CN112297531A

CN112297531A - Production process of heat-insulating anti-radiation laminated glass film

Info

Publication number: CN112297531A
Application number: CN202011182905.7A
Authority: CN
Inventors: 黄涛; 王久英
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-03-21
Filing date: 2019-03-21
Publication date: 2021-02-02
Also published as: CN109927356B; CN109927356A

Abstract

The invention discloses a production process of a heat-insulating and anti-radiation laminated glass film, which comprises the following components in parts by weight: 73-79 parts of high-strength epoxy resin, 6-7 parts of perfluoroalkyl ether quaternary ammonium salt, 5-8 parts of polyether silicone oil, 16-18 parts of silica sol, 26-28 parts of boron-rich curing agent and 220 parts of dimethyl sulfoxide 210-220. According to the invention, the film coating agent with radiation resistance and low thermal conductivity is prepared, then the film coating agent is coated between two layers of glass, and the two layers of glass are bonded and fixed through the film coating agent, so that a glass film is formed between the two layers of glass, the glass film has radiation resistance and thermal insulation performance, further the prepared double-layer glass has higher radiation resistance and thermal insulation performance, and meanwhile, the glass film in the double-layer glass can not be scratched or peeled off under the action of external force through the protection of the two layers of glass, so that the service life of the thermal insulation radiation resistant glass is prolonged.

Description

Production process of heat-insulating anti-radiation laminated glass film

The present application is a divisional application of the following applications: application No.: 201910218831.9, title of the invention: an insulating and anti-radiation laminated glass film and a production process thereof.

Technical Field

The invention belongs to the field of glass film preparation, and relates to a production process of a heat-insulating anti-radiation sandwich glass film.

Background

Radiation protection glass refers to special glass with the function of protecting radioactive rays such as x-rays and gamma-rays, and in recent years, with the development of the fields of radiation medicine, atomic energy industry and the like, the problem of radiation protection is also widely noticed, the radioactive rays such as x-rays and gamma-rays belong to high-energy electromagnetic waves, when the rays pass through different media, the atoms of the media can be ionized, and the shorter the wavelength of the electromagnetic waves is, the stronger the penetration capability of the electromagnetic waves is. Since the wavelength of the radiation is of the same order of magnitude as the size of the atoms, the molecular absorption coefficient can be obtained by adding the atomic absorption coefficients of the elements constituting the molecule. Therefore, the mass absorption coefficients of the various oxides constituting the glass can be calculated on this principle. The composition of the common glass can not effectively absorb the rays, a large amount of elements with high atomic number must be introduced into the composition of the glass to improve the absorption capacity of the glass, but the radiation-resistant substance is directly added into the glass, so that the manufacturing cost of the whole glass is higher, the radiation-resistant substance is easily distributed unevenly in the preparation process of the glass, and further the radiation-resistant performance of stripping is unevenly distributed.

In the prior art, in order to reduce the cost, a layer of anti-radiation film is usually directly compounded on the surface of glass, but under the condition of long-term use, the anti-radiation film is easy to scratch and peel under the action of external force, so that the appearance of the glass is influenced, and the anti-radiation performance of peeling is reduced at the same time.

Disclosure of Invention

The invention aims to provide a production process of a heat-insulating and anti-radiation laminated glass film, which comprises the steps of preparing a film covering agent with anti-radiation and low heat-conducting properties, then coating a film coating agent between two layers of glass, bonding and fixing the two layers of glass through the film coating agent, so that a glass film is formed between the two layers of glass, the glass film has the radiation resistance and the heat insulation performance, so that the prepared double-layer glass has higher radiation resistance and heat insulation performance, and simultaneously, the glass film in the double-layer glass can not be scratched or peeled off under the action of external force through the protection of the two layers of glass, thereby prolonging the service life of the heat-insulating and anti-radiation glass, solving the problem that the prior art directly compounds a layer of anti-radiation film on the surface of the glass, but the anti-radiation film is easy to scratch and peel under the action of external force under the long-term use condition, not only affecting the aesthetic appearance of the glass, but also causing the radiation resistance of the peeling to be simultaneously reduced.

The purpose of the invention can be realized by the following technical scheme:

a heat-insulating and anti-radiation laminated glass film comprises the following components in parts by weight:

73-79 parts of high-strength epoxy resin, 6-7 parts of perfluoroalkyl ether quaternary ammonium salt, 5-8 parts of polyether silicone oil, 16-18 parts of silica sol, 26-28 parts of boron-rich curing agent and 220 parts of dimethyl sulfoxide 210-220;

the specific preparation process of the high-strength epoxy resin is as follows:

step 1: adding melamine into methanol, stirring, mixing and dissolving, heating to 80-90 ℃, then dropwise adding p-hydroxybenzaldehyde into a reaction vessel, stirring vigorously while dropwise adding, keeping the temperature unchanged during the dropwise adding process, reacting at constant temperature for 13-15h after completely dropwise adding, then reducing to room temperature, separating out solids, filtering, washing with methanol and acetone in sequence, and drying to obtain a powder product; the amino in the melamine can perform nucleophilic addition reaction with aldehyde group in the p-hydroxybenzaldehyde to form imino, wherein-C ═ N-double bond of the imino and a benzene ring form a conjugated system between the melamine and a main ring of the p-hydroxybenzaldehyde, so that the strength and the toughness of the product can be improved; wherein the ratio of the amount of melamine to hydroxybenzaldehyde species is 1: 3.1-3.2;

step 2: adding the powder product prepared in the step 1 into dimethyl sulfoxide, stirring and dissolving, heating to 80-90 ℃, adding sodium hydroxide into a reaction vessel, mixing for 3-5min, adding glycerol triglycidyl ether, reacting at constant temperature for 10-12h, evaporating to remove the solvent, washing with water and ethanol respectively, and drying to obtain high-strength epoxy resin powder; wherein 0.29-0.3g of sodium hydroxide is added into each gram of powder product, 10-12mL of dimethyl sulfoxide is added, and 1.86-1.89g of glycerol triglycidyl ether is added into each gram of powder product; the phenolic hydroxyl groups in three directions on the benzene ring of the powder product and the epoxy groups in three directions of the glycerol triglycidyl ether are subjected to ring-opening reaction to form a polymer, and the phenolic hydroxyl groups are in three different directions and the epoxy groups are in three different directions, so that the polymer forms a hyperbranched reticular structure, the dispersion performance and the curing efficiency of the polymer are improved, and meanwhile, the powder product has high strength and toughness, so that the strength and the toughness of the polymer can be improved;

the preparation process of the boron-rich curing agent is as follows:

adding 4-aminophenol and dimethylformamide into a reaction kettle, adding sodium bicarbonate into the reaction kettle to adjust the pH of the solution to be 9-10, then adding 9-fluorenylmethylchloroformate into the reaction solution, controlling the pH of the reaction solution to be 9-10 in the reaction process, stirring and reacting for 8-10h at normal temperature, then carrying out reduced pressure distillation on the obtained solution, recovering the solvent, and using NaHSO with the pH of 2-3 to obtain a solid product₄Washing and drying the solution to obtain a product A; wherein 13-15mL of dimethylformamide is added into each gram of 4-aminophenol, and 2.39-2.41g of 9-fluorenylmethyl chloroformate is added;

adding the product A prepared in the step I and boric acid solution with the concentration of 5% into acetone, heating to 90-100 ℃, reacting for 14-18h at constant temperature, evaporating to remove the solvent, washing the obtained powder product with ethanol, and drying to obtain a product B; boric acid reacts with phenolic hydroxyl in the product A, so that boron is introduced into the product B to form boronized organic matter, and the prepared product B has certain radiation protection performance because the boronized organic matter can absorb rays to realize radiation protection; wherein, 1.5 to 1.8g of boric acid solution with the concentration of 5 percent is added into each gram of the product A;

thirdly, adding concentrated ammonia water, dioxane and a 4mol/L NaOH solution according to the volume ratio of 30-32: 9-10: 1, adding the product B prepared in the step II into the mixed solution, stirring and reacting for 20-22h at normal temperature, filtering, and washing and drying by using water and ethanol in sequence to obtain a boron-rich curing agent; adding 1g of the product B into every 6-7mL of the mixed solution;

a production process of a heat-insulating and anti-radiation laminated glass film comprises the following specific production processes:

adding high-strength epoxy resin into dimethyl sulfoxide, adding perfluoroalkyl ether quaternary ammonium salt, polyether silicone oil and silica sol after uniform mixing, stirring and uniformly mixing, then adding a boron-rich curing agent, and stirring and uniformly mixing at normal temperature to obtain a viscous film covering agent; because the high-strength epoxy resin is a hyperbranched structure and has good dispersibility, after the perfluoroalkyl ether quaternary ammonium salt, the polyether silicone oil and the silica sol are mixed with the high-strength epoxy resin, can be uniformly dispersed in resin, and three amino groups in the boron-rich curing agent are uniformly distributed in three directions, when reacting with high-strength epoxy resin, the boron-rich curing agent and the high-strength epoxy resin hyperbranched network structure are subjected to cross-linking reaction, so that the gaps of the net structure are smaller, the perfluoroalkyl ether quaternary ammonium salt, polyether silicone oil and silica sol are uniformly coated in the net structure framework, the addition of the perfluoroalkyl ether quaternary ammonium salt and the polyether silicone oil leads fluorine elements and silicon elements to be introduced into the film-coating liquid, the film coating solution has certain aging resistance and thermal stability, and the silica sol has a lower heat conductivity coefficient, so that the heat conductivity coefficient of the film coating solution is reduced by adding the silica sol;

and secondly, quickly coating the film laminating machine prepared in the first step on the surface of bottom glass, wherein the spraying thickness is 0.1-0.15mm, peeling off and placing in a drying chamber at 50-60 ℃ after spraying, drying until the film laminating liquid is solidified, forming a layer of semitransparent adhesive glass film on the peeled surface of the bottom layer, then pressing the bottom surface of the top glass on the surface of the adhesive glass film, fixing through the adhesive effect of the adhesive film, peeling off the compounded double layers, placing at room temperature, and drying for 3-4 days to obtain the double-layer adhesive glass.

The invention has the beneficial effects that:

according to the invention, the film coating agent with radiation resistance and low thermal conductivity is prepared, then the film coating agent is coated between two layers of glass, and the two layers of glass are bonded and fixed through the film coating agent, so that a glass film is formed between the two layers of glass, the glass film has radiation resistance and thermal insulation performance, further the prepared double-layer glass has higher radiation resistance and thermal insulation performance, meanwhile, the glass film in the double-layer glass can not be scratched or stripped under the action of external force through the protection of the two layers of glass, further the service life of the thermal insulation radiation-resistant glass is prolonged, the problem that the radiation-resistant film is directly compounded on the surface of the glass in the prior art, but the situation that the scratch and the stripping of the radiation-resistant film are easy to occur under the action of external force under the long-term use condition is solved, the attractiveness of the glass is influenced, and the stripped.

The high-strength epoxy resin prepared by the invention is a hyperbranched structure and has good dispersibility, the perfluoroalkyl ether quaternary ammonium salt, the polyether silicone oil and the silica sol can be uniformly dispersed in the resin after being mixed with the high-strength epoxy resin, simultaneously three amino groups in the boron-rich curing agent are uniformly distributed in three directions, when the boron-rich curing agent reacts with the high-strength epoxy resin, the boron-rich curing agent and the high-strength epoxy resin hyperbranched network structure are subjected to a cross-linking reaction, so that gaps of the network structure are smaller, the perfluoroalkyl ether quaternary ammonium salt, the polyether silicone oil and the silica sol are uniformly coated in a network structure, the addition of the perfluoroalkyl ether quaternary ammonium salt and the polyether silicone oil leads fluorine elements and silicon elements to be introduced into the membrane covering solution, further the membrane covering solution has certain aging resistance and thermal stability, meanwhile, the silica sol has lower heat conductivity coefficient, and the addition of the membrane covering solution reduces, and the prepared glass film has high heat insulation performance and uniform heat insulation dispersion.

The boron-rich curing agent prepared by the invention contains boron element, so that the curing agent has high radiation resistance, and the boron element is uniformly distributed on a skeleton structure after being crosslinked and cured with high-strength epoxy resin, so that the prepared glass film has high radiation resistance and the radiation resistance is uniformly distributed.

Drawings

In order to facilitate understanding for those skilled in the art, the present invention will be further described with reference to the accompanying drawings.

FIG. 1 is a reaction scheme in the preparation of the powder product of the present invention;

FIG. 2 is a reaction structural formula in the preparation process of the boron-rich curing agent.

Detailed Description

Please refer to fig. 1 and fig. 2, which are described in detail with reference to the following embodiments:

example 1

step 1: adding 1.26kg of melamine into 20L of methanol, stirring, mixing and dissolving, heating to 80-90 ℃, then dropwise adding 3.78kg of p-hydroxybenzaldehyde into a reaction vessel, violently stirring while dropwise adding, keeping the temperature unchanged during dropwise adding, reacting at constant temperature for 13-15h after completely dropwise adding, then reducing to room temperature, separating out solids, washing with methanol and acetone in sequence after filtering, and drying to obtain a powder product;

step 2: adding 1kg of the powder product prepared in the step 1 into 10L of dimethyl sulfoxide, stirring and dissolving, heating to 80-90 ℃, then adding 0.29kg of sodium hydroxide into a reaction vessel, mixing for 3-5min, adding 1.86kg of glycerol triglycidyl ether, reacting for 10-12h at constant temperature, evaporating to remove the solvent, and then washing and drying with water and ethanol respectively to obtain the high-strength epoxy resin powder.

Example 2

step 1: adding 1.26kg of melamine into 20L of methanol, stirring, mixing and dissolving, heating to 80-90 ℃, then dropwise adding 2.44kg of p-hydroxybenzaldehyde into a reaction vessel, violently stirring while dropwise adding, keeping the temperature unchanged during dropwise adding, reacting at constant temperature for 13-15h after completely dropwise adding, then reducing to room temperature, separating out solids, washing with methanol and acetone in sequence after filtering, and drying to obtain a powder product;

Example 3

The preparation process of the boron-rich curing agent is as follows:

adding 1kg of 4-aminophenol and 13L of dimethylformamide into a reaction kettle, adding sodium bicarbonate into the reaction kettle to adjust the pH of the solution to be 9-10, then adding 2.39kg of 9-fluorenylmethylchloroformate into the reaction solution, controlling the pH of the reaction solution to be 9-10 during the reaction, stirring and reacting for 8-10h at normal temperature, then carrying out reduced pressure distillation on the obtained solution, recovering the solvent, and using NaHSO with the pH of 2-3 to obtain a solid product₄Washing and drying the solution to obtain a product A; wherein 13-15mL of dimethylformamide is added into each gram of 4-aminophenol, and 2.39-2.41g of 9-fluorenylmethyl chloroformate is added;

adding 1kg of the product A prepared in the step I and 1.5kg of boric acid solution with the concentration of 5% into acetone, heating to 90-100 ℃, reacting for 14-18h at constant temperature, evaporating to remove the solvent, washing the obtained powder product with ethanol, and drying to obtain a product B;

thirdly, adding concentrated ammonia water, dioxane and a 4mol/L NaOH solution according to the volume ratio of 30-32: 9-10: 1, adding 1kg of the product B prepared in the step II into 6L of the mixed solution, stirring and reacting for 20-22h at normal temperature, filtering, washing with water and ethanol in sequence, and drying to obtain the boron-rich curing agent.

Example 4

step one, adding 7.3kg of the high-strength epoxy resin prepared in the embodiment 1 into 21kg of dimethyl sulfoxide, adding 0.6kg of perfluoroalkyl ether quaternary ammonium salt, 0.5kg of polyether silicone oil and 1.6kg of silica sol after uniformly mixing, stirring and uniformly mixing, then adding 2.6kg of the boron-rich curing agent prepared in the embodiment 3, and stirring and uniformly mixing at normal temperature to obtain a viscous film covering agent;

and secondly, quickly coating the film laminating machine prepared in the first step on the surface of the bottom layer glass, wherein the spraying thickness is 0.1-0.15mm, placing the film in a drying chamber at 50-60 ℃ after spraying, drying until the film laminating liquid is solidified, forming a layer of semitransparent adhesive glass film on the surface peeled from the bottom layer, then pressing the bottom surface of the top layer glass on the surface of the adhesive glass film, fixing the glass film through the adhesive effect of the adhesive film, and then peeling and placing the compounded double layers for airing at room temperature for 3-4 days to obtain the double-layer adhesive glass.

Example 5

step one, adding 7.3kg of the high-strength epoxy resin prepared in the embodiment 2 into 21kg of dimethyl sulfoxide, adding 0.6kg of perfluoroalkyl ether quaternary ammonium salt, 0.5kg of polyether silicone oil and 1.6kg of silica sol after uniformly mixing, stirring and uniformly mixing, then adding 2.6kg of the boron-rich curing agent prepared in the embodiment 3, and stirring and uniformly mixing at normal temperature to obtain a viscous film covering agent;

Example 6

step one, adding 7.3kg of the high-strength epoxy resin prepared in example 2 into 21kg of dimethyl sulfoxide, uniformly mixing, adding 0.6kg of perfluoroalkyl ether quaternary ammonium salt, 0.5kg of polyether silicone oil, 1.6kg of silica sol and 1.82kg of 5% boric acid solution, uniformly stirring and mixing, then adding 2.6kg of 1,3, 5-triaminobenzene, and uniformly stirring and mixing at normal temperature to obtain a viscous film coating agent;

Example 7

step one, adding 7.3kg of bisphenol A epoxy resin into 21kg of dimethyl sulfoxide, adding 0.6kg of perfluoroalkyl ether quaternary ammonium salt, 0.5kg of polyether silicone oil and 1.6kg of silica sol after uniformly mixing, stirring and uniformly mixing, then adding 2.6kg of the boron-rich curing agent prepared in the embodiment 3, stirring and uniformly mixing at normal temperature to obtain a viscous film covering agent;

Example 8

And (5) bonding and fixing the double-layer glass by using glass cement to obtain the double-layer glass.

Example 9

(1) The double-layer bonded glass prepared in examples 4 to 7 was subjected to a radiation resistance test as follows: 3 points were taken at 3 different positions on the surface of the double-glazing prepared in examples 4 to 7, one point was taken at random on the surface of the double-glazing prepared in example 8, 3 points of the glass in examples 4 to 7 and the first point in example 8 were measured by a digital medical X-ray radiography system, and attenuation ratios were calculated to evaluate the X-ray resistance thereof, and the results are shown in table 1, in which the attenuation ratio r is (a1-a0)/a1 × 100%, in which a1 represents the results of weighted average gray values at three points in the double-glazing prepared in examples 4 to 7; a0 is the result of weighted average gray scale values at one point in example 8;

table 1: results of testing radiation resistance of the double-glazing produced in examples 4 to 7

	Example 4	Example 5	Example 6	Example 7
					At point 1	82.31％	82.14％	46.26％	69.56％
At point 2	82.29％	58.31％	87.29％	82.24％
					At point 3	82.31％	63.25％	31.33％	59.38％

As can be seen from table 1, the film coating agent between the two layers of bonded glass prepared in example 4 is prepared by a curing reaction of a high-strength epoxy resin and a boron-containing curing agent, and since the boron-containing curing agent contains boron, the boron-containing curing agent itself has a high radiation resistance, and since the high-strength epoxy resin is a hyperbranched structure, the boron-containing curing agent is uniformly distributed during curing and crosslinking, and since the curing agent itself has a radiation resistance, a large amount of boron is uniformly distributed in a network skeleton of the prepared film coating agent after being cured by crosslinking with the epoxy resin, so that the prepared glass film rejects the high radiation resistance, and the radiation resistance is uniformly distributed; while the epoxy resin used in the examples 5 and 7 is linear epoxy resin, which has poor dispersibility and is difficult to be fully and uniformly dispersed and mixed with the boron-rich curing agent, so that the radiation resistance of the prepared glass film is not uniformly dispersed, the 1,3, 5-triaminobenzene is used as the curing agent in the example 6, boric acid is directly added in the curing process, and the boric acid is only distributed in the framework structure but not directly grafted on the framework structure, so that the boron element in the prepared glass film is poorly dispersed, and the radiation resistance of the glass is not uniform;

(2) the thermal conductivity at 3 positions selected in the surface of the double-glazing prepared in measurement examples 4 to 8 was measured at each of the three positions, and the results are shown in table 2:

TABLE 2 measurement results of thermal conductivity of double glass prepared in examples 4 to 8 (W/(m.k))

	Example 4	Example 5	Example 6	Example 7	Example 8
						Position 1	0.38	0.37	0.61	0.41	0.77
Position 2	0.38	0.65	0.39	0.48	0.76
						Position 3	0.37	0.53	0.38	0.65	0.77

As can be seen from table 2, after the glass membrane is compounded between the double-layer glass, because three amino groups in the boron-rich curing agent are uniformly distributed in three directions, when the boron-rich curing agent reacts with the high-strength epoxy resin, the boron-rich curing agent reacts with the high-strength epoxy resin hyperbranched network structure in a cross-linking manner, so that gaps of the network structure are smaller, the perfluoroalkyl ether quaternary ammonium salt, the polyether silicone oil and the silica sol are uniformly coated in a network structure framework, and the addition of the perfluoroalkyl ether quaternary ammonium salt and the polyether silicone oil leads fluorine elements and silicon elements to be introduced into the membrane coating solution, so that the membrane coating solution has certain aging resistance and thermal stability, and meanwhile, the silica sol has a lower thermal conductivity coefficient, and the addition of the silica sol leads the thermal conductivity coefficient; the epoxy resins used in examples 5, 6 and 7 are all linear structures and are not easy to disperse uniformly, so that the perfluoroalkyl ether quaternary ammonium salt, polyether silicone oil and silica sol are not uniformly distributed in the process of preparing the glass film, and the thermal conductivity of the glass film is not uniform.

The preferred embodiments of the invention disclosed above are intended to be illustrative only. The preferred embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A production process of a heat-insulating and anti-radiation laminated glass film comprises the following specific production processes:

step one, adding 7.3kg of high-strength epoxy resin into 21kg of dimethyl sulfoxide, adding 0.6kg of perfluoroalkyl ether quaternary ammonium salt, 0.5kg of polyether silicone oil and 1.6kg of silica sol after uniformly mixing, uniformly stirring and mixing, then adding 2.6kg of boron-rich curing agent, and uniformly stirring and mixing at normal temperature to obtain a viscous film covering agent;

secondly, quickly coating the film laminating machine prepared in the first step on the surface of bottom glass, wherein the spraying thickness is 0.1-0.15mm, placing the film in a drying chamber at 50-60 ℃ after spraying, drying until the film laminating liquid is solidified, forming a layer of semitransparent adhesive glass film on the surface peeled from the bottom layer, then pressing the bottom surface of the top glass on the surface of the adhesive glass film, fixing the glass film through the adhesive effect of the adhesive film, and then peeling the compounded double layers, placing the double layers, and airing at room temperature for 3-4 days to obtain the double-layer adhesive glass;

adding 1.26kg of melamine into 20L of methanol, stirring, mixing and dissolving, heating to 80-90 ℃, then dropwise adding 3.78kg of p-hydroxybenzaldehyde into a reaction container, stirring vigorously while dropwise adding, keeping the temperature unchanged during the dropwise adding process, reacting at constant temperature for 13-15h after completely dropwise adding, then reducing to room temperature, separating out solids, filtering, washing with methanol and acetone in sequence, and drying to obtain a powder product;

adding 1kg of the powder product prepared in the step 1 into 10L of dimethyl sulfoxide, stirring and dissolving, heating to 80-90 ℃, adding 0.29kg of sodium hydroxide into a reaction container, mixing for 3-5min, adding 1.86kg of glycerol triglycidyl ether, reacting at constant temperature for 10-12h, evaporating to remove the solvent, and washing and drying with water and ethanol respectively to obtain high-strength epoxy resin powder;

the preparation process of the boron-rich curing agent comprises the following steps:

adding 1kg of 4-aminophenol and 13L of dimethylformamide into a reaction kettle, adding sodium bicarbonate into the reaction kettle to adjust the pH of the solution to 9-10, and then adding 2.39kg of 9-fluorenylmethyl into the reaction solutionChloroformate, controlling the pH of the reaction solution to be 9-10 in the reaction process, stirring and reacting for 8-10h at normal temperature, then carrying out reduced pressure distillation on the obtained solution, recovering the solvent, and using NaHSO with the pH of 2-3 to obtain a solid product₄Washing and drying the solution to obtain a product A; wherein 13-15mL of dimethylformamide is added into each gram of 4-aminophenol, and 2.39-2.41g of 9-fluorenylmethyl chloroformate is added;