A halogen-free flame-retardant epoxy resin composition for copper-clad plate, a preparation method and application thereof

Abstract

The application relates to the field of copper-clad plates, and more particularly to a halogen-free flame-retardant epoxy resin composition for copper-clad plates and a preparation method and application thereof. The halogen-free flame-retardant epoxy resin composition for copper-clad plates comprises at least a halogen-free epoxy resin, a composite filler and an organic solvent composition, and the mass ratio of the three is (50-65):(20-30):(10-18). The epoxy resin composition prepared through the application can further obtain excellent heat resistance, moisture resistance, mechanical strength and electrical properties while maintaining the flame-retardant property, and the existing performance contradiction problems in the prior art are overcome, and the copper-clad plate material prepared through the application has excellent use effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of copper clad laminates, and more particularly to a halogen-free flame-retardant epoxy resin composition for copper clad laminates, a preparation method and application thereof. BACKGROUND

[0002] Copper clad laminates (CCL) as the core substrate of printed circuit boards (PCB), its performance directly determines the reliability, heat resistance and safety of electronic equipment. In recent years, epoxy resin has become the mainstream choice of copper clad laminate base resin due to its excellent adhesion, chemical resistance and processability. However, in order to meet the UL94 V-0 level flame retardant requirement, halogen-containing flame retardants (such as brominated epoxy resin) are often added in traditional epoxy resin system. With the strict restriction of environmental protection regulations on halogen compounds, the development of high-performance halogen-free flame-retardant epoxy resin system has become an important research direction in the field of copper clad laminates.

[0003] Current halogen-free flame-retardant technology mainly relies on the synergistic effect 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 uses a phosphorus-containing epoxy resin, a large amount of fillers and solvents. Under the premise of ensuring halogen-free, the adhesion, flame retardance and flexibility of the resin are effectively improved, and the copper clad laminate prepared thereby can maintain good peel strength and heat resistance. However, at the same time, such system is prone to a large increase in viscosity and an increase in dielectric loss. Although inorganic fillers are environmentally friendly and low in 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 wet heat and decreased thermal stability at high temperatures, which affect the long-term reliability of the copper clad laminate in a high temperature and high humidity environment.

[0004] In another aspect, as described in patent CN102051026B, the existing technology uses a large amount of ketone solvents and DMF solvents when using such epoxy resin system, which has high requirements for post-processing and recovery, and the cost is increased. In addition, such a large amount of solvents is not environmentally friendly, and there is a balance contradiction between flame retardance and comprehensive performance, which causes the copper clad laminate to lose its electrical performance while maintaining excellent flame retardance, and the mechanical strength is significantly decreased. SUMMARY

[0005] As described above, how to balance the comprehensive performance of the epoxy resin composition for copper-clad plate while maintaining excellent flame retardant performance, especially maintaining good electrical performance 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 stability, moisture resistance and processing performance of copper-clad plates. Therefore, in order to effectively solve the above problems, the applicant proposes a halogen-free flame-retardant epoxy resin composition for copper-clad plate and a preparation method thereof. The epoxy resin composition ultimately prepared by the applicant can further obtain excellent heat resistance, moisture resistance, mechanical strength and electrical performance while maintaining flame retardant performance, overcoming the performance contradiction problems existing in the prior art, and the copper-clad plate material prepared therefrom has excellent use effect.

[0006] A halogen-free flame-retardant epoxy resin composition for copper-clad plate, 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 1-3.5wt%.

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

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

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

[0014] In a preferred embodiment, the composite filler is a combination of hydroxyl aluminum oxide and boehmite.

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

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

[0017] In a preferred embodiment, the average particle diameter of the boehmite is 1 to 4 μm.

[0018] In a preferred embodiment, the average particle diameter of the boehmite is 1 to 4 μm.

[0019] In a preferred embodiment, the average particle diameter of the boehmite is 1 to 4 μm.

[0020] In a preferred embodiment, the average particle diameter of the boehmite is 1 to 4 μm.

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

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

[0023] In a preferred embodiment, the mass ratio of the ethylene glycol monomethyl ether, propylene glycol monomethyl ether acetate and γ-butyrolactone is (7 to 9) : (1 to 2) : (0.5 to 1).

[0024] In a preferred embodiment, the mass ratio of the ethylene glycol monomethyl ether, propylene glycol monomethyl ether acetate and γ-butyrolactone is (7 to 9) : (1 to 2) : (0.5 to 1).

[0025] In a preferred embodiment, the halogen-free flame-retardant epoxy resin composition for a copper-clad plate further includes a curing agent, a curing accelerator, a coupling agent and a surfactant.

[0026] In a preferred embodiment, the curing agent is dicyandiamide.

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

[0028] In a preferred embodiment, the curing accelerator is 2-phenylimidazole or 2-methylimidazole.

[0029] In a preferred embodiment, the curing accelerator is 2-phenylimidazole.

[0030] In a preferred embodiment, the coupling agent is at least one of an aminosilane coupling agent.

[0031] In a preferred embodiment, the surfactant is an organosilicon-based, a fluorocarbon-based, a fatty alcohol polyoxyethylene ether-based and a phosphate-based.

[0032] In a preferred embodiment, the surfactant is an organosilicon-based.

[0033] In a preferred embodiment, the surface active agent is BYK-307.

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

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

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

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

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

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

[0040] With the addition of the composite performance resin, under the action of high temperature in use, a crosslinked network containing phenolic hydroxyl groups is generated, which cooperates with the curing reaction of the phosphorus-containing epoxy resin to form an interpenetrating network structure, thereby improving the crosslinking density. During combustion, the generated phenolic structure cooperates with the phosphate ester of the phosphorus-containing epoxy resin to promote the formation of a dense carbon layer, thereby insulating the transmission of oxygen and heat, achieving a dual flame-retardant effect in the gas phase and the condensed phase. In addition, the specific molecular structure can impart low polarity to the resin, thereby reducing the dielectric constant and dielectric loss of the cured resin while maintaining good electrical properties.

[0041] On the other hand, the rigid naphthalene segment in the composite performance resin forms a semi-crystalline structure with the flexible ethylene glycol ester bond, which is dispersed in the epoxy resin matrix to improve the fracture toughness and fatigue resistance of the material through crack anchoring and energy dissipation mechanisms. In addition, the composite performance resin effectively improves the barrier property of the resin system to water molecules after curing, reduces the penetration path, and increases the penetration resistance, thereby maintaining the excellent mechanical strength of the resin system during long-term use. In addition, the composite performance resin inhibits the deformation of the resin at high temperatures through good thermal expansion resistance, thereby reducing the thermal expansion of the copper-clad plate in the Z-axis direction. Furthermore, the composite performance resin can be partially dissolved in the γ-butyrolactone added in the system to form a microphase separation structure, thereby balancing the melt viscosity of the resin system and significantly improving the processing performance of the resin system. Ultimately, the composite performance resin effectively improves the overall comprehensive performance of the system.

[0042] In a preferred embodiment, the copper-clad plate is prepared by using the halogen-free flame-retardant epoxy resin composition, and the raw materials include, in parts by mass, 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] In a preferred embodiment, 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).

[0044] The preparation method of the halogen-free flame-retardant epoxy resin composition for the copper-clad plate includes the following steps: S1: adding the raw materials in the organic solvent composition into a premixing tank, stirring and heating, continuously stirring after adding the curing agent, and aging to obtain a solvent system for standby; S2: adding the halogen-free epoxy resin, the composite performance resin and the composite filler into the solvent system for stirring and mixing, adding the remaining raw materials, and vacuum degassing; and S3: coating the degassed product on an electrolytic copper foil and heat curing to complete the preparation.

[0045] In a preferred embodiment, the preparation method includes the following steps: S1: adding the raw materials in the organic solvent composition into a premixing tank, stirring at 40-50℃ and 100-150rpm for 30-35min, heating to 63-65℃, adding the curing agent, stirring at 250-300rpm for 3-4h, and then transferring into an aging tank for aging for 18-20h to obtain a solvent system for standby; S2: adding the halogen-free epoxy resin, the composite performance resin and the composite filler into the solvent system, stirring and mixing at 40-45℃ and 100-120rpm for 1.5-2h, adding the remaining raw materials, and vacuum degassing; and S3: coating the degassed product on an electrolytic copper foil and heat curing to complete the preparation.

[0046] In a preferred embodiment, the aging temperature of the aging tank is 40-45℃, and nitrogen is introduced to maintain the oxygen content at ≤30ppm.

[0047] In a preferred embodiment, the heat curing temperature is 150-160℃, the time is 30-40min, and the pressure is 0.8-0.9MPa.

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

[0049] Actual significance and effects:

[0050] 1、The epoxy resin composition prepared in the application can further obtain excellent heat resistance, moisture resistance, mechanical strength and electrical properties while maintaining flame retardant properties, overcoming the performance contradiction problems existing in the prior art, such as a higher CTI value, which can reach 600, and a viscosity controlled in a reasonable range for convenient high-speed coating, so that the copper-clad plate material prepared therefrom has excellent use effect.

[0051] 2、In another aspect, compared with the halogen-free epoxy resin composition in the prior art, the use of a large amount of ketone and DMF organic solvents in the application is avoided, the requirements for post-treatment and recovery are reduced, VOCs emission is greatly reduced compared with the traditional prior art, and environmental friendliness is stronger.

[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 crosslinked network, the formation of a nail anchor effect and a microphase separation structure, balance the melt viscosity of the resin system, and further greatly improve the processing performance of the resin system, and finally the composite performance resin effectively prompts the overall comprehensive performance of the system. DETAILED DESCRIPTION

[0053] Example 1

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

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

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

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

[0058] The organic solvent composition is a composition of ethylene glycol methyl ether, propylene glycol methyl 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 amino silane coupling agent KH-550; and the surfactant is organic silicon BYK-307.

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

[0061] The benzoxazine is a bisphenol A type benzoxazine, with a brand of MT 35600, from Huntsman Corporation, USA.

[0062] The polyethylene naphthalate has a brand of TN8050SC, from Japan Teijin (from China Dongguan Zhangmutou Huaxin Plastic).

[0063] The preparation method of the halogen-free flame-retardant epoxy resin composition for copper-clad plate in the embodiment specifically comprises the following steps: S1: adding raw materials in an organic solvent composition into a premixing tank, stirring at 45°C and 120 rpm for 30 min, increasing the temperature to 63°C, adding a curing agent, stirring at 280 rpm for 4 h, and then transferring into an aging tank for aging for 18 h, with an aging temperature of 40°C, and nitrogen gas being introduced to keep the oxygen content ≤30 ppm, to obtain a solvent system for standby; S2: adding a halogen-free epoxy resin, a composite performance resin, and a composite filler into the solvent system, stirring and mixing at 45°C and 100 rpm for 1.5 h, adding remaining raw materials, and vacuum degassing; S3: coating the degassed product on an electrolytic copper foil and heat curing, with a heat curing temperature of 150°C, a time of 35 min, and a pressure of 0.8 MPa, to complete the process.

[0064] Example 2

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

[0066] The other embodiments are the same as above.

[0067] Example 3

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

[0069] The other embodiments are the same as above.

[0070] Comparative Example 1

[0071] Comparative Example 1 and Example 1 differ in that the halogen-free flame-retardant epoxy resin composition for a copper-clad plate comprises, by mass parts, halogen-free epoxy resin 75 parts, composite filler 12.5 parts, organic solvent composition 10 parts, curing agent 2.5 parts, curing accelerator 0.3 parts, coupling agent 1 part, surfactant 1.2 parts, and composite performance resin 12.5 parts.

[0072] The other embodiments are the same as above.

[0073] Comparative Example 2

[0074] Comparative Example 2 and Example 1 differ in that the halogen-free flame-retardant epoxy resin composition for a copper-clad plate comprises, by mass parts, halogen-free epoxy resin 60 parts, composite filler 26.8 parts, organic solvent composition 14.7 parts, curing agent 2.5 parts, curing accelerator 0.3 parts, coupling agent 1 part, surfactant 1.2 parts, and composite performance resin 4.5 parts.

[0075] The other embodiments are the same as above.

[0076] Comparative Example 3

[0077] Comparative Example 3 and Example 1 differ in that the organic solvent composition is a composition of ethylene glycol methyl ether, propylene glycol methyl ether acetate, in a mass ratio of 9:1.

[0078] The other embodiments are the same as above.

[0079] Comparative Example 4

[0080] Comparative Example 4 and Example 1 differ in that the organic solvent composition is a composition of dipropylene glycol methyl ether, n-propyl acetate, and γ-butyrolactone.

[0081] The other embodiments are the same as above.

[0082] Comparative Example 5

[0083] Comparative Example 5 and Example 1 differ in that the organic solvent composition is a composition of ethylene glycol methyl ether, propylene glycol methyl ether acetate, and γ-butyrolactone, in a mass ratio of 3:6:1.5.

[0084] Comparative Example 6

[0085] Comparative Example 6 and Example 1 differ in that the composite performance resin is a composition of benzoxazine and polyethylene naphthalate, in a mass ratio of 4:0.5.

[0086] The other embodiments are the same as above.

[0087] Comparative Example 7

[0088] Comparative Example 7 differs from Example 1 in that the performance resin is a combination of benzoxazine and polyethylene naphthalate in a mass ratio of 0.5:3.

[0089] The other embodiments are the same.

[0090] Performance tests

[0091] 1. CTI value: tested according to IEC 60112, the results were averaged from 10 tests and recorded in Table 1.

[0092] 2. Dielectric constant: tested according to IPC TM650 2.5.5.5, the results were averaged from 10 tests and recorded in Table 1.

[0093] 3. Peel strength: tested according to IPC TM650 2.4.9, the results were averaged from 10 tests and recorded in Table 1.

[0094] 4. Flame retardant rating: tested according to UL 94, the results were recorded in Table 1.

[0095] 5. Moisture resistance: resin composition samples were made into 2cm x 2cm x 0.5cm samples, dried in a 50°C oven for 24h, then kept at 85°C / 85%RH for 24h, the samples were weighed before and after the test, the moisture absorption % was calculated, the results were averaged from 10 tests and recorded in Table 1.

[0096] Table 1 Performance test results

[0097]

[0098]

[0099] From the final test results shown in Table 1, it can be seen that Comparative Examples 1 and 2 did not use the appropriate amount of epoxy resin, and the combination of filler and performance resin values, resulting in a significant decrease in overall performance compared to the examples.

[0100] Comparative Examples 3-7 did not use the correct organic solvent and the combination of performance resin values, resulting in a significant decrease in overall performance, which further led to a decrease in overall performance compared to the examples.

Claims

1. A halogen-free flame-retardant epoxy resin composition for copper clad laminates, characterized by: At least including halogen-free epoxy resin, composite filler and organic solvent composition, mass ratio is (50~65):(20~30):(10~18); The composite filler is a combination of hydroxyl aluminum oxide and boehmite, mass ratio is (8~25):(3~15); The organic solvent composition is a combination of ethylene glycol methyl ether, propylene glycol methyl ether acetate and gamma-butyrolactone, mass ratio is (7~9):(1~2):(0.5~1); The halogen-free epoxy resin is a phosphorus-containing DOPO type epoxy resin; The halogen-free flame-retardant epoxy resin composition for copper-clad plate further includes a composite performance resin; the composite performance resin is a combination of benzoxazine and polyethylene glycol naphthalate, mass ratio is (4~6):(2~3.5); The viscosity of the phosphorus-containing DOPO type epoxy resin is 400~800 mPa·s at 25℃.

2. The halogen-free flame-retardant epoxy resin composition for a copper-clad plate according to claim 1, characterized by: The phosphorus content of the phosphorus-containing DOPO type epoxy resin is 1~3.5wt%.

3. The halogen-free flame-retardant epoxy resin composition for a copper-clad plate according to any one of claims 1 to 2, characterized by: The average particle size of the hydroxyl aluminum oxide is 0.5~3μm; the average particle size of the boehmite is 1~4μm.

4. The halogen-free flame-retardant epoxy resin composition for a copper-clad plate according to claim 3, characterized by: The halogen-free flame-retardant epoxy resin composition for copper-clad plate further includes a curing agent, a curing accelerator, a coupling agent and a surfactant; the curing agent is dicyandiamide.

5. The halogen-free flame-retardant epoxy resin composition for a copper-clad plate according to claim 4, characterized by: The halogen-free flame-retardant epoxy resin composition for copper-clad plate includes, in mass parts, halogen-free epoxy resin 55~63 parts, composite filler 25~28 parts, organic solvent composition 12~16 parts, curing agent 2~4 parts, curing accelerator 0.2~0.5 parts, coupling agent 0.6~1.2 parts, surfactant 1~1.5 parts, and composite performance resin 9~14 parts. 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).

6. A method of producing the halogen-free flame-retardant epoxy resin composition for a copper-clad plate according to claim 5, characterized by: Specifically including the following steps: S1: adding raw materials in the organic solvent composition into a premixing tank, stirring and heating, continuing to stir after adding the curing agent, aging, obtaining a solvent system for standby; S2: adding halogen-free epoxy resin, composite performance resin and composite filler into the solvent system for stirring and mixing, adding the remaining raw materials, vacuum degassing; S3: coating the degassed product with electrolytic copper foil and heat curing, completing to obtain the product.

7. Use of the halogen-free flame-retardant epoxy resin composition for copper-clad plate according to claim 5 in the preparation of wearable devices, new energy automobile electronic control elements and small electronic products.

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