Propargyl polysiloxane-modified cyanate ester resin, and preparation method and application thereof

Abstract

The application discloses a propargyl polysiloxane modified cyanate ester resin and a preparation method and application thereof, and comprises the following steps: S1, a propargyl compound shown in formula I and polysiloxane shown in formula II are subjected to a heating reaction in the presence of a platinum catalyst and a solvent to obtain a propargyl polysiloxane; S2, the propargyl polysiloxane is mixed with a cyanate ester monomer, heated and stirred until a transparent solution is obtained, and subjected to a heat curing treatment to obtain the propargyl polysiloxane modified cyanate ester resin. The propargyl polysiloxane modified cyanate ester resin can be cured and formed at a lower curing temperature, and the prepared modified resin has lower dielectric loss, water absorption, higher impact strength and thermal stability, and has a good application prospect in high-end electronic materials.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a propargyl polysiloxane modified cyanate resin and its preparation method and application. Background Technology

[0002] Driven by cutting-edge technologies such as high-frequency communication (5G / 6G), artificial intelligence computing, and new energy vehicles, low-dielectric-loss heat-resistant resins have become a key basic material supporting the development of modern electronics industry. In the field of 5G / 6G communication, signal transmission in the millimeter-wave band is prone to attenuation. Therefore, core components such as base station antennas and filters must use low-loss resins to ensure signal integrity. In artificial intelligence servers, data transmission rates of over 100 Gbps between GPUs and CPUs place stringent requirements on circuit board materials. Traditional resins, due to severe signal attenuation, can no longer meet the requirements and must be replaced by low-dielectric-loss materials to reduce latency. In the field of automotive electronics, vehicle radar systems need to operate stably for extended periods in harsh environments such as high temperatures and vibrations in the engine compartment. This poses a significant challenge to the heat resistance and reliability of resin materials. Therefore, whether pursuing ultimate signal transmission efficiency or ensuring operational reliability under complex conditions, low dielectric loss and heat resistance have become indispensable dual core indicators for high-end electronic materials.

[0003] Cyanate ester resin (CE) is widely regarded as an ideal matrix resin for high-performance electronic materials due to its excellent heat resistance and low dielectric loss. However, cyanate ester resin still faces the following problems in practical applications: (1) The curing temperature of cyanate ester resin is usually high (≥250 ℃), which not only consumes a lot of energy, but also easily generates large thermal stress and volume shrinkage in the composite material, resulting in microcracks or stress concentration in the product, which seriously affects the mechanical properties and long-term reliability of the material; (2) In order to reduce the curing temperature of cyanate ester resin, traditional methods often add organometallic catalysts (such as copper acetylacetonate, zinc octanoate, etc.), but the introduction of these catalysts often increases the polarity of the resin system and significantly degrades the dielectric properties (especially the dielectric loss at high frequencies); (3) Cyanate ester resin itself has high crosslinking density and high brittleness, and insufficient impact resistance, which limits its application in electronic materials that require a certain degree of toughness.

[0004] Therefore, how to reduce the curing temperature of cyanate ester resin and improve its impact resistance while maintaining or even further improving its low dielectric loss, low water absorption and high thermal stability, and avoiding the problem of dielectric performance degradation caused by traditional catalysts, is one of the technical challenges that urgently need to be solved in the field of high-end electronic materials. Summary of the Invention

[0005] Existing cyanate ester resins suffer from problems such as high curing temperatures leading to stress concentration, the degradation of dielectric properties due to the addition of catalysts to lower the curing temperature, and inherent brittleness and insufficient impact resistance. To address these issues, this invention provides a propargyl polysiloxane-modified cyanate ester resin, its preparation method, and its applications. This resin can be cured at lower temperatures, and the resulting modified resin exhibits lower dielectric loss, lower water absorption, and higher impact strength and thermal stability, showing promising application prospects in high-end electronic materials.

[0006] Specifically, the following technical solutions are provided: The first aspect of this invention provides a method for preparing propargyl polysiloxane modified cyanate ester resin, comprising the following steps: S1. The propargyl compound shown in Formula I and the polysiloxane shown in Formula II are heated and reacted in the presence of a platinum catalyst and a solvent to obtain propargyl polysiloxane. The structures of Equations I and II are as follows:

[0007] Where m is any integer in the range of 20-200, more preferably any integer in the range of 50-115, and n is any integer in the range of 10-100, more preferably any integer in the range of 18-40. S2. The propargyl polysiloxane prepared in step S1 is mixed with cyanate monomer, heated and stirred until a transparent solution is obtained, and then subjected to thermosetting treatment to obtain the propargyl polysiloxane modified cyanate resin.

[0008] This invention, based on molecular design and green synthesis principles, first prepares a propargyl compound (Formula I) using natural products and magnolol as raw materials. Then, it is grafted onto the backbone of a polysiloxane (Formula II) via a hydrosilylation reaction to obtain propargyl polysiloxane (PMBS). This PMBS combines the flexible hydrophobic framework of polysiloxane with the high reactivity of propargyl groups. Blending it with CE and thermosetting it can form a chemically grafted interpenetrating or semi-interpenetrating network structure. The propargyl polysiloxane-modified cyanate ester resin prepared by the above method not only cures at lower curing temperatures to form a cyanate ester resin containing propargyl polysiloxane, but also exhibits lower dielectric loss, lower water absorption, and higher impact strength and thermal stability, as detailed below: Low curing temperature: The propargyl group in PMBS undergoes an exothermic self-curing reaction under heating conditions. The heat generated and the active intermediates effectively induce the cyclization trimerization reaction of the cyanate ester, thereby significantly reducing the curing onset and peak temperatures of the system (20-40℃ lower than pure CE), while avoiding the degradation of dielectric properties caused by external metal catalysts. Furthermore, the hydrogen atoms in the silane-hydrogen bonds of PMBS carry a partial negative charge, which can attack carbon atoms with low electron cloud density in the cyanate ester monomer (-OC≡N), forming an active intermediate transition state. This intermediate state more readily attracts another cyanate molecule to participate in the reaction, thus greatly accelerating the trimerization process and lowering the curing temperature of the cyanate ester.

[0009] Low dielectric loss: The Si-O-Si structure of the PMBS main chain has extremely low polarity, and its flexible segments increase the free volume of the modified resin, which limits the orientation polarization ability of the dipole under alternating electric field. Therefore, the prepared modified cyanate resin exhibits lower dielectric constant and dielectric loss.

[0010] Low water absorption: The hydrophobic silica backbone and nonpolar side chain groups of PMBS form micro-hydrophobic regions inside the resin, effectively hindering the diffusion of water molecules along polar channels; at the same time, the introduction of PMBS dilutes the concentration of unreacted hydrophilic groups such as cyanate in the cyanate ester, which significantly reduces the equilibrium water absorption of the modified resin, which is beneficial to the long-term stability of dielectric properties under humid and hot conditions.

[0011] Excellent mechanical properties: The long -Si-O-Si- bonds and large bond angles in the polysiloxane segments result in high rotational freedom of the segments, giving PMBS excellent flexibility and enabling it to act as a "flexible stress buffer unit" in the cured system. Upon impact, the PMBS-enriched phase can induce crazing and shear bands, dissipating a large amount of impact energy, thereby significantly improving the impact strength of the modified resin (more than 50% higher than that of pure CE resin).

[0012] High thermal stability: The high bond energy of the Si-O bond (approximately 452 kJ / mol) endows polysiloxane with intrinsic thermal inertness, delaying the thermal decomposition initiation temperature of the CE matrix; at higher temperatures, PMBS decomposes to generate Si-OC or Si-C ceramic phases, which synergistically form a dense protective carbon layer with the carbonization products of cyanate ester, inhibiting heat and oxygen penetration. Therefore, the thermogravimetric temperature (T0) of the modified resin is relatively low. di Both the 5% (5%) and high-temperature char residue rate are superior to traditional cyanate ester resins.

[0013] Further, in step S1, the preparation method of the propargyl compound represented by Formula I is as follows: magnolol and bromopropylalkyne are reacted in the presence of an organic solvent and anhydrous potassium carbonate. After the reaction is complete, the mixture is naturally cooled to room temperature. After filtration, washing, extraction and rotary evaporation to remove the solvent, the propargyl compound represented by Formula I is obtained.

[0014] In some preferred embodiments, the organic solvent is acetone, and the heating reaction is carried out at a temperature of 50-60°C for 24-48 hours.

[0015] Further, in step S1, the preparation method of the polysiloxane is as follows: Octamethylcyclotetrasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane and 1,1,3,3-tetramethyldisiloxane are reacted in the presence of an acid catalyst. After the reaction is complete, an alkaline reagent is added to adjust the pH to neutral. After extraction and rotary evaporation, the polysiloxane is obtained.

[0016] In some preferred embodiments, the acid catalyst is trifluoromethanesulfonic acid, and the acid catalyst accounts for 0.1 wt%-5 wt% of the total reactants (octamethylcyclotetrasiloxane + 2,4,6,8-tetramethylcyclotetrasiloxane + 1,1,3,3-tetramethyldisiloxane), for example, 0.3 wt%. More preferably, the molar ratio of octamethylcyclotetrasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane to 1,1,3,3-tetramethyldisiloxane is (1.15-1.3):1:(0.16-0.24), for example, 1.2:1:0.2, 1.2:1:0.24, 1.4:1:0.16, etc.

[0017] In this invention, the amount of 1,1,3,3-tetramethyldisiloxane added to the reactants for preparing polysiloxane directly affects the molecular weight and silane-hydrogen bond density of the prepared polysiloxane. If the amount added is too high, for example, if the molar ratio of 2,4,6,8-tetramethylcyclotetrasiloxane to 1,1,3,3-tetramethyldisiloxane is less than 1:0.24, the prepared polysiloxane will have a low molecular weight and low silane-hydrogen bond density, making it difficult to react further with propargyl compounds. However, if the amount added is too low, for example, if the molar ratio of 2,4,6,8-tetramethylcyclotetrasiloxane to 1,1,3,3-tetramethyldisiloxane is greater than 1:0.16, the prepared polysiloxane will have a high molecular weight and increased viscosity, which will reduce the accessibility of the Si-H reaction sites and thus inhibit the hydrosilylation reaction. Preferably, the molar ratio of the reaction raw materials used to prepare polysiloxanes needs to be controlled within a suitable range. For example, the molar ratio of octamethylcyclotetrasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane and 1,1,3,3-tetramethyldisiloxane should be controlled within the range of (1.15-1.3):1:(0.16-0.24) to obtain high yield and effective grafting of propargyl polysiloxane.

[0018] Furthermore, in step S1, m and n in the structure of equation II satisfy: 1 <m / n<5。

[0019] Furthermore, in step S1, the number-average molecular weight of the polysiloxane represented by Formula II is preferably 9500-12000, such as 10000, 11000, etc.

[0020] Furthermore, the propargyl polysiloxane has the following general structural formula:

[0021] Where m is any integer in the range of 20-200, n is any integer in the range of 10-100, and x is any value in the range of 0.2-0.4, such as 0.25, 0.3, 0.35, etc.

[0022] Furthermore, the molar ratio of the propargyl compound represented by Formula I to the polysiloxane represented by Formula II is preferably 1:(10-20), for example 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:20, etc., including but not limited to the molar ratios listed above.

[0023] Further, the platinum catalyst may be selected from one or more of Karstedt catalyst, Speier catalyst, and chloroplatinic acid; more preferably, the concentration of the platinum catalyst is 5-100 ppm (as a percentage of the total reactants, which are propargyl compounds represented by Formula I + polysiloxanes represented by Formula II).

[0024] Furthermore, the solvent may be selected from one or more of toluene, tetrahydrofuran, and n-hexane.

[0025] Furthermore, the heating reaction temperature is preferably 100-110 °C, and the time is preferably 22-26 h, for example 24 h.

[0026] Further, in step S2, the preferred mass ratio of the propargyl polysiloxane to the cyanate monomer is (1-50):100, such as 10:100, 20:100, 30:100, 40:100, etc., including but not limited to the mass ratios listed above. In this invention, the amount of propargyl polysiloxane added should not be excessive; excessive flexible segments will lead to a decrease in the density of the resin crosslinking network, which will instead impair the heat resistance of the material.

[0027] Further, in step S2, the cyanate monomer includes one or more of bisphenol A cyanate (CAS#: 1156-51-0), bisphenol E cyanate (CAS#: 47073-92-7), bisphenol F cyanate (CAS#: 101657-77-6), bisphenol M cyanate (CAS#: 127667-44-1), and phenolic cyanate (CAS#: 30944-92-4).

[0028] Furthermore, in step S2, the heating temperature is preferably 50-120 °C.

[0029] Further, in step S2, the temperature of the thermosetting treatment is preferably 120-240 ℃, and the time is preferably 16-20 h; more preferably, the thermosetting treatment is a stepped heating method, the holding time at each step temperature is not less than 1 h, and the temperature difference between adjacent steps does not exceed 30 ℃, for example, self-curing is carried out according to 120 ℃ / 1 h + 150 ℃ / 2 h + 180 ℃ / 2 h + 200 ℃ / 2 h + 220 ℃ / 2 h.

[0030] A second aspect of the present invention provides a propargyl polysiloxane modified cyanate resin, which is prepared by the preparation method described in the first aspect.

[0031] Furthermore, the initial thermal decomposition temperature (T0) of the propargyl polysiloxane modified cyanate resin is... di Temperature not lower than 430 °C (5% thermal weight loss), dielectric loss less than 0.005 × 10⁻⁶. 5 Hz, impact strength not less than 8.20 kJ / m 2 .

[0032] The third aspect of this invention provides the application of the propargyl polysiloxane modified cyanate resin described in the second aspect in base station antennas, filters, circuit board materials, or vehicle radar systems.

[0033] The beneficial effects of this invention are: 1. The propargyl polysiloxane modified cyanate resin prepared by this invention uses natural products and magnolol as raw materials, which reduces the dependence on non-renewable fossil resources and conforms to the greening and sustainable development strategy of materials.

[0034] 2. The propargyl polysiloxane disclosed in this invention has low viscosity and self-curing exothermic reaction, which can induce the curing reaction of cyanate ester. Furthermore, the hydrogen atoms in the silicon-hydrogen bonds of the propargyl polysiloxane carry a partial negative charge, which can attack the carbon atoms (-OC≡N) in the cyanate ester monomer with low electron cloud density, forming an active intermediate transition state. This intermediate state more easily attracts another cyanate ester molecule to participate in the reaction, thereby greatly accelerating the trimerization process and reducing the curing temperature of the cyanate ester. These effects result in a curing temperature of the prepared propargyl polysiloxane-modified cyanate ester resin lower than that of traditional commercial cyanate ester resins, overcoming the problems of stress concentration and high energy consumption caused by high-temperature curing.

[0035] 3. The propargyl polysiloxane modified cyanate ester resin prepared by the present invention has lower dielectric loss. This is because the modifier PMBS has a much lower polarity than cyanate ester, and the flexible segments increase the free volume of the modified resin system, reducing the orientation polarization capability of the dipole, thereby obtaining lower dielectric loss and meeting the signal integrity requirements of high-frequency communication and other fields.

[0036] 4. The propargyl polysiloxane-modified cyanate ester resin prepared in this invention has a lower water absorption rate, which is beneficial for maintaining stable electrical properties under humid and hot environments. This is because the main chain of PMBS is an inorganic silicon-oxygen skeleton, and the side chains are usually alkyl or aryl, which have extremely strong hydrophobicity. These form hydrophobic microdomains in the modified cyanate ester resin, hindering the penetration of water molecules. At the same time, the presence of propargyl polysiloxane dilutes the interaction between hydrophilic groups and water molecules in the cyanate ester resin, reducing the exposure of polar groups.

[0037] 5. The propargyl polysiloxane modified cyanate resin prepared by the present invention has higher impact strength. This is because the propargyl polysiloxane main chain has a large bond angle, high rotational freedom, and excellent chain segment flexibility. As a flexible internal toughening agent, it can absorb energy, induce crazes or shear bands when subjected to impact, prevent crack propagation, and moderately reduce the crosslinking density, thereby significantly improving the impact toughness of the modified resin.

[0038] 6. The propargyl polysiloxane-modified cyanate ester resin prepared in this invention exhibits higher thermal stability. This is because the bond energy of the -Si-O- backbone of the polysiloxane is as high as approximately 452 kJ / mol, far exceeding that of CC (347 kJ / mol) or CO (358 kJ / mol), resulting in excellent thermal stability. Therefore, the presence of polysiloxane can delay the thermal decomposition process of CE. Furthermore, the polysiloxane decomposes at high temperatures to generate Si-OC or Si-C ceramic phases, which synergistically form a dense carbon layer with the decomposition products of the cyanate ester resin, preventing heat and oxygen penetration and improving the char yield.

[0039] In summary, this invention, through the unique structural design of propargyl polysiloxane, enables the modified cyanate resin to simultaneously achieve multiple performance improvements, including low-temperature curing, low dielectric loss, low water absorption, high impact strength, and high thermal stability, thus showing broad application prospects in cutting-edge fields such as 5G / 6G communication, artificial intelligence servers, and automotive electronics. Attached Figure Description

[0040] Figure 1 This is a reaction flow diagram of the propargyl polysiloxane prepared in Example 1 of the present invention; Figure 2 The nuclear magnetic resonance hydrogen spectrum of the polysiloxane prepared in Example 1 of this invention ( 1 H-NMR spectrum; Figure 3 This is the Fourier transform infrared (FTIR) spectrum of the propargyl polysiloxane prepared in Example 1 of this invention; Figure 4 It is the propargyl polysiloxane prepared in Example 1 of this invention. 1 H-NMR spectrum; Figure 5 The carbon NMR spectrum of the propargyl polysiloxane prepared in Example 1 of this invention ( 1 C-NMR spectrum; Figure 6 This is a size exclusion chromatogram (GPC) of the propargyl polysiloxane prepared in Example 1 of the present invention. Figure 7 The differential scanning calorimetry (DSC) curves of propargyl polysiloxane modified cyanate resin, CE, PMBS and PMHS prepared in Example 1 of this invention are shown. The test conditions are nitrogen atmosphere and heating rate is 10 °C / min. Figure 8 This is an experimental diagram of the cured polysiloxane-modified cyanate ester resin prepolymer CE / PMHS prepared in Comparative Example 3 of this invention. Figure 9 The loss factor-temperature curve of the cured propargyl polysiloxane modified cyanate resin 200-CE / PMBS prepared in Example 1 of this invention is shown, with a heating rate of 3 ℃ / min. Figure 10 This is the loss factor-temperature curve of the cured cyanate ester resin 200-CE prepared in Comparative Example 1 of the present invention, with a heating rate of 3 °C / min. Figure 11 The loss factor-temperature curve of the cured propargyl polysiloxane modified cyanate resin 220-CE / PMBS prepared in Example 2 of this invention is shown, with a heating rate of 3 ℃ / min. Figure 12 This is the loss factor-temperature curve of the cured cyanate resin 220-CE prepared in Comparative Example 1 of the present invention, with a heating rate of 3 °C / min. Figure 13 The loss factor-temperature curve of the cured propargyl polysiloxane modified cyanate resin 240-CE / PMBS prepared in Example 3 of this invention is shown, with a heating rate of 3 °C / min. Figure 14 This is the loss factor-temperature curve of the cured cyanate resin 240-CE prepared in Comparative Example 1 of the present invention, with a heating rate of 3 °C / min. Figure 15 The loss factor-temperature curves of the cured propargyl polysiloxane modified cyanate resin 260-CE / PMBS prepared in Example 4 of this invention and the cured cyanate resin 260-CE prepared in Comparative Example 1 are shown, with a heating rate of 3 °C / min. Figure 16 The loss factor-temperature curve of the cured propargyl polysiloxane modified cyanate resin CE / PMBSm prepared in Comparative Example 2 of this invention is shown, with a heating rate of 3 ℃ / min. Figure 17These are the thermogravimetric analysis (TGA) curves of the propargyl polysiloxane modified cyanate resin prepared in Examples 1-4 of this invention and the cured cyanate resin prepared in Comparative Example 1 under a nitrogen atmosphere. The test conditions were a nitrogen atmosphere and a heating rate of 10℃ / min. Figure 18 The heat release rate (HRR)-temperature curves of the propargyl polysiloxane modified cyanate resin 220-CE / PMBS prepared in Example 2 of the present invention and the cyanate ester 220-CE prepared in Comparative Example 1 in the micro calorimetry (MCC) test at 100-750 °C are shown. Figure 19 The total heat release-temperature curves of the propargyl polysiloxane modified cyanate resin 220-CE / PMBS prepared in Example 2 of this invention and the cyanate ester 220-CE prepared in Comparative Example 1 in the micro calorimetry (MCC) test at 100-750 °C are shown. Detailed Implementation

[0041] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The terms “comprising” or “including” used in this invention may also be replaced with the closed form “is” or “consisting of”.

[0043] All raw materials used in the following examples are commercially available, and the specific preparation operations and testing methods involved are conventional methods in the art. Specifically: The 600 cm⁻¹ infrared spectrometer (Bruker Vertex 70, Germany) was used to measure the infrared spectrometer. -1 Up to 4000 cm -1 Fourier transform infrared (FTIR) spectra of the region.

[0044] Tested using a nuclear magnetic resonance spectrometer (Bruker 400-600 MHz, Germany). 1 H NMR and 13 C10 NMR, solvent: CDCl3.

[0045] The molecular weight of the polymer was determined using a TOSOH HLC-8320 size exclusion chromatograph (GPC) equipped with a differential analyzer and a UV detector.

[0046] Differential scanning calorimetry (DSC) curves in the range of 25 °C–300 °C under nitrogen atmosphere were tested using a TA Instrument (Q200, USA) at a heating rate of 10 °C / min.

[0047] Thermogravimetric analysis (TGA) curves were measured using a thermogravimetric analyzer (TA Instrument (Discovery), USA) under a nitrogen atmosphere from 25 °C to 800 °C. The heating rate was 10 °C / min, and the temperature at which 5% weight loss occurred was T. di .

[0048] Dynamic mechanical analysis (DMA) was performed using a dynamic mechanical analyzer (TA DMA Q800, USA) at a rate of 3 ℃ / min in the range of 25 ℃-350 ℃. The size of each sample was (30±0.5) mm × (5±0.2) mm × (1±0.1) mm.

[0049] The dielectric constant and dielectric loss were measured using a broadband dielectric spectrometer and impedance spectrometer (Novocontrol Concept 80). The sample consisted of a 10 mm diameter, 1 mm thick cured resin disc, and the testing frequency was 10 Hz ~ 10 Hz. 5 Hz.

[0050] Impact strength was measured using a Charpy impact testing machine XCJD-5 (Chengde Jinhe Instrument Manufacturing Co., Ltd., China) according to national standard GB / T 2567-2008. The sample dimensions were (80±0.1) mm × (10±0.1) mm × (3.5±0.02) mm, with a span of 58.5 mm. Microcalorimetry (MCC) tests were conducted using a DEATAK MCC-3 (USA) in a mixed atmosphere (79% nitrogen + 21% oxygen) at a heating rate of 1 ℃ / s within the range of 100-750 ℃.

[0051] The water absorption test was conducted using a hot water immersion experiment. The mass of a 60 mm × 60 mm × 10 mm sample after drying at 80 ℃ for 4 h was recorded as m0. The sample was then immersed in deionized water at 55~60 ℃ for 30 h. After the immersion, the sample was removed and the surface water was wiped off, and the mass of the sample was recorded as m. The water absorption rate was calculated as (m0-m) / m0×100%.

[0052] Example 1: This example relates to the preparation of a propargyl polysiloxane modified cyanate ester resin, such as... Figure 1 As shown, the specific operation is as follows: (1) Preparation of propargyl polysiloxane Preparation of polysiloxane PMHS: Under a nitrogen atmosphere, octamethylcyclotetrasiloxane (17.61 g, 0.059 mol), 2,4,6,8-tetramethylcyclotetrasiloxane (11.58 g, 0.048 mol), 1,1,3,3-tetramethyldisiloxane (1.22 g, 0.009 mol), and trifluoromethanesulfonic acid (0.3 wt% of total reactants) were added to a three-necked flask. The mixture was stirred at 25–30 °C for 24 h to obtain a crude polysiloxane product. Sodium bicarbonate was added to the reaction flask to adjust the pH of the solution to approximately 7. The solution was filtered and then rotary evaporated at 80 °C for 1 h to obtain 21.46 g of polysiloxane (denoted as PMHS-1), with a yield of 91%. GPC analysis of the product showed the following results: number average molecular weight 10124, molecular weight distribution 1.589. PMHS... 1 H NMR spectrum as follows Figure 2 As shown.

[0053] In the proton nuclear magnetic resonance spectrum ( 1 In ¹H NMR, the area ratio R (R = A_Si-H / A_CH3) is calculated by integrating the characteristic peak of silane-hydrogen bonds (δ ~4.7 ppm) and the silanyl internal standard peak (δ ~0.1 ppm). The number-average molecular weight (Mn_GPC) measured by GPC is relative to the polystyrene (PS) standard. For polysiloxanes, their absolute molecular weight (Mn_abs) needs to be corrected using the Mark-Hovink equation: Mn_abs = Mn_GPC × K; where K is the correction factor, and for polydimethylsiloxane (PDMS) in THF solvent, the K value is typically between 0.5 and 0.6.

[0054] For hydrogen-containing polysiloxanes (PMHS), their molecular weight and the integral ratio (R) of their 1H NMR spectrum are determined by the following relationships with the structural parameters m and n: Equation 1 (molecular weight equation): K × Mn_GPC≈74.1 × m + 60.1 × n + M_end.

[0055] Where M_end is the end-group mass, and for a structure with -Si(CH3)2H at both ends, M_end≈180. To simplify the derivation, it can be considered a constant.

[0056] Equation 2 (NMR integral ratio equation): R = A_Si-H / A_CH3 = (n + 1) / (3n + 6m + 6).

[0057] This formula reflects the ratio of the total number of Si-H protons to the total number of Si-CH3 protons.

[0058] Based on the above characterization results and equations 1 and 2, the m, n and m / n values ​​of PMHS are calculated: m is 50-80, n is 18-28, and m / n is 1.78-4.45.

[0059] Preparation of propargyl compound DBB: Under a nitrogen atmosphere, magnolol (14.4 g, 0.054 mol) and anhydrous potassium carbonate (18.12 g, 0.131 mol) were dissolved in 150 mL of acetone and stirred at 25–30 °C for 30 min. 3-bromopropylalkyne (18.56 g, 0.156 mol) was added dropwise, and the reaction was carried out at 55–60 °C for 48 h. After the reaction was completed, the mixture was allowed to cool naturally to room temperature and filtered to obtain the crude propargyl compound. The crude propargyl compound was dissolved in 100 mL of ethyl acetate and washed with 100 mL of deionized water. After extraction, the ethyl acetate was removed by rotary evaporation (50 °C, 0.08 MPa) to obtain 13.57 g of propargyl compound (denoted as DBB), with a yield of 95.1%. High-resolution mass spectrometry analysis was performed on the product, and the mass-to-charge ratio was [C]. 24 H 22 O2H] + : 343.17.

[0060] Preparation of propargyl polysiloxane PMBS: DBB (4.12 g, 0.012 mol) was dissolved in 20 mL of toluene, and 5 ppm (percentage of total reactants) of Karstedt catalyst was added. The reaction was carried out at 25–30 °C for 1 h to obtain a toluene solution containing propargyl compounds. PMHS (10.23 g, 0.15 mol) prepared in step (1) was dissolved in 20 mL of toluene, and the above-mentioned toluene solution containing propargyl compounds was added dropwise. The reaction was carried out at 100–105 °C for 24 h. Toluene was then removed by rotary evaporation (60 °C, 0.08 MPa), followed by washing with 20 mL of n-hexane, and then rotary evaporation was carried out again (50 °C, 0.08 MPa) to obtain 12.41 g of propargyl polysiloxane (denoted as PMBS), with a yield of 84.6%.

[0061] The product was characterized by infrared spectroscopy, nuclear magnetic resonance, GPC, and DSC. The characterization results are as follows: Figure 3 The FTIR spectrum of PMBS prepared in this embodiment shows the absorption peak of the stretching vibration of ≡CH (3300 cm⁻¹). -1 ), characteristic absorption peak of Si-H (2160 cm⁻¹) -1 ) and the typical absorption peak of C=C (1637 cm⁻¹) -1 This indicates that the propargyl compound was successfully grafted onto PMHS and that unreacted silane-hydrogen bonds exist.

[0062] Figure 4 The PMBS prepared in this embodiment 1 1H NMR spectroscopy. Using proton nuclear magnetic resonance spectroscopy (NMR spectroscopy). 1 The grafting rate x of propargyl compound (DBB) in self-curing propargyl polysiloxane monomer (PMBS) was quantitatively determined by ¹H NMR. The proton signal peak of the methyl group (-Si-CH3) directly bonded to silicon atoms in the polysiloxane backbone was selected as the internal standard reference peak. This peak had a stable chemical shift (δ ≈ 0.1 ppm), and its total proton count remained unchanged before and after the grafting reaction; the integrated area was denoted as A_ref. The characteristic proton signal peak of the silicon-hydrogen bond (Si-H) was selected as the monitoring peak. This peak had a chemical shift around δ ~ 4.7 ppm, and its integrated area was denoted as A_Si-H. The area of ​​this peak is proportional to the number of unreacted Si-H bonds in the system. ¹H NMR measurements and integral calculations showed that the A_ref of PMHS was 1.00, and that of PMBS- was also 1.00; the A_Si-H of PMHS was 0.58, and that of PMBS was 0.39. The grafting rate was calculated as x = 1 - (0.39 / 0.58) ≈ 0.328. This result indicates that approximately 32.8% of the Si-H bonds underwent hydrosilylation with the propargyl compound (DBB), successfully grafting onto the polysiloxane backbone.

[0063] Figure 5 The PMBS prepared in this embodiment 13 C NMR spectrum.

[0064] Figure 6 The GPC spectrum of the PMBS prepared in this embodiment shows the following results: number-average molecular weight is 12803, and molecular weight distribution is 2.031.

[0065] (2) Preparation of propargyl polysiloxane modified cyanate resin (200-CE / PMBS) Bisphenol A cyanate (10.0 g, 0.036 mol) was heated to melt at 80 °C, and then propargyl polysiloxane (1.12 g, 0.0875 mmol) synthesized in step (1) was added dropwise. After the addition was complete, the mixture was prepolymerized at 120 °C for 30 min to obtain the prepolymer (CE / PMBS).

[0066] The prepolymer CE / PMBS was poured into a mold and cured according to the following process: 120 ℃ / 1 h + 150 ℃ / 2 h + 180 ℃ / 2 h + 200 ℃ / 2 h. After curing, it was allowed to cool naturally to obtain the propargyl polysiloxane modified cyanate resin, denoted as 200-CE / PMBS.

[0067] Figure 7 The figure shows the DSC curves of bisphenol A cyanate, prepolymer CE / PMBS, PMBS, and PMHS. As can be seen from the figure, PMHS has no obvious curing exothermic peak. PMBS starts to react at a lower temperature (e.g., 150~200 ℃), where the most active part of the system, the alkynyl group, begins to react. Then, a large-scale and intense curing reaction occurs at a higher temperature (200~250 ℃). CE shows a curing peak at 255~350 ℃, while the curing peak of CE / PMBS is at 225~325 ℃. This indicates that the low viscosity and self-curing properties of PMBS, as well as the synergistic effect of hydrogen attacking the carbon atoms of cyanate in the silane-hydrogen bond to form an active intermediate transition state, can induce cyanate to cure at a lower temperature. This overcomes the disadvantage of high curing temperature of traditional cyanate resins and significantly improves its processability.

[0068] Example 2: This example relates to the preparation of a propargyl polysiloxane modified cyanate ester resin (220-CE / PMBS). The only difference from Example 1 is the curing procedure, which is as follows: curing is performed at 120 ℃ / 1 h + 150 ℃ / 2 h + 180 ℃ / 2 h + 200 ℃ / 2 h + 220 ℃ / 2 h. All other operations are the same, and the corresponding propargyl polysiloxane modified cyanate ester resin (220-CE / PMBS) is obtained.

[0069] Example 3: This example relates to the preparation of a propargyl polysiloxane modified cyanate ester resin (240-CE / PMBS). The only difference from Example 1 is the curing procedure, which is as follows: curing is performed at 120 ℃ / 1 h + 150 ℃ / 2 h + 180 ℃ / 2 h + 200 ℃ / 2 h + 220 ℃ / 2 h + 240 ℃ / 2 h. All other operations are the same, and the corresponding propargyl polysiloxane modified cyanate ester resin (240-CE / PMBS) is obtained.

[0070] Example 4: This example relates to the preparation of a propargyl polysiloxane modified cyanate ester resin (260-CE / PMBS). The only difference from Example 1 is the curing procedure, which is as follows: curing is performed according to the process of 120 ℃ / 1 h + 150 ℃ / 2 h + 180 ℃ / 2 h + 200 ℃ / 2 h + 220 ℃ / 2 h + 240 ℃ / 2 h + 260 ℃ / 2 h. All other operations are the same, and the corresponding propargyl polysiloxane modified cyanate ester resin (260-CE / PMBS) is prepared.

[0071] Comparative Example 1: This comparative example relates to the preparation of a cyanate ester resin (200-CE, 220-CE, 240-CE, 260-CE), as detailed below: Preparation of 200-CE: Bisphenol A cyanate (10.0 g, 0.036 mol) was heated to molten at 80 °C and reacted at 80 °C for 30 min until the solution became clear. The solution was then poured into a mold and cured according to the process of 120 °C / 1 h + 150 °C / 2 h + 180 °C / 2 h + 200 °C / 2 h. After curing, the solution was allowed to cool naturally to obtain the cured pure cyanate, which was designated as 200-CE.

[0072] Preparation of 220-CE: Bisphenol A cyanate (10.0 g, 0.036 mol) was heated to molten at 80 °C and reacted at 80 °C for 30 min until the solution became clear. The solution was then poured into a mold and cured according to the process of 120 °C / 1 h + 150 °C / 2 h + 180 °C / 2 h + 200 °C / 2 h + 220 °C / 2 h. After curing, the solution was allowed to cool naturally to obtain the cured pure cyanate, which was designated as 220-CE.

[0073] Preparation of 240-CE: Bisphenol A cyanate (10.0 g, 0.036 mol) was heated to 80 °C until melted, and reacted at 80 °C for 30 min until the solution became clear. The solution was then poured into a mold and cured according to the following process: 120 °C / 1 h + 150 °C / 2 h + 180 °C / 2 h + 200 °C / 2 h + 220 °C / 2 h + 240 °C / 2 h. After curing, the product was allowed to cool naturally to obtain the cured pure cyanate, which was designated as 240-CE.

[0074] Preparation of 260-CE: Bisphenol A cyanate (10.0 g, 0.036 mol) was heated to 80 °C until melted, and reacted at 80 °C for 30 min until the solution became clear. The solution was then poured into a mold and cured according to the following process: 120 °C / 1 h + 150 °C / 2 h + 180 °C / 2 h + 200 °C / 2 h + 220 °C / 2 h + 240 °C / 2 h + 260 °C / 2 h. After curing, the product was allowed to cool naturally to obtain the cured pure cyanate, which was designated as 260-CE.

[0075] Comparative Example 2: This comparative example relates to the preparation of a propargyl polysiloxane modified cyanate resin (CE / PMBSm). The only difference from Example 2 is the amount of PMBS added. Specifically, bisphenol A cyanate (10.0 g, 0.036 mol) was heated to melt at 80 °C, and then propargyl polysiloxane (6.32 g, 0.4936 mmol) synthesized in step (1) was added dropwise. All other operations were the same, and the corresponding propargyl polysiloxane modified cyanate resin, denoted as CE / PMBSm, was prepared.

[0076] Comparative Example 3: This comparative example relates to the preparation of a polysiloxane-modified cyanate ester resin (220-CE / PMHS), as detailed below: Bisphenol A cyanate (10.0 g, 0.036 mol) was heated to molten at 80 °C, and then the polysiloxane (1.12 g, 0.1106 mmol) synthesized in step (1) was added dropwise. After the addition was complete, the mixture was prepolymerized at 120 °C for 30 min to obtain the prepolymer (CE / PMHS), as shown below. Figure 8 As shown, the system failed to form a homogeneous and transparent solution, instead exhibiting a clear stratification phenomenon: the upper layer was a milky white or translucent PMHS-enriched phase, and the lower layer was a pale yellow, clear CE-enriched phase. The interface between the two phases was clear, with no signs of emulsification or dissolution. This stratification phenomenon indicates that, without the introduction of chemically active groups (such as propargyl groups), PMHS and CE resin are thermodynamically incompatible.

[0077] The prepolymer CE / PMHS was poured into a mold and cured according to the following process: 120 ℃ / 1 h + 150 ℃ / 2 h + 180 ℃ / 2 h + 200 ℃ / 2 h + 220 ℃ / 2 h. After curing, it was allowed to cool naturally, resulting in a propargyl polysiloxane modified cyanate resin, denoted as 220-CE / PMHS. The upper layer was liquid PMHS, and the lower layer was the cured CE resin. This phenomenon is consistent with the DSC test results of PMHS. Since PMHS has no obvious exothermic peak during curing and remains liquid after cooling, it can be concluded that PMHS cannot be directly used to modify CE resin.

[0078] Performance testing: (1) T of the modified or unmodified cyanate ester resins prepared in the above examples and comparative examples. g T di The test results for dielectric loss, impact strength, and water absorption rate are shown in the table below:

[0079] Figure 9The loss factor-temperature curve for 200-CE / PMBS shows a single peak and a superimposed broad peak. After peak splitting, three symmetrical peaks are obtained, with peak temperatures of 217 ℃, 289 ℃, and 321 ℃, respectively. Similar peak shapes also appear... Figure 10 The loss factor-temperature curve of 200-CE, as shown, yields three symmetrical peaks after peak splitting, with peak temperatures at 214 ℃, 288 ℃, and 314 ℃, respectively. A comparison reveals that the T values ​​of 200-CE / PMBS and 200-CE... g Similarly, it can be concluded that the presence of PBMS has almost no effect on the T of cyanate ester resins. g Similarly, compare the loss factor-temperature curves of 220-CE / PMBS ( Figure 11 The loss factor-temperature curve of 220-CE () and 220-CE Figure 12 Loss factor-temperature curve of 240-CE / PMBS ( Figure 13 The loss factor-temperature curve of 240-CE () Figure 14 It can be seen that the T of 220-CE / PMBS and 220-CE are... g Similar to 240-CE / PMBS, the T of 240-CE g The results were similar, unaffected by the modifier PMBS. However, as the curing temperature increased, the peak position of the loss factor-temperature curve appeared in the high-temperature direction, and at the highest curing temperature of 260 ℃, the peak of the loss factor-temperature curve was a narrow symmetrical peak (the peak temperature is T). g ),like Figure 15 As shown, the T of 260-CE / PMBS g The value is significantly higher than 260-CE, indicating that the presence of PMBS is beneficial for obtaining resins with higher heat resistance. This is because the high bond energy of the polysiloxane backbone (the bond energy of the Si-O bond is as high as about 452 kJ / mol) and the rigid biphenyl structure of PMBS can effectively improve the heat resistance of the resin.

[0080] It is worth noting that the amount of propargyl polysiloxane (PMBS) added has a significant impact on the thermal properties of the modified resin. The loss factor-temperature curve of CE / PMBSm prepared by adding a high content of propargyl polysiloxane in Comparative Example 2 is shown below. Figure 16 As shown, after peak splitting, two symmetrical peaks were obtained, with peak temperatures of 249 ℃ and 289 ℃, respectively, which are lower than those of 220-CE / PMBS (T) at the same curing temperature. g (for 272 ℃ and 315 ℃) and pure resin 220-CE (T g(The values ​​are 270 ℃ and 310 ℃). Therefore, excessive PMBS, due to its flexible segments, will cause a decrease in the density of the resin crosslinking network, thus impairing the material's heat resistance.

[0081] Figure 17 The TGA curves for 200-CE / PMBS, 220-CE / PMBS, 240-CE / PMBS, 260-CE / PMBS, and 200-CE, 220-CE, 240-CE, and 260-CE are shown in the figure and table above. It can be seen from the figure and table that, under the same curing temperature, the initial thermal decomposition temperature (temperature at which 5 wt% weight loss is achieved) of the PBMS-modified cyanate ester resin is... di The curing temperature of pure cyanate resin is significantly higher than that of pure cyanate resin. Furthermore, even increasing the curing temperature of pure cyanate resin does not effectively increase the Tg of pure cyanate resin. di The T of PBMS-modified cyanate ester resin di Under curing conditions of 200℃, the T of 200-CE / PMBS di The temperature reached 436 °C, which is not only about 30 °C higher than that of 200-CE, but also significantly higher than that of biomass-modified cyanate ester resins (T...). di <400 ℃). Therefore, the introduction of PBMS can effectively improve the thermal stability of cyanate ester resins.

[0082] Furthermore, as shown in the table above, this invention effectively improves the dielectric properties, impact strength, and water absorption of cyanate ester resins by introducing PBMS to synergistically control the curing temperature. In particular, when the maximum curing temperature is 200 °C or 220 °C, the modified resin exhibits improved performance at 10 °C. 5 The dielectric loss at Hz is as low as 0.00480 (200 ℃) and 0.00442 (220 ℃), compared to 0.00712 for unmodified pure resin (0.00639 for 200-CE and 0.00442 for 220-CE). 5 The impact strength decreased by approximately 32.6% (Hz), which is attributed to the low-polarity polysiloxane segments in PMBS effectively reducing the overall polarity and dipole loss of the resin system. Simultaneously, its rigid aromatic ring structure is well-compatible with the cyanate ester network, reducing relaxation loss and thus lowering dielectric loss. Furthermore, at the highest curing temperature of 220 °C, the impact strength increased by as much as 44.1%, and the water absorption decreased by 24.1%. This is mainly due to the introduction of flexible polysiloxane segments and low-hydrophobic propargyl polysiloxane segments into the PMBS molecular backbone, which significantly improves the resin's toughness and reduces its water absorption, thereby enhancing its impact resistance and moisture resistance.

[0083] (2) Taking samples 220-CE / PMBS and 220-CE as examples, the effect of PMBS addition on the flame retardant properties of the resin was studied by micro calorimetry. The results are as follows: Test results are as follows Figure 18 As shown, both 220-CE / PMBS and 220-CE resins exhibit heat release peaks at 450-550 ℃. The peak heat release rate for 220-CE is 305.5 W / g, while the peak heat release rate for 220-CE / PMBS decreases to 283.7 W / g. This decrease in peak value indicates a significant reduction in heat release per unit time and per unit mass during combustion, effectively suppressing the intensity of combustion. The total heat release (THR) versus temperature curve (…) Figure 19 As can be seen, before approximately 400 °C, the cumulative heat release of the THR of both resins is close to zero, indicating that there is no significant heat release in the low-temperature range. In the range of 400-600 °C, the THR curve increases with increasing temperature, but the final total heat release of 220-CE / PMBS (12.4 kJ / g) is lower than that of 220-CE resin (13.6 kJ / g), indicating that 220-CE / PMBS releases less total heat per unit mass and has better flame retardancy throughout the combustion process. This is mainly because the organosilicon backbone of PMBS can form a Si-containing composite carbon layer during combustion. This carbon layer has high strength and thermal stability, which can effectively block oxygen and heat transfer, inhibit the continued spread of combustion, and thus improve flame retardancy.

[0084] In summary, this invention successfully prepared a propargyl polysiloxane-modified cyanate ester resin using propargyl polysiloxane as a modifier. Compared with pure cyanate ester resin, the modified resin prepared by this invention can achieve lower dielectric loss, lower water absorption, higher impact strength, and higher thermal stability at lower curing temperatures, showing broad application prospects in cutting-edge fields.

[0085] The above-described embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A method for preparing a propargyl polysiloxane modified cyanate ester resin, characterized in that, Includes the following steps: S1. The propargyl compound shown in Formula I and the polysiloxane shown in Formula II are heated and reacted in the presence of a platinum catalyst and a solvent to obtain propargyl polysiloxane. The structures of Equations I and II are as follows: ， Where m is any integer in the range of 20-200, and n is any integer in the range of 10-100; S2. The propargyl polysiloxane prepared in step S1 is mixed with cyanate monomer, heated and stirred until a transparent solution is obtained, and then subjected to thermosetting treatment to obtain the propargyl polysiloxane modified cyanate resin.

2. The preparation method according to claim 1, characterized in that, In step S1, the preparation method of the polysiloxane is as follows: Octamethylcyclotetrasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane and 1,1,3,3-tetramethyldisiloxane are reacted in the presence of an acid catalyst. After the reaction is complete, an alkaline reagent is added to adjust the pH to neutral. After extraction and rotary evaporation, the polysiloxane is obtained. The molar ratio of octamethylcyclotetrasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane and 1,1,3,3-tetramethyldisiloxane is (1.15-1.3):1:(0.16-0.24).

3. The preparation method according to claim 1 or 2, characterized in that, In the structure of Equation II, m and n satisfy: 1 <m / n<5; And / or, the number-average molecular weight of the polysiloxane is 9500-12000; And / or, the propargyl polysiloxane has the following general structural formula: ， Where m is any integer in the range of 20-200, n is any integer in the range of 10-100, and x is any value in the range of 0.2-0.

4.

4. The preparation method according to claim 1, characterized in that, In step S1, the molar ratio of the propargyl compound represented by Formula I to the polysiloxane represented by Formula II is 1:(10-20). And / or, the platinum catalyst is selected from one or more of Karstedt catalysts, Speier catalysts, and chloroplatinic acid; And / or, the solvent is selected from one or more of toluene, tetrahydrofuran, and n-hexane; And / or, the heating reaction is carried out at a temperature of 100-110 °C for a time of 22-26 h.

5. The preparation method according to claim 1, characterized in that, In step S2, the mass ratio of the propargyl polysiloxane to the cyanate monomer is (1-50):

100.

6. The preparation method according to claim 1, characterized in that, In step S2, the cyanate monomer includes one or more of bisphenol A cyanate, bisphenol E cyanate, bisphenol F cyanate, bisphenol M cyanate, and phenolic cyanate.

7. The preparation method according to claim 1, characterized in that, In step S2, the heating temperature is 50-120℃.

8. The preparation method according to claim 1, characterized in that, In step S2, the temperature of the thermosetting treatment is 120-240 ℃, and the time is 16-20 h.

9. A propargyl polysiloxane-modified cyanate ester resin, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.

10. The application of the propargyl polysiloxane modified cyanate resin as described in claim 9 in base station antennas, filters, circuit board materials, or vehicle radar systems.

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