JPWO2014041816A1 - Transparent polyimide laminate and method for producing the same - Google Patents

Abstract

It is an object of the present invention to provide a transparent polyimide laminate having a transparent polyimide layer that has a high light transmittance, a small in-plane retardation, and can be easily peeled off from a support substrate. In order to solve the above problems, a method for producing a transparent polyimide laminate comprising a support substrate and a transparent polyimide layer laminated on the support substrate, wherein a) a tetracarboxylic acid component and a diamine component are reacted. A step of coating a polyimide precursor-containing solution containing a polyimide precursor and a solvent on the support substrate; and b) a polyimide precursor film comprising a coating film of the polyimide precursor-containing solution, the transparent polyimide The transparent polyimide layer has a glass transition temperature of 260 ° C. or higher, a total light transmittance of 80% or higher, a haze of 5% or lower, and an L * a * b color specification. The absolute value of the b value in the system is 5 or less, the in-plane retardation is 10 nm or less, and the peel strength when peeling the transparent polyimide layer from the support substrate is 0.005 to 0 It is 20 kN / m, the method for producing a transparent polyimide laminate.

Description

  The present invention relates to a transparent polyimide laminate and a method for producing the same.

  Polyimide resins have excellent heat resistance and mechanical properties, and polyimide films are applied to substrates of various flexible printed wiring boards. One method for producing a polyimide film is a casting method. The casting method includes (i) applying a polyimide precursor on a supporting substrate, (ii) imidizing the polyimide precursor by heat treatment, (iii) peeling the polyimide film from the supporting substrate, How to get. The support base material is generally a glass substrate, but it has also been proposed that the support base material be a metal plate, a non-thermoplastic resin, or the like (Patent Documents 1 to 3).

  Conventionally, in a display such as a liquid crystal display element or an organic EL display element, an inorganic glass which is a transparent material is used for a panel substrate or the like. However, inorganic glass has a high specific gravity (weight), and further has low flexibility and impact resistance. Therefore, films made of PET (polyethylene terephthalate) or PEN (polyethylene naphthalate) are widely used for substrates such as liquid crystal display elements and organic EL display elements that require flexibility. However, these films have low heat resistance, and the temperature at the time of forming various elements is limited. Therefore, a substrate having higher heat resistance is required.

  On the other hand, application of a polyimide film excellent in lightness, impact resistance, workability, and flexibility to a panel substrate of a flexible device has also been studied. However, the polyimide film obtained by the techniques of Patent Documents 1 to 3 described above has low light transmittance, and it has been difficult to apply it to a panel substrate of a flexible display. On the other hand, a polyimide film obtained by reacting bis (trifluoromethyl) benzidine with a tetracarboxylic acid component has been proposed as a film having both high transparency and heat resistance (Patent Document 4).

JP 2011-56825 A JP 2004-322441 A Japanese Patent Laid-Open No. 11-10664 JP2012-40836A

  However, the polyimide film of Patent Document 4 produced by the casting method is difficult to peel from the support substrate (glass substrate), and in order to peel the polyimide film, the support substrate and the polyimide film are immersed in water. In other words, it is necessary to irradiate the interface between the supporting substrate and the polyimide film with laser light.

  The present invention has been made in view of such circumstances. An object of this invention is to provide the transparent polyimide laminated body which has a transparent polyimide layer with high light transmittance, a small in-plane phase difference, and which can be easily peeled from a support base material, and its manufacturing method.

  1st of this invention is related with the manufacturing method of the following transparent polyimide laminated bodies.

  [1] A method for producing a transparent polyimide laminate comprising a supporting substrate and a transparent polyimide layer laminated on the supporting substrate, wherein a) a polyimide precursor obtained by reacting a tetracarboxylic acid component and a diamine component A step of coating a polyimide precursor-containing solution containing a body and a solvent on the support substrate; and b) a glass transition of the transparent polyimide layer with a polyimide precursor film comprising a coating film of the polyimide precursor-containing solution. The transparent polyimide layer has a glass transition temperature of 260 ° C. or higher, a total light transmittance of 80% or higher, a haze of 5% or lower, and a b value in the L * a * b color system. The absolute value is 5 or less, the in-plane retardation is 10 nm or less, and the peel strength when peeling the transparent polyimide layer from the support substrate is 0.005 to 0.20 kN / m. , The method for producing a transparent polyimide laminate.

[2] The method for producing a transparent polyimide laminate according to [1], wherein the support substrate is a flexible substrate.
[3] The method for producing a polyimide laminate according to [1] or [2], wherein a release agent is further included in the polyimide precursor-containing solution.
[4] The method for producing a transparent polyimide laminate according to any one of [1] to [3], wherein the oxygen concentration of the atmosphere is 5% by volume or less in the temperature range exceeding 200 ° C. in the step b).
[5] The method for producing a transparent polyimide laminate according to any one of [1] to [3], wherein the atmosphere is decompressed in a temperature range exceeding 200 ° C. in the step b).
[6] The step b) is a step of heating the polyimide precursor film while raising the temperature from 150 ° C. or lower to over 200 ° C., and the average temperature rising rate in the temperature range of 150 to 200 ° C. in the step b). The manufacturing method of the transparent polyimide laminated body in any one of [1]-[5] which makes 0.25-50 degree-C / min.

（一般式（ａ）中、Ｒ^１は炭素数４〜２７の４価の基を示し、かつ
脂肪族基、単環式脂肪族基、縮合多環式脂肪族基、単環式芳香族基、もしくは縮合多環式芳香族基を示すか、環式脂肪族基が直接もしくは架橋員により相互に連結された非縮合多環式脂肪族基を示すか、または芳香族基が直接もしくは架橋員により相互に連結された非縮合多環式芳香族基を示す）

[7] The polyimide precursor includes a tetracarboxylic acid component (A) containing at least one tetracarboxylic dianhydride represented by the following general formula (a), and the following general formulas (b-1) to ( The compound according to any one of [1] to [6], which is a compound obtained by reacting a diamine component (B) containing one or more diamines selected from the group consisting of compounds represented by b-3). A method for producing a transparent polyimide laminate.

(In the general formula (a), R ¹ represents a tetravalent group having 4 to 27 carbon atoms, and an aliphatic group, a monocyclic aliphatic group, a condensed polycyclic aliphatic group, or a monocyclic aromatic group. Or a condensed polycyclic aromatic group, a non-condensed polycyclic aliphatic group in which the cycloaliphatic groups are linked directly or by a bridging member, or an aromatic group is directly or a bridging member Represents non-condensed polycyclic aromatic groups linked together by

（一般式（Ｉ）中、Ｒ^１０は炭素数４〜２７の４価の基を示し、かつ
脂肪族基、単環式脂肪族基、縮合多環式脂肪族基、単環式芳香族基、もしくは縮合多環式芳香族基を示すか、環式脂肪族基が直接もしくは架橋員により相互に連結された非縮合多環式脂肪族基を示すか、または芳香族基が直接もしくは架橋員により相互に連結された非縮合多環式芳香族基を示す）[8] The polyimide precursor has a repeating unit represented by the following general formula (I), and the 1,4-bismethylenecyclohexane skeleton (X) in the general formula (I) is represented by the formula (X1). And a cis isomer represented by the formula (X2), the content ratio of the trans isomer to the cis isomer (trans isomer + cis isomer = 100%) is 60% ≦ trans isomer ≦ 100%, The method for producing a transparent polyimide laminate according to [7], wherein 0% ≦ cis body ≦ 40%.

(In the general formula (I), R ¹⁰ represents a tetravalent group having 4 to 27 carbon atoms, and an aliphatic group, a monocyclic aliphatic group, a condensed polycyclic aliphatic group, or a monocyclic aromatic group. Or a condensed polycyclic aromatic group, a non-condensed polycyclic aliphatic group in which the cycloaliphatic groups are linked directly or by a bridging member, or an aromatic group is directly or a bridging member Represents non-condensed polycyclic aromatic groups linked together by

（一般式（Ｇ）及び（Ｈ）中、Ｒ^６及びＲ^８はそれぞれ独立に炭素数４〜２７の４価の基であり、かつ脂肪族基、単環式脂肪族基、縮合多環式脂肪族基、単環式芳香族基、もしくは縮合多環式芳香族基を示すか、環式脂肪族基が直接もしくは架橋員により相互に連結された非縮合多環式脂肪族基を示すか、または芳香族基が直接もしくは架橋員により相互に連結された非縮合多環式芳香族基を示し；
一般式（Ｈ）において、Ｒ^７は、炭素数４〜５１の２価の基であり、かつ脂肪族基、単環式脂肪族基（但し、１,４-シクロヘキシレン基を除く）、縮合多環式脂肪族基、単環式芳香族基もしくは縮合多環式芳香族基であるか、環式脂肪族基が直接もしくは架橋員により相互に連結された非縮合多環式脂肪族基であるか、または芳香族基が直接もしくは架橋員により相互に連結された非縮合多環式芳香族基である）[9] The polyimide precursor is composed of a polyamic acid block composed of a repeating structural unit represented by the following general formula (G) and a polyimide block composed of a repeating structural unit represented by the following general formula (H) The method for producing a transparent polyimide laminate according to any one of [1] to [6], which is a block polyamic acid imide.

(In General Formulas (G) and (H), R ⁶ and R ⁸ are each independently a tetravalent group having 4 to 27 carbon atoms, and an aliphatic group, a monocyclic aliphatic group, or a condensed polycyclic group. Whether it represents an aliphatic group, a monocyclic aromatic group, or a condensed polycyclic aromatic group, or a non-condensed polycyclic aliphatic group in which the cyclic aliphatic groups are connected to each other directly or by a bridging member Or a non-condensed polycyclic aromatic group in which the aromatic groups are connected to each other directly or by a bridging member;
In the general formula (H), R ⁷ is a divalent group having 4 to 51 carbon atoms, and an aliphatic group, a monocyclic aliphatic group (excluding a 1,4-cyclohexylene group), a condensed group A polycyclic aliphatic group, a monocyclic aromatic group or a condensed polycyclic aromatic group, or a non-condensed polycyclic aliphatic group in which the cyclic aliphatic groups are connected to each other directly or by a bridging member Or a non-condensed polycyclic aromatic group in which the aromatic groups are connected to each other directly or by a bridging member)

  [10] The step a) is a step of applying the polyimide precursor-containing solution onto the support substrate fed out from a roll, and the step b) is performed after the polyimide precursor film is heated. The manufacturing method of the transparent polyimide laminated body in any one of [1]-[9] including the step which winds up a transparent polyimide laminated body on a roll.

2nd of this invention is related with the following transparent polyimide laminated bodies and optical films.
[11] A transparent polyimide laminate obtained from the production method according to any one of [1] to [9].
[12] An optical film obtained by peeling a transparent polyimide layer from a support substrate of the transparent polyimide laminate according to [11].

3rd of this invention is related with the manufacturing method of a transparent polyimide film, the manufacturing method of a flexible device, and various display apparatuses.
[13] A method for producing a transparent polyimide film, comprising a step of peeling the transparent polyimide layer from the support substrate of the transparent polyimide laminate according to [11] to obtain a transparent polyimide film.
[14] A step of forming an element on the transparent polyimide layer of the transparent polyimide laminate according to [11], and a step of peeling the transparent polyimide layer after forming the element from the support substrate. A manufacturing method of a flexible device.
[15] A method for producing a flexible device, comprising a step of forming an element on a transparent polyimide film obtained by the production method according to [11].
[16] A touch panel display obtained by the method for producing a flexible device according to [14] or [15].
[17] A liquid crystal display obtained by the method for producing a flexible device according to [14] or [15].
[18] An organic EL display obtained by the method for producing a flexible device according to [14] or [15].

  ADVANTAGE OF THE INVENTION According to this invention, the transparent polyimide laminated body which has the transparent polyimide layer which can be peeled easily from a support base material, has high light transmittance, and has a small in-plane phase difference is obtained.

FIG. 1 is a side view showing an example of a production apparatus for producing a long transparent polyimide laminate by the production method of the present invention. FIG. 2 is a schematic cross-sectional view showing an example of a method for producing a flexible device using the transparent polyimide laminate of the present invention. FIG. 3 is a schematic cross-sectional view showing another example of a method for producing a flexible device using the transparent polyimide laminate of the present invention. FIG. 4 is a schematic cross-sectional view showing another example of a method for producing a flexible device using the transparent polyimide laminate of the present invention.

A. The manufacturing method of a transparent polyimide laminated body In the manufacturing method of this invention, it is a transparent polyimide laminated body containing a support base material and a transparent polyimide layer, Comprising: The peel strength at the time of peeling a transparent polyimide layer from a support base material is 0. The transparent polyimide laminate is manufactured in a range of 005 to 0.20 kN / m, preferably 0.01 to 0.15 kN / m, and more preferably 0.05 to 0.10 kN / m. The peel strength is a value measured according to JIS C-6471 (peeling angle 90 °).

  As described above, when a polyimide film is produced on a supporting substrate by a general casting method, it is difficult to peel off the obtained polyimide film and the supporting substrate, and the polyimide film and the supporting substrate are immersed in water or supported. It was necessary to peel off the interface between the substrate and the polyimide film by laser irradiation. In addition, when an element is formed on a polyimide film and then the film is peeled off from the supporting substrate, there is a possibility that the element is stressed or water is attached to the element to damage the element.

  On the other hand, in the transparent polyimide laminated body manufactured with the manufacturing method of this invention, the peel strength of a transparent polyimide layer and a support base material is small. Therefore, even after an element is formed on the transparent polyimide layer, the transparent polyimide layer can be easily peeled from the support substrate.

The manufacturing method of the present invention includes the following two steps.
a) A step of applying a polyimide precursor-containing solution containing a polyimide precursor obtained by reacting a tetracarboxylic acid component and a diamine component and a solvent onto a supporting substrate. b) A coating film of the polyimide precursor-containing solution. The process of heating the polyimide precursor film above the glass transition temperature of the transparent polyimide layer

  The transparent polyimide laminate of the present invention can be produced as a long transparent polyimide laminate 30 using, for example, the apparatus shown in FIG. The manufacturing apparatus shown in FIG. 1 includes a polyimide precursor coating device 20, an endless belt 21, and a plurality of heating furnaces 10 arranged along the moving direction of the endless belt 21. A polyimide precursor is applied to the supporting base material 11 unwound from the roll by a coating device 20 to form a coating film 1 of the polyimide precursor. And the coating film 1 of a polyimide precursor is imidized with the heating furnace 10, and the transparent polyimide laminated body on which the support base material 11 and transparent polyimide layer 1 'were laminated | stacked is obtained. Thereafter, the long transparent polyimide laminate is wound up to form a roll body 30.

1. About Step a) A polyimide precursor-containing solution containing a polyimide precursor obtained by reacting a tetracarboxylic acid component and a diamine component and a solvent is prepared. The type of polyimide precursor contained in the polyimide precursor-containing solution is not particularly limited, but from the viewpoint of increasing the total light transmittance of the resulting transparent polyimide layer, the main chain of the polyimide precursor contains an alicyclic group. It is preferred that The polyimide precursor containing solution containing such a polyimide precursor will be described in detail later.

  The prepared polyimide precursor containing solution is apply | coated on a support base material. The supporting substrate is not particularly limited as long as it has solvent resistance and heat resistance. The support substrate is preferably one having good peelability of the resulting transparent polyimide layer, and is preferably a flexible substrate made of a metal or a heat-resistant polymer film. Examples of flexible substrates made of metal include copper, aluminum, stainless steel, iron, silver, palladium, nickel, chromium, molybdenum, tungsten, zirconium, gold, cobalt, titanium, tantalum, zinc, lead, tin, silicon, bismuth , Indium, or a metal foil made of an alloy thereof. A release agent may be coated on the surface of the metal foil.

  Examples of the flexible substrate made of a heat resistant polymer film include a polyimide film, an aramid film, a polyether ether ketone film, and a polyether ether sulfone film. The flexible substrate made of a heat-resistant polymer film may contain a release agent or an antistatic agent, and may be coated with a release agent or an antistatic agent on the surface. It is preferable that the supporting substrate is a polyimide film because the peelability from the obtained transparent polyimide layer is good and the heat resistance and solvent resistance are high.

  The ten-point average roughness (Rz) of the surface of the supporting substrate is preferably less than 0.4 μm, more preferably 0.2 μm or less, and even more preferably 0.1 μm or less. When the ten-point average roughness of the surface of the supporting substrate is small, the haze of the transparent polyimide layer formed on the supporting substrate tends to be small. The ten-point average roughness (Rz) of the surface of the supporting substrate is a value measured according to JIS B-0601, and is a value measured in the width direction of the supporting substrate.

  Moreover, it is preferable that there are no defects which consist of adhesion of a foreign material, a streak-like wound, etc. on the support base material surface. Even if the ten-point average roughness (Rz) is low, the haze of the obtained transparent polyimide layer tends to increase when these defects are present in the support substrate. The defects on the surface of the supporting substrate can be evaluated by “the number of defects per unit area”. Defects are confirmed by visual observation. The number of defects contained per support substrate 210 mm × 297 mm (A4 size) is usually preferably 10 or less, more preferably 5 or less, and even more preferably 1 or less.

  The shape of the support substrate is appropriately selected according to the shape of the transparent polyimide laminate to be produced, and may be a single-leaf sheet shape or a long shape. The thickness of the support substrate is preferably 5 to 150 μm, and more preferably 10 to 70 μm. When the thickness of the supporting substrate is less than 5 μm, wrinkles may be generated on the supporting substrate or the supporting substrate may be torn during application of the polyimide precursor-containing solution.

  Application | coating to the support base material of a polyimide precursor containing solution will not be restrict | limited especially if the polyimide precursor containing solution can be apply | coated by a fixed film thickness. Examples of the coating apparatus include a die coater, a comma coater, a roll coater, a gravure coater, a curtain coater, a spray coater, and a lip coater.

  The thickness (coating film thickness) of the polyimide precursor-containing solution is appropriately selected according to the desired thickness of the transparent polyimide layer and the concentration of the polyimide precursor in the polyimide precursor-containing solution.

2. About Step b) In Step b), the polyimide precursor-containing solution coating film formed on the supporting substrate in Step a) described above; that is, the polyimide precursor film is heated. Specifically, i) the polyimide precursor film is heated while increasing the temperature from 150 ° C. or lower to over 200 ° C., and ii) the temperature (constant temperature) equal to or higher than the glass transition temperature of the obtained transparent polyimide layer. Thus, it is preferable to be a step of heating for a certain time.

  i) The temperature at which a general polyimide precursor is imidized is 150 to 200 ° C. Therefore, when the temperature of the polyimide precursor film is rapidly increased to 200 ° C. or higher, the polyimide precursor on the coating film surface is imidized before the solvent is volatilized from the polyimide precursor film. And when the solvent in a coating film foams or a solvent is discharge | released outside, an unevenness | corrugation arises in the coating-film surface. Therefore, in the temperature range of 150 to 200 ° C., it is preferable to gradually increase the temperature of the polyimide precursor film. Specifically, the rate of temperature increase in the temperature range of 150 to 200 ° C. is preferably 0.25 to 50 ° C./min, more preferably 1 to 40 ° C./min, and further preferably 2 to 30 ° C./min. Minutes.

  Although the temperature rise may be continuous or stepwise (sequential), it is preferable to be continuous from the viewpoint of suppressing the appearance defect of the obtained transparent polyimide layer. Moreover, in the above-mentioned whole temperature range, the temperature increase rate may be constant or may be changed in the middle.

  An example of a method of heating a single-leaf polyimide precursor film while raising the temperature includes a method of raising the temperature in the oven for heating the polyimide precursor film. In this case, the heating rate is adjusted by the oven setting. When heating the long polyimide precursor film while raising the temperature, for example, as shown in FIG. 1, a heating furnace 10 for heating the polyimide precursor film 1 is transported to the support base 11 ( A plurality of them are arranged along the (moving) direction; the temperature of the heating furnace 10 is changed for each heating furnace 10. For example, what is necessary is just to raise the temperature of each heating furnace 10 along the moving direction of the support base material 11. FIG. In this case, the temperature increase rate is adjusted by the conveyance speed of the support substrate 11.

  ii) After heating the polyimide precursor film while increasing the temperature, the polyimide precursor film is further heated at a temperature (constant temperature) equal to or higher than the glass transition temperature of the transparent polyimide layer obtained. Although the temperature at this time will not be restrict | limited especially if it is more than the glass transition temperature of the transparent polyimide layer obtained, More preferably, it is 5-30 degreeC higher than the glass transition temperature of the transparent polyimide layer obtained, More preferably, the transparent obtained The temperature is 5 to 20 ° C. higher than the glass transition temperature of the polyimide layer. The polyimide precursor can be sufficiently imidized by heating at a temperature equal to or higher than the glass transition temperature of the obtained transparent polyimide layer for a certain time. Moreover, since it heats for a fixed time at the temperature higher than the glass transition temperature of the transparent polyimide layer obtained, a transparent polyimide layer softens and the solvent inside a transparent polyimide layer fully volatilizes. The heating time at a temperature equal to or higher than the glass transition temperature is appropriately selected according to the heating temperature, the thickness of the polyimide precursor film, the amount of solvent contained in the polyimide precursor-containing solution, and the like. Usually, it is about 0.5 to 2 hours.

  The heating method for heating the polyimide precursor film at a constant temperature is not particularly limited, and for example, it is heated in an oven adjusted to a constant temperature. Further, the long polyimide precursor film is heated in a heating furnace or the like that maintains a constant temperature.

  Polyimide is easily oxidized when heated at a temperature exceeding 200 ° C. When polyimide is oxidized, the transparent polyimide layer obtained turns yellow, and the total light transmittance of the transparent polyimide layer decreases. Therefore, in a temperature range exceeding 200 ° C., it is preferable that (i) the oxygen concentration of the heating atmosphere is 5% by volume or less, or (ii) the heating atmosphere is decompressed.

(I) When the oxygen concentration in the heating atmosphere is 5% by volume or less, the oxidation reaction of polyimide is suppressed. The oxygen concentration in the temperature region exceeding 200 ° C. is more preferably 3% by volume or less, and further preferably 1% by volume or less. A method for reducing the oxygen concentration is not particularly limited, and may be a method of introducing an inert gas into the heating atmosphere. The oxygen concentration in the atmosphere is measured by a commercially available oxygen concentration meter (for example, a zirconia oxygen concentration meter).

(Ii) Moreover, the oxidation reaction of polyimide is also suppressed by reducing the heating atmosphere. When the heating atmosphere is decompressed, the pressure in the atmosphere is preferably 5 kPa or less, more preferably 1 kPa or less. When reducing the heating atmosphere, the polyimide precursor film is heated in a vacuum oven or the like.

  Step b) The imidation ratio of the transparent polyimide layer at the end of heating is preferably 90% or more, more preferably 93% or more, and still more preferably 95% or more. If the imidization ratio is less than 90%, imidization proceeds when the transparent polyimide layer is used, and moisture may be released from the transparent polyimide layer. The imidization rate can be calculated from the measured value of the IR absorption spectrum of the transparent polyimide layer. Specifically, it is calculated by the following method.

The transparent polyimide layer is peeled from the supporting substrate, and the IR absorption spectrum is measured. The calculated absorption peak height of 1500 cm ^-1 for (peak by C = C stretching vibration of a benzene ring (the reference)), the absorption peak height of the 1370 cm ^-1 ratio A of (C-N stretching vibration of an imide ring) To do. On the other hand, a polyimide precursor film made of a polyimide precursor-containing solution having the same composition is produced, and this is heated at 270 ° C. for 2 hours or longer to be completely imidized. The IR absorption spectrum of this film was also measured. Similarly, the absorption peak height (imide ring) of 1370 cm ⁻¹ with respect to the absorption peak height of 1500 cm ⁻¹ (peak (reference) due to C═C stretching vibration of the benzene ring). (C-N stretching vibration) B is calculated. And the value of the ratio A with respect to the ratio B (ratio A / ratio B) x 100 (%) is obtained, and this is set as the imidization rate.

  On the other hand, at the end of step b), the amount of solvent remaining in the transparent polyimide layer (mass of remaining solvent × 100 / mass of transparent polyimide layer) is preferably 1.0% by mass or less, more preferably 0. 0.8 mass% or less, more preferably 0.5 mass% or less. If the residual amount of the solvent exceeds 1.0% by mass, the solvent may be released from the transparent polyimide layer when the transparent polyimide layer is used. The residual amount of solvent is specified by peeling the transparent polyimide layer from the support substrate, pyrolyzing the transparent polyimide layer with an electric furnace type pyrolysis furnace, etc., and analyzing the pyrolyzed components with a gas chromatography mass spectrometer To do.

  When the obtained transparent polyimide laminate is long after completion of the heating, a step of winding the transparent polyimide laminate to form a roll as described above may be performed.

3. About a polyimide precursor containing solution The polyimide precursor containing solution applied in step a) contains a polyimide precursor and a solvent, and if necessary, a release agent. When a release agent is contained in the polyimide precursor-containing solution, the peelability between the transparent polyimide layer and the support substrate in the transparent polyimide laminate is increased. Moreover, various additives may be contained in the polyimide precursor containing solution as needed.

3-1. Polyimide precursor The polyimide precursor is obtained by reacting a tetracarboxylic acid component (A) with a diamine component (B). It is preferable that the density | concentration of the polyimide precursor contained in a polyimide precursor containing solution is 5-50 mass%, More preferably, it is 10-40 mass%. When the density | concentration of a polyimide precursor exceeds 50 mass%, the viscosity of a polyimide precursor containing solution will become high too much, and the application | coating to a support base material may become difficult. On the other hand, when it is less than 5% by mass, the viscosity of the polyimide precursor-containing solution is excessively low, and the polyimide precursor film may not be applied to a desired thickness. Moreover, it takes time to dry the solvent, and the production efficiency of the polyimide film is deteriorated.

一般式（ａ）中、Ｒ^１は、炭素数４〜２７である４価の有機基を示す。Ｒ^１は、脂肪族基；単環式脂肪族基；縮合多環式脂肪族基；単環式芳香族基；縮合多環式芳香族基；環式脂肪族基が直接もしくは架橋員により相互に連結された非縮合多環式脂肪族基；芳香族基が直接もしくは架橋員により相互に連結された非縮合多環式芳香族基でありうる。3-1-1. Tetracarboxylic acid component (A)
The tetracarboxylic acid component (A) constituting the polyimide precursor includes a tetracarboxylic dianhydride represented by the following general formula (a). The tetracarboxylic acid component (A) may contain only one type of tetracarboxylic dianhydride represented by the general formula (a), or may contain two or more types.

In general formula (a), R ¹ represents a tetravalent organic group having 4 to 27 carbon atoms. R ¹ represents an aliphatic group; a monocyclic aliphatic group; a condensed polycyclic aliphatic group; a monocyclic aromatic group; a condensed polycyclic aromatic group; A non-fused polycyclic aliphatic group linked to each other; a non-fused polycyclic aromatic group in which the aromatic groups are linked to each other directly or by a cross-linking member.

  The tetracarboxylic dianhydride represented by the general formula (a) is particularly preferably an aromatic tetracarboxylic dianhydride or an alicyclic tetracarboxylic dianhydride.

  Examples of the aromatic tetracarboxylic dianhydride represented by the general formula (a) include pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) sulfide dianhydride, bis (3,4 -Dicarboxyphenyl) sulfone dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis ( 3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 1,3-bis (3,4-dicarboxyphenoxy) benzene dianhydride, 1,4 -Bis (3,4-dicarboxyphenoxy) benzene dianhydride, 4,4'-bis ( , 4-dicarboxyphenoxy) biphenyl dianhydride, 2,2-bis [(3,4-dicarboxyphenoxy) phenyl] propane dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,2 ', 3,3'-benzophenonetetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoro Propane dianhydride, bis (2,3-dicarboxyphenyl) ether dianhydride, bis (2,3-dicarboxyphenyl) sulfide dianhydride, bis (2,3-dicarboxyphenyl) sulfone dianhydride, 1,3-bis (2,3-dicarboxyphenoxy) benzene 1,4-bis (2,3-dicarboxyphenoxy) benzene dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,3-bis (3,4-dicarboxybenzoyl) ) Benzene dianhydride, 1,4-bis (3,4-dicarboxybenzoyl) benzene dianhydride, 1,3-bis (2,3-dicarboxybenzoyl) benzene dianhydride, 1,4-bis ( 2,3-dicarboxybenzoyl) benzene dianhydride, 4,4′-isophthaloyl diphthalic anhydride diazodiphenylmethane-3,3 ′, 4,4′-tetracarboxylic dianhydride, diazodiphenylmethane-2, 2 ', 3,3'-tetracarboxylic dianhydride, 2,3,6,7-thioxanthone tetracarboxylic dianhydride, 2,3,6,7-anthraquinone tetracarboxylic dianhydride, 2,3 , 6,7-xanthone tetracarboxylic dianhydride Murrell.

  Examples of the alicyclic tetracarboxylic dianhydride represented by the general formula (a) include cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1, 2,4,5-cyclohexanetetracarboxylic dianhydride, bicyclo [2.2.1] heptane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] oct-7 -Ene-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] octane-2,3,5,6-tetracarboxylic dianhydride, 2,3,5-tri Carboxycyclopentyl acetic acid dianhydride, bicyclo [2.2.1] heptane-2,3,5-tricarboxylic acid-6-acetic acid dianhydride, 1-methyl-3-ethylcyclohex-1-ene-3- ( 1,2), 5,6-tetracarboxylic dianhydride, decahydro-1,4,5,8-dimethananaphthalene-2,3,6,7-tetracarboxylic dianhydride, - (2,5-di-oxo-tetrahydrofuran-3-yl) - tetralin-1,2-dicarboxylic acid dianhydride, 3,3 ', and the like 4,4'-dicyclohexyl tetracarboxylic dianhydride.

  When the tetracarboxylic dianhydride represented by the general formula (a) includes an aromatic ring such as a benzene ring, a part or all of the hydrogen atoms on the aromatic ring are a fluoro group, a methyl group, a methoxy group It may be substituted with a group, a trifluoromethyl group, a trifluoromethoxy group, or the like. Further, when the tetracarboxylic dianhydride represented by the general formula (a) includes an aromatic ring such as a benzene ring, an ethynyl group, a benzocyclobuten-4′-yl group, a vinyl, depending on the purpose A group serving as a crosslinking point selected from a group, an allyl group, a cyano group, an isocyanate group, a nitrilo group, an isopropenyl group, and the like may be included in the structure of the tetracarboxylic acid. In particular, the tetracarboxylic dianhydride represented by the general formula (a) has a main clavicle group having a crosslinking point such as a vinylene group, a vinylidene group, and an ethynylidene group within a range that does not impair molding processability. It is preferably incorporated in the case.

  The tetracarboxylic acid component (A) may include hexacarboxylic dianhydrides and octacarboxylic dianhydrides in addition to the tetracarboxylic dianhydrides represented by the general formula (a). . When these anhydrides are contained, a branched chain is introduced into the resulting polyimide. Only one kind of these anhydrides may be contained, or two or more kinds may be contained.

3-1-2. Diamine component (B)
Diamines represented by the following general formulas (b-1) to (b-3) are included in the diamine component (B) constituting the polyimide precursor. In the diamine component (B), only one diamine represented by the following general formulas (b-1) to (b-3) may be included, or two or more diamines may be included. The diamine component (B) may contain a diamine (b-4) other than the diamines represented by the general formulas (b-1) to (b-3).

The cyclohexane skeleton of cyclohexadiamine represented by the general formula (b-1) includes the following two geometric isomers (cis isomer / trans isomer). The trans isomer is represented by the following general formula (Z-1), and the cis isomer is represented by the following general formula (Z-2).

  The cis / trans ratio of the cyclohexane skeleton in the general formula (Z-1) is preferably 50/50 to 0/100, and more preferably 30/70 to 0/100. When the proportion of the trans isomer increases, the molecular weight of the polyimide precursor generally tends to increase. Therefore, the strength of the film is likely to increase.

  The cis / trans ratio of cyclohexane-derived units contained in the polyimide precursor is measured by nuclear magnetic resonance spectroscopy.

  The position of the aminomethyl group of norbornanediamine represented by the general formula (b-2) is not particularly limited. For example, the norbornanediamine represented by the general formula (b-2) may include structural isomers having different aminomethyl group positions, optical isomers including S and R isomers, and the like. These may be included in any ratio.

The 1,4-bismethylenecyclohexane skeleton (X) of 1,4-bis (aminomethyl) cyclohexane represented by the general formula (b-3) has two kinds of geometric isomers (cis isomer / trans isomer). is there. The trans isomer is represented by the following general formula (X1), and the cis isomer is represented by the following general formula (X2).

  The cis / trans ratio of the unit derived from 1,4-bis (aminomethyl) cyclohexane is preferably 40/60 to 0/100, and more preferably 20/80 to 0/100. The glass transition temperature of the polyimide in which the diamine represented by the general formula (b-3) is contained as a constituent component is controlled by the cis / trans ratio, and when the ratio of the trans form (X1) increases, the glass transition temperature of the polyimide. Will increase.

  The cis / trans ratio of the unit derived from 1,4-bis (aminomethyl) cyclohexane contained in the polyimide precursor is measured by nuclear magnetic resonance spectroscopy.

In the diamine component (B), a diamine (b-4) represented by the following general formula other than the diamines represented by the above general formulas (b-1) to (b-3) may be contained. .

In General Formula (b-4), R ′ is a divalent group having 4 to 51 carbon atoms. R ′ represents an aliphatic group; a monocyclic aliphatic group (however, a 1,4-cyclohexylene group, a group represented by the following general formula (X), and a group represented by the following general formula (Y): Excluded); condensed polycyclic aliphatic group; monocyclic aromatic group; condensed polycyclic aromatic group; non-condensed polycyclic aliphatic group in which cyclic aliphatic groups are connected to each other directly or by a bridging member A non-condensed polycyclic aromatic group in which the aromatic groups are connected to each other directly or by a bridging member.

  Examples of the diamine represented by the general formula (b-4) include a diamine having a benzene ring, a diamine having an aromatic substituent, a diamine having a spirobiindane ring, a siloxane diamine, an ethylene glycol diamine, and an alkylene diamine. , Alicyclic diamines and the like.

Examples of diamines having a benzene ring include
<1> Diamine having one benzene ring such as p-phenylenediamine, m-phenylenediamine, p-xylylenediamine, m-xylylenediamine;
<2> 3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl sulfide, 3,4′-diaminodiphenyl sulfide, 4,4′- Diaminodiphenyl sulfide, 3,3′-diaminodiphenyl sulfone, 3,4′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl sulfone, 3,3′-diaminobenzophenone, 4,4′-diaminobenzophenone, 3,4 '-Diaminobenzophenone, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 2,2-di (3-aminophenyl) propane, 2,2-di (4- Aminophenyl) propane, 2- (3-aminophenyl) -2- (4-aminophenyl) propane, 2,2-di (3-aminophenyl)- , 1,1,3,3,3-hexafluoropropane, 2,2-di (4-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 2- (3-aminophenyl) ) -2- (4-Aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 1,1-di (3-aminophenyl) -1-phenylethane, 1,1-di ( Diamines having two benzene rings such as 4-aminophenyl) -1-phenylethane, 1- (3-aminophenyl) -1- (4-aminophenyl) -1-phenylethane;
<3> 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene, 1,4-bis (4- Aminophenoxy) benzene, 1,3-bis (3-aminobenzoyl) benzene, 1,3-bis (4-aminobenzoyl) benzene, 1,4-bis (3-aminobenzoyl) benzene, 1,4-bis ( 4-Aminobenzoyl) benzene, 1,3-bis (3-amino-α, α-dimethylbenzyl) benzene, 1,3-bis (4-amino-α, α-dimethylbenzyl) benzene, 1,4-bis (3-Amino-α, α-dimethylbenzyl) benzene, 1,4-bis (4-amino-α, α-dimethylbenzyl) benzene, 1,3-bis (3-amino-α, α-ditrifluoromethyl) Benzyl) benzene, 1,3-bis (4-amino-α, α-ditrifluoromethylben) L) benzene, 1,4-bis (3-amino-α, α-ditrifluoromethylbenzyl) benzene, 1,4-bis (4-amino-α, α-ditrifluoromethylbenzyl) benzene, 2,6- A diamine having three benzene rings such as bis (3-aminophenoxy) benzonitrile, 2,6-bis (3-aminophenoxy) pyridine;
<4> 4,4′-bis (3-aminophenoxy) biphenyl, 4,4′-bis (4-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone, bis [4- ( 4-aminophenoxy) phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (3-aminophenoxy) phenyl] sulfone Bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, 2,2-bis [4 -(3-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [3- (3-aminophene) Noxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3- A diamine having four benzene rings such as hexafluoropropane;
<5> 1,3-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,3-bis [4- (4-aminophenoxy) benzoyl] benzene, 1,4-bis [4- (3- Aminophenoxy) benzoyl] benzene, 1,4-bis [4- (4-aminophenoxy) benzoyl] benzene, 1,3-bis [4- (3-aminophenoxy) -α, α-dimethylbenzyl] benzene, , 3-Bis [4- (4-aminophenoxy) -α, α-dimethylbenzyl] benzene, 1,4-bis [4- (3-aminophenoxy) -α, α-dimethylbenzyl] benzene, 1,4 A diamine having five benzene rings such as bis [4- (4-aminophenoxy) -α, α-dimethylbenzyl] benzene;
<6> 4,4′-bis [4- (4-aminophenoxy) benzoyl] diphenyl ether, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] benzophenone, 4,4 Has 6 benzene rings such as' -bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] diphenylsulfone, 4,4'-bis [4- (4-aminophenoxy) phenoxy] diphenylsulfone Diamine is included.

  Examples of diamines with aromatic substituents include 3,3′-diamino-4,4′-diphenoxybenzophenone, 3,3′-diamino-4,4′-dibiphenoxybenzophenone, 3,3′-diamino -4-phenoxybenzophenone, 3,3′-diamino-4-biphenoxybenzophenone and the like are included.

  Examples of diamines having a spirobiindane ring include 6,6′-bis (3-aminophenoxy) -3,3,3 ′, 3′-tetramethyl-1,1′-spirobiindane, 6,6′-bis ( 4-aminophenoxy) -3,3,3 ′, 3′-tetramethyl-1,1′-spirobiindane and the like.

  Examples of siloxane diamines include 1,3-bis (3-aminopropyl) tetramethyldisiloxane, 1,3-bis (4-aminobutyl) tetramethyldisiloxane, α, ω-bis (3-aminopropyl) ) Polydimethylsiloxane, α, ω-bis (3-aminobutyl) polydimethylsiloxane and the like.

  Examples of ethylene glycol diamines include bis (aminomethyl) ether, bis (2-aminoethyl) ether, bis (3-aminopropyl) ether, bis [(2-aminomethoxy) ethyl] ether, bis [2- (2-aminoethoxy) ethyl] ether, bis [2- (3-aminoprotoxy) ethyl] ether, 1,2-bis (aminomethoxy) ethane, 1,2-bis (2-aminoethoxy) ethane, , 2-bis [2- (aminomethoxy) ethoxy] ethane, 1,2-bis [2- (2-aminoethoxy) ethoxy] ethane, ethylene glycol bis (3-aminopropyl) ether, diethylene glycol bis (3-amino Propyl) ether, triethylene glycol bis (3-aminopropyl) ether, and the like.

  Examples of alkylenediamines include ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, and 1,8-diaminooctane. 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane and the like are included.

  Examples of alicyclic diamines include cyclobutanediamine, cyclohexanediamine, di (aminomethyl) cyclohexane [bis (aminomethyl) cyclohexane excluding 1,4-bis (aminomethyl) cyclohexane], diaminobicycloheptane, diaminomethylbicyclo Heptane (including norbornanediamines such as norbornanediamine), diaminooxybicycloheptane, diaminomethyloxybicycloheptane (including oxanorbornanediamine), isophoronediamine, diaminotricyclodecane, diaminomethyltricyclodecane, bis (aminocyclohexane) Xyl) methane [or methylenebis (cyclohexylamine)], bis (aminocyclohexyl) isopropylidene and the like.

一般式（Ｇ）及び（Ｈ）中、Ｒ^６及びＲ^８はそれぞれ独立に、炭素数４〜２７の４価の基を示す。Ｒ^６及びＲ^８はそれぞれ独立に脂肪族基；単環式脂肪族基；縮合多環式脂肪族基；単環式芳香族基；もしくは縮合多環式芳香族基；環式脂肪族基が直接もしくは架橋員により相互に連結された非縮合多環式脂肪族基；芳香族基が直接もしくは架橋員により相互に連結された非縮合多環式芳香族基でありうる。具体的には、上述の一般式（ａ）で表されるテトラカルボン酸二無水物におけるＲ^１と同様である。3-1-3. Preferred polyimide precursor The polyimide precursor contained in the polyimide precursor-containing solution is not particularly limited as long as the tetracarboxylic acid component (A) and the diamine component (B) described above are reacted, The polyimide precursor is represented by a polyamic acid block (represented by the following general formula (G)) of a tetracarboxylic dianhydride represented by the general formula (a) and a diamine represented by the general formula (b-1). ), A tetracarboxylic dianhydride represented by the general formula (a), and a diamine polyimide represented by the general formula (b-2), (b-3), or (b-4) The block polyamic acid imide which the block (represented by the following general formula (H)) couple | bonded is preferable.

In general formulas (G) and (H), R ⁶ and R ⁸ each independently represents a tetravalent group having 4 to 27 carbon atoms. R ⁶ and R ⁸ are each independently an aliphatic group; a monocyclic aliphatic group; a condensed polycyclic aliphatic group; a monocyclic aromatic group; or a condensed polycyclic aromatic group; A non-condensed polycyclic aliphatic group directly or linked to each other by a bridging member; a non-fused polycyclic aromatic group whose aromatic groups are linked to each other directly or by a bridging member. Specifically, it is the same as R ¹ in the tetracarboxylic dianhydride represented by the general formula (a).

In the general formula (H), R ⁷ represents a divalent group having 4 to 51 carbon atoms. R ⁷ represents an aliphatic group; a monocyclic aliphatic group (excluding a 1,4-cyclohexylene group); a condensed polycyclic aliphatic group; a monocyclic aromatic group or a condensed polycyclic aromatic group; A non-condensed polycyclic aliphatic group in which the cycloaliphatic groups are linked to each other directly or via a bridging member; may be a non-fused polycyclic aromatic group in which the aromatic groups are linked to each other directly or by a bridging member . Specifically, it may be the same as R ′ of the diamine represented by the general formula (b-4) or a group represented by the following general formula (X) or (Y).

R ⁷ in the general formula (H) is particularly preferably a norbornane (a group represented by the above general formula (Y)). That is, the polyimide block represented by the general formula (H) is preferably a polyimide block containing a diamine represented by the general formula (b-2).

  M and n in Formula (G) and Formula (H) indicate the number of repeating structural units in each block. The average value of m and the average value of n are each independently preferably 2 to 1000, and more preferably 5 to 500.

  The ratio of m and n is preferably an average value of m: an average value of n = 9: 1 to 1: 9, and an average value of m: an average value of n = 8: 2 to 2: 8. Is more preferable. When the ratio of the repeating number m of the repeating structural unit represented by the formula (G) is a certain value or more, the thermal expansion coefficient of the obtained polyimide film becomes small. Moreover, the visible light transmittance | permeability of the polyimide film obtained as the ratio of repetition number m is more than fixed is increased. On the other hand, since cyclohexanediamine is generally expensive, reducing the ratio of the number m of repeating structural units represented by the formula (G) can reduce the cost.

  The ratio of the total number of repeating structural units represented by the formula (G) and the total number of repeating structural units represented by the formula (H) contained in the block polyamic acid imide that can be a polyimide precursor is (G) : (H) = 9: 1 to 1: 9 is preferable, and (G) :( H) = 8: 2 to 2: 8 is more preferable.

3-2. Solvent The solvent contained in the polyimide precursor-containing solution is not particularly limited as long as it is a solvent that can dissolve the tetracarboxylic acid component (A) and the diamine component (B). For example, it may be an aprotic polar solvent or a water-soluble alcohol solvent.

  Examples of aprotic polar solvents include N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoramide, 1,3-dimethyl-2-imidazo Lidinone, etc .; ether compounds such as 2-methoxyethanol, 2-ethoxyethanol, 2- (methoxymethoxy) ethoxyethanol, 2-isopropoxyethanol, 2-butoxyethanol, tetrahydrofurfuryl alcohol, diethylene glycol, diethylene glycol monomethyl ether , Diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monoethyl ether, tetraethylene glycol, 1-methoxy-2-propanol, 1-eth Xyl-2-propanol, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, polyethylene glycol, polypropylene glycol, tetrahydrofuran, dioxane, 1,2-dimethoxyethane, diethylene glycol dimethyl ether, diethylene glycol Diethyl ether and the like are included.

  Examples of water-soluble alcohol solvents include methanol, ethanol, 1-propanol, 2-propanol, tert-butyl alcohol, ethylene glycol, 1,2-propanediol, 1,3-propanediol, and 1,3-butanediol. 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 2-butene-1,4-diol, 2-methyl-2,4-pentanediol, 1,2,6-hexane Triol, diacetone alcohol and the like are included.

  The polyimide precursor-containing solution may contain only one kind of these solvents, or may contain two or more kinds. The solvent preferably contains N, N-dimethylacetamide, N-methyl-2-pyrrolidone, or a mixture thereof.

3-3. Release agent The release agent may be contained in the polyimide precursor containing solution. The release agent contained in the polyimide precursor-containing solution is not particularly limited as long as the release property between the support substrate and the transparent polyimide layer can be improved, and may be a known internal release agent. Examples of the internal release agent include aliphatic alcohols, fatty acid esters, triglycerides, fluorine surfactants, higher fatty acid metal salts, and phosphate ester release agents. From the viewpoint that the transparency of the transparent polyimide layer to be obtained is hardly hindered, it is preferably a phosphate ester release agent. Examples of the phosphoric ester release agent include compounds described in JP-A No. 2000-256377.

  The amount of the release agent contained in the polyimide precursor-containing solution is preferably 0.01 to 0.38 parts by mass, more preferably 100 parts by mass of the polyimide precursor contained in the polyimide precursor-containing solution. It is 0.02-0.30 mass part, More preferably, it is 0.04-0.20 mass part. When the amount of the release agent is less than 0.01 parts by mass, the peel strength when the transparent polyimide layer is peeled off from the support substrate is increased. On the other hand, when the amount of the release agent exceeds 0.38 parts by mass, it becomes difficult to apply the polyimide precursor-containing solution on the support substrate.

3-4. Other Additives As described above, the polyimide precursor-containing solution may contain various additives as long as the transparency and heat resistance of the obtained transparent polyimide layer are not impaired. Examples of various additives include antioxidants, heat stabilizers, antistatic agents, flame retardants, and ultraviolet absorbers.

3-5. Preparation Method of Polyimide Precursor-Containing Solution The polyimide precursor-containing solution is obtained by reacting the aforementioned tetracarboxylic acid component (A) and the aforementioned diamine component (B) in the aforementioned solvent. When the number of moles of the diamine component (B) in the solvent is x and the number of moles of the tetracarboxylic acid component (A) is y, y / x is preferably 0.9 to 1.1, 0.95 -1.05 is more preferable, 0.97-1.03 is further more preferable, and 0.99-1.01 is particularly preferable. By polymerizing the tetracarboxylic acid component (A) and the diamine component (B) at such a ratio, the molecular weight (polymerization degree) of the polyimide precursor can be appropriately adjusted.

  The procedure for the polymerization reaction is not particularly limited. For example, first, a container equipped with a stirrer and a nitrogen introduction tube is prepared. A solvent described later is put into a nitrogen-substituted container, diamine is added so that the solid content concentration of the obtained polyimide precursor is 50% by mass or less, and the temperature is adjusted, followed by stirring and dissolution. To this solution, the tetracarboxylic acid component (A) is added so that the molar ratio is 1 with respect to the diamine component (B), the temperature is adjusted, and the polyimide precursor is stirred for about 1 to 50 hours. The polyimide precursor containing solution to contain can be obtained.

  When the polyimide precursor is a block polyamic acid imide, for example, a polyamic acid imide may be generated by adding an acid anhydride-terminated polyimide solution to an amine-terminated polyamic acid solution and stirring. The polyamic acid diamine unit preferably contains a cyclohexane-containing diamine (the diamine represented by the general formula (b-1) or (b-3) described above); the polyimide diamine unit contains a cyclohexane-containing diamine. It is preferable that other diamines (diamines represented by the general formula (b-2) or (b-4) described above) are included. This is because polyimide having a structure containing cyclohexane (diamine represented by (b-1) or (b-3)) may be difficult to dissolve in a solvent. Polyamic acid is produced by the method described above. Moreover, a mold release agent is added suitably as needed.

4). Regarding the transparent polyimide layer The total light transmittance of the transparent polyimide layer in the transparent polyimide laminate obtained by the above-described method is 80% or more, more preferably 83% or more, and further preferably 85% or more. If the total light transmittance is 80% or more, the transparent polyimide layer can be applied to applications requiring transparency. The total light transmittance of the transparent polyimide layer is adjusted by the kind of polyimide, the oxygen concentration of the atmosphere in the above-described step b), the pressure, and the like. In particular, by reducing the oxygen concentration of the atmosphere in the temperature range exceeding 200 ° C. in step b) or lowering the pressure of the atmosphere, the oxidation of the polyimide is suppressed and the total light transmittance of the transparent polyimide layer is increased. The total light transmittance is measured with the light source D65 according to JIS-K7105 for the transparent polyimide layer after peeling the transparent polyimide layer from the support substrate.

  The in-plane retardation of the transparent polyimide layer in the transparent polyimide laminate is 10 nm or less, preferably 5 nm or less, more preferably 3 nm or less. If the in-plane retardation of the transparent polyimide layer is 10 nm or less, the transparent polyimide layer can be applied to a panel substrate of a flexible display device. If imidization partially proceeds after the completion of the above-mentioned step b) or if the solvent is volatilized, the in-plane retardation tends to increase. Therefore, in order to reduce the in-plane retardation, it is preferable to sufficiently increase the imidization ratio at the end of the above-mentioned step b) and to sufficiently reduce the amount of residual solvent at the end of step b). The in-plane retardation is a value measured with a photoelastic constant measuring device with light of 25 ° C. and wavelength of 550 nm. Specifically, the transparent polyimide layer is peeled from the support substrate, the refractive index of the transparent polyimide layer is measured with a photoelastic constant measuring device, the direction in which the refractive index is maximum is the X axis, and the direction perpendicular to the X axis Is the Y axis. When the refractive index in the X-axis direction is nx, the refractive index in the Y-axis direction is ny, and the thickness of the transparent polyimide layer is d, the value represented by (nx−ny) × d is the in-plane retardation. And

  The glass transition temperature (Tg) of the transparent polyimide layer in the transparent polyimide laminate is 260 ° C. or higher, preferably 270 ° C. or higher, more preferably 300 ° C. or higher. When the glass transition temperature of the transparent polyimide layer is 260 ° C. or higher, the transparent polyimide layer can be applied to applications requiring high heat resistance. For example, the process temperature for forming an electronic element is generally 250 ° C., and the transparent polyimide layer obtained by the present invention can be applied to a panel substrate of an apparatus including such an electronic element. The glass transition temperature of the transparent polyimide layer is adjusted by, for example, the equivalent of the imide group contained in the polyimide, the structure of the diamine component or tetracarboxylic dianhydride component constituting the polyimide, and the like. The glass transition temperature is measured with a thermomechanical analyzer (TMA).

  The haze of the transparent polyimide layer in the transparent polyimide laminate is 5% or less, preferably 3% or less, and more preferably 1% or less. When the haze of the transparent polyimide layer is 5% or less, the transparent polyimide layer can be applied to various optical films. The haze of the transparent polyimide layer is adjusted by the heating conditions of the polyimide precursor-containing solution, the crystallinity of the polyimide, the surface roughness of the support substrate, and the like.

  Further, in the transparent polyimide laminate, the absolute value of the b value represented by the L * a * b color system of the transparent polyimide layer is 5 or less, preferably 3 or less. On the other hand, the b value is preferably a positive value (0 or more). The L * a * b color system is standardized in JIS Z 8729. When the b value is a positive value, the transparent polyimide layer is yellowish, and when the b value is a negative value, the transparent polyimide layer is bluish. A general polyimide film has a large b value and is often yellow or brown. On the other hand, the transparent polyimide layer in the transparent polyimide laminate of the present invention has an absolute value of b value of 5 or less and is less colored. Therefore, the polyimide layer can be applied to various display substrates.

  The thickness of the transparent polyimide layer in the transparent polyimide laminate is not particularly limited, but is preferably 5 to 100 μm, and more preferably 10 to 50 μm. When the transparent polyimide layer has such a thickness, it can be used as a substrate for various flexible devices.

  Here, the present invention has a glass transition temperature of 260 ° C. or higher, a total light transmittance of 80% or higher, a haze of 5% or lower, an absolute value of b value in the L * a * b color system of 5 or lower, and a surface. A polyimide film having an internal retardation of 10 nm or less is also provided. It is preferable that the said polyimide film consists of a transparent polyimide layer obtained with the manufacturing method of the above-mentioned transparent polyimide laminated body. Furthermore, it is preferable that the physical property of the said polyimide film is the same range as the above-mentioned polyimide layer.

B. About the use of a transparent polyimide laminated body The transparent polyimide film obtained by peeling the transparent polyimide layer of the above-mentioned transparent polyimide laminated body from a support base material is applicable to the board | substrate and optical film of various flexible devices. Moreover, since the transparent polyimide film has a high total light transmittance and a very small in-plane retardation, it is particularly suitable for a flexible display substrate. Examples of the flexible display include a touch panel, a liquid crystal display, and an organic EL display.

  A touch panel is generally a panel body composed of (i) a transparent substrate having a transparent electrode (detection electrode layer), (ii) an adhesive layer, and (iii) a transparent substrate having a transparent electrode (drive electrode layer). . The above-mentioned transparent polyimide film can be applied to both the transparent substrate on the detection electrode layer side and the transparent substrate on the drive electrode layer side.

  In addition, the liquid crystal cell of the liquid crystal display device is usually a laminate in which (i) a first transparent plate, (ii) a liquid crystal material sandwiched between transparent electrodes, and (iii) a second transparent plate are laminated in this order. A panel body having a structure. The aforementioned transparent polyimide film can be applied to both the first transparent plate and the second transparent plate. The transparent polyimide film described above can also be applied to a substrate for a color filter in a liquid crystal display device.

  The organic EL panel is usually a panel in which a transparent substrate, an anode transparent electrode layer, an organic EL layer, a cathode reflective electrode layer, and a counter substrate are laminated in this order. The transparent polyimide film described above can be applied to both the transparent substrate and the counter substrate.

  The transparent polyimide layer (transparent polyimide film) of the above-mentioned transparent polyimide laminate is easily peeled from the support substrate. Therefore, when obtaining a flexible display, the transparent polyimide layer may be peeled off, and then an element may be formed on the transparent polyimide layer. After forming the element on the transparent polyimide layer, the transparent polyimide layer is supported on the support substrate. You may peel from.

  When the transparent polyimide layer is peeled off from the supporting substrate, there is a possibility that foreign matters are adsorbed on the transparent polyimide layer due to peeling charging, or the element may be damaged. Therefore, it is preferable to take measures to prevent charging of the transparent polyimide laminate. Specifically, (a) an antistatic agent is added to a polyimide precursor-containing solution, (b) an antistatic agent is coated on a support substrate, (c) a polyimide precursor-containing solution coating apparatus or a transparent polyimide layer It is preferable to install a static eliminating member (for example, a neutralizing bar, a neutralizing yarn, an ion blowing static eliminating device, etc.) on the peeling device. Only one type of these measures may be taken, or a plurality of measures may be taken.

  The following three methods are included in the method of forming an element on the transparent polyimide layer. In any method, a method for forming an element is not particularly limited, and may be a known method.

(I) 1st method The 1st method peels transparent polyimide film (transparent polyimide layer) 1 'from the support base material 11 in the transparent polyimide laminated body 12, as shown by the schematic sectional drawing of FIG. After that (FIG. 2A), the element 13 is formed on the transparent polyimide film 1 ′ (FIG. 2B). In the first method, the element 13 can be formed on the transparent polyimide film 1 ′ after the peeled transparent polyimide film 1 ′ is bonded to another substrate (not shown).

(Ii) Second Method As shown in the schematic cross-sectional view of FIG. 3, the second method is to form the element 13 on the transparent polyimide layer 1 ′ laminated with the support base 11 (FIG. 3 ( a)), a transparent polyimide film (transparent polyimide layer) 1 ′ is peeled from the support substrate 11 (FIG. 3B), and a transparent polyimide film 1 ′ having an element 13 formed thereon is obtained (FIG. 3). (C)). In the second method, the stress applied to the transparent polyimide layer 1 ′ when the element 13 is formed is easily absorbed by the support base material 11. Therefore, it is difficult for the transparent polyimide layer 1 ′ to tear or break when the element 13 is formed.

(Iii) Third Method As shown in the schematic cross-sectional view of FIG. 4, the third method is performed after the supporting base material 11 side of the transparent polyimide laminate 12 is bonded to another substrate 14 (FIG. 4 ( a)), various elements 13 are formed on the transparent polyimide layer 1 ′ (FIG. 4B), and the transparent polyimide film (transparent polyimide layer) 1 ′ is peeled from the support substrate 11 (FIG. 4C). ), And a method of obtaining a polyimide film 1 ′ on which the element 13 is formed (FIG. 4D). In the third method, since the other substrate 14 is bonded to the transparent polyimide laminate 12, the transparent polyimide laminate 12 does not bend when the element 13 is manufactured. Therefore, the element 13 can be formed on the transparent polyimide layer 1 ′ by various methods. Also in the third method, the stress applied to the transparent polyimide layer 1 ′ during the formation of the element 13 is easily absorbed by the support base material 11. Therefore, it is difficult for the transparent polyimide layer 1 ′ to tear or break when the element 13 is formed.

  The other substrate 14 to be bonded to the transparent polyimide laminate 12 is not particularly limited as long as it is a rigid substrate, and may be a glass substrate, a metal substrate, a ceramic substrate, a resin substrate, or the like. The bonding method between the support base 11 of the transparent polyimide laminate 12 and the other substrate 14 is not particularly limited, and may be a method of bonding with an adhesive or the like, for example.

5. Others The method for producing a polyimide laminate described above can also be applied to a method for producing a resin laminate having a support base and various resin layers. Specifically, it is set as the manufacturing method of a resin laminated body which has the process of (a) apply | coating the varnish containing various resin on a support base material, and (b) heat-hardening the coating film of the said varnish. Can do. According to the method for producing the resin laminate, a resin film that can be easily peeled off from the support substrate is obtained. Examples of various resins include polyimide resins (polyimide precursors) other than those described above, aramid resins, polyether ether ketone resins, and polyether sulfone resins.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited by this. In Examples and Comparative Examples, peel strength, imidization ratio, residual amount of solvent, glass transition temperature, total light transmittance, haze value, b value in L * a * b color system, in-plane retardation, and support The ten-point average roughness of the substrate was measured by the following method.

1) Peel strength The transparent polyimide laminates produced in the examples and comparative examples were cut into a length of 50 mm and a width of 3.5 mm. The peel strength of this transparent polyimide laminate was measured according to the method specified in JIS C-6471. Specifically, the edge of the short side of the transparent polyimide laminate was gripped, peeled from the support substrate at a peeling angle of 90 °, and a peeling speed of 50 mm / min, and the stress at the time of peeling was measured. The stress was measured with a tensile tester EZ-S manufactured by Shimadzu Corporation and an adhesive tape peeling tester.

2) Imidization rate The transparent polyimide layer was peeled off from the transparent polyimide laminates prepared in Examples and Comparative Examples, and the imidization rate of the transparent polyimide layer was calculated as follows. The IR absorption spectrum was measured by attaching a multiple reflection infrared spectrum measuring device (ATR PR0410-M manufactured by JASCO Corporation) to an FT-IR spectrometer (FT / IR 300E manufactured by JASCO Corporation). .

About the transparent polyimide layer produced by the Example and the comparative example, IR absorption spectrum was measured, respectively. For each film, the absorption peak height of 1370 cm ⁻¹ (CN stretching vibration of imide ring) with respect to the absorption peak height of 1500 cm ⁻¹ (peak (reference) due to C = C stretching vibration of benzene ring). The ratio A was calculated. On the other hand, a transparent polyimide layer was prepared in the same manner as in each Example and Comparative Example, and this was heated at 270 ° C. for 2 hours or longer to completely imidize. About these films, IR absorption spectrum was measured, respectively, and the absorption peak height of 1370 cm ⁻¹ with respect to the absorption peak height of 1500 cm ⁻¹ (peak (reference) due to C = C stretching vibration of the benzene ring) in the same manner as described above. The ratio B (CN stretching vibration of imide ring) was calculated.
And the value of the ratio A (ratio A / ratio B) x 100 (%) with respect to the ratio B of the corresponding film was determined, and this was defined as the imidization rate.

3) Residual amount of solvent The transparent polyimide layer was peeled from the transparent polyimide laminates produced in Examples and Comparative Examples, and the residual amount of solvent in the transparent polyimide layer was measured. The measurement is performed using an electric furnace type pyrolysis furnace (Shimadzu PYR-2A (pyrolysis temperature 320 ° C.)) and a gas chromatograph mass spectrometer (Shimadzu GC-8A (column Uniport HP 80/100 KG-02)). And the amount of solvent contained in the film was specified. At this time, the injector and detector temperatures of the apparatus were 200 ° C., and the column temperature was 170 ° C.

4) Total light transmittance The transparent polyimide layer was peeled from the transparent polyimide laminates prepared in Examples and Comparative Examples, and the total light transmittance of the transparent polyimide layer was measured. Specifically, according to JIS-K-7105, it measured with the light source D65 in Nippon Denshoku Industries haze meter NDH2000.

5) Haze The transparent polyimide layer was peeled from the transparent polyimide laminates produced in Examples and Comparative Examples, and the haze of the transparent polyimide layer was measured. Specifically, according to JIS-K-7105, it measured with the light source D65 in Nippon Denshoku Industries haze meter NDH2000.

6) b value The transparent polyimide layer was peeled from the transparent polyimide laminates produced in the examples and comparative examples, and the b value of the transparent polyimide layer was measured. For the measurement, a color difference meter (measuring head: CM-2500d, manufactured by Konica Minolta Co., Ltd.) was used, and the b value of the transparent polyimide layer was measured three times on a calibration white plate with a C light source, 2 °, field of view, and SCI mode. Measured. The b value was an average value of three measurement values.

7) In-plane retardation R0
The transparent polyimide layer was peeled from the transparent polyimide laminate produced in the examples and comparative examples. The in-plane retardation of the transparent polyimide layer was measured by X, Y mode of a photoelastic constant measuring device PEL-3A-102C manufactured by Uniopt. The measurement temperature was 25 ° C., and the measurement wavelength was 550 nm. Specifically, the refractive index of the polyimide film is measured with a photoelastic constant measuring device, the direction in which the refractive index is maximum is the X axis, the direction perpendicular to the X axis is the Y axis, and the refractive index nx in the X axis direction. And a refractive index ny in the Y-axis direction. And when the thickness of the film was set to d, the value represented by (nx-ny) * d was made into the in-plane phase difference.

8) Ten-point average roughness of supporting substrate The ten-point average roughness of the supporting substrates used in Examples and Comparative Examples was measured according to JIS B0601. At this time, with a cut-off value of 0.25 mm and a measurement length of 2.5 mm, the ten-point average roughness in the width direction of the support substrate was measured with a surface roughness / contour shape measuring machine (Surfcom 1400D manufactured by Tokyo Seimitsu). .

Abbreviations of compounds used in Examples and Comparative Examples are as follows.
[Diamine component]
14BAC: 1,4-bis (aminomethyl) cyclohexane NBDA: norbornanediamine ODA: 4,4′-diaminodiphenyl ether CHDA: trans-1,4-cyclohexanediamine [tetracarboxylic acid component]
PMDA: pyromellitic dianhydride BPDA: 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride [solvent]
DMAc: N, N-dimethylacetamide NMP: N-methyl-2-pyrrolidone

(Synthesis Example 1)
To a 300 mL five-necked separable flask equipped with a thermometer, a stirrer, and a nitrogen inlet tube, 149.4 g (3.3 mol) of 14BAC and 5761 g of DMAc were added and stirred. To this mixed solution, 970.9 g (3.3 mol) of powdery BPDA was added. After the addition of BPDA, the reaction vessel was bathed in an oil bath maintained at 120 ° C. for 5 minutes. About 3 minutes after the addition of BPDA, the salt precipitated, but then dissolved rapidly. This mixed solution was further stirred at room temperature for 18 hours to obtain a polyimide precursor-containing solution.

(Synthesis Example 2)
PMDA 39.7 g (0.180 mol) and DMAc 130 g were added to a 300 mL 5-neck separable flask equipped with a thermometer, a stirrer, a nitrogen inlet tube and a dropping funnel, and the PMDA slurry was stirred. Obtained. On the other hand, a mixed solution of 27.8 g (0.180 mol) of NBDA and 27.8 g of DMAc was prepared. This mixed solution was dropped into the slurry over 120 minutes while keeping the temperature constant. Thereafter, the mixed solution was stirred at 50 ° C. for 5 hours to obtain a polyimide precursor-containing solution.

(Synthesis Example 3)
To a 300 mL five-necked separable flask equipped with a thermometer, a stirrer, and a nitrogen inlet tube were added 14.1 g (0.099 mol) of 14BAC, 1.7 g (0.011 mol) of NBDA, and 189 g of DMAc. Stir. To this mixed solution, 29.1 g (0.099 mol) of powdery BPDA and 2.4 g (0.011 mol) of PMDA were added. After the addition of BPDA and PMDA, the reaction vessel was bathed in an oil bath maintained at 120 ° C. for 5 minutes. About 3 minutes after the addition of BPDA and PMDA, a salt precipitated, but then it quickly dissolved. This mixed solution was further stirred at room temperature for 18 hours to obtain a polyimide precursor-containing solution.

(Synthesis Example 4)
In a 300 mL five-necked separable flask equipped with a thermometer, a stirrer, and a nitrogen inlet tube, 10.0 g (0.050 mol) of ODA and 119 g of DMAc were added and stirred. To this mixed solution, 10.9 g (0.050 mol) of powdery PMDA was added while keeping the temperature constant. Thereafter, the mixed solution was stirred at 50 ° C. for 5 hours to obtain a polyimide precursor-containing solution.

(Synthesis Example 5)
Synthesis of amic acid oligomer solution To a 300 mL five-necked separable flask equipped with a thermometer, a stirrer, and a nitrogen inlet tube, 11.4 g (0.100 mol) of CHDA and 116 g of NMP as a solvent were added. Stir until clear. To this solution, 27.1 g (0.092 mol) of BPDA was charged in powder form, and the reaction vessel was bathed in an oil bath maintained at 120 ° C. for 5 minutes. Some time after the BPDA was charged, salt precipitated. Thereafter, the salt dissolved and became homogeneous and the viscosity of the solution increased. After removing the oil bath, the mixture was further stirred at room temperature for 18 hours to obtain an amic acid oligomer solution having an amino group derived from CHDA at the terminal.

・ Synthesis of imide oligomer solution To a 300 mL 5-neck separable flask equipped with a thermometer, a stirrer, and a nitrogen inlet tube, 11.1 g (0.072 mol) of NBDA and 94.5 g of NMP were added, and the solution was transparent. Stir until. To the solution, 29.4 g (0.100 mol) of BPDA was charged in a powder form, and the reaction vessel was bathed in an oil bath maintained at 120 ° C. for 5 minutes. After the BPDA was charged, salt temporarily precipitated. Thereafter, it was confirmed that the solution was re-dissolved with increasing viscosity and became a uniform transparent solution.
A cooling tube and a Dean-Stark type concentrator were attached to the separable flask, 80.0 g of xylene was added to the reaction solution, and dehydration thermal imidization reaction was performed at 180 ° C. for 4 hours while stirring. After the reaction, xylene was distilled off to obtain an imide oligomer solution having an acid anhydride structure derived from BPDA at the end.

-Synthesis | combination of block polyamic-acid imide solution The above-mentioned amic acid oligomer solution 40.0g and the above-mentioned imide oligomer solution 9.99g are mixed, and a high-viscosity material stirring defoaming mixer (The product made by Japan Unix Co., Ltd., product name: UM-118) was stirred for 10 minutes to obtain a block polyamic acid imide solution.

Example 1
The polyimide precursor-containing solution prepared in Synthesis Example 1 was applied with a doctor blade onto a Ube Industries polyimide film (UPILEX 50S (50 μm)) fixed to a glass substrate with Kapton tape. And the sample which consists of a glass substrate, a support base material, and a polyimide precursor film was put into inert oven. Thereafter, the oxygen concentration in the inert oven is controlled to 0.0%, the temperature is increased from 30 ° C. to 270 ° C. over 120 minutes (temperature increase rate: 2 ° C./min), and further maintained at 270 ° C. for 2 hours. A transparent polyimide laminate was produced on the substrate. The thickness of the obtained transparent polyimide layer was 30 μm.
The peel strength of the support base / transparent polyimide layer interface of the transparent polyimide laminate removed from the glass substrate was 0.039 kN / m.
The glass transition temperature (Tg) of the transparent polyimide film after peeling is 260 ° C., the total light transmittance is 87%, the in-plane retardation (R0) is 0.8 nm, the imidization rate is 98%, and the residual solvent amount is It was 0.2% by mass.

(Example 2)
A transparent polyimide laminate was produced on a glass substrate in the same manner as in Example 1 except that the oxygen concentration in the inert oven was changed to 5.0%. The peel strength of the support base / transparent polyimide layer interface of the transparent polyimide laminate removed from the glass substrate was 0.039 kN / m.
The glass transition temperature (Tg) of the transparent polyimide film after peeling is 261 ° C., the total light transmittance is 87%, the in-plane retardation (R0) is 0.8 nm, the imidization rate is 98%, and the residual solvent amount is It was 0.2% by mass.

(Example 3)
A transparent polyimide laminate was produced on a glass substrate in the same manner as in Example 1 except that the heating rate was changed to 10 ° C./min. The peel strength of the support base / transparent polyimide layer interface of the transparent polyimide laminate removed from the glass substrate was 0.032 kN / m.
The glass transition temperature (Tg) of the transparent polyimide film after peeling is 260 ° C., the total light transmittance is 87%, the in-plane retardation (R0) is 0.7 nm, the imidization rate is 95%, and the residual solvent amount is It was 0.5 mass%.

Example 4
A transparent polyimide laminate was produced on a glass substrate in the same manner as in Example 3 except that the maximum temperature of the inert oven was changed to 280 ° C. and the rate of temperature increase was 2 ° C./min. The peel strength of the support base / transparent polyimide layer interface of the transparent polyimide laminate removed from the glass substrate was 0.040 kN / m.
The transparent polyimide film after peeling has a glass transition temperature (Tg) of 261 ° C., a total light transmittance of 86%, an in-plane retardation (R0) of 0.7 nm, an imidization rate of 100%, and a residual solvent detected. Was not.

(Example 5)
The polyimide precursor-containing solution prepared in Synthesis Example 1 was applied with a doctor blade onto a Ube Industries polyimide film (UPILEX50S) fixed to a glass substrate with Kapton tape. And the sample which consists of a glass substrate, a support base material, and a polyimide precursor film was put into inert oven. Thereafter, the oxygen concentration in the inert oven was controlled to 20%, the temperature was raised from 30 ° C. to 180 ° C. over 75 minutes (temperature increase rate 2 ° C./min), and further maintained at 180 ° C. for 2 hours. Thereafter, the sample was transferred to a vacuum oven, and the temperature was increased after the vacuum was reduced to 1 kPa or less with full vacuum. The vacuum oven was heated from 30 ° C. to 270 ° C. over 60 minutes (temperature increase rate: 4 ° C./min), and further maintained at 270 ° C. for 1 hour to produce a transparent polyimide laminate on the glass substrate.
The peel strength of the support base / transparent polyimide layer interface of the transparent polyimide laminate removed from the glass substrate was 0.031 kN / m.
The glass transition temperature (Tg) of the transparent polyimide film after peeling is 260 ° C., the total light transmittance is 86%, the in-plane retardation (R0) is 0.5 nm, the imidization rate is 96%, and the residual solvent amount is It was 0.7 mass%.

(Example 6)
The polyimide precursor-containing solution prepared in Synthesis Example 2 was applied with a doctor blade onto a Ube Industries polyimide film (UPILEX50S) fixed to a glass substrate with Kapton tape. And the sample which consists of a glass substrate, a support base material, and a polyimide precursor film was put into inert oven. Thereafter, the oxygen concentration in the inert oven is controlled to 0.0%, the temperature is increased from 30 ° C. to 300 ° C. over 135 minutes (temperature increase rate: 2 ° C./min), and further maintained at 300 ° C. for 2 hours. A transparent polyimide laminate was produced on the substrate.
The peel strength of the support base / transparent polyimide layer interface of the transparent polyimide laminate removed from the glass substrate was 0.029 kN / m.
The glass transition temperature (Tg) of the transparent polyimide film after peeling is 290 ° C., the total light transmittance is 88%, the in-plane retardation (R0) is 0.3 nm, the imidization rate is 98%, and the residual solvent amount is It was 0.6 mass%.

(Example 7)
A transparent polyimide laminate was produced on a glass substrate in the same manner as in Example 1 except that the polyimide precursor-containing solution to be used was changed to that prepared in Synthesis Example 3 and the temperature increase rate was 2 ° C./min. The peel strength of the support base / transparent polyimide layer interface of the transparent polyimide laminate removed from the glass substrate was 0.041 kN / m.
The glass transition temperature (Tg) of the transparent polyimide film after peeling is 266 ° C., the total light transmittance is 88%, the in-plane retardation (R0) is 0.6 nm, the imidization rate is 96%, and the residual solvent amount is It was 0.3% by mass.

(Reference Example 1)
The polyimide precursor-containing solution prepared in Synthesis Example 1 was coated on a Tokai aluminum aluminum foil (50 μm) fixed to a glass substrate with Kapton tape with a doctor blade. And the sample which consists of a glass substrate, a support base material, and a polyimide precursor film was put into inert oven. Thereafter, the oxygen concentration in the inert oven is controlled to 0.0%, the temperature is increased from 30 ° C. to 270 ° C. over 120 minutes (temperature increase rate: 2 ° C./min), and further maintained at 270 ° C. for 2 hours. A transparent polyimide laminate was produced on the substrate. The peel strength of the support base / transparent polyimide layer interface of the transparent polyimide laminate removed from the glass substrate was 0.19 kN / m.
The glass transition temperature (Tg) of the transparent polyimide film after peeling is 261 ° C., the total light transmittance is 85%, the in-plane retardation (R0) is 1.4 nm, the imidization rate is 99%, and the residual solvent amount is It was 0.1 mass%.

(Reference Example 2)
Implemented except that 100 g of the polyimide precursor-containing solution prepared in Synthesis Example 1 was mixed with 0.01 g of DuPont release agent Zelec UN (corresponding to 500 ppm with respect to the solid content) and the release component-containing polyimide precursor-containing solution was used. In the same manner as in Example 8, a transparent polyimide laminate was produced on a glass substrate. The peel strength of the support base / transparent polyimide layer interface of the transparent polyimide laminate removed from the glass substrate was 0.007 kN / m.
The glass transition temperature (Tg) of the transparent polyimide film after peeling is 260 ° C., the total light transmittance is 85%, the in-plane retardation (R0) is 1.1 nm, the imidization rate is 99%, and the residual solvent amount is It was 0.1 mass%.

(Reference Example 3)
A transparent polyimide laminate was produced on a glass substrate in the same manner as in Example 9 except that the supporting substrate used was changed to SUS304 (50 μm). The peel strength of the support base / transparent polyimide layer interface of the transparent polyimide laminate removed from the glass substrate was 0.009 kN / m.
The glass transition temperature (Tg) of the transparent polyimide film after peeling is 262 ° C., the total light transmittance is 86%, the in-plane retardation (R0) is 1.2 nm, the imidization rate is 99%, and the residual solvent amount is It was 0.2% by mass.

(Example 8)
The polyimide precursor-containing solution prepared in Synthesis Example 1 was continuously and continuously cast onto a polyimide film (UPILEX 50S (50 μm)) manufactured by Ube Industries using a die coater, and the oxygen concentration was adjusted to 0.0%. Using a controlled drying furnace, the temperature was raised stepwise (corresponding to a heating rate of 5 ° C./min) and heated to a maximum temperature of 270 ° C. to produce a transparent polyimide laminate. The peel strength of the support base / transparent polyimide layer interface of the transparent polyimide laminate removed from the glass substrate was 0.039 kN / m.
The glass transition temperature (Tg) of the transparent polyimide film after peeling is 261 ° C., the total light transmittance is 87%, the in-plane retardation (R0) is 2.0 nm, the imidization rate is 97%, and the residual solvent amount is It was 0.8 mass%.

Example 9
The block polyamic acid imide solution prepared in Synthesis Example 5 was applied with a doctor blade onto a Ube Industries polyimide film (UPILEX 50S (50 μm, Rz = 0.03 μm)) fixed to a glass substrate with Kapton tape. And the sample which consists of a glass substrate, a support base material, and a block polyamic-acid imide film was put into inert oven. Thereafter, the oxygen concentration in the inert oven is controlled to 0.0%, the temperature is increased from 30 ° C. to 270 ° C. over 120 minutes (temperature increase rate: 2 ° C./min), and further maintained at 270 ° C. for 2 hours. A transparent polyimide laminate was produced on the substrate. The thickness of the transparent polyimide layer of the obtained transparent polyimide laminate was 30 μm. The peel strength of the support base / transparent polyimide layer interface of the transparent polyimide laminate removed from the glass substrate was 0.030 kN / m.
The glass transition temperature (Tg) of the transparent polyimide film after peeling is 286 ° C., the total light transmittance is 85%, the haze is 1.0%, the b value is 1.8, and the in-plane retardation (R0) is 0.9 nm. The imidation ratio was 98%, and the solvent residual amount was 0.5% by mass.

(Comparative Example 1)
The polyimide precursor-containing solution to be used was changed to that prepared in Synthesis Example 4, and the temperature was raised from 30 ° C. to 300 ° C. over 135 minutes (temperature increase rate 2 ° C./min), and kept at 300 ° C. for 2 hours. Made a transparent polyimide laminate on the glass substrate in the same manner as in Example 1. The peel strength of the support base / transparent polyimide layer interface of the transparent polyimide laminate removed from the glass substrate was 0.025 kN / m.
The glass transition temperature (Tg) of the transparent polyimide film after peeling was not detected, the total light transmittance was 78%, the in-plane retardation (R0) was 0.9 nm, the imidization rate was 95%, and the solvent remaining amount Was 0.9 mass%.

(Comparative Example 2)
A transparent polyimide laminate was produced on a glass substrate in the same manner as in Example 1 except that the oxygen concentration in the inert oven was changed to 10.0%. The peel strength of the support base / transparent polyimide layer interface of the transparent polyimide laminate removed from the glass substrate was 0.031 kN / m.
The glass transition temperature (Tg) of the transparent polyimide film after peeling is 259 ° C., the total light transmittance is 79%, the in-plane retardation (R0) is 0.8 nm, the imidization rate is 97%, and the residual solvent amount is It was 0.5 mass%.

(Comparative Example 3)
A transparent polyimide laminate was produced on a glass substrate in the same manner as in Example 1 except that the maximum temperature of the inert oven was changed to 230 ° C. The peel strength of the support base / transparent polyimide layer interface of the transparent polyimide laminate removed from the glass substrate was 0.010 kN / m.
The glass transition temperature (Tg) of the transparent polyimide film after peeling is 250 ° C., the total light transmittance is 90%, the in-plane retardation (R0) is 0.8 nm, the imidization rate is 78%, and the residual solvent amount is It was 3.0 mass%.

(Comparative Example 4)
A transparent polyimide laminate was produced on a glass substrate in the same manner as in Example 1 except that the supporting base used was changed to a copper foil (NA-DFF (12 μm)) manufactured by Mitsui Mining & Smelting. Although an attempt was made to peel off the transparent polyimide layer from the copper foil (support base material) of the transparent polyimide laminate removed from the glass substrate, it could not be removed.

(Comparative Example 5)
A release component-containing polyimide precursor-containing solution in which 0.10 g of DuPont release agent Zelec UN is mixed with 100 g of the polyimide precursor-containing solution prepared in Synthesis Example 1 (equivalent to 5000 ppm with respect to the solid content) is added to a glass substrate with Kapton tape. It was coated with a doctor blade on an aluminum foil (support base material: 50 μm) made of Tokai Aluminum fixed in (1). And the sample which consists of a glass substrate, a support base material, and a polyimide precursor film was put into inert oven. Thereafter, the oxygen concentration in the inert oven was controlled to 0.0%, the temperature was increased from 30 ° C. to 270 ° C. over 120 minutes (temperature increase rate 2 ° C./min), and further maintained at 270 ° C. for 2 hours. The transparent polyimide laminate taken out of the oven was confirmed to be difficult to form because the transparent polyimide layer was partially agglomerated by “repelling” on the support substrate.

(Comparative Example 6)
The polyimide precursor-containing solution prepared in Synthesis Example 1 was applied directly on a glass substrate with a doctor blade. And the sample which consists of a glass substrate and a polyimide precursor film was put into inert oven. Thereafter, the oxygen concentration in the inert oven is controlled to 0.0%, the temperature is increased from 30 ° C. to 270 ° C. over 120 minutes (temperature increase rate: 2 ° C./min), and further maintained at 270 ° C. for 2 hours. A transparent polyimide layer was produced on the substrate. The thickness of the obtained transparent polyimide layer was 30 μm.
Although an attempt was made to peel off the transparent polyimide layer from the glass substrate, it was difficult to peel off easily. Therefore, the glass substrate / transparent polyimide layer was immersed in distilled water to peel the transparent polyimide film from the glass substrate.
The glass transition temperature (Tg) of the transparent polyimide film after peeling is 260 ° C., the total light transmittance is 87%, the in-plane retardation (R0) is 0.8 nm, the imidization rate is 98%, and the residual solvent amount is It was 0.1 mass%.

(Comparative Example 7)
The polyimide precursor-containing solution prepared in Synthesis Example 1 was applied with a doctor blade onto a Ube Industries polyimide film (UPILEX50S (50 μm, Rz = 0.03 μm)) fixed to a glass substrate with Kapton tape. And the sample which consists of a glass substrate, a support base material, and a polyimide precursor film was put into inert oven. Thereafter, the oxygen concentration in the inert oven was controlled to 0.0%, the temperature was raised from 30 ° C. to 200 ° C. over 85 minutes (temperature increase rate: 2 ° C./min), and further maintained at 200 ° C. for 2 hours. The peel strength of the support base / transparent polyimide layer interface of the transparent polyimide laminate removed from the glass substrate was 0.008 kN / m.

  The transparent polyimide film after peeling was fixed to the stainless steel metal frame with Kapton tape all around. This was put into an inert oven, the oxygen concentration in the inert oven was controlled to 0.0%, and the temperature was increased from 30 ° C. to 250 ° C. over 110 minutes (temperature increase rate 2 ° C./min). And it hold | maintained at 250 degreeC for 2 hours, and obtained the transparent polyimide film with a film thickness of 30 micrometers. The glass transition temperature (Tg) of the obtained transparent polyimide film was 258 ° C., the total light transmittance was 87%, the haze was 3.7%, the b value was 0.9, the in-plane retardation (R0) was 80 nm, and the imide The conversion rate was 88%, and the residual solvent amount was 1.5% by mass.

(Comparative Example 8)
The polyimide precursor-containing solution prepared in Synthesis Example 1 was applied with a doctor blade onto a Ube Industries polyimide film (UPILEX50S (50 μm, Rz = 0.03 μm)) fixed to a glass substrate with Kapton tape. And the sample which consists of a glass substrate, a support base material, and a polyimide precursor film was put into inert oven. Thereafter, the oxygen concentration in the inert oven is controlled to 0.0%, the temperature is increased from 30 ° C. to 270 ° C. over 120 minutes (temperature increase rate: 2 ° C./min), and further maintained at 270 ° C. for 2 hours. A transparent polyimide laminate was produced on the substrate. The peel strength of the support base / transparent polyimide layer interface of the transparent polyimide laminate removed from the glass substrate was 0.039 kN / m.

  The peeled film was fixed to a stainless steel metal frame with Kapton tape all around. This is put into an inert oven, the oxygen concentration in the inert oven is controlled to 0.0%, the temperature is raised from 30 ° C. to 270 ° C. over 120 minutes (temperature rising rate 2 ° C./min), and further 2 at 270 ° C. Holding for a time, a transparent polyimide film having a thickness of 30 μm was obtained. The resulting transparent polyimide film had a glass transition temperature (Tg) of 260 ° C., a total light transmittance of 88%, a haze of 1.5%, a b value of 0.8, an in-plane retardation (R0) of 12 nm, and an imide. The conversion rate was 100%, and no solvent was detected.

  As shown in Table 1, when the polyimide precursor was heated at a temperature equal to or higher than the glass transition temperature of the obtained transparent polyimide layer (Examples 1 to 9, Reference Examples 1 to 3, Comparative Examples 2 and 6, and comparison) In Example 8), the residual solvent amount was 1.0% by mass or less, and the imidization ratio was 95% or more. On the other hand, when heated below the glass transition temperature of the transparent polyimide layer obtained (Comparative Example 3 and Comparative Example 7), the residual solvent amount is 3.0% by mass, and the imidization rate is less than 90%. The drying of the solvent and the imidization of the polyimide precursor were insufficient.

  In addition, in the case where polyimide films are obtained by heating to a temperature above the glass transition temperature on the supporting substrate (Examples 1 to 9, Reference Examples 1 to 3, and Comparative Examples 1, 2, and 6), an in-plane retardation is obtained. Was 10 nm or less. On the other hand, after heating below the glass transition temperature on the support substrate, the polyimide film is peeled off from the support substrate, and this is fixed to a metal frame and further heated (Comparative Example 7), or the support group After heating on the material above the glass transition temperature, the polyimide film is peeled off from the supporting substrate, fixed to a metal frame and further heated above the glass transition temperature (Comparative Example 8), in-plane retardation Was over 10 nm. If the in-plane retardation is more than 10 nm, the use as an optical film is limited.

When the support substrate is a polyimide film (Examples 1 to 9, Comparative Examples 1 to 3, 7, and 8), the peel strength when peeling the transparent polyimide layer from the support substrate is 0.041 kN / m or less, and the peelability of the transparent polyimide layer was good.
On the other hand, when the support substrate was an aluminum substrate, the peel strength when peeling the transparent polyimide layer from the support substrate was relatively high at 0.19 kN / m (Reference Example 1). On the other hand, even when the support substrate was an aluminum substrate, the peel strength was greatly reduced when a release agent was included in the polyimide precursor-containing solution (Reference Example 2). However, when there was too much quantity of a mold release agent, the polyimide precursor containing solution was not able to be apply | coated uniformly (comparative example 5). Moreover, when a SUS plate was used as a supporting base material and the release agent was contained in the polyimide precursor-containing solution, the peel strength when peeling the transparent polyimide layer from the supporting base material was low, and the peelability was good. (Reference Example 3).

  On the other hand, when the supporting base material is copper foil, and the release agent is not included in the polyimide precursor-containing solution (Comparative Example 4), the peel strength between the supporting base material and the transparent polyimide layer is high, and these can be peeled off. There wasn't. Moreover, when the support base material was a glass substrate (Comparative Example 6), the peel strength between the support base material and the transparent polyimide layer was high, and the transparent polyimide layer could not be peeled unless immersed in water.

  Further, when the supporting base material is an aluminum substrate, a SUS plate, or the like, the ten-point average roughness (Rz) of the surface of the supporting base material is rough, and the haze of the transparent polyimide layer formed on the supporting base material is increased. It was easy (Reference Examples 1-3).

  Moreover, when the alicyclic group was contained in the principal chain of polyimide, the total light transmittance was high (Examples 1-9, Reference Examples 1-3, and Comparative Examples 3, 6-8). In contrast, the wholly aromatic transparent polyimide film (Comparative Example 1) had a low total light transmittance. Moreover, even if the main chain of polyimide contains an alicyclic group, when the oxygen concentration during heating of the polyimide precursor-containing solution exceeds 5% by volume (Comparative Example 2), the total light transmittance is Declined. It is inferred that the polyimide was oxidized during heating and the film was yellowed.

  The transparent polyimide film obtained from the transparent polyimide laminate of the present invention has a high total light transmittance and a small in-plane retardation. Therefore, the present invention can be applied to various flexible display panel substrates such as a touch panel substrate, a color filter substrate, a liquid crystal cell substrate, and an organic EL display substrate.

DESCRIPTION OF SYMBOLS 1 Polyimide precursor film 1 'Transparent polyimide layer 10 Heating furnace 11 Support base material 12 Transparent polyimide laminated body 13 Element 14 Other board | substrates 20 Coating apparatus 21 Endless belt 30 Roll body

Claims (18)

A method for producing a transparent polyimide laminate comprising a support substrate and a transparent polyimide layer laminated on the support substrate,
a) a step of applying a polyimide precursor-containing solution containing a polyimide precursor obtained by reacting a tetracarboxylic acid component and a diamine component and a solvent onto the support substrate;
b) heating a polyimide precursor film comprising a coating film of the polyimide precursor-containing solution above the glass transition temperature of the transparent polyimide layer,
The transparent polyimide layer has a glass transition temperature of 260 ° C. or more, a total light transmittance of 80% or more, a haze of 5% or less, an absolute value of b value in the L * a * b color system of 5 or less, and an in-plane The phase difference is 10 nm or less,
The manufacturing method of the transparent polyimide laminated body whose peel strength at the time of peeling the said transparent polyimide layer from the said support base material is 0.005-0.20 kN / m.   The manufacturing method of the transparent polyimide laminated body of Claim 1 whose said support base material is a flexible base material.   The manufacturing method of the transparent polyimide laminated body of Claim 1 with which a mold release agent is further contained in the said polyimide precursor containing solution.   The manufacturing method of the transparent polyimide laminated body of Claim 1 which makes oxygen concentration of atmosphere 5 volume% or less in the temperature range exceeding 200 degreeC of the said process b).   The method for producing a transparent polyimide laminate according to claim 1, wherein the atmosphere is depressurized in a temperature range exceeding 200 ° C in the step b). The step b) is a step of heating the polyimide precursor film while raising the temperature from 150 ° C. or lower to over 200 ° C.,
The manufacturing method of the transparent polyimide laminated body of Claim 1 which makes the average temperature increase rate of the temperature range of 150-200 degreeC in the said process b) 0.25-50 degreeC / min. The polyimide precursor is
A tetracarboxylic acid component (A) containing one or more tetracarboxylic dianhydrides represented by the following general formula (a);
The compound formed by making these react with the diamine component (B) containing 1 or more types of diamine chosen from the group which consists of a compound represented by the following general formula (b-1)-(b-3). The manufacturing method of the transparent polyimide laminated body of description.

(In the general formula (a), R ¹ represents a tetravalent group having 4 to 27 carbon atoms, and an aliphatic group, a monocyclic aliphatic group, a condensed polycyclic aliphatic group, or a monocyclic aromatic group. Or a condensed polycyclic aromatic group, a non-condensed polycyclic aliphatic group in which the cycloaliphatic groups are linked directly or by a bridging member, or an aromatic group is directly or a bridging member Represents non-condensed polycyclic aromatic groups linked together by

The polyimide precursor has a repeating unit represented by the following general formula (I):
The 1,4-bismethylenecyclohexane skeleton (X) in the general formula (I) is composed of a trans isomer represented by the formula (X1) and a cis isomer represented by the formula (X2).
The transparent polyimide laminate according to claim 7, wherein the content ratio of the trans isomer to the cis isomer (trans isomer + cis isomer = 100%) is 60% ≦ trans isomer ≦ 100%, 0% ≦ cis isomer ≦ 40%. Body manufacturing method.

(In the general formula (I), R ¹⁰ represents a tetravalent group having 4 to 27 carbon atoms, and an aliphatic group, a monocyclic aliphatic group, a condensed polycyclic aliphatic group, or a monocyclic aromatic group. Or a condensed polycyclic aromatic group, a non-condensed polycyclic aliphatic group in which the cycloaliphatic groups are linked directly or by a bridging member, or an aromatic group is directly or a bridging member Represents non-condensed polycyclic aromatic groups linked together by The polyimide precursor is
A polyamic acid block composed of repeating structural units represented by the following general formula (G);
The manufacturing method of the transparent polyimide laminated body of Claim 1 which is a block polyamic-acid imide which has a polyimide block comprised by the repeating structural unit represented by the following general formula (H).

(In General Formulas (G) and (H), R ⁶ and R ⁸ are each independently a tetravalent group having 4 to 27 carbon atoms, and an aliphatic group, a monocyclic aliphatic group, or a condensed polycyclic group. Whether it represents an aliphatic group, a monocyclic aromatic group, or a condensed polycyclic aromatic group, or a non-condensed polycyclic aliphatic group in which the cyclic aliphatic groups are connected to each other directly or by a bridging member Or a non-condensed polycyclic aromatic group in which the aromatic groups are connected to each other directly or by a bridging member;
In the general formula (H), R ⁷ is a divalent group having 4 to 51 carbon atoms, and an aliphatic group, a monocyclic aliphatic group (excluding a 1,4-cyclohexylene group), a condensed group A polycyclic aliphatic group, a monocyclic aromatic group or a condensed polycyclic aromatic group, or a non-condensed polycyclic aliphatic group in which the cyclic aliphatic groups are connected to each other directly or by a bridging member Or a non-condensed polycyclic aromatic group in which the aromatic groups are connected to each other directly or by a bridging member) The step a) is a step of applying the polyimide precursor-containing solution on the support substrate that has been fed out from a roll.
The said process b) is a manufacturing method of the transparent polyimide laminated body of Claim 1 including the step which winds up the said transparent polyimide laminated body to a roll after the said polyimide precursor film is heated.   The transparent polyimide laminated body obtained from the manufacturing method of Claim 1.   The optical film obtained by peeling a transparent polyimide layer from the support base material of the transparent polyimide laminated body of Claim 11.   The manufacturing method of a transparent polyimide film including the process of peeling a transparent polyimide layer from the support base material of the transparent polyimide laminated body of Claim 11, and obtaining a transparent polyimide film. Forming a device on the transparent polyimide layer of the transparent polyimide laminate according to claim 11,
And a step of peeling the transparent polyimide layer after forming the element from the support substrate.   The manufacturing method of a flexible device which has the process of forming an element on the transparent polyimide film obtained with the manufacturing method of Claim 11.   The touch panel display obtained by the manufacturing method of the flexible device of Claim 14 or 15.   The liquid crystal display obtained by the manufacturing method of the flexible device of Claim 14 or 15. An organic EL display obtained by the method for producing a flexible device according to claim 14.

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