Low thermal expansion and recoverable polyimide resin and recovery method thereof

Abstract

The present invention provides a low thermal expansion and recoverable polyimide resin, which has a recoverable functional group and a rigid chemical structure, and thus can be easily recovered and used and has good dimensional stability. Therefore, the low-thermal-expansion and recoverable polyimide resin has the characteristics of rigidity, chemical resistance, low thermal expansion and recoverability; and a method for recovering the polyimide resin.

Description

Technical Field

[0001] The present invention relates to a low thermal expansion and recyclable polyimide resin and a method for preparing the same, in particular to a polyimide resin having advantages such as a wide applicable temperature range, chemical corrosion resistance, high strength, and recyclability, which can be repaired and recycled by controlling the temperature; and a method for recycling the polyimide resin is provided. Background Art

[0002] Polymers can be classified into two categories, thermoplastics and thermosets, according to their physical properties when heated. Thermosetting polymers are polymers that are cured immediately after synthesis and will not soften even when heated subsequently; in contrast, thermoplastic polymers will soften when heated after synthesis and curing and will solidify again when cooled. In addition, thermosetting polymers generally have better mechanical, thermal, and chemical properties and better dimensional stability than thermoplastic polymers. Therefore, they are widely used in applications that require use at high temperatures, or require high mechanical strength or chemical corrosion resistance, such as tires, circuit boards, etc., and can also be called thermosetting resins.

[0003] Thermosetting resin polymers can be applied in many fields. However, products made of conventional thermosetting resin polymers cannot be repaired when damaged or at the end of their life cycle and can only be discarded, resulting in a waste of resources. In addition, since waste thermosetting resin polymers are difficult to be naturally decomposed, they can currently only be disposed of by burying or incineration, thus causing serious environmental pollution.

[0004] Polyimide resin is an organic polymer material containing imide groups. It is mainly formed by the reaction of diamines and dianhydrides, and then polyimide polymers are formed by high-temperature cyclization and dehydration. Polyimide resin has excellent thermal stability and good mechanical, electrical, and chemical properties, and is widely used in various fields. In recent years, related industries such as semiconductors, electronics, and communications in China have developed vigorously, driving the domestic economic development, and the demand for electronic chemicals and materials has also increased day by day. Polyimide resin plays a very important role in electronic materials with its excellent properties. Especially in the electronic industry with strict material requirements, it has always been in the position of a key material, and its applications include high-temperature tapes, flexible circuit boards, photosensitive polyimide insulating layers for IC packaging, alignment films for LCDs, etc.

[0005] The previously used polyimide resin is usually not easily recyclable after being made into products for the sake of usability. Therefore, if the product is damaged or at the end of its life cycle, the polyimide resin product can only be discarded. Although there have been related studies published on repairable or recyclable polyimide resins, their heat resistance and chemical resistance are poor, which limits the application range of their products.

[0006] Therefore, it is an issue to be addressed to provide a polyimide resin that is recyclable, still has a certain degree of heat resistance and chemical resistance after recycling, improves the durability of products, can be recycled again, and achieves the goal of zero waste emissions upon recycling.

[0007] In summary, developing a polyimide resin that is rigid, chemical-resistant, heat-resistant, recyclable, and still has a certain degree of heat resistance and chemical resistance after recycling is a commercially valuable development goal. Summary of the Invention

[0008] The main objective of the present invention is to provide a low coefficient of thermal expansion and recyclable polyimide resin that is rigid, chemical-resistant, heat-resistant, recyclable, and still has a certain degree of heat resistance and chemical resistance after recycling.

[0009] Another objective of the present invention is to provide a method for recycling a low coefficient of thermal expansion and recyclable polyimide resin, which can recycle the polyimide resin in a low-temperature environment to achieve the goals of reducing resource waste and environmental pollution.

[0010] To address the above main objective, the present invention provides a low coefficient of thermal expansion and recyclable polyimide polymer resin, which comprises at least one unit as shown in Formula I: and at least one dianhydride unit wherein A is selected from the group consisting of the following groups: R is selected from the group consisting of the following groups: R 1 is selected from -CH 3 、-CH 2 CH 3 、or -CF 3 ; n is an integer greater than 1; and the dianhydride unit is selected from the group consisting of the following groups: 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, pyromellitic dianhydride, 4,4′-oxydiphthalic anhydride, bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic 2,3,5,6-dianhydride, dicyclohexyl-3,4,3′,4′-tetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride.

[0011] The present invention provides an embodiment, wherein the low thermal expansion and recyclable polyimide polymer resin comprises a unit of the following formula and a compound of formula 1, wherein n is an integer greater than 1, the molar ratio of formula 1 is about 80 - 95%, the molar ratio of formula 2 is about 5 - 20%, and the compound of formula 1 is different from formula 2.

[0012] The present invention provides an embodiment, wherein the low thermal expansion and recyclable polyimide polymer resin comprises a unit of the following formula and a compound of formula 1, wherein n is an integer greater than 1, the molar ratio of formula 1 is about 80 - 95%, the molar ratio of formula 3 is about 5 - 20%, and the compound of formula 1 is different from formula 3.

[0013] For another purpose, the present invention provides a method for recycling the low thermal expansion and recyclable polyimide resin as described above, which comprises: Performing a dissolution step of dissolving the low thermal expansion and recyclable polyimide resin in a polar aprotic solvent to obtain a polyimide recovery solution; and Performing a film-forming step of coating and baking the polyimide recovery solution to form a recovered polyimide film.

[0014] The present invention provides an embodiment, in the recovery method of the low thermal expansion and recyclable polyimide resin, the polar aprotic solvent is dimethylacetamide or N-methylpyrrolidone. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 : It is a flowchart of the steps of the recovery method of the low thermal expansion and recyclable polyimide resin of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] In order to have a further understanding and recognition of the structural features and achieved effects of the present invention, preferred embodiments and detailed descriptions are used as follows:

[0017] A low thermal expansion and recyclable polyimide resin of the present invention comprises at least one unit of the following formula: and at least one dianhydride unit; wherein A is selected from the group consisting of the following groups: R is selected from the group consisting of the following groups: R 1 is selected from -CH 3 、-CH 2 CH 3 、or -CF 3 , n is an integer greater than 1; and the dianhydride unit is selected from the group consisting of: 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, pyromellitic dianhydride, 4,4′-oxydiphthalic anhydride, bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic 2,3,5,6-dianhydride, dicyclohexyl-3,4,3′,4′-tetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride.

[0018] In one embodiment of the present invention, the low thermal expansion and recyclable polyimide resin preferably comprises a unit of the following formula and a unit of Formula 1 different from Formula 2, where n is an integer greater than 1. When the polyimide resin is polymerized, when Formula 1 is about 80-95% molar ratio and Formula 2 is about 5-20% molar ratio, the coefficient of thermal expansion (CTE) and glass transition temperature (Tg) of the polyimide resin at this time are optimal.

[0019] In another embodiment of the present invention, the low thermal expansion and recyclable polyimide resin preferably comprises a unit of the following formula. and a unit of Formula 1 different from Formula 3, where n is an integer greater than 1. When the polyimide resin is polymerized, when Formula 1 is about 80-95% molar ratio and Formula 3 is about 5-20% molar ratio, the coefficient of thermal expansion and glass transition temperature of the polyimide resin at this time are optimal.

[0020] The low thermal expansion and recyclable polyimide resin of the present invention can be recycled and reused after use. Please refer toFigure 1 , which is a schematic diagram of the steps of an embodiment of the recovery method of the present invention. The steps of the recovery method include:

[0021] Step S10: Dissolve the low thermal expansion and recyclable polyimide resin in a polar aprotic solvent to obtain a polyimide recovery solution; and

[0022] Step S20: Coating and baking the polyimide recovery solution into a film to form a recovered polyimide resin film.

[0023] When using this method to recover the low thermal expansion and recyclable polyimide resin, the solvent can be used to dissolve and recover at low temperature, and then the recovered polyimide resin solution is coated and baked into a film to form a recovered polyimide resin film again. For the recovered polyimide resin, its glass transition temperature and decomposition temperature (Td) are the same as those of the polyimide resin before recovery, and the recovery rate is greater than 90%. In step S10, the solvent used for dissolving and recovering the low thermal expansion and recyclable polyimide resin can be a polar aprotic solvent, preferably solvents such as DMAc (dimethylacetamide) and NMP (N-methylpyrrolidone).

[0024] The present invention will now be described in more detail with reference to the following examples, which are illustrative only and do not limit the scope of the present invention. Example 1 Synthesis of imine monomer (AZ):

[0025] Add 5.4 g of 4-aminoacetophenone (0.4 mol), 2.0 g of triethylamine (0.2 mol), and 4.0 grams of ethanol to the reaction flask. Then heat to 80 °C. After the reactants are completely dissolved in ethanol, add 2.7 g of hydrazine sulfate (0.2 mol) and reflux for 5 hours. Finally, precipitate the product by ice bath, filter, and wash the product with water and ethanol. Its monomer structure is as shown in Formula 1-1, and its NMR spectrum is 1H NMR (400 MHz, d6-DMSO): 7.6 (d, 4H), 6.30 (d, 2H), 2.29 (s, 6H). Example 2: Synthesis of imine monomer (AFZ):

[0026] Add 0.5 g of (4-Aminophenyl)-2,2,2-trifluoro-1-ethanone (0.5 mol), 0.8 g of triethylamine (2.5 mol), and 1.4 g of ethanol into a reaction flask. Then heat to 90 °C. After the reactants are completely dissolved in ethanol, add 0.17 g of hydrazine sulfate (0.5 mol), and reflux for 8 hours. Finally, precipitate the product by ice bath, filter it, and wash the product with water and ethanol. Its monomer structure is as shown in Formula 1-2 and its NMR spectrum is 1H NMR (400 MHz, d6-DMSO): 7.7 (d, 4H), 6.6 (d, 4H). Example 3: Synthesis of imine monomer (IAF-1):

[0027] Add 6.75 g of 4’-Aminoacetophenone (0.05 mol), 6.5 g of p-Phenylenediamine (0.06 mol), and 30 g of Toluene into a reaction flask. Then heat to 120 °C and reflux for 48 hours. After the reaction is completed, filter at room temperature, concentrate the filtrate to remove Toluene, and finally remove the solvent under high vacuum to obtain the product. Its monomer structure is as shown in Formula 1-3, and its structure is identified by NMR spectroscopy. Synthesis reaction of Polymer 1 in Example 4

[0028] First, put 1.00 mole of 4,4′-Oxydianiline (ODA) into a reaction flask, then pour in NMP (N-methylpyrrolidone) solvent to make the solid content of the solution 15-20%. After the above reactants are dissolved, add 1.00 mole of 6-FDA (4,4′-(Hexafluoroisopropylidene)diphthalic anhydride). Finally, stir at room temperature for 12-18 h to obtain a polymer solution. Coat the polymer solution on glass and place it in an oven at 200-240 °C for reaction for 2-4 h. After cooling, demold to obtain a polymer film. In the formula of this polymer, n is an integer greater than 1. The Tg and CTE of Polymer 1 are measured by a static mechanical analyzer (TMA), and its specification follows IPC-TM-650 2.4.24.5. Td is measured by a thermogravimetric analyzer (TGA), and the measurement results are shown in Table 1. Synthesis reaction of Polymer 2 in Example 5

[0029] First, put 0.95 moles of ODA (4,4′-Oxydianiline) and 0.05 moles of AZ into a reaction flask, then pour in the NMP (N-methylpyrrolidone) solvent to make the solid content of the solution 15 - 20%. After the above reactants are dissolved, add 1.00 moles of 6-FDA (4,4′-(Hexafluoroisopropylidene)diphthalic anhydride). Finally, stir at room temperature for 12 - 18 h to obtain a polymer solution. Coat the polymer solution on glass and place it in an oven at 200 - 240 °C for reaction for 2 - 4 h. After cooling, demold to obtain a recyclable polymer film. In the formula of this polymer, n is an integer greater than 1, x and y are real numbers greater than 0 and less than 1, and x + y = 1. The Tg and CTE of the polymer are both measured by a static mechanical analyzer (TMA), and its specification follows IPC-TM-650 2.4.24.5. Td is measured by a thermogravimetric analyzer (TGA), and the measurement results are shown in Table 1. Synthesis reaction of Polymer 3 in Example 6

[0030] First, put 0.95 moles of ODA (4,4′-Oxydianiline) and 0.05 moles of AZ into a reaction flask, then pour in the NMP (N-methylpyrrolidone) solvent to make the solid content of the solution 15 - 20%. After the above reactants are dissolved, add 0.05 moles of 6-FDA (4,4′-(Hexafluoroisopropylidene)diphthalic anhydride) and 0.95 moles of BPDA (Biphenyl-tetracarboxylic acid dianhydride). Finally, stir at room temperature for 12 - 18 h to obtain a polymer solution. Coat the polymer solution on glass and place it in an oven at 200 - 240 °C for reaction for 2 - 4 h. After cooling, demold to obtain a recyclable polymer film. In the formula of this polymer, n is an integer greater than 1, x and y are real numbers greater than 0 and less than 1, and x + y = 1. The Tg and CTE of the polymer are both measured by a static mechanical analyzer (TMA), and its specification follows IPC-TM-650 2.4.24.5. Td is measured by a thermogravimetric analyzer (TGA), and the measurement results are shown in Table 1. Synthesis reaction of Polymer 4 in Example 7

[0031] First, put 0.95 moles of ODA (4,4′-Oxydianiline) and 0.05 moles of AFZ into a reaction flask, then pour in the NMP (N-methylpyrrolidone) solvent to make the solid content of the solution 15 - 20%. After the above reactants are dissolved, add 0.05 moles of 6-FDA (4,4′-(Hexafluoroisopropylidene)diphthalic anhydride) and 0.95 moles of BPDA (Biphenyl-tetracarboxylic acid dianhydride). Finally, stir at room temperature for 12 - 18 h to obtain a polymer solution. Coat the polymer solution on glass and place it in an oven at 200 - 240 °C for reaction for 2 - 4 h. After cooling, demold to obtain a recyclable polymer film. In the formula of this polymer, n is an integer greater than 1, x and y are real numbers greater than 0 and less than 1, and x + y = 1. The Tg and CTE of Polymer 4 are both measured by a static mechanical analyzer (TMA), and its specifications follow IPC-TM-650 2.4.24.5. Td is measured by a thermogravimetric analyzer (TGA), and the measurement results are shown in Table 1. Synthesis reaction of Polymer 5 in Example 8

[0032] The reaction formula is as follows. According to the molar dosage of the drugs required in Table 1, first put 0.95 moles of ODA (4,4′-Oxydianiline) and 0.05 moles of IAF-1 into a reaction flask, then pour in the NMP (N-methylpyrrolidone) solvent to make the solid content of the solution 15 - 20%. After the above reactants are dissolved, add 0.05 moles of 6-FDA (4,4′-(Hexafluoroisopropylidene)diphthalic anhydride) and 0.95 moles of BPDA (Biphenyl-tetracarboxylic acid dianhydride). Finally, stir at room temperature for 12 - 18 h to obtain a polymer solution. Coat the polymer solution on glass and place it in an oven at 200 - 240 °C for reaction for 2 - 4 h. After cooling, demold to obtain a recyclable polymer film. In the formula of this polymer, n is an integer greater than 1, x and y are real numbers greater than 0 and less than 1, and x + y = 1. The Tg and CTE of Polymer 5 are both measured by a static mechanical analyzer (TMA), and its specifications follow IPC-TM-650 2.4.24.5. Td is measured by a thermogravimetric analyzer (TGA). Thermal property test of the prepared polymers in Table 1 Polymer 1 Polymer 2 Polymer 3 Polymer 4 Polymer 5 CTE (ppm / ℃) 49 51 48 21 18 Tg (℃) 300 291 307 301 311 Td (℃) 505 497 558 571 567 Recycling example

[0033] The films of Polymers 2, 3, and 5 of Examples 5, 6, and 8 prepared were cut into two equal halves, and then the two separated films were stacked together and recycled at a temperature ranging from room temperature to 150 °C. The recycled films were subjected to the thermal property tests of glass transition temperature and thermal decomposition temperature as described above, and the test results are shown in Table 2. Retention rate calculation: T2 / T1 * 100% (T1: thermal property temperature of the original film; T2: thermal property temperature of the recycled film). Table 2 Thermal Property Tests of the Polymers of the Present Invention Before and After Recycling

[0034] From the above recycling examples, it can be seen that for the polyimide resin of the present invention, when its glass transition temperature and thermal decomposition temperature are tested after recycling, they are nearly the same as those of the polyimide resin before recycling. It can be seen that the low thermal expansion and recyclable polyimide resin of the present invention can be recycled, and still has certain heat resistance and chemical resistance after recycling, which is beneficial to the recycling and reuse of polyimide resin, reduces the amount of waste materials, and achieves the goal of being environmentally friendly. Therefore, the present invention is indeed novel, progressive, and industrially applicable, and undoubtedly meets the requirements for patent application in the Patent Law. Hence, an invention patent application is filed according to law, praying that your bureau will grant the patent at an early date. Thank you very much.

[0035] The magnitudes of the serial numbers of the steps in the above embodiments do not mean the order of execution. The order of execution of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

[0036] The above is only the preferred embodiment of the present invention, and is not used to limit the scope of implementation of the present invention. All equivalent changes and modifications made according to the shape, structure, features, and spirit described in the scope of the claims of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A low thermal expansion and recyclable polyimide resin, characterized in that, it comprises at least one unit of the following formula: and at least one dianhydride unit; wherein, A is selected from the group consisting of the following groups: R is selected from the group consisting of the following groups: R 1 Selected from -CH 3 、-CH 2 CH 3 、 or -CF 3 ; n is an integer greater than 1; and the dianhydride unit is selected from the group consisting of the following groups: 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, pyromellitic dianhydride, 4,4′-oxydiphthalic anhydride, bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic 2,3,5,6-dianhydride, dicyclohexyl-3,4,3′,4′-tetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride.

2. The low thermal expansion and recyclable polyimide resin according to claim 1, characterized in that, wherein the low thermal expansion and recyclable polyimide resin comprises a unit of the following formula and a unit of formula 1, n is an integer greater than 1, formula 1 is in a molar ratio of about 80 - 95%, formula 2 is in a molar ratio of about 5 - 20%, and the unit of formula 1 is different from formula 2.

3. The low thermal expansion and recyclable polyimide resin according to claim 1, characterized in that, wherein the low thermal expansion and recyclable polyimide resin comprises a unit of the following formula and a unit of formula 1, n is an integer greater than 1, formula 1 is in a molar ratio of about 80 - 95%, formula 3 is in a molar ratio of about 5 - 20%, and the unit of formula 1 is different from formula 3.

4. A method for recycling a low thermal expansion and recyclable polyimide resin according to claim 1, characterized in that, it comprises: performing a dissolution step of dissolving the low thermal expansion and recyclable polyimide resin in a polar aprotic solvent to obtain a polyimide recovery solution; and performing a film-forming step of coating and baking the polyimide recovery solution to form a recovered polyimide film.

5. The method for recycling a low thermal expansion and recyclable polyimide resin according to claim 4, characterized in that, Wherein the polar aprotic solvent is dimethylacetamide, a dimethylacetamide derivative, N-methylpyrrolidone, or an N-methylpyrrolidone derivative.

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