A high heat-resistant linear phenolic resin based on organosilicon resin composite and its preparation method

Abstract

This invention discloses a high-heat-resistant linear phenolic resin based on organosilicon resin composite, prepared from the following raw materials in parts by weight: 35-50 parts phenol, 12-20 parts refined cashew nut shell extract, 28-40 parts formaldehyde solution (37% by mass), 6-15 parts composite modified resin, 1.2-3 parts acid catalyst, 0.6-1.5 parts co-catalyst, 0.15-0.3 parts polymerization inhibitor, 25-40 parts organic solvent, and 35-50 parts deionized water. This invention achieves a synergistic effect through the modification of the cashew nut shell shell molecular chain and in-situ grafting of organosilicon resin, combined with an oxalic acid-p-toluenesulfonic acid composite catalytic system and a stepwise prepolymerization process. This simultaneously improves the heat resistance, flexibility, environmental friendliness, and water resistance of the linear phenolic resin, while ensuring sufficient reaction and stable product performance. The preparation process is mild, requires no modification to existing equipment, and is suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention relates to the field of new polymer material preparation technology, specifically a high heat-resistant linear phenolic resin based on organosilicon resin composite and its preparation method. Background Technology

[0002] Linear phenolic resins are linear polymers produced by the condensation polymerization of phenols and aldehydes under acidic conditions. Due to their excellent electrical insulation, adhesion, dimensional stability, and basic heat resistance, they are widely used in electronics, chemicals, and composite materials. Traditional linear phenolic resins use phenol and formaldehyde as the main raw materials. Although the process is mature and the cost is low, they have several technical drawbacks: First, the high regularity of the molecular chains and few branches result in high brittleness and poor flexibility, making them prone to cracking after molding, limiting their application in impact-resistant and bending-resistant applications. Second, excessive formaldehyde addition during synthesis can easily lead to formaldehyde residue in the product, affecting safety and causing environmental pollution, which is inconsistent with the trend of green chemical development. Third, there is limited room for improvement in heat resistance; the 5% thermal decomposition temperature is mostly below 330℃, failing to meet the high-temperature resistance requirements of mid-to-high-end applications. Fourth, they have poor water resistance and chemical corrosion resistance, and are prone to performance degradation when exposed to humid or corrosive environments for extended periods.

[0003] To improve the performance of linear phenolic resins, existing technologies mostly employ single or simple modification with modifiers. Common modifiers include epoxy resins, silicone resins, and polyurethanes. Epoxy resin modification can improve the resin's adhesion and flexibility, but its effect on heat resistance is limited. Silicone resin modification can significantly improve heat and water resistance, but its compatibility with linear phenolic resins is poor, easily leading to phase separation, and it is also costly. Polyurethane modification can improve flexibility, but it significantly reduces the resin's heat resistance and thermal stability. Meanwhile, existing resin composite modification methods mostly employ physical blending, which results in weak bonding between the composite components and the phenolic resin molecular chains, poor interfacial compatibility, and a tendency for weak performance synergy and unstable product performance.

[0004] Cashew nut shell oil, a natural phenolic compound extracted from cashew nut shell oil, contains phenolic hydroxyl groups, C15 unsaturated long-chain alkyl groups, and a benzene ring in its molecular structure. The phenolic hydroxyl groups can undergo condensation reactions with formaldehyde and phenol, achieving chemical bonding with the linear phenolic resin molecular chains. The long-chain alkyl groups can disrupt the tight packing of the phenolic resin molecular chains, improving flexibility and hydrophobicity, while the benzene ring maintains the resin's heat resistance and rigidity. Cashew nut shell oil is widely available, inexpensive, and environmentally friendly, making it an ideal modifier for phenolic resins. However, existing cashew nut shell oil modification technologies are mostly focused on thermosetting phenolic resins, with limited research on the modification of linear phenolic resins. Furthermore, most existing technologies involve single-component cashew nut shell oil modification, resulting in limited improvement in heat resistance and poor synergy with other heat-resistant modifying components. Additionally, the modification process is prone to mismatches in reactivity between cashew nut shell oil and phenol or formaldehyde, leading to incomplete reactions and fluctuations in product performance.

[0005] Therefore, developing a synergistic modification scheme that combines directional modification of cashew phenol molecules with in-situ composite of organosilicon resin is crucial to solving the technical problems of difficulty in achieving both heat resistance and flexibility, poor composite compatibility, and high formaldehyde residue in traditional modification methods. This would allow for the preparation of linear phenolic resins with high heat resistance, excellent flexibility, environmental friendliness, and water resistance, with a simple process, controllable cost, and suitability for industrial production. This has become a pressing technical challenge in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a high heat-resistant linear phenolic resin based on organosilicon resin composite and its preparation method, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A high-heat-resistant linear phenolic resin based on organosilicon resin composite is prepared from the following raw materials in parts by weight: 35-50 parts phenol, 12-20 parts refined cashew nut shell phenol, 28-40 parts formaldehyde solution with a mass fraction of 37%, 6-15 parts composite modified resin, 1.2-3 parts acid catalyst, 0.6-1.5 parts co-catalyst, 0.15-0.3 parts polymerization inhibitor, 25-40 parts organic solvent, and 35-50 parts deionized water.

[0008] As a further aspect of this invention: refined cashew phenol: purity ≥99%, free phenol content ≤0.1%, to avoid impurities affecting the purity of electronic packaging; the phenolic hydroxyl groups in the molecular structure undergo condensation reaction with phenol and formaldehyde to achieve directional modification of the molecular chain; C15 unsaturated long-chain alkyl groups disrupt the tight packing of phenolic resin molecular chains, improving flexibility and hydrophobicity; benzene rings maintain the heat resistance and rigidity of the resin; and cashew phenol is a natural raw material, environmentally friendly, and free of harmful impurities; the weight ratio of cashew phenol to phenol is 1:2.5-4 to avoid excessive cashew phenol leading to a decrease in heat resistance and dielectric properties.

[0009] As a further aspect of the present invention: composite modified resin: the phenyl structure of methylphenyl organosilicon resin greatly improves the resin's heat resistance and thermal stability, while the silicon-oxygen bond improves hydrophobicity and dielectric properties. The combination of the two achieves synergistic enhancement of heat resistance, flexibility, and dielectric properties, and chemical bonding is achieved through in-situ grafting, thus solving the compatibility problem of physical blending.

[0010] As a further aspect of the present invention: the formaldehyde solution has a molar ratio of 0.6-0.8:1 to the total phenolic monomers, which is a near equimolar ratio to avoid excessive formaldehyde leading to residual free formaldehyde and to reduce the content of volatile impurities in the product from the source.

[0011] As a further aspect of the present invention: the acid catalyst is an aqueous solution of oxalic acid, and the co-catalyst is p-toluenesulfonic acid. Oxalic acid is a mild organic acid that controls the reaction rate and reduces side reactions. P-toluenesulfonic acid synergistically improves the catalytic efficiency, solves the problem of mismatched reactivity between cashew phenol and phenol and formaldehyde, ensures a full reaction without over-polymerization, avoids the generation of impurities, and the resin molecular chains prepared by the synergistic catalysis of the two are uniformly distributed and have stable performance.

[0012] As a further aspect of the present invention: Organic solvent: a mixed solvent of anhydrous ethanol and toluene is used, with a volume ratio of 1:1.2-2 and a moisture content of ≤0.5%, to avoid moisture affecting the reaction and dielectric properties of the product. Ethanol promotes the dissolution of phenolic monomers, and toluene improves the fluidity of resin processing and is easily removed by vacuum distillation without residue.

[0013] A method for preparing a high heat-resistant linear phenolic resin based on organosilicon resin composite includes the following steps: pre-dissolution and impurity removal → stepwise controllable prepolymerization → original flavor grafting composite → neutralization and precision washing → vacuum post-treatment; The original grafting composite is achieved by adding the composite modified resin to the prepolymer solution in 2-3 parts, and stirring at 90-98℃ and 180-220r / min for 1-1.5h to achieve chemical bonding grafting. Precision washing until the aqueous phase conductivity is ≤50μS / cm, high vacuum distillation at 0.09-0.1MPa and 120-130℃ for 2-3 hours, and precision filtration using a 200-300 mesh polytetrafluoroethylene filter membrane.

[0014] Compared with the prior art, the beneficial effects of the present invention are: This invention achieves a synergistic effect by modifying the cashew phenol molecular chain and grafting it onto organosilicon resin in situ, combined with an oxalic acid and p-toluenesulfonic acid composite catalytic system and a stepwise prepolymerization process. This simultaneously improves the heat resistance, flexibility, environmental friendliness, and water resistance of linear phenolic resin, while ensuring sufficient reaction and stable product performance. The preparation process is mild, requires no modification to existing equipment, and is suitable for large-scale industrial production. Detailed Implementation

[0015] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0016] Furthermore, to better illustrate this application, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that this application can be implemented even without certain specific details. In some instances, methods, means, and elements well-known to those skilled in the art have not been described in detail in order to highlight the main points of this application.

[0017] Example 1

[0018] A high-heat-resistant linear phenolic resin based on organosilicon resin composite is prepared from the following raw materials in parts by weight: 35 parts phenol, 12 parts refined cashew nut shell extract (purity 99.0%, free phenol content 0.08%), 28 parts formaldehyde solution with a mass fraction of 37%, 6 parts composite modified resin (methyl phenyl organosilicon resin with a mass fraction of 25%), 1.2 parts oxalic acid aqueous solution with a mass fraction of 50%, 0.6 parts p-toluenesulfonic acid, 0.15 parts hydroquinone, 25 parts anhydrous ethanol-toluene mixed solvent (volume ratio 1:1.2, moisture content 0.3%), and 35 parts deionized water (conductivity ≤10μS / cm).

[0019] The preparation method is as follows: Pre-dissolution and impurity removal: Add the specified amounts of phenol, refined cashew phenol, and anhydrous ethanol-toluene mixed solvent to a stainless steel reactor equipped with stirring, temperature control, condensation, and vacuum impurity removal devices. Adjust the stirring speed to 220 r / min, turn on the temperature control system to raise the temperature to 55℃, and maintain the temperature and stir for 25 min to fully dissolve the phenol monomers and form a homogeneous solution. Then turn on the vacuum impurity removal device and evacuate to a system vacuum degree of 0.05 MPa. Maintain this vacuum degree for 10 min to remove trace amounts of low-boiling-point impurities and moisture entrained in the raw materials. Turn off the vacuum device, add the specified amount of hydroquinone to the system, and continue stirring for 10 min to obtain a homogeneous and impurity-free phenol monomer solution.

[0020] Stepwise controllable prepolymerization: Maintaining the temperature inside the reactor at 55℃ and the stirring rate at 220 r / min, formaldehyde solution was slowly added dropwise to the phenol monomer solution at a rate of 1.2 drops / second through a constant pressure dropping funnel. During the addition process, the system temperature was continuously monitored, and the temperature was maintained stable through a temperature control system to avoid side reactions caused by excessively high local formaldehyde concentrations. After the formaldehyde addition was completed, 50% oxalic acid aqueous solution and p-toluenesulfonic acid were added to the system in sequence. After stirring and mixing for 5 min, the system temperature was raised to 75℃ and the reaction was maintained at this temperature for 2.5 h with continuous stirring to obtain cashew phenol modified linear phenolic resin prepolymer solution.

[0021] In-situ grafting composite: High-purity nitrogen gas is introduced into the reactor to purge the air inside the reactor, and nitrogen protection is maintained throughout the process; the composite modified resin is added to the prepolymer solution in two parts. First, 50% of the composite modified resin is added and stirred for 20 minutes until completely dispersed, then the remaining 50% of the composite modified resin is added and stirred for another 20 minutes; then the system temperature is raised to 90℃, the stirring rate is adjusted to 180 r / min, and the mixture is kept at this temperature and stirred for 1 hour to allow the composite modified resin to undergo a chemical bonding reaction with the active sites on the molecular chain of the prepolymer solution, thereby achieving in-situ grafting composite and obtaining the composite modified reaction solution.

[0022] Neutralization and Precision Washing: Turn off the temperature control system and allow the composite modified reaction solution to cool naturally to 60℃. Slowly add a 6% sodium hydroxide aqueous solution through a constant pressure dropping funnel, continuously stirring and monitoring the pH value of the system during the addition. Stop adding when the pH value reaches 7.0. Add the required amount of deionized water to the system, adjust the stirring speed to 200 r / min, stir for 18 min, then stop stirring and let stand for 30 min. After the system separates into layers, remove the lower aqueous phase through the bottom discharge port. Add an equal volume of deionized water again and repeat the above washing operation until the conductivity of the aqueous phase after washing is ≤45 μS / cm, thus obtaining the purified organic phase.

[0023] Vacuum post-treatment: The purified organic phase is transferred to a vacuum distillation apparatus, the vacuum system is turned on to evacuate to 0.09 MPa, and the temperature control system is turned on to raise the temperature to 120°C. This condition is maintained for vacuum distillation for 2 hours to completely remove organic solvents, unreacted trace monomers, and moisture from the system. After distillation, the vacuum and temperature control systems are turned off, and the material is allowed to cool naturally to 50°C. It is then filtered through a 200-mesh polytetrafluoroethylene filter membrane to remove trace insoluble substances from the system. The filtered material is collected in a dry storage tank and cooled to room temperature to obtain the high heat-resistant linear phenolic resin product for electronic packaging.

[0024] The performance test results are as follows: The product contains 0.05% free formaldehyde, 0.15% free phenol, 0.7% water absorption rate in 24 hours, and 0.2% volatile matter at 180℃ for 2 hours. The finished product is a pale yellow, transparent, viscous liquid with no impurities or irritating odor. It has excellent adhesion, stable dielectric properties, and is suitable for the packaging requirements of high-power semiconductor devices.

[0025] Example 2

[0026] A high-heat-resistant linear phenolic resin based on organosilicon resin composite is prepared from the following raw materials in parts by weight: 42 parts phenol, 16 parts refined cashew phenol (purity 99.2%, free phenol content 0.07%), 35 parts formaldehyde solution with a mass fraction of 37%, 10 parts modified resin (methyl phenyl organosilicon resin with a mass fraction of 25%), 2 parts oxalic acid aqueous solution with a mass fraction of 50%, 1.0 part p-toluenesulfonic acid, 0.2 parts hydroquinone, 32 parts anhydrous ethanol-toluene mixed solvent (volume ratio 1:1.5, moisture content 0.2%), and 42 parts deionized water (conductivity ≤10μS / cm).

[0027] The preparation method is as follows: Pre-dissolution and impurity removal: Phenol, refined cashew phenol and mixed solvent were added to the reaction vessel, the stirring rate was adjusted to 230 r / min, the temperature was raised to 58℃, and the mixture was stirred for 28 min; the vacuum was drawn to 0.055 MPa and impurities were removed for 12 min; hydroquinone was added and stirring was continued for 11 min to obtain a homogeneous and impurity-free phenol monomer solution.

[0028] Stepwise controllable prepolymerization: Maintain the system temperature at 58℃, add formaldehyde solution dropwise at a rate of 1.5 drops / second, and after the addition is complete, add oxalic acid aqueous solution and p-toluenesulfonic acid, stir and mix for 6 minutes; raise the temperature to 80℃, keep the reaction at this temperature for 3 hours, and obtain cashew phenol modified linear phenolic resin prepolymer solution.

[0029] In-situ grafting composite: High-purity nitrogen gas is introduced to maintain a protective state. The composite modified resin is added to the prepolymer solution in two portions, and the mixture is stirred for 25 minutes after each addition. The temperature is raised to 95°C, the stirring rate is adjusted to 200 r / min, and the mixture is kept at this temperature and stirred for 1.2 hours to complete the in-situ grafting composite and obtain the composite modified reaction solution.

[0030] Neutralization and fine washing: Cool the reaction solution to 60℃, add 7% sodium hydroxide aqueous solution to adjust the pH to 7.2; add deionized water, stir for 19 min and let stand to separate the layers, remove the aqueous phase; repeat the washing operation until the conductivity of the aqueous phase is ≤40μS / cm, to obtain the purified organic phase.

[0031] Vacuum post-treatment: The purified organic phase was placed in a vacuum distillation apparatus, vacuumed to 0.095 MPa, heated to 125°C, and distilled under reduced pressure for 2.5 h; then cooled to 52°C, and filtered through a 250-mesh polytetrafluoroethylene filter membrane for precision filtration. After cooling to room temperature, the finished resin was obtained.

[0032] The performance test results are as follows: The product contains 0.05% free formaldehyde, 0.1% free phenol, 0.6% water absorption rate over 24 hours, and 0.2% volatile matter at 180℃ for 2 hours. The finished product is a pale yellow, transparent, viscous liquid with no impurities or irritating odor. It has excellent adhesion, stable dielectric properties, and is suitable for the packaging requirements of high-power semiconductor devices.

[0033] Example 3

[0034] A high-heat-resistant linear phenolic resin based on organosilicon resin composite is prepared from the following raw materials in parts by weight: 50 parts phenol, 20 parts refined cashew phenol (purity 99.5%, free phenol content 0.05%), 40 parts formaldehyde solution with a mass fraction of 37%, 15 parts composite modified resin (methyl phenyl organosilicon resin with a mass fraction of 25%), 3 parts oxalic acid aqueous solution with a mass fraction of 50%, 1.5 parts p-toluenesulfonic acid, 0.3 parts hydroquinone, 40 parts anhydrous ethanol-toluene mixed solvent (volume ratio 1:2, moisture content 0.1%), and 50 parts deionized water (conductivity ≤10μS / cm).

[0035] The preparation method is as follows: Pre-dissolution and impurity removal: Phenol, refined cashew phenol and mixed solvent were added to the reaction vessel, the stirring rate was adjusted to 250 r / min, the temperature was raised to 60℃, and the mixture was stirred for 30 min; the vacuum was drawn to 0.06 MPa and impurities were removed for 15 min; hydroquinone was added and stirring was continued for 15 min to obtain a homogeneous and impurity-free phenol monomer solution.

[0036] Stepwise controllable prepolymerization: Maintain the system temperature at 60℃, add formaldehyde solution at a rate of 2 drops / second, and after the addition is complete, add oxalic acid aqueous solution and p-toluenesulfonic acid, stir and mix for 8 minutes; raise the temperature to 85℃, keep the reaction at this temperature for 4 hours, and obtain cashew phenol modified linear phenolic resin prepolymer solution.

[0037] In-situ grafting composite: High-purity nitrogen gas is introduced to maintain a protective state. The composite modified resin is added to the prepolymer solution in three portions, and stirred for 30 minutes after each addition. The temperature is raised to 98℃, the stirring rate is adjusted to 220 r / min, and the mixture is kept at this temperature and stirred for 1.5 h to complete the in-situ grafting composite and obtain the composite modified reaction solution.

[0038] Neutralization and fine washing: Cool the reaction solution to 60℃, add 8% sodium hydroxide aqueous solution to adjust the pH to 7.5; add deionized water, stir for 20 min and let stand to separate the layers, remove the aqueous phase; repeat the washing operation until the conductivity of the aqueous phase is ≤35μS / cm, to obtain the purified organic phase.

[0039] Vacuum post-treatment: The purified organic phase is placed in a vacuum distillation apparatus, vacuumed to 0.1 MPa, heated to 130°C, and distilled under reduced pressure for 3 hours; then cooled to 55°C, and precisely filtered through a 300-mesh polytetrafluoroethylene filter membrane, and cooled to room temperature to obtain the finished resin.

[0040] The performance test results are as follows: free formaldehyde content 0.05%, free phenol content 0.12%, 24h water absorption rate 0.8%, volatile matter at 180℃ / 2h 0.2%, the finished product is a light yellow transparent viscous liquid, free of impurities and irritating odor, with excellent adhesion and stable dielectric properties, suitable for the packaging requirements of high-power semiconductor devices.

[0041] Comparative Example 1 (linear phenolic resin for traditional electronic packaging, unmodified composite) A high-heat-resistant linear phenolic resin based on organosilicon resin composite is prepared from the following raw materials in parts by weight: 42 parts phenol, 35 parts formaldehyde solution with a mass fraction of 37%, 2 parts oxalic acid aqueous solution with a mass fraction of 50%, 1.0 part p-toluenesulfonic acid, 0.2 parts hydroquinone, 32 parts anhydrous ethanol-toluene mixed solvent (volume ratio 1:1.5, moisture content 0.2%), and 42 parts deionized water (conductivity ≤10μS / cm); without refined cashew phenol and composite modified resin.

[0042] The preparation method is as follows: Except for the absence of the in-situ grafting composite step, the rest of the preparation process is completely consistent with Example 2, that is, after completing the stepwise controllable prepolymerization, the neutralization, precision washing and vacuum post-treatment steps are directly carried out.

[0043] The performance test results are as follows: The product contains 0.18% free formaldehyde, 0.35% free phenol, 1.8% water absorption rate in 24 hours, and 0.8% volatile matter at 180℃ for 2 hours. The finished product is a pale yellow transparent liquid with a slightly irritating odor. It is brittle and prone to cracking after packaging. Furthermore, its high volatile matter content makes it easy to generate bubbles and voids during the curing process, which fails to meet the performance requirements of mid-to-high-end electronic packaging.

[0044] Comparative Example 2 (Single cashew phenol modification, without composite modified resin) A high-heat-resistant linear phenolic resin based on organosilicon resin composite is prepared from the following raw materials in parts by weight: 42 parts phenol, 16 parts refined cashew nut shell extract (purity 99.2%, free phenol content 0.07%), 35 parts formaldehyde solution (37% by mass), 2 parts oxalic acid aqueous solution (50% by mass), 1.0 part p-toluenesulfonic acid, 0.2 parts hydroquinone, 32 parts anhydrous ethanol-toluene mixed solvent (volume ratio 1:1.5, moisture content 0.2%), and 42 parts deionized water (conductivity ≤10μS / cm); without composite modification resin.

[0045] The preparation method is as follows: Except for the absence of the in-situ grafting composite step, the rest of the preparation process is completely consistent with that of Example 2.

[0046] The performance test results are as follows: The free formaldehyde content is 0.07%, the free phenol content is 0.16%, the 24-hour water absorption rate is 0.7%, and the volatile matter at 180℃ / 2h is 0.25%. The finished product is a pale yellow transparent liquid with no irritating odor. Its flexibility and environmental friendliness are significantly improved compared to traditional resins, but the improvement in heat resistance is limited. The 5% thermal decomposition temperature is below 340℃, which cannot meet the high-temperature packaging requirements of high-power electronic devices.

[0047] Comparative Example 3 (physical blending, non-in-situ grafting) The raw material ratio is exactly the same as in Example 2, with no adjustment to the principle ratio.

[0048] The preparation method is as follows: The pre-dissolution and impurity removal, and step-by-step controllable prepolymerization steps are completely consistent with those in Example 2, resulting in a cashew phenol modified linear phenolic resin prepolymer solution. The stepwise addition process was eliminated. The composite modified resin was added directly to the prepolymer solution in one go. The stirring speed was adjusted to 200 r / min, and the mixture was physically blended at room temperature for 30 min to obtain the mixture. The neutralization, precision washing, and vacuum post-treatment steps are completely consistent with those in Example 2.

[0049] The performance test results are as follows: The free formaldehyde content is 0.06%, the free phenol content is 0.17%, the water absorption rate is 0.9% in 24 hours, the volatile matter at 180℃ for 2 hours is 0.23%, and the finished product is a pale yellow slightly turbid liquid with slight phase separation. The flexibility and dielectric properties are significantly reduced compared to Example 2. Furthermore, because the composite modified resin and the prepolymer liquid are only physically bonded, the interfacial compatibility is poor, and long-term use is prone to performance delamination, resulting in insufficient stability of the encapsulation structure.

[0050] The test results are compared in the table below: Example 1 135 340 21 3.3 Example 2 142 352 24 3.6 Example 3 138 346 22 3.4 Comparative Example 1 123 328 13 4.2 Comparative Example 2 130 338 21 3.9 Comparative Example 3 132 340 19 3.9 The linear phenolic resin prepared by this invention has a glass transition temperature of 135℃, a 5% thermal decomposition temperature of 345℃, an impact strength of 22kJ / m², a free phenol content of 0.18%, a 24h water absorption rate of 0.8%, a dielectric constant (1MHz) of 3.8, a dielectric loss tangent (1MHz) of 0.02, and a volatile content of 0.1% at 150℃ / 2h. The finished product is a pale yellow, transparent, viscous liquid with no visible impurities, no irritating odor, good fluidity, and is suitable for electronic packaging process requirements.

[0051] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0052] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A high-heat-resistant linear phenolic resin based on organosilicon resin composite, characterized in that, It is prepared from the following raw materials in parts by weight: 35-50 parts phenol, 12-20 parts refined cashew phenol, 28-40 parts formaldehyde solution with a mass fraction of 37%, 6-15 parts composite modified resin, 1.2-3 parts acid catalyst, 0.6-1.5 parts co-catalyst, 0.15-0.3 parts polymerization inhibitor, 25-40 parts organic solvent, and 35-50 parts deionized water.

2. The high heat-resistant linear phenolic resin based on organosilicon resin composite according to claim 1, characterized in that, Refined cashew nut shell phenol: purity ≥99%, free phenol content ≤0.1%, avoiding impurities from affecting the purity of electronic packaging. The phenolic hydroxyl groups in the molecular structure undergo condensation reaction with phenol and formaldehyde to achieve directional modification of the molecular chain. C15 unsaturated long-chain alkyl groups break the tight packing of phenolic resin molecular chains, improving flexibility and hydrophobicity. Benzene rings maintain the heat resistance and rigidity of the resin. Cashew nut shell phenol is a natural raw material, environmentally friendly, and free of harmful impurities. The weight ratio of cashew nut shell phenol to phenol is 1:2.5-4 to avoid excessive cashew nut shell phenol from causing a decrease in heat resistance and dielectric properties.

3. The high heat-resistant linear phenolic resin based on organosilicon resin composite according to claim 1, characterized in that, Composite modified resin: The phenyl structure of methylphenyl organosilicon resin greatly improves the resin's heat resistance and thermal stability, while the silicon-oxygen bond improves hydrophobicity and dielectric properties. The combination of the two achieves a synergistic effect on heat resistance, flexibility, and dielectric properties, and chemical bonding is achieved through in-situ grafting, solving the compatibility problem of physical blending.

4. The high heat-resistant linear phenolic resin based on organosilicon resin composite according to claim 1, characterized in that, Formaldehyde solution: The total molar ratio of formaldehyde to phenol monomers is 0.6-0.8:1, which is a near equimolar ratio to avoid excessive formaldehyde and resulting in residual free formaldehyde, thereby reducing the content of volatile impurities in the product from the source.

5. The high heat-resistant linear phenolic resin based on organosilicon resin composite according to claim 1, characterized in that, The acid catalyst is an aqueous solution of oxalic acid, and the co-catalyst is p-toluenesulfonic acid. Oxalic acid is a mild organic acid that controls the reaction rate and reduces side reactions. P-toluenesulfonic acid synergistically improves the catalytic efficiency and solves the problem of mismatch in reactivity between cashew phenol and phenol and formaldehyde, ensuring that the reaction is complete and without over-polymerization, and avoiding the generation of impurities. The resin prepared by the synergistic catalysis of the two has a uniform molecular chain distribution and stable performance.

6. The high heat-resistant linear phenolic resin based on organosilicon resin composite according to claim 1, characterized in that, Organic solvent: A mixture of anhydrous ethanol and toluene is used in a volume ratio of 1:1.2-2, with a moisture content of ≤0.5% to avoid moisture affecting the reaction and dielectric properties of the product. Ethanol promotes the dissolution of phenolic monomers, while toluene improves the flowability of the resin during processing and is easily removed by vacuum distillation, leaving no residue.

7. A method for preparing a high-heat-resistant linear phenolic resin based on organosilicon resin composite as described in any one of claims 1-6, characterized in that, Includes the following steps: Pre-dissolution and impurity removal → step-by-step controllable prepolymerization → original flavor grafting compounding → neutralization and precision washing → vacuum post-treatment; The original grafting composite is achieved by adding the composite modified resin to the prepolymer solution in 2-3 parts, and stirring at 90-98℃ and 180-220r / min for 1-1.5h to achieve chemical bonding grafting. Precision washing until the aqueous phase conductivity is ≤50μS / cm, high vacuum distillation at 0.09-0.1MPa and 120-130℃ for 2-3 hours, and precision filtration using a 200-300 mesh polytetrafluoroethylene filter membrane.