WO2010131442A1 - Process for producing polyamic acid solution, and polyimide film - Google Patents

Abstract

A process for producing a polyamic acid solution using specific monomers, in particular, a process for producing a polyamic acid solution having a sufficiently high viscosity, in which the time period required for increasing viscosity can be controlled or shortened; a polyimide film composition; and a product or member produced using the resin composition and having excellent heat resistance. The process includes supplementing the monomers to a low-viscosity polyamic acid solution obtained from a specific aromatic acid dianhydride, a specific diamine, an aprotic polar solvent, and an aliphatic carboxylic acid and reacting the monomers, thereby producing, within two hours, a polyamic acid having a desired solution viscosity. Provided is a polyimide film having the same coefficient of expansion as various inorganic materials.

Description

Method for producing polyamic acid solution and polyimide film

The present invention relates to a polymer compound having excellent heat resistance and dimensional stability and a method for producing the same. Preferably, it relates to a polyimide having excellent heat resistance, and in particular, a method for producing a polyimide film that can be suitably used as a material (for example, a substitute for display device glass) for forming a product or member that has high demands on heat resistance and dimensional stability. In particular, a method for producing polyamic acid in which an aliphatic carboxylic acid is used as a part of a solvent to shorten the production time, a polyimide film obtained by the production method, a resin composition using the polyimide film, and the resin The present invention relates to an article produced using the composition.

In recent years, with the rapid progress of displays such as liquid crystal, organic EL, and electronic paper, and electronics such as solar cells and touch panels, devices have been required to be thinner and lighter, and more flexible. . In these devices, various electronic elements such as thin transistors and transparent electrodes are formed on a glass plate, but devices using a glass substrate have a problem that they are thick, heavy, and easily damaged. By changing this glass material to a film material, the panel itself can be made thinner and lighter, and more flexible. However, the formation of these electronic devices requires a high temperature process, and there has been no film material that can withstand this.

Moreover, when these fine elements made of an inorganic material are formed on a film, the film is bent after the formation of the inorganic element due to the difference in the linear expansion coefficient between the inorganic material and the film, and further, the inorganic element is destroyed. There was a fear. For this reason, a film material having the same linear expansion coefficient as an inorganic material while having transparency and heat resistance has been desired.

Polyimide has high heat resistance, dimensional stability, chemical resistance, electrical properties, mechanical properties, and other excellent properties, so it has been applied to semiconductors and electronic components. For this reason, it is often laminated with a metal such as single crystal silicon or copper, and attempts have been made to reduce the linear thermal expansion coefficient of polyimide to the same level as single crystal silicon or metal.

The chemical structure is a factor that greatly affects the linear thermal expansion coefficient of polyimide. Generally, it is said that the higher the rigidity and linearity of the polyimide polymer chain, the lower the expansion coefficient. In order to reduce the expansion coefficient, various structures have been proposed for both acid dianhydrides and diamines, which are polyimide raw materials. It was.

Among these, polyimide obtained from 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 2,2′-bis (trifluoromethyl) benzidine is transparent in addition to heat resistance and linear expansion coefficient. There are several reports so far. A polyimide film is obtained by immersing a film obtained by casting the polyamic acid solution obtained from both monomers in a dehydration catalyst and an imidizing agent solution. It is described that the linear expansion coefficient of the film was improved by dipping. (Patent Document 1).

For example, Patent Document 2 describes that a polyamic acid obtained by reacting these in m-cresol was gradually heated to 300 ° C. to obtain a polyimide. Only the thermophysical properties of are described, and details of other physical properties are not described.

In addition, Non-Patent Document 1 describes that a polyimide was obtained by adding a dehydration catalyst and an imidizing agent to a solution obtained by using both monomers. It only describes the thermophysical properties of the gel, not the physical properties of the film.

As described above, polyimides produced using 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 2,2′-bis (trifluoromethyl) benzidine have been conventionally known. This monomer has a low reactivity and requires a lot of reaction time in the polyamic acid synthesis stage.

JP2007-046054 U.S. Pat.

The present invention has been achieved in view of the above circumstances, and an object thereof is to obtain a low thermal expansion polyimide having excellent transparency, heat resistance, and linear expansion coefficient in a short production time. Furthermore, a resin composition useful as a resin material for forming a product or member having a high demand for heat resistance and a low linear thermal expansion coefficient using the polymer compound, and further, produced using the resin composition An object is to provide a product or member excellent in heat resistance. In particular, it is an object of the present invention to provide a product and a member in which the polyimide and the resin composition of the present invention are applied for use in contact with an inorganic substance such as glass, metal, metal oxide, or single crystal silicon.

The present invention has the following configuration.

1). A method for producing a polyamic acid solution containing a repeating unit represented by the following formula (1) by polymerizing a diamine compound and an acid dianhydride using a mixture of an aprotic polar solvent and an aliphatic carboxylic acid having 15 or less carbon atoms as a solvent. Yes, the proportion of the aliphatic carboxylic acid having 15 or less carbon atoms in the solvent is 0.5 or more and less than 29% by weight, and the polymerization temperature is 0 to 35 ° C. and −0.5 × (15 or less carbon atoms in the solvent) The ratio of the aliphatic carboxylic acid (% by weight)) The process for producing a polyamic acid solution containing a repeating unit represented by the following formula (1) is polymerized at a temperature of 45 or less.

(Wherein R ¹ represents a tetravalent organic group and R ² represents a divalent organic group).

2). R ¹ is an acid dianhydride residue containing a substituted or unsubstituted aromatic group. The method for producing a polyamic acid solution according to 1), wherein R ¹ is an acid dianhydride residue.

3). R ² has at least one aromatic group and at least one of them has a substituent, or has a plurality of aromatic groups and is bonded with a branched or straight chain alkyl group. The manufacturing method of the polyamic acid solution as described in).

4). 3. The method for producing a polyamic acid solution according to 3), wherein the substituent of R ² is selected from an alkyl group having 1 to 16 carbon atoms, a halogenated alkyl group having 1 to 16 carbon atoms, and halogen.

5). R ¹ is a tetravalent organic group selected from the following formula (2), The method for producing a polyamic acid solution according to 2).

6). R ² is a divalent organic group selected from the following formula (3), The method for producing a polyamic acid solution according to 3),

(R ³ represents an alkyl group having 1 to 16 carbon atoms, a halogenated alkyl group having 1 to 16 carbon atoms, or halogen).

7). The method for producing a polyamic acid solution according to 2), wherein R ¹ is a tetravalent organic group represented by the following formula (4).

8). The method for producing a polyamic acid solution according to 3), wherein the structure of R ^{2 is} a divalent biphenylene group selected from the following formula (5).

(R ³ represents an alkyl group having 1 to 16 carbon atoms, a halogenated alkyl group having 1 to 16 carbon atoms, or halogen).

9). The method for producing a polyamic acid solution according to 8), wherein R ³ is halogen or alkyl halide.

10). 8. The method for producing a polyamic acid solution as described in 8) above, wherein R ³ is a fluoroalkyl group having 1 to 16 carbon atoms.

11). A method for producing a polyimide film containing a repeating unit represented by formula (6), which is prepared by casting a solution obtained by mixing a polyamic acid obtained in 1) with a dehydration catalyst and an imidizing agent onto a support. A method for producing a polyimide film, comprising:

In the formula, R ¹ represents a tetravalent organic group selected from the following formula (2), R ² represents a divalent organic group selected from the following formula (3),

In the formula, R ³ represents hydrogen, halogen, alkyl halide, or a C1-C16 alkyl group.

12). The method for producing a polyimide film according to 11), wherein the structure of R ^{1 is} a tetravalent organic group selected from the following formula (4).

13). 11. The method for producing a polyimide film according to 11), wherein the structure of R ^{2 is} a divalent organic group biphenylene group or phenylene group selected from the following formula (5).

In the formula, R ³ represents hydrogen, halogen, alkyl halide, or a C1-C16 alkyl group.

14). R ³ is halogen, or process for producing a polyimide film as described in 13), which is a halogenated alkyl.

15). The process for producing a polyimide film as described in 13), wherein the R ³ is a trifluoromethyl group.

16). The method for producing a polyimide film according to 11), wherein the imidizing agent is selected from pyridine, picoline, quinoline, or isoquinoline, and the dehydration catalyst is selected from an acid anhydride such as acetic anhydride.

17). The method for producing a polyimide film according to 16), wherein the addition amount of the amine compound is 0.05 molar equivalent or more with respect to the carboxylic acid of the polyamic acid.

18). A polyimide film produced by the method according to any one of 1) to 17) having a linear thermal expansion coefficient of 40 ppm or less and a shrinkage ratio before and after heating of 0.1% or less.

19). The polyimide film according to any one of 1) to 17), which has a glass transition temperature of 200 ° C. or higher.

20). The polyimide film according to any one of 1) to 17), which has a weight average molecular weight of 3,000 or more.

21). 18) A polyimide resin composition using the polyimide film described in 18).

22). 19) A polyimide resin composition using the polyimide film described in 19).

23). Polyimide resin composition using the polyimide film described in 20).

24). 18) A laminate comprising at least one layer of an inorganic material laminated on the polyimide film described in 18).

25). (19) A laminate comprising at least one layer of an inorganic material laminated on the polyimide film described in (19).

26). (20) A laminate comprising at least one layer of an inorganic material laminated on the polyimide film described in (20).

It can be said that the imide skeleton contained in the repeating unit of the formula (1) is a rigid skeleton having high linearity. The obtained polyimide film not only has excellent heat resistance, but also exhibits a low coefficient of linear thermal expansion.

According to the present invention, the production rate of the polyamic acid can be controlled, and the production rate can be improved when a component containing halogen, particularly a component having a fluoroalkyl group, is used. Polyamide acid synthesis time can be shortened. In addition to transparency and heat resistance, the resin composition containing polyimide obtained in the present invention has the same linear expansion coefficient as various inorganic materials, and has low dimensional hysteresis. Suitable as a film or coating film for all known members that require expansibility (dimensional stability), such as printed matter, color filters, flexible displays, semiconductor parts, interlayer insulation films, wiring coating films, Use as an optical circuit, an optical circuit component, an antireflection film, a hologram, an optical member, a building material or a structure is expected.

The present invention will be described in detail below.

The polyamic acid produced in the present invention is a polyamic acid having a repeating unit represented by the formula (1). This polyamic acid can be synthesized using an acid dianhydride and a diamine compound. The aliphatic carboxylic acid used in the present invention is an aliphatic carboxylic acid having 15 or less carbon atoms.

In the aliphatic carboxylic acid having 15 or less carbon atoms that can be used in the present invention, the aliphatic group is preferably an alkyl group having 15 or less carbon atoms, and the alkyl group may have a branch. Among aliphatic carboxylic acids having 15 or less carbon atoms, carboxylic acids having 10 or less carbon atoms, more preferably 5 or less, and particularly 3 or less are preferable. Polyvalent carboxylic acids can also be used, but monovalent carboxylic acids are preferred. Specific examples of the carboxylic acid that can be used include formic acid, acetic acid, propionic acid, n-butyric acid, and iso-butyric acid. Of these, formic acid, acetic acid, and propionic acid are preferable, and acetic acid is more preferable.

The amount of the aliphatic carboxylic acid used in the present invention is 0.5 or more and less than 29% by weight, preferably 3.0 or more and less than 28% by weight, based on the total amount of the solvent including the aliphatic carboxylic acid used. Preferably it is 5.0 or more and less than 27 weight%. In terms of reaction rate, it is particularly preferably 15 to 27% by weight, most preferably 22 to 27% by weight. When the amount of the aliphatic carboxylic acid is higher than the above range, it is difficult to expect an improvement in the synthesis rate of the polyamic acid, and it is difficult to obtain a product having a desired molecular weight by decomposition of the produced polyamic acid. Further, when the amount of the aliphatic carboxylic acid is small, a sufficient polymerization rate cannot be obtained, and it is difficult to shorten the synthesis time of the polyamic acid.

R ¹ in the formula (1) is a tetravalent organic group, and a tetravalent organic group represented by the formula (2) is preferable. Specific examples thereof include a tetravalent organic group corresponding to each acid dianhydride component to be described later, that is, a structure in which acid dianhydride components are removed from both terminal acid anhydride groups involved in the formation of a polyimide chain. It is done.

Of the tetravalent organic groups listed in Formula (2), acid dianhydrides having the structure of Formula (4) are particularly preferred from the viewpoint of the rigidity exhibited by the resulting polymer and the availability of raw materials. A structure having a biphenylene group is more preferable. Further, two or more kinds of tetravalent organic groups can be used as long as the properties such as transparency and expansion coefficient of polyimide can be secured.

As described above, R ¹ in the formula (1) can be introduced from the acid dianhydride component (compound), and two or more kinds of acid dianhydride compounds can be used. As the acid dianhydride component, it is preferable to use an acid dianhydride compound having a tetravalent organic group listed in Formula (2).

In this case, the acid dianhydride compound having a tetravalent organic group listed in the formula (2) is 30 mol% or more, further 50 mol% or more of the whole acid dianhydride, depending on the target physical properties. It is particularly preferred that substantially all acid dianhydride compounds have the structure of formula (2). Moreover, when using 2 or more types, they may be regularly arranged and may exist in a polyimide at random.

Specific examples of the acid dianhydride having an organic group represented by the formula (2) include 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and pyromellitic dianhydride. .

As other acid dianhydrides that can be used in combination with the acid dianhydride having an organic group represented by the formula (2), specifically, for example, ethylene tetracarboxylic dianhydride, butane tetracarboxylic dianhydride , Cyclobutanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 2,2 ′, 3,3′-benzophenonetetracarboxylic Acid dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, bis (3,4-di Carboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, bis (2, 3-Dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3 , 3-hexafluoropropane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 1,3-bis [ (3,4-dicarboxy) benzoyl] benzene dianhydride, 1,4-bis [(3,4-dicarboxy) benzoyl] benzene dianhydride, 2,2-bis {4- [4- (1, 2-dicarboxy) phenoxy] phenyl} propane dianhydride, 2,2-bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} propane dianhydride, bis {4- [4- ( 1,2-dicarboxy) phenoxy] R} ketone dianhydride, bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} ketone dianhydride, 4,4′-bis [4- (1,2-dicarboxy) phenoxy] Biphenyl dianhydride, 4,4′-bis [3- (1,2-dicarboxy) phenoxy] biphenyl dianhydride, bis {4- [4- (1,2-dicarboxy) phenoxy] phenyl} sulfone Anhydride, bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} sulfone dianhydride, bis {4- [4- (1,2-dicarboxy) phenoxy] phenyl} sulfide dianhydride Bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} sulfide dianhydride, 2,2-bis {4- [4- (1,2-dicarboxy) phenoxy] phenyl} -1 , 1,1,3,3,3 Hexaflupropane dianhydride, 2,2-bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} -1,1,1,3,3,3-propane dianhydride, 2 , 3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,2 , 3,4-benzenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7 , 8-phenanthrenetetracarboxylic dianhydride and the like.

These may be used alone or in combination of two or more. Among them, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1 1,1,3,3,3-hexafluoropropane dianhydride is preferred.

On the other hand, R ² in the formula (1) is a divalent organic group, and specific examples thereof include a divalent organic group corresponding to each diamine component described later, as described in the formula (3). That is, the structure which remove | eliminated the both terminal amino group which participates in formation of a polyimide chain from a diamine component is mentioned.

From the viewpoint of the linear expansion property and colorability of the resulting polyimide, a rigid diamine having an electron withdrawing group is preferably used. Examples of R ² of these diamines include those having a phenylene group or a biphenylene group, more preferably a biphenylene group in the formula (3), and a diamine having a structure of the formula (5) is particularly preferable.

R ³ in the formulas (3) and (5) is a monovalent organic group representing hydrogen, halogen, alkyl halide, or C1-C16 alkyl group. From the transparency, heat resistance, and dimensional stability of the resulting polyimide, an electron withdrawing group such as halogen or alkyl halide is preferred, and a fluorine atom or a fluoroalkyl group is more preferred. A fluoromethyl group, more preferably a trifluoromethyl group, is most preferred. A specific example of the most preferred diamine is 2,2′-bis (trifluoromethyl) benzidine.

Two or more diamines can be used in combination as long as the transparency of the polyimide can be ensured. Depending on the desired physical properties, it is preferable to use a diamine having the structure of formula (3), particularly formula (5), in an amount of 30 mol% or more, preferably 50 mol% or more of the entire diamine, and substantially all diamines. It is particularly preferred to use a diamine having the structure of formula (3). Moreover, when using 2 or more types, they may be regularly arranged and may exist in the polyimide at random.

Specific examples of diamines that can be used in combination with the diamine having the structure of the formula (3) include, for example, p-phenylenediamine, m-phenylenediamine, o-phenylenediamine, 3,3′-diaminodiphenyl ether, 3, 4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,4′-diaminodiphenylsulfone, 4,4′-diaminodiphenylsulfone, 3,3′-diaminobenzophenone, 4,4′-diaminobenzophenone, 3,4′-diaminobenzophenone, 3,3′-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,4 ' Diaminodiphenylmethane, 2,2-di (3-aminophenyl) propane, 2,2-di (4-aminophenyl) propane, 2- (3-aminophenyl) -2- (4-aminophenyl) propane, 2, 2-di (3-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 2,2-di (4-aminophenyl) -1,1,1,3,3,3- Hexafluoropropane, 2- (3-aminophenyl) -2- (4-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 1,1-di (3-aminophenyl)- 1-phenylethane, 1,1-di (4-aminophenyl) -1-phenylethane, 1- (3-aminophenyl) -1- (4-aminophenyl) -1-phenylethane, 1,3-bis (3-Aminophenoxy) Zen, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (3-amino) Benzoyl) benzene, 1,3-bis (4-aminobenzoyl) benzene, 1,4-bis (3-aminobenzoyl) benzene, 1,4-bis (4-aminobenzoyl) benzene, 1,3-bis (3 -Amino-α, α-dimethylbenzyl) benzene, 1,3-bis (4-amino-α, α-dimethylbenzyl) benzene, 1,4-bis (3-amino-α, α-dimethylbenzyl) benzene, 1,4-bis (4-amino-α, α-dimethylbenzyl) benzene, 1,3-bis (3-amino-α, α-ditrifluoromethylbenzyl) benzene, 1,3-bis (4-amino -Α, α-ditrifluoromethylbenzyl) benzene, 1,4-bis (3-amino-α, α-ditrifluoromethylbenzyl) benzene, 1,4-bis (4-amino-α, α-ditrifluoromethyl) Benzyl) benzene, 2,6-bis (3-aminophenoxy) benzonitrile, 2,6-bis (3-aminophenoxy) pyridine, 4,4′-bis (3-aminophenoxy) biphenyl, 4,4′- Bis (4-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] sulfide Bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [ 4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, 2,2-bis [4- (3 -Aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3 , 3,3-hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 1,3-bis [4- (3-Aminophenoxy) benzoyl] benzene, 1,3-bis [4- (4-aminophenoxy) benzoyl] benzene, 1,4-bis [4- (3-aminophenoxy) benzoyl] , 1,4-bis [4- (4-aminophenoxy) benzoyl] benzene, 1,3-bis [4- (3-aminophenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [ 4- (4-aminophenoxy) -α, α-dimethylbenzyl] benzene, 1,4-bis [4- (3-aminophenoxy) -α, α-dimethylbenzyl] benzene, 1,4-bis [4- (4-aminophenoxy) -α, α-dimethylbenzyl] benzene, 4,4′-bis [4- (4-aminophenoxy) benzoyl] diphenyl ether, 4,4′-bis [4- (4-amino-α) , Α-dimethylbenzyl) phenoxy] benzophenone, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] diphenylsulfone, 4,4′-bis [4- (4-amino Phenoxy) phenoxy] diphenylsulfone, 3,3′-diamino-4,4′-diphenoxybenzophenone, 3,3′-diamino-4,4′-dibiphenoxybenzophenone, 3,3′-diamino-4-phenoxybenzophenone 3,3′-diamino-4-biphenoxybenzophenone, 6,6′-bis (3-aminophenoxy) -3,3,3 ′, 3′-tetramethyl-1,1′-spirobiindane, 6,6 '-Bis (4-aminophenoxy) -3,3,3', 3'-tetramethyl-1,1'-spirobiindane, 1,3-bis (3-aminopropyl) tetramethyldisiloxane, 1,3- Bis (4-aminobutyl) tetramethyldisiloxane, α, ω-bis (3-aminopropyl) polydimethylsiloxane, α, ω-bis (3-aminobutyl) polydimethyl Siloxane, bis (aminomethyl) ether, bis (2-aminoethyl) ether, bis (3-aminopropyl) ether, bis (2-aminomethoxy) ethyl] ether, bis [2- (2-aminoethoxy) ethyl] Ether, bis [2- (3-aminoprotoxy) ethyl] ether, 1,2-bis (aminomethoxy) ethane, 1,2-bis (2-aminoethoxy) ethane, 1,2-bis [2- ( Aminomethoxy) ethoxy] ethane, 1,2-bis [2- (2-aminoethoxy) ethoxy] ethane, ethylene glycol bis (3-aminopropyl) ether, diethylene glycol bis (3-aminopropyl) ether, triethylene glycol bis (3-aminopropyl) ether, ethylenediamine, 1,3-diaminopropane, 1 4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11- Diaminoundecane, 1,12-diaminododecane, 1,2-diaminocyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, trans-1,4-diaminocyclohexane, 1,2-di (2-aminoethyl) ) Cyclohexane, 1,3-di (2-aminoethyl) cyclohexane, 1,4-di (2-aminoethyl) cyclohexane, bis (4-aminocyclohexyl) methane, 2,6-bis (aminomethyl) bicyclo [2.2.1] heptane, 2,5-bis (aminomethyl) bicyclo [2.2.1] hepta In addition, a diamine obtained by substituting some or all of the hydrogen atoms on the aromatic ring of the diamine with a substituent selected from a fluoro group, a methyl group, a methoxy group, a trifluoromethyl group, or a trifluoromethoxy group is also used. be able to.

Further, depending on the purpose, any one or more of ethynyl group, benzocyclobuten-4′-yl group, vinyl group, allyl group, cyano group, isocyanate group, and isopropenyl group serving as a crosslinking point may be used. Even if it introduce | transduces into some or all of the hydrogen atoms on the aromatic ring of diamine as a substituent, it can be used.

Although it is preferable to use the substituent R ³ introduced in the state of diamine, it may be introduced in the state of polyimide or polyamic acid. By introducing the substituent R ³ , the wavelength of light to be absorbed can be adjusted, and the transparency and coloring degree of the resulting film can be adjusted.

The aprotic polar solvent used in the present invention is a solvent having high polarity and no acidic hydrogen. The high polarity means that the dielectric constant is preferably 5 or more, for example. Specifically, for example, N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), hexamethylphosphorylamide, acetonitrile, acetone Solvents such as tetrahydrofuran can be used singly or as a mixture, preferably N, N-dimethylformamide (DMF) and N, N-dimethylacetamide (DMAc).

The total amount of the solvent other than the aliphatic carboxylic acid having 15 or less carbon atoms used in the present invention is preferably an aprotic polar solvent, but an aromatic solvent or an ether solvent may be used as an auxiliary solvent. Examples of the auxiliary solvent include xylene, toluene, benzene, diethylene glycol ethyl ether, 1,2-dimethoxyethane (monoglyme), diethylene glycol dimethyl ether (diglyme), 1,2-bis- (2-methoxyethoxy) ethane (triglyme), Bis- (2-methoxyethyl) ether, butyl cellosolve, butyl cellosolve acetate, propylene glycol methyl ether and propylene glycol methyl ether acetate. The auxiliary solvent can be used in an amount of less than 50% by weight of the aprotic polar solvent used, further less than 30% by weight, particularly less than 15% by weight.

The solid content concentration of the polyamic acid solution synthesized according to the present invention is preferably 5 to 50% by weight, more preferably 10 to 35% by weight from the viewpoint of handling.

The diamine compound and acid dianhydride used in the production of the polyamic acid solution of the present invention are preferably carried out in substantially the same amount (molar ratio), but when the diamine component is large, the viscosity of the resulting polyamic acid solution However, it is preferable that the amount (molar ratio) of the acid dianhydride is larger than that of the diamine compound. The monomer ratio of the diamine compound to the acid dianhydride is, for example, preferably 92.0 to 99.5 mol%, more preferably 95.0 to 99.0 mol%, with respect to 100 mol% of the acid anhydride component. . If the diamine component is too small, sufficient viscosity cannot be obtained, and the mechanical properties of the polyimide film synthesized from polyamic acid are unlikely to be sufficient.

The method for obtaining the polyamic acid can be obtained by mixing an amine component and an acid anhydride component. Stirring is preferably performed during mixing, and the time is preferably as short as possible without causing inconvenience in operation. For example, 10 minutes to 20 hours, further 10 minutes to 10 hours, particularly 15 minutes to 5 hours are preferable. In the present invention, it can be carried out within 15 minutes to 3 hours, and further within 1 hour.

As the mixing method of the amine component and the acid anhydride component, the method of adding the acid anhydride component to the amine component and the opposite method can be adopted, but the method of adding the acid anhydride component to the amine component is preferable. Each component may be added at once, or may be added in multiple portions.

In the production of the polyamic acid solution, the diamine compound and the acid dianhydride to be used may be added at once (including adding the whole amount in the other), for example, either one of them. A method may be used in which a prepolymer (precursor) is first produced without using all components, and the remaining components are added later. The ratio of the diamine compound and the acid dianhydride used in the production of the polyamic acid of the present invention is preferably the above-mentioned ratio. It is preferable to produce a polyamic acid by synthesizing and then sequentially adding the other monomer and adjusting the viscosity.

Among them, the method using a diamine compound later is preferable in terms of the storage stability of the polyamic acid obtained. The amount of the acid dianhydride or diamine compound used later is preferably 3 to 15 mol%, more preferably 4 to 10 mol%, based on the total amount of the acid dianhydride or diamine compound.

The reaction temperature of the polyamic acid synthesized according to the present invention is 0 to 35 ° C., preferably 3 to 30 ° C. When reaction temperature is low, reaction time may become long. Further, when the reaction temperature is high, the viscosity may not increase.

That is, in the present invention, the reaction temperature for synthesizing the polyamic acid is 0 to 35 ° C., and it is −0.5 × (the proportion of aliphatic carboxylic acid having 15 or less carbon atoms in the solvent (% by weight)). It is necessary to carry out at a temperature (° C) of +45 or less. Further, the temperature is preferably −0.5 × (ratio of aliphatic carboxylic acid having 15 or less carbon atoms in the solvent (% by weight)) + 40 or less (° C.).

Further, −1.0 × (ratio of aliphatic carboxylic acid having 15 or less carbon atoms in the solvent (% by weight)) + 15 or more, and further −1.0 × (aliphatic carboxylic acid having 15 or less carbon atoms in the solvent) Ratio (wt%)) + 20 or more, in particular, −1.0 × (ratio of aliphatic carboxylic acid having 15 or less carbon atoms in the solvent (wt%)) + temperature (° C.) of 25 or more. It is preferable in terms of

As a method for producing the polyimide film of the present invention, a polyamic acid which is a precursor is synthesized from an acid dianhydride and a diamine, a dehydration catalyst and an imidizing agent are added thereto, and cast or coated on a substrate. A technique for obtaining a polyimide film is typically mentioned. As a method of casting or coating, a method of casting or coating on an endless belt or a method of casting or coating on a substrate having a predetermined size can be employed. The method of imidizing by heating without using a dehydration catalyst or imidizing agent is not suitable for the purpose because the resulting film has poor linear expansion and dimensional stability.

In addition, it is difficult to obtain a polyimide film by controlling the linear expansion coefficient and dimensional stability by the method of immersing in a dehydration catalyst or imidizing agent, and the linear expansion coefficient and dimensional stability comparable to the inorganic material as in the present invention. It is difficult to obtain a film having properties.

By producing a polyimide film by polyimidizing using the polyamic acid solution obtained by the production method of the present invention, it is possible to obtain a polyimide film having good linear expansion coefficient and dimensional stability, and the resulting polyimide film is Since the linear expansion coefficient and dimensional stability are good, it is useful as a flexible substrate.

As the imidizing agent to be used, a tertiary amine can be used. As the tertiary amine, a heterocyclic tertiary amine is more preferable. Preferable specific examples of the heterocyclic tertiary amine include pyridine, 2,5-diethylpyridine, picoline, quinoline, isoquinoline and the like.

It has been found that the physical properties of the resulting polyimide film can be improved by changing the amount of the polyamic acid added to the carboxylic acid as the amount of the imidizing agent. That is, the greater the amount of imidizing agent added, the better the linear expansion coefficient and dimensional stability of the resulting film. On the other hand, if imidization proceeds too quickly with a large amount of imidizing agent, it becomes insoluble before filming and cannot be cast. Further, the acid anhydride is less affected by the amount than the imidizing agent, but if it is too much, there is a problem that the cast film is peeled off from the substrate, and the following preferred ranges can be exemplified respectively. .

In the present invention, as the molar amount of the imidizing agent added to the carboxylic acid of the polyamic acid is increased, the linear expansion coefficient and dimensional stability of the resulting film tend to be improved. On the other hand, if imidization proceeds too quickly with a large amount of imidizing agent, it becomes insoluble before filming, which causes problems such as inability to cast. 0.05 to 2.0 times molar equivalent, more preferably 0.1 to 1.5 times molar equivalent, and particularly preferably 0.3 to 1.0 times equivalent to the carboxylic acid group of the polyamic acid.

As the dehydration catalyst, acid anhydrides are preferred, and specific examples include acetic anhydride, propionic anhydride, n-butyric anhydride, benzoic anhydride, and trifluoroacetic anhydride, with acetic anhydride being the most preferred. preferable.
The physical properties of the obtained film do not change regardless of the amount of the dehydration catalyst added, but if the amount added is increased, the cast film tends to be peeled off from the substrate. From these tendencies, the addition amount of the dehydration catalyst is 0.6 to 10.0 times molar equivalent, more preferably 1.0 to 7.0 times molar equivalent, more preferably relative to the carboxylic acid group of the polyamic acid. Is preferably 3.0 to 5.0 times equivalent. In addition, the said preferable range of an imidation agent and a dehydration catalyst can be used in combination as appropriate.

When adding an imidizing agent or a dehydration catalyst to a polyamic acid solution, it may be added directly without dissolving in a solvent, or a solution dissolved in a solvent may be added. In the direct addition method, the reaction may rapidly proceed before the imidizing agent or the dehydration catalyst diffuses to form a gel. Preferably, the imidizing agent and the dehydration catalyst are dissolved in a solvent, and the solution is mixed with the polyamic acid solution.

After stirring for a predetermined time, a polyamic acid solution is obtained. It is preferable to add the imidizing agent and the dehydrating agent at a low temperature of 3 ° C. or lower, more preferably around 0 ° C., particularly 0 ° C. or lower. After adding an imidizing agent and a dehydrating agent, the solution is vigorously stirred and defoamed under vacuum or using a centrifugal precipitator or the like, and then applied and dried on a substrate such as glass or a film to form a coating film. For example, a polyimide coating film can be obtained by heating it to 300 ° C. or higher.

∙ Remove the polyamic acid solvent by heating and imidize. It is preferable that the heating conditions at this time are gradually heated from a low temperature to a high temperature. The maximum temperature is preferably in the range of 200 to 400 ° C. The heating atmosphere can be performed in air, under reduced pressure, or in an inert gas such as nitrogen. Moreover, you may combine those atmospheres.

The polyimide of the present invention synthesized in this way is characterized by low linear expansion and dimensional stability before and after heating. For example, when measuring these values by the tensile load method, a film sample of 15 mm × 5 mm When the weight is set to 3.0 g and measured at a heating rate of 10 ° C./min, a polyimide film having a linear thermal expansion coefficient of 40 ppm or less, preferably 20 ppm or less can be obtained. Further, by adjusting the amount of the imidizing agent, a polyimide film of 10 ppm or less, particularly 5 ppm or less can be obtained. Moreover, when heated from 40 ° C. to 230 ° C. and returned to 40 ° C. again, a polyimide film having a dimensional change rate before and after heating of 0.1% or less and further 0.05% or less can be obtained. Further, a polyimide film of 0.003% or less can be obtained by adjusting the amount of the imidizing agent.

The thickness of the polyimide film produced in the present invention is not particularly specified, but if it is too thin, the resulting film becomes difficult to handle. On the other hand, when the thickness is thick, it becomes difficult to remove the solvent by heating, and the outgas amount of the film increases. The film thickness is preferably 10 μm to 100 μm, more preferably 20 μm to 80 μm.

If the molecular weight of the polyamic acid is not high to some extent, the mechanical properties of the polyimide obtained as described above are unlikely to be sufficient. Polyamic acid is an unstable compound, and as a simple method instead of grasping the polymerization state by molecular weight measurement, a method of grasping the polymerization state from the viscosity of the obtained polyamic acid solution is used. The polymerization conditions are preferably determined so that the viscosity of the polyimide acid solution is 500 to 4500 poises at 23 ° C., more preferably 850 to 4000 poises, and particularly 1000 to 3500 poises. When the solution viscosity is high, handling becomes difficult, and when the solution viscosity is low, the mechanical properties of the polyimide film synthesized from the polyamic acid are not sufficient.

The solution viscosity of the prepolymer can be adjusted so that the viscosity at 23 ° C. is 1 to 200 poise, preferably 2 to 150 poise, particularly preferably 3 to 100 poise.

If the molecular weight of the polyimide constituting the polyimide film of the present invention is expressed by force, the weight average molecular weight is preferably in the range of 3,000 to 1,000,000, although it depends on its use, 5,000 The range is more preferably in the range of ˜500,000, and the range in the range of 10,000 to 500,000 is more preferable.

If the weight average molecular weight is too low, it is difficult to obtain sufficient strength when used as a coating film or film. Moreover, from the point that there is little coloring of a film, 5000 or more, Furthermore, 10,000 or more are preferable. On the other hand, when the weight average molecular weight is too high, the viscosity increases and the solubility in a solvent also decreases, so that it is difficult to obtain a coating film or film having a smooth surface and a uniform film thickness.

The molecular weight used here refers to a value in terms of polystyrene measured by gel permeation chromatography (GPC), and may be the molecular weight of the polyimide precursor itself, or acetic anhydride when the resulting polyimide is solvent soluble. The thing after performing a chemical imidation process by etc. may be sufficient.

The polyimide film of the present invention is characterized by having particularly excellent dimensional stability, but the original properties of the polyimide such as heat resistance and insulation are not impaired and are good.

The glass transition temperature is preferably as high as possible from the viewpoint of heat resistance, but in a differential scanning calorimeter, the glass transition temperature when measured at a temperature rising rate of 10 ° C./min is preferably 200 ° C. or higher. More preferably, it is good at 300 degreeC or more.

The polyimide film in the present invention is characterized by having the structure represented by the formula (6) as described in detail, but it is 85% or more of the number of repeating units of the polyimide film, more preferably 93% or more, especially It is preferable that 97% or more has a structure represented by the above formula. Most preferably, substantially all of the structure is represented by the above formula.

The polyimide film according to the present invention may be used as it is for a coating or forming process for producing a product or a member as it is, but it may be used as a laminate by further processing such as coating on a molded product formed into a film shape. I can do it. In order to provide a coating or molding process, the polyimide film is dissolved or dispersed in a solvent as necessary. Further, a light or thermosetting component, a non-polymerizable binder resin other than the polyimide film component according to the present invention, other A polyimide resin composition may be prepared by blending the components.

The resin composition can be formed using a polyimide obtained by imidizing a polyamic acid obtained by the method for producing a polyamic acid solution according to the present invention. In addition, various organic or inorganic low-molecular or high-molecular compounds may be blended in order to impart processing characteristics and various functionalities to the obtained resin composition. For example, dyes, surfactants, leveling agents, plasticizers, fine particles, sensitizers, and the like can be used. The fine particles include organic fine particles such as polystyrene and polytetrafluoroethylene, inorganic fine particles such as colloidal silica, carbon, and layered silicate, and these may have a porous or hollow structure. The function or form includes pigments, fillers, fibers, and the like.

The polyimide resin composition can be obtained by containing the polyimide represented by the formula (1) in the range of usually 5 to 99.9% by weight with respect to the entire solid content of the resin composition. The blending ratio of the components that can be blended as described above is preferably in the range of 0.1 wt% to 95 wt% with respect to the total solid content of the polyimide resin composition. When the amount is small, the effect of adding the additive is hardly exhibited, and when the amount is large, the characteristics of the resin composition are hardly reflected in the final product. In addition, solid content of a polyimide resin composition is all components other than a solvent, and a liquid monomer component is also contained in solid content.

The polyimide film according to the present invention can be used as a laminate by subjecting the film to a treatment such as coating. The material such as coating is preferably an inorganic material, and examples thereof include various inorganic thin films such as metal oxides and transparent electrodes. As a lamination method, various inorganic thin films such as a metal oxide and a transparent electrode can be formed on the polyimide film surface and used. The method for forming these inorganic thin films is not particularly limited, and for example, a PVD method such as a CVD method, a sputtering method, a vacuum deposition method, or an ion plating method can be used.

The polyimide film obtained in the present invention can obtain a polyimide film having a yellowness (YI) as compared with a polyimide film obtained without using an aliphatic carboxylic acid.

If the yellowness of the polyimide film obtained in the present invention is too high, it cannot be used for products such as displays that require transparency. The polyimide film according to the present invention is a polyimide film having a thickness of 45 μm to 55 μm and can be 20 or less, preferably 18 or less, particularly 17 or less. The lower haze of the polyimide film is also preferred for the same reason. Preferably, it may be 5.0% or less, more preferably 3.0% or less.

Since the polyimide film according to the present invention has high dimensional stability in addition to the original characteristics of polyimide such as heat resistance and insulation, fields and products in which these characteristics are effective, such as printed matter, color filters, etc. Suitable for forming flexible displays, semiconductor parts, interlayer insulating films, wiring coating films, optical circuits, optical circuit parts, antireflection films, holograms, optical members or building materials.

Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to these examples.

(Synthesis of precursor solution)
[Evaluation of linear thermal expansion coefficient and dimensional change rate before and after heating]
The linear thermal expansion coefficient of the film produced in the above-mentioned thermophysical property evaluation was measured with a thermomechanical analyzer Thermo Plus TMA8310 (manufactured by Rigaku Corporation) at a heating rate of 10 ° C./min and a tensile load of 3 g.

[Linear expansion coefficient]
It was measured by SMA Nano Technology Co., Ltd. TMA (Thermal Mechanical Analysis) / SS120CU. A film piece having a length of 10 mm, a width of 4 mm, and a film thickness of about 40 μm was used as a test shape, and a load of 3 gf was applied and measurement was performed at a temperature rising rate of 5 ° C./min. The linear expansion coefficient was determined from the amount of change of the film piece per unit temperature at 100 ° C. to 200 ° C.

[Viscosity measurement]
The solution viscosity at 23 ° C. was measured using an E-type viscometer RE550 manufactured by Toki Sangyo Co., Ltd.
Measurement time is 15 minutes, 30 minutes, 40 minutes, 60 minutes, 80 minutes, 100 minutes, 2 hours, 3 hours, 4 hours, 24 hours, 48 hours, 72 hours after adding monomer to the precursor solution. The later viscosity was measured.

[Tensile properties]
According to ISO527, the test piece (type 2) was measured at a tensile speed of 20 mm / min.

[Total light transmittance and haze measurement]
The haze and total light transmittance of the film were measured using NDH-300A manufactured by Nippon Denshoku Industries Co., Ltd.

[YI (yellowness) measurement]
The YI of the film was measured using NR-3000 manufactured by Nippon Denshoku Industries Co., Ltd.

Example 1
In a 500 ml separable flask, 22.2 g (69.1 mmol) of 2,2′-bis (trifluoromethyl) benzidine was charged, dissolved in 175 g of dimethylacetamide (DMAc), and stirred in a 25 ° C. water bath. 3,3 ′, 4,4′-BPDA (22.4 g, 73.4 mmol) was added thereto, and the mixture was stirred at room temperature for 3 hours to obtain a uniform solution. The precursor solution 1 was obtained by stirring. The solution viscosity of the precursor solution 1 at 23 ° C. was 6 poise.

Furthermore, a solution prepared by dissolving 1.1 g (3.4 mmol) of 2,2′-bis (trifluoromethyl) benzidine in 6 g of DMAc was added to the precursor solution 1. The solution viscosity after the 2,2′-bis (trifluoromethyl) benzidine solution was added to the precursor solution 1 was traced with an E-type viscometer, and the difference between the previously measured viscosity and the next measured viscosity was ± The time when it was within 100 poise was taken as the polymerization time. The solution viscosity of the polyamic acid solution 1 thus obtained at 23 ° C. was 2660 poise, and the time until the final reached viscosity was 4.0 h. Moreover, solid content concentration was 18.0 weight%.

After cooling 35 g of this polyamic acid solution 1 to around 0 ° C., 1.4 g (15.5 mmol) of β-picoline and 9.5 g (92.7 mmol) of acetic anhydride were added and mixed. After defoaming under vacuum, it was cast on a polyethylene naphthalate film and dried with hot air at about 50 ° C. for about 10 minutes, at about 100 ° C. for about 10 minutes, and at about 200 ° C. for about 10 minutes. . Then, it heated at about 300 degreeC under nitrogen atmosphere for 1 hour, and the polyimide film 1 was obtained. The polyimide film 1 had a thickness of 50 μm, a linear expansion coefficient (100-200 ° C.) of 1.2 ppm, a total light transmittance of 87%, a haze of 2.0%, and a yellowness of 16.

(Example 2)
In a 500 ml separable flask, 22.0 g (68.6 mmol) of 2,2′-bis (trifluoromethyl) benzidine was charged, dissolved in 170 g of dimethylacetamide (DMAc), and stirred in a 25 ° C. water bath. Thereto, 22.4 g (76.3 mmol) of 3,3 ′, 4,4′-BPDA was added and stirred at room temperature for 3 hours to obtain a homogeneous solution, followed by addition of 38.0 g of acetic acid and 1 hour in a water bath. The precursor solution 2 was obtained by stirring. The solution viscosity at 23 ° C. of the precursor solution was 7 poise.

Further, to this precursor solution 2, a solution prepared by dissolving 2.1 g (6.5 mmol) of 2,2′-bis (trifluoromethyl) benzidine in 7 g of DMAc was added. The polymerization time was measured in the same manner as in Example 1. The solution viscosity at 23 ° C. of the polyamic acid solution 2 was 2130 poise, and the time until the final viscosity reached 120 minutes. The solid content concentration was 18.2% by weight.

After cooling 40 g of the polyamic acid solution 2 to around 0 ° C., 1.6 g (17.6 mmol) of β-picoline and 10.8 g (105.7 mmol) of acetic anhydride were added and mixed. A polyimide film 2 was obtained in the same manner as in Example 1. The polyimide film 2 had a thickness of 49 μm, a linear expansion coefficient (100-200 ° C.) of 0.9 ppm, a total light transmittance of 87%, a haze of 1.9%, and a yellowness of 16.1.

(Example 3)
In a 500 ml separable flask, 22.0 g (68.6 mmol) of 2,2′-bis (trifluoromethyl) benzidine was charged, dissolved in 160 g of dimethylacetamide (DMAc), and stirred in a 25 ° C. water bath. Thereto, 22.4 g (76.3 mmol) of 3,3 ′, 4,4′-BPDA was added and stirred at room temperature for 3 hours to obtain a homogeneous solution. The precursor solution 3 was obtained by stirring for 1 hour. The solution viscosity of the precursor solution 3 at 23 ° C. was 7 poise.

Further, a solution prepared by dissolving 2.1 g (6.5 mmol) of 2,2′-bis (trifluoromethyl) benzidine in 7 g of DMAc was added to the precursor solution 3. The solution viscosity after the 2,2′-bis (trifluoromethyl) benzidine solution was added to the precursor solution 3 was traced with an E-type viscometer, and the difference between the previously measured viscosity and the next measured viscosity was ± The time when it was within 100 poise was taken as the polymerization time. The solution viscosity at 23 ° C. of the polyamic acid solution 3 was 2130 poise, and the time until the final reached viscosity was 100 minutes.

After cooling 80 g of this polyamic acid solution 3 to around 0 ° C., 3.3 g (35.4 mmol) of β-picoline, 17.9 g (175.3 mmol) of acetic anhydride and 6.8 g of DMAc were added and mixed. After degassing under vacuum, polyimide film 3 was obtained by drying with hot air at 90 ° C. for 10 minutes, 150 ° C. for 10 minutes, 200 ° C. for 10 minutes, and 300 ° C. for 10 minutes. The polyimide film 3 had a thickness of 49 μm, a linear expansion coefficient (100-200 ° C.) of 0.0 ppm, a total light transmittance of 87%, a haze of 1.8%, and a YI of 15.8.

Example 4
To a 500 mL separable flask, 23.3 g (72.8 mmol) of 2,2′-bis (trifluoromethyl) benzidine was added, dissolved in 162 g of dimethylacetamide (DMAc), and stirred in a 25 ° C. water bath. Thereto, 23.0 g (78.2 mmol) of 3,3 ′, 4,4′-BPDA was added and stirred at room temperature for 3 hours to obtain a homogeneous solution, followed by addition of 50 g of acetic acid and 1 hour in a 25 ° C. water bath. The precursor solution 4 was obtained by stirring. The solution viscosity at 23 ° C. of the precursor solution 4 was 8 poise.

Further, a solution prepared by dissolving 2,2′-bis (trifluoromethyl) benzidine 1.4 (4.4 mmol) in 6 g of DMAc was added to the precursor solution 4. The polymerization time was measured in the same manner as in Example 1. The solution viscosity at 23 ° C. of the polyamic acid solution 4 thus obtained was 2020 poise, and the time until the final reached viscosity was 45 minutes.

After cooling 80 g of this polyamic acid solution 4 g to around 0 ° C., 3.3 g (35.4 mmol) of β-picoline, 17.9 g (175.3 mmol) of acetic anhydride and 6.8 g of DMAc were added and mixed. A polyimide film 4 was obtained in the same manner as in Example 1. The thickness of the polyimide film 4 is 48 μm, the linear expansion coefficient (100-200 ° C.) is −1.7 ppm, the thermal hysteresis is 0.6 μm, the total light transmittance is 87%, the haze is 1.9%, and the YI is 15 .8.

(Example 5)
In a 2 L separable flask, 69.9 g (0.22 mol) of 2,2′-bis (trifluoromethyl) benzidine was added, dissolved in 475 g of dimethylacetamide (DMAc), and stirred in a 25 ° C. water bath. 3,3 ′, 4,4′-BPDA (69.0 g, 0.23 mol) was added thereto, and the mixture was stirred at room temperature for 3 hours to obtain a homogeneous solution. The precursor solution 5 was obtained by stirring. The solution viscosity at 23 ° C. of the precursor solution 5 was 13 poise.

Furthermore, a solution prepared by dissolving 3.8 g (11.9 mmol) of 2,2′-bis (trifluoromethyl) benzidine in 13 g of DMAc was added to the precursor solution 5. The polymerization time was measured in the same manner as in Example 1. The solution viscosity at 23 ° C. of the polyamic acid solution 5 thus obtained was 2030 poise, and the time until the final reached viscosity was 30 minutes.

After cooling 80 g of the polyamic acid solution 5 to about 0 ° C., 3.3 g (35.4 mmol) of β-picoline, 17.9 g (175.3 mmol) of acetic anhydride and 6.8 g of DMAc were added and mixed. After degassing under vacuum, polyimide film 5 was obtained by drying with hot air at 90 ° C. for 10 minutes, 150 ° C. for 10 minutes, 200 ° C. for 10 minutes, and 300 ° C. for 10 minutes. The polyimide film 5 has a thickness of 47 μm, a linear expansion coefficient (100-200 ° C.) of 0.0 ppm, a thermal hysteresis of 0.1 μm, a total light transmittance of 87%, a haze of 2.0%, and a YI of 15. It was 8.

(Comparative Example 1)
In a 500 ml separable flask, 22.0 g (68.6 mmol) of 2,2′-bis (trifluoromethyl) benzidine was charged, dissolved in 127 g of dimethylacetamide (DMAc), and stirred in an ice water bath at about 5 ° C. . Thereto, 22.4 g (76.3 mmol) of 3,3 ′, 4,4′-BPDA was added and stirred at room temperature for 3 hours to obtain a homogeneous solution, followed by addition of 55.0 g of acetic acid and 1 hour in a water bath. The precursor solution 6 was obtained by stirring. The solution viscosity of the precursor solution 6 at 23 ° C. was 42 poise.

Further, a solution prepared by dissolving 1.7 g (5.3 mmol) of 2,2′-bis (trifluoromethyl) benzidine in 1.2 g of DMAc was added to the precursor solution 6. The polymerization time was measured in the same manner as in Example 1. The solution viscosity at 23 ° C. of the polyamic acid solution 6 thus obtained was 2900 poise, and the time until the final reached viscosity was 30 minutes. Moreover, solid content concentration was 20.1 weight%. After cooling 80 g of the above polyamic acid solution 6 to about 0 ° C., 3.3 g (35.4 mmol) of β-picoline, 17.9 g (175.3 mmol) of acetic anhydride and 6.8 g of DMAc were added and mixed. A polyimide film 6 was obtained in the same manner as in Example 1. The polyimide film 6 had a thickness of 50 μm, a linear expansion coefficient (100-200 ° C.) of 2.0 ppm, a total light transmittance of 87%, a haze of 2.0%, and a YI of 16.

(Comparative Example 2)
In a 500 ml separable flask, 21.4 g (66.8 mmol) of 2,2′-bis (trifluoromethyl) benzidine was charged, dissolved in 196 g of dimethylacetamide (DMAc), and stirred in a 25 ° C. water bath. Thereto, 21.0 g (71.4 mmol) of 3,3 ′, 4,4′-BPDA was added and stirred for 4 hours in a water bath to obtain a precursor solution 7. The solution viscosity at 23 ° C. of the precursor solution 7 was 5 poise.

Furthermore, a solution prepared by dissolving 2,2′-bis (trifluoromethyl) benzidine 1.2 (3.8 mmol) in 1.4 g of DMAc was added to the precursor solution 7. The polymerization time was measured in the same manner as in Example 1. The time required to reach the final viscosity of the polyamic acid solution 7 thus obtained was 72 hours. The solution viscosity at 23 ° C. was 2620 poise, and the solid content concentration was 18.0% by weight. After cooling 80 g of this polyamic acid solution 7 to about 0 ° C., 3.3 g (35.4 mmol) of β-picoline, 17.9 g (175.3 mmol) of acetic anhydride and 6.8 g of DMAc were added and mixed. A polyimide film 7 was obtained in the same manner as in Example 1. The polyimide film 7 had a thickness of 47 μm, a linear expansion coefficient (100-200 ° C.) of 0.3 ppm, a total light transmittance of 87%, a haze of 3%, and a YI of 17.4.

(Comparative Example 3)
In a 500 ml separable flask, 22.0 g (68.6 mmol) of 2,2′-bis (trifluoromethyl) benzidine was charged, dissolved in 165 g of dimethylacetamide (DMAc), and stirred in a water bath at 40 ° C. Thereto, 22.4 g (76.1 mmol) of 3,3 ′, 4,4′-BPDA was added and stirred at room temperature for 3 hours to obtain a homogeneous solution, followed by addition of 42.4 g of acetic acid and 1 hour in a water bath. The precursor solution 8 was obtained by stirring. The solution viscosity of the precursor solution 8 at 23 ° C. was 6 poise.

Furthermore, a solution prepared by dissolving 2.1 g (6.4 mmol) of 2,2′-bis (trifluoromethyl) benzidine in 4.9 g of DMAc was added to the precursor solution 8. The polymerization time was measured in the same manner as in Example 1. The time required to reach the final viscosity of the polyamic acid solution 8 thus obtained was 40 minutes. The solution viscosity at 23 ° C. was 800 poise, and the solid content concentration was 18.0% by weight. An attempt was made to obtain a polyimide film by the same operation as in Example 1, but the polyamide acid solution had a low viscosity and could not be formed.

(Comparative Example 4)
In a 500 ml separable flask, 22.0 g (68.6 mmol) of 2,2′-bis (trifluoromethyl) benzidine was charged, dissolved in 127 g of dimethylacetamide (DMAc), and stirred in a 25 ° C. water bath. Thereto, 22.4 g (76.1 mmol) of 3,3 ′, 4,4′-BPDA was added and stirred at room temperature for 3 hours to obtain a homogeneous solution, followed by addition of 55.0 g of acetic acid and 1 hour in a water bath. The precursor solution 9 was obtained by stirring. The solution viscosity of the precursor solution 9 at 23 ° C. was 42 poise.

Furthermore, a solution prepared by dissolving 1.6 g (5.0 mmol) of 2,2′-bis (trifluoromethyl) benzidine in 2.3 g of DMAc was added to the precursor solution 9. The polymerization time was measured in the same manner as in Example 1. The time until the final reached viscosity of the polyamic acid solution 9 thus obtained was 2 hours. The solution viscosity at 23 ° C. was 1100 poise, and the solid content concentration was 20.0% by weight. An attempt was made to obtain a polyimide film by the same operation as in Example 1, but the polyamide acid solution had a low viscosity and could not be formed.

From the results of Table 1, when no aliphatic carboxylic acid is used, it takes a long time to complete the viscosity increase from the low-viscosity polyamic acid (Comparative Example 2). In addition, when an aliphatic carboxylic acid was used and the polymerization temperature was 40 ° C., the viscosity of the final polyamic acid was almost the same as that of Examples 1 and 2 / Comparative Example 1 and the monomer composition. It does not reach a sufficiently high solution viscosity (Comparative Example 3).

Furthermore, when the polymerization temperature is 25 ° C. using 30% aliphatic carboxylic acid, a polyamic acid having a sufficiently high viscosity cannot be obtained (Comparative Example 4), whereas the aliphatic carboxylic acid in the present invention is not obtained. It can be seen that when the reaction is carried out at 0.5 or more and less than 29% by weight and at 25 ° C., a polyamic acid solution having a sufficiently high viscosity of 2000 poise or more can be synthesized within 4 hours. Furthermore, it can be seen that the viscosity is not lowered after the polyamic acid solution is stored at 0 ° C. for 200 hours, and the storage stability is excellent.

The polyimide film thus obtained has substantially the same expansion coefficient, thickness, transmittance and haze as when no aliphatic carboxylic acid is used. Further, the yellowness (YI) is improved as compared with the case where no aliphatic carboxylic acid is used. Thus, a polyimide film with improved physical properties can be obtained by using an aliphatic carboxylic acid in combination as a polymerization solvent.

In addition, the glass transition temperature (Tg) of the polyimide films obtained in Examples and Comparative Examples was measured. Since DSC Q200 manufactured by TS Instruments was used and measured at a heating rate of 10 ° C./min and no peak corresponding to Tg was observed up to 400 ° C., the Tg of the obtained polyimide film was Was also found to be at least 400 ° C. or higher.

The molecular weight of the polyamic acid obtained in the examples was measured using gel permeation chromatography. Dimethylformamide was used as a developing solvent, polystyrene was used as a standard sample, and Shodex, one KD-G, two KD-806M, and one KD-801 were connected in series to a Tosoh RI8020 column as a detector. The measurement was performed at a measurement temperature of 40 ° C. As a result, it was confirmed that all the polyamic acids of the examples had a weight average molecular weight of 3000 or more.

[Evaluation of dimensional change rate before and after heating]
The film produced in the example was heated to 230 ° C. at a temperature increase rate of 10 ° C./min with a thermomechanical analyzer Thermo Plus TMA8310 (manufactured by Rigaku Corporation), and then cooled to 40 ° C. at the same rate. The measurement was performed (dimension 1), and the dimensions were measured in the state of being cooled to 230 ° C. and superheated to 40 ° C. (dimension 2). As a result of comparing the dimension 1 and the dimension 2 and evaluating the dimensional change rate of the film, all the films showed a shrinkage ratio before and after heating of 0.05% or less. That is, it was found that the dimensional change rate before and after heating was 0.005% or less.

Since the polyimide film of the present invention thus produced has good heat resistance and can produce a film having an arbitrary low expansion coefficient and dimensional stability, these characteristics are considered to be effective. Fields and products such as paints, printing inks, color filters, flexible display films, semiconductor devices, electronic components, interlayer insulation films, wiring coating films, optical circuits, optical circuit components, antireflection films, holograms, etc. Suitable for forming optical members or building materials.

Claims (26)

1. A method for producing a polyamic acid solution containing a repeating unit represented by the following formula (1) by polymerizing a diamine compound and an acid dianhydride using a mixture of an aprotic polar solvent and an aliphatic carboxylic acid having 15 or less carbon atoms as a solvent. Yes, the proportion of the aliphatic carboxylic acid having 15 or less carbon atoms in the solvent is 0.5 or more and less than 29% by weight, and the polymerization temperature is 0 to 35 ° C. and −0.5 × (15 or less carbon atoms in the solvent) The ratio of the aliphatic carboxylic acid (% by weight)) The process for producing a polyamic acid solution containing a repeating unit represented by the following formula (1) is polymerized at a temperature of 45 or less.
   

   

   (In the formula, R ¹ represents a tetravalent organic group, and R ² represents a divalent organic group.)
2. The method for producing a polyamic acid solution according to claim 1, wherein R ¹ is an acid dianhydride residue containing a substituted or unsubstituted aromatic group.
3. R ² has at least one aromatic group and at least one of them has a substituent, or has a plurality of aromatic groups and is bonded with a branched or straight chain alkyl group. Item 2. A method for producing a polyamic acid solution according to Item 1.
4. 4. The method for producing a polyamic acid solution according to claim 3, wherein the substituent of R ² is selected from an alkyl group having 1 to 16 carbon atoms, a halogenated alkyl group having 1 to 16 carbon atoms, and a halogen.
5. The method for producing a polyamic acid solution according to claim 2, wherein R ¹ is a tetravalent organic group selected from the following general formula (2).
   

   
6. The method for producing a polyamic acid solution according to claim 3, wherein R ² is a divalent organic group selected from the following general formula (3).
   

   

   (R ³ represents an alkyl group having 1 to 16 carbon atoms, a halogenated alkyl group having 1 to 16 carbon atoms, or halogen).
7. The method for producing a polyamic acid solution according to claim 2, wherein R ¹ is a tetravalent organic group represented by the following general formula (4).
   

   
8. The method for producing a polyamic acid solution according to claim 3, wherein the structure of R ^{2 is} a divalent biphenylene group selected from the following general formula (5).
   

   

   (R ³ represents an alkyl group having 1 to 16 carbon atoms, a halogenated alkyl group having 1 to 16 carbon atoms, or halogen).
9. The method for producing a polyamic acid solution according to claim 8, wherein R ³ is halogen or an alkyl halide.
10. The method for producing a polyamic acid solution according to claim 8, wherein R ³ is a fluoroalkyl group having 1 to 16 carbon atoms.
11. It is a manufacturing method of the polyimide film containing the repeating unit represented by Formula (6), and it casts on the support body the solution which mixed the dehydration catalyst and the imidizing agent with the polyamic acid obtained in Claim 1. A method for producing a polyimide film, characterized by comprising:
    

    

    In the formula, R ¹ represents a tetravalent organic group selected from the following general formula (2), R ² represents a divalent organic group selected from the following general formula (3),
    

    

    

    In the formula, R ³ represents hydrogen, halogen, alkyl halide, or a C1-C16 alkyl group.
12. The method for producing a polyimide film according to claim 11, wherein the structure of R ^{1 is} a tetravalent organic group selected from the following general formula (4).
    

    
13. The method for producing a polyimide film according to claim 11, wherein the structure of R ^{2 is} a divalent organic group biphenylene group or phenylene group selected from the following general formula (5).
    

    

    In the formula, R ³ represents hydrogen, halogen, alkyl halide, or a C1-C16 alkyl group.
14. The method for producing a polyimide film according to claim 13, wherein R ³ is halogen or alkyl halide.
15. The method for producing a polyimide film according to claim 13, wherein R ³ is a trifluoromethyl group.
16. The method for producing a polyimide film according to claim 11, wherein the imidizing agent is selected from pyridine, picoline, quinoline, or isoquinoline, and the dehydration catalyst is selected from acid anhydrides such as acetic anhydride.
17. The method for producing a polyimide film according to claim 16, wherein the addition amount of the amine compound is 0.05 molar equivalent or more with respect to the carboxylic acid of the polyamic acid.
18. The polyimide film produced by the method according to any one of claims 1 to 17, having a linear thermal expansion coefficient of 40 ppm or less and a shrinkage ratio before and after heating of 0.1% or less.
19. The polyimide film according to any one of claims 1 to 17, which has a glass transition temperature of 200 ° C or higher.
20. The polyimide film according to any one of claims 1 to 17, which has a weight average molecular weight of 3,000 or more.
21. A polyimide resin composition using the polyimide film according to claim 18.
22. A polyimide resin composition using the polyimide film according to claim 19.
23. A polyimide resin composition using the polyimide film according to claim 20.
24. A laminate comprising at least one layer of an inorganic material laminated on the polyimide film according to claim 18.
25. A laminate comprising at least one layer of an inorganic material laminated on the polyimide film according to claim 19.
26. A laminate comprising at least one layer of an inorganic material laminated on the polyimide film according to claim 20.