Preparation method of phosphorus / silicon-containing phenolic resin for halogen-free copper-clad plate (FR-4)

Abstract

The invention relates to a preparation method of a phosphorus / silicon (P / Si)-containing phenolic resin curing agent for a copper-clad plate, belonging to a preparation method of a high polymer material. The flame-retardant phenolic resin material is prepared by directly introducing a flame retardant into a phenolic resin molecular chain, and 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and a silane coupling agent are mainly used as flame-retardant element donors; the two components are taken as raw materials in a phenolic resin synthesis process through chemical bonding to directly participate in the resin synthesis process, P and Si elements are effectively introduced into a resin molecular chain, and the heat resistance and flame retardance of the phenolic resin and a curing system thereof can be remarkably improved through the synergistic flame retardant effect of the P and Si elements. The preparation method overcomes the defects of poor flame-retardant effect and short service time of the material caused by molecular migration in the composite material due to the addition of the traditional small-molecular flame retardant / flame-retardant filler. The development of the novel curing agent not only promotes the technical progress of the phenolic resin curing agent, but also widens the practical application prospect of the phenolic resin curing agent.

Description

Technical Field

[0001] The invention belongs to a method for preparing a polymer material, and relates to a method for preparing a phosphorus / silicon-containing phenolic resin for a halogen-free copper-clad laminate. Background Art

[0002] With the increasing demand for PCB materials in the fields of electronic computers and smart materials such as AI, 5G, and intelligent assisted driving, the requirements for copper-clad PCB substrates are becoming increasingly higher, such as high frequency and high speed, low dielectric, flame retardant and heat resistant. In the early years, the industry generally used bromine-based, nitrogen-based and phosphorus-based flame retardants alone or in combination to improve the heat resistance and flame retardancy of epoxy phenolic curing systems. However, due to environmental pollution and other issues, the use of bromine-based flame retardants has gradually been restricted.

[0003] In addition, some phosphorus-based flame retardants (such as red phosphorus) have safety issues and their usage has gradually decreased. Moreover, the use of phosphate flame retardants will also reduce the heat resistance and solvent resistance of solder.

[0004] In recent years, copper clad laminates have mostly used phenolic resins with high-density heat-resistant benzene ring structures as curing agents for epoxy resins to improve the heat resistance of the curing system. With the development of environmental protection concepts and the demand of the electronic chemicals industry for high-frequency and high-speed data transmission, the development of high-performance halogen-free copper clad laminates (FR-4) is becoming more and more rapid. At present, high-end products in the FR-4 field mainly rely on imports. Therefore, the development of the PCB industry and downstream industries is to a certain extent limited by the research and development technology constraints in this field, and product nationalization substitution is imminent. Summary of the invention

[0005] The purpose of the present invention is to provide a method for synthesizing a phosphorus / silicon (P / Si) phenolic resin curing agent for copper clad laminates. The method uses 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and a silane coupling agent as flame retardant element donors, and directly participates in the resin synthesis process as raw materials in the phenolic resin synthesis process through chemical bonding, effectively introducing P and Si elements into the resin molecular chain, and the synergistic flame retardant effect of the P / Si elements can significantly improve the heat resistance and flame retardancy of the phenolic resin and its curing system. In addition, the curing agent has good compatibility in the downstream copper clad laminate formulation and can effectively optimize the performance of the final product.

[0006] The objective of the present invention is achieved through the following technical solutions: A method for preparing a P / Si-containing phenolic resin curing agent for copper-clad laminates, the method comprising the following preparation processes: first, preparing a P / Si-containing flame retardant (DOPO-KH), and second, preparing a P / Si-containing phenolic resin. The specific scheme is as follows: Step 1. Preparation of P / Si flame retardant: DOPO and hydrolyzed silane coupling agent were mixed evenly in a three-necked flask, and then triphenylphosphine catalyst was added. The reaction system was reacted at 115-140°C for 6-8h under an inert gas atmosphere. After the reaction was completed, chloroform was added to dissolve, and then petroleum ether was used to precipitate the sample. Finally, the mixture was heated at 60 o C oven for 12 h to obtain a P / Si containing flame retardant (DOPO-KH); Preferably, the molar ratio of DOPO to silane coupling agent is 0.9-1.1:1; Preferably, the silane coupling agent is KH-560; Preferably, the molar ratio of DOPO to triphenylphosphine is 1:0.01-0.1; Step 2. Preparation of P / Si-containing phenolic resin: After mixing phenolic substances and alkaline solution at 55-60°C, aldehyde substances are added and reacted at 70-80°C for 0.5-1h. Subsequently, DOPO-KH is added to the system and the temperature is slowly raised to 85-95°C for reaction for 1-3h. After the reaction, an appropriate amount of acid is added to adjust the pH of the system to neutral, and the reacted material is obtained by vacuum distillation, which is then washed and dried at 60°C to obtain the P / Si-containing phenolic resin.

[0007] Preferably, the molar ratio of the phenolic compound to the aldehyde compound is 1:1-2; Preferably, the inert gas is argon or nitrogen, preferably nitrogen; Preferably, the phenolic substance is one of phenol, 2-methylphenol, 2,6-dimethylphenol, bisphenol A, 4,4-biphenylene glycol, and 3,3'-dimethyl-4,4'-biphenylene glycol.

[0008] Preferably, the alkaline solution is an aqueous solution of sodium hydroxide or potassium hydroxide with a mass concentration of 10%; Preferably, the aldehyde substance is one of paraformaldehyde and formaldehyde aqueous solution; Preferably, the acid is one or more of glacial acetic acid, hydrochloric acid and concentrated sulfuric acid.

[0009] The beneficial effects of the present invention are: In the present invention, DOPO and a silane coupling agent are subjected to an addition reaction, and the P and Si elements are integrated as phenolic resin reaction monomers to prepare a flame-retardant phenolic resin, and the P and Si flame-retardant elements are directly introduced into the main chain of the phenolic resin. In addition, the preparation process of the synthesized P / Si synergistic flame retardant is convenient and simple, and the yield is high.

[0010] As a reactive flame retardant, P / Si synergistic flame retardant is grafted onto the main chain of phenolic resin, avoiding the migration, volatilization or precipitation of additive flame retardants in composite materials during use.

[0011] The P / Si elements work synergistically in the flame retardant process. The gas phase flame retardant effect of the phosphorus-containing flame retardant and the solid phase flame retardant effect of the silicon-containing flame retardant can significantly improve the heat resistance, flame resistance and other properties of the phenolic resin. The flame retardant is timely and efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is the synthesis reaction equation of the P / Si-containing flame retardant (DOPO-KH) of the present invention; Figure 2 It is the synthesis reaction equation of the P / Si-containing phenolic resin of the present invention. DETAILED DESCRIPTION

[0013] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention. Example 1

[0014] (1) Preparation of DOPO-KH containing P / Si flame retardant 216 g (1 mol) DOPO and 236 g (1 mol) KH-560 were mixed evenly in a three-necked flask, and 26.2 g (0.1 mol) triphenylphosphine was added. The reaction system was reacted at 130 ° C for 7 h under nitrogen. After the reaction was completed, chloroform was added to dissolve, and then the sample was precipitated with petroleum ether. Finally, the mixture was heated at 60 o C oven for 12 h to obtain a P / Si containing flame retardant (DOPO-KH); (2) Preparation of P / Si-containing phenolic resin 94 g (1 mol) of phenol and 10% sodium hydroxide solution were added to a three-necked flask, mixed evenly at 60 °C, 81 g (1 mol) of formaldehyde aqueous solution were added, and the mixture was reacted at 75 °C for 0.5 h. Subsequently, 131.1 g of DOPO-KH was added to the system, and the temperature was slowly raised to 90 °C for reaction for 2 h. After the reaction, concentrated sulfuric acid was added to adjust the pH of the system to neutral, and the reacted material was obtained by vacuum distillation, which was then washed and dried at 60 °C to obtain a P / Si-containing phenolic resin. Example 2

[0015] 94g (1 mol) of phenol and 10% sodium hydroxide solution were added to a three-necked flask, mixed evenly at 60°C, and 81g (1 mol) of formaldehyde aqueous solution was added. The reaction system was heated to 75°C and reacted for 2h. After the reaction, concentrated sulfuric acid was added to adjust the pH of the system to neutral, and the reaction material was obtained by vacuum distillation, washed and dried at 60°C to obtain phenolic resin. The obtained phenolic resin was evenly mixed with 69g of DOPO by tetrahydrofuran, and dried at 70°C to obtain a blended product of phenolic resin and DOPO. Example 3

[0016] 94g (1 mol) of phenol and 10% sodium hydroxide solution were added to a three-necked flask, mixed evenly at 60°C, and 81g (1 mol) of formaldehyde aqueous solution were added. The reaction system was heated to 75°C and reacted for 2h. After the reaction, concentrated sulfuric acid was added to adjust the pH of the system to neutral, and the reaction material was obtained by vacuum distillation, washed and dried at 60°C to obtain phenolic resin. The obtained phenolic resin was evenly mixed with 131.1g of DOPO-KH by tetrahydrofuran, and dried at 70°C to obtain a blended product of phenolic resin and DOPO-KH. Example 4

[0017] Add 94 g (1 mol) of phenol and 10% sodium hydroxide solution into a three-necked flask, mix well at 60°C, add 81 g (1 mol) of formaldehyde aqueous solution, heat the reaction system to 75°C and react for 2 hours. After the reaction, add concentrated sulfuric acid to adjust the pH of the system to neutral, distill under reduced pressure to obtain the reacted material, wash and dry at 60°C to obtain phenolic resin.

[0018] The phenolic resin curing agent obtained in the above embodiment was mixed evenly with the epoxy resin by solvent, and a curing accelerator 2-phenylimidazole was added. After the curing reaction, the limiting oxygen index LOI and vertical burning UL-94 tests were performed. The test results are shown in Table 1.

[0019] Table 1 Test results of the embodiment .

Claims

1. A method for preparing a phosphorus / silicon-containing phenolic resin for a halogen-free copper clad laminate (FR-4), characterized in that: The method comprises the following steps: Step 1. Preparation of P / Si flame retardant: DOPO and hydrolyzed silane coupling agent were mixed evenly in a three-necked flask, and then triphenylphosphine catalyst was added. The reaction system was reacted at 115-140°C for 6-8h under an inert gas atmosphere. After the reaction was completed, chloroform was added to dissolve, and then petroleum ether was used to precipitate the sample. Finally, the mixture was heated at 60 o C oven for 12 h to obtain a P / Si containing flame retardant (DOPO-KH); Step 2. Preparation of P / Si-containing phenolic resin: After mixing phenolic substances and alkaline solution at 55-60°C, aldehyde substances are added and reacted at 70-80°C for 0.5-1h. Subsequently, DOPO-KH is added to the system and the temperature is slowly raised to 85-95°C for reaction for 1-3h. After the reaction, an appropriate amount of acid is added to adjust the pH of the system to neutral, and the reacted material is obtained by vacuum distillation, which is then washed and dried at 60°C to obtain the P / Si-containing phenolic resin.

2. The method for preparing a phosphorus / silicon-containing phenolic resin for a halogen-free copper clad laminate (FR-4) according to claim 1, characterized in that: The molar ratio of DOPO to silane coupling agent is 0.9-1.1:

1.

3. The method for preparing a phosphorus / silicon-containing phenolic resin for a halogen-free copper clad laminate (FR-4) according to claim 1, characterized in that: The silane coupling agent is KH-560.

4. The method for preparing a phosphorus / silicon-containing phenolic resin for a halogen-free copper clad laminate (FR-4) according to claim 1, characterized in that: The molar ratio of DOPO to triphenylphosphine is 1:0.01-0.

1.

5. The method for preparing a phosphorus / silicon-containing phenolic resin for a halogen-free copper clad laminate (FR-4) according to claim 1, characterized in that: The molar ratio of the phenolic compound to the aldehyde compound is 1:1-2.

6. The method for preparing a phosphorus / silicon-containing phenolic resin for a halogen-free copper clad laminate (FR-4) according to claim 1, characterized in that: The inert gas is argon or nitrogen, preferably nitrogen.

7. The method for preparing a phosphorus / silicon-containing phenolic resin for a halogen-free copper clad laminate (FR-4) according to claim 1, characterized in that: The phenolic substance is one of phenol, 2-methylphenol, 2,6-dimethylphenol, bisphenol A, 4,4-biphenylene glycol, and 3,3'-dimethyl-4,4'-biphenylene glycol.

8. The method for preparing a phosphorus / silicon-containing phenolic resin for a halogen-free copper clad laminate (FR-4) according to claim 1, characterized in that: The alkaline solution is an aqueous solution of sodium hydroxide and potassium hydroxide with a mass concentration of 10%.

9. The method for preparing a phosphorus / silicon-containing phenolic resin for a halogen-free copper clad laminate (FR-4) according to claim 1, characterized in that: The aldehyde substance is one of paraformaldehyde and formaldehyde aqueous solution.

10. The method for preparing a phosphorus / silicon-containing phenolic resin for a halogen-free copper clad laminate (FR-4) according to claim 1, characterized in that: The acid is one or more of glacial acetic acid, hydrochloric acid and concentrated sulfuric acid.

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