TW201841993A - Polyimide film, laminate, and surface material for display - Google Patents

Abstract

A polyimide film is provided, wherein the polyimide film comprises two or more polyimide layers that have different Young's moduli; wherein an overall thickness of the polyimide film is 5 [mu]m or more and 200 [mu]m or less; and wherein a total light transmittance of the polyimide film measured in accordance with JIS K7361-1, is 85% or more.

Description

   Polyimide film, laminate, and surface material for display   

The present invention relates to a polyimide film, a laminate, and a surface material for a display.

The thinner plate glass is excellent in hardness and heat resistance, but on the other hand, it has the following disadvantages: it is not easy to bend, it is easy to break if dropped, and there are problems with workability, and it is heavier than plastic products. Therefore, from the viewpoint of processability and weight reduction, research into a resin product that is a substitute for glass is underway.

For example, with the rapid advancement of liquid crystal or organic EL displays, or electronic devices such as touch panels, thinner or lighter devices and more flexible devices are required. Among these devices, various electronic components, such as thin transistors or transparent electrodes, have been formed on thinner plate glass in the past. The thin plate glass can be replaced with a resin film to achieve the impact resistance of the panel itself. Enhancement, flexibility, thinness, or weight reduction.

Generally, the polyfluorene imide resin is a highly heat-resistant resin obtained by subjecting a polyfluorinated acid obtained by a condensation reaction of an aromatic tetracarboxylic anhydride and an aromatic diamine to a dehydration ring-closure reaction. However, generally speaking, polyimide resins are colored yellow or brown, and therefore it is difficult to use them in fields requiring transparency such as display applications and optical applications. Therefore, research is being conducted to apply polyimide having improved transparency to a member for a display. For example, in Patent Document 1, as a polyimide resin having high heat resistance, high transparency, and low water absorption, it is disclosed that one selected from 1,2,4,5-cyclohexanetetracarboxylic acid, 1, 2,4,5-Cyclohexanetetracarboxylic dianhydride and these reactive derivatives of at least one fluorenyl-containing compound and a specific formula represented by the formula selected from at least one phenylene group It is a polyimide resin formed by reacting at least one kind of imine-forming compound among isopropylidene compounds, and it is described that it is suitable for a substrate material such as a flat panel display or a mobile phone.

Further, Patent Document 2 discloses a transparent polyimide film which includes a unit structure derived from an aromatic diacid anhydride and an aromatic diamine, and further contains an additive for improving tear strength, or has a component selected from A unit structure of a functional group monomer in a group consisting of a hexafluoro group, a fluorenyl group, and an oxy group. In Patent Document 3, as a polyimide film excellent in transparency and heat resistance, a value obtained by distinguishing a loss elastic modulus based on a stored elastic modulus, that is, a peak of a peak of a tanδ curve, is in a specific range. Polyimide film.

On the other hand, Patent Document 4 discloses a polyimide film including a polyimide layer (b) containing a hot-melt polyimide layer, and a polyimide layer adjoining the polymer. The polyimide layer (b) and the laminated polyimide layer (a) containing polyimide obtained by using a specific tetracarboxylic acid component and a diamine component are described in the polyimide film. A metal laminate such as a copper foil is laminated on the hot-melt surface.

Prior art literature

Patent literature

Patent Document 1: Japanese Patent Application Laid-Open No. 2006-199945

Patent Document 2: Japanese Patent Publication No. 2014-501301

Patent Document 3: Japanese Patent Publication No. 2012-503701

Patent Document 4: International Publication No. 2012/133594

Mobile devices and equipment with folded screens are often transported in a folded state. Therefore, the flexible display mounted on such mobile equipment and devices is required to remain in the original state when it is folded for a long period of time. The base material or surface material for a flexible display is also required to be recoverable after being bent for a long period of time (hereinafter, sometimes referred to as static bending resistance).

However, the conventional resin film using transparent polyimide showed good results even in tests in which the flat state and the folded state were repeated at a fixed cycle. If the state was continued for a long period of time, creases appeared, It is difficult to recover the problems of flatness and poor static bending resistance.

In addition, by increasing the elastic modulus of the resin film, the rigidity of the film will be increased, so that the impact resistance can be improved. On the other hand, if the elastic modulus of the resin film is increased, there will be a problem after bending. The restorability is deteriorated and the bending resistance tends to be insufficient. In fact, as shown in Comparative Example 2 described below, a polyimide film having a large elastic modulus has improved impact resistance, but deteriorates in bending resistance. In order to improve the bending resistance, it is effective to reduce the film thickness of the film, because the stress on the film during bending can be reduced. However, in a resin film used as a surface material, if the film thickness of the film is reduced, there is a problem that the reduction in rigidity of the film results in a reduction in the function of protecting the light emitting device or circuit from impact. Therefore, in a resin film, it is thought that impact resistance and bending resistance have opposite characteristics. Since the resin film used as the surface material sets the thickness of the film in such a manner as to maintain a balance between impact resistance and bending resistance, it cannot obtain satisfactory impact resistance compared to glass for rigid panels that cannot be bent. To achieve both impact resistance and bending resistance.

The present invention has been made in view of the problems described above, and a main object thereof is to provide a resin film having excellent impact resistance and good bending resistance.

Another object of the present invention is to provide a laminated body including the resin film and a surface material for a display which is the resin film or the laminated body.

The polyimide film of the present invention has two or more polyimide layers having different Young's modules, and the overall thickness is 5 μm or more and 200 μm or less. The total light transmittance measured according to JIS K7361-1 More than 85%.

In the polyimide film of the present invention, in terms of impact resistance and bending resistance, the Young's modulus of the polyimide layer having the largest Young's modulus among the polyimide layers is preferable. It is more than 1.2 times the Young's modulus of the polyfluorene imide layer with the smallest Young's modulus.

In the polyimide film of the present invention, in terms of impact resistance and bending resistance, it is preferable to have three or more polyimide layers, and among the polyimide layers, the Young's modulus The largest polyimide layer is located on at least one surface.

In the polyimide film of the present invention, in terms of impact resistance and bending resistance, it is preferable to have three or more polyimide layers, and among the polyimide layers, the Young's modulus The smallest polyimide layer is not on the surface.

In the polyimide film of the present invention, in terms of impact resistance and bending resistance, it is preferable that the thickest layer of the polyimide layers is not the largest polyimide layer having a Young's modulus. Amine layer.

In the polyimide film of the present invention, in terms of impact resistance and bending resistance, it is preferable that the total thickness of the polyimide layer having the largest Young's modulus among the polyimide layers is the whole. Below 60% of thickness.

In the polyimide film of the present invention, in terms of bending resistance, when the static bending test is performed according to the following static bending test method, the internal angle after the test is preferably 90 ° or more.

[Static bending test method]

A test piece cut into a polyimide film of 15 mm × 40 mm was bent at a half of the long side, and a metal piece with a thickness of 6 mm (100 mm × 30mm × 6mm), and use tape to fix the two ends of the test piece and the overlap between the upper and lower parts of the metal piece, respectively. In this state, use a glass plate (100mm × 100mm × 0.7). mm) Clamp from above and below, and fix the test piece in a state of bending with an inner diameter of 6 mm. At this time, a dummy test piece is inserted between the metal piece and the glass plate without the test piece, and the glass plate is parallelized and fixed with an adhesive tape. The test piece fixed in a bent state in this manner was left to stand in an environment of 60 ° C and 90% relative humidity (RH) for 24 hours, and thereafter, the glass plate and the fixing tape were removed, and the test piece was released. The force exerted. Thereafter, one end of the test piece was fixed, and the inner angle of the test piece 30 minutes after the release of the force applied to the test piece was measured.

In the polyimide film of the present invention, in terms of suppressing coloration of yellow tones and improving light transmittance, a value obtained by dividing the yellowness calculated in accordance with JIS K7373-2006 by the film thickness (μm) is preferred. It is 0.330 or less.

In the polyimide film of the present invention, in terms of light transmittance and impact resistance, it is preferable that the above polyimide layer having two or more layers contains the following polyimide, respectively, the polyimide Contains an aromatic ring and includes a structure selected from the group consisting of (i) a fluorine atom, (ii) an aliphatic ring, and (iii) an aromatic ring connected to each other by a sulfofluorene group or an alkylene group which may be substituted with a fluorine atom At least one of the group.

In the polyimide film of the present invention, in terms of light transmittance, impact resistance, and bending resistance, it is preferred that the polyimide layer having the largest Young's modulus among the polyimide layers contains Polyfluorene imine having a structure represented by the following general formula (1).

(In the general formula (1), R ¹ represents a group selected from 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride residues, 3,3', 4,4'-benzophenone tetracarboxylic acid. At least one tetravalent group in the group consisting of an acid dianhydride residue and a pyromellitic dianhydride residue, and R ² represents a group selected from 2,2′-bis (trifluoromethyl) benzidine residues, 4,4'-diaminodiphenylphosphonium residue, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane residue, bis [4- (3-amino Phenoxy) phenyl] fluorene residue, bis [4- (4-aminophenoxy) phenyl] fluorene residue, 4,4'-diamino-2,2'-bis (trifluoromethyl) Group) diphenyl ether residue, 1,4-bis [4-amino-2- (trifluoromethyl) phenoxy] benzene residue, 2,2-bis [4- (4-amino-2 -Trifluoromethylphenoxy) phenyl] hexafluoropropane residue, 4,4'-diamino-2- (trifluoromethyl) diphenyl ether residue, and 9,9-bis (4- Aminophenyl) at least one divalent group in the group consisting of fluorene residues; n represents the number of repeating units and is 1 or more)

In the polyimide film of the present invention, in terms of light transmittance, impact resistance, and bending resistance, it is preferred that the polyimide layer having the largest Young's modulus among the polyimide layers contains The polyimide having a structure represented by the general formula (1), and the polyimide film further includes a polyimide layer containing the polyimide layer having the general formula (2) Structure of polyimide.

(In the general formula (2), R ³ represents a tetravalent residue of a tetracarboxylic acid residue having an aromatic ring or an aliphatic ring, R ⁴ represents a diamine residue of a divalent residue, and 50% of the total amount of R ⁴ Molar% or less Diamine residues having 1 or 2 silicon atoms in the main chain, and the remaining R ⁴ are diamine residues having no silicon atom and having an aromatic ring or an aliphatic ring, and the remaining R ⁴ More than half of them are selected from the group consisting of 1,4-cyclohexanediamine residues, trans-1,4-bismethylenecyclohexanediamine residues, 4,4'-diaminodiphenylsulfonium Residue, 3,4'-diaminodiphenylfluorene residue, bis [4- (3-aminophenoxy) phenyl] fluorene residue, bis [4- (4-aminophenoxy ) Phenyl] fluorene residue, 2,2-bis (4-aminophenyl) propane residue, 2,2-bis (4-aminophenyl) hexafluoropropane residue, and the following general formula ( 3) At least one type of divalent base in the group consisting of the divalent base indicated; n 'represents the number of repeating units, and is 1 or more)

(In the general formula (3), R ⁵ and R ⁶ are each independently and represent a hydrogen atom, an alkyl group, or a perfluoroalkyl group.)

In the polyfluorene imide film of the present invention, in terms of light transmittance and bending resistance, it is preferable to have a polyfluorene imide layer containing the compound having the general formula (2). Represented structure of polyimide.

The laminated system of the present invention includes the laminated body of the polyimide film of the present invention and a hard coat layer, and the hard coat layer contains at least one polymer of a radical polymerizable compound and a cation polymerizable compound.

In the laminated body of the present invention, in terms of the hardness and adhesion of the hard coat layer, and the aspect of light transmittance and impact resistance, it is preferable that the radical polymerizable compound has two or more molecules per molecule. The (meth) acrylfluorenyl compound is a compound having at least one of two or more epoxy groups and oxetanyl groups in one molecule.

The surface material for a display of the present invention is the polyimide film of the present invention described above, or the laminated body of the present invention described above.

The surface material for a display of the present invention can be used as a flexible display.

According to the present invention, a resin film having excellent impact resistance and good bending resistance can be provided.

Moreover, according to this invention, the laminated body which has the said resin film, and the surface material for displays as said resin film or said laminated body can be provided.

1a, 1a ', 1b‧‧‧Polyimide layer

10、11‧‧‧Polyimide film

2‧‧‧ metal sheet

3a, 3b‧‧‧ glass plate

4a, 4b ‧‧‧ dummy test piece

5‧‧‧ substrate

6‧‧‧ aluminum foil

7‧‧‧ Ballpoint Pen

FIG. 1 is a schematic cross-sectional view showing an example of a polyimide film of the present invention.

FIG. 2 is a schematic cross-sectional view showing another example of the polyfluorene imide film of the present invention.

Fig. 3 is a diagram for explaining a method of a static bending test.

FIG. 4 is a diagram for explaining an evaluation method of impact resistance.

I. Polyfluorene film

The polyimide film of the present invention has two or more polyimide layers having different Young's modules, and the overall thickness is 5 μm or more and 200 μm or less. The total light transmittance measured according to JIS K7361-1 More than 85%.

The polyimide film of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing an example of a polyimide film of the present invention. The polyimide film 10 of the present invention shown in FIG. 1 has a polyimide layer 1b between the polyimide layer 1a and the polyimide layer 1a ', and the polyimide layer 1a and the polyimide The amine layers 1a 'have the same Young's modulus, and the polyfluorene imine layer 1b is different from the polyfluorene imine layer 1a and the polyfluorine imine layer 1a' Young's modulus.

FIG. 2 is a schematic cross-sectional view showing another example of the polyfluorene imide film of the present invention. The polyimide film 11 of the present invention shown in FIG. 2 includes a polyimide layer 1a and a polyimide layer 1b, and the polyimide layer 1a and the polyimide layer 1b have different Young's modulus. the same.

In addition, in the present invention, the Young's modulus is a cross section of a test piece obtained by cutting a polyimide film in a thickness direction, and measured at 25 ° C according to ISO14577 using a nanoindentation method. . Specifically, a PICODENTOR HM500 manufactured by Fischer Instruments was used as the measurement device, and a Vickers indenter was used as the measurement indenter. For each layer of the cross section of the test piece, a value obtained by measuring 8 arbitrary points and performing a number average was defined as a Young's modulus of each layer. In addition, the measurement conditions were set as follows: the maximum indentation depth: 1000 nm; the load time: 20 seconds; and the creep time: 5 seconds.

In addition, in the present invention, the Young's modulus of the polyfluorine-imide layer is different from each other, which means that the difference between the Young's modulus is 0.3 GPa or more, and when the difference between the Young's modulus is less than 0.3 GPa, It is considered that the Young's modulus of the polyfluorene layer is the same as each other.

The polyimide film of the present invention has a total light transmittance of 85% or more as measured in accordance with JIS K7361-1. Since the transmittance is so high, the transparency becomes good and it can be used as a glass substitute. The total light transmittance measured according to JIS K7361-1 as described above is more preferably 88% or more, and even more preferably 90% or more.

The total light transmittance measured in accordance with JIS K7361-1 can be measured by, for example, a haze meter (for example, HM150 manufactured by Murakami Color Technology Research Institute).

In the polyimide film of the present invention, the reasons for excellent impact resistance and good bending resistance are estimated as follows.

A resin film excellent in bending resistance can improve impact resistance by increasing the thickness of the film, but if the thickness of the film is too thick, the bending resistance is deteriorated. On the other hand, the polyimide film of the present invention has two or more polyimide layers having different Young's modules, which has excellent impact resistance and good bending resistance. Among two or more polyimide layers, the polyimide layer having a relatively large Young's modulus is relatively difficult to deform and has excellent impact resistance. On the other hand, a polyfluorene layer having a relatively small Young's modulus is relatively easy to deform and has excellent bending resistance. In the polyfluorene imide film of the present invention, it is considered that a polyfluorene imide layer having a relatively large Young's modulus among two or more polyimide layers can improve impact resistance and make the Young's modulus relatively The smaller polyimide layer improves bending resistance while achieving impact resistance and bending resistance. From the standpoint of shock absorption, polyimide layers with relatively high Young's modulus tend to spread the force of collision on the surface, and polyimide layers with relatively low Young's modulus take time There is a strong tendency to spread the force of the collision. As for the polyimide film of the present invention, it is presumed that the maximum value of the impact force can be moderately diffused and the impact force can be reduced by combining the polyimide layers having different effects of diffusing the force of collision in this way. , Which is thought to further improve the impact resistance.

Hereinafter, the polyfluorene imide film of the present invention will be described in detail.

The polyimide film of the present invention has two or more polyimide layers having different Young's modules, the overall thickness is 5 μm or more and 200 μm or less, and the total light transmittance is 85% or more. As long as the effect of the present invention is not impaired, other configurations are possible.

1. Composition of polyimide film

The polyimide film layer of the present invention includes two or more polyimide layers having different Young's modules, and the polyimide film has two or more layers having different Young's modules. Those with imine layer.

The polyimide film according to the present invention may be one having two polyimide layers as shown in FIG. 2, or one having three polyimide layers as shown in FIG. 1, or may be one having four Polyimide layers above the layer are not shown.

In addition, the polyimide film of the present invention may be one having at least two polyimide layers having different Young's modulus from each other, and may include two or more polyimide layers having the same Young's modulus. . Among them, in terms of improving impact resistance and bending resistance, it is preferable that the polyimide layers adjacent to each other are polyimide layers having different Young's moduli, and more preferably alternately between adjacent layers. The layers include a polyimide layer having a relatively large Young's modulus and a polyimide layer having a relatively small Young's modulus.

The polyimide film of the present invention preferably has three or more polyimide layers in terms of impact resistance and bending resistance, and among the polyimide layers, a Young's mold is preferable. The largest polyimide layer is located on at least one surface, and it is particularly preferred that the polyimide layer has at least 3 and an odd number, and the polyimide layer has the largest Young's modulus among the polyimide layers. The amine layer is located on one surface. The Young's modulus of the polyimide layer with the largest Young's modulus is 1.0 times or more and less than 1.2 times the Young's modulus of the polyimide layer on the other surface. In terms of impact resistance and bending resistance, and in terms of suppressing warpage of the film, it is more preferably 1.0 times or more and 1.1 times or less.

The polyimide film of the present invention preferably has three or more polyimide layers in terms of impact resistance and bending resistance, and among the polyimide layers, a Young's mold is preferable. The polyimide layer having the smallest number is not located on the surface, and it is particularly preferred that the polyimide layer has 3 or more and an odd number, and the polyimide layer having the smallest Young's modulus among the polyimide layers described above. The floor is centrally located.

On the other hand, the polyimide film of the present invention, which is composed of two polyimide layers, is preferred in terms of improving impact resistance and bending resistance, and being thinner. When a polyimide film composed of two polyimide layers is used for the surface material, in terms of impact resistance and bending resistance, a polymer having a relatively large Young's modulus is preferred. The fluorene imine layer is used so that it may become a surface side. In the polyimide film of the present invention composed of two polyimide layers, the Young's modulus is preferable in terms of impact resistance and bending resistance, and in terms of suppressing warpage of the film. The Young's modulus of the relatively large polyimide layer is 1.2 times to 2.0 times the Young's modulus of the relatively small polyimide layer.

Regarding the polyimide film of the present invention, in terms of improving impact resistance and bending resistance, it is more preferable that the number of layers of the polyimide layer is 3 or more and odd, and the Young's modulus is relatively high. The large polyimide layer and the relatively small Young's modulus polyimide layer are alternately laminated between adjacent layers, and the polyimide layer on the surface is a polyimide having a relatively large Young's modulus. And further preferably a polyimide layer on one surface and a polyimide layer on the other surface are the polyimide layers having the largest Young's modulus among the polyimide layers, and further More preferably, the central polyimide layer is a polyimide layer having the smallest Young's modulus.

The number of polyimide layers in the polyimide film of the present invention is not particularly limited as long as it is two or more. From the viewpoint of thinning the polyimide film and ease of production, It is preferably 5 layers or less, and more preferably 2 or 3 layers. Among them, in terms of impact resistance, a three-layer structure in which a layer having a Young's modulus greater than the polyimide layer is located on both sides of a polyimide layer having a relatively small Young's modulus is particularly preferable.

Regarding the polyimide film of the present invention, in terms of impact resistance and bending resistance, a polyimide layer having a maximum Young's modulus is preferably a polyimide having a minimum Young's modulus. The imine layer has a Young's modulus of 1.2 times or more, and more preferably 1.5 times or more. On the other hand, the Young's modulus of the polyfluorene layer with the largest Young's modulus is preferably 4.0 times or less, and more preferably 3.0 times or less, of the polyfluorine layer with the smallest Young's modulus. It may be 2.0 times or less, but it is not particularly limited.

Furthermore, in the present invention, the ratio of the Young's modulus of the polyfluorene layer with the largest Young's modulus to the Young's modulus of the polyfluorene layer with the smallest Young's modulus is based on JIS Z8401: Rule B of 1999 was calculated by rounding the value to the first decimal place.

When the polyimide film of the present invention has three or more polyimide layers, the Young's modulus of the polyimide layer on one surface and the poplar of the polyimide layer on the other surface The difference in the Modulus of Modulus is preferably within 1.0 GPa, more preferably within 0.5 GPa, and even more preferably less than 0.3 GPa in terms of suppressing warpage of the polyfluoreneimide film.

Regarding the Young's modulus of each polyimide layer possessed by the polyimide film of the present invention, in terms of impact resistance and bending resistance, it is preferably 2.0 GPa or more, and more preferably 3.0 GPa or more. Furthermore, it is more preferably 3.5 GPa or more. On the other hand, it is preferably 10.0 GPa or less, more preferably 8.0 GPa or less, and even more preferably 7.0 GPa or less.

Among them, the Young's modulus of the polyfluorene layer having the largest Young's modulus is preferably 3.5 GPa or more, more preferably 5.0 GPa or more, and even more preferably 6.0 GPa or more. The Young's modulus of the polyimide layer having the smallest Young's modulus is preferably 4.5 GPa or less, and more preferably 4.0 GPa or less.

In the case where the polyimide film of the present invention has three or more polyimide layers, the temperature of the polyimide layer on one surface and the polyimide layer on the other surface is between 50 ° C and 50 ° C. The difference in linear thermal expansion coefficient (CTE) in the range of 250 ° C is preferably within 10 ppm / ° C, more preferably within 5ppm / ° C, and even more preferably 2ppm / ° C in terms of suppressing warpage of the polyimide film. Within ℃.

In addition, the linear thermal expansion coefficient (CTE) of each polyimide layer in the range of 50 ° C to 250 ° C can be obtained by using the same material, the same The single-layer polyimide film produced under the conditions was cut into 5mm × 15mm test pieces, and the thermomechanical analysis device (TMA) was used to measure the elongation of the test pieces under the following conditions and calculated at 50 ° C to 250 ° C The coefficient of linear thermal expansion (CTE).

<CTE measurement conditions>

Model name: TMA-60, manufactured by Shimadzu Corporation

Ambient gas: nitrogen

Gas flow: 50ml / min

Initial load: 9g

[Temperature control program]

Under a nitrogen environment, the temperature was maintained at 30 ° C for 10 minutes, and thereafter, the temperature was increased to 400 ° C at a heating rate of 10 ° C / min, and maintained at 400 ° C for 1 minute.

The linear thermal expansion coefficient (CTE) of each polyimide layer included in the polyimide film of the present invention in the range of 50 ° C to 250 ° C is not particularly limited, and in terms of heat resistance, each is preferably 70 ppm. / ° C or lower, more preferably 60 ppm / ° C or lower, and even more preferably 50 ppm / ° C or lower.

The overall thickness of the polyimide film of the present invention is 5 μm or more and 200 μm or less. In terms of bending resistance and impact resistance, it is more preferably 10 μm or more and 180 μm or less, and even more preferably 40 μm or more and 150 μm or less. It is more preferably 50 μm or more and 120 μm or less.

The thickness of each polyimide layer in the polyimide film of the present invention is not particularly limited. In terms of bending resistance and impact resistance, it is preferably the thickest among the polyimide layers described above. The layer is not a polyimide layer with the largest Young's modulus.

Moreover, in the polyfluorene imide film of the present invention, the thickness of each polyfluorine imide layer can be, for example, from a scanning electron microscope (SEM), a transmission electron microscope section microscope (TEM), or a scanning transmission electron. A cross section in the thickness direction observed by an electron microscope such as a microscope (STEM) is measured.

When the boundary of the adjacent polyimide layer has a mixed region formed by mixing the materials of the polyimide layers and the interface is unclear, for example, the boundary when determining the thickness of the polyimide layer may be Determine as follows. Select the elements that are most likely to appear in the materials of the two adjacent polyimide layers to perform element mapping by TOF-SIMS and other elements. The portion where the detected amount of the selected element becomes the average of the detected amounts of the elements in the two regions other than the above-mentioned mixed region is used as a boundary when the thickness of the polyimide layer is obtained. In the case where a portion having an average value of the detected amounts of the elements in the two regions other than the above-mentioned mixed region has a thickness region, the central portion in the thickness direction of the region is used as a boundary when the thickness of the polyimide layer is obtained .

In addition, the polyimide film of the present invention is preferably between adjacent polyimide layers in terms of excellent interlayer adhesion, suppression of interference fringes, and easy improvement of impact resistance. With mixed area.

Moreover, regarding the polyimide film of the present invention, in terms of improving bending resistance, it is preferable that the total thickness of the polyimide layer having the largest Young's modulus among the polyimide layers is polyimide. The total thickness of the amine film is 60% or less, more preferably 50% or less, still more preferably 40% or less, and still more preferably 30% or less. Regarding the total thickness of the polyimide layer having the largest Young's modulus among the above polyimide layers, in terms of improving impact resistance, it is preferably 5% or more of the overall thickness of the polyimide film. More preferably, it is 10% or more.

On the other hand, regarding the polyimide film of the present invention, if the total thickness of the polyimide layer having the largest Young's modulus among the polyimide layers is 15% or more of the overall thickness of the polyimide film Furthermore, 60% or less is preferable in terms of suppressing reduction in bending resistance and improving impact resistance, and may be set to 20% or more and 60% or less.

Moreover, regarding the polyimide film of the present invention, in terms of improving the bending resistance, it is preferable that the total thickness of the polyimide layer (low Young's modulus layer) having the smallest Young's modulus be larger than the above-mentioned polyimide layer. The ratio of the total thickness of the polyimide layer (high Young's modulus layer) with the largest Young's modulus among the rhenium imine layers (total thickness of the low Young's modulus layer / total thickness of the high Young's modulus layer) ) Is more than 1.0, more preferably 2.0 or more. On the other hand, the above ratio (total thickness of the low Young's modulus layer / total thickness of the high Young's modulus layer) is preferably 20 or less in terms of impact resistance, and more preferably 15 or less. Furthermore, from the viewpoint of suppressing reduction in bending resistance, the above ratio (total thickness of the low Young's modulus layer / total thickness of the high Young's modulus layer) is preferably 0.6 or more, more preferably 0.7 or more, and furthermore, It is more preferably 0.8 or more, and even more preferably 1.0 or more.

Further, in the polyfluorene imide film of the present invention, the total thickness of the polyfluorene imine layer (low Young's modulus layer) having the smallest Young's modulus among the polyfluorine imines is not particularly limited, and is preferably It is 20 micrometers or more and 120 micrometers or less, Especially when it is 20 micrometers or more and less than 70 micrometers, it is preferable in terms of bending resistance.

2.Polyimide layer

Each of the polyimide layers of the polyimide film of the present invention contains at least polyimide, and may contain additives or other resins other than polyimide as necessary within a range that does not impair the effects of the present invention.

(1) Polyimide

Polyimide is obtained by reacting a tetracarboxylic acid component and a diamine component. It is preferable to perform polyimidization by obtaining a polyamidic acid by the polymerization of a tetracarboxylic acid component and a diamine component. The fluorene imidization can be carried out by hot fluoridation or by chemical fluoridation. In addition, it can also be produced by a method in which thermal amidine and chemical amidine are used in combination.

As specific examples of the tetracarboxylic acid component, tetracarboxylic dianhydride can be preferably used, and examples thereof include cyclohexane tetracarboxylic dianhydride, cyclopentane tetracarboxylic dianhydride, and dicyclohexane-3,4, 3 ', 4'-tetracarboxylic dianhydride, pyromellitic dianhydride, 3,3', 4,4'-benzophenone tetracarboxylic dianhydride, 2,2 ', 3,3'-di Benzophenone tetracarboxylic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis ( 3,4-dicarboxyphenyl) fluorene 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) benzyl] Phthalic anhydride, 1,4-bis [(3,4-dicarboxy) benzylidene] phthalic anhydride, 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-di Carboxyl) phenoxy Yl] phenyl} ketone dianhydride, bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} ketone dianhydride, 4,4'-bis [4- (1,2-bis Carboxy) phenoxy] biphenyl dianhydride, 4,4'-bis [3- (1,2-dicarboxy) phenoxy] biphenyl dianhydride, bis {4- [4- (1,2-di Carboxy) phenoxy] phenyl} ketone dianhydride, bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} ketone dianhydride, bis {4- [4- (1,2 ( -Dicarboxy) phenoxy] phenyl} fluorene dianhydride, bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} fluorene dianhydride, bis {4- [4- (1 , 2-dicarboxy) phenoxy] phenyl} sulfide dianhydride, bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} sulfide dianhydride, 4,4'- (Hexafluoroisopropylidene) bisphthalic anhydride, 3,4 '-(hexafluoroisopropylidene) bisphthalic anhydride, 3,3'-(hexafluoroisopropylidene) bisphthalate Phthalic anhydride, 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-pyridinetetracarboxylic dianhydride, 2,3,6,7-anthracene tetracarboxylic dianhydride, 1,2,7 8-phenanthrenetetracarboxylic dianhydride.

These tetracarboxylic dianhydrides may be used alone or in combination of two or more.

As specific examples of the diamine component, p-phenylenediamine, m-phenylenediamine, o-phenylenediamine, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4 , 4'-diaminodiphenylsulfide, 3,3'-diaminodiphenylsulfide, 3,4'-diaminodiphenylsulfide, 4,4'-diaminodiphenylsulfide, 3,3'-diaminodiphenylphosphonium, 3,4'-diaminodiphenylphosphonium, 4,4'-diaminodiphenylphosphonium, 3,3'-diaminodiphenylbenzene Ketone, 4,4'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4,4'-diaminobenzidine aniline, 3,3'-diaminediamine Benzylmethane, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 2,2-bis (3-aminophenyl) propane, 2,2-bis (4- Aminophenyl) propane, 2- (3-aminophenyl) -2- (4-aminophenyl) propane, 2,2-bis (3-aminophenyl) -1,1,1, 3,3,3-hexafluoropropane, 2,2-bis (4-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 2- (3-aminophenyl) -2- (4-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 1,1-bis (3-aminophenyl) -1-phenylethane, 1, 1-bis (4-aminophenyl) -1-phenylethane, 1- (3-aminophenyl) -1- (4-aminophenyl) -1-phenylethane, 1,3- Bis (3-aminophenoxy) benzene, 1,3-bis (4-amino (Oxy) benzene, 1,4-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminobenzidine Phenyl) benzene, 1,3-bis (4-aminobenzyl) benzene, 1,4-bis (3-aminobenzyl) benzene, 1,4-bis (4-aminobenzyl) Fluorenyl) 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-bis (trifluoromethyl) benzyl) benzene, 1,3-bis (4-amino-α, α-bis (trifluoromethyl) benzyl) benzene 1,4-bis (3-amino-α, α-bis (trifluoromethyl) benzyl) benzene, 1,4-bis (4-amino-α, α-bis (trifluoromethyl) Benzyl) benzene, 2,6-bis (3-aminophenoxy) benzonitrile, 2,6-bis (3-aminophenoxy) pyridine, N, N'-bis (4-amino (Phenyl) p-xylylenediamine, 9,9-bis (4-aminophenyl) fluorene, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'- Bis (trifluoromethyl) -4,4'-diaminobiphenyl (2,2-bis (trifluoromethyl) benzidine), 3,3'-dichloro-4,4'-diamine Biphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 4,4'-bis (3- Phenylphenoxy) biphenyl, 4,4'-bis (4-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] one, bis [4- (4 -Aminophenoxy) phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfide,

Bis [4- (3-aminophenoxy) phenyl] fluorene, bis [4- (4-aminophenoxy) phenyl] fluorene, bis [4- (3-aminophenoxy) benzene Group] 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-hexa Fluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 1,3-bis [4- (3 -Aminophenoxy) benzylidene] benzene, 1,3-bis [4- (4-aminophenoxy) benzylidene] benzene, 1,4-bis [4- (3-amine Phenylphenoxy) benzylidene] benzene, 1,4-bis [4- (4-aminophenoxy) benzylidene] benzene, 1,3-bis [4- (3-aminophenylbenzene (Oxy) -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-dimethyl Benzyl] benzene, 4,4'-bis [4- (4-aminophenoxy) benzylidene] diphenyl ether, 4,4'-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] benzophenone, 4,4'-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] diphenylfluorene , 4,4'-Double [4- (4- Phenoxy) phenoxy] diphenylphosphonium, 3,3'-diamino-4,4'-diphenoxybenzophenone, 3,3'-diamino-4,4 ' -Diphenoxybenzophenone, 3,3'-diamino-4-phenoxybenzophenone, 3,3'-diamino-4-benphenoxybenzophenone, 6,6'-bis (3-aminophenoxy) -3,3,3 ', 3'-tetramethyl-1,1'-spirobiindan, 6,6'-bis ( 4-aminophenoxy) -3,3,3 ', 3'-tetramethyl-1,1'-spirobiindane, 1,3-bis (3-aminopropyl) tetramethyldi Siloxane, 1,3-bis (4-aminobutyl) tetramethyldisilaxane, 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-aminopropyloxy) ethyl] ether, 1 , 4-cyclohexanediamine, trans-1,4-bismethylenecyclohexanediamine (trans-1,4-bis (aminomethyl) cyclohexane), 2,6-bis (amine Methylmethyl) bicyclo [2,2,1] heptane, 2,5-bis (aminomethyl) bicyclo [2,2,1] heptane, and also selected from the group consisting of fluoro, Methyl, methoxy, trifluoromethyl A diamine in which a group or a substituent in a trifluoromethoxy group replaces part or all of the hydrogen atoms on the aromatic ring of the diamine.

These diamines may be used alone or in combination of two or more.

Further, in terms of improving light transmittance and improving impact resistance, it is preferable that the polyimide layers of the two or more layers each contain polyimide, and the polyimide contains an aromatic ring and contains a member selected from the group consisting of at least one of (i) a fluorine atom, (ii) an aliphatic ring, and (iii) a structure formed by connecting aromatic rings to each other by a sulfofluorene group or an alkylene group which may be substituted with a fluorine atom. When an aromatic ring is contained in the polyfluoreneimide, the alignment is improved and the rigidity is improved, so the impact resistance is improved, but the transmittance tends to decrease due to the absorption wavelength of the aromatic ring.

When the (i) fluorine atom is contained in the polyfluorene imide, the electron state in the polyfluorene imine skeleton can be made to be difficult to transfer charges, and in this respect, the light transmittance is improved.

If (ii) an aliphatic ring is contained in the polyfluorene imine, the conjugate of the π electrons in the polyfluorene imine skeleton will be cut off, thereby being able to hinder the transfer of charge in the skeleton. In this respect, transparent Photometric enhancement.

If the polyfluorene imine contains (iii) a structure in which aromatic rings are connected to each other by a sulfofluorene group or an alkylene group which can be substituted by a fluorine atom, the π electrons in the polyfluorene imine skeleton will be cut off. The yoke can thereby prevent the transfer of electric charge in the skeleton, and in this respect, the light transmittance is improved.

In terms of improving light transmittance and improving impact resistance, a polyfluorene imide containing an aromatic ring and containing a fluorine atom is particularly preferably used.

The proportion of fluorine atoms in polyfluorene imine is preferably a ratio (F / C) of the number of fluorine atoms (F) to the number of carbon atoms (C) obtained by measuring the surface of the polyfluorene imide by X-ray photoelectron spectroscopy. It is 0.01 or more, and more preferably 0.05 or more. On the other hand, if the content of fluorine atoms is too high, the original heat resistance of polyfluorene imine may be reduced. Therefore, the ratio of the number of fluorine atoms (F) to the number of carbon atoms (C) ( F / C) is 1 or less, and more preferably 0.8 or less.

Here, the above ratio measured by X-ray photoelectron spectroscopy (XPS) can be determined from the value of atomic% of each atom measured using an X-ray photoelectron spectroscopy device (for example, Theta Probe of Thermo Scientific Corporation).

Moreover, regarding the said polyfluorene imide, in terms of improvement of impact resistance, when the total of a tetracarboxylic acid residue and a diamine residue is 100 mol%, it is preferable that it is the four having an aromatic ring. The total of the carboxylic acid residue and the diamine residue having an aromatic ring is 50 mol% or more, more preferably 60 mol% or more, and even more preferably 75 mol% or more.

Furthermore, in the present invention, the content ratio of each repeating unit in polyfluorene imine, the content ratio of each tetracarboxylic acid residue or each diamine residue (mol%) can be added according to the production of polyfluorene imine. The molecular weight is determined. In addition, the content ratio (mol%) of each tetracarboxylic acid residue or each diamine residue in the polyfluorene imine can be used to dissolve the polyfluorene obtained by decomposing the sample with an alkaline aqueous solution or supercritical methanol. Decomposed products of amines were determined using high performance liquid chromatography, gas chromatography mass analyzer, NMR, elemental analysis, XPS / ESCA, TOF-SIMS, and thermal decomposition CG-MS.

In addition, as for the polyfluorene imine, in terms of improving impact resistance and light transmittance, it is preferable that at least one of a tetracarboxylic acid residue and a diamine residue contains an aromatic ring and a fluorine atom, and furthermore, Preferably, it has a tetracarboxylic acid residue containing an aromatic ring and a fluorine atom, and a diamine residue containing an aromatic ring and a fluorine atom.

Regarding the polyfluorene imine, when the total of the tetracarboxylic acid residue and the diamine residue is 100 mol%, a tetracarboxylic acid residue having an aromatic ring and a fluorine atom and an aromatic ring are preferred. The total of the diamine residues and the fluorine atom is 50 mol% or more, more preferably 60 mol% or more, and even more preferably 75 mol% or more.

In terms of improving light transmittance and improving rigidity, it is preferable to use 50% or more of hydrogen atoms bonded to carbon atoms contained in the polyfluorene imide as hydrogen directly bonded to the aromatic ring. Atom polyimide. The proportion of hydrogen atoms (number) directly bonded to the aromatic ring among all hydrogen atoms (number) bonded to carbon atoms contained in the polyfluorene imine is more preferably 60% or more, and more preferably More than 70%.

In the case where polyimide containing more than 50% of the hydrogen atoms bonded to carbon atoms contained in the polyfluorene imine is a hydrogen atom directly bonded to an aromatic ring, even after the heating step in the atmosphere, For example, stretching at 200 ° C or higher, the optical characteristics, especially the total light transmittance or the change in yellowness YI (Yellowness Index, yellowness index) value are also small, which is better in this respect. In the case where the polyfluorene imide contains more than 50% of the hydrogen atoms bonded to carbon atoms and the hydrogen atoms directly bonded to the aromatic ring, the reactivity with oxygen is low, Therefore, it is presumed that the chemical structure of polyimide is not easy to change. Polyimide film uses its high heat resistance, and is often used for devices that require processing steps accompanied by heating. It is 50% of hydrogen atoms bonded to carbon atoms contained in polyimide. When the above is a polyfluorene imine having a hydrogen atom directly bonded to an aromatic ring, there is no need to carry out these subsequent steps in an inert environment in order to maintain transparency, so it can suppress equipment costs or environmental control The advantages of the expense.

Here, the proportion of hydrogen atoms (number) of hydrogen atoms directly bonded to the aromatic ring among all hydrogen atoms (number) bonded to carbon atoms contained in the polyfluorene imine can be compared to the decomposition products of the polyfluorene. It was calculated | required using a high performance liquid chromatography, a gas chromatography mass analyzer, and NMR. For example, the ratio of hydrogen atoms (number) directly bonded to the aromatic ring among all hydrogen atoms (number) contained in the polyfluorene imine can be obtained as follows: by using an alkaline aqueous solution, or The decomposition product of polyfluorene imine obtained by decomposing the sample with supercritical methanol was separated by high-performance liquid chromatography, and qualitative analysis of each peak of the separation was performed using a gas chromatography mass analyzer and NMR, and Quantification was performed using high performance liquid chromatography.

In addition, as the polyimide used in the present invention, the adhesion between the adjacent polyimide layers and the adhesion between the polyimide film and other layers such as a hard coat layer are improved. From a viewpoint, polyimide containing a silicon atom can be preferably used. In addition, the polyimide layer containing polyimide containing silicon atoms is more likely to form the above-mentioned mixed region between adjacent polyimide layers, thereby improving the interlayer adhesion and suppressing the generation of interference fringes. It is also better. Moreover, if a polyimide film has the following polyimide layer, it is easy to improve impact resistance, and it is also preferable in this respect, and this polyimide layer contains polyimide containing a silicon atom.

As the polyfluorene imine containing a silicon atom used in the present invention, it may be particularly preferably used in a total of 100 mol% of diamine residues, preferably 1 mol% or more and 50 mol% or less, The polyfluorene imide having a diamine residue having a silicon atom is more preferably contained in a proportion of 2.5 mol% or more and 40 mol% or less, and even more preferably 5 mol% or more and 30 mol% or less.

The diamine residue having a silicon atom is preferably a diamine residue having 1 or 2 silicon atoms in the main chain.

Examples of the diamine having one silicon atom in the main chain include a diamine represented by the following general formula (A). Examples of the diamine having two silicon atoms in the main chain include a diamine represented by the following general formula (B).

(In the general formula (A) and the general formula (B), L is independent and is a direct bond or an -O- bond, and R ^{10 is} independent respectively, and represents a carbon number of 1 which may have a substituent and may also include an oxygen atom or a nitrogen atom. A monovalent hydrocarbon group of above and below 20; R ^{11 is} independent and represents a divalent hydrocarbon group of 1 or more and 20 or less in carbon that may have a substituent and may also include an oxygen atom or a nitrogen atom)

In the general formula (A) and the general formula (B), a plurality of L, R ¹⁰ , and R ¹¹ may be the same or different.

Examples of the monovalent hydrocarbon group represented by R ¹⁰ include an alkyl group having 1 to 20 carbon atoms, an aryl group, and combinations thereof. The alkyl group may be any of linear, branched, and cyclic, and may be linear or a combination of branched and cyclic.

The alkyl group having 1 to 20 carbon atoms is preferably an alkyl group having 1 to 10 carbon atoms. Specific examples include methyl, ethyl, propyl, isopropyl, butyl, and iso. Butyl, third butyl, pentyl, hexyl, and the like. The cyclic alkyl group is preferably a cycloalkyl group having 3 to 10 carbon atoms, and specific examples thereof include a cyclopentyl group and a cyclohexyl group. The aryl group is preferably an aryl group having 6 to 12 carbon atoms, and specific examples thereof include a phenyl group, a tolyl group, and a naphthyl group. The monovalent hydrocarbon group represented by R ¹⁰ may be an aralkyl group, and examples thereof include benzyl, phenethyl, and phenylpropyl.

Examples of the hydrocarbon group which may include an oxygen atom or a nitrogen atom include a divalent hydrocarbon group and at least one of an ether bond, a carbonyl bond, an ester bond, an amido bond, and an imine bond (-NH-) described below. The monovalent hydrocarbon group is a group obtained by bonding.

The substituent which the monovalent hydrocarbon group represented by R ¹⁰ may have is not particularly limited as long as the effect of the present invention is not impaired, and examples thereof include halogen atoms such as a fluorine atom and a chlorine atom, and hydroxyl groups.

As the monovalent hydrocarbon group represented by R ¹⁰ , in terms of impact resistance and bending resistance, an alkyl group having 1 or more and 3 carbon atoms or an aryl group having 6 or more and 10 carbon atoms is more preferable, It is an alkyl group having 1 to 3 carbon atoms. The alkyl group having 1 to 3 carbon atoms is more preferably a methyl group, and the aryl group having 6 to 10 carbon atoms is more preferably a phenyl group.

Examples of the divalent hydrocarbon group represented by R ¹¹ include an alkylene group having 1 to 20 carbon atoms, an arylene group, and a combination thereof. The alkylene may be any of linear, branched, and cyclic, and may be linear or a combination of branched and cyclic.

The alkylene group having 1 to 20 carbon atoms is preferably an alkylene group having 1 to 10 carbon atoms, and examples thereof include methylene, ethylene, various propyl groups, various butyl groups, A linear or branched chain alkylene and a cyclic alkylene combination, such as cyclohexyl.

The above-mentioned arylene group is preferably an arylene group having 6 to 12 carbon atoms. Examples of the arylene group include a phenylene group, a biphenylene group, and a naphthyl group. Aromatic ring as opposed to substituents.

Examples of the divalent hydrocarbon group which may include an oxygen atom or a nitrogen atom include the above-mentioned divalent hydrocarbon groups being bonded to each other by using at least one of an ether bond, a carbonyl bond, an ester bond, a amide bond, and an imine bond (-NH-). The base.

The substituent which the divalent hydrocarbon group represented by R ¹¹ may have is the same as the substituent which the monovalent hydrocarbon group represented by R ¹⁰ may have.

As the divalent hydrocarbon group represented by R ¹¹ , in terms of impact resistance and bending resistance, an alkylene group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms is preferred, Furthermore, an alkylene group having 2 or more and 4 or less carbon atoms is more preferable, and the alkylene group is preferably linear or branched.

A diamine having one or two silicon atoms as a main chain, and especially a diamine having two silicon atoms is preferable in terms of light transmittance, impact resistance, and bending resistance. Further, 1, 3-bis (3-aminopropyl) tetramethyldisilaxane, 1,3-bis (4-aminobutyl) tetramethyldisilaxane, 1,3-bis (5-amino Pentyl) tetramethyldisilaxane and the like are preferred from the viewpoint of achieving ease, transparency, and impact resistance at the same time.

In terms of impact resistance and bending resistance, the molecular weight of the diamine residue having 1 or 2 silicon atoms in the main chain is preferably 1,000 or less, more preferably 800 or less, and even more preferably 500 or less, and particularly preferably It is 300 or less.

The diamine residue having one or two silicon atoms in the main chain may be used alone or in combination of two or more kinds.

In addition, the polyimide film of the present invention is preferably the one having the largest Young's modulus among all the polyimide layers that the polyimide film has in terms of light transmittance, impact resistance, and bending resistance. The polyimide layer contains a polyimide having a structure represented by the following general formula (1).

(In the general formula (1), R ¹ represents a group selected from 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride residues, 3,3', 4,4'-benzophenone tetracarboxylic acid. At least one tetravalent group in the group consisting of an acid dianhydride residue and a pyromellitic dianhydride residue, and R ² represents a group selected from 2,2′-bis (trifluoromethyl) benzidine residues, 4,4'-diaminodiphenylphosphonium residue, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane residue, bis [4- (3-amino Phenoxy) phenyl] fluorene residue, bis [4- (4-aminophenoxy) phenyl] fluorene residue, 4,4'-diamino-2,2'-bis (trifluoromethyl) Group) diphenyl ether residue, 1,4-bis [4-amino-2- (trifluoromethyl) phenoxy] benzene residue, 2,2-bis [4- (4-amino-2 -Trifluoromethylphenoxy) phenyl] hexafluoropropane residue, 4,4'-diamino-2- (trifluoromethyl) diphenyl ether residue, and 9,9-bis (4- Aminophenyl) at least one divalent group in the group consisting of fluorene residues; n represents the number of repeating units and is 1 or more)

Regarding R ^{1 in} the general formula (1), a pyromellitic dianhydride residue is preferred in terms of improving impact resistance.

Regarding R ² of the general formula (1), among them, in terms of light transmittance, impact resistance, and bending resistance, it is preferably selected from 2,2′-bis (trifluoromethyl) benzidine residues. At least one divalent group of bis [4- (3-aminophenoxy) phenyl] fluorene residue, and bis [4- (4-aminophenoxy) phenyl] fluorene residue, More preferred is a 2,2, -bis (trifluoromethyl) benzidine residue.

In the structure represented by the general formula (1), n represents the number of repeating units, and is 1 or more.

The number of repeating units n in the polyfluorene imine may be appropriately selected according to the structure so as to exhibit a desired Young's modulus, and is not particularly limited. It is usually 10 or more and 2000 or less, and more preferably 15 or more and 1,000 or less. .

Furthermore, each of R ¹ in each repeating unit may be the same or different, and each of R ² in each repeating unit may be the same or different.

Of all the polyimides contained in the polyimide layer having the largest Young's modulus, the content of the polyimide having the structure represented by the general formula (1) above is light transmittance and impact resistance. In terms of bending resistance, it is preferably 60% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and even more preferably 100% by mass.

In addition, the polyimide used in the present invention may contain one or two or more polyimides having a structure represented by the general formula (1).

In addition, the polyimide film of the present invention is preferably one having the largest Young's modulus among all the polyimide layers that the polyimide film has in terms of light transmittance, impact resistance, and bending resistance. The polyimide layer contains a polyimide having a structure represented by the general formula (1), and the polyimide film further includes a polyimide layer including the following polyimide layer. Polyfluorene imine having a structure represented by formula (2). That is, the polyimide layer different from the polyimide layer having the largest Young's modulus contains a polyimide having a structure represented by the following general formula (2).

(In the general formula (2), R ³ represents a tetravalent residue of a tetracarboxylic acid residue having an aromatic ring or an aliphatic ring, R ⁴ represents a diamine residue of a divalent residue, and 50% of the total amount of R ⁴ Molar% or less Diamine residues having 1 or 2 silicon atoms in the main chain, and the remaining R ⁴ are diamine residues having no silicon atom and having an aromatic ring or an aliphatic ring, and the remaining R ⁴ More than half of them are selected from the group consisting of 1,4-cyclohexanediamine residues, trans-1,4-bismethylenecyclohexanediamine residues, 4,4'-diaminodiphenylsulfonium Residue, 3,4'-diaminodiphenylfluorene residue, bis [4- (3-aminophenoxy) phenyl] fluorene residue, bis [4- (4-aminophenoxy ) Phenyl] fluorene residue, 2,2-bis (4-aminophenyl) propane residue, 2,2-bis (4-aminophenyl) hexafluoropropane residue, and the following general formula ( 3) At least one type of divalent base in the group consisting of the divalent base indicated; n 'represents the number of repeating units, and is 1 or more)

(In the general formula (3), R ⁵ and R ⁶ are each independently and represent a hydrogen atom, an alkyl group, or a perfluoroalkyl group.)

R ^{3 in} the general formula (2) can be appropriately selected from the tetracarboxylic acid components described above to remove a residue of an acid dianhydride structure from a tetracarboxylic dianhydride having an aromatic ring or a tetracarboxylic acid having an aliphatic ring. The dianhydride removes the residue of the acid dianhydride structure and is not particularly limited. Among them, in terms of light transmission and impact resistance, it is more preferably selected from 4,4 ′-(hexafluoroisopropylidene). Diphthalic anhydride residue, 3,4 '-(hexafluoroisopropylidene) bisphthalic anhydride residue, 3,3'-(hexafluoroisopropylidene) bisphthalic anhydride At least one tetravalent group in a group consisting of a residue, a 4,4'-oxybisphthalic anhydride residue, and a 3,4'-oxybisphthalic anhydride residue, and more preferably Selected from the group consisting of 4,4 '-(hexafluoroisopropylidene) bisphthalic anhydride residues, 3,4'-(hexafluoroisopropylidene) bisphthalic anhydride residues, and 3,3 ' -At least one tetravalent group in a group consisting of (hexafluoroisopropylidene) bisphthalic anhydride.

It is also preferable that R ³ is selected from the group consisting of a pyromellitic dianhydride residue, a 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride residue, and 2,2', 3, At least one of the group consisting of 3'-biphenyltetracarboxylic dianhydride residues is a group of tetracarboxylic acid residues (group A) suitable for improving rigidity and, for example, selected from cyclohexanetetracarboxylic dianhydride residues , Cyclopentane tetracarboxylic dianhydride residue, dicyclohexane-3,4,3 ', 4'-tetracarboxylic dianhydride residue, cyclobutane tetracarboxylic dianhydride residue, 4,4' -(Hexafluoroisopropylidene) bisphthalic anhydride residue, 3,4 '-(hexafluoroisopropylidene) bisphthalic anhydride residue, 3,3'-(hexafluoroisopropylidene) (Propyl) at least one of the group consisting of a bisphthalic anhydride residue, a 4,4'-oxybisphthalic anhydride residue, and a 3,4'-oxybisphthalic anhydride residue It is suitable for mixed use of a group of tetracarboxylic acid residues (group B) suitable for improving light transmission. In this case, the content ratio of the tetracarboxylic acid residue group (group A) suitable for improving rigidity to the tetracarboxylic acid residue group (group B) suitable for improving light transmittance is preferably relative to The tetracarboxylic acid residue group (group B) for improving light transmittance is 1 mole, and the above-mentioned tetracarboxylic acid residue group (group A) suitable for improving rigidity is 0.05 mol or more and 9 mol or less, which is more preferable. It is 0.1 mol or more and 5 mol or less, and more preferably 0.3 mol or more and 4 mol or less.

Among them, as the group B, in terms of improvement of impact resistance and light transmittance, it is preferable to use a 4,4 ′-(hexafluoroisopropylidene) bisphthalic anhydride residue containing a fluorine atom. And at least one of 3,4 '-(hexafluoroisopropylidene) bisphthalic anhydride residues.

When R ³ contains a tetracarboxylic acid residue of the group A, in terms of bending resistance, it is preferable that R ⁴ of the general formula (2) includes one in which the main chain has one or two silicon atoms. Diamine residue.

In the above-mentioned R ³ , it is preferable to include these preferable residues in a total amount of 50 mol% or more, more preferably 70 mol% or more, and even more preferably 90 mol% or more.

In R ⁴ in the above general formula (2), the content ratio of the diamine residue having one or two silicon atoms in the main chain is not particularly limited as long as it is 50 mol% or less of the total amount of R ⁴ . It may not be contained. In terms of improving the adhesion between layers, suppressing the occurrence of interference fringes, and easily improving impact resistance, it is preferable to contain 1 mol of a diamine residue having 1 or 2 silicon atoms in the main chain. % Or more and 50 mol% or less, more preferably 2.5 mol% or more and 40 mol% or less.

Examples of the diamine residue having one or two silicon atoms in the main chain include residues obtained by removing two amine groups from the diamine having one or two silicon atoms in the main chain. Among them, in terms of light transmittance, and impact resistance and bending resistance, a diamine residue having two silicon atoms is preferred, and at the same time, ease, light transmittance, and impact resistance are obtained. From the viewpoint of realization, 1,3-bis (3-aminopropyl) tetramethyldisilazane residue and 1,3-bis (4-aminobutyl) tetramethyldisilazane are preferred. Oxane residues, 1,3-bis (5-aminopentyl) tetramethyldisilazane residues, and the like.

Regarding the above-mentioned R ⁴ and the total amount of R ⁴ , except for the diamine residue having 1 or 2 silicon atoms in the main chain, R ⁴ has no silicon atom and has an aromatic ring or an aliphatic ring. More than half of the remaining R ⁴ above are selected from the group consisting of 1,4-cyclohexanediamine residues, trans-1,4-bismethylenecyclohexanediamine residues (trans Formula-1,4-bis (aminomethyl) cyclohexane residue), 4,4'-diaminodiphenylfluorene residue, 3,4'-diaminodiphenylfluorene residue, Bis [4- (3-aminophenoxy) phenyl] fluorene residue, bis [4- (4-aminophenoxy) phenyl] fluorene residue, 2,2-bis (4-amino At least one of the groups consisting of a phenyl) propane residue, a 2,2-bis (4-aminophenyl) hexafluoropropane residue, and a divalent group represented by the general formula (3) Group (hereinafter sometimes referred to as "at least one divalent group selected from the group").

That is, if the diamine residue having one or two silicon atoms in the main chain is set to x mole% (0 ≦ x ≦ 50) in the total amount of R ⁴ (100 mole%), then (100-x) mol% of R ⁴ is 50 mol% or more and 100 mol% or less is a diamine residue having no silicon atom and having an aromatic ring or an aliphatic ring, and the amount of R ⁴ exceeding {(100 -x) / 2} mol% is at least one kind of divalent group selected from the above group. Among them, the ratio of the at least one divalent group selected from the above group among the remaining R ⁴ is the total of the diamine residues having no silicon atom and having an aromatic ring or an aliphatic ring. The ratio of at least one type of divalent group selected from the above group when the amount is set to 100 mol% is preferably 70 mol% or more in terms of surface hardness and impact resistance and light transmittance. , More preferably 85 mol% or more, and even more preferably 95 mol% or more. In addition, R ⁴ may contain other diamine residues which do not have a silicon atom and have an aromatic ring or an aliphatic ring different from at least one divalent group selected from the above group.

Here, the diamine residue having no silicon atom and having an aromatic ring may be a residue obtained by removing two amine groups from a diamine having no silicon atom and having an aromatic ring, and having no silicon atom and having The diamine residue of the aliphatic ring may be a residue obtained by removing two amine groups from a diamine having no silicon atom and having an aliphatic ring. The diamine used as R ⁴ which may be different from at least one divalent group selected from the above group and which does not have a silicon atom and has an aromatic ring or an aliphatic ring can be used, for example, from the above. Among the diamines, a diamine having no silicon atom and having an aromatic ring or an aliphatic ring is appropriately selected and used, and is not particularly limited.

As at least one kind of divalent group selected from the above group, in terms of impact resistance and light transmittance, it is preferably selected from the group consisting of trans-1,4-bismethylenecyclohexanediamine residues. Group, 4,4'-diaminodiphenylfluorene residue, 3,4'-diaminodiphenylfluorene residue, bis [4- (3-aminophenoxy) phenyl] fluorene residue Group, bis [4- (4-aminophenoxy) phenyl] fluorene residue, 2,2-bis (4-aminophenyl) propane residue, 2,2-bis (4-aminobenzene Group) a hexafluoropropane residue and at least one type of divalent group in the group consisting of the divalent group represented by the general formula (3), and more preferably the divalent group represented by the general formula (3). As the divalent group represented by the above-mentioned general formula (3), among them, R ⁵ and R ⁶ are more preferably a perfluoroalkyl group, and among them, a perfluoroalkyl group having a carbon number of 1 or more and 3 or less is more preferable. It is trifluoromethyl or perfluoroethyl. The alkyl groups of R ⁵ and R ⁶ in the general formula (3) are preferably alkyl groups having 1 to 3 carbon atoms, and more preferably methyl or ethyl groups.

In addition, in terms of improving the impact resistance and light transmittance of the polyfluorene imide film of the present invention, at least one of the two valences selected from the above group is preferably 50 mol based on the total amount of R ⁴ Above ⁴ %, it is particularly preferred that among the total amount of R ⁴ , except for the diamine residues in the main chain having 1 or 2 silicon atoms, all of R ⁴ are at least one divalent selected from the above group. base.

When R ⁴ contains a diamine residue that does not have a silicon atom and has an aromatic ring or an aliphatic ring that is different from at least one divalent group selected from the group, the content ratio is not particularly limited. In terms of impact resistance and light transmittance, the total amount of R ⁴ (100 mol%) is preferably 30 mol% or less, more preferably 20 mol% or less, and even more preferably 10 Moore% or less.

In the structure represented by the general formula (2), n ′ represents the number of repeating units, and is 1 or more.

The number of repeating units n 'in the polyimide may be appropriately selected depending on the structure so as to exhibit the required Young's modulus, and is not particularly limited. It is usually 10 or more and 2000 or less, and more preferably 15 or more and 1000. the following.

Furthermore, each of R ³ in each repeating unit may be the same or different, and each of R ⁴ in each repeating unit may be the same or different.

In a polyimide layer containing a polyimide having a structure represented by the general formula (2), the content ratio of the polyimide is in terms of light transmittance, impact resistance, and bending resistance. It is preferably 60% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and even more preferably 100% by mass.

The polyimide used in the present invention may contain one or two or more polyimides having a structure represented by the general formula (2).

In addition, the polyimide film of the present invention has the following polyimide layer, which is preferable in terms of light transmittance and bending resistance, and also preferable in terms of impact resistance. The polyimide The layer contains polyimide having a structure represented by the general formula (2). From the viewpoint of further improving impact resistance, the polyimide film of the present invention can contain a polyimide layer having a structure represented by the general formula (1) by making the polyimide layer having the largest Young's modulus. The amine does not contain a polyimide having the structure represented by the general formula (2) to further improve the impact resistance. The polyimide layer having the largest Young's modulus contains the polyimide layer having the general formula (2). The polyimide layer of the polyimide structure may also be a polyimide layer having a polyimide layer having a structure represented by the general formula (2). Imine layer.

Among all the polyimide layers that the polyimide film has, the polyimide layer having the largest Young's modulus contains a polyimide having a structure represented by the general formula (1), and further has the following In the polyimide film of the polyimide layer, in terms of bending resistance and impact resistance, the total thickness of the polyimide layer having the largest Young's modulus is preferably the entire polyimide film. The polyimide layer contains a polyimide having a structure represented by the general formula (2) above 5% and 60%.

In a polyimide film in which all the polyimide layers included in the polyimide film are polyimide layers containing a polyimide having a structure represented by the general formula (2) described above, bending resistance and In terms of impact resistance, it is preferable that the total thickness of the polyimide layer having the largest Young's modulus be 5% or more and 30% or less, and more preferably 5% or more of the overall thickness of the polyimide film. 20% or less, more preferably 5% or more and 15% or less.

The polyimide layer having the largest Young's modulus among all the polyimide layers included in the polyimide film includes a polyimide having a structure represented by the general formula (1), and further has In the polyimide film of the polyimide layer described below, in terms of impact resistance and bending resistance, the Young's modulus of the polyimide layer having the largest Young's modulus is preferably a Young's modulus. The polyimide layer having the smallest number is more than 1.5 times the Young's modulus, especially in terms of impact resistance, more preferably 1.7 times or more, and even more preferably 1.8 times or more. It contains a polyimide having a structure represented by the general formula (2).

In a polyimide film in which all the polyimide layers included in the polyimide film are polyimide layers containing a polyimide having a structure represented by the general formula (2), the impact resistance is high. In terms of bending resistance, it is preferable that the Young's modulus of the polyimide layer having the largest Young's modulus is 1.2 times or more the Young's modulus of the polyimide layer having the smallest Young's modulus, and It can be 2.0 times or less and 1.8 times or less.

In addition, as for the polyimide used in the present invention, as long as the effect of the present invention is not impaired, the polyimide structure may be included in a part thereof. Examples of the polyamine structure that can be included include a polyamine structure comprising a tricarboxylic acid residue such as trimellitic anhydride, or a polyamine structure containing a dicarboxylic acid residue such as terephthalic acid. structure.

In terms of heat resistance, the polyimide used in the present invention preferably has a glass transition temperature of 200 ° C or higher, more preferably 250 ° C or higher, and even more preferably 270 ° C or higher. On the other hand, in terms of lowering the baking temperature, the glass transition temperature is preferably 400 ° C or lower, and more preferably 380 ° C or lower.

The glass transition temperature of the polyimide used in the present invention is based on the temperature-tanδ (tanδ = loss elastic modulus (E ") / storage elastic modulus (E ')) curve obtained by dynamic viscoelasticity measurement. The peak temperature can be obtained. The glass transition temperature of polyimide, when there are multiple peaks of the tanδ curve, refers to the temperature at which the maximum value of the peak value is the maximum. For dynamic viscoelasticity measurement, for example, The dynamic viscoelasticity measuring device RSA III (TA Instruments Japan (Stock)) was used to set the measurement range from -150 ° C to 400 ° C at a frequency of 1 Hz and a heating rate of 5 ° C / min. The sample width can also be set to The measurement was performed at 5 mm and the inter-chuck distance was 20 mm.

In the present invention, the peak of the tanδ curve refers to a peak having a bending point as a maximum value and a peak width between a valley and a valley of 3 ° C or more. The fluctuation of noise and other sources from the measurement is slightly changed. , Not interpreted as the above peaks.

(2) Additives

Each polyimide layer included in the polyimide film of the present invention may contain an additive in addition to the polyimide as necessary. Examples of the additives include a silicon dioxide filler for smooth winding, a surfactant, and the like for improving film forming properties and defoaming properties.

In addition, each polyimide layer included in the polyimide film of the present invention may contain other resins other than polyimide as long as the effect of the present invention is not impaired. Examples of the other resins include polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyamide resins, polyimide resins, and polyimide resins. Phenyl sulfide resin, polyether ether ketone resin, polyether resin, polycarbonate resin, polyether resin, imine resin, epoxy resin, phenol resin, glass-epoxy resin, polyphenylene ether resin, acrylic resin, poly Polyolefin resins such as ethylene and polypropylene; polycycloolefins such as polynorbornene.

When the polyimide layer contains other resins other than polyimide, the content of the other resin is preferably 50% by mass or less, more preferably 30% by mass or less, based on the total amount of the polyimide layer. Especially preferably, it is 0 mass%.

3. Characteristics of polyimide film

The Young's modulus, the total light transmittance, and the linear thermal expansion coefficient of the polyfluorene imide film of the present invention have already been described above, so the description here is omitted.

Regarding the polyimide film of the present invention, in terms of excellent bending resistance, when the static bending test is performed according to the following static bending test method, the inner angle of the test piece is preferably 90 ° or more, more preferably It is 100 ° or more, and more preferably 110 ° or more. Furthermore, when the Young's modulus of the polyimide layer on one surface is different from the Young's modulus of the polyimide layer on the other surface, it is preferable to compare the Young's modulus with the Young's modulus. When the surface of the large polyimide layer is bent inward, the internal angle of the test piece when the static bending test is performed according to the following static bending test method is equal to or more than the above lower limit.

[Static bending test method]

A test piece cut into a polyimide film of 15 mm × 40 mm was bent at a half of the long side, and a metal piece with a thickness of 6 mm (100 mm × 30mm × 6mm), and use tape to fix the two ends of the test piece and the overlap between the upper and lower parts of the metal piece, respectively. In this state, use a glass plate (100mm × 100mm × 0.7). mm) Clamp from above and below, and fix the test piece in a state of bending with an inner diameter of 6 mm. At this time, a dummy test piece is inserted between the metal piece and the glass plate without the test piece, and the glass plate is parallelized and fixed with an adhesive tape. The test piece fixed in a bent state in this manner was left to stand in an environment of 60 ° C and 90% relative humidity (RH) for 24 hours, and thereafter, the glass plate and the fixing tape were removed, and the test piece was released. The force exerted. Thereafter, one end of the test piece was fixed, and the inner angle of the test piece 30 minutes after the release of the force applied to the test piece was measured.

In terms of impact resistance and bending resistance of the polyimide film of the present invention, it is preferable to set a tensile speed of 10 mm / min and a distance between chucks to a test piece of 15 mm × 40 mm in accordance with JIS K7127. The tensile elastic modulus at 25 ° C. obtained by measuring at 20 mm is 0.5 GPa or more, more preferably 0.8 GPa or more, even more preferably 1.0 GPa or more, even more preferably 1.50 GPa or more, and most preferably 2.0 GPa or more. The upper limit of the tensile elastic modulus is not particularly limited. In terms of bending resistance, it may be set to 5.2 GPa or lower, 5.0 GPa or lower, 4.5 GPa or lower, or 4.0 GPa. the following.

The above tensile elastic modulus can be measured by using a tensile testing machine (for example, made by Shimadzu Corporation: Autograph AG-X 1N; load cell: SBL-1KN), and a test piece having a width of 15 mm and a length of 40 mm can be cut from a polyimide film. The measurement was carried out at a stretching speed of 10 mm / min at a temperature of 20 ° C. with a distance between chucks of 20 mm.

In terms of impact resistance, the polyimide film of the present invention preferably has a pencil hardness of 2B or more, more preferably B or more, even more preferably HB or more, and even more preferably H or more.

The pencil hardness of the above polyimide film can be performed by performing a humidity control on the measurement sample at a temperature of 25 ° C. and a relative humidity of 60% for 2 hours, and thereafter, using JIS-S-6006 The pencil used for the test was subjected to a pencil hardness test (0.98 N load) specified in JIS K5600-5-4 (1999) on the film surface, and the highest pencil hardness without leaving a flaw was evaluated. For example, a pencil scratch coating film hardness tester manufactured by Toyo Seiki Co., Ltd. can be used.

The pencil hardness of the polyimide film is preferably achieved on the surface of the polyimide layer having a relatively large Young's modulus.

In terms of the adhesion between the polyimide layers and the surface hardness, the polyimide film of the present invention is preferably a polyimide on the surface when the adhesion test is performed according to the following adhesion test method. The area where the imine layer is peeled off is 20% or less of the whole, more preferably 10% or less, and even more preferably 5% or less.

<Adhesion test>

According to the grid test of JIS K5400, the polyimide layer on the surface was cut in a grid pattern at a 1 mm interval using a cutter to form 100 crystal lattices. Then, a transparent tape (Nichiban (strand)) was attached to the crystal lattice, followed by peeling. This operation was repeated five times, and then the peeling of the polyimide layer on the surface was observed.

In addition, the yellowness (YI value) of the polyimide film of the present invention calculated in accordance with the above JIS K7373-2006 is preferably 30.0 or less, more preferably 20.0 or less, even more preferably 17.0 or less, and even more preferably 16.0. the following.

The yellowness (Y1 value) calculated according to the above JIS K7373-2006 is particularly preferably 11.0 or less, more preferably 10.0 or less, still more preferably 5.0 or less, even more preferably 3.0 or less, and even more preferably 2.0 or less.

With the above-mentioned yellowness (YI value) being below the above-mentioned upper limit value, the polyimide film of the present invention can suppress the coloration of yellow tones, improve the light transmittance, and can become a glass substitute material.

In addition, the yellowness (YI value) can be determined by a spectrophotometric method using an ultraviolet-visible near-infrared spectrophotometer (for example, Japan Spectrophotometer Co., Ltd. V-7100) in accordance with JIS K7373-2006. The 2 degree field of view is measured at intervals of 1nm from 250nm to 800nm. Based on the obtained transmittance, the three stimulus values X, Y, and Z in the XYZ color system are obtained. Based on the X, Y, and Z values, The value is calculated by the following formula.

YI = 100 (1.2769X-1.0592Z) / Y

In addition, the polyimide film of the present invention can suppress yellow coloration, improve light transmittance, and can be preferably used as a glass substitute material. Preferably, the polyimide film is yellow based on the above JIS K7373-2006. The value (YI value / film thickness (μm)) obtained by dividing the degree (YI value) by the film thickness (μm) is 0.330 or less, more preferably 0.150 or less, even more preferably 0.100 or less, and even more preferably 0.030 or less.

Furthermore, in the present invention, the value (YI value / film thickness (μm)) obtained by dividing the above-mentioned yellowness (YI value) by the film thickness (μm) is in accordance with rule B of JIS Z8401: 1999, and is rounded to Value from the third decimal place.

The haze value of the polyfluorene imide film of the present invention is preferably 10 or less, more preferably 5 or less, and even more preferably 1.5 or less in terms of light transmittance.

The above haze value can be measured by a method according to JIS K-7105, and can be measured by, for example, a haze meter HM150 manufactured by Murakami Color Technology Research Institute.

In addition, the birefringence of the polyfluorene imide film in the thickness direction at a wavelength of 590 nm of the present invention is preferably 0.040 or less, more preferably 0.025 or less, even more preferably 0.020 or less, and even more preferably 0.015 or less. If the birefringence is below the above-mentioned upper limit value, the optical strain of the polyimide film is reduced, and when the polyimide film is used as a surface material for a display, a reduction in display quality of the display can be suppressed. When a film having a large birefringence in a thickness direction at a wavelength of 590 nm is installed on a display surface and the display is worn with polarized sunglasses, rainbow unevenness and visibility may be reduced. In terms of suppressing the occurrence of rainbow unevenness when viewing the display while wearing polarized sunglasses, it is preferable that the birefringence of the film provided on the display surface in the thickness direction is 0.040 or less. Furthermore, as long as the birefringence of the film provided on the display surface in the thickness direction is 0.025 or less, the color reproducibility is improved when the display is viewed obliquely. In terms of improving the color reproducibility when the display is viewed obliquely, the birefringence in the thickness direction of the film provided on the display surface is more preferably 0.020 or less.

The birefringence of the polyfluorene imide film of the present invention in the thickness direction of the above-mentioned wavelength of 590 nm can be determined as follows.

First, using a retardation measuring device (for example, manufactured by Oji Measurement Co., Ltd., product name "KOBRA-WR"), a thickness direction retardation value (Rth) of a polyimide film at 23 ° C with light having a wavelength of 590 nm ). The thickness direction retardation value (Rth) is a phase difference value at a 0-degree incidence and a phase difference value at an oblique 40-degree incidence, and the thickness direction retardation value Rth is calculated based on the retardation values. The above-mentioned retardation value at an angle of 40 degrees is measured by making light having a wavelength of 590 nm incident on the retardation film from a direction inclined from the normal of the retardation film by 40 degrees.

The birefringence in the thickness direction of the polyfluoreneimide film can be obtained by substituting into the formula: Rth / d. The above-mentioned d represents the film thickness (nm) of the polyfluoreneimide film.

In addition, regarding the thickness direction retardation value, the refractive index of the late phase axis direction (the direction in which the refractive index in the film surface direction becomes maximum) of the film in-plane direction is set to nx, and the phase advance axis in the film surface is set. When the refractive index in the direction (the direction in which the refractive index in the film surface becomes the smallest) is set to ny and the refractive index in the thickness direction of the film is set to nz, it can be expressed as Rth [nm] = {(nx + ny) / 2-nz} × d.

In addition, as a preferred form of the polyfluorene imide film of the present invention, the number of fluorine atoms (F) and carbon atoms (at least one surface of the film) of the polyfluorine film measured by X-ray photoelectron spectroscopy ( The ratio (F / C) of C) is preferably 0.01 or more and 1 or less, and more preferably 0.05 or more and 0.8 or less.

In addition, the ratio (F / N) of the number of fluorine atoms (F) to the number of nitrogen atoms (N) of at least one film surface of the polyfluoreneimide film measured by X-ray photoelectron spectroscopy is preferably 0.1 or more and 20 or less, more preferably 0.5 or more and 15 or less.

Here, the above ratio obtained by measurement by X-ray photoelectron spectroscopy (XPS) can be based on the value of atomic% of each original character measured using an X-ray photoelectron spectroscopy device (for example, Theta Probe from Thermo Scientific). Find it out.

4. Manufacturing method of polyimide film

The method for producing a polyimide film of the present invention is not particularly limited as long as it is a method for obtaining the above-mentioned polyimide film of the present invention. For example, a production method including the following steps may be cited as the first production method: A step of preparing a polyimide formed article; a step of preparing a polyimide precursor resin composition including a polyimide precursor and an organic solvent; and coating the above polymer on at least one side of the polyimide formed article A step of forming a polyimide precursor resin composition on the fluorene imine precursor resin composition; and a step of imidating the polyfluorene imine precursor by heating.

In the above-mentioned first production method, as a method for producing a polyimide film having three or more polyimide layers, for example, the following method can be mentioned: coating a polyimide precursor resin composition to form a polyimide The step of coating the fluorene imine precursor resin until it reaches the required number of layers, and then, by using the step of performing the fluorene imidization, each polyimide precursor contained in each of the fluorene imine precursor resin coating film is coated.醯 imidization. In addition, the polyimide precursor resin coating film of two or more layers may be formed only on one side of the polyimide molded article, or may be formed on one side and the other side of both sides.

As a method for producing a polyimide film having three polyimide layers by the above-mentioned first production method, for example, the following production method may be mentioned. The method includes the following steps: a step of preparing a polyimide shaped body; preparation The steps of the first polyimide precursor resin composition and the second polyimide precursor resin composition. The first polyimide precursor resin composition contains a polyimide precursor and an organic solvent. The second polyimide precursor resin composition contains a polyimide precursor and an organic solvent; the first polyimide precursor resin composition is coated on one side of the polyimide molded article to form a first polyimide precursor resin composition. A step of coating the polyimide precursor resin; coating the second polyimide precursor resin composition on the other side of the polyimide formed article to form a second polyimide precursor resin coating film A step; and the polyimide precursor contained in the first polyimide precursor resin coating film and the polyimide precursor contained in the second polyimide precursor resin coating film by heating Step of amination; and before the first polyimide Resin composition and the second composition of the polyimide resin precursor composition may be of the same composition.

In the above-mentioned first manufacturing method, each polyimide precursor resin coating film formed so as to form the polyimide molded article and a desired number of layers becomes a polyimide layer.

The said 1st manufacturing method is preferable at the point which is easy to reduce the birefringence of a polyfluorene imide film. According to the first manufacturing method, a polyimide film having a birefringence in a thickness direction at a wavelength of 590 nm of 0.035 or less, more preferably 0.030 or less, more preferably 0.025 or less, and more preferably 0.020 or less can be preferably formed. .

In the above-mentioned first manufacturing method, when two or more polyimide layers are formed on one surface of the polyimide formed article, it is more advantageous in terms of improving the adhesion between layers and suppressing the occurrence of interference fringes. It is preferable to perform the above step of imidization after forming all the polyimide precursor resin coating films used for forming the two or more layers of the polyimide layer. The reason is that it can be applied to the two layers. The above-mentioned polyimide layer has borders of adjacent polyimide layers to form the above-mentioned mixed region.

In the following, the step of preparing a polyimide molded article (hereinafter, referred to as a preparation step of preparing polyimide) and the step of preparing a polyimide precursor resin composition (hereinafter, referred to as a step) Polyimide precursor resin composition preparation step), coating polyimide precursor resin composition to form a polyimide precursor resin coating film (hereinafter, referred to as polyimide precursor resin coating The film formation step) and the step of fluorinating the polyfluorene imide precursor contained in the polyfluorene imide precursor resin composition (hereinafter referred to as the fluorene imine step) will be described in detail.

(1) Preparation procedure of polyimide shaped body

As the polyimide molded article used in the first production method, for example, a film-shaped polyimide molded article produced by the following production method can be used.

As a method for producing a film-shaped polyimide molded article, for example, a production method including the following steps can be cited as the production method A: preparing a polyimide precursor resin composition including a polyimide precursor and an organic solvent A step of coating the polyimide precursor resin composition on a support to form a polyimide precursor resin coating film; and imidating the polyimide precursor by heating The steps.

The above-mentioned manufacturing method A is preferable in terms of easy reduction of the birefringence of the polyfluorene imide film, and can form a polymer having a birefringence in a thickness direction at a wavelength of 590 nm of 0.025 or less, more preferably 0.020 or less.醯 imine film. In view of the high effect of reducing the birefringence of the polyimide film, it is more preferable to use the above-mentioned production method A as the production method of the polyimide formed article in the first production method, which may be more preferable. A polyimide film having a birefringence in a thickness direction at a wavelength of 590 nm of 0.025 or less, and more preferably 0.020 or less is formed.

In the above production method A, as the polyimide precursor resin composition, a polyimide precursor obtained from "Polyimide precursor resin composition preparation step" described later can be used. For the same resin composition, the method of forming a polyimide precursor resin coating film and the method of amidation may be set to the "polyimide precursor resin coating film" described later. The formation step is the same as the fluorene imidization step.

In the above-mentioned production method A, examples of the support include the same as those used in the second production method described later.

The production method A may further include at least at least a polyimide precursor resin coating film and a polyimide precursor coating film obtained by subjecting the polyimide precursor resin coating film to imidization. One performs the extension step. The extending step may be the same as the extending step of the second manufacturing method which will be described later.

As another method for producing a film-shaped polyimide molded article, for example, a production method including the following steps may be cited as the production method B: preparing a polyimide resin composition containing polyimide and an organic solvent. A step of coating the polyimide resin composition on a support to form a polyimide resin coating film.

The above-mentioned production method B can be preferably used in a case where the polyimide used has a solvent solubility of 5 mass% or more as dissolved in an organic solvent at 25 ° C.

The manufacturing method B described above is preferable in terms of easily reducing the yellowness (YI value) of the polyimide film, and it is possible to form the yellowness (YI value) calculated by the above JIS K7373-2006 divided by the film thickness. (μm) The obtained polyimide film has a value (YI value / film thickness (μm)) of 0.330 or less, more preferably 0.200 or less, and even more preferably 0.150 or less.

In the above-mentioned production method B, as the polyimide resin composition, the same as the polyimide resin composition of the third production method to be described later can be used as the polyimide resin coating film. The method can be the same as the polyimide resin coating film forming step of the third manufacturing method which will be described later.

Moreover, in the said manufacturing method B, as a support body, the same support body used for the 2nd manufacturing method mentioned later is mentioned, for example.

(2) Preparation steps of polyimide precursor resin composition

The polyimide precursor resin composition prepared in the above-mentioned first production method contains a polyimide precursor and an organic solvent, and may contain additives and the like as necessary.

The polyimide precursor is a polyamidic acid obtained by polymerization of a tetracarboxylic acid component and a diamine component. In the above-mentioned first production method, the tetracarboxylic acid component and the diamine component used in the polyfluorene imide precursor are not particularly limited, and examples thereof include the above-mentioned tetracarboxylic acid which becomes the tetracarboxylic acid residue of the polyfluorene Dianhydrides and diamines which become diamine residues.

The number average molecular weight of the polyimide precursor is preferably 2,000 or more, and more preferably 4,000 or more, in terms of strength at the time of film formation. On the other hand, if the number average molecular weight is too large, it will have a high viscosity and may reduce workability. It is preferably 1,000,000 or less, and more preferably 500,000 or less.

The number average molecular weight of the polyfluorene imide precursor can be determined by NMR (for example, manufactured by BRUKER, AVANCEIII). For example, a polyfluorene imide precursor solution can be applied to a glass plate and dried at 100 ° C. for 5 minutes. Thereafter, 10 mg of a solid component can be dissolved in 7.5 ml of a dimethylimine-d6 solvent and subjected to NMR. The number average molecular weight was calculated from the peak intensity ratio of hydrogen atoms bonded to the aromatic ring.

In addition, in terms of strength when the polyimide precursor is formed into a film, the weight average molecular weight is preferably 2,000 or more, and more preferably 4,000 or more. On the other hand, if the weight average molecular weight is too large, it will have a high viscosity and may reduce the workability of filtration and the like. It is preferably 1,000,000 or less, and more preferably 500,000 or less.

The weight average molecular weight of the polyimide precursor can be measured by gel permeation chromatography (GPC). Specifically, a polyimide precursor was prepared as an N-methylpyrrolidone (NMP) solution at a concentration of 0.5% by weight, and a 10 mmol% LiBr-NMP solution having a water content of 500 ppm or less was used as a developing solvent. A GPC apparatus (HLG-8120; using a column: GPC LF-804 manufactured by SHODEX) was measured under conditions of a sample injection amount of 50 μL, a solvent flow rate of 0.5 mL / min, and 40 ° C. The weight average molecular weight was calculated based on a polystyrene standard sample having the same concentration as the sample.

The polyfluorene imide precursor solution is obtained by reacting the tetracarboxylic dianhydride and the diamine in a solvent. The solvent used in the synthesis of the polyimide precursor (polyamidic acid) is not particularly limited as long as it can dissolve the tetracarboxylic dianhydride and diamine. For example, an aprotic polar solvent or a water-soluble alcohol can be used. Department of solvents, etc. In the present invention, it is particularly preferable to use N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylmethane, hexamethylene Organic solvents containing nitrogen atom, such as phosphinoxamine, 1,3-dimethyl-2-imidazolidinone; γ-butyrolactone, etc. Among them, an organic solvent containing a nitrogen atom is preferably used, and more preferably, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, or a combination thereof is used. The organic solvent is a solvent containing carbon atoms.

In the case where two or more kinds of diamines are combined to prepare the polyfluorene imide precursor solution, an acid dianhydride may be added to a mixed solution of two or more kinds of diamines to synthesize a polyamino acid, or two kinds of The above diamine component is added to the reaction solution in stages at an appropriate molar ratio, and the order in which each raw material is added to the polymer chain is controlled to a certain extent.

When a diamine having one or two silicon atoms in the main chain is used, for example, the following method can be used: Put the diamine having one or two silicon atoms in the reaction solution in which the main chain has 1 The 0.5 or more equivalent molar ratio of acid dianhydride of diamine of one or two silicon atoms is reacted, thereby synthesizing the diamine having one or two silicon atoms in the main chain for both ends of the acid dianhydride and The ammonium acid formed by the reaction is charged with all or a part of the remaining diamine, and an acid dianhydride is added to polymerize the amidine. When polymerization is performed by this method, a diamine having one or two silicon atoms in the main chain is introduced into the polyamic acid in the form of being linked through one acid dianhydride. When polyamic acid is polymerized by this method, the positional relationship of amidine having one or two silicon atoms in the main chain is specified to some extent, and a film excellent in impact resistance and bending resistance is easily obtained. In terms of better.

When setting the mole number of the diamine in the polyfluorene imide precursor solution (polyamino acid solution) to X and the mole number of the tetracarboxylic dianhydride to Y, it is preferable to set Y / X is 0.9 or more and 1.1 or less, more preferably 0.95 or more and 1.05 or less, still more preferably 0.97 or more and 1.03 or less, and even more preferably 0.99 or more and 1.01 or less. By setting it as such a range, the molecular weight (degree of polymerization) of the obtained polyamic acid can be adjusted appropriately.

The order of the polymerization reaction can be appropriately selected from known methods and is not particularly limited.

In addition, the polyimide precursor solution obtained by the synthesis reaction may be used directly, and other components may be mixed therein as required, or the solvent of the polyimide precursor solution may be dried and dissolved in other solvents. use.

The viscosity of the polyfluorene imide precursor solution at 25 ° C is preferably 500 cps or more and 100,000 cps or less in terms of forming a uniform coating film and a polyimide layer.

The viscosity of the polyimide precursor solution can be measured using a viscometer (eg, TVE-22HT, Toki Sangyo Co., Ltd.) at 25 ° C and a sample volume of 0.8 ml.

The said polyfluorene imide precursor resin composition contains an additive as needed. Examples of the additives include a silica filler for smooth winding, a surfactant for improving film-forming properties and defoaming properties, and the same as those described in the polyimide layer. .

The organic solvent used in the polyfluorene imide precursor resin composition is not particularly limited as long as it can dissolve the polyfluorine imide precursor. For example, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfine, hexamethylphosphamide, A nitrogen atom-containing organic solvent such as 1,3-dimethyl-2-imidazolidinone; γ-butyrolactone, and the like; among them, an organic solvent containing a nitrogen atom is preferably used.

The content of the polyimide precursor in the polyimide precursor resin composition is preferably a resin composition in terms of forming a uniform coating film and a polyimide layer having operable strength. The solid content of the product is 50% by mass or more, and more preferably 60% by mass or more, and the upper limit may be appropriately adjusted according to the contained component.

In terms of forming a uniform coating film and a polyimide layer, the organic solvent in the aforementioned polyimide precursor resin composition is preferably 40% by mass or more, and more preferably 50% in the resin composition. The mass% or more is preferably 99 mass% or less.

In addition, the polyimide precursor resin composition described above preferably has a moisture content of 1,000 ppm or less in terms of improving the storage stability of the polyimide precursor resin composition and improving productivity. . If a large amount of water is contained in the polyimide precursor resin composition, the polyimide precursor may be easily decomposed.

The water content in the polyimide precursor resin composition can be determined using a Karl Fischer moisture meter (for example, Mitsubishi Chemical Co., Ltd., trace moisture measuring device CA-200).

(3) Polyimide precursor resin coating film forming step

In the step of forming the polyimide precursor resin coating film by coating the polyimide precursor resin composition on at least one side of the polyimide molded article, the coating means may be a film capable of forming a target film. There is no particular limitation on the method for thick coating. For example, a die coater, a corner wheel coater, a roll coater, a gravure coater, a curtain coater, and a spray coater can be used. , Die lip coater, etc.

The coating can be performed by a one-piece coating device or by a roll-to-roll coating device.

After coating the polyimide precursor resin composition, the solvent in the polyimide precursor resin composition is dried at a temperature of 150 ° C. or lower, preferably 30 ° C. or higher and 120 ° C. or lower, until the coating film is changed. Not sticky. By setting the drying temperature of the solvent to 150 ° C. or lower, the imidization of the polyamidic acid can be suppressed.

The drying time can be appropriately adjusted according to the film thickness of the polyimide precursor resin coating film, the type of solvent, and the drying temperature. Usually, it is preferably 1 minute to 60 minutes, and more preferably 2 minutes to 30. minute. When it exceeds the upper limit, it is not good in terms of the production efficiency of the polyimide film. On the other hand, when it is lower than the lower limit, the appearance of the obtained polyimide film may be affected by the rapid drying of the solvent.

The method for drying the solvent is not particularly limited as long as the solvent can be dried at the above temperature. For example, an oven, a drying oven, a hot plate, or infrared heating can be used.

When a high degree of management of optical characteristics is required, the environment in which the solvent is dried is preferably an inert gas environment. Under an inert gas environment, a nitrogen environment is preferred, an oxygen concentration is preferably 100 ppm or less, and more preferably 50 ppm or less. When the heat treatment is performed in the atmosphere, the film may be oxidized and colored, or the performance may be reduced.

(4) Step of imidization

In the said 1st manufacturing method, the said polyfluorene imide precursor fluorene is imidized by heating.

The temperature of the fluorene imidization can be appropriately selected according to the structure of the fluorene imine precursor.

In general, it is preferable to set the initial temperature increase temperature to 30 ° C or higher, and more preferably to 100 ° C or higher. On the other hand, the temperature increase end temperature is preferably 250 ° C or higher.

The heating rate is preferably appropriately selected according to the film thickness of the obtained polyimide layer. When the film thickness of the polyimide layer is thick, it is preferable to slow down the heating rate.

In terms of production efficiency of the polyimide film, it is preferably set to 5 ° C / min or more, and more preferably set to 10 ° C / min or more. On the other hand, the upper limit of the heating rate is usually set to 50 ° C / min, preferably 40 ° C / min or less, and further preferably 30 ° C / min or less. The above-mentioned temperature increase rate can suppress the appearance of the film or decrease the strength, and can control the whitening accompanying the fluorene imidization reaction, which is preferable in terms of improvement in light transmittance.

The temperature increase may be performed continuously or stepwise, and it is preferable to perform the temperature continuously in terms of suppressing the appearance of the film or lowering the strength, and controlling the whitening accompanying the amidine reaction. In addition, the heating rate may be fixed in the above-mentioned entire temperature range, or it may be changed midway.

The temperature at which the hydrazone is imidized is preferably in an inert gas environment. Under an inert gas environment, a nitrogen environment is preferred, an oxygen concentration is preferably 100 ppm or less, and more preferably 50 ppm or less. When the heat treatment is performed in the atmosphere, the film is oxidized, and there is a possibility of coloration and performance degradation.

However, when more than 50% of the hydrogen atoms bonded to carbon atoms contained in the polyfluorene imide are hydrogen atoms directly bonded to the aromatic ring, oxygen has less influence on the optical characteristics, even if it is not used. Polyimide with high light transmission can also be obtained in an inert gas environment.

The heating method used for fluorene imidization is not particularly limited as long as the temperature can be raised at the above temperature, and for example, an oven, a heating furnace, infrared heating, electromagnetic induction heating, or the like can be used.

When the final polyfluorene imide film is obtained, it is preferred to advance the reaction to 90% or more, and then 95% or more, and 100%.

When the reaction progresses to 90% or more and 100% of the imidization, it is preferable to maintain the fixed time at the end of the temperature rise. The holding time is usually 1 minute to 180 minutes, and more preferably 5 minutes to 150 minutes.

In addition, the measurement of the sulfonium imidization rate can be performed by analysis of a spectrum obtained by infrared measurement (IR) or the like.

As a second manufacturing method of the polyimide film of the present invention, for example, a method including the following steps may be mentioned: separately preparing a first polyimide precursor resin composition and a second polyimide precursor resin composition Step: the first polyimide precursor resin composition includes a polyimide precursor and an organic solvent, and the second polyimide precursor resin composition includes a polyimide precursor and an organic solvent; A step of applying the first polyimide precursor resin composition to a support to form a first polyimide precursor resin coating film; and applying the above onto the first polyimide precursor resin coating film A step of forming a second polyimide precursor resin composition to form a second polyimide precursor resin coating film; and polymerizing the polyimide precursor resin composition contained in the first polyimide precursor resin composition by heating A step of fluorinating the fluorene imine precursor and the fluorene imine precursor contained in the second polyfluorene imine precursor resin composition;

In the second manufacturing method, as a method for manufacturing a polyimide film having three or more polyimide layers, for example, the following method can be mentioned: coating a polyimide precursor resin composition to form a polyimide The step of coating the imine precursor resin coating film until the required number of layers is obtained, and thereafter, each of the polyimide precursors contained in each of the polyimide precursor resin coating films is subjected to the above-described step of imidization. Imidization.

As a method for manufacturing a polyimide film having three polyamidine layers by the second manufacturing method described above, for example, the following manufacturing method may be mentioned. This method includes the following steps: preparing a first polyimide precursor resin composition Of a polymer, a second polyimide precursor resin composition, and a third polyimide precursor resin composition, wherein the first polyimide precursor resin composition includes a polyimide precursor and an organic A solvent, the second polyimide precursor resin composition includes a polyimide precursor and an organic solvent, and the third polyimide precursor resin composition includes a polyimide precursor and an organic solvent; A step of applying the first polyimide precursor resin composition to a support to form a first polyimide precursor resin coating film; and applying the above onto the first polyimide precursor resin coating film A step of forming a second polyimide precursor resin composition to form a second polyimide precursor resin coating film; and coating the third polyimide precursor resin coating film on the second polyimide precursor resin coating film Amine precursor resin composition to form a third polyimide A step of coating a precursor resin; and heating the polyimide precursor contained in the first polyimide precursor resin composition and the second polyimide precursor resin composition contained in the heat The polyimide precursor and the third polyimide precursor resin composition contained in the polyimide precursor liminization step; and the first polyimide precursor resin composition and the first polyimide precursor resin composition The 3 polyfluorene imide precursor resin composition may have the same composition.

In the second manufacturing method, each polyimide precursor resin coating film formed so as to have a desired number of layers becomes a polyimide layer.

The said 2nd manufacturing method is preferable at the point which is easy to reduce the birefringence of a polyfluorene imide film. According to the second manufacturing method, a polyimide film having a birefringence in a thickness direction at a wavelength of 590 nm of 0.025 or less and more preferably 0.020 or less can be preferably formed.

In the second manufacturing method, a step of preparing a polyimide precursor resin composition, a step of applying a polyimide precursor resin composition to form a polyimide precursor resin coating film, and a step of converting a polyfluorene The polyimide precursor sulfonium imidization step contained in the imine precursor resin composition may be the same as the first production method.

In the above-mentioned second manufacturing method, in terms of improving the adhesion between layers and suppressing the generation of interference fringes, it is preferable to perform the above-mentioned fluorene imidization step after all the polyfluorene imide precursor resin coating films are formed. The reason is that the above mixed region can be formed at the boundary of the adjacent polyimide layers.

The support used in the second manufacturing method is not particularly limited as long as it is a material having a smooth surface and having heat resistance and solvent resistance. Examples include inorganic materials such as glass plates, and metal plates whose surfaces have been mirror-finished. The shape of the support is selected according to the coating method, and may be, for example, a plate shape, a roll shape or a belt shape, or a sheet shape that can be wound into a roll.

In addition, the second manufacturing method may include a laminated body of a polyimide precursor resin coating film before forming the polyimide precursor resin coating film and then a step of imidizing the fluorene imine, and the fluorene After the amination step, at least one of the laminated body of the coating film after the imidization is extended (hereinafter, referred to as an extension step).

In the case where the manufacturing method has an extending step, the fluorene imidization step may be performed on the polyfluorene imide precursor in the aforementioned polyfluorene imide precursor resin coating film before the extending step, and may also be performed on the polyfluorine imide before the extending step. The polyimide precursor in the polyimide precursor resin coating film may be performed on the polyimide precursor in the polyimide precursor resin coating film before the extending step and the polyimide precursor in the polyimide precursor resin coating film before the extending step. This is done with both polyimide precursors present in the film.

In the second manufacturing method, in the case where the stretching step is performed, it is more preferable to set the hydrazone imidization ratio of the polyfluorene imide precursor to the hydrazone imidization step before the stretching step. above 50. Since the ammonium imidization ratio is set to 50% or more before the elongation step, it can be used even if the elongation is performed after this step, and then heated at a higher temperature for a fixed time to perform the imidization. Suppress the appearance of the film or make it white. Especially in terms of improving the impact resistance of the polyfluorene imide film, it is preferable to set the hydrazone imidization rate to 80% or more in the hydrazone imidization step before the extension step, and it is preferable to make the reaction Progress to more than 90%, and then 100%. Since the fluorene is extended after imidization, the rigid polymer chains are easily aligned, so it is estimated that the surface hardness is improved and the impact resistance is improved.

In the case where there is an extension step in the second manufacturing method described above, in terms of improving the impact resistance of the polyfluorene imide film, it is preferable to extend the laminated body including the coating film after the fluorene imidization. step.

In the case where the second manufacturing method has an elongation step, when the initial size before the elongation is set to 100%, it is preferable to perform the elongation step of 101% or more and 10,000% or less while heating at 80 ° C or higher.

The heating temperature during stretching is preferably within the range of glass transition temperature of polyimide or polyimide precursor ± 50 ° C, and preferably within the range of glass transition temperature of ± 40 ° C. If the elongation temperature is too low, the film may not be deformed and alignment may not be sufficiently induced. On the other hand, if the stretching temperature is too high, the alignment obtained by stretching may relax due to temperature, and sufficient alignment may not be obtained.

The elongation step can be performed simultaneously with the fluorene imidization step. In terms of improving the impact resistance of the polyfluorene imide film, it is preferred that the fluorene imidization rate is 80% or more, further 90% or more, more preferably 95% or more, and in particular, substantially 100% fluorination has been performed. After amination, the coating film was stretched after imidization.

The stretching ratio of the polyfluoreneimide film is preferably 101% to 10,000%, and more preferably 101% to 500%. By extending within the above range, the impact resistance of the obtained polyimide film can be further improved.

The method for fixing the polyimide film during stretching is not particularly limited, and can be selected according to the type of the stretching device and the like. In addition, the stretching method is not particularly limited, and for example, the stretching device having a conveying device such as a tenter can be used to stretch through a heating furnace. The polyimide film can be stretched in only one direction (longitudinal or horizontal), or it can be simultaneously extended in both directions by biaxial stretching, sequential biaxial stretching, or diagonal stretching.

As a method for producing a polyimide film of the present invention, a production method including the following steps may be cited as a third production method: a step of preparing a polyimide molded article; preparing a polymer including polyimide and an organic solvent A step of forming a polyimide resin composition; and a step of applying a polyimide resin composition on at least one side of the polyimide formed article to form a polyimide resin coating film.

Moreover, as a manufacturing method of the polyfluorene imide film of this invention, the manufacturing method which includes the following steps is mentioned as a 4th manufacturing method: respectively preparing a 1st polyfluorene imide resin composition and a 2nd polyfluorene imide resin composition In the step, the first polyimide resin composition includes polyimide and an organic solvent, and the second polyimide resin composition includes polyimide and an organic solvent; and the first polyimide resin includes A step of applying the composition to a support to form a first polyimide resin coating film; and applying the second polyimide resin composition to the first polyimide resin coating film to form The second step of coating the polyimide resin.

In the third manufacturing method and the fourth manufacturing method, as a method for manufacturing a polyimide film having three or more polyimide layers, for example, the steps of forming a polyimide resin coating film up to The required number of layers.

The third manufacturing method and the fourth manufacturing method described above can be preferably used in a case where the polyimide used has a solvent solubility of 5 mass% or more when dissolved in an organic solvent at 25 ° C.

The third manufacturing method and the fourth manufacturing method described above are preferable in that the yellowness (YI value) of the polyimide film can be easily reduced, and the yellowness (calculated based on the above JIS K7373-2006) can be preferably formed ( Polyimide film having a value (YI value / film thickness (μm)) divided by a film thickness (μm) of 0.330 or less, more preferably 0.200 or less, and even more preferably 0.150 or less.

In the third manufacturing method, the step of preparing the polyfluorene imide body may be the same as the step of preparing the polyfluorene imine body in the first manufacturing method. Among them, in the third manufacturing method, in terms of the effect of lowering the yellowness (YI value) of the polyimide film, it is preferable to use the above-mentioned manufacturing method B as a polyimide molded article. The method can preferably form a value (YI value / film thickness (μm)) obtained by dividing the yellowness (YI value) calculated by the above JIS K7373-2006 by the film thickness (μm) of 0.030 or less, more preferably Polyimide film below 0.025. According to the fourth manufacturing method, a value (YI value / film thickness (μm)) obtained by dividing the yellowness (YI value) calculated by the above JIS K7373-2006 by the film thickness (μm) is preferably Polyimide film of 0.030 or less, more preferably 0.025 or less.

Examples of the support used in the fourth manufacturing method include the same as the support used in the second manufacturing method.

Hereinafter, the steps of preparing the polyimide resin composition (hereinafter, referred to as the polyimide resin composition preparation step) for the third manufacturing method and the fourth manufacturing method described above, and forming a polyimide resin coating film The procedure (hereinafter referred to as a polyimide resin coating film forming step) will be described in detail.

The polyimide used in the polyimide resin composition preparation step of the third manufacturing method and the fourth manufacturing method may be the same as the polyimide described in the polyimide layer described above. Among polyimide, polyimide having the above-mentioned solvent solubility is selected and used. As a method of amidine imidization, as for the dehydration ring-closure reaction of a polyammine precursor, it is preferable to use chemical amidine imidization, which is carried out using a chemical amidine agent instead of heat dehydration. In the case of chemical hydrazone imidization, known compounds such as amines such as pyridine or β-picolinic acid, carbodiimides such as dicyclohexylcarbodiimide, and acid anhydrides such as acetic anhydride can be used as dehydration catalysts. The acid anhydride is not limited to acetic anhydride, and examples include propionic anhydride, n-butyric anhydride, benzoic anhydride, and trifluoroacetic anhydride, and are not particularly limited. In this case, a tertiary amine such as pyridine or β-picolinic acid may be used in combination. Among them, if these amines remain in the film, the optical characteristics, especially the yellowness (YI value), are lowered. Therefore, it is preferable to separate the components other than polyimide by reprecipitation, etc. Instead of forming the film after removing 100 ppm or less of the total weight of the polyimide, instead of directly casting the reaction solution obtained by reacting the precursor to the polyimide, the film is formed.

In the step of preparing the polyimide resin composition of the third manufacturing method and the fourth manufacturing method, the organic solvent used as the reaction solution for chemically imidizing the polyimide precursor may be, for example, used. It is the same as that described in the preparation step of the polyfluorene imide precursor resin composition in the first manufacturing method. In the preparation step of the polyimide resin composition, as the organic solvent used when the polyimide refined by the reaction solution is redissolved, for example, ethylene glycol monoethyl ether and ethylene glycol monoethyl ether acetate may be mentioned. Esters, ethylene glycol mono-n-butyl ether, ethylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, o-dichlorobenzene, xylene, cresol, chlorobenzene, isobutyl acetate, isoamyl acetate, N-butyl acetate, n-propyl acetate, n-pentyl acetate, cyclohexanol, cyclohexanone, 1,4-bis Alkanes, tetrachloroethylene, toluene, methyl isobutyl ketone, methyl cyclohexanol, methyl cyclohexanone, methyl-n-butyl ketone, dichloromethane, dichloroethane, and mixed solvents thereof Among them, at least one selected from the group consisting of dichloromethane, n-butyl acetate, propylene glycol monomethyl ether acetate, and mixed solvents thereof can be preferably used.

The said polyfluorene imide resin composition contains an additive as needed. As the additive, the same ones as described in the above-mentioned polyfluorene imide precursor resin composition preparation step in the first manufacturing method can be used.

Moreover, in the said 3rd manufacturing method and the said 4th manufacturing method, as the method of making the water content of the said polyfluorene imide resin composition 1000 ppm or less, you may use the said polyfluorene imine which is the same as the said 1st manufacturing method. The method described in the preparation step of the precursor resin composition is the same.

In the polyimide resin film forming step of the third manufacturing method and the fourth manufacturing method, the coating method may be the same as that used in the polyimide precursor resin coating film forming step of the first manufacturing method. The explainer is the same.

In the polyimide resin coating film forming step of the third manufacturing method and the fourth manufacturing method, after applying the polyimide resin composition, the solvent is dried as necessary. The drying temperature is preferably 80 ° C or higher and 150 ° C or lower under normal pressure. It is preferable to set it as the range of 10 degreeC or more and 100 degreeC or less under reduced pressure. In the said 3rd manufacturing method and the said 4th manufacturing method, after drying a solvent at 150 degreeC or less, you may dry it more than 150 degreeC and 300 degreeC or less.

In addition, the fourth manufacturing method may further include an extending step of extending the laminate of the polyimide resin coating film after forming all the polyimide resin coating films. This extending step may be the same as the extending step of the second manufacturing method.

5. Uses of polyimide film

The application of the polyimide film of the present invention is not particularly limited, and it can be used as a base material or a surface material for thin glass plates and other conventional glass products. Since the polyimide film of the present invention has improved impact resistance and bending resistance, it can be particularly suitably used as a substrate or a surface material for a display capable of adapting to a curved surface.

Specifically, the polyimide film of the present invention can be preferably used, for example, in a thin and flexible organic EL display, a mobile terminal such as a smart phone or a watch terminal, or a display inside a car. Flexible panels for devices, watches, etc. The polyimide film of the present invention can also be applied to a member for an image display device such as a liquid crystal display device or an organic EL display device, a member for a touch panel, a flexible printed circuit board, a surface protective film, or a substrate material. Solar panel members, optical waveguide members, and semiconductor-related members.

II. Laminate

The laminated system of the present invention includes the laminated body of the polyimide film of the present invention and a hard coat layer, and the hard coat layer contains at least one polymer of a radical polymerizable compound and a cation polymerizable compound.

Since the laminated body of the present invention is a person using the polyimide film of the present invention, it is a person having improved impact resistance and bending resistance. Furthermore, since it has a hard coating layer, the surface hardness is improved, and the impact resistance is further improved. By.

Polyimide film

As the polyimide film used in the laminated body of the present invention, the above-mentioned polyimide film of the present invention can be used, and therefore description thereof is omitted here.

2. Hard coating

The hard coat layer used in the laminated body of the present invention contains at least one polymer of a radical polymerizable compound and a cation polymerizable compound.

(1) Radical polymerizable compound

The radical polymerizable compound is a compound having a radical polymerizable group. The radically polymerizable group possessed by the radically polymerizable compound is not particularly limited as long as it is a functional group capable of generating a radical polymerization reaction, and examples thereof include a group containing a carbon-carbon unsaturated double bond, and the like, specifically, Examples include vinyl and (meth) acrylfluorenyl. When the radical polymerizable compound has two or more radical polymerizable groups, the radical polymerizable groups may be the same or different.

As for the number of radically polymerizable groups which the said radically polymerizable compound has in one molecule, from the viewpoint of improving the hardness of the hard coat layer, it is preferably two or more, and more preferably three or more.

As the above-mentioned radically polymerizable compound, a compound having a (meth) acrylfluorenyl group is particularly preferred from the viewpoint of a high degree of reactivity, and further, in terms of adhesion, light transmittance, surface hardness, and impact resistance In terms of properties, a compound having two or more (meth) acrylfluorenyl groups in one molecule is preferred. For example, it can be preferably used for a compound called a polyfunctional acrylate monomer having 2 to 6 (meth) acrylfluorenyl groups in one molecule, or a (meth) acrylate, a polyester (meth) acrylate An oligomer having several (meth) acrylfluorenyl groups in a molecule called epoxy (meth) acrylate having a molecular weight of hundreds to thousands.

In addition, in this specification, a (meth) acryl group means each of an acryl group and a methacryl group, and a (meth) acrylate means each of an acrylate and a methacrylate .

Specific examples of the radically polymerizable compound include ethylene compounds such as divinylbenzene; ethylene glycol di (meth) acrylate, bisphenol A epoxy di (meth) acrylate, and 9,9 -Bis [4- (2- (meth) acryloxyethoxy) phenyl] fluorene, alkylene oxide modified bisphenol A di (meth) acrylate (for example, ethoxylated (ethylene oxide Modifications: bisphenol A di (meth) acrylate, etc.), trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, neopentaerythritol tri (methyl) Base) acrylate, neopentaerythritol tetra (meth) acrylate, dinepentaerythritol tri (meth) acrylate, dinepentaerythritol tetra (meth) acrylate, dinepentaerythritol penta ( Polyacrylic acid polyacrylates such as meth) acrylates, dipentaerythritol hexa (meth) acrylates, diacrylates of bisphenol A diglycidyl ether, diacrylates of hexanediol diglycidyl ether, etc. Epoxy acrylates, amine acrylates, etc. obtained by reacting polyisocyanates with hydroxy acrylates such as hydroxyethyl acrylate.

(2) Cationic polymerizable compound

The cationically polymerizable compound is a compound having a cationically polymerizable group. The cationically polymerizable group which the cationically polymerizable compound has is not particularly limited as long as it is a functional group capable of causing a cation polymerization reaction, and examples thereof include an epoxy group, an oxetanyl group, and a vinyl ether group. When the cationically polymerizable compound has two or more cationically polymerizable groups, the cationically polymerizable groups may be the same or different.

The number of cationically polymerizable groups that the cationically polymerizable compound has in one molecule is preferably two or more, and more preferably three or more, in terms of increasing the hardness of the hard coat layer.

In addition, as the cationically polymerizable compound, a compound having at least one of an epoxy group and an oxetanyl group as a cationically polymerizable group is particularly preferable in terms of adhesion, light transmittance, surface hardness, and impact resistance. In terms of properties, a compound having at least one of two or more epoxy groups and oxetanyl groups in one molecule is more preferable. Cyclic ether groups such as an epoxy group and an oxetanyl group are preferred in that the shrinkage accompanying polymerization reaction is small. In addition, a compound having an epoxy group in a cyclic ether group has the following advantages: it is easy to obtain compounds of various structures, does not adversely affect the durability of the obtained hard coat layer, and is also easy to control and free radicals Compatibility of polymerizable compounds. In addition, the oxetanyl group in the cyclic ether group has the following advantages: compared with the epoxy group, the degree of polymerization is higher, and the toxicity is low; when the obtained hard coat layer is combined with a compound having an epoxy group, Accelerate the formation rate of the network obtained from the cationically polymerizable compound in the coating film. In the area where it is mixed with the radically polymerizable compound, it will also form an independent network without leaving unreacted monomers in the film. Internet, etc.

Examples of the cationically polymerizable compound having an epoxy group include hydrogen peroxide, a polyglycidyl ether of a polyalcohol having an alicyclic ring, or a compound containing a cyclohexene ring and a cyclopentene ring. Alicyclic epoxy resin obtained by epoxidation with a suitable oxidant such as peracid; aliphatic polyhydric alcohol, polyglycidyl ether of an alkylene oxide adduct thereof, polyglycidyl ester of aliphatic long chain polyacid, ( Aliphatic epoxy resins such as homopolymers and copolymers of glycidyl methacrylate; by bisphenols such as bisphenol A, bisphenol F or hydrogenated bisphenol A, or alkylene oxide adducts thereof Glycidyl ethers produced by the reaction of derivatives such as caprolactone adducts with epichlorohydrin, and glycidyl ether epoxy resins derived from bisphenols, such as novolac epoxy resins.

Examples of the alicyclic epoxy resin include 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (UVR-6105, UVR-6107, UVR-6110), and bis- 3,4-epoxycyclohexylmethyl adipate (UVR-6128) (above, the trade name in parentheses, manufactured by Dow Chemical).

Examples of the glycidyl ether type epoxy resin include sorbitol polyglycidyl ether (DENACOL EX-611, DENACOL EX-612, DENACOL EX-614, DENACOL EX-614B, DENACOL EX-622), and polyglycerol. Polyglycidyl ether (DENACOL EX-512, DENACOL EX-521), neopentyl tetraglycidyl ether (DENACOL EX-411), diglycerol polyglycidyl ether (DENACOL EX-421), glycerin polyglycidyl ether ( DENACOL EX-313, DENACOL EX-314), trimethylolpropane polyglycidyl ether (DENACOL EX-321), resorcinol diglycidyl ether (DENACOL EX-201), neopentyl glycol diglycidyl ether (DENACOL EX-211), 1,6 hexanediol diglycidyl ether (DENACOL EX-212), hydrogen bisphenol A diglycidyl ether (DENACOL EX-252), ethylene glycol diglycidyl ether (DENACOL EX -810, DENACOL EX-811), polyethylene glycol diglycidyl ether (DENACOL EX-850, DENACOL EX-851, DENACOL EX-821), propylene glycol glycidyl ether (DENACOL EX-911), polypropylene glycol glycidyl ether (DENACOL EX-941, DENACOL EX-920), allyl glycidyl ether (DENACOL EX-111), 2-ethylhexyl glycidyl ether (DENACOL EX-121), phenyl glycidyl Glycidyl ether (DENACOL EX-141), phenol glycidyl ether (DENACOL EX-145), butylphenyl glycidyl ether (DENACOL EX-146), diglycidyl phthalate (DENACOL EX-721), Hydroquinone diglycidyl ether (DENACOL EX-203), diglycidyl terephthalate (DENACOL EX-711), glycidyl phthalimide (DENACOL EX-731), dibromobenzene Glycidyl ether (DENACOL EX-147), dibromo neopentyl glycol diglycidyl ether (DENACOL EX-221) (above, the trade names in parentheses are manufactured by Nagase chemteX).

In addition, as other commercially available epoxy resins, trade names are Epikote 825, Epikote 827, Epikote 828, Epikote 828EL, Epikote 828XA, Epikote 834, Epikote 801, Epikote 801P, Epikote 802, Epikote 815, Epikote 815XA Epikote 816A, Epikote 819, Epikote 834X90, Epikote 1001B80, Epikote 1001X70, Epikote 1001X75, Epikote 1001T75, Epikote 806, Epikote 806P, Epikote 8000, Epikote 154, Epikote 154, Epikote , Epikote YX8034, etc. (the above are trade names, manufactured by Japan Epoxy Resins).

Examples of the cationically polymerizable compound having an oxetanyl group include 3-ethyl-3-hydroxymethyloxetane (OXT-101) and 1,4-bis-3-ethyloxane Cyclobutane-3-ylmethoxymethylbenzene (OXT-121), bis-1-ethyl-3-oxetanyl methyl ether (OXT-221), 3-ethyl-3-2-ethyl Hexyloxymethyloxetane (OXT-212), 3-ethyl-3-phenoxymethyloxetane (OXT-211) (above, the name in brackets is East Asia) Synthetic manufacturing), or trade names ETERNACOLL EHO, ETERNACOLL OXBP, ETERNACOLL OXTP, ETERNACOLL OXMA (the above are the trade names, manufactured by Ube Industries).

(3) Polymerization initiator

At least one polymer of the above-mentioned radical polymerizable compound and the cationically polymerizable compound contained in the hard coat layer used in the present invention can be obtained, for example, by using the above-mentioned radically polymerizable compound and the above-mentioned cationically polymerizable compound. A polymerization initiator is added to at least one type of intermediate as needed, and a polymerization reaction is performed by a known method.

As said polymerization initiator, a radical polymerization initiator, a cationic polymerization initiator, a radical, a cationic polymerization initiator, etc. can be selected suitably and used. These polymerization initiators undergo radical decomposition or cationic polymerization by decomposing at least one of light irradiation and heating to generate radicals or cations.

The radical polymerization initiator may release a substance that initiates radical polymerization by at least one of light irradiation and heating. Examples of the photoradical polymerization initiator include imidazole derivatives, bisimidazole derivatives, N-aryl glycine derivatives, organic azide compounds, titanocene, aluminate complexes, Organic peroxide, N-alkoxypyridinium salt, 9-oxosulfur Derivatives and the like, more specifically, 1,3-bis (third butyldioxycarbonyl) benzophenone, 3,3 ', 4,4'-tetrakis (third butyldioxycarbonyl) Benzophenone, 3-phenyl-5-iso Azolinone, 2-mercaptobenzimidazole, bis (2,4,5-triphenyl) imidazole, 2,2-dimethoxy-1,2-diphenylethane-1-one (trade name Irgacure 651, manufactured by Ciba Japan (stock), 1-hydroxy-cyclohexyl-phenyl-one (trade name Irgacure 184, manufactured by Ciba Japan (stock)), 2-benzyl-2-dimethylamino-1- (4- Phenylphenyl) -butane-1-one (trade name Irgacure 369, manufactured by Ciba Japan), bis (η5-2,4-cyclopentadien-1-yl) -bis (2,6- Difluoro-3- (1H-pyrrole-1-yl) -phenyl) titanium) (trade name: Irgacure 784, manufactured by Ciba Japan Co., Ltd.) and the like are not limited thereto.

In addition to the above, commercially available products can also be used. Specific examples include: Irgacure 907, Irgacure 379, Irgacure 819, Irgacure 127, Irgacure 500, Irgacure 754, Irgacure 250, Irgacure 1800, Irgacure manufactured by Ciba Japan. 1870, Irgacure OXE01, DAROCUR TPO, DAROCUR1173, SpeedcureMBB, SpeedcurePBZ, SpeedcureITX, SpeedcureCTX, SpeedcureEDB, Esacure ONE, Esacure KIP150, Esacure KTO46, and Nippon Kayaku Yakuyakury (made by Nihon SiberHegner) , KAYACURE BMS, KAYACURE DMBI, etc.

The cationic polymerization initiator may release a substance that initiates cationic polymerization by at least one of light irradiation and heating. Examples of the cationic polymerization initiator include sulfonate, sulfonium imine sulfonate, dialkyl-4-hydroxysulfonium salt, p-nitrobenzyl arylsulfonate, silanol-aluminum complex, ( η ⁶ -benzene) (η ⁵ -cyclopentadiene) iron (II) and the like, more specifically, benzoin tosylate, 2,5-dinitrobenzyl tosylate, and N-toluenesulfonic acid Fluorenimide phthalimide and the like are not limited thereto.

Examples of the polymer which can be used as a radical polymerization initiator or a cationic polymerization initiator include aromatic sulfonium salts, aromatic sulfonium salts, aromatic diazonium salts, aromatic sulfonium salts, and Compounds, iron aromatic hydrocarbon complexes, and the like, more specifically, diphenylfluorene, bis (tolyl) fluorene, bis (p-thirdbutylphenyl) fluorene, bis (p-chlorophenyl) fluorene, etc Phosphonium salts such as chloride, bromide, fluoroborate, hexafluorophosphate, hexafluoroantimonate, triphenylphosphonium, 4-tert-butyltriphenylphosphonium, tris (4-methylphenyl) Samarium and other samarium chlorides, bromides, fluoroborate, hexafluorophosphate, and hexafluoroantimonate, and other ammonium salts, , 2-phenyl-4,6-bis (trichloromethyl) -1,3,5-tri , 2-methyl-4,6-bis (trichloromethyl) -1,3,5-tri Etc. 2,4,6- substituted for -1,3,5 three Compounds and the like are not limited thereto.

(4) Additives

The hard coat layer used in the present invention may contain an antistatic agent, an anti-glare agent, an anti-fouling agent, inorganic or organic fine particles for improving the hardness, a leveling agent, various sensitizers, etc. in addition to the above-mentioned polymers, if necessary additive.

3.Composition of laminated body

The laminated body of the present invention is not particularly limited as long as it has the polyimide film and the hard coat layer, and may be one having the hard coat layer laminated on one side of the polyimide film, or The two areas of the polyimide film have the above-mentioned hard coat layer. In addition, the laminated body of the present invention may have, in addition to the polyimide film and the hard coat layer, a range in which the effects of the present invention are not impaired. Other layers such as improved primer coatings. The laminated body of the present invention may be one in which the polyimide film is provided adjacent to the hard coat layer.

The Young's modulus of the two polyimide layers located on the outermost surface of the polyimide film used in the laminate of the present invention is different from each other, and the above-mentioned hard coat layer is provided on one area of the polyimide film. In the case of a laminated body, in terms of improving impact resistance, it is preferable that the hard coat layer is located on the polyimide layer side having a relatively large Young's modulus among the two polyimide layers.

The overall thickness of the laminated body of the present invention may be appropriately selected depending on the application. In terms of strength and impact resistance, it is preferably 10 μm or more, and more preferably 40 μm or more. On the other hand, in terms of bending resistance, it is preferably 300 μm or less, and more preferably 250 μm or less.

In the laminated body of the present invention, the thickness of each hard coat layer is preferably 2 μm or more and 80 μm or less, and more preferably 3 μm or more and 50 μm or less.

4. Characteristics of laminated body

The laminated body of the present invention preferably has a pencil hardness of HB or higher, more preferably F or higher, even more preferably H or higher, and even more preferably 2H or higher.

The pencil hardness of the laminated body of the present invention can be measured in the same manner except that the load is set to 9.8 N in the method for measuring pencil hardness of the polyimide film described above.

The total light transmittance of the laminated body of the present invention measured in accordance with JIS K7361-1 is preferably 85% or more, further preferably 88% or more, and even more preferably 90% or more. Since the transmittance is so high, the transparency becomes good and it can be used as a glass substitute.

The total light transmittance of the laminated body of the present invention can be measured in the same manner as the total light transmittance of the polyimide film measured according to JIS K7361-1.

The yellowness (YI value) calculated according to the above JIS K7373-2006 of the laminated body of the present invention is preferably 30 or less, more preferably 20 or less, and even more preferably 16 or less.

The said yellowness (YI value) of the laminated body of this invention can be measured similarly to the said yellowness (YI value) calculated based on the said JISK7373-2006 of the said polyimide film.

The haze value of the laminated body of the present invention is preferably 10 or less, more preferably 8 or less, and even more preferably 5 or less in terms of light transmittance.

The haze value of the laminated body of the present invention can be measured in the same manner as the haze value of the polyfluorene film.

The birefringence of the multilayer body of the present invention in the thickness direction at a wavelength of 590 nm is preferably 0.040 or less, more preferably 0.025 or less, even more preferably 0.020 or less, and even more preferably 0.015 or less.

The birefringence of the multilayer body of the present invention can be measured in the same manner as the birefringence in the thickness direction of the polyimide film at a wavelength of 590 nm.

5. Uses of laminates

The application of the laminated body of the present invention is not particularly limited, and for example, it can be used for the same application as that of the polyimide film of the present invention described above.

6. Manufacturing method of laminated body

As a method for producing the laminated body of the present invention, for example, a production method including the steps of forming at least one type containing a radically polymerizable compound and a cationically polymerizable compound on at least one side of the polyimide film of the present invention is mentioned. A step of coating the composition for forming a hard coat layer; and a step of hardening the coating film.

The said composition for hard-coat layer formation contains at least 1 type of a radically polymerizable compound and a cationically polymerizable compound, and may further contain a polymerization initiator, a solvent, an additive, etc. as needed.

Here, the radical polymerizable compound, cation polymerizable compound, polymerization initiator, and additive contained in the composition for forming a hard coat layer may be the same as those described in the hard coat layer, and the solvent may be freely used. A known solvent is appropriately selected and used.

As a method of forming the coating film of the composition for forming a hard coat layer on at least one side of a polyimide film, for example, the hard coat layer may be applied to at least one side of the polyimide film by a known coating method. Method for forming a composition.

The coating means is not particularly limited as long as it is a method capable of coating at a target film thickness, and examples thereof include the same as the above-mentioned means for coating a polyimide precursor resin composition on a support.

The coating amount of the hardening resin composition for the hard coat layer varies depending on the properties required of the obtained laminate, and it is preferably adjusted so that the film thickness after drying becomes 3 μm or more and 25 μm or less. The coating amount is preferably within a range of 3 g / m ² or more and 30 g / m ² or less, particularly within a range of 5 g / m ² or more and 25 g / m ² or less.

Regarding the coating film of the curable resin composition for a hard-coat layer, the solvent is removed by drying if necessary. Examples of the drying method include a method of drying under reduced pressure or heating, and a combination of these. When drying is performed under normal pressure, drying is preferably performed at 30 ° C or higher and 110 ° C or lower.

The coating film of the above-mentioned hardening resin composition for hard-coating can be applied and dried if necessary. Based on the polymerizable groups of the radical polymerizable compound and the cation polymerizable compound contained in the hardening resin composition, The coating film is hardened by at least one of light irradiation and heating, and a hard coat layer is formed on at least one side of the polyimide film. The hard coat layer contains at least one of a radical polymerizable compound and a cation polymerizable compound. Kind of polymer.

In light irradiation, ultraviolet rays, visible light, electron beams, and free radiation are mainly used. In the case of ultraviolet curing, ultraviolet rays emitted from light sources such as ultra-high-pressure mercury lamps, high-pressure mercury lamps, low-pressure mercury lamps, carbon arcs, xenon arcs, and metal halide lamps are used. The irradiation amount of the energy ray source is about 50 to 5000 mJ / cm ² based on the cumulative exposure amount at the ultraviolet wavelength of 365 nm.

In the case of heating, the treatment is usually performed at a temperature of 40 ° C or higher and 120 ° C or lower. The reaction can also be carried out by leaving it to stand at room temperature (25 ° C) for more than 24 hours.

III. Surface material for display

The surface material for a display of the present invention is the polyimide film of the present invention described above or the laminated body of the present invention described above.

The surface material for a display of the present invention is used by being disposed on the surface of various displays. The surface material for the display of the present invention is the same as the polyimide film of the present invention and the laminated body of the present invention, and is improved in impact resistance and bending resistance. Therefore, it can be used as a flexible display.

The surface material for a display of the present invention can be used for various known displays, and is not particularly limited. For example, it can be used for the display described in the application of the polyimide film of the present invention.

Furthermore, in the case where the surface material of the display of the present invention is the laminated body of the present invention described above, the surface that becomes the outermost surface after the surface of the display may be the surface of the polyimide film side or may be hard-coated Layer-side surface. Among these, in terms of impact resistance and bending resistance, it is preferable to arrange the surface material for a display of the present invention such that the surface on the hard coat layer side becomes the surface on the positive side. When the surface material of the display of the present invention is the polyimide film of the present invention and the Young's modulus of the two polyimide layers on the outermost surface of the polyimide film are different from each other, In terms of impact resistance and bending resistance, the surface material for a display of the present invention is preferably arranged such that the surface on the polyimide layer side with a relatively large Young's modulus becomes the surface on the more positive side. The surface material for a display of the present invention may be one having an anti-fingerprint adhesion layer on the outermost surface.

The method of disposing the surface material for a display of the present invention on the surface of a display is not particularly limited, and examples thereof include a method of passing through an adhesive layer. As the said adhesive layer, the conventionally well-known adhesive layer which can be used for the adhesive of the surface material for displays can be used.

Examples

[Evaluation method]

Hereinafter, unless otherwise stated, measurement or evaluation is performed at 25 ° C.

<Weight average molecular weight of polyimide precursor>

The weight average molecular weight of the polyimide precursor is obtained by making the polyimide precursor into a 0.5% by weight N-methylpyrrolidone (NMP) solution and passing the solution through a syringe filter (pore size: (0.45 μm), filtered, using a 10 mmol% LiBr-NMP solution with a water content of 500 ppm or less as a developing solvent, using a GPC device (manufactured by Tosoh; HLC-8120; using a column: GPC LF-804 by SHODEX). The measurement was performed under conditions of 50 μL, a solvent flow rate of 0.5 mL / min, and 40 ° C. The weight average molecular weight of the polyimide precursor is determined based on a polystyrene standard sample (weight average molecular weight: 364,700, 204,000, 103,500, 44,360, 27,500, 13,030, 6,300, 3,070) of the same concentration as the sample. Conversion value for standard polystyrene. The dissolution time was compared with a calibration curve to determine a weight average molecular weight.

<Viscosity of Polyimide Precursor Solution>

The viscosity of the polyimide precursor solution was measured using a viscometer (for example, TVE-22HT, Toki Sangyo Co., Ltd.) at a sample volume of 0.8 ml at 25 ° C.

<Polyimide weight average molecular weight>

15 mg of polyimide powder was immersed in 15000 mg of N-methylpyrrolidone (NMP), and was heated to 60 ° C in a water bath while being stirred at 200 rpm with a stirrer for 3 to 60 hours until visually confirmed dissolution. Thus, an NMP solution having a concentration of 0.1% by weight was obtained. This solution was filtered through a syringe filter (pore diameter: 0.45 μm), and a 30 mmol% LiBr-NMP solution having a water content of 500 ppm or less was used as a developing solvent, using a GPC device (manufactured by Tosoh; HLC-8120; detector: differential refractive index) (RID) detector; using a column: 2 GPC LF-804 manufactured by SHODEX are connected in series) under the conditions of sample injection volume of 50 μL, solvent flow rate of 0.4 mL / min, column temperature of 37 ° C, and detector temperature of 37 ° C Perform the measurement. The weight average molecular weight of polyimide is a standard polybenzene measured based on a polystyrene standard sample (weight average molecular weight: 364,700, 204,000, 103,500, 44,360, 27,500, 13,030, 6,300, 3,070) of the same concentration as the sample. Conversion value for ethylene. The dissolution time was compared with a calibration curve to determine a weight average molecular weight.

<Viscosity of Polyimide Solution>

The viscosity of the polyimide solution was measured using a viscometer (for example, TVE-22HT, Toki Sangyo Co., Ltd.) at a sample volume of 0.8 ml at 25 ° C.

<Film thickness>

The film thickness of each polyimide layer included in the polyimide film of each example, and the film thickness of the single-layer polyimide film of each comparative example are based on a polyimide cut into a size of 10 cm × 10 cm. The cross section of the test piece obtained by cutting the film in the thickness direction was observed with a scanning electron microscope (SEM), and each polyimide layer was positioned at 5 points at equal intervals from both ends in the width direction of the polyimide film. The film thickness was measured and the average value was set.

Regarding the polyimide films of Examples 7 to 12, because the polyimide layer has a mixed region in which the materials of each polyimide layer are mixed at the boundary of the adjacent polyimide layers, the thickness of the polyimide film is reduced. The cross-section of the test piece obtained by cutting in the direction was performed using a time-of-flight secondary ion mass spectrometer (manufactured by ION-TOF, model TOF.SIMS5). Mapping, taking the part where the detected amount of silicon atoms becomes the average value of the detected amount of silicon atoms in two regions of the non-mixed region as the boundary between the polyimide layers, and measuring the film thickness of each polyimide layer. In addition, when a portion having a thickness is a portion having an average value of the detected amount of silicon atoms in the two non-mixed regions, the central portion in the thickness direction of the region is used as the boundary between the polyimide layers. The film thickness of each polyimide layer was measured.

<Young's modulus>

The cross-section of the test piece obtained by cutting the polyimide film in the thickness direction was measured at a temperature of 25 ° C. using the nanoindentation method in accordance with ISO14577. Specifically, a PICODENTOR HM500 manufactured by Fischer Instruments was used as the measurement device, and a Vickers indenter was used as the measurement indenter. For each layer of the cross section of the test piece, 8 arbitrary points were measured and number averaged, and the obtained value was set as the Young's modulus of each layer. In addition, the measurement conditions were set as follows: the maximum indentation depth: 1000 nm; the load time: 20 seconds; and the creep time: 5 seconds.

<Linear Thermal Expansion Coefficient (CTE)>

For a test piece obtained by cutting a single layer of polyimide film into 5mm × 15mm, the elongation of the test piece was measured by a thermomechanical analysis device (TMA) under the following conditions, and the temperature at 50 ° C to 250 ° C was calculated. Linear thermal expansion coefficient (CTE) of the range.

<CTE measurement conditions>

Model name: TMA-60, manufactured by Shimadzu Corporation

Ambient gas: nitrogen

Gas flow: 50ml / min

Initial load: 9g

[Temperature control program]

The temperature was maintained at 30 ° C for 10 minutes under a nitrogen atmosphere, and thereafter, the temperature was increased to 400 ° C at a heating rate of 10 ° C / min, and the temperature was maintained at 400 ° C for 1 minute.

<Tensile elastic modulus>

The test piece obtained by cutting a polyimide film into 15 mm × 40 mm was subjected to humidity control at a temperature of 25 ° C. and a relative humidity of 60% for 2 hours. Thereafter, the stretching speed was set to 8 mm / min in accordance with JIS K7127. The distance between the chucks was set to 20 mm, and the tensile elastic modulus at 25 ° C was measured. A tensile testing machine was used (manufactured by Shimadzu Corporation: Autograph AG-X 1N; load cell: SBL-1KN).

<Total light transmittance>

According to JIS K7361-1, the measurement was performed with a haze meter (HM150 manufactured by Murakami Color Technology Research Institute).

<Haze value>

The measurement was performed with a haze meter (HM150 manufactured by Murakami Color Technology Research Institute) in accordance with JIS K-7105.

<YI value (yellowness)>

The YI value is based on JIS K7373-2006, using an ultraviolet-visible near-infrared spectrophotometer (Japanese spectrophotometer (stock) V-7100), using a spectrophotometric method, using an auxiliary luminous body C, a 2-degree field of view of 250 nm to 800 nm The range was performed at intervals of 1 nm, and based on the obtained transmittance, three stimulus values X, Y, and Z in the XYZ color system were obtained, and the values of X, Y, and Z were calculated by the following formula.

YI = 100 (1.2769X-1.0592Z) / Y

Furthermore, the value (YI / film thickness (μm)) of the YI value divided by the overall film thickness (μm) of the polyimide film was determined.

<Birefringence>

The retardation value (Rth) of the polyimide film in the thickness direction was measured using a retardation measuring device (manufactured by Oji Measurement Co., Ltd., product name "KOBRA-WR") at 23 ° C using light having a wavelength of 590 nm. The thickness direction retardation value (Rth) is a phase difference value at a 0-degree incidence and a phase difference value at an oblique 40-degree incidence, and the thickness direction retardation value Rth is calculated based on the retardation values. The above-mentioned retardation value at an angle of 40 degrees is measured by making light having a wavelength of 590 nm incident on the retardation film from a direction inclined from the normal of the retardation film by 40 degrees.

The birefringence of the polyfluorene imide film is obtained by substituting the formula: Rth / d (film thickness (nm) of the polyfluorene imide film).

<Static bending test>

Hereinafter, a method of the static bending test will be described with reference to FIG. 3.

A test piece 10 cut into a 15mm × 40mm polyimide film is bent at a half of the long side, and a metal piece 2 with a thickness of 6mm is sandwiched from the upper and lower sides of the long side of the test piece 10 (100mm × 30mm × 6mm), and the two end portions of the test piece 10 and the overlapping portions of the upper and lower surfaces of the metal piece 2 are each 10mm fixed with tape, and in this state, a glass plate is used. (100mm × 100mm × 0.7mm) 3a and 3b are clamped from above and below, and the test piece 10 is fixed in a state of being bent with an inner diameter of 6mm. At this time, dummy test pieces 4a, 4b are inserted between the metal sheet 2 and the glass plates 3a, 3b without the test piece 10, and fixed with tape so that the glass plates 3a, 3b become parallel. The test piece 10 fixed in a bent state in this manner was left to stand in an environment of 60 ° C and 90% relative humidity (RH) for 24 hours. Thereafter, the glass plate and the fixing tape were removed, and the test was released. The force exerted by the sheet 10. Thereafter, one end of the test piece 10 was fixed, and the inner angle of the test piece 30 minutes after the release of the force applied to the test piece 10 was measured.

In addition, the polyimide film of Example 11 was bent so that the polyimide layer having a relatively large Young's modulus became the inner side.

When the film is completely restored to its original state without being affected by the static bending test, the above-mentioned internal angle becomes 180 °.

<Pencil hardness>

The pencil hardness of the polyimide film can be performed as follows: The humidity of the measurement sample is controlled at a temperature of 25 ° C and a relative humidity of 60% for 2 hours, and thereafter, the test specified by JIS-S-6006 is used. For pencils, use a pencil scratch coating film hardness tester manufactured by Toyo Seiki Co., Ltd. to perform a pencil hardness test (0.98N load) specified in JIS K5600-5-4 (1999) on the film surface. Pencil hardness. In addition, the polyimide film of Example 11 was subjected to a pencil hardness test on the surface of a polyimide layer having a relatively large Young's modulus.

<Impact resistance>

Hereinafter, a method for evaluating impact resistance will be described with reference to FIG. 4.

Ten aluminum foils 6 with a thickness of 100 μm were laminated on the iron substrate 5, and a test piece 10 cut into a 15 mm × 40 mm polyimide film was placed thereon. Set the ballpoint pen 7 (manufactured by BiC, 0.7mm) to a height (distance between the test piece 10 and the front end of the ballpoint pen) of 90mm, drop the ballpoint pen 7 on the top surface of the test piece 10, and face the aluminum foil 6 formed by the front end of the ballpoint pen 7. The depth of the pit was evaluated by measuring it with an optical microscope (focus depth). The depths of the pits are shown in Tables 2 and 4. The smaller the pit depth, the better the impact resistance. In addition, the polyimide film of Example 11 evaluated the impact resistance using the surface of the polyimide layer having a relatively large Young's modulus as the upper surface.

(Synthesis example 1)

In a 5L separable flask, 3081 g of dehydrated dimethylacetamide and 322 g (1.00 mol) of 2,2'-bis (trifluoromethyl) benzidine (TFMB) were added, and a solution in which TFMB was dissolved The liquid temperature was controlled to 30 ° C, and 443 g (1.00 mol) of 4,4 '-(hexafluoroisopropylidene) bisphthalic anhydride (6FDA) was slowly and dividedly divided into several times so that the temperature rose to below 2 ° C. In addition, a polyimide precursor solution 1 (solid content 20% by weight) in which the polyimide precursor 1 is dissolved is synthesized. The viscosity of polyimide precursor solution 1 (solid content 20% by weight) at 25 ° C was 34920 cps. The weight average molecular weight of polyimide precursor 1 measured by GPC was 408500.

(Synthesis examples 2 to 3)

The reaction was carried out in the order of the above Synthesis Example 1 so as to have the raw material and solid component concentrations shown in Table 1 to prepare polyimide precursor solutions 2 to 3.

(Synthesis example 4)

A 5L separable flask was charged with dehydrated dimethylacetamide (2265g) and 1,3-bis (3-aminopropyl) tetramethyldisilazane (AprTMOS) (24.9 g) solution, control the liquid temperature to 30 ° C, and slowly add 4,4 '-(hexafluoroisopropylidene) bisphthalic anhydride (6FDA) (22.2g) so that the temperature rises to 2 ° C or lower ) And stir for 30 minutes with a mechanical stirrer. To this was added 2,2'-bis (trifluoromethyl) benzidine (TFMB) (288g), and after confirming the complete dissolution, 4,4 '-(six) was slowly added in several portions so that the temperature rose to 2 ° C or lower. Fluoroisopropylidene) bisphthalic anhydride (6FDA) (420g), and a polyfluorene imide precursor solution 4 (solid content: 25% by mass) in which the polyfluorene imine precursor 4 was dissolved was synthesized. Furthermore, in the polyimide precursor solution 4, the molar ratio of TFMB to AprTMOS (TFMB: AprTMOS) was 90:10, and the total molar of TFMB and AprTMOS was set to be the same as that of TFMB in Synthesis Example 1. .

In the following, the abbreviations in the tables are as follows.

TFMB: 2,2'-bis (trifluoromethyl) benzidine

BAPS: bis [4- (4-aminophenoxy) phenyl] fluorene

AprTMOS: 1,3-bis (3-aminopropyl) tetramethyldisilazane

6FDA: 4,4 '-(hexafluoroisopropylidene) bisphthalic anhydride

PMDA: pyromellitic dianhydride

(Example 1)

As the polyimide shaped body A, a single-layer polyimide film having a film thickness of 50 μm, which was obtained by using the polyimide precursor solution 1 in the order of (1) to (3), was prepared.

(1) The polyfluorene imide precursor solution 1 was coated on a glass plate and dried in a circulating oven at 120 ° C. for 10 minutes.

(2) The temperature was increased to 350 ° C. at a temperature increase rate of 10 ° C./min under a nitrogen gas flow (oxygen concentration of 100 ppm or less), and the temperature was maintained at room temperature for 1 hour.

(3) Peeling from a glass plate and obtaining a polyimide film.

The polyimide precursor solution 2 was coated on the front and back surfaces of the polyimide formed article A so that the film thickness after the imidization became 3 μm, respectively, and dried in a 120 ° C circulating oven for 10 minutes. The polyimide precursor resin coating film was then heated to 350 ° C at a temperature increase rate of 10 ° C / min under a nitrogen gas flow (oxygen concentration of 100 ppm or less), held for 1 hour, and then cooled to room temperature. The polyimide precursor was then cooled to room temperature. The amidine is imidized to obtain the polyammine film of Example 1. The obtained polyimide film is a polymer having a relatively small Young's modulus layer (hereinafter, referred to as a low Young's modulus layer) having a relatively large Young's modulus, A multilayer polyimide film composed of a layer of a fluorene imine layer (hereinafter referred to as a high Young's modulus layer).

(Examples 2 and 3)

In Example 1, except that the thickness of the high Young's modulus layer was set as shown in Table 2, the polyimide films of Examples 2 and 3 were obtained in the same manner as in Example 1.

(Examples 4 to 6)

In Example 1, the polyimide formed body B, which is a single-layer polyimide film having a film thickness of 80 μm, which is prepared by changing the coating amount of the polyimide precursor solution 1, is used instead of the polyimide formed body A. And setting the thickness of the high Young's modulus layer as in Table 2, except that the polyfluorene imine films of Examples 4 to 6 were obtained in the same manner as in Example 1.

(Example 7)

A polyimide precursor solution 4 was used instead of the polyimide precursor solution 1 in the production of the polyimide precursor A of Example 1. A single layer having a film thickness of 51 μm was obtained in the same manner. A polyimide film was used as the polyimide molded body C. In the production of the polyimide film of Example 1, a polyimide formed body C was used instead of the polyimide formed body A, and the polyfluorene of Example 7 was obtained in the same manner as in Example 1. Imine film.

(Comparative example 1)

A single-layer polyimide film having a thickness of 48 μm, which was obtained using the polyimide precursor solution 1 in the same order as in (1) to (3) of Example 1, was used as the polyimide of Comparative Example 1. Amine film.

(Comparative example 2)

A single-layer polyimide film having a film thickness of 49 μm obtained using the polyimide precursor solution 2 in the same order as in (1) to (3) of Example 1 was used as the polyimide of Comparative Example 2. Amine film.

(Comparative example 3)

A single-layer polyimide film having a film thickness of 49 μm, which was obtained using the polyimide precursor solution 3 in the same order as in (1) to (3) of Example 1, was used as the polyimide of Comparative Example 3. Amine film.

(Comparative Example 4)

A single-layer polyimide film having a film thickness of 52 μm, which was obtained using the polyimide precursor solution 4 in the same order as in (1) to (3) of Example 1, was used as the polyimide of Comparative Example 4. Amine film.

(Comparative example 5)

A single-layer polyimide film having a film thickness of 80 μm obtained using the polyimide precursor solution 1 in the same order as in (1) to (3) of Example 1 was used as the polyimide of Comparative Example 5. Amine film.

The polyimide films of Examples 1 to 7 and Comparative Examples 1 to 5 were evaluated using the above-mentioned evaluation methods. The evaluation results are shown in Table 2.

In addition, in the layer configurations shown in Tables 2 and 4, the "high" means a high Young's modulus layer, and the "low" means a low Young's modulus layer. In addition, the film thickness, Young's modulus, and linear thermal expansion coefficient (CTE) shown in Tables 2 and 4 are the measurement results of each polyimide layer, and the other evaluation results indicate the evaluation of the entire polyimide film. result. The polyimide types Nos. 1 to 6 in Tables 2 and 4 correspond to the polyimide obtained using the polyimide precursor solution or the polyimide solution 1 to 6, respectively. The Young's modulus ratio (high / low) in Tables 2 and 4 is the value of the Young's modulus of the polyimide layer with the highest Young's modulus divided by the Yang of the polyimide layer with the lowest Young's modulus. The value obtained from the value of the Modulus of Modulus. The thickness ratio (%) of the high Young's modulus layer in Tables 2 and 4 is the ratio of the total thickness of the polyimide layer with the largest Young's modulus when the total thickness of the polyimide film is set to 100%. (%).

According to Table 2, the polyimide films of Examples 1 to 3 having a high Young's modulus layer on both sides of the low Young's modulus layer having a film thickness of 50 μm have a layer with a low Young's modulus of about 50 μm. Comparative Example 1 of a single-layer polyimide film has the same degree of good bending resistance and improved impact resistance, and is further compared to Comparative Example 2 of a single-layer polyimide film having a high Young's modulus layer. The bending resistance is improved. With respect to Examples 2 and 3, the impact resistance is also improved. The polyimide films of Examples 4 to 6 having high Young's modulus layers on both sides of the low Young's modulus layer having a film thickness of 80 μm have a single layer with a low Young's modulus layer having a film thickness of 80 μm. Comparative Example 5 of the polyimide film has the same degree of good bending resistance, and the impact resistance is improved. Further, compared with Comparative Example 2 which is a single layer of a polyimide film having a high Young's modulus layer, the impact resistance is higher. Improved flexibility and bending resistance. The polyimide film of Example 7 having a high Young's modulus layer on both sides of the low Young's modulus layer containing a silicon atom has polyimide as a single layer of a low Young's modulus layer containing a silicon atom. Comparative Example 4 of the film has the same degree of good bending resistance and improved impact resistance, and further has higher impact resistance and bending resistance than Comparative Example 2 which is a high-Young's modulus single-layer polyimide film. Promotion.

In addition, the single-layer polyfluorene imine films of Comparative Examples 3 and 4 were inferior in impact resistance compared to the polyfluorene imine films of Examples 1 to 7.

(Synthesis example 5)

In a 5L separable flask, add dehydrated dimethylacetamide (2903g) and 1,3-bis (3-aminopropyl) tetramethyldisilaxane (AprTMOS) (15.9 g) For the solution, control the liquid temperature to 30 ° C, and slowly add 4,4 '-(hexafluoroisopropylidene) bisphthalic anhydride (6FDA) (14.6g) so that the temperature rises below 2 ° C. ) And stir for 30 minutes with a mechanical stirrer. To this was added 2,2'-bis (trifluoromethyl) benzidine (TFMB) (387g), and after confirming complete dissolution, 4,4 '-(slowly divided into several portions so that the temperature rose to 2 ° C or lower. Hexafluoroisopropylidene) bisphthalic anhydride (6FDA) (548g), and a polyfluorene imide precursor solution 5 (solid content: 25% by mass) in which the polyfluorene imine precursor 5 was dissolved was synthesized.

Under a nitrogen atmosphere, a 5 L separable flask was charged with the above polyamidine precursor solution 5 (400 g) which had been lowered to room temperature. Dehydrated dimethylacetamide (109 g) was added thereto and stirred until it became homogeneous. Then, pyridine (41.4 g) and acetic anhydride (53.4 g) as catalysts were added and stirred at room temperature for 24 hours to synthesize a polyfluorene imine solution. To the obtained polyimide solution was added butyl acetate (406 g) and stirred until it became homogeneous, and then methanol (3000 g) was slowly added to obtain a white slurry. The slurry was filtered and washed with methanol five times to obtain polyimide 5. The weight average molecular weight of polyimide was 175,000 as measured by GPC.

Polyimide 5 was dissolved in a solvent (dichloromethane) to prepare a polyimide solution 5 having a solid content of 15% by mass. The viscosity of the polyfluorene imine solution 5 (solid content: 15% by mass) at 25 ° C was 4174 cps.

(Synthesis example 6)

Polyurethane was obtained in the same manner as in Synthesis Example 5 except that the polyimide precursor solution 4 obtained in Synthesis Example 4 was used in the order of the above Synthesis Example 5 instead of the polyfluorene imide precursor solution 5. Amine 6. Table 3 shows the weight average molecular weight of polyfluoreneimine 6 measured by GPC. In addition, in the above Synthesis Example 5, a polyfluorene imine solution 6 shown in Table 3 was obtained in the same manner as in the above Synthesis Example 5 except that the polyfluorene imine 6 was used instead of the polyfluorene imine 5. Table 3 shows the viscosity of the polyfluoreneimine solution 6 (solid content: 15% by mass) at 25 ° C.

(Example 8)

A polyimide solution 6 was used to prepare a single-layer polyimide film having a film thickness of 47 μm obtained in the order of (i) to (iii) below as the polyimide molded body D.

(i) A polyimide solution 6 is applied to a glass plate, and the film is peeled from the glass plate after being naturally dried.

(ii) The film was dried in a circulating oven at 50 ° C for 10 minutes.

(iii) The film was heated to 200 ° C. at a heating rate of 10 ° C./min under a nitrogen gas flow (oxygen concentration of 100 ppm or less), maintained at 200 ° C. for 1 hour, and then cooled to room temperature to obtain a polyimide film.

Apply polyimide solution 5 on both the front and back sides of the polyimide formed body D so that the film thickness after drying becomes 3 μm, and then dry naturally in a circulating oven at 50 ° C for 10 minutes. Under a nitrogen gas flow (with an oxygen concentration of 100 ppm or less), the temperature was raised to 200 ° C. at a heating rate of 10 ° C./min, and the temperature was maintained at 200 ° C. for 1 hour, and then cooled to room temperature, thereby obtaining a polyimide film of Example 8.

(Example 9)

In the order of (i) to (iii) in Example 8, the polyimide solution 5 was used instead of the polyimide solution 6, except that the procedure was the same as the order of (i) to (iii) above. A single-layer polyimide film having a film thickness of 55 μm was obtained as a polyimide formed body E.

Apply polyimide precursor solution 2 on both the front and back sides of the polyimide formed body E so that the film thickness after the imidization becomes 3 μm, and dry in a circulating oven at 120 ° C for 10 minutes to form a polymer. The polyimide precursor resin coating film was then heated to 350 ° C. at a heating rate of 10 ° C./min under a nitrogen gas flow (oxygen concentration of 100 ppm or less), held for 1 hour, and then cooled to room temperature. The amidine is imidized, whereby the polyammine film of Example 9 is obtained.

(Example 10)

In the order of (i) to (iii) in Example 8, the polyimide solution 5 was used instead of the polyimide solution 6, and the coating amount was adjusted so that the film thickness after drying became 20 μm. Other than this, a single-layer polyimide film having a film thickness of 20 μm was obtained as the polyimide shaped body F in the same manner as in the order of (i) to (iii) above.

Apply polyimide precursor solution 2 on the front and back sides of the polyimide formed body F such that the film thickness after the imidization becomes 15 μm, respectively, and dry in a circulating oven at 120 ° C for 10 minutes to form a polymer. The polyimide precursor resin coating film was then heated to 350 ° C. at a heating rate of 10 ° C./min under a nitrogen gas flow (oxygen concentration of 100 ppm or less), held for 1 hour, and then cooled to room temperature. The fluorene imine was obtained, thereby obtaining the polyfluorene film of Example 10.

(Example 11)

In the order of (i) to (iii) in Example 8, the polyimide solution 5 was used instead of the polyimide solution 6, except that the procedure was the same as the order of (i) to (iii) above. A single-layer polyimide film having a film thickness of 48 μm was obtained as a polyimide formed body G.

The polyimide precursor solution 2 was coated on one surface of the polyimide formed body G so that the film thickness after the imidization became 3 μm, and dried in a circulating oven at 120 ° C. for 10 minutes to form a polyimide precursor. The resin resin coating film was then heated to 350 ° C. at a heating rate of 10 ° C./min under a nitrogen gas flow (oxygen concentration of 100 ppm or less), maintained for 1 hour, and then cooled to room temperature to imidize the polyimide precursor. Thus, a polyfluorene imide film of Example 11 was obtained.

(Example 12)

In the order of (i) to (iii) in Example 1, the polyimide precursor solution 2 was used instead of the polyimide precursor solution 1. Otherwise, in addition to the above (i) to (iii), In the same manner, a single-layer polyimide film having a film thickness of 10 μm was obtained as the polyimide formed body H.

Apply the polyimide solution 5 on both the front and back sides of the polyimide formed body H so that the film thickness after drying becomes 20 μm, and then dry naturally in a circulating oven at 50 ° C for 10 minutes. Under a nitrogen gas flow (oxygen concentration of 100 ppm or less), the temperature was increased to 200 ° C. at a temperature increase rate of 10 ° C./min, and the temperature was maintained at 200 ° C. for 1 hour, followed by cooling to room temperature, thereby obtaining a polyimide film of Example 12.

(Comparative Example 6)

As the polyimide film of Comparative Example 6, a single-layer polyimide film having a film thickness of 55 μm, which was obtained using the polyimide solution 5 in the same order as in (i) to (iii) of Example 8 above, was used. .

(Comparative Example 7)

A single-layer polyimide film having a film thickness of 47 μm, which was obtained in the same order as in (i) to (iii) of Example 8 using polyimide solution 6, was used as the polyimide film of Comparative Example 7. .

The polyimide films of Examples 8 to 12 and Comparative Examples 6 and 7 were evaluated using the evaluation method described above. The evaluation results are shown in Table 4.

According to Table 4, the polyfluorene imide film of Example 8 has a high Young's modulus layer containing a silicon atom on both sides of the low Young's modulus layer containing a silicon atom, and has the same properties as a low Young's modulus containing a silicon atom. Comparative Example 7 of several layers of polyfluoride imide film has the same degree of good bending resistance and improved impact resistance, and is further compared with Comparative Example 6 of a polyfluoride film which is a single layer of a high Young's modulus layer. Compared with this, the bending resistance is improved, and the impact resistance is also improved.

The polyfluorene imide films of Examples 9 and 10 had a high Young's modulus layer containing no silicon atom on both sides of the low Young's modulus layer containing a silicon atom, and had a low Young's modulus as a silicon atom-containing layer. Comparative Example 6 of a single-layer polyimide film has the same degree of good bending resistance and significantly improved impact resistance, and is further compared with Comparative Example 2 of a single-layer polyimide film having a high Young's modulus layer. Compared with this, the bending resistance is improved, and the impact resistance is significantly improved.

The polyfluorene imide film of Example 11 has a high Young's modulus layer containing no silicon atoms on one side of the low Young's modulus layer containing silicon atoms, and has the same properties as a low Young's modulus layer containing silicon atoms. Comparative Example 6 of the polyfluoride film of the same layer has good bending resistance and the impact resistance is improved, and compared with Comparative Example 2 of the polyfluoride film which is a single layer of a high Young's modulus layer, Improved bending resistance and improved impact resistance.

The polyfluorene imide film of Example 12 has a low Young's modulus layer containing a silicon atom on both sides of the high Young's modulus layer not containing a silicon atom, and is a single layer as a low Young's modulus layer containing a silicon atom. Compared to Comparative Example 6 of the polyfluorene imide film, the impact resistance was improved, and bending resistance was improved compared to Comparative Example 2 of the polyfluorene imide film, which is a single layer of a high Young's modulus layer.

In addition, the polyfluorene imine films of Examples 7 to 12 were cut in the thickness direction, and the cross-section was observed with a scanning electron microscope (SEM). As a result, each of the polyfluorine imide layers adjacent to each other had a mixture of each other. Mixed area of material of polyimide layer.

Moreover, the polyimide films of Examples 1 to 12 were examined for the presence or absence of interference fringes. Specifically, one side of the polyimide film was filled with black ink, and an interference fringe inspection lamp was placed on the other side, and reflection observation was performed visually. As a result, any polyimide film is a practical grade, and compared with the polyimide films of Examples 1 to 6, interference fringes of the polyimide films of Examples 7 to 12 are suppressed.

The polyimide films of Examples 1 to 12 were subjected to the adhesion test of the polyimide layer on the surface according to the following adhesion test method. As a result, the proportion of the area where the polyimide layer peeled off on the surface was 20% or less. Furthermore, in Example 11, the adhesion test was performed on the surface of the high Young's modulus layer side, and in each of the examples other than Example 11, the adhesion test was performed on both sides.

<Adhesion test>

According to the grid test of JIS K5400, the polyimide layer on the surface was cut in a grid pattern at a 1 mm interval using a cutter to form 100 crystal lattices. Then, a transparent tape (Nichiban (strand)) was attached to the crystal lattice, followed by peeling. This operation was repeated five times, and then the peeling of the polyimide layer on the surface was observed.

(Example 13)

10 parts by mass of 1-hydroxy-cyclohexyl-phenyl-ketone was added to 40 parts by mass of methyl isobutyl ketone solution of neopentaerythritol triacrylate in 100 parts by mass of neopentaerythritol triacrylate ( Manufactured by BASF, Irgacure 184) to prepare a resin composition for a hard coat layer.

The polyimide film of Example 1 was cut into 10 cm × 10 cm, and the resin composition for a hard coat layer was coated on one side, and was irradiated with ultraviolet light under a nitrogen gas flow at an exposure amount of 200 mJ / cm ² to harden to form 10 μm. The hardened film with a film thickness is a hard coat layer, and a laminated body is produced.

(Examples 14 to 24)

In Example 13, the polyimide films of Examples 2 to 12 were used instead of the polyimide film of Example 1, and the laminates of Examples 14 to 24 were produced in the same manner as in Example 13. body. Furthermore, in Example 23 using the polyfluorene imide film of Example 11, a hard coat layer was formed on the surface of the high Young's modulus layer side of the polyfluorine imide film to produce a laminated body.

<Pencil hardness>

The laminated bodies obtained in Examples 13 to 24 were subjected to humidity control for 2 hours under the conditions of a temperature of 25 ° C. and a relative humidity of 60%. Thereafter, a test pencil specified by JIS-S-6006 was used and manufactured by Toyo Seiki Co., Ltd. A pencil scratch coating film hardness tester performs a pencil hardness test (9.8 N load) specified in JIS K5600-5-4 (1999) on the surface of the hard coating side to evaluate the highest pencil hardness that does not leave a flaw. This obtained the pencil hardness of each laminated body. The pencil hardness of the laminated bodies obtained in Examples 13 to 24 was all 2H.

In the laminates obtained in Examples 13 to 24, the polyimide layer containing silicon atoms and the hard coat layer were disposed adjacent to each other in the polyimide film of the laminates of Examples 20 and 24 and the hard coat layer. Better adhesion.

Claims (24)

    A polyimide film having two or more polyimide layers having different Young's modules, having an overall thickness of 5 μm or more and 200 μm or less, and a total light transmittance measured in accordance with JIS K7361-1 85% or more.         The polyimide film according to claim 1, wherein the polyimide layer having the largest Young's modulus among the polyimide layers is the polyimide having the smallest Young's modulus The Young's modulus of the layer is more than 1.2 times.         The polyimide film according to claim 1 or 2, which has more than three polyimide layers, and the polyimide layer having the largest Young's modulus among the polyimide layers is at least one surface.         The polyimide film according to claim 3, which has more than three polyimide layers, and the polyimide layer having the smallest Young's modulus among the polyimide layers is not located on the surface.         The polyimide film according to claim 1 or 2, wherein the thickest layer among the polyimide layers is not the polyimide layer having the largest Young's modulus.         The polyimide film according to claim 3, wherein the thickest layer of the polyimide layers is not a polyimide layer having the largest Young's modulus.         The polyimide film according to claim 1 or 2, wherein the total thickness of the polyimide layer having the largest Young's modulus among the polyimide layers is 60% or less of the overall thickness.         The polyimide film according to claim 3, wherein the total thickness of the polyimide layer having the largest Young's modulus among the polyimide layers is 60% or less of the overall thickness.         The polyimide film according to claim 1 or 2, wherein when the static bending test is performed according to the following static bending test method, the internal angle after the test is 90 ° or more; [static bending test method] A test piece cut into a polyimide film of 15 mm × 40 mm was bent at a half of the long side, and a metal piece with a thickness of 6 mm (100 mm × 30 mm × 6mm), and fixed with tape so that the two ends of the test piece and the overlapping parts above and below the metal piece each become 10mm. In this state, use a glass plate (100mm × 100mm × 0.7mm) clamped from above and below, and fix the test piece in a state of bending with an inner diameter of 6mm; at this time, insert a dummy test piece between the metal piece and the glass plate without the test piece, and make the glass plate parallel The test piece was fixed with a tape; the test piece fixed in a bent state was left to stand for 24 hours in an environment of 60 ° C and 90% relative humidity (RH), and thereafter, the glass plate and the tape for fixing were removed. To release the force applied to the test strip; thereafter, one of the test strips The end was fixed, and the inner angle of the test piece 30 minutes after the release of the force applied to the test piece was measured.         The polyimide film according to claim 3, wherein when the static bending test is performed according to the following static bending test method, the internal angle after the test is 90 ° or more; [static bending test method] will be cut out The test piece formed into a 15mm × 40mm polyimide film was bent at a half of the long side, and a metal piece with a thickness of 6mm (100mm × 30mm × 6mm), and use tape to fix both ends of the test piece and the overlap between the upper and lower parts of the metal piece, respectively, and use a glass plate (100mm × 100mm × 0.7mm) in this state. Clamp it from top to bottom and fix the test piece in a state of bending with an inner diameter of 6mm; at this time, insert a dummy test piece between the metal piece and the glass plate without the test piece, and use the tape so that the glass plates become parallel Fixation: The test piece fixed in a bent state in this manner was left to stand in an environment of 60 ° C and 90% relative humidity (RH) for 24 hours. Thereafter, the glass plate and the fixing tape were removed, and the alignment was released. The force exerted by the test piece; thereafter, one end of the test piece Fixed, and the test piece was measured from the inner corner released within 30 minutes after the power is applied to the test piece.         The polyimide film according to claim 1 or 2, wherein the value obtained by dividing the yellowness calculated in accordance with JIS K7373-2006 by the film thickness (μm) is 0.330 or less.         The polyimide film according to claim 3, wherein the value obtained by dividing the yellowness calculated in accordance with JIS K7373-2006 by the film thickness (m) is 0.330 or less.         The polyimide film according to claim 1 or 2, wherein each of the two or more polyimide layers contains a polyimide, the polyimide containing an aromatic ring and containing polyimide selected from (i At least one of a group consisting of a fluorine atom, (ii) an aliphatic ring, and (iii) a structure in which aromatic rings are connected to each other by a sulfofluorene group or an alkylene group which may be substituted by a fluorine atom.         The polyimide film according to claim 3, wherein each of the three or more polyimide layers contains the following polyimide, the polyimide containing an aromatic ring and containing a group selected from (i) fluorine At least one of the group consisting of an atom, (ii) an aliphatic ring, and (iii) a structure in which aromatic rings are connected to each other by a sulfonyl group or an alkylene group which may be substituted by a fluorine atom.     The polyimide film according to claim 1 or 2, wherein the polyimide layer having the largest Young's modulus among the polyimide layers contains a polyimide layer having a structure represented by the following general formula (1) Polyimide (In the general formula (1), R ¹ represents a group selected from 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride residues, 3,3', 4,4'-benzophenone tetracarboxylic acid. At least one tetravalent group in the group consisting of an acid dianhydride residue and a pyromellitic dianhydride residue, and R ² represents a group selected from 2,2′-bis (trifluoromethyl) benzidine residues, 4,4'-diaminodiphenylphosphonium residue, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane residue, bis [4- (3-amino Phenoxy) phenyl] fluorene residue, bis [4- (4-aminophenoxy) phenyl] fluorene residue, 4,4'-diamino-2,2'-bis (trifluoromethyl) Group) diphenyl ether residue, 1,4-bis [4-amino-2- (trifluoromethyl) phenoxy] benzene residue, 2,2-bis [4- (4-amino-2 -Trifluoromethylphenoxy) phenyl] hexafluoropropane residue, 4,4'-diamino-2- (trifluoromethyl) diphenyl ether residue, and 9,9-bis (4- At least one divalent group in a group consisting of an aminophenyl) fluorene residue; n represents the number of repeating units and is 1 or more). The polyimide film according to claim 15, further comprising a polyimide layer containing a polyimide having a structure represented by the following general formula (2); (In the general formula (2), R ³ represents a tetravalent residue of a tetracarboxylic acid residue having an aromatic ring or an aliphatic ring, R ⁴ represents a diamine residue of a divalent residue, and 50% of the total amount of R ⁴ Molar% or less Diamine residues having 1 or 2 silicon atoms in the main chain, and the remaining R ⁴ are diamine residues having no silicon atom and having an aromatic ring or an aliphatic ring, and the remaining R ⁴ More than half of them are selected from the group consisting of 1,4-cyclohexanediamine residues, trans-1,4-bismethylenecyclohexanediamine residues, 4,4'-diaminodiphenylsulfonium Residue, 3,4'-diaminodiphenylfluorene residue, bis [4- (3-aminophenoxy) phenyl] fluorene residue, bis [4- (4-aminophenoxy ) Phenyl] fluorene residue, 2,2-bis (4-aminophenyl) propane residue, 2,2-bis (4-aminophenyl) hexafluoropropane residue, and the following general formula ( 3) At least one type of divalent base in the group consisting of the divalent base indicated; n 'represents the number of repeating units, and is 1 or more) (In the general formula (3), R ⁵ and R ⁶ are each independently and represent a hydrogen atom, an alkyl group, or a perfluoroalkyl group). The polyimide film according to claim 3, wherein the polyimide layer having the largest Young's modulus among the polyimide layers contains a polyimide having a structure represented by the following general formula (1) Imine (In the general formula (1), R ¹ represents a group selected from 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride residues, 3,3', 4,4'-benzophenone tetracarboxylic acid. At least one tetravalent group in the group consisting of an acid dianhydride residue and a pyromellitic dianhydride residue, and R ² represents a group selected from 2,2′-bis (trifluoromethyl) benzidine residues, 4,4'-diaminodiphenylphosphonium residue, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane residue, bis [4- (3-amino Phenoxy) phenyl] fluorene residue, bis [4- (4-aminophenoxy) phenyl] fluorene residue, 4,4'-diamino-2,2'-bis (trifluoromethyl) Group) diphenyl ether residue, 1,4-bis [4-amino-2- (trifluoromethyl) phenoxy] benzene residue, 2,2-bis [4- (4-amino-2 -Trifluoromethylphenoxy) phenyl] hexafluoropropane residue, 4,4'-diamino-2- (trifluoromethyl) diphenyl ether residue, and 9,9-bis (4- At least one divalent group in a group consisting of an aminophenyl) fluorene residue; n represents the number of repeating units and is 1 or more). The polyimide film according to claim 17, further comprising a polyimide layer containing a polyimide having a structure represented by the following general formula (2); (In the general formula (2), R ³ represents a tetravalent residue of a tetracarboxylic acid residue having an aromatic ring or an aliphatic ring, R ⁴ represents a diamine residue of a divalent residue, and 50% of the total amount of R ⁴ Molar% or less Diamine residues having 1 or 2 silicon atoms in the main chain, and the remaining R ⁴ are diamine residues having no silicon atom and having an aromatic ring or an aliphatic ring, and the remaining R ⁴ More than half of them are selected from the group consisting of 1,4-cyclohexanediamine residues, trans-1,4-bismethylenecyclohexanediamine residues, 4,4'-diaminodiphenylsulfonium Residue, 3,4'-diaminodiphenylfluorene residue, bis [4- (3-aminophenoxy) phenyl] fluorene residue, bis [4- (4-aminophenoxy ) Phenyl] fluorene residue, 2,2-bis (4-aminophenyl) propane residue, 2,2-bis (4-aminophenyl) hexafluoropropane residue, and the following general formula ( 3) At least one type of divalent base in the group consisting of the divalent base indicated; n 'represents the number of repeating units, and is 1 or more) (In the general formula (3), R ⁵ and R ⁶ are each independently and represent a hydrogen atom, an alkyl group, or a perfluoroalkyl group). The polyimide film according to claim 1 or 2, which has a polyimide layer containing a polyimide having a structure represented by the following general formula (2); (In the general formula (2), R ³ represents a tetravalent residue of a tetracarboxylic acid residue having an aromatic ring or an aliphatic ring, R ⁴ represents a diamine residue of a divalent residue, and 50% of the total amount of R ⁴ Molar% or less Diamine residues having 1 or 2 silicon atoms in the main chain, and the remaining R ⁴ are diamine residues having no silicon atom and having an aromatic ring or an aliphatic ring, and the remaining R ⁴ More than half of them are selected from the group consisting of 1,4-cyclohexanediamine residues, trans-1,4-bismethylenecyclohexanediamine residues, 4,4'-diaminodiphenylsulfonium Residue, 3,4'-diaminodiphenylfluorene residue, bis [4- (3-aminophenoxy) phenyl] fluorene residue, bis [4- (4-aminophenoxy ) Phenyl] fluorene residue, 2,2-bis (4-aminophenyl) propane residue, 2,2-bis (4-aminophenyl) hexafluoropropane residue, and the following general formula ( 3) At least one type of divalent base in the group consisting of the divalent base indicated; n 'represents the number of repeating units, and is 1 or more) (In the general formula (3), R ⁵ and R ⁶ are each independently and represent a hydrogen atom, an alkyl group, or a perfluoroalkyl group). The polyimide film according to claim 3, which has a polyimide layer containing a polyimide having a structure represented by the following general formula (2); (In the general formula (2), R ³ represents a tetravalent residue of a tetracarboxylic acid residue having an aromatic ring or an aliphatic ring, R ⁴ represents a diamine residue of a divalent residue, and 50% of the total amount of R ⁴ Below Mohr%, diamine residues having 1 or 2 silicon atoms in the main chain, and the remaining R ⁴ are diamine residues having no silicon atom and having an aromatic ring or an aliphatic ring. More than half of these are selected from the group consisting of 1,4-cyclohexanediamine residues, trans-1,4-bismethylenecyclohexanediamine residues, and 4,4'-diaminodiphenylsulfonium residues. Group, 3,4'-diaminodiphenylfluorene residue, bis [4- (3-aminophenoxy) phenyl] fluorene residue, bis [4- (4-aminophenoxy) Phenyl] fluorene residue, 2,2-bis (4-aminophenyl) propane residue, 2,2-bis (4-aminophenyl) hexafluoropropane residue, and the following general formula (3 ) At least one type of divalent base in the group consisting of divalent bases represented by); n 'represents the number of repeating units, and is 1 or more) (In the general formula (3), R ⁵ and R ⁶ are each independently and represent a hydrogen atom, an alkyl group, or a perfluoroalkyl group).     A laminated body comprising the polyimide film according to any one of the above claims 1 to 20, and a hard coat layer, wherein the hard coat layer contains at least one type of polymerization of a radical polymerizable compound and a cation polymerizable compound. Thing.         For example, the laminated body according to claim 21, wherein the radical polymerizable compound is a compound having two or more (meth) acrylfluorene groups in one molecule, and the cationic polymerizable compound is two compounds having one or more epoxy groups in one molecule. A compound of at least one kind of oxo and oxetanyl.         A surface material for a display, which is the polyimide film according to any one of the above claims 1 to 20, or a laminate having the polyimide film and a hard coat layer, wherein the hard coat layer contains a radical At least one polymer of a polymerizable compound and a cationically polymerizable compound.         The surface material for a display according to claim 23, which is a flexible display.