A phenol novolac epoxy resin, its preparation method and application

Abstract

The present application relates to the technical fields of epoxy resin synthesis, in particular to a phenolic epoxy resin, a preparation method and application thereof. The phenolic epoxy resin has the structure shown in the following formula I: Formula I; wherein, in the formula I, n represents a polymerization degree, and is 0.2-0.6; R1, R2 and R3 are each independently selected from H or C1-C 10 alkyl; and R4 is selected from H or a fused ring group. The preparation method of the phenolic epoxy resin adds a phenolic compound for molecular modification in a refining stage, increases the proportion of secondary hydroxyl groups in the epoxy resin, promotes the curing of the epoxy resin, effectively shortens the gel time of the epoxy resin, does not change the mechanical properties of the cured epoxy resin, avoids adding a small molecule accelerator in the epoxy resin compound, and therefore can effectively improve the electrical properties of the cured product.

Description

Technical Field

[0001] This invention relates to the field of epoxy resin synthesis technology, specifically to a phenolic epoxy resin, its preparation method, and its applications. Background Technology

[0002] Epoxy resin boasts outstanding advantages such as low shrinkage, good adhesion, high corrosion resistance, and excellent electrical properties, making it widely used in electronic and electrical fields such as copper-clad laminates (CCLs) and encapsulation materials. Copper-clad laminates (CCLs) are products made by impregnating reinforcing materials such as paper or glass cloth with resin, covering one or both sides with copper foil, and then hot-pressing them. They are a raw material used in the manufacture of printed circuit boards (PCBs). As one of the main raw materials for CCL manufacturing, the structure and properties of epoxy resin play a crucial role in the development of CCLs. Different epoxy resins exhibit different properties; for example, o-cresol-type epoxy resin has high thermal and chemical stability, while bisphenol A-type epoxy resin has low shrinkage and low volatility. Each generation of resin determines the next generation of CCLs, and technological innovation continuously drives the optimization of CCL performance. With the rapid development of the electronic information industry, the advancement of electronic products and circuit assembly technology has driven the development of printed circuit board technology towards micro-aperture, fine lines, high-density wiring and high multilayer, which puts forward higher requirements for the heat resistance, dimensional stability and dielectric loss of copper clad laminates, thereby further promoting new demands for the development of epoxy resin performance.

[0003] Among various encapsulation materials, cured resins can effectively bond copper foil and other materials together to form a stable copper-clad laminate (CCL) structure. The curing agent and epoxy resin together influence the flow characteristics, thermal properties, and electrical properties of epoxy molding compounds. The performance of the cured system can be improved by changing the type of epoxy resin, curing agent, fillers, and additives. Gel time (GT) is a crucial indicator of the CCL adhesive, directly affecting the coating process parameters, oven temperature, and baking time. A short gel time results in a rapid increase in adhesive viscosity, causing some solvent to not evaporate in time, leading to lower strength and easier damage to the prepreg. A long gel time results in a slower viscosity increase, causing some adhesive to flow and drip, resulting in a lower adhesive content in the prepreg, exposing some glass fibers and leading to product defects. In existing technologies, the way to change the gel time of epoxy resin is to add a certain amount of accelerator to the formulation, such as polar substances like protic acids, tertiary amine compounds, Lewis acids, and ureas. During the preparation of copper clad laminates, the residue of trace small molecule compounds can easily cause shrinkage cavities or the presence of more free electrons, thereby affecting the dielectric properties and service life of the copper clad laminate. Summary of the Invention

[0004] This invention provides a phenolic epoxy resin, its preparation method, and its application, in order to solve the aforementioned problems existing in the prior art.

[0005] According to a first aspect of the present invention, a phenolic epoxy resin is provided having the structure shown in Formula I: Formula I; Where n represents the degree of polymerization, which is 0.2 to 0.6; R1, R2, and R3 are each independently selected from H or Cl-C. 10 The alkyl group; R4 is selected from H or fused ring groups.

[0006] The phenolic epoxy resin of this invention uses specific structural groups to modify the ends. By changing the molecular chain segments of the epoxy resin, the gel time of the epoxy resin can be effectively reduced. The phenolic epoxy resin of this invention can be used as a high-performance chip bottom bonding material with novel microstructures and has good application prospects. Applying the phenolic epoxy resin of this invention to copper clad laminates can form a stable copper clad laminate structure without affecting the dielectric properties and service life of the copper clad laminate.

[0007] Furthermore, R1, R2, and R3 are each independently selected from H or C1-C5 alkyl groups. In some specific embodiments, R1, R2, and R3 are each independently selected from H, methyl, or tert-butyl.

[0008] Preferably, the phenolic epoxy resin satisfies at least one of the following characteristics (1) to (5): (1) The epoxy equivalent of the phenolic epoxy resin is 210-220 g / mol; (2) The gelation time of the phenolic epoxy resin at a temperature of 171°C is 100-300s, more preferably 100-200s, and more preferably 140-180s; (3) The hydrolytic chlorine content of the phenolic epoxy resin is <200 ppm; (4) The total chlorine content of the phenolic epoxy resin is <1500 ppm; (5) The aged resin content of the phenolic epoxy resin is less than 4‰.

[0009] According to a second aspect of the present invention, the present invention also provides a method for preparing the above-mentioned phenolic epoxy resin, comprising the following steps: Step (1) Ring-opening reaction: 4,4'-methylenebis(2,6-dimethyl)phenol and epichlorohydrin are subjected to a ring-opening reaction in the presence of a co-catalyst and a first basic catalyst; Step (2) Ring-closing reaction: Add alkaline solution to the product obtained in step (1) to carry out the ring-closing reaction, and obtain a material containing epichlorohydrin (ECH) and crude resin. Step (3) Removal of ECH: The material containing ECH solvent and crude resin in step (2) is heated to remove ECH solvent and kept under vacuum to obtain crude resin; Step (4) Refining and modification of crude resin: Dissolve the crude resin obtained in step (3) in a solvent, add a second alkaline catalyst and a phase transfer catalyst, and add phenolic compounds to react. After the reaction is completed, extract, wash with water and remove solvent to obtain phenolic epoxy resin.

[0010] The preparation method of this invention involves adding phenolic compounds during the refining stage of epoxy resin preparation for molecular modification. This increases the content of secondary hydroxyl groups in the epoxy resin molecular chain, promotes epoxy resin curing, and effectively shortens the epoxy resin gel time without altering the mechanical properties of the cured epoxy resin. This avoids the need to add small-molecule accelerators to the epoxy resin mixture, thus effectively improving the electrical properties of the cured product. This invention completes molecular modification and refining / dechlorination in the same system through a one-step reaction, making the reaction process simple and easy to operate. Furthermore, phenolic compounds are weakly acidic compounds; their addition during the refining stage allows them to form sodium phenolate intermediates with alkaline solutions, effectively weakening the alkalinity of the mixed system and acting as a buffer solution. During the refining ring-closing and chain extension processes, the reduced alkalinity effectively reduces the amount of aged resin generated, resulting in minimal solid waste and efficient material utilization with a synergistic effect.

[0011] Further, in step (4), the phenolic compound is one or more of phenol, 2-methylphenol, p-methylphenol, p-tert-butylphenol, 2,5-dimethylphenol, 2,6-dimethylphenol, and β-naphthol, preferably 2,6-dimethylphenol.

[0012] Furthermore, the molar amount of the phenolic compound is 6-12% of the molar amount of 4,4'-methylenebis(2,6-dimethyl)phenol. If the amount is too high, the gel time of the epoxy resin will be too short, which does not meet the process requirements of general copper clad laminate manufacturers. The resin may not be fully cured, resulting in insufficient adhesion and affecting the overall safety of the structure. If the amount is too low, the modification effect will be insignificant, and the gel time of the epoxy resin will be too long. Preferably, it is 8-10%, and more preferably 9-10%.

[0013] Further, in step (4), the added second alkaline catalyst is a sodium hydroxide solution with a mass concentration of 10-20%; in some specific embodiments, in step (4), the added second alkaline catalyst is a sodium hydroxide solution with a mass concentration of 15%.

[0014] Furthermore, the phase transfer catalyst is any one of triethylbenzylammonium chloride, tetramethylammonium bromide, and triphenylmethylphosphine bromide, and the amount added is 0.5% to 1% of the weight of the crude resin.

[0015] Furthermore, the solvent in step (4) is any one or two of methyl isobutyl ketone, toluene, and 2-butanone.

[0016] Furthermore, the reaction temperature in step (4) is 80-85℃ and the reaction time is 1.5-2h.

[0017] Further, in step (1), the molar ratio of 4,4'-methylenebis(2,6-dimethyl)phenol to epichlorohydrin is 1:(4-8), preferably 1:(6.5-7).

[0018] Furthermore, the ring-opening reaction is carried out at a temperature of 40–70°C for 1–4 hours; preferably, the ring-opening reaction is carried out at a temperature of 53–57°C.

[0019] Furthermore, the ring-opening reaction is carried out under nitrogen protection.

[0020] Furthermore, the cocatalyst in step (1) is polyethylene glycol, and the amount added is 0.05% to 0.15% of the weight of the epichlorohydrin. The preparation method of the present invention does not require the addition of an organic cosolvent in the etherification stage. A small amount of polyether alcohol can accelerate the ring-opening reaction. The epoxy resin synthesized according to the steps are all within the specified range, effectively avoiding energy waste and having good atom economy.

[0021] Further, the first alkaline catalyst in step (1) is a sodium hydroxide solution, preferably a sodium hydroxide solution with a mass concentration of 40% to 50%. In some specific embodiments, the first alkaline catalyst in step (1) is a sodium hydroxide solution with a mass concentration of 48%.

[0022] Further, in step (2), the temperature of the closed-loop reaction is 50-80℃ and the time is 2-8h; preferably, the dripping time of the alkali solution is 4-6h, and the heat preservation time after the alkali solution is dripped is 0.5-1h; preferably, the temperature of the closed-loop reaction is 63-67℃.

[0023] Further, the alkaline solution in step (2) is a sodium hydroxide solution, preferably a sodium hydroxide solution with a mass concentration of 40% to 50%. In some specific embodiments, the alkaline solution in step (2) is a sodium hydroxide solution with a mass concentration of 48%.

[0024] Furthermore, the closed-loop reaction is carried out under vacuum conditions, with a vacuum pressure of -0.015 MPa to -0.025 MPa.

[0025] Furthermore, the sum of the amounts of the first alkaline catalyst in step (1) and the alkaline solution in step (2) is 0.9 to 0.95 times the theoretical amount of alkaline solution. Specifically, the amount of the first alkaline catalyst in step (1) accounts for 7 to 9% of the total amount of alkaline solution, and the amount of alkaline solution in step (2) accounts for 91 to 93% of the total amount of alkaline solution. It should be noted that the theoretical amount of alkaline solution is equal to the amount of phenolic hydroxyl groups, and both the sum of the amounts of alkaline solution and the amount of alkaline solution used refer to molar amounts.

[0026] Furthermore, in step (3), the conditions for removing ECH are: temperature 120-130℃, pressure 0-0.005MPa, and time 1-2h.

[0027] According to a third aspect of the present invention, the present invention also provides the application of the above-described phenolic epoxy resin or the phenolic epoxy resin prepared by the above-described preparation method in adhesive materials.

[0028] The beneficial effects of this invention are: The present invention provides a phenolic epoxy resin with specific structural groups modifying the ends, thereby effectively reducing the epoxy resin gel time by changing the epoxy resin molecular chain segments.

[0029] This invention provides a method for preparing phenolic epoxy resin. During the purification stage, a certain amount of phenolic compounds are added for molecular modification, increasing the proportion of secondary hydroxyl groups in the epoxy resin, promoting curing, and effectively shortening the gel time without altering the mechanical properties of the cured epoxy resin. This avoids the need to add small-molecule accelerators to the epoxy resin composition, thus effectively improving the electrical properties of the cured product. This invention completes molecular modification and purification / dechlorination in the same system through a one-step reaction, making the reaction process simple and easy to operate. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0031] Figure 1 This is an HPLC chromatogram of the epoxy resin prepared in the comparative examples and embodiments of the present invention.

[0032] Figure 2 The image shows the molecular weight distribution (GPC) plot of the epoxy resins prepared in the comparative examples and embodiments of this invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0034] The phenolic epoxy resins in the following examples have the structure shown in Formula I: Formula I; In Equation I, n represents the degree of polymerization, which is 0.2 to 0.6; R1, R2, and R3 are each independently selected from H or C1 to C2. 10 The alkyl group; R4 is selected from H or fused ring groups.

[0035] Example 1 This embodiment provides a phenolic epoxy resin of Formula I, wherein n is 0.2 to 0.6, and R1, R2, R3, and R4 are all H.

[0036] Its preparation method includes the following steps: (1) Ring-opening reaction: Add 1 mol of 4,4'-methylenebis(2,6-dimethyl)phenol, 6.8 mol of epichlorohydrin, and 0.0006 mol of PEG-200 to a four-necked flask and dissolve them completely to form a homogeneous solution. Under nitrogen protection, heat the solution to 55°C and add the alkaline catalyst using a peristaltic pump. At this time, the amount of etherified alkaline solution added accounts for 8% of the total amount of alkaline solution added. The reaction is carried out for 3 hours.

[0037] (2) Closed-loop reaction: The product in step (1) is heated to 65°C, and the alkaline solution is added dropwise using a peristaltic pump to control the time. The alkaline addition time is 5h. At this time, the amount of etherified alkaline solution added accounts for 92% of the total amount of alkaline solution added. After the addition is completed, the reaction is kept at the temperature for 0.5h.

[0038] (3) Removal of ECH: The material containing ECH solvent and crude resin in step (2) is heated to 130°C to remove ECH solvent, and then kept at P=-0.005MPa for 0.5h to obtain crude resin.

[0039] (4) Refining and modification of crude resin: The crude resin obtained in step (3) is dissolved in toluene, and 48g of 15% sodium hydroxide solution, 0.5g of triethylbenzylammonium chloride and 0.09mol of phenol are added. The mixture is reacted at 85℃ for 2h. After the reaction is completed, a series of refining processes such as extraction, water washing and solvent removal are carried out to obtain DMP phenolic special epoxy resin.

[0040] Example 2 This embodiment provides a phenolic epoxy resin of Formula I, wherein n is 0.2 to 0.6, R1 and R2 are both methyl, R3 is H, and R4 is H.

[0041] Its preparation method includes the following steps: (1) Ring-opening reaction: Add 1 mol of 4,4'-methylenebis(2,6-dimethyl)phenol, 6.8 mol of epichlorohydrin, and 0.0006 mol of PEG-200 to a four-necked flask and dissolve them completely to form a homogeneous solution. Under nitrogen protection, heat the solution to 55°C and add the alkaline catalyst using a peristaltic pump. At this time, the amount of etherified alkaline solution added accounts for 8% of the total amount of alkaline solution added. The reaction is carried out for 3 hours.

[0042] (2) Closed-loop reaction: The product in step (1) is heated to 65°C, and the alkaline solution is added dropwise using a peristaltic pump to control the time. The alkaline addition time is 5h. At this time, the amount of etherified alkaline solution added accounts for 92% of the total amount of alkaline solution added. After the addition is completed, the reaction is kept at the temperature for 0.5h.

[0043] (3) Removal of ECH: The material containing ECH solvent and crude resin in step (2) is heated to 130°C to remove ECH solvent, and then kept at P=-0.005MPa for 0.5h to obtain crude resin.

[0044] (4) Refining and modification of crude resin: The crude resin obtained in step (3) is dissolved in toluene, and 48g of 15% sodium hydroxide solution, 0.5g of triethylbenzylammonium chloride, and 0.09mol of 2,6-dimethylphenol are added. The mixture is reacted at 85℃ for 2h. After the reaction is completed, a series of refining processes such as extraction, water washing, and solvent removal are carried out to obtain DMP phenolic special epoxy resin.

[0045] Example 3 This embodiment provides a phenolic epoxy resin of Formula I, wherein n is 0.2 to 0.6, R1 is methyl, and R2, R3, and R4 are all H.

[0046] Its preparation method includes the following steps: (1) Ring-opening reaction: Add 1 mol of 4,4'-methylenebis(2,6-dimethyl)phenol, 6.8 mol of epichlorohydrin, and 0.0006 mol of PEG-200 to a four-necked flask and dissolve them completely to form a homogeneous solution. Under nitrogen protection, heat the solution to 55°C and add the alkaline catalyst using a peristaltic pump. At this time, the amount of etherified alkaline solution added accounts for 8% of the total amount of alkaline solution added. The reaction is carried out for 3 hours.

[0047] (2) Closed-loop reaction: The product in step (1) is heated to 65°C, and the alkaline solution is added dropwise using a peristaltic pump to control the time. The alkaline addition time is 5h. At this time, the amount of etherified alkaline solution added accounts for 92% of the total amount of alkaline solution added. After the addition is completed, the reaction is kept at the temperature for 0.5h.

[0048] (3) Removal of ECH: The material containing ECH solvent and crude resin in step (2) is heated to 130°C to remove ECH solvent, and then kept at P=-0.005MPa for 0.5h to obtain crude resin.

[0049] (4) Refining and modification of crude resin: The crude resin obtained in step (3) is dissolved in toluene, and 48g of 15% sodium hydroxide solution, 0.5g of triethylbenzylammonium chloride and 0.09mol of 2-methylphenol are added. The mixture is reacted at 85℃ for 2h. After the reaction is completed, a series of refining processes such as extraction, water washing and solvent removal are carried out to obtain DMP phenolic special epoxy resin.

[0050] Example 4 This embodiment provides a phenolic epoxy resin of Formula I, wherein n is 0.2 to 0.6, R3 is methyl, and R1, R2, and R4 are all H.

[0051] Its preparation method includes the following steps: (1) Ring-opening reaction: Add 1 mol of 4,4'-methylenebis(2,6-dimethyl)phenol, 6.8 mol of epichlorohydrin, and 0.0006 mol of PEG-200 to a four-necked flask and dissolve them completely to form a homogeneous solution. Under nitrogen protection, heat the solution to 55°C and add the alkaline catalyst using a peristaltic pump. At this time, the amount of etherified alkaline solution added accounts for 8% of the total amount of alkaline solution added. The reaction is carried out for 3 hours.

[0052] (2) Closed-loop reaction: The product in step (1) is heated to 65°C, and the alkaline solution is added dropwise using a peristaltic pump to control the time. The alkaline addition time is 5h. At this time, the amount of etherified alkaline solution added accounts for 92% of the total amount of alkaline solution added. After the addition is completed, the reaction is kept at the temperature for 0.5h.

[0053] (3) Removal of ECH: The material containing ECH solvent and crude resin in step (2) is heated to 130°C to remove ECH solvent, and then kept at P=-0.005MPa for 0.5h to obtain crude resin.

[0054] (4) Refining and modification of crude resin: The crude resin obtained in step (3) is dissolved in toluene, and 48g of 15% sodium hydroxide solution, 0.5g of triethylbenzylammonium chloride and 0.09mol of p-methylphenol are added. The mixture is reacted at 85℃ for 2h. After the reaction is completed, a series of refining processes such as extraction, water washing and solvent removal are carried out to obtain DMP phenolic special epoxy resin.

[0055] Example 5 This embodiment provides a phenolic epoxy resin of Formula I, wherein n is 0.2 to 0.6, R3 is tert-butyl, and R1, R2, and R4 are all H.

[0056] Its preparation method includes the following steps: (1) Ring-opening reaction: Add 1 mol of 4,4'-methylenebis(2,6-dimethyl)phenol, 6.8 mol of epichlorohydrin, and 0.0006 mol of PEG-200 to a four-necked flask and dissolve them completely to form a homogeneous solution. Under nitrogen protection, heat the solution to 55°C and add the alkaline catalyst using a peristaltic pump. At this time, the amount of etherified alkaline solution added accounts for 8% of the total amount of alkaline solution added. The reaction is carried out for 3 hours.

[0057] (2) Closed-loop reaction: The product in step (1) is heated to 65°C, and the alkaline solution is added dropwise using a peristaltic pump to control the time. The alkaline addition time is 5h. At this time, the amount of etherified alkaline solution added accounts for 92% of the total amount of alkaline solution added. After the addition is completed, the reaction is kept at the temperature for 0.5h.

[0058] (3) Removal of ECH: The material containing ECH solvent and crude resin in step (2) is heated to 130°C to remove ECH solvent, and then kept at P=-0.005MPa for 0.5h to obtain crude resin.

[0059] (4) Refining and modification of crude resin: The crude resin obtained in step (3) is dissolved in toluene, and 48g of 15% sodium hydroxide solution, 0.5g of triethylbenzylammonium chloride and 0.09mol of p-tert-butylphenol are added. The mixture is reacted at 85℃ for 2h. After the reaction is completed, a series of refining processes such as extraction, water washing and solvent removal are carried out to obtain DMP phenolic special epoxy resin.

[0060] Example 6 This embodiment provides a phenolic epoxy resin of Formula I, wherein n is 0.2 to 0.6, R1, R2, and R3 are all H, and R4 is a fused phenyl group.

[0061] Its preparation method includes the following steps: (1) Ring-opening reaction: Add 1 mol of 4,4'-methylenebis(2,6-dimethyl)phenol, 6.8 mol of epichlorohydrin, and 0.0006 mol of PEG-200 to a four-necked flask and dissolve them completely to form a homogeneous solution. Under nitrogen protection, heat the solution to 55°C and add the alkaline catalyst using a peristaltic pump. At this time, the amount of etherified alkaline solution added accounts for 8% of the total amount of alkaline solution added. The reaction is carried out for 3 hours.

[0062] (2) Closed-loop reaction: The product in step (1) is heated to 65°C, and the alkaline solution is added dropwise using a peristaltic pump to control the time. The alkaline addition time is 5h. At this time, the amount of etherified alkaline solution added accounts for 92% of the total amount of alkaline solution added. After the addition is completed, the reaction is kept at the temperature for 0.5h.

[0063] (3) Removal of ECH: The material containing ECH solvent and crude resin in step (2) is heated to 130°C to remove ECH solvent, and then kept at P=-0.005MPa for 0.5h to obtain crude resin.

[0064] (4) Refining and modification of crude resin: The crude resin obtained in step (3) is dissolved in toluene, and 48g of 15% sodium hydroxide solution, 0.5g of triethylbenzylammonium chloride and 0.09mol of β-naphthol are added. The mixture is reacted at 85℃ for 2h. After the reaction is completed, a series of refining processes such as extraction, water washing and solvent removal are carried out to obtain DMP phenolic special epoxy resin.

[0065] Example 7 This embodiment provides a phenolic epoxy resin of Formula I, wherein n is 0.2 to 0.6, R1 and R2 are both methyl, R3 is H, and R4 is H.

[0066] Its preparation method includes the following steps: (1) Ring-opening reaction: Add 1 mol of 4,4'-methylenebis(2,6-dimethyl)phenol, 6.8 mol of epichlorohydrin, and 0.0006 mol of PEG-200 to a four-necked flask and dissolve them completely to form a homogeneous solution. Under nitrogen protection, heat the solution to 55°C and add the alkaline catalyst using a peristaltic pump. At this time, the amount of etherified alkaline solution added accounts for 8% of the total amount of alkaline solution added. The reaction is carried out for 3 hours.

[0067] (2) Closed-loop reaction: The product in step (1) is heated to 65°C, and the alkaline solution is added dropwise using a peristaltic pump to control the time. The alkaline addition time is 5h. At this time, the amount of etherified alkaline solution added accounts for 92% of the total amount of alkaline solution added. After the addition is completed, the reaction is kept at the temperature for 0.5h.

[0068] (3) Removal of ECH: The material containing ECH solvent and crude resin in step (2) is heated to 130°C to remove ECH solvent, and then kept at P=-0.005MPa for 0.5h to obtain crude resin.

[0069] (4) Refining and modification of crude resin: The crude resin obtained in step (3) is dissolved in toluene, and 48g of 15% sodium hydroxide solution, 0.5g of triethylbenzylammonium chloride and 0.10 mol of 2,6-dimethylphenol are added. The mixture is reacted at 85℃ for 2h. After the reaction is completed, a series of refining processes such as extraction, water washing and solvent removal are carried out to obtain DMP phenolic special epoxy resin.

[0070] Example 8 This embodiment provides a phenolic epoxy resin of Formula I, wherein n is 0.2 to 0.6, R1 and R2 are both methyl, R3 is H, and R4 is H.

[0071] Its preparation method includes the following steps: (1) Ring-opening reaction: Add 1 mol of 4,4'-methylenebis(2,6-dimethyl)phenol, 6.8 mol of epichlorohydrin, and 0.0006 mol of PEG-200 to a four-necked flask and dissolve them completely to form a homogeneous solution. Under nitrogen protection, heat the solution to 55°C and add the alkaline catalyst using a peristaltic pump. At this time, the amount of etherified alkaline solution added accounts for 8% of the total amount of alkaline solution added. The reaction is carried out for 3 hours.

[0072] (2) Closed-loop reaction: The product in step (1) is heated to 65°C, and the alkaline solution is added dropwise using a peristaltic pump to control the time. The alkaline addition time is 5h. At this time, the amount of etherified alkaline solution added accounts for 92% of the total amount of alkaline solution added. After the addition is completed, the reaction is kept at the temperature for 0.5h.

[0073] (3) Removal of ECH: The material containing ECH solvent and crude resin in step (2) is heated to 130°C to remove ECH solvent, and then kept at P=-0.005MPa for 0.5h to obtain crude resin.

[0074] (4) Refining and modification of crude resin: The crude resin obtained in step (3) is dissolved in toluene, and 48g of 15% sodium hydroxide solution, 0.5g of triethylbenzylammonium chloride, and 0.08 mol of 2,6-dimethylphenol are added. The mixture is reacted at 85℃ for 2h. After the reaction is completed, a series of refining processes such as extraction, water washing, and solvent removal are carried out to obtain DMP phenolic special epoxy resin.

[0075] Comparative Example 1 This comparative example provides a method for preparing phenolic epoxy resin, comprising the following steps: (1) Ring-opening reaction: Add 1 mol of 4,4'-methylenebis(2,6-dimethyl)phenol, 6.8 mol of epichlorohydrin, and 0.0006 mol of PEG-200 to a four-necked flask and dissolve them completely to form a homogeneous solution. Under nitrogen protection, heat the solution to 55°C and add the alkaline catalyst using a peristaltic pump. At this time, the amount of etherified alkaline solution added accounts for 8% of the total amount of alkaline solution added. The reaction is carried out for 3 hours.

[0076] (2) Closed-loop reaction: The product in step (1) is heated to 65°C, and the alkaline solution is added dropwise using a peristaltic pump to control the time. The alkaline addition time is 5h. At this time, the amount of etherified alkaline solution added accounts for 92% of the total amount of alkaline solution added. After the addition is completed, the reaction is kept at the temperature for 0.5h.

[0077] (3) Removal of ECH: The material containing ECH solvent and crude resin in step (2) is heated to 130°C to remove ECH solvent, and then kept at P=-0.005MPa for 0.5h to obtain crude resin.

[0078] (4) Refining and modification of crude resin: Dissolve the crude resin obtained in step (3) in toluene, add 48g of 15% sodium hydroxide solution and 0.5g of triethylbenzylammonium chloride, react at 85℃ for 2h, and after the reaction is completed, carry out a series of refining processes such as extraction, water washing and solvent removal to obtain phenolic epoxy resin.

[0079] Comparative Example 2 This comparative example provides a method for preparing phenolic epoxy resin, comprising the following steps: (1) Ring-opening reaction: Add 1 mol of 4,4'-methylenebis(2,6-dimethyl)phenol, 6.8 mol of epichlorohydrin, and 0.0006 mol of PEG-200 to a four-necked flask and dissolve them completely to form a homogeneous solution. Under nitrogen protection, heat the solution to 65°C and add the alkaline catalyst using a peristaltic pump. At this time, the amount of etherified alkaline solution added accounts for 8% of the total amount of alkaline solution added. The reaction is carried out for 3 hours.

[0080] (2) Closed-loop reaction: The product in step (1) is heated to 65°C, and the alkaline solution is added dropwise using a peristaltic pump to control the time. The alkaline addition time is 5h. At this time, the amount of etherified alkaline solution added accounts for 92% of the total amount of alkaline solution added. After the addition is completed, the reaction is kept at the temperature for 0.5h.

[0081] (3) Removal of ECH: The material containing ECH solvent and crude resin in step (2) is heated to 130°C to remove ECH solvent, and then kept at P=-0.005MPa for 0.5h to obtain crude resin.

[0082] (4) Refining and modification of crude resin: Dissolve the crude resin obtained in step (3) in toluene, add 48g of 15% sodium hydroxide solution and 0.5g of triethylbenzylammonium chloride, react at 85℃ for 2h, and after the reaction is completed, carry out a series of refining processes such as extraction, water washing and solvent removal to obtain phenolic epoxy resin.

[0083] Table 1. Specifications of epoxy resin products prepared in the examples and comparative examples

[0084] *Gel time test method: The gel time test was conducted using a domestic GT-III gel time tester according to the IPC-TM-650 test method. The test temperature was T=171℃. Component A was DMP phenolic resin (80%) / acetone solution, and component B was a mixture with a mass ratio of 2PI:dicy:DMAC=1:10:140, where the resin solution:curing agent solution = 5:3.

[0085] Depend on Figure 1It can be seen that, compared with the epoxy resins obtained in Comparative Example 1 and Comparative Example 2, the composition of the modified phenolic epoxy resin of the present invention has changed significantly, with the modified epoxy resin component increasing in the t=30~40min range.

[0086] Depend on Figure 2 It can be seen that, compared with the epoxy resins obtained in Comparative Examples 1 and 2, the molecular weight distribution of the phenolic epoxy resins in Examples 1 to 8 has changed significantly, with an increase in the number of medium molecular weight components.

[0087] As shown in Table 1, the phenolic epoxy resin of this invention has an epoxy equivalent of 210–220 g / mol, a gel time of 140–200 s at 171°C (preferably 140–180 s), a hydrolytic chlorine content of <200 ppm, a total chlorine content of <1500 ppm, and an aged resin content of less than 4‰. Compared to the comparative example without the addition of phenolic compounds during the refining stage, the phenolic epoxy resin obtained by this invention has a shorter gel time, effectively improving the electrical properties of the cured product. Furthermore, the phenolic epoxy resin obtained by this invention has a lower aged resin content and extremely low solid waste content, enabling efficient material utilization. The gel time of the phenolic epoxy resin obtained by the method of this invention meets the process requirements of general copper-clad laminate manufacturers. Depending on the specific needs of each manufacturer, the gel time can be adjusted by adding different amounts of phenol to achieve precise control.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A phenolic epoxy resin, characterized in that, It has the structure shown in Equation I: Equation I; In Equation I, n represents the degree of polymerization, which is 0.2 to 0.6; R1, R2, and R3 are each independently selected from H or C1 to C2. 10 The alkyl group; R4 is selected from H or fused ring groups.

2. The phenolic epoxy resin according to claim 1, characterized in that, R1, R2, and R3 are each independently selected from H or C1 to C5 alkyl groups.

3. The phenolic epoxy resin according to claim 1, characterized in that, The phenolic epoxy resin satisfies at least one of the following characteristics (1) to (5): (1) The epoxy equivalent of the phenolic epoxy resin is 210-220 g / mol; (2) The gelation time of the phenolic epoxy resin at a temperature of 171°C is 100-300 s; (3) The hydrolytic chlorine content of the phenolic epoxy resin is <200 ppm; (4) The total chlorine content of the phenolic epoxy resin is <1500 ppm; (5) The aged resin content of the phenolic epoxy resin is less than 4‰.

4. The method for preparing the phenolic epoxy resin according to any one of claims 1-3, characterized in that, Includes the following steps: Step (1) Ring-opening reaction: 4,4'-methylenebis(2,6-dimethyl)phenol and epichlorohydrin are subjected to a ring-opening reaction in the presence of a co-catalyst and a first basic catalyst; Step (2) Ring-closing reaction: Add alkaline solution to the product obtained in step (1) to carry out the ring-closing reaction, and obtain a material containing epichlorohydrin and crude resin; Step (3) Removal of epichlorohydrin: The material containing epichlorohydrin and crude resin in step (2) is heated to remove epichlorohydrin and kept under vacuum to obtain crude resin. Step (4) Refining and modification of crude resin: Dissolve the crude resin obtained in step (3) in a solvent, add a second alkaline catalyst and a phase transfer catalyst, and add phenolic compounds to react. After the reaction is completed, extract, wash with water and remove solvent to obtain phenolic epoxy resin.

5. The preparation method according to claim 4, characterized in that, In step (4), the phenolic compound is one or more of phenol, 2-methylphenol, p-methylphenol, p-tert-butylphenol, 2,6-dimethylphenol, and β-naphthol, preferably 2,6-dimethylphenol; And / or, the molar amount of the phenolic compound is 6-12% of the molar amount of the 4,4'-methylenebis(2,6-dimethyl)phenol.

6. The preparation method according to claim 4, characterized in that, In step (4), the second alkaline catalyst added is a sodium hydroxide solution with a mass concentration of 10-20%; The phase transfer catalyst is any one of triethylbenzylammonium chloride, tetramethylammonium bromide, and triphenylmethylphosphine bromide, and the amount added is 0.5% to 1% of the weight of the crude resin. The solvent in step (4) is any one or two of methyl isobutyl ketone, toluene, and 2-butanone; The reaction temperature in step (4) is 80-85℃ and the reaction time is 1.5-2h.

7. The preparation method according to claim 4, characterized in that, In step (1), the molar ratio of 4,4'-methylenebis(2,6-dimethyl)phenol to epichlorohydrin is 1:(4-8), preferably 1:(6.5-7). And / or, the ring-opening reaction is carried out at a temperature of 40–70°C for a time of 1–4 h; preferably, the ring-opening reaction is carried out at a temperature of 53–57°C. And / or, the ring-opening reaction is carried out under nitrogen protection; And / or, the co-catalyst in step (1) is polyethylene glycol, and the amount added is 0.05% to 0.15% of the weight of the epichlorohydrin; And / or, the first alkaline catalyst in step (1) is a sodium hydroxide solution, preferably a sodium hydroxide solution with a mass concentration of 40% to 50%.

8. The preparation method according to claim 4, characterized in that, In step (2), the temperature of the closed-loop reaction is 50-80℃ and the time is 2-8h; preferably, the alkali solution is added for 4-6h and the heat preservation time after the alkali solution is added is 0.5-1h; preferably, the temperature of the closed-loop reaction is 63-67℃. And / or, the alkaline solution in step (2) is a sodium hydroxide solution, preferably a sodium hydroxide solution with a mass concentration of 40% to 50%; And / or, the sum of the amount of the first alkaline catalyst in step (1) and the amount of alkaline solution in step (2) is 0.9 to 0.95 times the theoretical amount of alkaline solution, wherein the amount of the first alkaline catalyst in step (1) accounts for 7 to 9% of the sum of the amount of alkaline solution, and the amount of alkaline solution in step (2) accounts for 91 to 93% of the sum of the amount of alkaline solution; And / or, the closed-loop reaction is carried out under vacuum conditions, with a vacuum pressure of -0.015 MPa to -0.025 MPa.

9. The preparation method according to claim 4, characterized in that, In step (3), the conditions for removing epichlorohydrin are: temperature 120-130℃, pressure 0-0.005MPa, and time 1-2h.

10. The use of the phenolic epoxy resin according to any one of claims 1-3 or the phenolic epoxy resin prepared by the preparation method according to any one of claims 4-9 in adhesive materials.

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