Polyimide resins and varnishes

Abstract

This invention provides a polyimide resin with an improved balance between solvent solubility and elastic modulus. [Solution] A polyimide resin containing a diamine residue represented by the general formula (x1). TIFF2026068834000037.tif44153 (In general formula (x1), R 1 Each of the above independently represents an alkyl group with 1 to 4 carbon atoms, a and b independently represent integers from 0 to 4, and * represents a bond.

Description

[Technical Field]

[0001] This invention relates to polyimide resins and varnishes. [Background technology]

[0002] Polyimide resins are widely used as thin films for electronic materials such as semiconductor protective materials, insulating materials, and color filters due to their high mechanical strength, heat resistance, insulation properties, and solvent resistance.

[0003] Patent Document 1 describes a polyimide resin comprising a constituent unit A derived from a tetracarboxylic dianhydride and a constituent unit B derived from a diamine compound, with the objective of providing a polyimide resin with a high glass transition temperature. The polyimide resin is described as having a constituent unit A comprising at least one of constituent units (A-1), (A-2), and (A-3) derived from a compound represented by a predetermined formula, and a constituent unit B comprising a constituent unit (B-1) derived from a compound represented by a predetermined formula, wherein the ratio of constituent unit (B-1) in constituent unit B is 60 mol% or more, and the glass transition temperature exceeds 410°C. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2017 / 191822 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] This invention provides a polyimide resin with an improved balance between solvent solubility and elastic modulus. [Means for solving the problem]

[0006] The inventors of the present invention have discovered that a polyimide resin containing predetermined structural units can improve the balance between solvent solubility and elastic modulus, and have completed the present invention.

[0007] In other words, the present invention provides the following polyimide resins and varnishes.

[0008] [1] A polyimide resin containing a constituent unit represented by the following general formula (1). [ka] (In general formula (1), X represents a divalent organic group (X) and Y represents a tetravalent organic group (Y), The aforementioned constituent unit (X) includes the constituent unit (X-1) represented by the following general formula (x1). [ka] (In general formula (x1), R 1 Each of these independently represents an alkyl group having 1 to 4 carbon atoms. a and b each independently represent integers between 0 and 4. * represents a bond. [2] The polyimide resin according to [1], wherein the constituent unit (Y) includes a constituent unit (Y-1) represented by the following general formula (y1). [ka] (In general formula (y1), R 3 Each of these independently represents an alkyl group having 1 to 4 carbon atoms. Z 1 This represents a single bond or a divalent organic group. e and f each independently represent integers from 0 to 4. * represents a bond. [3] The polyimide resin according to [2], wherein the ratio of the constituent unit (Y-1) in the constituent unit (Y) is 10 mol% or more. [4] The polyimide resin according to any one of [1] to [3], wherein the constitutional unit (Y) includes a constitutional unit (Y-2) represented by the following general formula (y2). [Chemical formula] (In the general formula (y2), Z 2 represents a single bond, -C(=O)-, or -SO2-, * represents a bond.) [5] The polyimide resin according to any one of [1] to [4], wherein the constitutional unit (X) further includes a constitutional unit (X-2) represented by the following general formula (x2). [Chemical formula] (In the general formula (x2), R 2 each independently represents an alkyl group having 1 to 4 carbon atoms, c and d each independently represent an integer of 0 to 4, * represents a bond.) [6] The polyimide resin according to any one of [1] to [5], wherein the constitutional unit (X) further includes a constitutional unit (X-3) represented by the following general formula (x3). [Chemical formula] (In the general formula (x3), * represents a bond.) [7] The polyimide resin according to any one of [1] to [6], having a storage modulus at 30°C of more than 3.3 GPa, measured by dynamic viscoelasticity measurement (DMA) in accordance with JIS K 7244-4:1999. [8] The polyimide resin according to any one of [1] to [7], having a glass transition temperature of 300°C or higher, measured by dynamic viscoelasticity measurement (DMA) in accordance with JIS K 7244-4:1999. [9] A polyimide resin as described in any one of [1] to [8], wherein the mean coefficient of linear expansion (CTE) in the range of 50°C to 100°C, as measured by thermomechanical analysis (TMA) in accordance with JIS K 7197:2012, is less than 49 ppm / °C.

[10] A polyimide resin according to any one of [1] to [9], wherein the maximum elongation at break at 23°C obtained by the following method is 5% or more. (method) A solution is prepared by dissolving 4 g of polyimide resin in 16 g of γ-butyrolactone. The solution is spin-coated onto an 8-inch silicon wafer, and then heated at 110°C for 3 minutes to dry the solution. The spin-coating is performed so that the film thickness after drying is 10 μm. Next, the wafer is heated at 170°C for 3 hours under a nitrogen atmosphere to form a cured film. The silicon wafer with the cured film is cut to a width of 7 mm using a dicing saw. The cut silicon wafer is immersed in a 2 mass% hydrofluoric acid aqueous solution to peel off the cured film from the silicon wafer. The peeled cured film is dried at 80°C for 90 minutes to obtain a cured film. A test piece (50 mm × 7 mm × 10 μm thick) is cut from the obtained cured film. In accordance with JIS K 7197:2012, a thermomechanical analyzer is used to measure the elongation at break from the initial position to the fracture point of the test specimen under the following conditions: air atmosphere, tensile mode, chuck distance of 20 mm, tensile speed of 5 mm / min, and 23°C. Measurements are performed on 10 test specimens, and the maximum value of the elongation at break is determined.

[11] A varnish comprising a polyimide resin and a solvent as described in any one of [1] to

[10] . [Effects of the Invention]

[0009] According to the present invention, a polyimide resin with an improved balance between solvent solubility and elastic modulus can be provided. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described below. In this specification, unless otherwise specified, "A to B" indicating a numerical range means A or greater and B or less.

[0011] (Polyimide resin) The polyimide resin of this embodiment includes a constituent unit represented by the following general formula (1).

[0012] [ka]

[0013] In general formula (1), X represents a divalent organic group (X) and Y represents a tetravalent organic group (Y).

[0014] In this embodiment, the constituent unit (X) includes the constituent unit (X-1) represented by the following general formula (x1).

[0015] [ka]

[0016] In general formula (x1), R 1 Each of these independently represents an alkyl group having 1 to 4 carbon atoms. a and b each independently represent integers between 0 and 4. * represents a bond.

[0017] In this embodiment, constituent unit (X) includes constituent unit (X-1). That is, since the polyimide resin of this embodiment has a cardo structure, it is thought that its solvent solubility can be improved. Furthermore, by including constituent unit (X) (X-1), it is thought that the balance between the solvent solubility and elastic modulus of the polyimide resin can be improved.

[0018] Furthermore, since the polyimide resin of this embodiment has a cardo structure, it is believed that its heat resistance can be improved. In other words, it is believed that the polyimide resin of this embodiment can improve the balance between solvent solubility and heat resistance.

[0019] The constituent unit (X-1) is considered to have a flexible structure because it contains two ether groups. Therefore, it is thought that the moldability of the polyimide resin can be improved by including the constituent unit (X-1) in the constituent unit (X).

[0020] In general formula (x1), R 1 Each of these independently represents an alkyl group having 1 to 4 carbon atoms. 1 It may contain at least one group selected from the group consisting of methyl group, ethyl group, isopropyl group, n-propyl group, and tert-butyl group, and may contain at least one group selected from the group consisting of methyl group and ethyl group, and may contain a methyl group.

[0021] In the general formula (x1), a and b each independently represent integers between 0 and 4. A and b can each independently be 0 or 1, or they can be 0.

[0022] The constituent unit (X-1) may include, for example, the constituent unit represented by the following formula (x11).

[0023] [ka]

[0024] The ratio of constituent unit (X-1) to constituent unit (X) is preferably 5 mol% to 100 mol%, more preferably 10 mol% to 90 mol%, even more preferably 15 mol% to 80 mol%, even more preferably 20 mol% to 70 mol%, and even more preferably 25 mol% to 60 mol%. By setting the ratio of constituent unit (X-1) to constituent unit (X) within the above range, the balance between the solvent solubility and elastic modulus of the polyimide resin can be further improved. Furthermore, the balance between the solvent solubility and heat resistance of the polyimide resin can be further improved.

[0025] The constituent units contained in the polyimide resin of this embodiment will be described in more detail below.

[0026] (Structural unit (X)) The structural unit (X) preferably further includes a structural unit (X-2) represented by the following general formula (x2).

[0027] [Chemical formula]

[0028] In the general formula (x2), R 2 each independently represents an alkyl group having 1 to 4 carbon atoms, c and d each independently represent an integer of 0 to 4, * represents a bond.

[0029] By the structural unit (X) including the structural unit (X-2), the solvent solubility of the polyimide resin can be further improved.

[0030] In the general formula (x2), R 2 each independently represents an alkyl group having 1 to 4 carbon atoms. R 2 may include at least one group selected from the group consisting of a methyl group, an ethyl group, an isopropyl group, an n-propyl group, and a tert-butyl group, may include at least one group selected from the group consisting of a methyl group and an ethyl group, and may include a methyl group.

[0031] In the general formula (x2), c and d each independently represent an integer of 0 to 4. From the viewpoint of further improving the elastic modulus, c and d each independently are preferably an integer of 0 to 2, more preferably 0 or 1, and still more preferably 1. From the viewpoint of improving the tensile elongation, c and d each independently are preferably an integer of 0 to 2, more preferably 0 or 1, and still more preferably 0.

[0032] From the viewpoint of further improving the elastic modulus of the polyimide resin, the constituent unit (X-2) preferably includes at least one selected from the group consisting of the constituent unit represented by the following formula (x21) and the constituent unit represented by the following formula (x22), and more preferably includes the constituent unit represented by the following formula (x21). From the viewpoint of improving the tensile elongation of the polyimide resin, the constituent unit (X-2) preferably includes at least one selected from the group consisting of the constituent unit represented by the following formula (x21) and the constituent unit represented by the following formula (x22), and more preferably includes the constituent unit represented by the following formula (x22).

[0033] [ka]

[0034] [ka]

[0035] The ratio of constituent unit (X-2) to constituent unit (X) is preferably greater than 0 mol% and 95 mol% or less, more preferably 10 mol% to 90 mol%, even more preferably 20 mol% to 85 mol%, even more preferably 30 mol% to 80 mol%, and even more preferably 40 mol% to 75 mol%. By setting the ratio of constituent unit (X-2) to constituent unit (X) within the above range, the balance between the solvent solubility and elastic modulus of the polyimide resin can be further improved. In addition, the balance between the solvent solubility and heat resistance of the polyimide resin can be further improved.

[0036] The ratio of constituent unit (X-2) to constituent unit (X-1) in constituent unit (X) is preferably greater than 0 mol% and 500 mol% or less, more preferably 25 mol% to 450 mol%, even more preferably 50 mol% to 400 mol%, even more preferably 75 mol% to 350 mol%, and even more preferably 100 mol% to 300 mol%. By setting the ratio of constituent unit (X-2) to constituent unit (X-1) within the above range, the balance between the solvent solubility and elastic modulus of the polyimide resin can be further improved.

[0037] The ratio of the constituent units represented by formula (x21) in constituent unit (X) is preferably greater than 0 mol% and 95 mol% or less, more preferably 10 mol% or more and 90 mol% or less, even more preferably 20 mol% or more and 85 mol% or less, even more preferably 30 mol% or more and 80 mol% or less, and even more preferably 40 mol% or more and 75 mol% or less. By setting the ratio of the constituent units represented by formula (x21) in constituent unit (X) within the above range, the balance between the solvent solubility and elastic modulus of the polyimide resin can be further improved.

[0038] The ratio of the constituent units represented by formula (x22) in constituent unit (X) is preferably greater than 0 mol% and 95 mol% or less, more preferably 10 mol% to 90 mol%, even more preferably 20 mol% to 85 mol%, even more preferably 30 mol% to 80 mol%, and even more preferably 40 mol% to 75 mol%. By setting the ratio of the constituent units represented by formula (x22) in constituent unit (X) within the above range, the balance between the solvent solubility and elastic modulus of the polyimide resin can be further improved. In addition, the tensile elongation of the polyimide resin can be improved.

[0039] The constituent unit (X) may further include the constituent unit (X-3) represented by the following general formula (x3).

[0040] [ka]

[0041] In the general formula (x3), * represents a bond.

[0042] The constituent unit (X-3) may include, for example, the constituent unit represented by the following formula (x31).

[0043] [ka]

[0044] (Constituent unit (Y)) The constituent unit (Y) preferably includes a constituent unit (Y-1) represented by the following general formula (y1).

[0045] [ka]

[0046] In general formula (y1), R 3 Each of these independently represents an alkyl group having 1 to 4 carbon atoms. Z 1 This represents a single bond or a divalent organic group. e and f each independently represent integers from 0 to 4. * represents a bond.

[0047] By including constituent unit (Y-1) within constituent unit (Y), the balance between the solvent solubility and elastic modulus of the polyimide resin can be further improved. Furthermore, the mean coefficient of linear thermal expansion (CTE) of the polyimide resin can be reduced.

[0048] In general formula (y1), R 3 Each of these independently represents an alkyl group having 1 to 4 carbon atoms. 3 Preferably, it comprises at least one group selected from the group consisting of methyl, ethyl, isopropyl, n-propyl, and tert-butyl groups, more preferably at least one group selected from the group consisting of methyl, isopropyl, and tert-butyl groups, and even more preferably a methyl group. This can further improve the solvent solubility of the polyimide resin. It can also reduce the mean coefficient of linear expansion (CTE) of the polyimide resin.

[0049] In the general formula (y1), e and f each independently represent integers from 0 to 4. e and f may also independently be integers from 0 to 3, or they may be 3.

[0050] In general formula (y1), Z 1 Z represents a single bond or a divalent organic group. 1Preferably, the group is a single bond, a cyclohexane-1,1-diyl group, a phenylene group, or a biphenyl-4,4'-diyl group, more preferably a single bond or a cyclohexane-1,1-diyl group, and even more preferably a single bond. This can further improve the solvent solubility of the polyimide resin. It can also reduce the mean coefficient of linear thermal expansion (CTE) of the polyimide resin.

[0051] The constituent unit (Y-1) preferably includes a constituent unit represented by the following formula (y11). This allows for a better balance between the solvent solubility and elastic modulus of the polyimide resin. It also allows for a reduction in the mean coefficient of linear thermal expansion (CTE) of the polyimide resin.

[0052] [ka]

[0053] The ratio of constituent unit (Y-1) to constituent unit (Y) is preferably 10 mol% or more, more preferably 20 mol% or more, even more preferably 30 mol% or more, even more preferably 40 mol% or more, and even more preferably 50 mol% or more. By setting the ratio of constituent unit (Y-1) to constituent unit (Y) to the above lower limit or higher, the balance between the solvent solubility and elastic modulus of the polyimide resin can be further improved. The upper limit of the ratio of constituent unit (Y-1) to constituent unit (Y) is not particularly limited, but for example, it may be 100 mol% or less, 95 mol% or less, or 90 mol% or less.

[0054] The ratio of the constituent units represented by formula (y11) in constituent unit (Y) is preferably 10 mol% or more, more preferably 20 mol% or more, even more preferably 30 mol% or more, even more preferably 40 mol% or more, and even more preferably 50 mol% or more. By setting the ratio of the constituent units represented by formula (y11) in constituent unit (Y) to be above the lower limit, the balance between the solvent solubility and elastic modulus of the polyimide resin can be further improved. The upper limit of the ratio of the constituent units represented by formula (y11) in constituent unit (Y) is not particularly limited, but for example, it may be 100 mol% or less, 95 mol% or less, or 90 mol% or less.

[0055] The constituent unit (Y) may include the constituent unit (Y-2) represented by the following general formula (y2).

[0056] [ka]

[0057] In general formula (y2), Z 2 This represents a single bond, -C(=O)-, or -SO2-. * represents a bond.

[0058] Z 2 This can be a single bond, or it can be -C(=O)-, or it can be -C(=O)-.

[0059] The constituent unit (Y-2) may include, for example, at least one selected from the group consisting of the constituent unit represented by the following formula (y21) and the constituent unit represented by the following formula (y22), and may also include the constituent unit represented by the following formula (y21).

[0060] [ka]

[0061] [ka]

[0062] The constituent unit (Y) may include the constituent unit represented by the following formula (y31).

[0063] [ka]

[0064] (Physical properties of polyimide resin) The physical properties of the polyimide resin of this embodiment will be described below.

[0065] In the polyimide resin of this embodiment, the storage modulus at 30°C, measured by dynamic viscoelasticity measurement (DMA) in accordance with JIS K 7244-4:1999, may be greater than 3.3 GPa and less than or equal to 20.0 GPa, 3.6 GPa or more and less than or equal to 15.0 GPa, 3.8 GPa or more and less than or equal to 10.0 GPa, or 3.9 GPa or more and less than or equal to 8.0 GPa.

[0066] In the polyimide resin of this embodiment, the glass transition temperature measured by dynamic viscoelasticity measurement (DMA) in accordance with JIS K 7244-4:1999 may be 300°C or more and 500°C or less, 310°C or more and 475°C or less, or 320°C or more and 450°C or less.

[0067] In the polyimide resin of this embodiment, the mean coefficient of linear expansion (CTE) in the range of 50°C to 100°C, measured by thermomechanical analysis (TMA) in accordance with JIS K 7197:2012, may be 15 ppm / °C or more and less than 49 ppm / °C, 20 ppm / °C or more and 45 ppm / °C or less, or 25 ppm / °C or more and 40 ppm / °C or less.

[0068] In the polyimide resin of this embodiment, the maximum value of the elongation at break at 23°C obtained by the following method may be 5% or more and 70% or less, 7% or more and 60% or less, or 9% or more and 50% or less.

[0069] (method) A solution is prepared by dissolving 4 g of polyimide resin in 16 g of γ-butyrolactone. The solution is spin-coated onto an 8-inch silicon wafer, and then heated at 110°C for 3 minutes to dry the solution. The spin-coating is performed so that the film thickness after drying is 10 μm. Next, the wafer is heated at 170°C for 3 hours under a nitrogen atmosphere to form a cured film. The silicon wafer with the cured film is cut to a width of 7 mm using a dicing saw. The cut silicon wafer is immersed in a 2 mass% hydrofluoric acid aqueous solution to peel off the cured film from the silicon wafer. The peeled cured film is dried at 80°C for 90 minutes to obtain a cured film. A test piece (50 mm × 7 mm × 10 μm thick) is cut from the obtained cured film. In accordance with JIS K 7197:2012, a thermomechanical analyzer is used to measure the elongation at break from the initial position to the fracture point of the test specimen under the following conditions: air atmosphere, tensile mode, chuck distance of 20 mm, tensile speed of 5 mm / min, and 23°C. Measurements are performed on 10 test specimens, and the maximum value of the elongation at break is determined.

[0070] (Method for manufacturing polyimide resin) The polyimide resin of this embodiment can be obtained, for example, by imidizing a diamine and an acidic dianhydride in an organic solvent.

[0071] The ratio (molar ratio) of the amount of diamine added to the amount of acidic dianhydride added is not particularly limited, but may be, for example, 0.70 or more and 1.30 or less.

[0072] Organic solvents are, for example, aprotic polar solvents such as γ-butyrolactone (GBL), N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, cyclohexanone, and 1,4-dioxane; Aromatic hydrocarbons such as toluene, ethylbenzene, xylene, and mesitylene; and, It may also contain at least one selected from the group consisting of ether-based solvents such as cyclopentyl methyl ether.

[0073] (varnish) The varnish of this embodiment comprises the polyimide resin and solvent of this embodiment.

[0074] The solvent may include, for example, at least one selected from the group consisting of acetone, methyl ethyl ketone, toluene, propylene glycol methyl ethyl ether, propylene glycol dimethyl ether, propylene glycol 1-monomethyl ether 2-acetate, diethylene glycol ethyl methyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, benzyl alcohol, propylene carbonate, ethylene glycol diacetate, propylene glycol diacetate, propylene glycol monomethyl ether acetate, dipropylene glycol methyl-n-propyl ether, butyl acetate, γ-butyrolactone, methyl lactate, ethyl lactate, and butyl lactate.

[0075] Although embodiments of the present invention have been described above, these are merely examples, and various other configurations can be adopted. Furthermore, the present invention is not limited to the embodiments described above, and modifications, improvements, etc., within the scope that can achieve the objectives of the present invention are included in the present invention. [Examples]

[0076] The present invention will be described in detail below with reference to examples. However, the present invention is not limited in any way to the descriptions in these examples.

[0077] (1) Raw materials The raw materials used in each example and comparative example are shown below.

[0078] (Diamine) BPF-AN: Represented by the following formula, 9,9-bis[4-(4-aminophenoxy)phenyl]fluorene [ka]

[0079] OTBAF: 9,9-bis(4-amino-3-methylphenyl)fluorene, represented by the following formula. [ka]

[0080] BAF: 9,9-bis(4-aminophenyl)fluorene, represented by the following formula. [ka]

[0081] DABA: 3,5-diaminobenzoic acid, represented by the following formula. [ka]

[0082] MED-J: 4,4-diamino-3,3-diethyl-5,5-dimethyldiphenylmethane, represented by the following formula. [ka]

[0083] 1,5-DAN: 1,5-diaminonaphthalene, represented by the following formula. [ka]

[0084] (acid dianhydride) TMPBP-TME: Represented by the following formula, 2,2',3,3',5,5'-hexamethyl[1,1'-biphenyl]-4,4'-diyl=bis(1,3-dioxo-1,3-dihydro-2-benzofuran-5-carboxylate) (manufactured by Honshu Chemical Industry Co., Ltd.) [ka]

[0085] BTDA: A dianhydride of 3,3',4,4'-benzophenonetetracarboxylic acid, represented by the following formula. [ka]

[0086] PMDA: Pyromellitic anhydride, represented by the following formula. [ka]

[0087] (2) Synthesis of polyimide resin In a flask equipped with a Dean-Stark apparatus, 9 g of diamine, 11 g of acidic dianhydride, and solvents (88 g of 3-methyl-2-oxazolidone and 16 g of cyclopentyl methyl ether) were added. The starting material compositions of the diamine and acidic dianhydride are shown in Table 1 (units are molar ratios). The mixture was then stirred at room temperature for 10 minutes under a nitrogen atmosphere, and then heated in an oil bath and reacted at 150°C for 1 hour. 3 g of 2,6-lutidine was added as a dehydration catalyst, and the reaction was further carried out at 190°C for 4 hours. After the reaction solution was cooled to room temperature, it was diluted with tetrahydrofuran, and isopropanol was added dropwise to precipitate a solid. The obtained solid was filtered, washed, and vacuum-dried at 60°C to obtain a polyimide resin.

[0088] (3) Evaluation of polyimide resins (Preparation of cured polyimide resin films) A solution was prepared by dissolving 4 g of polyimide resin in 16 g of γ-butyrolactone. The solution was spin-coated onto an 8-inch silicon wafer, and then heated at 110°C for 3 minutes to dry the solution. The spin-coating was performed to achieve a film thickness of 10 μm after drying. Next, the wafer was heated at 170°C for 3 hours under a nitrogen atmosphere to form a cured film. The silicon wafer with the cured film was cut into 7 mm wide strips using a dicing saw. The cut silicon wafer was immersed in a 2% by mass aqueous hydrofluoric acid solution to peel off the cured film from the silicon wafer. The peeled cured film was dried at 80°C for 90 minutes to obtain a cured film.

[0089] (Dynamic viscoelasticity measurement) A test specimen (30 mm × 7 mm × 10 μm thick) was cut from the obtained cured film. Dynamic viscoelasticity measurements (DMA) were performed using a dynamic viscoelasticity analyzer (TA Instruments "Q800") in accordance with JIS K 7244-4:1999, under the conditions of an air atmosphere, frequency of 1 Hz, tensile mode, heating rate of 5 °C / min, chuck distance of 20 mm, and heating from 30 °C to 400 °C. The storage modulus at 30 °C was read from the obtained temperature-storage modulus (E') graph. In addition, the temperature at which the loss tangent (tanδ) was maximum in the obtained temperature-storage tangent (tanδ) graph was defined as the glass transition temperature (Tg).

[0090] (Measurement of mean linear thermal expansion coefficient) A test specimen (20 mm × 4 mm × 10 μm thick) was cut from the obtained cured film. Thermomechanical analysis (TMA) was performed in accordance with JIS K 7197:2012 using a thermomechanical analyzer (Hitachi High-Tech Corporation "TMA-7100C") under nitrogen atmosphere, tensile mode, heating rate of 10 °C / min, chuck distance of 10 mm, and heating from 30 °C to 400 °C. The mean coefficient of linear expansion (CTE) in the range of 50 °C to 100 °C was determined from the obtained temperature-displacement graph.

[0091] (Measurement of elongation at break) A test specimen (50 mm × 7 mm × 10 μm thick) was cut from the obtained cured film. In accordance with JIS K 7197:2012, the elongation at break from the initial position to the breaking point of the test specimen was measured using a thermomechanical analyzer (A&D Corporation "STB-1225S") under the conditions of air atmosphere, tensile mode, chuck distance of 20 mm, tensile speed of 5 mm / min, and 23°C. Measurements were performed on 10 test specimens, and the maximum value of the elongation at break was determined.

[0092] (Evaluation of solvent solubility) A solution was prepared by dissolving 4 g of polyimide resin in 16 g of γ-butyrolactone. The solution was allowed to stand at 25°C for 3 hours to stabilize its temperature. While measuring the viscosity of the solution using a viscometer (TV-25 viscometer, cone-plate type, manufactured by Toki Sangyo Co., Ltd.), γ-butyrolactone was further added to the solution and diluted until the viscosity reached 2000 ± 200 mPa·s to obtain a solution for solubility evaluation. The solution for solubility evaluation was filtered under pressure with nitrogen gas for 30 minutes using a 3M Lab Scale Filter Disc DP Series (NM04711 BF100) (material: polypropylene, filtration accuracy: 10.0 μm) as a filter. The presence or absence of residue on the filter after filtration was visually confirmed, and the solvent solubility of the polyimide resin was evaluated according to the following criteria. A: No residue was found. B: Residue was found.

[0093] Table 1 shows the evaluation results for each example and comparative example.

[0094] [Table 1]

Claims

1. A polyimide resin containing a constituent unit represented by the following general formula (1). 【Chemistry 1】 (In general formula (1), X represents a divalent organic group (X) and Y represents a tetravalent organic group (Y), The aforementioned constituent unit (X) includes the constituent unit (X-1) represented by the following general formula (x1). 【Chemistry 2】 (In general formula (x1), R １ Each of these independently represents an alkyl group having 1 to 4 carbon atoms. a and b each independently represent integers from 0 to 4. * indicates a bonding operation.

2. The polyimide resin according to claim 1, wherein the aforementioned constituent unit (Y) includes a constituent unit (Y-1) represented by the following general formula (y1). 【Transformation 3】 (In general formula (y1), R ３ Each of these independently represents an alkyl group having 1 to 4 carbon atoms. Z １ This represents a single bond or a divalent organic group. e and f each independently represent integers from 0 to 4. * indicates a bonding operation.

3. The polyimide resin according to claim 2, wherein the ratio of the constituent unit (Y-1) in the constituent unit (Y) is 10 mol% or more.

4. The polyimide resin according to any one of claims 1 to 3, wherein the constituent unit (Y) includes a constituent unit (Y-2) represented by the following general formula (y2). 【Chemistry 4】 (In general formula (y2), Z ２ This is a single bond, -C(=O)-, or -SO ２ - represents, * indicates a bonding operation.

5. The polyimide resin according to any one of claims 1 to 3, wherein the constituent unit (X) further comprises a constituent unit (X-2) represented by the following general formula (x2). 【Transformation 5】 (In general formula (x2), R ２ Each of these independently represents an alkyl group having 1 to 4 carbon atoms. c and d each independently represent integers from 0 to 4. * indicates a bonding operation.

6. The polyimide resin according to any one of claims 1 to 3, wherein the aforementioned constituent unit (X) further comprises a constituent unit (X-3) represented by the following general formula (x3). 【Transformation 6】 (In the general formula (x3), * represents a bond.)

7. A polyimide resin according to any one of claims 1 to 3, wherein the storage modulus at 30°C is greater than 3.3 GPa, as measured by dynamic viscoelasticity measurement (DMA) in accordance with JIS K 7244-4:1999.

8. A polyimide resin according to any one of claims 1 to 3, wherein the glass transition temperature, as measured by dynamic viscoelastic analysis (DMA) in accordance with JIS K 7244-4:1999, is 300°C or higher.

9. A polyimide resin according to any one of claims 1 to 3, wherein the mean coefficient of linear thermal expansion (CTE) in the range of 50°C to 100°C, as measured by thermomechanical analysis (TMA) in accordance with JIS K 7197:2012, is less than 49 ppm / °C.

10. The polyimide resin according to any one of claims 1 to 3, wherein the maximum value of the elongation at break at 23°C obtained by the following method is 5% or more. (method) Prepare a solution by dissolving 4 g of polyimide resin in 16 g of γ-butyrolactone. Spin coat the solution onto an 8-inch silicon wafer, then heat at 110°C for 3 minutes to dry the solution. Spin coating is performed so that the film thickness after drying is 10 μm. Next, heat at 170°C for 3 hours under a nitrogen atmosphere to form a cured film. Using a dicing saw, the silicon wafer with the hardened film formed on it is cut into strips 7 mm wide. The cut silicon wafer is immersed in a 2% hydrofluoric acid aqueous solution to peel off the hardened film from the silicon wafer. The peeled hardened film is dried at 80°C for 90 minutes to obtain a hardened film. A test piece (50 mm × 7 mm × 10 μm thick) is cut from the obtained hardened film. In accordance with JIS K 7197:2012, the elongation at break from the initial position to the breaking point of the test piece is measured using a thermomechanical analyzer under air atmosphere, tensile mode, chuck distance of 20 mm, tensile speed of 5 mm / min, and 23°C. Measurements are performed on 10 test pieces to determine the maximum elongation at break.

11. A varnish comprising the polyimide resin and solvent according to any one of claims 1 to 3.

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