Halogen-free fireproof aluminum-plastic composite board and preparation method thereof

Abstract

The application provides a halogen-free fireproof aluminum-plastic composite board and a preparation method thereof, and belongs to the technical field of building materials, and comprises an aluminum plate layer and a fireproof core layer located in the middle of the aluminum plate layer. The fireproof core layer comprises modified polyester resin and auxiliary additives, the modified polyester resin comprises the following components in parts by weight: terephthalic acid 40-60 parts, ethylene glycol 20-40 parts, fireproof monomer 5-10 parts and catalyst 1-3 parts, and the fireproof monomer is prepared by the reaction of 5-hydroxymethyl furfural and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide. The fireproof monomer of the application participates in the polycondensation reaction of polyester like terephthalic acid or ethylene glycol, and can simultaneously improve the fireproof effect and mechanical properties of the polyester resin.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a halogen-free fireproof aluminum-plastic composite panel and its preparation method. Background Technology

[0002] Aluminum-plastic composite panels are a type of building decoration material made of aluminum sheet layers and non-metallic core materials bonded together with a polymer adhesive. They combine the texture of metal with the lightness of plastic. With their advanced composite material structure and characteristics, excellent cost performance and easy processing, rich and varied decorative effects and durability, and significant resource conservation and environmental protection, they are widely used in building curtain walls, interior and exterior decoration, advertising signs, vehicle and ship decoration, furniture manufacturing and other fields.

[0003] The fire resistance of aluminum composite panels mainly depends on the flame retardant effect of their core material. In the existing technology, the core material of fireproof aluminum composite panels mainly uses polyethylene or polyurethane as the base material, and flame retardants are added to the base material. Among them, halogenated flame retardants are widely used as flame retardant additives because of their low price and high flame retardant efficiency. However, halogenated flame retardants release a large amount of toxic gases after combustion, which is very unfriendly to the environment. Summary of the Invention

[0004] In view of the above situation and to overcome the defects of the prior art, the purpose of this invention is to provide a halogen-free fireproof aluminum-plastic composite panel and its preparation method, so as to at least partially solve the problems mentioned in the background art.

[0005] The technical solution adopted in this invention is as follows:

[0006] The first aspect of this invention provides a halogen-free fireproof aluminum-plastic composite panel, comprising an upper aluminum plate layer, a lower aluminum plate layer, and a flame-retardant core layer located between the upper and lower aluminum plate layers. The flame-retardant core layer comprises a modified polyester resin and auxiliary additives. The modified polyester resin comprises the following components in parts by weight: 40-60 parts of terephthalic acid, 20-40 parts of ethylene glycol, 5-10 parts of flame-retardant monomer, and 1-3 parts of catalyst. The flame-retardant monomer is prepared by reacting 5-hydroxymethylfurfural with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0007] In some embodiments of the present invention, the amount of the auxiliary additives added is 1-5 wt% of the mass of the modified polyester resin, and the auxiliary additives include stabilizers, antioxidants and ultraviolet absorbers.

[0008] In some embodiments of the present invention, the catalyst is one of antimony trioxide, antimony acetate, and butyltin triisooctanoate.

[0009] A second aspect of this invention provides a method for preparing a halogen-free fireproof aluminum-plastic composite panel, comprising the following steps:

[0010] After the modified polyester resin and auxiliary additives are mixed evenly, they are added to an extruder, extruded and granulated, and then plasticized into sheets to obtain a flame-retardant core layer.

[0011] The flame-retardant core layer is bonded between the aluminum plate layers to obtain a halogen-free fireproof aluminum-plastic composite panel.

[0012] In some embodiments of the present invention, the method for preparing the modified polyester resin includes the following steps:

[0013] Under a nitrogen atmosphere, terephthalic acid, flame retardant monomer, ethylene glycol and catalyst are added sequentially to a reactor for esterification. After the reaction is completed, stirring is continued for 20-30 minutes, followed by polycondensation. After the reaction is completed, modified polyester resin is obtained.

[0014] In some embodiments of the present invention, the esterification reaction is carried out under the following conditions: pressure 0.2-0.4 MPa, temperature 220-230°C, and time 1-3 h.

[0015] In some embodiments of the present invention, the conditions for the polycondensation reaction are a pressure of 0.7-0.8 MPa, a temperature of 240-280°C, and a time of 4-6 h.

[0016] In some embodiments of the present invention, the method for preparing the flame-retardant monomer includes the following steps:

[0017] 5-Hydroxymethylfurfural and ethanol were added to a reaction vessel and stirred thoroughly. Then 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added. The mixture was heated to 80-85℃ and reacted for 10-20 h under a nitrogen atmosphere. After the reaction was completed, the mixture was cooled to room temperature. The product was washed and dried to obtain the flame-retardant monomer.

[0018] In some embodiments of the present invention, the mass ratio of 5-hydroxymethylfurfural to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:(1.5-2).

[0019] In some embodiments of the present invention, the amount of 5-hydroxymethylfurfural added to ethanol is 50-80 g / L.

[0020] The beneficial effects achieved by this invention are as follows:

[0021] This invention prepares a flame-retardant monomer by nucleophilic addition of the aldehyde group of 5-hydroxymethylfurfural to the pH bond of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), thereby improving the compatibility of DOPO with polyester resin. At the same time, highly reactive hydroxyl groups are introduced into DOPO, enabling the flame-retardant monomer to participate in the polycondensation reaction of polyester like terephthalic acid or ethylene glycol, thus simultaneously improving the flame-retardant effect and mechanical properties of polyester resin. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0024] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0025] In view of the deficiencies in the prior art mentioned in the background, the first aspect of the present invention provides a halogen-free fireproof aluminum-plastic composite panel, comprising an upper aluminum plate layer, a lower aluminum plate layer, and a flame-retardant core layer located between the upper and lower aluminum plate layers. The flame-retardant core layer comprises a modified polyester resin and auxiliary additives. The modified polyester resin comprises the following components in parts by weight: 40-60 parts of terephthalic acid, 20-40 parts of ethylene glycol, 5-10 parts of flame-retardant monomer, and 1-3 parts of catalyst. The flame-retardant monomer is prepared by reacting 5-hydroxymethylfurfural with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0026] 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) is a highly efficient phosphorus-based flame retardant monomer with a two-phase flame retardant mechanism involving both gas and condensed phases. However, its compatibility with polyester resins is limited, and when used alone as an additional flame retardant additive, it requires a relatively high dosage, which can affect the mechanical properties of the material. 5-Hydroxymethylfurfural (HMF) is a furanyl molecule derived from biomass. Its heteroatomic furan ring, aldehyde group, and hydroxymethyl group give it high chemical reactivity. This invention prepares a flame retardant monomer by nucleophilic addition of the aldehyde group of HMF to the PH bond of DOPO, improving the compatibility of DOPO with polyester resins. Simultaneously, highly reactive hydroxyl groups are introduced into DOPO, allowing the flame retardant monomer to participate in the polycondensation reaction of polyesters like terephthalic acid or ethylene glycol, thereby simultaneously improving both the flame retardant effect and mechanical properties of the polyester resin.

[0027] In some embodiments, the amount of auxiliary additives added is 1-5 wt% of the modified polyester resin. These auxiliary additives include stabilizers, antioxidants, and UV absorbers. The heat stabilizers (e.g., triphenyl phosphate, triethyl phosphonoacetate) are mainly used to prevent thermal decomposition of the polyester during high-temperature processing (such as melt extrusion, injection molding), thus improving processing stability. The antioxidants (e.g., phosphite antioxidant 1024) can prevent oxidative aging of the polyester during use by capturing free radicals or decomposing peroxides. The UV absorbers (e.g., benzotriazole UVA) prevent photo-oxidative degradation of the polyester under outdoor sunlight by absorbing ultraviolet light and converting it into heat energy.

[0028] In some embodiments, the catalyst is one of antimony trioxide, antimony acetate, and butyltin triisooctanoate. The catalyst can improve the reaction efficiency in the polyester resin preparation process. Antimony trioxide has a large specific surface area, uniform dispersion, numerous active sites, high catalytic efficiency, and is inexpensive. Antimony acetate is readily soluble in ethylene glycol at room temperature, requiring no high-temperature pretreatment, and can be directly fed to avoid pipeline blockage, exhibiting strong process adaptability. Butyltin triisooctanoate can inhibit polyester discoloration and is relatively environmentally friendly.

[0029] A second aspect of this invention provides a method for preparing a halogen-free fireproof aluminum-plastic composite panel, comprising the following steps:

[0030] After the modified polyester resin and auxiliary additives are mixed evenly, they are added to an extruder, extruded and granulated, and then plasticized into sheets to obtain a flame-retardant core layer.

[0031] The flame-retardant core layer is bonded between the aluminum plate layers to obtain a halogen-free fireproof aluminum-plastic composite panel.

[0032] The flame-retardant core layer is extruded, granulated, and plasticized into sheets, which can improve the uniformity of the flame-retardant core layer. The core layer is bonded to the aluminum plate with an adhesive layer, which can produce an aluminum-plastic composite panel with high peel strength and impact resistance, thus improving the service life of the aluminum-plastic composite panel.

[0033] In some embodiments, the method for preparing the modified polyester resin includes the following steps:

[0034] Under a nitrogen atmosphere, terephthalic acid, flame retardant monomer, ethylene glycol and catalyst are added sequentially to a reactor for esterification. After the reaction is completed, stirring is continued for 20-30 minutes, followed by polycondensation. After the reaction is completed, modified polyester resin is obtained.

[0035] By directly adding flame-retardant monomers during the esterification reaction stage, the -OH group of the flame-retardant monomers reacts with the -COOH group of terephthalic acid or the -OH group of ethylene glycol, thereby embedding the flame-retardant monomers into the polyester backbone. Then, through polycondensation reaction, the molecular weight of the polyester can be increased, allowing the modified polyester resin to form a dense char layer during combustion, further enhancing the flame-retardant effect of the modified polyester resin.

[0036] In some embodiments, the esterification reaction conditions are a pressure of 0.2-0.4 MPa, a temperature of 220-230°C, and a time of 1-3 hours. By controlling the pressure, temperature, and time of the esterification reaction within appropriate ranges, it is beneficial to increase the rate of the esterification reaction and make the reaction more complete.

[0037] In some embodiments, the conditions for the polycondensation reaction are a pressure of 0.7-0.8 MPa, a temperature of 240-280°C, and a time of 4-6 hours. By controlling the pressure, temperature, and time of the polycondensation reaction within appropriate ranges, it is beneficial to increase the rate of the polycondensation reaction and promote the shift of the polycondensation equilibrium towards higher molecular weight products.

[0038] In some embodiments, the method for preparing flame-retardant monomers includes the following steps:

[0039] 5-Hydroxymethylfurfural and ethanol were added to a reaction vessel and stirred thoroughly. Then 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added. The mixture was heated to 80-85℃ and reacted for 10-20 h under a nitrogen atmosphere. After the reaction was completed, the mixture was cooled to room temperature. The product was washed and dried to obtain the flame-retardant monomer.

[0040] Flame retardant monomers can be prepared by a one-pot method using ethanol as a solvent, under a nitrogen atmosphere and at a temperature of 80-85°C, through nucleophilic addition of the pH bond of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to the aldehyde group of 5-hydroxymethylfurfural.

[0041] In some embodiments, the mass ratio of 5-hydroxymethylfurfural to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:(1.5-2). By setting the mass ratio of 5-hydroxymethylfurfural to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to 1:(1.5-2), the reaction between 5-hydroxymethylfurfural and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide can be made more complete, allowing the reaction to proceed more thoroughly.

[0042] In some embodiments, the amount of 5-hydroxymethylfurfural added to ethanol is 50-80 g / L. Using ethanol as the reaction solvent, setting the amount of 5-hydroxymethylfurfural added to ethanol to 50-80 g / L ensures complete dissolution of the 5-hydroxymethylfurfural, thereby improving reaction efficiency.

[0043] The present invention will be further described below by way of specific embodiments.

[0044] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods already existing in the art; unless otherwise specified, the experimental materials used in the following embodiments are all purchased from commercial channels.

[0045] Example 1:

[0046] 5-Hydroxymethylfurfural and ethanol were added to a reaction vessel at a concentration of 50 g / L. The mixture was stirred thoroughly, and then 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added. The mass ratio of 5-hydroxymethylfurfural to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was 1:1.5. The mixture was heated to 80 °C and reacted for 10 h under a nitrogen atmosphere. After the reaction was completed, the mixture was cooled to room temperature, and the product was washed and dried to obtain the flame-retardant monomer.

[0047] Under a nitrogen atmosphere, 40 parts by weight of terephthalic acid, 5 parts by weight of flame retardant monomer, 20 parts by weight of ethylene glycol and 1 part by weight of catalyst were added to a reactor. Esterification reaction was carried out for 1 hour at a pressure of 0.2 MPa and a temperature of 220 °C. After the reaction was completed, stirring was continued for 20 minutes. Then, polycondensation reaction was carried out for 4 hours at a pressure of 0.7 MPa and a temperature of 240 °C. After the reaction was completed, modified polyester resin was obtained.

[0048] After the modified polyester resin and auxiliary additives are mixed evenly, they are added to the extruder. The amount of auxiliary additives added is 1 wt% of the mass of the modified polyester resin. After extrusion granulation and plasticizing into sheets, a flame-retardant core layer is obtained.

[0049] The flame-retardant core layer is then bonded between the aluminum plate layers to obtain a halogen-free fireproof aluminum-plastic composite panel.

[0050] Example 2:

[0051] 5-Hydroxymethylfurfural and ethanol were added to a reaction vessel at a concentration of 80 g / L. The mixture was stirred thoroughly, and then 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added. The mass ratio of 5-hydroxymethylfurfural to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was 1:2. The mixture was heated to 85°C and reacted for 20 h under a nitrogen atmosphere. After the reaction was completed, the mixture was cooled to room temperature, and the product was washed and dried to obtain the flame-retardant monomer.

[0052] Under a nitrogen atmosphere, 60 parts by weight of terephthalic acid, 10 parts by weight of flame retardant monomer, 40 parts by weight of ethylene glycol and 3 parts by weight of catalyst were added to a reactor. The esterification reaction was carried out at a pressure of 0.4 MPa and a temperature of 230 °C for 3 hours. After the reaction was completed, the mixture was stirred for 30 minutes. Then, the polycondensation reaction was carried out at a pressure of 0.8 MPa and a temperature of 280 °C for 6 hours. After the reaction was completed, the modified polyester resin was obtained.

[0053] After the modified polyester resin and auxiliary additives are mixed evenly, they are added to the extruder. The amount of auxiliary additives added is 5 wt% of the mass of the modified polyester resin. After extrusion granulation and plasticizing into sheets, a flame-retardant core layer is obtained.

[0054] The flame-retardant core layer is then bonded between the aluminum plate layers to obtain a halogen-free fireproof aluminum-plastic composite panel.

[0055] Example 3:

[0056] 5-Hydroxymethylfurfural and ethanol were added to a reaction vessel at a concentration of 65 g / L. The mixture was stirred thoroughly, and then 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added. The mass ratio of 5-hydroxymethylfurfural to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was 1:1.7. The mixture was heated to 85°C and reacted for 15 h under a nitrogen atmosphere. After the reaction was completed, the mixture was cooled to room temperature, and the product was washed and dried to obtain the flame-retardant monomer.

[0057] Under a nitrogen atmosphere, 50 parts by weight of terephthalic acid, 8 parts by weight of flame retardant monomer, 20-40 parts by weight of ethylene glycol and 2 parts by weight of catalyst were added to a reactor. The esterification reaction was carried out at a pressure of 0.3 MPa and a temperature of 225 °C for 2 hours. After the reaction was completed, the mixture was stirred for 25 minutes. Then, the polycondensation reaction was carried out at a pressure of 0.7 MPa and a temperature of 260 °C for 5 hours. After the reaction was completed, the modified polyester resin was obtained.

[0058] After the modified polyester resin and auxiliary additives are mixed evenly, they are added to the extruder. The amount of auxiliary additives added is 3 wt% of the mass of the modified polyester resin. After extrusion granulation and plasticizing into sheets, a flame-retardant core layer is obtained.

[0059] The flame-retardant core layer is then bonded between the aluminum plate layers to obtain a halogen-free fireproof aluminum-plastic composite panel.

[0060] Comparative Example 1:

[0061] Consistent with Example 1, except that 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is used instead of the flame retardant monomer.

[0062] Comparative Example 2:

[0063] Consistent with Example 1, except that no flame retardant monomer is added.

[0064] Tests were conducted on Examples 1-3 and Comparative Examples 1 and 2. The specific test contents are as follows:

[0065] Mechanical property testing: The flame-retardant core layer was tested according to "Determination of Tensile Properties of Plastics". A tensile testing machine was used to stretch the sample at a constant speed along the longitudinal main axis until the sample broke. The load and elongation of the sample during this process were measured and recorded. The gauge length of the sample was 75 mm, the thickness was 4 ± 0.2 mm, and the tensile speed was 10 ± 5 mm / min.

[0066] Limiting Oxygen Index (LOI) Test: According to the "Test Method for Burning Performance of Plastics - Oxygen Index Method" (GB / T2406-93), a flat vulcanizing apparatus is used to heat and melt the flame-retardant core layer and press it into a sheet. The sheet is then placed on a critical oxygen index analyzer, and the oxygen concentration is adjusted before a combustion test is conducted. After multiple experiments to reduce errors, the limiting oxygen index of the sample is obtained.

[0067] Vertical burning performance test: According to the "Test Method for Flame Retardant Properties - Vertical Burning Method" (GB2409-84), the sample to be tested was pressed into a strip using a miniature injection molding machine. The strip was fixed at a position 30.0 cm away from the base, and a 0.5 cm thick layer of degreased cotton was placed at the base. A flame source was continuously applied to the bottom of the strip for 10 seconds, and after the strip extinguished, the flame source was applied for another 10 seconds. The experimental phenomena and data were recorded and compared with the vertical burning level reference standard.

[0068] The test results are shown in Table 1.

[0069] Table 1

[0070]

[0071] Referring to the test results in Table 1, Example 1 showed a significant improvement in mechanical properties compared to Comparative Example 1, indicating that flame retardant monomers can improve the mechanical properties of polyester resin by participating in the reaction of polyester resin. Example 1 also showed a significant improvement in flame retardant properties compared to Comparative Example 2, indicating that the addition of flame retardant monomers can significantly improve the flame retardant properties of polyester resin.

[0072] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0073] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the protection scope of the present invention.

Claims

1. A halogen-free fireproof aluminum-plastic composite panel, characterized in that, The material comprises an upper aluminum plate layer, a lower aluminum plate layer, and a flame-retardant core layer located between the upper and lower aluminum plate layers. The flame-retardant core layer comprises a modified polyester resin and auxiliary additives. The modified polyester resin is prepared from components comprising the following parts by weight: 40-60 parts of terephthalic acid, 20-40 parts of ethylene glycol, 5-10 parts of flame-retardant monomer, and 1-3 parts of catalyst. The flame-retardant monomer is prepared by reacting 5-hydroxymethylfurfural with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

2. The halogen-free fireproof aluminum-plastic composite panel according to claim 1, characterized in that, The amount of the auxiliary additives added is 1-5 wt% of the modified polyester resin, and the auxiliary additives include stabilizers, antioxidants and ultraviolet absorbers.

3. The halogen-free fireproof aluminum-plastic composite panel according to claim 1, characterized in that, The catalyst is one of antimony trioxide, antimony acetate, and butyltin triisooctanoate.

4. A method for preparing a halogen-free fireproof aluminum-plastic composite panel according to any one of claims 1-3, characterized in that, Includes the following steps: After the modified polyester resin and auxiliary additives are mixed evenly, they are added to an extruder, extruded and granulated, and then plasticized into sheets to obtain a flame-retardant core layer. The flame-retardant core layer is bonded between the aluminum plate layers to obtain a halogen-free fireproof aluminum-plastic composite panel.

5. The preparation method according to claim 4, characterized in that, The method for preparing the modified polyester resin includes the following steps: Under a nitrogen atmosphere, terephthalic acid, flame retardant monomer, ethylene glycol and catalyst are added sequentially to a reactor for esterification. After the reaction is completed, stirring is continued for 20-30 minutes, followed by polycondensation. After the reaction is completed, modified polyester resin is obtained.

6. The preparation method according to claim 5, characterized in that, The esterification reaction is carried out under the following conditions: pressure 0.2-0.4 MPa, temperature 220-230℃, and time 1-3 h.

7. The preparation method according to claim 5, characterized in that, The conditions for the polycondensation reaction are a temperature of 240-280℃ and a time of 4-6 hours.

8. The preparation method according to claim 5, characterized in that, The preparation method of the flame-retardant monomer includes the following steps: 5-Hydroxymethylfurfural and ethanol were added to a reaction vessel and stirred thoroughly. Then 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added. The mixture was heated to 80-85℃ and reacted for 10-20 h under a nitrogen atmosphere. After the reaction was completed, the mixture was cooled to room temperature. The product was washed and dried to obtain the flame-retardant monomer.

9. The preparation method according to claim 8, characterized in that, The mass ratio of 5-hydroxymethylfurfural to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:(1.5-2).

10. The preparation method according to claim 8, characterized in that, The amount of 5-hydroxymethylfurfural added to ethanol is 50-80 g / L.

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