Environment-friendly flame-retardant interface agent and preparation method thereof

Abstract

The invention discloses an environment-friendly flame-retardant interface agent and a preparation method thereof, and belongs to the technical field of artificial boards. The interface agent comprises the following components in parts by weight: 10-25 parts of magnesium sulfate, 2-8 parts of polyvinyl alcohol, 30-50 parts of magnesium chloride, 0.1-2 parts of borax, 1-5 parts of industrial starch, 80-120 parts of magnesium oxide and 120-160 parts of water. The preparation method comprises the following steps: dissolving polyvinyl alcohol in water, and adding magnesium sulfate to obtain a first preparation; mixing magnesium chloride, borax and industrial starch, and adding water in batches to obtain a second preparation; adding the first preparation into the second preparation and mixing; and finally, adding magnesium oxide in batches to obtain a thick pasty interface agent. The magnesium sulfate replaces part of magnesium chloride to solve the problem of moisture absorption and halogenation, the polyvinyl alcohol and the borax synergistically enhance interface bonding, and the starch improves the stability of the system. The interface agent has excellent adhesiveness, water resistance and flame retardance, is suitable for interface enhancement between wood and magnesium oxychloride cement, and solves the technical problems of insufficient interface bonding strength, easy efflorescence and the like in the prior art.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of artificial board, in particular to an environment-friendly flame-retardant interface agent and a preparation method thereof. BACKGROUND

[0002] The aldehyde-based adhesive commonly used in the wood industry in China and its products release formaldehyde during use, pollute the living environment, and have poor thermal stability and flame retardant properties. Compared with aldehyde-based organic adhesives, magnesium-based adhesives have the characteristics of non-toxic, environmental protection, abundant resources, high bonding strength, good weather resistance, good flame retardancy, etc.

[0003] Magnesium-based adhesives are products prepared by stirring, shaping, curing and other processes according to certain proportions of magnesium oxide, magnesium chloride (or magnesium sulfate) and water as basic combination materials, and adding filling and modifying materials (organic or inorganic fiber materials, fly ash, slag powder and other materials) according to different purposes. The magnesium-based adhesive prepared from magnesium oxide and magnesium chloride is called magnesium oxychloride adhesive.

[0004] In the preparation process of magnesium-based adhesives, different raw material proportions and preparation processes have significant effects on mechanical properties, micro-morphology and hydration reaction process. Magnesium oxychloride cement is synthesized by the reaction of MgO-MgCl2-H2O three-phase system, and the product mainly includes 5-phase and / or 3-phase. The molar ratio of MgO / MgCl2, the concentration of magnesium chloride solution, the solidification temperature and the activity of magnesium oxide all affect the performance and structure of magnesium oxychloride cement. The component proportion of the existing magnesium oxychloride adhesive lacks systematic optimization, and it is difficult to achieve overall performance improvement by simply relying on the binary system of magnesium chloride and magnesium oxide, especially in the aspect of bonding strength, which is not ideal, limiting its application effect as an interface agent.

[0005] Modifying magnesium oxychloride cement by adding modifiers is the most widely used improvement method at present. The types of modifiers include acids (phosphoric acid, citric acid), salts (phosphate, silicate), fly ash and other mineral admixtures, and other cementitious materials. Different types of modifiers mainly work through: (1) stabilizing the hydration products of the magnesium oxychloride cement system to generate more water-stable gel-like five-phase; (2) constructing a water-blocking film on the crystal surface to weaken the water infiltration of magnesium oxychloride cement; (3) filling the internal pores of magnesium oxychloride cement to form a dense structure while preventing water molecules from directly contacting the five-phase crystals of magnesium oxychloride cement, thereby improving the water resistance of magnesium oxychloride cement. However, these modification schemes mostly use a single type of inorganic modifier, lack systematic research on organic-inorganic composite modification, and fail to fully exert the synergistic effect of the excellent adhesion of organic materials and the excellent flame-retardant water resistance of inorganic materials, resulting in difficulty in achieving an ideal balance in adhesion, water resistance and flame retardancy.

[0006] In addition, the existing magnesium oxychloride adhesive still has the phenomenon of moisture absorption and halogen return, that is, the surface appears white frost due to the precipitation of chloride ions, which not only affects the appearance quality, but also may cause corrosion to metal components, and the water resistance needs to be further improved.

[0007] Therefore, it is urgent to develop an environmentally friendly flame-retardant interface agent that significantly enhances adhesion while having excellent water resistance and flame retardance to solve the above technical problems. SUMMARY

[0008] Based on the problems in the background art, the present application provides an environmentally friendly flame-retardant interface agent and a preparation method thereof, to solve the technical problems of the existing magnesium oxychloride cement adhesive formula not being optimized enough, poor toughness, easy moisture absorption and halogen return, and insufficient interfacial bonding strength with wood, and to achieve the preparation of an interface agent with high strength, good water resistance, environmental protection and flame retardance.

[0009] The present application is implemented by the following technical solutions:

[0010] The present application discloses an environmentally friendly flame-retardant interface agent, comprising the following components by weight: magnesium sulfate 10-25 parts, polyvinyl alcohol 2-8 parts, magnesium chloride 30-50 parts, borax 0.1-2 parts, industrial starch 1-5 parts, magnesium oxide 80-120 parts, and water 120-160 parts.

[0011] Further, the components include the following by weight: magnesium sulfate 15 parts, polyvinyl alcohol 5 parts, magnesium chloride 40 parts, borax 1 part, industrial starch 3 parts, magnesium oxide 100 parts, and water 140 parts.

[0012] The present application discloses a preparation method of the environmentally friendly flame-retardant interface agent, comprising the following steps:

[0013] S1. Dissolve polyvinyl alcohol in water, then add magnesium sulfate and mix uniformly to obtain a first preparation;

[0014] S2. Mix magnesium chloride, borax and industrial starch uniformly to obtain a mixture;

[0015] S3. Add the remaining water to the mixture in batches, stir uniformly to obtain a second preparation;

[0016] S4. Add the first preparation to the second preparation, stir uniformly to obtain a mixed solution;

[0017] S5. Add magnesium oxide to the mixed solution in batches, mix uniformly to obtain a thick paste-shaped environmentally friendly flame-retardant interface agent.

[0018] Further, in step S1, the polyvinyl alcohol is dissolved in water at 80-90℃, and then the temperature is lowered to below 60℃ before adding magnesium sulfate.

[0019] Polyvinyl alcohol typically dissolves at 80-90℃, and the dissolution process is relatively slow; the larger the molecular weight, the less easily it dissolves. MgSO4 ionizes at high temperatures to produce Mg... 2+ and It is a strong hydration ion, which will compete with polyvinyl alcohol for free water, causing it to dehydrate and curl up to form gel particles. Therefore, MgSO4 should be added after cooling.

[0020] The purpose of adding polyvinyl alcohol in this invention is that polyvinyl alcohol has a high elastic modulus and good interfacial adhesion. Its long chain has strong hydrogen bond interaction with wood and the good fluidity of the long chain molecules improves the binding and permeability of the system with wood.

[0021] The purpose of adding magnesium sulfate is that, in magnesium-based cementitious systems, magnesium chloride dominates the formation of the 518 phase, but Cl... - Easily soluble, reducing water resistance and causing efflorescence; replacing 20-30% magnesium chloride with magnesium sulfate reduces the total amount of soluble ions and reduces moisture absorption and efflorescence; excessive addition of magnesium sulfate will form an unstable 318 phase, affecting the performance of the hydration reaction products.

[0022] Furthermore, in step S1, water accounts for 55-60% of the total water volume, and in step S3, water accounts for 40-45% of the total water volume.

[0023] Furthermore, in step S2, the magnesium chloride, borax, and industrial starch are mixed evenly without adding water. This involves mixing the brine raw materials and fillers evenly. If water is added first to make the magnesium chloride and water brine, and then borax and starch are added later, it is easy for the mixture to clump together. Uneven mixing will affect the coagulation process of the gelling material.

[0024] The purpose of adding borax is that it is often used as a slow-release agent to delay the setting time, and it can cross-link with polyvinyl alcohol to form a network structure to enhance the mechanical properties of materials, such as elastic modulus and viscosity, making it particularly suitable for hydrogel preparation; however, excessive addition of borax may reduce compressive strength.

[0025] The purpose of adding starch is that, as a water-absorbing polymer, starch can act as a buffer in magnesium oxychloride slurry to reduce solid-liquid separation and achieve the construction of a stable system.

[0026] Furthermore, in step S3, the stirring speed is ≤20 r / min, and the stirring time is 15-30 min.

[0027] The purpose of step S3 is to ensure that the material is fully dissolved, accelerate the dissolution while minimizing air bubbles and voids in the solution. Since the dissolution of magnesium chloride is an exothermic reaction, the process of dissolving in small amounts multiple times and stirring slowly is to control the temperature from becoming too high and causing the starch to gelatinize and clump together.

[0028] Further, the first preparation is cooled to room temperature in step S4, and then added into the second preparation, the stirring speed is less than or equal to 20 r / min, and the stirring time is 8-15 min.

[0029] Further, the mixing time of the magnesium oxide into the mixed solution in step S5 is 20-30 min.

[0030] The initial setting time of the magnesium oxide and the mixed magnesium oxide and water is generally within 60 min, and the mixed magnesium oxide and water is mixed within 30 min, so that the mixture is kept in a thick paste or cream state, and then used as an interface agent.

[0031] The third aspect of the present application discloses the application of the environment-friendly flame-retardant interface agent in the preparation of the composite artificial board.

[0032] Further, the environment-friendly flame-retardant interface agent is coated between the board core layer and the flame-retardant layer.

[0033] The beneficial effects of the present application are as follows:

[0034] 1. The present application is a mixed interface agent, which is combined with organic and inorganic cementing materials, utilizes the adhesion of the organic material and the flame retardance and water resistance of the inorganic material, and is mainly used for enhancing the bonding strength of the organic-inorganic interface between the wood and the magnesium oxychloride cement, so that the different density board core and the flame-retardant surface layer are firmly combined, and have the characteristics of environment-friendly flame retardance, water resistance and the like.

[0035] 2. The interface agent of the present application has simple and reasonable manufacturing procedures, fully utilizes the characteristics of different materials, simplifies the process flow, saves the working time, and improves the production efficiency.

[0036] 3. The organic and inorganic fillers added in the present application are low in price, and the optimal amount is controlled, so that the raw material cost is saved, and the batch production is suitable. BRIEF DESCRIPTION OF DRAWINGS

[0037] The accompanying drawings are used to further explain the present application, and constitute a part of the specification, and are used to explain the present application together with the embodiments of the present application, and do not constitute a limitation on the present application. In the drawings:

[0038] Figure 1 It is a structural schematic diagram of the composite artificial board of the present application;

[0039] Figure 2 It is a process flow diagram for preparing the environment-friendly flame-retardant interface agent of the present application. DETAILED DESCRIPTION

[0040] The technical solutions of the present application are further described below in combination with specific embodiments, but the protection scope of the present application is not limited to the following embodiments.

[0041] Embodiments 1-9

[0042] The Examples 1-9 determine the optimal ratio of magnesium cementitious system hydration reaction.

[0043] The specific preparation steps of the test sample are as follows: according to the data in Table 1, a certain weight part of magnesium sulfate is made into a first preparation with 80 parts of water, and a certain part of magnesium chloride is made into a second preparation with 60 parts of water. After the first preparation and the second preparation are mixed uniformly, 100 parts of magnesium oxide are added batch by batch and stirred for 30 min, then poured into a mold and sealed for curing at room temperature for 24 h, and then the magnesium oxychloride cement sample is obtained after indoor curing at room temperature for 24 h. The sample is analyzed for performance, and the corresponding test standards are: GB / T 17671-2021 "Cement mortar strength test method"; JC / T568-2023 "Magnesium oxychloride cement plate"; the results are shown in Tables 1 and 2.

[0044] Table 1 Effect of magnesium chloride and magnesium sulfate ratio on performance of magnesium oxychloride cement in Examples 1-9

[0045]

[0046] Table 2 Variance analysis of test data in Examples 1-9

[0047]

[0048] The compressive strength reflects the strength of the mechanical properties of magnesium oxychloride cement, and the softening coefficient reflects the strength of the water resistance. From the data in Tables 1 and 2, it can be concluded that the optimal ratio is 15 parts of magnesium sulfate and 40 parts of magnesium chloride. The initial setting time is 42 minutes, which is at a medium level, but it is slightly faster for actual production, and subsequent adjustments can be made according to production needs. The double factors have a significant effect on the compressive strength and the softening coefficient. Replacing magnesium chloride with an appropriate amount of magnesium sulfate can significantly improve the water resistance of the material, and excessive addition of magnesium sulfate will not further improve the performance, but will easily lead to loose material structure and performance decline. If there is excess magnesium chloride in the magnesium oxychloride cement, it will cause the cement surface to appear moisture absorption and halogen return, and other phenomena; and if there is excess magnesium oxide in the system, it will absorb water in the air to form Mg(OH)2, thereby causing the magnesium oxychloride cement sample to expand and even crack.

[0049] Examples 10-18

[0050] Examples 10-18 test the effect of polyvinyl alcohol and borax on the performance of the interfacial agent.

[0051] The specific preparation steps of the test sample are as follows: according to the data in Table 3, a certain amount of polyvinyl alcohol is dissolved in 80 parts of water at 85°C, 15 parts of magnesium sulfate is added when the temperature is lowered to below 60°C to prepare a first preparation, 40 parts of magnesium chloride is mixed with a certain amount of borax and then added to 60 parts of water to prepare a second preparation, the first preparation and the second preparation are mixed uniformly, then 100 parts of magnesium oxide is added in batches and stirred for 30 min, then poured into a mold, sealed and cured at room temperature for 24 h, and then cured at room temperature for 24 h in the room to obtain a magnesium oxychloride cement sample (used to measure the compressive strength, softening coefficient and initial setting time).

[0052] The specific preparation steps of the composite board sample are as follows: a certain amount of polyvinyl alcohol is dissolved in 80 parts of water at 85°C, 15 parts of magnesium sulfate is added when the temperature is lowered to below 60°C to prepare a first preparation, 40 parts of magnesium chloride is mixed with a certain amount of borax and then added to 60 parts of water to prepare a second preparation, the first preparation and the second preparation are mixed uniformly, then 100 parts of magnesium oxide is added in batches and stirred for 30 min, then poured into a mold, sealed and cured at room temperature for 24 h, and then cured at room temperature for 24 h in the room to obtain a composite board sample (such as shown in Figure 1 The specific preparation steps of the composite board sample are as follows: a certain amount of polyvinyl alcohol is dissolved in 80 parts of water at 85°C, 15 parts of magnesium sulfate is added when the temperature is lowered to below 60°C to prepare a first preparation, 40 parts of magnesium chloride is mixed with a certain amount of borax and then added to 60 parts of water to prepare a second preparation, the first preparation and the second preparation are mixed uniformly, then 100 parts of magnesium oxide is added in batches and stirred for 30 min, then poured into a mold, sealed and cured at room temperature for 24 h, and then cured at room temperature for 24 h in the room to obtain a composite board sample (such as shown in

[0053] The performance of the sample is analyzed, and the relevant standards are JC / T 568-2023 “Magnesium Oxychloride Cement Board” GB / T 17671-2021 “Cement Mortar Strength Test Method” GB / T 17657-2022 “Artificial Board and Faced Artificial Board Physical and Chemical Performance Test Method” The final results are shown in Tables 3 and 4.

[0054] Table 3 Influence of polyvinyl alcohol and borax in group 10-18 on the performance of the interfacial agent

[0055]

[0056] Table 4 Variance analysis of the adhesive layer shear strength data of examples 10-18

[0057]

[0058] From the results of Table 3 and Table 4, it can be seen that the double factors have a significant effect on the adhesive layer shear strength, and have a positive effect on the improvement of the compressive strength and softening coefficient, but the improvement range is smaller. The reason is that polyvinyl alcohol is a linear long chain containing a large number of hydroxyl groups. After combining with magnesium oxide, there are a large number of long dangling chains, which are beneficial to the penetration on the porous hydrophilic wood surface. The hydroxyl groups (-OH) on the surface of PVA fibers form hydrogen bonds with cellulose / hemicellulose of wood components, thereby enhancing the interfacial bonding strength between the wood and the wood. Borax is commonly used as a retarder, but excessive addition of borax will affect the hydration reaction and reduce the compressive strength. Therefore, the best ratio is polyvinyl alcohol 5 parts and borax 1 part, the adhesive layer shear strength of the interfacial agent is high, the material toughness is good, and the strength and water resistance of the magnesium oxychloride cement are improved less. Due to the retarding effect of borax, the initial setting time is 60 minutes, which is at a moderate level.

[0059] Examples 19-22

[0060] Examples 19-22 test the effect of starch on the performance of the interfacial agent.

[0061] The specific preparation steps of the test sample are as follows: according to the data in Table 5, 5 parts of polyvinyl alcohol are dissolved in 80 parts of water at 85°C, and 15 parts of magnesium sulfate are added to the first preparation after cooling to below 60°C. 60 parts of water are added to the second preparation after mixing 40 parts of magnesium chloride, 1 part of borax and a certain number of starches uniformly. After mixing the first preparation and the second preparation uniformly, 100 parts of magnesium oxide are added in batches and stirred for 30 minutes. Then, the mixture is poured into a mold, sealed at room temperature and cured for 24 hours. After indoor curing at room temperature for 24 hours, the magnesium oxychloride cement sample (used to determine the softening coefficient) is obtained.

[0062] The specific preparation steps of the test sample are as follows: according to the data in Table 5, 5 parts of polyvinyl alcohol are dissolved in 80 parts of water at 85°C, and 15 parts of magnesium sulfate are added to the first preparation after cooling to below 60°C. 60 parts of water are added to the second preparation after mixing 40 parts of magnesium chloride, 1 part of borax and a certain number of starches uniformly. After mixing the first preparation and the second preparation uniformly, 100 parts of magnesium oxide are added in batches and stirred for 30 minutes. Then, the mixture is poured into a mold, sealed at room temperature and cured for 24 hours. After indoor curing at room temperature for 24 hours, the magnesium oxychloride cement sample (used to determine the softening coefficient) is obtained.

[0063] The performance of the sample is analyzed, and the relevant standards are JC / T 568-2023 "Magnesium Oxychloride Cement Board" and GB / T 17657-2022 "Artificial Board and Faced Artificial Board Physical and Chemical Performance Test Method". The final results are shown in Table 5.

[0064] Table 5 Effect of starch on the performance of the interfacial agent in Examples 19-22

[0065] Table 5 Effect of starch on the performance of the interfacial agent in Examples 19-22

[0066] From the data in Table 5, it can be seen that the optimal ratio of starch is 3 parts, and the appropriate amount of starch can promote the hydration of MgO and the formation of 5-phase. Due to the hydrophilicity of starch, adding an excessive amount of starch will cause the water resistance to decrease. Therefore, when 5 parts of starch are added, the interfacial agent's glue layer shear strength and softening coefficient both decrease. The initial adhesion is of great significance to the manufacturing process of the artificial board, and too low initial adhesion is prone to cause slip dislocation during assembly. When the amount of starch is 3 parts, the initial adhesion of the interfacial agent is significantly improved to 5.33 N / mm, which makes it have good adhesion on the surface of wood and makes the glue layer shear strength reach the highest value. The performance data of the interfacial agent reaches the inflection point.

[0067] Examples 23-26

[0068] Examples 23-26 of the present embodiment test the influence of different mixing methods on the performance of the interfacial agent.

[0069] The optimal ratio of magnesium sulfate 15 parts, polyvinyl alcohol 5 parts, magnesium chloride 40 parts, borax 1 part, industrial starch 3 parts, magnesium oxide 100 parts, and water 140 parts is selected.

[0070] The test sample process is as follows:

[0071] A polyvinyl alcohol, B water, C magnesium sulfate, D magnesium chloride, E borax, F industrial starch, and G magnesium oxide.

[0072] Example 23:

[0073] The materials are mixed in the order of the present application, as shown in Figure 2 , A+B+C=first preparation, D+E+F+B=second preparation, first preparation+second preparation+G=interfacial agent.

[0074] Example 24:

[0075] Polyvinyl alcohol is added after the magnesium sulfate solution, A+B+C=first preparation, B+C+D+E+F=second preparation, second preparation+G=third preparation, third preparation+first preparation=interfacial agent.

[0076] Example 25:

[0077] The conventional magnesium oxychloride cement is mixed, A+B+C+D+E+F=first preparation, first preparation+G=interfacial agent.

[0078] Example 26:

[0079] All solid raw materials are uniformly mixed, and then water is added, A+C+D+E+F+G=mixture, mixture+B=interfacial agent.

[0080] The sample was subjected to performance analysis, and the relevant standards were JC / T 568-2023 "Magnesium oxychloride cement plate" and GB / T 17657-2022 "Test methods for physical and chemical properties of wood-based panels and veneered wood-based panels". The final results are shown in Table 6.

[0081] Table 6: Influence of different mixing methods on the performance of interface agent in groups 23-26

[0082]

[0083] As can be seen from the results in Table 6, group 23 is the best, the reaction between the components is reasonable, the physical and chemical properties of the interface agent are improved, and the dispersion is the lowest, which is suitable for industrial production; groups 24 and 25 have large fluctuations, the wrong reaction combination leads to insufficient reaction of the components, the organic-inorganic system is not fully combined, and the dispersion is high, which is not suitable for industrial production; group 26 is the worst, dry mixing of materials leads to mutual wrapping and clumping of organic and inorganic materials, the hydration mechanism is severely damaged, the product quality is extremely unstable, and industrial application is impossible.

[0084] The final performance detection results of the interface agent (group 23) of the present application are shown in Table 7.

[0085] Table 7: Performance detection results of the interface agent of the present application

[0086]

[0087] Finally, it should be noted that the above-described examples only express several embodiments of the present application and do not limit the present application. Any modifications, equivalent replacements, improvements, etc. made by those skilled in the art without departing from the concept of the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. An environmentally friendly flame retardant interfacial agent, characterized in that, The components include the following weight parts: magnesium sulfate 10-25 parts, polyvinyl alcohol 2-8 parts, magnesium chloride 30-50 parts, borax 0.1-2 parts, industrial starch 1-5 parts, magnesium oxide 80-120 parts, and water 120-160 parts.

2. The environmentally friendly flame retardant interfacial agent according to claim 1, wherein The components include the following weight parts: magnesium sulfate 15 parts, polyvinyl alcohol 5 parts, magnesium chloride 40 parts, borax 1 part, industrial starch 3 parts, magnesium oxide 100 parts, and water 140 parts.

3. A process for the preparation of an environmentally friendly flame retardant interfacial agent as claimed in claim 1 or 2, characterized in that, The method comprises the following steps: S1. Dissolve polyvinyl alcohol in water, then add magnesium sulfate, mix well to obtain a first preparation; S2. Mix magnesium chloride, borax and industrial starch well to obtain a mixture; S3. Add the remaining water to the mixture in batches, mix well to obtain a second preparation; S4. Add the first preparation to the second preparation, mix well to obtain a mixed solution; S5. Add magnesium oxide to the mixed solution in batches, mix well to obtain a thick paste-shaped environment-friendly flame-retardant interface agent.

4. The production method according to claim 3, characterized by, In step S1, the polyvinyl alcohol is dissolved in water at 80-90℃, then the temperature is lowered to below 60℃ before adding magnesium sulfate.

5. The preparation method according to claim 3, characterized in that, In step S1, the water accounts for 55-60% of the total water amount, and in step S3, the water accounts for 40-45% of the total water amount.

6. The preparation method according to claim 3, characterized in that, In step S3, the stirring speed is ≤20 r / min, and the stirring time is 15-30 min.

7. The preparation method according to claim 3, characterized in that, In step S4, the first preparation is cooled to room temperature before being added to the second preparation, the stirring speed is ≤20 r / min, and the stirring time is 8-15 min.

8. The preparation method according to claim 3, characterized in that, In step S5, the mixing time of adding magnesium oxide to the mixed solution is 20-30 min.

9. Use of the environment-friendly flame-retardant interface agent according to claim 1 or 2 in the preparation of composite wood-based panels.

10. Use according to claim 9, characterized in that, The environment-friendly flame-retardant interface agent is coated between the core layer and the flame-retardant layer.

Images