JP2017185806A - Polyimide resin laminate and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyimide resin laminate used for a display or a touch panel and capable of suppressing warpage as much as possible while maintaining handling ability in a manufacturing process and thickness as a substrate.SOLUTION: There is provided a polyimide resin laminate by laminating a curl suppression layer consisting of a polyimide resin, a carrier layer consisting of the polyimide resin and a substrate layer consisting of the polyimide resin, the curl suppression layer and the carrier layer are detachably adhered to one surface side of the substrate layer and thermal expansion coefficient (CTE) of a layer contacting with the substrate layer is smaller or larger than CTEs of any other layers.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a polyimide resin laminate in which functional layers such as a liquid crystal display device, an organic EL display, organic EL lighting, electronic paper, a touch panel, and a color filter are formed on a polyimide substrate, and a method for manufacturing the same.

  Display devices such as liquid crystal display devices and organic EL display devices are widely used from large displays such as televisions to small displays such as mobile phones, personal computers and smartphones. For example, in an organic EL display device, a thin film transistor (TFT) is formed on a glass substrate, an electrode, a light emitting layer, an electrode and the like are sequentially formed, and finally airtightly sealed with a glass substrate and a multilayer thin film.

  Here, the type of the display device is not particularly limited, but includes display device components such as a liquid crystal display device, an organic EL display device, electronic paper, and a color filter. In addition, the display device includes an organic EL lighting device, a touch panel device, a conductive film laminated with ITO, a gas barrier film that prevents permeation of moisture, oxygen, and the like, and components of a flexible circuit board. Various functional devices used are also included. That is, the flexible device referred to in the present invention is not only a component such as a liquid crystal display device, an organic EL display device, and a color filter, but also an organic EL lighting device, a touch panel device, an electrode layer or a light emitting layer of the organic EL display device, A gas barrier film, an adhesive film, a thin film transistor (TFT), a wiring layer of a liquid crystal display device, or a combination of two or more types such as a transparent conductive layer is also included.

  By replacing the glass substrate with a resin base material, it is possible to realize a reduction in thickness, weight, and flexibility, thereby further expanding the applications of the display device. However, there are problems that the resin is inferior in dimensional stability, transparency, heat resistance, moisture resistance, gas barrier properties, etc., compared to glass.

  For example, Patent Document 1 relates to a polyimide useful as a plastic substrate for a flexible display and an invention relating to a precursor thereof, and uses tetracarboxylic acids containing an alicyclic structure such as cyclohexylphenyltetracarboxylic acid. Discloses that the polyimide reacted with various diamines is excellent in transparency. In addition to this, attempts have been made to reduce the weight by using a flexible resin base instead of a glass substrate. For example, in Non-Patent Documents 1 and 2, an organic EL display device using highly transparent polyimide is used. Has been proposed.

  Thus, although it is known that a resin film such as polyimide is useful as a support base material for a flexible display, the manufacturing process of the display device has already been performed using a glass substrate, and its production equipment Most of them are designed on the assumption that glass substrates are used. Therefore, it is desirable to be able to produce display devices while effectively utilizing existing production equipment.

  As one of the examination examples, the manufacturing process of a predetermined display device is completed in a state where the resin is laminated on the glass substrate, and then the glass substrate is removed to provide a display unit on the resin base material. There are methods for manufacturing a display device (see Patent Documents 2 to 3 and Non-Patent Documents 3 to 4). In the case of such a method, it is important to separate the resin base material and the glass without damaging the display portion formed on the resin base material.

  That is, in Patent Document 3 and Non-Patent Document 3, after a predetermined display portion is formed on a resin base material applied and fixed on a glass substrate, a method called an EPLaR (Electronics on Plastic by Laser Release) process is used. The resin base material provided with the display part is forcibly separated from the glass substrate by irradiating a laser from the glass side. In Patent Document 2 and Non-Patent Document 4, after a release layer is formed on a glass substrate, a polyimide resin is applied slightly larger than the release layer to form a polyimide layer, and a cutting line reaching the release layer is inserted. Thus, a slightly smaller polyimide film is peeled off from the release layer.

  On the other hand, when a resin is laminated on a glass substrate, warping becomes a big problem. That is, the thermal expansion coefficient of the glass substrate is several ppm / K, whereas the resin generally has a thermal expansion coefficient of several tens of ppm / K or more. For example, a resin solution is applied on the glass substrate and heated. When it is cured by treatment or the like to form a resin layer and allowed to cool to room temperature, warpage occurs. If such warpage cannot be suppressed, the subsequent formation of the display portion and the like will be adversely affected.

  In the process using a polyimide laminate, the flexible display TFT substrate process usually uses an In-Ga-Zn-O semiconductor (IGZO) or low-temperature polysilicon (LTPS) method, and heat is applied at 350 ° C or higher. . At that time, the thermal expansion coefficient of the glass substrate is several ppm / K, whereas the resin generally has a thermal expansion coefficient of several tens of ppm / K or more, so that the laminate is warped, and the display unit There is a risk that it will not be possible to reduce the size.

  In this regard, in Patent Document 3, a resin layer (b) having a thermal expansion coefficient between the support substrate and the resin film (a) is provided between the support substrate and the resin film (a). Although disclosed, the effect of suppressing warpage is not sufficient.

By the way, when a display, a touch panel, etc. are manufactured by a roll-to-roll (hereinafter also referred to as “RTR”) system, the film as a supporting substrate can withstand high temperature processing exceeding 300 ° C. during the process. Therefore, the material is required to be excellent in heat resistance. Moreover, when considering the light transmittance, a thin film is preferable. However, since it is difficult to handle a thin film and it is difficult to manufacture, a transparent film having a thickness of 50 μm or more is currently used.
In addition, a transparent film with a carrier has been proposed as a method of achieving both handling and manufacturing ease and thinness. In this laminated film with carrier, a carrier film and a transparent substrate film are laminated without using an adhesive, and after forming a functional layer such as a thin film transistor on the transparent substrate, it is further bonded to the front plate By peeling off the carrier film, it is possible to achieve both handleability in the manufacturing process and thinness as a transparent support substrate in a display or a touch panel.
However, the conventional laminated film with a carrier is likely to warp (curl), and the handling property in the manufacturing process is very poor.

  In patent document 4, in order to suppress generation | occurrence | production of curvature, the 1st polyimide layer whose thermal expansion coefficient is smaller than it is provided with respect to support bodies, such as a glass substrate, and a thermal expansion coefficient is a support body on it. Although providing the 2nd polyimide layer larger than this is disclosed, the examination about the support body which consists of heat resistant resin which is not a glass substrate is not disclosed.

JP 2008-231327 A Japanese Patent No. 4834758 Japanese Patent No. 5408848 JP-A-2015-182393

S. An et. al., "2.8-inch WQVGA Flexible AMOLED Using High Performance Low Temperature Polysilicon TFT on Plastic Substrates", SID2010 DIGEST, p706 (2010) Oishi et. al., "Transparent PI for flexible display", IDW'11 FLX2 / FMC4-1 E.I. Haskal et. Al. "Flexible OLED Displays Made with the EPLaR Process", Proc. Eurodisplay '07, pp. 36-39 (2007) Cheng-Chung Lee et. Al. "A Novel Approach to Make Flexible Active Matrix Displays", SID10 Digest, pp.810-813 (2010)

  Therefore, the object of the present invention is a polyimide resin laminate with a carrier used as a glass substitute substrate for a display or a touch panel, and even in the case where a heat resistant resin applicable to the RTR process is used as a carrier material, A polyimide resin laminate capable of suppressing curling as much as possible while maintaining handling properties and thinness as a support substrate in a display or touch panel, and capable of easily and easily separating the support substrate from a carrier material, and its production Is to provide a method.

  Thus, as a result of intensive studies to solve these problems, the present inventors have surprisingly found that a curl suppressing layer made of a predetermined polyimide resin is provided on one side of a base material layer made of a predetermined polyimide resin. And by laminating a carrier layer made of a predetermined polyimide resin, it was found that curling can be improved while maintaining handling properties and thinness as a substrate, and the present invention has been completed.

  That is, the present invention is a polyimide resin laminate in which a curl suppressing layer made of a polyimide resin, a carrier layer made of a polyimide resin, and a base material layer made of a polyimide resin are laminated, on one side of the base material layer The polyimide, wherein the curl-suppressing layer and the carrier layer are detachably bonded, and the coefficient of thermal expansion (CTE) of the layer in contact with the base material layer is smaller or larger than any of the CTEs of the other layers It is a resin laminate.

The polyimide resin laminate of the present invention is preferably in any of the following aspects.
1) It has a curl suppressing layer on one side of the carrier layer, and further has a base material layer that is releasably adhered to the curl suppressing layer, and the CTE of the curl suppressing layer is higher than any of the CTE of the support layer and the base material layer. Small or large,
2) having a base material layer releasably bonded to one side of the carrier layer, having a curl suppression layer on the opposite side of the carrier layer, and the CTE of the carrier layer being the CTE of the base material layer and the curl control layer Smaller or larger than either.

In the polyimide resin laminate of the present invention, the CTE difference between the base material layer and the carrier layer or the CTE difference between the base material layer and the curl suppressing layer is preferably ± 40 ppm / K or less.
The polyimide resin laminate of the present invention is a polyimide resin laminate in which a functional layer is further formed on one side of the carrier layer with a curl suppression layer and a substrate layer interposed therebetween, or a substrate layer on the one side of the carrier layer It can be preferably used as a polyimide resin laminate with a functional layer in which a functional layer is further formed with an intervening layer interposed therebetween.
In the polyimide resin laminate of the present invention, the total light transmittance of the base material layer is preferably 80% or more and the thickness is preferably 50 μm or less, and the Tg of the polyimide resin forming the base material layer is 300 ° C. or more. It is preferable that

As another aspect of the present invention, the polyimide resin laminate with a functional layer is used, and the carrier layer and the curl are peeled off at the interface between the curl suppressing layer and the base material layer or at the interface between the carrier layer and the base material layer. It is a polyimide film with a functional layer formed by removing the suppression layer.
Moreover, this invention is a method of manufacturing the said polyimide resin laminated body, Comprising: A curl suppression layer and a base material layer are formed in a carrier layer by the casting method, It is a manufacturing method of the polyimide resin laminated body characterized by the above-mentioned. .
In this production method, the curl suppressing layer and the base material layer coated on the carrier layer are preferably integrally cured, and the casting method is preferably coating with a multilayer die or a continuous die.

  According to the present invention, it is possible to suppress warping (curl) as much as possible while maintaining the handling property in the manufacturing process and the thinness as a support base material in a display or a touch panel, and the required characteristics of the polyimide resin laminate for display or touch panel applications. Can be satisfied.

It is sectional drawing which shows each layer structure about the laminated body of this invention. It is a schematic diagram of the apparatus for forming a functional layer about a laminated body. It is a simulation figure which shows a mode that curvature generate | occur | produces in a laminated body.

  First, the polyimide resin laminate of the present invention includes a carrier layer made of a polyimide resin. The carrier layer maintains the thin base layer in a predetermined shape in the RTR process, and is peeled off from the base layer after a functional layer such as an ITO film is formed through the base layer. Is. Therefore, in order to adapt to the RTR process, it is required to maintain flexibility by reinforcing the base material layer, but transparency is not necessarily required. Therefore, the thickness of the carrier layer is larger than that of the thin film base layer, preferably 10 to 100 μm, more preferably 30 to 75 μm. Moreover, since the heat resistance applicable to the high temperature process of RTR is requested | required, Preferably glass transition temperature (Tg) is 300 degreeC or more, More preferably, it is 300-450 degreeC.

The polyimide resin laminate of the present invention includes a curl suppression layer made of polyimide resin (hereinafter also simply referred to as a curl suppression layer), a carrier layer made of polyimide resin (hereinafter also simply referred to as a carrier layer), and a polyimide resin. A polyimide laminate in which a base material layer (hereinafter also simply referred to as a base material layer) is laminated, and a laminate of a curl suppressing layer and a carrier layer is detachably adhered to one surface side of the base material layer. It is characterized by being. Furthermore, in the polyimide resin laminate, the CTE of the layer in contact with the base material layer is smaller or larger than any of the CTEs of the other layers.
Here, the layer in contact with the base material layer has either two forms of a curl suppression layer or a carrier layer, and the other layer is a base when the layer in contact with the base material layer is a curl control layer. The material layer and the carrier layer are referred to. When the layer in contact with the base material layer is the carrier layer, the material layer and the curl suppressing layer are referred to.
There are two types of the polyimide resin laminate (form 1 and form 2). Below, each form is demonstrated concretely.

[Form 1]
The polyimide resin laminate of aspect 1 has a curl suppression layer on one side of the carrier layer, and further has a base material layer that is releasably bonded to the curl suppression layer, and the CTE of the curl suppression layer is the carrier layer and the base layer. Smaller or larger than any of the material layer CTEs.

  Further, from the viewpoint of warpage suppression, the CTE of the carrier layer is preferably approximated to the CTE of the base material layer, and the CTE difference (ΔCTE) between them is preferably within ± 15 ppm / K, more preferably the base material. The difference in the CTE of the layer is within +15 ppm / K compared to the CTE of the carrier layer, that is, the CTE difference is 0 to +15 ppm / K. For example, the CTE of the carrier layer is preferably 10 to 85 ppm / K. Here, the CTE difference within ± 15 ppm / K means that the CTE of the base material layer is a difference of −15 to +15 ppm / K compared to the CTE of the carrier layer.

  On one side of the carrier layer, a base material layer is provided with a post-curl suppression layer interposed therebetween. The base material layer is formed with a functional layer such as an ITO film, and after the RTR process is finished, the carrier layer is peeled and removed, and then becomes a transparent substrate instead of glass that supports the functional layer. Therefore, the base material layer preferably has a total light transmittance of 80% or more, more preferably 90% or more. The thickness of the base material layer is preferably as thin as possible from the required characteristics of thinning, lightening, and flexibility, and is preferably 50 μm or less, more preferably 5 to 25 μm. As described above, the CTE of the base material layer should be close to the CTE of the carrier layer, and is preferably 10 to 80 ppm / K. Moreover, since the heat resistance applicable to the high temperature process of RTR is requested | required, the glass transition temperature (Tg) of a base material layer becomes like this. Preferably it is 300 degreeC or more, More preferably, it is 300-450 degreeC. The elastic modulus of the base material layer is preferably 2 to 15 GPa, for example, because it is used as a resin base material instead of glass.

On one side of the carrier layer, a curl suppressing layer made of polyimide resin is provided between the carrier layer and the base material layer. From the viewpoint of adapting to the RTR process, the curl suppression layer is formed between the carrier layer and the base material layer in order to suppress the warpage of the base material layer with carrier as much as possible, and the carrier layer and the curl suppression layer are the base material layer. A functional layer such as an ITO film is formed with the intervening layer, and when the carrier layer is peeled and removed after completion of the RTR process, the functional layer is removed together with the carrier layer. Therefore, the thickness and the thermal expansion coefficient are selected in order to suppress warping as much as possible in the RTR process. Therefore, the thickness of the curl suppressing layer is preferably 50 μm or less, more preferably 5 to 30 μm. Moreover, since heat resistance applicable to the high temperature process of RTR is requested | required, Tg becomes like this. Preferably it is 300 degreeC or more, More preferably, it is 300-450 degreeC.
The CTE of the curl suppression layer is selected so that the CTE difference between the carrier layer and the base material layer is relatively large. For example, the CTE of the carrier layer and the base material layer may not necessarily be the same, but it is preferable to select the CTE of the curl suppression layer to have a certain difference or more with respect to both of these CTEs.
Therefore, for the CTE of the curl suppression layer, the CTE difference with the carrier layer and the CTE difference with the base material layer are preferably ± 15 ppm / K or more, more preferably CTE in the range of −15 to −60 ppm / K. It is a difference. The CTE of the curl suppressing layer is preferably −10 to 20 ppm / K. Here, the CTE difference of ± 15 ppm / K or more means that the CTE of the curl suppression layer is larger than −15 ppm / K compared to the CTE of the carrier layer and the CTE of the base material layer, or +15 ppm / K. Means that the difference is greater.

  The carrier-attached base material composed of the carrier layer and the base material layer has a curl-suppressing layer between the carrier layer and the base material layer, so that the fourth generation of the so-called glass substrate (680 × 880 mm to 730 × Even when a relatively large laminate corresponding to 920 mm) or later is used, the effect of suppressing warping can be sufficiently obtained. In addition, the presence of the curl suppression layer can increase the degree of freedom in designing the base material layer. Furthermore, the foreign matter adhering to the carrier layer is not easily mixed into the base material layer. In addition, since the surface state of the carrier layer hardly affects the base material layer, it is possible to increase the degree of freedom in designing the carrier layer, such as selecting an inexpensive polyimide film.

[Form 2]
The polyimide resin laminate of aspect 2 has a base material layer that is releasably bonded to one side of the carrier layer, and further has a curl suppressing layer on the opposite side of the carrier layer, and the CTE of the carrier layer is It is smaller or larger than any of the CTE of the base material layer and the curl suppressing layer.
That is, the carrier layer is located between the base material layer and the curl suppressing layer. If it is this structure, it is preferable from a viewpoint of curvature suppression. For example, the CTE of the carrier layer is preferably 10 to 70 ppm / K.

The base material layer is formed with a functional layer such as an ITO film, and after the RTR process is finished, the carrier layer is peeled and removed, and then becomes a transparent substrate instead of glass that supports the functional layer. Therefore, the base material layer preferably has a total light transmittance of 80% or more, more preferably 90% or more. The thickness of the base material layer is preferably as thin as possible within the range that does not impair the workability from the required characteristics of thinning, lightening, and flexibility, and is preferably 50 μm or less, more preferably 5 to 25 μm. The CTE of the base material layer is preferably 1 to 80 ppm / K.
Moreover, since the heat resistance applicable to the high temperature process of RTR is requested | required, Preferably glass transition temperature (Tg) is 300 degreeC or more, More preferably, it is 300-450 degreeC. The elastic modulus of the base material layer is preferably 2 to 15 GPa, for example, because it is used as a resin base material instead of glass.

On the opposite side of the carrier layer, there is a curl suppression layer made of polyimide resin. From the viewpoint of adapting to the RTR process, the curl suppression layer is formed on the side opposite to the base material layer in order to suppress the warpage of the base material layer with carrier as much as possible, and the carrier layer interposes the base material layer and the ITO film. When the carrier layer is peeled and removed after completion of the RTR process, the functional layer is removed together with the carrier layer. Therefore, thickness and thermal expansion coefficient are selected in order to suppress warping (curl) as much as possible in the RTR process. Therefore, the thickness of the curl suppressing layer is preferably 50 μm or less, more preferably 6 to 30 μm. Moreover, since the heat resistance applicable to the high temperature process of RTR is requested | required, Preferably glass transition temperature (Tg) is 300 degreeC or more, More preferably, it is 300-450 degreeC.
The CTE of the curl suppressing layer is preferably close to the CTE of the base material layer, and is preferably selected so as to cancel the CTE difference between the carrier layer and the base material layer. Therefore, the CTE difference with the base material layer is within ± 40 ppm / K, preferably within ± 15 ppm / K. For example, the CTE of the curl suppressing layer is preferably 1 to 90 ppm / K.

  The base material with carrier consisting of the carrier layer and the base material layer has the curl suppression layer on the side opposite to the base material, so that the fourth generation of the so-called glass substrate (680 × 880 mm to 730 × 920 mm) or later in particular. Even when a relatively large laminated body corresponding to the above is used, the effect of suppressing warpage can be sufficiently obtained. In addition, the presence of the curl suppression layer can increase the degree of freedom in designing the base material layer.

  Below, the content common to the form 1 and the form 2 is demonstrated concretely.

The polyimide resin used as the curl suppressing layer is not particularly limited as long as the above characteristics are satisfied. For example, it may be formed of polyimide having a structural unit represented by the following general formula (1). Preferably, it is a polyimide containing 50 mol% or more of a structural unit represented by the following general formula (1).

Here, X in the general formula (1) is an aromatic group or an alicyclic group, which is a tetravalent organic group having one or more aromatic rings or alicyclic rings, and R is a carbon number of 1-6. Is a substituent. Among these, suitable specific examples of raw materials for forming the group X include, for example, pyromellitic dianhydride (PMDA), naphthalene-2,3,6,7-tetracarboxylic dianhydride (NTCDA). ), 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) and the like. Further, suitable examples of R, for example, -CH _3, -CF _3, and the like.

In particular, when R is —CF ₃ , the peelability at the interface with the base material layer can be improved, and separation of these can be facilitated.

  In addition, as for what can be contained other than the structural unit represented by the above general formula (1), preferably less than 50 mol% at maximum, a general acid anhydride and diamine can be used. Structural units. Among them, pyromellitic dianhydride (PMDA), naphthalene-2,3,6,7-tetracarboxylic dianhydride (NTCDA), 3,3 ′, 4,4 are preferably used. '-Biphenyltetracarboxylic dianhydride (BPDA), cyclohexanetetracarboxylic dianhydride, phenylenebis (trimellitic monoester anhydride), 4,4'-oxydiphthalic dianhydride, benzophenone-3,4, 3 ', 4'-tetracarboxylic dianhydride, diphenylsulfone-3,4,3', 4'-tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 4 4,4 '-(2,2'-hexafluoroisopropylidene) diphthalic dianhydride. On the other hand, diamines include m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, 4,4'-diaminodiphenyl ether, 1,3-bis (4-aminophenoxy) benzene, 4,4'-diamino. Diphenylsulfone, 2,2-bis (4-aminobenzyloxyphenyl) propane, bis [4- (4-aminophenoxy) phenyl] sulfone, 4,4′-diaminobenzanilide, 9,9-bis (4-amino) Phenyl) fluorene and the like.

  In general, when the thermal expansion coefficient of polyimide is reduced, transparency is lowered and retardation in the thickness direction (phase difference due to difference in birefringence) is increased. Therefore, it becomes unsuitable when the base material layer separated from the carrier layer after the RTR process is used as, for example, a resin base material of a display device, a gas barrier film, or a touch panel substrate. On the other hand, in the present invention, the use of the base material layer having a larger thermal expansion coefficient than that of the carrier layer is allowed due to the presence of the curl suppressing layer on the opposite side.

The polyimide which forms a base material layer can be suitably selected according to the use of a polyimide resin laminated body. In particular, when used as a flexible resin substrate in a display device such as a liquid crystal display device, an organic EL display device, electronic paper, a color filter, or a touch panel, it is represented by the following general formula (2). The polyimide which has a structural unit is mentioned, Preferably, it is a polyimide which contains 50 mol% or more of structural units represented by this General formula (2). In addition, about what can be contained other than the structural unit represented by this general formula (2) (preferably containing less than 50 mol% at the maximum), unless the transparency is inhibited, the general formula (1) The thing similar to what was demonstrated in (1) is mentioned. Preferred acid anhydrides include pyromellitic dianhydride (PMDA), naphthalene-2,3,6,7-tetracarboxylic dianhydride (NTCDA), 3,3 ′, 4,4′- Biphenyltetracarboxylic dianhydride (BPDA), cyclohexanetetracarboxylic dianhydride, phenylenebis (trimellitic monoester anhydride), 4,4'-oxydiphthalic dianhydride, benzophenone-3,4,3 ' , 4'-tetracarboxylic dianhydride, diphenylsulfone-3,4,3 ', 4'-tetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 4,4 '-(2,2'-hexafluoroisopropylidene) diphthalic dianhydride and the like. On the other hand, diamines include m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, 4,4'-diaminodiphenyl ether, 1,3-bis (4-aminophenoxy) benzene, 4,4'-diamino. Diphenylsulfone, 2,2-bis (4-aminobenzyloxyphenyl) propane, bis [4- (4-aminophenoxy) phenyl] sulfone, 4,4′-diaminobenzanilide, 9,9-bis (4-amino) Phenyl) fluorene and the like.

In the general formula (2), Y is an aromatic or alicyclic tetravalent organic group, and is preferably any one represented by the following formula (3).

Among them, as a base material layer, from the viewpoint of obtaining a polyimide resin having a transmittance in a wavelength range of 440 nm to 780 nm at 500 nm of 80% or more and a thickness direction retardation of 200 nm or less, more preferably, It is either shown by Formula (4).

Preferably, it is a polyimide resin represented by the following formula (5).

  The polyimide resin used as the carrier layer is not particularly limited as long as it satisfies the above-mentioned characteristics. For example, Kapton (manufactured by Toray DuPont), Upilex (manufactured by Ube Industries), Apical (Kaneka) Or a commercially available polyimide having a structure similar to these, or can be synthesized from diamine and acid dianhydride as described in detail below.

  The various polyimides described above are obtained by imidizing a polyimide precursor (hereinafter also referred to as polyamic acid), but the polyamic acid resin solution uses substantially equimolar amounts of diamine and acid dianhydride as raw materials. It can be obtained by reacting in an organic solvent. Specifically, for example, it can be obtained by dissolving diamine in an organic polar solvent such as N, N-dimethylacetamide under a nitrogen stream, adding tetracarboxylic dianhydride, and reacting at room temperature for about 5 hours. it can. Here, the weight average molecular weight (Mw) of the polyamic acid is preferably about 10,000 to 300,000 from the viewpoint of uniform film thickness during coating and the mechanical strength of the resulting polyimide. The preferred molecular weight range of the polyimide resin is also the same molecular weight range as that of the polyamic acid.

  The base material layer and the curl suppressing layer in the present invention are preferably obtained by a so-called casting method in which a polyimide or polyimide precursor resin solution is applied and dried, followed by heat treatment. That is, in obtaining the polyimide resin laminate of the present invention, it is preferable to apply and dry a polyimide or polyimide precursor resin solution on one side or both sides of the carrier layer, respectively, and heat-treat the substrate. Layers and curl suppression layers can be formed. For example, after preheating at 90 to 130 ° C. for about 5 to 30 minutes for drying, etc., further high temperature heating at 130 to 360 ° C. for about 10 to 240 minutes is performed for imidization. Is preferred.

  The polyimide resin laminate thus obtained can be separated at the interface between the base material layer and the layer (carrier layer or curl suppression layer) in contact with the base material layer. In order to facilitate the above, it is preferable that the base material layer be formed of a fluorine-containing polyimide having a fluorine atom in the polyimide structure. By using such a fluorine-containing polyimide, the peel strength between the base material layer and the layer in contact with the base material layer is preferably 1 to 200 N / m, more preferably 1 to 100 N / m. Therefore, for example, it has a separability enough to be easily peeled off by a human hand. In addition, the separation surface of the base material layer maintains the surface roughness obtained by the casting method (generally surface roughness Ra = 1 to 80 nm) as it is, so that the visibility of the display device is adversely affected. Nor.

  In the present invention, with respect to a polyimide resin laminate in which different materials are laminated, warping deformation (amount of warpage) can be obtained by calculation based on the following idea, and the polyimide resin laminate can be optimized. . That is, based on simple material mechanics calculation, the influence of its own weight was calculated by three-dimensional material mechanics calculation and added to warpage deformation (warpage amount) to obtain the final warpage amount. As a calculation method, a finite element method was used in which the final warpage deformation in a state where thermal deformation and its own weight are balanced is discretized using a laminated shell element and numerically calculated by a computer. (See Figure 3)

  As described above, the polyimide resin laminate of the present invention can be suitably used to obtain a display device having a functional member on a base material layer. That is, after a predetermined functional layer is formed on the base material layer, the functional layer may be separated at the interface between the curl suppression layer and the base material layer or at the interface between the base material layer and the carrier layer. Here, the carrier layer serves as a pedestal when forming the display part on the base material layer side, and ensuring the handleability and dimensional stability of the base material layer in the manufacturing process of the display part Even if it exists, it is removed finally and does not constitute a display device. Similarly, the curl-suppressing layer is not separated from the carrier layer and finally removed in the same manner to constitute a display device, and it may be inferior in transparency. By using such a polyimide resin laminate, it is possible to accurately and reliably form a predetermined functional layer on the base material layer, and to obtain a thin, lightweight, and flexible display device. it can.

  The functional layer formed on the base material layer is not particularly limited. For example, in the case of an organic EL display device, typically, an organic EL element including a TFT, an electrode, a light emitting layer, or the like corresponds to the display unit. In the case of a liquid crystal display device, a TFT, a drive circuit, and a color filter as necessary. In addition to these, various functional layers conventionally formed on a glass substrate including various display devices such as electronic paper and MEMS displays, etc., for projecting a predetermined video (moving image or image). Necessary parts correspond to the display unit. Among these, for example, formation of TFT generally requires an annealing step of about 400 ° C., but the polyimide resin laminate in the present invention has heat resistance that can withstand such an annealing step.

  Hereinafter, based on an Example and a comparative example, this invention is demonstrated concretely. The present invention is not limited to these contents.

1. Various physical property measurement and performance test methods

[Peel strength]
The peel strength between the base material layer- (curl suppression layer) -carrier layer was obtained by processing the laminate into a strip shape having a width of 1 mm to 10 mm and a length of 10 mm to 25 mm. Using Graph-M1), the carrier layer was peeled off in the 180 ° direction, and the peel strength was measured. In addition, the thing whose peeling strength was strong and it was difficult to peel was made into "non-peeling".

[Transmissivity]
A 20 μm-thick base material layer was cut into a 5 cm square, and this was measured for transmittance from 380 nm to 780 nm using HAZE METER NDH-5000 manufactured by Nippon Denshoku Industries Co., Ltd.

[Ra]
The base material layer, the carrier layer, and the curl suppression layer were each cut into 3 cm squares, and Ra was measured using an AFM manufactured by Bruker AXS.

[CTE]
The CTE of the base material layer, the carrier layer, and the curl suppression layer was cut into 3 mm × 15 mm squares, and this was constant while applying a 5.0 g load with a thermomechanical analysis (TMA) apparatus manufactured by Seiko Instruments. A tensile test is performed in a temperature range of 30 ° C. to 260 ° C. at a rate of temperature increase (10 ° C./min), and CTE (× 10 ⁻⁶ / K) is calculated from the amount of elongation of the polyimide film relative to the temperature at 100 ° C. to 250 ° C. It was measured.

[warp]
A square sample with a side of 100mm was cut out from the laminated film with a cutter knife, conditioned at 23 ° C and 50% for 24 hours, placed on a surface plate, measured with four calipers, and the average value warped ( Curl).

2. Synthesis of Polyamic Acid (Polyimide Precursor) Solution The raw materials used in the following synthesis examples and examples are shown below.

[Aromatic diamino compounds]
・ 4,4′-diamino-2,2′-bis (trifluoromethyl) biphenyl (TFMB)
・ 2,2'-dimethyl-4,4'-diaminobiphenyl (mTB)
1,3-bis (4-aminophenoxy) benzene (TPER)
2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP)
・ 1,4-Phenylenediamine (PPD)
[Aromatic tetracarboxylic acid anhydride]
・ Pyromellitic anhydride (PMDA)
2,2-bis (3,4-anhydrodicarboxyphenyl) hexafluoropropane (6FDA)
・ 2,3,2 ′, 3′-biphenyltetracarboxylic dianhydride (BPDA)
〔solvent〕
・ N, N-dimethylacetamide (DMAc)

Synthesis example 1
Under a nitrogen stream, TFMB (9.4 g, 0.03 mol) was added to 127.5 g of solvent DMAc while stirring in a 300 ml separable flask, and dissolved at 50 ° C. 6FDA (13.09 g, 0.03 mol) was then added. The molar ratio of diamine to acid anhydride was substantially 1: 1. Thereafter, the solution was stirred at room temperature for 3 hours to carry out a polymerization reaction to obtain 200 g of a pale yellow viscous polyamic acid varnish A. In addition, the polyimide resin A is obtained by hardening | curing this polyamic-acid varnish A on the below-mentioned heating conditions.

Synthesis example 2
Under a nitrogen stream, 10.2 g of m-TB and 1.6 g of TPE-R at a molar ratio of 90:10 were added to 170 g of solvent DMAc while stirring in a 300 ml separable flask, and dissolved at 50 ° C. . Next, 9.2 g of PMDA and 3.1 g of BPDA were added at a molar ratio of 90:10. The molar ratio of diamine to acid anhydride was substantially 1: 1. Thereafter, the solution was stirred at room temperature for 3 hours to carry out a polymerization reaction to obtain 200 g of a pale white viscous polyamic acid varnish B. In addition, the polyimide resin B is obtained by hardening | curing this polyamic-acid varnish B on the below-mentioned heating conditions.

Synthesis example 3
Under a nitrogen stream, TFMB (12.6 g, 0.04 mol) was added to 127.5 g of solvent DMAc while stirring in a 300 ml separable flask, and dissolved at 50 ° C. Then 6FDA (2.2 g, 0.005 mol) and PMDA (7.7 g, 0.035 mol) were added at a molar ratio of 12.5: 87.5. The molar ratio of diamine to acid anhydride was substantially 1: 1. Thereafter, the solution was stirred at room temperature for 3 hours to carry out a polymerization reaction to obtain 150 g of a pale white viscous polyamic acid varnish C. In addition, the polyimide resin C is obtained by hardening | curing this polyamic-acid varnish C on the below-mentioned heating conditions.

Synthesis example 4
Under a nitrogen stream, m-TB (14.4 g, 0.07 mol) was added to 170 g of solvent DMAc while stirring in a 300 ml separable flask, and dissolved at 50 ° C. PMDA (13.6 g 0.06 mol) and BPDA (2 g, 0.007 mol) were then added at a 90:10 molar ratio. The molar ratio of diamine to acid anhydride was substantially 1: 1. Thereafter, the solution was stirred at room temperature for 3 hours to carry out a polymerization reaction to obtain 200 g of a pale white viscous polyamic acid varnish D. In addition, the polyimide resin D is obtained by hardening | curing this polyamic-acid varnish D on the below-mentioned heating conditions.

Synthesis example 5
Under a nitrogen stream, TPE-R (14.8 g, 0.05 mol) as a diamine was added to 170 g of solvent DMAc while stirring in a 300 ml separable flask, and dissolved at 50 ° C. Then BPDA (15.2 g, 0.05 mol) was added as an acid anhydride. The molar ratio of diamine to acid anhydride was substantially 1: 1. Thereafter, the solution was stirred at room temperature for 3 hours to carry out a polymerization reaction to obtain 200 g of a pale white viscous polyamic acid varnish E. In addition, the polyimide resin E is obtained by hardening | curing this polyamic-acid varnish E on the below-mentioned heating conditions.

Synthesis Example 6
Under a nitrogen stream, m-TB: TPE-R was added to 170 g of solvent DMAc while stirring in a 300 ml separable flask so that the molar ratio was 90:10, and dissolved at 50 ° C. Subsequently, it added so that the molar ratio of PMDA: BPDA might be set to 80:20. The molar ratio of diamine to acid anhydride was substantially 1: 1. Thereafter, the solution was stirred at room temperature for 3 hours to carry out a polymerization reaction to obtain 200 g of a pale white viscous polyamic acid F varnish. In addition, the polyimide resin F is obtained by hardening | curing this polyamic-acid F varnish on the below-mentioned heating conditions.

Synthesis example 7
Under a nitrogen stream, TFMB (16.93 g) was dissolved in the solvent DMAc (170 g) with stirring in a 300 ml separable flask. PMDA (10.12 g) and 6FDA (2.95 g) were then added. Thereafter, the solution was stirred at room temperature for 6 hours to carry out a polymerization reaction to obtain 200 g of a pale yellow viscous polyamic acid H varnish. In addition, the polyimide resin H is obtained by hardening | curing this polyamic-acid H varnish on the below-mentioned heating conditions.

Synthesis Example 8
Under a nitrogen stream, BAPP (19.45 g) was dissolved in the solvent DMAc (170 g) with stirring in a 300 ml separable flask. PMDA (9.85 g) and BPDA (0.70 g) were then added. Thereafter, the solution was continuously stirred at room temperature for 6 hours to carry out a polymerization reaction to obtain 200 g of a pale yellow viscous polyamic acid I varnish. In addition, the polyimide resin I is obtained by hardening | curing this polyamic-acid I varnish on the below-mentioned heating conditions.

Synthesis Example 9
Under a nitrogen stream, 4,4′-DAPE (8.97 g) was dissolved in the solvent DMAc (170 g) with stirring in a 300 ml separable flask. PMDA (8.95 g) and BPDA (12.08 g) were then added. Thereafter, the solution was stirred at room temperature for 6 hours to carry out a polymerization reaction, thereby obtaining 200 g of a brown viscous polyamic acid J varnish. In addition, the polyimide resin J is obtained by hardening | curing this polyamic-acid J varnish on the below-mentioned heating conditions.

Synthesis Example 10
Under a nitrogen stream, 4,4′-DAPE (8.14 g) and PPD (4.40 g) were dissolved in the solvent DMAc (170 g) with stirring in a 300 ml separable flask. PMDA (17.45 g) was then added. Thereafter, the solution was stirred at room temperature for 6 hours to carry out a polymerization reaction to obtain 200 g of a brown viscous polyamic acid K varnish. In addition, the polyimide resin K is obtained by hardening | curing this polyamic-acid K varnish on the below-mentioned heating conditions.

3. Formation of polyimide (PI) layer by coating Two types of polyimide films were used as carrier layers.
1) Polyimide film 1: Ningbo Imayama, China, thickness = 0.75 mm, CTE = 45 ppm / K, Ra = 3 nm (hereinafter also referred to as carrier film 1)
2) Polyimide film 2: manufactured by China Rayitek, thickness = 0.75 mm, CTE = 45 ppm / K, Ra = 10 nm (hereinafter also referred to as carrier film 2)

Example 1
The carrier film 1 (width 520 mm × length 500 m × thickness 75 μm) is provided with an unwinding section, a lip coater, a continuous drying furnace, a continuous furnace, and a winding section, for example, RTR type coating drying curing shown in FIG. While unwinding at a speed of 2 m / min with the equipment, the polyamic acid varnish B was applied using a Mono pump so that the film thickness was 45 μm. This is passed through a continuous drying furnace composed of a plurality of furnaces, dried at 90 ° C. for 2 minutes and at 130 ° C. for 1 minute, and further composed of a plurality of furnaces, from the furnace on the sample inlet side to the furnace on the outlet side. By passing through a continuous furnace where the temperature gradually increases and gradually heating from 130 ° C. to 400 ° C. for a total of 25 minutes, polyimide resin B as a curl suppressing layer was formed on the carrier film. Created a role. Next, this roll is set in the unwinding part of the same coating and drying apparatus, and the polyimide acid varnish A is applied to the polyimide resin B by 100 μm and passed through a continuous drying furnace composed of a plurality of furnaces. Dried at 130 ° C. for 2 minutes and further at 130 ° C. for 1 minute, and further passed through a continuous furnace composed of a plurality of furnaces and gradually increasing in temperature from the sample inlet side furnace to the outlet side furnace. From 10 ° C. to 400 ° C. in steps, the mixture was heated stepwise for a total of 20 minutes to form a polyimide resin A having a thickness of 10 μm as a base material layer to obtain a roll-shaped polyimide resin laminate (laminate 1).
The thickness of each layer of the laminate 1 was 75 μm for the carrier layer, 4.5 μm for the curl suppressing layer, and 10 μm for the base material layer. The layer structure of the laminate 1 is schematically shown in FIG. It has a structure in which the base material layer 2 is laminated on one surface side of the carrier film 4 with the curl suppression layer 3 interposed (mode 1). The functional layer 1 is formed on the base material layer 2 of the laminate by the following method.

Next, with respect to the roll-shaped polyimide resin laminate, the base material layer is formed at a speed of 2 m / min using an RTR system apparatus including an unwinding section, a transport roll, a process processing section, and a winding section. ITO as a functional layer having a thickness of 50 nm is formed on the base material layer by a sputtering method while being unwound in the longitudinal direction so as to be upward and introduced into a process processing unit installed in a vacuum chamber via a transport roll. Was formed into a film by continuous treatment and wound up as a polyimide substrate film with a functional layer.
Furthermore, the transparent circuit processing was performed in the XY direction of one direction (X direction) and the other direction (Y direction) about the ITO which was cut into the sheet | seat shape of the polyimide substrate film with a functional layer 370x450mm, and was formed into a film. At that time, the intersection of the Y circuit and the X circuit did not form a circuit.
Subsequently, an overcoat is applied to the intersection of the XY circuit, heat-treated at 250 ° C. to cure the overcoat layer, and a silver paste is used to bridge the overcoat layer to complete the XY circuit. Further, an overcoat was applied to the entire surface of the ITO film formation side, and an annealing treatment was performed at 270 ° C. to cure the overcoat and crystallize the ITO.
Finally, an OCA (transparent adhesive sheet) is attached to the surface of the ITO film on the cover glass, and then the carrier film and the curl suppression layer are mechanically peeled off, and the touch panel substrate on which the functional layer is formed on the base material layer Was completed.

Comparative Example 1
Without forming the curl suppressing layer, a polyimide resin A (thickness 10 μm) as a base material layer was formed on the carrier film 1 in the same manner as in Example 1 to obtain a polyimide resin laminate (laminate C1).
This laminated body C1 has a large warp (curl), and when the ITO film is cut into a sheet shape in the touch panel manufacturing process, it cannot be aligned with the mask due to the warp, and the transparent circuit processing in the XY directions cannot be performed. Could not be created.

Example 2
The carrier film 1 (width 520 mm × length 500 m × thickness 75 μm) is provided with an unwinding section, a lip coater, a continuous drying furnace, a continuous furnace, and a winding section, for example, RTR type coating drying curing shown in FIG. While unwinding at a speed of 2 m / min with equipment, the polyamic acid varnish E was applied using a Mono pump so that the film thickness was 100 μm. This is passed through a continuous drying furnace composed of a plurality of furnaces and dried at 90 ° C. for 2 minutes and 130 ° C. for 1 minute, and a roll on which a polyimide resin E as a curl suppressing layer is formed on a carrier film is provided. Created. Next, this roll is set in the unwinding part of the same coating and drying apparatus, and the polyamic acid varnish A is applied to the opposite side of the polyimide resin E by 100 μm, and passed through a continuous drying furnace composed of a plurality of furnaces. Dry at 90 ° C. for 2 minutes and 130 ° C. for 1 minute, and further pass through a continuous furnace that is composed of a plurality of furnaces and gradually increases in temperature from the furnace on the sample inlet side to the furnace on the outlet side, Stepwise heating from 130 ° C. to 400 ° C. for a total of 20 minutes was performed to form a polyimide resin A having a thickness of 10 μm as a base material layer to obtain a roll-shaped polyimide resin laminate (laminate 2). .
The thickness of each layer of the laminate 2 was 75 μm for the carrier film, 13 μm for the curl suppression layer, and 10 μm for the base material layer. The layer structure of the laminate 2 is a structure in which the curl suppressing layer 3 and the carrier film 4 are laminated in reverse in FIG. 1, with the curl suppressing layer 3 on one side of the carrier film 4 and the base material layer 2 on the opposite side. Are stacked (form 2).

  Next, for the laminate 2, a touch panel substrate in which a functional layer was formed on the base material layer was completed by the same method as in Example 1.

Example 3
Polyimide acid varnish C was used instead of the polyamic acid varnish A as the base material layer, and the polyamic acid varnish D was used instead of the polyamic acid varnish E as the curl suppression layer. A resin laminate (laminate 3) was obtained.
The thickness of each layer of the laminate 3 was 75 μm for the carrier layer, 12 μm for the base material layer, and 13 μm for the curl suppressing layer.
On this laminated body 2, the ITO and XY circuit were formed by the method similar to Example 1, and the touch panel was obtained.

Example 4
A polyimide resin laminate (laminated body 4) is obtained in the same manner as in Example 1 except that the polyimide film 2 is used as a carrier and the polyamic acid varnish F is used instead of the polyamic acid varnish C as a curl suppressing layer. It was.
The thickness of each layer of the laminate 4 was 75 μm for the carrier layer, 10 μm for the base material layer, and 4 μm for the curl suppressing layer.

Example 5
Polyimide acid varnish H was used instead of polyamic acid varnish A as the base material layer, and polyamic acid varnish E was used instead of polyamic acid varnish B as the curl suppression layer. A resin laminate (laminate 5) was obtained.
The thickness of each layer of the laminate 5 was 75 μm for the carrier layer, 10 μm for the base material layer, and 50 μm for the curl suppression layer.

Example 6
A polyimide resin laminate (laminate 6) was obtained in the same manner as in Example 2 except for the thicknesses of the base material layer and the curl suppressing layer.
The thickness of each layer of the laminate 6 was 75 μm for the carrier layer, 10 μm for the base material layer, and 13 μm for the curl suppressing layer.

Example 7
Polyimide resin laminate in the same manner as in Example 2 except that the polyamic acid varnish A was used instead of the polyamic acid varnish A, and B was used instead of the polyamic acid varnish E as the curl suppression layer. A body (laminate 7) was obtained.
The thickness of each layer of the laminate 7 was 75 μm for the carrier layer, 10 μm for the base material layer, and 15 μm for the curl suppressing layer.

Comparative Example 2
A polyimide resin laminate (laminate C2) was obtained in the same manner as in Example 1, except that the polyamic acid varnish B was used instead of the polyamic acid varnish B as the curl suppressing layer.
The thickness of each layer of the laminate C2 was 75 μm for the carrier layer, 10 μm for the base material layer, and 4 μm for the curl suppressing layer.

Comparative Example 3
A polyimide resin laminate (laminate C3) was obtained in the same manner as in Example 2 except that the polyamic acid varnish E was used instead of the polyamic acid varnish E as the curl suppressing layer.
The thickness of each layer of the laminate C3 was 75 μm for the carrier layer, 10 μm for the base material layer, and 15 μm for the curl suppressing layer.

Comparative Example 4
A polyimide resin laminate (laminate C4) was obtained in the same manner as in Example 1 except that the polyamic acid varnish I was used in place of the polyamic acid varnish B as the curl suppressing layer.
The thickness of each layer of the laminate C4 was 75 μm for the carrier layer, 10 μm for the base material layer, and 13 μm for the curl suppressing layer.

Comparative Example 5
The same procedure as in Example 1 was performed except that polyamic acid H was used instead of polyamic acid A of Example 4 and polyamic acid K was used instead of polyamic acid E.
Polyimide acid varnish H was used instead of polyamic acid varnish A as the base material layer, and polyamic acid varnish K was used as the curl suppression layer instead of polyamic acid varnish B. A resin laminate (laminate C5) was obtained.
The thickness of each layer of the laminate C5 was 75 μm for the carrier layer, 10 μm for the base material layer, and 13 μm for the curl suppressing layer.

  Table 1 shows the physical properties of the polyimide resin laminates obtained in these examples and comparative examples.

DESCRIPTION OF SYMBOLS 1 Functional layer 2 Base material layer 3 Curl suppression layer 4 Carrier layer (carrier film)
DESCRIPTION OF SYMBOLS 10 Laminated body 11 Sputtering device 12, 13 Guide roll 14 Unwinding roll 15 Winding roll

Claims (14)

A polyimide resin laminate in which a curl suppression layer made of a polyimide resin, a carrier layer made of a polyimide resin, and a base material layer made of a polyimide resin are laminated, and on one side of the base material layer, a curl suppression layer and a carrier layer A polyimide resin laminate, wherein the layer is in a peelable manner and the coefficient of thermal expansion (CTE) of the layer in contact with the base material layer is smaller or larger than any of the CTEs of the other layers.   It has a curl suppression layer on one side of the carrier layer, and further has a base material layer that is releasably adhered to the curl control layer, and the thermal expansion coefficient (CTE) of the curl control layer is the heat of the carrier layer and the base material layer. The polyimide resin laminate according to claim 1, which is smaller or larger than any of the coefficient of expansion (CTE).   The polyimide resin laminate according to claim 2, wherein a difference in coefficient of thermal expansion (CTE) between the base material layer and the carrier layer is ± 40 ppm / K or less.   The polyimide resin laminate according to claim 2, wherein a functional layer is further formed on one side of the carrier layer with a curl suppressing layer and a base material layer interposed.   It has a base material layer that is releasably bonded to one side of the carrier layer, has a curl suppression layer on the opposite side of the carrier layer, and has a thermal expansion coefficient (CTE) of the carrier layer and the curl control layer The polyimide resin laminate according to claim 1, which is smaller or larger than any of the thermal expansion coefficients (CTEs).   The polyimide resin laminate according to claim 5, wherein a difference in coefficient of thermal expansion (CTE) between the base material layer and the curl suppressing layer is ± 40 ppm / K or less.   The polyimide resin laminate according to claim 5, wherein a functional layer is further formed on one side of the carrier layer with a base material layer interposed.   The polyimide resin laminate according to claim 2 or 5, wherein the substrate layer has a total light transmittance of 80% or more and a thickness of 50 µm or less.   The polyimide resin laminate according to claim 2 or 5, wherein Tg of the polyimide resin forming the base material layer is 300 ° C or higher.   A polyimide film with a functional layer, wherein the polyimide resin laminate according to claim 4 is used, and the carrier layer and the curl suppressing layer are removed by peeling at the interface between the curl suppressing layer and the base material layer.   A polyimide film with a functional layer, wherein the polyimide resin laminate according to claim 7 is used, and the carrier layer and the curl suppressing layer are removed by peeling at the interface between the carrier layer and the base material layer.   A method for producing a polyimide resin laminate according to claim 1, wherein the curl suppressing layer and the base material layer are coated on the carrier layer by a casting method.   The method for producing a polyimide resin laminate according to claim 13, wherein the curl suppressing layer and the base material layer coated on the carrier layer are integrally cured. The method for producing a polyimide resin laminate according to claim 13, wherein the casting method is coating with a multilayer die or a continuous die.

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