Initiator-free cross-linked polyphenyl ether composite material as well as preparation method and application thereof

Abstract

The invention discloses an initiator-free cross-linked polyphenyl ether composite material as well as a preparation method and application thereof, and relates to the technical field of composite materials. The composite material is prepared from the following raw materials in parts by weight: 10 to 65 parts of polyphenyl ether resin, 35 to 90 parts of benzocyclobutene resin and 0 to 10 parts of functional filler. The initiator-free cross-linked polyphenyl ether composite material is formed by cross-linking and compounding two low-dielectric resins, and the principle that a BCB group can be subjected to ring opening under a high-temperature condition to form conjugated double bonds and can be subjected to a Diels-Alder (D-A) reaction with an olefin group to realize cross-linking and curing is utilized, so that an initiator and an accelerant are not required to be added during cross-linking, and the cross-linked polyphenyl ether composite material is prepared. Therefore, the composite material obtained by crosslinking not only has the advantages of low dielectric loss and low hygroscopicity, but also has more crosslinking points, higher crosslinking degree and better high temperature resistance, and is beneficial to large-scale application of the composite material in copper-clad plate materials.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, mainly to the field of polyphenylene ether composite material technology, and specifically to an initiator-free crosslinked polyphenylene ether composite material, its preparation method, and its application. Background Technology

[0002] With the rapid development of high-frequency high-speed communication technology (5G / 6G) and millimeter-wave technology, more stringent performance requirements have been placed on the copper-clad laminate materials used: low dielectric constant (Dk≤2.8), low dielectric loss (Df≤0.005), low moisture absorption (≤0.2%), and high temperature resistance (heat distortion temperature≥280℃). These are the core prerequisites for achieving low signal attenuation, high transmission rate, and long-term equipment stability.

[0003] Polyphenylene oxide (PPO) resin, due to its regular main chain structure and low polarity, possesses natural advantages such as low dielectric constant (Dk≈2.5-2.8) and low moisture absorption (water absorption rate ≤0.1%), making it one of the more ideal choices for high-frequency copper-clad laminate matrix resins. However, traditional PPO resins mostly have inert groups such as methyl or phenyl on their side groups, lacking reactive sites. This prevents them from forming a stable three-dimensional network structure during crosslinking, resulting in crosslinked composite materials that typically suffer from insufficient mechanical strength and high-temperature resistance. In addition, existing PPO-based composite copper clad laminate materials have the following defects: (1) In order to achieve the reaction between PPO and crosslinking resin, free radical initiators (such as dicumyl peroxide) or curing accelerators need to be added. The residual initiators or accelerators will introduce polar sites, which will lead to an increase in dielectric loss (Df≥0.008) and moisture absorption rate (≥0.3%) of the composite material, which seriously affects the transmission quality of high frequency signals; (2) The crosslinking reaction mechanism is mostly a single free radical reaction, with low reaction efficiency and easy aging of the crosslinking network, resulting in a heat distortion temperature of the composite material ≤260℃, which cannot withstand high temperature processing processes such as welding.

[0004] Therefore, developing a high-temperature resistant composite material based on polyphenylene ether with low dielectric and low moisture absorption will play a positive role in breaking through the bottleneck of high-frequency and high-speed copper clad laminate technology and promoting the large-scale application of high-frequency and high-speed communication technology and millimeter wave technology. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of poor dielectric properties, high moisture absorption, and poor high temperature resistance of existing polyphenylene ether-based composite materials when used as copper clad laminate materials. This invention proposes an initiator-free crosslinked polyphenylene ether composite material, its preparation method, and its application.

[0006] To achieve the above objectives, the present invention provides an initiator-free crosslinked polyphenylene ether composite material, which is prepared from the following raw materials in parts by weight: 10-65 parts of polyphenylene ether resin, 35-90 parts of benzocyclobutene resin and 0-10 parts of functional filler. The structure of the polyphenylene ether resin is shown in Formula I:

[0007] I; In these cases, R is absent (i.e., the two benzene rings of R are combined to form a biphenyl structure), or R is a sulfoxide, sulfone, alkylene, or isopropyl group, and the number of carbon atoms in R is 0-3; R1~R 24 It is a hydrogen atom, alkyl, isopropyl, isobutyl, tertiary alkyl, vinyl, allyl, or 2-allyl, and R1~R 24 Same or different or not completely the same, R1~R 24 The number of carbon atoms in it is 0-5, R1~R 24 At least two of them contain unsaturated C=C double bonds; R a and R b It is a hydrogen atom, vinylphenyl, benzocyclobutenyl or methacrylate group, and R a and R b They are the same or different; x, y, m1, m2 and n are each integers from 0 to 100, and at least one of m1 and m2 is an integer between 2 and 40.

[0008] This invention discloses an initiator-free crosslinked polyphenylene ether composite material, which is a composite resin material obtained by crosslinking and curing a polyphenylene ether resin with unsaturated C=C double bonds on its side groups and a resin containing benzocyclobutene groups. It utilizes the principle that BCB groups can open rings to form conjugated double bonds under high-temperature conditions and undergo Diels-Alder (DA) reactions with olefin groups to achieve crosslinking and curing, thus eliminating the need for initiators and accelerators and avoiding the significant increase in dielectric loss constant and moisture absorption rate of the composite material caused by the introduction of initiators and accelerators. Furthermore, by using a polyphenylene ether resin with multiple unsaturated C=C double bonds on its side groups as the crosslinking material, more crosslinking reaction sites are created, enabling it to crosslink with benzocyclobutene resin to form a more stable three-dimensional network structure, thereby significantly increasing the high-temperature resistance of the composite material. Simultaneously, the unsaturated C=C double bonds are located on the side chains (not the ends) of the polyphenylene ether resin, resulting in lower moisture absorption of both the polyphenylene ether resin and the composite material. This initiator-free crosslinked polyphenylene ether composite material is composed of two low-dielectric resins crosslinked together. The crosslinking does not require the addition of initiators and accelerators, so the crosslinked composite material not only has the advantages of low dielectric loss and low moisture absorption, but also has more crosslinking sites and a higher degree of crosslinking. The composite material has better high-temperature resistance, which is conducive to the large-scale application of this composite material in copper clad laminate materials.

[0009] Preferably, in the polyphenylene ether resin, R is an alkylene group having 1-3 carbon atoms.

[0010] Preferably, in the polyphenylene ether resin, R1~R4, R5~R8, and R9~R 12 R 13 ~R 16 R 17 ~R 20 and R 21 ~R 24 Each of the components contains at least one unsaturated C=C double bond (i.e., each benzene ring in the main chain contains at least one unsaturated C=C double bond); the preferred polyphenylene ether resin has a more stable three-dimensional structure formed by crosslinking, better high-temperature resistance, and lower moisture absorption.

[0011] Preferably, the content of C=C double bonds on the side chain of the polyphenylene ether resin is 0.8-2.5 mmol / g.

[0012] Preferably, the number-average molecular weight of the polyphenylene ether resin is 1.5 × 10⁻⁶. 3 -3.0×1 g / mol.

[0013] Preferably, the polyphenylene ether resin is prepared by: Method 1, by polymerizing phenolic monomers containing unsaturated C=C double bond groups in an organic solvent; or, Method 2, by copolymerizing phenolic monomers containing unsaturated C=C double bond groups and phenolic monomers without C=C double bonds in an oxidizing atmosphere and an organic solvent.

[0014] More preferably, in method 2, the molar ratio of the phenolic monomer containing unsaturated C=C double bond groups to the phenolic monomer without C=C double bonds is 0.01-100:1; a further preferred molar ratio is 0.2-2:1, and the most preferred molar ratio is 0.25-1:1.

[0015] More preferably, the structure of the phenolic monomer containing unsaturated C=C double bond groups is shown in Formula II:

[0016] II; Wherein, T1 is an alkylene, cycloalkylene, isopropyl, or isobutyl group with 1-5 carbon atoms; T2-T4 are hydrogen atoms, alkyl, isopropyl, tertiary alkyl, vinyl, allyl, or 2-allyl groups with 0-5 carbon atoms, and T2-T4 may be the same, different, or not completely the same; one of T5 and T6 is a hydroxyl group, and the other is a hydrogen atom or a benzene ring structure with a phenolic hydroxyl group.

[0017] More preferably, T1 is an alkylene group with 1-3 carbon atoms; T2-T4 are alkyl groups with 1-2 carbon atoms.

[0018] More preferably, in the method for preparing the polyphenylene ether resin, the organic solvent is one or more selected from toluene, benzene, xylene, trimethylbenzene, chlorobenzene, nitrobenzene, trichloroethylene, dichloroethane, chloroform, tetrachloroethane, methanol, ethanol, isopropanol, tetrahydrofuran, dimethyl sulfoxide, n-hexane, and cyclohexane; even more preferably, the organic solvent is one or more selected from toluene, trimethylbenzene, tetrahydrofuran, methanol, and ethanol; most preferably, the organic solvent is toluene, methanol, or a combination thereof.

[0019] More preferably, the polymerization reaction and / or copolymerization reaction is carried out at a temperature of 10-150°C for 3-18 hours; even more preferably, the temperature is 20-100°C for 5-12 hours; and most preferably, the temperature is 20-90°C for 6-10 hours.

[0020] More preferably, the oxidizing atmosphere is a mixture of gases containing at least 10% oxygen by volume.

[0021] More preferably, method 2 further includes a catalyst and a phase transfer agent; the catalyst is a combination of a copper salt and a ligand, the copper salt being cuprous bromide, and the ligand being a secondary monoamine and / or a tertiary monoamine; the phase transfer agent is a quaternary ammonium compound, a quaternary phosphorus compound, a tertiary amine compound, or a combination thereof; most preferably, the secondary monoamine is di-n-butylamine, the tertiary monoamine is N,N-dimethylbutylamine, and the phase transfer agent is N,N,N',N'-decyldimethylammonium chloride.

[0022] Preferably, the benzocyclobutene resin is one or a mixture of several of the following: siloxanes, carbosilanes, polyether siloxanes, or hydrocarbon resins containing benzocyclobutene groups.

[0023] Preferably, the content of benzocyclobutene groups in the benzocyclobutene resin is 3.0-7.0 mmol / g.

[0024] Preferably, the functional filler is one or more of phosphorus-based flame retardants, nano-silica powder, and release agents.

[0025] Preferably, the composite material has a dielectric constant of ≤2.8 at 1MHz, a dielectric loss of ≤0.005 at 1MHz, a water absorption rate of ≤0.2% at 24h and 23℃, a heat distortion temperature of ≥280℃ at 1.82MPa, and a tensile strength of ≥85MPa.

[0026] To achieve the above objectives, the present invention further provides a method for preparing an initiator-free cross-linked polyphenylene ether composite material, comprising the steps of: mixing the raw materials in the prescribed amounts evenly, and then cross-linking and curing them under an inert atmosphere or vacuum conditions.

[0027] This invention discloses a method for preparing an initiator-free crosslinked polyphenylene ether composite material. Utilizing the mechanism of the Diels-Alder (DA) reaction of raw materials, the crosslinking and curing of raw materials are achieved without the addition of an initiator, thereby preparing a crosslinked polyphenylene ether composite material. This preparation method features a simple reaction process, mild conditions, lower energy consumption, good controllability, stable product performance, and a green and environmentally friendly preparation process, making it suitable for large-scale, industrial production of crosslinked polyphenylene ether composite materials.

[0028] Preferably, the cross-linking curing temperature is 180℃~300℃ and the time is 2-12h; more preferably, the temperature is 200~240℃ and the time is 3-8h.

[0029] Preferably, the crosslinking curing is carried out by a segmented heating method. Specifically, the crosslinking reaction is first cured at 200°C for 2 hours, and then cured at 220°C for 1.5 hours.

[0030] Preferably, the inert atmosphere is one or more of nitrogen, helium, and argon; nitrogen is preferred.

[0031] Preferably, the method for mixing the raw materials is melt blending or solution blending.

[0032] Preferably, in the case of solution blending, the solvent is one or more of toluene, xylene, trimethylbenzene, chloroform, and tetrahydrofuran; the resin (including the sum of polyphenylene ether resin and benzocyclobutene resin) has a solid content of 20-90 wt%.

[0033] To achieve the above objectives, the present invention further provides an application of an initiator-free cross-linked polyphenylene ether composite material in the core material or adhesive layer of copper clad laminates; using the cross-linked polyphenylene ether composite material of the present invention in copper clad laminate materials can effectively reduce the dielectric loss and failure rate of copper clad laminates (low moisture absorption), reduce material costs, facilitate processing (high temperature resistance), and is suitable for large-scale application in copper clad laminates.

[0034] Preferably, the copper-clad laminate operates at a frequency of 1MHz-10GHz and has a signal transmission attenuation of ≤0.1dB / cm.

[0035] Beneficial effects of the present invention

[0036] 1. The composite material of the present invention utilizes the principle that the BCB group can open the ring to form a conjugated double bond under high temperature conditions and can undergo a Diels-Alder (DA) reaction with olefin groups to achieve cross-linking and curing. Therefore, there is no need to add initiators and accelerators, avoiding the problem of a significant increase in the dielectric loss constant and moisture absorption rate of the composite material due to the introduction of initiators and accelerators (dielectric constant (1MHz) ≤2.5, dielectric loss (1MHz) ≤0.004, water absorption rate (24h, 23℃) ≤0.2%).

[0037] 2. The composite material of the present invention uses polyphenylene ether resin with multiple unsaturated C=C double bonds on the side groups as the crosslinking material, which has more crosslinking reaction sites and can crosslink with benzocyclobutene resin to form a more stable three-dimensional network structure, thereby significantly increasing the high temperature resistance of the composite material (heat distortion temperature ≥280℃, thermal decomposition temperature (T5%) ≥420℃).

[0038] 3. The preparation method of the composite material of the present invention has a simple reaction process, mild conditions, lower energy consumption, good controllability, stable product performance, and green and environmentally friendly preparation process, making it suitable for large-scale, industrial production of cross-linked polyphenylene ether composite materials.

[0039] 4. The cross-linked polyphenylene ether composite material of the present invention can be used in copper clad laminate materials, which can effectively reduce the dielectric loss and failure rate of copper clad laminate (low moisture absorption), reduce material costs, and make processing more convenient (high temperature resistance), making it suitable for large-scale application in copper clad laminates. Attached Figure Description

[0040] Figure 1 This is a schematic diagram illustrating the mechanism of the DA crosslinking reaction between polyphenylene ether resin and benzocyclobutene resin of the present invention.

[0041] Figure 2 This is a schematic diagram illustrating the mechanism of the ring-opening crosslinking reaction that the benzocyclobutene resin itself can undergo in this invention.

[0042] Figure 3 The infrared spectrum is shown for the polyphenylene ether resin with vinyl groups synthesized in Example 1 of this invention. Detailed Implementation

[0043] The technical solution of the present invention will be further described in detail below with reference to the embodiments.

[0044] Unless otherwise specified, all raw materials used in the embodiments of the present invention are commercially available products.

[0045] The specifications of the raw materials used in the specific embodiments of this invention are as follows: 2-Allylphenol: 97.5% purity, Shanghai Maclean Biochemical Technology Co., Ltd. 2,6-Dimethylphenol (DMP): 99.1% purity, Sinopharm Chemical Reagent Co., Ltd.; BCB resin: BCB group content 3.0-7.0 mmol / g, Mianyang Fulixin Materials Co., Ltd.; Oxidative coupling agents: CuCl / triethylamine complex (molar ratio 1:2.5), CuBr / pyridine complex (molar ratio 1:2), self-made; Solvents: Toluene, ethanol, chloroform, and tetrahydrofuran, all analytical grade, Sinopharm Chemical Reagent Co., Ltd.

[0046] In a specific embodiment of the present invention, the performance testing method is as follows: Dielectric constant (Dk) and dielectric loss (Df): Tested at 1MHz using a precision impedance analyzer according to GB / T 1409-2006; Water absorption rate: Tested according to GB / T 1034-2008, after soaking in distilled water at 23℃ for 24 hours; Tensile strength / flexural strength: tested using a universal testing machine according to GB / T 1040.1-2006 and GB / T 9341-2008 (tensile rate 5 mm / min). Thermal decomposition temperature (T)5% According to GB / T 27761-2011, thermogravimetric analyzer (N atmosphere, heating rate 10℃ / min); Crosslinking conversion rate: double bond characteristic peak (1640 cm⁻¹) was measured by FT-IR. -1 ) Calculation of residual amount.

[0047] Examples 1-3

[0048] A cross-linked polyphenylene ether composite material without initiator is composed of allyl polyphenylene ether resin and BCB resin cross-linked together (see Table 1 for specific composition). The specific steps are as follows: (1) The allyl polyphenylene ether resin (with a double bond content of 1.9 mmol / g on the side chain and a number average molecular weight of 3.5 × 10⁻⁶) is cross-linked together with BCB resin. 3 (1) Add g / mol) and BCB resin (divinylsiloxane-bisbenzocyclobutene (DVSBCB) resin, BCB group content 5.1 mmol / g) to a single-necked flask; (2) Then add chloroform, adjust the resin solid content to 40 wt%, and ultrasonically disperse at 300 W for 30 min (power density 1 W / mL) to ensure uniform resin mixing; (3) Cast the dispersion evenly onto a polytetrafluoroethylene plate (casting rate 5 cm / s), vacuum dry at 80 °C for 4 h to remove solvent, and obtain a prepreg film with a thickness of 0.2 mm; (4) Place the prepreg film in an oven, and under a nitrogen atmosphere, use a segmented heating process (reaction principle as follows) Figure 1 As shown): First, heat at 200℃ for 2 hours, then heat at 220℃ for 1.5 hours, and then cool naturally to room temperature to obtain an initiator-free cross-linked polyphenylene ether composite film.

[0049] Table 1 Composition of raw materials in Examples 1-3

[0050] The preparation method of allyl polyphenylene ether resin is as follows: (1) Set up the apparatus (equip a 5L three-necked flask with a mechanical stirrer, thermometer, nitrogen inlet tube and reflux condenser); (2) Then purge the apparatus with nitrogen (flow rate 50mL / min) 3 times, 5min each time, to completely remove air and avoid monomer oxidation; (3) Add mixed solvent (toluene 375mL + ethanol 125mL), 2-allylphenol (100g), CuCl / triethylamine complex (molar ratio 1:2.5) 1.2g in sequence, stir at 350r / min until completely dissolved (about 30min), heat to 45℃ and react at a constant temperature for 7h, continuously purging oxygen (40 SCCM); (4) After the reaction is completed, cool the reaction solution to room temperature, add 200mL of 1mol / L dilute hydrochloric acid, stir and wash for 15min, let stand for layering and discard the aqueous phase (containing copper ions), repeat washing 4 times. (5) The organic phase was transferred to a rotary evaporator and concentrated to 170 mL (1 / 3 of the original volume) by vacuum distillation at 60 °C and -0.09 MPa. 510 mL of methanol was slowly added dropwise (dropping rate 10 mL / min), and the mixture was stirred to precipitate for 1 h to form a yellow powder. (6) The solid was collected by vacuum filtration and dried at 80 °C for 6 h to obtain a yellow powder of allyl polyphenylene ether resin (infrared spectrum as shown in the figure). Figure 2 As shown; NMR spectrum as shown Figure 3 (As shown).

[0051] Examples 4-8

[0052] A cross-linked polyphenylene ether composite material without initiator is composed of 50 parts by weight of allyl polyphenylene ether resin and 50 parts by weight of BCB resin. The specific steps are as follows: (1) The allyl polyphenylene ether resin (the content of double bonds on the side chain is shown in Table 2, and the number average molecular weight is 2.95×10) is cross-linked. 3 (2) Add g / mol) and BCB resin (4-[(4-vinylphenyl)vinyl]benzocyclobutene resin, BCB group content 3.3 mmol / g) to a single-necked flask; (3) Add toluene, adjust the resin solid content to 30 wt%, and ultrasonically disperse at 300 W for 30 min (power density 1 W / mL) to ensure uniform resin mixing; (4) Degas the dispersion for 15 min (vacuum degree -0.08 MPa) and pour it into a 5 mm thick stainless steel mold; vacuum dry at 85℃ for 4 h to remove solvent and obtain composite material blank; (5) Place the blank in an oven and use a segmented heating process under nitrogen atmosphere: first keep at 200℃ for 2 h, then keep at 230℃ for 1 h, and cool naturally to room temperature to obtain initiator-free cross-linked polyphenylene ether composite material parts.

[0053] Table 2. Double bond content on the side chain of allyl polyphenylene ether resins in Examples 4-8

[0054] Examples 9-13

[0055] An initiator-free crosslinked polyphenylene ether composite material, comprising 35 parts by weight of allyl polyphenylene ether resin (double bond content on side chains 1.8 mmol / g, number average molecular weight 4.3 × 10⁻⁶). 3 The prepreg was made by crosslinking 65 parts by weight of BCB resin (benzocyclobutene-functionalized siloxane oligomer, BCB group content is shown in Table 3) with g / mol) and 65 parts by weight of BCB resin (benzocyclobutene-functionalized siloxane oligomer, BCB group content is shown in Table 3). The specific steps are as follows: (1) Add allyl polyphenylene ether resin and BCB resin to a single-necked flask; (2) Add tetrahydrofuran, adjust the resin solid content to 50wt%, and ultrasonically disperse at 300W for 30min (power density 1W / mL) to ensure uniform mixing of resin; (3) Cast the dispersion evenly onto a polytetrafluoroethylene plate (casting rate 5cm / s), vacuum dry at 80℃ for 4h to remove solvent, and obtain a prepreg film with a thickness of 0.1mm; (4) Place the prepreg film in an oven, and under a nitrogen atmosphere, use a segmented heating process: first keep at 200℃ for 2h, then keep at 220℃ for 1h, and cool naturally to room temperature to obtain an initiator-free crosslinked polyphenylene ether composite film.

[0056] Table 3. BCB group content of BCB resins in Examples 9-13

[0057] Examples 14-16

[0058] A cross-linked polyphenylene ether composite material without initiator is made by cross-linking 50 parts by weight of allyl polyphenylene ether resin (with a double bond content of about 1.5 mmol / g on the side chain and a number average molecular weight as shown in Table 4) and 50 parts by weight of BCB resin (DVSBCB resin, with a BCB group content of 5.1 mmol / g). The specific steps are as follows: (1) Add allyl polyphenylene ether resin and BCB resin to a single-necked flask; (2) Then add chloroform to adjust the resin solid content to 40 wt% and 30 wt% respectively. (2) Disperse the resin by ultrasonication for 30 minutes (power density 1W / mL) to ensure uniform mixing; (3) Flow the dispersion evenly onto a polytetrafluoroethylene plate (flow rate 5cm / s), and vacuum dry at 80℃ for 4 hours to remove the solvent, and obtain a prepreg film with a thickness of 0.2mm; (4) Place the prepreg film into an oven and use a segmented heating process under a nitrogen atmosphere: first keep it at 200℃ for 2 hours, then keep it at 220℃ for 1.5 hours, and cool it naturally to room temperature to obtain an initiator-free crosslinked polyphenylene ether composite film.

[0059] Table 4. Number average molecular weights of allyl polyphenylene ether resins in Examples 14-16

[0060] Example 17

[0061] A cross-linked polyphenylene ether composite material without initiator is composed of 10 parts by weight of polyphenylene ether resin (as shown in the formula below) and 90 parts by weight of BCB resin. The specific steps are as follows: (1) cross-link the polyphenylene ether resin (double bond content 1.91 mmol / g, number average molecular weight 3.71 × 10⁻⁶) to form a cross-linked composite material. 3 (2) Add g / mol) and BCB resin (DVSBCB resin, BCB group content 5.1mmol / g) to a single-necked flask; (3) Add toluene, adjust the resin solid content to 30wt%, and ultrasonically disperse at 300W for 30min (power density 1W / mL) to ensure uniform resin mixing; (4) Degas the dispersion for 15min (vacuum degree -0.08MPa) and pour it into a 5mm thick stainless steel mold; vacuum dry at 85℃ for 4h to remove solvent and obtain composite material blank; (5) Place the blank in an oven and use a segmented heating process under nitrogen atmosphere: first keep at 200℃ for 2h, then keep at 230℃ for 1h, and cool naturally to room temperature to obtain initiator-free cross-linked polyphenylene ether composite material parts.

[0062] The structure of the polyphenylene ether resin is as follows:

[0063] Where x, y, m1, and m2 are each integers from 0 to 100, and the average sum of all x and m2 in the numerator is 18; the average sum of all m1 and y is 7.1.

[0064] Example 18

[0065] A cross-linked polyphenylene ether composite material without initiator is composed of 65 parts by weight of polyphenylene ether resin (as shown in the formula below) and 35 parts by weight of BCB resin. The specific steps are as follows: (1) cross-link the polyphenylene ether resin (double bond content 1.48 mmol / g, number average molecular weight 2.43 × 10⁻⁶) to form a composite material. 3 (2) Add g / mol) and BCB resin (DVSBCB resin, BCB group content 5.1 mmol / g) to a single-necked flask; (3) Add toluene, adjust the resin solid content to 30 wt%, and ultrasonically disperse at 300 W for 30 min (power density 1 W / mL) to ensure uniform resin mixing; (4) Degas the dispersion for 15 min (vacuum degree -0.08 MPa) and pour it into a 5 mm thick stainless steel mold; vacuum dry at 85 °C for 4 h to remove solvent and obtain composite material blank; (5) Place the blank in an oven, keep it at 210 °C for 4 h under nitrogen atmosphere, and cool it naturally to room temperature to obtain initiator-free cross-linked polyphenylene ether composite material parts.

[0066] The structure of the polyphenylene ether resin is as follows: ; Where x, y, m1, and m2 are each integers from 0 to 100, and the average sum of all x and m2 in the numerator is 11.5; the average sum of all m1 and y is 3.6.

[0067] Comparative Example 1

[0068] A cross-linked polyphenylene ether composite material is prepared by the following method: (1) PPO with terminal hydroxyl groups modified (number average molecular weight 2.4 × 10⁻⁶) 3 35 parts of BCB resin (DVSBCB resin, BCB group content 5.1 mmol / g) and 0.5 parts of dicumyl peroxide (DCP) initiator were added to a single-necked flask. (2) Then add chloroform to adjust the resin solid content to 40wt%, and ultrasonically disperse at 300W for 30min (power density 1W / mL) to ensure that the resin is mixed evenly; (3) The dispersion was uniformly cast onto a polytetrafluoroethylene plate (casting rate 5 cm / s), and vacuum dried at 80°C for 4 h to remove the solvent, resulting in a prepreg film with a thickness of 0.2 mm. (4) Place the prepreg film in an oven and use a segmented heating process under a nitrogen atmosphere: first heat at 120°C for 1 hour, then heat at 180°C for 1 hour, and finally heat at 200°C for 3 hours. Then cool naturally to room temperature to obtain a cross-linked polyphenylene ether composite film.

[0069] Comparative Example 2

[0070] A cross-linked polyphenylene ether composite material is prepared by the following method: (4) Modify terminal vinylphenyl PPO (number average molecular weight 2.8 × 10⁻⁶) 3 35 parts of BCB resin (DVSBCB resin, BCB group content 5.1mmol / g) and 65 parts of BCB resin (DVSBCB resin, BCB group content 5.1mmol / g) were added to a single-necked flask; (5) Then add chloroform to adjust the resin solid content to 40wt%, and ultrasonically disperse at 300W for 30min (power density 1W / mL) to ensure that the resin is mixed evenly; (6) The dispersion was uniformly cast onto a polytetrafluoroethylene plate (casting rate 5 cm / s), and vacuum dried at 80°C for 4 h to remove the solvent, resulting in a prepreg film with a thickness of 0.2 mm. (4) Place the prepreg film in an oven and use a segmented heating process under a nitrogen atmosphere: first heat at 120°C for 1 hour, then heat at 180°C for 1 hour, and finally heat at 200°C for 3 hours. Then cool naturally to room temperature to obtain a cross-linked polyphenylene ether composite film.

[0071] Comparative Example 3

[0072] A cross-linked polyphenylene ether composite material without initiator is composed of 35 parts by weight of polyphenylene ether resin (as shown in the formula below) and 65 parts by weight of BCB resin. The specific steps are as follows: (1) cross-link the polyphenylene ether resin (with a double bond content of 1.75 mmol / g on the side chain and a number average molecular weight of 2.13 × 10⁻⁶) to form a cross-linked polyphenylene ether resin. 4 (2) Add g / mol) and BCB resin (DVSBCB resin, BCB group content 5.1mmol / g) to a single-necked flask; (3) Add toluene, adjust the resin solid content to 30wt%, and ultrasonically disperse at 300W for 30min (power density 1W / mL) to ensure uniform resin mixing; (4) Degas the dispersion for 15min (vacuum degree -0.08MPa) and pour it into a 5mm thick stainless steel mold; vacuum dry at 85℃ for 4h to remove solvent and obtain composite material blank; (5) Place the blank in an oven and use a segmented heating process under nitrogen atmosphere: first keep at 200℃ for 2h, then keep at 230℃ for 1h, and cool naturally to room temperature to obtain initiator-free cross-linked polyphenylene ether composite material parts.

[0073] The structure of the polyphenylene ether resin is shown below: ; Where x and m2 are integers from 26 to 100, and y and m1 are integers from 0 to 100, and the average sum of all x and m2 in the numerator is 126; the average sum of all m1 and y is 37.2.

[0074] Experimental example: The cross-linked polyphenylene ether composite materials prepared in Examples 1-18 and Comparative Examples 1-3 were tested for dielectric constant, dielectric loss, water absorption (24h, 23℃), heat distortion temperature (1.82MPa), tensile strength, cross-linking conversion rate, and dielectric change rate after damp heat aging (1000h in 85℃ / 85% RH). The test results are shown in Table 5.

[0075] Table 5. Test results of composite material properties in Examples 1-18 and Comparative Examples 1-3

[0076] Analysis of the test results in Table 5 shows that, within the preferred scope of this invention, the prepared cross-linked polyphenylene ether composite material exhibits excellent low dielectric properties, thermal stability, and low water absorption. Furthermore, the composite material has a high cross-linking density and stable overall performance.

[0077] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An initiator-free crosslinked polyphenylene ether composite material, characterized in that, It is prepared from the following raw materials in parts by weight: 10-65 parts of polyphenylene ether resin, 35-90 parts of benzocyclobutene resin and 0-10 parts of functional filler. The structure of the polyphenylene ether resin is shown in Formula I: I； Where R is absent, or R is sulfoxide, sulfone, alkylene, or isopropyl, and the number of carbon atoms in R is 0-3; R1~R 24 It is a hydrogen atom, alkyl, isopropyl, isobutyl, tertiary alkyl, vinyl, allyl, or 2-allyl, and R1~R 24 Same or different or not completely the same, R1~R 24 The number of carbon atoms in it is 0-5, R1~R 24 At least two of them contain unsaturated C=C double bonds; Ra and Rb are hydrogen atoms, vinylphenyl, benzocyclobutenyl or methacrylate groups, and Ra and Rb may be the same or different; x, y, m1, m2 and n are each integers from 0 to 100, and at least one of m1 and m2 is an integer between 2 and 40.

2. The initiator-free crosslinked polyphenylene ether composite material according to claim 1, characterized in that, In the polyphenylene ether resin, R is an alkylene group having 1-3 carbon atoms; and / or, in the polyphenylene ether resin, R1~R4, R5~R8, R9~R 12 R 13 ~R 16 R 17 ~R 20 and R 21 ~R 24 Each of them contains at least one unsaturated C=C double bond.

3. The initiator-free crosslinked polyphenylene ether composite material according to claim 1, characterized in that, In the polyphenylene ether resin, the content of C=C double bonds on the side chain is 0.8-2.5 mmol / g; and / or, the number average molecular weight of the polyphenylene ether resin is 1.5 × 10⁻⁶. 3 -10.0×1 g / mol.

4. The initiator-free crosslinked polyphenylene ether composite material according to claim 1, characterized in that, The polyphenylene ether resin is prepared by: Method 1, by polymerizing phenolic monomers containing unsaturated C=C double bond groups in an organic solvent; or, Method 2, by copolymerizing phenolic monomers containing unsaturated C=C double bond groups and phenolic monomers without C=C double bonds in an oxidizing atmosphere and an organic solvent.

5. The initiator-free crosslinked polyphenylene ether composite material according to claim 4, characterized in that, The structure of the phenolic monomer containing unsaturated C=C double bond groups is shown in Formula II: II; Wherein, T1 is an alkylene, cycloalkylene, isopropyl, or isobutyl group with 1-5 carbon atoms; T2-T4 are hydrogen atoms, alkyl, isopropyl, tertiary alkyl, vinyl, allyl, or 2-allyl groups with 0-5 carbon atoms, and T2-T4 may be the same, different, or not completely the same; one of T5 and T6 is a hydroxyl group, and the other is a hydrogen atom or a benzene ring structure with a phenolic hydroxyl group.

6. The initiator-free crosslinked polyphenylene ether composite material according to claim 1, characterized in that, The benzocyclobutene resin is one or a mixture of several of the following: siloxanes, carbosilanes, polyether siloxanes, or hydrocarbon resins containing benzocyclobutene groups.

7. The initiator-free crosslinked polyphenylene ether composite material according to claim 1, characterized in that, The benzocyclobutene resin contains 3.0-7.0 mmol / g of benzocyclobutene groups.

8. A method for preparing an initiator-free crosslinked polyphenylene ether composite material according to any one of claims 1-7, characterized in that, The process includes the following steps: After mixing the raw materials in the specified amounts evenly, the mixture is cross-linked and cured under an inert atmosphere or vacuum.

9. The method for preparing the initiator-free crosslinked polyphenylene ether composite material according to claim 8, characterized in that, The cross-linking curing temperature is 180℃~300℃, and the time is 2-12h; preferably, the cross-linking curing is carried out by segmented heating reaction, specifically, the cross-linking reaction is first cured at 200℃ for 2h, and then cured at 220℃ for 1.5h.

10. Application of an initiator-free cross-linked polyphenylene ether composite material in copper clad laminate core material or adhesive layer.

Images