JP2002148598A - Reflection type liquid crystal cell substrate and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection type liquid crystal cell substrate which is thin and light in weight and has excellent mechanical strength, gas barrier properties and heat resistance and a low yellowing degree changing ratio and to provide a liquid crystal display device using the reflection type liquid crystal cell substrate. SOLUTION: The reflection type liquid crystal cell substrate wherein a reflection layer consisting of at least a hard coat layer, a base material layer and a metal thin layer is laminated and the hard coat layer is the outermost layer characteristically has <=0.75% yellowing degree changing ratio calculated from the yellowing degree after the substrate is heated at 200 deg.C for 30 min and the yellowing degree at room temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflective liquid crystal cell substrate which is thin, lightweight, excellent in mechanical strength and gas barrier properties, has a low rate of change in yellowness, and is excellent in heat resistance. The present invention relates to a liquid crystal display device used.

[0002]

2. Description of the Related Art In recent years, with the development of satellite communication and mobile communication technology, demand for small portable information terminal equipment has been increasing.
Display devices mounted on many small portable information terminal devices are required to be thin, and liquid crystal display devices are most frequently used. In addition, since a display device for a small portable information terminal device is required to have low power consumption and high visibility under external light, a reflection type liquid crystal display device is more preferable than a transmission type liquid crystal display device. It is heavily used. Glass-based reflective liquid crystal cell substrates have a low impact resistance and are very heavy. Therefore, plastic-based reflective liquid crystal cell substrates are being studied. However, plastic-based liquid crystal cell substrates have poor gas barrier properties, and moisture and oxygen penetrate into the cell through the liquid crystal cell substrate, causing disconnection of the transparent electrode film pattern and moisture and oxygen entering the cell to form bubbles. Grow up to
Problems such as poor appearance and deterioration of the liquid crystal have been problems. Therefore, inorganic gas barrier layers such as metal oxides and organic gas barrier layers such as polyvinyl alcohol have been studied as gas barrier layers. However, the formation of the inorganic gas barrier layer has a problem that productivity is poor because a film forming method such as a sputtering method or a vacuum evaporation method is used. Further, the organic gas barrier layer has a problem that the organic gas barrier layer is liable to yellow and causes poor appearance.

[0003]

SUMMARY OF THE INVENTION The present invention relates to a reflective liquid crystal cell substrate which is thin, lightweight, excellent in mechanical strength and gas barrier properties, hardly yellowed, has a low rate of change in yellowness, and is excellent in heat resistance. It is an object to provide a liquid crystal display device using the reflective liquid crystal cell substrate.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a reflective liquid crystal cell substrate in which at least a hard coat layer, a base layer and a thin metal layer are laminated, and the hard coat layer is the outermost layer. The yellowness change rate calculated from the yellowness after heating at room temperature for 30 minutes and the yellowness at room temperature is 0.7.
It is intended to provide a reflection type liquid crystal cell substrate characterized by being 5 or less. The reflective liquid crystal cell substrate of the present invention preferably has an oxygen transmittance of 0.3 cc / m ² · 24 h · atm or less. The hard coat layer is preferably made of a urethane resin, and the base material layer is preferably made of an epoxy resin. Further, the reflective liquid crystal cell substrate of the present invention preferably has a heat resistance of 200 ° C. or higher. An electrode is formed on the reflective liquid crystal cell substrate of the present invention,
A reflective liquid crystal cell substrate with electrodes can also be used. The present invention also provides a liquid crystal display device using a reflective liquid crystal cell substrate with electrodes.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The reflection type liquid crystal cell substrate according to the present invention has at least a reflection layer composed of a hard coat layer, a base material layer and a thin metal layer, and the hard coat layer is the outermost layer. Wherein the yellowness change rate calculated from the yellowness after heating at 200 ° C. for 30 minutes and the yellowness at room temperature is 0.75 or less.

In the present invention, the reflective layer does not need to be on the outermost layer. That is, the present invention provides a laminate of the outermost layer from the hard coat layer, the substrate layer, and the reflective layer, or a laminate of the outermost layer from the hard coat layer, the reflective layer, and the substrate layer.

In the present invention, the material for forming the hard coat layer includes urethane resin, acrylic resin, polyester resin, polyvinyl alcohol and ethylene.
Examples thereof include a polyvinyl alcohol-based resin such as a vinyl alcohol copolymer, a vinyl chloride-based resin, and a vinylidene chloride-based resin.

Further, polyarylate resins, sulfone resins, amide resins, imide resins, polyethersulfone resins, polyetherimide resins, polycarbonate resins, silicone resins, fluorine resins, polyolefin resins, Styrene-based resins, vinylpyrrolidone-based resins, cellulose-based resins, acrylonitrile-based resins, and the like can also be used for forming the resin layer. Among these resins, urethane resins are preferable, and urethane acrylate is particularly preferably used. In addition, in forming the resin layer,
A blend of two or more kinds of appropriate resins can also be used.

In the present invention, it is preferable to use a thermoplastic resin or a thermosetting resin as the resin forming the base layer. As the thermoplastic resin, polycarbonate,
Polyarylate, polyether sulfone, polysulfone, polyester, polymethyl methacrylate, polyether imide, polyamide, and the like.Examples of the thermosetting resin include epoxy resin, unsaturated polyester, polydiallyl phthalate, polyisobonyl methacrylate, and the like. Can be One or more of these resins can be used, and they can be used as a copolymer or a mixture with other components.

A thermosetting resin is preferably used in order to obtain surface smoothness, and among the thermosetting resins, an epoxy resin is particularly preferably used from the viewpoint of hue. As the epoxy resin, for example, bisphenol A such as bisphenol A type, bisphenol F type, bisphenol S type and their water addition, novolak type such as phenol novolak type and cresol novolak type, triglycidyl isocyanurate type and hydantoin type Nitrogen-containing ring type,
Examples thereof include an alicyclic type, an aliphatic type, an aromatic type such as a naphthalene type, a low water absorption type such as a glycidyl ether type and a biphenyl type, a dicyclo type, an ester type, an ether ester type, and a modified form thereof. These may be used alone or in combination. Among the above various epoxy resins, it is preferable to use a bisphenol A type epoxy resin, an alicyclic epoxy resin, or a triglycidyl isocyanurate type from the viewpoint of anti-discoloration properties.

As such an epoxy resin, those having an epoxy equivalent of 100 to 1000 and a softening point of 120 ° C. or lower are preferably used in view of physical properties such as flexibility and strength of the obtained resin sheet. From the viewpoint of obtaining an epoxy resin-containing liquid having excellent coating properties and spreadability into a sheet, etc., a two-liquid mixed type liquid which shows a liquid state at a temperature lower than the temperature at the time of coating, particularly at room temperature, can be preferably used.

The epoxy resin includes a curing agent, a curing accelerator, and, if necessary, an antioxidant, a denaturant, a surfactant, a dye, a pigment, a discoloration inhibitor,
Various conventionally known additives such as an ultraviolet absorber can be appropriately compounded.

The curing agent is not particularly limited.
One or more appropriate curing agents depending on the epoxy resin can be used. Incidentally, examples thereof include tetrahydrophthalic acid, methyltetrahydrophthalic acid, organic acid compounds such as hexahydrophthalic acid and methylhexahydrophthalic acid, ethylenediamine, propylenediamine, diethylenetriamine, triethylenetetramine and their amine adducts, meta Examples include amine compounds such as phenylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone.

Amide compounds such as dicyandiamide and polyamide; hydrazide compounds such as dihydrazide; methylimidazole, 2-ethyl-4-methylimidazole, ethylimidazole, isopropylimidazole, 2,4-dimethylimidazole, phenylimidazole; Imidazole compounds such as undecyl imidazole, heptadecyl imidazole and 2-phenyl-4-methylimidazole are also examples of the curing agent.

Further, methylimidazoline, 2-ethyl-4-methylimidazoline, ethylimidazoline, isopropylimidazoline, 2,4-dimethylimidazoline, phenylimidazoline, undecylimidazoline,
Imidazoline compounds such as heptadecyl imidazoline and 2-phenyl-4-methylimidazoline, phenol compounds, urea compounds and polysulfide compounds are also examples of the curing agent.

In addition, acid anhydride compounds and the like are also mentioned as examples of the curing agent, and from the viewpoint of preventing discoloration, such acid anhydride curing agents can be preferably used. Examples thereof are phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride, nadic anhydride, glutaric anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, Examples include methylhexahydrophthalic anhydride, methylnadic anhydride, dodecenylsuccinic anhydride, dichlorosuccinic anhydride, benzophenonetetracarboxylic anhydride and chlorendic anhydride.

In particular, they are colorless or pale yellow, such as phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride and methylhexahydrophthalic anhydride.
An acid anhydride curing agent having a molecular weight of about 140 to about 200 is preferably used.

The mixing ratio of the epoxy resin and the curing agent is such that when an acid anhydride curing agent is used as the curing agent, the acid anhydride equivalent is 0.5 to 1 to 1 equivalent of the epoxy group of the epoxy resin. It is preferable to mix so as to be 5 equivalents, more preferably 0.7 to 1.2 equivalents. If the acid anhydride is less than 0.5 equivalent, the hue after curing becomes worse,
If it exceeds 1.5 equivalents, the moisture resistance tends to decrease. When other curing agents are used alone or in combination of two or more, the amount used is in accordance with the equivalent ratio described above.

Examples of the curing accelerator include tertiary amines, imidazoles, quaternary ammonium salts, organic metal salts, phosphorus compounds, urea compounds, and the like. In particular, tertiary amines, It is preferable to use imidazoles and phosphorus compounds. These can be used alone or in combination.

The amount of the curing accelerator is preferably 0.05 to 7.0 parts by weight, more preferably 0.2 to 3.0 parts by weight, based on 100 parts by weight of the epoxy resin. . If the amount of the curing accelerator is less than 0.05 parts by weight, a sufficient curing promoting effect cannot be obtained, and if it exceeds 7.0 parts by weight, the cured product may be discolored.

Examples of the antioxidant include conventionally known compounds such as phenol compounds, amine compounds, organic sulfur compounds and phosphine compounds.

Examples of the modifying agent include conventionally known modifying agents such as glycols, silicones and alcohols.

The above-mentioned surfactant is added to smooth the surface of the epoxy resin sheet when the epoxy resin sheet is molded by the casting method while contacting the epoxy resin with air. Examples of the surfactant include a silicone type, an acrylic type, a fluorine type and the like, and a silicone type is particularly preferable.

The reflection layer of the present invention needs to be formed of a thin metal layer such as silver or aluminum. The reflective layer has a gas barrier function and prevents moisture and oxygen from penetrating the liquid crystal cell substrate and entering the cell. Therefore, in the present invention, there is no need to laminate an organic gas barrier layer made of polyvinyl alcohol or the like or an inorganic gas barrier layer made of silicon oxide or the like.

The thickness of the reflective layer is preferably 50 to 1000 nm, more preferably 100 to 500 nm.
Is good. When the thickness of the reflective layer is less than 50 nm, reliability such as heat resistance and moisture resistance is reduced. The thickness of the reflective layer is 1
If it exceeds 000 nm, cracks are likely to occur and the cost increases. Further, the transmission mode between the transmission mode and the reflection mode cannot be used.

In the present invention, the liquid crystal cell substrate is 200
The yellowness change rate calculated from the yellowness after heating at 30 ° C. for 30 minutes and the yellowness at room temperature needs to be 0.75 or less. The degree of change in yellowness is defined as Y at room temperature.
I, when the yellowness after heating at 200 ° C. for 30 minutes is YI ₂₀₀ , it can be calculated by (Equation 1). Yellowness change rate is 0.7
When the value exceeds 5, when a liquid crystal display device is formed using the liquid crystal cell substrate, the display quality deteriorates, such as a white display having a yellow tint.

(Equation 1)

The oxygen transmission rate of the reflective liquid crystal cell substrate of the present invention is preferably 0.3 cc / m ² · 24 h · atm or less. More preferably, the oxygen permeability of the liquid crystal cell substrate is 0.15 cc / m ² · 24 h · atm or less. If the oxygen transmission rate exceeds 0.3 cc / m ² · 24 h · atm, moisture and oxygen enter the cell, causing disconnection of the transparent conductive film pattern and moisture and oxygen entering the cell to form bubbles. By that time, problems such as poor appearance and deterioration of the liquid crystal arise.

In the step of assembling the liquid crystal cell from the liquid crystal cell substrate, the step of firing the alignment film and the step of firing the sealing agent are performed at about 150 ° C., and the sputtering of a transparent electrode such as ITO is performed at about 180 ° C. In these steps, in order to maintain the quality reliability of the liquid crystal cell substrate, the liquid crystal cell substrate preferably has heat resistance of 200 ° C. or higher.

The reflection type liquid crystal cell substrate of the present invention can be provided with electrodes to provide a reflection type liquid crystal cell substrate with electrodes.

As the electrode, a transparent electrode film is preferably used. The transparent electrode film is provided by using a suitable forming material such as indium oxide, tin oxide, indium / tin mixed oxide, gold, platinum, palladium, or a transparent conductive paint, for example, by a vacuum evaporation method, a sputtering method, or a coating method. Alternatively, the transparent conductive film can be formed by a method according to the related art such as a coating method, and the transparent conductive film can be directly formed in a predetermined electrode pattern. An alignment film for liquid crystal alignment provided on the transparent conductive film as needed can also be added by a method according to the related art.

A liquid crystal display device is generally formed by appropriately assembling components such as a polarizing plate, a liquid crystal cell, a reflector or a backlight, and optical components as necessary, and incorporating a drive circuit. In the present invention, there is no particular limitation except that the above-mentioned reflection type liquid crystal cell substrate is used, and it can be formed according to a conventional method. Therefore, when forming the liquid crystal display device of the present invention, for example, a light diffusion plate provided on the polarizing plate on the viewing side, an anti-glare layer,
Appropriate optical components such as an antireflection film, a protective layer, a protective plate, or a compensating retardation plate provided between the liquid crystal cell and the polarizing plate on the viewing side can be appropriately combined with the reflective liquid crystal cell substrate.

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited to these examples.

Example 1: 100 parts (parts by weight, hereinafter the same) of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate represented by the chemical formula (1) and the chemical formula (2) 125 parts of methylhexahydrophthalic anhydride and 1 part of tetra-n-butylphosphonium o, o-diethylphosphorodithioate represented by the following chemical formula were stirred and mixed to prepare a liquid containing an epoxy resin. .

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First, a 17 wt% toluene solution of urethane acrylate represented by the chemical formula (Chemical Formula 4) was applied to a stainless steel endless belt at a running speed of 0.3 m / min by casting and air-dried to evaporate toluene. Thereafter, the composition was cured using a UV curing apparatus to form a hard coat layer having a thickness of 2 μm. Subsequently, the epoxy-based resin-containing liquid was cast and applied on the hard coat layer at a rate of 0.3 m / min and cured using a heating device to form an epoxy-based resin layer having a thickness of 400 μm.

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Next, the laminated body of the hard coat layer and the epoxy resin layer was peeled off from the endless belt, and was replaced on a glass plate at 180 ° C. in an atmosphere having an oxygen concentration of 0.5% by nitrogen replacement.
× After leaving for 1 hour, after-curing was performed. Next, an aluminum reflective layer having a thickness of 1000 nm was formed on the epoxy resin layer side of the laminate including the hard coat layer and the epoxy resin layer by a vacuum evaporation method.

[0035]

Comparative Example 1 First, a 17% by weight urethane acrylate toluene solution was cast and applied to a stainless steel endless belt at a running speed of 0.3 m / min, air-dried to evaporate the toluene, and then a UV curing device was used. Cured to a film thickness of 2 μm
Was formed. Subsequently, a 5.5% by weight aqueous solution of a polyvinyl alcohol-based resin is applied on the hard coat layer by casting at a rate of 0.3 m / min and dried at 100 ° C. for 10 minutes to form an organic gas barrier layer having a thickness of 3.7 μm. did.
Subsequently, the epoxy resin-containing liquid prepared in Example 1 was applied onto the organic gas barrier layer by casting at a rate of 0.3 m / min, and cured using a heating device to form an epoxy resin layer having a thickness of 400 μm. did. Next, the laminated body of the hard coat layer, the organic gas barrier layer, and the epoxy resin layer was peeled off from the endless belt, and left on a glass plate at 180 ° C. for 1 hour in an atmosphere having an oxygen concentration of 0.5% by replacing with nitrogen. Cure was done. Next, an aluminum reflective layer having a thickness of 1000 nm was formed on the epoxy resin layer side of the laminate including the hard coat layer, the organic gas barrier layer, and the epoxy resin layer by a vacuum evaporation method.

Evaluation test: oxygen permeability (cc / m ² · 24)
h · atm), yellowness index (YI value) Oxygen permeability is OX- manufactured by Modern Controls according to the oxirant method.
Measured using TRAN TWIN. Measurement conditions are 40
° C and 43% RH. The yellowness index (YI value) is JIS K-7103 using CMS-500 manufactured by Murakami Colors.
It was measured according to. The sample used was a 30 × 50 mm flat plate.

The results are shown in Table 1.

[Table 1]

When a liquid crystal display device was prepared using the liquid crystal cell substrate of Example 1, the weather resistance was excellent and the display quality was excellent. When a liquid crystal display device was prepared using the liquid crystal cell substrate of Comparative Example 1, there was no problem with weather resistance.
The white display was yellowish.

[0039]

As described above, the reflection type liquid crystal cell substrate of the present invention is thin, light, and excellent in mechanical strength because it is made of resin.
Since the reflection layer has a gas barrier function, there is no need to stack an organic gas barrier layer. Therefore, the reflective liquid crystal cell substrate of the present invention has a feature that the rate of change in yellowness is small and the heat resistance is excellent.

[Brief description of the drawings]

FIG. 1 shows an example of the resin sheet of the present invention.

[Explanation of symbols]

 1: Hard coat layer 2: Base layer 3: Reflective layer

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Yoshimasa Sakata 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation (72) Inventor Kiichi Shimohira 1-1-2 Shimohozumi, Ibaraki-shi, Osaka No. Nitto Denko F-term (reference) 2H090 HA04 HB07X JA06 JA07 JB03 JB06 JC07 JD01 JD17 LA01 LA20 2H091 FA14Z FB08 GA02 GA07 GA16 LA04 LA11 LA20 2K009 AA15 BB23 CC35

Claims (7)

[Claims] 1. A reflective liquid crystal cell substrate in which at least a reflective layer comprising a hard coat layer, a base material layer and a thin metal layer is laminated, and the hard coat layer is the outermost layer, the reflective liquid crystal cell substrate has a temperature
A reflection type liquid crystal cell substrate, wherein a yellowness change rate calculated from yellowness after minute heating and yellowness at room temperature is 0.75 or less. 2. An oxygen permeability of 0.3 cc / m ² · 24 h ·
2. The reflection type liquid crystal cell substrate according to claim 1, wherein the reflection type liquid crystal cell substrate is at most atm. 3. The reflective liquid crystal cell substrate according to claim 1, wherein said hard coat layer is made of a urethane resin. 4. The reflective liquid crystal cell substrate according to claim 1, wherein said base layer is made of an epoxy resin. 5. The reflective liquid crystal cell substrate according to claim 1, which has a heat resistance of 200 ° C. or higher. 6. A reflection type liquid crystal cell substrate, wherein electrodes are provided on the reflection type liquid crystal cell substrate according to claim 1. 7. A liquid crystal display device using the reflection type liquid crystal cell substrate according to claim 6.