High-toughness phenolic resin-based composite refractory plate and preparation method thereof

Abstract

The invention discloses a high-toughness phenolic resin-based composite refractory plate and a preparation method thereof, and relates to the technical field of high-molecular compound composition refractory plates. The high-toughness phenolic resin-based composite refractory plate is prepared from the following components in parts by mass: 40-65 parts of phenolic resin, 10-25 parts of reinforced fibers, 15-30 parts of a flame retardant, 8-20 parts of inorganic filler, 5-12 parts of a toughening agent, 0.5-3 parts of a coupling agent and 5-10 parts of a stability enhancer. The stability enhancer and phenolic resin are cross-linked to form a three-dimensional network, a multi-path flame suppression mechanism of a fluorine polymer toughening and flame-retardant system is cooperated, and a gradient pressure hot pressing process is combined, so that the mechanical property and flame retardance of the material are synergistically improved. The material has excellent toughness, lasting fire resistance and high-temperature stability, and can be widely applied to the fields of building fire prevention, aerospace and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of refractory plates of polymer compound compositions, and particularly relates to a high-toughness phenolic resin-based composite refractory plate and a preparation method thereof. Background Art

[0002] With the rapid development of modern industry, the performance requirements for refractory materials are becoming increasingly stringent. Among many refractory materials, phenolic resin-based composites are widely used in key fields such as building fire protection, aerospace, and electronics and electrical due to their excellent heat resistance, dimensional stability, and electrical insulation. However, traditional phenolic resin-based composites have some significant deficiencies, which limit their further expansion of application scope.

[0003] Firstly, phenolic resin itself is a brittle material with low tensile strength and impact strength, and it is prone to fracture when subjected to external force impact. This brittle characteristic makes it difficult for the material to withstand large mechanical stresses during actual use, especially under dynamic loads or complex working conditions, and the reliability of the material is greatly reduced.

[0004] Secondly, in order to meet the fire resistance requirements, a large amount of flame retardants are usually added to phenolic resin-based composites. However, the addition of these flame retardants often leads to a further decrease in the toughness of the material, forming a contradiction between toughening and flame retardancy. In addition, traditional flame retardant systems may release harmful gases at high temperatures, which not only pollute the environment but also may pose a hazard to human health.

[0005] Furthermore, in a high-temperature environment, the mechanical properties of phenolic resin-based composites will significantly decline. As the temperature increases, the molecular chain movement inside the material will intensify, resulting in a decrease in its strength and modulus, and it cannot meet the requirements for stable operation under high-temperature conditions for a long time.

[0006] Finally, the compatibility between phenolic resin and inorganic fillers is poor. Although the addition of inorganic fillers can improve some properties of the material, due to the weak interfacial bonding force between the two, stress concentration is likely to occur, which will instead reduce the comprehensive performance of the material.

[0007] In summary, existing phenolic resin-based composites have a series of problems in terms of toughness, flame retardancy, high-temperature stability, and compatibility with fillers. Therefore, developing a phenolic resin-based composite refractory plate with high toughness, excellent flame retardant performance, stable mechanical properties at high temperatures, and good compatibility with inorganic fillers has become an urgent technical problem to be solved in this field and an important direction to promote the development of related industries. Summary of the Invention

[0008] The present invention aims to provide a high-toughness phenolic resin-based composite refractory board with high toughness, excellent flame retardancy, good high-temperature stability and good compatibility with inorganic fillers and a preparation method thereof, so as to overcome the problems of insufficient material toughness, difficulty in balancing flame retardancy and toughening, poor high-temperature performance and poor filler compatibility in the prior art, and meet the needs of modern industry for high-performance refractory materials.

[0009] To achieve the above object, the technical solution adopted by the present invention is: a high-toughness phenolic resin-based composite refractory board, composed of the following components by mass: 40-65 parts of phenolic resin, 10-25 parts of reinforcing fiber, 15-30 parts of flame retardant, 8-20 parts of inorganic filler, 5-12 parts of toughening agent, 0.5-3 parts of coupling agent, and 5-10 parts of stabilizing and strengthening agent; The flame retardant is a composite system of aluminum hydroxide and ammonium phosphate, and the mass ratio thereof is (2-3):1; The toughening agent is polytetrafluoroethylene and / or polyperfluoroethylene propylene; The stabilizing agent has a structure shown in Formula 1: Formula 1; The R1 is selected from the group consisting of: methyl, ethyl, tert-butyl, phenyl, furyl, and thienyl.

[0010] Furthermore, the inorganic filler is a mixture of nano-silicon dioxide and micron-sized aluminum oxide, wherein the particle size of the nano-silicon dioxide is 20-50 nm, the mesh size of the aluminum oxide is 600-800 mesh, and the mass ratio of the two is 1:(0.8-1.2).

[0011] Furthermore, the reinforcing fiber is alkali-free glass fiber with a fiber diameter of 9-13 μm and a fiber length of 4-6 mm.

[0012] Furthermore, the coupling agent is a titanate coupling agent.

[0013] Furthermore, the titanate coupling agent is selected from: triisostearyl isopropyl titanate and / or tetraisopropyl di(dioctylphosphite) titanate.

[0014] Furthermore, the stabilizing enhancer is selected from any one of the compounds shown in the following structures: ; .

[0015] Furthermore, the synthesis method of the stabilizing enhancer is: ; Step 1: Raw materials 1 and 2 are subjected to Buchwald-Hartwig arylation reaction to synthesize intermediate 1; Step 2: Intermediate 1 and raw material 3 are subjected to a substitution reaction to synthesize Intermediate 2; Step 3: Intermediate 2 and raw material 4 are subjected to a Williamson reaction to synthesize a stability enhancer.

[0016] A preparation method of a high-toughness phenolic resin-based composite refractory board, comprising the following steps: S1. The reinforcing fiber is dried at 60 - 80 °C for 4 - 6 hours to obtain a dried reinforcing fiber; S2. The phenolic resin, flame retardant, inorganic filler, and toughening agent are kneaded in a kneader at 80 - 100 °C for 20 - 40 minutes to obtain a kneaded material; S3. The dried reinforcing fiber and the kneaded material are compounded on a two-roll open mill, and the roll temperature is controlled at 70 - 90 °C to obtain a composite material; S4. The composite material is placed in a mold and hot-pressed and formed at 160 - 180 °C and a pressure of 10 - 15 MPa, and the pressure holding time is 20 - 40 minutes; it is cooled stepwise to below 40 °C and demolded to obtain a high-toughness phenolic resin-based composite refractory board.

[0017] Further, the rotor speed of the kneader is 30 - 50 rpm, and the flame retardant is added in three times during the kneading process, with an interval of 5 - 8 minutes each time.

[0018] Further, the hot-pressing and forming adopts three-stage pressure control: maintaining 5 MPa for the initial 5 minutes, then rising to 12 MPa in the next 10 minutes, and finally maintaining 15 MPa until the end.

[0019] Further, the oxygen index of the high-toughness phenolic resin-based composite refractory board is ≥ 35%, the flexural strength is ≥ 85 MPa, and the notch impact strength is ≥ 15 kJ / m 2 , and the thermal weight loss rate at 300 °C is ≤ 5%.

[0020] The stability enhancer described in the present invention has a rigid skeleton containing polycyclic aromatic hydrocarbons or heterocycles, and its action mechanism is mainly reflected in: the conjugated structure of the aromatic ring or heterocycle can absorb heat energy, inhibit the breakage of molecular chains at high temperatures, and slow down thermal decomposition; the active sites (such as hydroxyl groups, amino groups) in the parent nucleus undergo a condensation reaction with the hydroxymethyl group of the phenolic resin to form a three-dimensional cross-linked network, enhancing the rigidity of the material; the aromatic ring structure can capture free radicals generated by high-temperature degradation, block the chain oxidation reaction, and delay the aging of the material.

[0021] The phenolic resin described in the present invention provides basic rigidity through a cross-linked network as the matrix. The reinforcing fibers and inorganic fillers form a rigid-flexible skeleton structure. The former inhibits crack propagation while the latter fills micro-defects. At the same time, the flame retardant inhibits combustion through the dual paths of endothermic decomposition and gas-phase barrier during pyrolysis. Its residue forms a physical barrier with the fluoropolymer in the toughening agent, blocking oxygen diffusion and absorbing impact energy through interface slip; the coupling agent improves the interfacial compatibility between the filler and the resin through molecular bridging. The rigid nucleus of the stabilizing and strengthening agent penetrates the resin cross-linked network and stabilizes the molecular chain movement through the electron delocalization effect at high temperatures. Combined with the gradient densification structure formed by the stepped hot pressing process, a multiple positive synergistic trend of toughness maintenance, flame retardant enhancement, high-temperature dimensional stability, and stress dispersion is finally achieved.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Synergistic improvement of toughness and strength: Through the synergistic effect of the three-dimensional cross-linked network of the toughening agent and the stabilizing and strengthening agent, while maintaining the high strength of the phenolic resin matrix, the impact resistance of the material is significantly improved, breaking through the limitations of traditional materials with high brittleness and easy fracture.

[0023] 2. Dynamic balance between flame retardancy and thermal stability: The combination of the flame retardant and the stabilizing and strengthening agent inhibits combustion in the gas-solid dual paths and forms a thermal stability barrier at high temperatures, solving the industry problem of the deterioration of mechanical properties caused by the addition of flame retardants.

[0024] 3. Optimization of interfacial compatibility and process adaptability: Through the directional modification of the coupling agent and the stepped hot pressing process, stress dispersion at the interface of fiber-filler-resin is achieved, forming a multi-scale reinforcement structure, and significantly improving the performance stability of the material under complex working conditions. Description of the Drawings

[0025] Figure 1 It is the synthesis method of the stabilizing and strengthening agent described in the present invention. Detailed Embodiments

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the drawings in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art without creative work based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0027] Synthesis Example 1 Synthesis of stabilizing and strengthening agent 1: ; Step 1: Under nitrogen protection, add 20g of raw material 1, 23.30g of raw material 2, 2.23g of tri(dibenzylideneacetone)dipalladium, 22.46g of potassium carbonate, 0.8g of tri-tert-butylphosphine and 200g of toluene to the reaction system, stir evenly, heat to 120°C, and reflux for 12h; after the reaction is completed, slightly lower the temperature, filter with silica gel, cool the filtrate to room temperature, wash three times with water, retain the organic phase, and then extract the aqueous phase with ethyl acetate; after combining the organic phases, dry with anhydrous magnesium sulfate, spin dry, column chromatography, and use a mixture of petroleum ether and ethyl acetate as an eluent to obtain 16.66g of intermediate 1. MS (MS+1): 356.

[0028] Step 2: Under nitrogen protection, add 16.66g of intermediate 1, 12.44g of aluminum chloride and 100g of toluene to the reaction system, slowly drop 60g of toluene solution containing 3.66g of raw material 3 at 0℃, the temperature does not exceed 10℃ during the dropwise addition, and then react at 25℃ for 6h. Slowly pour the reaction solution into 500ml 0.1mol / L HCl at 0℃, stir for 30min, stand for separation, and retain the organic phase. Wash the aqueous phase 3 times with 50ml of dichloromethane, combine the organic phases, add 100ml of 0.1mol / L sodium bicarbonate solution, stir and shake, adjust the pH to neutral, and retain the organic phase. Dry with anhydrous magnesium sulfate, spin dry, column chromatography, use a mixture of petroleum ether and ethyl acetate as eluent, and obtain 13.89g of intermediate 2. MS (MS+1): 399.

[0029] Step 3: Under nitrogen protection, add 13.89 g of intermediate 2, 17.26 g of raw material 4, 18.53 g of potassium phosphate trihydrate, 0.04 g of pyridine-2-carboxylic acid, and 0.3 g of CuI to the reaction system, react at 85°C for 16 h, extract the obtained reaction mixture with aqueous ammonia solution and methyl tert-butyl ether after cooling, wash the organic phase with water five times, and then wash it twice with saturated NaCl solution; dry the combined organic phase with anhydrous magnesium sulfate, spin dry, column chromatography, and use a mixture of petroleum ether and ethyl acetate as eluent to obtain 18.43 g of stabilizing enhancer 1. MS (MS+1): 731.

[0030] Stable Enhancer 1 1HNMR (chloroform-d) was as follows: δ 8.85 (d, 1H), 8.17 - 8.07 (m, 1H), 8.11 - 8.04 (m, 1H), 7.98 (s, 1H), 7.92 (dd, 1H), 7.79 (m, 1H), 7.71 (dd, 1H), 7.68 - 7.55 (m, 3H), 7.53 (dd, 1H), 7.45 (m, 1H), 7.41 - 7.33 (m, 1H), 6.95 (dd, 1H), 6.42 (t, 1H), 4.22 (t, 2H), 4.02 (t, 2H), 3.71 - 3.56 (m, 4H), 2.81 (t, 2H), 2.64 (s, 3H), 2.29 - 2.17 (m, 2H).

[0031] Synthesis Examples 2 - 6 Synthesis Examples 2 - 6 were used to synthesize Stabilizers 2 - 6 in sequence. Referring to the synthesis method of Synthesis Example 1, raw material 3 was replaced, and the rest was kept the same as that of Synthesis Example 1. The specific structures of raw material 3, Stabilizers 2 - 6, and MS (MS + 1) data are shown in the following table: .

[0032] Example 1 Preparation of a high-toughness phenolic resin-based composite refractory board, the specific steps are as follows: Raw material ratio (parts by mass): phenolic resin 50 parts, reinforcing fiber (non-alkali glass fiber) 18 parts, flame retardant (aluminum hydroxide and ammonium phosphate compounded by a mass ratio of 2.5:1) 22 parts, inorganic filler (nano-silica with a particle size of 30 nm, alumina of 800 mesh, mass ratio 1:1) 15 parts, toughening agent (polytetrafluoroethylene) 8 parts, coupling agent (isotridecyl titanate isopropyl ester) 1.5 parts, stabilizing and strengthening agent (stabilizing and strengthening agent 1 prepared in Synthesis Example 1) 7 parts.

[0033] Preparation method: S1. Place the non-alkali glass fiber in an oven at 70 °C and dry for 5 hours to remove surface moisture, obtaining dried reinforcing fiber.

[0034] S2. Add phenolic resin, flame retardant (added in three times, 5 parts for the first time, 10 parts for the second time, 7 parts for the third time, with an interval of 6 minutes each time), nano-silica, alumina, and polytetrafluoroethylene into a kneader, set the rotor speed at 40 rpm, the mixing temperature at 90 °C, and the mixing time at 30 minutes to obtain a mixed material.

[0035] S3. Compound the dried reinforcing fiber and the mixed material on a two-roll open mill, control the roll temperature at 80 °C, adjust the roll gap to 1.5 mm, and thin-pass repeatedly 5 times to ensure uniform dispersion of the fiber, obtaining a composite material.

[0036] S4. Load the composite material into the mold and adopt three-stage pressure control: Initial stage: Maintain a pressure of 5 MPa for 5 minutes to discharge air bubbles; Heating stage: Raise the pressure to 12 MPa and keep it for 10 minutes at a temperature of 170 °C; Final pressure stage: Raise the pressure to 15 MPa and maintain it for 20 minutes to ensure complete curing. Gradually cool down to below 40 °C (cool down 20 °C every 10 minutes), cut after demolding to obtain a high-toughness phenolic resin-based composite refractory board.

[0037] Examples 2 - 6 Referring to the preparation method of Example 1, sequentially replace the stabilizing and strengthening agent therein with the stabilizing and strengthening agents prepared in Synthesis Examples 2 - 6, and keep the rest the same as in Example 1.

[0038] Comparative Example 1 Referring to the preparation method of Example 1, replace the stabilizing and strengthening agent therein with Comparative Compound 1, and keep the rest the same as in Example 1.

[0039] Comparative Compound 1: .

[0040] Comparative Example 2 Referring to the preparation method of Example 1, replace the stabilizing and strengthening agent therein with Comparative Compound 2, and keep the rest the same as in Example 1.

[0041] Comparative Compound 2: .

[0042] Comparative Example 3 Referring to the preparation method of Example 1, do not add the stabilizing and strengthening agent therein, and keep the rest the same as in Example 1.

[0043] Comparative Example 4 Referring to the preparation method of Example 1, change the raw material ratio (parts by mass) to: 70 parts of phenolic resin, 18 parts of reinforcing fiber (non-alkali glass fiber), 22 parts of flame retardant (composite of aluminum hydroxide and ammonium phosphate with a mass ratio of 2.5:1), 25 parts of inorganic filler (nano-silica with a particle size of 30 nm and alumina of 800 mesh, with a mass ratio of 1:1), 30 parts of toughening agent (polytetrafluoroethylene), 1.5 parts of coupling agent (isopropyl triisostearoyl titanate), 7 parts of stabilizing and strengthening agent (stabilizing and strengthening agent 1 prepared in Synthesis Example 1), and keep the rest the same as in Example 1.

[0044] Performance test: 1. Determine the thermal conductivity of different products according to GB / T10294 - 2008 "Determination of Steady-State Thermal Resistance and Related Characteristics of Thermal Insulation Materials - Guarded Hot Plate Method"; 2. Determine the fire protection grade of different products according to GB8624 - 2019 "Classification of the Burning Performance of Building Materials and Products"; 3. Measure the compressive strength of different products in accordance with GB / T 10801.1-2021 "Expanded Polystyrene (EPS) for Thermal Insulation".

[0045] 4. Measure the tensile strength in accordance with JG / T 536-2017 "Thermosetting Composite Polystyrene Foam Thermal Insulation Board".

[0046] The test results are shown in the following table. In terms of thermal conductivity, the heat insulation effect of the examples is significantly better than that of the comparative examples, indicating that the material structure design effectively reduces heat conduction; in terms of fire protection level, all examples meet the highest fire resistance standard, while the comparative examples show an obvious degradation, indicating that the synergistic effect of the flame retardant system is fully exerted in the examples; in terms of mechanical properties, the compressive and tensile strengths of the examples are generally higher than those of the comparative examples, especially the comparative examples lacking key components or with unbalanced ratios show significant mechanical property attenuation. In addition, although adjusting the component ratio in the comparative examples improves some properties, it still does not reach the comprehensive level of the examples, confirming the strict ratio relationship between components and the key role of the stable strengthening agent in high-temperature stability. Generally speaking, the examples achieve positive synergy in flame retardancy, mechanics and thermal stability through component optimization and process control.

[0047] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-toughness phenolic resin-based composite refractory board, characterized in that, It consists of the following components in parts by mass: 40 - 65 parts of phenolic resin, 10 - 25 parts of reinforcing fiber, 15 - 30 parts of flame retardant, 8 - 20 parts of inorganic filler, 5 - 12 parts of toughening agent, 0.5 - 3 parts of coupling agent, and 5 - 10 parts of stabilizing and strengthening agent; The flame retardant is a composite system of aluminum hydroxide and ammonium phosphate, and the mass ratio thereof is (2 - 3):1; The toughening agent is polytetrafluoroethylene and / or perfluoroethylenepropylene; The stabilizing and strengthening agent has the structure shown in Formula 1: Formula 1; The R1 is selected from: methyl, ethyl, tert-butyl, phenyl, furyl, thienyl.

2. The high-toughness phenolic resin-based composite refractory board according to claim 1, characterized in that, The inorganic filler is a mixture of nano-silica and micron-sized alumina, wherein the particle size of the nano-silica is 20 - 50 nm, the mesh number of the alumina is 600 - 800 mesh, and the mass ratio of the two is 1:(0.8 - 1.2).

3. A high-toughness phenolic resin-based composite refractory board according to claim 1, characterized in that, The reinforcing fiber is alkali-free glass fiber, with a fiber diameter of 9 - 13 μm and a fiber length of 4 - 6 mm.

4. A high-toughness phenolic resin-based composite refractory board according to claim 1, characterized in that The coupling agent is a titanate coupling agent.

5. A high-toughness phenolic resin-based composite refractory sheet according to claim 4, characterized in that, The titanate coupling agent is selected from: triisostearoyl titanate isopropyl ester and / or tetra-isopropyl di(dioctyl phosphite acyloxy) titanate.

6. The high-toughness phenolic resin-based composite refractory board according to claim 1, wherein The stabilizing and strengthening agent is selected from any one of the compounds shown in the following structures: ； 。 7. A method for preparing a high-toughness phenolic resin-based composite refractory board according to any one of claims 1-6, characterized in that, It includes the following steps: S1. Dry the reinforcing fiber at 60 - 80 °C for 4 - 6 hours to obtain dried reinforcing fiber; S2. Mix the phenolic resin, flame retardant, inorganic filler and toughening agent in a mixer at 80 - 100 °C for 20 - 40 minutes to obtain a mixed material; S3. Compound the dried reinforcing fiber and the mixed material on a two-roll mill, and control the roll temperature at 70 - 90 °C to obtain a composite material; S4. Place the composite material in a mold, and hot press it at 160 - 180 °C under a pressure of 10 - 15 MPa for 20 - 40 minutes; cool it stepwise to below 40 °C and demold to obtain a high-toughness phenolic resin-based composite refractory board.

8. The preparation method of a high-toughness phenolic resin-based composite refractory board according to claim 7, characterized in that, The rotor speed of the mixer is 30 - 50 rpm, and the flame retardant is added in three times during the mixing process, with an interval of 5 - 8 minutes each time.

9. The preparation method of a high-toughness phenolic resin-based composite refractory board according to claim 7, characterized in that, The hot pressing adopts three-stage pressure control: maintain 5 MPa for the initial 5 minutes, then increase to 12 MPa in the next 10 minutes, and keep 15 MPa until the end in the last stage.

10. A high-toughness phenolic resin-based composite refractory board according to claim 1, characterized in that, The oxygen index of the described high-toughness phenolic resin-based composite refractory board is ≥ 35%, the flexural strength is ≥ 85 MPa, and the notched impact strength is ≥ 15 kJ / m 2 , and the thermal weight loss rate at 300 °C is ≤ 5%.

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