Negative CTE polyimide composite material and preparation method thereof
By using raw materials such as phenylatic acid dianhydride, benzine, 1,3,5-tris(4-aminophenoxy)benzene and modified thermoplastic elastomer, polyimide composite materials with negative thermal expansion coefficients are prepared, which solves the problem of mismatch in thermal expansion coefficients of the packaging materials, achieves the balance of rigidity and toughness of the material, and improves the packaging stability and service life of the sensor.
Patent Information
- Application Number
- CN202510506036.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-22
- Publication Date
- 2025-07-25
AI Technical Summary
The existing polyimide packaging materials are mismatched in high-precision sensors, resulting in layering and cracking of the packaging process, affecting the normal operation and service life of electronic components.
The polyimide composite material with negative thermal expansion coefficient is prepared by forming a rigid rod-shaped linear backbone structure and introducing hydroxyl polar functional groups, combined with the modified thermoplastic elastomer, polyimide composite material with negative thermal expansion coefficient is prepared to enhance the rigidity and toughness of the material and reduce the thermal expansion coefficient.
It effectively reduces the thermal expansion coefficient of the material, improves the toughness and impact resistance of polyimide, improves compatibility and interface adhesion, and ensures the stability and service life of the packaging material.
Smart Images
Figure BDA0005369802560000091
Abstract
Description
Technical Field
[0001] This application relates to the technical field of sensor packaging materials, and more specifically, it relates to a negative CTE polyimide composite material and a preparation method thereof. Background Art
[0002] With the rapid development of modern technology, high-precision sensors have been widely used in many fields. High-precision sensors are the core components for realizing intelligent perception and data collection of devices. In the aerospace field, they are used to monitor various parameters of aircraft to ensure flight safety and performance optimization. In the automotive electronics field, sensors are used to monitor the operating status of vehicles in real time, improving driving safety and comfort.
[0003] The selection of packaging materials is crucial for the overall performance of sensors. Commonly used packaging materials in the market currently include polyimide because polyimide has excellent high and low temperature resistance, excellent insulation performance and mechanical properties, as well as good processability. With the rapid development of technology, the precision of sensors is getting higher and higher, so the requirements for the stability of packaging materials are also becoming more and more stringent.
[0004] The coefficient of thermal expansion (CTE) is one of the most critical performance indicators affecting the stability of packaging materials. The thermal expansion coefficient of conventional polyimide is above 30×10 -6 / °C, while the thermal expansion coefficient of copper foil, for example, which is compounded with or in contact with polyimide film in a circuit board, is about 17×10 -6 / °C, and the thermal expansion coefficient of silicon wafers is even only (4 - 5)×10 -6 / °C. Severe mismatch in thermal expansion coefficients will cause delamination and cracking of the packaging material during the heat treatment in the packaging process or during the use of the circuit, which will not only affect the normal operation of electronic components but also reduce their service life. Summary of the Invention
[0005] In order to be able to improve the defect that the thermal expansion coefficient may not match when polyimide is used as a packaging material, this application provides a negative CTE polyimide composite material and a preparation method thereof.
[0006] In the first aspect, a negative CTE polyimide composite material provided by this application adopts the following technical solution:
[0007] A negative CTE polyimide composite material, comprising the following raw materials: 25 - 35 g of pyromellitic dianhydride, 15 - 19 g of benzidine, 15 - 22 g of 1,3,5-tris(4-aminophenoxy)benzene, 15 - 25 g of modified thermoplastic elastomer, and 450 - 550 ml of N-methylpyrrolidone.
[0008] Since pyromellitic dianhydride is a commonly used dianhydride monomer with high reactivity and a rigid structure, it can form a rigid rod-like linear main chain structure. The presence of the rigid rod-like linear main chain structure is conducive to achieving a high degree of in-plane orientation of the polyimide molecular chains, thereby reducing the thermal expansion coefficient of the material. Benzidine is a rigid diamine monomer that can react with pyromellitic dianhydride to form a highly rigid polyimide chain, further enhancing the rigidity and orientation of the polyimide molecular chains, and contributing to the realization of the negative thermal expansion coefficient property. 1,3,5-Tris(4-aminophenoxy)benzene is a triamine monomer with large-volume substituents, and the presence of the substituents makes the polyimide exhibit an amorphous state.
[0009] In order to achieve the property of negative thermal expansion coefficient, polyimide has a highly rigid molecular structure, which may lead to an increase in the brittleness of the material and a reduction in its impact resistance. The flexible chain segments of the modified thermoplastic elastomer help to release the internal stress of the material and reduce the internal stress generated during processing and use, thereby improving the toughness and impact resistance of polyimide. At the same time, the amount of the modified thermoplastic elastomer added in this scheme is not likely to affect the property of the negative thermal expansion coefficient of polyimide.
[0010] Preferably, the modified thermoplastic elastomer is introduced with polar functional groups, and the polar functional groups are hydroxyl functional groups.
[0011] Since thermoplastic elastomers are usually composed of hard segments and soft segments, this structure is prone to phase separation, and the intermolecular interaction with other materials is weak. Moreover, the molecular weight distribution of thermoplastic elastomers is relatively wide, and the molecular weight difference will also cause phase separation, affecting the compatibility. Therefore, introducing hydroxyl polar functional groups on the thermoplastic elastomer can form hydrogen bonds with polar groups in other materials, enhance the intermolecular force, and thus enhance the interfacial adhesion and improve the compatibility.
[0012] Preferably, the modified thermoplastic elastomer comprises the following raw materials in parts by mass: 20-30 parts of polyphenylene ether, 55-65 parts of modified styrene-ethylene / butylene-styrene block copolymer, and 10-20 parts of ethylene-propylene-hexene terpolymer.
[0013] Since polyphenylene ether has excellent mechanical properties, heat resistance, and dimensional stability, it is conducive to improving the overall strength, heat resistance, and dimensional stability of the material and is suitable for high-temperature environments. The modified styrene-ethylene / butylene-styrene block copolymer has good elasticity, which is conducive to enhancing the flexibility of the material. The ethylene-propylene-hexene terpolymer has good impact resistance, which is conducive to improving the impact resistance of the material. Moreover, the dosage of the above raw materials is not likely to affect the property of polyimide to achieve a negative thermal expansion coefficient.
[0014] Preferably, the preparation method of the modified thermoplastic elastomer: Weigh 20-30 parts of polyphenylene ether and 55-65 parts of modified styrene-ethylene / butene-styrene block copolymer, dry the materials in an oven at 70-90 °C for 1-3 h, then add 10-20 parts of ethylene-propylene-hexene terpolymer, and stir at high speed for 2-4 min to obtain a uniformly dispersed mixture. The mixture is mixed and kneaded by a twin-screw extruder, and the extruded material is cooled and pelletized by water, and then dried in an oven at 70-90 °C for 3-5 h to obtain the modified thermoplastic elastomer.
[0015] Preferably, the modified styrene-ethylene / butene-styrene block copolymer comprises the following raw materials: 50-60 g of modified styrene-butadiene-styrene block copolymer, 0.5-1.5 g of nickel naphthenate, 0.5-1.5 g of triisobutylaluminum, and 100-200 ml of absolute ethanol.
[0016] Since the modified styrene-butadiene-styrene block copolymer is composed of alternating styrene and butadiene, and butadiene has a highly flexible molecular chain, the modified styrene-butadiene-styrene block copolymer has good elasticity, thereby improving the flexibility of the material. Nickel naphthenate, as a catalyst, can effectively promote the hydrogenation reaction and improve the reaction efficiency. Triisobutylaluminum, as a co-catalyst, acts synergistically with nickel naphthenate to further improve the efficiency and selectivity of the hydrogenation reaction. Absolute ethanol, as a coagulant, can effectively separate and purify the reaction products.
[0017] Preferably, the preparation method of the modified styrene-ethylene / butene-styrene block copolymer: Add 0.5-1.5 g of nickel naphthenate to an aging kettle evacuated with high-purity nitrogen, add 0.5-1.5 g of triisobutylaluminum while stirring, age at 50-70 °C for 1-2 h, and then add it to a premixing kettle containing 50-60 g of modified styrene-butadiene-styrene block copolymer evacuated with nitrogen for stirring. After stirring evenly, transfer it to a reaction kettle for hydrogenation reaction, and then coagulate with 100-200 ml of absolute ethanol and dry it in a vacuum oven at 30-50 °C until the mass is constant to obtain the modified styrene-ethylene / butene-styrene block copolymer.
[0018] Preferably, the modified styrene-butadiene-styrene block copolymer comprises the following raw materials: 300-500 ml of cyclohexane, 10-24 g of styrene, 0.1-0.3 g of butyllithium, 35-45 g of butadiene, 0.5-1.5 g of ethylene oxide.
[0019] Since ethylene oxide is a three-membered cyclic ether with a highly reactive epoxy group, the epoxy group is prone to ring opening during the reaction to form a hydroxyl polar functional group, thereby enabling the introduction of a hydroxyl polar functional group onto the styrene-butadiene-styrene block copolymer, thus improving the compatibility and interfacial adhesion of the material.
[0020] Preferably, the preparation method of the modified styrene-butadiene-styrene block copolymer is as follows: Add 300-500 ml of cyclohexane, 6-15 g of styrene and 0.1-0.3 g of butyllithium into a reaction kettle, react at 60-70 °C for 25-35 min, then add 35-45 g of butadiene, react at 50-70 °C for 55-65 min, then add 4-9 g of styrene, react at 60-70 °C for 30-50 min, and finally add 0.5-1.5 g of ethylene oxide, react at 55-65 °C for 30-50 min. After the reaction is completed, use hydrogen to terminate the reaction to obtain the modified styrene-butadiene-styrene block copolymer.
[0021] In a second aspect, the present application provides a method for preparing a negative CTE polyimide composite material, adopting the following technical solution:
[0022] A method for preparing a negative CTE polyimide composite material includes the following steps:
[0023] S1: Weigh 25-35 g of pyromellitic dianhydride and 15-19 g of benzidine, add them to 450-550 ml of N-methylpyrrolidone and react for 0.5-1.5 h. Then, sequentially add 15-22 g of 1,3,5-tris(4-aminophenoxy)benzene and 15-25 g of modified thermoplastic elastomer, heat with an oil bath to 60-70 °C and continuously react for 7-9 h.
[0024] In summary, the present application has the following beneficial effects:
[0025] 1. Since pyromellitic dianhydride is a commonly used dianhydride monomer with high reactivity and a rigid structure, it can form a rigid rod-like linear main chain structure. The existence of the rigid rod-like linear main chain structure is beneficial to achieving a high degree of in-plane orientation of the polyimide molecular chain, thereby reducing the thermal expansion coefficient of the material. Benzidine is a rigid diamine monomer that can react with pyromellitic dianhydride to form a highly rigid polyimide chain, further enhancing the rigidity and orientation of the polyimide molecular chain, and contributing to achieving the negative thermal expansion coefficient characteristic. 1,3,5-tris(4-aminophenoxy)benzene is a triamine monomer with large-volume substituents, and the presence of the substituents makes the polyimide amorphous.
[0026] In order to achieve the characteristics of negative thermal expansion coefficient, polyimide has a highly rigid molecular structure, which may lead to an increase in the brittleness of the material and a decrease in its impact resistance. The flexible segments of the modified thermoplastic elastomer help to release the internal stress of the material and reduce the internal stress generated during processing and use, thereby improving the toughness and impact resistance of polyimide. At the same time, the amount of the modified thermoplastic elastomer added in this solution is not likely to affect the characteristics of the negative thermal expansion coefficient of polyimide.
[0027] 2. Since thermoplastic elastomers are usually composed of hard segments and soft segments, this structure is prone to phase separation, and the intermolecular interaction with other materials is weak. Moreover, the molecular weight distribution of thermoplastic elastomers is relatively wide, and the molecular weight difference will also lead to phase separation, affecting compatibility. Therefore, introducing hydroxyl polar functional groups onto thermoplastic elastomers can form hydrogen bonds with polar groups in other materials, enhancing intermolecular forces, thereby enhancing interfacial adhesion and improving compatibility.
[0028] 3. Since polyphenylene ether has excellent mechanical properties, heat resistance, and dimensional stability, it is beneficial to improve the overall strength, heat resistance, and dimensional stability of the composite material and is suitable for high-temperature environments. The modified styrene-ethylene / butene-styrene block copolymer has good elasticity, which is beneficial to enhancing the flexibility of the composite material. The ethylene-propylene-hexene terpolymer has good impact resistance, which is beneficial to improving the impact resistance of the composite material. Specific Embodiments
[0029] The following further elaborates on this application in combination with Examples 1 - 10 and Comparative Examples 1 - 3.
[0030] Raw Materials
[0031] Pyromellitic dianhydride CAS: 89 - 32 - 7; Benzidine CAS: 92 - 87 - 5; 1,3,5-Tris(4-aminophenoxy)benzene CAS: 102852 - 92 - 6; N-Methylpyrrolidone CAS: 872 - 50 - 4; Polyphenylene ether CAS: 31533 - 76 - 3; Ethylene-propylene-hexene terpolymer Suzhou Dow Import and Export Co., Ltd.; Nitrogen CAS: 7727 - 37 - 9; Nickel naphthenate CAS: 61788 - 71 - 4; Triisobutylaluminum CAS: 100 - 99 - 2; Absolute ethanol CAS: 64 - 17 - 5; Cyclohexane CAS: 110 - 82 - 7; Styrene CAS: 100 - 42 - 5; Butyllithium CAS: 109 - 72 - 8; Butadiene CAS: 106 - 99 - 0; Ethylene oxide CAS: 75 - 21 - 8; Hydrogen CAS: 1333 - 74 - 0.
[0032] Example 1
[0033] A negative CTE polyimide composite material, comprising the following raw materials: 30 g of pyromellitic dianhydride, 17 g of benzidine, 18.5 g of 1,3,5-tris(4-aminophenoxy)benzene, 20 g of a modified thermoplastic elastomer, and 500 ml of N-methylpyrrolidone.
[0034] Specifically, the preparation method of the negative CTE polyimide composite material comprises the following steps:
[0035] S1: Add 400 ml of cyclohexane, 10.5 g of styrene, and 0.2 g of butyllithium into a reaction kettle, react at 65 °C for 30 min, then add 40 g of butadiene, react at 60 °C for 60 min, then add 6.5 g of styrene, react at 65 °C for 40 min, and finally add 1 g of ethylene oxide, react at 60 °C for 40 min. After the reaction is completed, terminate the reaction with hydrogen to obtain a modified styrene-butadiene-styrene block copolymer.
[0036] S2: Add 1 g of nickel naphthenate into an aging kettle evacuated with high-purity nitrogen, add 1 g of triisobutylaluminum while stirring, age at 60 °C for 1.5 h, then add it into a premixing kettle containing 55 g of the modified styrene-butadiene-styrene block copolymer evacuated with nitrogen for stirring. After stirring evenly, pump it into a reaction kettle for hydrogenation reaction, then coagulate with 150 ml of absolute ethanol and dry it in a vacuum oven at 40 °C until the mass is constant to obtain a modified styrene-ethylene / butene-styrene block copolymer.
[0037] S3: Weigh 25 g of polyphenylene ether and 60 g of the modified styrene-ethylene / butene-styrene block copolymer, dry the materials in an oven at 80 °C for 2 h, then add 15 g of an ethylene-propylene-hexene terpolymer, stir at high speed for 3 min to obtain a uniformly dispersed mixture. Mix and knead the mixture through a twin-screw extruder, cut the extruded material with water cooling, and then dry it in an oven at 80 °C for 4 h to obtain a modified thermoplastic elastomer.
[0038] S4: Weigh 30 g of pyromellitic dianhydride and 17 g of benzidine, add them into 500 ml of N-methylpyrrolidone and react for 1 h, then successively add 18.5 g of 1,3,5-tris(4-aminophenoxy)benzene and 20 g of the modified thermoplastic elastomer, heat with an oil bath to 65 °C and continue to react for 8 h.
[0039] Examples 2 - Examples 3
[0040] The difference from Example 1 is that the addition amounts of the components of the negative CTE polyimide composite material are different, as specifically shown in Table 1.
[0041] Table 1 Addition amounts of components of the negative CTE polyimide composite material in Examples 1 - 3
[0042] Example 1 Example 2 Example 3 Pyromellitic dianhydride 30g 25g 35g Benzidine 17g 19g 15g 1,3,5-Tris(4-aminophenoxy)benzene 18.5g 22g 15g Modified thermoplastic elastomer 20g 15g 25g N-Methylpyrrolidone 500ml 450ml 550ml
[0043] Example 4
[0044] It is different from Example 1 in that pyromellitic dianhydride is replaced with a dibasic anhydride in the same addition amount.
[0045] Examples 5 - 6
[0046] It is different from Example 1 in that the addition amounts of the components of the modified thermoplastic elastomer are different, as specifically shown in Table 2.
[0047] Table 2 Addition amounts of the components of the modified thermoplastic elastomer in Example 1 and Examples 5 - 6 (g)
[0048] Example 1 Example 5 Example 6 Polyphenylene ether 25 20 30 Modified styrene-ethylene / butylene-styrene block copolymer 60 65 55 Ethylene-propylene-hexene terpolymer 15 10 20
[0049] Examples 7 - 8
[0050] It is different from Example 1 in that the addition amounts of the components of the modified styrene - ethylene / butylene - styrene block copolymer are different, as specifically shown in Table 3.
[0051] Table 3 Addition amounts of the components of the modified styrene - ethylene / butylene - styrene block copolymer in Example 1 and Examples 7 - 8
[0052] Example 1 Example 7 Example 8 Modified styrene-butadiene-styrene block copolymer 55g 60g 50g Nickel naphthenate 1g 1.5g 0.5g Triisobutylaluminum 1g 0.5g 1.5g Absolute ethanol 150ml 100ml 200ml
[0053] Examples 9 - 10
[0054] It is different from Example 1 in that the addition amounts of the components of the modified styrene - butadiene - styrene block copolymer are different, as specifically shown in Table 4.
[0055] Table 4 Addition amounts of the components of the modified styrene - butadiene - styrene block copolymer in Example 1 and Examples 9 - 10
[0056] Example 1 Example 7 Example 8 Cyclohexane 400ml 300ml 500ml Styrene 17g 24g 10g Butyllithium 0.2g 0.1g 0.3g Butadiene 40g 35g 45g Ethylene oxide 1g 1.5g 0.5g
[0057] Comparative Example 1
[0058] It is different from Example 1 in that pyromellitic dianhydride is replaced with a monobasic anhydride in the same addition amount.
[0059] Comparative Example 2
[0060] It is different from Example 1 in that the modified thermoplastic elastomer is replaced with a thermoplastic elastomer in the same addition amount.
[0061] Comparative Example 3
[0062] It is different from Example 1 in that no modified thermoplastic elastomer is added.
[0063] Performance detection test
[0064] I. Coefficient of thermal expansion
[0065] Take three samples from Examples 1 - 10 and Comparative Examples 1 - 3 respectively, use a static mechanical analyzer, according to ASTM D696, in a nitrogen atmosphere, apply a load of 50 mN, and measure at a heating rate of 10 °C / min to test the coefficient of thermal expansion in the temperature range of 100 - 200 °C, and take the average value.
[0066] The test data is shown in Table 5.
[0067] Table 5 Coefficient of thermal expansion table of Examples 1 - 10 and Comparative Examples 1 - 3 (ppm / k)
[0068]
[0069]
[0070] II. Mechanical properties
[0071] Take three samples from Examples 1 - 10 and Comparative Examples 1 - 3 respectively, and measure the elongation at break of the samples according to the ASTM D882 standard, and take the average value.
[0072] The test data is shown in Table 6.
[0073] Table 6 Elongation at break rate table of Examples 1 - 10 and Comparative Examples 1 - 3 (%)
[0074] Elongation at break Example 1 35 Example 2 31 Example 3 28 Example 4 19 Example 5 23 Example 6 25 Example 7 27 Example 8 26 Example 9 22 Example 10 24 Comparative Example 1 15 Comparative Example 2 18 Comparative Example 3 8
[0075] Combining Example 1 and Comparative Example 1 and combining Table 5 and Table 6, it can be seen that, compared with Example 1, the coefficient of thermal expansion of Comparative Example 1 has a large increase, and the elongation at break of Comparative Example 1 also has a large decrease. Thus, it shows that, compared with adding a monobasic anhydride, adding pyromellitic dianhydride can effectively improve the elongation at break of polyimide and is beneficial to achieving the negative coefficient of thermal expansion of polyimide.
[0076] The reason is that pyromellitic dianhydride is a commonly used dianhydride monomer with high reactivity and a rigid structure, which can form a rigid rod-like linear main chain structure. The presence of the rigid rod-like linear main chain structure is conducive to achieving a high degree of in-plane orientation of the polyimide molecular chains, thereby reducing the thermal expansion coefficient of the material. Benzidine is a rigid diamine monomer that can react with pyromellitic dianhydride to form a highly rigid polyimide chain, further enhancing the rigidity and orientation of the polyimide molecular chains and contributing to the realization of the negative thermal expansion coefficient characteristic. 1,3,5-Tris(4-aminophenoxy)benzene is a triamine monomer with large-volume substituents, and the presence of the substituents makes the polyimide amorphous.
[0077] Combining Example 1 and Comparative Example 2 and referring to Table 5 and Table 6, it can be seen that compared with Example 1, the thermal expansion coefficient of Comparative Example 2 has increased significantly, and the elongation at break of Comparative Example 1 has also decreased significantly. This shows that compared with adding a conventional thermoplastic elastomer, adding a modified thermoplastic elastomer can effectively improve the elongation at break of polyimide and is conducive to achieving the negative expansion coefficient of polyimide.
[0078] The reason is that since thermoplastic elastomers are usually composed of hard segments and soft segments, this structure is prone to phase separation, and the intermolecular interaction with other materials is weak. Moreover, the molecular weight distribution of thermoplastic elastomers is relatively wide, and the molecular weight difference will also cause phase separation, affecting compatibility. Therefore, introducing hydroxyl polar functional groups onto the thermoplastic elastomer can form hydrogen bonds with polar groups in other materials, enhancing the intermolecular force, thereby enhancing the interfacial adhesion and improving compatibility.
[0079] Combining Example 1 and Comparative Example 3 and referring to Table 5 and Table 6, it can be seen that compared with Example 1, the thermal expansion coefficient of Comparative Example 3 has increased, and the elongation at break of Comparative Example 3 has decreased significantly. This shows that compared with not adding a modified thermoplastic elastomer, adding a modified thermoplastic elastomer can effectively improve the elongation at break of polyimide, and the added modified thermoplastic elastomer is not likely to affect the characteristic of polyimide to achieve a negative thermal expansion coefficient.
[0080] The reason is that since polyphenylene ether has excellent mechanical properties, heat resistance and dimensional stability, it is conducive to improving the overall strength, heat resistance and dimensional stability of the composite material and is suitable for high-temperature environments. The modified styrene-ethylene / butene-styrene block copolymer has good elasticity, which is conducive to enhancing the flexibility of the composite material. The ethylene-propylene-hexene terpolymer has good impact resistance, which is conducive to improving the impact resistance of the composite material.
[0081] Combining Example 1 with Examples 2 - 3 and Tables 5 and 6, it can be seen that, compared with Example 1, the coefficient of thermal expansion of Examples 2 and 3 has increased, and the elongation at break of Examples 2 and 3 has also decreased. This shows that the addition amounts of the components of the negative CTE polyimide composite affect the realization of the negative coefficient of thermal expansion of polyimide and the improvement of the elongation at break of polyimide, and the addition amounts of the components of the negative CTE polyimide composite in Example 1 are the optimal ones.
[0082] Combining Example 1 with Example 4 and Tables 5 and 6, it can be seen that, compared with Example 1, the coefficient of thermal expansion of Example 4 has increased significantly, and the elongation at break of Example 4 has also decreased significantly. This shows that, compared with the addition of dianhydride, the addition of pyromellitic dianhydride can effectively improve the elongation at break of polyimide and is also beneficial to the realization of the negative coefficient of thermal expansion of polyimide.
[0083] Combining Example 1 with Examples 5 - 6 and Tables 5 and 6, it can be seen that, compared with Example 1, the coefficient of thermal expansion of Examples 5 and 6 has increased, and the elongation at break of Examples 5 and 6 has also decreased. This shows that the addition amounts of the components of the modified thermoplastic elastomer affect the realization of the negative coefficient of thermal expansion of polyimide and the improvement of the elongation at break of polyimide, and the addition amounts of the components of the modified thermoplastic elastomer in Example 1 are the optimal ones.
[0084] Combining Example 1 with Examples 7 - 8 and Tables 5 and 6, it can be seen that, compared with Example 1, the coefficient of thermal expansion of Examples 7 and 8 has increased, and the elongation at break of Examples 7 and 8 has also decreased. This shows that the addition amounts of the components of the modified styrene - ethylene / butylene - styrene block copolymer affect the realization of the negative coefficient of thermal expansion of polyimide and the improvement of the elongation at break of polyimide, and the addition amounts of the components of the modified styrene - ethylene / butylene - styrene block copolymer in Example 1 are the optimal ones.
[0085] Combining Example 1 with Examples 9 - 10 and Tables 5 and 6, it can be seen that, compared with Example 1, the coefficient of thermal expansion of Examples 9 and 10 has increased, and the elongation at break of Examples 9 and 10 has also decreased. This shows that the addition amounts of the components of the modified styrene - ethylene / butylene - styrene block copolymer affect the realization of the negative coefficient of thermal expansion of polyimide and the improvement of the elongation at break of polyimide, and the addition amounts of the components of the modified styrene - ethylene / butylene - styrene block copolymer in Example 1 are the optimal ones.
[0086] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment that do not contribute creatively as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.
Claims
1. A negative CTE polyimide composite material, characterized in that, It includes the following raw materials: 25 - 35 g of pyromellitic dianhydride, 15 - 19 g of benzidine, 15 - 22 g of 1,3,5-tris(4-aminophenoxy)benzene, 15 - 25 g of modified thermoplastic elastomer, and 450 - 550 ml of N-methylpyrrolidone.
2. The negative CTE polyimide composite material according to claim 1, wherein: The modified thermoplastic elastomer is introduced with polar functional groups, and the polar functional group is a hydroxyl functional group.
3. The negative CTE polyimide composite material according to claim 2, wherein, The modified thermoplastic elastomer includes the following raw materials in parts by mass: 20 - 30 parts of polyphenylene ether, 55 - 65 parts of modified styrene-ethylene / butylene-styrene block copolymer, and 10 - 20 parts of ethylene-propylene-hexene terpolymer.
4. A negative CTE polyimide composite material according to claim 3, characterized in that, The preparation method of the modified thermoplastic elastomer: Weigh 20 - 30 parts of polyphenylene ether and 55 - 65 parts of modified styrene-ethylene / butylene-styrene block copolymer, dry the materials in an oven at 70 - 90 °C for 1 - 3 h, then add 10 - 20 parts of ethylene-propylene-hexene terpolymer, stir at high speed for 2 - 4 min to obtain a uniformly dispersed mixture. Mix and knead the mixture through a twin-screw extruder. After the material is extruded, it is cut into pellets by water cooling, and then dried in an oven at 70 - 90 °C for 3 - 5 h to obtain the modified thermoplastic elastomer.
5. A negative CTE polyimide composite material according to claim 4, characterized in that, The modified styrene-ethylene / butylene-styrene block copolymer includes the following raw materials: 50 - 60 g of modified styrene-butadiene-styrene block copolymer, 0.5 - 1.5 g of nickel naphthenate, 0.5 - 1.5 g of triisobutylaluminum, and 100 - 200 ml of absolute ethanol.
6. The negative CTE polyimide composite material according to claim 5, wherein The preparation method of the modified styrene-ethylene / butylene-styrene block copolymer: Add 0.5 - 1.5 g of nickel naphthenate to an aging kettle after evacuation with high-purity nitrogen, add 0.5 - 1.5 g of triisobutylaluminum while stirring, age at 50 - 70 °C for 1 - 2 h, then add it to a premixing kettle containing 50 - 60 g of modified styrene-butadiene-styrene block copolymer after evacuation with nitrogen for stirring. After stirring evenly, transfer it to a reaction kettle for hydrogenation reaction. Then, coagulate with 100 - 200 ml of absolute ethanol and dry it in a vacuum oven at 30 - 50 °C until the mass is constant to obtain the modified styrene-ethylene / butylene-styrene block copolymer.
7. A negative CTE polyimide composite material according to claim 6, wherein The modified styrene-butadiene-styrene block copolymer includes the following raw materials: 300 - 500 ml of cyclohexane, 10 - 24 g of styrene, 0.1 - 0.3 g of butyl lithium, 35 - 45 g of butadiene, 0.5 - 1.5 g of ethylene oxide.
8. A negative CTE polyimide composite material according to claim 7, characterized in that The preparation method of the modified styrene-butadiene-styrene block copolymer: Add 300 - 500 ml of cyclohexane, 6 - 15 g of styrene and 0.1 - 0.3 g of butyllithium into a reaction kettle, react at 60 - 70 °C for 25 - 35 min, then add 35 - 45 g of butadiene, react at 50 - 70 °C for 55 - 65 min, then add 4 - 9 g of styrene, react at 60 - 70 °C for 30 - 50 min, and finally add 0.5 - 1.5 g of ethylene oxide, react at 55 - 65 °C for 30 - 50 min. After the reaction is completed, use hydrogen to terminate the reaction, thus obtaining the modified styrene-butadiene-styrene block copolymer.
9. The preparation method of a negative CTE polyimide composite material according to any one of claims 1-8, characterized in that, It includes the following steps: S1: Weigh 25 - 35 g of pyromellitic dianhydride and 15 - 19 g of benzidine, add them into 450 - 550 ml of N-methylpyrrolidone and react for 0.5 - 1.5 h. Then, successively add 15 - 22 g of 1,3,5-tris(4-aminophenoxy)benzene and 15 - 25 g of modified thermoplastic elastomer, heat with an oil bath to 60 - 70 °C and continuously react for 7 - 9 h.