Phenolic resin glue solution for impact-resistant copper-clad laminate and preparation process of phenolic resin glue solution

Abstract

The invention discloses a phenolic resin glue solution for an impact-resistant copper-clad laminate and a preparation process thereof. According to the phenolic resin glue solution, the mechanical property of a prepreg can be effectively improved, the tensile strength and bending strength of the prepreg can be improved, and the heat-conducting property of a copper-clad plate can be effectively improved, so that heat energy of the copper-clad plate can be quickly dissipated; in the phenolation treatment process, part of phenol is condensed with-OH on a lignin aliphatic chain at an ortho-position, the reaction activity of high phenol content and the wettability on electronic glass fabric are better, and the prepreg has a good coating effect on the electronic glass fabric, so that the bending strength and other mechanical properties of the prepreg are effectively enhanced; a close packing three-dimensional heat conduction network is formed, and an efficient and abundant heat conduction network is constructed, so that the heat conductivity of the prepreg is further improved; the silane coupling agent KH560 is stably connected to a molecular chain of the lignin-based phenolic resin through a chemical bond, so that the mechanical property of the prepreg can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of phenolic resins, and more particularly to a phenolic resin adhesive for impact-resistant copper-clad laminates and a preparation process thereof. Background Art

[0002] A circuit board can be called a printed circuit board or printed circuit board. The main raw materials required for the production of printed circuit boards include copper clad laminates, prepregs, copper foil, chemicals, anode copper / tin / nickel, dry film, and ink. Copper clad laminates are the core components of printed circuit boards. They largely determine the quality, performance, processability, manufacturing cost, manufacturing level, and long-term reliability and stability of printed circuit boards. Copper clad laminates are a type of plate-like material made by impregnating electronic fiberglass cloth or other reinforcing materials with resin, covering one or both sides with copper foil, and then hot pressing.

[0003] Common resin materials include phenolic resin, epoxy resin, polyester resin, etc. These resin materials have good insulation properties, heat resistance and mechanical properties, and can meet the manufacturing requirements of printed circuit boards; phenolic resin has good acid resistance, heat resistance and mechanical properties. The development and research work on phenolic resin mainly focuses on flame retardancy, reinforcement, low smoke and molding applicability, and develops towards functionalization and refinement.

[0004] When phenolic resin is used in copper clad laminates, the impact resistance of the phenolic resin directly determines the impact resistance of the copper clad laminates. In addition, the thermal conductivity of the phenolic resin is low, and it cannot quickly dissipate the heat energy of the copper clad laminates. The copper clad laminates remain in a high temperature state for a long time, which directly affects their performance. Summary of the Invention

[0005] In order to overcome the above-mentioned defects of the prior art, embodiments of the present invention provide a phenolic resin adhesive for impact-resistant copper-clad laminates and a preparation process thereof.

[0006] The invention discloses a phenolic resin adhesive for impact-resistant copper-clad laminates, wherein the raw materials are calculated as follows by weight: 5.2-5.6% of enzymatically hydrolyzed lignin, 12.2-13.0% of phenol, 0.65-0.75% of sodium hydroxide, 17.8-18.2% of formaldehyde, 5.9-6.1% of a silane coupling agent, 14.8-15.2% of an epoxy resin, and the remainder is aluminum dioxide.

[0007] Furthermore, the silane coupling agent is one or a combination of silane coupling agent KH550, silane coupling agent KH560 and silane coupling agent KH570; the alumina contains alumina of two particle sizes, large-particle alumina is spherical, and the particle size distribution is between 20 and 80 μm, and small-particle alumina is spherical, and the particle size distribution is between 100 nm and 2 μm; the weight ratio of the large-particle alumina to the small-particle alumina is 1:1.

[0008] Furthermore, the raw materials of the phenolic resin glue for impact-resistant copper-clad laminates are calculated as follows by weight: 5.3-5.5% enzymatic lignin, 12.4-12.8% phenol, 0.68-0.72% sodium hydroxide, 17.9-18.1% formaldehyde, 5.95-6.05% silane coupling agent, 14.9-15.1% epoxy resin, and the rest is aluminum dioxide.

[0009] Furthermore, the raw materials of the phenolic resin glue for impact-resistant copper-clad laminates are calculated by weight as follows: 5.2% enzymatic lignin, 12.2% phenol, 0.65% sodium hydroxide, 17.8% formaldehyde, 5.9% silane coupling agent, 14.8% epoxy resin, and the rest is aluminum dioxide.

[0010] Furthermore, the raw materials of the phenolic resin glue for impact-resistant copper-clad laminates are calculated as follows by weight: 5.4% enzymatic lignin, 12.6% phenol, 0.70% sodium hydroxide, 18.0% formaldehyde, 6.0% silane coupling agent, 15.0% epoxy resin, and the rest is aluminum dioxide.

[0011] The preparation process of phenolic resin adhesive for impact-resistant copper-clad laminates is as follows:

[0012] Step 1: Weigh the enzymatically hydrolyzed lignin, phenol, sodium hydroxide, formaldehyde, silane coupling agent, epoxy resin, and aluminum dioxide in the raw materials;

[0013] Step 2: adding sodium hydroxide to deionized water, stirring to dissolve, adding enzymatic lignin and phenol, ultrasonically treating in a water bath for 40 to 60 minutes, and cooling to 65 to 75° C. to obtain a phenolic lignin solution;

[0014] Step 3: adding aluminum dioxide to deionized water, ultrasonically treating in a water bath for 10 to 20 minutes, then adding half the weight of a silane coupling agent, continuing ultrasonically treating in a water bath for 40 to 60 minutes, centrifuging, washing, and drying to obtain modified aluminum dioxide;

[0015] Step 4: adding epoxy resin, modified alumina and the remaining silane coupling agent to the phenolized lignin solution, ultrasonically treating in a water bath for 10 to 20 minutes, adding formaldehyde dropwise thereto in the form of a solution, ultrasonically treating in a water bath for 10 to 20 minutes, heating and continuing ultrasonically treating in a water bath for 20 to 40 minutes to obtain a phenolic resin glue for impact-resistant copper-clad laminates.

[0016] Furthermore, in step 2, the weight ratio of sodium hydroxide to deionized water is 1:240-250, the water bath temperature is 85-95° C., the ultrasonic frequency is 60-80 KHz, and the ultrasonic power is 400-600 W.

[0017] Furthermore, in step three, the weight ratio of aluminum dioxide to deionized water is 1:20-30, the ultrasonic frequency is 1.3-1.5 MHz, the ultrasonic power is 200-400 W, the water bath temperature is 50-60° C., deionized water and anhydrous ethanol are used for alternating washing treatment, and the product is dried at a temperature of 60-70° C. in a vacuum drying oven.

[0018] Furthermore, in step 4, before formaldehyde is added, the water bath temperature is 65-75° C., the ultrasonic frequency is 1.3-1.5 MHz, and the ultrasonic power is 200-400 W; after formaldehyde is added, the water bath temperature is 65-75° C., the ultrasonic frequency is 60-80 kHz, and the ultrasonic power is 400-600 W; the heating temperature is 85-95° C., and after heating, the water bath temperature is 85-95° C., the ultrasonic frequency is 1.3-1.5 MHz, and the ultrasonic power is 200-400 W; the concentration of the formaldehyde aqueous solution is 35-40%.

[0019] Furthermore, in step 2, the weight ratio of sodium hydroxide to deionized water is 1:245, the water bath temperature is 90°C, the ultrasonic frequency is 70KHz, and the ultrasonic power is 500W; in step 3, the weight ratio of aluminum dioxide to deionized water is 1:25, the ultrasonic frequency is 1.4MHz, the ultrasonic power is 300W, and the water bath temperature is 55°C. Deionized water and anhydrous ethanol are used for alternating washing treatment, and the mixture is dried at 65°C in a vacuum drying oven; in step 4, before formaldehyde is added, the water bath temperature is 70°C, the ultrasonic frequency is 1.4MHz, and the ultrasonic power is 300W; after formaldehyde is added, the water bath temperature is 70°C, the ultrasonic frequency is 70KHz, and the ultrasonic power is 500W; the heating temperature is 90°C, and after heating, the water bath temperature is 90°C, the ultrasonic frequency is 1.4MHz, and the ultrasonic power is 300W; the concentration of the formaldehyde aqueous solution is 38%.

[0020] Technical effects and advantages of the present invention:

[0021] 1. The phenolic resin glue for impact-resistant copper-clad laminate prepared by the raw material formula of the present invention can effectively improve the mechanical properties of the prepreg, improve the tensile strength and flexural strength of the prepreg, effectively improve the thermal conductivity of the copper-clad laminate, so that the heat energy of the copper-clad laminate can be quickly dissipated, and can effectively prevent the copper-clad laminate from being in a high-temperature state for a long time, thereby ensuring the performance of the copper-clad laminate; the alkali-catalyzed phenolization-modified enzymatic hydrolysis of lignin mainly takes the para-position condensation as the main method, significantly increases the phenolic hydroxyl content, and significantly increases the active sites of the enzymatic hydrolysis of lignin; during the phenolization process, part of the phenol condenses with the -OH on the fatty chain of lignin at the ortho position; the high phenol content has good reaction activity and wettability to electronic glass fiber cloth, has a good coating effect on the electronic glass fiber cloth, thereby effectively enhancing the flexural strength and Other mechanical properties: Small particles are filled between large particles to form a tightly packed three-dimensional thermal conductive network, thereby forming more thermal conductive pathways, building an efficient and rich thermal conductive network, and further improving the thermal conductivity of the prepreg; the surface grafting modification treatment of silica with silane coupling agent KH560 can effectively improve the contact and bonding effect between silica and phenolic resin-based materials, and can effectively improve the filling and modification effect of silica on phenolic resin glue, further improving the thermal conductivity of the prepreg; at the same time, the silane coupling agent KH560 is stably connected to the molecular chain of lignin-based phenolic resin through chemical bonds; it can effectively improve the mechanical properties of the prepreg; adding epoxy resin to lignin-based phenolic resin, and grafting epoxy resin to lignin-based phenolic resin molecules, can improve the mechanical properties of lignin-based phenolic resin;

[0022] 2. In the present invention, sodium hydroxide is added to deionized water, and then enzymatic lignin and phenol are added after dissolving. Under water bath ultrasonic treatment, the enzymatic lignin and phenol can be effectively dissolved and reacted in an alkaline environment to ensure the rapid synthesis of phenolic lignin solution; in step three, large-particle alumina and small-particle alumina are added to deionized water and ultrasonicated in a water bath, which can effectively perform ultrasonic dispersion treatment on the large-particle alumina and small-particle alumina, ensuring the uniformity of dispersion of silicon dioxide in deionized water, which is convenient for subsequent surface grafting treatment; a portion of silane coupling agent KH560 is added and ultrasonicated in a water bath, so that the silane coupling agent KH560 is fully in contact with the silicon dioxide, ensuring the grafting modification treatment on the silicon dioxide surface, and at the same time ensuring the remaining The phenolic resin is modified by using a silane coupling agent KH560; in step 4, epoxy resin, modified alumina, and silane coupling agent KH560 are added to the phenolized lignin solution and subjected to water bath ultrasonic treatment, so that the epoxy resin, modified alumina, and silane coupling agent KH560 can be uniformly dispersed in the phenolic resin precursor before the phenolic resin synthesis reaction, so that during the subsequent phenolic resin synthesis, the epoxy resin, modified alumina, and silane coupling agent KH560 can be better doped into the phenolic resin; formaldehyde aqueous solution is added dropwise, and water bath ultrasonic treatment is performed, so that formaldehyde is quickly incorporated into the resin glue solution, and water bath ultrasonic treatment is performed after heating, which can effectively ensure the rapid synthesis of the phenolic resin, thereby obtaining a phenolic resin glue solution for impact-resistant copper-clad laminates. DETAILED DESCRIPTION

[0023] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are within the scope of protection of the present invention.

[0024] Example 1:

[0025] The present invention provides a phenolic resin glue for impact-resistant copper-clad laminates, comprising 52 g of enzymatically hydrolyzed lignin, 122 g of phenol, 6.5 g of sodium hydroxide, 178 g of formaldehyde, 59 g of a silane coupling agent KH560, 148 g of an epoxy resin, and 434.5 g of aluminum dioxide; the aluminum dioxide comprises large-particle aluminum oxide and small-particle aluminum oxide, wherein 217.25 g of the large-particle aluminum oxide is spherical and has a particle size of 50 μm; and 217.25 g of the small-particle aluminum oxide is spherical and has a particle size distribution of 200 nm.

[0026] Enzymatic lignin was purchased from Hubei Langbowan Biopharmaceutical Co., Ltd., brand: Langbowan; phenol was purchased from Jinan Chuangshi Chemical Co., Ltd., item number: HG036; sodium hydroxide was purchased from Jinan Guocheng Chemical Co., Ltd., item number: 0413; formaldehyde was purchased from Nantong Runfeng Petrochemical Co., Ltd.; silane coupling agent KH560 was purchased from Shanghai Yuanye Biotechnology Co., Ltd.; epoxy resin was purchased from Jinan Shanhai Chemical Technology Co., Ltd., Phoenix brand epoxy E51; large-particle alumina was purchased from Yumu (Ningbo) New Materials Co., Ltd., item number: YM-Al2O3-W50; small-particle alumina was purchased from Yumu (Ningbo) New Materials Co., Ltd., item number: YM-Al2O3-N200;

[0027] The preparation process of phenolic resin adhesive for impact-resistant copper-clad laminates is as follows:

[0028] Step 1: Weigh the enzymatically hydrolyzed lignin, phenol, sodium hydroxide, formaldehyde, silane coupling agent KH560, epoxy resin, large-particle alumina, and small-particle alumina in the raw materials;

[0029] Step 2: Add sodium hydroxide to deionized water, stir and dissolve, add enzymatic lignin and phenol, perform ultrasonic treatment in a water bath for 50 minutes, and cool to 70°C to obtain a phenolic lignin solution;

[0030] Step 3: Add large-particle aluminum oxide and small-particle aluminum oxide to deionized water, perform water bath ultrasonic treatment for 15 minutes, then add half the weight of silane coupling agent KH560, continue water bath ultrasonic treatment for 50 minutes, centrifuge, wash, and dry to obtain modified aluminum dioxide;

[0031] Step 4: Add epoxy resin, modified alumina and the remaining silane coupling agent KH560 to the phenolized lignin solution, ultrasonically treat in a water bath for 15 minutes, add formaldehyde dropwise thereto in the form of a solution, ultrasonically treat in a water bath for 15 minutes, heat and continue ultrasonically treating in a water bath for 30 minutes to obtain a phenolic resin glue for impact-resistant copper-clad laminates.

[0032] In step 2, the weight ratio of sodium hydroxide to deionized water is 1:240, the water bath temperature is 85° C., the ultrasonic frequency is 60 kHz, and the ultrasonic power is 400 W. In step 3, the weight ratio of the total weight of large-particle alumina and small-particle alumina to deionized water is 1:20, the ultrasonic frequency is 1.3 MHz, the ultrasonic power is 200 W, and the water bath temperature is 50° C. Deionized water and anhydrous ethanol are used for alternating washing, and the product is dried at 60° C. in a vacuum drying oven. In step 4, before formaldehyde is added, the water bath temperature is 65° C., the ultrasonic frequency is 1.3 MHz, and the ultrasonic power is 200 W. After formaldehyde is added, the water bath temperature is 65° C., the ultrasonic frequency is 60 kHz, and the ultrasonic power is 400 W. The heating temperature is 85° C., and after heating, the water bath temperature is 85° C., the ultrasonic frequency is 1.3 MHz, and the ultrasonic power is 200 W. The concentration of the formaldehyde aqueous solution is 38%.

[0033] Example 2:

[0034] Different from Example 1, the phenolic resin glue for impact-resistant copper-clad laminates is prepared by weighing 5.6 g of enzymatic lignin, 13.0 g of phenol, 0.75 g of sodium hydroxide, 18.2 g of formaldehyde, 6.1 g of silane coupling agent KH560, 15.2 g of epoxy resin, 41.15 g of aluminum dioxide, 205.75 g of large-particle aluminum oxide, and 205.75 g of small-particle aluminum oxide.

[0035] Example 3:

[0036] Different from Examples 1-2, the phenolic resin glue for impact-resistant copper-clad laminates is prepared by weighing 5.4 g of enzymatic lignin, 12.6 g of phenol, 0.70 g of sodium hydroxide, 18.0 g of formaldehyde, 6.0 g of silane coupling agent KH560, 15.0 g of epoxy resin, 42.3 g of aluminum dioxide, 211.5 g of large-particle aluminum oxide, and 211.5 g of small-particle aluminum oxide.

[0037] Example 4:

[0038] The difference from Example 3 is that in step 2, the weight ratio of sodium hydroxide to deionized water is 1:245, the water bath temperature is 90°C, the ultrasonic frequency is 70 kHz, and the ultrasonic power is 500 W; in step 3, the weight ratio of the total weight of large-particle alumina and small-particle alumina to deionized water is 1:25, the ultrasonic frequency is 1.4 MHz, the ultrasonic power is 300 W, the water bath temperature is 55°C, deionized water and anhydrous ethanol are used for alternating washing, and the mixture is dried at 65°C in a vacuum drying oven; in step 4, before formaldehyde is added, the water bath temperature is 70°C, the ultrasonic frequency is 1.4 MHz, and the ultrasonic power is 300 W; after formaldehyde is added, the water bath temperature is 70°C, the ultrasonic frequency is 70 kHz, and the ultrasonic power is 500 W; the heating temperature is 90°C, and after heating, the water bath temperature is 90°C, the ultrasonic frequency is 1.4 MHz, and the ultrasonic power is 300 W; the concentration of the formaldehyde aqueous solution is 38%.

[0039] Comparative Example 1:

[0040] The difference from Example 4 is that: the phenolic resin glue for impact-resistant copper-clad laminates is as follows: 5.4 g of enzymatically hydrolyzed lignin, 12.6 g of phenol, 0.70 g of sodium hydroxide, 18.0 g of formaldehyde, 6.0 g of silane coupling agent KH560, 15.0 g of epoxy resin, and 42.3 g of large-particle aluminum oxide are weighed;

[0041] The preparation process of phenolic resin adhesive for impact-resistant copper-clad laminates is as follows:

[0042] Step 1: Weigh the enzymatically hydrolyzed lignin, phenol, sodium hydroxide, formaldehyde, silane coupling agent KH560, epoxy resin, and large-particle alumina in the raw materials;

[0043] Step 2: Add sodium hydroxide to deionized water, stir and dissolve, add enzymatic lignin and phenol, perform ultrasonic treatment in a water bath for 50 minutes, and cool to 70°C to obtain a phenolic lignin solution;

[0044] Step 3: Add large-particle aluminum oxide to deionized water, perform water bath ultrasonic treatment for 15 minutes, then add half the weight of silane coupling agent KH560, continue water bath ultrasonic treatment for 50 minutes, centrifuge, wash, and dry to obtain modified aluminum dioxide;

[0045] Step 4: Add epoxy resin, modified alumina and the remaining silane coupling agent KH560 to the phenolized lignin solution, ultrasonically treat in a water bath for 15 minutes, add formaldehyde dropwise thereto in the form of a solution, ultrasonically treat in a water bath for 15 minutes, heat and continue ultrasonically treating in a water bath for 30 minutes to obtain a phenolic resin glue for impact-resistant copper-clad laminates.

[0046] Comparative Example 2:

[0047] The difference from Example 4 is that: the phenolic resin glue for impact-resistant copper-clad laminates is as follows: 5.4 g of enzymatically hydrolyzed lignin, 12.6 g of phenol, 0.70 g of sodium hydroxide, 18.0 g of formaldehyde, 6.0 g of silane coupling agent KH560, 15.0 g of epoxy resin, and 42.3 g of small-particle aluminum oxide are weighed;

[0048] The preparation process of phenolic resin adhesive for impact-resistant copper-clad laminates is as follows:

[0049] Step 1: Weigh the enzymatic lignin, phenol, sodium hydroxide, formaldehyde, silane coupling agent KH560, epoxy resin, and small-particle alumina in the raw materials;

[0050] Step 2: Add sodium hydroxide to deionized water, stir and dissolve, add enzymatic lignin and phenol, perform ultrasonic treatment in a water bath for 50 minutes, and cool to 70°C to obtain a phenolic lignin solution;

[0051] Step 3: Add small-particle aluminum oxide to deionized water, perform water bath ultrasonic treatment for 15 minutes, then add half the weight of silane coupling agent KH560, continue water bath ultrasonic treatment for 50 minutes, centrifuge, wash, and dry to obtain modified aluminum dioxide;

[0052] Step 4: Add epoxy resin, modified alumina and the remaining silane coupling agent KH560 to the phenolized lignin solution, ultrasonically treat in a water bath for 15 minutes, add formaldehyde dropwise thereto in the form of a solution, ultrasonically treat in a water bath for 15 minutes, heat and continue ultrasonically treating in a water bath for 30 minutes to obtain a phenolic resin glue for impact-resistant copper-clad laminates.

[0053] Comparative Example 3:

[0054] The difference from Example 4 is that:

[0055] Phenolic resin glue for impact-resistant copper-clad laminates: weigh 18.0 g of phenol, 0.70 g of sodium hydroxide, 18.0 g of formaldehyde, 6.0 g of silane coupling agent KH560, 15.0 g of epoxy resin, 42.3 g of aluminum dioxide, 211.5 g of large-particle aluminum oxide, and 211.5 g of small-particle aluminum oxide;

[0056] The preparation process of phenolic resin adhesive for impact-resistant copper-clad laminates is as follows:

[0057] Step 1: Weigh phenol, sodium hydroxide, formaldehyde, silane coupling agent KH560, epoxy resin, large-particle alumina and small-particle alumina in the raw materials;

[0058] Step 2: Add sodium hydroxide to deionized water, stir to dissolve, add phenol, ultrasonicate in a water bath for 50 minutes, and cool to 70°C to obtain an alkaline phenol solution;

[0059] Step 3: Add large-particle aluminum oxide and small-particle aluminum oxide to deionized water, perform water bath ultrasonic treatment for 15 minutes, then add half the weight of silane coupling agent KH560, continue water bath ultrasonic treatment for 50 minutes, centrifuge, wash, and dry to obtain modified aluminum dioxide;

[0060] Step 4: Add epoxy resin, modified alumina and the remaining silane coupling agent KH560 to the alkaline phenol solution, ultrasonically treat in a water bath for 15 minutes, add formaldehyde dropwise thereto in the form of a solution, ultrasonically treat in a water bath for 15 minutes, heat and continue ultrasonically treating in a water bath for 30 minutes to obtain a phenolic resin glue for impact-resistant copper-clad laminates.

[0061] Comparative Example 4:

[0062] The difference from Example 4 is that:

[0063] Phenolic resin glue for impact-resistant copper-clad laminates: weigh 5.4 g of enzymatically hydrolyzed lignin, 12.6 g of phenol, 0.70 g of sodium hydroxide, 18.0 g of formaldehyde, 6.0 g of silane coupling agent KH560, 42.3 g of aluminum dioxide, 211.5 g of large-particle aluminum oxide, and 211.5 g of small-particle aluminum oxide;

[0064] The preparation process of phenolic resin adhesive for impact-resistant copper-clad laminates is as follows:

[0065] Step 1: Weigh the enzymatically hydrolyzed lignin, phenol, sodium hydroxide, formaldehyde, silane coupling agent KH560, large-particle alumina, and small-particle alumina in the raw materials;

[0066] Step 2: Add sodium hydroxide to deionized water, stir and dissolve, add enzymatic lignin and phenol, perform ultrasonic treatment in a water bath for 50 minutes, and cool to 70°C to obtain a phenolic lignin solution;

[0067] Step 3: Add large-particle aluminum oxide and small-particle aluminum oxide to deionized water, perform water bath ultrasonic treatment for 15 minutes, then add half the weight of silane coupling agent KH560, continue water bath ultrasonic treatment for 50 minutes, centrifuge, wash, and dry to obtain modified aluminum dioxide;

[0068] Step 4: Add the modified alumina and the remaining silane coupling agent KH560 to the phenolized lignin solution, perform water bath ultrasonic treatment for 15 minutes, add formaldehyde dropwise thereto in the form of a solution, perform water bath ultrasonic treatment for 15 minutes, heat and continue water bath ultrasonic treatment for 30 minutes after heating, to obtain a phenolic resin glue for impact-resistant copper clad laminates.

[0069] The phenolic resin glue for impact-resistant copper-clad laminates in the comparative examples and embodiments of the present invention was tested and processed:

[0070] First, electronic glass fiber cloth was immersed in a phenolic resin adhesive used for impact-resistant copper-clad laminates for 10 minutes, and then baked at 150°C for 5 minutes to produce a prepreg. The performance of the prepreg was tested.

[0071] GB / T1040.1-2018 is used to test the tensile strength of the prepreg;

[0072] GB / T1449-2005 is used to test the bending performance of prepreg;

[0073] The thermal conductivity of the prepreg was tested at room temperature using the TC3000E thermal conductivity meter produced by Xi'an Xiaxi Electronic Technology Co., Ltd. using the hot wire method.

[0074] The results are shown in Table 1:

[0075] Table 1:

[0076] Tensile strength (MPa) Flexural strength (MPa) Thermal conductivity W / (m·K) Comparative Example 1 83.8 356 0.63 Comparative Example 2 75.6 338 0.51 Comparative Example 3 68.2 296 1.15 Comparative Example 4 84.2 364 1.06 Example 1 95.6 385 1.42 Example 2 96.1 386 1.42 Example 3 97.3 391 1.44 Example 4 97.8 394 1.45

[0077] As can be seen from the above table, the phenolic resin adhesive for impact-resistant copper-clad laminates of the present invention can effectively improve the mechanical properties of the prepreg, increase the tensile strength and flexural strength of the prepreg, and effectively improve the thermal conductivity of the copper-clad laminate, so that the heat energy of the copper-clad laminate can be quickly dissipated, which can effectively prevent the copper-clad laminate from being in a high-temperature state for a long time, thereby ensuring the performance of the copper-clad laminate.

[0078] The sodium hydroxide in the present invention is used to provide an alkaline environment for the enzymatic hydrolysis of lignin and phenol, thereby promoting the reaction of the enzymatic hydrolysis of lignin and phenol. Formaldehyde reacts with the phenolized lignin to generate a lignin-based phenolic resin. The alkali-catalyzed phenolization-modified enzymatic hydrolysis of lignin is mainly based on para-position condensation, which significantly increases the phenolic hydroxyl content and significantly increases the active sites of the enzymatic hydrolysis of lignin. During the phenolization process, part of the phenol condenses with the -OH on the lignin fatty chain at the ortho position. In the process of synthesizing the phenolic resin, in addition to the -OH structure generated by the hydroxymethylation reaction on the benzene ring, the phenolic resin also contains alcoholic hydroxyl groups on the lignin side chain structure. As the lignin substitution rate increases, although the lignin structure becomes more and more obvious, the lignin-based phenolic resin basically maintains the same structure as the phenolic resin. The content has good reactivity and wettability on electronic glass fiber cloth, and has a good coating effect on the electronic glass fiber cloth, thereby effectively enhancing the bending strength and other mechanical properties of the semi-cured sheet; the silica adopts two different particle size specifications, and the silica of two different particle size specifications is filled into the phenolic resin glue, and the small particles are filled between the large particles to form a tightly packed three-dimensional thermal conductive network, thereby forming more thermal conductive pathways, constructing an efficient and rich thermal conductive network, and further improving the thermal conductivity of the semi-cured sheet; the hydroxyl groups adsorbed on the surface of the spherical silica form hydrogen bonds with the chain end groups of the phenolic resin molecules, thereby enhancing the interaction between the two, thereby limiting the thermal motion of the phenolic resin molecular chain, and due to the physical shielding effect of the inorganic filler, it can The silane coupling agent KH560 is used to carry out surface grafting modification of silica, which can effectively improve the contact and bonding effect between silica and phenolic resin-based materials, and effectively improve the filling and modification effect of silica on phenolic resin glue, further improving the thermal conductivity of the semi-cured sheet; at the same time, the silane coupling agent KH560 is stably connected to the molecular chain of lignin-based phenolic resin through chemical bonds; it can effectively improve the mechanical properties of the semi-cured sheet; adding epoxy resin to lignin-based phenolic resin, epoxy resin is grafted into lignin-based phenolic resin molecules, which can improve the mechanical properties of lignin-based phenolic resin; in step 2, sodium hydroxide is added to the deionized water. In step 3, large-particle aluminum oxide and small-particle aluminum oxide are added to deionized water for ultrasonic treatment in a water bath, which can effectively perform ultrasonic dispersion treatment on the large-particle aluminum oxide and small-particle aluminum oxide, thereby ensuring the uniform dispersion of silicon dioxide in the deionized water and facilitating subsequent surface grafting treatment; a portion of silane coupling agent KH560 is added for ultrasonic treatment in a water bath, so that the silane coupling agent KH560 is fully in contact with the silicon dioxide, thereby ensuring the grafting modification treatment on the silicon dioxide surface, and at the same time ensuring that the remaining silane coupling agent KH560 performs the modification treatment on the phenolic resin;In step 4, epoxy resin, modified alumina, and silane coupling agent KH560 are added to the phenolized lignin solution and ultrasonically treated in a water bath. This allows the epoxy resin, modified alumina, and silane coupling agent KH560 to be evenly dispersed within the phenolic resin precursor before the phenolic resin synthesis reaction, allowing the epoxy resin, modified alumina, and silane coupling agent KH560 to be better incorporated into the phenolic resin during the subsequent phenolic resin synthesis. A formaldehyde solution is then added dropwise and ultrasonically treated in a water bath to allow the formaldehyde to be quickly incorporated into the resin adhesive. After heating, ultrasonic treatment in a water bath is performed, effectively ensuring the rapid synthesis of the phenolic resin, thereby obtaining a phenolic resin adhesive for impact-resistant copper-clad laminates.

[0079] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A phenolic resin adhesive for impact-resistant copper-clad laminates, characterized by: The raw materials are calculated by weight percentage as follows: 5.2-5.6% of enzymatically hydrolyzed lignin, 12.2-13.0% of phenol, 0.65-0.75% of sodium hydroxide, 17.8-18.2% of formaldehyde, 5.9-6.1% of silane coupling agent, 14.8-15.2% of epoxy resin, and the rest is aluminum dioxide.

2. The phenolic resin adhesive for impact-resistant copper-clad laminates according to claim 1, characterized in that: The silane coupling agent is one or a combination of silane coupling agent KH550, silane coupling agent KH560 and silane coupling agent KH570; the alumina contains alumina of two particle sizes, large-particle alumina is spherical, and the particle size distribution is between 20 and 80 μm, and small-particle alumina is spherical, and the particle size distribution is between 100 nm and 2 μm; the weight ratio of the large-particle alumina to the small-particle alumina is 1:

1.

3. The phenolic resin glue for impact-resistant copper-clad laminates according to claim 2, characterized in that: The raw materials are calculated by weight percentage as follows: 5.3-5.5% of enzymatically hydrolyzed lignin, 12.4-12.8% of phenol, 0.68-0.72% of sodium hydroxide, 17.9-18.1% of formaldehyde, 5.95-6.05% of silane coupling agent, 14.9-15.1% of epoxy resin, and the rest is aluminum dioxide.

4. The phenolic resin adhesive for impact-resistant copper-clad laminates according to claim 2, characterized in that: The raw materials are calculated by weight percentage as follows: 5.2% of enzymatically hydrolyzed lignin, 12.2% of phenol, 0.65% of sodium hydroxide, 17.8% of formaldehyde, 5.9% of silane coupling agent, 14.8% of epoxy resin, and the rest is aluminum dioxide.

5. The phenolic resin adhesive for impact-resistant copper-clad laminates according to claim 2, characterized in that: The raw materials are calculated as follows according to weight percentage: 5.4% enzymatically hydrolyzed lignin, 12.6% phenol, 0.70% sodium hydroxide, 18.0% formaldehyde, 6.0% silane coupling agent, 15.0% epoxy resin, and the rest is aluminum dioxide.

6. A process for preparing a phenolic resin adhesive for impact-resistant copper-clad laminates, characterized in that: The specific preparation steps are as follows: Step 1: Weigh the enzymatically hydrolyzed lignin, phenol, sodium hydroxide, formaldehyde, silane coupling agent, epoxy resin, and aluminum dioxide in the raw materials; Step 2: adding sodium hydroxide to deionized water, stirring to dissolve, adding enzymatic lignin and phenol, ultrasonically treating in a water bath for 40 to 60 minutes, and cooling to 65 to 75° C. to obtain a phenolic lignin solution; Step 3: adding aluminum dioxide to deionized water, ultrasonically treating in a water bath for 10 to 20 minutes, then adding half the weight of a silane coupling agent, continuing ultrasonically treating in a water bath for 40 to 60 minutes, centrifuging, washing, and drying to obtain modified aluminum dioxide; Step 4: adding epoxy resin, modified alumina and the remaining silane coupling agent to the phenolized lignin solution, ultrasonically treating in a water bath for 10 to 20 minutes, adding formaldehyde dropwise thereto in the form of a solution, ultrasonically treating in a water bath for 10 to 20 minutes, heating and continuing ultrasonically treating in a water bath for 20 to 40 minutes to obtain a phenolic resin glue for impact-resistant copper-clad laminates.

7. The process for preparing the phenolic resin adhesive for impact-resistant copper-clad laminates according to claim 6, wherein: In step 2, the weight ratio of sodium hydroxide to deionized water is 1:240-250, the water bath temperature is 85-95° C., the ultrasonic frequency is 60-80 KHz, and the ultrasonic power is 400-600 W.

8. The process for preparing the phenolic resin adhesive for impact-resistant copper-clad laminates according to claim 7, wherein: In step three, the weight ratio of aluminum dioxide to deionized water is 1:20-30, the ultrasonic frequency is 1.3-1.5 MHz, the ultrasonic power is 200-400 W, the water bath temperature is 50-60° C., deionized water and anhydrous ethanol are used for alternating washing, and the product is dried at 60-70° C. in a vacuum drying oven.

9. The process for preparing the phenolic resin glue for impact-resistant copper-clad laminates according to claim 8, wherein: In step 4, before formaldehyde is added, the water bath temperature is 65-75° C., the ultrasonic frequency is 1.3-1.5 MHz, and the ultrasonic power is 200-400 W; after formaldehyde is added, the water bath temperature is 65-75° C., the ultrasonic frequency is 60-80 kHz, and the ultrasonic power is 400-600 W; the heating temperature is 85-95° C., and after heating, the water bath temperature is 85-95° C., the ultrasonic frequency is 1.3-1.5 MHz, and the ultrasonic power is 200-400 W; the concentration of the formaldehyde aqueous solution is 35-40%.

10. The process for preparing the phenolic resin adhesive for impact-resistant copper-clad laminates according to claim 9, wherein: In step 2, the weight ratio of sodium hydroxide to deionized water is 1:245, the water bath temperature is 90° C., the ultrasonic frequency is 70 kHz, and the ultrasonic power is 500 W; in step 3, the weight ratio of aluminum dioxide to deionized water is 1:25, the ultrasonic frequency is 1.4 MHz, the ultrasonic power is 300 W, and the water bath temperature is 55° C., deionized water and anhydrous ethanol are used for alternating washing treatment, and the mixture is dried at a temperature of 65° C. in a vacuum drying oven; in step 4, before formaldehyde is added, the water bath temperature is 70° C., the ultrasonic frequency is 1.4 MHz, and the ultrasonic power is 300 W; after formaldehyde is added, the water bath temperature is 70° C., the ultrasonic frequency is 70 kHz, and the ultrasonic power is 500 W; the heating temperature is 90° C., and after heating, the water bath temperature is 90° C., the ultrasonic frequency is 1.4 MHz, and the ultrasonic power is 300 W; the concentration of the formaldehyde aqueous solution is 38%.