Halogen-free flame-retardant epoxy resin composition for copper-clad plate as well as preparation method and application thereof

Abstract

The invention relates to the field of copper-clad plates, in particular to a halogen-free flame-retardant epoxy resin composition for a copper-clad plate as well as a preparation method and application of the halogen-free flame-retardant epoxy resin composition. The halogen-free flame-retardant epoxy resin composition for the copper-clad plate at least comprises halogen-free epoxy resin, a composite filler and an organic solvent composition in a mass ratio of (50-65): (20-30): (10-18). The epoxy resin composition finally prepared in the invention can further obtain excellent heat resistance, moisture resistance, mechanical strength and electrical properties while keeping flame retardance, the problem of performance contradiction in the prior art is solved, and a copper-clad plate material prepared from the epoxy resin composition is excellent in use effect.

Description

Technical Field

[0001] The present application relates to the field of copper clad laminates, and more specifically, to a halogen-free flame retardant epoxy resin composition for copper clad laminates, its preparation method and applications. Background Art

[0002] As the core substrate of printed circuit boards (PCBs), copper clad laminates (CCLs) directly determine the reliability, heat resistance and safety of electronic devices. In recent years, due to its excellent adhesiveness, chemical resistance and processability, epoxy resin has become the mainstream choice for the matrix resin of copper clad laminates. However, halogen-containing flame retardants (such as brominated epoxy resin) are often added to traditional epoxy resin systems to meet the UL94 V-0 flame retardant requirements. With the strict restrictions of environmental protection regulations on halogen compounds, the development of high-performance halogen-free flame retardant epoxy resin systems has become an important research direction in the field of copper clad laminates.

[0003] Currently, halogen-free flame retardant technologies mainly rely on the synergistic effects of phosphorus-based, nitrogen-based, silicon-based flame retardants and inorganic fillers (such as aluminum hydroxide, magnesium hydroxide, etc.). For example, Patent CN102051026B proposes a halogen-free flame retardant epoxy resin composition, which adopts a system containing phosphorus-containing epoxy resin, a large amount of fillers and solvents. On the premise of ensuring halogen-free, it effectively improves the adhesiveness, flame retardancy and flexibility of the resin, and can maintain good peel strength and heat resistance when preparing copper clad laminates. However, at the same time, this type of system is prone to a significant increase in viscosity and an increase in dielectric loss. Moreover, although inorganic fillers are environmentally friendly and low-cost, a high filling amount will deteriorate the mechanical properties and processing fluidity of the material. In addition, some halogen-free systems have problems such as insufficient resistance to heat and humidity and a decrease in thermal stability at high temperatures, which affect the long-term reliability of copper clad laminates in high-temperature and high-humidity environments.

[0004] On the other hand, as described in Patent CN102051026B, when the existing technology uses this type of epoxy resin system, a large amount of ketone solvents and DMF solvents are used, resulting in higher requirements for post-treatment and recycling, a large increase in cost, and poor environmental friendliness of such a large amount of solvents. There is also a balance contradiction between flame retardancy and comprehensive performance, resulting in the loss of electrical properties and a significant decrease in mechanical strength while maintaining excellent flame retardancy of the copper clad laminate. Summary of the Invention

[0005] As described above, how to balance the comprehensive properties of the epoxy resin composition for copper clad laminates while maintaining excellent flame retardant properties, especially maintaining good electrical properties and mechanical strength, has become the focus of research and development for those skilled in the art. At the same time, with the continuous development of printed circuit boards, new requirements have been put forward for the heat resistance stability, moisture resistance and processing performance of copper clad laminates. Therefore, in order to effectively solve the above problems, the applicant proposes a halogen-free flame retardant epoxy resin composition for copper clad laminates and its preparation method. The finally obtained epoxy resin composition can not only maintain the flame retardant properties, but also further obtain excellent heat resistance, moisture resistance, mechanical strength and electrical properties, overcoming the performance contradiction problems existing in the prior art, and the copper clad laminate material prepared therefrom has excellent use effects.

[0006] A halogen-free flame retardant epoxy resin composition for copper clad laminates, which at least comprises a halogen-free epoxy resin, a composite filler and an organic solvent composition.

[0007] In a preferred embodiment, the mass ratio of the halogen-free epoxy resin, the composite filler and the organic solvent composition is (50-65):(20-30):(10-18).

[0008] In a preferred embodiment, the mass ratio of the halogen-free epoxy resin, the composite filler and the organic solvent composition is (55-63):(25-28):(12-16).

[0009] In a preferred embodiment, the halogen-free epoxy resin is a phosphorus-containing DOPO type epoxy resin.

[0010] In a preferred embodiment, the phosphorus content of the phosphorus-containing DOPO type epoxy resin is 1-3.5 wt%.

[0011] In a preferred embodiment, the phosphorus content of the phosphorus-containing DOPO type epoxy resin is 1.5-3 wt%.

[0012] In a preferred embodiment, the viscosity of the phosphorus-containing DOPO type epoxy resin is 400-800 mPa·s at 25 °C.

[0013] In a preferred embodiment, the viscosity of the phosphorus-containing DOPO type epoxy resin is 500-600 mPa·s at 25 °C.

[0014] In a preferred embodiment, the composite filler is a composition of aluminum hydroxide and boehmite.

[0015] In a preferred embodiment, the mass ratio of the aluminum hydroxide and the boehmite is (8-25):(3-15).

[0016] In a preferred embodiment, the mass ratio of the aluminum hydroxide and the boehmite is (12-15):(8-10).

[0017] Preferred embodiment, the average particle size of the hydroxyaluminum oxide is 0.5 to 3 μm.

[0018] Preferred embodiment, the average particle size of the hydroxyaluminum oxide is 0.8 to 1.5 μm.

[0019] Preferred embodiment, the average particle size of the boehmite is 1 to 4 μm.

[0020] Preferred embodiment, the average particle size of the boehmite is 2 to 3 μm.

[0021] Preferred embodiment, the organic solvent composition is a composition of ethylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and γ-butyrolactone.

[0022] Preferred embodiment, the mass ratio of ethylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and γ-butyrolactone is (7 to 9):(1 to 2):(0.5 to 1).

[0023] Preferred embodiment, the mass ratio of ethylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and γ-butyrolactone is (7.5 to 8.5):(1.5 to 2):(0.5 to 0.8).

[0024] Preferred embodiment, the mass ratio of ethylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and γ-butyrolactone is 8:2:(0.6 to 0.7).

[0025] Preferred embodiment, the halogen-free flame-retardant epoxy resin composition for copper clad laminates further comprises a curing agent, a curing accelerator, a coupling agent, and a surfactant.

[0026] Preferred embodiment, the curing agent is dicyandiamide.

[0027] Preferred embodiment, the curing accelerator is at least one of 2-phenylimidazole, 2-methylimidazole, triphenylphosphine, triethanolamine, and benzyldimethylamine.

[0028] Preferred embodiment, the curing accelerator is 2-phenylimidazole or 2-methylimidazole.

[0029] Preferred embodiment, the curing accelerator is 2-phenylimidazole.

[0030] Preferred embodiment, the coupling agent is at least one of amino-silane coupling agents.

[0031] Preferred embodiment, the surfactant is silicone-based, fluorocarbon-based, fatty alcohol polyoxyethylene ether-based, and phosphate-based.

[0032] Preferred embodiment, the surfactant is silicone-based.

[0033] In a preferred embodiment, the surfactant is BYK-307.

[0034] In a preferred embodiment, the halogen-free flame-retardant epoxy resin composition for copper clad laminates further comprises a composite property resin.

[0035] In a preferred embodiment, the composite property resin is a composition of benzoxazine and polyethylene naphthalate.

[0036] In a preferred embodiment, the mass ratio of benzoxazine to polyethylene naphthalate is (4 - 6):(2 - 3.5).

[0037] In a preferred embodiment, the mass ratio of benzoxazine to polyethylene naphthalate is (4.5 - 5):(2.5 - 3).

[0038] In a preferred embodiment, the mass ratio of the halogen-free epoxy resin to the composite property resin is (50 - 65):(8 - 16).

[0039] In a preferred embodiment, the mass ratio of the halogen-free epoxy resin to the composite property resin is (55 - 63):(9 - 14).

[0040] By adding the composite property resin, under the action of high temperature during use, a cross-linked network containing phenolic hydroxyl groups is generated, which synergistically forms an interpenetrating network structure with the curing reaction of the phosphorus-containing epoxy resin, improving the cross-linking density. And during combustion, the phenolic structure decomposed and the phosphate ester of the phosphorus-based epoxy resin act synergistically to promote the formation of a dense carbon layer, isolating the transfer of oxygen and heat, achieving a double flame-retardant effect in the gas phase - condensed phase. It can also be given low polarity through a specific molecular structure, reducing the dielectric constant and dielectric loss of the cured resin while maintaining good electrical properties.

[0041] On the other hand, the rigid naphthalene ring segments contained in the composite property resin and the flexible ethylene glycol ester bonds form a semi-crystalline structure, which is dispersed in the epoxy resin matrix. Through crack pinning and energy dissipation mechanisms, the fracture toughness and fatigue resistance of the material are improved, and the barrier property of the cured resin system to water molecules is effectively enhanced, reducing its penetration path and increasing the penetration resistance. Therefore, the excellent mechanical strength of the resin system is maintained during long-term use, and the deformation of the resin at high temperature is suppressed through good thermal expansion resistance, reducing the Z-axis thermal expansion of the copper clad laminate. And it can be partially dissolved in γ-butyrolactone added to the system of this application to form a micro-phase separation structure, balancing the melt viscosity of the resin system, thereby greatly improving the processing performance of the resin system. Finally, the composite property resin effectively improves the overall comprehensive performance of the system.

[0042] Preferred embodiment: For the halogen-free flame-retardant epoxy resin composition for copper clad laminates, calculated by mass parts, the raw materials include: 55 - 63 parts of halogen-free epoxy resin, 25 - 28 parts of composite filler, 12 - 16 parts of organic solvent composition, 2 - 4 parts of curing agent, 0.2 - 0.5 parts of curing accelerator, 0.6 - 1.2 parts of coupling agent, 1 - 1.5 parts of surfactant, and 9 - 14 parts of composite performance resin.

[0043] Preferred embodiment: The mass ratio of the curing agent, curing accelerator and coupling agent is (2.5 - 3):(0.3 - 0.4):(0.9 - 1.1).

[0044] The preparation method of the above-mentioned halogen-free flame-retardant epoxy resin composition for copper clad laminates specifically includes the following steps: S1: Add the raw materials in the organic solvent composition to a premixing tank, stir and heat up, continue to stir after adding the curing agent, and age to obtain a solvent system for standby; S2: Add the halogen-free epoxy resin, composite performance resin and composite filler to the solvent system, stir and mix, add the remaining raw materials, and carry out vacuum degassing; S3: Coating the degassed product on the electrolytic copper foil and thermally curing to complete.

[0045] Preferred embodiment: The preparation method specifically includes the following steps: S1: Add the raw materials in the organic solvent composition to a premixing tank, stir at 40 - 50 °C and 100 - 150 rpm for 30 - 35 min, heat up to 63 - 65 °C, add the curing agent, stir at 250 - 300 rpm for 3 - 4 h, then transfer to an aging tank for aging for 18 - 20 h to obtain a solvent system for standby; S2: Add the halogen-free epoxy resin, composite performance resin and composite filler to the solvent system, stir and mix at 40 - 45 °C and 100 - 120 rpm for 1.5 - 2 h, add the remaining raw materials, and carry out vacuum degassing; S3: Coating the degassed product on the electrolytic copper foil and thermally curing to complete.

[0046] Preferred embodiment: The aging temperature of the aging tank is 40 - 45 °C, and nitrogen is introduced to keep the oxygen content ≤ 30 ppm.

[0047] Preferred embodiment: The temperature of the thermal curing is 150 - 160 °C, the time is 30 - 40 min, and the pressure is 0.8 - 0.9 MPa.

[0048] This application further defines the application of the above-mentioned halogen-free flame-retardant epoxy resin composition for copper clad laminates in the preparation of wearable devices, new energy vehicle electronic control components and small electronic products.

[0049] Practical significance and effect:

[0050] 1. The finally obtained epoxy resin composition in this application can further achieve excellent heat resistance, moisture resistance, mechanical strength and electrical properties while maintaining the flame retardant performance, overcoming the performance contradiction problems existing in the prior art. For example, the CTI value is higher and can reach 600, and the viscosity is also controlled within a reasonable range to facilitate high-speed coating. Therefore, the copper clad laminate material prepared therefrom has excellent use effects.

[0051] 2. On the other hand, compared with the halogen-free epoxy resin composition in the prior art, this application avoids the situation of a large amount of ketone and DMF organic solvents used in the past, reduces the requirements for post-treatment and recycling, and the VOCs emissions are significantly reduced compared with the traditional prior art, showing stronger environmental friendliness.

[0052] 3. Further adding the composite performance resin can effectively improve the mechanical strength, thermal stability and moisture resistance of the epoxy resin composition through the formation of a cross-linked network, the nail-anchoring effect and the formation of a microphase separation structure, and balance the melt viscosity of the resin system, thereby greatly improving the processing performance of the resin system. Finally, the composite performance resin effectively improves the overall comprehensive performance of the system. Specific Embodiments

[0053] Example 1

[0054] The halogen-free flame retardant epoxy resin composition for copper clad laminate, in parts by mass, comprises the following raw materials: 60 parts of halogen-free epoxy resin, 26.8 parts of composite filler, 14.7 parts of organic solvent composition, 2.5 parts of curing agent, 0.3 part of curing accelerator, 1 part of coupling agent, 1.2 parts of surfactant, and 12.5 parts of composite performance resin.

[0055] The halogen-free epoxy resin is a phosphorus-containing DOPO type epoxy resin with a phosphorus content of 2 wt%, a viscosity of 600 mPa·s at 25°C, and the brand number: KB-686N75, from Zhongxin Century Electronic Materials (Shixing) Co., Ltd., China.

[0056] The composite filler is a composition of hydroxyaluminum oxide and boehmite with a mass ratio of 13:9.

[0057] The average particle size of the hydroxyaluminum oxide is 1.1 μm, and the average particle size of the boehmite is 2.6 μm.

[0058] The organic solvent composition is a composition of ethylene glycol monomethyl ether, propylene glycol monomethyl ether acetate and γ-butyrolactone with a mass ratio of 8:2:0.6.

[0059] The curing agent is dicyandiamide; the curing accelerator is 2-phenylimidazole; the coupling agent is an amino silane coupling agent KH-550; the surfactant is an organosilicon type BYK-307.

[0060] The composite performance resin is a composition of benzoxazine and polyethylene naphthalate glycolate, and the mass ratio is 5:2.5.

[0061] The benzoxazine is bisphenol A type benzoxazine, with the trade name MT 35600, from Huntsman Corporation, USA.

[0062] The polyethylene naphthalate glycolate has the trade name TN8050SC, and the brand is Teijin of Japan (from Huaxin Plastics, Zhangmutou, Dongguan, China).

[0063] The preparation method of the halogen-free flame-retardant epoxy resin composition for the copper clad laminate in this example specifically includes the following steps: S1: Add the raw materials in the organic solvent composition to the premixing tank, stir at 45°C and 120 rpm for 30 min, heat up to 63°C, add the curing agent, stir at 280 pm for 4 h, then transfer to the aging tank for aging for 18 h, the aging temperature is 40°C, and introduce nitrogen to keep the oxygen content ≤ 30 ppm to obtain the solvent system for standby; S2: Add the halogen-free epoxy resin, the composite performance resin and the composite filler to the solvent system, stir and mix at 45°C and 100 rpm for 1.5 h, add the remaining raw materials, and perform vacuum degassing; S3: Coat the degassed product on the electrolytic copper foil and perform thermal curing, the thermal curing temperature is 150°C, the time is 35 min, and the pressure is 0.8 MPa. Once completed, it is obtained.

[0064] Example 2

[0065] The difference between Example 2 and Example 1 is that: for the halogen-free flame-retardant epoxy resin composition for the copper clad laminate, by mass, the raw materials include: 63 parts of halogen-free epoxy resin, 28 parts of composite filler, 15.5 parts of organic solvent composition, 2.8 parts of curing agent, 0.3 parts of curing accelerator, 0.9 parts of coupling agent, 1.2 parts of surfactant, and 13.5 parts of composite performance resin.

[0066] The other implementation schemes are the same.

[0067] Example 3

[0068] The difference between Example 3 and Example 1 is that: for the halogen-free flame-retardant epoxy resin composition for the copper clad laminate, by mass, the raw materials include: 65 parts of halogen-free epoxy resin, 22.5 parts of composite filler, 12.5 parts of organic solvent composition, 2.6 parts of curing agent, 0.4 parts of curing accelerator, 1.1 parts of coupling agent, 1.2 parts of surfactant, and 14.8 parts of composite performance resin.

[0069] The other implementation schemes are the same.

[0070] Comparative Example 1

[0071] The difference between Comparative Example 1 and Example 1 is as follows: For the halogen-free flame-retardant epoxy resin composition used in the copper clad laminate, by mass, the raw materials include: 75 parts of halogen-free epoxy resin, 12.5 parts of composite filler, 10 parts of organic solvent composition, 2.5 parts of curing agent, 0.3 part of curing accelerator, 1 part of coupling agent, 1.2 parts of surfactant, and 12.5 parts of composite performance resin.

[0072] Other implementation schemes are the same.

[0073] Comparative Example 2

[0074] The difference between Comparative Example 2 and Example 1 is as follows: For the halogen-free flame-retardant epoxy resin composition used in the copper clad laminate, by mass, the raw materials include: 60 parts of halogen-free epoxy resin, 26.8 parts of composite filler, 14.7 parts of organic solvent composition, 2.5 parts of curing agent, 0.3 part of curing accelerator, 1 part of coupling agent, 1.2 parts of surfactant, and 4.5 parts of composite performance resin.

[0075] Other implementation schemes are the same.

[0076] Comparative Example 3

[0077] The difference between Comparative Example 3 and Example 1 is as follows: The organic solvent composition is a composition of ethylene glycol monomethyl ether and propylene glycol monomethyl ether acetate, and the mass ratio is 9:1.

[0078] Other implementation schemes are the same.

[0079] Comparative Example 4

[0080] The difference between Comparative Example 4 and Example 1 is as follows: The organic solvent composition is a composition of dipropylene glycol monomethyl ether, n-propyl acetate, and γ-butyrolactone.

[0081] Other implementation schemes are the same.

[0082] Comparative Example 5

[0083] The difference between Comparative Example 5 and Example 1 is as follows: The organic solvent composition is a composition of ethylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and γ-butyrolactone, and the mass ratio is 3:6:1.5.

[0084] Comparative Example 6

[0085] The difference between Comparative Example 6 and Example 1 is as follows: The composite performance resin is a composition of benzoxazine and polyethylene naphthalate, and the mass ratio is 4:0.5.

[0086] Other implementation schemes are the same.

[0087] Comparative Example 7

[0088] The difference between Comparative Example 7 and Example 1 is that the composite performance resin is a composition of benzoxazine and polyethylene naphthalate, and the mass ratio is 0.5:3.

[0089] In addition, the other implementation schemes are the same.

[0090] Performance Test

[0091] 1. CTI value: The test refers to IEC 60112, and the result of taking the average value of 10 tests is recorded in Table 1.

[0092] 2. Dielectric constant: The test refers to IPC TM650 2.5.5.5, and the result of taking the average value of 10 tests is recorded in Table 1.

[0093] 3. Peel strength: The test refers to IPC TM650 2.4.9, and the result of taking the average value of 10 tests is recorded in Table 1.

[0094] 4. Flame retardant grade: The test refers to UL 94, and the result is recorded in Table 1.

[0095] 5. Damp heat resistance: Prepare a 2 cm × 2 cm × 0.5 cm sample piece from the resin composition sample, dry it in an oven at 50 °C for 24 h, then keep it at 85 °C / 85% RH for 24 h, weigh the sample before and after the test, obtain the moisture absorption rate %, and the result of taking the average value of 10 tests is recorded in Table 1..

[0096] Table 1 Performance Test Results Table

[0097]

[0098]

[0099] Judging from the final test results shown in Table 1, in Comparative Examples 1 and 2, because the appropriate amounts of epoxy resin, composite filler, and the ratio of composite performance values were not used, their comprehensive performance decreased significantly compared with the Example.

[0100] In Comparative Examples 3 to 7, because the correct organic solvent and the combination of composite performance values were not used respectively, the overall combined effect decreased significantly, which further led to the decrease in comprehensive performance compared with the Example.

Claims

1. A halogen-free flame-retardant epoxy resin composition for a copper clad laminate, characterized in that: It comprises at least a halogen-free epoxy resin, a composite filler and an organic solvent composition, with a mass ratio of (50-65):(20-30):(10-18); The composite filler is a composition of aluminum hydroxide and boehmite, with a mass ratio of (8-25):(3-15); The organic solvent composition is a composition of ethylene glycol monomethyl ether, propylene glycol monomethyl ether acetate and γ-butyrolactone, with a mass ratio of (7-9):(1-2):(0.5-1).

2. The halogen-free flame-retardant epoxy resin composition for copper clad laminate according to claim 1, wherein: The halogen-free epoxy resin is a phosphorus-containing DOPO type epoxy resin.

3. The halogen-free flame-retardant epoxy resin composition for copper clad laminates according to claim 2, wherein: The phosphorus content of the phosphorus-containing DOPO type epoxy resin is 1-3.5 wt%.

4. The halogen-free flame-retardant epoxy resin composition for copper clad laminates according to claim 3, wherein: The viscosity of the phosphorus-containing DOPO type epoxy resin is 400-800 mPa·s at 25 °C.

5. The halogen-free flame-retardant epoxy resin composition for copper clad laminates according to any one of claims 1 to 4, characterized in that: The average particle size of the aluminum hydroxide is 0.5-3 μm; the average particle size of the boehmite is 1-4 μm.

6. The halogen-free flame-retardant epoxy resin composition for a copper clad laminate according to claim 1, wherein: The halogen-free flame-retardant epoxy resin composition for copper clad laminates further comprises a curing agent, a curing accelerator, a coupling agent and a surfactant; the curing agent is dicyandiamide.

7. The halogen-free flame-retardant epoxy resin composition for copper clad laminates according to claim 6, characterized in that: The halogen-free flame-retardant epoxy resin composition for copper clad laminates further comprises a composite performance resin; the composite performance resin is a composition of benzoxazine and polyethylene naphthalate, with a mass ratio of (4-6):(2-3.5).

8. The halogen-free flame-retardant epoxy resin composition for copper clad laminates according to claim 7, wherein: For the halogen-free flame-retardant epoxy resin composition for copper clad laminates, calculated by mass parts, the raw materials include: 55-63 parts of halogen-free epoxy resin, 25-28 parts of composite filler, 12-16 parts of organic solvent composition, 2-4 parts of curing agent, 0.2-0.5 parts of curing accelerator, 0.6-1.2 parts of coupling agent, 1-1.5 parts of surfactant, and 9-14 parts of composite performance resin; The mass ratio of the curing agent, the curing accelerator and the coupling agent is (2.5-3):(0.3-0.4):(0.9-1.1).

9. A preparation method of the halogen-free flame-retardant epoxy resin composition for copper clad laminates as claimed in claim 8, characterized in that: Specifically, it includes the following steps: S1: Add the raw materials in the organic solvent composition to a premixing tank, stir and heat up, continue to stir after adding the curing agent, and age to obtain a solvent system for standby; S2: Add the halogen-free epoxy resin, the composite performance resin and the composite filler to the solvent system and stir to mix, add the remaining raw materials, and carry out vacuum degassing; S3: Coating the degassed product on the electrolytic copper foil and thermally curing to complete the preparation.

10. Application of the halogen-free flame-retardant epoxy resin composition for copper clad laminates according to claim 8 in the preparation of wearable devices, new energy vehicle electronic control components and small electronic products.

Images