JP2011111596A - Manufacturing method of polyimide film, and polyimide film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a polyimide film which is transparent and satisfies both a low linear expansion and a low birefringence by fabricating a specific aromatic acid dianhydride and a specific diamine by a specific fabrication method; and to further provide a product using the polyimide film to form a product or a member requiring the transparency and the heat resistance and a low linear thermal expansion coefficient and a low birefringence. <P>SOLUTION: The manufacturing method of a polyimide film includes mixing a polyamic acid obtained by reacting at least two polyamide acids having specific structures, with a dehydration catalyst and an imidization agent, and allowing the mixture to react. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a polymer compound that is transparent, has low linear expansion, and is excellent in low birefringence. Preferably, the polyimide film can be suitably used as a material (for example, a liquid crystal display device) for forming a product or member that has a high requirement for heat resistance and low linear expansion and low birefringence. The manufacturing method of this, the polyimide obtained by the said manufacturing method, the resin composition containing the said polyimide, and the articles | goods produced using the said resin 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. By changing this glass material to a film material, the panel itself can be made thinner and lighter. . However, the formation of these electronic devices requires a high temperature process, and there has been no film material that can withstand this.

  Since polyimide has high insulation performance as well as heat resistance, it has been applied to semiconductors and electronic components. Therefore, it is often laminated with metals such as single crystal silicon and copper, and attempts have been made to solve the warpage of the laminated substrate by reducing the thermal expansion coefficient of polyimide to the same level as single crystal silicon and metal. It was.

  When polyimide is used as an optical material, low birefringence is also an important characteristic in order not to cause polarization dependency of optical components.

  The chemical structure is a factor that greatly affects the physical properties of such polyimide. Generally, it is said that the higher the polymer chain of polyimide and the higher the linearity, the lower the coefficient of thermal expansion. To reduce the coefficient of thermal expansion, various structures are proposed for both acid dianhydride and diamine, which are polyimide raw materials. It has been.

  However, the coefficient of thermal expansion and birefringence are in a trade-off relationship, and the higher the rigidity and linearity of the polyimide polymer chain, the lower the coefficient of thermal expansion and the higher the birefringence. Known to. For example, in Patent Document 1, a polyimide film made of 4-amino-2-methylphenyl-4′-aminobenzoate and pyromellitic dianhydride showed a low coefficient of linear expansion of 0.8 ppm / K, but birefringence. Shows a high value of 0.196.

JP2007-112990

  The present invention has been accomplished in view of the above circumstances, and an object of the present invention is to obtain a polyimide having both transparency and heat resistance, as well as low thermal expansion and low birefringence. 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.

  The present invention has the following configuration.

  1). A dehydration catalyst and imidation are carried out on a polyamic acid obtained by reacting a compound represented by the following formula (1) and a compound represented by the following formula (2), or a compound represented by the following formula (3) and a compound represented by the following formula (4). A method for producing a polyimide film, which is prepared by casting a solution mixed with an agent on a support.

Where n represents the number of repeating units,

In the formula, m represents a repeating unit and is an integer smaller than n, and R _{2 in the} formulas (1) and (2) may not necessarily be the same,

Where o represents the number of repeating units,

In the formula, p represents the number of repeating units and is an integer smaller than o, and R _{2 in the} formulas (3) and (4) may not necessarily be the same.

R _{1 in the} above formula represents a tetravalent organic group selected from the following general formula (5), and R ₂ represents a divalent organic group selected from the following general formula (6).

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

2). As a repeating unit represented by the formula (2) or (4), the structure of R ₁ is the following general formula (7).

3). As the repeating unit represented by the formula (1), (2), (3) or (4), the structure of R ₂ is a divalent organic group selected from the following general formula (8). The manufacturing method of the polyimide film as described in 1) or 2).

4). The method for producing a polyimide film according to any one of 1) to 3), wherein R ₃ is halogen or alkyl halide.

5). The process for producing a polyimide film as described in any of 1) to 4), characterized in that R ₃ is a trifluoromethyl group.

  6). The polyamic acid obtained by reacting the above formulas (1) and (2) or the above formulas (3) and (4) is imidized by using an imidizing agent and a dehydrating catalyst. The manufacturing method of the polyimide film in any one of 5).

  7). 6. The method for producing a polyimide film according to 6), wherein the imidizing agent is a tertiary amine.

  8). The method for producing a polyimide film according to 6) or 7), wherein the dehydration catalyst is an acid anhydride.

  9). The method for producing a polyimide film according to any one of 6) to 8), wherein the imidizing agent is used in an amount of 0.01 molar equivalent or more with respect to the carboxylic acid of the polyamic acid.

  10). The method for producing a polyimide film according to any one of 6) to 9), wherein the dehydration catalyst is used in an amount of 0.05 molar equivalent or more relative to the carboxylic acid of the polyamic acid.

  11). The method for producing a polyimide film according to any one of 1) to 10), wherein the polyamic acid has a weight average molecular weight of 3,000 or more.

  12). The polyimide film manufactured by the method in any one of 1) thru | or 11) whose linear thermal expansion coefficient is 40 ppm / K or less.

  13). The polyimide film as described in 12), wherein the birefringence is 0.1 or less.

  14). The polyimide film according to 12) or 13), which has a glass transition temperature of 200 ° C. or higher.

  15). A polarizing plate comprising an optical film and a polarizer, wherein the optical film is a polyimide film according to any one of 11) to 14).

  16). A liquid crystal panel in which an optical member is disposed on at least one surface of a liquid crystal cell, wherein the optical member is the polyimide film according to any one of 11) to 14).

  17). A liquid crystal panel in which an optical member is disposed on at least one surface of a liquid crystal cell, wherein the optical member is a polarizing plate described in 15).

  18). A liquid crystal display device including a liquid crystal panel, wherein the liquid crystal panel is a liquid crystal panel according to 17).

  The resin composition containing the polyimide according to the present invention has a partially disturbed molecular orientation and birefringence by partially introducing a more rigid polymer chain into a rigid and highly linear polymer chain. Has a characteristic that low CTE can be maintained by the introduced rigid polymer chain.

  Moreover, since the resin composition containing the polyimide according to the present invention is excellent in low linear expansion and low birefringence in addition to transparency and heat resistance, it has heat resistance and low expansion (dimensional stability). Suitable for films and coatings for all known members that require low birefringence, such as printed materials, color filters, flexible displays, semiconductor parts, interlayer insulation films, wiring coating films, optical circuits Use as an optical circuit component, an antireflection film, a hologram, an optical member, a building material or a structure is expected.

The present invention is described in detail below.
The polyimide produced by the present invention is a polyimide derived from polyamic acid obtained by reacting the above formula (1) and the above formula (2), or the above formula (3) and the above formula (4). R _{1 in} formula (2) or formula (4) is a structure obtained by removing both terminal acid anhydride groups involved in the formation of the polyimide chain from the acid dianhydride component, and has the structure represented by formula (5) It is.

  Of the tetravalent organic groups listed in the formula (5), a structure having a phenylene group is particularly preferable from the viewpoint of the rigidity exhibited by the obtained polymer and the availability of raw materials. In this case, the acid dianhydride used for producing the formula (2) or the formula (4) is preferably pyromellitic dianhydride, respectively.

  In the formula (1) and the formula (2), or in the formula (3) and the formula (4), the reaction rate of the terminal functional group is 90% or more, more preferably 95% or more, and particularly 98% or more. It is preferable to mix and react. It is most desirable to react substantially all. When the terminal reaction rate is low, the molecular orientation is not disturbed, and it is difficult to exert the effect of lowering the birefringence.

In the structure derived from the acid dianhydride component of the polyimide film of the present invention, the structure represented by R ₁ is 1 to 30 mol%, more preferably 3 to 25 mol%, particularly 5 to 20 mol%. preferable.

If the transparency of the polyimide can be ensured, two or more types of acid dianhydrides are used in combination in order to form the structure of R ₁ in formula (2) or formula (4). be able to.

  Other acid dianhydrides that can be used in combination with the above formula (5) include, for example, ethylenetetracarboxylic dianhydride, butanetetracarboxylic dianhydride, cyclobutanetetracarboxylic dianhydride, cyclopentanetetracarboxylic acid Anhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 2,2 ′, 3,3′-benzophenone tetracarboxylic dianhydride, 2,2-bis (3,4-di Carboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxy) Phenyl) 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] phenyl} ketone dianhydride Bis (4- [3- (1,2-di Ruboxy) phenoxy] phenyl} ketone dianhydride, 4,4′-bis [4- (1,2-dicarboxy) phenoxy] biphenyl dianhydride, 4,4′-bis [3- (1,2-di) Carboxy) phenoxy] biphenyl dianhydride, bis {4- [4- (1,2-dicarboxy) phenoxy] phenyl} ketone dianhydride, bis {4- [3- (1,2-dicarboxy) phenoxy] Phenyl} ketone dianhydride, bis {4- [4- (1,2-dicarboxy) phenoxy] phenyl} sulfone dianhydride, 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} sulfi 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, 1,4,5,8-naphthalenetetracarboxylic Acid dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic acid Anhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic dianhydride and the like can be mentioned.

  These may be used alone or in admixture of two or more with the acid dianhydride represented by the formula (5). As particularly preferred tetracarboxylic dianhydrides, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, 2,2- Bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride is mentioned.

On the other hand, R ₂ in the formula (1), (2), (3) or (4) is a divalent organic group, and specific examples thereof include a divalent organic group corresponding to each diamine component described later. That is, the structure shown by Formula (6) which remove | eliminated the both terminal amino group which participates in formation of a polyimide chain from a diamine component is mentioned. Of the formula (6), a phenylene group or a biphenylene group is preferable. In this case, the diamines used for producing the formula (1), (2), (3) or (4) are a diamine having a phenylene group and a diamine having a biphenylene group, respectively.

R ₃ in the formula (6) is a monovalent organic group that represents a halogen, an alkyl halide, or a C1-C16 alkyl group. In view of the transparency, heat resistance and dimensional stability of the resulting polyimide, an electron withdrawing group such as halogen or halogenated alkyl is preferred, a fluorine atom or a trifluoromethyl group is more preferred, and a trifluoromethyl group is particularly preferred.

As for the diamine, a rigid diamine having an electron withdrawing group is preferably used because of the linear expansion and colorability of the resulting polyimide. R ₂ is preferably a phenylene group, a biphenylene group or even a biphenylene group in the formula (6). Of these, diamines having a trifluoromethyl group are preferred. The most preferred specific compound is 2,2′-bis (trifluoromethyl) benzidine.

Two or more of these diamines can be used in combination. Further, in the polyimide film of the present invention, in the structure derived from the diamine component, it is preferable to use a diamine having an R ₂ structure, but the diamine having a structure other than R ₂ is preferably 70 mol% of the total diamine, May be used in a range not exceeding 50 mol%, more preferably not exceeding 20 mol%. When using multiple types including the diamine of the said diamine, they may be regularly arranged and may exist in the polyimide at random.

  Examples of other diamines that can be used in combination include 3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl sulfide, and 3,4′-diaminodiphenyl. Sulfide, 4,4′-diaminodiphenylsulfide, 3,3′-diaminodiphenylsulfone, 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- ( -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) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene 1,4-bis (4- Minophenoxy) benzene, 1,3-bis (3-aminobenzoyl) 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-ditrifluoromethyl) Benzyl) benzene, 1,3-bis (4-amino-α, α-ditrifluoromethylbenzyl) benzene, 1,4-bis (3-amino-α, α-ditrifluoromethylbenzyl) ben 1,4-bis (4-amino-α, α-ditrifluoromethylbenzyl) 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-amino Phenoxy) 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] benzene, 1,4-bis [4- (4-aminophenoxy) benzoyl] benzene, 1,3-bis [4- (3-aminophenoxy)- , 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-aminophenoxy) 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) polydimethylsiloxane, 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-diamino Pentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminoio Tan, 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] heptane. Can do.

  Furthermore, depending on the purpose, any one or two or more of the ethynyl group, benzocyclobuten-4′-yl group, vinyl group, allyl group, cyano group, isocyanate group, and isopropenyl group serving as a crosslinking point, 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.

The substituent R ₃ may be introduced in the raw material state and may be introduced in the state of a diamine, and the substituent R ₃ may be introduced in the state of polyimide or polyamic acid by reacting with the diamine. Moreover, it is possible to adjust the wavelength of light to be absorbed by introducing a substituent, which affects the transparency and coloring degree of the resulting film.

  As described in detail, the polyimide film of the present invention has a polyimide structure derived from polyamic acid obtained by reacting Formula (1) and Formula (2), or Formula (3) and Formula (4). However, the imidation ratio of the polyimide film is preferably 85% or more, more preferably 93% or more, and particularly preferably 97% or more. Most preferably, substantially all are imidized.

  As a method for producing the polyimide of the present invention, conventionally known methods can be applied. For example, a polyamic acid which is a precursor is synthesized from an acid dianhydride and a diamine, and a dehydration catalyst and an imidizing agent are synthesized therewith. As a representative method, a polyimide film can be obtained by adding and coating (chemical imidization). Molding in the state of polyamic acid, and then imidizing by heating without using a dehydration catalyst or imidizing agent (thermal imidization), the resulting film has poor linear expansion and dimensional stability, and the purpose Is not suitable.

  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, picoline, quinoline and isoquinoline. An acid anhydride can be used as the dehydration catalyst. Specific examples of preferred acid anhydrides include acetic anhydride, propionic anhydride, n-butyric anhydride, benzoic anhydride, trifluoroacetic anhydride, and the like.

  The amount of the imidizing agent or dehydration catalyst added is 0.01 to 2.0 times molar equivalent, more preferably 0.05 to 1.5 times molar equivalent, relative to the carboxylic acid group of the polyamic acid. In particular, a molar equivalent of 0.1 to 1.0 is preferable. The dehydration catalyst is preferably 0.05 to 15.0 times molar equivalent, more preferably 1.0 to 12 times molar equivalent, and particularly preferably 2.0 to 10 times molar equivalent.

  When an imidizing agent or a dehydration catalyst is added to the polyamic acid solution, it may be added directly without being dissolved 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.

  Next, the method for synthesizing the polyimide according to the present invention will be illustrated more specifically, but the present invention is not limited thereto.

  A method for obtaining a polyamic acid can be obtained by mixing an amine component and an acid anhydride component. It is preferable to stir during mixing, and the stirring time is preferably 1 to 100 hours. The temperature at the time of mixing may be room temperature if attention is paid to heat generation, but it is preferably 10 ° C. or lower, more preferably 5 ° C. or lower. It is preferable to use substantially equimolar amounts of the amine component and the acid anhydride component. As the mixing method, a method in which an acid anhydride component is added to an amine component and the opposite method can be adopted. Each component may be added at once, or may be added in multiple portions.

  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 near 0 ° C. 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.

  The polyimide of the present invention synthesized in this manner is characterized by low linear expansion and low birefringence. For example, when measuring the linear thermal expansion coefficient by the tensile load method, a film sample of 15 mm × 5 mm is weighted. Is 3.0 g, and the linear thermal expansion coefficient is 40 ppm / K or less, preferably 20 ppm / K or less, more preferably 10 ppm / K or less, and particularly 8 ppm / K or less when measured at a heating rate of 10 ° C./min. The polyimide film can be obtained. Moreover, when the birefringence of this film is measured, a polyimide film having a birefringence of 0.2 or less, preferably 0.15 or less, and more preferably 0.1 or less can be obtained.

  The weight average molecular weight of the polyamic acid according to the present invention is preferably in the range of 3,000 to 1,000,000, more preferably in the range of 5,000 to 500,000, although it depends on the use. Preferably, it is in the range of 10,000 to 500,000. When the weight average molecular weight is small, it is difficult to obtain sufficient strength when a coating film or film is used, and coloring may occur because the number of polymer ends that cause coloring is relatively large. On the other hand, if it is too large, the viscosity of the solution increases and the solubility in the solvent also decreases, so that it becomes 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 by gel permeation chromatography (GPC).

  The polyimide of the present invention is characterized by having a low linear expansion and a low birefringence, but is good because the original properties of the polyimide such as heat resistance and insulation are not impaired.

  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 polyamic acid according to the present invention may be used as it is for a coating or molding process for producing a product or member as it is, but it may be used as a laminate by subjecting a molded product formed into a film to a treatment such as coating. I can do it. In order to provide a coating or molding process, the polyamic acid is dissolved or dispersed in a solvent as necessary, and further, a light or thermosetting component, a non-polymerizable binder resin other than the polyamic acid according to the present invention, and other components. May be blended to prepare a polyimide resin composition.

  In order to impart processing characteristics and various functionalities to the resin composition according to the present invention, various organic or inorganic low-molecular or high-molecular compounds may be blended. 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 film according to the present invention may have various inorganic thin films such as metal oxides and transparent electrodes formed on the surface thereof. The method for forming these inorganic thin films is not particularly limited, and may be, for example, a PVD method such as a CVD method, a sputtering method, a vacuum deposition method, or an ion plating method.

  Since the polyimide resin composition 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, for example, printed matter, Suitable for forming color filters, flexible displays, semiconductor parts, interlayer insulating films, wiring coating films, optical circuits, optical circuit parts, antireflection films, holograms, optical members or building materials.

  Specifically, the polyimide film of the present invention can be used as a so-called optical film and used as a polarizing plate in combination with a deflector. Moreover, the optical member which consists of a polarizing plate using the polyimide film of this invention or the polyimide film of this invention is provided in the at least one surface of a liquid crystal cell, and it can use also as a liquid crystal panel.

  Furthermore, it can also be used as a liquid crystal display device using the liquid crystal panel.

(Synthesis of precursor solution)
(1) Synthesis of Precursor Solution 1 2.50 g (17.2 mmol) of 2,2′-bis (trifluoromethyl) benzidine was put into a 100 mL three-necked flask, and 59.5 g of dehydrated dimethylacetamide ( The solution was dissolved in DMAc) and stirred under a nitrogen stream. Thereto, 5.0 g (17.0 mmol) of 3,3 ′, 4,4′-BPDA was added under ice-cooling (3 ° C.). After the addition was completed, the mixture was stirred for 2 days to obtain a viscous liquid (precursor solution). 1) was obtained.

(2) Synthesis of Precursor Solution 2 2,2′-bis (trifluoromethyl) benzidine (4.0 g, 12.5 mmol) was charged into a 100 mL three-necked flask and dissolved in 39.7 g of dehydrated DMAc. The mixture was stirred under a nitrogen stream. Thereto, 3.0 g (13.8 mmol) of pyromellitic dianhydride was added under ice cooling (3 ° C.), and after completion of the addition, the mixture was stirred for 1 day to obtain a viscous liquid (precursor solution 2). .

(3) Synthesis of precursor solution 3 Precursor solution 1 (14.3 g) and precursor solution 2 (1.3 g) were placed in a 50 mL three-necked flask and stirred under a nitrogen stream. The mixture was stirred for 1 day to obtain a viscous liquid (precursor solution 3). Moreover, as a result of measuring the molecular weight of this precursor solution 3, the weight average molecular weight was 144000.

(4) Synthesis of Precursor Solution 4 2.39 g (16.8 mmol) of 2,2′-bis (trifluoromethyl) benzidine was charged into a 100 mL three-necked flask, and 58.9 g of dehydrated dimethylacetamide ( The solution was dissolved in DMAc) and stirred under a nitrogen stream. Thereto, 5.0 g (17.0 mmol) of 3,3 ′, 4,4′-BPDA was added under ice-cooling (3 ° C.). After the addition was completed, the mixture was stirred for 2 days to obtain a viscous liquid (precursor solution). 4) was obtained.

(5) Preparation of precursor solution 5 Precursor solution 4 (14.3 g) and precursor solution 2 (1.3 g) were placed in a 50 mL three-necked flask and stirred under a nitrogen stream. The mixture was stirred for 1 day to obtain a viscous liquid (precursor solution 5).

Example 1
After the synthesized precursor solution 3 (15.6 g) was cooled to around 0 ° C., a mixed solution of 0.16 g (1.7 mmol) of β-picoline and 1.18 g (11.6 mmol) of acetic anhydride was added vigorously. Stir. Then, after defoaming under vacuum, it was poured on a polyethylene naphthalate film and applied onto the film with a bar coater in which the slit interval was set to 0.5 mm. Then, it was dried in an oven heated to 120 ° C. for 7 minutes and 20 seconds. Thereafter, heating was performed at 300 ° C. for 1 hour in an oven under a nitrogen atmosphere to obtain a polyimide film.

(Comparative Example 1)
After the synthesized precursor solution 5 (15.6 g) is cooled to around 0 ° C., a mixed solution of 0.16 g (1.7 mmol) of β-picoline and 1.18 g (11.6 mmol) of acetic anhydride is added vigorously. Stir. Thereafter, a polyimide film was obtained in the same manner as in Example 1.

(Comparative Example 2)
After the synthesized precursor solution 4 (20.0 g) was cooled to around 0 ° C., a mixed solution of β3 picoline 0.23 g (2.5 mmol) and acetic anhydride 1.5 g (14.7 mmol) was added vigorously. Stir. Thereafter, a polyimide film was obtained in the same manner as in Example 1.

(Comparative Example 3)
After the synthesized precursor solution 4 (20.0 g) was cooled to around 0 ° C., a mixed solution of β-picoline 0.68 g (7.3 mmol) and acetic anhydride 4.5 g (44.1 mmol) was added vigorously. Stir. Thereafter, a polyimide film was obtained in the same manner as in Example 1.

[Evaluation of glass transition temperature]
The Tg (glass transition temperature) of the polymer was determined by DSC-50 (Shimadzu heat flux differential scanning calorimeter) measured at a rate of temperature increase of 10 ° C./min.

[Evaluation of linear thermal expansion coefficient]
With the thermomechanical analyzer Thermo Plus TMA8310 (manufactured by Rigaku Corporation), the linear thermal expansion coefficient of the film prepared above was set to a weight of 3.0 g on a 15 mm × 5 mm film sample at a heating rate of 10 ° C./min. Measurements were made.

[Evaluation of birefringence]
The retardation of the film created above was measured by a phase difference measuring device KOBRA (manufactured by Oji Scientific Instruments) and determined by dividing by the thickness of the film.

  Table 1 shows the results of evaluating film properties in Examples and Comparative Examples.

From Table 1, the following is clear.
(1) The birefringence of the films obtained in Comparative Examples 1 and 2 is comparable to that of the Examples, but the linear expansion coefficient is remarkably bad.
(2) The linear expansion coefficient of the film obtained in Comparative Example 3 is almost the same as in Examples, but the birefringence is remarkably bad.

  As a result of measuring the Tg of the film of Table 1, no clear Tg was observed up to 320 ° C.

  From these results, since the polyimide film of the present invention has good heat resistance and can produce a film having both low linear expansion and low birefringence, these characteristics are effective.・ Products such as paint, printing ink, color filters, flexible display films, semiconductor devices, electronic components, interlayer insulation films, wiring coating films, optical circuits, optical circuit components, antireflection films, holograms, and other optical members Or it is suitable for forming building materials.

  Specifically, it can also be used as a polarizing plate, a liquid crystal panel, and a liquid crystal display device using the liquid crystal panel.

Claims (18)

A dehydration catalyst and imidation are carried out on a polyamic acid obtained by reacting a compound represented by the following formula (1) and a compound represented by the following formula (2), or a compound represented by the following formula (3) and a compound represented by the following formula (4). A method for producing a polyimide film, which is prepared by casting a solution mixed with an agent on a support.

Where n represents the number of repeating units,

In the formula, m represents a repeating unit and is an integer smaller than n, and R _{2 in the} formulas (1) and (2) may not necessarily be the same,

Where o represents the number of repeating units,

In the formula, p represents the number of repeating units and is an integer smaller than o, and R _{2 in the} formulas (3) and (4) may not necessarily be the same.
R _{1 in the} above formula represents a tetravalent organic group selected from the following general formula (5), and R ₂ represents a divalent organic group selected from the following general formula (6).

In the formula, R ₃ represents a halogen, an alkyl halide, or a C1-C16 alkyl group. 2. The method for producing a polyimide film according to claim 1, wherein the repeating unit represented by the formula (2) or (4) has a structure of R ₁ represented by the following general formula (7).

As the repeating unit represented by the formula (1), (2), (3) or (4), the structure of R ₂ is a divalent organic group selected from the following general formula (8). The manufacturing method of the polyimide film of Claim 1 or 2.

The method for producing a polyimide film according to any one of claims 1 to 3, wherein R ₃ is halogen or an alkyl halide. The method for producing a polyimide film according to any one of claims 1 to 4, wherein R ₃ is a trifluoromethyl group. The polyamic acid obtained by reacting the formulas (1) and (2) or the formulas (3) and (4) is imidized by using an imidizing agent and a dehydration catalyst. The manufacturing method of the polyimide film in any one of thru | or 5.   The method for producing a polyimide film according to claim 6, wherein the imidizing agent is a tertiary amine.   The method for producing a polyimide film according to claim 6 or 7, wherein the dehydration catalyst is an acid anhydride.   The method for producing a polyimide film according to any one of claims 6 to 8, wherein the imidizing agent is used in an amount of 0.01 molar equivalent or more with respect to the carboxylic acid of the polyamic acid.   The method for producing a polyimide film according to any one of claims 6 to 9, wherein the dehydration catalyst is used in an amount of 0.05 molar equivalent or more with respect to the carboxylic acid of the polyamic acid.   The manufacturing method of the polyimide film in any one of Claims 1 thru | or 10 whose weight average molecular weights of a polyamic acid are 3,000 or more. The polyimide film manufactured with the method in any one of Claims 1 thru | or 11 whose linear thermal expansion coefficient is 40 ppm / K or less.   The polyimide film of Claim 12 whose birefringence is 0.1 or less.   The polyimide film of Claim 12 or 13 whose glass transition temperature is 200 degreeC or more.   A polarizing plate comprising an optical film and a polarizer, wherein the optical film is a polyimide film according to claim 11.   A liquid crystal panel in which an optical member is disposed on at least one surface of a liquid crystal cell, wherein the optical member is a polyimide film according to claim 11.   A liquid crystal panel in which an optical member is disposed on at least one surface of a liquid crystal cell, wherein the optical member is a polarizing plate according to claim 15.   A liquid crystal display device including a liquid crystal panel, wherein the liquid crystal panel is a liquid crystal panel according to claim 17.