JP-2026076008-A - Polyimide resins, compositions, polyimide films, optical materials, cladding materials, and optical waveguides for low refractive index materials, as well as polyamic acids and compositions for low refractive index materials.

Abstract

[Problem] To provide a polyimide resin for low refractive index materials that achieves both a low refractive index and a low coefficient of thermal expansion. [Solution] A polyimide resin comprising an acid anhydride and a diamine, wherein (1) the acid anhydride is a tetracarboxylic dianhydride having a substituent with a fluorine atom and an aromatic ring structure which may also be a condensed structure, and the diamine is a diamine with an aromatic ring or biphenyl skeleton which may also be a condensed structure, or (2) the acid anhydride is an alicyclic tetracarboxylic dianhydride and the diamine is a diamine with an aromatic ring or biphenyl skeleton which may also be a condensed structure. [Selection Diagram] None

Inventors

• 吉崎 達
• 大西 正人
• 水谷 晟吾
• 米田 聡
• 関 豊光
• 東 昌弘
• 岸川 洋介
• 茂本 勇
• 匂坂 重仁
• 塩見 淳一郎

Assignees

• ダイキン工業株式会社
• 国立大学法人 東京大学

Dates

Publication Date

20260511

Application Date

20241023

Claims (15)

1. It consists of an acid anhydride and a diamine, The acid anhydride is one or more compounds selected from the group consisting of compounds represented by the following general formula (A-1a) and compounds represented by the following general formula (A-1b). A polyimide resin for low refractive index materials, wherein the diamine is one or more selected from the group consisting of compounds represented by the following general formula (B-1) and compounds represented by the following general formula (B-2). In the general formula (A-1a) above, R1 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted aromatic ring, and optionally substituted heterocycle. At least one R1 has a fluorine atom, m represents an integer between 0 and 3. In the general formula (A-1b) above, R1 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted aromatic ring, and optionally substituted heterocycle. n represents an integer from 1 to 5. Each R2 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted aromatic ring, or optionally substituted heterocycle, and two adjacent R2s may bond to each other to form a cycloalkyl group. At least one R2 is a fluoroalkyl group which may have substituents. X is independently selected from the group consisting of -O-, -C( R3 ) 2- , and -SO2- . Each R3 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted aromatic ring, or optionally substituted heterocycle, and two adjacent R3s may bond to each other to form a cycloalkyl group. In the general formula (B-1) above, R1 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted alkoxy group, optionally substituted aromatic ring, and optionally substituted heterocycle. l represents an integer between 1 and 3. m represents an integer between 0 and 3. n represents an integer from 0 to 5. o represents an integer from 0 to the maximum number of substituents. Each R2 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted aromatic ring, or optionally substituted heterocycle, and two adjacent R2s may bond to each other to form a cycloalkyl group. At least one R2 is a fluoroalkyl group which may have substituents. X is independently selected from the group consisting of -O-, -C( R3 ) 2- , and -SO2- . Each R3 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted aromatic ring, or optionally substituted heterocycle, and two adjacent R3s may bond to each other to form a cycloalkyl group. In the general formula (B-2) above, R1 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted alkoxy group, optionally substituted aromatic ring, and optionally substituted heterocycle. At least one R1 has a fluorine atom, Each m represents an integer between 0 and 2, independently. 'o' represents an integer between 0 and the maximum number of substituents.
2. The above general formula (B-1) is either the following general formula (B-1a) or the following general formula (B-1b), The polyimide resin according to claim 1, wherein the general formula (B-2) is the following general formula (B-2a). In the general formula (B-1a) above, R1 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted alkoxy group, optionally substituted aromatic ring, and optionally substituted heterocycle. 'o' represents an integer between 0 and 4. In the general formula (B-1b) above, R1 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted alkoxy group, optionally substituted aromatic ring, and optionally substituted heterocycle. m represents an integer between 1 and 3. 'o' represents an integer between 0 and the maximum number of substituents. In the general formula (B-2a) above, R1 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted alkoxy group, optionally substituted aromatic ring, and optionally substituted heterocycle. At least one R1 has a fluorine atom, 'o' represents an integer from 0 to 8.
3. It consists of an acid anhydride and a diamine, The acid anhydride is one or more compounds selected from the group consisting of compounds represented by the following general formulas (A-2a) to (A-2g). A polyimide resin for low refractive index materials, wherein the diamine is one or more selected from the group consisting of compounds represented by the following general formula (B-3) and compounds represented by the following general formula (B-4). In the general formulas (A-2a) to (A-2g) above, R1 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted alkoxy group, optionally substituted aromatic ring, and optionally substituted heterocycle. l represents an integer between 1 and 3. Each R2 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted alkoxy group, optionally substituted aromatic ring, and optionally substituted heterocycle. In the general formula (B-3) above, R1 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted alkoxy group, optionally substituted aromatic ring, and optionally substituted heterocycle. l represents an integer between 1 and 3. m represents an integer between 0 and 3. n represents an integer from 0 to 5. o represents an integer from 0 to the maximum number of substituents. R2 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted aromatic ring, and optionally substituted heterocycle. At least one R2 is a fluoroalkyl group which may have substituents. X is independently selected from the group consisting of -O-, -C( R3 ) 2- , and -SO2- . Each R3 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted aromatic ring, or optionally substituted heterocycle, and two adjacent R3s may bond to each other to form a cycloalkyl group. In the general formula (B-4) above, R1 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted alkoxy group, optionally substituted aromatic ring, and optionally substituted heterocycle. Each m represents an integer between 0 and 2, independently. 'o' represents an integer between 0 and the maximum number of substituents.
4. The above general formula (B-3) is either the following general formula (B-3a) or the following general formula (B-3b), The polyimide resin according to claim 3, wherein the general formula (B-4) is the following general formula (B-4a). In the general formula (B-3a) above, R1 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted alkoxy group, optionally substituted aromatic ring, and optionally substituted heterocycle. 'o' represents an integer between 0 and 4. In the general formula (B-3b) above, R1 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted alkoxy group, optionally substituted aromatic ring, and optionally substituted heterocycle. m represents an integer between 1 and 3. 'o' represents an integer between 0 and the maximum number of substituents. In the general formula (B-4a) above, R1 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted alkoxy group, optionally substituted aromatic ring, and optionally substituted heterocycle. At least one R1 has a fluorine atom, 'o' represents an integer from 0 to 8.
5. The refractive index is 1.57 or less. The polyimide resin according to claim 1 or 3, wherein the coefficient of linear thermal expansion is 50 ppm/K or less.
6. A polyimide resin having the structural unit of the following general formula (1), In the general formula (1) above, R1 represents a tetravalent group derived from a tetravalent tetracarboxylic acid having 2 or more carbon atoms in the R a (CO) 4 portion, and Rb (N) 2 portion represents a tetravalent group derived from a divalent diamine having 2 or more carbon atoms. The free volume fraction and average number of neighboring atoms of the amorphous polyimide resin in equilibrium at a temperature of 300 K and a pressure of 1 atm, as calculated by molecular dynamics calculations, satisfy any of the following conditions (1) to (4): (1) The free volume fraction is 0.23 to 0.32 and the average number of neighboring atoms is 3.90 to 4.60. (2) The free volume fraction is 0.23 to 0.32 and the average number of neighboring atoms is 3.90 to 4.60, and there are no trifluoromethyl groups. (3) The free volume fraction is 0.24 to 0.32 and the average number of neighboring atoms is 3.90 to 4.50, and there are no trifluoromethyl groups. (4) The free volume fraction is 0.28 to 0.32 and the average number of neighboring atoms is 3.90 to 4.50, and there are no trifluoromethyl groups. The average number of neighboring atoms is the average number of neighboring atoms per number of atoms constituting the system of the molecular dynamics calculation. A polyimide resin for low refractive index materials, wherein the number of adjacent atoms is the total number of atom pairs satisfying (a) and (b) below. (a) Atomic pairs that share one side of a Voronoi cell with each atom as the parent point; (b) Atomic pairs separated by four or more bonds, or atomic pairs between different molecules.
7. The free volume fraction and average number of neighboring atoms of the amorphous polyimide resin in equilibrium at a temperature of 300 K and a pressure of 1 atm, as calculated by molecular dynamics calculations, satisfy any of the following conditions (1) to (4): (1) The free volume fraction is 0.23 to 0.32 and the average number of neighboring atoms is 3.90 to 4.60. (2) The free volume fraction is 0.23 to 0.32 and the average number of neighboring atoms is 3.90 to 4.60, and there are no trifluoromethyl groups. (3) The free volume fraction is 0.24 to 0.32 and the average number of neighboring atoms is 3.90 to 4.50, and there are no trifluoromethyl groups. (4) The free volume fraction is 0.28 to 0.32 and the average number of neighboring atoms is 3.90 to 4.50, and there are no trifluoromethyl groups. The average number of neighboring atoms is the average number of neighboring atoms per molecule of the polyimide resin. The average number of neighboring atoms is the average number of neighboring atoms per number of atoms constituting the molecular dynamics calculation system, The polyimide resin according to claim 1 or 3, wherein the number of adjacent atoms is the total number of atom pairs satisfying (a) and (b) below. (a) Atomic pairs that share one side of a Voronoi cell with each atom as the parent point; (b) Atomic pairs separated by four or more bonds, or atomic pairs between different molecules.
8. A composition for low refractive index materials containing the polyimide resin according to any one of claims 1, 3, and 6.
9. A polyimide film for low refractive index materials containing the polyimide resin described in any one of claims 1, 3, and 6.
10. An optical material containing the polyimide resin described in any one of claims 1, 3, and 6.
11. A clad material containing the polyimide resin described in any one of claims 1, 3, and 6.
12. An optical waveguide having a cladding material as described in claim 11.
13. It consists of an acid anhydride and a diamine, The acid anhydride is one or more compounds selected from the group consisting of compounds represented by the following general formula (A-1a) and compounds represented by the following general formula (A-1b). A polyamic acid for low refractive index materials, wherein the diamine is one or more selected from the group consisting of compounds represented by the following general formula (B-1) and compounds represented by the following general formula (B-2). In the general formula (A-1a) above, R1 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted aromatic ring, and optionally substituted heterocycle. At least one R1 has a fluorine atom, m represents an integer between 0 and 3. In the general formula (A-1b) above, R1 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted aromatic ring, and optionally substituted heterocycle. n represents an integer from 1 to 5. Each R2 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted aromatic ring, or optionally substituted heterocycle, and two adjacent R2s may bond to each other to form a cycloalkyl group. At least one R2 is a fluoroalkyl group which may have substituents. X is independently selected from the group consisting of -O-, -C( R3 ) 2- , and -SO2- . Each R3 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted aromatic ring, or optionally substituted heterocycle, and two adjacent R3s may bond to each other to form a cycloalkyl group. In the general formula (B-1) above, R1 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted aromatic ring, and optionally substituted heterocycle. l represents an integer between 1 and 3. m represents an integer between 0 and 3. n represents an integer from 0 to 5. o represents an integer from 0 to the maximum number of substituents. Each R2 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted aromatic ring, or optionally substituted heterocycle, and two adjacent R2s may bond to each other to form a cycloalkyl group. At least one R2 is a fluoroalkyl group which may have substituents. X is independently selected from the group consisting of -O-, -C( R3 ) 2- , and -SO2- . Each R3 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted aromatic ring, or optionally substituted heterocycle, and two adjacent R3s may bond to each other to form a cycloalkyl group. In the general formula (B-2) above, R1 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted aromatic ring, and optionally substituted heterocycle. At least one R1 has a fluorine atom, Each m represents an integer between 0 and 2, independently. 'o' represents an integer between 0 and the maximum number of substituents.
14. It consists of an acid anhydride and a diamine, The acid anhydride is one or more compounds selected from the group consisting of compounds represented by the following general formulas (A-2a) to (A-2g). A polyamic acid for low refractive index materials, wherein the diamine is one or more compounds selected from the group consisting of compounds represented by the following general formula (B-3) and compounds represented by the following general formula (B-4). In the general formulas (A-2a) to (A-2g) above, R1 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted alkoxy group, optionally substituted aromatic ring, and optionally substituted heterocycle. l represents an integer between 1 and 3. Each R2 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted alkoxy group, optionally substituted aromatic ring, and optionally substituted heterocycle. In the general formula (B-3) above, R1 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted alkoxy group, optionally substituted aromatic ring, and optionally substituted heterocycle. l represents an integer between 1 and 3. m represents an integer between 0 and 3. n represents an integer from 0 to 5. o represents an integer from 0 to the maximum number of substituents. R2 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted aromatic ring, and optionally substituted heterocycle. At least one R2 is a fluoroalkyl group which may have substituents. X is independently selected from the group consisting of -O-, -C( R3 ) 2- , and -SO2- . Each R3 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted aromatic ring, or optionally substituted heterocycle, and two adjacent R3s may bond to each other to form a cycloalkyl group. In the general formula (B-4) above, R1 is independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl group, optionally substituted alkoxy group, optionally substituted aromatic ring, and optionally substituted heterocycle. Each m represents an integer between 0 and 2, independently. 'o' represents an integer between 0 and the maximum number of substituents.
15. A composition for low refractive index materials containing the polyamic acid and solvent described in claim 13 or 14.

Description

This disclosure relates to polyimide resins, compositions, polyimide films, optical materials, cladding materials, and optical waveguides for low refractive index materials, as well as polyamic acids and compositions for low refractive index materials. In the field of optics, plastic materials such as polyimide resins, epoxy resins, and acrylate resins are widely used. However, compared to metal materials, resins generally have a larger coefficient of linear thermal expansion, leading to the problem of substrate warping due to heating after lamination. Furthermore, a low refractive index and a low coefficient of linear thermal expansion are generally in a trade-off relationship, making it difficult to achieve both simultaneously. To date, resin compositions have been reported that are excellent in transparency and low refractive index, and have low thermal expansion, and that contain (A) an epoxy compound having two or more epoxy groups, (B) a compound having a phenolic hydroxyl group, (C) silica particles with an average particle size of 1 nm or more and 70 nm or less, and (D) silicone oil (see, for example, Patent Document 1). Japanese Patent Publication No. 2016-180014 Figure 1 is a cross-sectional view showing an example of an optical waveguide according to this embodiment.Figure 2 is a cross-sectional view showing another example of the optical waveguide in this embodiment.Figure 3 is a graph showing the relationship between refractive index, free volume fraction, and average number of neighboring atoms in the molecular dynamics simulation of the example.Figure 4 is a graph showing the relationship between the coefficient of linear expansion, the free volume fraction, and the average number of neighboring atoms in the molecular dynamics simulation of the example.Figure 5 is a graph showing the relationship between experimental values and calculated values from molecular dynamics simulations for refractive index.Figure 6 is a graph showing the relationship between experimental values and calculated values from molecular dynamics simulations for the coefficient of thermal expansion. (Polyimide resin for low refractive index materials) The polyimide resin for low refractive index materials of this disclosure is a polyimide resin used in applications of low refractive index materials that achieves both a low refractive index and a low coefficient of thermal expansion, and is a polyimide resin that (1) has a specific chemical structure in the first embodiment, (2) has a specific chemical structure in the second embodiment, (3) satisfies the requirements for free volume fraction and average number of neighboring atoms in the third embodiment, or (4) satisfies (1) or (2) and (3) above. The polyimide resin preferably has a refractive index of 1.57 or less and a coefficient of linear expansion of 50 ppm/K or less. The polyimide resin for low refractive index materials described herein is based on the following findings made by the inventors. In other words, conventionally, a low refractive index and a low coefficient of thermal expansion are generally in a trade-off relationship, making it difficult to achieve both. However, as shown in the examples described later, the inventors identified two parameters, "free volume fraction" and the newly defined "average number of neighboring atoms," through molecular dynamics simulations using amorphous polyimide resin, and found that these two parameters correlate with the calculated values of refractive index and coefficient of thermal expansion. In addition, as a result of evaluating the relationship between the refractive index and the experimental values of the coefficient of thermal expansion for numerous known polyimide resins, they found that a high "free volume fraction" contributes to a low refractive index and a low coefficient of thermal expansion, and that a low "average number of neighboring atoms" contributes to a low refractive index. From this, we found that a polyimide resin that achieves both a low refractive index and a low coefficient of thermal expansion can be identified using the free volume fraction and the average number of neighboring atoms as indicators. Furthermore, we identified the chemical structure of a polyimide resin that achieves both a low refractive index and a low coefficient of thermal expansion through molecular dynamics simulations. [First Embodiment] The polyimide resin for low refractive index materials in the first embodiment of this disclosure is a polyimide resin comprising an acid anhydride and a diamine, wherein the acid anhydride is one or more selected from the group consisting of compounds represented by the following general formula (A-1a) and compounds represented by the following general formula (A-1b), and the diamine is one or more selected from the group consisting of compounds represented by the following general formula (B-1) and compounds represented by the following general formula (B-2). <Acid anhydride> The a