A phosphorus-containing phenolic resin, its preparation method and application

Abstract

The present invention provides a phosphorus-containing phenolic resin, a preparation method and an application thereof, belonging to the technical field of polymer materials. By designing the raw material components of the phenolic resin, using a first boron-containing mixture, cooperating with a second mixture containing silicon, nitrogen and benzene rings, reacting with an aldehyde compound, and introducing a phosphorus element through (methoxymethyl)diphenylphosphine oxide, the prepared phosphorus-containing phenolic resin has a relatively high thermal degradation temperature and heat distortion temperature, and effectively improves the flame retardancy performance.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a phosphorus-containing phenolic resin and a preparation method and application thereof. Background Art

[0002] Phenolic resin (PF) is a type of high molecular polymer formed by the condensation polymerization of phenolic compounds and aldehyde compounds under the catalysis of acidic or alkaline catalysts. Among them, phenolic resin formed by the condensation polymerization of phenol and formaldehyde is the most common and has the longest industrial production time. As one of the earliest artificial synthetic resins, phenolic resin can be used as adhesives, fireproof materials, insulating materials, friction materials and ablation-resistant materials because of its easy availability of raw materials, simple synthesis process, easy control of production conditions, and excellent mechanical properties and electrical insulation after curing. It is widely used in various fields closely related to the national economy, such as construction, electronics, machinery, aerospace and bonding. With the continuous development of industrial technology, people's requirements for material performance are getting higher and higher, so new demands are also put forward for phenolic resin.

[0003] A Chinese patent (publication number CN105754287A) discloses a high-performance phosphorus-containing phenolic resin. By combining two different phosphorus-containing phenolic resins together through the fusion of modified components, a high-performance phenolic resin is formed. The phosphorus content is increased, and the phosphorus element is introduced into the phenolic resin without affecting the mechanical properties of the resin itself. The introduction of the phosphorus element also avoids the high softening point of the product affecting the mechanical properties of the resin. However, the existing phenolic resin still has problems such as poor high temperature resistance, low thermal degradation temperature and heat deformation temperature, and the flame retardant performance needs to be improved.

[0004] Therefore, how to design the components, introduce groups that can withstand high temperatures, and use multiple elements to synergize flame retardancy so that the prepared phenolic resin has a higher thermal degradation temperature and heat deformation temperature and improves flame retardancy has become a direction that needs to be focused on. Summary of the invention

[0005] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a phosphorus-containing phenolic resin and a preparation method and application thereof, aiming to solve the problems that the existing phenolic resin has poor high temperature resistance, low thermal degradation temperature and thermal deformation temperature, and the flame retardant performance needs to be improved.

[0006] The present invention designs the raw material components of the phenolic resin, uses a first mixture containing boron, and cooperates with a second mixture containing silicon, nitrogen and benzene rings to react with aldehyde compounds, and introduces the phosphorus element through (methoxymethyl) diphenylphosphine, so that the prepared phosphorus-containing phenolic resin has a higher thermal degradation temperature and heat deformation temperature, and effectively improves the flame retardant performance.

[0007] The technical solution adopted by the present invention to solve the above technical problems is as follows:

[0008] In the first aspect of the present invention, a preparation method of a phosphorus-containing phenolic resin is provided, comprising the following steps:

[0009] Step S1: By weight, mix 20 - 30 parts of phenol, 3 - 5 parts of toluene and 5 - 8 parts of boric acid evenly for a first pre-reaction. After the first pre-reaction is completed, cool down to 90 °C to obtain a first mixture;

[0010] Step S2: By weight, mix 20 - 30 parts of phenol and 5 - 10 parts of anilinomethyltrimethoxysilane evenly, then add 0.3 - 0.5 parts of a catalyst, and carry out a second pre-reaction under the protection of a nitrogen atmosphere. After the second pre-reaction is completed, cool down to 90 °C to obtain a second mixture;

[0011] Step S3: By weight, mix 20 - 30 parts of the first mixture, 20 - 30 parts of the second mixture and 15 - 20 parts of an aldehyde compound for a polymerization reaction. After the polymerization reaction is completed, a prepolymer system is obtained;

[0012] Step S4: By weight, add 30 - 40 parts of a phosphorus-containing compound to the prepolymer system for an addition reaction. After the addition reaction is completed, add 3 - 5 parts of carbon quantum dot-modified antimony trioxide and 3 - 5 parts of an aluminum chloride complex, and mix evenly to obtain a phosphorus-containing phenolic resin.

[0013] The following are the preferred technical solutions of the present invention, but do not limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the purpose and beneficial effects of the present invention can be better achieved.

[0014] As a preferred technical solution of the present invention, the reaction temperature of the first pre-reaction is 160 - 165 °C, and the reaction time is 2 - 3 h.

[0015] The first mixture contains boron element, and boron can be introduced into the phenolic resin in subsequent reactions. Boron oxide is generated during the high-temperature combustion process, which can adhere to the surface of the combustible material to form a dense barrier layer, which can isolate the heat and the propagation of combustible gases during the combustion process, cause the material to self-extinguish, and at the same time reduce its smoke production, thereby improving the flame retardant effect.

[0016] As a preferred technical solution of the present invention, the catalyst in step S2 is a Bronsted acid catalyst.

[0017] As a preferred technical solution of the present invention, the reaction temperature of the second pre-reaction in step S2 is 155 - 160 °C, and the reaction time is 5 - 6 h.

[0018] The second mixture contains silicon, nitrogen and benzene rings. The surface energy of silicon element is relatively low, and it is easy to migrate to the material surface to form a silicon-containing protective layer, improving the high-temperature stability of the material; nitrogen element can generate flame-retardant nitrogen-containing compounds at high temperature to dilute the concentration of combustion gases near the flame, playing a flame-retardant effect; benzene rings can hinder the movement of molecular chains, reduce the thermal expansion phenomenon, and improve the heat distortion temperature of the material.

[0019] Preferably, the aldehyde compound in step S3 is paraformaldehyde.

[0020] Preferably, the reaction temperature of the polymerization reaction in step S3 is 90 - 110 °C, and the reaction time is 1 - 3 h.

[0021] As a preferred technical solution of the present invention, the phosphorus-containing compound in step S4 is (methoxymethyl)diphenylphosphine oxide.

[0022] As a preferred technical solution of the present invention, the reaction temperature of the addition reaction in step S4 is 119 - 121 °C, and the reaction time is 2 - 3 h.

[0023] The phosphorus element and benzene rings are introduced into the phenolic resin through the phosphorus-containing compound. The phosphorus element releases phosphorus oxide free radicals under high-temperature conditions, combines with the free radicals promoting combustion, thereby terminating the chain reaction of combustion, and thus improving the limiting oxygen index; benzene rings belong to rigid structures, which can increase the packing density of molecular chains, thereby reducing the free volume and effectively reducing the degree of thermal deformation.

[0024] As a preferred technical solution of the present invention, the preparation method of the carbon quantum dot-modified antimony trioxide in step S4 includes: by weight, evenly spreading 2 - 4 parts of itaconic acid on the bottom of a 50 ml beaker, reacting in a vacuum drying oven, the reaction temperature is 200 - 220 °C, and the reaction time is 1 - 2 h; after the reaction is completed, it is naturally cooled to room temperature to obtain a solid, then the solid is added to 10 - 20 parts of 1 mol / L sodium hydroxide solution, and then 5 - 10 parts of antimony trioxide are added, stirred evenly, freeze-dried and ground to obtain the carbon quantum dot-modified antimony trioxide.

[0025] As a preferred technical solution of the present invention, the preparation method of the aluminum chloride complex in step S4 includes: by weight, adding 4 - 6 parts of aluminum chloride to 100 - 120 parts of deionized water, then adding 0.5 - 0.8 parts of sodium carbonate and stirring for 20 - 30 min, then under a nitrogen atmosphere, adding 1 - 3 parts of acrylamide and 0.1 - 0.2 parts of ammonium cerium nitrate and reacting for 2 - 4 h, and after the reaction is completed, vacuum drying to obtain the aluminum chloride complex.

[0026] In the second aspect of the present invention, there is provided a phosphorus-containing phenolic resin prepared by the method as described in the first aspect.

[0027] The third aspect of the present invention provides an application of a phosphorus-containing phenolic resin prepared by the method described in the first aspect in the printed circuit board industry.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) Under the action of a Bronsted acid catalyst, phenol and anilinomethyltrimethoxysilane in the present invention react to form a second mixture, and the silicon element in the second mixture is introduced into the phenolic resin through subsequent reactions. The surface energy of the silicon element is relatively low, and it is easy to migrate to the material surface to form a silicon-containing protective layer, thereby increasing the thermal degradation temperature of the material.

[0030] (2) Both the second mixture and the phosphorus-containing compound in the present invention contain benzene rings. The benzene ring belongs to a rigid structure, which can increase the molecular chain packing density, thereby reducing the free volume and at the same time hindering the movement of the molecular chain and reducing the thermal expansion phenomenon. The combined effect improves the heat distortion temperature of the material.

[0031] (3) The phenolic resin of the present invention introduces elements such as boron, silicon, nitrogen, and phosphorus. Among them, boron element generates boron oxide during the high-temperature combustion process, which can isolate the transmission of heat and combustible gases during the combustion process; the synergistic effect of silicon and nitrogen elements is to generate flame-retardant nitrogen-containing gases to play a flame-retardant effect in the condensed phase and gas phase; the synergistic effect of phosphorus and silicon elements is to form a phosphorus-containing carbon layer and a silicon-containing protective layer to avoid the oxidation of the carbon layer on the material surface. Through the combined action of boron-silicon-nitrogen-phosphorus four elements, the limiting oxygen index of the phenolic resin is increased.

[0032] (4) During the preparation of carbon quantum dot-modified antimony trioxide in the present invention, the C-H bonds in itaconic acid are gradually oxidized into carboxyl groups, and some C-C bonds are broken or recombined. As the itaconic acid molecules are continuously carbonized, the surface carboxyl groups are continuously enriched to form itaconic acid carbon quantum dots and use them to modify antimony trioxide, making its surface rich in groups such as hydroxyl and carboxyl; the aluminum chloride complex is modified through acrylamide to introduce amino groups. When used in combination with carbon quantum dot-modified antimony trioxide, the amino group can combine with the hydroxyl and carboxyl groups rich in carbon quantum dots, effectively increasing the thermal degradation temperature and heat distortion temperature of the resin composition. At the same time, when the temperature rises, antimony trioxide and the aluminum chloride complex can react to generate antimony halide vapor, and these vapors can dilute the combustible gas and cool the flame, thereby preventing combustion. Specific Embodiments

[0033] To facilitate the understanding of the present invention, the following examples are listed. Those skilled in the art should understand that the examples are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0034] The sources of some components in the examples and comparative examples are as follows:

[0035] Phenol, CAS No. 108-95-2, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0036] Toluene, CAS No. 108-88-3, was purchased from Shanghai Lingfeng Chemical Reagent Co., Ltd.;

[0037] Boric acid, CAS No. 11113-50-1, was purchased from Tianjin Damao Chemical Reagent Factory;

[0038] Acetic acid, CAS No. 64-19-7, was purchased from Shanghai Macklin Biochemical Co., Ltd.;

[0039] Bronsted acid catalyst, product number S816962, was purchased from Shanghai Macklin Biochemical Co., Ltd.;

[0040] Anilinomethyltrimethoxysilane, CAS No. 77855-73-3, was purchased from Shandong Baiqian Chemical Co., Ltd.;

[0041] Paraformaldehyde, CAS No. 30525-89-4, was purchased from Shanghai Macklin Biochemical Co., Ltd.;

[0042] (Methoxymethyl)diphenylphosphine oxide, CAS No. 4455-77-0, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0043] Itaconic acid, product number PA54343, was purchased from Shanghai Chuangsai Technology Co., Ltd.;

[0044] Sodium hydroxide, CAS No. 1310-73-2, was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0045] Antimony trioxide, product number FR-180, was purchased from Hunan Flash Star Antimony Industry Co., Ltd.;

[0046] Aluminum chloride, CAS No. 7446-70-0, was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0047] Sodium carbonate, CAS No. 497-19-8, was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0048] Acrylamide, product number A8887, was purchased from Sigma-Aldrich (Shanghai) Trading Co., Ltd.;

[0049] Ammonium cerium(IV) nitrate, CAS No. 16774-21-3, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0050] Preparation of carbon quantum dot-modified antimony trioxide: By weight, 4 parts of itaconic acid are evenly spread on the bottom of a 50 ml beaker and reacted in a vacuum drying oven at a reaction temperature of 220 °C for 2 h; after the reaction is completed, it is naturally cooled to room temperature to obtain a solid, and then the solid is added to 20 parts of 1 mol / L sodium hydroxide solution, and then 10 parts of antimony trioxide are added, stirred evenly, freeze-dried and ground to obtain carbon quantum dot-modified antimony trioxide.

[0051] Preparation of aluminum chloride complex: By weight, 6 parts of aluminum chloride are added to 120 parts of deionized water, and then 0.8 part of sodium carbonate is added and stirred for 30 min. Then, in a nitrogen atmosphere, 3 parts of acrylamide and 0.2 part of ammonium cerium nitrate are added and reacted for 4 h. After the reaction is completed, it is vacuum dried to obtain the aluminum chloride complex.

[0052] Example 1

[0053] This example provides a preparation method of a phosphorus-containing phenolic resin, including the following steps:

[0054] Step S1: By weight, 30 parts of phenol, 5 parts of toluene and 8 parts of boric acid are mixed evenly for the first pre-reaction (reaction temperature is 165 °C, reaction time is 2 h). After the first pre-reaction is completed, the temperature is lowered to 90 °C to obtain the first mixture;

[0055] Step S2: By weight, 30 parts of phenol and 10 parts of anilinomethyltrimethoxysilane are mixed and stirred evenly, and then 0.5 part of Bronsted acid catalyst is added, and the second pre-reaction is carried out under the protection of a nitrogen atmosphere (reaction temperature is 160 °C, reaction time is 5 h). After the second pre-reaction is completed, the temperature is lowered to 90 °C to obtain the second mixture;

[0056] Step S3: By weight, 30 parts of the first mixture, 30 parts of the second mixture and 20 parts of paraformaldehyde are mixed for a polymerization reaction (the reaction temperature of the polymerization reaction is 110 °C, reaction time is 1 h). After the polymerization reaction is completed, a prepolymerization system is obtained;

[0057] Step S4: By weight, 40 parts of (methoxymethyl)diphenylphosphine oxide are added to the prepolymerization system for an addition reaction (the reaction temperature of the addition reaction is 121 °C, reaction time is 2 h). After the addition reaction is completed, 5 parts of carbon quantum dot-modified antimony trioxide and 5 parts of aluminum chloride complex are added, and mixed evenly to obtain the phosphorus-containing phenolic resin.

[0058] Example 2

[0059] This example provides a preparation method of a phosphorus-containing phenolic resin, including the following steps:

[0060] Step S1: Mix 20 parts of phenol, 3 parts of toluene and 5 parts of boric acid evenly by weight and carry out a first pre-reaction (reaction temperature: 160 °C, reaction time: 3 h). After the first pre-reaction is completed, cool down to 90 °C to obtain a first mixture;

[0061] Step S2: Mix 20 parts of phenol and 5 parts of anilinomethyltrimethoxysilane evenly by weight and stir well. Then add 0.3 parts of Bronsted acid catalyst and carry out a second pre-reaction under the protection of a nitrogen atmosphere (reaction temperature: 155 °C, reaction time: 6 h). After the second pre-reaction is completed, cool down to 90 °C to obtain a second mixture;

[0062] Step S3: Mix 20 parts of the first mixture, 20 parts of the second mixture and 15 parts of paraformaldehyde evenly by weight and carry out a polymerization reaction (reaction temperature of the polymerization reaction: 90 °C, reaction time: 3 h). After the polymerization reaction is completed, a prepolymer system is obtained;

[0063] Step S4: Add 30 parts of (methoxymethyl)diphenylphosphine oxide to the prepolymer system by weight and carry out an addition reaction (reaction temperature of the addition reaction: 119 °C, reaction time: 3 h). After the addition reaction is completed, add 3 parts of carbon quantum dot modified antimony trioxide and 3 parts of aluminum chloride complex and mix evenly to obtain a phosphorus-containing phenolic resin.

[0064] Example 3

[0065] This example provides a preparation method of a phosphorus-containing phenolic resin, including the following steps:

[0066] Step S1: Mix 25 parts of phenol, 4 parts of toluene and 6 parts of boric acid evenly by weight and carry out a first pre-reaction (reaction temperature: 162 °C, reaction time: 3 h). After the first pre-reaction is completed, cool down to 90 °C to obtain a first mixture;

[0067] Step S2: Mix 25 parts of phenol and 8 parts of anilinomethyltrimethoxysilane evenly by weight and stir well. Then add 0.4 parts of Bronsted acid catalyst and carry out a second pre-reaction under the protection of a nitrogen atmosphere (reaction temperature: 158 °C, reaction time: 5 h). After the second pre-reaction is completed, cool down to 90 °C to obtain a second mixture;

[0068] Step S3: Mix 25 parts of the first mixture, 25 parts of the second mixture and 18 parts of paraformaldehyde evenly by weight and carry out a polymerization reaction (reaction temperature of the polymerization reaction: 100 °C, reaction time: 2 h). After the polymerization reaction is completed, a prepolymer system is obtained;

[0069] Step S4: Add 35 parts of (methoxymethyl)diphenylphosphine oxide by weight to the prepolymerization system for an addition reaction (the reaction temperature of the addition reaction is 120 °C and the reaction time is 3 h). After the addition reaction is completed, add 4 parts of carbon quantum dot-modified antimony trioxide and 4 parts of aluminum chloride complex, and mix evenly to obtain a phosphorus-containing phenolic resin.

[0070] Comparative Example 1

[0071] This comparative example provides a method for preparing a phenolic resin, which includes the following steps:

[0072] Step S1: Mix 30 parts of phenol, 5 parts of toluene and 8 parts of acetic acid evenly by weight for a first pre-reaction (the reaction temperature is 165 °C and the reaction time is 2 h). After the first pre-reaction is completed, cool down to 90 °C to obtain a first mixture;

[0073] Step S2: Mix 30 parts of phenol and 10 parts of anilinomethyltrimethoxysilane evenly by weight, then add 0.5 part of Bronsted acid catalyst, and carry out a second pre-reaction under the protection of a nitrogen atmosphere (the reaction temperature is 160 °C and the reaction time is 5 h). After the second pre-reaction is completed, cool down to 90 °C to obtain a second mixture;

[0074] Step S3: Mix 30 parts of the first mixture, 30 parts of the second mixture and 20 parts of paraformaldehyde by weight for a polymerization reaction (the reaction temperature of the polymerization reaction is 110 °C and the reaction time is 1 h). After the polymerization reaction is completed, a prepolymerization system is obtained;

[0075] Step S4: Add 40 parts of (methoxymethyl)diphenylphosphine oxide by weight to the prepolymerization system for an addition reaction (the reaction temperature of the addition reaction is 121 °C and the reaction time is 2 h). After the reaction is completed, add 5 parts of carbon quantum dot-modified antimony trioxide and 5 parts of aluminum chloride complex, and mix evenly to obtain a phosphorus-containing phenolic resin.

[0076] Comparative Example 2

[0077] This comparative example provides a method for preparing a phenolic resin, which includes the following steps:

[0078] Step S1: Mix 30 parts of phenol, 5 parts of toluene and 8 parts of boric acid evenly by weight for a first pre-reaction (the reaction temperature is 165 °C and the reaction time is 2 h). After the first pre-reaction is completed, cool down to 90 °C to obtain a first mixture;

[0079] Step S2: Mix 30 parts of the first mixture, 30 parts of phenol and 20 parts of paraformaldehyde by weight for a polymerization reaction (the reaction temperature of the polymerization reaction is 110 °C and the reaction time is 1 h). After the polymerization reaction is completed, a prepolymerization system is obtained;

[0080] Step S3: Add 40 parts of (methoxymethyl)diphenylphosphine oxide to the prepolymerization system by weight for an addition reaction (the reaction temperature of the addition reaction is 121 °C and the reaction time is 2 h). After the reaction is completed, add 5 parts of carbon quantum dot-modified antimony trioxide and 5 parts of aluminum chloride complex, and mix evenly to obtain a phosphorus-containing phenolic resin.

[0081] Comparative Example 3

[0082] This comparative example provides a method for preparing a phenolic resin, which includes the following steps:

[0083] Step S1: Mix 30 parts of phenol, 5 parts of toluene and 8 parts of boric acid evenly by weight for a first pre-reaction (the reaction temperature is 165 °C and the reaction time is 2 h). After the first pre-reaction is completed, cool down to 90 °C to obtain a first mixture;

[0084] Step S2: Mix 30 parts of phenol and 10 parts of anilinomethyltrimethoxysilane evenly by weight, then add 0.5 part of Bronsted acid catalyst, and carry out a second pre-reaction under the protection of a nitrogen atmosphere (the reaction temperature is 160 °C and the reaction time is 5 h). After the second pre-reaction is completed, cool down to 90 °C to obtain a second mixture;

[0085] Step S3: Mix 30 parts of the first mixture, 30 parts of the second mixture and 20 parts of paraformaldehyde by weight for a polymerization reaction (the reaction temperature of the polymerization reaction is 110 °C and the reaction time is 1 h). After the polymerization reaction is completed, a prepolymerization system is obtained; raise the temperature of the prepolymerization system to 120 °C and continue the reaction for 4 h. After the reaction is completed, add 5 parts of carbon quantum dot-modified antimony trioxide and 5 parts of aluminum chloride complex, and mix evenly to obtain a phosphorus-containing phenolic resin.

[0086] Comparative Example 4

[0087] This comparative example provides a method for preparing a phenolic resin, which includes the following steps:

[0088] Step S1: Mix 30 parts of phenol, 5 parts of toluene and 8 parts of boric acid evenly by weight for a first pre-reaction (the reaction temperature is 165 °C and the reaction time is 2 h). After the first pre-reaction is completed, cool down to 90 °C to obtain a first mixture;

[0089] Step S2: Mix 30 parts of the first mixture, 30 parts of phenol and 20 parts of paraformaldehyde by weight for a polymerization reaction (the reaction temperature of the polymerization reaction is 110 °C and the reaction time is 1 h). After the polymerization reaction is completed, a prepolymerization system is obtained; raise the temperature of the prepolymerization system to 120 °C and continue the reaction for 4 h. After the reaction is completed, add 5 parts of carbon quantum dot-modified antimony trioxide and 5 parts of aluminum chloride complex, and mix evenly to obtain a phosphorus-containing phenolic resin.

[0090] Comparative Example 5

[0091] This comparative example provides a method for preparing phenolic resin, including the following steps:

[0092] Step S1: By weight, mix 30 parts of phenol, 5 parts of toluene and 8 parts of acetic acid evenly for the first pre-reaction (reaction temperature is 165 °C, reaction time is 2 h). After the first pre-reaction is completed, cool down to 90 °C to obtain the first mixture;

[0093] Step S2: By weight, mix 30 parts of phenol and 10 parts of anilinomethyltrimethoxysilane evenly, then add 0.5 part of Bronsted acid catalyst, and carry out the second pre-reaction under the protection of nitrogen atmosphere (reaction temperature is 160 °C, reaction time is 5 h). After the second pre-reaction is completed, cool down to 90 °C to obtain the second mixture;

[0094] Step S3: By weight, mix 30 parts of the first mixture, 30 parts of the second mixture and 20 parts of paraformaldehyde for polymerization reaction (reaction temperature of the polymerization reaction is 110 °C, reaction time is 1 h). After the polymerization reaction is completed, a prepolymerization system is obtained; raise the temperature of the prepolymerization system to 120 °C and continue the reaction for 4 h. After the reaction is completed, add 5 parts of carbon quantum dot modified antimony trioxide and 5 parts of aluminum chloride complex, and mix evenly to obtain a phosphorus-containing phenolic resin.

[0095] Comparative Example 6

[0096] This comparative example provides a method for preparing phenolic resin, including the following steps:

[0097] Step S1: By weight, mix 30 parts of phenol, 5 parts of toluene and 8 parts of acetic acid evenly for the first pre-reaction (reaction temperature is 165 °C, reaction time is 2 h). After the first pre-reaction is completed, cool down to 90 °C to obtain the first mixture;

[0098] Step S2: By weight, mix 30 parts of the first mixture, 30 parts of phenol and 20 parts of paraformaldehyde for polymerization reaction (reaction temperature of the polymerization reaction is 110 °C, reaction time is 1 h). After the polymerization reaction is completed, a prepolymerization system is obtained;

[0099] Step S3: By weight, add 40 parts of (methoxymethyl)diphenylphosphine oxide to the prepolymerization system for addition reaction (reaction temperature of the addition reaction is 121 °C, reaction time is 2 h). After the addition reaction is completed, add 5 parts of carbon quantum dot modified antimony trioxide and 5 parts of aluminum chloride complex, and mix evenly to obtain a phosphorus-containing phenolic resin.

[0100] Comparative Example 7

[0101] This comparative example provides a method for preparing phenolic resin. The difference from Example 1 is that carbon quantum dot-modified antimony trioxide is not added in step S4, and other conditions are the same as those in Example 1.

[0102] Comparative Example 8

[0103] This comparative example provides a method for preparing phenolic resin. The difference from Example 1 is that aluminum chloride complex is not added in step S4, and other conditions are the same as those in Example 1.

[0104] Comparative Example 9

[0105] This comparative example provides a method for preparing phenolic resin. The difference from Example 1 is that carbon quantum dot-modified antimony trioxide and aluminum chloride complex are not added in step S4, and other conditions are the same as those in Example 1. The properties of the phenolic resins provided in the above examples and comparative examples were tested, and the test methods are as follows:

[0106] (1) Thermal degradation temperature test: Using a thermogravimetric analyzer (TA Instruments, TAInstruments Q500TGA, USA), the stability of the resin at high temperatures was studied in a nitrogen environment. The test temperature was from room temperature to 800 °C, and the heating rate was 20 °C / min.

[0107] (2) Heat distortion temperature test: The test was carried out according to the requirements of "GB / T 1634.2-2019 Plastics - Determination of heat distortion temperature - Part 2: Plastics and hard rubbers".

[0108] (3) Flame retardancy test: The limiting oxygen index method was used, and the test was carried out according to the requirements of "GB / T 2406.3-2022 Plastics - Determination of flammability by the oxygen index - Part 3: High-temperature test".

[0109] The above performance test data are shown in Table 1.

[0110] Table 1 Performance test results

[0111]

[0112] As can be seen from the above content, in the present invention, by designing the components, groups capable of withstanding high temperatures are introduced, and through the synergistic flame retardancy of multiple elements, the prepared phosphorus-containing phenolic resins (Examples 1 to 3) have a thermal degradation temperature of 478.1 - 478.2 °C, a heat distortion temperature of 208.1 - 208.5 °C, and a limiting oxygen index of 35.2 - 35.4%.

[0113] Compared with Example 1, when acetic acid is used to replace boric acid, the limiting oxygen index decreases (Comparative Example 1); compared with Example 1, when phenol is used to replace the second mixture, the thermal degradation temperature, heat distortion temperature and limiting oxygen index decrease (Comparative Example 2); compared with Example 1, when (methoxymethyl)diphenylphosphine oxide is not used, the heat distortion temperature and limiting oxygen index decrease (Comparative Example 3); compared with Example 1, when phenol is used to replace the second mixture and (methoxymethyl)diphenylphosphine oxide is not used, the thermal degradation temperature, heat distortion temperature and limiting oxygen index decrease (Comparative Example 4); compared with Example 1, when acetic acid is used to replace boric acid and (methoxymethyl)diphenylphosphine oxide is not used, the heat distortion temperature and limiting oxygen index decrease (Comparative Example 5); compared with Example 1, when acetic acid is used to replace boric acid and phenol is used to replace the second mixture, the thermal degradation temperature, heat distortion temperature and limiting oxygen index decrease (Comparative Example 6); compared with Example 1, when carbon quantum dot-modified antimony trioxide is not added in step S4, the thermal degradation temperature, heat distortion temperature and limiting oxygen index decrease (Comparative Example 7); compared with Example 1, when aluminum chloride complex is not added in step S4, the thermal degradation temperature, heat distortion temperature and limiting oxygen index decrease (Comparative Example 8); compared with Example 1, when carbon quantum dot-modified antimony trioxide and aluminum chloride complex are not added in step S4, the thermal degradation temperature, heat distortion temperature and limiting oxygen index decrease (Comparative Example 9).

[0114] In summary, by designing the raw material components of the phenolic resin, the present invention uses a boron-containing first mixture, cooperates with a second mixture containing silicon, nitrogen and benzene rings, reacts with an aldehyde compound, and introduces a phosphorus element through (methoxymethyl)diphenylphosphine oxide, so that the prepared phosphorus-containing phenolic resin has a high thermal degradation temperature and heat distortion temperature, and effectively improves the flame retardancy performance.

[0115] The applicant declares that the present invention uses the above-mentioned examples to illustrate the detailed process flow of the present invention, but the present invention is not limited to the above-mentioned detailed process flow, that is, it does not mean that the present invention must rely on the above-mentioned detailed process flow to be implemented. Those skilled in the art should understand that any improvement of the present invention, the equivalent replacement of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc. all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a phosphorus-containing phenolic resin, characterized in that: The following steps are involved: Step S1: by weight, 20 to 30 parts of phenol, 3 to 5 parts of toluene and 5 to 8 parts of boric acid are uniformly mixed to perform a first pre-reaction, and after the first pre-reaction is completed, the temperature is lowered to 90° C. to obtain a first mixture; Step S2: Mix 20-30 parts of phenol and 5-10 parts of aniline methyl trimethoxy silane by weight, stir them evenly, then add 0.3-0.5 parts of catalyst, carry out a second pre-reaction under the protection of nitrogen atmosphere, and cool the temperature to 90° C. after the second pre-reaction is completed to obtain a second mixture; Step S3: by weight, 20 to 30 parts of the first mixture, 20 to 30 parts of the second mixture and 15 to 20 parts of the aldehyde compound are mixed to carry out a polymerization reaction, and after the polymerization reaction is completed, a prepolymer system is obtained; Step S4: adding 30 to 40 parts by weight of a phosphorus-containing compound to the prepolymerization system for an addition reaction, and after the addition reaction is completed, adding 3 to 5 parts of carbon quantum dot-modified antimony trioxide and 3 to 5 parts of an aluminum chloride complex, mixing them evenly, to obtain a phosphorus-containing phenolic resin; The phosphorus-containing compound in step S4 is (methoxymethyl)diphenylphosphine; The reaction temperature of the addition reaction in step S4 is 119-121° C., and the reaction time is 2-3 h; The preparation method of the carbon quantum dot modified antimony trioxide in step S4 comprises: in parts by weight, 2 to 4 parts of itaconic acid are evenly spread on the bottom of a 50 ml beaker, and reacted in a vacuum drying oven at a reaction temperature of 200 to 220 ° C. for a reaction time of 1 to 2 hours; after the reaction is completed, the solid is naturally cooled to room temperature to obtain a solid, and then 10 to 20 parts of a 1 mol / L sodium hydroxide solution are added to the solid, and then 5 to 10 parts of antimony trioxide are added, stirred evenly, freeze-dried, and ground to obtain carbon quantum dot modified antimony trioxide; The preparation method of the aluminum chloride complex in step S4 includes: adding 4 to 6 parts of aluminum chloride to 100 to 120 parts of deionized water, adding 0.5 to 0.8 parts of sodium carbonate and stirring for 20 to 30 minutes, and then adding 1 to 3 parts of acrylamide and 0.1 to 0.2 parts of ammonium cerium nitrate under a nitrogen atmosphere for reaction for 2 to 4 hours. After the reaction is completed, vacuum drying is performed to obtain an aluminum chloride complex.

2. The method for preparing a phosphorus-containing phenolic resin according to claim 1, characterized in that: The reaction temperature of the first pre-reaction in step S1 is 160-165° C., and the reaction time is 2-3 h.

3. The method for preparing a phosphorus-containing phenolic resin according to claim 1, characterized in that: The catalyst in step S2 is a Bronsted acid catalyst; the reaction temperature of the second pre-reaction is 155-160° C., and the reaction time is 5-6 hours.

4. The method for preparing a phosphorus-containing phenolic resin according to claim 1, characterized in that: In step S3, the aldehyde compound is paraformaldehyde; the reaction temperature of the polymerization reaction is 90-110° C., and the reaction time is 1-3 hours.

5. A phosphorus-containing phenolic resin, characterized in that: The method is obtained by the preparation method according to any one of claims 1 to 4.

6. Application of the phosphorus-containing phenolic resin obtained according to the preparation method according to any one of claims 1 to 4 in the printed circuit board industry.

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