CN112346273A - Flexible liquid crystal display device - Google Patents
Flexible liquid crystal display device Download PDFInfo
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- CN112346273A CN112346273A CN202010786822.2A CN202010786822A CN112346273A CN 112346273 A CN112346273 A CN 112346273A CN 202010786822 A CN202010786822 A CN 202010786822A CN 112346273 A CN112346273 A CN 112346273A
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1337—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
- G02F1/133711—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers by organic films, e.g. polymeric films
- G02F1/133723—Polyimide, polyamide-imide
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/133509—Filters, e.g. light shielding masks
- G02F1/133514—Colour filters
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Abstract
本发明的课题是实现一种柔性液晶显示装置，其具有形成了聚酰亚胺的基板，其实现工艺成本的降低而不使用激光剥离，且提高液晶显示装置的机械强度，具有弯曲耐受性。提供一种柔性液晶显示装置(1)，其为包含薄膜晶体管(TFT)布线层(300)、液晶层(500)、滤色器层(800)、透明聚酰亚胺层(200、900)和玻璃基板(100、1000)的柔性液晶显示装置(1)，具有按照TFT布线层(300)或滤色器层(800)、以及透明聚酰亚胺层(200、900)和玻璃基板(100、1000)的顺序层叠而成的层叠结构，且玻璃基板(100、1000)的厚度为10～70μm。
The subject of the present invention is to realize a flexible liquid crystal display device having a substrate formed with polyimide, which realizes a reduction in process cost without using laser lift-off, improves the mechanical strength of the liquid crystal display device, and has bending resistance . A flexible liquid crystal display device (1) is provided, which comprises a thin film transistor (TFT) wiring layer (300), a liquid crystal layer (500), a color filter layer (800), and a transparent polyimide layer (200, 900) A flexible liquid crystal display device (1) with a glass substrate (100, 1000), having a TFT wiring layer (300) or a color filter layer (800), and a transparent polyimide layer (200, 900) and a glass substrate ( 100, 1000) in the order of lamination, and the thickness of the glass substrate (100, 1000) is 10 to 70 μm.
Description
Technical Field
The present invention relates to a display device, and more particularly, to a flexible liquid crystal display device.
Background
The conventional display device is not flexible, and is a rigid type display device. In recent years, display devices having flexibility have been developed, and as flexible display devices, there are devices using organic light emitting elements (OLEDs) and devices using liquid crystal elements (LCDs).
In order to exhibit flexibility, a substrate using resin instead of glass has been proposed as a substrate of a display device. Here, in order to form a substrate using only resin, the following operations are studied: a polyimide layer is formed on a glass substrate, and then, after a display forming process, the polyimide layer is peeled from the glass substrate by irradiating laser light from the glass substrate side (patent document 1). However, since the polyimide layer has insufficient mechanical strength, there are problems that the display device is damaged when peeling off the polyimide layer and that the display device is damaged when the display device is repeatedly wound up and unwound.
On the other hand, a rigid type display device is thinned by etching a glass substrate, but the display device is not flexible as described above (patent document 2).
Documents of the prior art
Patent document
Patent document 1: japanese Kokai publication No. 2007-512568
Patent document 2: japanese patent laid-open publication No. 2018-16518
Disclosure of Invention
Problems to be solved by the invention
When the laser lift-off as described in patent document 1 is used, a very expensive process cost is required. In addition, in general, the manufacturing process of the organic light emitting display device is expensive as compared with the manufacturing process of the liquid crystal display device. Therefore, it is required to utilize the conventional manufacturing process of the liquid crystal display device and to suppress the cost.
In view of the above-described requirements, an object of the present invention is to realize a liquid crystal display device having a substrate on which polyimide is formed, which has improved mechanical strength and bending resistance while reducing process costs without using laser lift-off.
Means for solving the problems
The inventors of the present invention found that: the above problems can be solved by maintaining and thinning a glass substrate used for a TFT wiring layer or a color filter layer in a flexible liquid crystal display device, and the present invention has been completed. The following illustrates an aspect of the present invention.
[1] A flexible liquid crystal display device is a flexible liquid crystal display device including a Thin Film Transistor (TFT) wiring layer, a liquid crystal layer, a color filter layer, a transparent polyimide layer, and a glass substrate,
the flexible liquid crystal display device has a laminated structure in which the TFT wiring layer, the transparent polyimide layer and the glass substrate are laminated in this order, and
the thickness of the glass substrate is 10 to 70 μm.
[2] The flexible liquid crystal display device according to item 1, wherein the glass substrate has a thickness of 10 to 50 μm.
[3] The flexible liquid crystal display device according to item 1 or 2, wherein the glass substrate has a thickness of 10 to 24 μm.
[4] A flexible liquid crystal display device is a flexible liquid crystal display device including a Thin Film Transistor (TFT) wiring layer, a liquid crystal layer, a color filter layer, a transparent polyimide layer, and a glass substrate,
the flexible liquid crystal display device has a laminated structure in which the TFT wiring layer, the transparent polyimide layer and the glass substrate are laminated in this order, and
the thickness of the glass substrate after chemical etching is 10 to 70 μm.
[5] The flexible liquid crystal display device according to any one of items 1 to 4, wherein the transparent polyimide layer and the glass substrate are supports for the TFT wiring layer.
[6] A flexible liquid crystal display device is a flexible liquid crystal display device including a Thin Film Transistor (TFT) wiring layer, a liquid crystal layer, a color filter layer, a transparent polyimide layer, and a glass substrate,
the flexible liquid crystal display device has a laminated structure in which the color filter layer, the transparent polyimide layer, and the glass substrate are laminated in this order, and
the thickness of the glass substrate is 10 to 70 μm.
[7] The flexible liquid crystal display device according to item 6, wherein the glass substrate has a thickness of 10 to 50 μm.
[8] The flexible liquid crystal display device according to item 6 or 7, wherein the glass substrate has a thickness of 10 to 24 μm.
[9] A flexible liquid crystal display device is a flexible liquid crystal display device including a Thin Film Transistor (TFT) wiring layer, a liquid crystal layer, a color filter layer, a transparent polyimide layer, and a glass substrate,
the flexible liquid crystal display device has a laminated structure in which the color filter layer, the transparent polyimide layer, and the glass substrate are laminated in this order, and
the thickness of the glass substrate after chemical etching is 10 to 70 μm.
[10] A flexible liquid crystal display device is a flexible liquid crystal display device including a Thin Film Transistor (TFT) wiring layer, a liquid crystal layer, a color filter layer, a transparent polyimide layer, and a glass substrate,
the flexible liquid crystal display device has a laminated structure I in which the TFT wiring layer, the transparent polyimide layer and the glass substrate are laminated in this order
The flexible liquid crystal display device has a laminated structure II in which the color filter layer, the transparent polyimide layer and the glass substrate are laminated in this order
The thickness of the glass substrate is 10 to 70 μm.
[11] The flexible liquid crystal display device of item 10, wherein the glass substrate has a thickness of 10 to 50 μm.
[12] The flexible liquid crystal display device according to item 10 or 11, wherein the glass substrate has a thickness of 10 to 24 μm.
[13] A flexible liquid crystal display device is a flexible liquid crystal display device including a Thin Film Transistor (TFT) wiring layer, a liquid crystal layer, a color filter layer, a transparent polyimide layer, and a glass substrate,
the flexible liquid crystal display device has a laminated structure I in which the TFT wiring layer, the transparent polyimide layer and the glass substrate are laminated in this order
The flexible liquid crystal display device has a laminated structure II in which the color filter layer, the transparent polyimide layer and the glass substrate are laminated in this order
The thickness of the glass substrate after chemical etching is 10 to 70 μm.
[14] The flexible liquid crystal display device according to any one of items 6 to 13, wherein the transparent polyimide layer and the glass substrate are supports for the color filter layer.
[15] The flexible liquid crystal display device according to any one of items 1 to 14, wherein the polyimide contained in the transparent polyimide layer has a structural unit derived from a diamine selected from the group consisting of diaminodiphenyl sulfone, 4 '-diaminodiphenyl sulfide, 3' -diaminodiphenyl sulfide, 4 '-diaminobiphenyl, 3' -diaminobiphenyl, 4 '-diaminobenzophenone, 3' -diaminobenzophenone, 4 '-diaminodiphenylmethane, 3' -diaminodiphenylmethane, 1, 4-bis (4-aminophenoxy) benzene, and mixtures thereof, 1, 3-bis (4-aminophenoxy) benzene, 1, 3-bis (3-aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl ] sulfone, 4-bis (4-aminophenoxy) biphenyl, 4-bis (3-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) phenyl ] ether, bis [4- (3-aminophenoxy) phenyl ] ether, 1, 4-bis (4-aminophenyl) benzene, 1, 3-bis (4-aminophenyl) benzene, 9, 10-bis (4-aminophenyl) anthracene, 2-bis (4-aminophenyl) propane, 2-bis (4-aminophenyl) hexafluoropropane, 2-bis [4- (4-aminophenoxy) phenyl ] propane, 2, 2-bis [4- (4-aminophenoxy) phenyl ] hexafluoropropane, 1, 4-bis (3-aminopropyldimethylsilyl) benzene and 9, 9-bis (4-aminophenyl) fluorene (BAFL).
[16] The flexible liquid crystal display device according to any one of items 1 to 15, wherein the polyimide contained in the transparent polyimide layer has a structural unit derived from an acid anhydride selected from the group consisting of 3,3 ', 4,4 ' -biphenyltetracarboxylic dianhydride (BPDA), 4,4 ' -Oxydiphthalic Dianhydride (ODPA), norbornane-2-spiro-2 ' -cyclopentanone-5 ' -spiro-2 ' -norbornane-5, 5 ', 6,6 ' -tetracarboxylic dianhydride (CpODA), 2 ', 3,3 ' -biphenyltetracarboxylic dianhydride, 4,4 ' - (hexafluoroisopropylidene) diphthalic anhydride (6FDA), 5- (2, 5-dioxotetrahydro-3-furanyl) -3-methyl-cyclohexene-1, 2-dicarboxylic anhydride, 1,2,3, 4-benzenetetracarboxylic dianhydride, 3 ', 4,4 ' -diphenylsulfonetetracarboxylic dianhydride, methylene-4, 4 ' -diphthalic dianhydride, 1-ethylene-4, 4 ' -diphthalic dianhydride, 2-propylene-4, 4 ' -diphthalic dianhydride, 1, 2-ethylene-4, 4 ' -diphthalic dianhydride, 1, 3-trimethylene-4, 4 ' -diphthalic dianhydride, 1, 4-tetramethylene-4, 4 ' -diphthalic dianhydride, 1, 5-pentamethylene-4, 4 ' -diphthalic dianhydride, 4,4 ' -oxydiphthalic dianhydride, 1, 2-diphenyl sulfone tetracarboxylic dianhydride, and 1,2, 4 ' -diphenyl sulfone tetracarboxylic dianhydride, P-phenylene bis (trimellitic anhydride), thio-4, 4 '-diphthalic dianhydride, sulfonyl-4, 4' -diphthalic dianhydride, 1, 3-bis (3, 4-dicarboxyphenyl) benzene dianhydride, 1, 3-bis (3, 4-dicarboxyphenoxy) benzene dianhydride, 1, 4-bis (3, 4-dicarboxyphenoxy) benzene dianhydride, 1, 3-bis [2- (3, 4-dicarboxyphenyl) -2-propyl ] benzene dianhydride, 1, 4-bis [2- (3, 4-dicarboxyphenyl) -2-propyl ] benzene dianhydride, bis [3- (3, 4-dicarboxyphenoxy) phenyl ] methane dianhydride, bis [4- (3, 4-dicarboxyphenoxy) phenyl ] methane dianhydride, 2, 2-bis [3- (3, 4-dicarboxyphenoxy) phenyl ] propane dianhydride, bis (3, 4-dicarboxyphenoxy) dimethylsilane dianhydride, 1, 3-bis (3, 4-dicarboxyphenyl) -1,1,3, 3-tetramethyldisiloxane dianhydride, 3,4,9, 10-perylenetetracarboxylic dianhydride, 2,3,6, 7-anthracenetetracarboxylic dianhydride, 1,2,7, 8-phenanthrenetetracarboxylic dianhydride and dicyclohexyl-3, 3', 9, 9-bis (3, 4-dicarboxyphenyl) fluorene dianhydride (BPAF).
[17] The flexible liquid crystal display device according to any one of items 1 to 16, wherein the liquid crystal layer is provided between the TFT wiring layer and the color filter layer.
[18] A method for manufacturing a flexible liquid crystal display device including a Thin Film Transistor (TFT) wiring layer, a liquid crystal layer, a color filter layer, a transparent polyimide layer, and a glass substrate, comprising the steps of:
a laminating step of forming a laminated structure in which the TFT wiring layer, the transparent polyimide layer, and the glass substrate are laminated in this order; and
and an etching step of etching the glass substrate so that the thickness of the glass substrate is within a range of 10 to 70 μm in the laminated structure.
[19] The method of manufacturing a flexible liquid crystal display device as defined in item 18, wherein in the etching step, the thickness of the glass substrate is adjusted to be within a range of 10 to 50 μm.
[20] The method of manufacturing a flexible liquid crystal display device according to item 18 or 19, wherein in the etching step, the TFT wiring layer and the transparent polyimide layer are masked.
[21] A method for manufacturing a flexible liquid crystal display device including a Thin Film Transistor (TFT) wiring layer, a liquid crystal layer, a color filter layer, a transparent polyimide layer, and a glass substrate, comprising the steps of:
a laminating step of forming a laminated structure in which the color filter layer, the transparent polyimide layer, and the glass substrate are laminated in this order; and
and an etching step of etching the glass substrate so that the thickness of the glass substrate is within a range of 10 to 70 μm in the laminated structure.
[22] The method of manufacturing a flexible liquid crystal display device as defined in item 21, wherein in the etching step, the thickness of the glass substrate is adjusted to be within a range of 10 to 50 μm.
[23] The method of manufacturing a flexible liquid crystal display device as described in item 21 or 22, wherein in the etching step, the color filter layer and the transparent polyimide layer are masked.
[24] A method for manufacturing a flexible liquid crystal display device including a Thin Film Transistor (TFT) wiring layer, a liquid crystal layer, a color filter layer, a transparent polyimide layer, and a glass substrate, comprising the steps of:
a laminating step of forming a laminated structure I in which the TFT wiring layer, the transparent polyimide layer, and the glass substrate are laminated in this order;
a laminating step of forming a laminated structure II in which the color filter layer, the transparent polyimide layer, and the glass substrate are laminated in this order;
a step of bonding the TFT wiring layer and the color filter layer via a sealing material; and
and an etching step of etching the glass substrate so that the thickness of the glass substrate is in the range of 10 to 70 μm in the laminated structures I and II.
[25] The method of manufacturing a flexible liquid crystal display device as defined in item 24, wherein in the etching step, the thickness of the glass substrate is adjusted to be within a range of 10 to 50 μm.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, a flexible liquid crystal display device having improved mechanical strength and bending resistance can be provided, which can reduce the process cost without using laser lift-off.
Drawings
Fig. 1 is a schematic cross-sectional view of a flexible liquid crystal display device according to an embodiment of the present invention.
FIG. 2 is a schematic sectional view before an etching process for a laminated structure of a TFT wiring layer, a transparent polyimide layer and a glass substrate (thickness: more than 300 μm) in this order.
FIG. 3 is a schematic cross-sectional view after an etching step for sequentially forming a laminated structure of a TFT wiring layer, a transparent polyimide layer and a glass substrate (thickness: 10 to 70 μm).
FIG. 4 is a schematic cross-sectional view before an etching process for a laminated structure of a color filter layer, a transparent polyimide layer and a glass substrate (thickness: more than 300 μm) in this order.
FIG. 5 is a schematic cross-sectional view after an etching step for sequentially forming a laminated structure of a color filter layer, a transparent polyimide layer and a glass substrate (thickness: 10 to 70 μm).
Fig. 6 is a schematic flow chart of a method for manufacturing a flexible liquid crystal display device according to a third embodiment.
Description of the reference numerals
1 Flexible liquid Crystal display device
100 glass substrate (TFT wiring layer substrate)
200 transparent polyimide layer (TFT wiring layer substrate)
300 TFT wiring layer
400 oriented film
500 liquid crystal layer
600 sealing material
700 alignment film
800 color filter layer
900 transparent polyimide layer (color filter layer substrate)
1000 glass substrate (color filter layer substrate)
Detailed Description
The following describes details of the embodiments of the present invention.
The flexible liquid crystal display device comprises a Thin Film Transistor (TFT) wiring layer, a liquid crystal layer, a color filter layer, a transparent polyimide layer and a glass substrate with the thickness of 10-70 mu m, and has the following laminated structure I and/or laminated structure II:
I. a laminated structure in which a TFT wiring layer, a transparent polyimide layer, and a glass substrate are laminated in this order;
a laminated structure in which a color filter layer, a transparent polyimide layer, and a glass substrate are laminated in this order.
The flexible liquid crystal display device can reduce the process cost and has bending tolerance.
The present invention surprisingly found that the process cost of flexible liquid crystal display devices is significantly lower compared to organic light emitting display devices (OLEDs), and deliberately maintaining a thin glass substrate can help to reduce the process cost while compromising bend resistance. From this viewpoint, the thickness of the glass substrate is 10 to 70 μm, preferably 10 to 50 μm, more preferably 10 to 24 μm, and still more preferably 10 to 20 μm. From the same viewpoint, the transparent polyimide layer and the glass substrate preferably constitute a TFT wiring layer substrate as a support for the TFT wiring layer and/or a color filter layer substrate as a support for the color filter layer.
Here, the meaning of "flexible" of the flexible liquid crystal display device means: the liquid crystal display device can be bent to a curvature radius of 150mm or less without damaging the liquid crystal display device, and is preferably bent to a curvature radius of 3mm and has flexibility, and therefore, the liquid crystal display device is not easily broken even if dropped. This is a feature that conventional rigid liquid crystal display devices using only glass as a substrate do not have.
In the present invention, the transparent polyimide layer and the glass substrate in the glass substrate laminate may be etched to be thin in the process of manufacturing the display. Therefore, in the process before etching, the display is manufactured using a thick glass substrate, so that the display can be manufactured stably and the yield can be improved.
In one embodiment, the thickness of the glass substrate included in the laminated structure I and/or the laminated structure II after chemical etching is 10 to 70 μm, preferably 10 to 50 μm, more preferably 10 to 24 μm, and still more preferably 10 to 20 μm, from the viewpoint of reducing the process cost and achieving the bending resistance. The chemically etched glass substrate preferably has a surface roughness (Z) of 0.1 to 1.0nm (measured by AFM), an alkali elution amount of more than 0 and 1.0mg or less (according to JIS R3502), preferably contains no fine scratches (foreign matter having a size of μm unit), and/or preferably contains no silica particles having an average particle diameter of 80nm or less.
The flexible liquid crystal display device may include additional constituent elements such as an alignment film, a sealing material, a polarizing film, a planar electrode, and the like, and may have a laminated structure other than the laminated structures I and II by definition or by addition, as desired.
Fig. 1 is a schematic cross-sectional view of a flexible liquid crystal display device according to an embodiment of the present invention. In a flexible liquid crystal display device (1), a side portion of a liquid crystal layer (500) is sealed with a sealing material (600), thereby constituting a liquid crystal display unit. A laminated structure I in which a TFT wiring layer (300), a transparent polyimide layer (200) and a glass substrate (100) are laminated in this order is provided on one surface of a liquid crystal display cell so that the TFT wiring layer (300) is in contact with a sealing material (600). On the other surface of the liquid crystal display unit, a laminated structure II in which a color filter layer (800), a transparent polyimide layer (900), and a glass substrate (1000) are laminated in this order is provided so that the color filter layer (800) is in contact with the sealing material (600). Alignment films (400, 700) may be disposed in contact with each other on upper and lower portions of the liquid crystal layer (500).
A liquid crystal layer (500) is provided between the TFT wiring layer (300) and the color filter layer (800). A glass substrate (100) and a transparent polyimide layer (200) are used as a TFT wiring layer substrate, with the transparent polyimide layer (200) between the glass substrate (100) and the TFT wiring layer (300). A glass substrate (1000) and a transparent polyimide layer (900) are used as a color filter layer substrate, with the transparent polyimide layer (900) between the glass substrate (1000) and the color filter layer (800). The following describes each constituent element of the flexible liquid crystal display device.
< liquid Crystal display Unit >
Liquid crystal is sealed in the liquid crystal display cell. The liquid crystal layer is made of liquid crystal, and the peripheral portion thereof is sealed with a sealing material. Upper and lower portions of the liquid crystal layer may be covered with alignment films, as desired. The liquid crystal display unit is preferably sealed so that foreign matter such as gas or liquid does not enter the liquid crystal display unit. The sealing material and the alignment film may be formed of, for example, a known ultraviolet-curable resin, a known thermosetting resin, or the like, and the material thereof may be determined depending on the sealing property, the bonding with the TFT wiring layer or the color filter layer, or the like.
< glass substrate >
In one embodiment, at least one pair of glass substrates is disposed so as to sandwich a liquid crystal display unit. The pair of glass substrates may have the same size from the viewpoint of the manufacturing process and cost of the flexible liquid crystal display device. The glass substrate material may be, for example, an alkali-free glass substrate or the like. The glass substrate may be subjected to various treatments such as hydrophobization, hydrophilization, smoothing, roughening, chemical etching, and the like, as desired.
Examples of the means for controlling the thickness of the glass substrate to be within the range of 10 to 70 μm include (i) preparing and using a glass substrate having a thickness of 10 to 70 μm in advance; (ii) a glass substrate having a thickness of more than 70 μm (for example, a thickness of more than 300 μm) is prepared in advance, and is adjusted to a range of 10 to 70 μm by chemical etching in the manufacturing process. Among them, the above (ii) is preferable from the viewpoint of the strength of the glass substrate, the bending resistance of the flexible liquid crystal display device, and the like.
< TFT Wiring layer >
A TFT (thin-film transistor) is a display element using a thin-film transistor as a switching element, and is widely used for a liquid crystal display or a thin television set. The TFT is formed on a substrate, and in the case of a conventional rigid display, a glass substrate is used as the substrate. In recent years, as a display capable of being bent has been studied, use of heat-resistant polyimide has also been studied.
Conventionally, when a transparent polyimide is used as a TFT substrate, it has been studied to form a transparent polyimide layer on a glass substrate, further form a TFT wiring layer, and then perform laser lift-off to peel off the polyimide from the glass substrate. However, since the laser lift-off process is very expensive, the mechanical strength of the TFT wiring layer and polyimide after the lift-off is insufficient, and thus, there have been reported problems such as occurrence of breakage, poor yield in the manufacturing process, and the like.
As a countermeasure against these problems, in the present invention, a transparent polyimide layer and a glass substrate having a thickness of 10 to 70 μm are used as a substrate of a TFT wiring layer, and both cost reduction of the process, improvement of the yield, and good mechanical characteristics are achieved. Here, the thickness of the glass substrate as the substrate of the TFT wiring layer is 10 to 70 μm, preferably 10 to 50 μm, and more preferably 20 to 50 μm.
< color Filter layer >
The color filter is a filter for generating colors of images or videos, and has a pattern formed of color resists of three colors, red (R), green (G), and blue (B), on a substrate thereof, and boundaries are separated into a lattice shape by a Black Matrix (BM) in order to prevent color mixing of the color resists adjacent to each other. In the case of a conventional rigid display, a glass substrate is used as the substrate of the color filter. In recent years, a display which can be bent has been studied, and use of polyimide having heat resistance has also been studied.
When polyimide is used as a substrate for a color filter, it has been studied to form polyimide on a glass substrate, form a color filter, and then peel the polyimide from the glass substrate by laser lift-off. However, since the laser lift-off process is very expensive and the mechanical strength of the color filter layer after lift-off is insufficient, there have been reported problems such as occurrence of breakage and poor yield in the manufacturing process.
As a countermeasure against these problems, the present invention uses a transparent polyimide layer and a glass substrate having a thickness of 10 to 70 μm as substrates of a color filter layer, and achieves both cost reduction of the process, improvement of the yield, and good mechanical properties. Here, the substrate of the color filter layer is a glass substrate having a thickness of 10 to 70 μm, preferably 10 to 50 μm, and more preferably 20 to 50 μm.
< transparent polyimide layer >
The transparent polyimide layer is a layer containing polyimide and is transparent to visible light. From the viewpoint of use in a flexible liquid crystal display device, the transparent polyimide layer may be colorless and transparent. Specifically, the transparent polyimide layer according to the present embodiment can have a light transmittance of 70% or more (converted to a thickness of 10 μm) in the visible light region of 400nm to 750nm, which is not achieved by conventional brown polyimide (e.g., Kapton). The polyimide contained in the transparent polyimide layer is a resin obtained by heating a polyimide precursor obtained by reacting a diamine compound with an acid dianhydride compound, and has high heat resistance as required in the process of a liquid crystal display device.
Examples of the diamine compound include diaminodiphenyl sulfone (e.g., 4 ' -diaminodiphenyl sulfone, 3 ' -diaminodiphenyl sulfone), p-phenylenediamine, m-phenylenediamine, 4 ' -diaminodiphenyl sulfide, 3 ' -diaminodiphenyl sulfide, 4 ' -diaminobiphenyl, 3 ' -diaminobiphenyl, 4 ' -diaminobenzophenone, 3 ' -diaminobenzophenone, 4 ' -diaminodiphenylmethane, 3 ' -diaminodiphenylmethane, 1, 4-bis (4-aminophenoxy) benzene, 3 ' -diaminodiphenyl sulfone, etc.), p-phenylenediamine, m, 1, 3-bis (4-aminophenoxy) benzene, 1, 3-bis (3-aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl ] sulfone, 4-bis (4-aminophenoxy) biphenyl, 4-bis (3-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) phenyl ] ether, bis [4- (3-aminophenoxy) phenyl ] ether, 1, 4-bis (4-aminophenyl) benzene, 1, 3-bis (4-aminophenyl) benzene, 9, 10-bis (4-aminophenyl) anthracene, 2-bis (4-aminophenyl) propane, 2-bis (4-aminophenyl) hexafluoropropane, 2-bis [4- (4-aminophenoxy) phenyl) propane, 2, 2-bis [4- (4-aminophenoxy) phenyl) hexafluoropropane, 1, 4-bis (3-aminopropyldimethylsilyl) benzene, 9-bis (4-aminophenyl) fluorene (BAFL) and the like.
Among the above diamine compounds, diaminodiphenyl sulfone, 4 '-diaminodiphenyl sulfide, 3' -diaminodiphenyl sulfide, 4 '-diaminobiphenyl, 3' -diaminobiphenyl, 4 '-diaminobenzophenone, 3' -diaminobenzophenone, 4 '-diaminodiphenylmethane, 3' -diaminodiphenylmethane, 1, 4-bis (4-aminophenoxy) benzene, 1, 3-bis (3-aminophenoxy) benzene, 3-bis (4-aminophenoxy) benzene, 3-bis (3-aminobenzophenone, 3-diaminodiphenyl sulfide, 3,4 '-diaminodiphenyl sulfide, 3, 4' -diamino, Bis [4- (4-aminophenoxy) phenyl ] sulfone, 4-bis (4-aminophenoxy) biphenyl, 4-bis (3-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) phenyl ] ether, bis [4- (3-aminophenoxy) phenyl ] ether, 1, 4-bis (4-aminophenyl) benzene, 1, 3-bis (4-aminophenyl) benzene, 9, 10-bis (4-aminophenyl) anthracene, 2-bis (4-aminophenyl) propane, 2-bis (4-aminophenyl) hexafluoropropane, 2-bis [4- (4-aminophenoxy) phenyl ] propane, 2-bis [4- (4-aminophenoxy) phenyl ] hexafluoropropane, At least one of 1, 4-bis (3-aminopropyldimethylsilyl) benzene and BAFL.
The polyimide precursor and the polyimide obtained therefrom may contain a structural unit represented by the following general formula (1).
{ formula (II) wherein R1When a plurality of the groups are present, each independently represents a 1-valent aliphatic hydrocarbon group having 1 to 5 carbon atoms or a 1-valent aromatic group having 6 to 10 carbon atoms, R2When a plurality of the groups are present, each independently represents a 1-valent aliphatic hydrocarbon group having 1 to 5 carbon atoms or a 1-valent aromatic group having 6 to 10 carbon atoms, and m represents an integer of 1 to 200 }
The polyimide precursor and the polyimide obtained therefrom may have a structural unit of the general formula (1) at any site in the molecule, and the structure of the general formula (1) is preferably derived from a silicon-containing compound, for example, a silicon-containing diamine, from the viewpoint of the kind of siloxane monomer, cost, and molecular weight of the polyimide precursor obtained. The silicon-containing diamine is preferably, for example, diamino (poly) siloxane represented by the following formula (2).
{ formula (II) wherein P5Each independently represents a divalent hydrocarbon group, optionally the same or different, P3And P4Are each independently of R as defined in the general formula (1)1And R2And l represents an integer of 1 to 200. }
As the compound represented by the general formula (2), specifically, examples thereof include amine-modified methylphenyl silicone oil at both ends (manufactured BY shin-Etsu chemical Co., Ltd.: X22-1660B-3 (number average molecular weight: 4400), X22-9409 (number average molecular weight: 1340)), anhydride-modified methylphenyl silicone oil at both ends (manufactured BY shin-Etsu chemical Co., Ltd.: X22-168-P5-B (number average molecular weight: 4200)), epoxy-modified methylphenyl silicone oil at both ends (manufactured BY shin-Etsu chemical Co., Ltd.: X22-2000 (number average molecular weight: 1240)), amino-modified dimethyl silicone oil at both ends (manufactured BY shin-Etsu chemical Co., Ltd.: X22-161A (number average molecular weight: 1600), X22-161B (number average molecular weight: 3000), KF8021 (number average molecular weight: 4400), BY16-835U (number average molecular weight: 900), Silaplane FM3311 (number average molecular weight: 1000), and the like.
Examples of the acid dianhydride compound include pyromellitic dianhydride (PMDA), 3,3 ', 4, 4' -biphenyltetracarboxylic dianhydride (BPDA), 4,4 '-Oxydiphthalic Dianhydride (ODPA), norbornane-2-spiro-2' -cyclopentanone-5 '-spiro-2 "-norbornane-5, 5", 6,6 "-tetracarboxylic dianhydride (CpODA), 2', 3,3 '-biphenyltetracarboxylic dianhydride, 4, 4' - (hexafluoroisopropylidene) diphthalic anhydride (6FDA), 5- (2, 5-dioxotetrahydro-3-furanyl) -3-methyl-cyclohexene-1, 2-dicarboxylic anhydride, 1,2,3, 4-benzenetetracarboxylic dianhydride, 3,3 ', 4,4 ' -benzophenonetetracarboxylic dianhydride, 2 ', 3,3 ' -benzophenonetetracarboxylic dianhydride, 3,3 ', 4,4 ' -diphenylsulfonetetracarboxylic dianhydride, methylene-4, 4 ' -diphthalic dianhydride, 1-ethylene-4, 4 ' -diphthalic dianhydride, 2-propylene-4, 4 ' -diphthalic dianhydride, 1, 2-ethylene-4, 4 ' -diphthalic dianhydride, 1, 3-trimethylene-4, 4 ' -diphthalic dianhydride, 1, 4-tetramethylene-4, 4 ' -diphthalic dianhydride, 1, 5-pentamethylene-4, 4 ' -diphthalic dianhydride, 2,3 ' -diphenyl sulfone dianhydride, 1,4 ' -diphenyl sulfone dianhydride, 1, 2-ethylene-4, 4 ' -diphthalic dianhydride, 1, 3-trimethylene-4, 4 ' -diphthalic, 4,4 ' -oxydiphthalic dianhydride, p-phenylene bis (trimellitic anhydride), thio-4, 4 ' -diphthalic dianhydride, sulfonyl-4, 4 ' -diphthalic dianhydride, 1, 3-bis (3, 4-dicarboxyphenyl) benzene dianhydride, 1, 3-bis (3, 4-dicarboxyphenoxy) benzene dianhydride, 1, 4-bis (3, 4-dicarboxyphenoxy) benzene dianhydride, 1, 3-bis [2- (3, 4-dicarboxyphenyl) -2-propyl ] benzene dianhydride, 1, 4-bis [2- (3, 4-dicarboxyphenyl) -2-propyl ] benzene dianhydride, bis [3- (3, 4-dicarboxyphenoxy) phenyl ] methane dianhydride, bis [4- (3, 4-dicarboxyphenoxy) phenyl ] methane dianhydride, 2-bis [3- (3, 4-dicarboxyphenoxy) phenyl ] propane dianhydride, 2-bis [4- (3, 4-dicarboxyphenoxy) phenyl ] propane dianhydride, bis (3, 4-dicarboxyphenoxy) dimethylsilane dianhydride, 1, 3-bis (3, 4-dicarboxyphenyl) -1,1,3, 3-tetramethyldisiloxane dianhydride, 2,3,6, 7-naphthalenetetracarboxylic dianhydride, 1,4,5, 8-naphthalenetetracarboxylic dianhydride, 1,2,5, 6-naphthalenetetracarboxylic dianhydride, 3,4,9, 10-perylenetetracarboxylic dianhydride, 2,3,6, 7-anthracenetetracarboxylic dianhydride and 1,2,7, 8-phenanthrenetetracarboxylic dianhydride, dicyclohexyl-3, 3', 9, 9-bis (3, 4-dicarboxyphenyl) fluorene dianhydride (BPAF), and the like.
Among the above acid dianhydride compounds, preferred are BPDA, ODPA, CpODA, 2 ', 3, 3' -biphenyltetracarboxylic dianhydride, 6FDA, 5- (2, 5-dioxotetrahydro-3-furanyl) -3-methyl-cyclohexene-1, 2-dicarboxylic anhydride, 1,2,3, 4-benzenetetracarboxylic dianhydride, 3,3 ', 4, 4' -diphenylsulfonetetracarboxylic dianhydride, methylene-4, 4 '-diphthalic dianhydride, 1-ethylene-4, 4' -diphthalic dianhydride, 2-propylene-4, 4 '-diphthalic dianhydride, 1, 2-ethylene-4, 4' -diphthalic dianhydride, 1, 3-trimethylene-4, 4 '-Biphthalic dianhydride, 1, 4-Tetramethylene-4, 4' -Biphthalic dianhydride, 1, 5-Pentamethylene-4, 4 '-Biphthalic dianhydride, 4' -Oxybisphthalic dianhydride, p-phenylene bis (trimellitic anhydride), thio-4, 4 '-Biphthalic dianhydride, sulfonyl-4, 4' -Biphthalic dianhydride, 1, 3-bis (3, 4-dicarboxyphenyl) benzene dianhydride, 1, 3-bis (3, 4-dicarboxyphenoxy) benzene dianhydride, 1, 4-bis (3, 4-dicarboxyphenoxy) benzene dianhydride, 1, 3-bis [2- (3, 4-dicarboxyphenyl) -2-propyl ] benzene dianhydride, 1, 3-bis, 1, 4-bis [2- (3, 4-dicarboxyphenyl) -2-propyl ] benzene dianhydride, bis [3- (3, 4-dicarboxyphenoxy) phenyl ] methane dianhydride, bis [4- (3, 4-dicarboxyphenoxy) phenyl ] methane dianhydride, 2-bis [3- (3, 4-dicarboxyphenoxy) phenyl ] propane dianhydride, bis (3, 4-dicarboxyphenoxy) dimethylsilane dianhydride, 1, 3-bis (3, 4-dicarboxyphenyl) -1,1,3, 3-tetramethyldisiloxane dianhydride, 3,4,9, 10-perylene tetracarboxylic dianhydride, 2,3,6, 7-anthracenetetracarboxylic dianhydride, 1,2,7, 8-phenanthrenetetracarboxylic dianhydride and BPAF.
< method for manufacturing flexible liquid Crystal display device >
Another aspect of the present invention is a method of manufacturing a flexible liquid crystal display device including a TFT wiring layer, a liquid crystal layer, a color filter layer, a transparent polyimide layer, and a glass substrate. In the method for manufacturing a flexible liquid crystal display device, the constituent elements, raw materials, and process conditions described above for the flexible liquid crystal display device may be used alone or in combination, unless otherwise specified.
A first embodiment of a method for manufacturing a flexible liquid crystal display device includes the steps of:
(A-I) a laminating step of forming a laminated structure I in which a TFT wiring layer, a transparent polyimide layer and a glass substrate are laminated in this order; and
(B-I) an etching step of etching the glass substrate in the laminated structure I so that the thickness of the glass substrate is in the range of 10 to 70 μm.
In the first embodiment, the processes (a-I) and (B-I) can reduce the process cost and improve the yield without using laser lift-off, and can ensure the bend resistance of the flexible liquid crystal display device. In addition, before or during the step (A-I), a glass substrate having a thickness of more than 70 μm (for example, a thickness of more than 300 μm) is prepared in advance for the TFT wiring layer, and in the step (B-I), the thickness of the glass substrate is adjusted to be in the range of 10 to 70 μm by chemical etching, so that the strength of the glass substrate and the mechanical strength of the flexible liquid crystal display device can be improved. From this viewpoint, in the step (B-I), the thickness of the glass substrate is preferably adjusted to be within a range of 10 to 50 μm, more preferably within a range of 10 to 24 μm, and still more preferably within a range of 10 to 20 μm.
The steps (A-I) and (B-I) will be described with reference to FIGS. 2 and 3. Fig. 2 is a schematic cross-sectional view of a laminated structure I formed using, for example, a TFT wiring layer (300), a transparent polyimide layer (200), and a glass substrate (100) having a thickness of more than 300 μm in the process (a-I) before the process (B-I). The formation of the transparent polyimide layer (200) on the glass substrate (100) having a thickness of more than 300 μm can be performed by, for example, applying or spraying a polyimide precursor resin composition in a nitrogen atmosphere (followed by heating to effect polyimidation), or by bonding the glass substrate (100) and the transparent polyimide layer (200). Further, the formation of the TFT wiring layer (300) on the transparent polyimide layer (200) may be performed by metal (e.g., Al, etc.) sputtering, photolithography/patterning, chemical vapor deposition, or the like.
FIG. 3 is a schematic cross-sectional view of a laminated structure I etched until the thickness of the glass substrate 100 is within a range of 10 to 70 μm, for example, during or after the step (B-I). From the viewpoint of the glass substrate (100) having a residual thickness of 10 μm or more, the etching is preferably chemical etching, and more preferably etching with a hydrofluoric acid solution. In addition, from the viewpoint of reducing the process cost and achieving the bending resistance, the etching solution preferably does not contain silica particles having an average particle diameter of 80nm or less. In the step (B-I), it is preferable to mask the TFT wiring layer (300) and the transparent polyimide layer (200) of the laminated structure I with, for example, a sealant or the like, and etch the exposed glass substrate (100).
A second embodiment of the method for manufacturing a flexible liquid crystal display device includes the steps of:
(A-II) a laminating step of forming a laminated structure II in which a color filter layer, a transparent polyimide layer and a glass substrate are laminated in this order; and
(B-II) an etching step of etching the glass substrate in the laminated structure II so that the thickness of the glass substrate is in the range of 10 to 70 μm.
In the second embodiment, the processes (a-II) and (B-II) can reduce the process cost without using laser lift-off, and ensure the bending resistance of the flexible liquid crystal display device. In addition, before or during the step (A-II), a glass substrate having a thickness of more than 70 μm (for example, a thickness of more than 300 μm) is prepared in advance for the color filter layer, and in the step (B-II), the thickness of the glass substrate is adjusted to be in the range of 10 to 70 μm by chemical etching, so that the strength of the glass substrate and the mechanical strength of the flexible liquid crystal display device can be improved. From this viewpoint, in the step (B-II), the thickness of the glass substrate is preferably adjusted to be within a range of 10 to 50 μm, more preferably within a range of 10 to 24 μm, and still more preferably within a range of 10 to 20 μm.
The steps (A-II) and (B-II) will be described with reference to FIGS. 4 and 5. Fig. 4 is a schematic cross-sectional view of a laminated structure II formed using, for example, a color filter layer (800), a transparent polyimide layer (900), and a glass substrate (1000) having a thickness of more than 300 μm in the process (a-II) before the process (B-II). The formation of the transparent polyimide layer (900) on the glass substrate (1000) having a thickness of more than 300 μm can be performed by, for example, applying or spraying a polyimide precursor resin composition in a nitrogen atmosphere (followed by heating to effect imidization), or by bonding the glass substrate (1000) and the transparent polyimide layer (900). The color filter layer (800) on the transparent polyimide layer (900) can be formed according to a known method for manufacturing a color filter and a black matrix.
FIG. 5 is a schematic cross-sectional view of the laminated structure II etched until the thickness of the glass substrate (1000) is within the range of 10 to 70 μm, for example, during or after the step (B-II). From the viewpoint of a glass substrate (1000) having a residual thickness of 10 μm or more, the etching is preferably chemical etching, and more preferably etching with a hydrofluoric acid solution. In addition, from the viewpoint of reducing the process cost and achieving the bending resistance, the etching solution preferably does not contain silica particles having an average particle diameter of 80nm or less. In the step (B-II), it is preferable that the color filter layer (800) and the transparent polyimide layer (900) of the laminated structure II are masked with, for example, a sealing material, and the exposed glass substrate (1000) is etched.
A third embodiment of the method for manufacturing a flexible liquid crystal display device provides a liquid crystal display unit in which all of the steps (a-I), (a-II), (B-I), and (B-II) described above are performed, the liquid crystal display unit is bonded to the laminated structure I and the laminated structure II with a sealant interposed therebetween, and liquid crystal is injected between the TFT wiring layer of the laminated structure I and the color filter layer of the laminated structure II to form a liquid crystal layer. Fig. 6 is a schematic flow chart of a method for manufacturing a flexible liquid crystal display device according to a third embodiment.
Further, the liquid crystal layer (500) can also be formed by performing the steps (a-I) and (B-I) described above, bonding the liquid crystal display cell to the laminated structure I and the laminated structure II via the sealant, and injecting the liquid crystal between the TFT wiring layer (300) of the laminated structure I and the color filter layer (800) of the laminated structure II (fig. 6 a). Thereafter, the following steps are performed:
(B-III) in the laminated structure I and the laminated structure II, the same flexible liquid crystal display device (1) as described above can be obtained by performing an etching step of etching the glass substrate so that the thickness of the glass substrate is in the range of 10 to 70 μm, and etching the glass substrates (100, 1000) of the laminated structure I and the laminated structure II (B of fig. 6).
As a method for making the glass substrate into a thin film in the steps (B-I), (B-II) and (B-III), there are chemical etching and physical polishing, and in the case of polishing, micro scratches may occur, and chemical etching is preferable from the viewpoint of optical compensation.
By the manufacturing methods of the first, second, and third embodiments, the flexible liquid crystal display device (1) shown in fig. 1 can be obtained.
Examples
(Synthesis of transparent polyimide precursor)
< Synthesis example 1>
To a 3L separable flask equipped with a stirring bar, 233g of N-methylpyrrolidone (NMP) was added while introducing nitrogen, 31.1g of TFMB (2, 2' -bis (trifluoromethyl) benzidine) as a diamine, 13.20g of X-22-1660B-3 (both-terminal amine-modified methylphenyl silicone oil, number-average molecular weight 4400, manufactured by shin-Etsu chemical Co., Ltd.) as a silicon-containing compound was added with stirring, 22.9g of BPAF (9, 9-bis (3, 4-dicarboxyphenyl) fluorene dianhydride) as an acid dianhydride, and 10.9g of PMDA (pyromellitic dianhydride) were added. Here, the molar ratio of acid dianhydride to diamine is 100: 99. Subsequently, the flask was heated to 80 ℃ by using an oil bath, and after stirring for 3 hours, the oil bath was removed and returned to room temperature, thereby obtaining a transparent NMP solution of polyamic acid (hereinafter also referred to as varnish A). The varnish thus obtained was stored in a refrigerator and used after thawing at the time of evaluation.
< Synthesis example 2>
To a 3L separable flask equipped with a stirring bar, while introducing nitrogen gas, NMP (405g) was added, while stirring, 20.5g of TFMB (12.6g), BAFL (1, 4-bis (3-aminopropyldimethylsilyl) benzene, 9-bis (4-aminophenyl) fluorene) as a diamine was added, and then 38.4g of CpODA (norbornane-2-spiro-2 '-cyclopentanone-5' -spiro-2 ″ -norbornane-5, 5 ″,6,6 ″ -tetracarboxylic dianhydride) as an acid dianhydride was added. Here, the molar ratio of acid dianhydride to diamine was 100: 98. Subsequently, the flask was heated to 80 ℃ by using an oil bath, and after stirring for 3 hours, the oil bath was removed and returned to room temperature, thereby obtaining a transparent NMP solution of polyamic acid (hereinafter also referred to as varnish B). The varnish thus obtained was stored in a refrigerator and used after thawing at the time of evaluation.
(preparation of test sample)
< example 1>
The polyimide precursor composition (varnish A) of Synthesis example 1 was applied to an alkali-free glass substrate (hereinafter, also referred to as "glass substrate" or simply as "substrate") having a length of 300 mm. times.350 mm. times.0.7 mm and a thickness of 10 μm after imidization in a region located inside 5mm from the edge of the glass substrate. A slit coater (LC-R300G, manufactured by SCREEN financial Solutions) was used for coating. The solvent was removed from the resulting glass substrate with a coating film by a vacuum dryer (manufactured by Tokyo chemical industries, Ltd.) at 80 ℃ and 100Pa for 30 minutes. The obtained glass substrate having the coating film of the polyimide precursor composition was heated at 400 ℃ for 1 hour in a nitrogen atmosphere (oxygen concentration of 300ppm or less) using an oven (manufactured by INH-9N1Koyo Thermo System), and the polyimide layer was visually confirmed to be transparent by forming the polyimide layer on the glass substrate.
Next, aluminum was formed into a film with a thickness of 100nm by sputtering on the entire glass substrate on which the polyimide layer was formed, and then the film was patterned by photolithography to form an aluminum pattern. Next, an SiN layer was formed on the entire substrate by CVD to a thickness of 200 nm.
Thereafter, an acrylic sealing material was applied to the SiN layer side surface and the substrate side surface of the substrate.
In order to etch the glass substrate, the substrate coated with the sealing material was immersed in an etching bath containing high-purity hydrofluoric acid (Stella Chemifa) at a concentration of 50 wt%, and etched until the thickness of the glass substrate became 70 μm, followed by rinsing with ultrapure water. The thickness of the glass substrate was evaluated by cutting the substrate, embedding the substrate with epoxy resin, and observing the cross section with an optical microscope.
Thereafter, the seal material was removed by immersing the etched sample in an alkali stripping solution (TMAH (tetramethylammonium hydroxide)), thereby obtaining an evaluation sample.
< examples 2 to 4 and comparative examples 1 and 2>
Samples were produced in the same manner as in example 1, except that the etching conditions were adjusted to the thickness of the glass substrate described in table 1.
< examples 5 to 7 and comparative examples 4 and 5>
Samples were produced in the same manner as in example 1, except that the varnish used was changed to varnish B and the thickness of the glass substrate described in table 1 was changed.
< comparative example 3>
In example 1, using a sample before etching of a glass substrate, an excimer laser (wavelength 308nm) was irradiated from the glass substrate side of the glass substrate on which polyimide was formed, and the polyimide was peeled from the glass substrate (no glass substrate).
< comparative example 6>
On an alkali-free glass substrate (hereinafter, also referred to as "glass substrate" or simply "substrate") having a length of 300mm × 350mm × a thickness of 0.7mm, aluminum was formed in a thickness of 100nm by sputtering, and thereafter, the aluminum was patterned by photolithography to form an aluminum pattern. Subsequently, an SiN layer was formed on the entire substrate by a CVD method at a thickness of 200nm to produce a PI-free thin film substrate.
Then, an acrylic sealing material was applied to the surface of the substrate on the SiN layer side and the substrate side surface to obtain a laminate.
The glass substrate is thinned by replacing etching with polishing. Specifically, the side of the laminate body coated with the sealing material is fixed to a polishing head of a polishing apparatus, and polishing is performed by rotating the polishing head and rotating a polishing pad. The polishing slurry used was colloidal silica having an average particle diameter of 80nm or less at a ratio of 100g/cm2The pressure of (3) to perform the grinding. Thereafter, the polishing pad and the slurry were changed to those for finish polishing, finish polishing was performed, etching was performed until the thickness of the glass substrate became 24 μm, and cleaning was performed with ultrapure water. The thickness of the glass substrate was evaluated by cutting the substrate, embedding the cut substrate with epoxy resin, and observing the cross section of the substrate with an optical microscope.
Thereafter, the sealing material was removed by immersing the laminate in an alkali stripping solution (TMAH (tetramethylammonium hydroxide)), thereby obtaining an evaluation sample.
(optical microscopic observation of aluminum surface)
The aluminum surfaces of the substrates obtained in examples and comparative examples were observed with an optical microscope (hereinafter also referred to as "OM observation"). The observation results were evaluated according to the following criteria.
A (optional): no etching was observed on the aluminum surface.
B (non-optional): etching was observed on the aluminum surface.
It was observed that the etched was a sample in which the thickness of the glass substrate was 5 μm or less. This is considered to be because: the glass substrate has a thin portion where the polyimide is etched by hydrofluoric acid (HF), and thereafter the aluminum is etched.
(evaluation of bending resistance)
The substrates obtained in examples and comparative examples were subjected to bending evaluation. Specifically, the minimum radius of curvature at which the substrate was not cracked was evaluated. The bending resistance was evaluated by measuring the radius of curvature according to the following criteria.
A (excellent): the curvature radius is less than 30mm
B (good): the curvature radius is more than 30mm and less than 40mm
C (optional): the curvature radius is more than 40mm and less than 50mm
D (not): radius of curvature exceeding 50mm
The sample having a large radius of curvature is a glass substrate having a thickness of 10 μm or less. This is considered to be because the glass substrate is thick and the glass is broken.
Furthermore, from the comparison of example 7 with comparative example 6, it can be confirmed that: even when the glass substrates have the same thickness, the composite material of the glass substrate and the PI thin film has sufficient bending resistance, although the glass substrate alone has no bending resistance.
(evaluation of warpage)
Warpage evaluation was performed on the substrates obtained in examples and comparative examples. Specifically, the obtained sample was left to stand in a thermostatic chamber of 50 Rh% at 23 ℃ for one day and night. Thereafter, the glass substrate was allowed to stand on the smooth glass plate for a further 30 minutes with the glass substrate side facing downward. The maximum amount of the portion of the sample protruding from the glass plate was measured as the amount of warpage, and evaluated according to the following criteria.
A (optional): the warping amount is below 15mm
B (non-optional): the warping amount exceeds 15mm or the shape of a cylinder
The samples with a large warpage amount had a glass substrate thickness of 5 μm or less or samples without a glass substrate. It can be considered that: the warpage occurs due to a difference in elongation between the polyimide and the inorganic film due to water absorption.
The types of varnish of the polyimide precursor, the thickness of the glass substrate, and various evaluation results are shown in table 1 below.
[ Table 1]
(production of Flexible liquid Crystal display device)
Using the sample of example 7 (thickness of glass substrate: 24 μm), a 100nm Poly-Si layer was formed on the SiN film by CVD, and then annealing was performed at 380 ℃. Further, an alignment film is formed on the TFT wiring layer. Next, an acrylic sealing material is formed at the boundary of the liquid crystal cell, and liquid crystal is dropped into a region surrounded by the sealing material, thereby producing a TFT substrate.
On the other hand, a polyimide layer was formed on the other glass substrate (thickness: 700 μm) in the same manner as in the above-described example, and then a black matrix and a color filter were formed on the surface of the polyimide layer. Thereafter, an alignment film is formed on the color filter. Next, in the same manner as in example 7, a color filter substrate was produced by etching the alignment film so that the thickness of the glass substrate became 24 μm.
The TFT substrate and the color filter substrate were bonded together with a sealing material to produce a flexible liquid crystal display device. The flexible liquid crystal display device includes a TFT substrate including a glass substrate having a thickness of 24 μm and a polyimide layer as substrates, and a color filter substrate including a glass substrate having a thickness of 24 μm and a polyimide layer as substrates, and is excellent in mechanical strength, bending resistance, and warping property.
Claims (25)
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| JP2011227205A (en) * | 2010-04-16 | 2011-11-10 | Hitachi Displays Ltd | Display device |
| CN104765188A (en) * | 2015-04-07 | 2015-07-08 | 深圳市华星光电技术有限公司 | Flexible liquid crystal display |
| CN107994134A (en) * | 2017-11-09 | 2018-05-04 | 武汉华星光电半导体显示技术有限公司 | A kind of flexible base board and preparation method thereof |
| CN108962028A (en) * | 2018-07-10 | 2018-12-07 | 云谷（固安）科技有限公司 | Flexible display screen cover board, Flexible Displays mould group and flexible display apparatus |
| CN109839770A (en) * | 2017-11-29 | 2019-06-04 | 张家港康得新光电材料有限公司 | Flexible display panels and flexible liquid crystal display based on it |
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| US10953633B2 (en) * | 2012-08-31 | 2021-03-23 | Corning Incorporated | Strengthened thin glass-polymer laminates |
| JP2015096313A (en) * | 2013-11-15 | 2015-05-21 | 日本電気硝子株式会社 | Glass film laminate and method of producing liquid crystal panel |
| WO2015194324A1 (en) * | 2014-06-16 | 2015-12-23 | 旭硝子株式会社 | Composite |
-
2020
- 2020-07-13 JP JP2020119918A patent/JP2021026232A/en active Pending
- 2020-08-05 TW TW109126487A patent/TWI743925B/en active
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| JP2011227205A (en) * | 2010-04-16 | 2011-11-10 | Hitachi Displays Ltd | Display device |
| CN104765188A (en) * | 2015-04-07 | 2015-07-08 | 深圳市华星光电技术有限公司 | Flexible liquid crystal display |
| CN107994134A (en) * | 2017-11-09 | 2018-05-04 | 武汉华星光电半导体显示技术有限公司 | A kind of flexible base board and preparation method thereof |
| CN109839770A (en) * | 2017-11-29 | 2019-06-04 | 张家港康得新光电材料有限公司 | Flexible display panels and flexible liquid crystal display based on it |
| CN108962028A (en) * | 2018-07-10 | 2018-12-07 | 云谷（固安）科技有限公司 | Flexible display screen cover board, Flexible Displays mould group and flexible display apparatus |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2025024098A (en) | 2025-02-19 |
| TWI743925B (en) | 2021-10-21 |
| TW202121024A (en) | 2021-06-01 |
| JP2021026232A (en) | 2021-02-22 |
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