JP2002287121A - Substrate for reflective liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection type liquid crystal display substrate being low-cost, resistant to cracks, excellent in insulation efficiency and characteristic of generating no cracks in electrodes. SOLUTION: The substrate for the reflective liquid crystal display is constructed by using a laminated sheet consisting of at least a metal layer with 50 to 700 μm thickness and a resin layer having imide bonds in the main- chain and exhibiting -10 to 50 ppm average linear expansion coefficient at 30 to 200 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic substrate for a display element mainly used for a reflection type liquid crystal display device.

[0002]

2. Description of the Related Art Liquid crystals, plasma displays, electroluminescence (EL), fluorescent display tubes, light emitting diodes
A glass plate is often used as a display substrate such as a glass substrate. However, considering a large area, it is easy to crack,
In recent years, many attempts have been made to use a plastic material instead of a glass plate due to problems such as being unbendable, having a large specific gravity, and being unsuitable for weight reduction. However, in a conventional plastic display element substrate, since the difference in thermal expansion coefficient between the resin layer and the electrode forming the substrate is large, especially in the case of a TFT liquid crystal substrate which is exposed to a high temperature change during processing, a transparent electrode is used. Cracks were likely to occur, causing an increase in the resistance value, and sometimes a disconnection. IT
Materials having a thermal expansion coefficient close to that of an electrode such as O include ceramics such as glass, metal, and polyimide. However, glass is easily broken as described above, and metal has a problem in insulating properties as a substrate. . Further, polyimide is expensive as a material of the substrate.

On the other hand, a reflection type liquid crystal display device does not require a backlight which occupies a large part of power consumption in an environment where external light is present. ing. In an environment where there is external light such as sunlight, the reflection type liquid crystal display device is used as a substitute for a backlight by reflecting and scattering by a reflection plate provided on a backside substrate of a display cell.
The display can also be performed by reflecting light supplied from the light source.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a reflection type liquid crystal display substrate having the above-mentioned problems, and is characterized by being inexpensive, resistant to cracking, excellent in insulating properties and not causing wiring cracks. It supplies a reflective liquid crystal display substrate.

[0005]

Means for Solving the Problems Plastic is light,
Although it has the advantage of being difficult to break and is easy to bend, and has characteristics that glass does not have as a next-generation display element substrate, it has problems in elongation and contraction due to water absorption and temperature change, that is, dimensional stability. On the other hand, metals are excellent in impact resistance, gas barrier properties, etc., but have problems in acid resistance, insulating properties as a substrate, and the like. Polyimide, a type of plastic, has high water absorption, but has a low coefficient of linear thermal expansion and is an excellent material in that it does not cause cracks in wiring.However, compared to glass and other plastic materials, the material unit price is higher. It was expensive and difficult to use in terms of cost. The present inventors consider that it is difficult to solve the above-described problems by using one type of material, and as a result of intensive studies,
The inventors have found that the above problem can be solved by laminating a resin layer having an imide bond by a method such as direct coating on a metal, and have reached the following invention.

That is, the present invention provides: (1) at least a metal layer having a thickness of 50 to 700 μm and an average linear expansion coefficient at 30 to 200 ° C. of -10 to 5;
A reflective liquid crystal display substrate using a laminated sheet comprising a resin layer having an imide bond in a main chain of 0 ppm. (2) The reflective liquid crystal display substrate according to claim 1, wherein a difference in average linear expansion coefficient between the metal layer and the polyimide at 30 to 200 ° C is 0 to 30 ppm. (3) The thickness of the resin layer is 1 to 700 μm (1),
(2) The reflective liquid crystal display substrate. (4) A resin layer is formed on both sides of a metal layer (1) to
(3) The reflection type liquid crystal display substrate. (5) The total thickness of the substrate is 51 to 1100 μm (1)
(4) The reflection type liquid crystal display substrate. (6) The resin layer having an imide bond in the main chain is mainly composed of a thermosetting polyimide (1) to (5).
Reflective liquid crystal display substrate. (7) The reflective liquid crystal display substrate according to any one of (1) to (6), wherein the resin layer having an imide bond in the main chain contains a condensation type polyimide as a main component. (8) The reflective liquid crystal display substrate of (7), wherein the condensed polyimide is synthesized from the aromatic dianhydride represented by Formula 1 and the aromatic diamine represented by Formula 2.

[0007]

Embedded image (R and R 'each represent an alkyl group, an alkoxy group having ₁ to ₃ carbon atoms, an acyl group, or a halogen, and may be the same or different. X and y each represent the number of substituents on the same aromatic ring; =
The integers of 0 to 3 and y = 0 to 3 may be the same or different.
n = 0 to 5)

[0008]

Embedded image (R and R 'each represent an alkyl group, an alkoxy group having ₁ to ₃ carbon atoms, an acyl group, or a halogen, and may be the same or different. X and y each represent the number of substituents on the same aromatic ring; =
0 to 4, y = 0 to 4 may be the same or different.
n = 0 to 5)

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The metal layer of the present invention is for maintaining rigidity of a substrate and suppressing thermal expansion, and has a thickness of 50 to 700 μm, preferably 70 to 500 μm.
More preferably 80 to 400 μm, even more preferably 1 to 400 μm.
It is 00 to 300 μm. If this thickness is too thin, rigidity cannot be maintained, and if it is too thick, it becomes heavy. Examples of preferred metals include metals and alloys typically including stainless steel, copper, aluminum, iron, nickel, chromium, zinc, tin, magnesium and the like.

The resin layer having an imide bond in the main chain of the present invention is for improving electrical insulation, preventing direct contact with an acidic substance and reducing its weight, and also for suppressing thermal expansion. . Therefore, 30 to 200
The average coefficient of linear expansion at ℃ is in the range of -10 to 50 ppm, preferably in the range of -5 to 30 ppm, more preferably in the range of 0 to 20 ppm. Average linear expansion coefficient is -10
If the content is less than 50 ppm or more than 50 ppm, the difference from the average linear expansion coefficient of the metal used for the wiring becomes large, and there is a possibility that disconnection may occur when exposed to high temperatures.
For this reason, it is desirable that the difference in the average linear expansion coefficient between 30 and 200 ° C. between the metal layer and the resin layer be 0 to 30 ppm. As a preferred example of the resin layer, a thermosetting polyimide resin is preferably used as a main component, and among the thermosetting polyimides, a condensation type polyimide is preferable. As an example of the condensation type polyimide, a polyimide synthesized from an aromatic dianhydride represented by Formula 1 and an aromatic diamine represented by Formula 2 can be given.

The substituents R and R 'in the formula 1 represent an alkyl group, an alkoxy group having ₁ to ₃ carbon atoms, an acyl group, and a halogen, and may be the same or different. The number of substituents is not particularly limited, and may not have a substituent. Also, the bonding position is not particularly limited. The number of aromatic rings may be 1 to 6 and para-bonded (n = 0 to 5), preferably 1 to 3 (n = 0 to 2), and most preferably 1 (N = 0). For example,
Examples include pyromellitic dianhydride, biphthalic anhydride, p-terphenyltetracarboxylic dianhydride, and the like.
Particularly preferred is pyromellitic dianhydride. These aromatic acid dianhydrides may be used alone or in combination of several kinds. In order to balance with other characteristics, a small amount of another acid anhydride may be used in combination.

Other acid anhydrides to be used in combination include, for example, benzene-1,2,3,4-tetracarboxylic dianhydride,
3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 2,2 ′, 3,3′-benzophenonetetracarboxylic dianhydride, 2,3,3 ′, 4′-benzophenonetetracarboxylic acid Dianhydride, naphthalene-2,3,
6,7-tetracarboxylic dianhydride, naphthalene-1,
2,5,6-tetracarboxylic dianhydride, naphthalene-
1,2,4,5-tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, naphthalene-1,2,6,7-tetracarboxylic dianhydride,
4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5 , 6, 7-
Hexahydronaphthalene-2,3,6,7-tetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,
4,5,8-tetracarboxylic dianhydride, 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-tetrachloronaphthalene-
1,4,5,8-tetracarboxylic dianhydride, 1,4,
5,8-tetrachloronaphthalene-2,3,6,7-tetracarboxylic dianhydride, 2,2-bis (2,3-dicarboxyphenyl) -propane dianhydride, 2,2-bis (3 , 4-dicarboxyphenyl) -propane dianhydride, bis (2,3-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (2,3-di Carboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl)
Methane dianhydride, bis (2,3-dicarboxyphenyl) sulfone dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane Dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, berylen-2,3,8,9-tetracarboxylic dianhydride,
Perylene-3,4,9,10-tetracarboxylic dianhydride, perylene-4,5,10,11-tetracarboxylic dianhydride, perylene-5,6,11,12-tetracarboxylic dianhydride Phenanthrene-1,2,7,8-tetracarboxylic dianhydride, phenanthrene-1,2,
6,7-tetracarboxylic dianhydride, phenanthrene-
1,2,9,10-tetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, pyrazine-2,3,5,6-tetracarboxylic dianhydride, Examples include, but are not limited to, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride and thiophene-2,3,4,5-tetracarboxylic dianhydride. In addition, in use, even one kind is 2
Mixtures of more than one type may be used.

The aromatic diamine used in the present invention may have a skeleton as shown in Formula 2, and a substituent may be bonded to the aromatic ring.

[0014]

Embedded image (R and R 'each represent an alkyl group, an alkoxy group having ₁ to ₃ carbon atoms, an acyl group, or a halogen, and may be the same or different. X and y represent the number of substituents on the same aromatic ring;
= 0 to 4, y = 0 to 4 may be the same or different. n = 0 to 5)

The substituents R and R 'are an alkyl group and the carbon number is C.
Represents an alkoxy group, an acyl group, or a halogen atom of ₁ to ₃ ;
It may be the same or different. It is preferably an alkyl group, and particularly preferably a methyl group. The number of substituents is not particularly limited, and may not have a substituent. Also,
The bonding position is not particularly limited. The number of aromatic rings may be 1 to 6 and para-bonded (n = 0 to 5).
), And preferably 2 to 3 (n = an integer of 1 to 2). For example, p-phenylenediamine, benzidine,
o-Tolidine, m-tolidine, bis (trifluoromethyl) benzidine, 4,4 "-diamino-p-terphenyl and the like. Preferably, o-tolidine, m-tolidine, 4,4" -diamino-p -Terphenyl. These aromatic diamines may be used alone or in combination of several kinds. In order to balance with other characteristics, a small amount of other diamines may be used in combination.

Other diamines used in combination include 1,4
-Bis (3-aminopropyl) tetramethyldisiloxane, m-phenylene-diamine, 1-isopropyl-
2,4-phenylene-diamine, 4,4′-diamino-
Diphenylpropane, 3,3′-diamino-diphenylpropane, 4,4′-diamino-diphenylethane,
3,3′-diamino-diphenylethane, 4,4′-diamino-diphenylmethane, 3,3′-diamino-diphenylmethane, 4,4′-diamino-diphenyl sulfide, 3,3′-diamino-diphenyl sulfide,
4,4'-diamino-diphenylsulfone, 3,3'-
Diamino-diphenylsulfone, 4,4'-diamino-
Diphenyl ether, 3,3′-diamino-diphenyl ether, benzidine, 3,3′-diamino-biphenyl, 3,3′-dimethyl-4,4′-diamino-biphenyl, 3,3′-dimethoxy-benzidine, 4,4 '-
Diamino-p-terphenyl, 3,3′-diamino-p
-Terphenyl, bis (p-amino-cyclohexyl)
Methane, bis (p-β-amino-t-butylphenyl)
Ether, bis (p-β-methyl-δ-aminopentyl) benzene, p-bis (2-methyl-4-amino-pentyl) benzene, p-bis (1,1-dimethyl-5-
(Amino-pentyl) benzene, 1,5-diamino-naphthalene, 2,6-diamino-naphthalene, 2,4-bis (β-amino-t-butyl) toluene, 2,4-diamino-toluene, 2,6- Diamino-pyridine, 2,5-
Diamino-pyridine, 2,5-diamino-1,3,4-
Oxadiazole, 1,4-diamino-cyclohexane, piperazine, methylene-diamine, ethylene-diamine, propylene-diamine, 2,2-dimethyl-propylene-diamine, tetramethylene-diamine, pentamethylene-diamine, hexamethylene-diamine 2,
5-dimethyl-hexamethylene-diamine, 3-methoxy-hexamethylene-diamine, heptamethylene-diamine, 2,5-dimethyl-heptamethylene-diamine,
3-methyl-heptamethylene-diamine, 4,4-dimethyl-heptamethylene-diamine, octamethylene-diamine, nonamethylene-diamine, 5-methyl-nonamethylene-diamine, 2,5-dimethyl-nonamethylene-
Diamine, decamethylene-diamine, 1,10-diamino-1,10-dimethyl-decane, 2,11-diamino-dodecane, 1,12-diamino-octadecane, 1,
12-diamino-octadecane, 2,17-diamino-
Aicosan, diaminosiloxane, 2,6-diamino-
4-carboxylic benzene, 3,3'-diamino-
4,4′-dicarboxylic benzidine and the like, but are not limited thereto. In use, one kind or a mixture of two or more kinds may be used.

In the resin layer of the present invention, if necessary, various kinds of additives such as a lubricant, a heat-resistant agent, an antistatic agent, an ultraviolet absorber, a pigment, etc., which are usually blended in optical materials, as long as the effects of the present invention are not impaired. Can be blended. Further, on the resin layer, it is also possible to laminate an inorganic film for suppressing a dimensional change due to water absorption, and to protect an undercoat layer and an inorganic film for improving the adhesion between the inorganic film and the resin layer. Can be laminated. The resin layer of the present invention,
It must be in direct contact with the metal layer, and is preferably formed by spraying, a roll coater, a gravure coater, a dip coater, or a casting method (solvent casting), but is not particularly limited. Further, the thickness of the resin layer is preferably formed to be 1 to 700 μm.

The metal layer and the resin layer of the present invention may be at least one layer. For example, by laminating resin layers on both sides of the metal layer, or by changing the thickness and type of the resin layers on both sides. It is also possible to prevent the substrate from warping.
Of course, any number of various metal layers and resin layers may be laminated. And the total thickness is preferably 51 to 1100 μm. If it is too thin, it lacks rigidity, and if it is too thick, there is no merit as a thin display element.

[0019]

Next, the present invention will be described in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples unless it exceeds the gist. (Example 1): After completely dissolving 6.37 g of o-tolidine in 130 mL of N, N-dimethylacetamide, 6.54 g of pyromellitic dianhydride was added, and the mixture was added at 15 ° C. for 1 hour and at room temperature for 3 hours. Stirred. The obtained varnish is applied to a thickness of 10
After casting on a 0 μm stainless steel foil (SUS403) and drying, the back surface is also cast in the same manner, and 150 ° C. * 30 minutes + 200 ° C. * 30 minutes + 25 in an oven under reduced pressure.
Heating was carried out under reduced pressure at 0 ° C. * 30 minutes + 300 ° C. * 3 hours for imidization to obtain a 200 μm thick substrate. (Polyimid / SUS403 / Polyimid = 50/100/50 μm) (Example 2): After completely dissolving 3.24 g of p-phenylenediamine in 130 mL of N, N-dimethylacetamide, 8.83 g of biphthalic anhydride was added. In addition, 15 ℃
For 1 hour and at room temperature for 20 hours. The obtained varnish was dip-coated on a zinc plate having a thickness of 300 μm, dried, and further heated in an oven under reduced pressure at 150 ° C. for 30 minutes.
Heating was performed under reduced pressure at 200 ° C. * 30 minutes + 250 ° C. * 30 minutes + 300 ° C. * 3 hours for imidization to obtain a substrate having a thickness of 320 μm. (Polyimid / zinc / polyimid = 10/300 / 10μm)

(Comparative Example 1): After completely dissolving 6.01 g of 4,4′-diaminodiphenyl ether in 130 mL of N, N-dimethylacetamide, 6.54 g of pyromellitic dianhydride was added, and the mixture was heated at 15 ° C. Stir for 1 hour and 3 hours at room temperature. The resulting varnish was cast on a stainless steel foil (SUS304) having a thickness of 100 μm, dried, and then cast on the back surface in the same manner.
0 ° C * 30 minutes + 200 ° C * 30 minutes + 250 ° C * 30 minutes +
Heat at 300 ° C * 3 hours under reduced pressure for imidization, thickness 20
A 0 μm substrate was obtained. (Polyimide / SUS304 / Polyimid = 50/100 /
(50 μm) These sheets were evaluated by the following evaluation methods. The results are shown in Table 1.

<Evaluation method> Average coefficient of linear expansion: TMA / SS12 manufactured by Seiko Denshi
Using a 0C-type thermal stress / strain measuring apparatus, the temperature was raised from room temperature at a rate of 5 ° C./min.
° C) and hold for 20 minutes, then 5 ° C per minute
The temperature was cooled to room temperature at a rate of and the temperature was kept at room temperature for 5 minutes. Thereafter, the temperature was again raised at a rate of 5 ° C. per minute, and the value at 30 ° C. to 200 ° C. was measured and found.
(When the temperature obtained by subtracting 20 ° C. from the heat deformation temperature is 350 ° C. or more, the temperature is 350 ° C.) Solvent resistance: 40 ° C. dimethyl sulfoxide (DMS)
O) The sample is immersed in the solution and left for 60 minutes. After taking out the sample, the external appearance was visually observed. Alignment agent resistance: A sample is placed on a spin coater. After dropping CRD-8201 (manufactured by Sumitomo Bakelite) on the surface, spin coating was performed at 2500 rpm. 180
After drying at 60 ° C. for 60 minutes, the appearance was visually observed. Liquid crystal resistance: ZLI-479 manufactured by Merck on the surface of the substrate
2 is added dropwise. Put in an oven at 120 ° C and put 6
Leave for 0 minutes. After removing the sample, the external appearance is visually observed. Heat resistance: 200 ° C x 2 hours, 95 ° C hot water x 3
After repeating the treatment for 0 minutes twice, the resin layer surface was visually observed.

[0022]

[Table 1]

As shown in Table 1, in Examples, the average linear expansion coefficient of the resin layer was as low as 30 ppm or less, and the difference in average linear expansion coefficient with the metal layer was as low as 5 ppm. No changes such as cracks were observed in the resin layer even in the property evaluation test. On the other hand, in the comparative example, although the same polyimide resin was used for the resin layer, the average linear expansion coefficient was as high as 59 ppm, and the difference between the average linear expansion coefficient and the metal layer was about 50 ppm. Therefore, it is considered that the resin layer was cracked in the heat resistance evaluation. The substrate of the present invention was considered to be suitable for use as a reflective liquid crystal display substrate without any problem in solvent resistance, alignment agent resistance, and liquid crystal resistance.

[0024]

As described above, according to the method of the present invention, in the performance of the reflection type liquid crystal display substrate, all of which could not be satisfied by the conventional technique, the reflection type liquid crystal display substrate is inexpensive, hardly cracked, and has excellent insulating properties. As a result, it has become possible to supply a reflective liquid crystal display substrate having the characteristic of not causing cracks in the electrodes.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Sumio Shibahara 2-5-8 Higashishinagawa, Shinagawa-ku, Tokyo Sumitomo Bakelite Co., Ltd. F-term (reference) 2H090 HB08X HB09X HC07 HC08 JA06 JA09 JA19 JB01 JB03 JC07 JD18 2H091 FA14X FA14Z FD06 GA07 LA04 LA11 4J043 PA02 QB15 QB26 QB31 RA05 RA35 SA06 SA42 SA47 SA51 SA72 SB01 TA06 TA22 TA41 TA71 TB01 UA111 UA112 UA121 UA122 UA131 UA132 UA141 UA142 UA151 UA152 UA161 UA47 ABA4A1A UA172 UA172 UA172 UA172 UA172 UA172 UA172

Claims (8)

[Claims] At least a metal layer having a thickness of 50 to 700 μm and an average linear expansion coefficient at 30 to 200 ° C.
A reflective liquid crystal display substrate using a laminated sheet comprising a resin layer having an imide bond in the main chain at 10 to 50 ppm. 2. The reflective liquid crystal display substrate according to claim 1, wherein the difference in the average linear expansion coefficient between the metal layer and the polyimide at 30 to 200 ° C. is 0 to 30 ppm. 3. The reflective liquid crystal display substrate according to claim 1, wherein the thickness of the resin layer is 1 to 700 μm. 4. The reflective liquid crystal display substrate according to claim 1, wherein a resin layer is formed on both sides of the metal layer. 5. The reflective liquid crystal display substrate according to claim 1, wherein the total thickness of the substrate is 51 to 1100 μm. 6. The reflective liquid crystal display substrate according to claim 1, wherein the resin layer having an imide bond in a main chain is mainly composed of a thermosetting polyimide. 7. The resin layer having an imide bond in a main chain mainly comprising a condensation type polyimide.
7. The reflective liquid crystal display substrate according to any one of claims 6 to 6. 8. The reflective liquid crystal display substrate according to claim 7, wherein the condensed polyimide is synthesized from an aromatic dianhydride represented by Formula 1 and an aromatic diamine represented by Formula 2. Embedded image (R and R 'each represent an alkyl group, an alkoxy group having ₁ to ₃ carbon atoms, an acyl group, or a halogen, and may be the same or different. X and y each represent the number of substituents on the same aromatic ring; =
The integers of 0 to 3 and y = 0 to 3 may be the same or different.
(n = an integer from 0 to 5) (R and R ′ represent an alkyl group, an alkoxy group having ₁ to ₃ carbon atoms, an acyl group, or a halogen, and may be the same or different. X and y represent the number of substituents on the same aromatic ring; =
0 to 4, y = 0 to 4 may be the same or different.
n = 0 to 5)