Polyimide oligomer, method for preparing the same, and cured product having low dielectric properties prepared thereby

Abstract

The present invention provides a polyimide oligomer, a method for preparing the same, and a cured product having low dielectric properties prepared thereby. The polyimide oligomer of the present invention has the structure shown in formula (I) or formula (II), where the symbols in formulas (I) and (II) are as defined in the specification. By combining a dimeric diamine with a specific monomer and adjusting the ratio, a radical-curable polyimide oligomer can be obtained, and the cured product has good thermal properties and excellent low dielectric properties, making it suitable for industrial applications in high-frequency circuit boards. [Formula 1] JPEG2026514529000021.jpg59170

Description

[Technical Field]

[0001] The present invention relates to oligomers, methods for preparing the same, and cured products thereof, and more particularly to polyimide oligomers derived from dimeric diamines, methods for preparing the same, and cured products having low dielectric properties prepared thereby. [Background technology]

[0002] Currently, with the rise of cloud technologies such as the internet and data centers, radical curing systems are attracting considerable attention in the application of printed circuit board materials. Noryl SA9000, sold by SABIC, is a polyphenylene ether oligomer with difunctional acrylic groups at its ends. Due to its low molecular weight, it has good organic solubility and excellent workability in the impregnation process. Therefore, Noryl SA9000 acquires its basic properties through radical curing of the terminal acrylic groups, and in addition to the non-polar structure of the polyphenylene ether itself, no polar basis groups are formed after radical curing, resulting in excellent electrical properties of the cured product. As a result, Noryl SA9000 is becoming one of the mainstream materials for high-grade printed circuit board materials. However, the preparation process of Noryl SA9000 is difficult to purify and generates a large amount of wastewater. From an environmental protection perspective, developing a usable material with good electrical properties and less process pollution will contribute to both the development of printed circuit board materials and environmental protection.

[0003] In recent years, with increasing awareness of environmental protection and carbon reduction, many studies have focused on applied research on special bio-based diamines. For example, dimer diamines are mixed with the aromatic diamine monomer m-tolidine and polymerized with 4,4'-bisphenol A dihydroanhydride (BPADA) to obtain high-molecular-weight polyimide (PI), or dimer diamines and dihydroanhydrides are reacted to prepare polyimide oligomers or polymers with reactive functional groups at the ends. The dimer diamine itself has a large, branched diamine structure and a large free volume, so its introduction into materials is expected to result in low dielectric properties. As a result, the measured electrical properties of the above polyimide materials are very good, but there is still considerable room for improvement in heat resistance. [Overview of the project] [Problems that the invention aims to solve]

[0004] In light of this, the goal of the relevant industry is to synthesize radical-curable polyimide oligomers derived from bio-based dimeric diamines to overcome the problem of poor thermal properties of dimeric diamine derivative products and to provide them with high-frequency, low-dielectric properties. [Means for solving the problem]

[0005] One object of the present invention is to provide a polyimide oligomer, a method for preparing the same, and a cured product having low dielectric properties prepared thereby. By combining a dimeric diamine with other monomers and adjusting the ratio, a radical-curable polyimide oligomer can be obtained, and the cured product has heat resistance and excellent electrical properties.

[0006] One embodiment of the present invention provides a polyimide oligomer having a structure represented by formula (I) or formula (II), [ka] However, X is independently either a hydrogen atom or a methyl group, and R1 is a cycloalkane having a total of 5 to 20 carbon atoms and a structure with 5 or more carbon atoms, as shown in formula (A), formula (B), or formula (C). [ka] Each R2 is independently a saturated or unsaturated hydrocarbon group having 36 carbon atoms, and each A is independently a benzene ring, biphenyl, naphthalene ring, cycloalkanes having 4 to 6 carbon atoms, or a structure represented by formula (a), formula (b), formula (c), formula (d), formula (e), formula (f), formula (g), formula (h), or formula (i). [ka] However, n is any number between 0 and 10, and m / p is any number between 0.5 and 5.

[0007] According to the polyimide oligomers described in the preamble, cycloalkanes having 5 or more carbon atoms may include the structures shown in formula (D), formula (E), or formula (F). [ka]

[0008] According to the polyimide oligomers described in the preamble, R2 may have the structure shown in formula (G), formula (H), formula (I), or formula (J). [ka]

[0009] The polyimide oligomers described in the preamble may have the structure shown in formula (I-1) or formula (II-1). [ka]

[0010] Another embodiment of the present invention provides a method for preparing the polyimide oligomer, which includes performing a first dissolution step, a second dissolution step, a mixing step, and an addition step. The first dissolution step involves dissolving a dianhydride and a single anhydride having an unsaturated double bond in a first solvent to form an anhydride solution. The second dissolution step involves mixing a dimer diamine and a bifunctional aliphatic amine having a rigid cyclic structure and dissolving them in a second solvent to form a diamine solution. The mixing step involves adding the diamine solution to the anhydride solution and reacting at a polymerization temperature to form a mixed solution. The addition step involves adding xylene to the mixed solution and performing reaction and distillation at a reactive distillation temperature to obtain a polyimide oligomer.

[0011] According to the method for preparing the polyimide oligomer described above, the first solvent and the second solvent may be selected from the group consisting of N,N-dimethylacetamide, N-methylpyrrolidone, dimethylformamide, anisole, dimethyl sulfoxide, cyclohexanone, and resorcinol.

[0012] According to the method for preparing the polyimide oligomer described above, the polymerization temperature may be 0°C to 90°C.

[0013] According to the method for preparing the polyimide oligomer described above, the reactive distillation temperature may be 130°C to 170°C.

[0014] According to the method for preparing the polyimide oligomer described above, the molar ratio of the dimer diamine to the bifunctional aliphatic amine may be 1:0.4 to 1:3.

[0015] According to the method for preparing the polyimide oligomer described above, the molar ratio of the diamine obtained by adding the bifunctional aliphatic amine to the dimer diamine to the dianhydride may be 1.2:1 to 1.8:1.

[0016] Another embodiment of the present invention provides a cured product having low dielectric properties, which is obtained by adding a radical initiator to the polyimide oligomer and firing at a curing temperature.

[0017] According to the cured product having low dielectric properties described in the preamble, the radical initiator may be a peroxide, an azo initiator, or a mixture thereof.

[0018] According to the cured product having low dielectric properties described in the preamble, the amount of radical initiator added may be 0.3 to 2 weight percent of the polyimide oligomer content.

[0019] According to the cured product having low dielectric properties as described in the preamble, the curing temperature may be 160°C to 240°C.

[0020] According to the cured product having low dielectric properties as described in the preamble, the curing temperature may be 180°C, 200°C, or 220°C.

[0021] As a result, the polyimide oligomer of the present invention can be polymerized using a dimeric diamine as a raw material in combination with a specific monomer, without requiring a purification process, and can be directly subjected to radical thermal curing by providing a reactive unsaturated double bond at the end of the molecular chain. After curing and molding, it exhibits good heat resistance and excellent electrical properties, making it a promising material for use in high-frequency circuit board applications. [Brief explanation of the drawing]

[0022] To make the above and other objectives, features, advantages, and embodiments of the present invention clearer and easier to understand, the accompanying drawings are described below. [Figure 1] This is a process flow diagram showing a method for preparing a polyimide oligomer according to one embodiment of the present invention. [Modes for carrying out the invention]

[0023] The embodiments of the present invention will be described in more detail below. However, these embodiments are applications of various inventive concepts and can be specifically implemented in various different specific scopes. Specific embodiments are for illustrative purposes only and are not limited to the scope of disclosure.

[0024] In this invention, the structure of a compound may be represented by a skeleton formula, in which carbon atoms, hydrogen atoms, and carbon-hydrogen bonds may be omitted. However, if functional groups are explicitly depicted in the structural formula, those depicted shall be used as the basis.

[0025] In the present invention, the phrase "the polyimide oligomer has the structure shown in formula (I)" may sometimes be expressed as the polyimide oligomer shown in formula (I) or polyimide oligomer (I) for brevity and fluency, and the same applies to the expression of other compounds or base groups.

[0026] In the present invention, unless otherwise specified, the grouping of a given fundamental element may or may not be substituted. For example, "alkyl group" may or may not be substituted.

[0027] <Polyimide oligomer> The present invention provides a polyimide oligomer having the structure shown in formula (I) or formula (II), [ka] However, X is independently either a hydrogen atom or a methyl group, and R1 is a cycloalkane having a total of 5 to 20 carbon atoms and a structure with 5 or more carbon atoms, as shown in formula (A), formula (B), or formula (C). [ka] Each R2 is independently a saturated or unsaturated hydrocarbon group having 36 carbon atoms. Each A is independently a benzene ring, a biphenyl ring, a naphthalene ring, a cycloalkane having 4 to 6 carbon atoms, or a structure represented by formula (a), formula (b), formula (c), formula (d), formula (e), formula (f), formula (g), formula (h), or formula (i). [ka] However, n is any number between 0 and 10, and m / p is any number between 0.5 and 5.

[0028] More specifically, cycloalkanes having five or more carbon atoms may include the structures shown in formula (D), formula (E), or formula (F). [ka] However, the present invention is not limited to these. Furthermore, R2 may have the structure shown in formula (G), formula (H), formula (I), or formula (J). [ka]

[0029] For example, in a polyimide oligomer represented by formula (I) or formula (II), if X is hydrogen, R1 is the structure shown in formula (D), R2 is the structure shown in formula (J), and A is a benzene ring, the polyimide oligomer has the structure shown in formula (I-1) or formula (II-1). [ka]

[0030] As a result, the polyimide oligomer of the present invention is derived from a dimeric diamine, has reactive unsaturated double bonds at its structural ends, and can form a cured product with good mechanical properties and heat resistance after curing by radical polymerization. Furthermore, because the main structure is composed of a large amount of aliphatic carbon chains, it can provide the material with excellent low dielectric properties and has considerable potential for application as a printed circuit board material.

[0031] <Method for preparing polyimide oligomers> Please refer to Figure 1. Figure 1 is a process flow diagram showing a method 100 for preparing a polyimide oligomer according to one embodiment of the present invention. In Figure 1, the method 100 for preparing a polyimide oligomer includes steps 110, 120, 130, and 140.

[0032] Step 110 is a first dissolution step in which a diacid anhydride and a monoacid anhydride are dissolved in a first solvent to form an acid anhydride solution. The monoacid anhydride has an unsaturated double bond and satisfies the requirements for subsequent radical curing. Specifically, the monoacid anhydride may be, but is not limited to, maleic anhydride or itaconic anhydride.

[0033] Step 120 is a second dissolution step in which the dimeric diamine and the bifunctional aliphatic amine are mixed and dissolved in the second solvent to form a diamine solution. However, the molar ratio of the dimeric diamine to the bifunctional aliphatic amine may be 1:0.4 to 1:3, preferably 1:0.5 to 1:2. Specifically, the dimeric diamine is a bio-based diamine, a diamine monomer derived from a fatty acid, and has a polycarbonate aliphatic main structure, while the bifunctional aliphatic amine has a rigid cyclic structure and provides good heat resistance to the subsequent radical-cured derivative. Specifically, the bifunctional aliphatic amine may be, but is not limited to, isophorone diamine or norbornene diamine.

[0034] The first solvent in step 110 and the second solvent in step 120 may be the same or different, and are selected from the group consisting of N,N-dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), dimethylformamide (DMF), anisole, dimethyl sulfoxide (DMSO), cyclohexanone, and resorcinol (m-cresol).

[0035] Step 130 involves a mixing step in which the diamine solution is added to the acid anhydride solution and reacted at the polymerization temperature to form a mixed solution. However, the polymerization temperature may be 0°C to 90°C, preferably 40°C to 80°C, and polymerization proceeds at the polymerization temperature after the diamine solution is added to the acid anhydride solution. The molar ratio of the diamine obtained by adding a bifunctional aliphatic amine to the dimerized diamine to the diacid anhydride may be 1.2:1 to 1.8:1, preferably 1.4:1 to 1.6:1.

[0036] Step 140 involves an addition step in which xylene is added to the mixed solution, and the reaction and distillation are carried out at the reaction distillation temperature to obtain a polyimide oligomer. However, the reaction distillation temperature may be 130°C to 170°C, preferably 140°C to 160°C. Specifically, after adding xylene to the mixed solution, a Dean-Stark apparatus is set up, the temperature is raised to the reaction distillation temperature to carry out a dead cycle reaction and distillation dehydration, and after cooling, a polyimide oligomer solution is obtained, which contains the polyimide oligomer and the solvent.

[0037] <Cured product with low dielectric properties> The present invention provides a cured product having low dielectric properties, which is obtained by adding a radical initiator to the polyimide oligomer and firing it at a curing temperature. However, the radical initiator may be a peroxide, an azo initiator, or a mixture thereof, and the amount of radical initiator added may be 0.3 to 2 weight percent of the polyimide oligomer content, preferably 0.5 to 1.5 weight percent. The radical curing reaction may be carried out by a stepwise heating method, but is not limited to this heating method. The curing temperature may be 160°C to 240°C, preferably 180°C, 200°C, or 220°C.

[0038] As a result, the method for preparing polyimide oligomers of the present invention, by selectively blending and adjusting the ratio of amines, allows the product to maintain high-frequency low dielectric properties while overcoming poor thermal properties after curing. Furthermore, by improving the selection and supply order of monomers in the process, it is possible to prepare polyimide oligomers without adding catalysts, and it can be used directly in the impregnation process of printed circuit boards, reducing wastewater generation and solvent usage, and achieving both the development of the printed circuit board industry and the trend toward carbon neutrality.

[0039] The present invention will be further illustrated by the following specific embodiments, so that those skilled in the art can fully utilize and practice the invention without overinterpretation. These embodiments should not be considered to limit the scope of the invention, but are used to illustrate how the materials and methods of the present invention are implemented.

[0040] <Examples / Comparative Examples> Example 1: Acid anhydride solutions were prepared by dissolving 20 g (0.0917 mol) of pyromellitic dianhydride (PMDA) and 8.99 g (0.0917 mol) of maleic anhydride in 90 g of N,N-dimethylacetamide (DMAc). Subsequently, diamine solutions were prepared by dissolving 36.79 g (0.0688 mol) of dimeric diamine (Priamine 1075, purchased from Croda) and 11.71 g (0.0688 mol) of isophoronediamine (IPDA) in 73 g of N,N-dimethylacetamide. Subsequently, the diamine solution was slowly added dropwise to the acid anhydride solution, and the temperature was controlled to below 60°C using a water bath. After the addition was complete, the temperature was raised to 80°C and the reaction was allowed to proceed for 3 hours. After completion, 54 g of xylene was added to form the target mixture, and the polyimide oligomer solution was separated from the target mixture by distillation. Using a Dean-Stark apparatus, for example, the target mixture was heated to 150°C and dehydrated for 4 hours, then heated to 160°C and dehydrated further. After the amount of distillate reached the predetermined amount of dehydrated water, the temperature was lowered to obtain the polyimide oligomer solution of Example 1. Specifically, the polyimide oligomer of Example 1 had the structure shown in formula (I-1), with an m / p ratio of 1, and its number-average molecular weight (Mn) was 2095 and its weight-average molecular weight (Mw) was 4841, as measured by gel permeation chromatography (GPC).

[0041] Example 2: An acid anhydride solution was prepared by dissolving 20 g (0.0917 mol) of pyromellitic dianhydride and 8.99 g (0.0917 mol) of maleic anhydride in 90 g of N,N-dimethylacetamide. Subsequently, a diamine solution was prepared by dissolving 24.53 g (0.0459 mol) of dimeric diamine (Priamine 1075, purchased from Croda) and 15.62 g (0.0917 mol) of isophorone diamine in 56.54 g of N,N-dimethylacetamide. Then, the diamine solution was slowly added dropwise to the acid anhydride solution, and the temperature was controlled to below 60°C in a water bath. After the addition was complete, the temperature was raised to 80°C and the reaction was allowed to proceed for 3 hours. After completion, 48.85 g of xylene was added, and the remaining steps were carried out in the same manner as in Example 1 to obtain the polyimide oligomer solution of Example 2. Specifically, the polyimide oligomer of Example 2 had the structure shown in formula (I-1), an m / p ratio of 2, and its number-average molecular weight (Mn) was 1448 and its weight-average molecular weight (Mw) was 3049, as determined by gel permeation chromatography (GPC).

[0042] Example 3: An acid anhydride solution was prepared by dissolving 20 g (0.0917 mol) of pyromellitic dianhydride and 8.99 g (0.0917 mol) of maleic anhydride in 90 g of N,N-dimethylacetamide (DMAc). Subsequently, a diamine solution was prepared by dissolving 49.05 g (0.0917 mol) of dimeric diamine (Priamine 1075, purchased from Croda) and 7.81 g (0.0458 mol) of isophorone diamine in 90.07 g of N,N-dimethylacetamide. Then, the diamine solution was slowly added dropwise to the acid anhydride solution, and the temperature was controlled to below 60°C in a water bath. After the addition was complete, the temperature was raised to 80°C and the reaction was allowed to proceed for 3 hours. After completion, 60.02 g of xylene was added, and the remaining steps were carried out in the same manner as in Example 1 to obtain the polyimide oligomer solution of Example 3. Specifically, the polyimide oligomer of Example 3 had the structure shown in formula (I-1), an m / p ratio of 0.5, and its number-average molecular weight (Mn) was 1050 and its weight-average molecular weight (Mw) was 2373, as determined by gel permeation chromatography (GPC).

[0043] Example 4: An acid anhydride solution was prepared by dissolving 20 g (0.0917 mol) of pyromellitic dianhydride and 10.28 g (0.0917 mol) of itaconic anhydride in 90 g of N,N-dimethylacetamide. Subsequently, a diamine solution was prepared by dissolving 24.53 g (0.0459 mol) of dimeric diamine (Priamine 1075, purchased from Croda) and 15.62 g (0.0917 mol) of isophorone diamine in 56.54 g of N,N-dimethylacetamide. Then, the diamine solution was slowly added dropwise to the acid anhydride solution, and the temperature was controlled to below 60°C in a water bath. After the addition was complete, the temperature was raised to 80°C and the reaction was allowed to proceed for 3 hours. After completion, 48.85 g of xylene was added, and the remaining steps were carried out in the same manner as in Example 1 to obtain the polyimide oligomer solution of Example 4. Specifically, the polyimide oligomer of Example 4 had the structure shown in formula (II-1), an m / p ratio of 2, and its number-average molecular weight (Mn) was 2235 and its weight-average molecular weight (Mw) was 5669, as determined by gel permeation chromatography (GPC).

[0044] Comparative Example 1: An acid anhydride solution was prepared by dissolving 20 g (0.0917 mol) of pyromellitic dianhydride and 8.99 g (0.0917 mol) of maleic anhydride in 90 g of N,N-dimethylacetamide. Subsequently, a diamine solution was prepared by dissolving 23.42 g (0.1375 mol) of isophoronediamine in 24.14 g of N,N-dimethylacetamide. Then, the diamine solution was slowly added dropwise to the acid anhydride solution, and the temperature was controlled to below 60°C using a water bath. After the addition was complete, the temperature was raised to 80°C and the reaction was allowed to proceed for 3 hours. After completion, 38.14 g of xylene was added, and the remaining steps were carried out in the same manner as in Example 1 to obtain the polyimide oligomer solution of Comparative Example 1. Specifically, Comparative Example 1 was measured by gel permeation chromatography (GPC), and the number-average molecular weight (Mn) was 2117 and the weight-average molecular weight (Mw) was 2950.

[0045] Comparative Example 2: An acid anhydride solution was prepared by dissolving 20 g (0.0917 mol) of pyromellitic dianhydride and 1.798 g (0.0813 mol) of maleic anhydride in 80 g of N,N-dimethylacetamide. Subsequently, a diamine solution was prepared by dissolving 26.98 g (0.0504 mol) of dimeric diamine (Priamine 1075, purchased from Croda) and 8.59 g (0.0504 mol) of isophorone diamine in 39.6 g of N,N-dimethylacetamide. Then, the diamine solution was slowly added dropwise to the acid anhydride solution, and the temperature was controlled to below 60°C using a water bath. After the addition was complete, the temperature was raised to 80°C and the reaction was allowed to proceed for 3 hours. After completion, 39.87 g of xylene was added, and the other steps were carried out in the same manner as in Example 1. However, a large amount of salts were generated during the preparation process and were difficult to remove, so the product could not be obtained successfully. This is due to changing the molar ratio of diamine to dihydroanhydride to 1.1:1.

[0046] Comparative Example 3: An acid anhydride solution was prepared by dissolving 20 g (0.0917 mol) of pyromellitic dianhydride and 8.99 g (0.0917 mol) of maleic anhydride in 90 g of N,N-dimethylacetamide. Subsequently, a diamine solution was prepared by dissolving 36.79 g (0.0688 mol) of dimeric diamine (Priamine 1075, purchased from Croda) and 11.71 g (0.0688 mol) of isophorone diamine in 73 g of N,N-dimethylacetamide. After that, the acid anhydride solution was slowly added dropwise to the diamine solution, but the reaction proceeded vigorously during the dropwise addition process, and the reaction rapidly gelled, making it impossible to obtain the product successfully. This was due to the incorrect dropwise addition order of the diamine solution and the acid anhydride solution.

[0047] Comparative Example 4: An acid anhydride solution was prepared by dissolving 20 g (0.0917 mol) of pyromellitic dianhydride and 8.99 g (0.0917 mol) of maleic anhydride in 90 g of N,N-dimethylacetamide. Subsequently, a diamine solution was prepared by dissolving 73.58 g (0.1375 mol) of dimeric diamine (Priamine 1075, purchased from Croda) in 127.28 g of N,N-dimethylacetamide. Then, the diamine solution was slowly added dropwise to the acid anhydride solution, and the temperature was controlled to below 60°C using a water bath. After the addition was complete, the temperature was raised to 80°C and the reaction was allowed to proceed for 3 hours. After completion, 72.43 g of xylene was added, and the remaining steps were carried out in the same manner as in Example 1 to obtain the polyimide oligomer solution of Comparative Example 4. Specifically, comparative example 4 was measured by gel permeation chromatography (GPC), and the number-average molecular weight (Mn) was 1937 and the weight-average molecular weight (Mw) was 2480.

[0048] <Preparation of hardened material> Example 5: A prepolymer solution was prepared by adding 0.015 g (1 wt%) of dicumyl peroxide (DCP) to 5 g of the polyimide oligomer solution from Example 1 (30% solids content, DMAc solvent). After pouring the solution into a mold, the temperature was gradually increased from 80°C to 140°C to remove the solvent, and then the temperature was further increased to cure. A stepwise heating method was used for the curing process. In this example, curing was performed in three stages, curing at 180°C, 200°C, and 220°C for 2 hours each to obtain the cured product of Example 5.

[0049] Example 6: A prepolymer solution was prepared by adding 0.015 g (1 wt%) of dicumyl peroxide to 0.015 g of the polyimide oligomer solution from Example 2 (30% solids, DMAc solvent). After pouring the solution into a mold, all other steps were carried out in the same manner as in Example 5 to obtain the cured product of Example 6.

[0050] Example 7: A prepolymer solution was prepared by adding 0.015 g (1 wt%) of dicumyl peroxide to 0.015 g of the polyimide oligomer solution from Example 3 (30% solids, DMAc solvent). After pouring the solution into a mold, all other steps were carried out in the same manner as in Example 5 to obtain the cured product of Example 7.

[0051] Example 8: A prepolymer solution was prepared by adding 0.015 g (1 wt%) of dicumyl peroxide to 0.015 g of the polyimide oligomer solution from Example 4 (30% solids, DMAc solvent). After pouring the solution into a mold, all other steps were carried out in the same manner as in Example 5 to obtain the cured product of Example 8.

[0052] Comparative Example 5: A prepolymer solution was prepared by adding 0.015 g (1 wt%) of dicumyl peroxide to 0.015 g of the polyimide oligomer solution of Comparative Example 1 (30% solids, DMAc solvent) and pouring it into a mold. All other steps were carried out in the same manner as in Example 5 to obtain the cured product of Comparative Example 5. However, due to its significant foaming and high brittleness, it was not possible to successfully produce a complete film material.

[0053] Comparative Example 6: A prepolymer solution was prepared by adding 0.015 g (1 wt%) of dicumyl peroxide to 0.015 g of the polyimide oligomer solution of Comparative Example 4 (30% solids content, DMAc solvent) and pouring it into a mold. All other steps were carried out in the same manner as in Example 5 to obtain the cured product of Comparative Example 6.

[0054] Comparative Example 7: A prepolymer solution was prepared by adding 5 g of polyphenylene ether resin (Noryl SA9000, purchased from SABIC) to 0.015 g of dicumyl peroxide. After pouring the solution into a mold, all other steps were carried out in the same manner as in Example 5 to obtain the cured product of Comparative Example 7.

[0055] <Evaluation Test Method> Glass transition temperature (T gThe glass transition temperature of the cured material was measured using a Dynamic Mechanical Analyzer (DMA), and the detection was performed under conditions of a heating rate of 5°C / min.

[0056] Dielectric analysis method: In order to evaluate the dielectric properties of the cured product obtained by curing the polyimide oligomer of the present invention, the present invention uses the dielectric constant (D) of the cured product at 10 GHz. k ) and dielectric loss (D f ) was measured.

[0057] The above evaluation test method was performed for Examples 5 to 8 and Comparative Examples 6 to 7, and the results are recorded in Table 1. [Table 1]

[0058] As can be seen from the results in Table 1 above, after radical curing, the polyimide oligomers of Examples 1 to 4 yielded glass transition temperatures of the cured products of Examples 5 to 8, all exceeding 100°C. Furthermore, as the amount of rigid isophorone diamine used increased, the glass transition temperatures of Examples 6 and 8 could reach 180°C or higher. Although their heat resistance is inferior to that of Comparative Example 7, which was obtained from the currently widely used polyphenylene ether resin SA9000, the heat resistance of the cured products of Examples 5 to 8 is indeed significantly improved compared to the cured product of Comparative Example 6, which did not contain rigid isophorone diamine.

[0059] Furthermore, in high-frequency measurements, the cured products of Examples 5 to 8 showed superior insulation properties compared to Comparative Example 7, which was obtained from the currently widely used polyphenylene ether resin SA9000. Example 6, which had the best heat resistance, was used as an example to determine its dielectric constant (D k ) shows a level almost equivalent to that of Comparative Example 7, but dielectric loss (D f ) has been greatly improved. However, as the amount of dimerized diamine used increases, the resulting cured product exhibits better insulating properties, and as an example, Example 7, which uses the largest amount of dimerized diamine, shows its dielectric constant (Dk ) reached 2.21, and the dielectric loss (D f ) reached 0.0027, showing extremely excellent electrical properties and being applicable to the manufacture of high-frequency printed wiring boards.

[0060] In addition, the cured product of Comparative Example 6 without adding rigid diamine has a dielectric constant (D k ) whose performance is not better than that of Example 7, but the performance of the dielectric loss (D f ) can be further optimized to 0.0018. This indicates that after the dimer diamine structure reaches a certain usage amount, its contribution to the dielectric constant (D k ) gradually becomes smaller, but the dielectric loss (D f ) can be further improved. However, from the perspective of heat resistance, the heat resistance of Comparative Example 6 also significantly decreases, so there are limitations in the application of circuit board materials that require heat resistance.

[0061] In short, the polyimide oligomer of the present invention uses a dimer diamine as a raw material and combines a rigid bifunctional diamine monomer, which indeed improves the heat resistance problem, retains the excellent electrical properties of the material, and shows better electrical properties than the polyphenylene ether resin currently widely used in the industry. This indicates that the polyimide oligomer proposed by the present invention has application potential in the circuit board industry and can also improve the environmental problems associated with material development.

[0062] [[ID=2​​​​​​​​​​

Claims

1. A polyimide oligomer having the structure shown in formula (I) or formula (II), 【Chemistry 1】 However, X is independently either a hydrogen atom or a methyl group, and R １ This is a cycloalkane having a total of 5 to 20 carbon atoms and a structure with 5 or more carbon atoms, represented by formula (A), formula (B), or formula (C). 【Chemistry 2】 R ２ Each of these is independently a saturated or unsaturated hydrocarbon group having 36 carbon atoms, and A is independently a benzene ring, biphenyl, naphthalene ring, cycloalkanes having 4 to 6 carbon atoms, or a structure represented by formula (a), formula (b), formula (c), formula (d), formula (e), formula (f), formula (g), formula (h), or formula (i). 【Transformation 3】 A polyimide oligomer characterized in that n is any number between 0 and 10, and m / p is any number between 0.5 and 5.

2. The cycloalkanes having five or more carbon atoms are defined by formula (D), formula (E), or formula (F). 【Chemistry 4】 The polyimide oligomer according to claim 1, characterized by comprising the structure shown in (1).

3. R ２ is formula (G), formula (H), formula (I), or formula (J) 【Transformation 5】 The polyimide oligomer according to claim 1, characterized by having the structure shown in (1).

4. Equation (I-1) or Equation (II-1) 【Transformation 6】 The polyimide oligomer according to claim 1, characterized by having the structure shown in (1).

5. A method for preparing a polyimide oligomer according to claim 1, The first dissolution step involves dissolving a diacid anhydride and a monoacid anhydride having an unsaturated double bond in a first solvent to form an acid anhydride solution. The second dissolution step involves mixing a dimeric diamine with a bifunctional aliphatic amine having a rigid cyclic structure and dissolving it in a second solvent to form a diamine solution. The mixing step involves adding the diamine solution to the acid anhydride solution and reacting it at the polymerization temperature to form a mixed solution. The addition step involves adding xylene to the mixed solution and carrying out the reaction and distillation at the reaction distillation temperature to obtain the polyimide oligomer. A method for preparing a polyimide oligomer, characterized by containing [a specific substance].

6. The method for preparing a polyimide oligomer according to claim 5, characterized in that the first solvent and the second solvent are selected from the group consisting of N,N-dimethylacetamide, N-methylpyrrolidone, dimethylformamide, anisole, dimethyl sulfoxide, cyclohexanone, and resorcinol.

7. The method for preparing a polyimide oligomer according to claim 5, characterized in that the polymerization temperature is 0°C to 90°C.

8. The method for preparing a polyimide oligomer according to claim 5, characterized in that the reaction distillation temperature is 130°C to 170°C.

9. The method for preparing a polyimide oligomer according to claim 5, characterized in that the molar ratio of the dimerized diamine to the bifunctional aliphatic amine is 1:0.4 to 1:

3.

10. The method for preparing a polyimide oligomer according to claim 5, characterized in that the molar ratio of the diamine obtained by adding the bifunctional aliphatic amine to the dimerized diamine to the diacid anhydride is 1.2:1 to 1.8:

1.

11. A cured product having low dielectric properties, characterized by being obtained by adding a radical initiator to a polyimide oligomer according to any one of claims 1 to 4 and firing it at a curing temperature.

12. The cured product having low dielectric properties according to claim 11, characterized in that the radical initiator is a peroxide, an azo initiator, or a mixture thereof.

13. The cured product having low dielectric properties according to claim 11, characterized in that the amount of radical initiator added is 0.3 to 2 weight percent of the polyimide oligomer content.

14. The cured product having low dielectric properties according to claim 11, characterized in that the curing temperature is 160°C to 240°C.

15. The cured product having low dielectric properties according to claim 14, characterized in that the curing temperature is 180°C, 200°C, or 220°C.

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