A flame retardant epoxy resin composition and its preparation method, application and product

Abstract

The present invention provides a flame-retardant epoxy resin composition, its preparation method, application, and product, belonging to the field of polymer materials technology. The flame-retardant epoxy resin composition comprises an epoxy resin, a curing agent, and an inorganic nitride. The epoxy resin is synthesized in a one-step process from a phosphorus-containing compound and epichlorohydrin, or from a phosphorus-containing compound, epichlorohydrin, and a phenolic hydroxyl-containing compound. The curing agent and inorganic nitride significantly enhance the epoxy resin's resistance to moisture and heat while maintaining flame retardancy, making it suitable for a wider range of applications in prepregs, metal-clad laminates, or printed circuit boards.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials and relates to a flame retardant epoxy resin composition and a preparation method, application and product thereof. Background Art

[0002] Epoxy resin (EP) can be used as coatings, casting materials, molding materials, adhesives, and laminates due to its good formability, adhesion, electrical properties, and mechanical properties. It is widely used in fields such as packaging materials for aircraft and large-scale integrated circuits, insulation materials for copper-clad laminates, coatings for steel and wood, adhesives for mechanical and civil construction, and even coatings on the inner walls of food cans and metal anti-corrosion electrophoretic coatings.

[0003] EP is a linear thermoplastic resin that does not harden on its own. Only when a curing agent crosslinks its linear structure into a network or bulk structure does it exhibit good performance. Its performance largely depends on the curing agent. Furthermore, EP readily absorbs water, which can deteriorate its thermal, electrical, and mechanical properties, limiting its use. Furthermore, EP materials that have absorbed water molecules can experience weld cracking due to the vaporization and expansion of these molecules. Therefore, when EP is used in electronic packaging and other applications, it must possess high purity, low shrinkage, excellent heat resistance, low moisture absorption, and rapid curing.

[0004] The biggest disadvantage of epoxy resin is its flammability. Phosphorus is an element that easily forms compounds. POC bonds or PC bonds have good stability. Phosphorus-based flame retardant systems can increase the carbonization rate of materials, especially oxygen-containing polymers, during combustion. The resulting carbon layer is resistant to oxidation. At the same time, since phosphoric acid can cover the carbon layer, it can prevent ignition.

[0005] Chinese invention patent application CN110105539A discloses the use of a phosphorus-containing compound in the one-step synthesis of a flame-retardant epoxy resin, a flame-retardant epoxy resin, a preparation method, and an application thereof. The flame-retardant epoxy resin is synthesized in a one-step process from a phosphorus-containing compound and epichlorohydrin. The phosphorus-containing compound can be located not only at the end group of the flame-retardant epoxy resin, but also on the main chain of the flame-retardant epoxy resin, thereby making the flame-retardant epoxy resin have not only excellent flame retardant properties, but also excellent moisture-resistant and heat-resistant stability, thereby effectively meeting the high-frequency and high-speed usage requirements of existing electronic products.

[0006] However, as the demand for high-speed and multifunctional information processing in electronic products continues to increase, the frequency of application is also increasing, and the flame retardancy and moisture-heat stability of resins are also becoming increasingly demanding. Therefore, it is necessary to further study its curing agent and additive system to improve its comprehensive performance. Summary of the Invention

[0007] The inventors of the present invention have discovered that a flame-retardant epoxy resin synthesized from a phosphorus-containing compound and epichlorohydrin by a one-step process, after being compounded with a suitable curing agent and a modification aid, particularly an inorganic nitride, further improves its moisture and heat resistance while maintaining flame retardancy. Therefore, the resulting flame-retardant epoxy resin composition has a wider range of applications in prepregs, metal foil-clad laminates, or printed circuit boards.

[0008] One of the technical solutions of the present invention is:

[0009] Provided is a flame-retardant epoxy resin composition, comprising: an epoxy resin, a curing agent, and an inorganic nitride; the epoxy resin is synthesized from a phosphorus-containing compound and epichlorohydrin by a one-step process, wherein the phosphorus-containing compound has the following structure:

[0010]

[0011] Formula I

[0012] Wherein, R1, R2, R3 and R4 are independently selected from hydrogen atom, aliphatic hydrocarbons having 1-20 carbon atoms or their derivatives, alicyclic hydrocarbons having 3-20 carbon atoms or their derivatives, unsaturated aliphatic hydrocarbons having 2-20 carbon atoms or their derivatives, aromatic hydrocarbons having 6-20 carbon atoms or their derivatives.

[0013] The phosphorus in the phosphorus-containing compound in the phosphorus-containing flame-retardant epoxy resin selected by the present invention is wrapped by a condensed ring structure, which provides the composition with lower water absorption and higher structural stability; in addition, the flame-retardant epoxy resin has a higher P content, which also provides the composition with higher flame retardant properties. Experiments have found that when it is used with a curing agent and an auxiliary agent, especially an inorganic nitride as an auxiliary agent, it can improve moisture and heat resistance while ensuring its own flame retardant properties.

[0014] In some preferred embodiments of the present invention, the phosphorus content in the epoxy resin is 0.1-7.2 wt %; and the epoxy equivalent weight of the flame retardant epoxy resin is 180-2000 g / mol.

[0015] Typically, but not limiting, the phosphorus content in the flame retardant epoxy resin is 0.1 wt%, 0.2 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, 1.5 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt% or 7.2 wt%.

[0016] Typically, but not limiting, the epoxy equivalent weight of the flame retardant epoxy resin is 180 g / mol, 200 g / mol, 250 g / mol, 300 g / mol, 400 g / mol, 500 g / mol, 800 g / mol, 1000 g / mol, 1200 g / mol, 1500 g / mol, 1800 g / mol or 2000 g / mol.

[0017] Specifically, the epoxy resin of the present invention is prepared using the technical solution disclosed in patent application CN201910499212.1, synthesized in a one-step process from a phosphorus-containing compound (structure shown in Formula I) and epichlorohydrin. In some specific embodiments of the present invention, the phosphorus-containing compound, epichlorohydrin, and an optional hydroxyl-containing phenolic compound are uniformly mixed in a solvent and subjected to a one-step polymerization reaction under alkaline conditions. The polymerization reaction temperature is 50-100°C, and the reaction system pH is 8-14.

[0018] Furthermore, the flame retardant epoxy resin composition contains, by weight, 50-200 parts of epoxy resin, 10-60 parts of curing agent, and 100-200 parts of inorganic nitride.

[0019] Preferably, the flame retardant epoxy resin composition contains, by weight, 80-100 parts of epoxy resin, 20-40 parts of curing agent and 120-150 parts of inorganic nitride.

[0020] Furthermore, the curing agent is an amine curing agent, an amide curing agent and / or an imidazole curing agent.

[0021] Preferably, the curing agent is an amine curing agent or an imidazole curing agent.

[0022] More preferably, the weight ratio of the amine curing agent to the imidazole curing agent is 1-5:0.05-0.2.

[0023] Typically, but not limited to, the weight ratio of the amine curing agent to the imidazole curing agent is 1:0.2, 1:0.1, 1:0.05, 2:0.05, 3:0.05, 4:0.05, or 5:0.05.

[0024] Furthermore, the amine curing agent is specifically selected from one or more of m-phenylenediamine, m-phenylenediamine, diaminodiphenylmethane, diaminodiphenyl sulfone, m-aminomethylamine, phenylenediamine and methylenebisphenylenediamine.

[0025] Furthermore, the amide curing agent is selected from polyamide 650 and / or polyamide 651.

[0026] Furthermore, the imidazole curing agent is specifically selected from one or more of imidazole, 2-methylimidazole, 2-ethylimidazole and 2-ethyl-4-methylimidazole.

[0027] Furthermore, the inorganic nitride is selected from one or more of silicon nitride, aluminum nitride and boron nitride.

[0028] Furthermore, the flame retardant epoxy resin composition further contains: a lanthanide compound.

[0029] Preferably, the lanthanide compound is specifically selected from one or more of lanthanum chloride, lanthanum oxide or lanthanum hydroxide.

[0030] More preferably, the mass ratio of the lanthanide compound to the inorganic nitride is 0.1-5:1; further preferably 0.1-1:1.

[0031] Typically, but not limited to, the mass ratio of the lanthanide compound to the inorganic nitride is 0.1:1, 0.2:1, 0.5:1, 0.8:1, 1:1, 2:1, 3:1, 4:1, or 5:1.

[0032] The second technical solution of the present invention is:

[0033] Provided is a method for preparing any of the above-mentioned flame-retardant epoxy resin compositions, comprising the following steps:

[0034] (1) dissolving epoxy resin, curing agent and inorganic nitride in a solvent;

[0035] (2) With or without adding lanthanide compounds, the product is obtained by melting.

[0036] The third technical solution of the present invention is:

[0037] Provided is the use of any of the above-mentioned flame-retardant epoxy resin compositions or the flame-retardant epoxy resin composition prepared by any of the above-mentioned preparation methods in prepregs, metal foil-clad laminates or printed circuit boards.

[0038] The fourth technical solution of the present invention is:

[0039] Provided is a product comprising any of the above-mentioned flame-retardant epoxy resin compositions or a flame-retardant epoxy resin composition prepared by any of the above-mentioned preparation methods, wherein the product is any of a prepreg, a metal foil-clad laminate, or a printed circuit board.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] (1) The composition of the present invention is simple in composition and adopts phosphorus-containing epoxy resin, which itself has good flame retardancy and moisture-heat resistance. By combining the auxiliary nitride with the curing agent, the flame-retardant epoxy resin composition obtained has better comprehensive performance than other auxiliary agents;

[0042] (2) Further, by selecting a curing agent, in particular, using an imidazole curing agent, which acts as a curing agent on the one hand and a curing accelerator for an amine curing agent on the other hand, the curing time of the composition can be significantly improved when the amount of the imidazole curing agent is extremely low, thereby obtaining a cured product with less ionic impurities and excellent moisture and heat resistance, which has a significant effect on improving the performance of the composition;

[0043] (3) The inventors of the present invention have also found that adding rare earth compounds, especially lanthanide compounds, to the system can further improve the moisture and heat resistance of the composition;

[0044] (4) The epoxy curing system of the epoxy resin composition prepared by the present invention has good flame retardant properties and other excellent properties of epoxy resin, such as moisture and heat resistance, and can be widely used in prepregs, laminates, metal foil-clad laminates or printed circuit boards. It also has excellent dielectric properties and has greater application value in printed circuit boards. DETAILED DESCRIPTION

[0045] The embodiments of the present invention will be described in detail below with reference to the examples, but those skilled in the art will appreciate that the following examples are intended only to illustrate the present invention and should not be construed as limiting the scope of the invention. Where specific conditions are not specified in the examples, conventional conditions were used. Where the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0046] Flame-retardant epoxy resin A used in this embodiment was prepared using the method of Example 2 of patent application CN201910499212.1; the epoxy resin had an epoxy equivalent weight of 260 g / mol and a phosphorus content of 7.0 wt%. Flame-retardant epoxy resin B was prepared using the method of Comparative Example 1 of patent application CN201910499212.1; the epoxy resin had an epoxy equivalent weight of 310 g / mol and a phosphorus content of 2.5 wt%.

[0047] Examples 1-10

[0048] Flame-retardant epoxy resin prepregs and laminates were prepared according to the formulation in Table 1. The specific steps are as follows:

[0049] (1) Weigh each component according to the formula in Table 1 and dissolve them in a mixed solvent of N-methylpyrrolidone and cyclohexanone (1:1 V / V) to form a varnish;

[0050] (2) impregnating a 125 μm thick glass fiber cloth prepreg (model: 7628) with the varnish, heating to 170°C, and drying for 5 minutes to obtain prepregs 1-10;

[0051] (3) Three more impregnated pieces were overlapped, and a 20 μm thick copper foil (purchased from Kunshan Luzhifa Electronic Technology Co., Ltd.) was added to the upper and lower surfaces of the three overlapping pieces. The laminates 1-10 were cured at 180°C for 2 hours using a vacuum hot press.

[0052] Table 1 Flame retardant epoxy resin composition formula

[0053]

[0054] The test results of the properties of the prepregs and laminates prepared in the above examples are shown in Table 2.

[0055] Table 2 Performance indicators of prepregs 1-10 and laminates 1-10

[0056]

[0057] Description: (1) Flame retardancy: UL94 evaluation standard for flammability test of plastic materials is used; (2) Glass transition temperature: Differential scanning calorimeter is used, test conditions: room temperature - 240°C, heating rate 20°C / min; (3) Peel strength: Measured according to JIS C 6481 specification; (4) Moisture and heat resistance: After absorbing water in the vapor phase at 121°C and 100% humidity for 6 hours, observe its quality changes, bubbles and peeling.

[0058] Comparative Example 1

[0059] 100g of flame-retardant epoxy resin, 180g of phenolic epoxy resin (model NPPN638, produced by Nan Ya Plastics, Taiwan, China), 120g of silica and dicy (chemical name dicyandiamide, CAS: 461-58-5, Ningxia Darong Industrial Group Co., Ltd.) prepared by the method of Example 2 of patent application CN201910499212.1, wherein the amount of dicy is 0.6eq of the total amount of flame-retardant epoxy resin and phenolic epoxy resin, and a prepreg 11 and a laminate 11 are prepared according to the preparation method of Example 1.

[0060] Comparative Example 2

[0061] Compared with composition 3, the only difference is that epoxy resin B is used instead of epoxy resin A in an equal amount. A prepreg 12 and a laminate 12 are prepared according to the preparation method of Example 1.

[0062] Comparative Example 3

[0063] Compared with composition 3, the only difference is that silicon nitride is replaced by an equal amount of silicon oxide. A prepreg 13 and a laminate 13 are prepared according to the preparation method of Example 1.

[0064] Comparative Example 4

[0065] Compared with composition 8, the only difference is that lanthanum oxide is replaced by an equal amount of cerium oxide. A prepreg 14 and a laminate 14 are prepared according to the preparation method of Example 1.

[0066] Comparative Example 5

[0067] Compared with composition 8, the only difference is the amount of each component in the composition, specifically: 100 parts of epoxy resin, 180 parts of diaminodiphenylmethane, 120 parts of silicon carbide, and 168 parts of lanthanum oxide (the same ratio of flame retardant epoxy resin, phenolic epoxy resin, silica and dicy as in Comparative Example 1). Prepreg 15 and laminate 15 were prepared according to the preparation method of Example 1.

[0068] Table 3 Performance indicators of prepregs 3, 8, 11-15 and laminates 3, 8, 11-15

[0069]

[0070] Note: The relevant performance testing methods are the same as those in Table 2.

[0071] As can be seen from the above table, the composition obtained by combining the phosphorus-containing flame-retardant epoxy resin of the present invention with a curing agent and an inorganic nitride auxiliary agent has excellent flame retardancy, while also having improved moisture and heat resistance and bonding strength with copper foil. Furthermore, through the optimization of curing agent type and dosage, the introduction and dosage adjustment of lanthanide compounds, the moisture and heat resistance of the composition is further improved, resulting in excellent overall performance.

[0072] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A flame retardant epoxy resin composition, characterized in that: The flame retardant epoxy resin composition comprises, by weight, 80-100 parts of epoxy resin, 20-60 parts of curing agent and 100-150 parts of inorganic nitride; The epoxy resin is synthesized from a phosphorus-containing compound and epichlorohydrin by a one-step method. The structure of the phosphorus-containing compound is as follows: The curing agent is an amine curing agent and an imidazole curing agent; the weight ratio of the amine curing agent to the imidazole curing agent is 3.8-5:0.

2.

2. The flame retardant epoxy resin composition according to claim 1, wherein: The amine curing agent is specifically selected from one or more of m-phenylenediamine, m-phenylenediamine, diaminodiphenylmethane, diaminodiphenyl sulfone, m-aminomethylamine, phenylenediamine and methylenebisphenylenediamine; the imidazole curing agent is specifically selected from one or more of imidazole, 2-methylimidazole, 2-ethylimidazole and 2-ethyl-4-methylimidazole.

3. The flame retardant epoxy resin composition according to claim 1, wherein: The inorganic nitride is selected from one or more of silicon nitride, aluminum nitride and boron nitride.

4. Use of the flame retardant epoxy resin composition according to any one of claims 1 to 3 in prepregs, metal foil-clad laminates or printed circuit boards.

5. A product comprising the flame retardant epoxy resin composition according to any one of claims 1 to 3, characterized in that: The product is any one of a prepreg, a metal foil clad laminate or a printed circuit board.

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