Phosphorus-containing flame retardants, methods of making and using the same, resin compositions and uses thereof

Abstract

This invention provides a phosphorus-containing flame retardant, its preparation method and application, and a resin composition and its application, specifically relating to the field of polymer materials technology. The phosphorus-containing flame retardant provided by this invention achieves an integrated design of the flame-retardant unit and the elastic matrix at the molecular scale by directionally and controllably grafting phosphorus-containing groups M onto the active sites of the polybutadiene soft segments in a styrene-butadiene-styrene block copolymer via covalent bonds. This structure retains the inherent high flexibility, impact resistance, and processing rheological properties of the styrene-butadiene-styrene block copolymer while imparting intrinsic, durable, and uniformly distributed flame-retardant capabilities to the material. Simultaneously, because the phosphorus element is anchored to the polymer backbone / side chain, no small molecule polar impurities are introduced, significantly suppressing dielectric polarization loss and hygroscopicity increases. This provides a structural basis and performance guarantee for the subsequent construction of a high-end thermosetting resin system for copper-clad laminates with low Dk / Df, high Tg, and low CTE.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a phosphorus-containing flame retardant, its preparation method and application, and a resin composition and its application. Background Technology

[0002] To meet the environmental requirements of halogen-free combustion, phosphorus-containing flame retardants, as the primary alternative to traditional bromine-based flame retardants, have been widely used in the copper-clad laminate industry. Their flame-retardant mechanism mainly lies in the fact that during combustion, phosphorus compounds promote the formation of a dense char layer on the polymer surface, providing heat insulation and oxygen barrier functions; simultaneously, they can capture free radicals in the gas phase, interrupting the combustion chain reaction. Compared to halogen-based flame retardants, phosphorus-containing flame retardants have the advantages of low smoke, low toxicity, and environmental friendliness, complying with international environmental directives such as RoHS.

[0003] However, the widely used additive phosphorus-containing flame retardants have also revealed significant drawbacks in high-end applications. First, to achieve an effective flame retardant rating, a high addition level (typically above 10%) is often required. This inevitably compromises the inherent superior properties of the matrix resin, leading to a decrease in the glass transition temperature (Tg) of the composite material, an increase in dielectric loss, increased hygroscopicity, and deterioration of mechanical properties. Second, additive small-molecule flame retardants have limited compatibility with the resin matrix, and migration and precipitation problems may occur during long-term use. This not only causes the flame retardant performance to decay over time but may also affect the reliability of subsequent processes.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a phosphorus-containing flame retardant, its preparation method and application, and a resin composition and its application, aiming to solve at least one of the above-mentioned technical problems in the prior art.

[0006] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: A first aspect of the present invention provides a phosphorus-containing flame retardant, wherein the phosphorus-containing flame retardant is a modified phosphorus-containing styrene-butadiene-styrene block copolymer; The chemical structural formula of the modified phosphorus-containing styrene-butadiene-styrene block copolymer is: ; Where a > 1, b is an integer between 15 and 75, c is an integer between 15 and 75, and d > 1; M is a phosphorus-containing group.

[0007] Furthermore, the phosphorus-containing group includes , , , , , , or .

[0008] Preferably, the phosphorus-containing flame retardant has the following structural formula: , .

[0009] Furthermore, the chemical structural formula of the styrene-butadiene-styrene block copolymer is as follows: ; Where a > 1, b is an integer between 15 and 75, c is an integer between 15 and 75, and d > 1.

[0010] Preferably, in the phosphorus-containing flame retardant, the grafting rate of the phosphorus-containing groups is 3~12wt%.

[0011] Preferably, the number average molecular weight of the phosphorus-containing flame retardant is 4000~35000 g / mol, more preferably 7000~25000 g / mol.

[0012] Preferably, the molecular weight distribution of the phosphorus-containing flame retardant is 1.0 to 1.2.

[0013] The second aspect of the present invention provides a method for synthesizing the phosphorus-containing flame retardant, wherein, under the protection of an inert gas, a styrene-butadiene-styrene block copolymer is dissolved in a solvent, a phosphorus-containing compound and a thermal initiator are added to react, and after the reaction is completed, the phosphorus-containing flame retardant is obtained by ethanol precipitation, filtration and drying.

[0014] Furthermore, the phosphorus-containing compound includes at least one of DOPO and DPPO.

[0015] Preferably, the amount of phosphorus-containing compound added is 4 to 15% of the mass of the styrene-butadiene-styrene block copolymer.

[0016] Preferably, the amount of solvent added is 4 to 6 times the mass of the styrene-butadiene-styrene block copolymer.

[0017] Preferably, the solvent includes at least one of toluene, xylene, butanone, cyclohexanone, propylene glycol methyl ether acetate, and dimethylformamide.

[0018] Preferably, the reaction temperature is 90~110℃ and the time is 6~10h.

[0019] The third aspect of the present invention provides the application of the phosphorus-containing flame retardant in the preparation of flame-retardant engineering plastics, flame-retardant coatings, flame-retardant adhesives or flame-retardant resin composites.

[0020] The fourth aspect of the present invention provides a resin composition comprising, by weight, 80-150 parts of a phosphorus-containing flame retardant, 50-100 parts of a modified polyphenylene ether resin, 15-25 parts of a crosslinking agent, 50-100 parts of a filler, and 0.2-3 parts of an initiator. The phosphorus-containing flame retardant is the phosphorus-containing flame retardant described in the first aspect.

[0021] Furthermore, the modified polyphenylene ether resin includes acrylate and / or styrene-terminated polyphenylene ether resins.

[0022] Preferably, the number average molecular weight of the modified polyphenylene ether resin is 500~25000 g / mol.

[0023] Preferably, the crosslinking agent comprises at least one selected from the group consisting of a triallenyl isocyanurate compound, a polyfunctional acrylate compound, a polyfunctional methacrylate compound, a polyfunctional vinyl compound, and a divinylbenzene compound.

[0024] Preferably, the trialnyl isocyanurate compound is at least one of trialnyl isocyanurate, trialnyl cyanurate, trimethylallyl isocyanurate, and trimethylallyl cyanurate.

[0025] Preferably, the multifunctional acrylate compound includes trimethylolpropane triacrylate.

[0026] Preferably, the polyfunctional methacrylate compound includes trimethylolpropane trimethacrylate.

[0027] Preferably, the multifunctional vinyl compound includes at least one of tert-butylstyrene, diallyl isophthalate, and diallyl phthalate.

[0028] Preferably, the filler material includes at least one of aluminum nitride, aluminum borate, magnesium oxide, magnesium carbonate, cubic boron nitride, crystalline silicon dioxide, synthetic silicon dioxide, hollow silicon dioxide, spherical silicon dioxide, fused silicon dioxide, talc, aluminum oxide, barium sulfate, barium titanate, strontium titanate, calcium carbonate, or titanium dioxide.

[0029] Preferably, the filler material comprises spherical silica fillers whose surfaces have been treated with vinyl, allyl, or (meth)acrylate silane coupling agents.

[0030] Preferably, the particle size of the filler material is 0.5~5μm.

[0031] Preferably, the initiator includes azobisisobutyronitrile, azobis(2-isopropyl)butyronitrile, azobis(hexamethylene)-butyronitrile, benzoyl peroxide, dimethylbenzoyl peroxide, diisopropyl peroxide, dicumyl peroxide, cyclohexanone peroxide, methyl ethyl ketone peroxide, dicyclohexyl peroxide, benzoic acid peroxide, tert-butyl peroxide, butyl benzoic acid peroxide, tert-butyl peroxide, di-tert-butyl peroxide, dilauroyl peroxide, cumyl peroxide, tert-butyl peroxide, tert-butyl peroxypentanoate, tert-butyl peroxypentanoate, tert-butyl peroxyisobutyrate, tert-butyl peroxide-3,5,5-trimethylhexanoate, tert-butyl peroxyacetate, tert-butyl peroxybenzoate, and 1,1-di-tert-butyl peroxide-3... At least one of the following: 5,5-trimethylcyclohexane, 1,1-di-tert-butylcyclohexane peroxide, 2,2-di(tert-butylperoxide)butane, bis(4-tert-butylcyclohexyl)peroxide, hexadecyl peroxide, tetradecyl peroxide, dipentylhexyl peroxide, diisopropylbenzene peroxide, bis(tert-butylperoxide isopropyl)benzene, 2,5-dimethyl-2,5-di-tert-butylperoxide, 2,5-dimethyl-2,5-di-tert-butylperoxide hexyne, diisopropylbenzene hydrogen peroxide, isopropylbenzene hydrogen peroxide, tert-pentyl hydrogen peroxide, tert-butyl hydrogen peroxide, tert-butyl isopropylbenzene peroxide, tert-butylperoxide-2-ethylhexyl percarbonate, and 4,4-di(tert-butylperoxide)pentanoate.

[0032] Furthermore, the resin composition also includes 0.1 to 2 parts of toughening agent.

[0033] Preferably, the toughening agent comprises a polystyrene-butadiene copolymer.

[0034] The fifth aspect of the present invention provides the use of the resin composition described herein in the preparation of copper-clad laminates.

[0035] Compared with the prior art, the present invention has at least the following beneficial effects: The phosphorus-containing flame retardant provided by this invention achieves an integrated design of flame-retardant units and elastic matrix at the molecular scale by directionally and controllably grafting phosphorus-containing groups M onto the active sites of polybutadiene soft segments in styrene-butadiene-styrene block copolymers in the form of covalent bonds. This structure retains the inherent high flexibility, impact resistance, and processing rheological properties of styrene-butadiene-styrene block copolymers, while also endowing the material with intrinsic, durable, and uniformly distributed flame retardant capabilities. It avoids the migration, precipitation, phase separation, and long-term performance degradation problems caused by poor compatibility of traditional additive phosphorus-containing flame retardants. At the same time, since the phosphorus element is anchored to the polymer backbone / side chain, no small molecule polar impurities are introduced, which significantly inhibits dielectric polarization loss and hygroscopicity increase. This provides a structural basis and performance guarantee for the subsequent construction of high-end thermosetting resin systems for copper clad laminates with low Dk / Df, high Tg, and low CTE.

[0036] Given the advantages of the aforementioned phosphorus-containing flame retardants, better flame retardant options are provided for the preparation of flame-retardant engineering plastics, flame-retardant coatings, flame-retardant adhesives, or flame-retardant resin composites. Furthermore, the resin composition provided by this invention constructs a thermosetting system that integrates intrinsic flame retardancy, low dielectric constant, high heat resistance, and strong interfacial properties, significantly improving copper foil peel strength, reducing moisture absorption expansion rate, and maintaining excellent dielectric consistency at high frequencies. After curing, this composition achieves UL94V-0 flame retardancy, Tg≥228°C, Dk≤3.3@10GHz, Df≤0.0048@10GHz, and a pyrolysis temperature (Td)≥408°C. Moreover, after PCT (120°C / 2h), the 288°C solder pot heat resistance time is >60s, fully meeting the stringent requirements of 5G high-frequency, high-speed PCB substrates for reliability, signal integrity, and green manufacturing. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0038] In the following, the terms “comprising,” “having,” and their cognates, which may be used in various embodiments of the invention, are intended only to indicate a particular feature, number, step, operation, element, component, or combination thereof, and should not be construed as excluding, firstly, the presence of one or more other features, numbers, steps, operations, elements, components, or combinations thereof, or adding the possibility of one or more features, numbers, steps, operations, elements, components, or combinations thereof.

[0039] A first aspect of the present invention provides a phosphorus-containing flame retardant, wherein the phosphorus-containing flame retardant is a modified phosphorus-containing styrene-butadiene-styrene block copolymer; The chemical structural formula of the modified phosphorus-containing styrene-butadiene-styrene block copolymer is: ; Where a > 1, b is an integer between 15 and 75, c is an integer between 15 and 75, and d > 1; M is a phosphorus-containing group.

[0040] The phosphorus-containing flame retardant provided by this invention achieves an integrated design of flame-retardant units and elastic matrix at the molecular scale by directionally and controllably grafting phosphorus-containing groups M onto the active sites of polybutadiene soft segments in styrene-butadiene-styrene block copolymers in the form of covalent bonds. This structure retains the inherent high flexibility, impact resistance, and processing rheological properties of styrene-butadiene-styrene block copolymers, while also endowing the material with intrinsic, durable, and uniformly distributed flame retardant capabilities. It avoids the migration, precipitation, phase separation, and long-term performance degradation problems caused by poor compatibility of traditional additive phosphorus-containing flame retardants. At the same time, since the phosphorus element is anchored to the polymer backbone / side chain, no small molecule polar impurities are introduced, which significantly inhibits dielectric polarization loss and hygroscopicity increase. This provides a structural basis and performance guarantee for the subsequent construction of high-end thermosetting resin systems for copper clad laminates with low Dk / Df, high Tg, and low CTE.

[0041] Furthermore, the phosphorus-containing group includes , , , , , , or .

[0042] Preferably, the phosphorus-containing flame retardant has the following structural formula: , .

[0043] Furthermore, the chemical structural formula of the styrene-butadiene-styrene block copolymer is as follows: ; Where a > 1, b is an integer between 15 and 75, c is an integer between 15 and 75, and d > 1.

[0044] Typical but not restrictive, b can be, for example, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70 or 75, or any integer in the range of 15 to 75; c can be, for example, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70 or 75, or any integer in the range of 15 to 75.

[0045] Preferably, in the phosphorus-containing flame retardant, the grafting rate of the phosphorus-containing groups is 3~12wt%.

[0046] Typically, but not limitingly, the grafting rate of the phosphorus-containing group can be, for example, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, or 12wt%, or any value in the range of 3 to 12wt%.

[0047] Preferably, the number average molecular weight of the phosphorus-containing flame retardant is 4000~35000 g / mol, more preferably 7000~25000 g / mol.

[0048] The number-average molecular weight of the phosphorus-containing flame retardant is typically, but not limitingly, 4000 g / mol, 8000 g / mol, 12000 g / mol, 16000 g / mol, 20000 g / mol, 24000 g / mol, 28000 g / mol, 32000 g / mol, or 35000 g / mol, or any value in the range of 4000 to 35000 g / mol; more preferably, its number-average molecular weight is, for example, 7000 g / mol, 10000 g / mol, 13000 g / mol, 16000 g / mol, 19000 g / mol, 22000 g / mol, or 25000 g / mol, or any value in the range of 7000 to 25000 g / mol.

[0049] Preferably, the molecular weight distribution of the phosphorus-containing flame retardant is 1.0 to 1.2.

[0050] The molecular weight distribution of the phosphorus-containing flame retardant is typically, but not limitingly, 1.0, 1.05, 1.1, 1.15 or 1.2, or any value in the range of 1.0 to 1.2.

[0051] The second aspect of the present invention provides a method for synthesizing the phosphorus-containing flame retardant, wherein, under the protection of an inert gas, a styrene-butadiene-styrene block copolymer is dissolved in a solvent, a phosphorus-containing compound and a thermal initiator are added to react, and after the reaction is completed, the phosphorus-containing flame retardant is obtained by ethanol precipitation, filtration and drying.

[0052] Furthermore, the phosphorus-containing compound includes at least one of DOPO and DPPO.

[0053] DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) combines high phosphorus content, rigid cage structure, and excellent gas-phase free radical capture and condensed-phase carbonization catalytic ability. Its active sites at the ortho positions of the benzene ring readily undergo free radical addition or Michael addition with the double bonds of polybutadiene, achieving directional grafting. Although DPPO (diphenylphosphine oxide) has a slightly lower phosphorus content, it has low steric hindrance and high reactivity, which is conducive to achieving a high grafting rate under mild conditions. Furthermore, its hydrophobicity can further suppress hygroscopicity.

[0054] In some embodiments of the present invention, when preparing the phosphorus-containing flame retardant, AIBN (azobisisobutyronitrile) and BPO are added as thermally initiated free radical sources. The amount added is 0.15~0.6% of the styrene-butadiene-styrene block copolymer. This is used to controllably activate the C=C double bonds in the polybutadiene soft segments, generating carbon-centered free radicals, which then efficiently and selectively covalently bond with DOPO or DPPO. This avoids the introduction of strong acids / bases or metal catalysts, ensuring the integrity and thermal stability of the styrene-butadiene-styrene block copolymer main chain.

[0055] Preferably, the amount of phosphorus-containing compound added is 4 to 15% of the mass of the styrene-butadiene-styrene block copolymer.

[0056] The amount of phosphorus-containing compound added, typically but not limitingly, can be 4%, 6%, 8%, 10%, 12%, 14% or 15% of the mass of the styrene-butadiene-styrene block copolymer, or any value in the range of 4% to 15%.

[0057] Preferably, the amount of solvent added is 4 to 6 times the mass of the styrene-butadiene-styrene block copolymer.

[0058] The amount of solvent added is typically, but not limitingly, 4, 4.5, 5, 5.5, or 6 times the mass of the styrene-butadiene-styrene block copolymer, or any value in the range of 4 to 6 times.

[0059] Preferably, the solvent includes at least one of toluene, xylene, butanone, cyclohexanone, propylene glycol methyl ether acetate, and dimethylformamide.

[0060] Preferably, the reaction temperature is 90~110℃ and the time is 6~10h.

[0061] The temperature of the reaction, typically but not limitingly, can be 90°C, 95°C, 100°C, 105°C or 110°C, or any value within the range of 90°C to 110°C; the time of the reaction, typically but not limitingly, can be 6h, 7h, 8h, 9h or 10h, or any value within the range of 6h to 10h.

[0062] The third aspect of the present invention provides the application of the phosphorus-containing flame retardant in the preparation of flame-retardant engineering plastics, flame-retardant coatings, flame-retardant adhesives or flame-retardant resin composites.

[0063] The fourth aspect of the present invention provides a resin composition comprising, by weight, 80-150 parts of a phosphorus-containing flame retardant, 50-100 parts of a modified polyphenylene ether resin, 15-25 parts of a crosslinking agent, 50-100 parts of a filler, and 0.2-3 parts of an initiator. The phosphorus-containing flame retardant is the phosphorus-containing flame retardant described in the first aspect.

[0064] Typically, but not limitingly, the amount of the phosphorus-containing flame retardant can be, for example, 80 parts, 90 parts, 100 parts, 110 parts, 120 parts, 130 parts, 140 parts, or 150 parts, or any value within the range of 80 to 150 parts; the amount of the modified polyphenylene ether resin can be, for example, 50 parts, 60 parts, 70 parts, 80 parts, 90 parts, or 100 parts, or any value within the range of 50 to 100 parts; the amount of the crosslinking agent can be, for example, 15 parts. The number of parts can be 17, 19, 21, 23, or 25, or any value within the range of 15 to 25; the number of parts of the filler material can be, for example, 50, 60, 70, 80, 90, or 100, or any value within the range of 50 to 100; the number of parts of the initiator can be, for example, 0.2, 0.5, 1, 1.5, 2, 2.5, or 3, or any value within the range of 0.2 to 3.

[0065] Furthermore, the modified polyphenylene ether resin includes acrylate and / or styrene-terminated polyphenylene ether resins. Styrene end-capping imparts vinyl functional groups to the PPE ends, allowing it to directly participate in free radical copolymerization or undergo efficient olefin addition reactions with crosslinking agents such as triallyl isocyanurate, increasing crosslinking density and network rigidity, thereby synergistically improving Tg and thermal decomposition temperature. Acrylate end-capping introduces highly reactive C=C double bonds and polar ester groups, enhancing hydrogen bonding / dipole interactions with phosphorus-containing flame retardants and silane coupling agents-treated fillers, while significantly improving the system's melt viscosity and processing rheology, optimizing glass cloth wettability and prepreg uniformity.

[0066] Preferably, the number average molecular weight of the modified polyphenylene ether resin is 500~25000 g / mol, more preferably 700~13000 g / mol. When the number average molecular weight is below 500 g / mol, the polyphenylene ether segments are too short, resulting in weak intermolecular forces, which leads to an increase in dielectric constant (Dk) and dielectric loss factor (Df), and a decrease in film-forming properties and thermal stability. When the number average molecular weight is above 25,000 g / mol, the melt viscosity is too high, the fluidity of the resin system deteriorates significantly, affecting the uniformity of adhesive application and the wettability of glass cloth, and may even reduce the Tg and thermal decomposition temperature (Td) due to insufficient crosslinking. The preferred range of 700~13,000 g / mol maximizes the density and rigidity of the cured network structure while ensuring good solubility, moderate melt viscosity and excellent compatibility. This supports key properties such as high frequency and low loss (Dk≤3.3@10 GHz, Df≤0.0048), high Tg (≥228°C) and high copper foil peel strength, precisely adapting to the multi-dimensional and stringent requirements of 5G high frequency and high speed copper clad laminates on the resin matrix.

[0067] The number-average molecular weight of the modified polyphenylene ether resin is typically, but not limitingly, 500 g / mol, 3000 g / mol, 5500 g / mol, 8000 g / mol, 10500 g / mol, 13000 g / mol, 15500 g / mol, 18000 g / mol, 20500 g / mol, 23000 g / mol, or 25000 g / mol, or any value in the range of 500 to 25000 g / mol; more preferably, its number-average molecular weight is, for example, 700 g / mol, 900 g / mol, 1100 g / mol, 1300 g / mol, 3300 g / mol, 5300 g / mol, 7300 g / mol, 9300 g / mol, 11300 g / mol, or 13000 g / mol, or any value in the range of 700 to 13000 g / mol.

[0068] Preferably, the modified polyphenylene ether resin has a molecular weight distribution of 1.0 to 2.4.

[0069] The molecular weight distribution of the modified polyphenylene ether resin is typically, but not limitingly, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2 or 2.4, or any value in the range of 1.0 to 2.4.

[0070] Preferably, the crosslinking agent comprises at least one selected from the group consisting of a triallenyl isocyanurate compound, a polyfunctional acrylate compound, a polyfunctional methacrylate compound, a polyfunctional vinyl compound, and a divinylbenzene compound.

[0071] Preferably, the trialnyl isocyanurate compound is at least one of trialnyl isocyanurate, trialnyl cyanurate, trimethylallyl isocyanurate, and trimethylallyl cyanurate.

[0072] Preferably, the multifunctional acrylate compound includes trimethylolpropane triacrylate.

[0073] Preferably, the polyfunctional methacrylate compound includes trimethylolpropane trimethacrylate.

[0074] Preferably, the multifunctional vinyl compound includes at least one of tert-butylstyrene, diallyl isophthalate, and diallyl phthalate.

[0075] Preferably, the filler material includes at least one of aluminum nitride, aluminum borate, magnesium oxide, magnesium carbonate, cubic boron nitride, crystalline silicon dioxide, synthetic silicon dioxide, hollow silicon dioxide, spherical silicon dioxide, fused silicon dioxide, talc, aluminum oxide, barium sulfate, barium titanate, strontium titanate, calcium carbonate, or titanium dioxide.

[0076] The surface of the inorganic filler used in this invention can be treated with a silane coupling agent. The filler treated with the coupling agent exhibits superior compatibility with the resin composition system, further improving the dielectric properties of the composition, while also enhancing moisture resistance and peel strength to copper foil. The silane coupling agent can be selected from silane coupling agents known in the art; this invention further specifies that the silane coupling agent used is a vinyl silane coupling agent, an acrylate-based silane coupling agent, or a methacrylate-based silane coupling agent.

[0077] Preferably, the filler material comprises spherical silica fillers whose surfaces have been treated with vinyl, allyl, or (meth)acrylate silane coupling agents.

[0078] Preferably, the particle size of the filler material is 0.5~5μm.

[0079] Preferably, the initiator includes azobisisobutyronitrile, azobis(2-isopropyl)butyronitrile, azobis(hexamethylene)-butyronitrile, benzoyl peroxide, dimethylbenzoyl peroxide, diisopropyl peroxide, dicumyl peroxide, cyclohexanone peroxide, methyl ethyl ketone peroxide, dicyclohexyl peroxide, benzoic acid peroxide, tert-butyl peroxide, butyl benzoic acid peroxide, tert-butyl peroxide, di-tert-butyl peroxide, dilauroyl peroxide, cumyl peroxide, tert-butyl peroxide, tert-butyl peroxypentanoate, tert-butyl peroxypentanoate, tert-butyl peroxyisobutyrate, tert-butyl peroxide-3,5,5-trimethylhexanoate, tert-butyl peroxyacetate, tert-butyl peroxybenzoate, and 1,1-di-tert-butyl peroxide-3... At least one of the following: 5,5-trimethylcyclohexane, 1,1-di-tert-butylcyclohexane peroxide, 2,2-di(tert-butylperoxide)butane, bis(4-tert-butylcyclohexyl)peroxide, hexadecyl peroxide, tetradecyl peroxide, dipentylhexyl peroxide, diisopropylbenzene peroxide, bis(tert-butylperoxide isopropyl)benzene, 2,5-dimethyl-2,5-di-tert-butylperoxide, 2,5-dimethyl-2,5-di-tert-butylperoxide hexyne, diisopropylbenzene hydrogen peroxide, isopropylbenzene hydrogen peroxide, tert-pentyl hydrogen peroxide, tert-butyl hydrogen peroxide, tert-butyl isopropylbenzene peroxide, tert-butylperoxide-2-ethylhexyl percarbonate, and 4,4-di(tert-butylperoxide)pentanoate.

[0080] Furthermore, the resin composition also includes 0.1 to 2 parts of toughening agent.

[0081] The resin composition also includes a toughening agent, typically but not limitingly, in parts such as 0.1, 0.5, 0.6, 0.8, 1, 1.5, 1.7, 1.8, 1.9 or 2 parts, or any value in the range of 0.1 to 2 parts.

[0082] Preferably, the toughening agent comprises a polystyrene-butadiene copolymer.

[0083] The resin composition is prepared by mixing the raw materials evenly to obtain the resin composition.

[0084] The fifth aspect of the present invention provides the use of the resin composition described herein in the preparation of copper-clad laminates.

[0085] The method for preparing the copper-clad laminate includes the following steps: applying the resin composition as an adhesive onto a glass fiber cloth, drying and curing it to allow the solvent to evaporate, and obtaining a prepreg; stacking the prepreg with copper foil and pressing it to obtain the copper-clad laminate, and using the copper-clad laminate to prepare a circuit board.

[0086] Preferably, the linear speed of the adhesive coating is 8~25m / min; the drying and curing temperature is 110~230℃; the pressing pressure is 70~600 psi, the temperature is 70~240℃, the vacuum degree is 0.02~0.1MPa, the curing time is 50~130min, and the pressing time is 70~200min.

[0087] The linear velocity of the adhesive coating is typically, but not limitingly, for example, 8 m / min, 11 m / min, 14 m / min, 17 m / min, 20 m / min, 23 m / min or 25 m / min, or any value in the range of 8 to 25 m / min.

[0088] The drying and curing temperature is typically, but not limitingly, for example, 110°C, 130°C, 150°C, 170°C, 190°C, 210°C, or 230°C, or any value within the range of 110°C to 230°C.

[0089] The pressure of the compression is typically, but not limitingly, for example, 70 psi, 150 psi, 230 psi, 310 psi, 390 psi, 470 psi, 550 psi or 600 psi, or any value in the range of 70 to 600 psi.

[0090] The pressing temperature, typically but not limitingly, can be, for example, 70°C, 90°C, 110°C, 130°C, 150°C, 170°C, 190°C, 210°C, 230°C, or 240°C, or any value within the range of 70°C to 240°C.

[0091] The vacuum level of the compression is typically, but not limitingly, for example, 0.02 MPa, 0.04 MPa, 0.06 MPa, 0.08 MPa or 0.1 MPa, or any value in the range of 0.02 to 0.1 MPa.

[0092] The curing time, typically but not limitingly, can be 50 min, 70 min, 90 min, 110 min or 130 min, or any value within the range of 50 to 130 min.

[0093] The compression time, typically but not limitingly, can be 70 min, 90 min, 110 min, 130 min, 150 min, 170 min, 190 min, or 200 min, or any value within the range of 70 to 200 min.

[0094] Preferably, the glass cloth-based copper clad laminate can be available in various sizes, such as 36×48, 37×49, 40×48, 40.5×48.5, 41×49, 42.5×48.5, and 43×49.

[0095] Preferably, the fiberglass cloth is grade E and has specifications of 1035, 1078, 1080, 2113, 2116 or 3313.

[0096] In a preferred embodiment of the invention, the copper foil is 1 / 3 oz, Hoz, 1 oz, 2 oz, 3 oz, 4 oz or RTF copper foil.

[0097] Given the advantages of the aforementioned phosphorus-containing flame retardants, better flame retardant options are provided for the preparation of flame-retardant engineering plastics, flame-retardant coatings, flame-retardant adhesives, or flame-retardant resin composites. Furthermore, the resin composition provided by this invention constructs a thermosetting system that integrates intrinsic flame retardancy, low dielectric constant, high heat resistance, and strong interfacial properties, significantly improving copper foil peel strength, reducing moisture absorption expansion rate, and maintaining excellent dielectric consistency at high frequencies. After curing, this composition achieves UL94V-0 flame retardancy, Tg≥228°C, Dk≤3.3@10GHz, Df≤0.0048@10GHz, and a pyrolysis temperature (Td)≥408°C. Moreover, after PCT (120°C / 2h), the 288°C solder pot heat resistance time is >60s, fully meeting the stringent requirements of 5G high-frequency, high-speed PCB substrates for reliability, signal integrity, and green manufacturing.

[0098] The present invention is further illustrated below with specific embodiments and comparative examples. However, it should be understood that these embodiments are merely for illustrative purposes and should not be construed as limiting the invention in any way. Unless otherwise specified, the raw materials used in the embodiments and comparative examples of the present invention were carried out under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0099] Information on the raw materials used in the embodiments and comparative examples of this invention is shown in Table 1.

[0100] Table 1

[0101] Example 1 This embodiment provides a phosphorus-containing flame retardant, and the specific preparation method is as follows: Under nitrogen protection, 100g of styrene-butadiene-styrene block copolymer R181 was added to a 1L three-necked flask, 450g of toluene was added, the temperature was raised to 80℃ and stirred to dissolve, then 7.2g of DOPO and 0.29g of BPO were added, the temperature was raised to 100℃ and reacted for 8h. After the reaction was completed, the product was poured into excess ethanol to precipitate, filtered and vacuum dried to constant weight to obtain product D1 with a grafting rate of about 5%.

[0102] Example 2 This embodiment provides a phosphorus-containing flame retardant, and the specific preparation method is as follows: Under nitrogen protection, 100g of styrene-butadiene-styrene block copolymer R100 is added to a 1L three-necked flask, 480g of toluene is added, and the mixture is heated to 85°C to dissolve. Then, 8.1g of DOPO and 0.24g of AIBN are added, and the mixture is heated to 95°C to react for 9 hours. The product is precipitated with ethanol, filtered, and vacuum dried to obtain product D2 with a grafting rate of about 5%.

[0103] Example 3 This embodiment provides a phosphorus-containing flame retardant, and the specific preparation method is as follows: Under nitrogen protection, 100g of Nisso-SBS is added to a 1L three-necked flask, 420g of toluene is added, and the mixture is heated to 75°C to dissolve. Then, 5.9g of DOPO and 0.18g of BPO are added, and the mixture is heated to 105°C to react for 7 hours. The product is precipitated with ethanol, filtered, and vacuum dried to obtain product D3 with a grafting rate of about 5%.

[0104] Example 4 This embodiment provides a phosphorus-containing flame retardant, and the specific preparation method is as follows: Under nitrogen protection, 100g of styrene-butadiene-styrene block copolymer R181 was added to a 1L three-necked flask, 450g of toluene was added, the temperature was raised to 80℃ and stirred to dissolve, then 14.5g of DOPO and 0.58g of BPO were added, the temperature was raised to 100℃ and reacted for 8h. After the reaction was completed, the product was poured into excess ethanol to precipitate, filtered and vacuum dried to constant weight to obtain product D4 with a grafting rate of about 10%.

[0105] Example 5 This embodiment provides a phosphorus-containing flame retardant, and the specific preparation method is as follows: Under nitrogen protection, 100g of styrene-butadiene-styrene block copolymer R181 was added to a 1L three-necked flask, 450g of toluene was added, the temperature was raised to 80℃ and stirred to dissolve, then 4.3g of DOPO and 0.17g of BPO were added, the temperature was raised to 100℃ and reacted for 8h. After the reaction was completed, the product was poured into excess ethanol to precipitate, filtered and vacuum dried to constant weight to obtain product D5 with a grafting rate of about 3%.

[0106] Example 6 This embodiment provides a phosphorus-containing flame retardant, and the specific preparation method is as follows: Under nitrogen protection, 100g of styrene-butadiene-styrene block copolymer R181 was added to a 1L three-necked flask, 450g of toluene was added, the temperature was raised to 80℃ and stirred to dissolve, then 7.5g of DPPO and 0.30g of BPO were added, the temperature was raised to 100℃ and reacted for 8h. After the reaction was completed, the product was poured into excess ethanol to precipitate, filtered and vacuum dried to constant weight to obtain product D6 with a grafting rate of about 5%.

[0107] Comparative Example 1 This comparative example provides a flame retardant, and the specific preparation method is as follows: Under nitrogen protection, 100g of B-2000 polybutadiene was added to a 1L three-necked flask, 450g of toluene was added, the temperature was raised to 80℃ and stirred to dissolve, then 7.5g of DOPO and 0.23g of BPO were added, the temperature was raised to 100℃ and reacted for 8h. After the reaction was completed, the product was poured into excess ethanol to precipitate, filtered and vacuum dried to constant weight to obtain product X1 with a grafting rate of about 5%.

[0108] Comparative Example 2 This comparative example provides a styrene-butadiene-styrene block copolymer R181.

[0109] Examples 7-12 This embodiment provides a resin composition comprising 80g of modified polyphenylene ether resin SA9000, 12g of triallyl isocyanurate resin STR6400, 80g of spherical silica SP0045, 6g of polystyrene-butadiene copolymer B3000, 1.5g of peroxide initiator 25B, and 80g of flame retardants D1-D6 provided in Examples 1-6.

[0110] Example 13 This embodiment provides a resin composition that differs from Example 7 in that modified polyphenylene ether resin OPE-2ST is used instead of modified polyphenylene ether resin SA9000. All other raw materials are the same as in Example 7 and will not be described again here.

[0111] Comparative Example 3 This comparative example provides a resin composition that differs from Example 7 in that product X1 from Comparative Example 1 is used instead of D1, and modified polyphenylene ether resin OPE-2ST is used instead of modified polyphenylene ether resin SA9000. All other raw materials are the same as in Example 7 and will not be described again here.

[0112] Comparative Example 4 This comparative example provides a resin composition that differs from Example 7 in that it uses the styrene-butadiene-styrene block copolymer R181 from Comparative Example 2 instead of D1. All other raw materials are the same as in Example 7 and will not be described again here.

[0113] Comparative Example 5 This comparative example provides a resin composition that differs from Example 7 in that D1 is removed and replaced with 74.6g of styrene-butadiene-styrene block copolymer R181 and 5.4g of DOPO. All other raw materials are the same as in Example 7 and will not be described again here.

[0114] Test case The resin compositions obtained in the examples and comparative examples were used as adhesives and applied to fiberglass cloth at a rate of 15 m / min. The cloth was then dried and cured at 200°C for 120 min to allow the solvent to evaporate, resulting in a prepreg. The prepreg was then stacked with copper foil and pressed under a vacuum of 0.02 MPa, 240°C, and 100 psi for 200 min to obtain a copper-clad laminate sample.

[0115] The following tests were performed on the copper-clad laminate samples: (a) Glass transition temperature (Tg): The peak temperature of Tanδ is determined by dynamic mechanical analysis (DMA) and is taken as the glass transition temperature.

[0116] (ii) Peel strength (PS): The peel strength of the sample was tested using a universal tensile testing machine in accordance with the standard IPC-TM-650-2.4.8.

[0117] (III) 288℃ heat resistance test (T288): Place an 8mm×8mm copper foil substrate on a thermomechanical analyzer (TMA), raise the temperature from room temperature to 288℃ at a heating rate of 10℃ / min and maintain it at 288℃, observe the size change of the sample and record the time when the plate bursts after 288℃.

[0118] (iv) Coefficient of thermal expansion: The coefficient of thermal expansion of the sample shall be determined using a TMA instrument in accordance with the standard specified in IPC-TM-6502.4.24; (v) Dielectric constant (Dk) and dielectric loss factor (Df): The test methods for dielectric constant and dielectric loss factor shall be in accordance with the test methods specified in IPC-TM-6502.5.5.9; (vi) Flame retardancy: Sample test pieces measuring 130mm × 12.5mm were taken, and according to UL94 standard, two burning tests were conducted on each of the five test pieces. Flame retardancy was evaluated by the sum of the burning durations during these tests. (vii) Decomposition temperature (Td): Select a square sample with dimensions of 6.35mm×6.35mm and a minimum sample weight of 30mg. Bake at 110±2℃ for 24 hours and cool to room temperature in a desiccator. Use a thermogravimetric analyzer (TGA) to increase the temperature from room temperature to 450℃ at a rate of 10℃ / min. Record the percentage of weight loss of the sample as the temperature increases. The temperature at which the weight loss is 5% is reported as Td. (viii) PCT: The samples were subjected to a steaming test using a pressure cooker. After the plates were steamed continuously at 0.105 MPa and 120°C for 120 min, they were immersed in a tin furnace at 288°C to observe the delamination and bubbling time. Samples with a delamination time of less than 5 min were evaluated as ×, and samples with a delamination time of more than 5 min but less than 10 min were evaluated as ○.

[0119] The test results are summarized in Table 2.

[0120] Table 2

[0121] As shown in Table 2, the phosphorus-containing flame retardants D1 to D6 used in Examples 7 to 12 all achieved UL94V0 flame retardancy, with Tg between 228℃ and 241℃, copper foil peel strength between 0.72 and 0.87 N / cm, tin furnace heat resistance time at 288℃ reaching 60 minutes, thermal decomposition temperature Td between 408℃ and 421℃, dielectric constant Dk stable between 3.1 and 3.3, dielectric loss factor Df controlled between 0.0035 and 0.0048, and PCT test results all at 000, indicating excellent interlayer bonding stability and anti-delamination ability under high temperature and high humidity conditions. Among them, Example 7 showed the best performance, with Tg reaching 241℃, peel strength of 0.87 N / cm, Df as low as 0.0035, and Td as high as 421℃, exhibiting the most outstanding overall performance.

[0122] In contrast, Comparative Example 3, which used X1 instead of the phosphorus-containing flame retardant of this invention, saw its Tg decrease to 195°C, peel strength drop to 0.54 N / cm, Df increase to 0.0062, and PCT result degrade to ×O×. The heat resistance time of 288 was only 17 minutes, indicating a lack of rigid support from the styrene hard segments and the ability to regulate the microphase separation structure, leading to significant deterioration in thermal stability, interfacial adhesion, and resistance to damp heat. Comparative Example 4, which directly used unmodified R181, increased its Tg to 225°C, but its flame retardant rating dropped to V2, the heat resistance time of 288 was only 15 minutes, and the PCT was O15, indicating that the system lost its intrinsic flame retardant ability and long-term thermal stability due to the absence of covalently anchored phosphorus units. Comparative Example 5 uses a physical blending method to simply mix DOPO and SBS. Although it achieves the V2 flame retardant level, the peel strength further decreases to 0.59 N / cm, Df rebounds to 0.0039, and the PCT result is 25, showing a clear tendency to delamination. This confirms that the migration and precipitation of small molecule DOPO seriously weakens the interfacial compatibility and the integrity of the cured network.

[0123] In Example 13, after replacing the polyphenylene oxide with styrene-terminated polyphenylene oxide OPE-2ST, the Tg dropped to 219°C, the peel strength was only 0.61 N / cm, the Df increased to 0.0052, the flame retardancy rating degraded to V, and the Td dropped to 341°C. This indicates that the highly reactive double bonds and polar groups introduced by the acrylate-modified polyphenylene oxide SA9000 play an irreplaceable role in synergistic crosslinking, enhancing the interfacial effect of fillers, and improving network density.

[0124] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A phosphorus-containing flame retardant, characterized in that, The phosphorus-containing flame retardant is a modified phosphorus-containing styrene-butadiene-styrene block copolymer; The chemical structural formula of the modified phosphorus-containing styrene-butadiene-styrene block copolymer is: ; Where a > 1, b is an integer between 15 and 75, c is an integer between 15 and 75, and d > 1; M is a phosphorus-containing group.

2. The phosphorus-containing flame retardant according to claim 1, characterized in that, The phosphorus-containing groups include , , , , , , or ; Preferably, the phosphorus-containing flame retardant has the following structural formula: , .

3. The phosphorus-containing flame retardant according to claim 1 or 2, characterized in that, The chemical structural formula of the styrene-butadiene-styrene block copolymer is: ; Where a > 1, b is an integer between 15 and 75, c is an integer between 15 and 75, and d > 1; Preferably, in the phosphorus-containing flame retardant, the grafting rate of the phosphorus-containing groups is 3~12wt%; Preferably, the number average molecular weight of the phosphorus-containing flame retardant is 4000~35000 g / mol, more preferably 7000~25000 g / mol; Preferably, the molecular weight distribution of the phosphorus-containing flame retardant is 1.0 to 1.

2.

4. A method for synthesizing a phosphorus-containing flame retardant according to any one of claims 1 to 3, characterized in that, Under inert gas protection, styrene-butadiene-styrene block copolymer is dissolved in a solvent, and then a phosphorus-containing compound and a thermal initiator are added to carry out the reaction. After the reaction is completed, the phosphorus-containing flame retardant is obtained by ethanol precipitation, filtration and drying.

5. The synthesis method according to claim 4, characterized in that, The phosphorus-containing compound includes at least one of DOPO and DPPO; Preferably, the amount of the phosphorus-containing compound added is 4-15% of the mass of the styrene-butadiene-styrene block copolymer; Preferably, the amount of solvent added is 4 to 6 times the mass of the styrene-butadiene-styrene block copolymer; Preferably, the solvent includes at least one of toluene, xylene, butanone, cyclohexanone, propylene glycol methyl ether acetate, and dimethylformamide; Preferably, the reaction temperature is 90~110℃ and the time is 6~10h.

6. The use of a phosphorus-containing flame retardant according to any one of claims 1 to 3 in the preparation of flame-retardant engineering plastics, flame-retardant coatings, flame-retardant adhesives or flame-retardant resin composites.

7. A resin composition, characterized in that, By weight, it includes 80-150 parts of phosphorus-containing flame retardant, 50-100 parts of modified polyphenylene ether resin, 15-25 parts of crosslinking agent, 50-100 parts of filler material, and 0.2-3 parts of initiator; The phosphorus-containing flame retardant is the phosphorus-containing flame retardant according to any one of claims 1 to 3.

8. The resin composition according to claim 7, characterized in that, The modified polyphenylene ether resin includes acrylate and / or styrene-terminated polyphenylene ether resins; Preferably, the number-average molecular weight of the modified polyphenylene ether resin is 500~25000 g / mol; Preferably, the crosslinking agent comprises at least one selected from the group consisting of a triallenyl isocyanurate compound, a polyfunctional acrylate compound, a polyfunctional methacrylate compound, a polyfunctional vinyl compound, and a divinylbenzene compound; Preferably, the trialenyl isocyanurate compound is at least one of trialenyl isocyanurate, trialenyl cyanurate, trimethylallyl isocyanurate, and trimethylallyl cyanurate. Preferably, the multifunctional acrylate compound includes trimethylolpropane triacrylate; Preferably, the polyfunctional methacrylate compound includes trimethylolpropane trimethacrylate; Preferably, the multifunctional vinyl compound includes at least one of tert-butylstyrene, diallyl isophthalate, and diallyl phthalate. Preferably, the filler material includes at least one of aluminum nitride, aluminum borate, magnesium oxide, magnesium carbonate, cubic boron nitride, crystalline silicon dioxide, synthetic silicon dioxide, hollow silicon dioxide, spherical silicon dioxide, fused silicon dioxide, talc, aluminum oxide, barium sulfate, barium titanate, strontium titanate, calcium carbonate, or titanium dioxide. Preferably, the filler material comprises spherical silica fillers whose surfaces have been treated with vinyl, allyl, or (meth)acrylate silane coupling agents; Preferably, the particle size of the filler material is 0.5~5μm; Preferably, the initiator includes azobisisobutyronitrile, azobis(2-isopropyl)butyronitrile, azobis(hexamethylene)-butyronitrile, benzoyl peroxide, dimethylbenzoyl peroxide, diisopropyl peroxide, dicumyl peroxide, cyclohexanone peroxide, methyl ethyl ketone peroxide, dicyclohexyl peroxide, benzoic acid peroxide, tert-butyl peroxide, butyl benzoic acid peroxide, tert-butyl peroxide, di-tert-butyl peroxide, dilauroyl peroxide, cumyl peroxide, tert-butyl peroxide, tert-butyl peroxypentanoate, tert-butyl peroxypentanoate, tert-butyl peroxyisobutyrate, tert-butyl peroxide-3,5,5-trimethylhexanoate, tert-butyl peroxyacetate, tert-butyl peroxybenzoate, and 1,1-di-tert-butyl peroxide-3... At least one of the following: 5,5-trimethylcyclohexane, 1,1-di-tert-butylcyclohexane peroxide, 2,2-di(tert-butylperoxide)butane, bis(4-tert-butylcyclohexyl)peroxide, hexadecyl peroxide, tetradecyl peroxide, dipentylhexyl peroxide, diisopropylbenzene peroxide, bis(tert-butylperoxide isopropyl)benzene, 2,5-dimethyl-2,5-di-tert-butylperoxide, 2,5-dimethyl-2,5-di-tert-butylperoxide hexyne, diisopropylbenzene hydrogen peroxide, isopropylbenzene hydrogen peroxide, tert-pentyl hydrogen peroxide, tert-butyl hydrogen peroxide, tert-butyl isopropylbenzene peroxide, tert-butylperoxide-2-ethylhexyl percarbonate, and 4,4-di(tert-butylperoxide)pentanoate.

9. The resin composition according to claim 7 or 8, characterized in that, The resin composition further includes 0.1 to 2 parts of toughening agent; Preferably, the toughening agent comprises a polystyrene-butadiene copolymer.

10. The use of the resin composition according to any one of claims 7 to 9 in the preparation of copper-clad laminates.

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