Laminated sheet

Abstract

To provide a long laminated sheet a polyimide layer having excellent visibility with less variation in visibility.SOLUTION: There is provided a long laminated sheet having a support and a polyimide layer laminated on the support, wherein the length of the laminated sheet in the width direction perpendicular to the longitudinal direction is 500 mm or more and 1200 mm or less, for at least eight test pieces with dimensions of 50 mm (length)×50 mm (width) taken at symmetrical locations with respect to a center line connecting the middle points of the entire length of the polyimide layer in the width direction and at least eight test pieces with dimensions of 50 mm long×50 mm wide taken at a distance of 200 mm in the longitudinal direction from the respective sampling positions of the at least eight test pieces, the standard deviation of HAZE in the evaluation of variation using at least the total 16 test pieces is within the range of 0.25% or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a long laminated plate including a support and a polyimide layer laminated on the support.

Background Art

[0002] In recent years, with the progress of miniaturization, weight reduction, and space saving of electronic devices, there has been an increasing demand for flexible printed circuit boards (FPCs) that are thin, lightweight, flexible, and have excellent durability even when repeatedly bent. Since FPCs enable three-dimensional and high-density mounting even in limited space, their applications are expanding, for example, to wirings in movable parts of electronic devices such as HDDs, DVDs, and smartphones, and to components such as cables and connectors. Many FPCs are manufactured by forming a circuit on the metal layer of a metal-clad laminated plate (particularly Flexible Cupper Clad Laminate: FCCL) obtained by laminating a metal layer using a metal foil or the like and an insulating resin base material (for example, a polyimide resin layer).

[0003] In subsequent mounting processes of FCCL, when aligning marks or the like are recognized by a camera through the resin layer at the location where a metal foil such as a copper foil is etched during circuit pattern formation, positioning may be performed. Therefore, visibility is required such that the light transmitted through this resin layer can be clearly recognized by the camera without being diffused. Further, in the photolithography process for FCCL, various processes such as bonding, cutting, exposure, and etching may be performed based on alignment marks provided on the FCCL. In order to maintain processing accuracy, it is required to accurately recognize the alignment marks through the resin layer of the FCCL.

[0004] However, when the light transmittance of the resin layer is low, when scattering, refraction, etc. are large, or when there are causes such as non-uniform thickness and distortion of the resin layer, the visibility through the resin layer may decrease. As a result, the alignment marks may not be accurately recognized, which may lead to a decrease in the accuracy of the above-mentioned processing.

[0005] Regarding the visibility of the resin layer, when trying to identify and improve the above-mentioned causes, the appropriate conditions vary for each material, and there is also a tendency for the margin of manufacturing conditions, etc. to obtain them to be narrow. Therefore, it takes time to optimize the conditions and may also lead to a decrease in work efficiency.

[0006] As one method for improving the visibility of such a resin layer, heretofore, attention has been paid to HAZE (turbidity), and studies have been made to reduce the HAZE as much as possible. Since this HAZE depends on the surface shape and surface state of the resin layer, it has been necessary to prevent the surface (the surface that becomes the pressure-bonding surface, coating surface, etc. depending on the manufacturing method) transferred from the support such as copper foil during manufacturing from being rough. However, when the transfer surface of the support is too smooth, there are also concerns that the gloss (reflection) of the support surface becomes high, which conversely affects the visibility of the resin layer, or that the adhesion to the resin layer is impaired due to its smoothness. Based on such points, studies have been made on the surface of the support (copper foil) in contact with the above-mentioned transfer surface (pressure-bonding surface, coating surface) in the resin layer, especially the lightness L * Techniques using copper foil blackened to a lightness L value of 30 or less (for example, Patent Document 1), and techniques for reducing the diffuse reflectance by roughening treatment with pure copper in consideration of the adhesion and visibility after circuit pattern formation in the application of a wiring board (for example, Patent Document 2) have been proposed.

[0007] Here, for example, as methods for manufacturing a laminate having a polyimide layer on a support such as an FPC or an FCCL, there have conventionally been a lamination method and a casting method. The casting method is a method of forming a polyimide layer by applying a precursor solution of polyimide onto a support (for example, a metal layer such as a copper foil), followed by drying and curing. A high adhesive force can be obtained between the support and the polyimide layer, and it is excellent in terms of dimensional stability, improvement in heat resistance, adjustment of layer configuration, etc. As a method for manufacturing a laminate of a support and a polyimide layer by the casting method, from the viewpoint of productivity, for example, while unwinding a roll-shaped support, continuously applying a precursor solution of polyimide, and drying the obtained sheet-like substrate while continuously running it in a floating state in a hot air stream in a floating form, and then winding it up in a roll shape. This is carried out by a roll-to-roll method. Thereby, an intermediate roll body in which a long laminate is wound in a roll shape can be manufactured. For the roll body, usually, it is in the state of the roll body, or the precursor resin layer of polyimide is heat-cured (imidized) while unwinding the roll body.

[0008] However, it is often difficult to strictly manage such a manufacturing process. In a long laminate, it is difficult to identify factors that affect the visibility of the resin layer as described above and manufacture it while reducing variations in their characteristics and quality. When manufacturing such a long laminate, variations during manufacturing lead to variations in the width direction and length direction of the resin layer, and also lead to variations within the resin layer plane. Further, in a manufacturing method via a roll body to obtain a long laminate, since the coating surface of the precursor solution of polyimide inevitably comes into contact with the back surface of the support, it is considered necessary to also deal with the influence of the back surface side of the support on the coating surface. However, in the prior art, there has been little consideration focused on the in-plane variations in various characteristics of such a resin layer, and the consideration has not been sufficient.

[0009] Moreover, FPCs, which are particularly excellent in transparency, have characteristics such as being thin, lightweight, bendable, and crack-resistant, and are thus applied to display devices such as liquid crystal display devices, organic EL display devices, touch panels, color filters, and electronic papers, as well as their components (for example, Patent Document 3). Furthermore, in recent years, there have been glass antennas that use it as a transparent antenna and form it on the surface of window glass to localize the window, technologies for embedding antennas in displays in mobile applications, or an expanding demand for substrate applications in fields where the installation of large electro-optical panels and LED transparent displays including LED visions is expected. In such new applications, particularly high substrate visibility is required, so there is concern that even a slight variation in visibility may cause a change in the amount of light, and it is necessary to suppress the variation in visibility within the resin layer. However, even in FPCs with excellent transparency, no studies have been conducted focusing on the in-plane variation of various properties of such resin layers.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0011] Therefore, based on the above problems of the prior art, the inventors of the present application conducted intensive studies. Surprisingly, they found that the surface characteristics of the back side of the support that comes into contact with the polyimide layer when winding into a roll also have an impact. And based on such findings, by optimizing the surface characteristics of the back side of the support, they found that a long laminated plate provided with a polyimide layer with reduced in-plane variation in HAZE can be obtained, thus completing the present invention. In addition, they also found that while suppressing the in-plane variation in HAZE of the polyimide layer, variations in other characteristics related to visibility other than HAZE can also be suppressed.

[0012] Accordingly, an object of the present invention is to provide a long laminated plate provided with a polyimide layer having excellent visibility with little variation in visibility. Also, with regard to the excellent visibility of such a long polyimide layer, it is also an object of the present invention to provide a method for clarifying a method for evaluating the in-plane variation in HAZE of the polyimide layer.

Means for Solving the Problems

[0013] That is, the gist of the present invention is as follows. (1) A long laminated plate comprising a support and a polyimide layer laminated on the support, wherein the length in the width direction orthogonal to the longitudinal direction of the laminated plate is 500 mm or more and 1200 mm or less, at least 8 test pieces taken in a size of 50 mm in length × 50 mm in width at symmetric positions with respect to the center line connecting the midpoints of the total length in the width direction of the polyimide layer, and at positions 200 mm apart in the longitudinal direction from the respective sampling positions of the at least 8 test pieces, for at least 8 test pieces taken in a size of 50 mm in length × 50 mm in width, the standard deviation of HAZE in the evaluation of variation using the at least 16 test pieces in total is within a range of 0.25% or less. The laminated plate is characterized by this. (2) The laminated plate according to (1), wherein the polyimide layer has an HAZE of 50% or less. (3) The laminate according to (1) or (2), wherein the total light transmittance of the polyimide layer is 70% or more. (4) The laminate according to (1) or (2), wherein the standard deviation of the in-plane total light transmittance in the variation evaluation of the polyimide layer is 0.25% or less. (5) For at least 26 measurement points at symmetric positions with respect to the center line connecting the midpoints of the entire length in the width direction of the polyimide layer, and at least 26 measurement points located at a distance of 200 mm in the longitudinal direction from the at least 26 measurement points, the standard deviation of the thickness of the polyimide layer at the at least total 52 measurement points is 0.35 μm or less. The laminate according to claim 1 or 2. (6) The laminate according to (1) or (2), wherein the surface roughness Ra of the polyimide layer is 10 nm or less. (7) The laminate according to (1) or (2), wherein the polyimide layer has 3 or fewer streaks with a width of 0.1 mm or more and a length of 10 cm or more. (8) A laminate obtained by cutting the laminate according to (1) or (2) along the longitudinal direction, having a length in the width direction orthogonal to the longitudinal direction of 250 mm or more.

Advantages of the Invention

[0014] According to the present invention, a long laminate provided with a polyimide layer having excellent visibility with little variation in visibility can be obtained.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described.

[0017] The laminate of the present embodiment includes a support and a polyimide layer laminated on the support. Here, regarding the laminate of the present embodiment, from the viewpoint of more greatly expressing the effect of improving the in-plane variation of the characteristics related to visibility, the length in the width direction (hereinafter also referred to as TD) orthogonal to the longitudinal direction (hereinafter also referred to as MD) is 500 mm or more and 1200 mm or less. This is because when the laminate is continuously manufactured, the effect of the invention becomes particularly remarkable if the film in the width direction is relatively wide.

[0018] Also, regarding the laminate being long, the length in the longitudinal direction is not limited. For example, the following embodiments of the length can be adopted. That is, embodiments such as 1 m or more, 2 m or more, 10 m or more, 50 m or more, 100 m or more, 500 m or more, 1000 m or more in order can be cited. Examples of the embodiment of the laminate having a relatively large length in the longitudinal direction include, but are not limited to, a roll body as described later. For example, it also includes a laminate obtained by slitting a continuously manufactured laminate at a certain value in the width direction and / or the longitudinal direction. For example, after manufacturing the laminate having a width of 500 mm or more and 1200 mm or less, a slitting process of cutting along the longitudinal direction can be performed to obtain a laminate having a length in the width direction orthogonal to the longitudinal direction of 250 mm or more.

[0019] <Standard Deviation of HAZE of Polyimide Layer> As described above, the laminate of the present embodiment has little in-plane variation in the characteristics related to visibility, and particularly has a small standard deviation of the HAZE of the polyimide layer. Since the small standard deviation of the HAZE of the polyimide layer suppresses the variation from the average value, for example, it is possible to suppress the variation in processing and treatment based on the aforementioned alignment marks in actual use using the laminate and improve the accuracy. Also, in various applications using an FPC with excellent transparency, it is possible to suppress the variation in the amount of light. The standard deviation of the HAZE is 0.25% or less, preferably 0.20% or less, more preferably 0.18% or less. It is most preferable that the numerical value is low, and there is no need to set a lower limit value.

[0020] Regarding the evaluation method of the standard deviation of the HAZE of the polyimide layer, test pieces are sampled by the following method, the HAZE of the sampled test pieces is measured, and the standard deviation is calculated based on each measured value. Specifically, it is as follows. That is, as also shown in the embodiments described later, first, the support is removed from the laminated board that has been manufactured. The method for removing the support is not limited and can be performed by known methods. When the support is a copper foil, for example, a method of etching the copper foil can be mentioned. After obtaining the polyimide layer from which the support has been removed, as shown in FIG. 1, first, a center line connecting the midpoints of the entire length in the width direction of the obtained polyimide layer is determined. Next, based on the center line, sampling positions with dimensions of 50 mm in the longitudinal direction (MD) × 50 mm in the transverse direction (TD) are determined at symmetric positions in the width direction (left and right). At this time, at least 8 sampling positions and sampling numbers are provided based on the center line. The reason for setting at least 8 is to obtain more reliable results so that the entire width direction can be evaluated without unevenness. The total number of samplings on the left and right can be appropriately changed depending on the length and degree of variation in the width direction. There is no upper limit to the number of samplings on the left and right, but for the reason of being able to measure the variation in the entire width direction, it is preferably 10 locations, more preferably 14 locations. For example, as shown in FIG. 1, left and right regions are provided based on the center line, and at symmetric positions in the width direction, a total of 8 locations shown as 1 to 4 in the left region and 5 to 8 in the right region at 10 mm intervals are set as the sampling positions. Here, the interval between the test pieces is exemplified as 10 mm because it is for taking a sufficient number of samples in the width direction. However, for example, when the variation is large and more locations are to be measured, the interval can be made even narrower.

[0021] Next, at positions 200 mm apart in the longitudinal direction from each of the sampling positions of the at least 8 test pieces described above, similarly, sampling positions of at least 8 test pieces sampled with dimensions of 50 mm in the longitudinal direction × 50 mm in the transverse direction are provided. For example, as shown in FIG. 1, at positions 9 to 12 and 13 to 16 in the lower row, which are 200 mm apart in the longitudinal direction from 1 to 4 and 5 to 8 shown in the upper row, sampling positions with the same dimensions of 50 mm × 50 mm are provided. Here, the reason for leaving a distance of 200 mm in the longitudinal direction is that the variation in the longitudinal direction can be measured more accurately.

[0022] Then, using at least a total of 16 test pieces exemplified at the sampling positions 1 to 16 in FIG. 1 above, the HAZE of each sampling position is measured, and the standard deviation is calculated using all the measured values of HAZE. The standard deviation is calculated based on the ordinary mathematical formula shown in the examples.

[0023] In the laminate of the present embodiment, since the standard deviation of the HAZE of the polyimide layer calculated in this way is small, the variation in the in-plane HAZE can be suppressed, and thereby, the above-described effects can be achieved. Since the laminate of the present embodiment is long, preferably, by collecting and evaluating test pieces in a similar manner in the longitudinal direction, the in-plane variation of the polyimide layer in the long laminate can be measured. That is, following the sampling positions 9 to 12 and 13 to 16 described above, leaving the same fixed distance as described above, similarly, as the upper layer, at least in the left region, 17 to 20 and in the right region, 21 to 24, and as the lower layer, at least in the left region, 25 to 28 and in the right region, 29 to 32, a method of providing sampling positions for measuring HAZE and calculating the standard deviation can be mentioned. Thereafter, it is preferable to provide sampling positions at the same fixed distance in the longitudinal direction and perform measurement and evaluation. Regarding the "fixed distance" at this time, considering the length in the longitudinal direction of the laminate, the measurement time, etc., for example, it is preferable to perform evaluation leaving a distance for each one-third of the total length in the longitudinal direction, but it is not limited thereto. For example, when the sampling positions of at least the total of 16 test pieces are regarded as one region, measurement can be performed on 2 or 3 regions out of a total of 3 regions including at least the regions at the first and last ends in the longitudinal direction and the middle thereof.

[0024] <Standard deviation other than HAZE of polyimide layer> Further, regarding the polyimide layer of the laminate of the present embodiment, it is preferable that not only the above-described HAZE but also the variation in other characteristics related to visibility is small. That is, in the same method as the evaluation method of the standard deviation of HAZE described above, the total light transmittance, yellowness index (YI), and L * a * b *L of the color system * (Brightness) is measured respectively, and by calculating the standard deviation, it can be confirmed that the variation within the plane of these characteristics is small. These measurements can also be performed by the methods shown in the examples. Further, the standard deviation is calculated based on the ordinary mathematical formulas shown in the examples.

[0025] The standard deviation of the total light transmittance is preferably 0.25% or less, more preferably 0.20% or less.

[0026] Also, the standard deviation of YI is preferably 1.35 or less, more preferably 1.00 or less, and even more preferably 0.50 or less.

[0027] Also, L * The standard deviation of is preferably 0.74 or less, more preferably 0.60 or less, and even more preferably 0.50 or less.

[0028] <HAZE, total light transmittance, YI and L * Range of Also, for the above-mentioned HAZE, total light transmittance, YI and L * Regarding, it is also preferable that not only the standard deviation but also the range indicating the variation due to the difference between the maximum value and the minimum value in each measurement item is small. Since a small range indicates that not only the above-mentioned standard deviation but also the characteristics are less uneven and more uniform, and there are fewer locally weak parts, it is more preferable. For this range, test pieces are sampled in the same manner as the evaluation of the standard deviation, and the maximum value and the minimum value of each measured value measured thereby are taken out and calculated from "maximum value - minimum value".

[0029] Here, the range of HAZE is preferably 1.0% or less, more preferably 0.8% or less, and even more preferably 0.7% or less.

[0030] The range of the total light transmittance is preferably 1.0% or less, more preferably 0.8% or less, and even more preferably 0.6% or less.

[0031] Also, the range of YI is preferably 5 or less, more preferably 3 or less, still more preferably 1 or less.

[0032] Also, L * The range is preferably 3.0 or less, more preferably 2.0 or less, still more preferably 1.5 or less, and even more preferably 1.2 or less.

[0033] <HAZE, total light transmittance, YI and L of the polyimide layer * > Furthermore, from the viewpoints of the visibility and light transmittance of the polyimide layer itself, not only the above-mentioned in-plane variation (standard deviation, range), but also the HAZE of the polyimide layer is preferably 90% or less, more preferably 70% or less, still more preferably 50% or less, even more preferably 10% or less, and most preferably 5% or less. The lower limit is not limited, but for example, it is preferably 0.05% or more, more preferably 0.1% or more, and still more preferably 0.2% or more. Regarding this HAZE, it is preferable that this numerical range is satisfied for the entire polyimide layer regardless of the measurement location. Therefore, regarding the HAZE of the entire polyimide layer, it may be calculated from the average value of the measured values of at least a total of 16 test pieces in the evaluation of the standard deviation and range.

[0034] Similarly, the polyimide layer of the laminate of the present embodiment is preferably nearly transparent, and the total light transmittance of the entire polyimide layer is preferably 70% or more, more preferably 75% or more. Also, YI is preferably 90 or less, more preferably 70 or less, still more preferably 50 or less, and most preferably 30 or less. For example, at a polyimide layer thickness of 25 μm, it is preferable that this numerical range is satisfied. By controlling to such a numerical range, the polyimide layer can be made nearly colorless. On the other hand, when YI exceeds the above numerical range, yellow to yellow-brown coloring becomes stronger and the visibility tends to decrease, but it can be appropriately selected according to the application and the like. Further, L * is preferably 50 or more, more preferably 70 or more, still more preferably 90 or more.

[0035] <Thickness of polyimide layer> Regarding the polyimide layer of the laminate of the present embodiment, from the viewpoints of workability, transportability, and supportability of the film itself during the process, it is preferably in the thickness range of 9 to 100 μm. Although it can be appropriately selected according to the intended use and the like, since high transparency is preferred, it is more preferably 9 to 80 μm, and even more preferably 9 to 60 μm. As will be described later, the polyimide layer may be formed of a single layer or a plurality of layers. And, since it is preferable to suppress variations in visibility, it is preferable that the standard deviation of the thickness of the polyimide layer is small. When the standard deviation of the thickness of the polyimide layer is small, variations in thickness from the average value can be suppressed as in the case of the above-mentioned HAZE, etc. Therefore, for example, variations in processing and treatment based on the above-mentioned alignment marks in actual use using the laminate can be suppressed and the accuracy can be improved. Also, in various applications using an FPC with excellent transparency, variations in the amount of light can be suppressed. The standard deviation of the thickness is preferably 0.35 μm or less, more preferably 0.30 μm or less, and even more preferably 0.25 μm or less. It is most preferable that the numerical value is low, and there is no need to set a lower limit value. Also, the thickness range is preferably 2.5 μm or less, more preferably 2.0 μm or less, and even more preferably 1.5 μm or less.

[0036] And, regarding the method for evaluating the standard deviation of the thickness of the polyimide layer, it is different from the method of collecting test pieces such as the measurement of the above-mentioned HAZE, etc., and specifically is as follows. That is, for the polyimide layer from which the support has been removed, at least 13 measurement points are provided at symmetric positions in the width direction (left and right) with respect to the center line as shown in Fig. 2. Here, the reason for setting at least 13 for each and a total of 26 is that by providing many measurement points, the variation from the average value of the thickness can be obtained over the entire width direction. The total number of measurement points on the left and right can be appropriately changed according to the length in the width direction and the degree of variation. Although there is no upper limit for the measurement points on the left and right, for the reason that it can be evaluated evenly and accurately, it is preferably 30 points, more preferably 40 points. For example, as shown in Fig. 2, left and right regions are provided with reference to the center line, and at symmetric positions in the width direction, 26 positions shown as 1 to 13 from the left end in the left region and 14 to 26 in the right region at intervals of 20 mm are used as the sampling positions. Here, the interval between the test pieces is exemplified as 20 mm because the variation in thickness over the entire width direction can be evaluated evenly. However, for example, when evaluating the variation in more detail, the interval can be made narrower.

[0037] Next, at positions 200 mm apart in the longitudinal direction from each sampling position of the at least 26 test pieces described above, at least 26 measurement points are similarly provided. For example, as shown in Fig. 2, at positions 27 to 39 and 40 to 52 in the lower stage, which are 200 mm apart in the longitudinal direction from 1 to 13 and 14 to 26 in the upper stage, the same measurement points as described above are provided.

[0038] Then, using at least a total of 52 test pieces exemplified at the sampling positions 1 to 26 and 27 to 52 in Fig. 2, the thickness of each measurement point is measured, and the standard deviation is calculated using all the measured values of the thickness. The calculation of the standard deviation is the same as described above.

[0039] Regarding the thickness as well, since the laminate of the present embodiment is long, preferably, by installing and evaluating measurement points at similar positions in the longitudinal direction, it becomes possible to measure the in-plane variation of the polyimide layer in the long laminate. That is, following the above-mentioned sampling positions 27 to 39 and 40 to 52, leaving the same fixed distance as described above, for example, in the same manner, as the upper row, at least in the left region, 53 to 65 and in the right region, 66 to 78, and as the lower row, at least in the left region, 79 to 91 and in the right region, 92 to 104, a method of providing measurement points for thickness measurement and calculating the standard deviation can be mentioned. Thereafter, it is preferable to leave a fixed distance and provide measurement points in the longitudinal direction in the same manner for measurement and evaluation. Here, regarding the "fixed distance", it is preferable to be the same as in the case of the above-mentioned HAZE and the like.

[0040] <Surface roughness of the polyimide layer> Since the larger the surface roughness of the polyimide layer, the more likely the HAZE deteriorates and the visibility decreases when irradiating light, the surface roughness Ra of the polyimide layer is preferably 10 nm or less, more preferably 8 nm or less, and even more preferably 6 nm or less. The lower limit value of Ra is not limited, but it is preferably 1 nm or more. Also, the surface roughness Rz is preferably 100 nm or less, more preferably 80 nm or less, and even more preferably 60 nm or less. The lower limit value of Rz is not limited, but it is preferably 10 nm or more. It is preferable that the Ra and Rz satisfy the above numerical ranges on the surface in contact with the support.

[0041] <Support> The support used in the laminate of this embodiment is not limited as long as it can withstand imidization (heat curing) when forming the polyimide layer formed on the support, and examples include metal, Teflon (registered trademark), polyimide film, glass fiber fabric, etc. In a flexible printed wiring board (FPC), a metal layer is preferably used, and examples include copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, tantalum, titanium, lead, magnesium, manganese, and alloys thereof. Among these, a metal element of copper, iron or nickel, or indium tin oxide (ITO) is preferred, and copper (copper foil) is more preferred. As the copper foil, either an electrolytic copper foil or a rolled copper foil can be used. In selecting the metal layer, it is selected so as to exhibit the characteristics required for the purpose of use, such as conductivity, light transmittance of the polyimide layer, and adhesiveness to the polyimide layer. There is no particular limitation on the shape of the metal layer, but appropriate processing etc. may be carried out according to the application. A roll-shaped one formed in a long shape is preferably used.

[0042] The thickness of the support is not particularly limited, but is preferably 100 μm or less, more preferably in the range of 0.1 to 50 μm, and even more preferably in the range of 1 to 35 μm.

[0043] Since the support used in the laminate of this embodiment affects, for example, HAZE etc. as the surface characteristics of the polyimide layer after removing the support from the laminate, the surface roughness Ra of the surface of the support in contact with the polyimide layer (hereinafter sometimes referred to as the M surface) is preferably 0.01 μm or more and 0.12 μm or less, more preferably 0.01 μm or more and 0.10 μm or less. Also, the surface roughness Rz of the M surface of the support is preferably 0.06 μm or more and 0.85 μm or less, more preferably 0.06 μm or more and 0.6 μm or less, and even more preferably 0.06 μm or more and 0.5 μm or less.

[0044] In addition, regarding the support, as described above, the surface characteristics of the M surface that usually contacts the polyimide layer should be noted. However, for long products such as the laminate of the present embodiment, an embodiment in which it is continuously manufactured as a roll body as described later is preferably used. Then, when winding as a roll body, regardless of the winding direction, the surface on which the polyimide layer is formed (that is, the surface on which the resin layer of polyamic acid as a precursor is formed) inevitably contacts the back surface of the support on the side opposite to the M surface (hereinafter, this may be referred to as the S surface). Therefore, the surface characteristics of the S surface are also important. When wound as a roll body, the surface of the resin layer (or polyimide layer) of polyamic acid contacts the S surface of the support, and the surface profile of the S surface is transferred as it is to the polyimide layer surface. That is, in the laminate of the present embodiment, it is preferable that the surface roughness of the S surface of the support is defined, and such a viewpoint has not been found conventionally. Here, the Ra of the S surface of the support is preferably 0.01 μm or more and 0.10 μm or less, more preferably 0.01 μm or more and 0.07 μm or less, and even more preferably 0.01 μm or more and 0.05 μm or less. Also, the surface roughness Rz of the S surface of the support is preferably 0.06 μm or more and 0.6 μm or less, more preferably 0.06 μm or more and 0.4 μm or less, and even more preferably 0.06 μm or more and 0.3 μm or less.

[0045] <Method for manufacturing a laminate> The manufacturing method of the laminate of the present embodiment is not limited. For example, when using a metal layer as the support, after preparing the polyimide layer having the above characteristics, sputtering metal thereon to form a seed layer, and then forming a metal layer by, for example, plating, it can be prepared. As another method, after preparing the polyimide layer having the above characteristics, it can be prepared by laminating a metal layer such as a copper foil thereto by a method such as thermocompression bonding. As another method, a polyamic acid, which is a precursor of polyimide, is applied onto a metal layer such as a copper foil, dried, and if necessary, the application and drying are repeated a plurality of times to form a coating film, and then heat-treated to imidize to form a polyimide layer, it can also be prepared. Further, as another method, it can also be prepared by a method such as applying and drying a laminated structure of polyamic acid simultaneously by multi-layer extrusion onto a support and then performing imidization. Among these, from the viewpoints of controlling dimensional stability, adhesion between the polyimide layer and the support, and HAZE of the polyimide layer after removing the support, etc., it is preferable to form a laminate by applying polyamic acid onto the support.

[0046] Hereinafter, as a preferable laminate, a method of manufacturing a laminate by using a method of applying polyamic acid onto a support and passing through a roll body will be exemplified and described. When obtaining a roll body, preferably, a method of using a protective film for the purpose of protecting the resin layer of the outermost polyamic acid applied can be mentioned, and the method using a protective film will be particularly described. However, the present embodiment also includes an embodiment without using a protective film. The specific procedure of the preferable manufacturing method of the laminate using a protective film is as follows. That is, I) A step of laminating at least one layer of a resin layer of polyamic acid on a support; II) A step of disposing a protective film on the surface of the outermost resin layer of polyamic acid among the resin layers of polyamic acid laminated in the step I and winding it around a core to obtain a roll body of a laminate with a protective film; III) A step of peeling the protective film while unwinding the roll body of the laminate with a protective film from the core; IV) After the step III, a step of imidizing the resin layer of the polyamic acid to form a polyimide layer is included. Even when the protective film is not used, it may be in the form of a roll in the same procedure as described above.

[0047] 〔Step I〕 In the step I of the present embodiment, at least one layer of a polyamic acid resin layer is laminated (hereinafter, may be described as "formed") on a support. As the support, those as described above can be used.

[0048] (Method for laminating the polyamic acid resin layer) As a method for laminating a polyamic acid (described later) resin layer on a support, although not limited, preferably, it is performed by applying a solution of polyamic acid on the support and drying it. That is, it is dried until the solvent concentration (solid content concentration) in the applied polyamic acid solution reaches a predetermined range, so as to form a polyamic acid resin layer (hereinafter, may be simply described as "resin layer").

[0049] The method for applying the polyamic acid solution is not limited and can be performed by a known method. For example, it can be applied with a coater such as comma, die, knife, lip, etc. In this step I, a multilayer polyamic acid resin layer may be formed. In that case, as described above, a method of repeating a series of operations of applying the polyamic acid solution to the support and drying it a plurality of times can be mentioned. Alternatively, by multi-layer extrusion, a multi-layer structure of polyamic acid may be applied and dried simultaneously to form a multi-layer polyamic acid resin layer on the support (multi-layer extrusion method).

[0050] As a method for drying the polyimide acid solution applied on the support, it is not limited and can be performed using any method or apparatus. For example, it is preferable to adopt a floating type method. That is, as illustrated in FIG. 3, it is preferable to run the support coated with the polyamic acid solution in a state of continuously floating in the hot air flow in a drying furnace.

[0051] The drying conditions can be appropriately set based on factors such as the amount of solvent to be volatilized (i.e., the solid content concentration of the polyamic acid). Usually, it can be carried out at a temperature of 150°C or lower, preferably in the range of 60°C to 130°C. However, depending on the composition of the polyamic acid, as the degree of drying increases, curling or folding at the edges may occur due to differences in shrinkage stress between the support and the resin layer laminated thereon. Therefore, it is preferable to set the drying conditions to prevent this. That is, in order to alleviate such a difference in shrinkage stress between the support and the resin layer, it is preferable to set the drying conditions so that a certain amount of solvent remains in any one or all of the resin layers of the polyamic acid to be laminated.

[0052] A more preferable degree of drying is such that the residual solvent amount in any one or all of the resin layers of the polyamic acid to be laminated is in the range of 30 to 45% by mass. For the resin layer for which it is preferable to set the residual solvent amount within the above range, it can be appropriately determined according to the composition of the polyamic acid and the like. That is, it may be such that a resin layer having a residual solvent amount outside the above range and a resin layer dried to the above residual solvent amount are laminated. In the present embodiment, in order to prevent the occurrence of curling and folding as much as possible, it is preferable to dry at least the main resin layer (described later) so that the residual solvent amount is within the above range. More preferably, it is preferable to dry so that the residual solvent amounts of the main resin layer and the resin layer laminated directly above it are within the above range.

[0053] The drying conditions when setting the residual solvent amount within the above range can be appropriately set. For example, the drying temperature is preferably 60 to 120°C, more preferably 65 to 90°C. The drying time can be set according to the configuration of the drying apparatus, the length of the line, etc., and residence time, etc. are also considered, but it is preferably about 3 to 10 minutes.

[0054] In addition to the amount of residual solvent, the degree of drying of the polyamic acid resin layer can also be confirmed, for example, by checking the degree of adhesion of the resin layer or by checking from the storage modulus E' by dynamic viscoelasticity measurement (DMA). As a specific method for confirming the degree of adhesion, when the polyamic acid resin layers after drying are bonded together and held under a predetermined pressure and time, the degree of drying can be confirmed by checking that there is no adhesion and no change in the appearance pattern at the bonding surface. Regarding the confirmation by DMA, the dynamic viscoelasticity of the polyamic acid resin layer is measured with a dynamic thermomechanical analyzer while heating from 20°C to 200°C at a rate of 10°C / min, and it is preferable that the storage modulus E' at 30°C is 3 GPa or less, and more preferably, it is dried so as to be in the range of 1 GPa or more and 3 GPa or less from the viewpoint of suppressing the curl of the metal laminate due to polyimide shrinkage.

[0055] 〔Process II〕 In Process II, a protective film is disposed on the surface of the outermost resin layer of the polyamic acid resin layer with respect to the laminate of the support and the polyamic acid resin layer obtained in the above Process I. Further, in Process II, the laminate with the protective film disposed thereon (the laminate with the protective film) is wound around a winding core to obtain a roll body of the laminate with the protective film.

[0056] The protective film is not limited in its arrangement range and material as long as it protects the outermost resin layer and prevents damage due to contact with the support during subsequent winding and the transfer of the surface characteristics of the support to the coating surface of the resin layer. The protective film may cover and protect a part or all of the main surface side where the outermost resin layer is exposed, and more preferably, it is preferable that all of the main surface side is covered. From the viewpoint of manufacturing efficiency, when laminating a plurality of polyimide layers, it is preferable to laminate a plurality of polyamic acid resin layers by the method in the above Process I and then dispose a protective film on the outermost layer.

[0057] Also, as the material of the protective film, a resin film is preferably used. Examples of the resin film include, but are not limited to, polyester, polyethylene, polyethylene terephthalate, polyimide, polyethylene naphthalate, etc., which are preferable from the viewpoints of smoothness, flexibility, elastic modulus, supportability, transparency, etc. Among these, from the viewpoints of smoothness, transparency, and flexibility, it is more preferable to use polyethylene, polyester, or polyethylene terephthalate.

[0058] Also, the protective film may have adjusted adhesiveness. If the adhesive force between the protective film and the resin layer on which it is disposed is too weak, the protective film may peel off during subsequent winding. On the other hand, if the adhesive force is too strong, when peeling the protective film in Step III described later, it becomes difficult to peel off, and there is a risk of breakage, streaks, wrinkles, etc. occurring on the resin layer side. Therefore, it is preferable to use a protective film having an adhesive force with the resin layer on which it is disposed of 0.01 to 0.2 N / 25 mm. Also, the 90-degree peel strength between the protective film and the resin layer at that time is preferably 0.05 kN / m or more and 0.4 kN / m or less.

[0059] Also, the protective film may be composed of multiple layers. For example, it may be a structure in which another layer such as a release layer or an adhesive layer is provided on a base material made of the above-mentioned resin film, and is not limited. Also, the protective film usually has a thickness of about 10 to 100 μm, but from the viewpoint of handleability, etc., it is more preferably 20 to 50 μm.

[0060] The method of disposing the protective film is not limited. As illustrated in FIG. 3, for example, a roll body around which the protective film is wound is prepared in advance during the process, and the protective film is unwound and pressure-bonded to the main surface of the resin layer in accordance with the movement of the dried laminate (a laminate of a support and a resin layer) traveling from roll to roll on the production line. In addition, in the case of a protective film having an adhesive layer, cold dry lamination without applying heat is effective. The lamination conditions are not particularly limited as long as the substrate does not wrinkle. However, a laminate with good appearance can be obtained by performing lamination with a clearance for the total thickness of the support thickness, resin layer thickness, and protective film thickness.

[0061] Next, after obtaining the laminate with the protective film disposed as described above, a roll body of the laminate with the protective film is obtained by winding the laminate with the protective film around a core. It is preferable that the winding is performed while the laminate is traveling on a roll on the production line as exemplified above. The core is not particularly limited and may have a shape or material commonly used in the art. Examples of the shape include a solid or hollow cylindrical shape (i.e., a cylindrical shape) or a polygonal prism shape. Examples of the material include plastic, metal, or paper (paper tube).

[0062] The method of winding the laminate with the protective film around a core to obtain a roll body is not limited, but it is preferably a method in which at least the resin layer and the support do not suffer damage such as streaks or wrinkles or deformation such as curling. For example, it is preferable to adjust the winding tension while checking the winding state. For example, it is good to wind with a winding tension in the range of about 50 to 100 N, preferably 70 to 90 N, to form a roll body. Adjusting the winding tension is preferable because it can suppress the occurrence of wrinkles during excessive tension, the occurrence of unwinding during low tension, and the occurrence of tight winding during unwinding in the next process.

[0063] Also, although there is no restriction on the winding direction (the direction of the winding surface) during winding, in order to suppress the occurrence of curl that tends to occur toward the resin layer side and the peeling of the protective film, etc., it is preferable to wind the roll so that the support is on the outside (the resin layer with the protective film is on the inside).

[0064] Regarding the roll of the laminate with the protective film obtained by such a method, it is preferable that any one or all of the resin layers satisfy the above-mentioned residual solvent amount. Further, it is preferable that the roll has no occurrence of adhesion of the resin layer as described above, and also that the storage elastic modulus E' of the resin layer by DMA is within the above-mentioned range.

[0065] 〔Process III〕 In Process III, while unwinding the roll of the laminate with the protective film obtained in Process II, the protective film is peeled off.

[0066] The method of unwinding the roll is not limited, but similar to the case of winding, it is preferably a method that does not cause damage such as streaks or wrinkles to at least the resin layer and the support.

[0067] The method of peeling the protective film is not limited either, but similarly, it is preferably a method that does not cause damage such as streaks or wrinkles to at least the resin layer and the support. For example, while running the laminate with the protective film in the state of being unwound from the roll on the roll, while fixing the end portions of the protective film and the other laminate of the laminate with the protective film to different cores with an adhesive tape, etc., and winding them onto separate cores, a method of peeling the protective film simultaneously with winding can be mentioned. Also, a method using a peeling device capable of tension control, etc., can be mentioned.

[0068] Regarding the laminate from which the protective film has been peeled off, it may be directly fed into the next step IV without being wound up in this step III. Alternatively, the laminate with the protective film peeled off may be temporarily stored. Further, when the step of laminating the above-described polyamic acid resin layer on the laminate after peeling off the protective film is repeatedly performed, it may be once stored as a roll of the laminate (without the protective film), or the polyamic acid resin layer may be laminated as it is without forming a roll.

[0069] When further laminating a polyamic acid resin layer on the laminate after unwinding from the roll and peeling off the protective film, the following step I' and step II' similar to the above-described step I and step II can be performed. That is, a step (step I') of laminating at least one layer of a polyamic acid resin layer on the resin layer side of the laminate from which the protective film has been peeled off in this step III can be performed in the same manner as in step I. Next, in the same manner as in step II, a step (step II') of disposing a protective film on the surface of the outermost polyamic acid resin layer laminated in this step I' and winding it around a core to obtain a roll of the laminate with the protective film can be performed.

[0070] Furthermore, with respect to the roll of the laminate with the protective film obtained through such step II', in the same manner as in this step III, by unwinding from the core after step II', the protective film can be peeled off, and a laminate (a support and a polyamic acid resin layer (multiple layers)) from which the protective film has been peeled off can be obtained (step III'). It is also possible to further laminate a polyamic acid resin layer on the resin layer of the laminate obtained after this step III' in the same manner as above.

[0071] [Step IV] Then, with respect to the support and the polyamic acid resin layer obtained by performing the previous step III or, further, steps I' to III' thereon, imidization is carried out with the resin layer laminated on the support to convert the resin layer into a polyimide layer. Thereby, a laminate having a single layer or a plurality of polyimide layers laminated on the support can be obtained.

[0072] The method of the imidization is not limited, and known methods can be used. For example, a laminate of a support with the protective film peeled off and a polyamic acid resin layer is passed through a heat drying furnace while running on a roll and heated at a temperature condition in the range of about 80 to 400°C, preferably 120 to 370°C, for about 5 minutes to 24 hours, preferably for about 5 minutes to 1 hour. Such heat treatment is preferably employed. The heating time can be appropriately set according to the thickness of the resin layer, the amount of residual solvent (solid content concentration), the type of solvent, etc., and the completion of polyimidization can be judged, for example, based on the presence or absence of the peak of polyamic acid by IR spectrum.

[0073] Regarding the obtained laminate, it can be appropriately changed according to the type of the support and the composition of the polyimide. However, the method of the present embodiment is particularly useful in that it can form a polyimide layer with excellent visibility and excellent optical properties and relatively high transparency on the support. That is, as described above, in the method of the present embodiment, since it is preferable to dispose a protective film on the surface of the resin layer at an appropriate position in the manufacturing process, even when passing through the roll of the laminate on the way, damage to the resin layer side does not occur, and it is also possible to suppress the transfer of the S surface profile of the support to the resin layer, and a polyimide layer with characteristics related to visibility hardly impaired can be formed on the support. By using the protective film, it is possible to suppress the occurrence of streak-like patterns on the surface of the polyimide layer that may occur due to the tension and rigidity of the support by contacting the support. Preferably, the occurrence of streaks with a width of 0.1 mm or more and a length of 10 cm or more is preferably 3 or less, and more preferably, no streaks occur. Further, by using the protective film, it is preferable because it is possible to reduce the in-plane variation (standard deviation, range) of the total light transmittance, which is a characteristic related to visibility. Regarding the optical properties of the polyimide layer, excluding the influence in the manufacturing process, it can be appropriately adjusted according to the raw materials (acid anhydrides and diamines described later) constituting the polyamic acid.

[0074] As a preferred embodiment of the laminate of the present embodiment, a metal-clad laminate in which the support is a metal layer (for example, a copper foil) is preferably used as the FPC. In the case of a metal-clad laminate, in particular, it is preferable that the 180-degree peel strength in a 1-mm-wide laminate of the support and the polyimide layer is 0.5 kN / m or more.

[0075] Regarding the laminate obtained in Step IV, after forming an adhesive layer that does not inhibit optical properties or the like directly or as necessary on the polyimide layer side, the support (for example, a metal layer) can be laminated by means such as heat pressing to obtain a laminate in which supports are laminated on both outermost layers.

[0076] (Composition of the polyamic acid resin layer and polyimide layer) Here, the polyamic acid used in the present embodiment is a precursor of polyimide, and is composed of an acid anhydride residue which is a tetravalent group derived from a tetracarboxylic dianhydride (hereinafter sometimes simply referred to as "acid anhydride") component, and a diamine residue which is a divalent group derived from a diamine compound (hereinafter sometimes simply referred to as "diamine") component. When these constituent components are connected and regarded as one repeating unit, it is composed of a polymer of that repeating unit. It is possible to control the structure by adjusting the charged amounts (molar ratio) of the acid anhydride component and the diamine component.

[0077] Generally, polyamic acid is obtained by dissolving a predetermined acid anhydride component and diamine component in an organic solvent in approximately equimolar amounts and stirring them at a temperature in the range of usually 0 to 100 °C for 30 minutes to 50 hours to cause a polymerization reaction. In this reaction, the reaction components are dissolved so that the resulting precursor is usually in the range of 5 to 30% by weight, preferably in the range of 10 to 20% by weight, in the organic solvent (the same as the solvent in the above-mentioned residual solvent). Examples of the organic solvent include N,N-dimethylformamide, N,N-dimethylacetamide (DMAC), N-methyl-2-pyrrolidone, 2-butanone, dimethyl sulfoxide, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diglyme, triglyme, γ-butyrolactone, etc. These solvents can also be used in combination of two or more kinds, and furthermore, a combination with aromatic hydrocarbons such as xylene and toluene is also possible.

[0078] In the synthesis of polyamic acid and polyimide, only one kind of each of the acid anhydride component and the diamine component may be used, or two or more kinds may be used in combination. Also, by selecting the molar ratio of each, physical properties such as, for example, thermal conductivity, thermal expansion, adhesiveness, optical properties (such as transparency), glass transition temperature, tear propagation resistance, end crack resistance, tensile elongation, etc. can be controlled.

[0079] In addition, a terminal blocking agent may be used for the polyamic acid. Monoamines or dicarboxylic acids are preferable as the terminal blocking agent. The charged amount of the terminal blocking agent to be introduced is preferably in the range of 0.0001 mol or more and 0.1 mol or less, particularly preferably in the range of 0.001 mol or more and 0.05 mol or less, per 1 mol of the acid anhydride component. Examples of the monoamine terminal blocking agent include methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3-methylbenzylamine, aniline, 4-methylaniline, etc. Among these, benzylamine and aniline can be preferably used. As the dicarboxylic acid terminal blocking agent, dicarboxylic acids are preferable, and a part of them may be in a ring-closed form. For example, phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, cyclopentane-1,2-dicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, etc. are recommended. Among these, phthalic acid and phthalic anhydride can be preferably used.

[0080] In addition, although not limited, the polyamic acid preferably has a viscosity in the range of 1,000 to 200,000 cP by adjusting the concentration and the weight average molecular weight Mw. When the viscosity is high, it may be diluted by adding a solvent. The weight average molecular weight Mw of the polyamic acid is preferably in the range of, for example, 10,000 or more and 500,000 or less, more preferably in the range of 50,000 or more and 500,000 or less. When the weight average molecular weight is less than 10,000, the strength of the film tends to decrease and it tends to become brittle. On the other hand, when the weight average molecular weight exceeds 500,000, the viscosity increases excessively and uneven film thickness, streaks, and other defects are likely to occur during the coating operation.

[0081] Here, the acid anhydride component and the diamine component constituting the polyamic acid used in the present embodiment are not limited, and all known acid anhydride components and diamine components can be used. And the method of the present embodiment is particularly suitable when laminating a resin layer and a polyimide layer of a polyamic acid having the following composition.

[0082] (Regarding the main layer) That is, the polyimide constituting the main layer of the resin layer of the polyamic acid and the polyimide layer formed therefrom preferably contains either or both of a diamine residue derived from any one or more selected from the group consisting of an aromatic diamine compound containing a fluorine atom, an aromatic diamine compound containing a fluorene structure, and an alicyclic diamine compound containing an alicyclic structure, and an acid anhydride residue derived from any one or more selected from the group consisting of an aromatic tetracarboxylic dianhydride containing a fluorine atom, an aromatic tetracarboxylic dianhydride containing a fluorene structure, and an alicyclic tetracarboxylic dianhydride containing an alicyclic structure.

[0083] These diamine compounds and acid anhydrides have a bulky structure containing fluorine atoms or a fluorene structure, or an alicyclic structure, so that the interactions such as π-π stacking between polymer chains can be reduced, and the formation of charge transfer complexes within and between molecules can be suppressed. Therefore, it is preferable in that a polyimide having excellent optical properties can be obtained.

[0084] Here, the "main layer" means having the largest thickness when a plurality of resin layers of polyamic acid and polyimide layers are provided, and preferably refers to a layer having a thickness of 60% or more, more preferably 70% or more, and even more preferably 80% or more with respect to the total thickness of all layers. The main polyimide layer is preferably composed of a non-thermoplastic polyimide.

[0085] (Acid anhydride component of the main layer) Here, as the acid anhydride component used in the polyamic acid of the present embodiment, as described above, in the main layer, it preferably contains an acid anhydride derived from any one or more selected from the group consisting of an aromatic tetracarboxylic dianhydride containing a fluorine atom, an aromatic tetracarboxylic dianhydride containing a fluorene structure, and an alicyclic tetracarboxylic dianhydride containing an alicyclic structure. In the acid anhydride component of the main layer, these tetracarboxylic dianhydrides are preferably in an amount of 10 mol parts or more and less than 50 mol parts based on 100 mol parts in total of all the acid anhydride components. Including these tetracarboxylic dianhydrides, in the main layer, it is preferable to contain those represented by the following formula (1) and / or an alicyclic tetracarboxylic dianhydride having an alicyclic structure.

[0086]

Chemical formula

[0087] Examples of the compound represented by such formula (1) include 4,4'-oxydiphthalic dianhydride (ODPA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 2,2-bis(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride (6FDA), 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, and the like.

[0088] Examples of the alicyclic tetracarboxylic dianhydride containing an alicyclic structure include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, cycloalkanone bisspironorbornanetetracarboxylic dianhydride, and the like.

[0089] The remaining anhydride component of the main layer is not limited, but from the perspective of dimensional stability (coefficient of thermal expansion (CTE)), it preferably contains a tetravalent anhydride residue (hereinafter sometimes referred to as "PMDA residue") derived from pyromellitic dianhydride (PMDA) represented by the following formula B1. The PMDA residue is preferably contained in an amount of 50 mole parts or more, more preferably in the range of 60 mole parts or more and 90 mole parts or less, based on 100 mole parts in total of all the anhydride components in the main layer. If the PMDA residue is less than 50 mole parts, the CTE of the main layer may increase and the dimensional stability may decrease.

[0090]

Chemical formula

[0091] In addition, the main layer may generally contain any other anhydride component other than those used in the synthesis of polyimide.

[0092] (Diamine component of the main layer) In addition, as the diamine component in the main layer, it preferably contains a diamine derived from any one or more selected from the group consisting of aromatic diamine compounds containing a benzidine skeleton, aromatic diamine compounds containing a fluorine atom, aromatic diamine compounds containing a fluorene structure, and alicyclic diamine compounds containing an alicyclic structure. In the diamine component of the main layer, these diamine compounds are preferably in the range of 50 mole parts or more and 100 mole parts or less based on 100 mole parts in total of all the diamine components. Including these diamine compounds, it is preferable that the main layer contains a diamine represented by the following formula (2) or an alicyclic diamine compound having an alicyclic structure.

[0093]

Chemical formula

[0094] Examples of the compound represented by such formula (2) include diamine compounds such as bis(4-aminophenyl) terephthalate, 4,4'-diaminobenzanilide (DABA), 4,4'-diamino-2'-methoxybenzanilide (MABA), 4-aminophenyl-4-aminobenzoate (APAB), 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl (TFMB), 3,4-diamino-2,2'-bis(trifluoromethyl)biphenyl, 2,2-bis(4-aminophenyl)hexafluoropropane, 9,9-bis(4-aminophenyl)fluorene, 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB).

[0095] Examples of the alicyclic diamine compound containing an alicyclic structure include isophoronediamine, norbornanediamine, 1,6-cyclohexanediamine, piperazine, and the like.

[0096] In addition, the main layer may generally contain any other diamine compound used in the synthesis of polyimide. These other diamine compounds are preferably less than 50 mol parts with respect to 100 mol parts in total of all diamine components.

[0097] (Regarding the layer other than the main layer) Regarding the polyamic acid resin layer and the polyimide layer formed therefrom in the present embodiment, as described above, they may be provided as multiple layers. In the case of multiple layers, as the finally formed laminate, a two-layer structure of a polyimide layer P1 directly laminated on a support (for example, a metal layer) and a polyimide layer P2 not directly laminated on the support may be used. Configurations 1 to 4 exemplified below and other configurations are possible and not limited, but preferably three layers, and more preferably, it is preferable to include a third polyimide layer P3 and laminate them in the order of P1 / P2 / P3. M1 and M2 represent the support, and M1 and M2 may be the same or different. The polyimide layer P1 directly laminated on the support and the third polyimide layer P3 may have the same composition. For example, when forming a plurality of polyimide layers by the casting method according to the above-described steps I to IV (including I' to III'), a two-layer structure in which the polyimide layer P1 directly laminated on the support from the casting surface and the polyimide layer P2 not directly laminated on the support are laminated in this order may be used, or a three-layer structure in which the polyimide layer P1 directly laminated on the support from the casting surface side, the polyimide layer P2 not directly laminated on the support, and the third polyimide layer P3 are laminated in this order may be used. The "casting surface" mentioned here refers to the surface on the support side when forming the polyamic acid resin layer (polyimide layer). The surface on the opposite side of the casting surface is called the laminate surface. As described above, in the laminate obtained in the present embodiment, a support can also be laminated on the laminate surface.

[0098] Configuration 1; M1 / P1 / P2 Configuration 2; M1 / P1 / P2 / P1 (or P3) Configuration 3; M1 / P1 / P2 / P1 (or P3) / M2 (or M1) Configuration 4; M1 / P1 / P2 / P1 (or P3) / P2 / P1 (or P3) / M2 (or M1)

[0099] The polyimide constituting the polyimide layer P1 and the polyimide layer P3 is preferably a thermoplastic polyimide, which improves the adhesiveness of the polyimide layer and is suitable for application as an adhesive layer to the support.

[0100] A preferred embodiment of the polyimide layer laminated in this embodiment has a thermoplastic polyimide layer P1 and a non-thermoplastic polyimide layer P2 (main layer) composed of a non-thermoplastic polyimide, and it is preferable to have a polyimide layer P1 that becomes a thermoplastic polyimide layer on at least one side of this non-thermoplastic polyimide layer P2. That is, the polyimide layer P1 may be provided on one or both sides of the non-thermoplastic polyimide layer.

[0101] Also, the non-thermoplastic polyimide layer constitutes a low coefficient of thermal expansion polyimide layer, and the thermoplastic polyimide layer constitutes a high coefficient of thermal expansion polyimide layer. Here, the low coefficient of thermal expansion polyimide layer refers to a polyimide layer having a coefficient of thermal expansion (CTE) preferably in the range of 1 ppm / K or more and 25 ppm / K or less, more preferably in the range of 3 ppm / K or more and 25 ppm / K or less. Also, the high coefficient of thermal expansion polyimide layer refers to a polyimide layer having a CTE preferably in the range of 35 ppm / K or more, more preferably in the range of 35 ppm / K or more and 80 ppm / K or less, and still more preferably in the range of 35 ppm / K or more and 70 ppm / K or less. The polyimide layer can be made into a polyimide layer having a desired CTE by appropriately changing the combination of raw materials used, thickness, drying and curing conditions.

[0102] The coefficient of thermal expansion (CTE) of the entire polyimide layer laminated in this embodiment is preferably in the range of 10 to 30 ppm / K. By controlling within such a range, deformation such as curl can be suppressed, and high dimensional stability can be ensured. Here, the CTE is the average value of the coefficients of thermal expansion in the MD and TD of the insulating resin layer.

[0103] Here, the non-thermoplastic polyimide generally refers to a polyimide that does not soften or show adhesiveness even when heated. In this embodiment, the storage elastic modulus at 30°C measured using a dynamic viscoelasticity measuring device (DMA) is 1.0×10 9 Pa or more, and the storage elastic modulus at 350°C is 1.0×10 9It refers to polyimide with a pressure above Pa. Also, thermoplastic polyimide (also referred to as "TPI") generally means polyimide for which the glass transition temperature (Tg) can be clearly confirmed. In this embodiment, however, the storage modulus at 30 °C measured using DMA is 1.0×10 9 Pa or more, and the storage modulus at 300 °C is 1.0×10 8 Pa or less.

[0104] Among the polyimide layers, when the thickness of the polyimide layer P1 in contact with the support is T1 and the thickness of the main polyimide layer is T2, the thickness of T1 is preferably in the range of 1 μm or more and 4 μm or less, and the thickness of T2 is preferably in the range of 4 μm or more and 30 μm or less. From another perspective, the thickness of T1 is preferably 50% or less of the total thickness. Note that "main" is as described above.

[0105] In such a preferred embodiment exemplified as above, for example, each layer of the polyamic acid resin layer forming the polyimide layers P1 to P3 on the support may be laminated in the procedure of arranging the protective film and passing through the roll as in the above steps I to III (including steps I' to III'), or as described above, for example, it may not include the step of arranging the protective film or winding around the roll between the first resin layer and the second resin layer. The same applies to other layers. In particular, when laminating the polyamic acid resin layer for the thermoplastic polyimide P1 on the support and then laminating the polyamic acid resin layer for the non-thermoplastic polyimide P2 (main layer), the resin layer for the next P2 may be laminated without arranging the protective film. This is because the resin layer for the P1 is usually thin, easily volatilizes the solvent, and is easy to dry, so there is little transfer to the winding surface when winding. Furthermore, after laminating as a plurality of layers of polyamic acid resin layers by sequential coating or multilayer extrusion as described in the above step I, steps II to IV may be performed to form a laminate. From the perspective of manufacturing efficiency, it is preferable to perform the latter method.

[0106] (Anhydride component of layers other than the main layer) Layers other than the main layer are suitable for the layer directly laminated on the support, and are suitable as layers including the layers corresponding to the polyimide layers P1 and P3. However, for these layers, it is preferable to be formed as the thermoplastic polyimide layer as described above. That is, in these layers, preferably, an aromatic tetracarboxylic dianhydride represented by the following general formula (3) is used in an amount of 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more, based on the total acid anhydride component. By setting it within such a range, the polyimide layer formed is likely to exhibit flexibility, heat resistance, and low retardation. Also, it is preferable to contain an aromatic diamine compound represented by the general formula (4) in an amount of 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more, based on the total diamine component.

[0107] The aromatic tetracarboxylic anhydride represented by the following general formula (3) imparts flexibility to the polyimide, reduces interactions such as π-π stacking between polymer chains, and makes it difficult to cause charge transfer (CT) between the aromatic tetracarboxylic acid residue and the aromatic diamine residue in the polyimide layer. Therefore, it is considered that the resulting polyimide can be made nearly colorless and transparent. Also, the aromatic diamine compound represented by the general formula (4) has two or more benzene rings, and due to the amino groups directly connected to at least two benzene rings and the divalent linking group Z, the degree of freedom of the polyimide molecular chain increases and it has high flexibility. It is considered to contribute to the improvement of the flexibility of the polyimide molecular chain and promote high toughness.

[0108] The acid anhydride component used for forming the polyimide layer suitable for the polyimide layers P1 and P3 is preferably an aromatic tetracarboxylic dianhydride represented by the following general formula (3).

[0109]

Chemical formula

[0110] In formula (3), X represents a divalent group selected from a single bond, -O-, or -C(CF3)2-.

[0111] Examples of the aromatic tetracarboxylic dianhydride represented by the formula (3) include 4,4'-oxydiphthalic dianhydride (ODPA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), and 2,2-bis(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride (6FDA). These aromatic tetracarboxylic dianhydrides are preferable because they can impart strength and flexibility to the polyimide film, are excellent in heat resistance and transparency, and can control the CTE within an appropriate range. Among them, ODPA and 6FDA are particularly preferable.

[0112] (Diamine component of layers other than the main layer) The diamine component used for forming a polyimide layer suitable for the polyimide layers P1 and P3 is preferably an aromatic diamine compound represented by the following general formula (4).

[0113] [Chemical formula]

[0114] In the formula (4), Z independently represents a divalent group selected from -O-, -S-, -CH2-, -CH(CH3)-, -C(CH3)2-, -CO-, -COO-, -SO2-, -NH- or -NHCO-, preferably -O- or -SO2-. n2 represents an integer of 0 to 4, preferably 0 or 1. R is a substituent and independently represents a halogen atom, or an alkyl group or an alkoxy group which may be substituted with a halogen atom having 1 to 6 carbon atoms, or a phenyl group or a phenoxy group which may be substituted with a monovalent hydrocarbon group or an alkoxy group having 1 to 6 carbon atoms. n1 independently represents an integer of 0 to 3, preferably 0 or 1.

[0115] Examples of the aromatic diamine compound represented by the formula (4) include 3,3'-diaminodiphenylmethane, 3,3'-diaminodiphenylpropane, 3,3'-diaminodiphenylsulfide, 3,3'-diaminodiphenylsulfone, bis[4-(aminophenoxy)phenyl]sulfone (BAPS), 3,3-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylpropane, 3,4'-diaminodiphenylsulfide, 3,4'-diaminobenzophenone, (3,3'-bisamino)diphenylamine, 1,4-bis(3-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene (APB), 1,3-bis(4-aminophenoxy)benzene (TPE-R), 3-[4-(4-aminophenoxy)phenoxy]benzeneamine, 3-[3-(4-aminophenoxy)phenoxy]benzeneamine, 4,4'-[2-methyl-(1,3-phenylene)bisoxy]bisaniline, 4,4'-[4-methyl-(1,3-phenylene)bisoxy]bisaniline, 4,4'-[5-methyl-(1,3-phenylene)bisoxy]bisaniline, bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(3-aminophenoxy)phenyl]propane, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)]benzophenone, bis[4,4'-(3-aminophenoxy)]benz anilide, 4-[3-[4-(4-aminophenoxy)phenoxy]phenoxy]aniline, 4,4’-[oxybis(3,1-phenyleneoxy)]bisaniline, bis[4-(4-aminophenoxy)phenyl]ether (BAPE), bis[4-(4-aminophenoxy)phenyl]ketone (BAPK), bis[4-(3-aminophenoxy)]biphenyl, bis[4-(4-aminophenoxy)]biphenyl, 2,2-bis(4-aminophenoxyphenyl)propane (BAPP), 4,4’-diaminodiphenyl ether, and the like.Among these, 1,3-bis(3-aminophenoxy)benzene (APB), 1,3-bis(4-aminophenoxy)benzene (TPE-R), and bis[4-(aminophenoxy)phenyl]sulfone (BAPS) are preferable.

[0116] However, even in the formation of these polyimide layers, as long as the object of the present embodiment is not inhibited, other known acid anhydrides other than the formula (3) may be used. When using other acid anhydrides, it is 50 mol% or less of the total acid anhydride component, preferably less than 30 mol%, more preferably less than 10 mol%.

[0117] Similarly, other diamine compounds other than the formula (4) may be used. When using other known diamine compounds, it is 50 mol% or less of the total diamine component, preferably less than 30 mol%, more preferably less than 10 mol%.

[0118] (Other Components) The resin layer of the polyamic acid and the polyimide formed therefrom used in the present embodiment may, as long as the object of the present embodiment is not inhibited, be filled with silicon dioxide, aluminum oxide, boron nitride, magnesium oxide, beryllium oxide, aluminum nitride, silicon nitride, aluminum fluoride, calcium fluoride, metal salts of organic phosphinic acids, and other components as necessary. These components can be used alone or in combination of two or more.

Examples

[0119] Hereinafter, the content of the present embodiment will be specifically described based on examples, but the present embodiment is not limited to the scope of these examples. In the following examples, unless otherwise specified, various measurements and evaluations are as follows.

[0120] [Calculation of Hue (L * ) and Yellowness Index (YI)] For the sampling positions 1 to 16 shown as in Fig. 1, for each test piece of MD50mm × TD50mm, L * and YI were measured using a UV-3600 spectrophotometer manufactured by Shimadzu Corporation. 1) L * In accordance with JIS Z 8722, the light transmittance and L * were calculated. 2) YI In accordance with JIS Z 8722, it was calculated based on the calculation formula represented by the following formula (1). YI = 100×(1.2879X - 1.0592Z) / Y ···(1) X, Y and Z: Tristimulus values of the test piece The YI of the resin film with a thickness of 25 μm (T25) was calculated by substituting the value of YI calculated by the above formula (1) into the following formula (2). YI (T25) = YI / T × 25 ···(2) T: Thickness of the resin film (μm)

[0121] [Calculation of total light transmittance (T.T.) and haze (HAZE)] For MD500mm × TD500mm of the long polyimide layer (hereinafter referred to as polyimide film) after removing the support, for each test piece of MD50mm × TD50mm at the sampling positions 1 to 16 shown as in Fig. 1, the total light transmittance (T.T.) and haze (HAZE) were measured in accordance with JIS K 7136 using a HAZE METER NDH500 manufactured by Nippon Denshoku Industries Co., Ltd.

[0122] [Calculation of in-plane variation (range)] For all the test pieces sampled at the sampling positions 1 to 16 described above, L * , YI, T.T. and HAZE were measured, and for each item, the difference between the maximum value and the minimum value of the measured values was calculated, and this was taken as the in-plane variation (range).

[0123] [Calculation of standard deviation] For all the test pieces sampled at the sampling positions 1 to 16 described above, L *For the measurement results of YI, T.T., and HAZE, the standard deviation was calculated for each item using the following formula (3).

Number

[0124] [Calculation of in-plane variation (range, standard deviation) of thickness] For the long polyimide layer (hereinafter also referred to as polyimide film) of MD500 mm × TD500 mm after removing the support, the thickness at the 1 to 52 measurement points shown in Fig. 2 was measured using a thickness gauge (manufactured by Mitutoyo Corporation, trade name: gauge block measurement value display device ND281B attached), and the difference between the maximum value and the minimum value of the measurement values at all measurement points was calculated as the in-plane variation (range). Also, using all the measurement values, the standard deviation was calculated from the above formula (3).

[0125] [Measurement of viscosity] The viscosity was measured at 25 °C for the polyamic acid solution obtained in the synthesis example using a cone plate viscometer (manufactured by Tokimec Inc.) equipped with a constant temperature water bath.

[0126] [Measurement of glass transition temperature (Tg)] The dynamic viscoelasticity of the polyimide layer (5 mm × 22.6 mm) was measured with a dynamic thermomechanical analyzer while heating from 20 °C to 350 °C at a rate of 5 °C / min, and the glass transition temperature (Tanδ maximum value: °C) was determined.

[0127] [Measurement of thermal decomposition temperature (Td1)] (Polyimide film) The weight change of a polyimide film weighing 10 to 20 mg in a nitrogen atmosphere was measured with a thermogravimetric (TG) analyzer TG / DTA6200 manufactured by SEIKO Instruments Inc. while heating at a constant rate from 30 °C to 550 °C. With the weight at 200 °C set to zero, the temperature at which the weight loss rate was 1% was defined as the thermal decomposition temperature (Td1).

[0128] [Measurement of surface roughness of copper foil] The sample was cut into a size of approximately 10 mm square, fixed to the sample stage with double-sided tape, irradiated with soft X-rays to remove the static electricity on the copper foil surface, and then the surface roughness was measured. Using a scanning probe microscope (AFM, manufactured by Bruker AXS, product name: Dimension Icon type SPM), the arithmetic mean roughness Ra and the maximum height Rz of the surfaces of the coated surface (M surface) and the back surface of the coated surface (S surface) of the copper foil were measured under the following measurement conditions. The measurement conditions are as follows. The copper foil used in this application is treated with a surface treatment agent, and the M surface is a more glossy surface compared to the S surface. Measurement mode; Tapping mode Measurement area; 1 μm × 1 μm Scan speed; 1 Hz Probe; AC160 manufactured by Olympus Analysis software; NanoScope Analysis

[0129] [Measurement of surface roughness of polyimide layer and protective film] In the same manner as the measurement of the surface roughness of the above copper foil, the arithmetic mean roughness Ra and the maximum height Rz of the surface (the surface that contacts the support during winding) of the polyimide layer (polyimide film) were measured. Also, the arithmetic mean roughness Ra and the maximum height Rz of the protective film (the surface that contacts the polyimide layer) were measured in the same manner.

[0130] [Measurement of peel strength] (Copper-clad laminate) Using a tension tester, the polyimide layer side of a test sample having a circuit with a width of 1 mm obtained from a laminate of a copper foil as a support and a polyimide layer (hereinafter referred to as "copper-clad laminate") was fixed to an aluminum plate with double-sided tape, and the copper was peeled off at a speed of 50 mm / min in the 180° direction to obtain the peel strength between the copper foil and the polyimide layer.

[0131] [Measurement of peel strength] (Protective film / Copper-clad laminate) Using an Angle Change Tensile Tester (VERSATILE PEEL ANALYZER, KYOWA, VPA-3S), a sample was prepared by laminating a protective film on a laminate of a copper foil as a support and a polyimide layer (hereinafter referred to as "copper-clad laminate"). Cuts were made only on the protective film above the polyimide every 10 mm in width, and the copper foil side was fixed to a glass plate (12.5 cm × 12.5 cm, 0.7 mm thick) with double-sided tape. The protective film was peeled while moving the stage at a moving speed of 3 mm / min so that the protective film was in the 90°C direction, and the peel strength between the protective film and the polyimide layer was determined.

[0132] [MD streaks of the cured laminate] In the cured laminate, the surface state of the polyimide layer was visually observed. Regarding the linear pattern streaks in the MD direction, when more than 3 streaks with a width of 0.1 mm or more and a length of 10 cm or more occurred, it was marked as "×", when 1 to 3 streaks occurred, it was marked as "△", and when none were observed, it was marked as "〇".

[0133] [Measurement of coefficient of thermal expansion (CTE)] A test piece of MD 3 mm × TD 15 mm was heated from 30°C to 280°C at a heating rate of 10°C / min while applying a load of 5.0 g with a thermomechanical analysis (TMA) apparatus, and then cooled from 250°C to 100°C. The coefficient of thermal expansion was measured from the amount of elongation (linear expansion) during cooling.

[0134] [TG-DTA (Td1)] (Protective film) A measurement sample film of the protective film with a weight of 10 - 20 mg was heated from 30°C to 400°C at a rate of 10°C / min with a differential thermal balance analyzer TG / DTA7220 manufactured by EXSTAR in a nitrogen atmosphere, and then cooled from 400°C to 30°C at a rate of 50°C / min. Using the weight of the 200°C sample as a reference (100), the temperature at 1% weight loss was defined as Td1.

[0135] [Tensile strength measurement] Using a tensile device strograph VG1F (manufactured by TOYOSEIKI), a test sample of the protective film (size 10 mm × 110 mm) was subjected to a tensile test at a speed of 10 mm / min with a load of 100 N, and the tensile elongation (elongation at break point) was determined.

[0136] The abbreviations used in the examples, etc. represent the following compounds. APB: 1,3-bis(3-aminophenoxy)benzene TFMB: 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl BAPS: bis[4-(aminophenoxy)phenyl]sulfone ODPA: 4,4'-oxydiphthalic dianhydride PMDA: pyromellitic dianhydride 6FDA: 2,2-bis(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride BAPP: 2,2-bis(4-aminophenoxyphenyl)propane m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl TPE-R: 1,3-bis(4-aminophenoxy)benzene DMAc: N,N-dimethylacetamide

[0137] The following two types of protective films were used. (1) Pack: polyethylene film (manufactured by Sankei Kaken Co., Ltd., trade name; PAC type PAC-3J-30H, thickness; 30 μm, slightly adhesive, adhesive force 0.05 N / 25 mm) (2) Lumirror: polyester film (manufactured by Toray Industries, Inc., trade name; Lumirror 25S28L, thickness; 25 μm, non-adhesive)

[0138] Synthesis Example 1 To synthesize polyamic acid solution A, under a nitrogen stream, into a 200 ml separable flask, DMAc as a solvent was added to achieve a solid content concentration of 15 wt%. The diamine component and acid anhydride component shown in Table 1 were added and dissolved while stirring at room temperature. Then, the solution was continuously stirred at room temperature for 20 hours to conduct a polymerization reaction, and a viscous polyamic acid solution A was prepared. Subsequently, it was diluted to 12 wt% with the solvent DMAc. The viscosity after dilution was 3000 cP.

[0139] Synthesis Example 2 To synthesize polyamic acid solution B, under a nitrogen stream, into a 200 ml separable flask, DMAc as a solvent was added to achieve the solid content concentration shown in Table 1. The diamine component and acid anhydride component shown in Table 1 were heated and dissolved with stirring at 40 °C for 1 hour. Then, the solution was continuously stirred at room temperature for 2 days to conduct a polymerization reaction, and a viscous polyamic acid solution B was prepared. The viscosity was 25000 cP.

[0140] Synthesis Example 3 For polyamic acid solution C, the monomer types were changed as shown in Table 1, and polymerization was carried out in the same manner as in Synthesis Example 2. A viscous polyamic acid solution C was prepared. The viscosity was 26000 cP.

[0141] Synthesis Example 4 To synthesize polyamic acid solution D, under a nitrogen stream, into a 200 ml separable flask, DMAc as a solvent was added to achieve the solid content concentration shown in Table 1. The diamine component and acid anhydride component shown in Table 1 were dissolved with stirring. Then, the solution was continuously stirred at room temperature for 1 day to conduct a polymerization reaction, and a viscous polyamic acid solution D was prepared. The viscosity was 23000 cP.

[0142] Synthesis Example 5 For polyamic acid solution E, the monomer types were changed as shown in Table 1, and polymerization was carried out in the same manner as in Synthesis Example 4. A viscous polyamic acid solution E was prepared. The viscosity was 23000 cP.

[0143] Synthesis Example 6 The polyamic acid solution F was polymerized in the same manner as in Synthesis Example 1 with the monomer types changed as shown in Table 1. A viscous solution F of polyamic acid was prepared. The viscosity was 2300 cP.

[0144]

Table 1

[0145] The used support (copper foil) and the protective film are as described in Tables 2 and 3 below.

[0146]

Table 2

[0147]

Table 3

[0148] Example 1 On copper foil I, polyamic acid solution A was uniformly coated so that the cured thickness would be 2.0 μm, and then heated and dried stepwise in the temperature range up to 120 °C to remove the solvent to form the first layer. Next, on the first layer, polyamic acid solution B was uniformly coated so that the cured thickness would be 21.0 μm, and then heated and dried stepwise in the temperature range up to 70 °C to remove the solvent to form the second layer. The laminate in which the resin layers A and B of polyamic acid from which the solvent had been removed by heat drying were laminated was wound around the plastic core of the winding core, and when winding, protective film 1 (pack) was co-wound around the winding core while being attached to the resin layer B surface (roll body 1 of the laminate with protective film).

[0149] Subsequently, in order to perform heat drying, while unwinding the roll body 1 of the laminate with the protective film obtained above, the protective film was peeled off. At the same time, in the laminate after the protective film was peeled off and during unwinding, on the resin layer B of the second layer of polyamic acid, the polyamic acid solution A was uniformly applied so that the thickness after curing would be 2.0 μm. Then, it was heated and dried stepwise in the temperature range up to 120 °C to remove the solvent, and the third layer was formed. When winding up the laminate in which the resin layers A / B / A of polyamic acid were laminated after the solvent was removed, in the same manner as above, the protective film 1 (pack) was co-wound while being attached to the surface of the resin layer A of the third layer, and it was wound up on the said core (roll body 2 of the laminate with the protective film). In this way, three resin layers A, B, and A of polyamic acid corresponding to the polyamic acid solutions A, B, and A were formed in order from the copper foil I side. Further thereafter, before heat curing, while unwinding and peeling off the protective film from the roll body 2 of the laminate with the protective film, in the state of the laminate from which the protective film was removed, this was subjected to stepwise heat treatment from 125 °C to 360 °C to complete imidization, and a polyimide layer with a total thickness of 24.9 μm composed of polyimide layer A / polyimide layer B / polyimide layer A in order was formed on the copper foil I, and the single-sided copper-clad laminate 1A was prepared.

[0150] Regarding the obtained single-sided metal-clad laminate 1A, the MD streak after curing was evaluated, and also the peel strength (1 mm 180-degree peel strength) of the polyimide layer coating surface processed to a wiring width of 1 mm was measured. Also, using an aqueous ferric chloride solution, the copper foil I was etched and removed from the obtained single-sided copper-clad laminate 1A to prepare a polyimide film 1a. Regarding the polyimide film 1a, HAZE, T.T., YI, Ra, Rz, L * , thickness, Tg, CTE, and Td1 were determined. These measurement results are shown in Tables 4, 7 to 13. Regarding the HAZE, T.T., YI, and L * of the polyimide film 1a, test pieces at the upper and lower sampling positions 1 to 16 as shown in Fig. 1 were measured, and the details thereof are shown in Tables 7 to 11. Also, regarding the thickness, it was measured at the upper and lower measurement points 1 to 52 as shown in Fig. 2, and the details thereof are shown in Tables 12 and 13. The average values of the measurement results are shown in Table 4. Also, the in-plane variations (range, standard deviation) obtained from these measurement results are shown in Table 6.

[0151] Example 2 A single-sided copper-clad laminate 2A was prepared in the same procedure as in Example 1, except that the protective film was changed to a protective film 2 (Lumirror). Further, a polyimide film 2a was prepared from the obtained single-sided copper-clad laminate 2A, and each measurement item was measured in the same manner as in Example 1. These measurement results are shown in Table 4. Regarding Example 2, the details of the measurement results at sampling positions 1 to 16 such as HAZE and the measurement results at measurement locations 1 to 52 of the thickness were omitted.

[0152] Example 3 A single-sided copper-clad laminate 3A was prepared in the same procedure as in Example 1, including the procedure of winding it as the roll body 2, except that no protective film was used in the resin layer of the third-layer polyamic acid. Further, a polyimide film 3a was prepared from the obtained single-sided copper-clad laminate 3A, each measurement item was measured in the same manner as in Example 1, and the in-plane variation was calculated. These measurement results and calculation results are shown in Tables 4, 6 to 13.

[0153] Example 4 A single-sided copper-clad laminate 4A was prepared in the same procedure as in Example 1, including the procedures of winding it as the roll body 1 and the roll body 2, except that no protective film was used and no protective film was used in the resin layers of the second and third layers and they were imidized. Further, a polyimide film 4a was prepared from the obtained single-sided copper-clad laminate 4A, each measurement item was measured in the same manner as in Example 1, and the in-plane variation was calculated. These measurement results and calculation results are shown in Tables 4, 6 to 13.

[0154] Example 5 A single-sided copper-clad laminate 5A was prepared in the same procedure as in Example 1, except that the support was copper foil II and the polyamic acid for forming the second layer was polyamic acid solution C. Further, a polyimide film 5a was prepared from the obtained single-sided copper-clad laminate 5A, and each measurement item was measured in the same manner as in Example 1. The measurement results are shown in Table 4. Regarding Example 5, the details of the measurement results at sampling positions 1 to 16 such as HAZE and the measurement results at measurement locations 1 to 52 of the thickness were omitted.

[0155] Comparative Example 1 A single-sided copper-clad laminate 6A was prepared in the same procedure as in Example 1, including performing each procedure for winding as roll body 1 and roll body 2, except that the support was copper foil III, the polyamic acid solution for forming the first to third layers was changed as shown in Table 5, and no protective film was used. Further, a polyimide film 6a was prepared from the obtained single-sided copper-clad laminate 6A, and some of the measurement items in Example 1 were measured. These measurement results and calculation results are shown in Tables 5, 6 to 13.

[0156] Comparative Example 2 A single-sided copper-clad laminate 7A was prepared in the same procedure as in Example 1, including performing each procedure for winding as roll body 1 and roll body 2, except that the support was copper foil IV, the polyamic acid solution for forming the first to third layers was changed as shown in Table 5, and no protective film was used. Further, a polyimide film 7a was prepared from the obtained single-sided copper-clad laminate 7A, and some of the measurement items in Example 1 were measured. These measurement results and calculation results are shown in Tables 5, 6 to 13.

[0157]

Table 4

[0158]

Table 5

[0159]

Table 6

[0160]

Table 7

[0161]

Table 8

[0162]

Table 9

[0163]

Table 10

[0164]

Table 11

[0165]

Table 12

[0166]

Table 13

Claims

1. A long laminated plate comprising a support and a polyimide layer laminated on the support, wherein the length in the width direction orthogonal to the longitudinal direction of the laminated plate is 500 mm or more and 1200 mm or less, at least eight test pieces taken in a size of 50 mm in length × 50 mm in width at symmetric positions with respect to the center line connecting the midpoints of the total length in the width direction of the polyimide layer, and at least eight test pieces taken in a size of 50 mm in length × 50 mm in width at positions 200 mm apart in the longitudinal direction from the respective sampling positions of the at least eight test pieces, the standard deviation of HAZE in the evaluation of variation using the at least 16 test pieces is within the range of 0.25% or less. The laminated plate is characterized by this.

2. The laminated plate according to claim 1, wherein the polyimide layer has a HAZE of 50% or less.

3. The laminated plate according to claim 1 or 2, wherein the total light transmittance of the polyimide layer is 70% or more.

4. The laminated plate according to claim 1 or 2, wherein the standard deviation of the in-plane total light transmittance in the variation evaluation of the polyimide layer is 0.25% or less.

5. At least 26 measurement points at symmetric positions with respect to the center line connecting the midpoints of the total length in the width direction of the polyimide layer, and at least 26 measurement points located 200 mm apart in the longitudinal direction from the at least 26 measurement points. For these, the standard deviation of the thickness of the polyimide layer at the at least 52 measurement points in total is 0.35 μm or less. The laminated plate according to claim 1 or 2 is characterized by this.

6. The laminated plate according to claim 1 or 2, wherein the surface roughness Ra of the polyimide layer is 10 nm or less.

7. The laminated plate according to claim 1 or 2, wherein the polyimide layer has 3 or less streaks with a width of 0.1 mm or more and a length of 10 cm or more.

8. A laminated plate obtained by cutting the laminated plate according to claim 1 or 2 along the longitudinal direction, having a length in the width direction orthogonal to the longitudinal direction of 250 mm or more.

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