An epoxy resin prepreg with rapid secondary curing and its preparation method

Abstract

The present invention discloses an epoxy resin prepreg with rapid secondary curing and a preparation method thereof. The epoxy resin composition includes: ordinary epoxy resin, weather-resistant modified phenolic resin, flexible modified epoxy resin, curing agent, modified catalyst, and toluene. According to the characteristics of the epoxy resin, the present invention adds modified epoxy resin and additives. The prepared epoxy resin prepreg can be rapidly secondarily cured, facilitating secondary mold processing and forming. Moreover, after the secondary forming of the prepreg, the flame retardancy reaches UL94V-0 level, and it has advantages such as high flexibility, dimensional stability, and heat resistance, solving the problem in the prior art that it cannot simultaneously meet the requirements of good flexibility and rapid curing of the laminate. The present invention adopts staged reaction of epoxy resin, adding modified resin for reaction in sequence by stages and adding a catalyst to improve the crosslinking reaction of the epoxy functional groups of the epoxy resin at different stages, enabling its product to have excellent properties and rapid reaction at special temperature stages.

Description

Technical Field

[0001] The present invention belongs to the technical field of prepreg preparation, and more specifically, the present invention relates to an epoxy prepreg capable of rapid secondary curing and a preparation method thereof. Background Art

[0002] The prepreg, also known as "PP sheet", is one of the main materials for producing laminates, mainly composed of reinforcing materials and adhesives. Currently, glass fiber cloth is commonly used as the reinforcing material, and an epoxy resin composition is used as the adhesive. Flexibility, heat resistance, alkali resistance, and flame retardancy are important performance indicators of the adhesive. Due to its own structural reasons, epoxy resin has disadvantages such as poor heat resistance and poor flexibility. Therefore, solving the above problems of epoxy resin has become the research focus and hotspot in the field of electronic packaging. Secondly, currently, the high-temperature curing time of conventional epoxy prepregs is relatively long, requiring more than 30 minutes at temperatures above 160°C, which is not convenient for rapid mold processing. Therefore, developing an epoxy resin composition capable of rapid secondary curing has important application value. Summary of the Invention

[0003] An object of the present invention is to solve at least the above problems and / or defects and provide at least the advantages described hereinafter.

[0004] To achieve these objects and other advantages of the present invention, there is provided an epoxy prepreg capable of rapid secondary curing, the epoxy prepreg comprising a substrate and an epoxy resin composition loaded on the substrate;

[0005] The substrate comprises glass fiber cloth;

[0006] The epoxy resin composition is composed of the following components in parts by weight: 40 - 60 parts of ordinary epoxy resin, 10 - 15 parts of weather-resistant modified phenolic resin, 5 - 10 parts of flexible modified epoxy resin, 8 - 14 parts of curing agent, 0.05 - 0.1 part of modified catalyst, and 5 - 15 parts of toluene.

[0007] Preferably, the ordinary epoxy resin is DER383 resin; the weather-resistant modified phenolic resin is 8020 resin; the flexible modified epoxy resin is 240A40 resin.

[0008] Preferably, the curing agent is 4,4-diaminodiphenyl sulfone.

[0009] Preferably, the modified catalyst is an imidazole catalyst.

[0010] A preparation method of an epoxy prepreg capable of rapid secondary curing as described above comprises the following steps:

[0011] Step 1: Add ordinary epoxy resin and weather-resistant modified phenolic resin melted in a hot bath into a reaction kettle, stir evenly, heat to a specified temperature, then add a curing agent and toluene, pressurize and heat for insulation for 20 - 30 min. Take a sample and drop it on a colorless glass plate for observation. When it is completely transparent, stop the insulation.

[0012] Step 2: Wait for the reaction kettle to cool down to a certain temperature, add flexible modified epoxy resin, stir evenly, then add a modified catalyst, and continue stirring. Take a sample to test the gel time at 150 °C. If the gel time is greater than 300 s, add the modified catalyst until the gel time is 250 ± 50 s to obtain an epoxy resin adhesive.

[0013] Step 3: Add cyclohexanone to adjust the viscosity of the epoxy resin adhesive obtained in Step 2, and use a vertical gluing machine for gluing and coating, then heat and dry to obtain a rapidly secondarily cured epoxy resin prepreg.

[0014] Preferably, in Step 1, the specified temperature is 100 - 120 °C.

[0015] Preferably, in Step 1, the pressurized heating is as follows: under a pressure of 0.15 - 0.5 MPa, heat at a heating rate of 0.2 - 0.5 °C / min to 110 - 130 °C.

[0016] Preferably, in Step 2, wait for the reaction kettle to cool down to 40 - 60 °C; continue stirring for 100 - 140 min.

[0017] Preferably, in Step 3, adjust the viscosity to 50 ± 15 s (20 °C); the gluing and coating speed is 50 - 150 cm / min; the heat drying temperature is 120 - 200 °C, and the time is 2 - 10 min; the resin content of the rapidly secondarily cured epoxy resin prepreg is 38 - 65%.

[0018] Application of a rapidly secondarily cured epoxy resin prepreg prepared by the preparation method as described above in a laminate.

[0019] The present invention has at least the following beneficial effects: According to the characteristics of epoxy resin, modified epoxy resin and additives are added in the present invention. The prepared epoxy resin prepreg can be rapidly secondarily cured, shortening the hot pressing time, facilitating secondary processing and forming, improving production efficiency, and the flame retardancy of the prepreg reaches UL94V - 0 level after secondary forming, having good flexibility, dimensional stability, heat resistance and other advantages, solving the problem in the prior art that it cannot simultaneously meet the requirements of good flexibility and rapid curing of the laminate; the present invention adopts a segmented reaction of epoxy resin, adding modified resins for reaction in sequence, adding catalysts, improving the crosslinking reaction of epoxy functional groups at different stages of epoxy resin, making its product have excellent performance and be able to react rapidly at special temperature stages.

[0020] Other advantages, objects and features of the present invention will be partly reflected by the following description, and partly will be understood by those skilled in the art through the research and practice of the present invention. Detailed implementation mode

[0021] The following further describes the present invention in detail with reference to embodiments, so that those skilled in the art can implement it according to the text of the specification.

[0022] It should be understood that the terms such as "having", "comprising" and "including" used herein do not exclude the presence or addition of one or more other elements or their combinations.

[0023] Embodiment 1

[0024] A kind of epoxy resin prepreg with fast secondary curing, comprising a glass fiber cloth and an epoxy resin composition, wherein the epoxy resin composition is composed of the following components in parts by weight: 50 parts of ordinary epoxy resin (DER383), 10 parts of weather-resistant modified phenolic resin (8020 resin), 5 parts of flexible modified epoxy resin (240A40), 8 parts of 4,4-diaminodiphenyl sulfone, 0.05 part of 2-methylimidazole, and 5 parts of toluene;

[0025] Its preparation method includes the following steps:

[0026] Step 1: Inject the pre-melted ordinary epoxy resin and weather-resistant modified phenolic resin into the reaction kettle and stir evenly, heat to 110 °C, then add 4,4-diaminodiphenyl sulfone and toluene, and under the pressure of 0.2 MPa, increase the temperature to 120 °C at a heating rate of 0.3 °C / min, keep warm for 30 min, take a sample and drop it on a colorless glass plate to observe. When it is completely transparent, stop keeping warm;

[0027] Step 2: Wait for the reaction kettle to cool down to 50 °C, add the flexible modified epoxy resin, stir evenly and then add 2-methylimidazole, continue to stir for 120 min, take a sample and test the gel time at 150 °C, and add 2-methylimidazole to make the gel time 250 s to obtain the epoxy resin adhesive;

[0028] Step 3: Add cyclohexanone to adjust the viscosity of the epoxy resin adhesive obtained in Step 2 to 50 s (20 °C), use a vertical sizing machine to coat the adhesive at a speed of 100 cm / min, and heat at 160 °C for 3 min to obtain the epoxy resin prepreg with fast secondary curing, and its resin content is 45%.

[0029] Embodiment 2

[0030] The epoxy resin composition of this example consists of the following components in parts by weight: 50 parts of ordinary epoxy resin (DER383), 12 parts of weather-resistant modified phenolic resin (8020 resin), 8 parts of flexible modified epoxy resin (240A40), 10 parts of 4,4-diaminodiphenyl sulfone, 0.08 part of 2-methylimidazole, and 10 parts of toluene; the remaining steps are the same as those in Example 1.

[0031] Example 3

[0032] The epoxy resin composition of this example consists of the following components in parts by weight: 50 parts of ordinary epoxy resin (DER383), 15 parts of weather-resistant modified phenolic resin (8020 resin), 10 parts of flexible modified epoxy resin (240A40), 14 parts of 4,4-diaminodiphenyl sulfone, 0.1 part of 2-methylimidazole, and 15 parts of toluene; the remaining steps are the same as those in Example 1.

[0033] According to IPC-TM-650, the properties of the rapidly secondarily cured epoxy resin prepregs prepared in Examples 1 to 3 were tested. Four prepregs were laminated and hot-pressed at 160 °C and 2 MPa to form a laminate. The results of the property tests are shown in Table 1. It can be seen that the epoxy resin prepregs prepared by the present invention can be rapidly secondarily cured, with a curing time of 4 to 6 minutes, which can effectively shorten the lamination time to ≤ 7 minutes, and the obtained laminate has excellent flame retardancy, flexibility, dimensional stability, and heat resistance.

[0034] Table 1

[0035]

[0036] Comparative Example 1

[0037] An epoxy resin prepreg includes a glass fiber cloth and an epoxy resin composition. The epoxy resin composition consists of the following components in parts by weight: 55 parts of ordinary epoxy resin (DER383), 10 parts of flexible modified epoxy resin (240A40), 8 parts of 4,4-diaminodiphenyl sulfone, 0.05 part of 2-methylimidazole, and 5 parts of toluene. The remaining method is the same as that in Example 1.

[0038] Comparative Example 2

[0039] An epoxy resin prepreg includes a glass fiber cloth and an epoxy resin composition. The epoxy resin composition consists of the following components in parts by weight: 53 parts of ordinary epoxy resin (DER383), 12 parts of weather-resistant modified phenolic resin (8020 resin), 8 parts of 4,4-diaminodiphenyl sulfone, 0.05 part of 2-methylimidazole, and 5 parts of toluene. The remaining method is the same as that in Example 1.

[0040] Four epoxy resin prepregs prepared in Comparative Examples 1-2 were laminated respectively, and hot-pressed at 160 °C and 2 MPa to form a laminate. The performance test results are shown in Table 2. The secondary curing time of the epoxy resin prepregs prepared in Comparative Examples 1-2 was longer than that in Examples 1-3, with the curing time being 15-30 min, and the lamination time was correspondingly extended to >20 min. In addition, the flexibility, heat resistance and dimensional stability of the epoxy resin prepregs prepared in Comparative Examples 1-2 were also reduced.

[0041] Table 2

[0042]

[0043] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalent scope, the present invention is not limited to the specific details and the embodiments shown and described herein.

Claims

1. A semi-cured epoxy resin sheet with fast secondary curing, characterized in that, The epoxy resin prepreg includes a substrate and an epoxy resin composition loaded on the substrate; The substrate is one or more of glass fiber, carbon fiber, and silicon carbide fiber; The epoxy resin composition is composed of the following components in parts by weight: 40-60 parts of ordinary epoxy resin, 10-15 parts of weather-resistant modified phenolic resin, 5-10 parts of flexible modified epoxy resin, 8-14 parts of curing agent, 0.05-0.1 part of modified catalyst, and 5-15 parts of toluene; The ordinary epoxy resin is DER383 resin; the weather-resistant modified phenolic resin is 8020 resin; the flexible modified epoxy resin is 240A40 resin; The modified catalyst is 2-methylimidazole.

2. The epoxy resin prepreg with fast secondary curing according to claim 1, wherein The curing agent is 4,4-diaminodiphenyl sulfone.

3. The preparation method of a fast secondary-curing epoxy resin prepreg as claimed in claim 1, characterized in that, It includes the following steps: Step 1: Add the ordinary epoxy resin and the weather-resistant modified phenolic resin pre-melted in a hot bath into a reaction kettle, stir evenly, heat to a specified temperature, then add the curing agent and toluene, pressurize and heat to keep warm for 20-30 min, take a sample and drop it on a colorless glass plate to observe. When it is completely transparent, stop keeping warm; Step 2: Wait for the reaction kettle to cool down to a certain temperature, add the flexible modified epoxy resin, stir evenly and then add the modified catalyst, continue to stir, take a sample and test the gel time at 150 °C. If the gel time is greater than 300 s, add the modified catalyst until the gel time is 250±50 s to obtain an epoxy resin adhesive; Step 3: Add cyclohexanone to adjust the viscosity of the epoxy resin adhesive obtained in Step 2, perform sizing and coating using a vertical sizing machine, heat and dry to obtain a rapidly secondarily cured epoxy resin prepreg.

4. The preparation method of a fast secondary-curing epoxy resin prepreg according to claim 3, characterized in that, In Step 1, the specified temperature is 100-120 °C.

5. The preparation method of a fast secondary-cured epoxy resin prepreg according to claim 3, wherein, In Step 1, the pressurized heating is: under a pressure of 0.15-0.5 MPa, heat up to 110-130 °C at a heating rate of 0.2-0.5 °C / min.

6. The preparation method of a fast secondary-curing epoxy resin prepreg according to claim 3, characterized in that, In Step 2, wait for the reaction kettle to cool down to 40-60 °C; continue to stir for 100-140 min.

7. The preparation method of a fast secondary curing epoxy resin prepreg according to claim 3, characterized in that, In Step 3, adjust the viscosity to 50±15 s at 20 °C; the speed of sizing and coating is 50-150 cm / min; the heating and drying temperature is 120-200 °C, and the time is 2-10 min; the resin content of the rapidly secondarily cured epoxy resin prepreg is 38-65%.

8. Application of a rapidly secondarily cured epoxy resin prepreg prepared by the preparation method according to any one of claims 3-7 in the preparation of a copper clad laminate or a laminated board.

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