KR20240077428A - Polyimide based resin - Google Patents

Abstract

The polyimide resin of the present invention contains a structural unit (A) derived from tetracarboxylic anhydride and a structural unit (B) derived from diamine, and the structural unit (A) derived from tetracarboxylic anhydride has the formula (A1) :

[Z is equation (z1):

(n represents an integer from 2 to 4)
[It is a divalent organic group represented by]
A structural unit derived from tetracarboxylic anhydride represented by (A1), and formula (A2):

The structural unit (A2) derived from tetracarboxylic anhydride represented by , and the structural unit (B) derived from diamine include the structural unit (B1) derived from a diamine containing a biphenyl skeleton.

Description

Polyimide-based resin {POLYIMIDE BASED RESIN}

Includes a polyimide-based resin capable of forming a polyimide-based film that can be used as a printed circuit board for a high-frequency band or a substrate material compatible with an antenna board, the polyimide-based film and its manufacturing method, and the polyimide-based film. It relates to a laminated film and a flexible printed circuit board.

Flexible printed circuit boards (hereinafter sometimes referred to as FPCs) are thin, lightweight, and flexible, allowing for three-dimensional, high-density mounting, such as mobile phones, hard disks, etc. It is used in many electronic devices and contributes to their miniaturization and weight reduction. Conventionally, polyimide resins with excellent heat resistance, mechanical properties, and electrical insulation properties have been widely used in FPCs, for example, copper-clad laminates (hereinafter sometimes abbreviated as CCL) used in FPCs. As a metal-clad laminate, a laminate having a copper foil layer on one or both sides of a single-layer or multiple-layer polyimide film is known.

Recently, the 5th generation mobile communication system called 5G is being spread in earnest (for example, patent document 1).

Japanese Patent Laid-Open No. 2021-161285

However, in metal-clad laminates using polyimide materials that have been used conventionally, when transmitting high-frequency signals used in high-speed communication after 5G, transmission loss is large, and there are problems such as loss of electrical signals and long signal delay times. This happens. Therefore, for the purpose of reducing transmission loss, polyimide films with low dielectric loss tangent (hereinafter sometimes referred to as Df) and relative dielectric constant (hereinafter sometimes referred to as Dk) are being studied. No polyimide film has been found with sufficiently low electric current or dielectric loss tangent.

Therefore, the object of the present invention is to provide a polyimide-based resin capable of forming a polyimide-based film with a low Df that can form a metal-clad laminate such as CCL with low transmission loss in a high frequency band, the polyimide-based film, and the same. The object is to provide a manufacturing method, a laminated film containing the polyimide-based film, and a flexible printed circuit board.

The present inventors have arrived at the present invention as a result of intensive studies to solve the above problems. That is, the present invention provides the following suitable aspects.

[1] A polyimide resin containing a structural unit (A) derived from tetracarboxylic anhydride and a structural unit (B) derived from diamine,

The structural unit (A) derived from tetracarboxylic anhydride has the formula (A1):

[In formula (A1), Z is formula (z1):

(In formula (z1), R ^z11 to R ^z14 independently represent a monovalent hydrocarbon group that may have a hydrogen atom or a halogen atom, n represents an integer of 2 to 4, and * represents a bond. )

is a divalent organic group represented by , R ^a1 independently represents a halogen atom or an alkyl group, alkoxy group, aryl group or aryloxy group that may have a halogen atom, and s independently represents 0 to 3. represents an integer]

A structural unit derived from tetracarboxylic anhydride represented by (A1), and formula (A2):

[In formula (A2), R ^a2 independently represents a halogen atom or an alkyl group, alkoxy group, aryl group, or aryloxy group that may have a halogen atom, and k independently represents an integer of 0 to 2. indicates]

Contains a structural unit (A2) derived from tetracarboxylic anhydride represented by,

A polyimide-based resin in which the diamine-derived structural unit (B) contains a biphenyl skeleton-containing diamine-derived structural unit (B1).

[2] The polyimide resin according to [1], wherein the content of the structural unit (A1) is 15 mol% or more based on the total amount of the structural unit (A).

[3] The polyimide resin according to [1] or [2], wherein the content of the structural unit (A1) is 75 mol% or less based on the total amount of the structural unit (A).

[4] The polyimide resin according to [1] or [2], wherein the content of the structural unit (A2) is 25 mol% or more relative to the total amount of the structural unit (A).

[5] The structural unit (B1) has formula (b1):

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

p represents an integer from 0 to 4]

The polyimide resin according to [1] or [2], which is the diamine-derived structural unit (b1) represented by .

[6] The polyimide resin according to [5], wherein the content of the structural unit (B1) exceeds 30 mol% based on the total amount of the structural unit (B).

[7] The structural unit (B) is further represented by formula (b2):

[In formula (b2), R ^b2 independently represents a halogen atom or an alkyl group, alkoxy group, aryl group or aryloxy group which may have a halogen atom, and the hydrogen atoms contained in R ^b2 independently represent , may be substituted by a halogen atom,

W are, independently of each other, -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 )-, and R ^c is a hydrogen atom or 1 to 12 carbon atoms that may be substituted with a halogen atom. represents a monovalent hydrocarbon group, m represents 3 or 4, and q independently represents an integer of 0 to 4]

The polyimide resin according to [1] or [2], which contains less than 20 mol% of the diamine-derived structural unit (b2) represented by .

[8] A polyimide-based film containing the polyimide-based resin according to [1] or [2].

[9] The polyimide-based film according to [8], wherein the dielectric loss tangent at 10 GHz is 0.004 or less.

[10] The polyimide-based film according to [8], wherein the thickness is 5 to 100 μm.

[11] A laminated film comprising a metal foil layer on one or both sides of the polyimide-based film according to [8].

[12] The laminated film according to [11], wherein the metal foil layer is a copper foil layer.

[13] A flexible printed circuit board comprising the polyimide-based film according to [8].

[14] A process of coating a polyimide-based resin precursor solution containing a polyimide-based resin precursor having a structural unit derived from tetracarboxylic anhydride and a structural unit derived from diamine onto a substrate, and

The method for producing a polyimide-based film according to [8], which includes a step of imidizing a polyimide-based resin precursor by heat treatment at 200°C or higher and 500°C or lower.

The polyimide-based resin of the present invention can form a polyimide-based film with a low Df that can form a metal-clad laminate such as CCL with low transmission loss in a high frequency band.

Hereinafter, embodiments of the present invention will be described in detail. In addition, the scope of the present invention is not limited to the embodiments described herein, and various changes can be made without departing from the spirit of the present invention.

[polyimide-based resin]

The polyimide resin of the present invention is composed of a structural unit (A) derived from tetracarboxylic anhydride (sometimes simply referred to as structural unit (A)) and a structural unit (B) derived from diamine (simply referred to as structural unit ( (sometimes abbreviated as B)), and the structural unit (A) is formula (A1):

[In formula (A1), Z is formula (z1):

(In formula (z1), R ^z11 to R ^z14 independently represent a monovalent hydrocarbon group that may have a hydrogen atom or a halogen atom, n represents an integer of 2 to 4, and * represents a bond. )

is a divalent organic group represented by , R ^a1 independently represents a halogen atom or an alkyl group, alkoxy group, aryl group or aryloxy group that may have a halogen atom, and s independently represents 0 to 3. represents an integer]

A structural unit (A1) derived from tetracarboxylic acid anhydride represented by (sometimes simply referred to as structural unit (A1), or sometimes referred to as structural unit (A1) derived from an ester bond-containing tetracarboxylic acid anhydride), and the formula: (A2):

[In formula (A2), R ^a2 independently represents a halogen atom or an alkyl group, alkoxy group, aryl group, or aryloxy group that may have a halogen atom, and k independently represents an integer of 0 to 2. indicates]

Contains a structural unit (A2) derived from tetracarboxylic acid anhydride represented by (sometimes simply referred to as structural unit (A2) or sometimes referred to as structural unit (A2) derived from a benzene skeleton-containing tetracarboxylic acid anhydride). , the diamine-derived structural unit (B) includes a biphenyl skeleton-containing diamine-derived structural unit (B1).

In this specification, polyimide is sometimes abbreviated as PI. In the present invention, “derived structural unit” means “derived structural unit,” for example, “tetracarboxylic anhydride-derived structural unit (A)” means “tetracarboxylic anhydride-derived structural unit ( A)”.

The present inventor proposes that in the PI-based resin, as the structural unit (A), a structural unit (A1) derived from a specific ester bond-containing tetracarboxylic anhydride and a structural unit derived from a specific benzene skeleton-containing tetracarboxylic anhydride ( A2), and further included as the structural unit (B) a structural unit (B1) derived from a specific biphenyl skeleton-containing diamine, it was found that a PI-based film with reduced Df could be obtained. It is presumed that this is because when the structural unit (A1), the structural unit (A2), and the structural unit (B1) are combined, a higher-order structure in which molecular rotation of the PI-based resin is suppressed is likely to be formed.

In addition, the PI-based resin of the present invention can improve the thermal physical properties of the resulting PI-based film and, for example, can reduce the coefficient of linear thermal expansion (hereinafter sometimes referred to as CTE). In this specification, thermophysical properties mean physical properties including CTE, glass transition temperature (sometimes referred to as Tg), degree of denaturation or deterioration due to heat, etc., and improving thermal physical properties means, for example, , CTE is lowered, Tg is higher, and/or denaturation or deterioration due to heat is less.

Furthermore, the present inventor found that, unexpectedly, in a PI-based resin, when the above-mentioned structural unit (A1), structural unit (A2), and structural unit (B1) are combined, the shape retention (or shape retention property) of the resulting PI-based film is improved. ) was found to be able to improve. In this specification, shape retention (or shape retention characteristic) refers to the property of maintaining the changed shape when the shape of the film is changed by an external force.

In this specification, mechanical properties mean mechanical properties including bending resistance, bending resistance, and elastic modulus, and improving mechanical properties means, for example, bending resistance and/or elastic modulus. It indicates rising. Dielectric properties mean properties related to dielectric properties such as Df and Dk, and increasing or improving dielectric properties means that Df and/or Dk are reduced. Additionally, in this specification, the upper and lower limits in the numerical range can be arbitrarily combined.

[polyimide-based resin]

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

<Constitutive unit derived from tetracarboxylic anhydride (A)>

The PI-based resin of the present invention is a structural unit (A) derived from tetracarboxylic anhydride, and includes a structural unit (A1) and a structural unit (A2).

(Constitutive unit (A1))

In the PI-based resin of the present invention, the structural unit (A) derived from tetracarboxylic anhydride is,

Equation (A1):

[In formula (A1), Z is formula (z1):

(In formula (z1), R ^z11 to R ^z14 independently represent a monovalent hydrocarbon group that may have a hydrogen atom or a halogen atom, n represents an integer of 2 to 4, and * represents a bond. )

is a divalent organic group represented by , R ^a1 independently represents a halogen atom or an alkyl group, alkoxy group, aryl group or aryloxy group that may have a halogen atom, and s independently represents 0 to 3. represents an integer]

It includes a structural unit (A1) derived from tetracarboxylic anhydride represented by .

When the structural unit (A) contains the structural unit (A1), an ester bond having molecular orientation is included in the PI-based resin, making it easier for the PI-based resin to orient, and thus Df of the resulting PI-based film can be reduced. I think so. Additionally, CTE can be reduced and the dimensional stability of the PI-based film can be increased. Moreover, even if the imidization temperature is low, for example, 350°C or lower, the Df of the resulting PI-based film can be lowered. Therefore, by using the PI-based resin of the present invention, imidization at low temperature becomes possible, and even if the CCL is manufactured by thermal imidizing the PI-based resin precursor coating film in a laminated configuration with copper foil, deterioration of the copper foil surface is suppressed. It is easy to do, and CCL with excellent high-frequency characteristics can be obtained. Furthermore, a PI-based film with high shape retention can be obtained.

R ^a1 in the formula (A1) independently represents a halogen atom or an alkyl group, alkoxy group, aryl group, or aryloxy group that may have a halogen atom, from the viewpoint of reducing Df of the resulting PI-based film. , from the viewpoint of reducing CTE and improving shape retention, preferably, independently of each other, an alkyl group with 1 to 6 carbon atoms, an alkoxy group with 1 to 6 carbon atoms, or an aryl group with 6 to 12 carbon atoms.

Examples of alkyl groups having 1 to 6 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, 2- Examples include methyl-butyl group, 3-methyl-butyl group, 2-ethyl-propyl group, and n-hexyl group.

Examples of the alkoxy group having 1 to 6 carbon atoms include methoxy group, ethoxy group, propyloxy group, isopropyloxy group, n-butoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group, pentyloxy group, Hexyloxy group, cyclohexyloxy group, etc. are mentioned.

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

The hydrogen atoms contained in R ^a1 may be independently substituted with a halogen atom, and examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

Among these, from the viewpoint of reducing Df of the PI-based film, reducing CTE, and improving shape retention, R ^a1 may be independently selected from the group, preferably an alkyl group having 1 to 6 carbon atoms, and more. Preferably, an alkyl group having 1 to 3 carbon atoms is used.

In addition, s in the formula (A1) independently represents an integer of 0 to 3, preferably 0 or 1, and more preferably 0.

Z in equation (A1) is expressed in equation (z1):

(In formula (z1), R ^z11 to R ^z14 independently represent a monovalent hydrocarbon group that may have a hydrogen atom or a halogen atom, n represents an integer of 2 to 4, and * represents a bond. )

It is a divalent organic group represented by .

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

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

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

Examples of aliphatic hydrocarbon groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, 2-methyl-butyl group, and 3- Alkyl groups such as methyl-butyl group, 2-ethyl-propyl group, n-hexyl group, n-heptyl group, n-octyl group, tert-octyl group, n-nonyl group, and n-decyl group can be mentioned.

R ^z11 to R ^z14 are independently of each other, preferably an alkyl group which may have a hydrogen atom or a halogen atom, from the viewpoint of reducing Df of the PI-based film, reducing CTE, and improving shape retention, More preferably, it represents an alkyl group of 1 to 6 carbon atoms which may have a hydrogen atom or a halogen atom, more preferably an alkyl group of 1 to 3 carbon atoms which may have a hydrogen atom or a halogen atom, and particularly preferably a hydrogen atom. .

In one embodiment of the present invention, from the viewpoint of reducing Df of the PI-based film, reducing CTE, and improving shape retention, the benzene ring having R ^z11 to R ^z14 in the formula (z1) In this case, at least one of R ^z11 to R ^z14 may be a monovalent hydrocarbon group that may have a halogen atom, but it is preferable that all of R ^z11 to R ^z14 are hydrogen atoms.

In the formula (z1), n represents an integer of 2 to 4, and from the viewpoint of reducing Df of the PI-based film, reducing CTE, and improving shape retention, it is preferably 2 or 3, more preferably Hage represents 2.

In one preferred embodiment of the present invention, formula (A1) is expressed as formula (A1'):

It is preferred to be expressed as . If the PI-based resin contains a structural unit derived from tetracarboxylic acid anhydride represented by formula (A1') as the structural unit (A1), Df of the obtained PI-based film can be reduced, and CTE can also be reduced. It is easy and can also improve shape maintenance. In addition, even if the imidization temperature is low, for example, 350°C or lower, the Df of the obtained PI-based film can be lowered, so even if the CCL is manufactured by thermal imidizing the PI-based resin precursor coating film in a laminated configuration with copper foil. , it is easy to suppress deterioration of the copper foil surface, and CCL with excellent high-frequency characteristics can be obtained.

In one embodiment of the present invention, the content of structural unit (A1) is preferably 15 mol% or more, more preferably 20 mol% or more, and still more preferably 30 mol% or more, based on the total amount of structural unit (A). It may be mol% or more, for example, 35 mol% or more, or 40 mol% or more. If the content of the structural unit (A1) is more than the above lower limit, it is easy to reduce the Df and CTE of the resulting PI-based film and improve the shape retention. Moreover, the content of the structural unit (A1) is preferably 75 mol% or less, more preferably 70 mol% or less, further preferably 65 mol% or less, even more preferably, with respect to the total amount of structural unit (A). Preferably it is 60 mol% or less, particularly preferably 55 mol% or less. If the content of the structural unit (A1) is below the above upper limit, it is easy to reduce Df of the resulting PI-based film, easy to reduce CTE, and easy to improve shape retention. In addition, in this specification, the ratio of each structural unit can be measured using, for example, ¹ H-NMR, or can be calculated from the introduction ratio of the raw materials.

(Constitutive unit (A2))

In the PI-based resin of the present invention, the structural unit (A) derived from tetracarboxylic anhydride has the formula (A2):

[In formula (A2), R ^a2 independently represents a halogen atom or an alkyl group, alkoxy group, aryl group, or aryloxy group that may have a halogen atom, and k independently represents an integer of 0 to 2. indicates]

It includes a structural unit (A2) derived from tetracarboxylic anhydride represented by . When the structural unit (A) contains the structural unit (A2), Df of the resulting PI-based film can be reduced. In addition, it is easy to reduce CTE and improve the dimensional stability of the PI-based film. In addition, even if the imidization temperature is low, for example, 350°C or lower, the Df of the resulting PI-based film can be lowered, so even if the CCL is manufactured by thermal imidizing the PI-based resin precursor coating film in a laminated configuration with copper foil. , it is easy to suppress deterioration of the copper foil surface, and CCL with excellent high-frequency characteristics can be obtained. Furthermore, a PI-based film with high shape retention can be obtained.

R ^a2 in the formula (A2) independently represents a halogen atom or an alkyl group, alkoxy group, aryl group, or aryloxy group that may have a halogen atom, and from the viewpoint of reducing the Df of the resulting PI-based film, From the viewpoint of reducing CTE and increasing shape retention and bending resistance, preferably, an alkyl group with 1 to 6 carbon atoms, an alkoxy group with 1 to 6 carbon atoms, or an aryl group with 6 to 12 carbon atoms are represented independently of each other. 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 with a halogen atom, and examples of the halogen atom include those exemplified above. Among these, from the viewpoint of reducing Df of the obtained PI-based film, reducing CTE, and improving shape retention and bending resistance, R ^a2 is preferably, independently of each other, an alkyl group having 1 to 6 carbon atoms, and Alkyl groups of 1 to 3 are more preferable.

The bonding position of the two carboxylic anhydrides bonded to the benzene ring in formula (A2) is not particularly limited, but is from the viewpoint of reducing Df of the resulting PI-based film, reducing CTE, and further improving shape retention and bending resistance. From the viewpoint of height, it is preferable that it is at the 1,2-position and the 4,5-position, or at the 1,2-position and the 3,4-position, and more preferably at the 1,2-position and the 4,5-position. . k independently represents an integer of 0 to 2, and is preferably 0 or 1, more preferably 0 or 1, from the viewpoint of further reducing Df of the resulting PI-based film, reducing CTE, and improving shape retention. It represents 0.

In one preferred embodiment of the present invention, formula (A2) is expressed as formula (A2'):

It is preferred to be expressed as . When the PI-based resin contains a structural unit derived from tetracarboxylic anhydride represented by the formula (A2') as the structural unit (A2), the Df of the PI-based film can be further reduced and the CTE is lower, A PI-based film with higher shape retention can also be obtained.

In one embodiment of the present invention, the content of structural unit (A2) is preferably 5 mol% or more, more preferably 15 mol% or more, and still more preferably 25 mol% or more, based on the total amount of structural unit (A). It is mol% or more, more preferably 30 mol% or more, particularly preferably 35 mol% or more, particularly more preferably 40 mol% or more, and even more preferably 45 mol% or more. If the content of the structural unit (A2) is more than the above lower limit, it is easy to reduce the Df of the PI-based film, it is easy to reduce the CTE, and it is easy to improve the shape retention. In addition, the content of the structural unit (A2) is preferably 85 mol% or less, more preferably 80 mol% or less, and still more preferably 70 mol% or less, based on the total amount of structural unit (A), for example For example, it may be 65 mol% or less, or 60 mol% or less. If the content of the structural unit (A2) is below the above upper limit, it is easy to reduce the Df of the PI-based film, it is easy to reduce the CTE, and it is easy to improve the shape retention.

(Constitutive unit (A3))

Constituent unit (A) is expressed in formula (A3):

[In formula (A3), R ^a3 independently represents a halogen atom or an alkyl group, alkoxy group, aryl group or aryloxy group which may have a halogen atom,

t represents an integer of 0 to 3, independently of each other]

It may further contain a structural unit (A3) derived from tetracarboxylic anhydride represented by (sometimes simply referred to as structural unit (A3)). When the structural unit (A) contains the structural unit (A3), the Df of the PI-based film can be further reduced and the bending resistance can be improved. In addition, even if the imidization temperature is low, for example, 350°C or lower, the Df of the obtained PI-based film can be lowered, so even if the CCL is manufactured by thermal imidizing the PI-based resin precursor coating film in a laminated configuration with copper foil, Deterioration of the copper foil surface can be easily suppressed, and CCL with excellent high-frequency characteristics can be obtained.

Examples of the halogen atom in R ^a3 in formula (A3), and the alkyl group, alkoxy group, aryl group, and aryloxy group that may have a halogen atom include the halogen atom in R ^a2 in formula (A2), and the halogen atom. The same alkyl group, alkoxy group, aryl group, and aryloxy group that may be included are included.

The bonding position of the two carboxylic anhydrides bonded to the benzene ring constituting the biphenyl skeleton in the formula (A3) is not particularly limited, and is independently 3 based on the single bond bonding the two benzene rings. , 4- or 2,3- may be used, and 3,4- is preferred from the viewpoint of reducing Df of the resulting PI-based film and improving bending resistance. t independently represents an integer of 0 to 3, and is preferably an integer of 0 to 2, more preferably 0 or 1, from the viewpoint of reducing Df of the resulting PI-based film and improving bending resistance. indicates.

In one preferred embodiment of the present invention, formula (A3) is expressed as formula (A3'):

It is preferred to be expressed as . When the PI-based resin contains a structural unit derived from tetracarboxylic anhydride represented by the formula (A3') as the structural unit (A3), the Df of the resulting PI-based film can be further reduced and the bending resistance is further improved. can do.

In one embodiment of the present invention, when the structural unit (A) includes the structural unit (A3), the content of the structural unit (A3) is preferably 1 mol% relative to the total amount of the structural unit (A). or more, more preferably 5 mol% or more, more preferably 10 mol% or more, even more preferably 20 mol% or more, particularly preferably 30 mol% or more, especially more preferably 40 mol% or more, Preferably it is 70 mol% or less, more preferably 60 mol% or less. If the content of the structural unit (A3) is within the above range, Df of the resulting PI-based film can be reduced and bending resistance can be improved.

(Constitutive unit (A4))

In one embodiment of the present invention, the structural unit (A) may contain a structural unit (A4) derived from tetracarboxylic anhydride other than structural units (A1) to (A3).

As the structural unit (A4), for example, equation (1):

[In equation (1), Y is in equations (31) to (38):

[In Formulas (31) to (38), R ¹⁹ to R ²⁶ and R ^23' to R ^26' are each independently a hydrogen atom, an alkyl group with 1 to 6 carbon atoms, an alkoxy group with 1 to 6 carbon atoms, or a carbon number. It represents an aryl group of 6 to 12, and the hydrogen atoms contained in R ¹⁹ to R ²⁶ and R ^23' to R ^26' may be independently substituted with a halogen atom,

V ¹ and V ² are, independently of each other, a single bond (except when e+d=1), -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)

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

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

i represents an integer from 1 to 3,

* indicates a binding hand),

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

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

f1 represents an integer from 1 to 3, f2 represents an integer from 0 to 3,

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

* indicates a bonding hand]

Indicates the tetravalent organic group represented by]

A structural unit derived from tetracarboxylic anhydride represented by is included.

In formulas (31) to (33), R ¹⁹ to R ²⁶ and R ^23' to R ^26' are each independently a hydrogen atom, an alkyl group with 1 to 6 carbon atoms, an alkoxy group with 1 to 6 carbon atoms, or a carbon number. Represents an aryl group of 6 to 12.

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 ¹⁹ to R ²⁶ and R ^23' to R ^26' may be independently substituted with a halogen atom, and examples of the halogen atom include those exemplified above. Among these, from the viewpoint of improving the mechanical and thermal properties of the PI-based film, R ¹⁹ to R ²⁶ and R ^23' to R ^26' are preferably independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, A hydrogen atom or an alkyl group having 1 to 3 carbon atoms is more preferable, and a hydrogen atom is more preferable.

In formula (31), V ¹ and V ² are independently of each other a single bond (except when e+d=1), -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 ), and from the viewpoint of improving the mechanical and thermal properties of the PI-based film, preferably a single bond (except when e+d=1), -O-, -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ - or -CO-, more preferably a single bond (except when e+d=1), -O-, -C(CH ₃ ) ₂ It represents - or -C(CF ₃ ) ₂ -. R ^j represents a monovalent hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a hydrogen atom or a halogen atom. Monovalent hydrocarbon groups having 1 to 12 carbon atoms include, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, and n-pentyl group. , 2-methyl-butyl group, 3-methyl-butyl group, 2-ethyl-propyl group, n-hexyl group, n-heptyl group, n-octyl group, tert-octyl group, n-nonyl group and n-decyl group. real groups, etc. can be mentioned, and these may be substituted with a halogen atom. Halogen atoms include those similar to those mentioned above.

In equation (31), e and d independently represent an integer of 0 to 2 (however, e+d is not 0), and from the viewpoint of reducing the Df of the PI film, preferably 0 or 1. represents. Moreover, e+d preferably represents 1. Additionally, in Formula (31), when e is 0, it indicates that the two benzene rings are not bonded to V ¹ , and when d is 0, it indicates that the two benzene rings are not bonded to V ² .

In formulas (32) and (33), f1 represents an integer of 1 to 3, and preferably represents 1 or 2, and more preferably 1, from the viewpoint of reducing Df of the PI-based film. f2 represents an integer of 0 to 3, and preferably represents 0 or 1, and more preferably 0, from the viewpoint of reducing Df of the PI-based film.

In equation (33), g and h independently represent an integer of 0 to 4, and from the viewpoint of improving the mechanical and thermal properties of the PI-based film, preferably an integer of 0 to 2, more preferably Typically, it represents 0 or 1. Moreover, g+h preferably represents an integer of 0 to 2. In addition, when f2 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 each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Examples of alkyl groups having 1 to 6 carbon atoms include those exemplified above. Among these, from the viewpoint of improving the mechanical and thermal properties of the PI-based film, R ²⁷ to R ³⁰ independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and more preferably a hydrogen atom. represents.

In formula (a), D represents a single bond, -C(CH ₃ ) ₂ - or -C(CF ₃ ) ₂ . If D has such a structure, the mechanical and thermal properties of the PI-based film can be improved. i represents an integer of 1 to 3, and is preferably 1 or 2 from the viewpoint of improving the mechanical and thermal properties of the PI-based film. When i is 2 or more, a plurality of D and R ²⁷ to R ³⁰ are independent of each other and may be the same or different.

Among these, from the viewpoint of reducing Df of the obtained PI-based film, Y in formula (1) is preferably expressed in formula (42), formula (44) to formula (49), or formula (53):

A structural unit derived from tetracarboxylic acid anhydride represented by, more preferably, Y in formula (1) is derived from tetracarboxylic anhydride represented by formula (42), formula (46), formula (49), or formula (53). It is a constituent unit of In addition, * in the formula represents a bond.

In one embodiment of the present invention, a structural unit derived from tetracarboxylic anhydride that is the same as structural unit (A1) except that n in the above formula (A1) is changed from "an integer of 2 to 4" to "1". (X) (sometimes simply referred to as structural unit (X)) may be included as the structural unit (A4). The structural unit (X) is expressed by the formula (X'):

It is preferred to be expressed as .

In one embodiment of the present invention, the content of structural unit (A4) is preferably 30 mol% or less, more preferably 20 mol% or less, and still more preferably 10 mol% or less, based on the total amount of structural unit (A). It is mol% or less, more preferably 5 mol% or less, and preferably 0 mol% or more.

In one embodiment of the present invention, when the structural unit (A) includes the structural unit (A1) and the structural unit (A2), from the viewpoint of improving shape retention, (the structural unit (A1) and the structural unit (A2) The value of (total amount of)/(total amount of structural unit (A)) is preferably greater than 0.5, more preferably 0.6 or more, further preferably 0.8 or more, and even more preferably 1.0.

<Constitutive unit derived from diamine (B)>

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

(Constitutive unit derived from diamine containing biphenyl skeleton (B1))

The structural unit (B) includes a structural unit (B1) derived from a biphenyl skeleton-containing diamine. When the structural unit (B) contains the structural unit (B1), the Df of the resulting PI-based film can be reduced. In addition, it is easy to reduce the CTE of the obtained PI-based film and improve the dimensional stability. Additionally, if the structural unit (B1) is included as the structural unit (B) in addition to the structural units (A1) and (A2), the shape retention of the obtained PI-based film can be improved.

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 expressed by formula (b1) from the viewpoint of reducing Df of the obtained PI-based film, reducing CTE, and improving shape retention:

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

p represents an integer from 0 to 4]

It is preferable that it is structural unit (b1) derived from diamine represented by .

In formula (b1), R ^b1 independently represents a halogen atom or an alkyl group, alkoxy group, aryl group or aryloxy group which may have a halogen atom, preferably a halogen atom or an alkyl group which may have a halogen atom. an alkyl group, an alkoxy group, or an aryl group, more preferably a halogen atom, an alkyl group with 1 to 6 carbon atoms, an alkoxy group with 1 to 6 carbon atoms, 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 contained in R ^b1 may be independently substituted with a halogen atom, and examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. From the viewpoint of reducing Df of the resulting PI-based film, reducing CTE, and improving shape retention, R ^b1 is preferably, independently of each other, an alkyl group having 1 to 6 carbon atoms or a fluoroalkyl group having 1 to 6 carbon atoms. From the viewpoint of increasing adhesion to substrates such as metal foil, it is more preferable that it is an alkyl group with 1 to 6 carbon atoms that does not contain fluorine, more preferably an alkyl group with 1 to 3 carbon atoms that does not contain fluorine, and a methyl group. It is particularly preferable that

In formula (b1), p independently represents an integer of 0 to 4, and from the viewpoint of reducing Df of the resulting PI-based film, reducing CTE, and improving shape retention, preferably It is an integer of 0 to 2, more preferably 0 or 1.

In formula (b1), the -NH ₂ group bonded to each benzene ring is, respectively, ortho-position, meta-position, or para-position, or α-position, β-position, based on the single bond connecting each benzene ring. Alternatively, it may be bonded to any of the γ positions, and from the viewpoint of reducing Df of the resulting PI-based film, reducing CTE, and improving shape retention, it is preferably bound to the meta position or para position, or the β position, or the γ position. position, more preferably the para position, or the γ position.

In one preferred embodiment of the present invention, formula (b1) is expressed as formula (b1'):

It is preferred to be expressed as . If the PI-based resin contains a diamine-derived structural unit represented by formula (b1), especially formula (b1') as the structural unit (B1), it is easy to reduce Df of the resulting PI-based film and also reduce CTE. It is easy to do and easy to improve shape retention. In addition, even if the imidization temperature is low, for example, 350°C or lower, the Df of the resulting PI-based film can be lowered, so even if the CCL is manufactured by thermal imidizing the PI-based resin precursor coating film in a laminated configuration with copper foil. , it is easy to suppress deterioration of the copper foil surface, and CCL with excellent high-frequency characteristics can be obtained.

In one embodiment of the present invention, the content of structural unit (B1), preferably structural unit (b1), is preferably 10 mol% or more, more preferably 20 mol%, based on the total amount of structural unit (B). mol% or more, more preferably more than 30 mol%, even more preferably 35 mol% or more, particularly preferably 40 mol% or more, particularly more preferably 45 mol% or more, for example 50 mol%. % or more, 55 mol% or more, 60 mol% or more, or 65 mol% or more. In addition, the content of structural unit (B1), preferably structural unit (b1), is 100 mol% or less, preferably 95 mol% or less, for example, 90 mol% or less, relative to the total amount of structural unit (B). , may be 85 mol% or less, or 80 mol% or less. When the content of the structural unit (B1), preferably the structural unit (b1), is within the above range, it is easy to reduce Df of the resulting PI-based film, easy to reduce CTE, and easy to improve shape retention.

(Constitutive unit (B2))

In one embodiment of the present invention, the structural unit (B) is a diamine-derived structural unit (B2) (hereinafter simply referred to as structural unit), which has two or more aromatic rings and each aromatic ring is bonded through a divalent organic group. It is desirable to include the unit (sometimes simply referred to as unit (B2)). Examples of the divalent organic group in the structural unit (B2) include an alkylene group that may have a halogen atom, -O-, -COO-, -OOC-, -SO ₂ -, -S-, and -CO. - or -N(R ^c )-, etc. are mentioned, and R ^c represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom. Among these, the divalent organic group in structural unit (B2) is -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 )- are preferred.

The structural unit (B2) is a diamine-derived structural unit represented by the formula (b2) (sometimes simply referred to as structural unit (b2)), and a diamine-derived structural unit represented by the formula (b2') (simply referred to as structural unit (b2)). , a structural unit (sometimes abbreviated as structural unit (b2')), a structural unit derived from diamine represented by formula (2) (sometimes abbreviated as structural unit (2)), etc.

Equation (b2) is expressed as follows.

[In formula (b2), R ^b2 independently represents a halogen atom or an alkyl group, alkoxy group, aryl group or aryloxy group which may have a halogen atom, and the hydrogen atoms contained in R ^b2 independently represent , may be substituted by a halogen atom,

W are, independently of each other, -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 )-, and R ^c is a hydrogen atom or 1 to 12 carbon atoms that may be substituted with a halogen atom. represents a monovalent hydrocarbon group,

m represents 3 or 4,

q independently represents an integer from 0 to 4]

Formula (b2') is expressed as follows.

[In formula (b2'), R ^b2' independently represents a halogen atom or an alkyl group, alkoxy group, aryl group, or aryloxy group which may have a halogen atom, and the hydrogen atom contained in R ^b2' is: Independently of each other, they may be substituted by a halogen atom,

W' are, independently of each other, -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' )-, and R ^c' is a hydrogen atom or a carbon number that may be substituted by a halogen atom. Represents a monovalent hydrocarbon group of 1 to 12,

m' represents 1 or 2,

q' is independent of each other and represents an integer from 0 to 4]

Equation (2) is expressed as follows.

[In equation (2), X is equation (65):

(In formula (65), * represents a bonding hand) and represents a divalent organic group represented by

Among these, from the viewpoint of reducing Df of the obtained PI-based film, it is preferable that the structural unit (B2) is the structural unit (b2). Moreover, from the viewpoint of reducing Df of the obtained PI-based film, reducing CTE, and improving shape retention, it is preferable that the structural unit (B2) is a structural unit (b2').

In formulas (b2) and (b2'), R ^b2 and R ^b2' independently represent a halogen atom or an alkyl group, alkoxy group, aryl group, or aryloxy group that may have a halogen atom, and are preferred. Specifically, it represents a halogen atom, an alkyl group with 1 to 6 carbon atoms, an alkoxy group with 1 to 6 carbon atoms, 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 contained in R ^b2 and R ^b2' may each independently be substituted with a halogen atom, and examples of the halogen atom include those similar to the above. From the viewpoint of reducing the Df of the obtained PI-based film, reducing CTE, and improving shape retention, R ^b2 and R ^b2' are each independently an alkyl group having 1 to 6 carbon atoms or an alkyl group having 1 to 6 carbon atoms. It is preferable that it is a fluorinated alkyl group, and from the viewpoint of easy adhesion to a base material such as metal foil, it is more preferable that it is an alkyl group with 1 to 6 carbon atoms that does not contain fluorine, and an alkyl group with 1 to 3 carbon atoms that does not contain fluorine. It is more preferable, and a methyl group is especially preferable.

In formulas (b2) and (b2'), q and q' independently represent integers of 0 to 4, from the viewpoint of reducing the Df of the resulting PI-based film, reducing the CTE, and also reducing the shape. From the viewpoint of improving retention, it is preferably an integer of 0 to 2, and more preferably 0 or 1.

In formulas (b2) and (b2'), W and W' are independently of each other -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 )-, and the resulting PI system From the viewpoint of reducing the Df of the film, reducing CTE, and improving shape retention, preferably -O-, -CH ₂ -, -C(CH ₃ ) _2- , -C(CF ₃ ) ₂ -, -COO-, -OOC- or -CO-, and from the viewpoint of easy adhesion to substrates such as metal foil, more preferably -O-, -CH ₂ - or -C(CH ₃ ) ₂ -, more preferably -O- or -C(CH ₃ ) ₂ -. R ^c and R ^c' independently represent a monovalent hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a hydrogen atom or a halogen atom. Examples of the monovalent hydrocarbon group having 1 to 12 carbon atoms include those exemplified above, and these may be substituted with a halogen atom. Halogen atoms include those similar to those mentioned above.

In formula (b2), -W- is, independently of each other, at the ortho position, meta position, or para position, or at the α position, β position, or γ position, respectively, based on -NH ₂ of each benzene ring. It may be bonded to any, but from the viewpoint of reducing Df of the resulting PI-based film, reducing CTE, and improving shape retention, it is preferably meta-position or para-position, or β-position or γ-position, More preferably, it may bind to the para position or the γ position. When m is 2 or more, in the benzene ring to which two Ws are bonded, the bonding positions of the two Ws are in the ortho position, meta position, or para position, or in the α position, β position, or γ position. It may be a relationship, and from the viewpoint of reducing Df of the resulting PI-based film, reducing CTE, and improving shape retention, it is preferably a relationship in the meta position or para position, or the β position or the γ position. It may be a relationship of . The position of -W'- in formula (b2') is also the same as the position of -W- in formula (b2) above.

In formula (b2), m is 3 or 4, and from the viewpoint of reducing Df of the resulting PI-based film, m is preferably 3.

In formula (b2'), m' is 1 or 2, and from the viewpoint of reducing Df of the resulting PI-based film, reducing CTE, and improving shape retention, m' is preferably 2. .

In formula (b2), a plurality of W, R ^b2 , and q may be the same or different from each other, and may be the position of -W- based on -NH ₂ of each benzene ring to which -NH ₂ is bonded, or two The bonding positions of the two Ws in each benzene ring to which W is bonded may be the same or different. In formula (b2'), when m' is 2 or more, a plurality of W', R ^b2' , and q' may be the same or different from each other. The position of -W'- in formula (b2') is the same as the position of -W- in formula (b2) above.

In one embodiment of the present invention, from the viewpoint of reducing Df of the PI-based film obtained, in formula (b2), m is 3, and W is independently -O- or -C(CH ₃ ) ₂ It is preferable to represent -, and formula (b2) is formula (b2-1):

It is more preferable to represent .

In one embodiment of the present invention, from the viewpoint of reducing Df of the obtained PI-based film, reducing CTE, and improving shape retention, in equation (b2), m is 2, and W is each other. Independently, it is preferred to represent -O-, and formula (b2) is represented by formula (b2-2) or formula (b2-3):

It is more preferable to represent . When the PI-based resin contains a structural unit (b2'), especially a diamine-derived structural unit represented by formula (b2-2) and/or formula (b2-3), the resulting PI-based film has a low CTE and a low It is compatible with Df and can also exhibit excellent adhesiveness with metal foil. In addition, even if the imidization temperature is low, for example, 350°C or lower, the Df of the obtained PI-based film can be lowered, so even if the CCL is manufactured by thermal imidizing the PI-based resin precursor coating film in a laminated configuration with copper foil. , it is easy to suppress deterioration of the copper foil surface, and CCL with excellent high-frequency characteristics can be obtained. Additionally, the shape retention of the PI-based film can be improved.

In one embodiment of the present invention, the content of structural unit (b2) is preferably 0 mol% or more than 0 mol%, for example, 1 mol% or more, relative to the total amount of structural unit (B). It may be 5 mol% or more or 8 mol% or more. The content of structural unit (b2) is preferably 40 mol% or less, more preferably 30 mol% or less, further preferably 20 mol% or less, even more preferably, relative to the total amount of structural unit (B). It is less than 20 mol%. If the content of the structural unit (b2) is more than the above lower limit, Df of the PI-based film can be reduced. If the content of the structural unit (b2) is below the above upper limit, the CTE of the PI-based film can be reduced.

In one embodiment of the present invention, the content of structural unit (b2) is preferably less than 20 mol% relative to the total amount of structural unit (B). If the content of the structural unit (b2) is within the above range, the CTE of the obtained PI-based film can be further reduced and the shape retention can be improved. The upper limit of the content of the structural unit (b2) is preferably 15 mol% or less, more preferably 10 mol% or less, further preferably 5 mol% or less, and even more preferably 1 mol% or less. If the content of the structural unit (b2) is below the above upper limit, the CTE of the resulting PI-based film can be prevented from becoming too small, and peeling can be prevented when laminated with a metal layer. Additionally, shape retention can be improved.

In one embodiment of the present invention, the content of the structural unit (b2') may be 0 mol% or more than 0 mol%, preferably 5 mol% or more, more preferably 5 mol% or more, relative to the total amount of structural unit (B). Preferably it is 10 mol% or more, more preferably 15 mol% or more, particularly preferably 20 mol% or more, especially more preferably 25 mol% or more, preferably 70 mol% or less, more preferably 65 mol% or more. It is mol% or less, more preferably 60 mol% or less, even more preferably 55 mol% or less, for example, it may be 50 mol% or less, 45 mol% or less, or 40 mol% or less. If the content of the structural unit (b2') is within the above range, it is easy to reduce the Df of the resulting PI-based film, it is easy to adjust the CTE to a range suitable for CCL, and the shape retention is easy to improve.

(Constitutive unit (B3))

The PI-based resin may contain diamine-derived structural unit (B3) (hereinafter sometimes simply referred to as structural unit (B3)) other than structural unit (B1) and structural unit (B2). As the structural unit (B3), for example, a structural unit derived from diamine in which m in formula (b2) is 0, and X in formula (2) is represented by formulas (61) to (64):

[In formula (61), R ^b2 , W, m and q are independently of each other and the same as R ^b2 , W, m and q in formula (b2),

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 is 0 or more and represents an integer of (carbon number of ring A - 2) or less,

S1 and S2 independently represent integers from 0 to 20,

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

A structural unit derived from diamine represented by , etc. can be mentioned.

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 alkyl groups exemplified above. r in formula (62) is 0 or more and represents an integer equal to or less than “carbon number of ring A -2”. r is preferably 0 or more, and preferably 4 or less. S1 and S2 in formula (62) independently represent integers of 0 to 20. S1 and S2 are independently from each other, preferably 0 or more, more preferably 2 or more, and preferably 15 or less.

As a specific example of the structural unit (B3), Constituent units can be mentioned. In addition, in these formulas, * represents a bond.

Among these, it is preferable that X in formula (2) is a structural unit derived from diamine represented by formula (74), that is, a structural unit derived from p-phenylenediamine.

In one embodiment of the present invention, when the structural unit (B) includes the structural unit (B3), the content of the structural unit (B3) is preferably 25 mol% relative to the total amount of the structural unit (B). Below, more preferably 20 mol% or less, further preferably 10 mol% or less, and preferably 0.01 mol% or more.

In one embodiment of the present invention, when the structural unit (B) includes structural units (B1) and (b2'), from the viewpoint of improving shape retention, (structural unit (B1) and (b2') The value of (total amount of)/(total amount of structural unit (B)) is preferably greater than 0.8, more preferably greater than or equal to 0.85, further preferably greater than or equal to 0.90, and even more preferably 1.0.

In one embodiment of the present invention, the PI-based resin may contain a halogen atom, preferably a fluorine atom, which can be introduced by, for example, the halogen-containing atom substituent described above. When the PI-based resin contains a fluorine atom, it is easy to reduce the relative dielectric constant of the resulting PI-based film. Preferred fluorine-containing substituents for making the PI-based resin contain a fluorine atom include, for example, a fluoro group and a trifluoromethyl group.

Moreover, in another embodiment of the present invention, it is preferable that the PI-based resin does not contain a fluorine atom from the viewpoint of improving the adhesiveness of the resulting PI-based film with a base material such as metal foil. In addition, if the PI-based resin contains fluorine, it tends to weaken the interaction between molecular chains, and if it does not contain a fluorine atom, the PI-based resin tends to take on a higher-order structure in which molecular rotation is suppressed. As a result, the Df of the PI-based film of the present invention tends to be easily reduced and the bending resistance tends to be improved.

In one embodiment of the present invention, the content of halogen atoms in the PI-based resin is preferably 35% by mass or less, more preferably 25% by mass or less, more preferably 25% by mass or less, based on the mass of the PI-based resin. It is 15 mass% or less, more preferably 5 mass% or less, particularly preferably 1 mass% or less, and usually 0 mass% or more. If the halogen atom content is below the above upper limit, it is advantageous in terms of cost, it is easy to reduce the CTE of the PI-based film, and it is easy to increase the adhesion of the PI-based film to a base material such as metal foil.

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, further preferably 95% or more, and usually 100% or less. From the viewpoint of improving mechanical properties, thermal properties and dielectric properties, it is preferable that the imidization rate is more than the above lower limit. The imidization rate represents the ratio of the molar amount of the imide bond in the PI-based resin to twice the molar amount of the structural unit derived from the tetracarboxylic acid compound in the PI-based resin. In addition, when the PI-based resin contains a tricarboxylic acid compound, the molar amount of the structural unit derived from the tricarboxylic acid compound is twice the molar amount of the structural unit derived from the tetracarboxylic acid compound in the PI-based resin, and It represents the ratio of the molar amount of the imide bond in the PI-based resin to the total. Additionally, the imidization rate can be determined by IR method, NMR method, etc.

In one embodiment of the present invention, the weight average molecular weight of the PI-based resin in terms of polystyrene (hereinafter, the weight average molecular weight may be described as Mw) is preferably 100,000 or more, more preferably 110,000 or more. Preferably it is 120,000 or more, particularly preferably 130,000 or more, preferably 1,000,000 or less, more preferably 700,000 or less, further preferably 500,000 or less, especially preferably 300,000 or less. If Mw is more than the above lower limit, mechanical properties such as bending resistance are likely to be improved. If Mw is below the above upper limit, it is advantageous from the viewpoint of processability during film forming. In addition, Mw can be determined by measuring gel permeation chromatography (hereinafter sometimes referred to as GPC) and converting it to standard polystyrene.

In one embodiment of the present invention, the Tg of the PI-based resin is preferably 350°C or lower, more preferably 330°C or lower, from the viewpoint of reducing Df of the resulting PI-based film or improving bending resistance. , more preferably 310°C or lower, even more preferably 295°C or lower, particularly preferably 290°C or lower, particularly more preferably 290°C or lower, particularly more preferably 288°C or lower. Moreover, the Tg of the PI-based resin is preferably 200°C or higher, more preferably 205°C or higher, and even more preferably 210°C or higher from the viewpoint of easily increasing the heat resistance of the PI-based film. The Tg of the PI-based resin can be measured by dynamic viscoelasticity measurement, for example, by the method described in the Examples.

In one embodiment of the present invention, when the Tg of the PI-based resin is within the above range, preferably 200 to 290° C., the PI-based resin tends to form a desirable higher-order structure in which rotational movement is suppressed. It is assumed that the rotation of the polar group in the PI-based resin is suppressed, and the loss of electrical energy as thermal movement is reduced. Therefore, it is believed that a PI-based film with a low Df can be obtained by using a PI-based resin whose Tg is within the above range. By using such a PI-based resin, the Df of the resulting PI-based film can be lowered even if the imidization temperature is low, for example, 350°C or lower. Therefore, even if the CCL is manufactured by thermal imidizing the PI-based resin precursor coating film in a laminated configuration with copper foil, deterioration of the copper foil surface can be suppressed, and CCL with excellent high-frequency characteristics can be obtained.

The Tg of the PI-based resin can be adjusted by appropriately adjusting the types of structural units constituting the PI-based resin and their composition, and the molecular weight and production method of the PI-based resin, especially imidization conditions, etc., for example, as described above. It can be adjusted within the above range by adjusting within the range described as a preferred mode in the description.

[Method for producing polyimide resin]

The PI-based resin of the present invention is not particularly limited, but is manufactured by a method comprising the step of reacting tetracarboxylic anhydride and diamine to obtain a PI-based resin precursor, and the step of imidizing the obtained PI-based resin precursor. It is desirable. Additionally, in addition to tetracarboxylic acid compounds, dicarboxylic acid compounds and tricarboxylic acid compounds may be reacted.

Examples of the tetracarboxylic acid anhydride used in the synthesis of the PI-based resin precursor include aromatic tetracarboxylic acid compounds such as aromatic tetracarboxylic dianhydride; and aliphatic tetracarboxylic acid compounds such as aliphatic tetracarboxylic dianhydride. The tetracarboxylic acid compound may be used individually, or may be used in combination of two or more types. The tetracarboxylic acid compound may be a tetracarboxylic acid compound analog such as an acid chloride compound in addition to a dianhydride.

Examples of the tetracarboxylic acid compound include tetracarboxylic anhydride represented by formula (A1), tetracarboxylic anhydride represented by formula (A2), and tetracarboxylic acid anhydride represented by formula (A3).

Specific examples of tetracarboxylic acid compounds include pyromellitic anhydride (hereinafter sometimes referred to as PMDA) and 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride (hereinafter referred to as BPADA). 1,4,5,8-naphthalenetetracarboxylic 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 anhydride (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-phenylenebis(trimellitic acid monoester dianhydride) (hereinafter referred to as TAHQ) ), esterified product 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'-diphenyl ethertetracarboxylic 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-dicarboxy) Phenyl)methane dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, 1,2,7,8- , 1,2,6,7-phenanthrene-tetracarboxylic dianhydride, 1,2,9,10-phenanthrene-tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)tetra Fluoropropane dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride (hereinafter sometimes referred to as HPMDA), 2,3,5,6-cyclohexanetetracarboxylic dianhydride, 2 ,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, 4,4' -Bis(2,3-dicarboxyphenoxy)diphenylmethane dianhydride, 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride (hereinafter sometimes referred to as CBDA), norbornane-2 -Spiro-α'-Spiro-2"-norbornane-5,5',6,6'-tetracarboxylic anhydride, p-phenylenebis(trimellitate anhydride), 3,3',4,4 '-Diphenylsulfonetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1, 2,5,6-Tetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic acid 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-perylene-tetracarboxylic dianhydride, 3,4,9,10-perylene-tetracarboxylic dianhydride, 4,5,10,11- Perylene-tetracarboxylic dianhydride, 5,6,11,12-perylene-tetracarboxylic 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. can be mentioned. Among these, BPDA, PMDA, TAHQ, and BP-TME are preferable, and PMDA and BP-TME are preferable from the viewpoint of reducing Df of the obtained PI-based film, reducing CTE, and improving shape retention and bending resistance. It is more desirable. These tetracarboxylic acid compounds can be used individually or in combination of two or more types.

Examples of diamine compounds used in the synthesis of PI-based resin precursors include aliphatic diamine, aromatic diamine, and mixtures thereof. In addition, in this embodiment, “aromatic diamine” refers to a diamine having an aromatic ring, and a part of its structure may contain an aliphatic group or other substituent. This aromatic ring may be a single ring or a condensed ring, and examples include, but are not limited to, a benzene ring, a naphthalene ring, an anthracene ring, and a fluorene ring. Among these, a benzene ring is preferable. In addition, “aliphatic diamine” refers to a diamine having an aliphatic group, and may contain other substituents in part of its structure, but does not have an aromatic ring.

Examples of the diamine compound include diamine represented by formula (b1), diamine represented by formula (b2), diamine represented by formula (b2'), and diamine represented by formula (2).

Specific examples of diamine compounds include 1,4-diaminocyclohexane, 4,4'-diamino-2,2'-dimethylbiphenyl (hereinafter sometimes referred to as m-TB), and 4,4'-dia. Mino-3,3'-dimethylbiphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl (hereinafter sometimes referred to as TFMB), 4,4'- Diaminodiphenyl ether, 1,3-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene (hereinafter sometimes referred to as TPE-Q), 1,3 -Bis(4-aminophenoxy)benzene (hereinafter sometimes referred to as TPE-R), 2,2-bis[4-(4-aminophenoxy)phenyl]propane (hereinafter sometimes referred to as BAPP) There is), 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)phenyl]hexafluoropropane, 2,2-bis-[4-(3-aminophenoxy)phenyl] Hexafluoropropane, 4,4'-methylenedi-o-toluidine, 4,4'-methylenedi-2,6-xylidine, 4,4'-methylene-2,6-diethylaniline, 4, 4'-methylenedianiline, 3,3'-methylenedianiline, 4,4'-diaminodiphenylpropane, 3,3'-diaminodiphenylpropane, 4,4'-diaminodiphenylethane, 3 ,3'-diaminodiphenylethane, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3,3-diaminodiphenyl ether, 3,4'-diaminodi Phenyl ether, benzidine, 3,3'-diaminobiphenyl, 3,3'-dimethoxybenzidine, 4,4"-diamino-p-terphenyl, 3,3"-diamino-p-terphenyl, m-phenylenediamine, p-phenylenediamine (hereinafter sometimes referred to as p-PDA), resorcinol-bis(3-aminophenyl)ether, 4,4'-[1,4-phenylene Bis(1-methylethylidene)]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-diaminotoluene, m-xylylene-2,5-diamine, p-xylylene-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-amino Phenoxy) biphenyl, 4,4'-(hexafluoropropylidene) dianiline, 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-di Aminopentane, 1,6-diaminohexane, 1,2-diaminopropane, 1,2-diaminobutane, 1,3-diaminobutane, 2-methyl-1,2-diaminopropane, 2-methyl -1,3-diaminopropane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, norbornanediamine, 2'-methoxy-4,4'-dia Minobenzanilide, 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'-diaminodiphenyl sulfide, 3,3'- Diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 2,5-diamino-1,3,4-oxadiazole, bis[4,4 '-(4-aminophenoxy)]benzanilide, bis[4,4'-(3-aminophenoxy)]benzanilide, 2,6-diaminopyridine, 2,5-diaminopyridine, etc. there is. Among these, m-TB, BAPP, TPE-Q, and TPE-R are preferable from the viewpoint of reducing Df of the resulting PI-based film, reducing CTE, and improving shape retention and bending resistance, and m- TB, TPE-Q, and TPE-R are more preferred. Diamine compounds can be used individually or in combination of two or more types.

In addition, the PI-based resin precursor includes other tetracarboxylic acids and dicarboxylic acids in addition to the tetracarboxylic acid compounds used in the synthesis of the PI-based resin precursor, to the extent that the various physical properties of the resulting PI-based film are not impaired. and tricarboxylic acid and their anhydrides and derivatives may be further reacted.

Other tetracarboxylic acids include aqueous adducts of anhydrides of the above tetracarboxylic acid compounds.

Dicarboxylic acid compounds include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and their related acid chloride compounds and acid anhydrides, and two or more types may be used in combination. Specific examples include terephthalic acid; isophthalic acid; naphthalene dicarboxylic acid; 4,4'-biphenyldicarboxylic acid; 3,3'-biphenyldicarboxylic acid; A chain hydrocarbon dicarboxylic acid compound having 8 or less carbon atoms and two benzoic acids forming a single bond, -O-, -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -, or compounds linked by a phenylene group, and their acid chloride compounds.

Examples of tricarboxylic acid compounds include aromatic tricarboxylic acid, aliphatic tricarboxylic acid, and their related acid chloride compounds and acid anhydrides, and two or more types may be used in combination. Specific examples include anhydride of 1,2,4-benzenetricarboxylic acid; 2,3,6-naphthalenetricarboxylic acid-2,3-anhydride; Examples include compounds in which phthalic anhydride and benzoic acid are linked by a single bond, -O-, -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -, or a phenylene group. .

In the production of a PI-based resin precursor, the amount of diamine compound, tetracarboxylic acid compound, dicarboxylic acid compound, and tricarboxylic acid compound used can be appropriately selected depending on the ratio of each structural unit of the desired PI-based resin precursor.

In the present invention, the total number of moles of the diamine compound used per mole of the total amount of the tetracarboxylic acid compound is defined as the amine ratio. In a preferred embodiment of the present invention, the amine ratio is preferably 0.90 mol or more, and preferably 0.999 mol or less, based on 1 mol of the total amount of the tetracarboxylic acid compound. Moreover, in another embodiment, the amine ratio is preferably 1.001 mol or more, and preferably 1.10 mol or less, based on 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 or more and 0.999 mol or less, more preferably 0.95 mol or more and 0.997 mol or less, and still more preferably 0.97 mol or more and 0.995 mol or less. .

In one embodiment of the present invention, when the amine ratio is 1 or more, the amine ratio is preferably 1.001 mol or more and 1.10 mol or less, more preferably 1.002 mol or more and 1.05 mol or less, and still more preferably 1.003 mol or more and 1.03 mol or less. .

If the amine ratio is close to 1.0 mol, the molecular weight tends to increase rapidly during synthesis, and if the amine ratio is far from 1.0 mol, the molecular weight of the obtained PI-based resin tends to tend to decrease. When the molecular weight increases rapidly, it grows unevenly in the synthetic mass, 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, if the molecular weight is too low, mechanical properties tend to deteriorate.

The reaction temperature between the diamine compound and the tetracarboxylic acid compound is preferably 50°C or lower, more preferably 40°C or lower, and even more preferably 30°C or lower. If the reaction temperature is below the above upper limit, Df of the resulting PI-based film can be reduced, CTE can be easily reduced, and shape retention and bending resistance can be easily improved. Moreover, 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 even more preferably 15°C or higher. If the reaction temperature is equal to or higher than the above lower limit, the reaction rate tends to be increased and the polymerization time tends to be shortened.

The reaction time is not particularly limited, and may be, for example, about 0.5 to 72 hours, preferably 3 to 32 hours. If the reaction time is within the above range, Df of the resulting PI-based film can be reduced, CTE can be reduced, and shape retention and bending resistance can be improved.

The reaction between the diamine compound and the tetracarboxylic acid compound is preferably carried out in a solvent. The solvent is not particularly limited as long as it does not affect the reaction, and examples include water, methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, and 1-methoxy- Alcohol-based solvents such as 2-propanol, 2-butoxyethanol, and propylene glycol monomethyl ether; Phenol-based solvents such as phenol and cresol; Ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether 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; Ketone-based solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, and methyl isobutyl ketone; Aliphatic hydrocarbon solvents such as pentane, hexane, and heptane; Alicyclic hydrocarbon solvents such as ethylcyclohexane; Aromatic hydrocarbon solvents such as toluene and xylene; Nitrile-based solvents such as acetonitrile; ether-based solvents such as tetrahydrofuran and dimethoxyethane; Chlorine-containing solvents such as chloroform and chlorobenzene; amide-based solvents such as N,N-dimethylacetamide (hereinafter sometimes referred to as DMAc) and N,N-dimethylformamide (hereinafter sometimes referred to as DMF); Sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide, and sulfolane; Carbonate-based solvents such as ethylene carbonate and propylene carbonate; Pyrrolidone-based solvents such as N-methylpyrrolidone (hereinafter sometimes referred to as NMP); and combinations thereof. Among these, from the viewpoint of solubility, phenol-based solvents, lactone-based solvents, amide-based solvents, and pyrrolidone-based solvents can be preferably used, and more preferably amide-based solvents.

In one embodiment of the present invention, the boiling point of the solvent used in the reaction between the diamine compound and the tetracarboxylic acid compound is adjusted from the viewpoint of reducing Df of the resulting PI-based film, reducing CTE, and further reducing shape retention and From the viewpoint of improving bending resistance, the temperature is preferably 230°C or lower, more preferably 200°C or lower, and 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, from the viewpoint of reducing Df of the resulting PI-based film, reducing CTE, and improving shape retention and bending resistance. That's it.

The reaction between the diamine compound and the tetracarboxylic acid compound may, if necessary, be carried out under conditions of reduced pressure or an inert atmosphere such as a nitrogen atmosphere or argon atmosphere. However, it is preferable to carry out the dehydration while stirring in a strictly controlled dehydration solvent.

The obtained PI-based resin precursor may be isolated once by a common method, but without isolation, the reaction liquid containing the PI-based resin precursor obtained by synthesis of the PI-based resin precursor may be used for the production of the PI-based resin. .

The PI-based resin is preferably produced by imidizing the PI-based resin precursor through heat treatment at 200°C or higher and 500°C or lower.

The imidization temperature in the present invention is preferably 500°C or lower, more preferably 400°C or lower, further preferably 350°C or lower, even more preferably 340°C or lower, particularly preferably 330°C or lower, In particular, it is more preferably 320°C or lower. Moreover, the imidization temperature is preferably 200°C or higher, more preferably 210°C or higher, and even more preferably 220°C or higher from the viewpoint of sufficiently improving the imidation rate or Df. In addition, the heating may be carried out in stages, for example, by heating at a relatively low temperature of 50 to 150°C to remove the solvent, and then heating at 200°C or higher and 500°C or lower, preferably 200°C or higher and lower than 400°C, more preferably. Imidization may be performed by heating in stages to a temperature in the range of 200°C or more and less than 350°C.

In one embodiment of the present invention, the reaction time for imidization is preferably 0.5 to 24 hours, more preferably 1 to 12 hours. Moreover, in one embodiment of the present invention, the time for maintaining the temperature of 200°C or higher is preferably 10 to 90 minutes, more preferably 15 to 80 minutes, and still more preferably 20 to 70 minutes. If the reaction time of 200°C or more for imidization is within the above range, the imidization rate can be sufficiently improved and oxidative deterioration of the resin can be prevented, and the dielectric properties and bending resistance of the resulting PI-based film can be improved. there is.

PI-based resin can be separated and purified by conventional methods, such as separation means such as filtration, concentration, extraction, crystallization, recrystallization, and column chromatography, or a combination of these. .

[Polyimide-based film]

The present invention includes a PI-based film containing the PI-based resin of the present invention. Since the PI-based film of the present invention contains the PI-based resin, it can have a low Df. Additionally, it may have a low CTE. In addition, the PI-based film of the present invention has excellent shape retention properties, and when the shape of the film is changed by an external force, it can effectively maintain the changed shape. Therefore, when the PI-based film of the present invention is used for FPC substrate materials, etc., shaking of the substrate in the FPC can be suppressed or prevented, and in addition, the loss of wiring due to returning stress or contact with other components can be suppressed or prevented.

Moreover, the PI-based resin of the present invention can form a PI-based film with low Df even if the imidization temperature is low. In a preferred embodiment of the present invention, the PI-based film of the present invention is obtained by heat-treating the PI-based resin precursor at 200°C or higher and 500°C or lower, preferably 200°C or higher and lower than 400°C, more preferably 200°C or higher and lower than 350°C. It includes PI-based resin obtained by imidizing.

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, with respect to the mass of the PI-based film of the present invention. Typically, it is 80 mass% or more, particularly preferably 90 mass% or more. Additionally, the upper limit of the content of the PI-based resin is not particularly limited, and may be, for example, 100% by mass or less, 99% by mass or less, or 95% by mass or less relative to the mass of the PI-based film. If the content of the PI-based resin is within the above range, mechanical properties, thermal properties and dielectric properties can be improved.

The PI-based film of the present invention may contain a filler as needed. Examples of the filler include metal oxide particles such as silica and alumina, inorganic salts such as calcium carbonate, and polymer particles such as fluororesin and cycloolefin polymer. Fillers can be used alone or in combination of two 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, based on the mass of the PI film. It is more than %.

Additionally, in one embodiment of the present invention, the PI-based film of the present invention may contain additives as needed. Additives include, for example, antioxidants, flame retardants, crosslinking agents, surfactants, compatibilizers, imidization catalysts, weathering agents, lubricants, antiblocking agents, antistatic agents, antifogging agents, Examples include anti-dropping agents and pigments. Additives can be used alone or in combination of two or more. The content of various additives can be appropriately selected within a range that does not impair the effect of the present invention, and when various additives are included, the total content is preferably 7% by mass or less, based on the mass of the PI-based film. Preferably it is 5 mass% or less, more preferably 4 mass% or less, and preferably 0.001 mass% or more. Additionally, the PI-based resin of the present invention may contain the above filler and the above additive.

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, even more preferably 30 ppm/K or less, even more preferably It is 25 ppm/K or less, especially preferably 20 ppm/K or less, and may be, for example, 18 ppm/K or less, 15 ppm/K or less, or 13 ppm/K or less. If the CTE of the PI-based film is below the above upper limit, it can have excellent dimensional stability. Moreover, the CTE of the PI-based film is preferably 0 ppm/K or more, more preferably 5 ppm/K or more, further preferably 8 ppm/K or more, even more preferably 10 ppm/K or more, especially Preferably it is 11 ppm/K or more, particularly more preferably 11.8 ppm/K or more. By setting the CTE of the PI-based film to the above range (more than the lower limit and less than the upper limit), the CTE of the copper foil and the PI layer become closer, so peeling of the laminated film can be suppressed. In addition, CTE can be measured, for example, by a thermomechanical analysis device (hereinafter sometimes referred to as “TMA”), and is obtained by the method described in the Examples.

Print circuits are required to have small transmission losses. Transmission loss is expressed as the sum of dielectric loss, which is the loss caused by the electric field generated in the dielectric, and conductor loss, which is the loss caused by the current flowing through the conductor. It is known that dielectric loss is approximately proportional to the index (E) expressed by equation (i).

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

In the high frequency range used in FPC for 5G, dielectric loss tends to increase, so materials that have a small value of the index (E) and can suppress dielectric loss are particularly required.

On the other hand, in high-frequency signals, current is concentrated on the very surface of the conductor. Therefore, it is known that conductor loss is approximately proportional to (Dk) ^1/2 , in relation to the dielectric properties of the dielectric in contact.

As described above, the PI-based film of the present invention containing the PI-based resin of the present invention contains Df, Since Dk becomes small, the index of dielectric loss (E) and conductor loss also become small, and transmission loss can be reduced in a circuit containing the PI-based film.

In one embodiment of the present invention, the dielectric loss index (E) of the PI-based film at 10 GHz is preferably less than 0.008, more preferably 0.0075 or less, further preferably 0.007 or less, even more preferably Typically, it is 0.0065 or less, particularly preferably 0.006 or less. The smaller the index E, the lower the transmission loss of the electronic circuit including the PI film. 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 0.004 or less, more preferably 0.0038, from the viewpoint of reducing the transmission loss of the electronic circuit including the PI-based film. or less, more preferably 0.0035 or less, even more preferably 0.0033 or less, particularly preferably 0.003 or less, for example, 0.0029 or less, 0.0027 or less, 0.0025 or less, or 0.0023 or less. The smaller the Df, the lower the transmission loss of the electronic circuit including the PI film. 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 at 10 GHz of the PI-based film is preferably 3.50 or less, more preferably 3.45 or less, further preferably 3.41 or less, for example, 3.38 or less, or 3.36. The following may be acceptable.

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.

In one embodiment of the present invention, the PI-based film of the present invention has excellent bending resistance, particularly bending resistance. The number of times the PI film of the present invention is bent to fracture in the MIT bending fatigue test based on ASTM standard D2176-16 is preferably 15,000 times or more, more preferably 20,000 times or more, and still more preferably 30,000 times. That's it. If the number of bending is more than the above lower limit, the occurrence of cracks, fissures, folds, etc. can be effectively suppressed even if the bending is repeated. Additionally, the upper limit of the number of times of bending is not particularly limited, and may be, for example, 10,000,000 times or less. Additionally, the MIT fracture fatigue test can be measured using an MIT fracture fatigue tester.

The thickness of the PI-based film of the present invention can be appropriately selected depending on the application, and is preferably 5 μm or more, more preferably 10 μm or more, further preferably 20 μm or more, and preferably 500 μm or less. It is preferably 300 μm or less, more preferably 100 μm or less, 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 gauge, etc. Additionally, when the film of the present invention is a multilayer film, the thickness represents the thickness of the single layer portion.

The PI-based film of the present invention may be subjected to surface treatment, such as corona discharge treatment, plasma treatment, or ozone treatment, by methods commonly employed industrially.

Since the PI-based film of the present invention has a low Df, it can be appropriately used as a substrate material that can be used for printed circuit boards or antenna substrates for high frequency bands. CCL used in FPC is a widely used laminate having a copper foil layer on one or both sides of a single- or multiple-layer PI-based resin. When using the PI-based film of the present invention as a resin layer, the PI-based film of the present invention can lower Df even if the imidization temperature is low, such as 350°C or lower, so a PI-based resin precursor coating film can be formed on copper foil. Even if the CCL is manufactured by thermal imidization, deterioration of the copper foil surface can be suppressed, and therefore CCL with excellent high-frequency characteristics can be obtained.

[Method for producing polyimide-based film]

The PI-based film of the present invention can be produced, for example, through the following processes:

A process of coating a PI-based resin precursor solution containing a PI-based resin precursor having a structural unit derived from tetracarboxylic anhydride and a structural unit derived from diamine onto a substrate, and

Process of imidizing the PI-based resin precursor by heat treatment at 200℃ or higher and 500℃ or lower.

It can be manufactured by a method comprising:

< Coating process of polyimide resin precursor solution >

(Preparation of PI-based resin precursor solution)

The PI-based resin precursor solution contains the PI-based resin precursor and a solvent, and can be prepared by mixing the PI-based resin precursor and the solvent. Additionally, in one embodiment of the present invention, a reaction solution containing a PI-based resin precursor obtained by synthesizing a PI-based resin precursor may be appropriately diluted with a solvent as needed and used as a PI-based resin precursor solution.

The solvent contained in the PI-based resin precursor solution includes those exemplified as solvents used in the reaction between a diamine compound and a tetracarboxylic acid compound in the production of a PI-based resin precursor, and is preferably a lactone-based solvent or an amide-based solvent. A solvent, a pyrrolidone-based solvent, more preferably an amide-based solvent. In addition, in one embodiment of the present invention, the boiling point of the solvent contained in the PI-based resin precursor solution is from the viewpoint of reducing the Df of the PI-based film, reducing the CTE, and reducing the shape even if the imidization temperature is low. From the viewpoint of improving retention, preferably 230°C or lower, more preferably 200°C or lower, further preferably 180°C or lower, particularly preferably 170°C or lower, preferably 100°C or higher, more preferably It is above 120℃.

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 still more preferably 12% by mass, based on the total amount of the PI-based resin precursor solution. or more, particularly preferably 13 mass% or more, and preferably 30 mass% or less, more preferably 25 mass% or less, further preferably 23 mass% or less, particularly preferably 20 mass% or less. If the content of the PI-based resin precursor is within the above range, the processability during film forming is excellent.

(Coating of polyimide resin precursor solution)

The coating process of the PI-based resin precursor solution is a process of coating the PI-based resin precursor solution onto a substrate to form a coating film.

In the coating process, the composition is applied onto the substrate using a known coating method or application method to form a coating film. Known coating methods include, for example, roll coating methods such as wire bar coating, reverse coating, and gravure coating, die coating, comma coating, lip coating, spin coating, screen printing coating, and fountain coating. Examples include dipping method, spray method, curtain coating method, slot coating method, and flexible method. When coating or applying a solution of a PI-based resin precursor onto a substrate, a single layer of PI-based resin precursor may be applied on the substrate, or multiple layers of PI-based resin precursor may be applied on the substrate. When coating multiple layers of PI-based resin precursor on a substrate, the coating may be divided into multiple layers and dried, or multiple layers may be applied simultaneously.

Examples of the substrate include metal plates such as metal foil, SUS plates such as SUS belts, glass substrates, PET films, PEN films, PI-based resin films other than the PI-based film of the present invention, polyamide-based resin films, etc. . Among them, from the viewpoint of excellent heat resistance, metal plates, SUS plates, glass substrates, PET films, PEN films, etc. are preferred, and from the viewpoint of adhesion to the film and cost, metal plates, SUS plates, etc. are more preferred. A glass substrate or PET film, etc. can be mentioned. In one embodiment of the present invention, examples of metals constituting the metal foil include aluminum, copper, iron, nickel, chromium, titanium, tantalum, stainless steel, and alloys thereof. Among these, the metal foil is preferably copper foil, copper alloy foil, SUS foil, aluminum foil, etc., and from the viewpoint of conductivity and metal workability, copper foil or copper alloy foil is more preferable, and copper foil is especially preferable.

<Imidization process>

The imidization process is a process of imidizing the PI-based resin precursor coated on the substrate by heat treatment at 200°C or higher and 500°C or lower.

In one embodiment of the present invention, in the imidization process, before imidizing the PI-based resin precursor, the PI-based resin precursor solution coated on the substrate is heated and dried at a relatively low temperature, for example, less than 300°C, and the obtained It is preferable that this is a process of imidizing the dried film of the PI-based resin precursor by heat treatment at 200°C or higher and 500°C or lower. By such stepwise drying, it is easy to reduce the Df of the obtained PI-based film.

Additionally, in one embodiment of the present invention, a PI-based film may be obtained by imidizing the dried film of the PI-based resin precursor on the substrate, and the dried film of the PI-based resin precursor is peeled from the substrate, and the dried film peeled from the substrate is A PI-based film may be obtained by imidization.

In one embodiment of the present invention, the drying temperature of the PI-based resin precursor coated on the substrate is not particularly limited as long as it is in the temperature range at which the solvent dries and solidifies, but rapid drying causes roughness on the surface of the PI-based film. From the viewpoint of avoiding wrinkles and suppressing wrinkles, wrinkles, etc. that occur during processing, the temperature is preferably less than 300°C, more preferably less than 260°C, more preferably less than 200°C, and even more preferably less than 180°C. And, from the viewpoint of productivity, it is preferably 50°C or higher, more preferably 80°C or higher, and even more preferably 100°C or higher. If the drying temperature is within the above range, it is easy to reduce Df of the resulting PI-based film.

Even if the PI-based resin precursor in the present invention is imidized at low temperature, Df of the obtained PI-based film can be reduced and shape retention can also be improved. The heat treatment temperature in the imidization process, that is, the imidization temperature, is preferably 500°C or lower, more preferably 400°C or lower, further preferably 350°C or lower, even more preferably 340°C or lower, especially preferably Preferably it is 330°C or lower, particularly more preferably 320°C or lower. If the imidization temperature is below the above upper limit, even when copper foil is used as a base material, thermal deterioration of the copper foil can be suppressed, so it is easy to obtain CCL with excellent high-frequency characteristics. Additionally, the imidization temperature is preferably 200°C or higher, more preferably 210°C or higher, and even more preferably 220°C or higher from the viewpoint of easily improving the imidation rate and reducing Df. Additionally, from the viewpoint of obtaining a smooth film or reducing Df, it is preferable to perform heating in stages. For example, after heating at a relatively low temperature of 50 to 150°C to remove the solvent, the temperature is in the range of 200°C to 500°C, preferably 200°C to 400°C, more preferably 200°C to 350°C. Imidization may be performed by heating in stages.

In one embodiment of the present invention, the reaction time for imidization is preferably 30 minutes to 24 hours, more preferably 1 to 12 hours. Moreover, in one embodiment of the present invention, the time for maintaining the temperature of 200°C or higher is preferably 5 minutes to 90 minutes, more preferably 10 minutes to 70 minutes, and still more preferably 15 minutes to 50 minutes. .

After imidization, a PI-based film can be obtained by peeling the coating film formed on the substrate from the substrate. In one embodiment of the present invention, when the base material is copper foil, a PI-based film is formed without peeling the coating film from the copper foil, and the resulting laminated film in which the PI-based film is laminated on the copper foil can be used as a CCL.

When the film of the present invention is a multilayer film, it can be manufactured by, for example, a multilayer film forming method such as co-extrusion processing, extrusion lamination, heat lamination, or dry lamination.

[Laminated film]

Since the PI-based film of the present invention has a low Df, it can be appropriately used for forming metal-clad laminates used in FPC. Therefore, the present invention includes 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. In one embodiment of the present invention, the laminated film of the present invention may include the metal foil layer on only one side of the PI layer or on both sides.

In one embodiment of the present invention, the metals constituting the metal foil layer include the metals described above. Among these, the metal foil layer is preferably a copper foil layer, a copper alloy foil layer, a SUS foil layer, or an aluminum foil layer, and is conductive. And from the viewpoint of metal workability, a copper foil layer or a copper alloy foil layer is more preferable, and a copper foil layer is particularly preferable.

The PI-based film of the present invention can be appropriately used for forming a metal-clad laminate (preferably CCL) with low Df and excellent high-frequency characteristics and, preferably, shape retention, even if the thermal imidization temperature is low. In a preferred embodiment of the invention, the laminated film of the present invention is preferably a laminated film including a metal foil layer on one or both sides 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, more preferably 5 μm or more, and the circuit can be easily refined and bending resistance can be easily improved. From the viewpoint, it is preferably 100 μm or less, more preferably 50 μm or less, further preferably 30 μm or less, and 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 the PI-based film includes metal foil layers, especially copper foil layers, on both sides, the thickness of each metal foil layer, especially each copper foil layer, may 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, further preferably 15 μm or more, preferably 100 μm or less, more preferably It is 80 ㎛ or less, more preferably 60 ㎛ or less. The thickness of the laminated film can be measured using a film thickness gauge or the like.

In addition to the PI-based film and the metal foil layer, especially the copper foil layer, the laminated film of the present invention may contain other layers such as a functional layer. Examples of the functional layer include a thermoplastic PI-based resin layer or adhesive layer containing a thermoplastic PI-based resin. The functional layer can be used alone or in combination of two or more types.

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

In addition, since the PI-based film of the present invention has a low Df even when the imidization temperature is low, even if a laminated film in which the metal foil is copper foil is manufactured by performing thermal imidization of the PI-based resin precursor coating film on the copper foil, deterioration of the copper foil surface is avoided. It can be suppressed. Therefore, the laminated film of the present invention has excellent high-frequency characteristics even if it does not contain an adhesive layer.

Additionally, in one embodiment of the present invention, the PI-based film of the present invention may be in direct contact with the metal foil layer, especially the copper foil layer, and a functional layer is inserted between the PI-based film and the metal foil layer, especially the copper foil layer. Although these may be in contact through a functional layer, from the viewpoint of improving mechanical and thermal properties, it is preferable that the PI-based film and the metal foil layer, especially the copper foil layer, are in direct contact.

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

[Method for manufacturing laminated film]

For example, the laminated film of the present invention can be prepared through the following processes:

A process of coating a PI-based resin precursor solution containing a PI-based resin precursor having a structural unit (A) derived from tetracarboxylic anhydride and a structural unit (B) derived from diamine, onto a substrate, and

A process of imidizing a PI-based resin precursor by heat treatment at 200°C or higher and 500°C or lower to form the PI-based film of the present invention on a substrate.

It can be manufactured by a method comprising:

In the method for producing a laminated film of the present invention, the PI-based resin precursor is prepared by heat treatment at 200°C or higher and 500°C or lower. Regarding the “process of imidizing and forming the PI-based film of the present invention on the substrate,” the description of each process described in the section of [Method for producing polyimide-based film] is similarly applicable.

In one embodiment of the present invention, the base material is preferably metal foil, and particularly preferably copper foil. Descriptions regarding metal foil, especially copper foil, are similarly applicable to descriptions regarding metal foil described in the section of [Laminated Film].

The laminated film of the present invention uses a method other than the above method, for example, the structural unit (A) derived from tetracarboxylic anhydride and the structural unit (B) derived from diamine are formed on a substrate other than the metal foil contained in the laminated film. A dried film of the PI-based resin precursor obtained by coating and drying a PI-based resin precursor solution containing the PI-based resin precursor is peeled from the substrate, and the peeled dried film of the PI-based resin precursor is bonded to a metal foil. It may be manufactured by the following method. As a method for bonding the dried film of the PI-based resin precursor and the metal foil, a method using a press, a laminating method using a hot roll, etc. may be employed, and in the bonding process, imidization of the PI-based resin precursor may be performed simultaneously. . However, the PI-based film of the present invention has a low Df even if the imidization temperature is low, so even if a laminated film in which the metal foil is copper foil is manufactured by, for example, thermal imidization of the PI-based resin precursor coating film on the copper foil, the copper foil surface Deterioration can be suppressed. Therefore, the laminated film of the present invention has excellent high-frequency characteristics even if it is manufactured without going through the above bonding process.

[Flexible printed circuit board]

Since the PI-based film of the present invention has a low Df, the transmission loss of an electric circuit made of the PI-based film can be reduced. Additionally, the PI-based film of the present invention has a low CTE and excellent shape retention properties, so it can be appropriately used as an FPC substrate material. Accordingly, the present invention also includes an FPC substrate containing the PI-based film of the present invention.

[Example]

Hereinafter, the present invention will be described in more detail based on examples and comparative examples, but the present invention is not limited to the following examples.

The abbreviations used in the examples and comparative examples represent the following compounds.

BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride

PMDA: pyromellitic anhydride

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

p-PDA: p-phenylenediamine

m-TB: 4,4'-diamino-2,2'-dimethylbiphenyl

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

TRE-R: 1,3-bis(4-aminophenoxy)benzene

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

[Synthesis of polyimide resin precursor]

(Example 1)

After dissolving 22.658 g (106.7 mmol) of m-TB and 4.868 g (11.9 mmol) of BAPP in 405.0 g of DMAc, 31.214 g (58.4 mmol) of BP-TME was added and stirred at 20°C for 1 hour under a nitrogen atmosphere. After that, 12.740 g (58.4 mmol) of PMDA was added and stirred at 20°C for 24 hours under a nitrogen atmosphere to obtain a PI-based resin precursor composition. The molar ratio (amine ratio) of the diamine monomer to the acid dianhydride monomer used was 1.02.

(Examples 2 to 7, Comparative Examples 1 and 2)

A PI-based resin precursor composition was obtained in the same manner as in Example 1, except that the type of monomer used and the monomer composition were changed as shown in Table 1, respectively.

[Manufacture of polyimide-based film]

Using the solvent used in the synthesis of the PI-based resin precursor, the PI-based resin precursor composition obtained in Examples 1 to 7 and Comparative Examples 1 and 2 was appropriately diluted to a range where the content of the PI-based resin precursor was 10% by mass or more. A PI-based resin precursor solution was prepared by adjusting the viscosity to 40,000 cps or less. The PI-based resin precursor solution was formed into a film under any of the following film forming conditions 1 to 3, as shown in Table 1, and a PI-based film made of PI-based resin was obtained.

<Unveiling condition 1>

The PI-based resin precursor solution was flexible molded on a glass substrate, and a coating film of the PI-based resin precursor solution was formed using an applicator at a line speed of 0.4 m/min. The coating film was heated at 120°C for 30 minutes, the obtained film was peeled from the glass substrate, and the film was fixed to a metal frame. The film fixed to the metal frame was heated from 30°C to 320°C over 10 minutes in an oxygen concentration atmosphere of 1%, and then held at 320°C for 5 minutes to obtain a PI-based film.

<Unveiling condition 2>

The PI-based resin precursor solution was flexible molded on the roughened surface side (surface roughness; Rz = 1.3 μm) of an electrolytic copper foil (JXEFL-BHM, manufactured by JX Metal Co., Ltd., thickness 12 μm), and an applicator was applied. Using this, a coating film of the PI-based resin precursor solution was formed at a line speed of 0.4 m/min. The coating film was dried by heating at 120°C for 30 minutes. Thereafter, the laminated film of the copper foil and the coating film was fixed to a metal frame, the temperature was raised from 30°C to 320°C over 10 minutes in an oxygen concentration atmosphere of 1%, and then heated at 320°C for 5 minutes. The obtained laminated film of PI-based film and copper foil was immersed in a large aqueous solution of ferric chloride with a concentration of 40% by mass for 10 minutes at room temperature, and after visually confirming that there was no copper remaining, it was dried at 80°C for 1 hour and dried alone. A PI-based film was obtained.

<Unveiling condition 3>

The PI-based resin precursor solution was flexible molded on the roughened surface side (surface roughness; Rz = 1.3 μm) of electrolytic copper foil (JXEFL-BHM, manufactured by JX Metal Co., Ltd., thickness 12 μm), using an applicator, and applied at a flux of 0.4. A coating film of the PI-based resin precursor solution was formed at m/min. The coating film was dried by heating at 90°C for 10 minutes. After that, the laminated film of copper foil and the coating film was fixed to a metal frame, the temperature was raised from 30°C to 320°C over 10 minutes in an oxygen concentration atmosphere of 1%, and then heated at 320°C for 5 minutes. The obtained laminated film of PI-based film and copper foil was immersed in a large aqueous solution of ferric chloride with a concentration of 40% by mass for 10 minutes at room temperature, and after visually confirming that there was no copper remaining, it was dried at 80°C for 1 hour and dried alone. A PI-based film was obtained.

Each measurement and evaluation was performed on the PI-based films obtained in Examples and Comparative Examples. The measurement and evaluation methods are described below.

<Measurement of glass transition temperature (Tg)>

The Tg of the PI-based resin obtained in the examples and comparative examples was determined by measuring the PI-based film as follows.

Using a dynamic viscoelasticity measurement device (DVA-220, manufactured by IT Instrumentation Control Co., Ltd.), storage modulus (E') and loss modulus (E") were measured under the following samples and conditions. A tanδ curve, which is the ratio of the values, was obtained. The highest point of the peak of the tanδ curve was designated as Tg.

Test piece: A rectangular parallelepiped with a length of 40 mm, a width of 5 mm, and a thickness of 30 ㎛ (the thickness varies depending on the film used).

Experimental mode: single frequency, constant rate heating

Test Format: Seal

Length between sample grips: 15 mm

Measurement start temperature: room temperature to 342°C

Temperature increase rate: 5℃/min

Frequency: 10 Hz

Static/dynamic stress ratio: 1.8

Main data collected:

(1) Storage modulus (E')

(2) Loss modulus (E")

(3) tanδ(E"/E')

<Measurement of Coefficient of Linear Thermal Expansion (CTE)>

The CTE of the PI-based film obtained in the examples and comparative examples was measured using TMA under the following conditions, and the CTE (ppm/K) from 50°C to 100°C was calculated.

Device: TMA/SS7100 manufactured by Hitachi High-Tech Science Co., Ltd.

Load: 50.0 mN

Temperature program: temperature increase 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 30 ㎛ (the thickness may vary depending on the film used).

<Evaluation of oil field loss index (E)>

The dielectric loss index (E) of the PI-based films obtained in Examples and Comparative Examples was calculated using the following formula.

Df: Dielectric loss tangent

Dk: relative permittivity

(Measurement of Df and Dk)

Df and Dk of the PI-based films obtained in Examples and Comparative Examples were measured under the following conditions. Measurements were performed after the samples were humidified at 25°C/55% RH for 24 hours.

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

Cavity resonator (TE mode 10 GHz type) made by AT Co., Ltd.

Measurement frequency: 10 GHz

Measurement atmosphere: 23℃/50% RH

<Evaluation of shape retention>

A film of 5 mm (width) x 40 mm (length) was cut from the PI-based film obtained in Examples and Comparative Examples. Tape is attached to both ends of the cut sample at a position 5 mm from each end, and the sample is twisted 360° in the width direction, and the gap between the opposing tape attachment positions is 25 mm. It was fixed at a position that was mm (i.e., the length of the unfixed film was 25 mm) and left at room temperature for 1 hour. After 1 hour, remove the tape on one side to release the fixation, measure the time for which the warped height (height of the highest part of the film edge) is maintained at 10 mm or more, and evaluate based on the following criteria. did.

AA: Hold for more than 5 minutes

A: Stay at least 2 minutes but less than 5 minutes.

B: Hold for more than 1 minute but less than 2 minutes

C: Hold for less than 1 minute

D: Cracked just by twisting

For the PI-based films obtained in Examples and Comparative Examples, the types and ratios of PI-based resin constituent units, film forming conditions and film thickness, and each measurement and evaluation result are shown in Table 1. In addition, the number written in the column of the acid anhydride component is the ratio (%) of each monomer component to the total amount of the acid anhydride component, and the number written in the column of the diamine component is the ratio of each monomer component to the total amount of the diamine component (%) %)am.

As shown in Table 1, it was confirmed that the PI-based films obtained in Examples 1 to 7 had a low Df and a low dielectric loss index (E) compared to Comparative Examples 1 and 2. Therefore, the PI-based film containing the PI-based resin of the present invention can be suitably used in metal-clad laminates such as CCL, which have low transmission loss and can support high frequency bands. In addition, it was confirmed that the PI-based films obtained in Examples 1 to 7 had low CTE compared to Comparative Examples 1 and 2.

In addition, it was confirmed that the PI-based films obtained in Examples 2 to 4 had excellent shape retention properties compared to Comparative Examples 1 and 2.

Claims (14)

A polyimide resin containing a structural unit (A) derived from tetracarboxylic anhydride and a structural unit (B) derived from diamine,
The structural unit (A) derived from tetracarboxylic anhydride has the formula (A1):

[In formula (A1), Z is formula (z1):

(In formula (z1), R ^z11 to R ^z14 independently represent a monovalent hydrocarbon group that may have a hydrogen atom or a halogen atom, n represents an integer of 2 to 4, and * represents a bond. )
is a divalent organic group represented by , R ^a1 independently represents a halogen atom or an alkyl group, alkoxy group, aryl group or aryloxy group that may have a halogen atom, and s independently represents 0 to 3. represents an integer]
A structural unit derived from tetracarboxylic anhydride represented by (A1), and formula (A2):

[In formula (A2), R ^a2 independently represents a halogen atom or an alkyl group, alkoxy group, aryl group, or aryloxy group that may have a halogen atom, and k independently represents an integer of 0 to 2. indicates]
Contains a structural unit (A2) derived from tetracarboxylic anhydride represented by,
A polyimide-based resin in which the diamine-derived structural unit (B) contains a biphenyl skeleton-containing diamine-derived structural unit (B1). According to claim 1,
A polyimide-based resin in which the content of the structural unit (A1) is 15 mol% or more based on the total amount of the structural unit (A). The method of claim 1 or 2,
A polyimide-based resin in which the content of the structural unit (A1) is 75 mol% or less based on the total amount of the structural unit (A). The method of claim 1 or 2,
A polyimide-based resin in which the content of the structural unit (A2) is 25 mol% or more relative to the total amount of the structural unit (A). The method of claim 1 or 2,
The structural unit (B1) has formula (b1):

[In formula (b1), R ^b1 independently represents a halogen atom or an alkyl group, alkoxy group, aryl group or aryloxy group which may have a halogen atom,
p represents an integer from 0 to 4]
A polyimide-based resin that is a diamine-derived structural unit (b1) represented by . According to claim 5,
A polyimide-based resin in which the content of the structural unit (B1) exceeds 30 mol% based on the total amount of the structural unit (B). The method of claim 1 or 2,
The structural unit (B) further has formula (b2):

[In formula (b2), R ^b2 independently represents a halogen atom or an alkyl group, alkoxy group, aryl group or aryloxy group which may have a halogen atom, and the hydrogen atoms contained in R ^b2 independently represent , may be substituted by a halogen atom,
W are, independently of each other, -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 )-, and R ^c is a hydrogen atom or 1 to 12 carbon atoms that may be substituted with a halogen atom. represents a monovalent hydrocarbon group, m represents 3 or 4, and q independently represents an integer of 0 to 4]
A polyimide-based resin containing less than 20 mol% of diamine-derived structural unit (b2) represented by . A polyimide-based film comprising the polyimide-based resin according to claim 1 or 2. According to claim 8,
A polyimide-based film having a dielectric loss tangent of 0.004 or less at 10 GHz. According to claim 8,
A polyimide-based film with a thickness of 5 to 100 μm. A laminated film comprising a metal foil layer on one or both sides of the polyimide-based film according to claim 8. According to claim 11,
A laminated film, wherein the metal foil layer is a copper foil layer. A flexible printed circuit board comprising the polyimide-based film according to claim 8. A process of coating a polyimide-based resin precursor solution containing a PI-based resin precursor having a structural unit derived from tetracarboxylic anhydride and a structural unit derived from diamine onto a substrate, and
A method for producing a polyimide-based film according to claim 8, comprising a step of imidizing the polyimide-based resin precursor by heat treatment at 200°C or higher and 500°C or lower.