JP7424284B2 - Polyimide resin, polyimide varnish and polyimide film - Google Patents

Description

The present invention relates to polyimide resins, polyimide varnishes, and polyimide films.

Various uses of polyimide resins are being considered in fields such as electrical and electronic parts. For example, it is desired to replace the glass substrates used in image display devices such as liquid crystal displays and OLED displays with plastic substrates in order to make the devices lighter and more flexible. Research is underway. Polyimide films for such uses are required to be colorless and transparent.

In image display devices such as liquid crystal displays and OLED displays, thin film transistors (TFTs) are used as pixel switching elements. Polycrystalline silicon (polysilicon), which has excellent crystallinity, has higher electron mobility than amorphous silicon, so TFT characteristics are significantly improved. One of the methods for forming a polysilicon film is an excimer laser annealing (ELA) method. The amorphous silicon dehydrogenation process in this method is a high temperature process. Therefore, in order to form a polysilicon film on a plastic substrate, the plastic substrate is required to have high heat resistance (ie, high glass transition temperature). Furthermore, under high temperature conditions, organic compounds (outgas) volatilized from the substrate material itself may have a serious adverse effect on the device. Therefore, plastic substrates are also required to have high thermal stability in order to suppress the generation of outgas up to as high a temperature as possible. Furthermore, when light passes through a retardation film or polarizing plate (for example, in liquid crystal displays, OLED displays, touch panels, etc.), the plastic substrate is required to have high optical isotropy in addition to colorless transparency. be done.

Furthermore, in the manufacturing process of image display devices, there is a temperature cycle in which a high temperature process and cooling to room temperature are repeated. Therefore, plastic substrates are also required to have excellent dimensional stability against temperature cycles (ie, low coefficient of linear thermal expansion).
Patent Document 1 describes, as a polyimide resin having a low coefficient of linear thermal expansion, a first tetracarboxylic acid component such as pyromellitic anhydride and 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride. A polyimide resin synthesized from a second tetracarboxylic acid component such as, and a toridine sulfone skeleton diamine component is described.

Japanese Patent Application Publication No. 2010-053336

As mentioned above, plastic substrates are required to have various properties, but it is not easy for polyimide films to satisfy all of these properties at the same time.
The present invention was made in view of these circumstances, and an object of the present invention is to form a film that is colorless and transparent, has excellent heat resistance, thermal stability, optical isotropy, and dimensional stability against temperature cycles. An object of the present invention is to provide a polyimide resin capable of producing the same, a method for producing the same, and a polyimide varnish and polyimide film containing the polyimide resin.

The present inventors have discovered that a polyimide resin containing a specific combination of structural units can solve the above problems, and have completed the invention.

（式（ｂ－１－１）中、Ｒはそれぞれ独立して、水素原子、フッ素原子又はメチル基である。） That is, the present invention relates to the following [1] to [16].
[1]
A polyimide resin having a structural unit A derived from a tetracarboxylic dianhydride and a structural unit B derived from a diamine,
The structural unit A contains a structural unit (A-1) derived from a compound represented by the following formula (a-1),
Structural unit B derived from a compound represented by the following formula (b-1-1) (B-1-1), a structural unit derived from a compound represented by the following formula (b-1-2) (B-1-2), and the structural unit (B-1-3) derived from the compound represented by the following formula (b-1-3). -1),
A polyimide resin that does not contain cyclohexane rings.

(In formula (b-1-1), each R is independently a hydrogen atom, a fluorine atom, or a methyl group.)

［８］
構成単位（Ｂ－１－３）が構成単位（Ｂ－１－３１）である、上記［７］に記載のポリイミド樹脂。
［９］
構成単位Ａが、下記式（ａ－２）で表される化合物に由来する構成単位（Ａ－２）を更に含む、上記［１］～［８］のいずれかに記載のポリイミド樹脂。

［１０］
構成単位（Ａ－２）の比率が５～６０モル％である、上記［９］に記載のポリイミド樹脂。
［１１］
構成単位（Ａ－１）と構成単位（Ａ－２）の比［（Ａ－１）／（Ａ－２）］（モル／モル）が、は３０／７０～９０／１０である、上記［９］又は［１０］に記載のポリイミド樹脂。
［１２］
構成単位Ｂが、２，２’－ビス（トリフルオロメチル）ベンジジンに由来する構成単位を更に含む、上記［１］～［１１］のいずれかに記載のポリイミド樹脂。
［１３］
上記式（ａ－１）で表される化合物を含むテトラカルボン酸成分と、上記式（ｂ－１－１）で表される化合物、上記式（ｂ－１－２）で表される化合物、及び上記式（ｂ－１－３）で表される化合物からなる群より選ばれる少なくとも１つである化合物を含むジアミン成分とを反応溶剤存在下、加熱することによってイミド化反応を行う、ポリイミド樹脂の製造方法。
［１４］
反応溶剤が、アミド系溶剤及びラクトン系溶剤からなる群から選ばれる少なくとも１種である、上記［１３］に記載のポリイミド樹脂の製造方法。
［１５］
上記［１］～［１２］のいずれかに記載のポリイミド樹脂が有機溶媒に溶解してなるポリイミドワニス。
［１６］
上記［１］～［１２］のいずれかに記載のポリイミド樹脂を含む、ポリイミドフィルム。 [2]
The polyimide resin according to [1] above, wherein the ratio of the structural unit (A-1) in the structural unit A is 40 mol% or more.
[3]
The polyimide resin according to [1] or [2] above, wherein the ratio of the structural unit (B-1) in the structural unit B is 50 mol% or more.
[4]
The polyimide resin according to any one of [1] to [3] above, wherein the structural unit (B-1) is the structural unit (B-1-1).
[5]
The polyimide resin according to any one of [1] to [3] above, wherein the structural unit (B-1) is the structural unit (B-1-2).
[6]
The polyimide resin according to any one of [1] to [3] above, wherein the structural unit (B-1) is the structural unit (B-1-3).
[7]
The structural unit (B-1-3) is represented by a structural unit (B-1-31) derived from a compound represented by the following formula (b-1-31) and the following formula (b-1-32). The polyimide resin according to any one of [1] to [3] and [6] above, which is at least one structural unit selected from the group consisting of the structural unit (B-1-32) derived from a compound derived from a compound.

[8]
The polyimide resin according to [7] above, wherein the structural unit (B-1-3) is the structural unit (B-1-31).
[9]
The polyimide resin according to any one of [1] to [8] above, wherein the structural unit A further contains a structural unit (A-2) derived from a compound represented by the following formula (a-2).

[10]
The polyimide resin according to [9] above, wherein the ratio of the structural unit (A-2) is 5 to 60 mol%.
[11]
The ratio [(A-1)/(A-2)] (mol/mol) of the structural unit (A-1) and the structural unit (A-2) is from 30/70 to 90/10. 9] or the polyimide resin described in [10].
[12]
The polyimide resin according to any one of [1] to [11] above, wherein the structural unit B further includes a structural unit derived from 2,2'-bis(trifluoromethyl)benzidine.
[13]
A tetracarboxylic acid component containing a compound represented by the above formula (a-1), a compound represented by the above formula (b-1-1), a compound represented by the above formula (b-1-2), and a diamine component containing at least one compound selected from the group consisting of compounds represented by formula (b-1-3) above in the presence of a reaction solvent to perform an imidization reaction. manufacturing method.
[14]
The method for producing a polyimide resin according to [13] above, wherein the reaction solvent is at least one selected from the group consisting of amide solvents and lactone solvents.
[15]
A polyimide varnish obtained by dissolving the polyimide resin according to any one of [1] to [12] above in an organic solvent.
[16]
A polyimide film comprising the polyimide resin according to any one of [1] to [12] above.

According to the present invention, it is possible to form a film that is excellent in colorless transparency, heat resistance, thermal stability, optical isotropy, and dimensional stability against temperature cycles.

（式（ｂ－１－１）中、Ｒはそれぞれ独立して、水素原子、フッ素原子又はメチル基である。） [Polyimide resin]
The polyimide resin of the present invention has a structural unit A derived from a tetracarboxylic dianhydride and a structural unit B derived from a diamine, and the structural unit A is derived from a compound represented by the following formula (a-1). A structural unit (B-1-1) derived from a compound containing the structural unit (A-1), in which the structural unit B is represented by the following formula (b-1-1), the following formula (b-1-2) Selected from the group consisting of a structural unit (B-1-2) derived from a compound represented by the following formula (B-1-3) and a structural unit (B-1-3) derived from a compound represented by the following formula (b-1-3). However, a cyclohexane ring is not present in the resin.

(In formula (b-1-1), each R is independently a hydrogen atom, a fluorine atom, or a methyl group.)

In the present invention, since the polyimide resin does not contain a cyclohexane ring, the thermal stability of the film is improved.
Further, polyimide resins containing a cyclohexane ring generally tend to have excellent colorless transparency, but the polyimide resin of the present invention has excellent colorless transparency even without containing a cyclohexane ring.

<Constituent unit A>
Structural unit A is a structural unit derived from tetracarboxylic dianhydride that occupies the polyimide resin, and includes a structural unit (A-1) derived from a compound represented by the following formula (a-1).

The compound represented by formula (a-1) is 9,9'-bis(3,4-dicarboxyphenyl)fluorene dianhydride.
When the structural unit A contains the structural unit (A-1), the heat resistance, thermal stability, optical isotropy, and dimensional stability against temperature cycles of the film are improved.

The ratio of the structural unit (A-1) in the structural unit A is preferably 40 mol% or more, more preferably 50 mol% or more, still more preferably 60 mol% or more, even more preferably 80 mol% or more. It is mol% or more, more preferably 90 mol% or more, particularly preferably 99 mol% or more. The upper limit of the ratio of the structural unit (A-1) is not particularly limited, ie, 100 mol%. The structural unit A may consist only of the structural unit (A-1).
When the ratio of the structural unit (A-1) in the structural unit A is 40 mol % or more, particularly thermal stability and optical isotropy are improved, and colorless transparency is also improved.

The structural unit A may include structural units other than the structural unit (A-1). However, since there is no cyclohexane ring in the polyimide resin of the present invention, structural units containing a cyclohexane ring are excluded as structural units other than the structural unit (A-1) that is optionally included in the structural unit A.

In addition to the structural unit (A-1), the structural unit A preferably further includes a structural unit (A-2) derived from a compound represented by the following formula (a-2).

The compound represented by formula (a-2) is biphenyltetracarboxylic dianhydride (BPDA), and specific examples thereof include 3,3',4, 4'-biphenyltetracarboxylic dianhydride (s-BPDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA) represented by the following formula (a-2a), Examples include 2,2',3,3'-biphenyltetracarboxylic dianhydride (i-BPDA) represented by the following formula (a-2i).

When the structural unit A contains the structural unit (A-1) and the structural unit (A-2), the ratio of the structural unit (A-1) in the structural unit A is preferably 40 to 95 mol%, and more It is preferably 45 to 90 mol%, more preferably 45 to 85 mol%, even more preferably 50 to 80 mol%, particularly preferably 50 to 70 mol%, and The ratio of units (A-2) is preferably 5 to 60 mol%, more preferably 10 to 55 mol%, even more preferably 15 to 55 mol%, even more preferably 20 to 50 mol%. %, particularly preferably 30 to 50 mol%.
Further, the ratio [(A-1)/(A-2)] (mol/mol) between the structural unit (A-1) and the structural unit (A-2) is preferably 30/70 to 90/10. , more preferably 40/60 to 70/30, still more preferably 50/50 to 60/40.
The total ratio of structural units (A-1) and (A-2) in structural unit A is preferably 50 mol% or more, more preferably 70 mol% or more, and even more preferably 90 mol% or more. and particularly preferably 99 mol% or more. The upper limit of the total ratio of structural units (A-1) and (A-2) is not particularly limited, that is, 100 mol%. The structural unit A may consist only of the structural unit (A-1) and the structural unit (A-2).

When the structural unit A further contains the structural unit (A-2), the dimensional stability of the film against temperature cycles is improved.

Constituent units other than the constituent unit (A-1) that are optionally included in the constituent unit A are not limited to the constituent unit (A-2). Tetracarboxylic dianhydrides providing such arbitrary structural units include, but are not particularly limited to, aromatic tetracarboxylic dianhydrides such as pyromellitic dianhydride and 4,4'-(hexafluoroisopropylidene) diphthalic anhydride. Carboxylic dianhydride (excluding compounds represented by formula (a-1), compounds represented by formula (a-2), and compounds containing a cyclohexane ring); 1,2,3,4-cyclobutane Alicyclic tetracarboxylic dianhydrides such as tetracarboxylic dianhydride (excluding compounds containing a cyclohexane ring); and aliphatic tetracarboxylic dianhydrides such as 1,2,3,4-butanetetracarboxylic dianhydride Examples include carboxylic dianhydrides.
In addition, in this specification, aromatic tetracarboxylic dianhydride means a tetracarboxylic dianhydride containing one or more aromatic rings, and alicyclic tetracarboxylic dianhydride means a tetracarboxylic dianhydride containing one or more alicyclic rings. The term "aliphatic tetracarboxylic dianhydride" refers to a tetracarboxylic dianhydride containing the above and not containing an aromatic ring, and the term "aliphatic tetracarboxylic dianhydride" refers to a tetracarboxylic dianhydride containing neither an aromatic ring nor an alicyclic ring.
The number of structural units other than the structural unit (A-1) optionally included in the structural unit A may be one type or two or more types.

（式（ｂ－１－１）中、Ｒはそれぞれ独立して、水素原子、フッ素原子又はメチル基である。） <Constituent unit B>
Structural unit B is a structural unit derived from a diamine that occupies the polyimide resin, and includes a structural unit (B-1-1) derived from a compound represented by the following formula (b-1-1), a structural unit derived from the following formula (b-1-1), and a structural unit derived from the following formula (b-1-1). A structural unit (B-1-2) derived from a compound represented by -1-2) and a structural unit (B-1-3) derived from a compound represented by the following formula (b-1-3) Contains at least one structural unit (B-1) selected from the group consisting of.

(In formula (b-1-1), each R is independently a hydrogen atom, a fluorine atom, or a methyl group.)

In formula (b-1-1), each R is independently a hydrogen atom, a fluorine atom, or a methyl group, preferably a hydrogen atom. Examples of the compound represented by formula (b-1) include 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(3-fluoro-4-aminophenyl)fluorene, and 9,9-bis(4-aminophenyl)fluorene. Examples include (3-methyl-4-aminophenyl)fluorene, and 9,9-bis(4-aminophenyl)fluorene is preferred.
The compound represented by formula (b-1-2) is 4,4'-diamino-2,2'-bistrifluoromethyl diphenyl ether.

Examples of the compound represented by the formula (b-1-3) include the compound represented by the following formula (b-1-31) (i.e., 4,4'-diaminodiphenylsulfone) and the following formula (b-1- 32) (ie, 3,3'-diaminodiphenylsulfone), and the like.

The structural unit (B-1-3) is a structural unit (B-1-31) derived from a compound represented by formula (b-1-31) and a compound represented by formula (b-1-32). It is preferable that it is at least one selected from the group consisting of structural units (B-1-32) derived from.
The structural unit (B-1-3) may be only the structural unit (B-1-31), only the structural unit (B-1-32), or the structural unit (B-1). -31) and the structural unit (B-1-32).
Further, one embodiment of the polyimide resin of the present invention includes a polyimide resin in which the structural unit B does not include the structural unit (B-1-32).

When the structural unit B contains the structural unit (B-1), the colorless transparency, heat resistance, and thermal stability of the film are improved. Further, when the structural unit (B-1) is included as the structural unit (B-1), it is particularly excellent in heat resistance and thermal stability, and furthermore, it is excellent in optical isotropy.

The structural unit (B-1) may be only the structural unit (B-1-1), only the structural unit (B-1-2), or the structural unit (B-1-3). ) may be used.
Further, the structural unit (B-1) may be a combination of the structural unit (B-1-1) and the structural unit (B-1-2), or the structural unit (B-1-2) and the structural unit (B-1-3), or a combination of structural unit (B-1-1) and structural unit (B-1-3).
Furthermore, the structural unit (B-1) may be a combination of the structural unit (B-1-1), the structural unit (B-1-2), and the structural unit (B-1-3).

The ratio of the structural unit (B-1) in the structural unit B is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more, even more preferably 90 mol% or more. It is mol% or more, particularly preferably 99 mol% or more. The upper limit of the ratio of the structural unit (B-1) is not particularly limited, that is, 100 mol%. The structural unit B may consist only of the structural unit (B-1).

The structural unit B may include structural units other than the structural unit (B-1). However, since there is no cyclohexane ring in the polyimide resin of the present invention, structural units containing a cyclohexane ring are excluded as structural units other than the structural unit (B-1) optionally included in the structural unit B.
Diamines that provide structural units other than the structural unit (B-1) optionally included in structural unit B include, but are not particularly limited to, 1,4-phenylenediamine, p-xylylenediamine, and 3,5-diaminobenzoic acid. , 1,5-diaminonaphthalene, 2,2'-dimethylbiphenyl-4,4'-diamine, 2,2'-bis(trifluoromethyl)benzidine, 4,4'-diaminodiphenyl ether, 4,4'-diamino Diphenylmethane, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-diaminobenzanilide, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H -inden-5-amine, α,α'-bis(4-aminophenyl)-1,4-diisopropylbenzene, N,N'-bis(4-aminophenyl)terephthalamide, 4,4'-bis(4-aminophenyl)-inden-5-amine, Aromatic diamines such as -aminophenoxy)biphenyl, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, and 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane ( However, this excludes the compound represented by formula (b-1-1), the compound represented by formula (b-1-2), and the compound represented by formula (b-1-3)); alicyclic and aliphatic diamines such as ethylene diamine and hexamethylene diamine. Among these, 1,5-diaminonaphthalene, 2,2'-dimethylbiphenyl-4,4'-diamine, and 2,2'-bis(trifluoromethyl)benzidine are preferred.
In addition, in this specification, aromatic diamine means a diamine containing one or more aromatic rings, alicyclic diamine means a diamine containing one or more alicyclic rings and no aromatic ring, Group diamine means a diamine containing neither aromatic ring nor alicyclic ring.
The number of structural units other than the structural unit (B-1) optionally included in the structural unit B may be one type or two or more types.

The number average molecular weight of the polyimide resin of the present invention is preferably 5,000 to 300,000, more preferably 5,000 to 100,000, from the viewpoint of mechanical strength of the polyimide film obtained. Note that the number average molecular weight of the polyimide resin can be determined, for example, from a standard polymethyl methacrylate (PMMA) equivalent value measured by gel filtration chromatography.

The polyimide resin of the present invention may include a structure other than a polyimide chain (a structure formed by imide bonding of structural unit A and structural unit B). Structures other than polyimide chains that may be included in the polyimide resin include, for example, structures containing amide bonds.
The polyimide resin of the present invention preferably contains a polyimide chain (a structure formed by imide bonding of structural unit A and structural unit B) as a main structure. Therefore, the proportion of polyimide chains in the polyimide resin of the present invention is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 90% by mass or more, and particularly preferably 99% by mass. % or more.

By using the polyimide resin of the present invention, it is possible to form a film that is colorless and transparent, has excellent heat resistance, thermal stability, optical isotropy, and dimensional stability against temperature cycles, and has suitable physical properties that the film has. The values are as follows.
The total light transmittance is preferably 85% or more, more preferably 88% or more, and even more preferably 89% or more when the film has a thickness of 10 μm.
Yellow index (YI) is preferably 6.5 or less, more preferably 5.5 or less, still more preferably 3.5 or less, even more preferably It is 2.0 or less.
The glass transition temperature (Tg) is preferably 330°C or higher, more preferably 360°C or higher, and even more preferably 400°C or higher.
The 1% weight loss temperature is preferably 480°C or higher, more preferably 500°C or higher, and still more preferably 520°C or higher.
The 2% weight loss temperature is preferably 510°C or higher, more preferably 520°C or higher, and still more preferably 530°C or higher.
The 3% weight loss temperature is preferably 520°C or higher, more preferably 540°C or higher, and still more preferably 550°C or higher.
The 5% weight loss temperature is preferably 530°C or higher, more preferably 540°C or higher, and even more preferably 550°C or higher.
The weight loss rate at 450°C is preferably 1.10% or less, more preferably 0.80% or less, even more preferably 0.50% or less.
The weight loss rate at 480° C. is preferably 4.00% or less, more preferably 2.50% or less, and even more preferably 1.00% or less.
The absolute value of the thickness retardation (Rth) is preferably 250 nm or less, more preferably 180 nm or less, even more preferably 120 nm or less, even more preferably 90 nm or less when the film has a thickness of 10 μm. and is even more preferably 30 nm or less.
The coefficient of linear thermal expansion (CTE) is preferably 45 ppm/°C or less, more preferably 40 ppm/°C or less, and still more preferably 30 ppm/°C or less.

The film that can be formed using the polyimide resin of the present invention also has good mechanical properties and has the following suitable physical property values.
The tensile modulus is preferably 2.0 GPa or more, more preferably 2.5 GPa or more, still more preferably 3.0 GPa or more.
The tensile strength is preferably 80 MPa or more, more preferably 90 MPa or more, still more preferably 100 MPa or more.
In addition, the above-mentioned physical property values in the present invention can be specifically measured by the method described in the Examples.

[Production method of polyimide resin]
The polyimide resin of the present invention is produced by reacting a tetracarboxylic acid component containing a compound that provides the above-mentioned structural unit (A-1) with a diamine component that contains a compound that provides the above-mentioned structural unit (B-1). can do.
A more specific method for producing a polyimide resin of the present invention is to react a tetracarboxylic acid component containing a compound that provides the structural unit (A-1) with a diamine component that contains a compound that provides the structural unit (B-1) in a solvent. The imidization reaction is carried out by heating in the presence of the compound.
That is, a tetracarboxylic acid component containing a compound represented by formula (a-1), a compound represented by formula (b-1-1), a compound represented by formula (b-1-2), and An imidization reaction is carried out by heating a diamine component containing at least one compound selected from the group consisting of compounds represented by formula (b-1-3) in the presence of a reaction solvent.

Examples of the compound that provides the structural unit (A-1) include the compound represented by formula (a-1), but the compound is not limited thereto, and derivatives thereof may be used as long as they provide the same structural unit. Examples of the derivative include a tetracarboxylic acid corresponding to the tetracarboxylic dianhydride represented by formula (a-1), and an alkyl ester of the tetracarboxylic acid. As the compound providing structural unit (A-1), a compound represented by formula (a-1) (ie, dianhydride) is preferable.

The tetracarboxylic acid component preferably contains a compound providing the structural unit (A-1) in an amount of 40 mol% or more, more preferably 50 mol% or more, more preferably 60 mol% or more, and even more preferably 80 mol%. It contains at least 90 mol%, more preferably at least 90 mol%, particularly preferably at least 99 mol%. The upper limit of the content of the compound providing the structural unit (A-1) is not particularly limited, that is, it is 100 mol%. The tetracarboxylic acid component may consist only of the compound that provides the structural unit (A-1).

The tetracarboxylic acid component may contain a compound other than the compound providing the structural unit (A-1).
It is preferable that the tetracarboxylic acid component further contains a compound that provides the structural unit (A-2) in addition to the compound that provides the structural unit (A-1).
Examples of the compound that provides the structural unit (A-2) include the compound represented by formula (a-2), but the compound is not limited thereto, and derivatives thereof may be used as long as they provide the same structural unit. Examples of such derivatives include tetracarboxylic acids corresponding to the tetracarboxylic dianhydride represented by formula (a-2) and alkyl esters of the tetracarboxylic acids. As the compound providing structural unit (A-2), a compound represented by formula (a-2) (ie, dianhydride) is preferable.

When the tetracarboxylic acid component contains a compound that provides the structural unit (A-1) and a compound that provides the structural unit (A-2), the tetracarboxylic acid component preferably contains the compound that provides the structural unit (A-1). Contains 40 to 95 mol%, more preferably 45 to 90 mol%, still more preferably 45 to 85 mol%, even more preferably 50 to 80 mol%, particularly preferably 50 to 70 mol%, structural unit It preferably contains 5 to 60 mol%, more preferably 10 to 55 mol%, even more preferably 15 to 55 mol%, particularly preferably 20 to 50 mol% of the compound giving (A-2).
The tetracarboxylic acid component preferably contains a total of 50 mol% or more, more preferably 70 mol% or more, and even more preferably contains 90 mol% or more, particularly preferably 99 mol% or more. The upper limit of the total content of the compound providing the structural unit (A-1) and the compound providing the structural unit (A-2) is not particularly limited, that is, 100 mol%. The tetracarboxylic acid component may consist only of a compound that provides the structural unit (A-1) and a compound that provides the structural unit (A-2).

Compounds other than the compound that provides the structural unit (A-1) that are optionally included in the tetracarboxylic acid component are not limited to the compounds that provide the structural unit (A-2). Such optional compounds include the above-mentioned aromatic tetracarboxylic dianhydrides, alicyclic tetracarboxylic dianhydrides, and aliphatic tetracarboxylic dianhydrides, as well as derivatives thereof (tetracarboxylic acids, tetracarboxylic dianhydrides, alkyl esters of carboxylic acids, etc.).
The number of compounds other than the compound providing the structural unit (A-1) optionally included in the tetracarboxylic acid component may be one or two or more.

Examples of the compound that provides the structural unit (B-1) include a compound that provides the structural unit (B-1-1), a compound that provides the structural unit (B-1-2), and a compound that provides the structural unit (B-1-3). At least one selected from the group consisting of the given compounds is used.
The compound that provides the structural unit (B-1-1), the compound that provides the structural unit (B-1-2), and the compound that provides the structural unit (B-1-3) each have the formula (b-1- Examples include, but are not limited to, compounds represented by 1), compounds represented by formula (b-1-2), and compounds represented by formula (b-1-3). Derivatives thereof may be used within the range given. The derivatives include a diisocyanate corresponding to the diamine represented by the compound represented by formula (b-1-1), and a diisocyanate corresponding to the diamine represented by the compound represented by formula (b-1-2). , and a diisocyanate corresponding to the diamine represented by the compound represented by formula (b-1-3). The compound that provides the structural unit (B-1-1), the compound that provides the structural unit (B-1-2), and the compound that provides the structural unit (B-1-3) each have the formula (b-1- The compound represented by 1) (i.e., diamine), the compound represented by formula (b-1-2) (i.e., diamine), and the compound represented by formula (b-1-3) (i.e., diamine) ) is preferred.

As the compound that provides the structural unit (B-1), only the compound that provides the structural unit (B-1-1) may be used, or only the compound that provides the structural unit (B-1-2) may be used, Alternatively, only the compound that provides the structural unit (B-1-3) may be used.
Furthermore, as the compound that provides the structural unit (B-1), a combination of a compound that provides the structural unit (B-1-1) and a compound that provides the structural unit (B-1-2) may be used. A combination of a compound that provides structural unit (B-1-2) and a compound that provides structural unit (B-1-3) may be used, or a combination of a compound that provides structural unit (B-1-1) and a compound that provides structural unit (B-1 -3) may also be used.
In addition, as a compound that provides the structural unit (B-1), a compound that provides the structural unit (B-1-1), a compound that provides the structural unit (B-1-2), and a structural unit (B-1-3). Combinations of the compounds given may also be used.

The diamine component preferably contains 50 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more, even more preferably 90 mol% or more of the compound that provides the structural unit (B-1). The content is particularly preferably 99 mol% or more. The upper limit of the content of the compound providing the structural unit (B-1) is not particularly limited, that is, 100 mol%. The diamine component may consist only of the compound that provides the structural unit (B-1).

The diamine component may contain a compound other than the compound providing the structural unit (B-1), and such compounds include the above-mentioned aromatic diamines, alicyclic diamines, aliphatic diamines, and derivatives thereof (diisocyanates, etc.) can be mentioned.
The number of compounds other than the compound providing the structural unit (B-1) optionally included in the diamine component may be one or two or more.

In the present invention, the charging ratio of the tetracarboxylic acid component and the diamine component used in the production of the polyimide resin is preferably 0.9 to 1.1 mol of the diamine component per 1 mol of the tetracarboxylic acid component.

Furthermore, in the present invention, in addition to the above-mentioned tetracarboxylic acid component and diamine component, a terminal capping agent may be used in the production of the polyimide resin. As the terminal capping agent, monoamines or dicarboxylic acids are preferable. The amount of the terminal capping agent to be introduced is preferably 0.0001 to 0.1 mol, particularly preferably 0.001 to 0.06 mol, per 1 mol of the tetracarboxylic acid component. Examples of monoamine terminal capping agents include methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3-methylbenzylamine, 3- Ethylbenzylamine, aniline, 3-methylaniline, 4-methylaniline, etc. are recommended. Among these, benzylamine and aniline can be preferably used. As the dicarboxylic acid terminal capping agent, dicarboxylic acids are preferred, and a portion thereof may be ring-closed. For example, phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, 2,3-benzophenone dicarboxylic acid, 3,4-benzophenone dicarboxylic acid, cyclopentane-1,2-dicarboxylic acid, 4-cyclohexene-1 , 2-dicarboxylic acid, etc. are recommended. Among these, phthalic acid and phthalic anhydride can be preferably used.

There is no particular restriction on the method of reacting the above-mentioned tetracarboxylic acid component and diamine component, and any known method can be used.
The specific reaction method is as follows: (1) A tetracarboxylic acid component, a diamine component, and a reaction solvent are placed in a reactor, stirred at room temperature to 80°C for 0.5 to 30 hours, and then heated to imidize. Method of carrying out the reaction, (2) After charging the diamine component and the reaction solvent into a reactor and dissolving them, charging the tetracarboxylic acid component, stirring as necessary at room temperature to 80°C for 0.5 to 30 hours, and then (3) A method in which a tetracarboxylic acid component, a diamine component, and a reaction solvent are charged into a reactor, and the temperature is immediately raised to perform an imidization reaction.

The reaction solvent used for producing the polyimide resin may be any solvent as long as it does not inhibit the imidization reaction and can dissolve the polyimide produced. Examples include aprotic solvents, phenolic solvents, ether solvents, carbonate solvents, and the like.

Specific examples of aprotic solvents include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 1,3-dimethylimidazolidinone, and tetramethylurea. amide solvents, lactone solvents such as γ-butyrolactone and γ-valerolactone, phosphorus-containing amide solvents such as hexamethylphosphoric amide and hexamethylphosphine triamide, sulfur-containing solvents such as dimethylsulfone, dimethylsulfoxide, and sulfolane. Examples include ketone solvents such as acetone, cyclohexanone, and methylcyclohexanone, amine solvents such as picoline and pyridine, and ester solvents such as acetic acid (2-methoxy-1-methylethyl).
Among the amide solvents, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and N-methylcaprolactam are preferred, and N-methyl-2-pyrrolidone is more preferred.
Among the lactone solvents, γ-butyrolactone is preferred.

Specific examples of phenolic solvents include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4 -xylenol, 3,5-xylenol, etc.
Specific examples of ether solvents include 1,2-dimethoxyethane, bis(2-methoxyethyl)ether, 1,2-bis(2-methoxyethoxy)ethane, and bis[2-(2-methoxyethoxy)ethyl]. Examples include ether, tetrahydrofuran, 1,4-dioxane and the like.
Further, specific examples of carbonate-based solvents include diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, propylene carbonate, and the like.
Among the above reaction solvents, amide solvents and/or lactone solvents are preferred, and lactone solvents are more preferred. Further, the above reaction solvents may be used alone or in combination of two or more. When using a mixture of two or more types of solvents, it is particularly preferable to use a mixture of an amide solvent and a lactone solvent.

In the imidization reaction, it is preferable to use a Dean-Stark apparatus or the like to conduct the reaction while removing water generated during production. By performing such an operation, the degree of polymerization and the imidization rate can be further increased.

In the above imidization reaction, a known imidization catalyst can be used. Examples of imidization catalysts include base catalysts and acid catalysts.
Base catalysts include pyridine, quinoline, isoquinoline, α-picoline, β-picoline, 2,4-lutidine, 2,6-lutidine, trimethylamine, triethylamine, tripropylamine, tributylamine, triethylenediamine, imidazole, N,N Examples include organic base catalysts such as -dimethylaniline and N,N-diethylaniline, and inorganic base catalysts such as potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium hydrogen carbonate, and sodium hydrogen carbonate.
In addition, examples of acid catalysts include crotonic acid, acrylic acid, trans-3-hexenoic acid, cinnamic acid, benzoic acid, methylbenzoic acid, oxybenzoic acid, terephthalic acid, benzenesulfonic acid, p-toluenesulfonic acid, naphthalenesulfonic acid, etc. can be mentioned. The above imidization catalysts may be used alone or in combination of two or more.
Among the above, from the viewpoint of ease of handling, it is preferable to use a base catalyst, it is more preferable to use an organic base catalyst, it is even more preferable to use triethylamine, and it is particularly preferable to use a combination of triethylamine and triethylenediamine.

The temperature of the imidization reaction is preferably 120 to 250°C, more preferably 160 to 200°C from the viewpoint of reaction rate and suppression of gelation and the like. Further, the reaction time is preferably 0.5 to 10 hours after the start of distillation of the produced water.

[Polyimide varnish]
The polyimide varnish of the present invention is obtained by dissolving the polyimide resin of the present invention in an organic solvent. That is, the polyimide varnish of the present invention contains the polyimide resin of the present invention and an organic solvent, and the polyimide resin is dissolved in the organic solvent.
The organic solvent is not particularly limited as long as it dissolves the polyimide resin, but it is preferable to use the above-mentioned compounds alone or in a mixture of two or more types as a reaction solvent used in the production of the polyimide resin.
The polyimide varnish of the present invention may be a polyimide solution itself in which a polyimide resin obtained by a polymerization method is dissolved in a reaction solvent, or it may be a polyimide solution obtained by adding a diluting solvent to the polyimide solution.

Since the polyimide resin of the present invention has solvent solubility, it can be made into a highly concentrated varnish that is stable at room temperature. The polyimide varnish of the present invention preferably contains 5 to 40% by mass, more preferably 5 to 30% by mass, and even more preferably 10 to 30% by mass of the polyimide resin of the present invention. The viscosity of the polyimide varnish is preferably 1 to 200 Pa.s, more preferably 1 to 150 Pa.s, and even more preferably 5 to 150 Pa.s. The viscosity of the polyimide varnish is a value measured at 25°C using an E-type viscometer.
In addition, the polyimide varnish of the present invention may contain inorganic fillers, adhesion promoters, release agents, flame retardants, ultraviolet stabilizers, surfactants, leveling agents, antifoaming agents, fluorescent enhancers, etc. within the range that does not impair the required properties of the polyimide film. It may contain various additives such as a whitening agent, a crosslinking agent, a polymerization initiator, and a photosensitizer.
The method for producing the polyimide varnish of the present invention is not particularly limited, and known methods can be applied.

[Polyimide film]
The polyimide film of the present invention contains the polyimide resin of the present invention. Therefore, the polyimide film of the present invention has excellent colorless transparency, heat resistance, thermal stability, optical isotropy, and dimensional stability against temperature cycles. The preferred physical properties of the polyimide film of the present invention are as described above.
There are no particular limitations on the method for producing the polyimide film of the present invention, and known methods can be used. For example, after the polyimide varnish of the present invention is coated on a smooth support such as a glass plate, metal plate, or plastic, or formed into a film, organic solvents such as reaction solvents and diluting solvents contained in the varnish are removed. Examples include a method of removing by heating. A release agent may be applied to the surface of the support in advance, if necessary.
As a method for removing the organic solvent contained in the varnish by heating, the following method is preferable. That is, after evaporating the organic solvent at a temperature of 120° C. or lower to form a self-supporting film, the self-supporting film is peeled off from the support, the edges of the self-supporting film are fixed, and the organic solvent used is removed. It is preferable to produce a polyimide film by drying at a temperature equal to or higher than the boiling point of the polyimide film. Moreover, it is preferable to dry under a nitrogen atmosphere. The pressure of the drying atmosphere may be reduced pressure, normal pressure, or increased pressure. The heating temperature when drying the self-supporting film to produce a polyimide film is not particularly limited, but is preferably from 200 to 500°C, more preferably from 200 to 400°C.

Moreover, the polyimide film of the present invention can also be manufactured using a polyamic acid varnish formed by dissolving polyamic acid in an organic solvent.
The polyamic acid contained in the polyamic acid varnish is a precursor of the polyimide resin of the present invention, and is a tetracarboxylic acid component containing a compound that provides the above-mentioned structural unit (A-1) and the above-mentioned structural unit (B-1). ) is the product of a polyaddition reaction with a diamine component containing a compound that gives By imidizing this polyamic acid (dehydration ring closure), the final product, the polyimide resin of the present invention, is obtained.
As the organic solvent contained in the polyamic acid varnish, the organic solvent contained in the polyimide varnish of the present invention can be used.
In the present invention, the polyamic acid varnish is produced by combining a tetracarboxylic acid component containing a compound that provides the above-mentioned structural unit (A-1) and a diamine component containing a compound that provides the above-mentioned structural unit (B-1) in a reaction solvent. The polyamic acid solution itself obtained by polyaddition reaction may be used, or the polyamic acid solution may be prepared by adding a diluting solvent to the polyamic acid solution.

There are no particular limitations on the method for producing a polyimide film using polyamic acid varnish, and any known method can be used. For example, a polyamic acid varnish is applied onto a smooth support such as a glass plate, metal plate, or plastic, or formed into a film, and organic solvents such as reaction solvents and diluting solvents contained in the varnish are removed by heating. A polyimide film can be produced by obtaining a polyamic acid film and imidizing the polyamic acid in the polyamic acid film by heating.
The heating temperature when drying the polyamic acid varnish to obtain a polyamic acid film is preferably 50 to 120°C. The heating temperature when imidizing polyamic acid by heating is preferably 200 to 500°C, more preferably 200 to 480°C, even more preferably 200 to 450°C, even more preferably 200 to 400°C. It is ℃.
Note that the imidization method is not limited to thermal imidization, and chemical imidization can also be applied.

The thickness of the polyimide film of the present invention can be appropriately selected depending on the application, etc., but is preferably in the range of 1 to 250 μm, more preferably 5 to 100 μm, still more preferably 8 to 80 μm, even more preferably 10 to 80 μm. It is. A thickness of 1 to 250 μm allows practical use as a self-supporting membrane.
The thickness of the polyimide film can be easily controlled by adjusting the solid content concentration and viscosity of the polyimide varnish.

The polyimide film of the present invention is suitably used as a film for various members such as color filters, flexible displays, semiconductor parts, and optical members. The polyimide film of the present invention is particularly suitably used as a substrate for image display devices such as liquid crystal displays and OLED displays.

The present invention will be specifically explained below using Examples. However, the present invention is not limited to these Examples in any way.
The solid content concentration of the polyimide varnish and each physical property of the polyimide film obtained in Examples and Comparative Examples were measured by the methods shown below.

(1) Solid content concentration The solid content concentration of polyimide varnish was measured by heating the sample at 320°C x 120 min in a small electric furnace "MMF-1" manufactured by As One Co., Ltd., and calculating it from the difference in mass of the sample before and after heating. .
(2) Film thickness The film thickness was measured using a micrometer manufactured by Mitutoyo Co., Ltd.
(3) Total light transmittance, yellow index (YI) (evaluation of colorless transparency)
The total light transmittance and YI were measured in accordance with JIS K7361-1:1997 using a simultaneous color and turbidity meter "COH400" manufactured by Nippon Denshoku Industries Co., Ltd. The closer the total light transmittance is to 100%, and the smaller the YI value, the better the colorless transparency.
(4) Glass transition temperature (Tg) (evaluation of heat resistance)
Using a thermomechanical analyzer "TMA/SS6100" manufactured by Hitachi High-Tech Science Co., Ltd., remove residual stress in tensile mode under the conditions of sample size 2 mm x 20 mm, load 0.1 N, and temperature increase rate 10 ° C / min. The temperature was raised to a temperature sufficient to remove residual stress, and then cooled to room temperature. Thereafter, the elongation of the test piece was measured under the same conditions as the treatment for removing the residual stress, and the point where the inflection point of elongation was found was determined as the glass transition temperature. The larger the value of Tg, the better the heat resistance.
(5) 1%, 2%, 3%, and 5% weight loss temperature and 450°C and 480°C weight loss rate (evaluation of thermal stability)
A simultaneous differential thermogravimetric measurement device "TG/DTA6200" manufactured by Hitachi High-Tech Science Co., Ltd. was used. The sample was heated to 40 to 550°C at a heating rate of 10°C/min, and the temperatures at which the weight decreased by 1, 2, 3, and 5% compared to the weight at 300°C were determined as 1% and 2%, respectively. %, 3%, and 5% weight loss temperatures. The larger the value of each weight loss temperature, the better the thermal stability.
Further, the sample was heated from 40°C to a predetermined temperature (450°C or 480°C) at a heating rate of 10°C/min, and held at that temperature for 1 hour. The 450°C weight loss rate is the ratio of the weight reduced during holding at 450°C for 1 hour to the weight before holding for 1 hour, and the ratio of the weight reduced during holding at 480°C for 1 hour to the weight before holding for 1 hour. The ratio to the weight was defined as the 480°C weight loss rate. The smaller the weight loss rate, the better the thermal stability.
(6) Thickness retardation (Rth) (evaluation of optical isotropy)
The thickness retardation (Rth) was measured using an ellipsometer "M-220" manufactured by JASCO Corporation. The value of the thickness retardation was measured at a measurement wavelength of 590 nm. Note that Rth is expressed by the following formula, where the maximum in-plane refractive index of the polyimide film is nx, the minimum is ny, the refractive index in the thickness direction is nz, and the thickness of the film is d. It is something that The smaller the absolute value of Rth, the better the optical isotropy.
Rth=[{(nx+ny)/2}-nz]×d
(7) Coefficient of linear thermal expansion (CTE) (evaluation of dimensional stability against temperature cycles)
Using a thermomechanical analyzer "TMA/SS6100" manufactured by Hitachi High-Tech Science Co., Ltd., TMA measurements were performed in tensile mode under the conditions of a sample size of 2 mm x 20 mm, a load of 0.1 N, and a temperature increase rate of 10 ° C / min. The CTE between 100 and 200°C was determined. The smaller the CTE value, the better the dimensional stability against temperature cycles.
(8) Tensile modulus and tensile strength The tensile modulus and tensile strength were measured using a tensile tester "Strograph VG-1E" manufactured by Toyo Seiki Co., Ltd. in accordance with JIS K7127.

The tetracarboxylic acid component and diamine component used in Examples and Comparative Examples, and their abbreviations are as follows.
<Tetracarboxylic acid component>
BPAF: 9,9'-bis(3,4-dicarboxyphenyl)fluorene dianhydride (manufactured by JFE Chemical Co., Ltd.; compound represented by formula (a-1))
s-BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride (manufactured by Mitsubishi Chemical Corporation; compound represented by formula (a-2s))
a-BPDA: 2,3,3',4'-biphenyltetracarboxylic dianhydride (manufactured by Mitsubishi Chemical Corporation; compound represented by formula (a-2a))
HPMDA: 1,2,4,5-cyclohexanetetracarboxylic dianhydride (manufactured by Mitsubishi Gas Chemical Co., Ltd.)
<Diamine component>
BAFL: 9,9-bis(4-aminophenyl)fluorene (manufactured by Taoka Chemical Co., Ltd.; compound represented by formula (b-1-1))
6FODA: 4,4'-diamino-2,2'-bistrifluoromethyl diphenyl ether (manufactured by ChinaTech Chemical (Tianjin) Co., Ltd.; compound represented by formula (b-1-2))
4,4-DDS: 4,4'-diaminodiphenylsulfone (manufactured by Wakayama Seika Kogyo Co., Ltd.; compound represented by formula (b-1-3))
DAN: 1,5-diaminonaphthalene TFMB: 2,2'-bis(trifluoromethyl)benzidine

<Example 1>
34.845 g (0.100 mol) of BAFL was placed in a 1 L 5-necked round-bottomed flask equipped with a stainless steel half-moon stirring blade, a nitrogen inlet tube, a Dean Stark fitted with a cooling tube, a thermometer, and a glass end cap. and γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added in an amount of 98.826 g, and the mixture was stirred at a rotational speed of 150 rpm at a system temperature of 70° C. under a nitrogen atmosphere to obtain a solution.
To this solution, 45.843 g (0.100 mol) of BPAF and 24.206 g of N-methylpyrrolidone (manufactured by Mitsubishi Chemical Corporation) were added at once, and then triethylamine (manufactured by Kanto Chemical Co., Ltd.) was added as an imidization catalyst. ) and heated with a mantle heater to raise the temperature inside the reaction system to 190°C over about 20 minutes. The components to be distilled off were collected, and the reaction system was refluxed for 3 hours while maintaining the internal temperature at 190° C. while adjusting the rotation speed in accordance with the increase in viscosity.
Thereafter, 572.724 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added, the temperature inside the reaction system was cooled to 120°C, and the mixture was further stirred for about 3 hours to homogenize the solid content to 10.0 mass. % polyimide varnish was obtained.
Subsequently, the obtained polyimide varnish was applied onto a glass plate, held at 80°C for 20 minutes on a hot plate, and then heated at 400°C for 30 minutes in a hot air dryer under a nitrogen atmosphere to evaporate the solvent, resulting in a thickness of 18 μm. obtained the film. The results are shown in Table 1.

<Example 2>
A polyimide varnish was prepared in the same manner as in Example 1, except that 34.845 g (0.100 mol) of BAFL was changed to 33.620 g (0.100 mol) of 6FODA, and a polyimide varnish with a solid content concentration of 10.0% by mass was obtained. I got it.
Using the obtained polyimide varnish, a film was produced in the same manner as in Example 1 to obtain a film with a thickness of 10 μm. The results are shown in Table 1.

<Example 3>
A polyimide varnish was prepared in the same manner as in Example 1, except that 34.845 g (0.100 mol) of BAFL was changed to 24.830 g (0.100 mol) of 4,4-DDS, and the solid content concentration was 10.0 mass. % polyimide varnish was obtained.
Using the obtained polyimide varnish, a film was produced in the same manner as in Example 1 to obtain a film with a thickness of 10 μm. The results are shown in Table 1.

<Example 4>
Same as Example 1 except that the amount of BPAF was changed from 45.843 g (0.100 mol) to 36.674 g (0.080 mol) and 4.884 g (0.020 mol) of s-BPDA was added. A polyimide varnish was produced by the method described above, and a polyimide varnish with a solid content concentration of 10.0% by mass was obtained.
Using the obtained polyimide varnish, a film was produced in the same manner as in Example 1 to obtain a film with a thickness of 10 μm. The results are shown in Table 1.

<Example 5>
Same as Example 1 except that the amount of BPAF was changed from 45.843 g (0.100 mol) to 22.922 g (0.050 mol) and 14.711 g (0.050 mol) of s-BPDA was added. A polyimide varnish was produced by the method described above, and a polyimide varnish with a solid content concentration of 10.0% by mass was obtained.
Using the obtained polyimide varnish, a film was produced in the same manner as in Example 1 to obtain a film with a thickness of 10 μm. The results are shown in Table 1.

<Example 6>
17.423 g (0.050 mol) of BAFL was placed in a 1 L 5-neck round bottom flask equipped with a stainless steel half-moon stirring blade, a nitrogen inlet tube, a Dean Stark with a cooling tube, a thermometer, and a glass end cap. 7.910 g (0.050 mol) of DAN and 105.746 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added, and the mixture was stirred at a rotational speed of 150 rpm at a system temperature of 70°C under a nitrogen atmosphere to obtain a solution. Ta.
To this solution, 45.843 g (0.100 mol) of BPAF and 26.437 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added at once, and then triethylamine (manufactured by Kanto Chemical Co., Ltd.) was added as an imidization catalyst. 0.506g of was added and heated with a mantle heater to raise the temperature inside the reaction system to 190°C over about 20 minutes. The components to be distilled off were collected, and the reaction system was refluxed for 3 hours while maintaining the internal temperature at 190° C. while adjusting the rotation speed in accordance with the increase in viscosity.
Thereafter, 475.960 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added, the temperature inside the reaction system was cooled to 120°C, and the mixture was further stirred for about 3 hours to homogenize the solid content to 10.0 mass. % polyimide varnish was obtained.
Subsequently, the obtained polyimide varnish was applied onto a glass plate, held at 80°C for 20 minutes on a hot plate, and then heated at 400°C for 30 minutes in a hot air dryer under a nitrogen atmosphere to evaporate the solvent, resulting in a thickness of 9. A film of .3 μm was obtained. The results are shown in Table 1.

<Example 7>
The amount of BPAF was changed from 45.843 g (0.100 mol) to 22.922 g (0.050 mol), 14.711 g (0.050 mol) of s-BPDA was added, and 7.910 g (0.050 mol) of DAN was added. A polyimide varnish was produced in the same manner as in Example 6, except that 16.012 g (0.050 mol) of TFMB was added instead of TFMB, and a polyimide varnish with a solid content concentration of 10.0% by mass was obtained.
Using the obtained polyimide varnish, a film was produced in the same manner as in Example 1 to obtain a film with a thickness of 9.5 μm. The results are shown in Table 1.

<Example 8>
The amount of BPAF was changed from 45.843 g (0.100 mol) to 22.922 g (0.050 mol), 14.711 g (0.050 mol) of s-BPDA was added, and the amount of BAFL was changed to 17.423 g. (0.050 mol) to 27.876 g (0.080 mol), and 6.405 g (0.020 mol) of TFMB was added instead of DAN 7.910 g (0.050 mol). A polyimide varnish was produced by the same method as in No. 6 to obtain a polyimide varnish having a solid content concentration of 10.0% by mass.
Subsequently, the obtained polyimide varnish was applied onto a glass plate, held at 80°C for 20 minutes on a hot plate, and then heated at 420°C for 30 minutes in a hot air dryer under a nitrogen atmosphere to evaporate the solvent, resulting in a thickness of 9 μm. obtained the film. The results are shown in Table 1.

<Example 9>
A polyimide varnish was prepared in the same manner as in Example 6, except that 16.012 g (0.050 mol) of TFMB was added instead of 7.910 g (0.050 mol) of DAN, and the solid content concentration was 10.0% by mass. A polyimide varnish was obtained.
Using the obtained polyimide varnish, a film was produced in the same manner as in Example 1 to obtain a film with a thickness of 10 μm. The results are shown in Table 1.

<Example 10>
The amount of BPAF was changed from 45.843 g (0.100 mol) to 22.922 g (0.050 mol), 14.711 g (0.050 mol) of a-BPDA was added, and 7.910 g (0.050 mol) of DAN was added. A polyimide varnish was prepared in the same manner as in Example 6, except that the amount of BAFL was changed from 17.423 g (0.050 mol) to 34.845 g (0.100 mol), and the solid content was A polyimide varnish with a concentration of 10.0% by mass was obtained.
Using the obtained polyimide varnish, a film was produced in the same manner as in Example 1 to obtain a film with a thickness of 9 μm. The results are shown in Table 1.

<Example 11>
A polyimide varnish was prepared in the same manner as in Example 7, except that the reaction solvent and the dilution solvent after refluxing for 3 hours were changed from γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) to N-methylpyrrolidone (manufactured by Mitsubishi Chemical Corporation). A polyimide varnish with a solid content concentration of 10.0% by mass was obtained.
Subsequently, the obtained polyimide varnish was applied onto a glass plate, held at 80°C for 20 minutes on a hot plate, and then heated at 420°C for 30 minutes in a hot air dryer under a nitrogen atmosphere to evaporate the solvent, resulting in a thickness of 10 μm. obtained the film. The results are shown in Table 1.

<Example 12>
A polyimide varnish was prepared in the same manner as in Example 9, except that the reaction solvent and the dilution solvent after refluxing for 3 hours were changed from γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) to N-methylpyrrolidone (manufactured by Mitsubishi Chemical Corporation). A polyimide varnish with a solid content concentration of 10.0% by mass was obtained.
Subsequently, the obtained polyimide varnish was applied onto a glass plate, held at 80°C for 20 minutes on a hot plate, and then heated at 420°C for 30 minutes in a hot air dryer under a nitrogen atmosphere to evaporate the solvent, resulting in a thickness of 9 μm. obtained the film. The results are shown in Table 1.

<Example 13>
A polyimide varnish was produced in the same manner as in Example 5, except that the dilution solvent after refluxing for 3 hours was changed from γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) to N-methylpyrrolidone (manufactured by Mitsubishi Chemical Corporation). A polyimide varnish with a solid content concentration of 10.0% by mass was obtained.
Subsequently, the obtained polyimide varnish was applied onto a glass plate, held at 80°C for 20 minutes on a hot plate, and then heated at 450°C for 30 minutes in a hot air dryer under a nitrogen atmosphere to evaporate the solvent, resulting in a thickness of 9 μm. I got a film of. The results are shown in Table 1.

<Example 14>
A polyimide varnish was prepared in the same manner as in Example 10, except that the reaction solvent and the dilution solvent after refluxing for 3 hours were changed from γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) to N-methylpyrrolidone (manufactured by Mitsubishi Chemical Corporation). A polyimide varnish with a solid content concentration of 10.0% by mass was obtained.
Subsequently, the obtained polyimide varnish was applied onto a glass plate, held at 80°C for 20 minutes on a hot plate, and then heated at 450°C for 30 minutes in a hot air dryer under a nitrogen atmosphere to evaporate the solvent, resulting in a thickness of 8 μm. obtained the film. The results are shown in Table 1.

<Comparative example 1>
A polyimide varnish was prepared in the same manner as in Example 1, except that 45.843 g (0.100 mol) of BPAF was changed to 22.417 g (0.100 mol) of HPMDA, and a polyimide varnish with a solid content concentration of 10.0% by mass was obtained. I got it.
Using the obtained polyimide varnish, a film was produced in the same manner as in Example 1 to obtain a film with a thickness of 11 μm. The results are shown in Table 1.

<Comparative example 2>
Same method as Example 1 except that the amount of BPAF was changed from 45.843 g (0.100 mol) to 22.922 g (0.050 mol) and 11.209 g (0.050 mol) of HPMDA was added. A polyimide varnish with a solid content concentration of 10.0% by mass was obtained.
Using the obtained polyimide varnish, a film was produced in the same manner as in Example 1 to obtain a film with a thickness of 14 μm. The results are shown in Table 1.

As shown in Table 1, the polyimide films of Examples 1 to 14 produced using a specific tetracarboxylic acid component and a specific diamine component had colorless transparency, heat resistance, thermal stability, optical isotropy, and It had excellent dimensional stability against temperature cycles.
On the other hand, the polyimide film of Comparative Example 1 produced using HPMDA instead of BPAF as the tetracarboxylic acid component was 1%, 2%, 3%, and 5% by weight compared to the polyimide film of Example 1. The reduction temperature was low, and the weight loss rate at 450°C and 480°C was large. In addition, the polyimide film of Comparative Example 2, which was produced using a combination of BPAF and HPMDA as the tetracarboxylic acid component, also had a weight loss temperature of 1%, 2%, 3%, and 5% compared to the polyimide film of Example 1. The weight loss rate at 450°C and 480°C was large. Therefore, even when HPMDA was used in place of BPAF or in combination with BPAF as the tetracarboxylic acid component, the thermal stability of the polyimide film deteriorated.

Claims (10)

A polyimide resin having a structural unit A derived from a tetracarboxylic dianhydride and a structural unit B derived from a diamine,
A structural unit (A-1) in which structural unit A is derived from a compound represented by the following formula (a-1), and a structural unit (A-2) derived from a compound represented by the following formula (a-2) including;
A structural unit (B-1-1) in which the structural unit B is derived from a compound represented by the following formula (b-1-1), and a structure derived from a compound represented by the following formula (b-1-2) Contains at least one structural unit (B-1) selected from the group consisting of units (B-1-2),
The ratio of the structural unit (A-1) in the structural unit A is 80 to 85 mol%,
The ratio of the structural unit (A-2) in the structural unit A is 15 to 20 mol%,
A polyimide resin that does not contain cyclohexane rings.

(In formula (b-1-1), each R is independently a hydrogen atom, a fluorine atom, or a methyl group.) The polyimide resin according to claim 1, wherein the ratio of the structural unit (B-1) in the structural unit B is 50 mol% or more. The polyimide resin according to claim 1 or 2, wherein the structural unit (B-1) is a structural unit (B-1-1). The polyimide resin according to claim 1 or 2, wherein the structural unit (B-1) is a structural unit (B-1-2). A claim in which the ratio [(A-1)/(A-2)] (mol/mol) of the structural unit (A-1) and the structural unit (A- 2 ) is from 80/20 to 85/15. 5. The polyimide resin according to any one of 1 to 4. The polyimide resin according to any one of claims 1 to 5, wherein the structural unit B further includes a structural unit derived from 2,2'-bis(trifluoromethyl)benzidine. A compound represented by the following formula (a-1), a tetracarboxylic acid component containing a compound represented by the following formula (a-2), a compound represented by the following formula (b-1-1), and A polyimide resin which undergoes an imidization reaction by heating a diamine component containing at least one compound selected from the group consisting of compounds represented by the following formula (b-1-2) in the presence of a reaction solvent. A manufacturing method, wherein the ratio of the compound represented by formula (a-1) in the tetracarboxylic acid component is 80 to 85 mol%, and the ratio of the compound represented by formula (a-2) in the tetracarboxylic acid component is A method for producing a polyimide resin, wherein the ratio of the compound is 15 to 20 mol%.

(In formula (b-1-1), each R is independently a hydrogen atom, a fluorine atom, or a methyl group.) The method for producing a polyimide resin according to claim 7, wherein the reaction solvent is at least one selected from the group consisting of amide solvents and lactone solvents. A polyimide varnish obtained by dissolving the polyimide resin according to any one of claims 1 to 6 in an organic solvent. A polyimide film comprising the polyimide resin according to any one of claims 1 to 6.