JP6808401B2 - Manufacturing method of polyimide substrate film with functional layer - Google Patents

Description

The present invention relates to a method for producing a polyimide substrate film with a functional layer and a long polyimide substrate film with a functional layer. For details, the present invention includes flexible displays such as a liquid crystal display device and an organic EL display, organic EL lighting, electronic paper, and the like. Regarding a method for manufacturing a polyimide substrate film with a functional layer provided with a functional layer for forming a touch panel, a solar cell, a color filter, etc., and a long polyimide substrate film with a functional layer, and such a long polyimide with a functional layer. The present invention relates to a long polyimide laminate for obtaining a substrate film and a long polyimide laminate with a functional layer.

Display devices such as liquid crystal display devices and organic EL display devices are used for various display applications, from large displays such as televisions to small displays such as mobile phones, personal computers, and smartphones. A typical display device is an organic EL display device. For example, in this organic EL display device, a thin film transistor (hereinafter referred to as TFT) is formed on a glass substrate as a supporting base material, and an electrode, a light emitting layer, and an electrode are formed. Are sequentially formed, and finally, they are separately sealed with a glass substrate, a multilayer thin film, or the like.

Here, by replacing the glass substrate, which is the supporting base material, with a resin substrate, it is possible to realize thinness, light weight, and flexibility, and the use of the display device can be further expanded.

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 has been reported that 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 for the support base material. For example, in Non-Patent Documents 1 and 2 below, an organic in which highly transparent polyimide is applied to the support base material. An EL display device has been proposed.

As described above, it is known that a resin substrate such as polyimide is useful for a flexible substrate for a flexible display. However, resin substrates are generally inferior in dimensional stability, transparency, heat resistance, moisture resistance, gas barrier properties, etc. to glass, and therefore are currently in the research stage and various studies have been conducted.

For example, in Non-Patent Document 3, after forming a predetermined functional layer on a resin substrate coated and fixed on glass, a laser is irradiated from the glass side by a method called an EPLaR (Electronicson Plastic by Laser Release) process. Therefore, a method of forcibly separating a resin substrate provided with a functional layer from glass has been proposed.

Further, in Non-Patent Document 4, a polyamic acid (polyimide precursor) solution is applied onto glass via a release layer, and the polyimide substrate is cured to provide a predetermined functional layer on the glass. A method of peeling the polyimide substrate from the glass has been proposed. In the case of this method, the polyamic acid solution is applied over an area larger than the release layer so that the peripheral portion of the cured polyimide substrate is directly adhered to the glass, and this peripheral portion is left on the glass. A notch is made in the portion where the functional layer is formed, and the polyimide substrate formed through the release layer is separated from the glass.

All of the techniques disclosed in Non-Patent Documents 3 and 4 ensure the handleability and dimensional stability of the resin substrate by forming a resin substrate on glass and forming a functional layer on the resin substrate. is there. However, these methods have problems such as low productivity because a special means is adopted for separating the resin substrate from the glass. That is, in the method using the EPLaR process described in Non-Patent Document 3, not only it takes time to separate the resin substrate from the glass, but also the surface texture of the resin substrate may be adversely affected. In addition, the method described in Non-Patent Document 4 increases the number of steps and creates a region that cannot be used as a resin substrate, resulting in waste. Therefore, it is strongly desired to develop a technology that can be used by means that contributes industrially while taking advantage of the advantages of the resin substrate.

As a method for solving such a problem, a polyimide laminate having a polyimide film instead of glass on the back side of the polyimide substrate has a specific performance at the interface between the polyimide substrate and the polyimide film. A polyimide laminate characterized in that a polyimide film can be separated after forming a predetermined functional layer on the surface side of the polyimide substrate is disclosed (see Patent Document 2). This polyimide laminate uses a polyimide film as a supporting base material instead of the glass in Non-Patent Documents 3 and 4, and the surface of the polyimide film is coated with a polyamic acid solution and heat-treated. Then, a polyimide substrate is formed on the supporting base material. According to the polyimide laminate thus obtained, handleability, dimensional stability, and the like can be ensured, and the polyimide substrate can be easily separated from the supporting base material to form a polyimide film. Therefore, it can be suitably used for manufacturing a touch panel, a display device, or the like.

Japanese Unexamined Patent Publication No. 2008-23327 Japanese Unexamined Patent Publication No. 2014-61685

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)

According to the method described in Patent Document 2, the polyimide substrate can be easily separated from the supporting base material into a polyimide film while ensuring handleability, dimensional stability, etc., and thus a resin that replaces the conventional glass substrate. It is believed that the application of the substrate will be promoted. However, as in the method described in Patent Document 2, when a polyimide film is used as a supporting base material, a polyamic acid (polyimide precursor) solution or a polyimide resin solution is applied thereto, and heat treatment is performed to obtain a polyimide substrate film. In addition, if foreign matter such as particles adheres to the polyimide film used as the supporting base material, it may be mixed into the polyimide substrate film as it is.

For example, in the manufacturing process of flexible devices such as liquid crystal display devices, organic EL displays, organic EL lighting, electronic paper, touch panels, solar cells, color filters, etc., a high-level clean environment is required, and even minute dust and the like are tentatively required. Even if the mixture is mixed, the characteristics of the flexible device may be significantly deteriorated. Further, as the performance, size and thickness of flexible devices are reduced, it is required to make the polyimide substrate film itself thinner. However, when the polyimide substrate film becomes thin, the polyimide substrate film is damaged when peeled from the supporting substrate. There is a possibility that the peelability will be further improved.

Therefore, as a result of diligent studies on the above problems, the present inventors applied the first and second solutions composed of the polyimide precursor or the polyimide resin solution onto the carrier, respectively. By performing the first and second heat treatments to obtain a long polyimide laminate in which the carrier film and the polyimide substrate film are laminated, it is possible to prevent foreign matter from being mixed in as much as possible. The present invention has been completed by finding that the carrier film and the polyimide substrate film have good peelability and can be suitably used for manufacturing a flexible device.

Therefore, an object of the present invention is to prevent foreign matter from being mixed into the polyimide substrate film, and to have good peelability from the carrier film, and a polyimide with a functional layer having a functional layer on the polyimide substrate film. It is an object of the present invention to provide a method for producing a substrate film and a polyimide substrate film with a functional layer obtained thereby.

Another object of the present invention is to provide a polyimide laminate for obtaining such a polyimide substrate film with a functional layer, and a polyimide laminate with a functional layer.

That is, the gist of the present invention is as follows.
(1) A first solution composed of a polyimide precursor or a polyimide resin solution is applied onto a continuously supplied carrier to perform a first heat treatment, and a tack-free surface is formed on at least the surface of the first solution. The first polyimide composed of the first solution while continuously supplying the carrier by forming and then applying a second solution composed of a polyimide precursor or a polyimide resin solution and performing a second heat treatment. together and a hardened layer and the second polyimide cured layer made of the second solution, a step Ru to obtain a polyimide laminate long separated from the conveying member to the traveling direction of the conveying member as a longitudinal direction,
One of the first and second cured polyimide layers in the long polyimide laminate is used as a polyimide substrate film, the other is used as a carrier film, a functional layer is formed on the polyimide substrate film, and then the carrier film is separated. And the process of obtaining a polyimide substrate film with a functional layer ,
A method for producing a polyimide substrate film with a functional layer, which comprises .
(2) The long polyimide laminate is once wound on a winding roll, and then a functional layer is continuously formed on the polyimide substrate film while unwinding the polyimide laminate, or the polyimide laminate is formed. The method for producing a polyimide substrate film with a functional layer according to (1), wherein a functional layer is formed on the polyimide substrate film for each sheet-shaped polyimide laminate by cutting the body into a sheet with a predetermined length while unwinding the body.
(3) In obtaining the long polyimide laminate, the carrier is separated before the second heat treatment, or is separated after the second heat treatment (1) or (2). ). The method for manufacturing a polyimide substrate film with a functional layer.
(4) The method for producing a polyimide substrate film with a functional layer according to any one of (1) to (3), wherein the carrier is a metal drum, an endless belt, or a long base material wound in a roll shape.
(5) The carrier is a long base material wound in a roll shape, and while unwinding the long base material, coating of the first solution, the first heat treatment, and the second The polyimide with a functional layer according to any one of (1) to (3), wherein the coating of the solution and the second heat treatment are sequentially performed, and then the long base material is separated to obtain a long polyimide laminate. Method of manufacturing substrate film.
( 6 ) The method for producing a polyimide substrate film with a functional layer according to any one of (1) to ( 5 ), wherein the carrier film is made of a first polyimide cured layer and the polyimide substrate film is made of a second polyimide cured layer.
( 7 ) The method for producing a polyimide substrate film with a functional layer according to any one of (1) to ( 5 ), wherein the polyimide substrate film is composed of a first polyimide cured layer and the carrier film is composed of a second polyimide cured layer.
( 8 ) A first solution composed of a polyimide resin solution is applied onto the carrier, and a first heat treatment is performed with a maximum temperature of 60 ° C. to 300 ° C., and the surface of the first solution is tack-free. The method for producing a polyimide substrate film with a functional layer according to any one of (1) to ( 7 ), which forms a surface.
(9) A first solution made of a polyimide precursor is applied onto the carrier, a first heat treatment is performed at a maximum temperature of 100 ° C. to 450 ° C., and a first polyimide made of the first solution is cured. The method for producing a polyimide substrate film with a functional layer according to any one of (1) to ( 7 ), which forms a layer.
( 10 ) The method for producing a polyimide substrate film with a functional layer according to any one of (1) to ( 9 ), wherein the maximum temperature of the heat treatment in the second heat treatment is 100 ° C. to 450 ° C.
(11) The interlayer adhesion strength between the first polyimide cured layer and the second polyimide cured layer is 1 to 20 N / m, and the thickness of the first or second polyimide cured layer used as the polyimide substrate film is 1 to 50 μm. The method for producing a polyimide substrate film with a functional layer according to any one of (1) to ( 10 ).
(12) The first or second polyimide cured layer to be the polyimide substrate film is the polyimide substrate film with a functional layer according to any one of (1) to ( 11 ), which has a total light transmittance of 80% or more. Production method.
(13) The carrier is made of a long base material wound in a roll shape, and the long base material is a polyimide film, a SUS foil, a copper foil, or a composite in which two or more of these are laminated (1). ) To ( 12 ). The method for producing a polyimide substrate film with a functional layer.
(14) Any of (1) to ( 13 ) of (1) to ( 13 ), in which two or more first solutions composed of the polyimide precursor or the polyimide resin solution are overcoated and coated to form a first polyimide cured layer. A method for manufacturing a polyimide substrate film with a functional layer described in Crab.
(15) Any of (1) to ( 13 ) of (1) to ( 13 ), in which two or more kinds of the second solutions composed of the polyimide precursor or the polyimide resin solution are overcoated and coated to form the second polyimide cured layer. A method for manufacturing a polyimide substrate film with a functional layer described in Crab.

( 16 ) A carrier film made of a polyimide cured layer obtained by curing one of a first or second solution made of a polyimide precursor or a polyimide resin solution, and a first or second solution made of a polyimide precursor or a polyimide resin solution. A functional layer is continuously formed on the polyimide substrate film in the longitudinal direction of a long polyimide laminate in which a polyimide substrate film composed of a polyimide cured layer obtained by curing the other of the two is continuously formed on the polyimide substrate. The film has a thickness of 1 to 50 μm, a total light transmittance of 80% or more, and the interface with the carrier film has a surface roughness with an arithmetic average roughness Ra of 0 to 5 nm. A long polyimide laminate with a functional layer, characterized in that the interlayer adhesion strength between the carrier film and the polyimide substrate film is 1 to 20 N / m.
( 17 ) The long polyimide laminate with a functional layer according to ( 16 ), wherein the functional layer is an ITO film.
( 18 ) The long polyimide laminate with a functional layer according to ( 16 ), wherein the functional layer is a TFT.
( 19 ) The functional layer is composed of a transparent conductive layer, a wiring layer, a conductive layer, a gas barrier layer, a thin film transistor, an electrode layer, a light emitting layer, an adhesive layer, an adhesive layer, a transparent resin layer, a color filter resist, and a hard cord layer. The long polyimide laminate with a functional layer according to ( 16 ), which is a layer containing any one or a combination of two or more selected from the group.
( 20 ) A carrier film made of a polyimide cured layer obtained by curing one of a first or second solution made of a polyimide precursor or a polyimide resin solution, and a first or second solution made of a polyimide precursor or a polyimide resin solution. It is a long polyimide laminated body in which a polyimide substrate film composed of a polyimide cured layer obtained by curing the other of the two is laminated, and the interlayer adhesion strength between the carrier film and the polyimide substrate film is 1 to 20 N / m, and the polyimide The substrate film is a long polyimide laminate having a thickness of 1 to 50 μm and a total light transmittance of 80% or more.
( 21 ) A functional layer is continuously formed in the longitudinal direction of a long polyimide substrate film composed of a polyimide cured layer obtained by curing a solution composed of a polyimide precursor or a polyimide resin solution. It is characterized by having a thickness of 1 to 50 μm, a total light transmittance of 80% or more, and a surface roughness on the opposite side of the functional layer having an arithmetic average roughness Ra of 0 to 5 nm. A long polyimide substrate film with a functional layer.

According to the present invention, it is possible to prevent foreign matter from being mixed into the polyimide substrate film, and the releasability from the carrier film is good. The polyimide substrate film with a functional layer having a functional layer on the polyimide substrate film. Can be obtained. Of these, the polyimide substrate film has excellent heat resistance and can be applied to a heat treatment process at a high temperature, so that it can be used for manufacturing various flexible devices using a functional layer.

Further, in obtaining such a polyimide substrate film with a functional layer, in the present invention, after obtaining a long polyimide laminate, the functional layer is formed on the polyimide substrate film constituting the polyimide laminate. Handleability (handleability) and dimensional stability are ensured.

FIG. 1 is a schematic explanatory view showing a roll-to-roll type coating drying and curing apparatus used for obtaining a polyimide laminate. FIG. 2 is a schematic explanatory view showing an endless belt type coating drying and curing apparatus used for obtaining a polyimide laminate. FIG. 3 is a schematic explanatory view showing a metal drum type coating drying and curing apparatus used for obtaining a polyimide laminate. FIG. 4 is a schematic explanatory view showing a roll-to-roll type continuous manufacturing apparatus for forming a functional layer on a polyimide laminate.

Hereinafter, the present invention will be described in detail.
In the present invention, first, a first solution composed of a polyimide precursor or a polyimide resin solution is applied onto a continuously supplied carrier, and a first heat treatment is performed, so that at least the surface of the first solution is coated. A tack-free surface is formed, and then a second solution composed of a polyimide precursor or a polyimide resin solution is applied and a second heat treatment is performed to obtain a first polyimide cured layer composed of the first solution and a first. A second polyimide hardened layer composed of the solution of 2 is provided, and a long polyimide laminate separated from the carrier is obtained with the traveling direction of the carrier as the longitudinal direction.

In the present invention, the continuously supplied carrier is used by using the first and second solutions composed of the polyimide precursor or the polyimide resin solution, and the first polyimide cured layer and the second polyimide cured by the so-called casting method. This is for laminating the layers, and more specifically, for obtaining a long polyimide laminate in which these polyimide cured layers are laminated.

That is, the first solution is applied onto the continuously supplied carrier, the first heat treatment is performed to form at least a tack-free surface, and the second solution is applied onto the second solution. By performing the heat treatment, the obtained polyimide laminate becomes a long laminated film having a MD (Machine Direction) side longer than the TD (Transverse Direction) side. Such a long polyimide laminate can be conveyed by a roll-to-roll process in a later process. For example, the polyimide laminate is wound once on a winding roll and then wound. The functional layer can be continuously formed while being put out. Therefore, for example, as compared with the case where a sheet-shaped polyimide laminate is obtained by using an intermittently supplied carrier and a functional layer is formed by batch processing, the number of steps is reduced, so that foreign matter is mixed. The fear can be eliminated as much as possible, and flexible devices using the functional layer can be efficiently manufactured.

The continuously supplied carrier is not particularly limited, and examples thereof include a metal drum, an endless belt, and a long base material wound in a roll shape. Among them, from the viewpoint of productivity, it is preferable to use an endless belt or a long base material wound in a roll shape, and more preferably, a long base material wound in a roll shape. Of these, in the case of a long base material wound in a roll shape, the longer it is on the MD side, the longer the polyimide laminate can be obtained, which is desirable, but from the viewpoint of productivity and the like, it is preferable (on the MD side). The length) / (length on the TD side) is preferably 50 or more, more preferably 2000 or more. Further, in the case of an endless belt, the longer the MD side is, the better the productivity is, but on the other hand, the device becomes expensive and the size and weight of the device increase. From these balances, the length of the endless belt is preferably about 10 to 50 m.

Here, the material for forming the carrier may be any material that can withstand the temperature of the first heat treatment for forming the tack-free surface by applying at least the first solution. Specifically, in the case of a long base material wound in a roll shape, a polyimide film, a SUS foil, a copper foil, etc., which have excellent flexibility in addition to strength and heat resistance, can be mentioned, and a composite of these can be mentioned. It may be. Of these, a polyimide film is preferable. Further, in the case of an endless belt, it is preferable that the belt is made of SUS.

Then, a first solution composed of a polyimide precursor or a polyimide resin solution is applied onto the continuously supplied carrier to perform the first heat treatment, and at least the surface of the solution is tack-free. Form a surface. Here, the tack-free refers to a state in which the object does not adhere to the contacted object when it comes into contact with the surface of the object. For example, the first solution is applied and the first heat treatment is performed. This is a state in which the constituents of the first solution do not adhere to the fingertips when touched with a finger after the heat treatment.

Further, in order to make the first solution coated on the carrier at least in a tack-free state, at least a part of the solvent in the coated first solution is volatilized by the first heat treatment. dry. At that time, if the first solution is a polyimide resin solution, at least a part thereof may be imidized. If such a first heat treatment is insufficient, a tack-free surface is not formed and is mixed with the second solution, which later causes swelling in the polyimide laminate, or the polyimide substrate film and the carrier film. And may not be able to be separated. Further, in some cases, the carrier cannot be separated later.

The first heat treatment differs depending on the type of the first solution used, but when the first solution consists of a polyimide resin solution, it is not necessary to carry out an imidization reaction, and the solvent may be volatilized. Therefore, the first heat treatment is preferably performed at a maximum temperature of 60 ° C. to 300 ° C., more preferably 150 ° C. to 250 ° C. to form a tack-free surface on the surface of the first solution coated on the carrier. Is good. At this time, the first solution, which has been made tack-free by drying in the first heat treatment, preferably has a solid content concentration of about 95 to 99.5% by mass, more preferably 99 to 99.5% by mass. It is preferably 99.5% by mass.

On the other hand, when the first solution is made of a polyimide precursor, it is preferable that at least the surface thereof is imidized. From this point of view, the first heat treatment having a maximum temperature of preferably 100 ° C. to 450 ° C., more preferably 180 ° C. to 360 ° C. may be performed to form a first polyimide cured layer composed of the first solution. Good. At that time, preferably, the polyimide precursor is "almost completely imidized" to form the first polyimide cured layer. Here, "almost completely imidized" means a state in which the imidization rate is 90% or more. In that case, it is necessary to perform the heat treatment at a higher temperature than the tack-free state by the drying. By imidizing almost completely, the polyimide substrate film and the carrier film can be more easily separated. In that case, the maximum temperature is preferably 300 ° C. to 360 ° C. A so-called "imidization catalyst" such as pyridine, acetic anhydride, or N-methylimidazole may be added to the first solution composed of the polyimide precursor to imidize the solution. By adding the imidization catalyst, imidization can easily proceed even at a relatively low temperature.

When "nearly completely imidized", the solid content concentration of the first solution is approximately 100% by mass. However, if the heat treatment is performed rapidly, the solvent may rapidly volatilize from the first solution, causing problems such as foaming of the first solution coated on the carrier. Therefore, in the first heat treatment, it is desirable to gradually raise the temperature from a relatively low temperature state before reaching the maximum temperature. In that case, a method of using a continuous heat treatment apparatus which is composed of a plurality of furnaces and whose temperature is set to gradually increase from the furnace on the sample inlet side to the furnace on the outlet side is preferably mentioned. As another method, after drying (pre-heat treatment) at a maximum heat treatment temperature of 90 ° C. to 180 ° C. in advance with a heat treatment apparatus, the heat treatment is passed through another heat treatment apparatus and heat-treated within the above maximum temperature range (post-heat treatment). The method of doing so is preferably mentioned. In the latter case, the post-heat treatment temperature is set to be higher than the pre-heat treatment temperature.

Further, when applying the first solution on the carrier, a known coating method can be used. Specific examples thereof include a knife coater, a die coater, and a lip coater, but the lip coater is preferable because it is a closed type and has a wide viscosity range.

After forming at least a tack-free surface on the surface of the first solution coated on the carrier as described above, a second solution composed of a polyimide precursor or a polyimide resin solution is applied to the second solution. Is heat-treated to form a first polyimide cured layer composed of a first solution and a second polyimide cured layer composed of a second solution. In this second heat treatment, the solvent of the applied second solution may be dried to make it tack-free, and then the first polyimide cured layer and the second polyimide cured layer may be formed. (When the first polyimide cured layer is formed by the first heat treatment, the second polyimide cured layer is formed by this second heat treatment). By forming the second polyimide hardened layer (or the first and second polyimide hardened layers) after making the tack-free state once in this way, the peelability at the interface of these polyimide hardened layers can be further enhanced. it can.

Regarding this second heat treatment, the heat treatment conditions for putting the second solution in the tack-free state are the same as the heat treatment conditions for putting the first solution in the tack-free state in the first heat treatment. Further, in forming the second polyimide cured layer (or the first and second polyimide cured layers), when the second solution is composed of the polyimide precursor, it is described in the first heat treatment above. It is the same as the heat treatment conditions for "almost completely imidizing", and it is preferable that the maximum temperature of the heat treatment in the second heat treatment is 100 ° C. to 450 ° C. More preferably, it is 180 ° C. to 360 ° C., and even more preferably 300 ° C. to 360 ° C. On the other hand, when the second solution is a polyimide resin solution, it is preferable that the maximum temperature of the heat treatment is 150 ° C. to 250 ° C.

By such a second heat treatment, a long polyimide laminated body is provided with the first polyimide cured layer and the second polyimide cured layer, and is separated from the conveyed body with the traveling direction of the conveyed body as the longitudinal direction. Can be done. Here, in obtaining the long polyimide laminate, the carrier may be separated before the second heat treatment, or may be separated after the second heat treatment. FIGS. 1 to 3 schematically show a state until a long polyimide laminate is obtained. FIG. 1 shows an example in which a long base material 2 wound in a roll shape is used as a carrier, and here, a second solution applied using a second monopump 6 is applied by a lip coater (not shown). After the work is performed and the second heat treatment is performed by the second heat treatment apparatus 7, the long base material 2 is separated. Further, FIG. 2 shows an example in which the endless belt 11 is used as a carrier, and FIG. 3 shows an example in which a metal drum 12 is used as a carrier, both of which are the first coated using the first mono pump 4. The carrier (endless belt 11, metal drum 12) is separated after the solution is applied from a lip coater (not shown) and the first heat treatment is performed by the first heat treatment apparatus 5. In order to separate the carrier before the second heat treatment as described above, it is desirable to form the first polyimide cured layer by the first heat treatment, and the carrier is formed after the second heat treatment. The adhesive strength between the carrier and the first polyimide cured layer is preferably 1 to 100 N / m, preferably 10 to 50 N / m, including the case of separation. The first heat treatment refers to the one performed by applying the first solution, and the second heat treatment refers to the one performed after applying the second solution, each of which is a plurality of heat treatments. Heat treatment may be included. In addition, the arrows in the figure indicate the traveling direction of the carrier or the like.

A preferable form for obtaining a long polyimide laminate is a heat treatment provided with an unwinding roll (unwinding portion) 1, a lip coater (not shown), a continuous drying furnace, and a continuous furnace as shown in FIG. A roll-to-roll (RTR) system including an apparatus (first heat treatment apparatus 5, second heat treatment apparatus 7) and take-up rolls (winding portions) 9 and 10 for a carrier and a polyimide laminate. It is better to use a coating drying and curing device. That is, the long base material 2 wound in a roll shape is attached to the unwinding roll (unwinding portion) 1, and while unwinding the long base material 2, the first and second solutions applied by the MONO pumps 4 and 6 are applied with a lip coater. The polyimide laminate 8 is formed on the long base material 2 by coating and heat-treating each. Then, the long base material 2-polyimide laminate 8 is separated, and the long base material 2 and the polyimide laminate 8 are wound into rolls by the respective take-up rolls (winding portions) 9 and 10. To. Further, the continuous drying furnace is one in which two or more drying furnaces are connected, and the temperature of each drying furnace can be adjusted individually. The preferable set temperature of the drying furnace is preferably set so as to be gradually increased from the furnace on the unwinding portion side to the furnace on the winding portion side. For example, the unwinding portion side furnace is set to 130 ° C., the winding section side furnace is set to 400 ° C., and the unwinding section side furnace and the winding section side furnace are set to any temperature of 130 ° C. to 400 ° C. .. Further, the continuous furnace is one in which a plurality of two or more furnaces are connected, and the temperature of each furnace can be adjusted individually. The preferable set temperature of the furnace is preferably set so as to be gradually increased from the furnace on the unwinding portion side to the furnace on the winding portion side. For example, the unwinding portion side furnace is set to 130 ° C., the winding section side furnace is set to 400 ° C., and the unwinding section side furnace and the winding section side furnace are set to any temperature of 130 ° C. to 400 ° C. ..

Further, after forming the polyimide laminate on the carrier, the carrier and the polyimide laminate are peeled off in the coating drying and curing device, and the long substrate is rolled in the winding portion for the long substrate. The polyimide laminate is wound into a roll at the winding portion for the polyimide laminate. With such a method, it is possible to improve the work efficiency in the post-process of forming the functional layer by transporting the wound polyimide laminate. In addition, the work efficiency when disposing or reusing the wound carrier is also good. Alternatively, after forming the polyimide laminate on the long base material, the long base material and the polyimide laminate are once separately wound into a roll shape by a winding portion while they are laminated, and then the unwinding portion, In addition, these are unwound using an RTR-type peeling device equipped with a take-up portion for a long base material and a polyimide laminate, and after peeling between the long base material and the polyimide laminate, the long base material is used. The long base material may be wound in a roll shape in the winding portion for the polyimide laminate, and the polyimide laminate may be wound in a roll shape in the winding portion for the polyimide laminate.

In the polyimide laminate obtained as described above, one of the first and second polyimide cured layers is used as a polyimide substrate film, and the other is used as a carrier film to form a functional layer on the polyimide substrate film in a later step. Then, the carrier film is separated to obtain a polyimide substrate film having a functional layer. That is, the carrier film may be composed of the first polyimide cured layer, the polyimide substrate film may be composed of the second polyimide cured layer, the polyimide substrate film is composed of the first polyimide cured layer, and the carrier film is the second polyimide cured layer. It may consist of. Preferably, in the former case (the carrier film is the first polyimide cured layer and the polyimide substrate film is the second polyimide cured layer) from the viewpoint that the surface smoothness of the polyimide substrate film is not affected by the surface smoothness of the carrier. It is good to have it.

The thickness of the polyimide substrate film is preferably 1 to 50 μm, preferably 1 to 20 μm, and more preferably 1 to 20 μm from the viewpoint of maintaining the strength of the polyimide substrate and enabling the production of a thin flexible device. It is preferably 1 to 15 μm. If the thickness of the polyimide substrate film exceeds 50 μm, it may deviate from the purpose when producing a thin flexible device, and conversely, if it is less than 1 μm, the strength of the flexible device tends to be insufficient. is there. The thickness of the carrier film is preferably 30 to 200 μm from the viewpoint of ensuring workability when forming the functional layer. If the thickness exceeds 200 μm, winding tends to be difficult, and if it is less than 30 μm, processing may become difficult. The first and second solutions to be applied may be adjusted so as to have these thicknesses.

Regarding the adhesive strength between the carrier film and the polyimide substrate film, the layers do not peel off when the functional layer is formed, and when the carrier film is separated after the functional layer is formed, the layers are separated from each other. It suffices if peeling is possible, and the adhesive strength between these layers is preferably 1 to 20 N / m, more preferably 1.5 to 15 N / m.

In the present invention, the carrier is coated with the first solution for forming the carrier film to form at least a tack-free surface, and then the second solution for forming the polyimide substrate film is coated twice. By performing the above, a polyimide substrate film having a plurality of polyimide layers may be formed. At that time, the second heat treatment may be divided into a plurality of times by performing the heat treatment at 60 ° C. to 300 ° C. each time the second solution is applied, and finally these may be imidized. , The coating of the second solution may be carried out in a plurality of times, and heat treatment may be performed at 60 ° C. to 300 ° C. to make the coated surface in a tack-free state, and finally imidization may be performed. In the former case, the polyimide substrate film can be individually separated by each polyimide layer, and in the latter case, a polyimide substrate film having a plurality of polyimide layers having different characteristics can be obtained.

Further, when the first solution for forming the carrier film is applied to the carrier, the first solution is applied twice or more to form a carrier film having a plurality of polyimide layers. You may. In that case, the first heat treatment may be performed each time the first solution is applied to bring it into a tack-free state, or the first solution may be applied in a plurality of times and collectively. The first heat treatment may be performed to form a tack-free surface on the outermost surface. In the former case, each property of the plurality of polyimide layers can be easily imparted to each layer individually, and in the latter case, each property can be easily imparted to each layer integrally. In addition, production efficiency is high.

By the way, when a flexible device such as a bottom emission type organic EL display device is manufactured using the polyimide substrate film with a functional layer of the present invention, the total light transmittance specified in JIS J 7375: 2008 is 80% or more. It is preferably present, preferably 85% or more. Similarly, when the flexible device is a touch panel, the total light transmittance of the polyimide substrate film at a thickness of 20 μm is preferably 90% or more, considering that the visibility of the display is required. ..

The difference (ΔCTE) between the coefficient of thermal expansion (CTE) of the polyimide substrate film and the CTE of the carrier film is preferably −25 ppm / K to 25 ppm / K. More preferably, it is −10 ppm / K to 10 ppm / K. When the difference in CTE is within these ranges, delamination and warpage between the carrier and the polyimide laminate can be suitably suppressed in obtaining the polyimide laminate, and the functional layer is formed on the polyimide substrate film. Delamination and warpage can be suitably suppressed even when the film is formed.

The surface of the polyimide substrate film forming the interface with the carrier film preferably has an arithmetic mean roughness (Ra) of 0 nm to 5 nm, more preferably 0.3 to 3 nm, and even more preferably 0. It is preferably 3 to 2 nm. In the present invention, since the first and second polyimide cured layers constituting the carrier film and the polyimide substrate film are both formed by the casting method, the flatness of these interfaces can be ensured. If the surface roughness of the polyimide substrate film forming the interface with the carrier film is within these ranges, there is no possibility that the polyimide substrate film will be peeled off when obtaining the polyimide laminate or forming the functional layer. In addition, it is possible to reliably eliminate the risk of damaging the polyimide substrate film or the functional layer when the carrier film is separated.

Similarly, the surface of the carrier film forming the interface with the polyimide substrate film also preferably has an arithmetic mean roughness (Ra) of 0 nm to 5 nm, more preferably 0.3 to 3 nm, and even more preferably 0.3 nm. It is preferably 0.3 to 2 nm. The surface of the carrier to which the first solution is applied preferably has an arithmetic mean roughness (Ra) of 0 to 3.5 nm, more preferably 0.3 to 3 nm, and even more preferably 0.3 to 3 nm. It is preferably 0.3 to 2 nm. If the surface roughness of the carrier to which the first solution is applied is within these ranges, it may be accidentally peeled off when the polyimide laminate is obtained, or it may be damaged when the carrier is separated from the polyimide laminate. The risk of giving can be reliably eliminated. The arithmetic mean roughness (Ra) is calculated from the measured values measured using an atomic force microscope (AFM) under the conditions specified in JIS B0601: 2013.

In the present invention, the polyimide for forming the carrier film is not particularly limited, but from the viewpoint of being inexpensive and easily available, pyromellitic anhydride (PMDA), 2,3,2'as an acid anhydride compound is preferable. , 3'-Biphenyltetracarboxylic acid dianhydride (BPDA) or 3,3', 4,4'-benzophenone tetracarboxylic acid anhydride (BTDA), whichever is one or more, is used as the diamine compound. 4'-diaminodiphenyl ether (4,4'-DAPE), 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB), or 2,2-bis [4- (4-aminophenoxy) phenyl ] It is preferable that the polyimide is reacted with any one or more of propane (BAPP). Of these, the acid anhydride compound is PMDA and the diamine compound is 4,4'-DAPE.

In the present invention, the carrier film serves as a pedestal when forming the functional layer on the polyimide substrate film side, and ensures the handleability, dimensional stability, etc. of the polyimide substrate film in the manufacturing process of the functional layer. However, it is removed after the flexible device is manufactured. Therefore, even if it is inferior in transparency, it does not matter. By using the polyimide laminate as in the present invention, it is possible to accurately and surely form a predetermined functional layer on the polyimide substrate film, and to obtain a flexible device that is thin, lightweight and flexible. Can be done. That is, the carrier film may be separated and removed immediately after the functional layer is formed through various process treatments, or it may be integrated with the polyimide substrate film for a certain period of time, and then separated after being bonded to other device members. You may try to remove it. Examples of device members include glass, plastic plates, films, circuit boards, and housings.

On the other hand, regarding the polyimide for forming the polyimide substrate film, considering heat resistance and transparency as the polyimide substrate film provided with the functional layer, 4,4'-oxydiphthalic anhydride (ODPA) is preferably used as the acid anhydride compound. , 1,2,3,4-cyclobutanetetracarboxylic acid anhydride (CBDA), 1,2,3,4-cyclohexanetetracarboxylic acid dianhydride (CHDA), or 2, Using any one or more of 2-bis (3,4-anhydrodicarboxyphenyl) hexafluoropropane (6FDA) and 4,4'-diamino-2,2'-bis (trifluoromethyl) as a diamine compound. One or more of biphenyl (TFMB), 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB), or 4,4'-(hexafluoroisopropylene) dianiline (4,46F) It is a polyimide that has been used and reacted. Of these, the acid anhydride compound is at least one of 6FDA, PMDA, or CBDA, and the diamine compound is at least one of TFMB or 4,46F.

Examples of the solvent for the polyimide precursor or the polyimide resin solution constituting the first and second solutions include N-methylpyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), and dimethyl sulfoxide. Side (DMSO), dimethyl sulfate, sulfolane, butyrolactone, cresol, phenol, halogenated phenol, cyclohexanone, dioxane, tetrahydrofuran, diglime type, triglime type, carbonate type (dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, ethylene carbonate, propylene carbonate) Others) and so on.

Further, the polyimide precursor solution or the polyimide solution may contain a mold release agent, if necessary. In addition, additives such as catalysts, antioxidants, heat stabilizers, antistatic agents, flame retardants, ultraviolet absorbers, and lubricants may be included.

As the functional layer formed on the polyimide substrate film, an element that guarantees the function of a known flexible device can be applied. For example, an organic EL / TFT, a photoelectric conversion element, an electronic paper drive element, a color filter, a touch panel, etc. A photoelectric conversion device and the like can be mentioned. As an example, when an organic EL display is manufactured as a flexible device, a TFT for driving an image can be mentioned as a functional layer. The material of the TFT is a silicon semiconductor or an oxide semiconductor. When a flexible substrate, which is a conventional technique, is not used, a barrier layer made of an inorganic component is provided on a hard support such as flat glass, and a TFT is formed on the barrier layer. At the time of this formation, a high temperature treatment (300 ° C. to 400 ° C. range) is required, and polyimide can withstand this high temperature treatment. When a touch panel is manufactured as a flexible device, examples of the functional layer include an electrode layer such as a transparent conductive film and a metal mesh. Examples of the transparent conductive film include ITO (tin-doped indium oxide), SnO, ZnO, and IZO. When these electrode layers are formed, a conductive layer having a small resistance value can be obtained by performing a heat treatment at 200 ° C. or higher, but polyimide can withstand this high temperature treatment. Not limited to the touch panel, when a transparent conductive film is used as a functional layer, it is also referred to as a "transparent conductive layer".

As described above, as a preferable form for forming the functional layer on the polyimide substrate film of the polyimide laminate, the long polyimide laminate is once wound on a winding roll, and then the polyimide laminate is unwound. However, it is preferable to continuously form the functional layer on the polyimide substrate film. Further, the wound polyimide laminate may be unwound and cut into a sheet having a predetermined length to form a functional layer on the polyimide substrate film for each sheet-shaped polyimide laminate.

After forming the functional layer on the polyimide substrate film, the carrier film of the polyimide laminate is separated to obtain a polyimide substrate film having the functional layer. Here, the method for separating the carrier film is not particularly limited, and a known method can be used. At that time, for example, the carrier film is peeled off by a mechanical means such as a tip picking tool such as tweezers for forming the peeling start portion, a suction plate, or air blowing applied to the peeling portion after the peeling start portion is formed. You may. For example, the edge of the carrier film is pinched with tweezers to peel off the carrier film, and using other tools (tweezers, sticks, blades, sheets, etc.) as a starting point, a polyimide substrate having a functional layer is provided. Try to separate the film completely. Alternatively, instead of the above tweezers, a needle-shaped, hook-shaped, or insect-foot-shaped tool is used to insert these tools into the interface between the carrier film and the polyimide substrate film with a functional layer, and peel off the edges of the carrier film. Alternatively, the polyimide substrate film with a functional layer may be sucked with a suction plate to peel off the carrier film. It can be said that the method using the suction plate as described above is a preferable method in that the polyimide substrate film with the functional layer can be stably gripped and conveyed at the same time as peeling. The suction plate may be flat or curved such as a semicircle. Further, after peeling off the end portion of the carrier film by any of the above methods, a suction plate or compressed air may be blown to peel off the carrier film.

Here, a case where a touch panel is manufactured using the long polyimide laminate in the present invention will be described as an example. In this example, an RTR type continuous manufacturing apparatus as shown in FIG. 4 is used, and this continuous manufacturing apparatus uses an unwinding roll (unwinding roll) for unwinding a long polyimide laminate 8 wound in a roll shape. A winding unit) 13, a transport roll (guide roll) 14, a process processing unit 15, and a winding roll (winding unit) 17 are provided. The polyimide laminate 8 unwound from the unwinding roll 13 passes through a transport roll 14 for preventing wrinkles and unwinding, and is subjected to a functional layer on the surface of the polyimide laminate on the polyimide substrate film side in the process processing unit 15. ITO is vapor-deposited at 100 ° C. to 400 ° C. to form a functional layer (ITO) on the polyimide laminate. After that, the polyimide laminate 16 having the functional layer is wound into a roll by the winding roll 17 through the transport roll 14.

Instead of depositing ITO by the process processing unit 15, ITO is provided on a resin film support such as polyethylene terephthalate or polyethylene, and the ITO surface is brought into close contact with the surface of the polyimide substrate film in the polyimide laminate, and then the resin film is supported. The body may be peeled off to form ITO on the polyimide laminate.

Next, while unwinding the polyimide laminate 16 with the functional layer wound in a roll shape, it is cut out into a sheet shape with a predetermined length. The size of the sheet can be arbitrarily determined according to the size of the touch panel to be manufactured. ITO in the cut-out sheet-shaped polyimide laminate with a functional layer is etched to form a circuit shape used as a touch panel. A known method can be used for etching. For example, a liquid or film photoresist (which may be negative or positive) is laminated on the surface of ITO. In the case of a liquid photoresist, the solvent may be volatilized by heat treatment after lamination and dried. Then, a known photomask patterned in a circuit shape is laminated on the photoresist, exposed with a known exposure machine, and developed with a known developer. The developer can be appropriately selected from an alkaline aqueous solution, an organic solvent and the like depending on the photoresist used. By development, a photoresist suitable for the shape of the circuit used as a touch panel remains on the surface of ITO. Then, the etching solution is brought into contact with the etching solution to remove ITO in the portion where the photoresist is not laminated. A known etching solution can be used, and examples thereof include iron chloride-based and copper chloride-based etching solutions. Then, the remaining photoresist is peeled off and washed with water. Further, the carrier film is peeled off using tweezers or the like to obtain a polyimide substrate film with ITO used as a touch panel.

Further, in the process processing unit 15 of the continuous manufacturing apparatus as shown in FIG. 4, the ITO is formed on the polyimide laminate, processed into the shape of a circuit used as a touch panel by etching, and then the polyimide with a functional layer is formed. The laminate is wound up with a take-up roll 17, and then, in the same manner as described above, it is cut out into a sheet having an arbitrary size according to the size of the touch panel to be manufactured, and the carrier film is further peeled off to be used as a touch panel. A polyimide substrate film with ITO may be obtained.

Further, as another form for manufacturing a touch panel using the long polyimide laminate in the present invention, silver or copper nanowires (hereinafter referred to as "nanowires") are known as ultraviolet light instead of ITO. It is also possible to form a functional layer by laminating using a curable adhesive. In that case, in the process processing unit 15 of the continuous manufacturing apparatus of the RTR method, an ultraviolet curable resin is applied to the surface of the polyimide laminate on the polyimide substrate film side, dried, and nanowires are laminated in the shape of a circuit. When laminating, a groove may be provided in the shape of the circuit, and nanowires may be provided in the groove. Then, the ultraviolet light-curable adhesive is cured by irradiating with ultraviolet light to bond the nanowires to the polyimide laminate, and the polyimide laminate 16 having the functional layer is wound into a roll by a winding roll 17. To. Next, while unwinding the polyimide laminate 16 with this functional layer, it is cut out into a sheet shape with an arbitrary length as in the case of the previous production example, the carrier film is peeled off, and the polyimide laminate 16 is used as a touch panel. A polyimide substrate film is obtained. At that time, the end face of the nanowire may be smoothed by polishing or the like.

Further, in the present invention, a long polyimide laminate is cut out in advance in a sheet shape according to the size of a flexible device such as a touch panel to be manufactured, and ITO is formed on the sheet-shaped polyimide laminate. , It may be processed into the shape of a circuit used as a touch panel by etching, and further, the carrier film may be peeled off to obtain a polyimide substrate film with ITO to be used as a touch panel or the like.

On the other hand, the case where the coverlay film is manufactured by using the long polyimide laminate in the present invention will be described as an example. Similar to the case of manufacturing a touch panel, the polyimide laminate 8 is unwound from the unwinding roll 13 using the RTR type continuous manufacturing apparatus as shown in FIG. 4, passed through the transport roll 14, and then the process processing unit 15. An adhesive layer is formed as a functional layer on the surface of the polyimide laminate on the polyimide substrate film side. As a method for forming the adhesive layer, for example, a coating device such as a lip coater is used, and a known resin material such as an epoxy resin, an acrylic resin, a polyimide resin, or a silicon resin, which is a raw material of the adhesive layer, or a solvent system A known adhesive (pressure sensitive adhesive) such as an adhesive, an emulsion adhesive, a hot melt adhesive, and a rubber adhesive is applied and dried. Then, the polyimide laminate with the adhesive layer is wound into a roll with a winding roll 17, and then cut into a sheet having an arbitrary size according to the size of the coverlay film to be manufactured, and the carrier film is peeled off. , To obtain a polyimide substrate film with an adhesive layer to be used as a coverlay film. When the adhesive is used as the adhesive layer, the adhesive layer is also referred to as an "adhesive layer". When the pressure-sensitive adhesive layer is used as the functional layer of the present invention, when the above-mentioned touch panel is manufactured, the cover is formed when ITO is formed on the polyimide laminated body, and then the cover layer is further laminated on the polyimide laminated body. It can also be used to bond layers.

In the present invention, in order to obtain a polyimide substrate film with a functional layer such as a polyimide substrate film provided with this adhesive layer, a winding roll for winding the carrier film is separately provided in the above-mentioned RTR type continuous manufacturing apparatus. It may be provided and a long polyimide substrate film with a functional layer may be wound up. That is, after forming a functional layer on the polyimide laminate in the process processing unit, the carrier film is peeled off in this RTR type continuous manufacturing apparatus, and the carrier film is wound by a winding roll (not shown). The take-up roll 17 winds up the polyimide substrate film with the functional layer. If necessary, the wound polyimide substrate film with a functional layer may be cut out into a sheet shape according to the size of the flexible device and used.

Further, in the case of manufacturing an organic EL display using the long polyimide laminate in the present invention, for example, it is cut out in a sheet shape in advance according to the size of the organic EL display for which the polyimide laminate is manufactured. , A glass sheet is laminated on the carrier film side surface of this sheet-shaped polyimide laminate. Then, a TFT, an electrode layer, a light emitting layer, and an electrode layer are sequentially formed as functional layers on the surface on the polyimide substrate film side, and these functional layers are hermetically sealed with a glass substrate, a multilayer thin film, or the like, and a glass sheet and a carrier film are formed. Is peeled off to obtain a polyimide substrate film with a functional layer that can be used as an organic EL display. By the way, the formation temperature at the time of forming the TFT is 300 to 500 ° C.

Further, when the liquid crystal display device is manufactured using the long polyimide laminate in the present invention, a known color filter resist ink using a vinyl ester resin, a phenol resin, an acrylic resin or the like as a base resin is used as a color. It may be mounted as a filter resist layer.

Further, when the above-mentioned various flexible devices are manufactured using the long polyimide laminate of the present invention, the following functional layers may be mounted in order to improve each characteristic. That is, in order to improve the abrasion resistance of the polyimide substrate film, a known compound such as a melamine resin, a urethane resin, an acrylic resin, a silicon resin, a silane compound, or a metal oxide may be mounted as a hard coat layer. Further, in order to suppress the permeation of oxygen and water vapor of the polyimide substrate film, a known gas barrier layer such as alumina or silica may be mounted. Further, in order to control the optical characteristics, dimensional stability, etc. of the polyimide substrate film, a known transparent resin such as a cyclic olefin resin or an ester resin may be mounted as a transparent resin layer.

Further, in addition to the above-mentioned functional layers, copper, silver, gold, titanium, tungsten, ITO, etc. are used for exchanging electronic signals between flexible devices, between flexible devices and output devices, or between flexible devices and input devices. A known wiring material may be mounted as a wiring layer.

As described above, the polyimide substrate film with the functional layer obtained by the present invention has excellent smoothness and less foreign matter is mixed. Since it is thin and has excellent light transmission, for example, it includes flexible displays such as organic EL, various flexible devices such as touch panels, electronic paper, and solar cells, as well as thin-film deposition masks and fan-out wafers. It is extremely suitable for obtaining a substrate for a level package (FOWLP) or the like.

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

<1. Various physical property measurement and performance test methods>
[Measurement of peel strength]
The peel strength between the carrier film and the carrier film and the peel strength between the carrier film and the polyimide substrate film are obtained by processing these laminates into strips with a width of 1 mm to 10 mm and a length of 10 mm to 25 mm. The carrier film was peeled off in the 180 ° direction using a tensile tester (Strograph-M1) manufactured by Co., Ltd., and the peeling strength was measured. Those with strong peeling strength and difficult peeling were classified as "non-peeling".

[Transmittance]
A polyimide substrate film was cut into 5 cm squares, and the total light transmittance was measured using HAZE METER NDH-5000 manufactured by Nippon Denshoku Kogyo.

[Surface Roughness Ra]
Regarding the surface roughness Ra of the carrier, the carrier film, and the polyimide substrate film, each was cut out into a 3 cm square, and this was cut out using an AFM manufactured by Bruker AXS to obtain a surface roughness Ra (JIS B0601: 2013). The measurement was performed.

[CTE]
The CTEs of the carrier, carrier film, and polyimide substrate film are cut into 3 mm x 15 mm squares, which are constant while applying a load of 5.0 g using a thermomechanical analysis (TMA) device manufactured by Seiko Instruments Inc. A tensile test was carried out in a temperature range of 30 ° C. to 260 ° C. at a temperature rising rate of 10 ° C./min), and CTE (× ^10-6 / K) was measured from the amount of elongation of the polyimide film with respect to the temperature.

<2. Synthesis of polyamic acid (polyimide precursor) solution>
The raw materials, aromatic diamino compounds, acid anhydrides and solvents of aromatic tetracarboxylic acids used for the synthesis of the polyamic acid (polyimide precursor) solution used in the following synthesis examples, examples and comparative examples are shown below.

[Aromatic diamino compound]
4,4'-diamino-2,2'-bis (trifluoromethyl) biphenyl (TFMB)
・ 4,4'-Diaminodiphenyl ether (4,5'-DAPE)
[Acid anhydride of aromatic tetracarboxylic acid]
-Pyromellitic anhydride (PMDA)
-2,2-bis (3,4-anhydrodicarboxyphenyl) hexafluoropropane (6FDA)
〔solvent〕
-N, N-dimethylacetamide (DMAc)

(Synthesis Example 1)
Under a nitrogen stream, TFMB (9.4 g) was added to 127.5 g of solvent DMAc with stirring in a 300 ml separable flask and heated to dissolve at 50 ° C. Then 6 FDA (13.09 g,) was added. 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 A varnish. The polyimide resin A (CTE: 70 ppm / K) can be obtained by curing this polyamic acid A varnish under the heating conditions described later.

(Synthesis Example 2)
Under a nitrogen stream, 4,4'-DAPE (10.753 g,) was added to 170 g of solvent DMAc with stirring in a 300 ml separable flask and heated to dissolve at 50 ° C. PMDA (11.747g) was then added. 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 B varnish. The polyimide resin B (CTE: 69 ppm / K) can be obtained by curing this polyamic acid B varnish under the heating conditions described later.

<3. Formation of PI layer by coating>
Each material handled in the following Examples and Comparative Examples is shown below.
・ Long base material (conveyor)
Polyimide film (UPIREX S manufactured by Ube Industries, Ltd.), thickness 0.75 mm, CTE: 18 ppm / K.
Polyimide film (Kapton 300H manufactured by Toray DuPont Co., Ltd.), thickness 75 μm, CTE: 27 ppm / K.

(Example 1)
Using the clean UPIREX S (width 508 mm × length 1100 m × thickness 0.75 mm) wound up in a roll as the long base material 2, the unwinding portion 1 as shown in FIG. 1 and the lip coater ( A roll provided with a heat treatment apparatus (first heat treatment apparatus 5, second heat treatment apparatus 7) equipped with a continuous drying furnace and a continuous furnace, and winding portions 9 and 10 for a carrier and a polyimide laminate (not shown). -While unwinding at a speed of 8 m / min with a to-roll type coating drying and curing device, the polyamic acid B varnish applied from the MONO pump 4 was coated so that the film thickness was 500 μm. This is passed through a continuous drying furnace (first heat treatment apparatus 5) composed of a plurality of furnaces and dried at 90 ° C. for 2 minutes and at 130 ° C. for 1 minute, and further composed of a plurality of furnaces on the sample inlet side. From the furnace to the outlet side furnace, the temperature is gradually increased through a continuous furnace (first heat treatment device 5), and the temperature is gradually increased from 130 ° C to 400 ° C for a total of 20 minutes, and the polyimide (polyimide) is heated in stages. Hardened layer) B was formed.

Next, the polyamic acid A varnish is applied from the MONO pump 6, and the polyamic acid A varnish is coated on the polyimide B so as to have a thickness of 150 μm, and a continuous drying furnace composed of a plurality of furnaces (second). It is passed through a heat treatment device 7) and dried at 90 ° C. for 2 minutes and at 130 ° C. for 1 minute. Further, it is composed of a plurality of furnaces, and the temperature gradually increases from the sample inlet side furnace to the outlet side furnace. A polyimide (polyimide hardened layer) A was formed by passing through a continuous furnace (second heat treatment apparatus 7) and heating stepwise from 130 ° C. to 400 ° C. for a total of 10 minutes. Then, while peeling off the long base material 2 Iupirex S, the laminate 8 of the polyimide B and the polyimide A was wound up by the winding unit 10 to obtain the roll-shaped polyimide laminate according to Example 1.

The thickness of each layer of the obtained polyimide laminate 8 was 50 μm for polyimide B and 15 μm for polyimide A. Further, the peel strength between UPIREX S (long base material) and polyimide B is 0.12 N / m, and the peel strength between polyimide B and polyimide A is 0.10 N / m, both of which can be easily pulled. It was possible to peel it off. On the other hand, the surface roughness Ra of polyimide A after peeling off at each interface is 1.0 nm, the surface roughness Ra of polyimide B is 1.0 nm, and the surface roughness Ra of Upirex S is 1. It was 15 nm. Furthermore, the light transmittance of polyimide A was 91%.

Next, the roll-shaped polyimide laminate 8 obtained above is roll-to-rolled with the unwinding portion 13, the transport roll 14, the process processing unit 15, and the winding unit 17 as shown in FIG. The functional layer was formed as follows using a roll-type continuous manufacturing apparatus. That is, the polyimide laminate 8 is conveyed at a speed of 5 m / min, and while being unwound in the longitudinal direction so that the polyimide A surface to be the polyimide substrate film is on top, the vacuum chamber is passed through the transfer roll 14. It was introduced into a process processing unit 15 installed inside, and ITO having a thickness of 50 nm was formed on the polyimide A surface by continuous processing by a sputtering method in the process processing unit 15. Then, the polyimide laminate 16 with the functional layer provided with ITO was wound into a roll by the winding portion 17.

The polyimide laminate 16 with a functional layer obtained above was cut into a sheet of 370 mm × 450 mm while unwinding, and the film-formed ITO was subjected to XY transparent circuit processing. At that time, the intersection of the Y circuit and the X circuit did not form a circuit.

Next, an overcoat is applied to the intersection of the Y circuit and the X circuit and heat-treated at 250 ° C. to cure the overcoat layer, and a silver paste is used to perform bridge processing across the overcoat layer to perform the XY circuit. Was completed, and an overcoat was applied again to the entire surface of the ITO film-forming side, and annealing treatment was performed at 270 ° C. to cure the overcoat layer and crystallize ITO.

Next, OCA (Optically Clear Adhesive Tape, 8146-2 manufactured by 3M Co., Ltd.) was attached to the surface of the reapplied overcoat layer, and a cover glass was further attached thereto. Then, the polyimide B used as the carrier film was mechanically peeled off to complete a flexible touch panel substrate.

(Comparative Example 1)
The clean Kapton 300H (width 520 mm × length 1100 m × thickness 75 μm, surface roughness Ra = 4.0 nm) wound in a roll shape is shown in FIG. 1 by a roll-to-roll method of coating, drying and curing. While unwinding at a speed of 8 m / min by the apparatus, a polyamic acid A varnish is applied from the MONO pump 4 so that the film thickness becomes 150 μm, and the mixture is passed through a continuous drying furnace composed of a plurality of furnaces to 90. 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, and from 130 ° C. The mixture was stepwise heated to 400 ° C. for a total of 10 minutes to form a polyimide A having a thickness of 15 μm. Then, the laminate of Kapton 300H and polyimide A was wound up to obtain a roll-shaped polyimide laminate according to Comparative Example 1.

Here, in the obtained roll-shaped polyimide laminate, the polyimide A could not be peeled off from the Kapton 300H, so that the functional layer was not formed. The surface roughness Ra of the exposed surface of polyimide A was 1.0 nm.

1: Unwinding roll (unwinding part)
2: Long base material (conveyor)
3: Transport roll (guide roll)
4: 1st mono pump 5: 1st heat treatment device 6: 2nd mono pump 7: 2nd heat treatment device 8: Polyimide laminated body 9: Winding roll for carrier (winding part)
10: Winding roll for polyimide laminate (winding part)
11: Endless belt (conveyor)
12: Metal drum (conveyor)
13: Unwinding roll (unwinding part)
14: Transport roll (guide roll)
15: Process processing unit 16: Polyimide laminate with functional layer 17: Winding roll (winding part)

Claims (15)

A first solution composed of a polyimide precursor or a polyimide resin solution is applied onto a continuously supplied carrier, and the first heat treatment is performed to form a tack-free surface at least on the surface of the first solution. Next, by applying a second solution composed of a polyimide precursor or a polyimide resin solution and performing a second heat treatment, the first polyimide cured layer composed of the first solution is provided while continuously supplying the carrier. together and a second polyimide cured layer made of the second solution, a step Ru to obtain a polyimide laminate long separated from the conveying member to the traveling direction of the conveying member as a longitudinal direction,
One of the first and second cured polyimide layers in the long polyimide laminate is used as a polyimide substrate film, the other is used as a carrier film, a functional layer is formed on the polyimide substrate film, and then the carrier film is separated. And the process of obtaining a polyimide substrate film with a functional layer ,
A method for producing a polyimide substrate film with a functional layer, which comprises . The long polyimide laminate is once wound on a winding roll, and then a functional layer is continuously formed on the polyimide substrate film while unwinding the polyimide laminate, or the polyimide laminate is wound. The method for producing a polyimide substrate film with a functional layer according to claim 1, wherein a functional layer is formed on the polyimide substrate film for each sheet-shaped polyimide laminate by cutting out into a sheet shape with a predetermined length while taking out. The function according to claim 1 or 2, wherein in obtaining the long polyimide laminate, the carrier is separated before the second heat treatment or after the second heat treatment. A method for manufacturing a layered polyimide substrate film. The method for producing a polyimide substrate film with a functional layer according to any one of claims 1 to 3, wherein the carrier is a metal drum, an endless belt, or a long base material wound in a roll shape. The carrier is a long base material wound in a roll shape, and while unwinding the long base material, coating of the first solution, the first heat treatment, and coating of the second solution. The method for producing a polyimide substrate film with a functional layer according to any one of claims 1 to 3, wherein the operation and the second heat treatment are sequentially performed, and then the long base material is separated to obtain a long polyimide laminate. .. The method for producing a polyimide substrate film with a functional layer according to any one of claims 1 to 5 , wherein the carrier film is composed of a first polyimide cured layer and the polyimide substrate film is composed of a second polyimide cured layer. The method for producing a polyimide substrate film with a functional layer according to any one of claims 1 to 5 , wherein the polyimide substrate film is composed of a first polyimide cured layer and the carrier film is composed of a second polyimide cured layer. A first solution composed of a polyimide resin solution is applied onto the carrier, and a first heat treatment is performed with a maximum temperature of 60 ° C. to 300 ° C. to form a tack-free surface on the surface of the first solution. The method for producing a polyimide substrate film with a functional layer according to any one of claims 1 to 7 . A first solution made of a polyimide precursor is applied onto the carrier and a first heat treatment is performed with a maximum temperature of 100 ° C. to 450 ° C. to form a first polyimide cured layer made of the first solution. The method for producing a polyimide substrate film with a functional layer according to any one of claims 1 to 7 . The method for producing a polyimide substrate film with a functional layer according to any one of claims 1 to 9 , wherein the maximum temperature of the heat treatment in the second heat treatment is 100 ° C. to 450 ° C. Claimed that the interlayer adhesion strength between the first polyimide cured layer and the second polyimide cured layer is 1 to 20 N / m, and the thickness of the first or second polyimide cured layer used as the polyimide substrate film is 1 to 50 μm. Item 8. The method for producing a polyimide substrate film with a functional layer according to any one of Items 1 to 10 . The method for producing a polyimide substrate film with a functional layer according to any one of claims 1 to 11 , wherein the first or second polyimide cured layer to be the polyimide substrate film has a total light transmittance of 80% or more. Claims 1 to 12 wherein the carrier is made of a long base material wound in a roll shape, and the long base material is a polyimide film, a SUS foil, a copper foil, or a composite in which two or more of these are laminated. The method for producing a polyimide substrate film with a functional layer according to any one of. The function according to any one of claims 1 to 13 , wherein two or more kinds of first solutions composed of the polyimide precursor or the polyimide resin solution are overcoated and coated to form a first polyimide cured layer. A method for manufacturing a layered polyimide substrate film. The function according to any one of claims 1 to 13 , wherein two or more kinds of second solutions composed of the polyimide precursor or the polyimide resin solution are overcoated and coated to form a second polyimide cured layer. A method for manufacturing a layered polyimide substrate film.

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