JP7030418B2 - Polyimide resin laminate and its manufacturing method - Google Patents

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, an 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 displays 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, the electrode, a light emitting layer, an electrode, and the like are separately hermetically sealed with a glass substrate, a multilayer thin film, and the like.

Here, the type of display device is not particularly limited, but includes components of a display device such as a liquid crystal display device, an organic EL display device, a display device such as electronic paper, and a color filter. In addition, it accompanies the display device including an organic EL lighting device, a touch panel device, a conductive film on which ITO and the like are laminated, 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 an organic EL display device, and the like. It also includes one type or a combination of two or more types such as a gas barrier film, an adhesive film, a thin film transistor (TFT), a wiring layer of a liquid crystal display device, or a transparent conductive layer.

By replacing the glass substrate with a resin base material, it is possible to realize thinning, weight reduction, and flexibility, and it becomes possible to further expand the use of the display device. However, the resin has a problem that it is inferior in dimensional stability, transparency, heat resistance, moisture resistance, gas barrier property, etc. as compared with 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, using tetracarboxylic acids containing an alicyclic structure such as cyclohexylphenyltetracarboxylic acid. , It is disclosed that the polyimide reacted with various diamines has excellent transparency. In addition to this, attempts have been made to reduce the weight by using a flexible resin base material instead of the 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.

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

As one of the study examples, a display unit is provided on the resin base material by completing the manufacturing process of a predetermined display device in a state where the resin is laminated on the glass substrate and then removing the glass substrate. There is a method of 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 forming a predetermined display portion on a resin base material coated and fixed on a glass substrate, a method called EPLaR (Electronics on Plastic by Laser Release) process is used. A laser is irradiated from the glass side to forcibly separate the resin base material provided with the display unit from the glass substrate. Further, in Patent Document 2 and Non-Patent Document 4, after forming a release layer on a glass substrate, a polyimide resin is applied one size larger than the release layer to form a polyimide layer, and a cutting line reaching the release layer is inserted. Therefore, the polyimide film, which is one size smaller, is peeled off from the peeling layer.

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

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

Regarding this point, in Patent Document 3, a resin layer (b) is provided between the support substrate and the resin film (a) so that the coefficient of thermal expansion is 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, or the like is manufactured by a roll-to-roll (hereinafter also referred to as "RTR") method, the film used as a supporting base material can withstand high temperature treatment exceeding 300 ° C. during the process. Therefore, it is required to be a material having excellent heat resistance. Further, considering the light transmittance, a thin film is preferable. However, since it is difficult to handle a thin film and it is also difficult to manufacture it, a transparent film having a thickness of 50 μm or more is currently used.
Further, a transparent film with a carrier has been proposed as a method of achieving both ease of handling and manufacturing and thinness. In this laminated film with a carrier, a carrier film and a transparent base film are laminated without using an adhesive, and after forming a functional layer such as a thin film transistor on the transparent base material, the film 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 base material in displays and touch panels.
However, in the conventional laminated film with a carrier, warpage (curl) is likely to occur, and the handleability in the manufacturing process is very poor.

In Patent Document 4, in order to suppress the occurrence of warpage, a first polyimide layer having a smaller coefficient of thermal expansion is provided on a support such as a glass substrate, and a support having a coefficient of thermal expansion is provided on the first polyimide layer. Although it is disclosed that a second polyimide layer larger than that is provided, a study on a support made of a heat-resistant resin other than a glass substrate is not disclosed.

Japanese Unexamined Patent Publication No. 2008-231327 Japanese Patent No. 4834758 Japanese Patent No. 5488848 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, an 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 when a heat-resistant resin applicable to the RTR process is used as the carrier material in the manufacturing process. Manufacture of a polyimide resin laminate that can suppress warpage (curl) as much as possible while maintaining handleability and thinness as a support base material in displays and touch panels, and can easily and easily separate the support base material from the carrier material. Is to provide a method.

Therefore, as a result of diligent studies to solve these problems, the present inventors have surprisingly found that a curl-suppressing layer made of a predetermined polyimide resin is on one side of a base material layer made of a predetermined polyimide resin. Further, they have found that warpage (curl) can be improved while maintaining handleability and thinness as a base material by laminating a carrier layer made of a predetermined polyimide resin, and have completed the present invention.

That is, the present invention is a polyimide resin laminated body 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, and the present invention is on one surface side of the base material layer. , The curl-suppressing layer and the carrier layer are detachably adhered to each other, and the thermal expansion coefficient (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 preferably has any of the following aspects.
1) A curl-suppressing layer is provided on one surface side of the carrier layer, and a base material layer that is peelably adhered to the curl-suppressing layer is provided. Also small or large,
2) A peelable base material layer is provided on one surface side of the carrier layer, a curl suppression layer is provided on the opposite surface side of the carrier layer, and the CTE of the carrier layer is the CTE of the base material layer and the curl suppression 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 curl suppressing layer and a base material layer are interposed on one side of a carrier layer to further form a functional layer, or a base material layer on one side of a carrier layer. It can be preferably used as a polyimide resin laminate with a functional layer in which a functional layer is further formed via the above.
Further, 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. Is preferable.

As another aspect of the present invention, the polyimide resin laminate with the functional layer is used and peeled off at the interface between the curl suppressing layer and the base material layer or the interface between the carrier layer and the base material layer to cause the carrier layer and curl. It is a polyimide film with a functional layer obtained by removing the inhibitory layer.
Further, the present invention is a method for producing the above-mentioned polyimide resin laminate, which comprises forming a curl suppressing layer and a base material layer on a carrier layer by a casting method. ..
In this manufacturing method, it is preferable to integrally cure the curl suppressing layer and the base material layer coated on the carrier layer, and it is preferable that the casting method is coating with a multilayer die or a continuous die.

According to the present invention, warpage (curl) can be suppressed as much as possible while maintaining handleability in the manufacturing process and thinness as a supporting base material in displays and touch panels, and the required characteristics of polyimide resin laminates for displays and touch panels can be obtained. Can be met.

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 the state that the warp occurs 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 a thin base material layer in a predetermined shape in the RTR process, and is peeled off and removed from the base material layer after a functional layer such as an ITO film is formed via the base material layer. It is a thing. Therefore, flexibility and reinforcement of the substrate layer to maintain strength are required to adapt to the RTR process, but transparency is not always required. Therefore, the thickness of the carrier layer is larger than that of the thin film base material layer, preferably 10 to 100 μm, and more preferably 30 to 75 μm. Further, since heat resistance applicable to the high temperature process of RTR is required, the glass transition temperature (Tg) is preferably 300 ° C. or higher, more preferably 300 to 450 ° C.

The polyimide resin laminate of the present invention is made of a curl-suppressing layer made of a polyimide resin (hereinafter, also simply referred to as a curl-suppressing layer), a carrier layer made of a polyimide resin (hereinafter, also simply referred to as a carrier layer), and a polyimide resin. It is a polyimide laminated body in which a base material layer (hereinafter, also simply referred to as a base material layer) is laminated, and a laminated body 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. Further, 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 a curl-suppressing 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-suppressing layer. It refers to a material layer and a carrier layer, and when the layer in contact with the base material layer is a carrier layer, it means a base material layer and a curl suppressing layer.
There are two types of the polyimide resin laminate (form 1 and form 2). Hereinafter, each form will be specifically described.

[Form 1]
The polyimide resin laminate of Form 1 has a curl-suppressing layer on one surface side of the carrier layer, and further has a base material layer removably adhered to the curl-suppressing layer, and the CTE of the curl-suppressing layer is the carrier layer and the base. Less than or greater than any of the CTEs of the material layer.

Further, from the viewpoint of suppressing warpage, the CTE of the carrier layer is often close to the CTE of the base material layer, and the CTE difference (ΔCTE) between the two is preferably within ± 15 ppm / K, more preferably the base material. The difference between the CTE of the layer and the CTE of the carrier layer is within +15 ppm / K, 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 has a difference of -15 to +15 ppm / K as compared with the CTE of the carrier layer.

A base material layer is provided on one surface side of the carrier layer with a curl suppressing layer, which will be described later, interposed therebetween. The base material layer is a transparent base material that is a glass substitute that supports the functional layer after a functional layer such as an ITO film is formed on the base material layer and the carrier layer is peeled off and removed after the completion of the RTR process. Therefore, the total light transmittance of the base material layer is preferably 80% or more, more preferably 90% or more. The thickness of the base material layer is preferably as thin as possible, preferably 50 μm or less, and more preferably 5 to 25 μm, in view of the required characteristics of thinning, weight reduction, and flexibility. As described above, the CTE of the base material layer is often close to the CTE of the carrier layer, and is preferably 10 to 80 ppm / K. Further, since heat resistance applicable to the high temperature process of RTR is required, the glass transition temperature (Tg) of the base material layer is preferably 300 ° C. or higher, more preferably 300 to 450 ° C. Since it is used as a resin base material as a substitute for glass, the elastic modulus of the base material layer is preferably, for example, 2 to 15 GPa.

On one side of the carrier layer, a curl suppressing layer made of a polyimide resin is provided between the carrier layer and the base material layer. The curl suppressing layer is formed between the carrier layer and the base material layer in order to suppress the warp of the base material layer with a carrier as much as possible from the viewpoint of adapting to the RTR process, and the carrier layer and the curl suppressing layer are the base material layer. A functional layer such as an ITO film is formed by interposing the above, and when the carrier layer is peeled off and removed after the completion of the RTR process, it is removed together with the carrier layer. Therefore, in order to suppress warpage as much as possible in the RTR process, the thickness and the coefficient of thermal expansion are selected. Therefore, the thickness of the curl suppressing layer is preferably 50 μm or less, more preferably 5 to 30 μm. Further, since heat resistance applicable to the high temperature process of RTR is required, Tg is preferably 300 ° C. or higher, more preferably 300 to 450 ° C.
The CTE of the curl suppressing layer is selected so that the CTE difference between the carrier layer and the base material layer is relatively large. For example, the CTEs of the carrier layer and the base material layer do not necessarily have to be the same, but it is preferable to select so that the CTE of the curl suppressing layer has a certain difference or more with respect to both CTEs.
Therefore, regarding the CTE of the curl suppressing layer, the CTE difference from the carrier layer and the CTE difference from the base material layer are preferably ± 15 ppm / K or more, and more preferably CTE in the range of -15 to -60 ppm / K. It's a difference. The CTE of the curl suppressing layer is preferably −10 to 20 ppm / K. Here, when the CTE difference is ± 15 ppm / K or more, the CTE of the curl suppressing layer has a larger difference than -15 ppm / K or +15 ppm / K as compared with the CTE of the carrier layer and the CTE of the base material layer. Means that the difference is greater than.

The carrier-attached substrate made of the carrier layer and the substrate layer has a curl-suppressing layer between the carrier layer and the substrate layer, so that the fourth generation of the so-called glass substrate (680 × 880 mm to 730 ×) is particularly present. Even when a relatively large laminated body corresponding to 920 mm) or later is formed, the effect of suppressing warpage can be sufficiently obtained. In addition, the presence of the curl suppressing layer can increase 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 carrier layer does not easily affect the base material layer, it is possible to select an inexpensive polyimide film and increase the degree of freedom in designing the carrier layer.

[Form 2]
The polyimide resin laminate of Form 2 has a peelably adhered base material layer on one surface side of the carrier layer, and further has a curl suppressing layer on the opposite surface side of the carrier layer, and the CTE of the carrier layer is the said. It is smaller or larger than either the substrate layer or the CTE of the curl suppressing layer.
That is, the carrier layer is located between the base material layer and the curl suppressing layer. This configuration is preferable from the viewpoint of suppressing warpage. For example, the CTE of the carrier layer is preferably 10 to 70 ppm / K.

The base material layer is a transparent base material that is a glass substitute that supports the functional layer after a functional layer such as an ITO film is formed on the base material layer and the carrier layer is peeled off and removed after the completion of the RTR process. Therefore, the total light transmittance of the base material layer is preferably 80% or more, more preferably 90% or more. The thickness of the base material layer is preferably as thin as possible, preferably 50 μm or less, and more preferably 5 to 25 μm, as long as the workability is not impaired, from the required characteristics of thinning, weight reduction, and flexibility. The CTE of the substrate layer is preferably 1 to 80 ppm / K.
Further, since heat resistance applicable to the high temperature process of RTR is required, the glass transition temperature (Tg) is preferably 300 ° C. or higher, more preferably 300 to 450 ° C. Since it is used as a resin base material as a substitute for glass, the elastic modulus of the base material layer is preferably, for example, 2 to 15 GPa.

On the opposite side of the carrier layer, there is a curl suppressing layer made of a polyimide resin. The curl suppressing layer is formed on the opposite side of the base material layer in order to suppress the warp of the base material layer with a carrier as much as possible from the viewpoint of adapting to the RTR process, and the carrier layer intervenes the base material layer to form an ITO film. When the carrier layer is peeled off and removed after the RTR process is completed, the functional layer is removed together with the carrier layer. Therefore, the thickness and the coefficient of thermal expansion are selected in order to suppress the warp (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. Further, since heat resistance applicable to the high temperature process of RTR is required, the glass transition temperature (Tg) is preferably 300 ° C. or higher, more preferably 300 to 450 ° C.
The CTE of the curl-suppressing layer is often close to the CTE of the base material layer, and may be selected so as to cancel the CTE difference between the carrier layer and the base material layer. Therefore, the CTE difference from 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 carrier-attached substrate composed of the carrier layer and the substrate layer has the curl-suppressing layer on the opposite side of the substrate, so that the so-called fourth generation of glass substrate (680 × 880 mm to 730 × 920 mm) or later is particularly present. Even when a relatively large laminated body corresponding to the above is formed, the effect of suppressing warpage can be sufficiently obtained. In addition, the presence of the curl suppressing layer can increase the degree of freedom in designing the base material layer.

Hereinafter, the contents common to the first and second forms will be specifically described.

The polyimide resin used as the curl suppressing layer is not particularly limited as long as it satisfies the above characteristics, and for example, it may be formed of a polyimide having a structural unit represented by the following general formula (1). It is preferable that the polyimide contains 50 mol% or more of the structural unit represented by the following general formula (1).

Here, 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 alicyclics, and R is a tetravalent organic group having 1 to 6 carbon atoms. It is a substituent of. Among these, suitable specific examples of raw materials for forming the group X include, for example, pyromellitic dianhydride (PMDA) and naphthalene-2,3,6,7-tetracarboxylic dianhydride (NTCDA). ), 3,3', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) and the like. Moreover, as a preferable specific example of R, for example, -CH ₃ , -CF ₃ , and the like can be mentioned.

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

In addition, for those which can be contained other than the structural unit represented by the above general formula (1), preferably those which can contain less than 50 mol% at the maximum, general acid anhydride and diamine are used. The structural unit that was there can be mentioned. Among them, the acid anhydrides preferably used are pyromellitic acid dianhydride (PMDA), naphthalene-2,3,6,7-tetracarboxylic acid dianhydride (NTCDA), 3,3', 4,4. '-Biphenyltetracarboxylic acid dianhydride (BPDA), cyclohexanetetracarboxylic acid dianhydride, phenylenebis (trimellitic acid monoester anhydride), 4,4'-oxydiphthalic acid dianhydride, benzophenone-3,4, 3', 4'-Tetracarboxylic acid dianhydride, Diphenylsulfone-3,4,3', 4'-Tetracarboxylic acid dianhydride, 2,3,6,7-Naphthalenetetracarboxylic dianhydride, 4 , 4'-(2,2'-hexafluoroisopropyridene) diphthalic acid dianhydride and the like. On the other hand, as diamines, m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, 4,4'-diaminodiphenyl ether, 1,3-bis (4-aminophenoxy) benzene, 4,4'-diamino Diphenyl sulfone, 2,2-bis (4-aminobenzyloxyphenyl) propane, bis [4- (4-aminophenoxy) phenyl] sulfone, 4,4'-diaminobenzanilide, 9,9-bis (4-amino) Phenyl) Fluorene, etc.

Generally, when the coefficient of thermal expansion of polyimide becomes small, the transparency decreases and the retardation in the thickness direction (phase difference due to the difference in birefringence) increases. Therefore, it is not suitable when the base material layer separated from the carrier layer after the completion of the RTR process is used as a resin base material of a display device, for example, or used as a gas barrier film or a touch panel substrate. On the other hand, in the present invention, the presence of the curl suppressing layer on the opposite side allows the use of a base material layer having a larger coefficient of thermal expansion than the carrier layer.

The polyimide for forming the base material layer can be appropriately selected depending on the use of the polyimide resin laminate. In particular, when it is used as a flexible resin base material in a display device such as a liquid crystal display device, an organic EL display device, an electronic paper, a color filter, and a touch panel, it is represented by the following general formula (2). A polyimide having a structural unit can be mentioned, and a polyimide containing 50 mol% or more of the structural unit represented by the general formula (2) is preferable. For those that can be included in addition to the structural units represented by the general formula (2) (preferably containing less than 50 mol% at the maximum), the general formula (1) does not impair transparency. Examples are similar to those described in. Suitable acid anhydrides include pyromellitic acid dianhydride (PMDA), naphthalene-2,3,6,7-tetracarboxylic acid dianhydride (NTCDA), 3,3', 4,4'-. Biphenyltetracarboxylic acid dianhydride (BPDA), cyclohexanetetracarboxylic acid dianhydride, phenylenebis (trimellitic acid monoester anhydride), 4,4'-oxydiphthalic acid dianhydride, benzophenone-3,4,3' , 4'-Tetracarboxylic acid dianhydride, Diphenylsulfone-3,4,3', 4'-Tetracarboxylic acid dianhydride, 2,3,6,7-Naphthalenetetracarboxylic dianhydride, 4,4 '-(2,2'-Hexafluoroisopropylidene) diphthalic acid dianhydride and the like. On the other hand, as diamines, m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, 4,4'-diaminodiphenyl ether, 1,3-bis (4-aminophenoxy) benzene, 4,4'-diamino Diphenyl sulfone, 2,2-bis (4-aminobenzyloxyphenyl) propane, bis [4- (4-aminophenoxy) phenyl] sulfone, 4,4'-diaminobenzanilide, 9,9-bis (4-amino) Phenyl) Fluorene, etc.

In the above general formula (2), Y is an aromatic or alicyclic tetravalent organic group, preferably any of the following formulas (3).

Among them, the following is more preferable from the viewpoint of obtaining a polyimide resin having a transmittance of 80% or more at 500 nm in the wavelength region of 440 nm to 780 nm and a retardation in the thickness direction of 200 nm or less as the base material layer. It is one of the formulas (4).

A polyimide resin represented by the following formula (5) is preferable.

The polyimide resin used as the carrier layer is not particularly limited as long as it satisfies the above-mentioned characteristics, but for example, Kapton (manufactured by Toray DuPont), Upirex (manufactured by Ube Industries), and Apical (manufactured by Kaneka) are generally available. (Manufactured by) or a commercially available polyimide having a structure similar to these may be used, or it can be obtained by synthesizing 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 resin solution of polyamic acid uses substantially equal molars of the raw materials diamine and acid dianhydride. , 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. can. Here, from the viewpoint of uniform film thickness at the time of coating and the mechanical strength of the obtained polyimide, the weight average molecular weight (Mw) of the polyamic acid is preferably about 10,000 to 300,000. 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 resin solution of polyimide or a polyimide precursor is applied, dried, and heat-treated, respectively. That is, in obtaining the polyimide resin laminate of the present invention, preferably, a resin solution of polyimide or a polyimide precursor is applied to one side or both sides of a carrier layer, dried, and heat-treated to treat a base material. A layer and a curl suppressing layer can be formed. For example, a preliminary heat treatment at 90 to 130 ° C. for about 5 to 30 minutes is performed for drying, and then a high temperature heat treatment is performed at 130 to 360 ° C. for about 10 to 240 minutes for imidization. Is preferable.

The polyimide resin laminate thus obtained can be separated at the interface between the base material layer and the layer (carrier layer or curl suppressing layer) in contact with the base material layer, and can be separated at these interfaces. It is preferable that the base material layer is 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 that can be easily peeled off by human hands. Further, since the surface roughness obtained by the casting method (generally, the surface roughness Ra = about 1 to 80 nm) is maintained as it is on the separated surface of the base material layer, the visibility of the display device may be adversely affected. Nor.

In the present invention, it is possible to optimize the polyimide resin laminate by calculating the warp deformation (warp amount) of the polyimide resin laminate in which different materials are laminated, based on the following ideas. .. That is, based on a simple strength of materials calculation, the effect of its own weight was calculated by a three-dimensional strength of materials calculation, and then the warp deformation (warp amount) was added to obtain the final warp amount. As a calculation method, we used a finite element method in which the final warp deformation in a state where the thermal deformation and its own weight are balanced is discreteized using laminated shell elements and numerically calculated by a computer. (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 the base material layer. That is, after forming a predetermined functional layer on the base material layer, it may be separated at the interface between the curl suppressing 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 unit on the base material layer side, and it is not possible to ensure the handleability, dimensional stability, etc. of the base material layer in the manufacturing process of the display unit. Even if it exists, it is not finally removed to form a display device. Similarly, the curl-suppressing layer is not one that is separated along with the carrier layer and is finally removed to form a display device, and may be inferior in transparency. By using such a polyimide resin laminate, it is possible to obtain a display device that is thin, lightweight, and flexible while being able to accurately and reliably form a predetermined functional layer on the base material layer. 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, a TFT, an electrode, an organic EL element including a light emitting layer, or the like typically corresponds to a display unit. Further, in the case of a liquid crystal display device, it is a TFT, a drive circuit, a color filter or the like if 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, are used to project a predetermined image (moving image or image). The necessary parts correspond to the display unit. Of these, for example, the formation of a TFT generally requires an annealing step of about 400 ° C., and the polyimide resin laminate in the present invention has heat resistance that can withstand such an annealing step.

Hereinafter, the present invention will be specifically described based on Examples and Comparative Examples. The present invention is not limited to these contents.

1. 1. Various physical property measurement and performance test methods

[Peeling strength]
For the peel strength between the base material layer- (curl suppression layer) -carrier layer, the laminate is processed into strips with a width of 1 mm to 10 mm and a length of 10 mm to 25 mm, and a tensile tester manufactured by Toyo Seiki Co., Ltd. (Stro). Using Graph-M1), the carrier layer was peeled off in the 180 ° direction, and the peeling strength was measured. Those with strong peeling strength and difficult peeling were classified as "non-peeling".

[Transmittance]
A 20 μm-thick substrate layer was cut into 5 cm squares, and the transmittance was measured from 380 nm to 780 nm using HAZE METER NDH-5000 manufactured by Nippon Denshoku Kogyo.

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

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

[warp]
Cut out a square sample with a side of 100 mm from the laminated film with a cutter knife, adjust the humidity at 23 ° C and 50% for 24 hours, place it on a surface plate, measure the height of the four corners with a caliper, and warp the average value ( Carl).

2. 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 (mTB)
・ 1,3-Bis (4-aminophenoxy) benzene (TPER)
-2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP)
・ 1,4-Phenylenediamine (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
Under a nitrogen stream, TFMB (9.4 g, 0.03 mol) was added to 127.5 g of the solvent DMAc with stirring in a 300 ml separable flask and heated to dissolve at 50 ° C. Then 6 FDA (13.09 g, 0.03 mol) was added. The molar ratio of diamine to acid anhydride was made to be substantially 1: 1. Then, 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. The polyimide resin A can be obtained by curing this polyamic acid varnish A under the heating conditions described later.

Synthesis example 2
Under a nitrogen stream, 10.2 g of m-TB and 1.6 g of TPE-R were added to 170 g of solvent DMAc while stirring in a 300 ml separable flask at a molar ratio of 90:10, and the mixture was heated and dissolved at 50 ° C. .. Then, 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 made to be substantially 1: 1. Then, 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. The polyimide resin B can be obtained by curing this polyamic acid varnish B under the heating conditions described later.

Synthesis example 3
Under a nitrogen stream, TFMB (12.6 g, 0.04 mol) was added to 127.5 g of the solvent DMAc with stirring in a 300 ml separable flask and heated to dissolve at 50 ° C. Then 6 FDA (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 made to be substantially 1: 1. Then, 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. The polyimide resin C can be obtained by curing this polyamic acid varnish C under the heating conditions described later.

Synthesis example 4
Under a nitrogen stream, m-TB (14.4 g, 0.07 mol) was added to 170 g of the solvent DMAc with stirring in a 300 ml separable flask, heated, and dissolved at 50 ° C. PMDA (13.6 g 0.06 mol) and BPDA (2 g, 0.007 mol) were then added at a molar ratio of 90:10. The molar ratio of diamine to acid anhydride was made to be substantially 1: 1. Then, 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. The polyimide resin D can be obtained by curing this polyamic acid varnish D under the heating conditions described later.

Synthesis example 5
Under a nitrogen stream, TPE-R (14.8 g, 0.05 mol) as a diamine was added to 170 g of the solvent DMAc while stirring in a 300 ml separable flask, and the mixture was heated 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 made to be substantially 1: 1. Then, 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. The polyimide resin E can be obtained by curing this polyamic acid varnish E under the heating conditions described later.

Synthesis example 6
Under a nitrogen stream, the mixture was added to 170 g of the solvent DMAc while stirring in a 300 ml separable flask so that m-TB: TPE-R had a molar ratio of 90:10, and the mixture was heated and dissolved at 50 ° C. Then, it was added so that the molar ratio of PMDA: BPDA was 80:20. The molar ratio of diamine to acid anhydride was set to be substantially 1: 1. Then, 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. The polyimide resin F can be obtained by curing this polyamic acid F varnish under the heating conditions described later.

Synthesis example 7
Under a nitrogen stream, TFMB (16.93 g) was added and dissolved in solvent DMAc (170 g) with stirring in a 300 ml separable flask. Then PMDA (10.12g) and 6FDA (2.95g) were added. Then, 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. The polyimide resin H can be obtained by curing this polyamic acid H varnish under the heating conditions described later.

Synthesis example 8
BAPP (19.45 g) was added to and dissolved in the solvent DMAc (170 g) with stirring in a 300 ml separable flask under a nitrogen stream. Then PMDA (9.85 g) and BPDA (0.70 g) were added. Then, 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 I varnish. The polyimide resin I can be obtained by curing this polyamic acid I varnish under the heating conditions described later.

Synthesis example 9
Under a nitrogen stream, 4,4'-DAPE (8.97 g) was added and dissolved in solvent DMAc (170 g) with stirring in a 300 ml separable flask. Then PMDA (8.95 g) and BPDA (12.08 g) were added. Then, the solution was stirred at room temperature for 6 hours to carry out a polymerization reaction to obtain 200 g of brown viscous polyamic acid J varnish. The polyimide resin J can be obtained by curing this polyamic acid J varnish under the heating conditions described later.

Synthesis example 10
Under a nitrogen stream, 4,4'-DAPE (8.14 g) and PPD (4.40 g) were added and dissolved in solvent DMAc (170 g) with stirring in a 300 ml separable flask. Then PMDA (17.45 g) was added. Then, the solution was stirred at room temperature for 6 hours to carry out a polymerization reaction to obtain 200 g of brown viscous polyamic acid K varnish. The polyimide resin K can be obtained by curing this K polyamic acid varnish under the heating conditions described later.

3. 3. Formation of Polyimide (PI) Layer by Coating Two types of polyimide films were used as the carrier layer.
1) Polyimide film 1: Made by 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: Made by Rayitek, China, 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 portion, a lip coater, a continuous drying furnace, a continuous furnace and a winding portion, for example, the RTR method coating drying and curing shown in FIG. While unwinding at a rate of 2 m / min with the equipment, varnish B polyamic acid was applied using a mono pump so that the film thickness became 45 μm. This is passed through a continuous drying furnace composed of a plurality of furnaces and dried at 90 ° C. for 2 minutes and at 130 ° C. for 1 minute. The polyimide resin B as a curl suppressing layer was formed on the carrier film by passing it through a continuous furnace in which the temperature gradually increased and heating it stepwise from 130 ° C. to 400 ° C. for a total of 25 minutes. Created a role. Next, this roll is set in the unwinding portion of the same coating / drying device, 100 μm of polyimide acid varnish A is applied on the polyimide resin B, and the polyimide acid varnish A is passed through a continuous drying furnace composed of a plurality of furnaces. It is dried at ° C for 2 minutes and at 130 ° C for 1 minute, and is further passed through a continuous furnace composed of a plurality of furnaces and gradually increasing in temperature from the furnace on the sample inlet side to the furnace on the outlet side to 130. The polyimide resin A having a thickness of 10 μm as a substrate layer was formed by stepwise heating from ° C. to 400 ° C. for a total of 20 minutes to obtain a roll-shaped polyimide resin laminate (laminate 1).
The thickness of each layer of the laminated body 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 laminated body 1 is schematically shown in FIG. The structure is such that the base material layer 2 is laminated on one surface side of the carrier film 4 with the curl suppressing layer 3 interposed therebetween (form 1). The functional layer 1 is formed on the base material layer 2 of the laminated body by the following method.

Next, with respect to the roll-shaped polyimide resin laminate, the substrate layer was formed at a speed of 2 m / min using an RTR-type device provided with an unwinding section, a transport roll, a process processing section, and a winding section. While unwinding in the longitudinal direction so as to be on top, it is introduced into a process processing unit installed in a vacuum chamber via a transport roll, and ITO as a functional layer having a thickness of 50 nm is applied to a substrate layer by a sputtering method. Was formed into a film by continuous treatment and wound up as a polyimide substrate film with a functional layer.
Further, the polyimide substrate film with a functional layer was cut into a sheet of 370 × 450 mm, and the film-formed ITO was subjected to transparent circuit processing in one direction (X direction) and the other direction (Y direction) in the XY directions. At that time, the intersection of the Y circuit with the X circuit did not form a circuit.
Subsequently, an overcoat is applied to the intersections of the XY circuits and heat-treated at 250 ° C. to cure the overcoat layer, and a silver paste is used to perform bridge processing across the overcoat layers 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 cover glass on the ITO film-forming side, and then the carrier film and the curl-suppressing layer are mechanically peeled off to form a functional layer on the base material layer. Was completed.

Comparative Example 1
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 without forming a curl suppressing layer 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 in the XY direction cannot be processed. Could not be created.

Example 2
The carrier film 1 (width 520 mm × length 500 m × thickness 75 μm) is provided with an unwinding portion, a lip coater, a continuous drying furnace, a continuous furnace and a winding portion, for example, the RTR method coating drying and curing shown in FIG. While unwinding at a rate of 2 m / min with the equipment, varnish E polyamic acid was applied using a mono pump so that the film thickness became 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 at 130 ° C. for 1 minute to form a roll on which the polyimide resin E as a curl suppressing layer is formed on the carrier film. Created. Next, this roll was set in the unwinding portion of the same coating / drying device, 100 μm of varnish A polyamic acid was applied to the opposite side of the polyimide resin E, and the mixture was passed through a continuous drying furnace composed of a plurality of furnaces. It was dried at 90 ° C. for 2 minutes and dried at 130 ° C. for 1 minute, and then passed through a continuous furnace composed of multiple furnaces and gradually increasing in temperature from the sample inlet side furnace to the outlet side furnace. A polyimide resin A having a thickness of 10 μm was formed as a substrate layer by heating stepwise from 130 ° C. to 400 ° C. for a total of 20 minutes to obtain a roll-shaped polyimide resin laminate (laminate 2). ..
The thickness of each layer of the laminated body 2 was 75 μm for the carrier film, 13 μm for the curl suppressing layer, and 10 μm for the base material layer. In FIG. 1, the layer structure of the laminated body 2 is a structure in which the curl suppressing layer 3 and the carrier film 4 are laminated in reverse, 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 laminated (form 2).

Next, with respect to the laminated body 2, the touch panel substrate in which the functional layer was formed on the base material layer was completed by the same method as in Example 1.

Example 3
Polyimide was used in the same manner as in Example 2 except that the polyamic 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 suppressing layer. A resin laminated body (laminated body 3) was obtained.
The thickness of each layer of the laminated body 3 was 75 μm for the carrier layer, 12 μm for the base material layer, and 13 μm for the curl suppressing layer.
An ITO and XY circuits were formed on the laminated body 2 by the same method as in Example 1 to obtain a touch panel.

Example 4
A polyimide resin laminated body (laminated body 4) was obtained by the same method as in Example 1 except that the polyimide film 2 was used as the carrier and the polyamic acid varnish F was used as the curl suppressing layer instead of the polyamic acid varnish C. rice field.
The thickness of each layer of the laminated body 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 was used in the same manner as in Example 1 except that the polyamic acid varnish H was used instead of the polyamic acid varnish A as the base material layer and the polyamic acid varnish E was used instead of the polyamic acid varnish B as the curl suppressing layer. A resin laminated body (laminated body 5) was obtained.
The thickness of each layer of the laminated body 5 was 75 μm for the carrier layer, 10 μm for the base material layer, and 50 μm for the curl suppressing layer.

Example 6
A polyimide resin laminated body (laminated body 6) was obtained by the same method as in Example 2 except for the thickness of the base material layer and the curl suppressing layer.
The thickness of each layer of the laminated body 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 lamination was performed in the same manner as in Example 2 except that the polyamic acid varnish H was used instead of the polyamic acid varnish A and B was used instead of the polyamic acid varnish E as the curl suppressing layer. A body (laminated body 7) was obtained.
The thickness of each layer of the laminated body 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 laminated body (laminated body C2) was obtained by the same method as in Example 1 except that the polyamic acid varnish I was used instead of the polyamic acid varnish B as the curl suppressing layer.
The thickness of each layer of the laminated body 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 laminated body (laminated body C3) was obtained by the same method as in Example 2 except that the polyamic acid varnish J was used instead of the polyamic acid varnish E as the curl suppressing layer.
The thickness of each layer of the laminated body 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 laminated body (laminated body C4) was obtained by the same method as in Example 1 except that the polyamic acid varnish I was used instead of the polyamic acid varnish B as the curl suppressing layer.
The thickness of each layer of the laminated body 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 carried out except that the polyamic acid H was used instead of the polyamic acid A of Example 4 and the polyamic acid K was used instead of the polyamic acid E.
Polyimide was used in the same manner as in Example 1 except that the polyamic acid varnish H was used instead of the polyamic acid varnish A as the base material layer and the polyamic acid varnish K was used instead of the polyamic acid varnish B as the curl suppressing layer. A resin laminate (laminate C5) was obtained.
The thickness of each layer of the laminated body 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 characteristics of the polyimide resin laminates obtained in these Examples and Comparative Examples.

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

Claims (11)

A polyimide resin laminate in which a curl-suppressing layer made of a polyimide resin containing 50 mol% or more of a structural unit represented by the following general formula (1), a carrier layer made of a polyimide resin, and a base material layer made of a polyimide resin are laminated. The curl-suppressing layer is provided on one surface side of the carrier layer, and the curl-suppressing layer is peelably adhered to the base material layer, and the difference in thermal expansion coefficient (CTE) between the base material layer and the carrier layer is different. A polyimide resin laminate characterized by being ± 40 ppm / K or less.

Here, in the formula (1), X is an aromatic group or an alicyclic group, and is a tetravalent organic group having one or more aromatic rings or alicyclics, and R is a tetravalent organic group having 1 to 6 carbon atoms. It is a substituent. CTE is a value converted from the amount of elongation in the temperature range of 100 to 250 ° C after conducting a tensile test in the temperature range of 30 ° C to 260 ° C. The polyimide resin laminate according to claim 1, wherein a curl suppressing layer and a base material layer are interposed on one surface side of the carrier layer to further form a functional layer. A polyimide resin laminate in which a curl-suppressing layer made of a polyimide resin containing 50 mol% or more of a structural unit represented by the following general formula (1), a carrier layer made of a polyimide resin, and a base material layer made of a polyimide resin are laminated. It has a peelable base material layer on one surface side of the carrier layer, a curl suppression layer on the opposite surface side of the carrier layer, and a thermal expansion coefficient (CTE) between the base material layer and the curl suppression layer. ) A polyimide resin laminate characterized in that the difference is ± 40 ppm / K or less.

Here, in the formula (1), X is an aromatic group or an alicyclic group, and is a tetravalent organic group having one or more aromatic rings or alicyclics, and R is a tetravalent organic group having 1 to 6 carbon atoms. It is a substituent. CTE is a value converted from the amount of elongation in the temperature range of 100 to 250 ° C after conducting a tensile test in the temperature range of 30 ° C to 260 ° C. The polyimide resin laminate according to claim 3, wherein a functional layer is further formed by interposing a base material layer on one surface side of the carrier layer. The polyimide resin laminate according to claim 1 or 3, 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 1 or 3, wherein the Tg of the polyimide resin forming the base material layer is 300 ° C. or higher. A polyimide film with a functional layer, which comprises using the polyimide resin laminate according to claim 2 and peeling off at the interface between the curl suppressing layer and the base material layer to remove the carrier layer and the curl suppressing layer. A polyimide film with a functional layer, which comprises using the polyimide resin laminate according to claim 4 and peeling off at the interface between the carrier layer and the base material layer to remove the carrier layer and the curl suppressing layer. The method for producing a polyimide resin laminate according to claim 1 or 3, wherein the carrier layer is coated with a curl suppressing layer and a base material layer by a casting method. The method for producing a polyimide resin laminate according to claim 9, wherein the curl suppressing layer and the base material layer coated on the carrier layer are integrally cured. The method for manufacturing a polyimide resin laminate according to claim 9, wherein the casting method is coating with a multilayer die or a continuous die.

Images