Active ester curing agent, preparation method thereof and epoxy resin composition

Abstract

The invention discloses an active ester curing agent, a preparation method thereof and an epoxy resin composition, and relates to the field of electronic packaging materials. An active ester curing agent is prepared by acylation reaction of dihydric phenol and acyl chloride under the action of a catalyst, the dihydric phenol simultaneously contains phenolic hydroxyl groups, alkoxy groups and dimethyl siloxane chain segments, R is selected from alkylene groups containing 1-5 carbon atoms, the alkoxy groups are methoxy groups or ethyoxyl groups, and the value range of the dimethyl siloxane chain segments is an integer ranging from 35 to 50. The active ester curing agent has good compatibility with epoxy resin, is moderate in curing rate and small in internal stress when being used for curing the epoxy resin, can improve the film forming quality, can reduce the dielectric constant and dielectric loss of the epoxy resin, and ensures the low temperature resistance, high heat resistance, low hygroscopicity and flexibility of the epoxy resin; the method is suitable for the electronic packaging field.

Description

Technical Field

[0001] This application relates to the field of electronic packaging materials, and in particular to an active ester curing agent, its preparation method, and an epoxy resin composition. Background Technology

[0002] Epoxy resin is one of the important materials in the field of electronic packaging. Epoxy resin needs to undergo chemical cross-linking with a curing agent to form an infusible three-dimensional network structure to exert its excellent properties. Commonly used curing agents include amines, phenols, and acid anhydrides. Amine and phenolic curing agents contain active hydrogen, which reacts with epoxy groups to produce a large number of highly polar hydroxyl groups, increasing the water absorption and dielectric loss of the cured material. Acid anhydride curing agents do not produce additional hydroxyl groups after reacting with epoxy groups, but acid anhydrides themselves readily absorb water during storage, becoming free acids, which affect the degree of curing and performance of the cured material. Therefore, commonly used curing agents cannot meet the requirements of next-generation low-dielectric packaging materials.

[0003] Reactive ester curing agents are compounds containing two or more ester groups in their molecules. The ester groups in reactive ester curing agents have high reactivity and can react with epoxy groups under the action of accelerators to form a three-dimensional network structure, thereby curing the epoxy resin. It is worth noting that reactive ester curing agents do not produce strongly polar hydroxyl groups after reacting with epoxy groups; instead, they produce ester groups with low polarity and large volume. The resulting cured epoxy resin has lower water absorption and dielectric loss, making it more suitable for high-frequency, high-speed electronic packaging materials.

[0004] However, existing reactive ester curing agents are insufficient to maintain the low-temperature resistance, high heat resistance, low moisture absorption, and flexibility of epoxy resins while reducing their dielectric constant and dielectric loss. Therefore, further improvements are needed. Summary of the Invention

[0005] In order to ensure the low-temperature resistance, high heat resistance, low moisture absorption and flexibility of epoxy resin while reducing the dielectric constant and dielectric loss of epoxy resin, this application provides an active ester curing agent, its preparation method and epoxy resin composition.

[0006] Firstly, the active ester curing agent provided in this application adopts the following technical solution: An active ester curing agent is prepared by acylation reaction of a diphenol and an acyl chloride in the presence of a catalyst. The general structural formula of the diphenol is as follows: ; Wherein, R is selected as an alkylene group containing 1-5 carbon atoms, R1 is selected as methyl or ethyl, and n is an integer ranging from 35 to 50.

[0007] This application describes an active ester curing agent prepared by acylation reaction of a diphenol and an acyl chloride under the catalysis of a catalyst. Unlike existing active ester curing agents, the diphenol used in this application contains phenolic hydroxyl, alkoxy, and organosilicon segments. Specifically, R is defined as an alkylene group containing 1-5 carbon atoms, the alkoxy group is either methoxy or ethoxy, and the value of the dimethylsiloxane segment n is specified. The active ester curing agent is prepared by reacting this specific diphenol with an acyl chloride. This active ester curing agent exhibits good compatibility with epoxy resins. When used in the curing of epoxy resins, it provides a moderate curing rate, low internal stress, and improved film quality. Simultaneously, it reduces the dielectric constant and dielectric loss of the epoxy resin and ensures its low-temperature resistance, high heat resistance, low moisture absorption, and flexibility, making it suitable for the electronic packaging field.

[0008] It is important to note that R1 should not be an alkyl group with an excessively long carbon chain. An excessively long R1 carbon chain can significantly reduce the yield of the reactive ester curing agent, rendering it impractical. The value of n should be in the range of 35-50, which can balance the compatibility of the reactive ester curing agent with the epoxy resin, and can ensure the epoxy resin's high heat resistance, low moisture absorption, and flexibility while reducing its dielectric constant and dielectric loss.

[0009] In some specific embodiments, R is selected as an alkylene group containing 1-5 carbon atoms, R1 is selected as a methyl group, and the value of n is preferably an integer from 45 to 50.

[0010] In some specific embodiments, the molar ratio of the phenolic hydroxyl group in the diphenol to the acyl chloride group in the acyl chloride is 1:(1.02-1.05).

[0011] In this application, the preferred molar ratio of the phenolic hydroxyl group in the diphenol to the acyl chloride group in the acyl chloride is 1:(1.02-1.05). An appropriate excess of acyl chloride is beneficial to improving the conversion rate of the phenolic hydroxyl group in the diphenol.

[0012] In some specific embodiments, the acyl chloride includes aromatic diacyl chloride and aliphatic diacyl chloride, wherein the molar ratio of the aromatic diacyl chloride to the aliphatic diacyl chloride is 1:(1-1.5).

[0013] In this application, the preferred acyl chloride is a composition of aromatic diacyl chloride and aliphatic diacyl chloride in a molar ratio of 1:(1-1.5). The combination of the two is beneficial to further improve the high temperature resistance and flexibility of the epoxy resin cured with the active ester curing agent.

[0014] In some specific embodiments, the aromatic diacyl chloride is terephthaloyl chloride or isophthaloyl chloride.

[0015] In some specific embodiments, the aliphatic diacyl chloride is 1,8-dioctanoyl chloride.

[0016] In some specific embodiments, the amount of catalyst used is 0.2-0.5% of the weight of the diphenol.

[0017] In some specific embodiments, the catalyst is a composition of triethylamine and 4-dimethylaminopyridine in a weight ratio of 1:(3-4).

[0018] In this application, the catalyst is preferably a combination of triethylamine and 4-dimethylaminopyridine in a weight ratio of 1:(3-4), which is more conducive to overcoming the barrier of alkoxy groups adjacent to the phenolic hydroxyl group, and can increase the conversion rate of diphenol to more than 98%, which is beneficial to improving the yield of active ester curing agent.

[0019] Secondly, the preparation method of the active ester curing agent provided in this application adopts the following technical solution: A method for preparing an active ester curing agent includes the following steps: In an inert environment, the diphenol is dissolved in an anhydrous solvent to obtain a diphenol solution; The acyl chloride is dissolved in an anhydrous solvent to obtain an acyl chloride solution; Add the catalyst to the diphenol solution and stir until it is evenly dispersed. Then add the acyl chloride solution to the diphenol solution while maintaining the temperature at -5~0℃. After the acyl chloride solution is added, gradually raise the temperature to room temperature and react for 2-4 hours. Then raise the temperature to 40-50℃ and react for 4-8 hours. Remove impurities and purify to obtain the active ester curing agent.

[0020] This application uses the above method to prepare an active ester curing agent. By controlling the addition temperature of acyl chloride and the reaction temperature, the occurrence of acyl chloride side reactions can be reduced, the conversion rate of diphenols can be improved, and the yield of active ester curing agent can be increased.

[0021] In some specific embodiments, the anhydrous solvent is either dichloromethane or tetrahydrofuran.

[0022] Thirdly, the epoxy resin composition provided in this application adopts the following technical solution: An epoxy resin composition includes an epoxy resin, an active ester curing agent, a curing accelerator, inorganic pigments and fillers, and a dispersant; wherein the active ester curing agent is any one of the active ester curing agents described above.

[0023] In some specific embodiments, the weight ratio of the epoxy resin, reactive ester curing agent, curing accelerator, inorganic pigments and fillers, and dispersant is (40-50):(55-65):(0.2-0.4):(85-90):50.

[0024] The epoxy resin composition of this application combines high dielectric properties, low temperature resistance, high temperature resistance, and low moisture absorption, making it particularly suitable for electronic packaging materials.

[0025] In summary, this application includes at least the following beneficial technical effects: (1) The active ester curing agent of this application is prepared by acylation reaction of diphenol and acyl chloride under the catalysis of a catalyst. Unlike existing active ester curing agents, the diphenol used in this application contains phenolic hydroxyl, alkoxy, and organosilicon segments. The application specifically limits the selection of R to alkylene with 1-5 carbon atoms, alkoxy to methoxy or ethoxy, and the range of n values ​​for dimethylsiloxane segment. The active ester curing agent is prepared by reacting the diphenol with acyl chloride with this specific structure. The active ester curing agent has good compatibility with epoxy resin. When used in the curing of epoxy resin, the curing rate is moderate, the internal stress is small, and the film quality can be improved. At the same time, it can reduce the dielectric constant and dielectric loss of epoxy resin and ensure the low temperature resistance, high heat resistance, low moisture absorption and flexibility of epoxy resin. It is suitable for the field of electronic packaging.

[0026] (2) In this application, the preferred molar ratio of the phenolic hydroxyl group in the diphenol to the acyl chloride group in the acyl chloride is 1:(1.02-1.05). An appropriate excess of acyl chloride is beneficial to improving the conversion rate of the phenolic hydroxyl group in the diphenol.

[0027] (3) In this application, the catalyst is preferably a combination of triethylamine and 4-dimethylaminopyridine in a weight ratio of 1:(3-4), which is more conducive to overcoming the barrier of alkoxy groups adjacent to phenolic hydroxyl groups, and can increase the conversion rate of diphenols to more than 98%, which is beneficial to improving the yield of active ester curing agent.

[0028] (4) The active ester curing agent prepared by the above method can reduce the occurrence of acyl chloride side reactions by controlling the addition temperature of acyl chloride and the reaction temperature, thereby improving the conversion rate of diphenol and the yield of active ester curing agent.

[0029] (5) The epoxy resin composition of this application combines high dielectric properties, low temperature resistance, high temperature resistance and low moisture absorption, making it particularly suitable for electronic packaging materials. Detailed Implementation

[0030] The following section provides further explanation of this application in conjunction with specific experiments. Example

[0031]

Example 1

[0032] In this embodiment, the preparation method of the active ester curing agent includes the following steps: S1. Under a nitrogen atmosphere, dissolve the diphenol in tetrahydrofuran to obtain a diphenol solution. S2. Dissolve isophthaloyl chloride and 1,8-dioctanoyl chloride in tetrahydrofuran to obtain an acyl chloride solution; S3. Add triethylamine and 4-dimethylaminopyridine to the diphenol solution and stir until uniformly dispersed. Then add the acyl chloride solution to the diphenol solution while maintaining the temperature at -5℃. After the acyl chloride solution is added, gradually raise the temperature to 25℃ and react for 2 hours. Then raise the temperature to 45℃ and react for 6 hours. Remove impurities and purify to obtain the active ester curing agent.

[0033]

Example 2

[0034]

Example 3

[0035]

Example 4

[0036]

Example 5

[0037] Comparative Example Comparative Example 1 An active ester curing agent, differing from [Example 1] in that: the general structural formula of the diphenol is as follows: ; R stands for propylidene, and n takes the value 50.

[0038] Comparative Example 2 An active ester curing agent, differing from [Example 1] in that: the general structural formula of the diphenol is as follows: ; R is propylene, R1 is methyl, and n is 65.

[0039] Before purification, samples were taken from each example and comparative example to detect the phenolic hydroxyl content, and the conversion rate of diphenols in each example and comparative example was calculated and recorded in Table 1 below: Table 1

[0040] Based on the test data in Examples 1 and 3-5 in Table 1, it can be seen that in this application, the catalyst is a combination of triethylamine and 4-dimethylaminopyridine in a weight ratio of 1:(3-4), which is beneficial to increase the conversion rate of diphenol to more than 98% and can improve the yield of active ester curing agent.

[0041] Application examples

Application Example 1

[0042]

Application Example 2

[0043]

Application Example 3

[0044]

Application Example 4

[0045]

Application Example 5

[0046] Comparative application examples

Comparative Application Example 1

[0047]

Comparative Application Example 2

[0048] Performance testing The epoxy resin compositions from the above application examples and comparative application examples were coated onto PET release films, pre-baked at 65-75℃ for 10 min, and then cured at 170-180℃ for 60 min to obtain composite films. The composite films were tested for the following performance parameters, and the test results are recorded in Table 2 below: 1. Dart Impact Strength: The dart impact strength of the composite film before and after cryogenic treatment was tested using ASTM D1709, and the difference in dart impact strength before and after cryogenic treatment was recorded. The cryogenic treatment procedure is as follows: The composite film was placed in an environment of -10℃ for 168 hours, and then removed and allowed to return to room temperature naturally.

[0049] (2) Dielectric performance test: The dielectric constant (Dk) and dielectric loss (Df) of the composite film were tested at 10 GHz using the method of IEC 61189-2-721.

[0050] (3) Glass transition temperature: The glass transition temperature of the composite film was tested using the method in IPC-TM-650 2.4.24.4.

[0051] (4) Water absorption test: The water absorption of the composite film was tested using the method in 2.6.2.1 of IPC-TM-650.

[0052] (5) Surface roughness Ra: Roughness was tested using a Mitutoyo SJ-410 surface roughness tester from Japan.

[0053] Table 2

[0054] Based on the test data in Table 2, it can be seen that, due to the compatibility between the active ester curing agent and the epoxy resin, the low-temperature toughness, high-temperature resistance, and surface smoothness of the composite film prepared in Application Examples 1-2 are worse than those of the composite film prepared in Application Example 1.

[0055] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. An active ester curing agent, characterized in that: The diphenol is prepared by acylation reaction of a diphenol and an acyl chloride in the presence of a catalyst. The general structural formula of the diphenol is as follows: ； Wherein, R is selected as an alkylene group containing 1-5 carbon atoms, R1 is selected as methyl or ethyl, and n is an integer ranging from 35 to 50.

2. The active ester curing agent according to claim 1, characterized in that: R is selected as an alkylene group containing 1-5 carbon atoms, R1 is selected as a methyl group, and n is an integer ranging from 45 to 50.

3. The active ester curing agent according to claim 1, characterized in that: The molar ratio of the phenolic hydroxyl group in the diphenolic substance to the acyl chloride group in the acyl chloride is 1:(1.02-1.05).

4. The active ester curing agent according to claim 3, characterized in that: The acyl chlorides include aromatic diacyl chlorides and aliphatic diacyl chlorides, and the molar ratio of the aromatic diacyl chlorides to the aliphatic diacyl chlorides is 1:(1-1.5).

5. The active ester curing agent according to claim 4, characterized in that: The aromatic diacyl chloride is terephthaloyl chloride or isophthaloyl chloride.

6. The active ester curing agent according to claim 4, characterized in that: The aliphatic diacyl chloride is 1,8-dioctanoyl chloride.

7. The active ester curing agent according to claim 1, characterized in that: The amount of catalyst used is 0.2-0.5% of the weight of the diphenol.

8. The active ester curing agent according to claim 7, characterized in that: The catalyst is a combination of triethylamine and 4-dimethylaminopyridine in a weight ratio of 1:(3-4).

9. A method for preparing an active ester curing agent as described in any one of claims 1-8, characterized in that, Includes the following steps: In an inert environment, the diphenol is dissolved in an anhydrous solvent to obtain a diphenol solution; The acyl chloride is dissolved in an anhydrous solvent to obtain an acyl chloride solution; Add the catalyst to the diphenol solution and stir until it is evenly dispersed. Then add the acyl chloride solution to the diphenol solution while maintaining the temperature at -5~0℃. After the acyl chloride solution is added, gradually raise the temperature to room temperature and react for 2-4 hours. Then raise the temperature to 40-50℃ and react for 4-8 hours. Remove impurities and purify to obtain the active ester curing agent.

10. An epoxy resin composition, characterized in that: Including the active ester curing agent as described in any one of claims 1-8 of this application.

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