Flame-retardant phenolic / glass fiber composite board, preparation method and application thereof

Abstract

This invention belongs to the technical field of phenolic / glass fiber composite materials, specifically relating to a flame-retardant phenolic / glass fiber composite board, its preparation method, and its application. The flame-retardant phenolic / glass fiber composite board comprises 60-70 wt% glass fiber cloth and 30-40 wt% resin composition cured on the glass fiber cloth. The resin composition consists of the following raw materials in parts by weight: 90-100 parts modified phenolic resin, 5-10 parts epoxy resin, 1-2 parts multifunctional epoxy compound, 1-3 parts toughening agent, and diluent. The amount of diluent is such that the viscosity of the resin composition at 25°C is 150-400 mPa·s. The modified phenolic resin is prepared by reacting phenol, modified phenol, and formaldehyde under the action of an alkaline catalyst. The modified phenol is prepared by transesterification of phenolic alkyl alcohol compounds with phosphonate monocarboxylic acid alkyl esters. The flame-retardant phenolic / glass fiber composite panel of the present invention meets the flame-retardant performance requirements of Part 1 of Appendix F of CCAR-25, which specifies cabin interior facilities or cargo and baggage compartments, without the need for additional flame retardants.

Description

Technical Field

[0001] This invention belongs to the technical field of phenolic / glass fiber composite materials, specifically relating to a flame-retardant phenolic / glass fiber composite board, its preparation method, and its application. Background Technology

[0002] Phenolic / glass fiber composites, with their comprehensive advantages such as lightweight, high strength, high temperature resistance, intrinsic flame retardancy, low smoke, and low toxicity, have become one of the preferred materials for interior structures in aerospace, rail transportation, and marine industries. Particularly in aircraft passenger and cargo cabins, this material is widely used in the manufacture of components such as cabin floors, partitions, wall panels, ceilings, baggage compartments, and cargo hold liners. To meet lightweight requirements while maintaining high load-bearing capacity, load-bearing components such as aircraft floors and cargo hold liners commonly employ honeycomb sandwich structures. This structure, composed of upper and lower panels, an adhesive film, and a honeycomb core layer, possesses a series of excellent properties including high specific strength, high specific stiffness, light weight, sound insulation, noise reduction, and heat insulation. Phenolic / glass fiber composites are frequently used as the panel material for this sandwich structure.

[0003] The molding methods for honeycomb sandwich structures are mainly divided into co-curing and secondary bonding methods. Co-curing involves sequentially assembling the uncured upper and lower panels, honeycomb core, and adhesive film, with the panel curing and bonding to the honeycomb core completed in one step. This method has a short manufacturing cycle and low manufacturing cost. Secondary bonding involves pre-curing the upper and lower panels before bonding them to the honeycomb core and adhesive film. This method has a longer manufacturing cycle and higher manufacturing cost, but produces better panel quality with fewer internal defects, making it easier to control the thickness accuracy and surface quality of the panels. Furthermore, the honeycomb core is less prone to lateral slippage or crushing. Therefore, secondary bonding is more widely used to obtain high-quality flooring, as illustrated by patents such as CN116100907B (a method for preparing aircraft cargo hold flooring and the resulting aircraft cargo hold flooring), CN113650375B (an impact-resistant and flame-retardant flooring and its preparation method), and CN105860430B (a phenolic fiberglass prepreg with light color and high-quality surface effect and its preparation method). The above technology involves pre-pressing phenolic / glass fiber composite materials into phenolic / glass fiber composite boards, and then bonding them with adhesive film and honeycomb core using a secondary adhesive bonding method to prepare honeycomb sandwich structure panels. Although phenolic resin itself has good flame retardant properties, appropriate flame retardants still need to be added to meet the flame retardant requirements of aircraft. Since flame retardants are mostly inorganic powders or non-reactive organic particles, their interface bonding with phenolic resin and glass fiber is weak, which can easily cause stress concentration, interface debonding, and panel delamination damage.

[0004] Therefore, it is necessary to develop a flame-retardant phenolic / glass fiber composite material that has excellent flame-retardant properties and is not prone to delamination damage in phenolic / glass fiber composite boards. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a flame-retardant phenolic / glass fiber composite board, its preparation method, and its application. The composite board comprises 60-70 wt% glass fiber cloth and 30-40 wt% resin composition cured on the glass fiber cloth. The matrix resin of the resin composition includes a modified phenolic resin containing phosphonate groups with flame-retardant function in its molecular structure. The modified phenolic resin is first prepared by transesterification of phenolic alkyl alcohol compounds with phosphonate monocarboxylic acid alkyl esters. Then, phenol, modified phenol, and formaldehyde are reacted under the action of an alkaline catalyst to obtain the modified phenolic resin. The modified phenolic resin is a phosphorus-based flame-retardant phenolic resin, which can meet the stringent flame-retardant requirements of the aircraft industry for composite boards. It also eliminates the weak bonding interface between the added flame retardant and the resin matrix and glass fiber cloth, avoiding interface compatibility problems and preventing interface stress concentration and debonding. This fundamentally solves the defect of existing composite boards being prone to delamination and damage. Furthermore, the resin composition incorporates multifunctional epoxy compounds that synergistically work with the modified phenolic resin. By increasing the curing crosslinking density and interfacial chemical bonding, the roller peel strength is further improved, ensuring excellent overall structural integrity even under extreme stress conditions. The flame-retardant phenolic / glass fiber composite panel of this invention meets the flame-retardant performance requirements of CCAR-25 Appendix F Part 1 for cabin interior facilities or cargo holds and baggage compartments without the need for additional flame retardants.

[0006] To achieve the above objectives, the following technical solution is adopted:

[0007] A flame-retardant phenolic / glass fiber composite board comprises 60-70 wt% glass fiber cloth and 30-40 wt% resin composition cured on the glass fiber cloth. The resin composition consists of the following raw materials in parts by weight: 90-100 parts modified phenolic resin, 5-10 parts epoxy resin, 1-2 parts multifunctional epoxy compound, 1-3 parts toughening agent, and diluent. The amount of diluent is such that the viscosity of the resin composition at 25°C is 150-400 mPa·s. The modified phenolic resin is prepared by reacting phenol, modified phenol, and formaldehyde under the action of an alkaline catalyst. The modified phenol is prepared by transesterification of phenolic alkyl alcohol compounds with phosphonate monocarboxylic acid alkyl esters.

[0008] The molar ratio of the phenolic alkyl alcohol compound to the phosphonate monocarboxylic acid alkyl ester is 1.1-1.2:1.

[0009] The phenolic alkyl alcohol compounds are selected from one or more of p-hydroxybenzyl alcohol, o-hydroxybenzyl alcohol, m-hydroxybenzyl alcohol, p-hydroxyphenylethanol, o-hydroxyphenylethanol, and 2-(3-hydroxyphenyl)ethanol.

[0010] The phosphonate monocarboxylic acid alkyl ester is selected from one or more combinations of dimethylphosphonoethyl acetate, diethyl phosphonoacetate, [2-(methoxycarbonyl)ethyl] phosphate, trimethylphosphonoacetate, triethyl phosphonate, triethyl phosphonoacetate, triethyl phosphonoacetate, triethyl 4-phosphonobutyrate, triethyl-2-phosphonopropyl ester, and triethyl 2-phosphonobutyrate.

[0011] The modified phenol is prepared by a method comprising the following steps: dissolving phenolic alkyl alcohol compounds and phosphonate monocarboxylic acid alkyl esters in an organic solvent, adding a catalyst, and reacting under reflux conditions to obtain the modified phenol.

[0012] The organic solvent is selected from one or a combination of two or more of tetrahydrofuran, chloroform, dimethyl sulfoxide, N,N-dimethylformamide, and dioxane. The catalyst is selected from one or a combination of two of p-toluenesulfonic acid and sodium formate. The amount of catalyst used is 0.5-1 wt% of the combined mass of the phenolic alkyl alcohol compound and the phosphonate monocarboxylic acid alkyl ester. The reaction time is 6-10 h. After the reaction, the process includes post-treatment operations such as vacuum distillation to remove small molecule alcohol byproducts, precipitation with petroleum ether, filtration, washing, and drying. The washing is performed three times with alternating ethanol and water. The drying is performed at 60-80℃ and a vacuum of 0.01-0.09 MPa for 1-3 h.

[0013] The molar ratio of phenol, modified phenol, and formaldehyde is 0.8-0.9:0.1-0.2:1.2-1.5.

[0014] The alkaline catalyst is ammonia water with a concentration of 20-28 wt%. The alkaline catalyst is 3-5 wt% of the combined mass of phenol, modified phenol, and formaldehyde.

[0015] The formaldehyde was added in the form of a 30-37 wt% formaldehyde aqueous solution.

[0016] The modified phenolic resin is prepared by a method comprising the following steps: adding phenol, modified phenol, formaldehyde, and alkaline catalyst into a reaction vessel, mixing, heating and reacting, and dehydrating to obtain the modified phenolic resin.

[0017] The heating reaction is carried out at 50-95℃ for 2-5 hours; further, the heating is carried out at 50-75℃ for 1-3 hours, and then at 85-95℃ for 1-2 hours.

[0018] The dehydration was carried out at 50-90℃ and a vacuum of 0.05-0.09MPa. The gelation time of the dehydrated product was measured every 5-10 minutes. Dehydration was completed when the gelation time was 80-200 seconds at 150-160℃.

[0019] The multifunctional epoxy compound is selected from one or more combinations of trimethylolpropane triglycidyl ether, glycerol triglycidyl ether, triglycidyl p-aminophenol, triglycidyl m-aminophenol, and pentaerythritol glycidyl ether.

[0020] The fiberglass cloth has a basis weight of 100-450 g / m². 2 The preferred weight is 100-300g / m³. 2 S-fiberglass cloth or E-fiberglass cloth.

[0021] The epoxy value of the epoxy resin is 0.44-0.55. The epoxy resin is selected from one or a combination of two or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and phenolic type epoxy resin.

[0022] The toughening agent is selected from one or more of carboxyl-terminated nitrile rubber, carboxyl-terminated polybutadiene, hydroxyl-terminated polybutadiene, and polyvinyl butyral; preferably, it is hydroxyl-terminated polybutadiene with a weight average molecular weight of 2000-5000.

[0023] The diluent is selected from one or a combination of two or more of methanol, ethanol, propanol, and acetone.

[0024] The present invention also provides a method for preparing the above-mentioned flame-retardant phenolic / glass fiber composite board, comprising the following steps:

[0025] 1) Mix the modified phenolic resin, epoxy resin, toughening agent, and diluent to obtain a resin composition;

[0026] 2) The glass fiber cloth and resin composition are impregnated, dried, cooled and wound up on an impregnation machine to obtain a prepreg;

[0027] 3) Lay out prepreg and pre-cur it to obtain flame-retardant phenolic / glass fiber composite board.

[0028] In step 2), the pressure of the impregnation roller during impregnation is 0.1-0.3 MPa, and the rotation speed is 5-15 r / min. The drying temperature is 60-110℃.

[0029] In step 3), the number of layers is 2-6. During the layup, the warp faces of the fiberglass cloth face the same direction, and the warp angles of the fiberglass cloth in each prepreg layer are the same. The pre-curing conditions are 0.3-0.8 MPa, temperature 100-120℃, and time 10-60 min.

[0030] The present invention also provides the above-mentioned flame-retardant phenolic / glass fiber composite board as a panel for aircraft flooring and cargo hold lining with a honeycomb sandwich structure formed by a secondary bonding method.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] The composite board of this invention comprises 60-70 wt% glass fiber cloth and 30-40 wt% resin composition cured on the glass fiber cloth. The matrix resin of the resin composition includes a modified phenolic resin containing phosphonate groups with flame-retardant function in its molecular structure. The modified phenolic resin is obtained by first reacting phenol alkyl alcohol compounds with phosphonate monocarboxylic acid alkyl esters through transesterification. Then, phenol, modified phenol, and formaldehyde are reacted under the action of an alkaline catalyst to obtain the modified phenolic resin. The modified phenolic resin is a phosphorus-based flame-retardant phenolic resin, which can meet the stringent flame-retardant requirements of the aircraft industry for composite boards, and also eliminate the weak bonding interface between the added flame retardant and the resin matrix and glass fiber cloth, avoiding interface compatibility problems, preventing interface stress concentration and interface debonding, and fundamentally solving the defect of easy delamination and damage of existing composite boards. In addition, the resin composition incorporates multifunctional epoxy compounds that work synergistically with modified phenolic resins to increase curing crosslinking density and interfacial chemical bonding, thereby further improving roller peel strength and ensuring excellent overall structural integrity even under extreme stress conditions.

[0033] The flame-retardant phenolic / glass fiber composite panel of the present invention meets the flame-retardant performance requirements of Part 1 of Appendix F of CCAR-25, which stipulates that cabin interior facilities or cargo holds and baggage compartments can be installed without the need for additional flame retardants. Detailed Implementation

[0034] The present invention will be further described below with reference to specific embodiments, but is not limited to the contents of the specification. Unless otherwise specified, all "parts" mentioned in the embodiments of the present invention are parts by weight. All reagents used are commercially available in the art.

[0035] E-grade fiberglass cloth (EW100) has a weight of 100g / m². 2 It comes from Chongqing Canyue New Materials Co., Ltd.

[0036] The hydroxyl-terminated polybutadiene P-68911 has an average molecular weight of 4600 and is sourced from Hines.

[0037] Hydroxyl-terminated polybutadiene P-0445141 has a weight-average molecular weight of 2700 and is sourced from Hines.

[0038] Example 1

[0039] 1) Dissolve 1.2 mol of p-hydroxybenzyl alcohol and 1 mol of ethyl dimethylphosphonoethyl alcohol in 1 L of N,N-dimethylformamide, add p-hydroxybenzyl alcohol and ethyl dimethylphosphonoethyl alcohol by mass and 1 wt% p-toluenesulfonic acid, heat to reflux and react for 10 h. After the reaction is completed, remove the small molecule alcohol byproduct by distillation under reduced pressure, add petroleum ether to precipitate, filter, wash with ethanol and water alternately 3 times, and finally dry at 60 °C and vacuum degree of 0.03 MPa for 2 h to obtain modified phenol.

[0040] 2) Add 0.8 mol phenol, 0.2 mol modified phenol, a 37 wt% formaldehyde aqueous solution containing 1.5 mol formaldehyde, and 28 wt% ammonia solution (5 wt% of the total mass of phenol, modified phenol, and formaldehyde) to a reaction vessel and mix well. Heat to 60℃ and react for 2 hours, then heat to 85℃ and react for 2 hours. Then cool to 60℃ and dehydrate for 80 minutes under a vacuum of 0.07 MPa at 60℃. Raise the temperature to 85℃ and continue dehydration under a vacuum of 0.09 MPa at 85℃. Measure the gel time of the dehydrated product every 5 minutes. After 25 minutes, the dehydrated product was found to have a gel time of 150 seconds at 150℃, thus obtaining the modified phenolic resin.

[0041] 3) Mix 100 kg of modified phenolic resin, 10 kg of epoxy resin E-44, 2 kg of pentaerythritol glycidyl ether, 3 kg of hydroxyl-terminated polybutadiene P-68911 and ethanol. The amount of ethanol used is such that the viscosity of the mixture at 25°C is 400 mPa·s, and the resin composition is obtained.

[0042] 4) The resin composition is poured into the impregnation tank of the horizontal coating machine. E-glass fiber cloth (EW100) is introduced into the impregnation tank via impregnation rollers. After impregnation, drying, cooling, and winding, a prepreg is obtained. The impregnation roller pressure is 0.3 MPa and the rotation speed is 10 r / min. Drying is carried out in a drying tunnel, consisting of 5 sections, with temperatures of 65℃, 75℃, 80℃, 85℃, and 105℃ respectively.

[0043] 5) Lay two layers of the above prepreg, with the warp faces of the fiberglass cloth facing the same direction and the warp angles of the fiberglass cloth in each layer of prepreg being the same. Then, pre-cur the prepreg by hot pressing at 100℃ and 0.3MPa for 60 minutes to obtain a flame-retardant phenolic / fiberglass composite board with a composition of 60% fiberglass cloth and 40wt% resin cured on the fiberglass cloth.

[0044] Example 2

[0045] The rest is the same as in Example 1, except that in step 2), the amount of phenol used is 0.9 mol and the amount of modified phenol is 0.1 mol.

[0046] Example 3

[0047] The rest is the same as in Example 1, except that in step 2), the amount of modified phenol used is 0.25 mol.

[0048] Example 4

[0049] The rest is the same as in Example 1, except that in step 2), the amount of modified phenol used is 0.05 mol.

[0050] Example 5

[0051] The rest is the same as in Example 1, except that in step 3), the amount of pentaerythritol glycidyl ether used is 1 kg.

[0052] Example 6

[0053] The rest is the same as in Example 1, except that in step 3), pentaerythritol glycidyl ether is replaced with an equal mass of glycerol triglycidyl ether.

[0054] Example 7

[0055] The rest is the same as in Example 1, except that in step 3), the amount of modified phenolic resin used is 90 kg.

[0056] Example 8

[0057] 1) Dissolve 1.1 mol of p-hydroxyphenylethanol and 1 mol of trimethylphosphonoacetate in 1 L of N,N-dimethylformamide, add 1 wt% of p-toluenesulfonic acid (based on the combined mass of p-hydroxyphenylethanol and trimethylphosphonoacetate), heat to reflux and react for 10 h. After the reaction is complete, remove the small molecule alcohol byproduct by distillation under reduced pressure, add petroleum ether to precipitate, filter, wash three times alternately with ethanol and water, and finally dry at 60 °C and 0.03 MPa for 2 h to obtain modified phenol.

[0058] 2) Add 0.8 mol phenol, 0.2 mol modified phenol, a 37 wt% formaldehyde aqueous solution containing 1.2 mol formaldehyde, and a 28 wt% ammonia solution (3 wt% of the total mass of phenol, modified phenol, and formaldehyde) to a reaction vessel and mix well. Heat to 60℃ and react for 2 hours, then heat to 85℃ and react for 2 hours. Then cool to 60℃ and dehydrate for 85 minutes at 60℃ and a vacuum of 0.06 MPa. Raise the temperature to 85℃ and continue dehydration at 85℃ and a vacuum of 0.09 MPa. Measure the gel time of the dehydrated product every 5 minutes. After 15 minutes, the dehydrated product was found to have completed dehydration when the gel time at 150℃ was 150 seconds, thus obtaining the modified phenolic resin.

[0059] 3) Mix 100 kg of modified phenolic resin, 10 kg of epoxy resin E-44, 2 kg of pentaerythritol glycidyl ether, 3 kg of hydroxyl-terminated polybutadiene P-0445141 and ethanol. The amount of ethanol used is such that the viscosity of the mixture at 25°C is 200 mPa·s, and the resin composition is obtained.

[0060] 4) The resin composition is poured into the impregnation tank of the horizontal coating machine. E-glass fiber cloth (EW100) is introduced into the impregnation tank via impregnation rollers. After impregnation, drying, cooling, and winding, a prepreg is obtained. The impregnation roller pressure is 0.3 MPa and the rotation speed is 10 r / min. Drying is carried out in a drying tunnel, consisting of 5 sections, with temperatures of 65℃, 75℃, 80℃, 85℃, and 105℃ respectively.

[0061] 5) Lay 6 layers of the above prepreg, with the warp faces of the glass fiber cloth facing the same direction during the layering, and the warp angle of the glass fiber cloth in each layer of prepreg is the same. Then, pre-cur it by hot pressing at 120℃ and 0.8MPa for 10 minutes to obtain a flame-retardant phenolic / glass fiber composite board with a composition of 70wt% glass fiber cloth and 30wt% resin cured on the glass fiber cloth.

[0062] Comparative Example 1

[0063] 1) Add 1 mol of phenol, a 37wt% formaldehyde aqueous solution containing 1.5 mol of formaldehyde, and 28wt% ammonia solution (5wt% of the total mass of phenol and formaldehyde) to a reaction vessel and mix well. Heat to 60℃ and react for 2 hours, then heat to 85℃ and react for 2 hours. Then cool to 60℃ and dehydrate for 80 minutes under a vacuum of 0.07 MPa at 60℃. Raise the temperature to 85℃ and continue dehydration under a vacuum of 0.09 MPa at 85℃. Measure the gel time of the dehydrated product every 5 minutes. After 25 minutes, the dehydrated product was found to have completed dehydration when the gel time at 150℃ was 150 seconds, thus obtaining phenolic resin.

[0064] 2) Mix 80 kg of phenolic resin, 20 kg of flame retardant aluminum hydroxide (average particle size 3 μm, from Zhengzhou Xideli Chemical New Material Co., Ltd.), 10 kg of epoxy resin E-44, 2 kg of pentaerythritol glycidyl ether, 3 kg of hydroxyl-terminated polybutadiene P-68911 and ethanol. The amount of ethanol used is such that the viscosity of the mixture at 25°C is 400 mPa·s, to obtain the resin composition.

[0065] 3) The resin composition is poured into the impregnation tank of the horizontal coating machine. E-glass fiber cloth (EW100) is introduced into the impregnation tank via impregnation rollers. After impregnation, drying, cooling, and winding, a prepreg is obtained. The impregnation roller pressure is 0.3 MPa and the rotation speed is 10 r / min. Drying is carried out in a drying tunnel, consisting of 5 sections, with temperatures of 65℃, 75℃, 80℃, 85℃, and 105℃ respectively.

[0066] 4) Lay two layers of the above prepreg, with the warp faces of the fiberglass cloth facing the same direction during the layering, and the warp angles of the fiberglass cloth in each layer of prepreg being the same. Then, pre-cur the prepreg by hot pressing at 100℃ and 0.3MPa for 60 minutes to obtain a flame-retardant phenolic / fiberglass composite board with a composition of 60% fiberglass cloth and 40wt% resin cured on the fiberglass cloth.

[0067] Comparative Example 2

[0068] The rest is the same as in Example 1, except that in step 3), pentaerythritol glycidyl ether is replaced with an equal mass of E-44.

[0069] The flame-retardant phenolic / glass fiber composite boards prepared in the above embodiments and comparative examples were subjected to the following performance tests:

[0070] 1. Flame retardant performance: The flame retardant phenolic / glass fiber composite board was thermocured at 130℃ and 0.3MPa for 90min, and then the flame retardant performance was tested according to Appendix F Part 1 of standard CCAR-25, with 60s of vertical burning.

[0071] The flame-retardant phenolic / glass fiber composite boards prepared in the above embodiments and comparative examples were stacked in the following order to form a sandwich structure: flame-retardant phenolic / glass fiber composite board, epoxy film (without flame-retardant components, size 1220*2440*0.15mm, purchased from Shenzhen Tutmei Polymer Materials Co., Ltd.), Nomex honeycomb core (model SD-NH-1.83-48, core size 1220*2440*10mm, from Xiamen Paiyoupai New Materials Co., Ltd.), epoxy film (without flame-retardant components, size 1220*2440*0.15mm, purchased from Shenzhen Tutmei Polymer Materials Co., Ltd.), and flame-retardant phenolic / glass fiber composite board. The weft side of the glass fiber cloth on the flame-retardant phenolic / glass fiber composite board faced the honeycomb core. The mixture was thermosetting at 130℃ and 0.3MPa for 90 minutes to obtain a honeycomb sandwich structure floor. The following performance tests were performed:

[0072] 1. Flame retardant performance: The flame retardant performance test was conducted according to Appendix F, Part 1 of standard CCAR-25, with a 60s vertical burning test.

[0073] 2. Roller peel strength: Tested according to standard GB / T 1457-2022 Test method for peel strength of sandwich structure roller.

[0074] 3. Impact strength: Tested according to standard ASTM D 5420.

[0075] Table 1 Performance Test Results

[0076]

[0077] As shown in Table 1, the flame-retardant phenolic / glass fiber composite board prepared by this invention has good flame-retardant properties, with the extinguishing time controlled within 6 seconds, the charred length within 19-63 mm, and the dripping extinguishing time controlled within 3 seconds. When the flame-retardant phenolic / glass fiber composite board is applied to prepare honeycomb sandwich structure flooring, the extinguishing time is controlled within 2-9 seconds, the charred length within 42-77 mm, the dripping extinguishing time within 0-6 seconds, and the roller peel strength is 60.1-69.9 N·mm / mm. Moreover, the failure type is mostly epoxy film cohesive failure.

[0078] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included within the scope of the technical solution of the present invention.

Claims

1. A flame-retardant phenolic / glass fiber composite board, characterized in that, The composition comprises 60-70 wt% glass fiber cloth and 30-40 wt% resin cured on the glass fiber cloth. The resin composition consists of the following raw materials in parts by weight: 90-100 parts modified phenolic resin, 5-10 parts epoxy resin, 1-2 parts multifunctional epoxy compound, 1-3 parts toughening agent, and diluent. The amount of diluent is such that the viscosity of the resin composition at 25°C is 150-400 mPa·s. The modified phenolic resin is prepared by reacting phenol, modified phenol, and formaldehyde under the action of an alkaline catalyst. The modified phenol is prepared by transesterification of phenolic alkyl alcohol compounds with phosphonate monocarboxylic acid alkyl esters.

2. The flame-retardant phenolic / glass fiber composite board according to claim 1, characterized in that, The molar ratio of the phenolic alkyl alcohol compound to the phosphonate monocarboxylic acid alkyl ester is 1.1-1.2:

1.

3. The flame-retardant phenolic / glass fiber composite board according to claim 1, characterized in that, The phenolic alkyl alcohol compounds are selected from one or more of p-hydroxybenzyl alcohol, o-hydroxybenzyl alcohol, m-hydroxybenzyl alcohol, p-hydroxyphenylethanol, o-hydroxyphenylethanol, and 2-(3-hydroxyphenyl)ethanol; the phosphonate monocarboxylic acid alkyl esters are selected from one or more of dimethylphosphonoethyl acetate, diethyl phosphonoacetate, dimethyl [2-(methoxycarbonyl)ethyl] phosphate, trimethylphosphonoacetate, triethyl phosphonate, triethyl phosphonoacetate, triethyl phosphonoacetate, triethyl 4-phosphonobutyrate, triethyl 2-phosphonopropyl ester, and triethyl 2-phosphonobutyrate.

4. The flame-retardant phenolic / glass fiber composite board according to claim 1, characterized in that, The modified phenol is prepared by a method comprising the following steps: dissolving phenolic alkyl alcohol compounds and phosphonate monocarboxylic acid alkyl esters in an organic solvent, adding a catalyst, and reacting under reflux conditions to obtain the modified phenol.

5. The flame-retardant phenolic / glass fiber composite board according to claim 1, characterized in that, The molar ratio of phenol, modified phenol, and formaldehyde is 0.8-0.9:0.1-0.2:1.2-1.5; the alkaline catalyst is ammonia water with a concentration of 20-28wt%; the amount of alkaline catalyst is 3-5wt% of the total mass of phenol, modified phenol, and formaldehyde.

6. The flame-retardant phenolic / glass fiber composite board according to claim 1, characterized in that, The modified phenolic resin is prepared by a method comprising the following steps: adding phenol, modified phenol, formaldehyde, and alkaline catalyst into a reaction vessel, mixing, heating and reacting, and dehydrating to obtain the modified phenolic resin.

7. The flame-retardant phenolic / glass fiber composite board according to claim 6, characterized in that, The heating reaction is carried out at 50-95℃ for 2-5 hours; preferably, the heating is carried out at 50-75℃ for 1-3 hours, and then at 85-95℃ for 1-2 hours; the dehydration is carried out at 50-90℃ and a vacuum of 0.05-0.09MPa, and the gelation time of the dehydrated product is measured every 5-10 minutes. When the gelation time is 80-200 seconds at 150-160℃, the dehydration is completed.

8. The flame-retardant phenolic / glass fiber composite board according to claim 1, characterized in that, The multifunctional epoxy compound is selected from one or more combinations of trimethylolpropane triglycidyl ether, glycerol triglycidyl ether, triglycidyl-p-aminophenol, triglycidyl-m-aminophenol, and pentaerythritol glycidyl ether; the epoxy resin has an epoxy value of 0.44-0.55, specifically selected from one or more combinations of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and phenolic type epoxy resin; the glass fiber cloth is S glass fiber cloth or E glass fiber cloth, with a basis weight of 100-450 g / m². 2 The preferred weight is 100-300g / m³. 2 .

9. A method for preparing the flame-retardant phenolic / glass fiber composite board according to any one of claims 1-8, characterized in that, Includes the following steps: 1) Mix the modified phenolic resin, epoxy resin, toughening agent, and diluent to obtain a resin composition; 2) The glass fiber cloth and resin composition are impregnated, dried, cooled and wound up on an impregnation machine to obtain a prepreg; 3) Lay out prepreg and pre-cur it to obtain flame-retardant phenolic / glass fiber composite board.

10. The use of the flame-retardant phenolic / glass fiber composite board according to any one of claims 1-8 as a panel for aircraft flooring or cargo hold lining with a honeycomb sandwich structure formed by a secondary bonding method.

Images