A phenolic resin-based copper clad laminate filled with boron nitride micropowder and its preparation method

Abstract

The present invention relates to the field of copper clad laminates, and specifically discloses a phenolic resin-based copper clad laminate filled with boron nitride micropowder and a preparation method thereof; the method comprises the following steps: S1: taking 15-20 parts of linear phenolic resin, 6-8 parts of modified boron nitride micropowder, 0.5-1 part of phenolic epoxy resin, 1-2 parts of epoxy resin, 0.1-0.2 part of diluent dodecyl glycidyl ether, 2-4 parts of flame retardant toughening agent, and 0.01-0.03 part of imidazole, mixing uniformly, and performing high-speed shear emulsification for 1-2 h to obtain a resin adhesive; S2: impregnating a glass fiber cloth in the resin adhesive, pulling it out, drying at 190-200 °C for 2-3 min to obtain a prepreg; stacking 6 prepregs to obtain a substrate, pasting copper foils on both sides of the substrate, and performing hot pressing at a hot pressing temperature of 200-210 °C, a hot pressing pressure of 3-4 Mpa, and a pressing time of 100-150 min to obtain a phenolic resin-based copper clad laminate.

Description

Technical Field

[0001] The present invention relates to the field of copper clad laminates, and specifically discloses a phenolic resin-based copper clad laminate filled with boron nitride micropowder and a preparation method thereof. Background Art

[0002] Phenolic resin is inexpensive and has good performance, and is widely used in the fields of automobiles, electronics, transportation, aerospace, etc. The commonly used phenolic resin for preparing copper clad laminates is linear phenolic resin, which has better heat resistance, water resistance, corrosion resistance, mechanical properties and electrical insulation. When linear phenolic resin is used in combination with epoxy resin, materials with good thermal conductivity, electrical insulation, dielectric and other properties can be obtained.

[0003] However, copper clad laminates have high requirements for flame retardancy. Unmodified phenolic resin cannot meet the flame retardancy requirements of copper clad laminates, and phenolic resin is brittle and has low mechanical strength, which limits its application. Therefore, it is of great significance to study a phenolic resin-based copper clad laminate with both flame retardant properties and mechanical strength. Summary of the Invention

[0004] The purpose of the present invention is to provide a phenolic resin-based copper clad laminate filled with boron nitride micropowder and a preparation method thereof to solve the problems raised in the above background art.

[0005] To solve the above technical problems, the present invention provides the following technical solutions:

[0006] A preparation method of a phenolic resin-based copper clad laminate filled with boron nitride micropowder: includes the following steps: S1: Take phenolic resin, modified boron nitride micropowder, phenolic epoxy resin, epoxy resin, diluent, flame retardant toughening agent, imidazole, mix evenly, and perform high-speed shear emulsification to obtain a resin glue solution;

[0007] S2: Immerse a glass fiber cloth in the resin glue solution, pull it out, and dry to obtain a semi-cured sheet; Stack 5 to 10 semi-cured sheets to obtain a substrate, and attach copper foils to both sides of the substrate, and perform hot pressing and compounding to obtain a phenolic resin-based copper clad laminate.

[0008] Preferably, the resin glue solution includes the following raw materials, by mass: 15 to 20 parts of phenolic resin, 6 to 8 parts of modified boron nitride micropowder, 0.5 to 1 part of phenolic epoxy resin, 1 to 2 parts of epoxy resin, 0.1 to 0.2 part of diluent, 2 to 4 parts of flame retardant toughening agent, 0.01 to 0.03 part of imidazole.

[0009] Preferably, the epoxy resin is bisphenol A epoxy resin, the phenolic resin is linear phenolic resin, and the diluent is dodecyl to tetradecyl glycidyl ether.

[0010] Preferably, the preparation of the flame retardant and toughening agent comprises the following steps: taking a hyperbranched modifier, DOPO, ethanol, water, N,N-dimethylformamide, heating and stirring at 60-70 °C for 4-6 h, cooling, filtering, washing, and drying in vacuum to obtain the flame retardant and toughening agent.

[0011] Preferably, the flame retardant and toughening agent comprises the following raw materials in parts by mass: 20-30 parts of hyperbranched modifier, 5-10 parts of DOPO, 100-200 parts of ethanol, 50-100 parts of water, and 50-100 parts of N,N-dimethylformamide.

[0012] Preferably, the preparation of the hyperbranched modifier comprises the following steps: S1: taking 2,4-diaminophenol, p-hydroxybenzaldehyde, and ethanol, stirring evenly, stirring at 60-70 °C for 3-4 h, cooling to room temperature, filtering, washing, and drying in vacuum to obtain the modifier;

[0013] S2: mixing 3-(tert-butyldimethylsilyloxy) glutaric anhydride, the modifier, p-toluenesulfonic acid, water, and N,N-dimethylformamide, heating at 95-100 °C for 6-8 h, and drying by vacuum distillation to obtain the hyperbranched modifier.

[0014] Preferably, the modifier comprises the following raw materials in parts by mass: 20-30 parts of 2,4-diaminophenol, 15-25 parts of p-hydroxybenzaldehyde, and 300-400 parts of ethanol; the hyperbranched modifier comprises the following raw materials in parts by mass: 20-30 parts of 3-(tert-butyldimethylsilyloxy) glutaric anhydride, 10-15 parts of the modifier, 0.3-0.8 parts of p-toluenesulfonic acid, 40-60 parts of water, and 40-60 parts of N,N-dimethylformamide.

[0015] Preferably, the preparation of the modified boron nitride micropowder comprises the following steps: taking hexagonal boron nitride nanosheet powder, urea, and water, ball milling at room temperature, washing, and drying to obtain the modified boron nitride micropowder.

[0016] Preferably, the modified boron nitride micropowder comprises the following raw materials in parts by mass: 0.5-1 part of hexagonal boron nitride nanosheet powder, 30-40 parts of urea, and 10-15 parts of water.

[0017] Preferably, the addition amount of the phenolic epoxy resin is 50-60% of the mass of the epoxy resin, and the addition amount of the diluent is 8-15% of the mass of the epoxy resin.

[0018] Preferably, the preparation of the prepreg comprises the following steps: impregnating a glass fiber cloth in a resin sizing solution, pulling it out, and drying to obtain the prepreg, with a sizing amount of 150-200 g / m 2 .

[0019] Preferably, the preparation of the prepreg comprises the following steps: impregnating a glass fiber cloth in a resin sizing solution, pulling it out, and drying to obtain the prepreg, with the sizing amount being 160 g / m 2 .

[0020] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: (1) Preparation of a flame retardant toughening agent: using 2,4-diaminophenol and p-hydroxybenzaldehyde to prepare a modifier, and then using the reaction of 3-(tert-butyldimethylsilyloxy)glutaric anhydride with the modifier to prepare a modifier containing a hyperbranched structure, while introducing silicon with good flame retardant and heat resistance properties; the hyperbranched structure can introduce a large amount of free volume, enabling the chain segments to respond rapidly under load, thereby consuming energy and improving toughness. This structure is also beneficial for uniform dispersion in the resin matrix, achieving better flame retardant effects while enhancing the toughness of the resin matrix and improving the brittle problem of phenolic resin; at the same time, the hyperbranched structure improves the fluidity of the resin matrix, reduces viscosity, and makes it easier to process; then, using the carbon-nitrogen double bond structure in the hyperbranched modifier to react with DOPO to introduce phosphorus element, obtaining a hyperbranched structure flame retardant toughening agent containing silicon, nitrogen, and phosphorus, further enhancing the flame retardant effect;

[0021] (2) Preparation of modified boron nitride micropowder containing hydroxyl groups, which can improve the dispersibility, and its hydroxyl structure can assist in curing, increasing the crosslinking degree, improving the mechanical strength and thermal stability. However, excessive crosslinking will instead lead to a decline in performance, so the addition amount needs to be controlled;

[0022] (3) The sizing solution contains phenolic epoxy resin, bisphenol A epoxy resin, and the diluent dodecyl glycidyl ether. Phenolic epoxy resin has better thermal stability but a relatively high viscosity, so the addition amount should not be too high. At the same time, by introducing a diluent and the aforementioned hyperbranched flame retardant toughening agent to adjust the fluidity, a sizing solution with excellent processing performance, flame retardant performance, and mechanical properties is obtained. Specific Embodiments

[0023] The following is the preferred embodiment of the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. For those of ordinary skill in the art in this technical field, without departing from the principle of the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0024] Unless otherwise specified, the following parts are by mass;

[0025] Example 1: S1: Take 25 parts of 2,4-diaminophenol, 20 parts of p-hydroxybenzaldehyde, and 400 parts of ethanol, stir evenly, stir at 70 °C for 4 h, cool to room temperature, filter, wash, and dry in vacuum to obtain the modifier;

[0026] S2: Mix 25 parts of 3-(tert-butyldimethylsilyloxy) glutaric anhydride, 12 parts of modifier, 0.6 part of p-toluenesulfonic acid, 50 parts of water, and 50 parts of N,N-dimethylformamide, heat at 95 °C for 8 h, and dry by vacuum distillation to obtain a hyperbranched modifier;

[0027] S3: Take 25 parts of hyperbranched modifier, 8 parts of DOPO, 200 parts of ethanol, 80 parts of water, and 80 parts of N,N-dimethylformamide, heat and stir at 70 °C for 5 h, cool, filter, wash, and dry in vacuum to obtain a flame retardant and toughening agent;

[0028] S4: Take 1 part of hexagonal boron nitride nanosheet powder, 35 parts of urea, and 15 parts of water, ball mill at room temperature, with a 10-min interval for every 30-min ball milling, for a total of 2 h of ball milling, wash, and dry to obtain modified boron nitride micropowder;

[0029] S5: Take 20 parts of linear phenolic resin, 8 parts of modified boron nitride micropowder, 1 part of phenolic epoxy resin, 2 parts of epoxy resin, 0.2 part of dodecyl glycidyl ether, 3 parts of flame retardant and toughening agent, and 0.02 part of imidazole, mix evenly, and perform high-speed shear emulsification at a rate of 1000 rpm for 2 h to obtain a resin adhesive;

[0030] S6: Immerse a glass fiber cloth in the resin adhesive, pull it out, and dry at 190 °C for 3 min to obtain a semi-cured sheet; Stack 6 semi-cured sheets to obtain a substrate, attach copper foils to both sides of the substrate, and perform hot pressing and compounding at a hot pressing temperature of 210 °C, a hot pressing pressure of 4 Mpa, and a pressing time of 120 min to obtain a phenolic resin-based copper clad laminate.

[0031] Example 2: S1: Take 30 parts of 2,4-diaminophenol, 25 parts of p-hydroxybenzaldehyde, and 400 parts of ethanol, stir evenly, stir at 70 °C for 4 h, cool to room temperature, filter, wash, and dry in vacuum to obtain a modifier;

[0032] S2: Mix 30 parts of 3-(tert-butyldimethylsilyloxy) glutaric anhydride, 15 parts of modifier, 0.6 part of p-toluenesulfonic acid, 50 parts of water, and 50 parts of N,N-dimethylformamide, heat at 95 °C for 8 h, and dry by vacuum distillation to obtain a hyperbranched modifier;

[0033] S3: Take 30 parts of hyperbranched modifier, 10 parts of DOPO, 200 parts of ethanol, 80 parts of water, and 80 parts of N,N-dimethylformamide, heat and stir at 70 °C for 5 h, cool, filter, wash, and dry in vacuum to obtain a flame retardant and toughening agent;

[0034] S4: Take 1 part of hexagonal boron nitride nanosheet powder, 35 parts of urea, and 15 parts of water, ball mill at room temperature, with a 10-min interval for every 30-min ball milling, for a total of 2 h of ball milling, wash, and dry to obtain modified boron nitride micropowder;

[0035] S5: Take 20 parts of linear phenolic resin, 8 parts of modified boron nitride micropowder, 1 part of phenolic epoxy resin, 2 parts of epoxy resin, 0.2 part of dodecyl glycidyl ether, 4 parts of flame retardant toughening agent, and 0.02 part of imidazole. Mix them evenly, and after high-speed shear emulsification at a rate of 1000 rpm for 2 h, a resin glue solution is obtained;

[0036] S6: Immerse the glass fiber cloth in the resin glue solution, pull it out, and dry it at 190 °C for 3 min to obtain a semi-cured sheet; Stack 6 semi-cured sheets to obtain a substrate, stick copper foils on both sides of the substrate, and perform hot pressing and compounding. The hot pressing temperature is 210 °C, the hot pressing pressure is 4 Mpa, and the pressing time is 120 min to obtain a phenolic resin-based copper clad laminate.

[0037] Example 3: S1: Take 20 parts of 2,4-diaminophenol, 15 parts of p-hydroxybenzaldehyde, and 400 parts of ethanol. Stir them evenly, stir at 70 °C for 4 h, cool to room temperature, filter, wash, and dry in vacuum to obtain a modifier;

[0038] S2: Mix 20 parts of 3-(tert-butyldimethylsilyloxy)glutaric anhydride, 10 parts of the modifier, 0.6 part of p-toluenesulfonic acid, 50 parts of water, and 50 parts of N,N-dimethylformamide, heat at 95 °C for 8 h, and perform drying by vacuum distillation to obtain a hyperbranched modifier;

[0039] S3: Take 20 parts of the hyperbranched modifier, 5 parts of DOPO, 200 parts of ethanol, 80 parts of water, and 80 parts of N,N-dimethylformamide, heat and stir at 70 °C for 5 h, cool, filter, wash, and dry in vacuum to obtain a flame retardant toughening agent;

[0040] S4: Take 1 part of hexagonal boron nitride nanosheet powder, 35 parts of urea, and 15 parts of water, ball mill at room temperature. For every 30 min of ball milling, there is an interval of 10 min, and the total ball milling time is 2 h. Wash and dry to obtain modified boron nitride micropowder;

[0041] S5: Take 15 parts of linear phenolic resin, 6 parts of modified boron nitride micropowder, 1 part of phenolic epoxy resin, 2 parts of epoxy resin, 0.2 part of dodecyl glycidyl ether, 2 parts of flame retardant toughening agent, and 0.02 part of imidazole. Mix them evenly, and after high-speed shear emulsification at a rate of 1000 rpm for 2 h, a resin glue solution is obtained;

[0042] S6: Immerse the glass fiber cloth in the resin glue solution, pull it out, and dry it at 190 °C for 3 min to obtain a semi-cured sheet; Stack 6 semi-cured sheets to obtain a substrate, stick copper foils on both sides of the substrate, and perform hot pressing and compounding. The hot pressing temperature is 210 °C, the hot pressing pressure is 4 Mpa, and the pressing time is 120 min to obtain a phenolic resin-based copper clad laminate.

[0043] Comparative Example 1 (using itaconic anhydride instead of 3-(tert-butyldimethylsilyloxy) glutaric anhydride, and the remaining method steps are the same as those in Example 1): S1: Take 25 parts of 2,4-diaminophenol, 20 parts of p-hydroxybenzaldehyde, and 400 parts of ethanol, stir evenly, stir at 70 °C for 4 h, cool to room temperature, filter, wash, and dry in vacuum to obtain a modifier;

[0044] S2: Mix 25 parts of itaconic anhydride, 12 parts of the modifier, 0.6 part of p-toluenesulfonic acid, 50 parts of water, and 50 parts of N,N-dimethylformamide, heat at 95 °C for 8 h, and dry by vacuum distillation to obtain a hyperbranched modifier;

[0045] S3: Take 25 parts of the hyperbranched modifier, 8 parts of DOPO, 200 parts of ethanol, 80 parts of water, and 80 parts of N,N-dimethylformamide, heat and stir at 70 °C for 5 h, cool, filter, wash, and dry in vacuum to obtain a flame retardant and toughening agent;

[0046] S4: Take 1 part of hexagonal boron nitride nanosheet powder, 35 parts of urea, and 15 parts of water, ball mill at room temperature, ball mill for 30 min each time, with an interval of 10 min, for a total of 2 h of ball milling, wash, and dry to obtain modified boron nitride micropowder;

[0047] S5: Take 20 parts of linear phenolic resin, 8 parts of modified boron nitride micropowder, 1 part of phenolic epoxy resin, 2 parts of epoxy resin, 0.2 part of dodecyl glycidyl ether, 3 parts of the flame retardant and toughening agent, and 0.02 part of imidazole, mix evenly, and perform high-speed shear emulsification at a rate of 1000 rpm for 2 h to obtain a resin glue solution;

[0048] S6: Immerse the glass fiber cloth in the resin glue solution, pull it out, dry at 190 °C for 3 min to obtain a semi-cured sheet; stack 6 semi-cured sheets to obtain a substrate, attach copper foils to both sides of the substrate, and perform hot pressing and lamination. The hot pressing temperature is 210 °C, the hot pressing pressure is 4 Mpa, and the pressing time is 120 min to obtain a phenolic resin-based copper clad laminate.

[0049] Comparative Example 2 (changing the raw material addition amount of the resin glue solution, and the remaining method steps are the same as those in Example 1): S1: Take 25 parts of 2,4-diaminophenol, 20 parts of p-hydroxybenzaldehyde, and 400 parts of ethanol, stir evenly, stir at 70 °C for 4 h, cool to room temperature, filter, wash, and dry in vacuum to obtain a modifier;

[0050] S2: Mix 25 parts of 3-(tert-butyldimethylsilyloxy) glutaric anhydride, 12 parts of the modifier, 0.6 part of p-toluenesulfonic acid, 50 parts of water, and 50 parts of N,N-dimethylformamide, heat at 95 °C for 8 h, and dry by vacuum distillation to obtain a hyperbranched modifier;

[0051] S3: Take 25 parts of hyperbranched modifier, 8 parts of DOPO, 200 parts of ethanol, 80 parts of water, 80 parts of N,N-dimethylformamide, heat and stir at 70 °C for 5 h, cool, filter, wash, and dry in vacuum to obtain a flame retardant and toughening agent;

[0052] S4: Take 1 part of hexagonal boron nitride nanosheet powder, 35 parts of urea, 15 parts of water, ball mill at room temperature, every 30 min of ball milling, with an interval of 10 min, for a total of 2 h of ball milling, wash, and dry to obtain modified boron nitride micropowder;

[0053] S5: Take 20 parts of linear phenolic resin, 8 parts of modified boron nitride micropowder, 2 parts of phenolic epoxy resin, 1 part of epoxy resin, 0.1 part of dodecyl glycidyl ether, 1 part of flame retardant and toughening agent, 0.02 part of imidazole, mix evenly, and perform high-speed shear emulsification at a rate of 1000 rpm for 2 h to obtain a resin adhesive;

[0054] S6: Immerse the glass fiber cloth in the resin adhesive, pull it out, dry at 190 °C for 3 min to obtain a semi-cured sheet; Stack 6 semi-cured sheets to obtain a substrate, attach copper foils on both sides of the substrate, and perform hot pressing and compounding at a hot pressing temperature of 210 °C, a hot pressing pressure of 4 Mpa, and a pressing time of 120 min to obtain a phenolic resin-based copper clad laminate.

[0055] Comparative Example 3 (changing the preparation method of the flame retardant and toughening agent, and the other method steps are the same as those in Example 1): S1: Take 25 parts of 2,4-diaminophenol, 20 parts of p-hydroxybenzaldehyde, 400 parts of ethanol, stir evenly, stir at 70 °C for 4 h, cool to room temperature, filter, wash, and dry in vacuum to obtain a modifier;

[0056] S2: Take 17 parts of the modifier, 8 parts of hyperbranched modifier, 8 parts of DOPO, mix evenly to obtain a flame retardant and toughening agent;

[0057] S3: Take 1 part of hexagonal boron nitride nanosheet powder, 35 parts of urea, 15 parts of water, ball mill at room temperature, every 30 min of ball milling, with an interval of 10 min, for a total of 2 h of ball milling, wash, and dry to obtain modified boron nitride micropowder;

[0058] S4: Take 20 parts of linear phenolic resin, 8 parts of 3-(tert-butyldimethylsilyloxy) glutaric anhydride, 1 part of phenolic epoxy resin, 2 parts of epoxy resin, 0.2 part of dodecyl glycidyl ether, 3 parts of flame retardant and toughening agent, 0.02 part of imidazole, mix evenly, and perform high-speed shear emulsification at a rate of 1000 rpm for 2 h to obtain a resin adhesive;

[0059] S5: Immerse the fiberglass cloth in the resin sizing, pull it out, dry it at 190 °C for 3 min to obtain a prepreg; stack 6 prepregs to obtain a substrate, attach copper foils to both sides of the substrate, and perform hot pressing and lamination. The hot pressing temperature is 210 °C, the hot pressing pressure is 4 Mpa, and the pressing time is 120 min to obtain a phenolic resin-based copper clad laminate.

[0060] Comparative Example 4 (changing the addition amount of the modified boron nitride micropowder, and the remaining method steps are the same as those in Example 1): S1: Take 25 parts of 2,4-diaminophenol, 20 parts of p-hydroxybenzaldehyde, and 400 parts of ethanol, stir evenly, stir at 70 °C for 4 h, cool to room temperature, filter, wash, and dry in vacuum to obtain a modifier.

[0061] S2: Mix 25 parts of 3-(tert-butyldimethylsilyloxy)glutaric anhydride, 12 parts of the modifier, 0.6 part of p-toluenesulfonic acid, 50 parts of water, and 50 parts of N,N-dimethylformamide, heat at 95 °C for 8 h, and perform drying by vacuum distillation to obtain a hyperbranched modifier.

[0062] S3: Take 25 parts of the hyperbranched modifier, 8 parts of DOPO, 200 parts of ethanol, 80 parts of water, and 80 parts of N,N-dimethylformamide, heat and stir at 70 °C for 5 h, cool, filter, wash, and dry in vacuum to obtain a flame retardant and toughening agent.

[0063] S4: Take 1 part of hexagonal boron nitride nanosheet powder, 35 parts of urea, and 15 parts of water, ball mill at room temperature, ball mill for 30 min each time, with an interval of 10 min, and ball mill for a total of 2 h, wash, and dry to obtain modified boron nitride micropowder.

[0064] S5: Take 20 parts of linear phenolic resin, 10 parts of modified boron nitride micropowder, 1 part of phenolic epoxy resin, 2 parts of epoxy resin, 0.2 part of dodecyl glycidyl ether, 3 parts of the flame retardant and toughening agent, and 0.02 part of imidazole, mix evenly, and perform high-speed shear emulsification at a rate of 1000 rpm for 2 h to obtain a resin sizing.

[0065] S6: Immerse the fiberglass cloth in the resin sizing, pull it out, dry it at 190 °C for 3 min to obtain a prepreg; stack 6 prepregs to obtain a substrate, attach copper foils to both sides of the substrate, and perform hot pressing and lamination. The hot pressing temperature is 210 °C, the hot pressing pressure is 4 Mpa, and the pressing time is 120 min to obtain a phenolic resin-based copper clad laminate.

[0066] In the above examples, the test methods used are conventional methods unless otherwise specified; the raw materials used are commercially available unless otherwise specified, and the sources of the raw materials are as follows: ethanol (CAS: 64-17-5); bisphenol A epoxy resin (E44, epoxy equivalent 210-240 g / eq, Nanjing Bermuda Biotechnology Co., Ltd.); imidazole (CAS: 288-32-4); 2,4-diaminophenol (CAS: 95-86-3); p-hydroxybenzaldehyde (CAS: 123-08-0); 3-(tert-butyldimethylsilyloxy)glutaric anhydride (CAS: 91424- 40-7); p-toluenesulfonic acid (CAS: 104-15-4); N,N-dimethylformamide (CAS: 68-12-2); DOPO (9,10-dihydro-9-oxa-10-phosphane, CAS: 35948-25-5); hexagonal boron nitride nanosheet powder (Article No.: 52352, Xi'an Qiyue Biotechnology Co., Ltd.); urea (CAS: 57-13-6); linear phenolic resin (Grade No. 8013, Shandong Jinan Shengquan Group Co., Ltd.); phenolic epoxy resin (F51, Chengfeng); dodecyl glycidyl ether (CAS: 2461-18-9).

[0067] Experiment: Take the phenolic resin-based copper clad laminates prepared in Examples 1 to 3 and Comparative Examples 1 to 4, (1) refer to the standard ASTM D2863-2008, test the limiting oxygen index LOI, the sample size is 130 mm × 6.5 mm × 3.2 mm; (2) refer to GB / T 1043.1-2008, and perform impact test on a ZBC1400-A pendulum impact tester, the sample size is 100 mm × 12 × 6 mm; specific data are shown in the table below;

[0068]

[0069] Conclusion: In Comparative Example 1, itaconic anhydride was used to replace 3-(tert-butyldimethylsilyloxy) glutaric anhydride, and no silicon was introduced, resulting in a decrease in flame retardancy. In Comparative Example 2, the raw material addition amount of the resin glue was changed. The addition amount of phenolic epoxy resin was increased, while the addition amounts of epoxy resin, diluent, and flame retardant toughening agent were decreased. The properties of the obtained product were inferior to those of the examples. The possible reasons are as follows: When the viscosity is relatively high, the dispersibility of the modified boron nitride micropowder in the system will be affected, resulting in a decrease in the flame retardant effect. High viscosity may also lead to stress concentration during the curing process and reduce the impact strength. In Comparative Example 3, the modifier, 3-(tert-butyldimethylsilyloxy) glutaric anhydride, and DOPO were added separately, that is, there was no hyperbranched structure, and both the flame retardant ability and the impact strength decreased significantly. In Comparative Example 4, the addition amount of the modified boron nitride micropowder was increased. On the one hand, too much filler addition amount would lead to the problem of uneven dispersion. On the other hand, the addition of the modified boron nitride micropowder might lead to excessive crosslinking, thus affecting the flame retardant and impact properties. In summary, the phenolic resin-based copper clad laminate filled with boron nitride micropowder prepared by the present invention has both excellent flame retardancy and impact strength.

[0070] Finally, it should be noted that the above are only the preferred embodiments of the present invention, but the protection scope of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application, within the spirit and principle of the present invention, should be covered by the protection scope of this application; without conflict, the implementation manners and the features in the implementation manners of this application can be combined with each other. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims

1. A method for preparing a phenolic resin-based copper-clad laminate filled with boron nitride micropowder, characterized in that: The following steps are involved: S1: preparing a flame retardant toughening agent: taking 2,4-diaminophenol, p-hydroxybenzaldehyde, and ethanol, stirring for reaction, cooling, filtering, washing, and drying to obtain a modifier; mixing 3-(tert-butyldimethylsilyloxy)glutaric anhydride, a modifier, p-toluenesulfonic acid, water, and N,N-dimethylformamide, heating for reaction, and drying to obtain a hyperbranched modifier; taking a hyperbranched modifier, DOPO, ethanol, water, and N,N-dimethylformamide, heating and stirring, cooling, filtering, washing, and drying to obtain a flame retardant toughening agent; S2: Preparation of phenolic resin-based copper-clad laminate: phenolic resin, modified boron nitride powder, phenolic epoxy resin, epoxy resin, diluent, flame retardant toughening agent, imidazole, mix evenly, and emulsify at high speed shear to obtain resin glue; impregnate glass fiber cloth in the resin glue, pull it out, and dry it to obtain a prepreg; stack the prepregs to obtain a substrate, paste copper foil on both sides of the substrate, and hot-press and laminate to obtain a phenolic resin-based copper-clad laminate; The resin glue comprises the following raw materials, calculated by weight: 15 to 20 parts of phenolic resin, 6 to 8 parts of modified boron nitride powder, 0.5 to 1 part of phenolic epoxy resin, 1 to 2 parts of epoxy resin, 0.1 to 0.2 parts of diluent, 2 to 4 parts of flame retardant toughening agent, and 0.01 to 0.03 parts of imidazole; the flame retardant toughening agent comprises the following raw materials, calculated by weight: 20 to 30 parts of hyperbranched modifier, 5 to 10 parts of DOPO, 100 to 200 parts of ethanol, 50 to 100 parts of water, 50 to 1 00 parts of N,N-dimethylformamide; the modifier includes the following raw materials, by mass: 20-30 parts of 2,4-diaminophenol, 15-25 parts of p-hydroxybenzaldehyde, 300-400 parts of ethanol; the hyperbranched modifier includes the following raw materials, by mass: 20-30 parts of 3-(tert-butyldimethylsilyloxy)glutaric anhydride, 10-15 parts of modifier, 0.3-0.8 parts of p-toluenesulfonic acid, 40-60 parts of water, 40-60 parts of N,N-dimethylformamide; The preparation of the modified boron nitride micropowder comprises the following steps: taking hexagonal boron nitride nanosheet powder, urea and water, ball milling at room temperature, washing and drying to obtain modified boron nitride micropowder; The modified boron nitride micropowder comprises the following raw materials, calculated by weight: 0.5 to 1 part of hexagonal boron nitride nanosheet powder, 30 to 40 parts of urea, and 10 to 15 parts of water.

2. The method for preparing a phenolic resin-based copper-clad laminate filled with boron nitride micropowder according to claim 1, characterized in that: The conditions for the hot pressing composite are: the hot pressing temperature is 200-210° C., the hot pressing pressure is 3-4 MPa, and the pressing time is 100-150 min.

3. The method for preparing a phenolic resin-based copper-clad laminate filled with boron nitride powder according to claim 1, characterized in that: The preparation of the prepreg comprises the following steps: impregnating the glass fiber cloth with resin glue, pulling it out, and drying it to obtain the prepreg, wherein the glue amount is 150-200 g / m 2 .

4. A phenolic resin-based copper-clad laminate prepared according to the method for preparing a phenolic resin-based copper-clad laminate filled with boron nitride powder according to any one of claims 1 to 3.

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