TWI895875B - Low coefficient thermal expansion and recyclable polyimide resin and recycling method thereof - Google Patents

Abstract

This invention provides a low coefficient thermal expansion and recyclable polyimide resin. The polyimide resin with recyclable functional groups and rigid chemical structure has thermal dimensional stability and also can be easily to reuse. Based on the properties of the novel low coefficient thermal expansion and recyclable polyimide resin, it is rigid, chemical-resistant, low heat expansion and recyclable.

Description

Low thermal expansion and recyclable polyimide resin and recycling method thereof

The present invention relates to a low-thermal-expansion, recyclable polyimide resin and a method for preparing the same. The invention relates to a polyimide resin having a wide operating temperature range, chemical corrosion resistance, high strength, and recyclability. The polyimide resin can be repaired and recycled by controlling the temperature. A method for recycling the polyimide resin is also provided.

Polymers can be categorized as thermoplastics and thermosets based on their physical properties when heated. Thermoset polymers solidify upon synthesis and do not soften even after subsequent heating. In contrast, thermoplastic polymers soften upon heating after synthesis and solidify again upon cooling. Furthermore, thermoset polymers generally exhibit superior mechanical, thermal, and chemical properties, as well as improved dimensional stability, compared to thermoplastic polymers. Therefore, they are widely used in applications requiring high temperatures, high mechanical strength, or chemical corrosion resistance, such as tires and circuit boards. They are also referred to as thermosetting resins.

Thermosetting resin polymers are used in numerous fields. However, products made with these conventionally used polymers cannot be repaired upon damage or at the end of their life cycle and must be discarded, resulting in a waste of resources. Furthermore, because discarded thermosetting resin polymers are difficult to decompose naturally, they can only be disposed of by landfill or incineration, causing serious environmental pollution.

Polyimide resin is an organic polymer material containing imide groups. It is primarily synthesized by the reaction and polymerization of diamines and dianhydrides, followed by high-temperature cyclodehydration to form a polyimide polymer. Polyimide resins exhibit excellent thermal stability and good mechanical, electrical, and chemical properties, making them widely used in various fields. In recent years, the booming domestic semiconductor, electronics, and communications industries have driven economic growth, leading to a growing demand for electronic chemicals and materials. Due to its superior properties, polyimide resin plays a crucial role in electronic materials, particularly in the electronics industry, which places stringent material requirements. It is used in applications such as high-temperature tapes, flexible circuit boards, photosensitive polyimide insulation layers for IC packaging, and alignment films for LCDs.

Traditionally, polyimide resins have been difficult to recycle after being manufactured due to concerns about durability. Therefore, if a product is damaged or reaches the end of its lifecycle, it must be discarded. While previous research has demonstrated repairable or recyclable polyimide resins, their poor heat and chemical resistance limits their application.

Therefore, a polyimide resin that is recyclable and retains certain heat and chemical resistance after recycling, thereby improving product durability and being recyclable to achieve zero waste emissions, is currently being addressed.

In summary, developing a polyimide resin that is tough, chemically resistant, heat-resistant, recyclable, and retains a certain degree of heat and chemical resistance after recycling is a development goal with commercial value.

The main purpose of the present invention is to provide a low thermal expansion and recyclable polyimide resin that is tough, chemically resistant, heat resistant, recyclable, and still has a certain degree of heat resistance and chemical resistance after recycling.

Another object of the present invention is to provide a method for recycling low-thermal-expansion and recyclable polyimide resin, which can be recycled in a low-temperature environment to achieve the goal of reducing resource waste and lowering environmental pollution.

To achieve the above-mentioned main objectives, the present invention provides a low thermal expansion and recyclable polyimide polymer resin comprising at least one unit as shown in Formula I: Formula 1 and at least one dianhydride unit wherein A is selected from the group consisting of: 、 、 、 、 、 ,and ; R is selected from the group consisting of the following groups: 、 、 、 、 、 、 and 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 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.

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

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

To achieve another objective, the present invention provides a method for recovering the low thermal expansion, recyclable polyimide resin described above, comprising: a dissolution step of dissolving the low thermal expansion, recyclable polyimide resin in a polar aprotic solvent to obtain a recovered polyimide solution; and a film-forming step of coating and baking the recovered polyimide solution to form a recovered polyimide film.

The present invention provides an embodiment, wherein in the method for recovering a low thermal expansion and recyclable polyimide resin, the polar aprotic solvent is dimethylacetamide or N-methylpyrrolidone.

To help you better understand and appreciate the features and effects of this invention, we provide preferred embodiments and detailed descriptions. However, these embodiments can be applied to various inventive concepts and embodied in a variety of specific scopes. The specific embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure.

A low thermal expansion and recyclable polyimide resin of the present invention comprises at least one unit of the following formula: Formula 1 and at least one dianhydride unit; wherein A is selected from the group consisting of: 、 、 、 、 、 ,and ; R is selected from the group consisting of the following groups: 、 、 、 、 、 、 and 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 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.

In one embodiment of the present invention, the low thermal expansion and recyclable polyimide resin preferably comprises a unit of the following formula: Formula 2 and a unit of Formula 1 different from Formula 2, wherein n is an integer greater than 1. During polymerization of the polyimide resin, the coefficient of thermal expansion (CTE) and glass transition temperature (Tg) of the polyimide resin are optimal when the molar ratio of Formula 1 is approximately 80-95% and the molar ratio of Formula 2 is approximately 5-20%.

In another embodiment of the present invention, the low thermal expansion and recyclable polyimide resin preferably comprises units of the following formula. Formula 3, and a unit of Formula 1 different from Formula 3, wherein n is an integer greater than 1. During polymerization of the polyimide resin, the thermal expansion coefficient and glass transition temperature of the polyimide resin are optimal when the molar ratio of Formula 1 is approximately 80-95% and the molar ratio of Formula 3 is approximately 5-20%.

The low thermal expansion and recyclable polyimide resin of the present invention can be recycled and reused after use. Please refer to Figure 1, which is a schematic diagram of the steps of an embodiment of the recycling method of the present invention, wherein the steps of the recycling method include:

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

Step S20: coating and baking the recovered polyimide solution to form a recovered polyimide resin film.

When using this method to recover the low thermal expansion, recyclable polyimide resin, a solvent can be used for dissolution and recovery at low temperatures. The recovered polyimide solution is then coated and baked to form a film, re-forming a recycled polyimide resin film. The recovered polyimide resin has the same glass transition temperature and decomposition temperature (Td) as the polyimide resin before recycling, and the recovery rate is greater than 90%. In step S10, the solvent used to dissolve and recover the low thermal expansion, recyclable polyimide resin can be a polar aprotic solvent, preferably a solvent such as DMAc (dimethylacetamide) or NMP (N-methylpyrrolidone).

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

5.4 g 4-aminoacetophenone (0.4 mol), 2.0 g triethylamine (0.2 mol), and 4.0 g ethanol were added to a reaction flask. The mixture was then heated to 80°C. After the reactants were completely dissolved in ethanol, 2.7 g hydrazine sulfate (0.2 mol) was added and the reaction was refluxed for 5 hours. The product was precipitated in an ice bath, filtered, and washed with water and ethanol. The monomer structure is 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 an imine monomer (AFZ): Formula 1-2

To a reaction flask, add 0.5 g (4-Aminophenyl)-2,2,2-trifluoro-1-ethanone (0.5 mol), 0.8 g triethylamine (2.5 mol), and 1.4 g ethanol. The mixture is then heated to 90°C. Once the reactants are completely dissolved in ethanol, 0.17 g hydrazine sulfate (0.5 mol) is added and the reaction is refluxed for 8 hours. The product is precipitated in an ice bath, filtered, and washed with water and ethanol. The monomer structure is 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 an imine monomer (IAF-1): Formula 1-3

6.75 g 4'-Aminoacetophenone (0.05 mol), 6.5 g p -Phenylenediamine (0.06 mol), and 30 g Toluene were added to the reaction flask. The mixture was then heated to 120°C and refluxed for 48 hours. After the reaction, the mixture was filtered at room temperature, and the filtrate was concentrated to remove the Toluene. Finally, the solvent was removed under high vacuum to obtain the product. Its monomer structure is shown in Formula 1-3, and its structure was identified using NMR spectroscopy. Example 4 Synthesis of Polymer 1

First, 1.00 mol of 4,4′-Oxydianiline (ODA) was placed in a reaction flask, followed by NMP (N-methylpyrrolidone) solvent to a solids content of 15-20%. After the above reactants were dissolved, 1.00 mol of 6-FDA (4,4′-(Hexafluoroisopropylidene)diphthalic anhydride) was added. Finally, the mixture was stirred at room temperature for 12-18 hours to obtain a polymer solution. The polymer solution was then coated onto glass and placed in an oven at 200-240°C for 2-4 hours. After cooling, the film was stripped to obtain a polymer film. In the formula for this polymer, n is an integer greater than 1. The Tg and CTE of polymer 1 were measured using a static mechanical analyzer (TMA) in accordance with IPC-TM-650 2.4.24.5. Td was measured by thermogravimetric analysis (TGA), and the results are shown in Table 1. Example 5 Synthesis of Polymer 2

0.95 mol of ODA (4,4′-Oxydianiline) and 0.05 mol of AZ were placed in a reaction flask. NMP (N-methylpyrrolidone) solvent was then added to a solids content of 15-20%. After the reactants were dissolved, 1.00 mol of 6-FDA (4,4′-(Hexafluoroisopropylidene)diphthalic anhydride) was added. Finally, the mixture was stirred at room temperature for 12-18 hours to obtain a polymer solution. The polymer solution was then coated on glass and placed in an oven at 200-240°C for 2-4 hours. After cooling, the film was stripped to obtain a recyclable polymer film. The polymer formula is: 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 2 were measured by a static mechanical analyzer (TMA) in accordance with IPC-TM-650 2.4.24.5. Td was measured by a thermogravimetric analyzer (TGA), and the results are shown in Table 1. Example 6 Synthesis of polymer 3

0.95 mol of ODA (4,4′-Oxydianiline) and 0.05 mol of AZ were placed in a reaction flask. NMP (N-methylpyrrolidone) solvent was then added to a solids content of 15-20%. After the reactants were dissolved, 0.05 mol of 6-FDA (4,4′-(Hexafluoroisopropylidene)diphthalic anhydride) and 0.95 mol of BPDA (Biphenyl-tetracarboxylic acid dianhydride) were added. Finally, the mixture was stirred at room temperature for 12-18 hours to obtain a polymer solution. The polymer solution was then coated on glass and placed in an oven at 200-240°C for 2-4 hours. After cooling, the film was stripped to obtain a recyclable polymer film. The polymer formula is: 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 3 were measured by a static mechanical analyzer (TMA) in accordance with IPC-TM-650 2.4.24.5. Td was measured by a thermogravimetric analyzer (TGA), and the results are shown in Table 1. Example 7 Synthesis of polymer 4

0.95 mol of ODA (4,4′-Oxydianiline) and 0.05 mol of AFZ were placed in a reaction flask. NMP (N-methylpyrrolidone) solvent was then added to a solids content of 15-20%. After the reactants were dissolved, 0.05 mol of 6-FDA (4,4′-(Hexafluoroisopropylidene)diphthalic anhydride) and 0.95 mol of BPDA (Biphenyl-tetracarboxylic acid dianhydride) were added. Finally, the mixture was stirred at room temperature for 12-18 hours to obtain a polymer solution. The polymer solution was then coated on glass and placed in an oven at 200-240°C for 2-4 hours. After cooling, the film was stripped to obtain a recyclable polymer film. The polymer formula is: 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 were measured by a static mechanical analyzer (TMA) in accordance with IPC-TM-650 2.4.24.5. Td was measured by a thermogravimetric analyzer (TGA), and the results are shown in Table 1. Example 8 Synthesis of polymer 5

The reaction formula is as follows. Based on the required molar dosages of the drugs listed in Table 1, 0.95 mol of ODA (4,4′-Oxydianiline) and 0.05 mol of IAF-1 are placed in a reaction flask. NMP (N-methylpyrrolidone) solvent is then added to a solids content of 15-20%. After the reactants are dissolved, 0.05 mol of 6-FDA (4,4′-(Hexafluoroisopropylidene)diphthalic anhydride) and 0.95 mol of BPDA (Biphenyl-tetracarboxylic acid dianhydride) are added. Finally, the mixture is stirred at room temperature for 12-18 hours to obtain a polymer solution. The polymer solution is then coated onto glass and placed in an oven at 200-240°C for 2-4 hours. After cooling, the film is stripped to obtain a recyclable polymer film. In the polymer formula, 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 were measured using a static mechanical analyzer (TMA) in accordance with IPC-TM-650 2.4.24.5. Td was measured using a thermogravimetric analyzer (TGA). Table 1 Thermal properties of the prepared polymers Polymer 1 Polymer 2 Polymer 3 Polymer 4 Polymer 5 CTE (ppm/℃) 49 51 48 twenty one 18 Tg(℃) 300 291 307 301 311 Td(℃) 505 497 558 571 567 Recycling Example

The prepared films of polymers 2, 3, and 5 of Examples 5, 6, and 8 were cut into two equal halves, then stacked together and recovered at room temperature to 150°C. The recovered films were subjected to the aforementioned thermal property tests for glass transition temperature and thermal decomposition temperature. 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 recovered film). Table 2 Thermal property tests of the polymers of the present invention before and after recovery Recycling Example 1 Recycling Example 2 Recycling Example 3 Polymer 2 Recycled polymer 2 Polymer 3 Recycled polymer 3 Polymer 5 Recycled polymer 5 Tg(℃) 291 295 307 305 311 310 Tg maintenance rate 100% 99% 99% Td(℃) 497 504 558 549 567 564 Td maintenance rate 100% 99% 99%

As demonstrated in the above recycling examples, the glass transition temperature and thermal decomposition temperature of the polyimide resin of the present invention after recycling are nearly identical to those of the polyimide resin before recycling. This demonstrates that the low thermal expansion, recyclable polyimide resin of the present invention is recyclable and retains a certain degree of heat and chemical resistance after recycling, facilitating its recycling and reuse, reducing the amount of waste material and achieving environmentally friendly goals. Therefore, this invention is novel, advanced, and industrially applicable, undoubtedly meeting the patent application requirements under the Republic of my country's Patent Law. We have therefore filed an invention patent application in accordance with the law and sincerely pray for the expedited approval of the patent.

However, the above description is only a preferred embodiment of the present invention and is not intended to limit the scope of implementation of the present invention. All equivalent changes and modifications based on the shape, structure, characteristics and spirit described in the patent application scope of the present invention should be included in the patent application scope of the present invention.

S10 Step S20 Step

Figure 1: Flow chart of the steps of the recycling method of the low thermal expansion and recyclable polyimide resin of the present invention

S10 Step S20 Step

Claims (4)

A low thermal expansion and recyclable polyimide resin comprises units of the following formula: Formula 1 and Formula 2 and at least one dianhydride unit; wherein the unit of Formula 1 is different from that of Formula 2; and A is selected from the group consisting of: 、 、 、 、 、 , and ; R is selected from the group consisting of the following groups: 、 、 、 、 、 、 and 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, 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. A low thermal expansion and recyclable polyimide resin comprises units of the following formula: Formula 1 and Formula 3 and at least one dianhydride unit; wherein the unit of Formula 1 is different from that of Formula 3; and A is selected from the group consisting of: 、 、 、 、 、 , and ; R is selected from the group consisting of the following groups: 、 、 、 、 、 、 and 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, 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. A method for recovering a low thermal expansion and recyclable polyimide resin as described in claim 1 or 2, comprising: 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 a film-forming step of coating and baking the polyimide recovery solution to form a recycled polyimide resin film. The method for recovering a low thermal expansion and recyclable polyimide resin as described in claim 3, wherein the polar aprotic solvent is dimethylacetamide, a dimethylacetamide derivative, N-methylpyrrolidone, or an N-methylpyrrolidone derivative.