CN107263984B

CN107263984B - Polyimide resin laminate, method for producing same, and polyimide film with functional layer

Info

Publication number: CN107263984B
Application number: CN201710205150.XA
Authority: CN
Inventors: 林信行; 平石克文
Original assignee: Nippon Steel and Sumikin Chemical Co Ltd
Current assignee: Nippon Steel Chemical and Materials Co Ltd
Priority date: 2016-03-31
Filing date: 2017-03-30
Publication date: 2021-01-12
Anticipated expiration: 2037-03-30
Also published as: JP7030418B2; CN107263984A; TW201736139A; KR20170113434A; KR102313706B1; JP2017185806A; TWI719184B

Abstract

The present invention provides a polyimide resin laminate with a carrier used as a substrate instead of glass in a display or a touch panel, which can suppress warpage (curling) as much as possible while maintaining workability in a manufacturing process and thinness of a support base in the display or the touch panel, and can easily and simply separate the support base from the carrier material, even when a heat-resistant resin applicable to an RTR process is used as the carrier material, a method for manufacturing the same, and a polyimide film with a functional layer. The polyimide resin laminate of the present invention has a curl suppression layer containing a polyimide resin on one surface side of a support layer containing a polyimide resin, and further has a base material layer containing a polyimide resin bonded to the curl suppression layer in a releasable manner, and the curl suppression layer has a thermal expansion coefficient smaller or larger than any of the thermal expansion coefficients of the support layer and the base material layer.

Description

Polyimide resin laminate, method for producing same, and polyimide film with functional layer

Technical Field

The present invention relates to a polyimide resin laminate in which a functional layer such as a liquid crystal display device, an organic Electroluminescence (EL) display, an organic EL lighting, electronic paper, a touch panel (touch panel), a color filter (color filter) or the like is formed on a polyimide substrate, a method for producing the same, and a polyimide film with a functional layer.

Background

Display devices such as liquid crystal display devices and organic EL display devices are widely used for large-sized displays such as televisions to small-sized displays such as mobile phones, personal computers (personal computers), and smart phones. For example, an organic EL display device is manufactured by forming a Thin Film Transistor (TFT) on a glass substrate, sequentially forming an electrode, a light-emitting layer, an electrode, and the like, and finally hermetically sealing the resultant structure with a glass substrate, a multilayer Film, or the like.

Here, the type of the display device is not particularly limited, and includes components constituting a display device such as a liquid crystal display device, an organic EL display device, and a display device typified by electronic paper, and a color filter. In addition, various functional devices used in conjunction with the display device include an organic EL lighting device, a touch panel device, a conductive film laminated with Indium Tin Oxide (ITO) or the like, a gas barrier film for preventing permeation of moisture, oxygen, or the like, and components of a flexible circuit board. That is, the flexible element in the present invention includes not only the components of a liquid crystal display device, an organic EL display device, a color filter, and the like, but also one or a combination of two or more of an electrode layer or a light-emitting layer, a gas barrier film, an adhesive film, a Thin Film Transistor (TFT), a wiring layer or a transparent conductive layer of a liquid crystal display device, and the like in an organic EL lighting device, a touch panel device, and an organic EL display device.

By replacing the glass substrate with the resin base material, the display device can be made thinner, lighter, and more flexible, and the applications of the display device can be further expanded. However, resins have problems such as inferior dimensional stability, transparency, heat resistance, moisture resistance, gas barrier property, and the like, compared with glass.

For example, patent document 1 relates to an invention relating to polyimide and its precursor useful as a plastic substrate for flexible displays, and discloses: polyimides produced by reacting tetracarboxylic acids having an alicyclic structure such as cyclohexylphenyltetracarboxylic acid with various diamines have excellent transparency. In addition, attempts have been made to reduce the weight by using a flexible resin base material instead of a glass substrate, and for example, non-patent

documents

1 and 2 propose organic EL display devices using polyimide having high transparency.

As described above, resin films such as polyimide are known to be useful as support substrates for flexible displays, but the manufacturing process of display devices has been carried out using glass substrates, and most of the production facilities thereof have been designed on the premise of using glass substrates. Therefore, it is desirable to be able to effectively utilize existing production equipment and produce display devices.

As one of the examples of the study, there is the following method: a display device including a display portion on a resin base is manufactured by completing a manufacturing process of a predetermined display device in a state where a resin is laminated on a glass substrate and then removing the glass substrate (see patent documents 2 to 3 and non-patent documents 3 to 4). In the case of this method, it is important to separate the resin substrate from the glass without damaging the display portion formed on the resin substrate.

That is, in patent document 3 or non-patent document 3, after a predetermined display portion is formed on a resin base material that is applied to and fixed to a glass substrate, a Laser beam is irradiated from the glass side by a method called an electron beam emission (EPLaR) process, and the resin base material having the display portion is forcibly separated from the glass substrate. In patent document 2 or non-patent document 4, after a release layer is formed on a glass substrate, a polyimide resin one turn larger than the release layer is applied to form a polyimide layer, a cut line reaching the release layer is cut, and a polyimide film one turn smaller is peeled from the release layer.

On the other hand, when a resin is laminated on a glass substrate, warpage becomes a big problem. That is, since the glass substrate has a thermal expansion coefficient of several ppm/K, and the resin generally has a thermal expansion coefficient of several tens ppm/K or more, for example, when a resin solution is applied to the glass substrate, hardened by a heat treatment or the like to form a resin layer, and left to cool to room temperature, warpage occurs. If such warpage cannot be suppressed, it may adversely affect the subsequent formation of a display portion.

In the process using the polyimide laminate, the flexible display TFT substrate process is generally subjected to heat of 350 ℃ or higher using an In-Ga-Zn-O semiconductor (Indium Gallium Zinc Oxide, IGZO) or Low Temperature Polysilicon (LTPS) process. In this case, the glass substrate has a thermal expansion coefficient of several ppm/K, whereas the resin generally has a thermal expansion coefficient of several tens ppm/K or more, and therefore the laminate may warp, and miniaturization of the display portion cannot be achieved.

In this regard, patent document 3 discloses that 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), but the effect of suppressing warpage is insufficient.

In the case of manufacturing a display, a touch panel, or the like in a Roll-to-Roll (hereinafter also referred to as "RTR") manner, a film serving as a support substrate is required to be a material having excellent heat resistance because the film can withstand a high-temperature treatment exceeding 300 ℃. In addition, a thin film is preferable in view of light transmittance. However, the handling of the film is difficult and the production is also difficult, and the transparent film is used to have a thickness of 50 μm or more in the present state.

In addition, as a method of achieving both ease of handling and manufacturing and thinness, a transparent film with a support has been proposed. The carrier-attached laminated film is obtained by laminating a carrier film and a transparent base film without using an adhesive, and by forming a functional layer such as a thin film transistor on the transparent base, then laminating the functional layer to a front panel, and then peeling the carrier film, it is possible to achieve both the workability in the manufacturing process and the thinness of the transparent support base in a display or a touch panel.

However, the conventional carrier-attached laminate film is liable to warp (curl), and the workability in the production process is very poor.

Patent document 4 discloses that a first polyimide layer having a smaller thermal expansion coefficient is provided on a support such as a glass substrate in order to suppress the occurrence of warpage, and a second polyimide layer having a larger thermal expansion coefficient is provided thereon, but does not disclose any studies on a support containing a heat-resistant resin, which is not a glass substrate.

[ Prior art documents ]

[ patent document ]

[ patent document 1] Japanese patent application laid-open No. 2008-231327

[ patent document 2] Japanese patent No. 4834758 publication

[ patent document 3] Japanese patent No. 5408848 publication

[ patent document 4] Japanese patent laid-open No. 2015-182393 publication

[ non-patent document ]

[ non-patent document 1] S.An (S.an), et al, 2.8-inch WQVGA Flexible AMOLED (2.8-inch WQVGA Flexible AMOLED Using High Performance Low Temperature Polysilicon thin film transistors) on a Plastic substrate Using High Performance Low Temperature Polysilicon TFT on Plastic Substrates, summary of information display Association 2010 (SID2010DIGEST), p706(2010)

[ non-patent document 2] Oishi et al, "transparent PI for Flexible Display" (IDW) for International Display research Institute (IDW)' 11 FLX2/FMC4-1

Non-patent document 3 e.i. hasal (e.i. hastal) et al, "Flexible OLED display Made using EPLaR Process (trade with the EPLaR Process)," european display "07, pp.36-39 (2007)

[ non-patent document 4] plum (Cheng-Chung Lee) et al, New method (A Novel Approach to Make Flexible Active Matrix display) of manufacturing Flexible Active Matrix display, Abstract of information display Association 10 (SID10 Digest), pp.810-813 (2010)

Disclosure of Invention

[ problems to be solved by the invention ]

Accordingly, an object of the present invention is to provide a polyimide resin laminate with a carrier, which is used as a substrate instead of glass in a display or a touch panel, and which can maintain the workability in the manufacturing process and the thinness of a support base material in the display or the touch panel, suppress warpage (curling) as much as possible, and easily and simply separate the support base material from the carrier material, even when a heat-resistant resin applicable to an RTR process is used as the carrier material, and a method for manufacturing the same. The invention also provides a polyimide film with a functional layer.

[ means for solving problems ]

As a result of diligent research to solve these problems, the present inventors have surprisingly found that warping (curling) can be improved while maintaining workability and thinness as a base material by laminating a predetermined curl suppression layer containing a polyimide resin and a predetermined support layer containing a polyimide resin on one surface side of a predetermined base material layer containing a polyimide resin, thereby completing the present invention.

That is, the present invention is a polyimide resin laminate which is a laminate comprising a curl suppression layer made of a polyimide resin, a support layer made of a polyimide resin, and a base material layer made of a polyimide resin, wherein the curl suppression layer and the support layer are bonded to one side of the base material layer so as to be separable, and the Coefficient of Thermal Expansion (CTE) of a layer in contact with the base material layer is smaller or larger than the CTE of the other layer.

The polyimide resin laminate of the present invention preferably has a curl suppression layer made of a polyimide resin on one surface side of a support layer made of a polyimide resin, and further has a base material layer made of a polyimide resin bonded to the curl suppression layer so as to be peelable, and the curl suppression layer preferably has a Coefficient of Thermal Expansion (CTE) smaller than or larger than any of the Coefficients of Thermal Expansion (CTE) of the support layer and the base material layer; alternatively, a support layer made of a polyimide resin has a base material layer made of a polyimide resin bonded to one surface of the support layer in a releasable manner, and a curl suppression layer made of a polyimide resin is provided on the opposite surface of the support layer, and the Coefficient of Thermal Expansion (CTE) of the support layer is smaller or larger than those of the base material layer and the curl suppression layer.

In the polyimide resin laminate of the present invention, the difference in Coefficient of Thermal Expansion (CTE) between the base layer and the support layer or the difference in Coefficient of Thermal Expansion (CTE) between the base layer and the curl suppression layer is preferably ± 40ppm/K or less.

The polyimide resin laminate of the present invention can be preferably used as a polyimide resin laminate in which a functional layer is formed on one surface side of a support layer with a curl suppression layer and a base layer interposed therebetween, or a polyimide resin laminate with a functional layer formed on one surface side of a support layer with a base layer interposed therebetween.

The polyimide resin laminate of the present invention preferably has a total light transmittance of the base layer of 80% or more and a thickness of 50 μm or less, and the polyimide resin forming the base layer preferably has a Tg of 300 ℃ or more.

Another embodiment of the present invention is a polyimide film with a functional layer, which is obtained by removing a support layer and a curl suppression layer by peeling at an interface between the curl suppression layer and a base material layer or an interface between the support layer and the base material layer using the polyimide resin laminate with a functional layer.

The present invention also provides a method for producing a polyimide resin laminate, which comprises forming a curl suppressing layer and a base material layer on a support layer by a casting method.

In this production method, the curl suppression layer and the base material layer coated on the support layer are preferably integrally cured, and the casting method is preferably coating using a multilayer die or a continuous die.

[ Effect of the invention ]

According to the present invention, the required properties of the polyimide resin laminate for display and touch panel applications can be satisfied by suppressing warping (curling) as much as possible while maintaining the workability in the manufacturing process and the thinness of the support substrate for display and touch panel.

Drawings

Fig. 1 is a cross-sectional view showing the structure of each layer with a functional layer of the polyimide resin laminate of the present invention.

Fig. 2 is a schematic view of an apparatus for forming a functional layer on a laminate.

Fig. 3 is a simulation diagram showing a state in which a polyimide laminate is warped.

Fig. 4 shows the structure of each layer with a functional layer of the polyimide resin laminate of the present invention.

Description of the symbols

1: functional layer

2: substrate layer

3: support layer

4: curl suppressing layer

10: laminated body

11: sputtering device

12. 13: guide roller

14: winding-out roller

15: winding roller

Detailed Description

First, the polyimide resin laminate of the present invention includes a support layer containing a polyimide resin. The carrier layer maintains the base layer of the thin film in a predetermined shape in the RTR process, and is peeled and removed from the base layer after forming a functional layer such as an ITO film through the base layer. Therefore, in order to adapt to the RTR process, flexibility and reinforcement of the base material layer to maintain strength are required, but transparency is not necessarily required. The thickness of the support layer is therefore greater than that of the base layer of the film, preferably from 10 μm to 100 μm, more preferably from 30 μm to 75 μm. Further, since heat resistance is required for a high-temperature process applicable to RTR, the glass transition temperature (Tg) is preferably 300 ℃ or higher, more preferably 300 to 450 ℃.

The polyimide resin laminate of the present invention is a laminate including a curl suppression layer made of a polyimide resin (hereinafter also simply referred to as "curl suppression layer"), a support layer made of a polyimide resin (hereinafter also simply referred to as "support layer"), and a base material layer made of a polyimide resin (hereinafter also simply referred to as "base material layer"), and the curl suppression layer and the support layer are bonded to one side of the base material layer so as to be separable. Further, the polyimide resin laminate is characterized in that: the layer in contact with the substrate layer has a Coefficient of Thermal Expansion (CTE) that is less than or greater than any of the CTEs of the other layers.

Here, the layer in contact with the base material layer refers to both of the curl suppression layer and the carrier layer. The other layer refers to the base layer and the support layer when the layer in contact with the base layer is the curl suppression layer, and refers to the base layer and the curl suppression layer when the layer in contact with the base layer is the support layer.

The polyimide resin laminate has two types (first type and second type). Hereinafter, each mode will be specifically described.

[ form one ]

The polyimide resin laminate according to the first aspect has a curl suppressing layer on one surface side of the carrier layer, and further has a base material layer bonded to the curl suppressing layer in a releasable manner, and the CTE of the curl suppressing layer is smaller or larger than the CTE of either the carrier layer or the base material layer.

From the viewpoint of suppressing warpage, the CTE of the support layer is preferably close to the CTE of the base layer, and the difference in the coefficients of thermal expansion (also referred to as Δ CTE and "CTE difference") between the two is preferably within ± 15ppm/K, and more preferably within +15ppm/K of the CTE difference of the base layer from the CTE of the support layer, that is, the CTE difference is 0ppm/K to +15 ppm/K. Furthermore, for example, the CTE of the support layer is preferably 10ppm/K to 85 ppm/K. Here, the CTE difference of within "+ -15 ppm/K" means that the CTE difference of the base material layer is-15 ppm/K to +15ppm/K as compared with the CTE of the support layer.

The support layer has a base material layer on one surface side thereof with a curl suppression layer described later interposed therebetween. The substrate layer is a transparent substrate that replaces glass, and is a support functional layer after a functional layer such as an ITO film is formed on the substrate layer and an RTR process is completed, and the carrier layer is peeled off and removed. Therefore, the substrate 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 small as possible, preferably 50 μm or less, and more preferably 5 to 25 μm, from the viewpoint of the required characteristics of reduction in thickness, weight, and flexibility. As described above, the CTE of the substrate layer is preferably approximately equal to the CTE of the support layer, and preferably 10ppm/K to 80 ppm/K. Further, since heat resistance applicable to a high temperature process of RTR is required, the glass transition temperature (Tg) of the base layer is preferably 300 ℃ or higher, more preferably 300 to 450 ℃. Since the substrate is used as a resin substrate instead of glass, the elastic modulus of the substrate layer is preferably 2GPa to 15GPa, for example.

A curl suppressing layer made of a polyimide resin is provided on one surface side of the support layer between the support layer and the base material layer. In order to suppress warpage of the substrate layer with the carrier as much as possible in the RTR process, the curl suppression layer is formed between the carrier layer and the substrate layer, and after the RTR process is completed by forming a functional layer such as an ITO film on the carrier layer and the curl suppression layer via the substrate layer, the curl suppression layer is removed together with the carrier layer when the carrier layer is peeled off and removed. Therefore, the thickness or thermal expansion coefficient is selected in order to try to suppress warpage (curling) in the RTR process. Therefore, the thickness of the curl suppressing layer is preferably 50 μm or less, and more preferably 5 μm to 30 μm. Further, since heat resistance is required for a high-temperature process applicable to RTR, the glass transition temperature (Tg) is preferably 300 ℃ or higher, more preferably 300 to 450 ℃.

The CTE of the curl suppression layer is selected to be relatively large compared to the CTE of the carrier and substrate layers. For example, although the CTE of the support layer and the CTE of the base material layer may not necessarily be the same, it is preferable to select the CTE of the curl suppression layer to be a difference of a certain value or more with respect to the CTE of both the support layer and the base material layer.

Therefore, the CTE difference between the CTE of the curl suppressing layer and the CTE of the support layer and the CTE of the base material layer are preferably within a range of. + -. 15ppm/K or more, and more preferably within a range of-15 ppm/K to-60 ppm/K. The CTE of the curl suppressing layer is preferably-10 ppm/K to 20 ppm/K. Here, the CTE difference of "+/-15 ppm/K or more" means that the CTE difference of the curl suppression layer is more than-15 ppm/K or more than +15ppm/K as compared with the CTE of the support layer and the CTE of the base layer.

Even when a substrate with a carrier, which is formed of a carrier layer and a base material layer, is formed into a relatively large laminate, which corresponds to the fourth generation (680mm × 880mm to 730mm × 920mm) and later, of a so-called glass substrate, in particular, by providing a curl suppression layer between the carrier layer and the base material layer, a sufficient effect of suppressing warpage can be obtained. In addition, the presence of the curl suppression layer can improve the degree of freedom in designing the base material layer. Further, foreign matter adhering to the carrier layer is less likely to be mixed into the base material layer. Further, since the surface state of the support layer does not easily affect the base material layer, an inexpensive polyimide film or the like can be selected, and the degree of freedom in designing the support layer can be improved.

[ second form ]

The polyimide resin laminate of the second embodiment has a base material layer bonded to one surface of the support layer so as to be peelable, and further has a curl suppression layer on the opposite surface of the support layer, and the CTE of the support layer is smaller or larger than the CTE of the base material layer and the CTE of the curl suppression layer.

That is, the carrier layer is located between the base layer and the curl suppression layer. This configuration is preferable from the viewpoint of suppressing warpage. Furthermore, for example, the CTE of the support layer is preferably 10ppm/K to 70 ppm/K.

The substrate layer is a transparent substrate that replaces glass, and is a transparent substrate that supports the functional layer after the functional layer such as an ITO film is formed thereon and the RTR process is completed and the carrier layer is peeled off. Therefore, the substrate layer preferably has a total light transmittance of 80% or more, more preferably 90% or more. From the viewpoint of the required properties of reduction in thickness, weight, and flexibility, the thickness of the base material layer is preferably as thin as possible within a range not impairing workability, and is preferably 50 μm or less, and more preferably 5 to 25 μm. The CTE of the base material layer is preferably 1ppm/K to 80 ppm/K.

Further, since heat resistance is required for a high-temperature process applicable to RTR, the glass transition temperature (Tg) is preferably 300 ℃ or higher, more preferably 300 to 450 ℃. Since the substrate is used as a resin substrate instead of glass, the elastic modulus of the substrate layer is preferably 2GPa to 15GPa, for example.

The opposite surface side of the support layer is provided with a curl suppression layer containing polyimide resin. In order to suppress warpage of the base layer with the carrier in the RTR process, the curl suppression layer is formed on the opposite side of the base layer, and after the RTR process is completed by forming a functional layer such as an ITO film on the carrier layer through the base layer, the curl suppression layer is removed together with the carrier layer when the carrier layer is peeled off and removed. Therefore, the thickness or thermal expansion coefficient is selected in order to try to suppress warpage (curling) in the RTR process. Therefore, the thickness of the curl suppressing layer is preferably 50 μm or less, and more preferably 6 to 30 μm. Further, since heat resistance is required for a high-temperature process applicable to RTR, the glass transition temperature (Tg) is preferably 300 ℃ or higher, more preferably 300 to 450 ℃.

The CTE of the curl suppression layer is preferably similar to the CTE of the substrate layer, and is preferably selected so as to eliminate the CTE difference between the carrier layer and the substrate 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 1ppm/K to 90 ppm/K.

Even when a substrate with a carrier, which is formed of a carrier layer and a base material layer, is provided on the opposite side of the substrate with a curl suppression layer, a relatively large laminate corresponding to the fourth generation (680mm × 880mm to 730mm × 920mm) and later of the so-called glass substrate can be obtained in particular, and a sufficient effect of suppressing warpage can be obtained. In addition, the presence of the curl suppression layer can improve the degree of freedom in designing the base material layer.

Hereinafter, the common contents of the embodiment 1 and the embodiment 2 will be specifically described.

The polyimide resin used as the curl suppression layer is not particularly limited as long as the above-described properties are satisfied, and for example, the polyimide resin is formed of a polyimide having a structural unit represented by the following general formula (1). Preferably, the polyimide contains 50 mol% or more of a structural unit represented by the following general formula (1).

[ solution 1]

Wherein X in the general formula (1) is an aromatic group or an alicyclic group, and is a tetravalent organic group having one or more aromatic rings or alicyclic rings, and R is a substituent having 1 to 6 carbon atoms. Among them, suitable specific examples of the raw material for forming the group X include: pyromellitic dianhydride (PMDA), Naphthalene-2, 3, 6, 7-tetracarboxylic acid dianhydride (naphalene tetraca)rbctic dianhydrides, NTCDA), 3 ', 4, 4' -biphenyltetracarboxylic dianhydride (BPDA), and the like. Further, a suitable specific example of R is, for example, -CH₃、-CF₃And the like.

Wherein, if R is-CF₃The releasability at the interface with the base material layer can be improved, and these layers can be easily separated.

Further, as the structural unit which may be contained in addition to the structural unit represented by the above general formula (1), and preferably may be contained at most less than 50 mol%, structural units using a general acid anhydride and diamine are exemplified. Among them, examples of the acid anhydride which can be suitably used include pyromellitic dianhydride (PMDA), naphthalene-2, 3, 6, 7-tetracarboxylic dianhydride (NTCDA), 3 ', 4, 4 ' -biphenyltetracarboxylic dianhydride (BPDA), cyclohexanetetracarboxylic dianhydride, phenylenebis (trimellitic acid 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, and 4, 4 ' - (2, 2 ' -hexafluoroisopropylidene) bisphthalic dianhydride. On the other hand, the diamine includes m-phenylenediamine, p-phenylenediamine, 2, 4-diaminotoluene, 4 ' -diaminodiphenyl ether, 1, 3-bis (4-aminophenoxy) benzene, 4 ' -diaminodiphenyl sulfone, 2-bis (4-aminobenzyloxyphenyl) propane, bis [4- (4-aminophenoxy) phenyl ] sulfone, 4 ' -diaminobenzanilide, 9-bis (4-aminophenyl) fluorene, and the like.

In general, when the thermal expansion coefficient of polyimide is small, the transparency is lowered, and retardation (retardation) in the thickness direction (retardation) is high. It is therefore not suitable for the following cases: after the RTR process is completed, the substrate layer separated from the carrier layer is used as, for example, a resin substrate for a display device, or a gas barrier film, a touch panel substrate. In contrast, in the present invention, the presence of the opposite-side curl suppression layer allows the use of a base material layer having a larger thermal expansion coefficient than the carrier layer.

The polyimide forming the base layer may be appropriately selected depending on the use of the polyimide resin laminate. Among them, in the case of a flexible resin substrate used for a display device such as a liquid crystal display device, an organic EL display device, electronic paper, a color filter, or a touch panel, a polyimide having a structural unit represented by the following general formula (2) is exemplified, and a polyimide containing 50 mol% or more of the structural unit represented by the general formula (2) is preferable. Further, as for the structural unit that may be contained in addition to the structural unit represented by the general formula (2) (preferably, the structural unit may be contained at most by less than 50 mol%), the same structural units as those described in the general formula (1) may be mentioned as long as transparency is not impaired. Acid anhydrides which can be suitably used are pyromellitic dianhydride (PMDA), naphthalene-2, 3, 6, 7-tetracarboxylic dianhydride (NTCDA), 3 ', 4, 4 ' -biphenyltetracarboxylic dianhydride (BPDA), cyclohexanetetracarboxylic dianhydride, phenylenebis (trimellitic acid 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) bisphthalic dianhydride and the like. On the other hand, the diamine is m-phenylenediamine, p-phenylenediamine, 2, 4-diaminotoluene, 4 ' -diaminodiphenyl ether, 1, 3-bis (4-aminophenoxy) benzene, 4 ' -diaminodiphenyl sulfone, 2-bis (4-aminobenzyloxyphenyl) propane, bis [4- (4-aminophenoxy) phenyl ] sulfone, 4 ' -diaminobenzanilide, 9-bis (4-aminophenyl) fluorene, or the like.

[ solution 2]

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

[ solution 3]

Among them, from the viewpoint of obtaining a polyimide resin having a transmittance of 80% or more at 500nm in a wavelength range of 440nm to 780nm and a retardation in the thickness direction of 200nm or less as a base layer, any of the following is more preferable.

[ solution 4]

The polyimide resin represented by the following formula (4) is most suitable.

[ solution 5]

The polyimide resin used as the support layer is not particularly limited as long as the above-described properties are satisfied, and examples of commonly available polyimide resins include Kapton (Kapton) (manufactured by Toray-Dupont), Upilex (Upilex) (manufactured by yukyo), arbicar (apic) (manufactured by zenith (Kaneka)) and commercially available polyimides having a structure similar to those of polyimide resins, and can be synthesized from diamines and acid dianhydrides as described in detail below.

The various polyimides described above are obtained by imidizing a polyimide precursor (hereinafter also referred to as "polyamic acid"), and a resin solution of polyamic acid can be obtained by reacting a diamine and an acid dianhydride, which are substantially equimolar in an organic solvent, as raw materials. In detail, it can be obtained, for example, by: diamine is dissolved in an organic polar solvent such as N, N-dimethylacetamide under a nitrogen stream, and then tetracarboxylic dianhydride is added to the solution to react at room temperature for about 5 hours. Here, the weight average molecular weight (Mw) of the polyamic acid is preferably about 1 to 30 ten thousand from the viewpoint of uniformity of film thickness at the time of coating or mechanical strength of the polyimide obtained. A suitable molecular weight range of the polyimide resin is the same molecular weight range as that of the polyamic acid.

The base layer and the curl suppression layer of the present invention are preferably obtained by a so-called casting method in which a resin solution of polyimide or a polyimide precursor is applied, dried, and heat-treated. That is, when the polyimide resin laminate of the present invention is obtained, it is preferable that a resin solution of polyimide or a polyimide precursor is applied to one surface side or both surfaces of the support layer, dried, and heat-treated to form a base layer and a curl suppression layer. For example, it is preferable to perform a preliminary heat treatment at 90 to 130 ℃ for about 5 to 30 minutes for drying or the like, and then perform a high-temperature heat treatment at 130 to 360 ℃ for about 10 to 240 minutes for imidization.

The polyimide resin laminate obtained in this manner can be separated at the interface between the base material layer and the layer (support layer or curl suppression layer) in contact with the base material layer, but in order to facilitate separation at the interface between these layers, it is preferable that the base material layer is preferably 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 can be preferably 1N/m to 200N/m, more preferably 1N/m to 100N/m, and therefore, for example, the polyimide has separability to such an extent that the polyimide can be easily peeled by hand. The separation surface of the base material layer maintains the surface roughness (typically, the surface roughness Ra is about 1nm to 80 nm) obtained by the casting method as it is, and therefore, does not adversely affect the visibility of the display device and the like.

In the present invention, the warp deformation (warp amount) of the polyimide resin laminate obtained by laminating different materials can be calculated by the following idea, and the polyimide resin laminate can be optimized. That is, based on simple material mechanics calculation based on the idea of cited document 4, the influence of the own weight is calculated by three-dimensional material mechanics calculation, and then the warp deformation (warp amount) is added to obtain the final warp amount. As a calculation method, a finite element method (i.e., a method of discretizing a final warp deformation in a state of thermal deformation and weight balance by using a shell element) and performing a calculation by a computer in a numerical calculation manner is used (see fig. 3).

As described above, the polyimide resin laminate of the present invention can be suitably used for obtaining a display device having a functional member on a base material layer. That is, after a predetermined functional layer is formed on the base layer, the separation may be performed at the interface between the curl suppression layer and the base layer or at the interface between the base layer and the support layer. Here, the carrier layer functions as a base when forming the display portion on the base material layer side, and ensures handling properties, dimensional stability, and the like of the base material layer in the manufacturing process of the display portion, but is finally removed without constituting a display device. Similarly, the curl suppressing layer is also separated together with the carrier layer, and similarly, is finally removed, and does not constitute a display device, and even if the transparency is poor, the curl suppressing layer may be formed. By using such a polyimide resin laminate, a predetermined functional layer can be formed on a base material layer with good accuracy and reliability, and a thin, lightweight, and flexible display device can be obtained.

The functional layer formed on the base material layer is not particularly limited. For example, in the case of an organic EL display device, an organic EL element including a TFT, an electrode, and a light-emitting layer typically corresponds to a display portion. In the case of a liquid crystal display device, the functional layer is a TFT, a driver circuit, a color filter, or the like as necessary. In addition to these, various display devices such as electronic paper and Micro-Electro-Mechanical systems (MEMS) display devices are included, and components necessary for displaying a predetermined image (moving image or image) as various functional layers formed on a glass substrate in the past correspond to a display unit. Among these, for example, an annealing process of about 400 ℃ is usually required for forming a TFT, but the polyimide resin laminate of the present invention has heat resistance that can withstand such an annealing process.

[ examples ]

The present invention will be specifically described below with reference to examples and comparative examples. The present invention is not limited to these contents.

1. Method for measuring various physical properties and testing performance

[ peeling Strength ]

The peel strength between the substrate layer (curl suppression layer) and the carrier layer was measured by processing the laminate into a short strip having a width of 1mm to 10mm and a length of 10mm to 25mm, and peeling the carrier layer in a 180 ° direction using a tensile tester (strorograph-M1) manufactured by toyoyo seiki co. Further, a case where the peeling strength is strong and peeling is difficult is regarded as "peeling impossible".

[ transmittance ]

A substrate layer having a thickness of 20 μm was cut out in a 5cm square, and the transmittance thereof was measured at 380nm to 780nm using a HAZE METER (HAZE Meter) NDH-5000 manufactured by Nippon Denshoku industries.

[Ra]

The substrate layer, the carrier layer and the curl suppression layer were cut out individually at 3cm square, and Ra was measured using an Atomic Force Microscope (AFM) manufactured by Bruker element analysis (Bruker AXS).

[CTE]

The CTE of the base layer, carrier layer and curl suppressing layer was measured by cutting each layer at a 3mm × 15mm square, performing a tensile test at a temperature range of 30 to 260 ℃ at a constant temperature rise rate (10 ℃/min) while applying a load of 5.0g using a Thermo Mechanical Analysis (TMA) apparatus manufactured by a fine tool (Seiko Instruments), and measuring the CTE (× 10 × 15) from the elongation of the polyimide film at a temperature of 100 to 250 ℃ against the temperature^-6/K)。

[ warping ]

A square sample having one side of 100mm was cut out from the laminated film with a cutter knife (cutterknife), conditioned at 23 ℃ for 24 hours at 50%, placed on a surface plate, and the warp height at four corners was measured with a vernier caliper (vernier caliper), and the average value thereof was defined as the warp (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 Compound ]

4, 4 '-diamino-2, 2' -bis (trifluoromethyl) biphenyl (TFMB)

2, 2 '-dimethyl-4, 4' -diaminobiphenyl (m-TB)

1, 3-bis (4-aminophenoxy) benzene (TPE-R)

2, 2-bis [4- (4-aminophenoxy) phenyl ] propane (BAPP)

1, 4-phenylene diamine (PPD)

[ acid anhydride of aromatic tetracarboxylic acid ]

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

TFMB (9.4g, 0.03mol) was added to 127.5g of DMAc as a solvent while stirring in a 300ml separable flask under a nitrogen stream, and the mixture was warmed and dissolved at 50 ℃. Then 6FDA (13.09g, 0.03mol) was added. The molar ratio of diamine to acid anhydride was set to substantially 1: 1. Then, the solution was stirred at room temperature for another 3 hours to effect polymerization, and 200g of a pale yellow viscous polyamic acid varnish A was obtained. Further, the polyamic acid varnish a is hardened under heating conditions described later, thereby obtaining a polyimide resin a.

Synthesis example 2

10.2g of m-TB and 1.6g of TPE-R were added to 170g of DMAc solvent in a molar ratio of 90: 10 in a 300ml separable flask with stirring under a nitrogen stream, warmed and dissolved at 50 ℃. 9.2g of PMDA and 3.1g of BPDA were then added in a molar ratio of 90: 10. The molar ratio of diamine to acid anhydride was set to substantially 1: 1. Then, the solution was stirred at room temperature for 3 hours to effect polymerization, thereby obtaining 200g of a pale viscous polyamic acid varnish B. Further, the polyamic acid varnish B is hardened under heating conditions described later, thereby obtaining a polyimide resin B.

Synthesis example 3

TFMB (12.6g, 0.04mol) was added to 127.5g of DMAc as a solvent while stirring in a 300ml separable flask under a nitrogen stream, and the mixture was warmed and dissolved at 50 ℃. 6FDA (2.2g, 0.005mol) and PMDA (7.7g, 0.035mol) were then added in a molar ratio of 12.5: 87.5. The molar ratio of diamine to acid anhydride was set to substantially 1: 1. Then, the solution was stirred at room temperature for 3 hours to effect polymerization, and 150g of a pale viscous polyamic acid varnish C was obtained. Further, the polyamic acid varnish C is hardened under heating conditions described later, thereby obtaining a polyimide resin C.

Synthesis example 4

m-TB (14.4g, 0.07mol) was added to 170g of DMAc as a solvent while stirring in a 300ml separable flask under a nitrogen stream, and the mixture was heated and dissolved at 50 ℃. Then the speed of 90: PMDA (13.6g, 0.06mol) and BPDA (2g, 0.007mol) were added at a molar ratio of 10. The molar ratio of diamine to acid anhydride was set to substantially 1: 1. Then, the solution was stirred at room temperature for 3 hours to effect polymerization, thereby obtaining 200g of a pale viscous polyamic acid varnish D. Further, this polyamic acid varnish D is hardened under heating conditions described later, thereby obtaining a polyimide resin D.

Synthesis example 5

TPE-R (14.8g, 0.05mol) as a diamine was added to 170g of DMAc as a solvent while stirring in a 300ml separable flask under a nitrogen stream, and the mixture was heated and dissolved at 50 ℃. BPDA (15.2g, 0.05mol) was then added as the anhydride. The molar ratio of diamine to acid anhydride was set to substantially 1: 1. Then, the solution was stirred at room temperature for 3 hours to effect polymerization, thereby obtaining 200g of a pale viscous polyamic acid varnish E. Further, the polyamic acid varnish E is hardened under heating conditions described later, thereby obtaining a polyimide resin E.

Synthesis example 6

In a 300ml separable flask, the mixture was stirred while stirring under a nitrogen flow at a ratio of m-TB: TPE-R was added to 170g of DMAc as a solvent in a molar ratio of 90: 10, and the mixture was heated and dissolved at 50 ℃. Then, the mixture was added so that the molar ratio of PMDA to BPDA became 80: 20. The molar ratio of diamine to acid anhydride was set to substantially 1: 1. Then, the solution was stirred at room temperature for 3 hours to effect polymerization, thereby obtaining 200g of a pale viscous polyamic acid F varnish. Further, the polyamic acid F varnish was hardened under heating conditions described later, thereby obtaining a polyimide resin F.

Synthesis example 7

TFMB (16.93g) was added to and dissolved in DMAc (170g) solvent in a 300ml separable flask with stirring under a nitrogen stream. PMDA (10.12g) and 6FDA (2.95g) were then added. Then, the solution was stirred at room temperature for another 6 hours to effect polymerization, thereby obtaining 200g of a pale yellow viscous polyamic acid H varnish. Further, the polyamic acid H varnish was hardened under heating conditions described later, thereby obtaining a polyimide resin H.

Synthesis example 8

BAPP (19.45g) was added to and dissolved in DMAc (170g) solvent in a 300ml separable flask with stirring under a nitrogen stream. Then PMDA (9.85g) and BPDA (0.70g) were added. Then, the solution was stirred at room temperature for another 6 hours to effect polymerization, thereby obtaining 200g of a pale yellow viscous polyamic acid I varnish. Further, the polyamic acid I varnish was hardened under heating conditions described later, thereby obtaining a polyimide resin I.

Synthesis example 9

4, 4' -DAPE (8.97g) was added to DMAc (170g) as a solvent in a 300ml separable flask with stirring under a nitrogen stream and dissolved. Then PMDA (8.95g) and BPDA (12.08g) were added. Then, the solution was stirred at room temperature for 6 hours to effect polymerization, thereby obtaining 200g of brown viscous polyamic acid J varnish. Further, the polyamic acid J varnish was hardened under heating conditions described later, thereby obtaining a polyimide resin J.

Synthesis example 10

4, 4' -DAPE (8.14g) and PPD (4.40g) were added to and dissolved in DMAc (170g) solvent in a 300ml separable flask under a nitrogen stream with stirring. PMDA (17.45g) was then added. Then, the solution was stirred at room temperature for 6 hours to effect polymerization, thereby obtaining 200g of brown viscous polyamic acid K varnish. Further, the polyamic acid K varnish was hardened under heating conditions described later, thereby obtaining a polyimide resin K.

3. Formation of Polyimide (PI) layer by coating

A polyimide film (manufactured by Ningbo Jinshan of China, thickness 0.75mm, CTE 45ppm/K, hereinafter also referred to as "carrier film") was used as the carrier film.

As the support layer, 2 kinds of polyimide films were used.

1) Polyimide film 1: manufactured by Ningbo Jinshan, China, with a thickness of 0.75mm, a CTE of 45ppm/K, and a Ra of 3nm (hereinafter also referred to as carrier film 1)

2) Polyimide film 2: manufactured by Rayitek, china, having a thickness of 0.75mm, a CTE of 45ppm/K, and an Ra of 10nm (hereinafter also referred to as carrier film 2)

Example 1

The polyamic acid varnish B was applied to a film thickness of 45 μm by a moro pump while winding out the carrier film 1 (width 520mm × length 500m × thickness 75 μm) at a speed of 2m/min by using an RTR type coating, drying and curing apparatus shown in fig. 2, for example, which includes a winding-out section, a lip coater (lip coater), a continuous drying furnace, a continuous furnace, and a winding section. The film was passed through a continuous drying furnace composed of a plurality of furnaces, dried at 90 ℃ for 2 minutes and at 130 ℃ for 1 minute, and further passed through a continuous drying furnace composed of a plurality of furnaces, in which the temperature was increased stepwise from the furnace on the sample inlet side to the furnace on the sample outlet side, and the film was heated stepwise from 130 ℃ to 400 ℃ in 25 minutes in total, to produce a roll having a polyimide resin B as a curl suppressing layer formed on a carrier film. Then, the roll was set in the unwinding section of the same coating and drying apparatus, and a polyimide resin laminate (laminate 1) having a thickness of 10 μm as a base material layer was obtained by coating a polyimide acid varnish a having a thickness of 100 μm on a polyimide resin C, passing the roll through a continuous drying furnace composed of a plurality of furnaces, drying the roll at 90 ℃ for 2 minutes, drying the roll at 130 ℃ for 1 minute, further passing the roll through a continuous furnace composed of a plurality of furnaces and having a temperature gradually increased from the furnace on the sample inlet side to the furnace on the sample outlet side, and gradually heating the roll from 130 ℃ to 400 ℃ for 20 minutes in total, thereby obtaining a polyimide resin laminate having a roll shape (laminate 1).

The thicknesses of the layers of the laminate 1 were 75 μm for the carrier layer, 4.5 μm for the curl suppression layer and 10 μm for the base layer. The layer structure of the laminate 1 is schematically shown in fig. 1.

Then, the rolled polyimide resin laminate was fed into a process treatment section provided in a vacuum chamber via a transport roller while being rolled out in the longitudinal direction with a base material layer facing upward at a speed of 2m/min using an RTR system apparatus provided with a roll-out section, a transport roller, a process treatment section, and a winding section, and was rolled up as a polyimide plate film with a functional layer by forming ITO as the functional layer having a thickness of 50nm on the base material layer by a continuous process by a sputtering method.

Further, the polyimide substrate film with the functional layer was cut into a sheet shape of 370mm × 450mm, and transparent circuit processing was performed on the deposited ITO in the XY direction in one direction (X direction) and the other direction (Y direction). At this time, no circuit is formed at the intersection of the Y circuit and the X circuit.

Then, an overcoat agent (over coating) was applied to the intersection points of the XY circuits, the resultant was heat-treated at 250 ℃ to harden the overcoat layer, a silver paste was used to bridge across the overcoat layer to form the XY circuits, the overcoat agent was applied to the entire surface on the ITO film formation side, and annealing treatment was performed at 270 ℃ to harden the overcoat agent and crystallize ITO.

Finally, an Optically Clear Adhesive tape (OCA) (transparent Adhesive sheet) was attached to the surface of the cover glass (cover glass) on the ITO film side, and then the carrier film and the curl suppression layer were mechanically peeled off to prepare a touch panel substrate having a functional layer formed on the base layer.

Comparative example 1

A polyimide resin a (thickness 10 μm) as a base layer was formed on the carrier film in the same manner as in example 1 without forming a curl suppression layer, to obtain a polyimide resin laminate (laminate C1).

This laminate C1 has a large warpage (curl), and when the ITO film is cut into a sheet shape in the touch panel manufacturing process, alignment with the mask is not performed due to the warpage, and the XY-direction transparent circuit processing is not performed, and thus the touch panel cannot be manufactured.

Example 2

The polyamic acid varnish E was applied to a film thickness of 100 μm by a mohno pump while winding out a carrier film (width 520mm × length 500m × thickness 75 μm) at a speed of 2m/min by using an RTR coating, drying and curing apparatus shown in fig. 2, for example, which includes a winding-out section, a lip coater, a continuous drying furnace, a continuous furnace, and a winding section. The film was passed through a continuous drying furnace composed of a plurality of furnaces, dried at 90 ℃ for 2 minutes and at 130 ℃ for 1 minute, to prepare a roll having a polyimide resin E as a curl suppression layer formed on a carrier film. Then, the roll was set in the unwinding section of the same coating and drying apparatus, and a polyamic acid varnish a of 100 μm was applied to the opposite side of a polyimide resin E, passed through a continuous drying furnace composed of a plurality of furnaces, dried at 90 ℃ for 2 minutes, dried at 130 ℃ for 1 minute, further passed through a continuous furnace composed of a plurality of furnaces and having a temperature gradually increased from the furnace on the sample inlet side to the furnace on the sample outlet side, and gradually heated from 130 ℃ to 400 ℃ for 20 minutes in total, to form a polyimide resin a having a thickness of 10 μm as a base material layer, thereby obtaining a rolled 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 layer. The layer structure of the laminate 2 is schematically shown in fig. 4.

Then, a touch panel substrate having a functional layer formed on a base material layer was produced for the laminate 2 in the same manner as in example 1.

Example 3

A polyimide resin laminate (laminate 3) was obtained in the same manner as in example 2, except that polyamic acid varnish C was used as the base material layer in place of polyamic acid varnish a, and polyamic acid varnish D was used as the curl suppression layer in place of polyamic acid varnish E.

The thicknesses of the layers of the laminate 3 were 75 μm for the support layer, 12 μm for the base layer and 13 μm for the curl suppression layer.

ITO and an XY circuit were formed on the laminate 3 in the same manner as in example 1 to obtain a touch panel.

Example 4

A polyimide resin laminate (laminate 4) was obtained in the same manner as in example 1, except that the polyimide film 2 was used as the support layer and the polyamic acid varnish F was used as the curl suppression layer instead of the polyamic acid varnish C.

The thicknesses of the layers of the laminate 4 were 75 μm for the support layer, 10 μm for the base layer and 4 μm for the curl suppression layer.

Example 5

A polyimide resin laminate (laminate 5) was obtained in the same manner as in example 1, except that polyamic acid varnish H was used as the base layer in place of polyamic acid varnish a, and polyamic acid varnish E was used as the curl suppression layer in place of polyamic acid varnish B.

The thicknesses of the layers of the laminate 5 were 75 μm for the support layer, 10 μm for the base 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 suppression layer.

The thicknesses of the layers of the laminate 6 were 75 μm for the support layer, 10 μm for the base layer and 13 μm for the curl suppression layer.

Example 7

A polyimide resin laminate (laminate 7) was obtained in the same manner as in example 2, except that polyamic acid varnish H was used as the base material layer in place of polyamic acid varnish a, and polyamic acid varnish B was used as the curl suppression layer in place of polyamic acid varnish E.

The thicknesses of the layers of the laminate 7 were 75 μm for the support layer, 10 μm for the base layer and 15 μm for the curl suppression layer.

Comparative example 2

A polyimide resin laminate (laminate C2) was obtained in the same manner as in example 1, except that polyamic acid varnish I was used instead of polyamic acid varnish B as the curl suppression layer.

The thicknesses of the layers of laminate C2 were 75 μm for the carrier layer, 10 μm for the base layer and 4 μm for the curl suppression layer.

Comparative example 3

A polyimide resin laminate (laminate C3) was obtained in the same manner as in example 2, except that polyamic acid varnish J was used instead of polyamic acid varnish E as the curl suppression layer.

The thicknesses of the layers of laminate C3 were 75 μm for the carrier layer, 10 μm for the base layer and 15 μm for the curl suppression layer.

Comparative example 4

A polyimide resin laminate (laminate C4) was obtained in the same manner as in example 1, except that polyamic acid varnish I was used instead of polyamic acid varnish B as the curl suppression layer.

The thicknesses of the layers of laminate C4 were 75 μm for the carrier layer, 10 μm for the base layer and 13 μm for the curl suppression layer.

Comparative example 5

The operation was performed in the same manner as in example 1 except that polyamic acid H was used instead of polyamic acid a in example 4 and polyamic acid K was used instead of polyamic acid E.

A polyimide resin laminate (laminate C5) was obtained in the same manner as in example 1, except that polyamic acid varnish H was used as the base material layer in place of polyamic acid varnish a, and polyamic acid varnish K was used as the curl suppression layer in place of polyamic acid varnish B.

The thicknesses of the layers of laminate C5 were 75 μm for the carrier layer, 10 μm for the base layer and 13 μm for the curl suppression layer.

The physical properties of the polyimide resin laminates obtained in the above examples and comparative examples are shown in table 1.

Claims

1. A polyimide resin laminate which is a laminate comprising a curl suppression layer of a polyimide resin, a support layer comprising a polyimide resin, and a base material layer comprising a polyimide resin, and which is characterized in that: the curl suppressing layer and the carrier layer are bonded to one surface of the base layer so as to be peelable from each other, and a layer in contact with the base layer has a thermal expansion coefficient smaller or larger than that of another layer.

2. The polyimide resin laminate according to claim 1, wherein the curl suppressing layer is provided on one surface side of the carrier layer, and further the base material layer is bonded to the curl suppressing layer in a peelable manner, and a thermal expansion coefficient of the curl suppressing layer is smaller or larger than those of the carrier layer and the base material layer.

3. The polyimide resin laminate according to claim 2, wherein the difference in the thermal expansion coefficients between the base layer and the support layer is ± 40ppm/K or less.

4. The polyimide resin laminate according to claim 2, wherein a functional layer is further formed on one surface side of the support layer with the curl suppression layer and the base material layer interposed therebetween.

5. The polyimide resin laminate according to claim 1, wherein the base layer is releasably bonded to one surface side of the support layer, and the curl suppression layer is provided on the opposite surface side of the support layer, and the thermal expansion coefficient of the support layer is smaller or larger than the thermal expansion coefficients of the base layer and the curl suppression layer.

6. The polyimide resin laminate according to claim 5, wherein the difference in thermal expansion coefficient between the base layer and the curl suppression layer is ± 40ppm/K or less.

7. The polyimide resin laminate according to claim 5, wherein a functional layer is further formed on one surface side of the support layer with the base layer interposed therebetween.

8. The polyimide resin laminate according to claim 2 or 5, wherein the base material layer has a total light transmittance of 80% or more and a thickness of 50 μm or less.

9. The polyimide resin laminate according to claim 2 or 5, wherein a glass transition temperature of the polyimide resin forming the base layer is 300 ℃ or higher.

10. A polyimide film with a functional layer, characterized in that: the polyimide resin laminate according to claim 4, wherein the carrier layer and the curl suppression layer are removed by peeling at the interface between the curl suppression layer and the base material layer.

11. A polyimide film with a functional layer, characterized in that: the polyimide resin laminate according to claim 7, wherein the carrier layer and the curl suppressing layer are removed by peeling at the interface between the carrier layer and the base material layer.

12. A method for producing a polyimide resin laminate, which is a method for producing the polyimide resin laminate according to claim 1, and is characterized in that: the curl suppressing layer and the base material layer are coated on the carrier layer by a casting method.

13. The method of manufacturing a polyimide resin laminate according to claim 12, wherein the curl suppression layer and the base material layer applied to the support layer are integrally cured.

14. The method for producing a polyimide resin laminate according to claim 13, wherein the casting method is coating using a multilayer die or a continuous die.