CN116178712A - Polyimide resin precursor - Google Patents

Abstract

The present invention relates to a polyimide resin precursor. A polyimide-based resin precursor comprising a structural unit (A) derived from a tetracarboxylic anhydride and a structural unit (B) derived from a diamine, wherein the structural unit (A) comprises a structural unit (A1) derived from a tetracarboxylic anhydride containing an ester bond and a structural unit (A2) derived from a tetracarboxylic anhydride containing a biphenyl skeleton, the structural unit (A) satisfies the relationship of formula (X), the structural unit (B) comprises a structural unit (B1) derived from a diamine containing a biphenyl skeleton, and the content of the structural unit (B1) is more than 30 mol% based on the total amount of the structural units (B), and the polyimide-based resin precursor has a weight average molecular weight in terms of polystyrene of more than 100,000. (content of structural unit (A3) derived from tetracarboxylic anhydride excluding the structural unit (A1) and the structural unit (A2)/(total amount of the structural unit (A1) and the structural unit (A2)) <0.67 (X).

Description

Polyimide resin precursor

technical field

It relates to a polyimide-based resin precursor that can be used as a substrate material for a high-frequency-compatible printed circuit board and an antenna substrate.

Background technique

Flexible printed circuit boards (hereinafter, sometimes referred to as FPC) are thin, lightweight, and flexible, so they can be mounted in a three-dimensional and high-density manner, and are used in many electronic devices such as mobile phones and hard disks, contributing to their Miniaturization and light weight. Conventionally, polyimide resins excellent in heat resistance, mechanical properties, and electrical insulation have been widely used for FPC.

In recent years, the fifth-generation mobile communication system called 5G has been thoroughly popularized. In the polyimide material used in the past, when transmitting high-frequency signals used for 5G communication, the transmission loss is large, and problems such as loss of electrical signals and long delay times of signals occur. Therefore, polyimide films with low dielectric loss tangent (hereinafter, sometimes described as Df) and relative permittivity (hereinafter, sometimes described as Dk) have been studied for the purpose of reducing transmission loss.

In addition, for FPC, its use is expanding to components such as wiring, cables, and connectors of the movable part of electronic equipment, and foldable devices have been launched on the market, and the demand for FPC with higher bending resistance is increasing. Therefore, a polyimide film not only low in Df and Dk but also excellent in bending resistance is required.

For example, Patent Document 1 discloses a polyamide obtained by reacting a tetracarboxylic anhydride component containing ester-containing tetracarboxylic anhydride and biphenyltetracarboxylic anhydride with a diamine component containing 75 mol % or more of p-phenylenediamine. An imide resin precursor, and a polyimide resin obtained by curing the aforementioned polyimide resin precursor. In Patent Document 2, a polyimide film having a non-thermoplastic polyimide layer containing a non-thermoplastic polyimide and a thermoplastic polyimide layer containing a thermoplastic polyimide is disclosed, the aforementioned non-thermoplastic polyimide Thermoplastic polyimides contain tetracarboxylic acid residues, and diamine residues derived from specific diamine compounds. The tetracarboxylic acid residues include 3,3',4,4'-biphenyltetracarboxylic Anhydride (BPDA) derived tetracarboxylic acid residues (BPDA residues) and tetracarboxylic acid residues derived from 1,4-phenylene bis(trimellitic monoester) dianhydride (TAHQ) (TAHQ residues ) at least 1 etc. In addition, Patent Document 3 discloses a polyimide precursor resin composition containing aromatic A polyimide precursor resin composition obtained by polycondensation of an aromatic tetracarboxylic dianhydride and a diamine, wherein at least one of the above-mentioned aromatic tetracarboxylic dianhydride and the above-mentioned diamine has a biphenyl skeleton, and the above-mentioned has a biphenyl Content of the skeleton component is 40 mol% or more with respect to the total amount of the said aromatic tetracarboxylic dianhydride and the said diamine, The said aromatic tetracarboxylic dianhydride contains 5 mol% with respect to the said total amount The above p-phenylene bis(trimellitic acid monoester anhydride).

patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2018-150544

Patent Document 2: International Publication No. 2018/061727

Patent Document 3: Japanese Patent Laid-Open No. 2014-208793

Contents of the invention

As metal-clad laminates such as copper-clad laminates (hereinafter, sometimes referred to as CCL) used in FPC, metal foils such as copper foil layers on one or both sides of single-layer or multi-layer polyimide-based resins are widely used. of stacks. Metal-clad laminates such as CCL with a polyimide film are sometimes formed by casting a polyimide-based resin precursor solution on a metal foil such as copper foil, and coating the polyimide-based resin precursor. The film is produced by thermal imidization, and the thermal imidization is usually performed by heating at a high temperature of, for example, about 360°C.

In transmission of high-frequency current, a phenomenon called a skin effect in which current flows densely near the surface of a conductor becomes remarkable. Therefore, when a metal-clad laminate such as CCL is used in a high-frequency circuit, the roughness and oxidation of the surface of metal foil such as copper foil tend to cause an increase in transmission loss. For example, when copper foil is heated at a high temperature of 350° C. or higher, roughness of the copper foil surface, increase in crystal grain size, oxidation, etc. tend to occur, and the interface tends to become rough easily. In addition, when the crystal grain size on the surface of the copper foil increases, the bending resistance of the copper foil tends to decrease, and the bending resistance of the CCL tends to decrease.

Therefore, exposure of metal foils such as copper foil to high temperatures together with polyimide-based resins in the thermal imidization process will lead to an increase in transmission loss and a decrease in bending resistance.

According to the studies of the inventors of the present application, conventional polyimide resins may not be able to sufficiently reduce Df and Dk. In order to sufficiently reduce the Df and Dk of these polyimide resins and polyimide films, thermal imidization is performed at a high temperature of 350°C or higher to produce metal-clad laminates such as CCL, and copper foil is generated as described above. Therefore, it is difficult to simultaneously realize the suppression of roughness and oxidation of the metal foil surface and the reduction of the Df of the polyimide layer to form a CCL with low transmission loss when used in high-frequency circuits. Metal laminate. In addition, conventional polyimide films may not have sufficient bending resistance.

Therefore, an object of the present invention is to provide a polyimide-based resin precursor capable of forming a polyimide-based film having low Df and excellent bending resistance even when the thermal imidization temperature is low.

The inventors of the present application conducted intensive studies to solve the above-mentioned problems, and as a result, completed the present invention. That is, the present invention provides the following preferred embodiments.

[1] a polyimide-based resin precursor, which is a polyimide-based resin precursor comprising a structural unit (A) derived from tetracarboxylic anhydride and a structural unit (B) derived from diamine,

The aforementioned structural unit (A) includes a structural unit (A1) derived from a tetracarboxylic anhydride containing an ester bond and a structural unit (A2) derived from a tetracarboxylic anhydride containing a biphenyl skeleton,

The aforementioned structural unit (A) satisfies the relationship of formula (X),

(Content of tetracarboxylic anhydride-derived structural unit (A3) other than the aforementioned structural unit (A1) and the aforementioned structural unit (A2))/(The total amount of the aforementioned structural unit (A1) and the aforementioned structural unit (A2))< 0.67(X)

The aforementioned structural unit (B) contains a structural unit (B1) derived from a diamine containing a biphenyl skeleton, and the content of the aforementioned structural unit (B1) is greater than 30 mol % relative to the total amount of the aforementioned structural unit (B),

The polyimide-type resin precursor has a weight average molecular weight of more than 100,000 in terms of polystyrene.

[2] The polyimide resin precursor according to [1], wherein the structural unit (A1) is a structural unit (a1) derived from tetracarboxylic anhydride represented by formula (a1).

[in the formula (a1), Z represents a divalent organic group,

R ^a1 each independently represents a halogen atom, or an alkyl, alkoxy, aryl or aryloxy group which may have a halogen atom,

s independently represent an integer of 0 to 3]

[3] The polyimide resin precursor according to [1] or [2], wherein the structural unit (A2) is a structural unit (a2) derived from tetracarboxylic anhydride represented by formula (a2).

[In the formula (a2), R ^a2 independently represent a halogen atom, or an alkyl, alkoxy, aryl or aryloxy group that may have a halogen atom,

t each independently represents an integer of 0 to 3]

[4] The polyimide-based resin precursor according to any one of [1] to [3], wherein the structural unit (B1) is a structural unit (b1) derived from a diamine represented by the formula (b1) ).

[In the formula (b1), R ^b1 independently represent a halogen atom, or an alkyl, alkoxy, aryl or aryloxy group that may have a halogen atom,

p represents an integer from 0 to 4]

[5] The polyimide-based resin precursor according to any one of [1] to [4], wherein the structural unit (B) further includes a structural unit derived from a diamine represented by formula (b2) ( b2).

[In the formula (b2), R ^b2 independently represent a halogen atom, or an alkyl, alkoxy, aryl or aryloxy group that may have a halogen atom,

W independently represent -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -COO -, -OOC-, -SO ₂ -, -S-, -CO- or -N(R ^c )-, R ^c represents a hydrogen atom, a monovalent hydrocarbon group with 1 to 12 carbon atoms which may be substituted by a halogen atom, m is an integer of 1 to 4,

q independently represent an integer of 0 to 4]

[6] The polyimide resin precursor according to [5], wherein, in the structural unit (b2), m is 3, and W are independently -O- or -C(CH ₃ ) ₂ - .

[7] A polyimide-based resin obtained from the polyimide-based resin precursor according to any one of [1] to [6].

[8] The polyimide-based resin according to [7], which has a glass transition temperature of 200 to 290°C.

[9] The polyimide-based resin according to [7] or [8], which has a storage elastic modulus at 280° C. of less than 3×10 ⁸ Pa.

[10] A polyimide-based film comprising the polyimide-based resin according to any one of [7] to [9].

[11] The polyimide film according to [10], which has a dielectric loss tangent at 10 GHz of 0.004 or less.

[12] A laminated film comprising a metal foil layer on one or both sides of the polyimide film according to [10] or [11].

[13] A flexible printed circuit board comprising the polyimide film according to [10] or [11].

Invention effect

According to the present invention, it is possible to provide a polyimide resin precursor capable of forming a polyimide-based film having low Df and excellent bending resistance even when the thermal imidization temperature is low.

Detailed ways

Hereinafter, embodiments of the present invention will be described in detail. In addition, the scope of this invention is not limited to embodiment demonstrated here, Various changes are possible in the range which does not deviate from the summary of this invention.

〔Polyimide resin precursor〕

The polyimide resin precursor of the present invention comprises a structural unit (A) (hereinafter, sometimes abbreviated as structural unit (A)) from tetracarboxylic anhydride and a structural unit (B) from diamine (hereinafter, sometimes abbreviated as structure unit (B)), the structural unit (A) includes a structural unit (A1) derived from a tetracarboxylic anhydride containing an ester bond (hereinafter, sometimes abbreviated as a structural unit (A1)) and a structure derived from a tetracarboxylic anhydride containing a biphenyl skeleton Unit (A2) (hereinafter, sometimes abbreviated as structural unit (A2)), structural unit (A) satisfies formula (X): (except structural unit (A1) and structural unit (A2) from the structural unit of tetracarboxylic anhydride (A3) content)/(total amount of structural unit (A1) and structural unit (A2))<0.67 (X), structural unit (B) contains structural unit derived from diamine containing biphenyl skeleton (B1 ) (hereinafter, sometimes simply referred to as structural unit (B1)), relative to the total amount of structural unit (B), the content of structural unit (B1) is greater than 30 mol%, the polyimide resin precursor of the present invention The polystyrene-equivalent weight-average molecular weight (hereinafter, the weight-average molecular weight may be described as Mw) is greater than 100,000.

In this specification, polyimide may be described as PI. In the present invention, the so-called "structural unit from ..." refers to "the structural unit from ...", for example, "the structural unit (A) from tetracarboxylic anhydride" refers to "the structural unit from tetracarboxylic anhydride ( A)".

The inventors of the present application have found that if the structural unit (A) in the PI-based resin precursor satisfies the relationship of formula (X), the content of the structural unit (B1) is greater than 30 mol%, and the Mw is greater than 100,000, then even thermal acyl A PI-based resin precursor that can form a PI-based film with a low Df and excellent bending resistance at a low temperature for amination. It is inferred that this is because, if the structural unit (A) satisfies the relationship of the formula (X), the content of the structural unit (B1) is within the above-mentioned range, and the Mw is within the above-mentioned range, then the PI-based resin precursor is thermally acylated. When a PI-based resin is obtained by imidization, even if the thermal imidization temperature is low, the amic acid site and the imide site move simultaneously to easily form a higher-order structure, and the obtained PI-based resin is easy to form a suppressed The ideal high-order structure of molecular chain rotation, therefore, can inhibit the rotation of polar groups in PI-based resins and reduce the loss of electrical energy in the form of thermal motion. Therefore, the PI-based resin precursor of the present invention can form a PI-based film capable of reducing Df while maintaining excellent bending resistance even when the thermal imidization temperature is low.

The structural unit (A) contained in the PI-based resin precursor satisfies the relationship of formula (X), that is, the value on the left side of formula (X) is less than 0.67. Therefore, the imide group concentration of the PI-based resin obtained from the PI-based resin precursor of the present invention is easily reduced, so the moisture absorption resistance of the obtained PI-based resin is improved, and the Df of the obtained PI-based film is easily reduced. As a result, Even if the imidization temperature of the PI-based resin is low, the Df of the obtained PI-based film tends to be lowered.

(Content of structural unit (A3) derived from tetracarboxylic anhydride other than structural unit (A1) and structural unit (A2))/(total amount of structural unit (A1) and structural unit (A2))<0.67(X)

In one embodiment of the present invention, the value on the left side of the formula (X) is preferably 0.6 or less, more preferably 0.5 or less, more preferably 0.4 or less, still more preferably 0.3 or less, particularly preferably 0.20 or less. In addition, the lower limit of the value on the left side of the formula (X) is not particularly limited, and may be 0 or more.

The denominator on the left side of the formula (X), that is, the total amount of the structural unit (A1) and the structural unit (A2) relative to the total amount of the structural unit (A) is not particularly limited, as long as the formula (X) is satisfied, Even if the imidization temperature is low, the Df of the obtained PI-based film can be easily lowered and the bending resistance can be easily improved. With respect to the total amount of the structural unit (A), it is preferably 50 mol% or more, It is more preferably 60 mol% or more, still more preferably 70 mol% or more, still more preferably 80 mol% or more, particularly preferably 90 mol% or more. Moreover, the upper limit of the total amount of a structural unit (A1) and a structural unit (A2) is not specifically limited, For example, it may be 100 mol% or less. The ratio of the aforementioned structural units can be measured using, for example, ¹ H-NMR, or can be calculated from the input ratio of raw materials.

The molecule on the left side of the formula (X), that is, the structural unit (A3) derived from tetracarboxylic anhydride other than the structural unit (A1) and the structural unit (A2) relative to the total amount of the structural unit (A) (hereinafter, Sometimes the content of the structural unit (A3)) is not particularly limited, as long as the formula (X) is satisfied, relative to the total amount of the structural unit (A), for example, it can be 0 to 40 mol%, preferably 40 mol % or less, more preferably 35 mol% or less, further preferably 30 mol% or less, particularly preferably 25 mol% or less, particularly more preferably 20 mol% or less, particularly more preferably 15 mol% or less, and preferably 0 mol% or more, more preferably 0.01 mol% or more, still more preferably 10 mol% or more. When the content of the structural unit (A3) is within the above range, the obtained PI-based resin is likely to be oriented, and therefore, the Df of the obtained PI-based film tends to decrease, and the bending resistance tends to be improved.

The ratio of the aforementioned structural units can be measured using, for example, ¹ H-NMR, or can be calculated from the input ratio of raw materials.

It should be noted that, in this description, the so-called "structural unit (A3) from tetracarboxylic anhydride other than structural unit (A1) and structural unit (A2)" means that it does not belong to structural unit (A1) and structural unit ( The structural unit derived from tetracarboxylic anhydride in any one of A2), "the content of structural unit (A3)" means the total amount of structural unit (A3) when a plurality of structural units (A3) exist.

From the point of view that the Df of the obtained PI-based film can be easily lowered and the bending resistance can be easily improved even if the imidization temperature is low, the structural unit (B1) ( The content of the structural unit (b1)) described below is preferably more than 30 mol%, preferably 35 mol% or more, more preferably 40 mol% or more, still more preferably 60 mol% or more, and even more preferably 70 mol% or more, It is particularly preferably 80 mol % or more, and particularly more preferably 90 mol % or more. In addition, the upper limit of the content of the structural unit (B1) (preferably a structural unit (b1) described later) is not particularly limited, and may be 100 mol% or less based on the total amount of the structural unit (B). The ratio of the aforementioned structural units can be measured using, for example, ¹ H-NMR, or can be calculated from the input ratio of raw materials.

From the viewpoint of easily lowering the Df of the obtained PI-based film and improving the bending resistance, the Mw of the PI-based resin precursor is greater than 100,000 in terms of polystyrene, preferably 110,000 or more, more preferably 120,000 or more, and even more preferably It is 130,000 or more, particularly preferably 140,000 or more. In addition, from the viewpoint of processability during film formation, it is preferably 1,000,000 or less, more preferably 700,000 or less, still more preferably 500,000 or less, still more preferably 400,000 or less, particularly preferably 300,000 or less.

From the viewpoint of easy improvement of bending resistance, the ratio (Mw/Mn) of the Mw of the PI-based resin precursor to the number average molecular weight (hereinafter, the number average molecular weight may be described as Mn) is preferably 3.5 or more in terms of polystyrene. , more preferably 4.0 or more, more preferably 4.2 or more, still more preferably 4.5 or more, particularly preferably 4.7 or more, preferably 8.0 or less, more preferably 7.0 or less, further preferably 6.0 or less, particularly preferably 5.5 or less.

It should be noted that Mw and Mn can be measured by gel permeation chromatography (hereinafter, sometimes referred to as GPC), and can be obtained in terms of standard polystyrene, for example, by the method described in the examples. .

<Structural unit (A) derived from tetracarboxylic anhydride>

The PI-based resin precursor of the present invention contains a structural unit (A) derived from tetracarboxylic anhydride.

(Structural unit (A1) derived from tetracarboxylic anhydride containing ester bond)

The structural unit (A) contains the structural unit (A1) derived from tetracarboxylic anhydride containing an ester bond. If the structural unit (A) contains the structural unit (A1), the ester bond with molecular orientation is introduced into the PI-based resin precursor. Therefore, after the PI-based resin precursor solution is applied to the substrate and Orientation is easy in the imidization process of a coating film, and even if imidization temperature is low, Df of the PI-type film obtained will fall easily. In addition, the ester bond can be rotated to maintain flexibility, so it is easy to improve the bending resistance of the obtained PI-based film, and it is easy to reduce the coefficient of linear expansion (hereinafter, sometimes described as CTE), and it is easy to increase the size of the PI-based film. stability.

In one embodiment of the present invention, the structural unit (A1) is not particularly limited as long as it contains an ester bond. The ester bond contained in the structural unit (A1) may be one or two or more. The structural unit (a1) derived from the tetracarboxylic anhydride represented by formula (a1) is preferable from the viewpoint that the Df of the obtained PI-based film is easily lowered even at a low temperature, and the bending resistance is easily improved.

[in the formula (a1), Z represents a divalent organic group,

R ^a1 each independently represents a halogen atom, or an alkyl, alkoxy, aryl or aryloxy group which may have a halogen atom,

s independently represent an integer of 0 to 3]

R ^a1 in the formula (a1) independently represents a halogen atom, or an alkyl, alkoxy, aryl, or aryloxy group that may have a halogen atom, so that even if the imidization temperature is low, it is easy to reduce the From the viewpoint of Df of the obtained PI-based film, it is preferable to independently represent an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms.

Examples of the alkyl group having 1 to 6 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, 2- Methylbutyl, 3-methylbutyl, 2-ethylpropyl, n-hexyl, etc.

Examples of the alkoxy group having 1 to 6 carbon atoms include methoxy, ethoxy, propyloxy, isopropyloxy, n-butoxy, isobutoxy, sec-butoxy, t- Butoxy, pentyloxy, hexyloxy and cyclohexyloxy, etc.

Examples of the aryl group having 6 to 12 carbon atoms include phenyl, tolyl, xylyl, naphthyl, biphenyl and the like.

The hydrogen atoms included in R ^a1 may be independently substituted by halogen atoms, and examples of the halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

Among them, from the viewpoint of easily lowering the Df of the PI-based film even if the imidization temperature is low, R ^a1 is independently preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms. An alkyl group having 1 to 3 carbon atoms is mentioned.

Moreover, s in Formula (a1) mutually independently represents the integer of 0-3, Preferably it represents 0 or 1, More preferably, it represents 0.

Z in the formula (a1) represents a divalent organic group. As the divalent organic group, it preferably represents a divalent organic group having 4 to 40 carbon atoms, and more preferably represents a cyclic structure having 4 to 40 carbon atoms. The divalent organic group in is more preferably a divalent organic group having 4 to 40 carbon atoms having an aromatic ring. Among them, Z is preferably divalent represented by formula (z1), formula (z2), or formula (z3), from the viewpoint of easily lowering the Df of the obtained PI-based film even if the imidization temperature is low. The organic group is more preferably a divalent organic group represented by formula (z1).

[In formula (z1) to formula (z3), R ^z11 to R ^z14 independently represent a hydrogen atom or a monovalent hydrocarbon group that may have a halogen atom,

R ^z2 each independently represent a monovalent hydrocarbon group which may have a halogen atom,

n represents an integer of 1 to 4,

j each independently represents an integer of 0 to 3,

*Indicates a connection key]

In one embodiment of the present invention, R ^z11 to R ^z14 in formula (z1) independently represent a hydrogen atom or a monovalent hydrocarbon group which may have a halogen atom.

Examples of the monovalent hydrocarbon group include aromatic hydrocarbon groups, alicyclic hydrocarbon groups, and aliphatic hydrocarbon groups.

Examples of the aromatic hydrocarbon group include aryl groups such as phenyl, tolyl, xylyl, naphthyl and biphenyl, and the like.

Examples of the alicyclic hydrocarbon group include cycloalkyl groups such as cyclopentyl and cyclohexyl, and the like.

Examples of aliphatic hydrocarbon groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, 2-methylbutyl, 3-methylbutyl Alkyl group, 2-ethylpropyl group, n-hexyl group, n-heptyl group, n-octyl group, t-octyl group, n-nonyl group, n-decyl group, etc.

Examples of the halogen atom include those described above.

From the viewpoint that Df of the PI-based film is easily lowered even if the imidization temperature is low, R ^z11 to R ^z14 independently of each other preferably represent a hydrogen atom or an alkyl group that may have a halogen atom, and more preferably represent a hydrogen atom, Or an alkyl group having 1 to 6 carbon atoms which may have a halogen atom, more preferably a hydrogen atom, or an alkyl group having 1 to 3 carbon atoms which may have a halogen atom, particularly preferably a hydrogen atom.

In one embodiment of the present invention, from the viewpoint of lowering the Df of the PI-based film easily even if the imidization temperature is low, among the benzene rings having R ^z11 to R ^z14 in the formula (z1), R ^z11 to At least one of R ^z14 may be a monovalent hydrocarbon group which may have a halogen atom, but all of R ^z11 to R ^z14 are preferably hydrogen atoms.

In the formula (z1), n represents an integer of 1 to 4, and preferably represents an integer of 1 to 3, and more preferably represents 1 or 2, from the viewpoint that the Df of the PI-based film is easily lowered even if the imidization temperature is low. , particularly preferably represents 2.

In one embodiment of the present invention, R ^z2 in the formula (z2) independently represent a monovalent hydrocarbon group which may have a halogen atom, and examples of the monovalent hydrocarbon group include the monovalent hydrocarbon groups exemplified above. From the viewpoint of lowering the Df of the PI-based film easily even if the imidization temperature is low, R ^z2 independently of each other preferably represent an alkyl group that may have a halogen atom, and more preferably represent an alkyl group that may have a halogen atom and have 1 to 2 carbon atoms. The alkyl group of 6 more preferably represents an alkyl group having 1 to 3 carbon atoms which may have a halogen atom.

j in formula (z2) represents 0-3 mutually independently. In one embodiment of the present invention, j is independently preferably 0 or 1, more preferably 0, and even more preferably j all are 0.

In a preferred embodiment of the present invention, formula (a1) is preferably represented by formula (a1') or formula (a1").

If the PI-based resin precursor contains as a structural unit (A1) a structural unit derived from tetracarboxylic anhydride represented by formula (a1), especially formula (a1') or formula (a1"), even if the imidization temperature is low , it is also easy to lower the Df of the obtained PI-based film, and it is easy to improve the bending resistance.

In one embodiment of the present invention, the content of the structural unit (A1) is preferably 10 mol% or more, more preferably 15 mol% or more, and still more preferably 20 mol% or more, based on the total amount of the structural unit (A). , still more preferably 30 mol% or more, particularly preferably 35 mol% or more, particularly more preferably 40 mol% or more. In addition, the content of the structural unit (A1) is preferably 75 mol% or less, more preferably 70 mol% or less, still more preferably 65 mol% or less, particularly preferably 60 mol% with respect to the total amount of the structural unit (A). %the following. When the content of the structural unit (A1) is within the above range, the obtained PI-based resin is likely to be oriented, the Df of the obtained PI-based film is likely to decrease, and the bending resistance is easily improved. The ratio of the aforementioned structural units can be measured using, for example, ¹ H-NMR, or can be calculated from the input ratio of raw materials.

(Structural unit (A2) derived from tetracarboxylic anhydride containing biphenyl skeleton)

The structural unit (A) contains the structural unit (A2) derived from the tetracarboxylic anhydride containing a biphenyl skeleton. When the structural unit (A) contains the structural unit (A2), even if the imidization temperature is low, it is easy to lower the Df of the obtained PI-based film, and it is easy to improve the bending resistance.

In one embodiment of the present invention, the structural unit (A2) is not particularly limited as long as it contains a biphenyl skeleton, and the number of biphenyl skeletons contained in the structural unit (A2) may be one or two or more. In addition, in one embodiment of the present invention, the structural unit (A2) is preferably a structural unit that contains a biphenyl skeleton but does not contain an ester bond. The structural unit of is not a structural unit (A2), but is classified as a structural unit (A1) derived from tetracarboxylic anhydride containing an ester bond.

In one embodiment of the present invention, the structural unit (A2) is preferably a structural unit (a2) derived from tetracarboxylic anhydride represented by formula (a2).

[In the formula (a2), R ^a2 independently represent a halogen atom, or an alkyl, alkoxy, aryl or aryloxy group that may have a halogen atom,

t each independently represents an integer of 0 to 3]

R ^a2 in the formula (a2) independently represents a halogen atom, or an alkyl, alkoxy, aryl, or aryloxy group that may have a halogen atom, and is obtained because the imidization temperature is easily lowered even at a low temperature. From the viewpoint of Df of the PI-based film and easy improvement of bending resistance, it is preferable to independently represent an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aromatic group having 6 to 12 carbon atoms. base. Examples of the alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms, and the aryl group having 6 to 12 carbon atoms include those exemplified above. The hydrogen atoms contained in R ^a2 may be independently substituted by halogen atoms, and examples of the halogen atoms include those exemplified above. Among them, R ^a2 is preferably an alkyl group having 1 to 6 carbon atoms independently of each other from the viewpoint that Df of the obtained PI-based film can be easily lowered and the bending resistance can be easily improved even if the imidization temperature is low. , more preferably an alkyl group having 1 to 3 carbon atoms.

Moreover, t in Formula (a2) mutually independently represents the integer of 0-3, Preferably it represents 0 or 1, More preferably, it represents 0.

The bonding position of the two carboxylic anhydrides bonded to the benzene ring constituting the biphenyl skeleton in the formula (a2) is not particularly limited, and based on the single bond connecting the two benzene rings, it may be 3 independently of each other. ,4-, or 2,3-, is preferably 3,4- from the viewpoint that Df of the obtained PI-based film is easily lowered and the bending resistance is easily improved even if the imidization temperature is low.

In a preferred embodiment of the present invention, formula (a2) is preferably represented by formula (a2').

If the PI-based resin precursor contains as a structural unit (A2) a structural unit derived from tetracarboxylic anhydride represented by formula (a2), especially formula (a2'), even if the imidization temperature is low, it is easy to reduce the obtained The Df of the PI-based film is easy to improve the bending resistance.

In one embodiment of the present invention, the content of the structural unit (A2) is preferably 25 mol% or more, more preferably 30 mol% or more, and still more preferably 35 mol% or more, based on the total amount of the structural unit (A). , particularly preferably 40 mol% or more. In addition, the content of the structural unit (A2) is preferably 90 mol % or less, more preferably 85 mol % or less, still more preferably 80 mol % or less, and even more preferably 70 mol % or less with respect to the total amount of the structural unit (A). mol% or less, particularly preferably 60 mol% or less. When the content of the structural unit (A2) is within the above range, the orientation of the PI-based resin is likely to occur, so that Df of the PI-based film tends to decrease. The ratio of the aforementioned structural units can be measured using, for example, ¹ H-NMR, or can be calculated from the input ratio of raw materials.

(structural unit (A3))

In one embodiment of the present invention, the structural unit (A) may contain a structural unit (A3) derived from tetracarboxylic anhydride other than the structural unit (A1) and the structural unit (A2).

In one embodiment of the present invention, the structural unit (A3) includes a structural unit derived from a tetracarboxylic anhydride that does not contain any of an ester bond and a biphenyl skeleton, for example, a tetracarboxylic anhydride represented by formula (1). structural unit.

[In formula (1), Y represents the 4-valent organic group shown in formula (31) ~ formula (38),

[In formulas (31) to (38), R ¹⁹ to R ²⁶ and R ^23' to R ^26' independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkane group having 1 to 6 carbon atoms Oxygen or an aryl group with 6 to 12 carbon atoms, the hydrogen atoms contained in R ¹⁹ to R ²⁶ and R ^23' to R ^26' may be independently substituted by halogen atoms,

V ¹ and V ² independently represent a single bond (where e+d=1 is excluded), -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, - C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -, -S-, -CO-, -N(R ^j )-, formula (a),

(In formula (a), R ²⁷ to R ³⁰ independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms,

D independently of each other represents a single bond, -C(CH ₃ ) ₂ - or -C(CF ₃ ) ₂ -,

i represents an integer from 1 to 3,

＊Indicates the connection key)

^Rj represents a hydrogen atom, or a monovalent hydrocarbon group with 1 to 12 carbon atoms which may be substituted by a halogen atom,

e and d independently represent an integer of 0 to 2 (wherein, e+d is not 0),

f represents an integer from 0 to 3,

g and h independently represent an integer of 0 to 4,

＊Indicates the connection key]]

In formula (31) to formula (33), R ¹⁹ to R ²⁶ and R ^23' to R ^26' independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms group or an aryl group with 6 to 12 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms, and the aryl group having 6 to 12 carbon atoms include those exemplified above. The hydrogen atoms included in R ¹⁹ to R ²⁶ and R ^23' to R ^26' may be independently substituted by halogen atoms, and examples of the halogen atoms include those exemplified above. Among them, R ¹⁹ to R ²⁶ and R ^23' to R ^26' are independently preferably hydrogen atoms or 1 to 6 carbon atoms from the viewpoint of improving the mechanical and thermal properties of the obtained PI-based film. The alkyl group is more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and is even more preferably a hydrogen atom. The term "mechanical properties" refers to mechanical properties including bending resistance and elastic modulus, and improvement in mechanical properties means, for example, that bending resistance and/or elastic modulus become higher. In addition, thermal physical properties refer to thermal physical properties including glass transition temperature (hereinafter sometimes described as Tg), CTE, cases with little denaturation and deterioration due to heat, and cases with little deformation after heating. The so-called improved thermal physical properties , for example, indicates that the Tg becomes higher and/or the CTE becomes lower.

In formula (31), V ¹ and V ² independently represent a single bond (where e+d=1 is excluded), -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH ( CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -, -S-, -CO-, -N(R ^j )- or formula (a), from From the viewpoint of easily improving the mechanical and thermal properties of the PI-based film, it is preferable to represent a single bond (where e+d=1 is excluded), -O-, -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ - or -CO-, more preferably represents a single bond (wherein, the case of e+d=1 is excluded), -O-, -C(CH ₃ ) ₂ - or -C(CF ₃ ) ₂ -. R ^j represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms which may be substituted by a halogen atom. Examples of monovalent hydrocarbon groups having 1 to 12 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, 2-methylbutyl, 3-methylbutyl, 2-ethylpropyl, n-hexyl, n-heptyl, n-octyl, tert-octyl, n-nonyl and n-decyl, etc., which can be replaced by halogen atoms replace. Examples of the halogen atom include the same ones as those described above.

In the formula (31), e and d independently represent an integer of 0 to 2 (wherein, e+d is not 0), and from the viewpoint that the Df of the PI-based film is easily lowered even if the imidization temperature is low, Preferably represents 0 or 1. In addition, e+d preferably represents 1. It should be noted that in formula (31), when e is 0, it means that the two benzene rings are not bonded by ^V1 , and when d is 0, it means that the two benzene rings are not bonded by ^V2 .

In formula (32) and formula (33), f represents an integer of 0 to 3, and from the viewpoint that the Df of the PI-based film is easily lowered even if the imidization temperature is low, it preferably represents 0 or 1, and more preferably represents 0.

In formula (33), g and h independently represent an integer of 0 to 4, and preferably represent an integer of 0 to 2, and more preferably represent 0 or 1, from the viewpoint of easily improving the mechanical and thermal properties of the PI-based film. In addition, g+h preferably represents an integer of 0-2. In addition, when f is 1 or more, a plurality of g and h may be the same or different independently of each other.

In formula (a), R ²⁷ to R ³⁰ independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms include the alkyl groups having 1 to 6 carbon atoms exemplified above. Among them, R ²⁷ to R ³⁰ independently of each other preferably represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and more preferably represent a hydrogen atom, from the viewpoint of easily improving the mechanical and thermal properties of the PI-based film.

In formula (a), D represents a single bond, -C(CH ₃ ) ₂ - or -C(CF ₃ ) ₂ -. When D has such a structure, it is easy to improve the mechanical properties and thermal properties of the PI-based film. i represents an integer of 1 to 3, and is preferably 1 or 2 from the viewpoint of making it easier to improve the mechanical properties and thermal properties of the PI-based film. When i is 2 or more, a plurality of D and R ²⁷ to R ³⁰ may independently be the same or different.

Among them, it is preferable that Y in the formula (1) is represented by the formula (42) to The structural unit of the tetracarboxylic anhydride represented by formula (49) or formula (53), more preferably Y from formula (1) by formula (42), formula (43), formula (46), formula (49) or The structural unit of the tetracarboxylic anhydride represented by formula (53) is more preferably derived from tetracarboxylic anhydride represented by formula (42), formula (46), formula (49) or formula (53) in Y in formula (1) Structural units. In addition, in these formulae, * represents a linking bond.

<Structural unit (B) derived from diamine>

The PI-based resin precursor of the present invention contains a diamine-derived structural unit (B).

(Structural unit (B1) derived from biphenyl skeleton-containing diamine)

The structural unit (B) contains a structural unit (B1) derived from a biphenyl skeleton-containing diamine. For the PI-based resin precursor whose structural unit (B) contains the structural unit (B1), even if the imidization temperature is low, the Df of the obtained PI-based film is also likely to decrease. Therefore, the PI-based film containing this The circuit is easy to reduce the transmission loss. Moreover, when a structural unit (B) contains a structural unit (B1), it becomes easy to improve the bending resistance of the obtained PI-type film.

In one embodiment of the present invention, the structural unit (B1) is not particularly limited as long as it contains a biphenyl skeleton, and the number of biphenyl skeletons contained in the structural unit (B1) may be one or two or more. In one embodiment of the present invention, the structural unit (B1) is preferably derived from the formula (b1) from the viewpoint of easily lowering the Df of the obtained PI-based film and improving the bending resistance even if the imidization temperature is low. Structural unit (b1) of diamine represented.

[In the formula (b1), R ^b1 independently represent a halogen atom, or an alkyl, alkoxy, aryl or aryloxy group that may have a halogen atom,

p represents an integer from 0 to 4]

In formula (b1), R ^b1 independently represents a halogen atom, or an alkyl, alkoxy, aryl, or aryloxy group that may have a halogen atom, preferably represents a halogen atom, or an alkyl group that may have a halogen atom, The alkoxy group or aryl group more preferably represents a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms, and the aryl group having 6 to 12 carbon atoms include those exemplified above. The hydrogen atoms contained in R ^b1 may be independently substituted by halogen atoms, and examples of the halogen atoms include the halogen atoms exemplified above. R ^b1 is preferably an alkyl group having 1 to 6 carbon atoms or fluorine having 1 to 6 carbon atoms independently of each other from the viewpoint of making it easy to lower the Df of the obtained PI-based film and to improve the bending resistance and dimensional stability. The substituted alkyl group is more preferably an alkyl group having 1 to 6 carbon atoms that does not contain fluorine, and is still more preferably an alkyl group having 1 to 6 carbon atoms that does not contain fluorine, from the viewpoint of easily improving the adhesiveness with substrates such as copper foil. 3, particularly preferably methyl.

In the formula (b1), p independently represents an integer of 0 to 4, and is preferably an integer of 0 to 2, more preferably 0 or 1.

In the formula (b1), the _-NH group bonded to each benzene ring can be respectively bonded to the ortho-position, meta-position or para-position, or the α-position, β-position or Any position in the γ position can be preferably bonded to the meta-position or para-position, or the β The position or the γ position may be more preferably bonded to the para position or the γ position.

In a preferred embodiment of the present invention, formula (b1) is preferably represented by formula (b1').

If the PI-based resin precursor contains as a structural unit (B1) a structural unit derived from a diamine represented by formula (b1), especially formula (b1'), even if the imidization temperature is low, the obtained PI-based film The Df is also easy to lower, and it is easy to improve the bending resistance.

(structural unit (B2))

In one embodiment of the present invention, the structural unit (B) preferably contains a structural unit (B2) derived from a diamine having two or more aromatic rings and each aromatic ring is bonded via a divalent organic group (hereinafter, Sometimes abbreviated as structural unit (B2)). Examples of the divalent organic group in the structural unit (B2) include an alkylene group which may have a halogen atom, -O-, -COO-, -OOC-, -SO ₂ -, -S-, - CO- or -N(R ^c )-, etc., R ^c represents a hydrogen atom, a monovalent hydrocarbon group having 1 to 12 carbon atoms which may be substituted by a halogen atom. Among them, as the divalent organic group in the structural unit (B2), -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -COO-, -OOC-, -SO ₂ -, -S-, -CO- or -N(R ^c )-.

Examples of the structural unit (B2) include a structural unit (b2) derived from a diamine represented by the formula (b2) (hereinafter, sometimes abbreviated as a structural unit (b2)), a structural unit derived from a diamine represented by the formula (2) wait.

[In the formula (b2), R ^b2 independently represent a halogen atom, or an alkyl, alkoxy, aryl or aryloxy group that may have a halogen atom,

W independently represent -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -COO -, -OOC-, -SO ₂ -, -S-, -CO- or -N(R ^c )-, R ^c represents a hydrogen atom, a monovalent hydrocarbon group with 1 to 12 carbon atoms which may be substituted by a halogen atom, m represents an integer of 1 to 4,

q independently represent an integer of 0 to 4]

H ₂ NX-NH ₂ (2)

[In the formula (2), X represents the divalent organic group shown in the formula (65) (in the formula (65), * represents the linking bond),

Among them, the structural unit (B2) is preferably a structural unit (b2) from the viewpoint that Df of the obtained PI-based film tends to decrease even if the imidization temperature is low, and the bending resistance is easily improved. If the structural unit (B) contains the structural unit (B2), especially the structural unit (b2), even if the imidization temperature is low, the Df of the obtained PI-based film is likely to decrease. As a result, even if the imidization When the temperature is low, the transmission loss of the electronic circuit including the obtained PI-based film tends to be reduced, and the bending resistance of the obtained PI-based film tends to be improved.

In formula (b2), R ^b2 independently represent a halogen atom, or an alkyl, alkoxy, aryl, or aryloxy group that may have a halogen atom, preferably a halogen atom, an alkyl group having 1 to 6 carbon atoms , an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms, and the aryl group having 6 to 12 carbon atoms include those exemplified above. The hydrogen atoms contained in R ^b2 may be independently substituted by halogen atoms, and examples of the halogen atoms include the halogen atoms exemplified above. R ^b2 is preferably an alkyl group having 1 to 6 carbon atoms independently of each other from the viewpoint that Df of the obtained PI-based film can be easily lowered even if the imidization temperature is low, and that bending resistance and dimensional stability can be easily improved. Or a fluoroalkyl group having 1 to 6 carbon atoms, more preferably a fluorine-free alkyl group having 1 to 6 carbon atoms, and even more preferably The alkyl group having 1 to 3 carbon atoms not containing fluorine is particularly preferably a methyl group.

In the formula (b2), q independently represent an integer of 0 to 4, and it is considered from the viewpoint that the Df of the obtained PI-based film is easily lowered and the bending resistance and dimensional stability are easily improved even if the imidization temperature is low. , is preferably an integer of 0-2, more preferably 0 or 1.

In formula (b2), W independently represents -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -COO-, -OOC-, -SO ₂ -, -S-, -CO-, or -N(R ^c )-, the resulting PI system is easy to reduce even if the imidization temperature is low. From the standpoint of Df of the film and easy improvement of bending resistance and dimensional stability, it is preferable to represent -O-, -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -COO-, -OOC- or -CO- is more preferably -O-, -CH ₂ - or -C(CH ₃ ) ₂ -, more preferably -O- or -C(CH ₃ ) ₂ -. R ^c represents a hydrogen atom and a monovalent hydrocarbon group having 1 to 12 carbon atoms which may be substituted by a halogen atom. Examples of the monovalent hydrocarbon group having 1 to 12 carbon atoms include the monovalent hydrocarbon groups having 1 to 12 carbon atoms exemplified above, and these may be substituted with a halogen atom. Examples of the halogen atom include the same ones as those described above.

In the formula (b2), m is an integer of 1 to 4, and is preferably It is an integer of 1-3, More preferably, it is 2 or 3. In the formula (b2), a plurality of W, R ^b2 , and q may be the same or different from each other, and the positions of -W- based on -NH ₂ of each benzene ring may be the same or different.

In the formula (b2), -W- can be bonded to any position in the ortho, meta or para positions, or the α, β or γ positions based on the _-NH of each benzene ring. From the viewpoint that the Df of the obtained PI-based film can be easily lowered even if the imidization temperature is low, and the bending resistance and dimensional stability can be easily improved, it can be preferably bonded to the meta-position or para-position, or the β-position or γ-position, Bonding to the para-position or the γ-position may be more preferable.

In one embodiment of the present invention, even if the imidization temperature is low, it is easy to lower the Df of the obtained PI-based film, it is easy to improve the bending resistance, and it is easy to improve the obtained PI-based film and copper foil. From the viewpoint of the adhesiveness of the metal foil, it is preferable that m in the formula (b2) is 3, and W independently represent -O- or -C(CH ₃ ) ₂ -, and it is more preferable that the formula (b2) is represented by the formula (b2' )express.

If the PI-based resin precursor contains a structural unit (b2), especially a structural unit derived from a diamine represented by the formula (b2'), even if the imidization temperature is low, it is easy to obtain a low Df, and it is compatible with copper foil, etc. PI-based film with excellent adhesion to metal foil.

In one embodiment of the present invention, the structural unit (b2) may include, in addition to, or instead of, the structural unit derived from the diamine represented by the formula (b2′) derived from the formula (b2) where m is 1 and W represents -O- is the structural unit of diamine.

In one embodiment of the present invention, the content of the structural unit (B2) is preferably 0 mol% or more, more preferably 0.3 mol% or more, and still more preferably 0.5 mol% or more, based on the total amount of the structural unit (B). , still more preferably 0.8 mol% or more, particularly preferably 1 mol% or more, particularly more preferably 5 mol% or more, even more preferably 8 mol% or more. The adhesiveness of the obtained PI-type film and base materials, such as copper foil, as content of a structural unit (B2) is more than the said minimum is easy to improve. In addition, the upper limit of the content of the structural unit (B2) is preferably 75 mol% or less, more preferably 60 mol% or less, still more preferably 40 mol% or less, and even more preferably It is 30 mol% or less, especially preferably 20 mol% or less. When content of a structural unit (B2) is below the said upper limit, there exists a tendency for mechanical physical properties, such as CTE of the PI type film obtained, to improve easily. The ratio of the aforementioned structural units can be measured using, for example, ¹ H-NMR, or can be calculated from the input ratio of raw materials.

(structural unit (B3))

The PI-based resin precursor may contain, as a structural unit (B), a diamine-derived structural unit (B3) (hereinafter, may be abbreviated as structural unit (B3)) other than the structural unit (B1) and structural unit (B2). As the structural unit (B3), for example, a structural unit derived from a diamine in which m is 0 in formula (b2), a diamine derived from formula (61) to formula (64) in which X in formula (2) is represented, Amine structural units, etc.

[In formula (61), R ^a , R ^b , W, t, u and n are independently the same as R ^a , R ^b , W, t, u and n in formula (60),

In formula (62), ring A represents a cycloalkane ring having 3 to 8 carbon atoms,

R ^d represents an alkyl group having 1 to 20 carbon atoms,

r represents an integer not less than 0 and not more than (number of carbon atoms in the ring A-2),

S1 and S2 independently represent an integer of 0 to 20,

In Formula (61) to Formula (64), * represents a connecting bond. ]

In this specification, "a structural unit (B3) derived from a diamine other than a structural unit (B1) and a structural unit (B2)" refers to any of the structural unit (B1) and structural unit (B2). Different structural units derived from diamines.

In formula (62), ring A represents a cycloalkane ring having 3 to 8 carbon atoms. Examples of cycloalkane rings include cyclopropane rings, cyclobutane rings, cyclopentane rings, cyclohexane rings, cycloheptane rings, and cyclooctane rings, preferably rings having 4 to 6 carbon atoms. alkane ring. In ring A, the linkages may or may not be adjacent to each other. For example, when ring A is a cyclohexane ring, the two linkages may be in the positional relationship of α-position, β-position or γ-position, and may preferably be in the positional relationship of β-position or γ-position.

R ^d in the formula (62) represents an alkyl group having 1 to 20 carbon atoms, preferably an alkyl group having 1 to 10 carbon atoms, and examples thereof include the groups exemplified above. r in the formula (62) represents an integer not less than 0 and not more than "number of carbon atoms of the ring A-2". r is preferably 0 or more, preferably 4 or less. S1 and S2 in Formula (62) mutually independently represent the integer of 0-20. S1 and S2 are independently preferably 0 or more, more preferably 2 or more, and preferably 15 or less.

As a specific example of the structural unit (B3), X in formula (2) can be enumerated by formula (71), formula (74), formula (77), formula (78), formula (89) and formula (90) ) is a structural unit of a diamine represented by the formula (74), among them, a structural unit derived from a diamine represented by X in formula (2) (a structural unit derived from p-phenylenediamine) is preferable. In addition, in these formulae, * represents a linking bond.

In one embodiment of the present invention, when the structural unit (B) contains the structural unit (B3), the content of the structural unit (B3) is preferably 25 mol % or less with respect to the total amount of the structural unit (B), More preferably, it is 20 mol% or less, Still more preferably, it is 10 mol% or less, Preferably it is 0.01 mol% or more.

In one embodiment of the present invention, the PI-based resin precursor may contain, for example, a halogen atom, preferably a fluorine atom, which can be introduced by the above-mentioned halogen atom-containing substituent or the like. When the PI-based resin precursor contains fluorine atoms, the relative permittivity of the obtained PI-based film tends to decrease. As a fluorine-containing substituent preferably used for making the PI-based resin precursor contain a fluorine atom, a fluorine group and a trifluoromethyl group are mentioned, for example.

Moreover, in another embodiment of this invention, it is preferable that a PI-type resin precursor does not contain a fluorine atom from a viewpoint of making it easy to improve the adhesiveness of the obtained PI-type film and base materials, such as copper foil. In addition, if the PI-based resin precursor contains fluorine, there is a tendency to weaken the interaction between the molecular chains. Therefore, if the PI-based resin precursor does not contain fluorine atoms, there is a tendency to easily suppress the formation of the PI-based resin precursor. The rotation of the higher-order structure of the obtained PI-based resin tends to lower the Df of the obtained PI-based film and improve the bending resistance.

When the PI-based resin precursor contains a halogen atom, based on the mass of the PI-based resin precursor, the content of the halogen atom, especially the fluorine atom, in the PI-based resin precursor is preferably 0.1 to 35% by mass, more preferably It is 0.1-30 mass %, More preferably, it is 0.1-20 mass %, Especially preferably, it is 0.1-10 mass %. When content of a halogen atom is more than the said minimum, it becomes easy to improve the heat resistance and dielectric characteristic of the PI system film obtained. When content of a halogen atom is below the said upper limit, it is advantageous in terms of cost, it becomes easy to lower the CTE of a PI-type film, and it becomes easy to synthesize|combine a PI-type resin. The so-called dielectric properties refer to dielectric-related properties including relative permittivity and dielectric loss tangent, and the so-called increase or improvement of dielectric properties means that relative permittivity and/or dielectric loss tangent decrease.

[Manufacturing method of polyimide-based resin precursor]

The PI-based resin precursor of the present invention can be obtained by reacting tetracarboxylic anhydride and diamine. In addition, it is also possible to react a dicarboxylic acid compound and a tricarboxylic acid compound other than a tetracarboxylic acid compound.

Examples of tetracarboxylic anhydrides used in the synthesis of PI-based resin precursors include: aromatic tetracarboxylic acid compounds such as aromatic tetracarboxylic dianhydrides; and aliphatic tetracarboxylic acid compounds such as aliphatic tetracarboxylic dianhydrides; etc. A tetracarboxylic acid compound may be used individually or in combination of 2 or more types. The tetracarboxylic acid compound may be analogues of tetracarboxylic acid compounds such as acid chloride compounds other than dianhydrides.

As a tetracarboxylic-acid compound, the tetracarboxylic anhydride represented by said formula (1) is mentioned, for example, Preferably, the tetracarboxylic anhydride represented by a formula (a1) and the tetracarboxylic anhydride represented by a formula (a2) are mentioned.

Specific examples of tetracarboxylic acid compounds include pyromellitic dianhydride (hereinafter sometimes referred to as PMDA), 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic acid Dicarboxylic anhydride (hereinafter sometimes referred to as BPADA), 1,4,5,8-naphthalene tetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride (hereinafter sometimes referred to as BPDA) , 4,4'-(hexafluoroisopropylidene) diphthalic dianhydride (hereinafter, sometimes referred to as 6FDA), 4,4'-oxydiphthalic dianhydride (hereinafter, sometimes referred to as ODPA ), 2,2',3,3'-, 2,3,3',4'- or 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 2,3',3, 4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, p-phenylene bis(trimellitic acid monoester dianhydride) (hereinafter sometimes referred to as TAHQ ), esterification of trimellitic anhydride and 2,2',3,3',5,5'-hexamethyl-4,4'-biphenol (hereinafter sometimes referred to as TMPBP), 4,4'-bis(1 ,3-dioxo-1,3-dihydroisobenzofuran-5-ylcarbonyloxy)biphenyl (hereinafter sometimes referred to as BP-TME), 2,3',3,4'-biphenyl base ether tetracarboxylic dianhydride, bis(2,3-dicarboxyphenyl) ether dianhydride, 3,3”, 4,4”-p-terphenyltetracarboxylic dianhydride, 2,3,3”, 4”- p-Terphenyltetracarboxylic dianhydride, 2,2”,3,3”-p-Terphenyltetracarboxylic dianhydride, 2,2-bis(2,3-dicarboxyphenyl)-propane dianhydride, 2,2- Bis(3,4-dicarboxyphenyl)-propane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, 1,1- Bis(2,3-dicarboxyphenyl)ethanedianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethanedianhydride, 1,2,7,8-, 1,2,6 ,7-phenanthrene tetracarboxylic dianhydride, 1,2,9,10-phenanthrene tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)tetrafluoropropane dianhydride, 1,2,4, 5-cyclohexanetetracarboxylic dianhydride (hereinafter sometimes referred to as HPMDA), 2,3,5,6-cyclohexanetetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 1, 2,5,6-naphthalene tetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, 4,4'-bis(2,3-dicarboxyphenoxy)diphenylmethane Dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride (hereinafter sometimes referred to as CBDA), norbornane-2-spiro-α'-spiro-2"-norbornane-5,5 ',6,6'-tetracarboxylic anhydride, p-phenylene bis(trimellitic anhydride), 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, 2,3,6, 7-Anthracene tetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic dianhydride, 2,6-di Chloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-tetrachloronaphthalene-1 ,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-tetrachloronaphthalene-2,3,6,7-tetracarboxylic dianhydride, 1,4,5,8-tetrachloronaphthalene-1 ,4,5,8-tetracarboxylic dianhydride, 1,4,5,8-tetrachloronaphthalene-2,3,6,7-tetracarboxylic dianhydride, 2,3,8,9-perylenetetracarboxylic dianhydride , 3,4,9,10-perylenetetracarboxylic dianhydride, 4,5,10,11-perylenetetracarboxylic dianhydride, 5,6,11,12-perylenetetracarboxylic dianhydride, pyrazine-2,3, 5,6-tetracarboxylic dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride, thiophene-2,3,4,5-tetracarboxylic dianhydride, bis(2,3-dicarboxyphenyl ) sulfone dianhydride, bis(3,4-dicarboxyphenyl) sulfone dianhydride, etc. Among them, BPDA, TAHQ, and BP-TME are preferable from the viewpoint of lowering Df of the obtained PI-based film and improving bending resistance easily even if the imidization temperature is low. These tetracarboxylic acid compounds can be used individually or in combination of 2 or more types.

Examples of the diamine compound used for the synthesis of the PI-based resin precursor include aliphatic diamine, aromatic diamine, and mixtures thereof. In addition, in this embodiment, "aromatic diamine" means the diamine which has an aromatic ring, and may contain an aliphatic group or other substituents in part of the structure. The aromatic ring may be a single ring or a condensed ring, and examples thereof include, but are not limited to, a benzene ring, a naphthalene ring, an anthracene ring, and a fluorene ring. Among them, a benzene ring is preferable. In addition, "aliphatic diamine" means a diamine having an aliphatic group, which may contain other substituents in a part of its structure, but does not have an aromatic ring.

As a diamine compound, the diamine compound represented by said formula (2) is mentioned, for example, Preferably, the diamine compound represented by a formula (b1) and the diamine compound represented by a formula (b2) are mentioned.

Specific examples of diamine compounds include 1,4-diaminocyclohexane, 4,4'-diamino-2,2'-dimethylbiphenyl (hereinafter sometimes referred to as m-Tb), 4,4'-diamino-3,3'-dimethylbiphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (hereinafter sometimes referred to as TFMB), 4,4'-Diaminodiphenyl ether, 1,3-bis(3-aminophenoxy)benzene (hereinafter sometimes referred to as 1,3-APB), 1,4-bis(4-aminophenoxy base) benzene (hereinafter sometimes referred to as TPE-Q), 1,3-bis(4-aminophenoxy)benzene, 2,2-bis[4-(4-aminophenoxy)phenyl]propane ( Sometimes described as BAPP), 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxy-4,4'-diaminobiphenyl, 2,2-bis-[ 4-(3-aminophenoxy)phenyl]propane, bis[4-(4-aminophenoxy)]biphenyl, bis[4-(3-aminophenoxy)biphenyl, bis[1- (4-aminophenoxy)]biphenyl, bis[1-(3-aminophenoxy)]biphenyl, bis[4-(4-aminophenoxy)phenyl]methane, bis[4-( 3-aminophenoxy)phenyl]methane, bis[4-(4-aminophenoxy)phenyl]ether, bis[4-(3-aminophenoxy)phenyl]ether, bis[4- (4-aminophenoxy)]benzophenone, bis[4-(3-aminophenoxy)]benzophenone, 2,2-bis-[4-(4-aminophenoxy)benzene base]hexafluoropropane, 2,2-bis-[4-(3-aminophenoxy)phenyl]hexafluoropropane, 4,4'-methylenedi-o-toluidine, 4,4'-methylene Methyldi-2,6-xylidine, 4,4'-methylene-2,6-diethylaniline, 4,4'-methylenedianiline, 3,3'-methylenedi Aniline, 4,4'-diaminodiphenylpropane, 3,3'-diaminodiphenylpropane, 4,4'-diaminodiphenylethane, 3,3'-diaminodiphenylethane alkane, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3,3-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, bis Aniline, 3,3'-diaminobiphenyl, 3,3'-dimethoxybenzidine, 4,4"-diamino-p-terphenyl, 3,3"-diamino-p-terphenyl, m-phenylenediamine , p-phenylenediamine (sometimes recorded as p-PDA), resorcinol-bis(3-aminophenyl) ether, 4,4'-[1,4-phenylene bis(1-methylethylidene) base)] bisaniline, 4,4'-[1,3-phenylenebis(1-methylethylidene)]bisaniline, bis(p-aminocyclohexyl)methane, bis(p-β-amino- tert-butylphenyl) ether, bis(p-β-methyl-δ-aminopentyl)benzene, p-bis(2-methyl-4-aminopentyl)benzene, p-bis(1,1- Dimethyl-5-aminopentyl)benzene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,4-bis(β-amino-tert-butyl)toluene, 2,4-diamino Toluene, m-xylene-2,5-diamine, p-xylene-2,5-diamine, m-xylylenediamine, p-xylylenediamine, piperazine, 4,4'-diamino-2,2 '-bis(trifluoromethyl)bicyclohexane, 4,4'-diaminodicyclohexylmethane, 4,4"-diamino-p-terphenyl, bis(4-aminophenyl) terephthalate, 1,4-bis(4-aminophenoxy)-2,5-di-tert-butylbenzene, 4,4'-(1,3-phenylenediisopropylidene)bisaniline, 1,4- Bis[2-(4-aminophenyl)-2-propyl]benzene, 2,4-diamino-3,5-diethyltoluene, 2,6-diamino-3,5-diethyltoluene , 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-(hexafluoropropylene)diphenylamine, 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,2-diaminopropane, 1,2-diaminobutane, 1,3-diamino Butane, 2-methyl-1,2-diaminopropane, 2-methyl-1,3-diaminopropane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(amino Methyl)cyclohexane, norbornanediamine, 2'-methoxy-4,4'-diaminobenzanilide, 4,4'-diaminobenzanilide, bis[4-(4 -aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, 9,9-bis[4-(4-aminophenoxy)phenyl]fluorene, 9 ,9-bis[4-(3-aminophenoxy)phenyl]fluorene, 4,4'-diaminodiphenylsulfide, 3,3'-diaminodiphenylsulfide, 4,4' -Diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 2,5-diamino-1,3,4-oxadiazole, bis[4,4'-(4-aminophenoxy Base)] benzoanilide, bis[4,4'-(3-aminophenoxy)] benzoanilide, 2,6-diaminopyridine, 2,5-diaminopyridine, etc. Among them, m-Tb, BAPP, TPE-Q, 1,3- Bis(4-aminophenoxy)benzene and the like, more preferably m-Tb, BAPP and the like. A diamine compound can be used individually or in combination of 2 or more types.

It should be noted that the PI-based resin precursor of the present invention may be a tetracarboxylic acid compound used in the synthesis of the above-mentioned PI-based resin precursor as long as the various physical properties of the obtained PI-based film are not impaired. Products obtained by further reacting other tetracarboxylic acids, dicarboxylic acids, tricarboxylic acids, and their anhydrides and derivatives.

As another tetracarboxylic acid, the water adduct of the anhydride of the said tetracarboxylic-acid compound is mentioned.

Examples of the dicarboxylic acid compound include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and their similar acid chloride compounds, acid anhydrides, and the like, and two or more of them may be used in combination. Specific examples include terephthalic acid; isophthalic acid; naphthalene dicarboxylic acid; 4,4'-biphenyl dicarboxylic acid; 3,3'-biphenyl dicarboxylic acid; Dicarboxylic acid compounds of hydrocarbons and 2 benzoic acids through a single bond, -O-, -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ - or phenylene Linked compounds, and their acid chloride compounds.

Examples of the tricarboxylic acid compound include aromatic tricarboxylic acids, aliphatic tricarboxylic acids, and their similar acid chloride compounds, acid anhydrides, and the like, and two or more of them may be used in combination. As specific examples, 1,2,4-benzenetricarboxylic anhydride; 2,3,6-naphthalenetricarboxylic acid-2,3-anhydride; phthalic anhydride and benzoic acid through a single bond, -O- , -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ - or a phenylene link.

In the manufacture of the PI-based resin precursor, the amount of diamine compound, tetracarboxylic acid compound, dicarboxylic acid compound, and tricarboxylic acid compound can be appropriately adjusted according to the ratio of each structural unit of the desired PI-based resin precursor. choose.

In this invention, the total number of moles used of the diamine compound with respect to 1 mol of total amounts of a tetracarboxylic-acid compound is defined as an amine ratio. In one preferred embodiment of the present invention, the amine ratio is preferably 0.90 mol or more and preferably 0.999 mol or less with respect to 1 mol of the total amount of the tetracarboxylic acid compound. In addition, in another embodiment, the amine ratio is preferably 1.001 mol or more and preferably 1.10 mol or less with respect to 1 mol of the total amount of the tetracarboxylic acid compound.

In one embodiment of the present invention, when the amine ratio is 1 or less, the amine ratio is preferably 0.90 mol to 0.999 mol, more preferably 0.95 mol to 0.997 mol, even more preferably 0.97 mol to 0.995 mol.

In one embodiment of the present invention, when the amine ratio is 1 or more, the amine ratio is preferably 1.001 mol to 1.1 mol, more preferably 1.002 mol to 1.05 mol, and still more preferably 1.003 mol to 1.03 mol.

When the amine ratio is close to 1.0 mol, the molecular weight tends to increase rapidly during synthesis, and when the amine ratio is significantly different from 1.0 mol, the molecular weight of the obtained PI-based resin tends to decrease easily. If the molecular weight increases rapidly, it tends to grow unevenly in the synthetic material, and the physical properties of the PI-based resin obtained from the PI-based resin precursor tend to be difficult to stabilize. On the other hand, when the molecular weight is too low, mechanical properties tend to decrease.

The reaction temperature between the diamine compound and the tetracarboxylic acid compound is preferably 50°C or lower, more preferably 40°C or lower, even more preferably 30°C or lower. If the reaction temperature is below the above-mentioned upper limit, the Df of the obtained PI-based film is easily reduced, and the bending resistance is easily improved. It is particularly remarkable in a PI-based film of a PI-based resin obtained from a PI-based resin precursor containing a structural unit (A1). In addition, the reaction temperature between the diamine compound and the tetracarboxylic acid compound is preferably 5°C or higher, more preferably 10°C or higher, and still more preferably 15°C or higher. It exists in the tendency for reaction rate to be easy to raise and shorten polymerization time that reaction temperature is more than the said minimum.

The reaction time is not particularly limited, and is, for example, about 0.5 to 72 hours, preferably 3 to 24 hours. When the reaction time is within the above-mentioned range, even if the imidization temperature is low, the Df of the obtained PI-based film will be easily lowered.

The reaction of the diamine compound and the tetracarboxylic acid compound is preferably performed in a solvent. The solvent is not particularly limited as long as it does not affect the reaction. For example, water, methanol, ethanol, ethylene glycol, isopropanol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, 1 - Alcohol solvents such as methoxy-2-propanol, 2-butoxyethanol, propylene glycol monomethyl ether; phenolic solvents such as phenol and cresol; ethyl acetate, butyl acetate, ethylene glycol methyl ether Ester-based solvents such as acetate, propylene glycol methyl ether acetate, and ethyl lactate; Lactone-based solvents such as γ-butyrolactone (hereinafter, sometimes referred to as GBL) and γ-valerolactone; Acetone, methyl ethyl lactone, etc. Ketone solvents such as ketone, cyclopentanone, cyclohexanone, 2-heptanone, and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane, and heptane; alicyclic solvents such as ethylcyclohexane Hydrocarbon solvents; aromatic hydrocarbon solvents such as toluene and xylene; nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; chlorinated solvents such as chloroform and chlorobenzene; N,N-dimethylacetamide (hereinafter, sometimes described as DMAc), N,N-dimethylformamide (hereinafter, sometimes described as DMF) and other amide solvents; dimethyl sulfone, dimethyl sulfoxide, sulfolane and other sulfur-containing solvents; carbonic acid Carbonate-based solvents such as vinyl ester and propylene carbonate; pyrrolidone-based solvents such as N-methylpyrrolidone (hereinafter, sometimes referred to as NMP); and combinations thereof. Among them, from the viewpoint of solubility, preferably, phenol-based solvents, lactone-based solvents, amide-based solvents, and pyrrolidone-based solvents can be suitably used, more preferably amide-based solvents.

In one embodiment of the present invention, it is used in the reaction of a diamine compound and a tetracarboxylic acid compound from the viewpoint that the Df of the obtained PI-based film can be easily lowered and the bending resistance can be easily improved even if the imidization temperature is low. The boiling point of the solvent is preferably 230°C or lower, more preferably 200°C or lower, even more preferably 180°C or lower. In addition, the boiling point of the solvent is preferably 100°C or higher, more preferably 120°C or higher, from the viewpoint of easily lowering the Df of the obtained PI-based film even if the imidization temperature is low.

The reaction between the diamine compound and the tetracarboxylic acid compound can be carried out under an inert atmosphere such as a nitrogen atmosphere or an argon atmosphere or under reduced pressure as needed. The dehydration is carried out with stirring in a tightly controlled dehydration solvent.

The PI-based resin precursor can be separated and purified by common methods, such as filtration, concentration, extraction, crystallization, recrystallization, column chromatography and other separation methods, or by combining them. On the other hand, the reaction solution containing the PI-based resin precursor obtained by synthesizing the PI-based resin precursor is used to manufacture the PI-based resin.

〔Polyimide resin〕

The present invention also includes PI-based resins obtained from the PI-based resin precursors of the present invention. As will be described later, the PI-based resin of the present invention is a PI-based resin obtained by imidating the above-mentioned PI-based resin precursor.

Since the PI-based resin of the present invention is obtained from the PI-based resin precursor of the present invention, each structural unit contained in the PI-based resin precursor of the present invention, such as structural unit (A1), structural unit (A2), The same structural unit, such as a structural unit (B1), is contained in the same content. Therefore, regarding the type and content of the structural unit contained in the PI-based resin, the descriptions related to the type and content of each structural unit in the section of [polyimide-based resin precursor] are similarly applied.

In one embodiment of the present invention, the PI-based resin may contain, for example, a halogen atom, preferably a fluorine atom, which can be introduced by the above-mentioned halogen atom-containing substituent or the like. When the PI-based resin contains fluorine atoms, the relative permittivity of the obtained PI-based film tends to decrease. As a fluorine-containing substituent preferably used for making a fluorine atom into a PI resin, a fluorine group and a trifluoromethyl group are mentioned, for example.

Moreover, in another embodiment of this invention, it is preferable that a PI-type resin does not contain a fluorine atom from a viewpoint of making it easy to improve the adhesiveness of the obtained PI-type film and base materials, such as copper foil. In addition, if the PI-based resin contains fluorine, there is a tendency to weaken the interaction between molecular chains. Therefore, if the PI-based resin does not contain fluorine atoms, there is a tendency to form a high molecular weight structure that inhibits the molecular rotation of the PI-based resin. substructure, and as a result, the effects of the present invention are easily obtained.

When the PI-based resin contains a halogen atom, based on the mass of the PI-based resin, the content of the halogen atom, especially the fluorine atom, in the PI-based resin is preferably 0.1 to 35% by mass, more preferably 0.1 to 30% by mass , more preferably 0.1 to 20% by mass, particularly preferably 0.1 to 10% by mass. When content of a halogen atom is more than the said minimum, it becomes easy to improve the heat resistance and dielectric characteristic of the PI system film obtained. When content of a halogen atom is below the said upper limit, it is advantageous in terms of cost, it becomes easy to lower the CTE of a PI-type film, and it becomes easy to synthesize|combine a PI-type resin.

In one embodiment of the present invention, the imidization rate of the PI-based resin is preferably 90% or more, more preferably 93% or more, still more preferably 95% or more, and usually 100% or less. It is preferable that the imidation rate is more than the above-mentioned lower limit from a viewpoint of making it easy to improve a mechanical physical property, a thermal physical property, and a dielectric characteristic. The imidization rate shows the ratio of the molar quantity of the imide bond in a PI-type resin with respect to the value which is 2 times the molar quantity of the structural unit originating in the tetracarboxylic-acid compound in a PI-based resin. In addition, when the PI-based resin contains a tricarboxylic acid compound, the imidization rate represents the molar amount of the imide bond in the PI-based resin relative to the structural unit derived from the tetracarboxylic acid compound in the PI-based resin. The ratio of the value twice the molar amount of the tricarboxylic acid compound to the total molar amount of the structural unit derived from the tricarboxylic acid compound. In addition, the imidization rate can be calculated|required by IR method, NMR method, etc.

In one embodiment of the present invention, the polystyrene-equivalent Mw of the PI-based resin is preferably greater than 100,000, more preferably 110,000 or more, further preferably 120,000 or more, particularly preferably 130,000 or more, preferably 1,000,000 or less, more preferably 700,000 or less, more preferably 500,000 or less, particularly preferably 300,000 or less. When Mw is more than the above-mentioned lower limit, it is easy to improve mechanical properties such as bending resistance. It is advantageous from the viewpoint of processability at the time of film formation that Mw is not more than the above-mentioned upper limit.

In one embodiment of the present invention, the ratio of Mw to Mn (Mw/Mn) of the PI-based resin is preferably 3.5 or more in terms of polystyrene, more preferably 4.0 or more, still more preferably 4.2 or more, still more preferably 4.5 Above, especially preferably 4.7 or more, preferably 8.0 or less, more preferably 7.0 or less, still more preferably 6.0 or less, particularly preferably 5.5 or less. In addition, Mw and Mn can be calculated|required by performing gel permeation chromatography (it may describe as GPC hereafter) measurement, and calculating|required by standard polystyrene conversion.

In one embodiment of the present invention, the Tg of the PI-based resin is preferably 290°C or lower, more preferably lower than 290°C, even more preferably 280°C or lower, even more preferably 275°C or lower, especially preferably 260°C or lower, particularly preferably 250°C or lower, particularly more preferably 240°C or lower, from From the viewpoint of easy reduction of Df of the PI-based film and the viewpoint of easy improvement of heat resistance of the PI-based film, it is preferably 200°C or higher, more preferably 202°C or higher, and even more preferably 205°C or higher. Tg of the PI-based resin can be measured by dynamic viscoelasticity measurement, for example, by the method described in the examples.

The Tg of the PI-based resin can be adjusted by suitably adjusting the types of structural units constituting the PI-based resin and their structures, as well as the molecular weight and production method of the PI-based resin, especially the imidization conditions, etc., for example, by adjusting It adjusts to the said range within the range described as a preferable form in the said description.

In one embodiment of the present invention, the storage elastic modulus (hereinafter, sometimes referred to as E') of the PI-based resin at 280°C is easy to reduce the Df of the obtained PI-based film and to improve the bending resistance. From the viewpoint of stability, it is preferably 3×10 ⁸ Pa or less, more preferably 2×10 ⁸ Pa or less, still more preferably 1.5×10 ⁸ Pa or less, still more preferably 1×10 ⁸ Pa or less, and particularly preferably 0.8×10 8 Pa or less. 10 ⁸ Pa or less is preferably 1×10 ⁴ Pa or more, more preferably 1×10 ⁵ Pa or more, and still more preferably 1×10 ⁶ Pa or more from the viewpoint of easily suppressing deformation during processing of the PI-based film. E' of the PI-based resin can be measured by dynamic viscoelasticity measurement, for example, by the method described in the examples.

E' at 280°C of the PI-based resin can be adjusted by appropriately adjusting the types of structural units constituting the PI-based resin and their structures, as well as the molecular weight and production method of the PI-based resin, especially the imidization conditions, etc. , for example, can be adjusted to be within the above-mentioned range by adjusting to within the range described as the preferred mode in the above-mentioned description.

[Manufacturing method of polyimide resin]

The PI-based resin of the present invention can be produced by imidizing the PI-based resin precursor of the present invention, and is preferably produced by imidizing the PI-based resin precursor by heat treatment at 200° C. or higher and lower than 350° C. .

For the PI-based resin precursor in the present invention, even if imidization is carried out at low temperature, the Df of the PI-based film containing the obtained PI-based resin can be reduced, and the bending resistance can be improved. The amination temperature is preferably lower than 350°C, more preferably lower than 340°C, even more preferably lower than 330°C, even more preferably lower than 310°C, particularly preferably lower than 300°C. In addition, the imidization temperature is preferably 200° C. or higher, more preferably 210° C. or higher, and still more preferably 220° C. or higher, from the viewpoint of easily increasing the imidation rate sufficiently. In addition, the heating can be carried out stepwise. For example, after removing the solvent by heating at a relatively low temperature of 50 to 150° C., heating can be carried out stepwise to a temperature in the range of 200° C. or higher and lower than 350° C. Amination.

In one embodiment of the present invention, the reaction time in imidation is preferably 30 minutes to 24 hours, more preferably 1 to 12 hours. In addition, in one embodiment of the present invention, the time for maintaining the temperature of 200° C. or higher is preferably 5 to 90 minutes, more preferably 15 to 70 minutes, and even more preferably 20 to 50 minutes. When the reaction time at 200° C. or higher in imidization is within the above range, it is easy to sufficiently increase the imidization rate, it is easy to prevent oxidative degradation of the resin, and it is easy to improve dielectric properties and bending resistance.

The PI-based resin can be separated, purified, and separated by separation methods such as filtration, concentration, extraction, crystallization, recrystallization, column chromatography, and separation methods that combine them.

〔Polyimide film〕

The PI-based film of the present invention includes a PI-based resin obtained from the PI-based resin precursor of the present invention.

The PI-based film of the present invention has a low Df and is excellent in bending resistance even if the imidization temperature is low. Therefore, the present invention also includes a PI-based film comprising the PI-based resin of the present invention. In addition, the present invention also includes a PI-based film including a PI-based resin obtained by imidating a PI-based resin precursor by heat treatment at 200° C. or higher and lower than 350° C.

In one embodiment of the present invention, the content of the PI-based resin in the PI-based film is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass relative to the mass of the PI-based film of the present invention. % by mass or more, particularly preferably 90% by mass or more. The upper limit of the content of the PI-based resin is not particularly limited, but is, for example, 100% by mass or less, preferably 99% by mass or less, more preferably 95% by mass or less, based on the mass of the PI-based film. When the content of the PI-based resin is within the above range, it is easy to improve mechanical properties and thermal properties.

The PI-based film of the present invention may contain fillers as needed. Examples of the filler include metal oxide particles such as silica and alumina, inorganic salts such as calcium carbonate, polymer particles such as fluororesins and cycloolefin polymers, and the like. A filler can be used individually or in combination of 2 or more types. When a filler is included, its content is preferably 50% by mass or less, more preferably 40% by mass or less, further preferably 30% by mass or less, and preferably 0.01% by mass or more, based on the total mass of the PI-based film.

In addition, in one embodiment of the present invention, the PI-based film of the present invention may contain additives as necessary. Examples of additives include antioxidants, flame retardants, crosslinking agents, surfactants, compatibilizers, imidization catalysts, weather resistance agents, lubricants, antiblocking agents, antistatic agents, and antihalation agents. , No drops, pigments, etc. Additives can be used individually or in combination of 2 or more types. The content of various additives can be appropriately selected within the range that does not impair the effects of the present invention. When various additives are included, the total content is preferably 7% by mass or less with respect to the mass of the PI-based film, more preferably It is 5 mass % or less, More preferably, it is 4 mass % or less, Preferably it is 0.001 mass % or more.

In one embodiment of the present invention, the CTE of the PI-based film is preferably 50 ppm/K or less, more preferably 40 ppm/K or less, further preferably 30 ppm/K or less, still more preferably 25 ppm/K or less, preferably 0 ppm/K Above, more preferably 5 ppm/K or more, still more preferably 8 ppm/K or more, still more preferably 12 ppm/K or more. Since the copper foil and the CTE of the PI layer are close to each other by setting it in the above-mentioned range, peeling of a laminated film can be suppressed. In addition, CTE can be measured using the thermomechanical analysis apparatus (it may describe as "TMA" hereafter), for example, and can be calculated|required by the method described in an Example.

For printed circuits, transmission loss is required to be small. The transmission loss is represented by the sum of dielectric loss which is a loss due to an electric field generated by a dielectric, and conductor loss which is a loss due to a current flowing through a conductor. Furthermore, it is known that the dielectric loss is approximately proportional to the index E represented by the formula (i).

E＝Df×(Dk) ^1/2 (i)

[In the formula (i), Df represents the dielectric loss tangent, and Dk represents the relative permittivity]

In the high-frequency region used in 5G FPCs, the dielectric loss tends to increase. Therefore, a material with a small value of the above-mentioned index E and capable of suppressing the dielectric loss is particularly required.

On the other hand, the current of the high-frequency signal is concentrated on the outermost surface of the conductor. Thus, conductor loss is related to the dielectric properties of the adjoining dielectric, which is known to be approximately proportional to (Dk) ^1/2 .

For the PI-based film of the present invention obtained from the PI-based resin precursor of the present invention, as described above, in the PI-based resin precursor, the structural unit (A) satisfies the relationship of formula (X), and the structural unit (B1) The content is greater than 30 mol%, and Mw is greater than 100,000, therefore, Df and Dk become smaller, thus, the index E of the dielectric loss and the conductor loss are also smaller, and the transmission loss can be reduced in a circuit including the PI-based film.

In one embodiment of the present invention, the dielectric loss index E of the PI film at 10 GHz is preferably 0.01 or less, more preferably 0.009 or less, still more preferably 0.008 or less, still more preferably 0.007 or less, particularly preferably 0.006 or less. The smaller the index E is, the lower the transmission loss of the electronic circuit including the PI-based film is. Therefore, the lower limit of the index E is not particularly limited, and may be, for example, 0 or more.

In one embodiment of the present invention, the Df at 10 GHz of the PI-based film is preferably less than 0.004, more preferably 0.0038 or less, and still more preferably 0.0035 or less, from the viewpoint of easily reducing the transmission loss of an electronic circuit including a PI-based film. , is still more preferably 0.0033 or less, especially preferably 0.0030 or less, even more preferably 0.0027 or less, particularly preferably 0.0024 or less. The smaller the Df is, the lower the transmission loss of the electronic circuit including the PI-based film is. Therefore, the lower limit of the Df is not particularly limited, and may be, for example, 0 or more.

In one embodiment of the present invention, the Dk of the PI-based film at 10 GHz is preferably less than 3.50, more preferably 3.45 or less, further preferably 3.40 or less, still more preferably 3.38 or less, especially preferably 3.36 or less, and even more preferably 3.33 or less. or less, more particularly preferably 3.30 or less, particularly preferably 3.27 or less, particularly more preferably 3.22 or less.

Df and Dk of the PI-based film can be measured using a vector network analyzer and a resonator, for example, by the method described in the Examples.

For the PI-based film of the present invention obtained from the PI-based resin precursor of the present invention, as described above, in the PI-based resin precursor, the structural unit (A) satisfies the relationship of the aforementioned formula (X), and the structural unit (B1 ) content is more than 30 mol%, and Mw is more than 100,000, therefore, it has excellent bending resistance, especially bending resistance. In the MIT folding fatigue test according to ASTM standard D2176-16, the PI-based film of the present invention has a bending frequency of preferably 20,000 or more, more preferably 30,000 or more, still more preferably 50,000 or more, and even more preferably It is preferably 100,000 times or more, particularly preferably 150,000 times or more, and even more preferably 200,000 times or more. When the number of times of bending is equal to or greater than the above lower limit, even if bending is repeated, the occurrence of cracks, cracks, creases, and the like can be effectively suppressed. In addition, the upper limit of the number of times of bending is not particularly limited, and may be, for example, 10,000,000 or less. In addition, the MIT folding fatigue test can be measured using the MIT folding fatigue tester, for example, can be measured by the method described in an Example.

In one embodiment of the present invention, from the viewpoint of easily reducing the Df of the PI-based film and improving the bending resistance, E' at 280° C. of the PI-based resin and the CTE of the PI-based film containing the PI resin preferably satisfy The relationship of formula (Y).

120,000≤(CTE of PI-based film)×(E' of PI-based resin at 280°C) ^1/2 ≤850,000

In one embodiment of the present invention, the value of the formula (Y) is preferably greater than 120,000, more preferably 125,000 or more, further preferably 135,000 or more, and is preferably 750,000 or less, more preferably 500,000 or less, still more preferably 450,000 or less, still more preferably 400,000 or less, particularly preferably 300,000 or less, even more preferably 200,000 or less, and even more preferably 190,000 or less.

The thickness of the PI-based film of the present invention can be appropriately selected according to the application, and is preferably 5 μm or more, more preferably 10 μm or more, further preferably 20 μm or more, preferably 500 μm or less, more preferably 300 μm or less, and even more preferably 100 μm or less. It is particularly preferably 80 μm or less, and particularly more preferably 50 μm or less. The thickness of the film can be measured using a film thickness meter or the like. In addition, when the film of this invention is a multilayer film, the said thickness shows the thickness of a single-layer part.

The PI-based film of the present invention can be subjected to surface treatments such as corona discharge treatment, plasma treatment, and ozone treatment by methods generally used industrially.

The PI-based film of the present invention has a low Df and is excellent in bending resistance, so it can be suitably used as a substrate material for printed circuit boards for high-frequency bands, antenna substrates, and the like. Metal-clad laminates such as CCL used for FPC are widely used in which a single-layer or multi-layer PI-based resin has a thin metal layer such as a copper foil layer on one or both sides. When using the PI-based film of the present invention as the resin layer, since the PI-based film of the present invention can lower Df even if the imidization temperature is low, even if the PI-based film of the present invention is used on a metal foil such as copper foil, Thermal imidization of a PI-based resin precursor coating film to produce metal-clad laminates such as CCL can also suppress the deterioration of the metal foil surface, so CCL with excellent high-frequency characteristics can be obtained.

[Manufacturing method of polyimide-based film]

The PI-based film of the present invention can be produced, for example, by a method including the following steps.

A step of coating a PI-based resin precursor solution comprising the PI-based resin precursor of the present invention on a substrate; and

A process of imidating the PI-based resin precursor by heat treatment at 200° C. or higher and lower than 350° C.

<Coating process of polyimide-based resin precursor solution>

(Preparation of PI-based resin precursor solution)

The PI-based resin precursor solution includes the PI-based resin precursor of the present invention and a solvent, and can be prepared by mixing the PI-based resin precursor of the present invention with a solvent. In addition, in one embodiment of the present invention, the reaction solution containing the PI-based resin precursor obtained through the synthesis of the PI-based resin precursor can also be appropriately diluted with a solvent as needed, and the PI-based resin precursor solution can be use.

The solvent contained in the PI-based resin precursor solution includes solvents exemplified as solvents used in the reaction of diamine compounds and tetracarboxylic acid compounds in the production of PI-based resin precursors, preferably lactone-based solvents, amides solvents, pyrrolidone-based solvents, more preferably amide-based solvents. In addition, in one embodiment of the present invention, even if the imidization temperature is low, the Df of the obtained PI-based film can be easily lowered and the bending resistance can be easily improved. The solvent contained in the PI-based resin precursor solution The boiling point of is preferably 230°C or lower, more preferably 200°C or lower, even more preferably 180°C or lower, particularly preferably 170°C or lower. In addition, the boiling point of the solvent is preferably 100° C. or higher, and more preferably 120° C. or higher, from the viewpoint of easily lowering Df of the obtained PI-based film and improving bending resistance.

With respect to the total amount of the PI-based resin precursor solution, the content of the PI-based resin precursor contained in the PI-based resin precursor solution is preferably 8% by mass or more, more preferably 10% by mass or more, and even more preferably 12% by mass. % or more, particularly preferably 13 mass % or more, and preferably 30 mass % or less, more preferably 25 mass % or less, still more preferably 23 mass % or less, particularly preferably 20 mass % or less. When content of a PI type resin precursor exists in the said range, it will be excellent in the processability at the time of film formation.

(Coating of polyimide resin precursor solution)

The step of applying the PI-based resin precursor solution is a step of applying the PI-based resin precursor solution on a substrate to form a coating film.

In the coating step, the composition is coated on the substrate to form a coating film using a known coating method or coating method. Examples of known coating methods include roll coating methods such as wire bar coating, reverse coating, and gravure coating, die coating, comma coating, lip coating, spin coating, Screen printing coating method, jet knife coating method, dipping method, spray coating method, curtain coating method, slit coating method, tape casting method, etc. When coating or coating the solution of PI-based resin precursor on the substrate, a single layer of PI-based resin precursor can be coated on the substrate, or multiple layers of PI-based resin precursor can be coated on the substrate . In the case of coating the PI-based resin precursor in multiple layers on the base material, the coating and drying may be divided into multiple times, or multiple layers may be coated at the same time.

Examples of substrates include copper plates such as copper foil, SUS plates such as SUS foil and SUS tape, glass substrates, PET films, PEN films, PI-based resin films other than the PI-based film of the present invention, polyamide-based resin film etc. Among them, from the viewpoint of excellent heat resistance, copper plates, SUS plates, glass substrates, PET films, PEN films, etc. are preferably mentioned, and from the viewpoints of adhesion to the film and cost, copper plates, SUS board, glass substrate or PET film, etc.

<Imidization process>

The imidization step is a step of imidating the PI-based resin precursor applied on the substrate by heat treatment at 200° C. or higher and lower than 350° C.

In one embodiment of the present invention, the imidization step is preferably the following step: before the imidization of the PI-based resin precursor, the coating is applied to the substrate at a lower temperature, for example, lower than 200°C. The PI-based resin precursor solution is heated and dried, and the obtained dry film of the PI-based resin precursor is imidized by heat treatment at 200° C. or higher and lower than 350° C.

In addition, in one embodiment of the present invention, the dried film of the PI-based resin precursor on the substrate may be imidized to obtain a PI-based film, or the dried film of the PI-based resin precursor may be peeled off from the substrate. , imidizes the dry film peeled off from the substrate to obtain a PI-based film.

In one embodiment of the present invention, the drying temperature of the PI-based resin precursor applied to the substrate is not particularly limited as long as it is within the temperature range where the solvent can be dried and solidified. From the viewpoint of surface roughness due to drying and suppression of wrinkles and kinks during processing, it is preferably lower than 300°C, more preferably 260°C or lower, even more preferably 200°C or lower, and even more preferably 180°C or lower. In addition, from the viewpoint of productivity, it is preferably 50°C or higher, more preferably 80°C or higher, and still more preferably 100°C or higher.

In the PI-based resin precursor in the present invention, even if imidization is performed at a low temperature, Df of the PI-based film obtained can be lowered, and bending resistance can be improved. The heat treatment temperature in the imidization step, that is, the imidization temperature is preferably lower than 350°C, more preferably 340°C or lower, even more preferably 330°C or lower, still more preferably 310°C or lower, particularly preferably 300°C or lower . If the imidization temperature is below the above-mentioned upper limit, even when metal foil such as copper foil is used as a base material, thermal deterioration of metal foil, etc., especially copper foil, can be suppressed, so it is easy to obtain high-frequency characteristics and CCL with excellent bending resistance. In addition, the imidization temperature is preferably 200° C. or higher, more preferably 210° C. or higher, and still more preferably 220° C. or higher, from the viewpoint of easily increasing the imidation rate sufficiently. Moreover, it is preferable to heat in stages from the viewpoint of being easy to obtain a smooth film. For example, after removing a solvent by heating at a relatively low temperature of 50 to 150° C., imidization may be performed by heating stepwise to a temperature in a range from 200° C. to less than 350° C.

In one embodiment of the present invention, the reaction time in imidation is preferably 30 minutes to 24 hours, more preferably 1 to 12 hours. In addition, in one embodiment of the present invention, the time for maintaining the temperature of 200° C. or higher is preferably 10 minutes to 90 minutes, more preferably 15 minutes to 70 minutes, and even more preferably 20 minutes to 50 minutes.

After the imidization, the coating film formed on the base material is peeled off from the base material, whereby a PI-based film can be obtained. In one embodiment of the present invention, when the base material is a metal foil such as copper foil, a PI-based film can also be formed without peeling the coating film from the metal foil such as copper foil, and the obtained film can be coated on a copper foil or the like. A laminated film in which a PI-based film is laminated on a metal foil is used for CCL.

When the film of the present invention is a multilayer film, it can be produced by, for example, a multilayer film forming method such as coextrusion processing, extrusion lamination, thermal lamination, or dry lamination.

〔Laminated film〕

Since the PI-based film of the present invention has low Df and excellent bending resistance, it can be suitably used for forming a metal-clad laminate for FPC. Therefore, a laminated film including a PI layer and a metal foil layer using the PI-based film of the present invention as a PI layer is included. In one embodiment of the present invention, the laminated film of the present invention may contain the metal foil layer on only one side of the PI layer, or may contain the metal foil layer on both sides of the PI layer.

In one embodiment of the present invention, examples of the metal foil include copper foil, SUS foil, aluminum foil, and the like, and copper foil is preferable from the viewpoint of electrical conductivity and metal workability.

For the PI-based film of the present invention, even if the thermal imidization temperature is low, its Df is low, and it can be suitably used to form a CCL having excellent high-frequency characteristics and bending resistance. Therefore, it is a preferred embodiment of the present invention. Among the embodiments, the laminated film of the present invention is preferably a laminated film including a copper foil layer on one or both surfaces of the PI-based film of the present invention.

In one embodiment of the present invention, the thickness of the metal foil layer, especially the copper foil layer, is preferably 1 μm or more, and more preferably 5 μm or more. In addition, from the viewpoint of easy miniaturization of circuits and improvement of bending resistance, preferably It is 100 μm or less, more preferably 50 μm or less, still more preferably 30 μm or less, particularly preferably 20 μm or less. The thickness of the metal foil layer, especially the copper foil layer, can be measured using a film thickness gauge or the like. In addition, when both surfaces of a PI-type film contain a metal foil layer, especially a copper foil layer, the thickness of each metal foil layer, especially each copper foil layer may mutually be the same or different.

In one embodiment of the present invention, the thickness of the laminated film is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 60 μm or less. The thickness of the laminated film can be measured using a film thickness meter or the like.

The laminated film of the present invention may contain other layers such as functional layers in addition to the PI-based film and the metal foil layer, especially the copper foil layer. The layer exemplified above is mentioned as a functional layer, For example, a thermoplastic PI-based resin layer containing a thermoplastic PI-based resin, an adhesive layer, etc. are mentioned. A functional layer can be used individually or in combination of 2 or more types.

In one embodiment of the present invention, the laminated film of the present invention may be a double-layer metal-clad laminate composed of a metal foil layer and a PI layer, or a three-layer laminate composed of a metal foil layer, a PI layer and an adhesive layer. The metal laminate is preferably a two-layer metal-clad laminate that does not include an adhesive layer from the viewpoint of heat resistance, dimensional stability, and weight reduction.

In addition, the PI-based film of the present invention has low Df and excellent bending resistance even if the imidization temperature is low. The laminated film in which the metal foil is copper foil is produced by imidization, and the deterioration of the copper foil surface can also be suppressed. Therefore, even if the laminated film of the present invention does not include an adhesive layer, it has excellent high-frequency characteristics.

In addition, in one embodiment of the present invention, the PI-based film of the present invention may be directly in contact with the metal foil layer, especially the copper foil layer, or may be inserted between the PI-based film and the metal foil layer, especially the copper foil layer. The functional layers are in contact with each other through the functional layer, and the PI-based film is preferably in direct contact with the metal foil layer, especially the copper foil layer, from the viewpoint of easy improvement of mechanical and thermal properties.

The functional layer that can be inserted between the PI-based film and the metal foil layer of the present invention may be a thermoplastic PI layer. The layer in direct contact with the metal foil layer, especially the copper foil layer, is preferably the PI film of the present invention or a thermoplastic PI layer as a functional layer from the viewpoint of easy improvement of mechanical and thermal properties.

〔Manufacturing method of laminated film〕

The laminated film of the present invention can be produced, for example, by a method including the following steps.

A step of coating a PI-based resin precursor solution comprising the PI-based resin precursor of the present invention on a substrate; and

A step of imidizing a PI-based resin precursor by heat treatment at 200° C. or higher and lower than 350° C. to form the PI-based film of the present invention on a substrate.

Regarding "the step of applying the PI-based resin precursor solution containing the PI-based resin precursor of the present invention on the base material" and "passing the temperature at 200° C. Heat treatment to imidize the PI-based resin precursor to form the PI-based film of the present invention on the base material", related to each step described in the item [Method for producing polyimide-based film] The same instructions apply.

In one embodiment of the present invention, the substrate is preferably metal foil, particularly preferably copper foil. Regarding the description about the metal foil, especially the copper foil, the description about the metal foil described in the section of "Laminated Film" is also applicable.

The laminated film of the present invention can also be produced by methods other than the above-mentioned methods, for example, the following method: On a substrate other than the metal foil contained in the laminated film, PI containing the PI-based resin precursor of the present invention is coated. The PI-based resin precursor solution was dried, the thus-obtained dried film of the PI-based resin precursor was peeled from the substrate, and the peeled dried film of the PI-based resin precursor was bonded to a metal foil. As a method of bonding the dry film of the PI-based resin precursor to the metal foil, a method based on pressure, a lamination method using a hot roll, etc. may be used, and the PI-based resin pretreatment may be carried out simultaneously in the bonding process. imidization of body. However, the PI-based film of the present invention has a low Df and excellent bending resistance even at a low imidization temperature. It is also possible to suppress the deterioration of the copper foil surface by imidizing to produce a laminated film in which the metal foil is copper foil. Therefore, the laminated film of the present invention has excellent high-frequency characteristics and bending resistance even if it is produced without going through the above-mentioned bonding process.

〔Flexible printed circuit board〕

The PI-based film obtained from the PI-based resin precursor of the present invention has a low Df and excellent bending resistance, so it can be suitably used as an FPC substrate material, especially an FPC substrate material for foldable devices. The present invention also includes an FPC substrate including the above-mentioned PI-based film.

[Example]

Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

Abbreviations used in Examples, Comparative Examples, and Reference Examples represent the following compounds.

BPDA: 3,3’,4,4’-Biphenyltetracarboxylic dianhydride

TAHQ: p-phenylene bis(trimellitic acid monoester dianhydride)

PMDA: pyromellitic dianhydride

BP-TME: 4,4’-bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-ylcarbonyloxy)biphenyl

m-Tb: 4,4’-diamino-2,2’-dimethylbiphenyl

BAPP: 2,2-bis[4-(4-aminophenoxy)phenyl]propane

TPE-Q: 1,4-bis(4-aminophenoxy)benzene

[Synthesis of polyimide resin precursor]

(Example 1)

After dissolving 27.00 g (127.2 mmol) of m-Tb in 421 g of DMAc, 28.86 g (63.0 mmol) of TAHQ was added, and stirred at 20° C. for 1 hour under a nitrogen atmosphere. Then, BPDA 18.52g (63.0mmol) was added, and it stirred at 20 degreeC for 24 hours under nitrogen atmosphere, and obtained the PI resin precursor composition. The molar ratio of the diamine monomer used with respect to the acid dianhydride monomer was 1.01. Mn in the polystyrene conversion molecular weight of the obtained PI resin precursor was 35,000, and Mw was 170,000.

(Examples 2-11, Comparative Examples 2-3)

The PI resin precursor composition was obtained similarly to Example 1 except having changed the monomer type and monomer composition used, respectively, as shown in Table 1. Regarding the order of adding monomers, as long as there is no special record, the order of diamine and acid dianhydride is followed. The anhydrides are added in the order in which the acid dianhydrides derived from the structural units (A1), (A2) and (A3) are added.

[Manufacture of polyimide film]

Using the solvent used in the synthesis of the PI resin precursor, the PI resin precursors obtained in Examples 1 to 11 and Comparative Examples 2 and 3 are appropriately combined within the range where the content of the PI resin precursor becomes 10% by mass or more. Dilute the product and adjust the viscosity below 40,000cps to prepare the PI resin precursor solution. The PI resin precursor solution was formed into a film under any one of the following film forming conditions 1 to 4 as shown in Table 1, to obtain a PI film made of a PI resin.

<Film Production Condition 1>

The PI resin precursor solution was tape casted on a glass substrate, and a coating film of the PI resin precursor solution was formed at a line speed of 0.4 m/min using an applicator. The said coating film was heated at 120 degreeC for 30 minutes, and after peeling the obtained film from a glass substrate, the film was fixed to the metal frame. The film fixed to the metal frame was heated from 30° C. to 270° C. over 19 minutes in an atmosphere having an oxygen concentration of 7%, and then cooled to 200° C. over 35 minutes to produce a PI film. The time during which the temperature of 220° C. or higher was maintained was 23 minutes. In addition, the time during which the temperature of 200° C. or higher was maintained was 34 minutes.

<Film Production Condition 2>

The PI resin precursor solution was tape-cast on the roughened surface side (surface roughness; Rz=1.3 μm) of an electrolytic copper foil (manufactured by JX Metal Co., Ltd., JXEFL-BHM thickness: 12 μm), using an applicator, A coating film of the PI resin precursor solution was formed at a line speed of 0.4 m/min. The said coating film was heated and dried at 120 degreeC for 30 minutes. Then, the laminated film of the copper foil and the precursor was fixed to a metal frame, and in an atmosphere with an oxygen concentration of 1%, the temperature was raised from 30°C to 320°C over 9 minutes, then heated at 320°C for 6 minutes, and then cooled for 15 minutes. to 200°C to produce a laminated film of PI film and copper foil. The time during which the temperature of 220° C. or higher was maintained was 21 minutes. In addition, the time for maintaining the temperature of 200° C. or higher was 25 minutes.

The laminated film of the obtained PI film and copper foil was immersed in a large-capacity ferric chloride aqueous solution having a concentration of 40% by mass at room temperature for 10 minutes, and after visually confirming that there was no copper residue, it was carried out at 80°C for 1 Hours of drying to obtain a separate PI film.

<Film Forming Condition 3>

The PI resin precursor solution was tape-cast on a glass substrate, and a coating film of the resin precursor solution was formed at a line speed of 0.4 m/min using an applicator. The said coating film was heated at 120 degreeC for 30 minutes, and after peeling the obtained film from a glass substrate, the film was fixed to the metal frame. For the film fixed on the metal frame, in an atmosphere with an oxygen concentration of 1%, the temperature was raised from 30°C to 320°C in 9 minutes, then heated at 320°C for 6 minutes, and cooled to 200°C in 15 minutes to produce PI. membrane. The time during which the temperature of 220° C. or higher was maintained was 21 minutes. In addition, the time for maintaining the temperature of 200° C. or higher was 25 minutes.

<Film Production Condition 4>

The PI resin precursor solution was tape casted on a glass substrate, and a coating film of the PI resin precursor solution was formed at a line speed of 0.4 m/min using an applicator. The said coating film was heated at 120 degreeC for 30 minutes, and after peeling the obtained film from a glass substrate, the film was fixed to the metal frame. For the film fixed on the metal frame, in an atmosphere with an oxygen concentration of 1%, the temperature was raised from 30°C to 320°C in 5 minutes, then heated at 320°C for 5 minutes, and cooled to 200°C in 15 minutes to produce PI. membrane. The time during which the temperature of 220° C. or higher was maintained was 17 minutes. In addition, the time during which the temperature of 200° C. or higher was maintained was 21 minutes.

[Synthesis of polyimide resin precursor and production of polyimide film]

(comparative example 1)

After dissolving 70.33 g (331 mmol) of m-Tb in 720 g of NMP, 73.06 g (248 mmol) of BPDA and 37.94 g (83 mmol) of TAHQ were added thereto, and stirred at room temperature for 1 hour under a nitrogen atmosphere. Then, it stirred at 60 degreeC for 20 hours, and obtained the PI resin precursor composition. In addition, Mw in terms of polystyrene of the PI resin precursor was 91,000, and Mn was 27,000. The PI resin precursor composition was appropriately diluted with NMP to adjust the viscosity to prepare a PI resin precursor solution, and the obtained PI resin precursor solution was formed into a film under the aforementioned film forming condition 1 to obtain a PI film.

The obtained PI film had a thickness of 30 μm, a Dk of 3.45, a Df of 0.0040, an index E of 0.0074, the number of times of bending until breaking was 886, and a CTE of 38.2 ppm. In addition, the Tg of the PI resin is 255°C, the E' at 280°C is 5.53×10 ⁸ Pa, and the CTE×(E') ^1/2 is 8.98×10 ⁵ .

In addition, Tg obtained by using the tangent method from the storage elastic modulus curve was 230°C.

Each measurement and evaluation were performed about the PI resin precursor and PI film obtained in the Example and the comparative example. The measurement and evaluation methods will be described below.

<Measurement of weight average molecular weight and number average molecular weight>

Mw and Mn in terms of polystyrene of the PI resin precursor obtained by synthesis were measured using GPC. GPC measurement was carried out under the following conditions.

(1) Pretreatment method

After diluting the sample with DMF, it filtered with a 0.45-micrometer membrane filter, and the obtained solution was used as a measurement solution.

(2) Measurement conditions

Column: Connect 2 pieces of TSKgel SuperAWM-H (inner diameter 6.0mm, length 150mm)

Eluent: DMF (add 10mmol/L lithium bromide, add 30mmol/L phosphoric acid)

Flow: 0.6mL/min

Detector: RI detector

Column temperature: 40°C

Injection volume: 20μL

Molecular weight standard: standard polystyrene

<Measurement of glass transition temperature (Tg)>

Tg of the PI resins obtained in Examples and Comparative Examples was determined by measuring the PI film as follows.

Using a dynamic viscoelasticity measuring device (manufactured by IT Keisoku Seigyo Co., Ltd., DVA-220), the measurement is carried out under the following sample and conditions, and the storage modulus (Storage modulus, E') and The tan δ curve of the ratio of the loss elastic modulus (Loss modulus, E") value. Let the topmost point of the peak of the tan δ curve be Tg.

Test piece: a rectangular parallelepiped with a length of 40 mm, a width of 5 mm, and a thickness of 50 μm (it should be noted that the thickness varies depending on the film used)

Experiment mode: single frequency, constant temperature rise

Experimental method: stretching

Sample clamping interval length: 15mm

Determination of starting temperature: room temperature ~ 342 ℃

Heating rate: 5°C/min

Frequency: 10Hz

Static/dynamic stress ratio: 1.8

Main collected data:

(1) Storage modulus (Storage modulus, E')

(2) Loss modulus of elasticity (Loss modulus, E")

(3) tanδ(E”/E’)

<Measurement of storage elastic modulus (E')>

E' at 280°C of the PI resins obtained in Examples and Comparative Examples was determined by performing dynamic viscoelasticity measurement in the same manner as Tg measurement.

<Measurement of Coefficient of Thermal Expansion (CTE)>

The CTE of the PI films obtained in Examples and Comparative Examples was measured using TMA under the following conditions, and the CTE at 50°C to 100°C was calculated.

Device: TMA/SS7100 manufactured by Hitachi High-Tech Science Corporation

Load: 50.0mN

Temperature program: from 20°C to 130°C at a rate of 5°C/min

Test piece: a rectangular parallelepiped with a length of 40 mm, a width of 5 mm, and a thickness of 50 μm (it should be noted that the thickness varies depending on the film used)

<Evaluation of index E of dielectric loss>

The index E of the dielectric loss of the film was calculated from the following formula.

E＝Df×(Dk) ^1/2 (i)

Df: dielectric loss tangent

Dk: relative permittivity

(Determination of Df and Dk)

Measurement samples of 50 mm×50 mm were cut out from the PI films obtained in Examples and Comparative Examples, and Df and Dk were measured under the following conditions. The measurement was performed after humidity-conditioning the measurement sample at 25° C./55% RH for 24 hours.

Device: Compact USB vector network analyzer manufactured by Anritsu Corporation (product name: MS46122B)

AET Inc. Cavity Resonator (TE Mode 10GHz Type)

Measurement frequency: 10GHz

Measuring atmosphere: 23°C/50%RH

<Evaluation of bending resistance>

The bending resistance of the PI films obtained in Examples and Comparative Examples was evaluated by measuring the number of times the film was bent under the following conditions. The film was cut into a rectangle having a length of 100 mm and a width of 10 mm using a dumbbell cutter. Set the cut film on the MIT folding fatigue tester (manufactured by Toyo Seiki Seisakusho, MIT-DA) based on ASTM standard D2176-16, at a test speed of 175cpm and a bending angle of 135° , under the conditions of a load of 750 g and a bending jig of R=1.0 mm, the film was alternately bent in two directions, the front and the back, and the number of times of bending until fracture occurred was measured. The larger the number of bending times, the better the bending resistance.

Table 1 shows the measurement and evaluation results and amine ratios of the PI resin precursors, PI resins, and PI films obtained in Examples and Comparative Examples. In Table 1, CTE×(E′) ^1/2 represents CTE×(E′ at 280° C. of PI resin) ^1/2 of the PI film.

[Table 1]

As shown in Table 1, it was confirmed that for the PI films obtained from the PI resin precursors of Examples 1 to 11, even if the highest temperature of the imidization treatment was as low as 270° C. or 320° C. Df is also low compared with the comparative example, and it is excellent in bending resistance. Therefore, for the PI-based film obtained from the PI-based resin precursor of the present invention, even if the PI resin precursor solution is cast into a film on a metal foil such as copper foil, and the PI resin precursor is cast on the metal foil, The coating film of the solution is produced by thermal imidization, and thermal deterioration such as surface roughness of the metal foil can also be suppressed, so it can be suitably used for high-frequency bands and foldable devices with low transmission loss. And CCL with excellent bending resistance. As a result, an FPC with a small dielectric loss can be provided.

In addition, by using the PI resin precursor of the present invention, even if imidization is performed in a structure laminated with metal foil such as copper foil, FPC can be produced without exposing the metal foil to high temperature, and the metal foil can be suppressed. The surface roughness and oxidation of the foil also reduce the conductor loss, so it is possible to provide an FPC that suppresses the transmission loss that is the sum of the dielectric loss and the conductor loss. In addition, since metal foils such as copper foil are not exposed to high temperatures, it is possible to suppress the reduction in bending resistance caused by the increase in the crystal grain size of the metal foil caused by heating, and it is possible to provide both the PI film and the metal foil that can withstand continuous Curved, FPC with excellent bending resistance.

Claims (13)

1. A polyimide resin precursor comprising a structural unit (A) derived from a tetracarboxylic anhydride and a structural unit (B) derived from a diamine,

the structural unit (A) comprises a structural unit (A1) derived from a tetracarboxylic anhydride containing an ester bond and a structural unit (A2) derived from a tetracarboxylic anhydride containing a biphenyl skeleton,

the structural unit (A) satisfies the relationship of formula (X),

(content of structural unit (A3) derived from tetracarboxylic anhydride excluding the structural unit (A1) and the structural unit (A2)/(total amount of the structural unit (A1) and the structural unit (A2)) <0.67 (X);

the structural unit (B) contains a structural unit (B1) derived from a diamine having a biphenyl skeleton, the content of the structural unit (B1) is more than 30 mol% with respect to the total amount of the structural units (B),

the polyimide resin precursor has a weight average molecular weight of more than 100,000 in terms of polystyrene.

2. The polyimide-based resin precursor according to claim 1, wherein the structural unit (A1) is a structural unit (A1) derived from a tetracarboxylic anhydride represented by the formula (A1),

in the formula (a 1), Z represents a 2-valent organic group,

R ^a1 independently of one another, represents a halogen atom or an alkyl, alkoxy, aryl or aryloxy group which may have a halogen atom,

s independently of one another represent an integer from 0 to 3.

3. The polyimide-based resin precursor according to claim 1 or 2, wherein the structural unit (A2) is a structural unit (A2) derived from a tetracarboxylic anhydride represented by the formula (A2),

in the formula (a 2), R ^a2 Independently of one another, represents a halogen atom or an alkyl, alkoxy, aryl or aryloxy group which may have a halogen atom,

t independently of one another represents an integer from 0 to 3.

4. The polyimide-based resin precursor according to any one of claim 1 to 3, wherein the structural unit (B1) is a structural unit (B1) derived from a diamine represented by the formula (B1),

in the formula (b 1), R ^b1 Independently of one another, represents a halogen atom or an alkyl, alkoxy, aryl or aryloxy group which may have a halogen atom,

p represents an integer of 0 to 4.

5. The polyimide-based resin precursor according to any one of claims 1 to 4, wherein the structural unit (B) further comprises a structural unit (B2) derived from a diamine represented by the formula (B2),

in the formula (b 2), R ^b2 Independently of one another, represents a halogen atom or an alkyl, alkoxy, aryl or aryloxy group which may have a halogen atom,

w independently of one another represents-O-, -CH ₂ -、-CH ₂ -CH ₂ -、-CH(CH ₃ )-、-C(CH ₃ ) ₂ -、-C(CF ₃ ) ₂ -、-COO-、-OOC-、-SO ₂ -, -S-, -CO-or-N (R) ^c )-，R ^c Represents a monovalent hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom,

m is an integer of 1 to 4,

q independently of one another represents an integer from 0 to 4.

6. The polyimide-based resin precursor according to claim 5, wherein m is 3,W in the structural unit (b 2) independently of each other is-O-or-C (CH) ₃ ) ₂ -。

7. A polyimide resin obtained from the polyimide resin precursor according to any one of claims 1 to 6.

8. The polyimide resin according to claim 7, having a glass transition temperature of 200 to 290 ℃.

9. The polyimide-based resin according to claim 7 or 8, which has a storage elastic modulus of less than 3X 10 at 280 ℃ ⁸ Pa。

10. A polyimide film comprising the polyimide resin according to any one of claims 7 to 9.

11. The polyimide film according to claim 10, which has a dielectric loss tangent of 0.004 or less at 10 GHz.

12. A laminated film comprising a metal foil layer on one or both surfaces of the polyimide film according to claim 10 or 11.

13. A flexible printed circuit board comprising the polyimide film according to claim 10 or 11.