

[0139] FT-IR test results are as follows Figure 3 As shown, there is no substantial difference between UF-GZ / PA / Mg and GZ / PA / Cu, that is, they both contain the characteristic peaks of -NH2, P=O and OPC, among which the characteristic peak of -NH2 belongs to GZ, and the characteristic peaks of P=O and OPC belong to PA.

[0140] EDS test results are as follows Fig.12As shown, the surface of the carbon layer of UF-GZ / PA / Mg after combustion contains not only N and P elements, but also Mg elements, among which N element comes from GZ, P element comes from PA, and Mg element comes from Mg(OH)2;

[0141] The results of FT-IR and EDS tests showed that UF-GZ / PA / Mg flame retardant coating was composed of GZ, PA and Mg elements, that is, UF-GZ / PA / Mg was successfully synthesized.

[0142] In order to prove the technical effect of UF-GZ / PA / Mg as a wood flame retardant coating, TG test was carried out. The test results are as follows Figure 5 As shown in Table 1, the decomposition temperature of UF-GZ / PA / Mg when decomposing 5% is 205.2°C. The temperature when the maximum decomposition rate is reached is 302.8°C, and the amount of carbon residue at 800.0°C is 27.3wt.%. Compared with Example 1, it can be seen that the increase in the amount of carbon residue by replacing Mg with Cu is negligible, which indicates that the type of metal element has no substantial effect on the amount of carbon residue.

[0143] In order to further verify the microstructure of the residual carbon layer, SEM test was performed on the surface of UF-GZ / PA / Mg after TG test. Fig.13 As shown, the residual carbon layer formed by UF-GZ / PA / Mg has many holes, that is, a dense residual carbon layer cannot be formed.

[0144] Compared with Comparative Example 2, it can be seen that the addition of GZ / PA / Mg can transform the residual carbon layer from a broken structure to a porous structure;

[0145] Compared with Example 1, it can be seen that replacing Mg with Cu can transform the residual carbon layer from a porous structure to a dense structure, that is, improve the quality of the residual carbon layer.

[0146] In order to further demonstrate the flame retardancy of UF-GZ / PA / Mg, vertical burning test and limiting oxygen index test were performed.

[0147] Vertical burning test results are as follows Figure 7 As shown in Table 2, the open flame time after the first ignition of UF-GZ / PA / Mg is 1.1s, and the open flame and flameless combustion time after the second ignition is 3.9s, and there is no dripping, which indicates that UF-GZ / PA / Mg passes the UL-94 V-0 grade. Compared with Example 1, it can be seen that the coated UF-GZ / PA / Cu and UF-GZ / PA / Mg can pass the UL-94 grade test, which indicates that the type of metal element has no substantial effect on the UL-94 grade.

[0148] The limiting oxygen index test results are shown in Table 2. The limiting oxygen index of UF-GZ / PA / Mg is 31.5%. Compared with Example 1, it can be seen that the improvement of the limiting oxygen index by replacing Mg with Cu is negligible, which indicates that the type of metal element has no substantial effect on the limiting oxygen index.

[0149] In order to further quantify the flame retardancy of UF-GZ / PA / Mg, cone calorimetry tests were performed. The test results are shown in Figure 8 As shown in Figure 2, the HRR of UF-GZ / PA / Mg reaches 39.20kW / m 2 Compared with Example 1, it can be seen that replacing Mg with Cu can significantly reduce HRR.

[0150] Through analysis and testing, it can be seen that the type of metal element has no substantial effect on the amount of residual carbon, UL-94 grade and limiting oxygen index; the role of the metal element Cu in the technical solution is to promote the formation of a dense structure in the residual carbon layer, thereby reducing HRR and ultimately improving flame retardant properties.

[0151] Comparative Example 5

[0152] A guanazole-phytic acid metal salt flame retardant resin coating based on the Mg element. The steps not specifically stated are the same as those in Example 1, except that: in the step 1, the Ca element is introduced instead of the Cu element, specifically 5.042g of calcium hydroxide is added instead of 8.664g of copper hydroxide, and the material obtained in the step 1 is referred to as GZ / PA / Ca. In the subsequent step 2, GZ / PA / Ca is added instead of GZ / PA / Cu, and the material obtained in the step 2 is referred to as UF-GZ / PA / Ca.

[0153] In order to prove the GZ / PA / Ca composition, that is, the successful synthesis, XRD test was carried out. The test results are as follows Figure 1 As shown, GZ / PA / Ca also contains the characteristic peak of Ca(PO3)2. The test results show that the Ca element is successfully complexed with PA.

[0154] In order to prove the composition of GZ / PA / Ca, i.e. the successful synthesis, FT-IR test was performed. The test results are as follows Figure 2 As shown, there is no substantial difference between GZ / PA / Ca and GZ / PA / Cu, that is, they both contain the characteristic peaks of -NH2, P=O and OPC, among which the characteristic peak of -NH2 belongs to GZ, and the characteristic peaks of P=O and OPC belong to PA.

[0155] The XRD and FT-IR test results proved that the GZ / PA / Ca flame retardant was successfully synthesized.

[0156] In order to prove the composition of UF-GZ / PA / Ca, i.e., the successful synthesis, FT-IR test was carried out. At the same time, since FT-IR test cannot prove the existence of metal elements, EDS test was carried out on the burned UF-GZ / PA / Ca.

[0157] FT-IR test results are as follows Figure 3 As shown, UF-GZ / PA / Ca has no substantial difference with GZ / PA / Cu, that is, it contains characteristic peaks of -NH2, P=O and OPC at the same time, among which the characteristic peak of -NH2 belongs to GZ, and the characteristic peaks of P=O and OPC belong to PA;

[0158] EDS test results are as follows Fig.14 As shown, the surface of the carbon layer of UF-GZ / PA / Ca after combustion contains not only N and P elements, but also Ca elements, among which N elements come from GZ, P elements come from PA, and Ca elements come from Ca(OH)2;

[0159] The results of FT-IR and EDS tests showed that UF-GZ / PA / Ca flame retardant coating was composed of GZ, PA and Ca elements, that is, UF-GZ / PA / Ca was successfully synthesized.

[0160] In order to prove the technical effect of UF-GZ / PA / Ca as a wood flame retardant coating, TG test was carried out. The test results are as follows Figure 5 As shown in Table 1, the decomposition temperature of UF-GZ / PA / Ca when decomposing 5% is 191.4°C. The temperature when the maximum decomposition rate is reached is 301.5°C, and the amount of residual carbon at 800.0°C is 29.4wt.%. Compared with Example 1, it can be seen that the increase in the amount of residual carbon by replacing Ca with Cu is negligible, which indicates that the type of metal element has no substantial effect on the amount of residual carbon.

[0161] In order to further verify the microstructure of the residual carbon layer, SEM test was performed on the surface of UF-GZ / PA / Ca after TG test. Fig.15 , the residual carbon layer formed by UF-GZ / PA / Ca has many holes, that is, it is impossible to form a dense residual carbon layer.

[0162] Compared with Comparative Example 2, it can be seen that the addition of GZ / PA / Ca can transform the residual carbon layer from a broken structure to a porous structure;

[0163] Compared with Example 1, it can be seen that replacing Ca with Cu can transform the residual carbon layer from a porous structure to a dense structure, that is, improve the quality of the residual carbon layer.

[0164] In order to further demonstrate the flame retardancy of UF-GZ / PA / Ca, vertical burning test and limiting oxygen index test were performed.

[0165] Vertical burning test results are as follows Figure 7 As shown in Table 2, the open flame time after the first ignition of UF-GZ / PA / Ca is 1.2s, and the open flame and flameless combustion time after the second ignition is 2.0s, and there is no dripping, which indicates that UF-GZ / PA / Ca passes the UL-94 V-0 grade. Compared with Example 1, it can be seen that the coated UF-GZ / PA / Cu and UF-GZ / PA / Ca can pass the UL-94 grade test, which indicates that the type of metal element has no substantial effect on the UL-94 grade.

[0166] The limiting oxygen index test results are shown in Table 2. The limiting oxygen index of UF-GZ / PA / Ca is 30.0%. Compared with Example 1, it can be seen that the improvement of the limiting oxygen index by replacing Ca with Cu is negligible, which shows that the type of metal element has no substantial effect on the limiting oxygen index.

[0167] In order to further quantify the flame retardancy of UF-GZ / PA / Ca, cone calorimetry tests were performed. Figure 8 As shown in Figure 2, the HRR of UF-GZ / PA / Ca reaches 43.30kW / m 2 Compared with Example 1, it can be seen that replacing Ca with Cu can significantly reduce HRR.

[0168] Comparative Example 6

[0169] A guanazole-phytic acid metal salt flame retardant resin coating based on the Mg element. The steps not specifically stated are the same as those in Example 1, except that: in the step 1, the Mn element is introduced instead of the Cu element, specifically, 5.224g of manganese dioxide is added instead of 8.664g of copper hydroxide, and the material obtained in the step 1 is referred to as GZ / PA / Mn. In the subsequent step 2, GZ / PA / Mn is added instead of GZ / PA / Cu, and the material obtained in the step 2 is referred to as UF-GZ / PA / Mn.

[0170] In order to prove the GZ / PA / Mn composition, i.e., successful synthesis, XRD test was performed. The test results are shown in Figure 1 As shown in Figure 2, GZ / PA / Mn also contains the characteristic peaks of Mn(PO3)3. The test results show that the Mn element is successfully complexed with PA.

[0171] In order to prove the composition of GZ / PA / Mn, i.e. the successful synthesis, FT-IR test was performed. The test results are as follows Figure 2 As shown, there is no substantial difference between GZ / PA / Mn and GZ / PA / Cu, that is, they both contain the characteristic peaks of -NH2, P=O and OPC, among which the characteristic peak of -NH2 belongs to GZ, and the characteristic peaks of P=O and OPC belong to PA.

[0172] The XRD and FT-IR test results proved that the GZ / PA / Mn flame retardant was successfully synthesized.

[0173] In order to prove the composition of UF-GZ / PA / Mn, i.e. the successful synthesis, FT-IR test was carried out. At the same time, since FT-IR test could not prove the existence of metal elements, EDS test was carried out on the UF-GZ / PA / Mn after combustion.

[0174] FT-IR test results are as follows Figure 3 As shown, UF-GZ / PA / Mn has no substantial difference with GZ / PA / Cu, that is, it contains characteristic peaks of -NH2, P=O and OPC at the same time, among which the characteristic peak of -NH2 belongs to GZ, and the characteristic peaks of P=O and OPC belong to PA;

[0175] EDS test results are as follows Fig.16 As shown, the surface of the carbon layer of UF-GZ / PA / Mn after combustion contains not only N and P elements, but also Mn elements, among which N elements come from GZ, P elements come from PA, and Mn elements come from MnO2;

[0176] The results of FT-IR and EDS tests showed that UF-GZ / PA / Mn flame retardant coating was composed of GZ, PA and Mn elements, that is, UF-GZ / PA / Mn was successfully synthesized.

[0177] In order to prove the technical effect of UF-GZ / PA / Mn as a wood flame retardant coating, TG test was carried out. The test results are as follows Figure 5 As shown in Table 1, the decomposition temperature of UF-GZ / PA / Mn when decomposing 5% is 184.0°C. The temperature when the maximum decomposition rate is reached is 304.1°C, and the amount of carbon residue at 800.0°C is 26.0wt.%. Compared with Example 1, it can be seen that the increase in the amount of carbon residue by replacing Mn with Cu is negligible, which indicates that the type of metal element has no substantial effect on the amount of carbon residue.

[0178] In order to further verify the microstructure of the residual carbon layer, SEM test was performed on the surface of UF-GZ / PA / Mn after TG test. Fig.17 , the residual carbon layer formed by UF-GZ / PA / Mn has many holes, that is, it is impossible to form a dense residual carbon layer.

[0179] Compared with Comparative Example 2, it can be seen that the addition of GZ / PA / Mn can transform the residual carbon layer from a broken structure to a porous structure;

[0180] Compared with Example 1, it can be seen that replacing Ca with Cu can transform the residual carbon layer from a porous structure to a dense structure, that is, improve the quality of the residual carbon layer.

[0181] In order to further prove the flame retardancy of UF-GZ / PA / Mn, vertical burning test and limiting oxygen index test were carried out.

[0182] Vertical burning test results are as follows Figure 7 As shown in Table 2, the open flame time of UF-GZ / PA / Mn after the first ignition is 1.7s, and the open flame and flameless combustion time after the second ignition is 1.8s, and there is no dripping, which indicates that UF-GZ / PA / Mn passes the UL-94V-0 grade. Compared with Example 1, it can be seen that the coated UF-GZ / PA / Cu and UF-GZ / PA / Mn can pass the UL-94 grade test, which indicates that the type of metal element has no substantial effect on the UL-94 grade.

[0183] The limiting oxygen index test results are shown in Table 2. The limiting oxygen index of UF-GZ / PA / Mn is 29.0%. Compared with Example 1, it can be seen that the improvement of the limiting oxygen index by replacing Mn with Cu is negligible, which shows that the type of metal element has no substantial effect on the limiting oxygen index.

[0184] In order to further quantify the flame retardancy of UF-GZ / PA / Mn, cone calorimetry tests were performed. The test results are shown in Figure 8 As shown in Figure 2, the HRR of UF-GZ / PA / Mn reaches 47.00kW / m 2 Compared with Example 1, it can be seen that replacing Mn with Cu can significantly reduce HRR.

[0185] The following conclusions can be drawn from Example 1, Comparative Example 4, Comparative Example 5 and Comparative Example 6:

[0186] 1. The type of metal element has no substantial effect on the carbon residue, UL-94 grade and limiting oxygen index;

[0187] 2. Metal elements have a significant impact on the quality of the carbon layer formed after combustion and the HRR value. The reason is that the role of the metal element Cu in the technical solution is to promote the formation of a dense structure in the residual carbon layer, thereby reducing HRR and improving the flame retardant properties, while other metal elements Mg, Ca and Mn can only form a residual carbon layer with a porous structure, which cannot effectively improve the flame retardant properties.

Claims

1. A urea-formaldehyde resin blended guanazole-phytic acid-copper flame retardant resin coating, characterized in that: The urea-formaldehyde resin blended guanazole-phytic acid-copper flame retardant UF-GZ / PA / Cu was prepared by combining guanazole-phytic acid-copper flame retardant GZ / PA / Cu with urea and formaldehyde as main raw materials, using dioctyl phthalate DOP as plasticizer and tannic acid TA as curing agent through three-stage reaction.

2. The urea-formaldehyde resin blended guanazole-phytic acid-copper flame retardant resin coating according to patent claim 1 is characterized in that: The GZ / PA / Cu is prepared by complexing reaction using 3,5-diamino-1,2,4-triazole GZ, phytic acid PA and copper source as bio-based flame retardant ingredients as raw materials; The obtained GZ / PA / Cu contains Cu4O(PO4)2, CuO, -NH2, P=O and OPC.

3. The urea-formaldehyde resin blended guanazole-phytic acid-copper flame retardant resin coating according to patent claim 1 is characterized in that: The temperature at which the UF-GZ / PA / Cu decomposes to 5% by mass is 195.5±2.1°C, the temperature at which the maximum decomposition rate is reached is 300.6±1.5°C, and the residual carbon content at 800°C is 29.8±2.5wt.%; When the addition amount of GZ / PA / Cu is 1wt.%, a dense residual carbon layer is formed.

4. A method for preparing a urea-formaldehyde resin blended guanazole-phytic acid-copper flame retardant resin coating, characterized in that The following steps are involved: Step 1, preparation of GZ / PA / Cu flame retardant, first, dissolving 3,5-diamino-1,2,4-triazole GZ in water to obtain a GZ solution, then, under certain conditions, adding a phytic acid PA solution dropwise to the GZ solution to obtain a GZ / PA solution, and finally, under certain conditions, adding copper hydroxide to the GZ / PA solution to react, after the reaction is completed, filtering, washing, drying, and grinding the obtained product into powder to obtain a guanazole-phytic acid-copper flame retardant, referred to as GZ / PA / Cu; The washing condition is that the pH of the washing solution is 5.0-6.0; The drying conditions are as follows: drying temperature is 80°C and drying time is 24h; Step 2, preparation of modified urea-formaldehyde resin emulsion UF, first, adding a certain amount of sodium hydroxide solution to the formaldehyde solution to adjust the pH value of the solution to obtain solution A, and then, under certain conditions, adding urea, GZ / PA / Cu and other raw materials in three stages to prepare urea-formaldehyde resin blended guanazole-phytic acid-copper flame retardant resin coating, referred to as UF-GZ / PA / Cu.

5. The preparation method according to claim 4, characterized in that: In the step 1, the mass ratio of GZ, PA and Cu(OH)2 is 1:6:1; In step 1, the conditions for preparing the GZ / PA solution are: stirring temperature of 70° C., stirring speed of 500-600 rpm, stirring time of 30 min, and drop rate of 0.5 drops / s; In the step 1, the reaction conditions are: reaction temperature is 90° C., and reaction time is 3 h.

6. The preparation method according to claim 4, characterized in that: In the step 2, the mass ratio of the total added amount of GZ / PA / Cu, formaldehyde and urea obtained in step 1 is 1:100:57; In step 2, the conditions for preparing solution A are to adjust the pH value of the solution to 8.0-8.5; In step 2, the conditions for adding urea are: a stirring speed of 400-500 rpm and a reaction temperature of 90°C.

7. The preparation method according to claim 4, characterized in that: In step 2, the three stages of adding urea are specifically: Step 2.1 is to add the first stage urea under a certain temperature condition, and continue stirring for a certain stirring time after the addition is completed; Step 2.2 is, under a certain temperature condition, firstly add acetic acid solution to adjust the pH value of the solution, then add the second stage urea, and finally add GZ / PA / Cu. After the addition is completed, continue stirring for a certain stirring time until the reaction end point is reached; The endpoint of the second stage reaction is determined by the following sign: a drop of the solution is dropped into 30°C water, and the dropped solution condenses in the water without dispersing; Step 2.3 is to first add sodium hydroxide solution to adjust the pH value under a certain temperature condition, and then add urea from the third stage. After the addition is completed, stir under certain conditions to obtain UF-GZ / PA / Cu.

8. The preparation method according to claim 7, characterized in that: In the step 2.1, the amount of urea added is 64.9% of the total amount of urea, the temperature in step 2.1 is 90° C., and the stirring time is continued for 30 minutes; In the step 2.2, the amount of urea added is 21.6% of the total amount of urea, the pH value of the solution is adjusted to 4.5-5.0, the temperature of step 2.2 is 90° C., and the stirring time is continued for 15 minutes; In the step 2.3, the amount of urea added is 13.3% of the total amount of urea, the pH value of the solution is adjusted to 7.5-8.0, the temperature of step 2.2 is 90° C. when adjusting the pH value, and after the pH value is adjusted, the temperature is adjusted to 70° C., and the stirring time is 30-40 minutes.

9. A urea-formaldehyde resin blended guanazole-phytic acid-copper flame retardant resin coating, characterized in that: When used as a flame retardant coating for wood, it has flame retardant properties and can form a continuous and dense residual carbon layer after combustion; in the UL-94 grade test, it passes the UL-94V-0 grade test.

10. A urea-formaldehyde resin blended guanazole-phytic acid-copper flame retardant resin coating, characterized in that: When used as a wood flame retardant coating, the heat release rate HRR is 25.38±1.25kW / m in the cone calorimetry test. 2 .

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