JPH07325296A - Plastic substrate for liquid crystal display panel - Google Patents

Abstract

PURPOSE:To obtain a substrate for liquid crystal display panel low in moisture vapor permeation rate, excellent in adhesivility to a supporting body and a transparent electrode and having excellent solvent resistance by providing a hardened layer formed by cross-linking and bonding an addition polymerizable monomer to a styrene/maleic acid monoamide copolymer on one surface of a plastic film. CONSTITUTION:A polymerization initiator or photopolymerization initiator (1), the addition polymerizable monomer (2) having an ethylenic unsaturated double bond and a photopolymerizable composition (3) obtained by allowing a styrene/maleic anhydride copolymer having a repeating unit expressed by formula 1 and 500-10000 weight average molecular weight to react with a primary amine expressed by formula 11 are applied on the plastic film and are photopolymerized. The reaction ratio of the primary amine to the styrene/maleic anhydride copolymer is preferably 0.1-1.0 equivalent per equivalent of styrene/ maleic anhydride copolymer. As the primary amine, 2-ethoxy ethylamine or 3-methoxy propylamine is preferably used.

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 liquid crystal display panel having a low moisture permeability.

[0002]

2. Description of the Related Art In recent years, liquid crystal display panels have been widely used in devices such as notebook personal computers, electronic notebooks, mobile phones, etc. where portability is important, and along with this demand for thinner and lighter devices. ing. Usually, a glass substrate is used in these display panels, and studies have been made to reduce the thickness of the substrate. However, there is a problem that the thinner the substrate, the easier it is to break.

In order to solve this problem, the possibility of using a plastic sheet (or film) as a substrate has been studied, but one of the major problems of the plastic substrate is that it is more permeable to moisture than a glass substrate. It is easy to do. Moisture that has penetrated into the liquid crystal through the substrate may hydrolyze and deteriorate liquid crystal molecules, and may even damage the electrodes. In order to prevent this, various measures have been taken so far.

Japanese Patent Laid-Open No. 61-69027 discloses a technique of forming a polyvinyl alcohol film. However, these layers do not always have sufficient heat resistance, and from the viewpoint of solvent resistance, it is necessary to perform lamination or multilayer coating.

Japanese Unexamined Patent Publication (Kokai) No. 4-337208 discloses providing a metal thin film and a transparent transparent metal oxide layer. Although this method is very effective from the viewpoint of moisture permeability, vacuum processing is the main method and the process is economically inferior.

Japanese Unexamined Patent Publication Nos. 3-9323 and 5-3131
No. 50 discloses a technique in which an anchor coat layer is provided on a support, an air permeation resistant layer is then provided, and a layer made of a crosslinked resin cured product is further provided thereon. However, even if the adhesive strength is increased by the anchor coat layer and the cured resin layer is pressed from above, sufficient heat resistance is not always imparted.
If a vinyl-based polymer is used for the gas permeable layer, this layer softens during high temperature treatment to cause film misalignment, or when a large amount of vinylidene halide is used, dehydrohalogenation reaction often occurs. There is a phenomenon that it is awakened and colored. This tendency becomes even stronger if the thickness of this layer is increased in order to improve air resistance.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to
(1) The moisture permeability is lowered, (2) the adhesion between the support and the transparent electrode is good, (3) it is not attacked by the patterning treatment of the transparent electrode, and (4) the coating solvent for the alignment film is also used. No corrosion, (5) Deformation or coloring does not occur even if left in an atmosphere of 180 ° C. for about 1 hour, (6) Curing by ultraviolet rays and / or heat, moisture resistance and as an undercoat layer for transparent electrodes An object of the present invention is to provide a plastic substrate for a liquid crystal display panel, which has a layer having both characteristics.

[0008]

As a result of earnest efforts, the present inventors have found that the object of the present invention is to provide at least (1) a photopolymerization initiator or a photopolymerization initiator system, or heat on a plastic film or sheet. A polymerization initiator or a thermal polymerization initiator system, (2) an addition polymerizable monomer having an ethylenically unsaturated double bond, and (3) a repeating unit represented by the following general formula (I), and having a weight average molecular weight: 500-1
50,000 styrene / maleic anhydride copolymers,
Include a styrene / maleic acid monoamide copolymer obtained by reacting a primary amine represented by the following general formula (II) in a ratio of 1.0 to 0.1 equivalent relative to 1 equivalent of an anhydride group. The present invention has been accomplished by discovering that this can be achieved by applying a photopolymerizable composition characterized by the above, and performing photopolymerization and / or heat polymerization on a plastic substrate.

[0009]

[Chemical 1]

Where Φ is an alkyl group having 1 to 4 carbon atoms,
It represents an alkoxy group having 1 to 4 carbon atoms, an aralkyl group having 8 to 12 carbon atoms, a phenyl group which may be substituted with a halogen atom or a combination of two or more thereof. x and y represent the mole fraction of the repeating unit, and y / x + y = 0.15
Is about 0.45. Wherein _{R-NH 2 (II),} R is an alkyl group having 1 to 12 carbon atoms, 7 carbon atoms
14 represents an aralkyl group having 14 carbon atoms, an aryl group having 6 to 18 carbon atoms, or an alkoxyalkyl group having 2 to 14 carbon atoms.
Hereinafter, the present invention will be described in detail.

The composition ratio y / x + y of repeating units of the styrene / maleic anhydride copolymer used in the present invention is preferably 0.15 to 0.45, particularly preferably 0.
2 to 0.45.

The weight average molecular weight of the styrene / maleic acid copolymer is preferably in the range of 500 to 20,000,
More preferably, it is 1,000 to 10,000. It is difficult to produce a copolymer having a weight average molecular weight of less than 500.

Specific examples of the primary amine used in the present invention include methylamine, ethylamine, propylamine,
Iso-propylamine, butylamine, t-butylamine, sec-butylamine, pentylamine, hexylamine, cyclohexylamine, heptylamine, octylamine, laurylamine, benzylamine, phenethylamine, aniline, octylaniline, anisidine, 4-chloroaniline, 1-naphthylamine, methoxymethylamine, 2-methoxyethylamine, 2-ethoxyethylamine, 3-methoxypropylamine, 2-
Examples thereof include butoxyethylamine, 2-cyclohexyloxyethylamine, 3-ethoxypropylamine, 3-propoxypropylamine, 3-isopropoxypropylamine, cyclohexylamine and benzylamine. Examples of particularly preferred primary amines are 2-methoxyethylamine, 2-ethoxyethylamine or 3-
Methoxypropylamine.

In the present invention, the reaction ratio of the styrene / maleic anhydride copolymer and the primary amine is preferably 0.1 to 1.0 equivalent, more preferably 1 equivalent to the maleic anhydride group. Is 0.2 to 1.0 equivalent. The desired reaction can be efficiently progressed by making the charged amount of amine excess over the maleic anhydride equivalent, but in that case, excess amine is removed and purified by a method such as reprecipitation of the copolymer. It is desirable to do.

The addition-polymerizable monomer having an ethylenically unsaturated double bond can be used alone or in combination with other monomers, and specifically, t-butyl acrylate, ethylene glycol diacrylate, 2-hydroxypropyl methacrylate, triethylene glycol diacrylate, trimethylolpropane triacrylate, 2-ethyl, 2-butyl-propanediol diacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, dipentaerythritol pentaacrylate,
Polyoxyethylated trimethylolpropane triacrylate, tris (2-acryloyloxyethyl) isocyanurate, 1,4-diisopropenylbenzene,
Examples thereof include 1,4-dihydroxybenzene dimethacrylate, decamethylene glycol diacrylate, styrene, diallyl fumarate, triallyl trimellitic acid, lauryl acrylate, methacrylamide, and xylylenebisacrylamide. Particularly preferred are pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, dipentaerythritol pentaacrylate, and tris (2-acryloyloxyethyl) isocyanurate.

The total amount of monomers in the above composition is
It is 10% to 80% by weight, particularly preferably 20% to 70% by weight, based on all components of the composition. 8
If it exceeds 0% by weight, the tackiness of the composition is increased and the handleability is poor.

As the photopolymerization initiator or the photopolymerization initiator system contained in the composition, substantially all known compounds can be used. Examples include p-methoxyphenyl-2,4-bis (trichloromethyl) -s-triazine, 2- (p-butoxystyryl) -5-trichloromethyl-1,3,4-oxadiazole, 9-phenyl. There are acridine, 9,10-dimethylbenzphenazine, benzophenone / Michler's ketone, hexaarylbiimidazole / mercaptobenzimidazole, benzyldimethylketal, thioxanthone / amine and the like.
Particularly preferred is 2- (p-butoxystyryl) -5-
There are trihalomethyl group-containing compounds such as trichloromethyl-1,3,4-oxadiazole. The addition amount of the photopolymerization initiator is 0.1% by weight to 20% by weight, and particularly preferably 0.5% by weight to 5% by weight, based on the total solid content.

Examples of the thermal polymerization initiator include various peroxides and azo compounds. Specific examples include 2,2-azobisisobutyronitrile and 1,1'-azobis (cyclohexane-1-carbonitrile). ), 2,2′-azobis (2-methylbutyronitrile) and the like.

As the plastic film or sheet, polycarbonate, polyether sulfone, polyethylene terephthalate, polyethylene naphthalate,
Homopolymers or copolymers of polymethylmethacrylate, polyacrylate, polyether, polysulfone, norbornene polymer and the like can be used.

The film thickness of the moisture-permeable and crosslinked cured layer of the present invention is preferably 1 to 20 μm, more preferably 2 to 20 μm.
It is 15 μm. This layer may be provided alone, or another layer may be provided between the support and the layer. A spin coater, a roll coater, a hopper coater, a dip coater, or the like can be used to provide the layer. It may be continuously applied to a roll-shaped plastic film, or may be cut into a sheet shape and applied one by one.

In the case of photopolymerization, a mercury lamp or the like may be used as a light source and ultraviolet light may be irradiated. Irradiation efficiency can be improved by performing irradiation in a nitrogen atmosphere or under reduced pressure. In the case of thermal polymerization, it may be placed in an atmosphere of 80 to 150 ° C. or the film may be placed on a hot plate.

To provide a transparent electrode on the layer, a method known to those skilled in the art, such as sputtering, vacuum deposition, or ion plating, can be used. The transparent electrode thus formed can be patterned by using a photolithography process, and an alignment film for liquid crystal can be applied onto the electrode.

The plastic substrate for a liquid crystal display panel according to the present invention is a TN (Twisted Nematic) type, STN (Super Tw) type.
isted Nematic) type, ferroelectric liquid crystal type, MIM (Metal-Ins)
It can be used for a display element using an emulator-metal type or the like. Hereinafter, the present invention will be described in detail based on examples, but the present invention is not limited thereto.

[0024]

【Example】

Example 1 [Synthesis of styrene / maleic acid amide copolymer] Styrene / maleic anhydride copolymer (SMA2 manufactured by Atchem Co., Ltd.)
000, styrene / maleic anhydride = about 2/1 (molar ratio), weight average molecular weight = 2800) and 30.6 parts of propylene glycol monomethyl ether acetate 122.
Dissolved in 4 parts. Methoxyethylamine 3.76
Parts / propylene glycol monomethyl ether acetate (15.0 parts) was added dropwise at room temperature over about 1 hour.
Further, the mixture was stirred at room temperature for 6 hours to obtain a 20% by weight solution of methoxyethylamine modified product of styrene / maleic anhydride.

[Preparation of coating liquid] Mix and dissolve with the following composition,
A coating liquid for forming a protective layer was prepared by filtering with a filter having a hole diameter of 0.2 μm. 20 parts by weight solution of the copolymer produced in Synthesis Example 68 parts Dipentaerythritol hexaacrylate 3.4 parts Tris (acryloyloxyethyl) isocyanurate 10.2 parts 2- (4-butoxystyryl) -5 -Trichloromethyl-1,3,4-oxadiazole 0.65 part-Hydroquinone monomethyl ether 0.007 part-Fluorine-based surfactant (F177P) 0.002 part (MechaFac F111P manufactured by Dainippon Ink and Chemicals, Inc.) )

[Preparation of coating film] The above coating liquid was applied onto a norbornene-based polymer having a film thickness of 120 μm using a bar coater to form a coating film having a film thickness after drying of 3 μm. 200 mj / c under ultra-high pressure mercury lamp under reduced pressure
It was irradiated with ultraviolet rays with a light amount of m ² , and subsequently heat-treated at 145 ° C. for 60 minutes.

[Measurement of Moisture Permeability] The moisture permeability was measured in accordance with the cup method defined in JIS-70208. However, the atmosphere was 30 ° C. and 85% RH. As a comparative sample, a single film made of norbornene polymer was used. The moisture permeability was as follows. Film according to the present invention 1.7 × 10 ⁻³ g / 24Hr · cm ² Norbornene simple substance film 5.1 × 10 ⁻³ g / 24Hr · cm ² From this, it can be seen that the moisture permeability was reduced to 1/3.

[Formation of transparent electrode] Indium tin oxide (tin oxide content: 10%, hereinafter referred to as ITO) was formed on the film provided with the moisture-proof layer according to the present invention by using a magnetron sputtering apparatus. Abbreviated target is used,
IT with a film thickness of 100 nm at a sputtering rate of 10 nm / min
An O film was formed. The surface resistivity was 42Ω / □.

Furthermore, a positive photoresist (FH, manufactured by Fuji Hunt Electronics Technology Co., Ltd., is formed on the ITO film).
2130), exposed through an electrode pattern mask, developed, etched the ITO layer with hydrochloric acid / iron chloride aqueous solution, and peeled with a resist stripping solution (Fuji Hunt Electronics Technology Co., Ltd., MS2001). The ITO electrode without the obtained was obtained.

On the other hand, when the transparent electrode was formed on the norbornene simple substance film by the same method at the same time, the ITO surface was cracked during the etching process. In some areas, it was even worse, and there were areas where the ITO had almost peeled off.

[Formation of Alignment Film] On a substrate provided with a moisture-proof film and a transparent electrode layer on a norbornene film, an alignment film coating liquid (polyimide resin N-methylpyrrolidone / γ-butyrolactone solution) was spin-coated. Although it was applied and dried at 145 ° C., an alignment film layer was obtained without swelling and generation of reticulation.

Example 2 [Preparation of coating liquid] The following composition was mixed and dissolved, and filtered through a filter having a hole diameter of 0.2 μm to prepare a coating liquid for forming a protective layer. 20 parts by weight solution of the copolymer produced in the synthesis example 68 parts Dipentaerythritol hexaacrylate 3.4 parts Tris (acryloyloxyethyl) isocyanurate 10.2 parts 2,2'-azobisisobutyro Nitrile 0.7 parts ・ Fluorosurfactant (F177P) 0.002 parts (MechaFac F111P manufactured by Dainippon Ink and Chemicals, Inc.)

The above coating solution was applied onto a polyether sulfone film (thickness 110 μm) and dried at 80 ° C. for 20 minutes. The film thickness after drying was 8 μm. Further 17
It heat-processed at 5 degreeC for 1 hour.

The moisture permeability of this sample was measured under the same conditions as in Example 1 and found to be 1.2 × 10 ⁻³ g / 24 Hr · cm ² .

On this layer, as in the first embodiment, IT
An O layer was provided and patterned. 18 after applying the alignment film
After heat treatment at 0 ° C. for 30 minutes, no cracks or reticulation were generated on the electrode surface, and no problem occurred in the subsequent rubbing process.

[0036]

EFFECT OF THE INVENTION The plastic substrate for liquid crystal display panel of the present invention has low moisture permeability, good adhesion to the support and the transparent electrode, and is practically used as a coating solvent for the patterning of the transparent electrode and a coating solvent for the alignment film. 180 ℃
Even if left in the atmosphere for about 1 hour, no deformation or coloring occurs.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yuichi Wakata Inventor Yuichi Wakata 200 Onakazato, Fujinomiya-shi, Shizuoka Fuji Photo Film Co., Ltd.

Claims (1)

[Claims] 1. A layer containing at least one side of a plastic film or plastic sheet, containing at least a styrene / maleic acid monoamide copolymer, a monomer having an ethylenically unsaturated double bond, and a polymerization initiator, A plastic substrate for a liquid crystal display panel, which is provided with a transparent electrode after light and / or thermal polymerization.