JP2003222840A - Plastics substrate for display element and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plastics substrate for a display element, which is excellent in surface smoothness, has excellent characteristics as a plastics substrate for a display element such as a substrate for a liquid crystal display element and which is efficiently and continuously produced and to provide a liquid crystal display device using the same. <P>SOLUTION: The plastics substrate for the display element is characterized by being manufactured by laminating an ultraviolet curing resin composition predominantly composed of an acrylate monomer and a high molecular weight acrylate on a base film, closely bringing a smooth surface with the maximum value of the surface roughness (Rmax) satisfying an inequality Rmax≤0.1 μinto contact with the resin composition side of the laminate in a state in which the ultraviolet curing resin composition is softened, making ultraviolet rays irradiate the resultant composite, transferring the smooth surface thereto and molding the substrate and by having 80% or higher total light transmittance. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a plastic substrate for a display element and a liquid crystal display device using the same.

[0002]

2. Description of the Related Art Conventionally, a glass substrate has been used as a transparent electrode substrate for a liquid crystal display element. However, in a liquid crystal display element using a glass substrate, the glass substrate itself is thick, so that the liquid crystal display element itself cannot be thinned. In addition to being difficult, it is difficult to reduce the weight, and there is a problem in impact resistance. As a method for improving the drawbacks of the glass substrate liquid crystal display element, reduction in weight and improvement in impact resistance have been studied by producing a liquid crystal display element using an optical polymer sheet. For example, in JP-A-53-68099 and JP-A-54-126559, liquid crystal display elements are continuously formed by using a long polyester film deposited with a conductive metal oxide substance instead of a glass substrate. Although it has been shown to be produced, unlike a glass substrate which can obtain extremely good smoothness by polishing, it is hard to say that the polymer sheet has excellent surface smoothness. In particular, STN (Super Tw
In the case of an isted Nematic) type liquid crystal display element, the surface smoothness of the polymer sheet is extremely high because the display is performed by utilizing the birefringence of the liquid crystal between the substrates, which is controlled in the unit of 0.1 μm. It's getting serious.

As a method for solving the surface smoothness, a method has been proposed in which a liquid ultraviolet-curable resin composition or thermosetting resin composition is poured onto a surface of a polished glass or the like and cured to obtain a sheet. . However, this method has a problem that the obtained sheet is fragile and is cracked or chipped during handling, and the superiority of using a polymer sheet for a glass substrate has not been sufficiently exerted. Moreover, the method has low productivity, resulting in expensive substrates.
Further, a method of continuously transferring the surface of a metal roll or an endless belt whose surface has been polished has been proposed, but the releasability between the metal and the ultraviolet curable resin layer is not sufficient, or the releasability between the metal and A good ultraviolet curable resin has insufficient heat resistance after curing, and when used as a liquid crystal display element, there is a problem that the connection reliability due to the anisotropic conductive film is lowered or the display quality is lowered.

[0004]

The object of the present invention is to provide a display having excellent surface smoothness and excellent characteristics as a plastic substrate for display devices such as substrates for liquid crystal display devices and capable of efficient continuous production. An object is to provide a plastic substrate for devices and a liquid crystal display device using the same.

[0005]

Means for Solving the Problems That is, according to the present invention, (1) an ultraviolet curable resin composition containing an acrylate monomer and a high molecular weight acrylate as a main component is laminated on a base film to soften the ultraviolet curable resin composition. The maximum surface roughness (Rmax) is Rmax ≦
A plastic substrate for a display device, wherein a 0.1 μm smooth surface is brought into close contact, ultraviolet rays are irradiated to transfer and mold the smoothed surface, and the total light transmittance is 80% or more. (2) The plastic substrate for a display device according to (1), wherein the high molecular weight acrylate has a molecular weight of 2000 or more. (3) The acrylate monomer is isocyanuric acid E
The plastic substrate for a display device according to (1) or (2), which is an O-modified triacrylate. (4) The plastic substrate for a display device according to (1) to (3), wherein the compounding ratio of the high molecular weight acrylate in the ultraviolet curable resin composition is 5% to 50%. (5) The ultraviolet-curable resin composition has excellent releasability from a metal after the effect (1) to
(4) A plastic substrate for a display device. (6) The plastic substrate for a display element according to (1) to (5), wherein the ultraviolet curable resin composition has a dynamic storage elastic modulus of 10 ³ MPa or more at a temperature of 200 ° C. or less. (7) The plastic substrate for a display element according to any one of (1) to (6), wherein the surface having the smooth surface is provided on the cell inner surface side of the liquid crystal display device. (8) The glass transition temperature of the base film is 160 ° C.
The above is the plastic substrate for a display device according to (1) to (7). (9) A liquid crystal display device using the plastic substrate for a display device according to (1) to (8). Is.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention provides an acrylate monomer in order to prevent the metal roll from being easily peeled off after transfer of a smooth surface and the resin composition to be transferred to the roll side, which has been a problem in the past. It is a plastic substrate for a display device in which a high molecular weight acrylate is blended with to improve roll releasability, and is a liquid crystal display device using the same.

The base film used for the plastic substrate for a display device of the present invention is required to withstand the manufacturing environment temperature of the display device, and its glass transition temperature is preferably 160 ° C. or higher. Examples include polyesters, polycarbonates, norbornenes, polyetherimides, polyarylates, polyethersulfones, polyetherketones, polyphenylene sulfides, syndiotactic polystyrenes, cyclic polyolefins and their copolymers, imide-modified polymethylmethacrylate, and other imide-modified high polymers. Examples thereof include a film sheet made of molecules and the like, but are not particularly limited. Further, the base film of the present invention may be subjected to surface treatment such as degassing treatment, corona discharge treatment and flame treatment in order to enhance the adhesion with each layer to be laminated, prior to the formation of each layer. The base film is
It can be formed into a sheet by a method such as extrusion molding and casting, and the plastic substrate for a display element of the present invention is
It has a structure in which an ultraviolet curable resin composition is laminated on a molded base film by casting, coating or various printing methods, laminating methods and the like.

The ultraviolet curable resin composition used in the present invention contains a mixture of an acrylate monomer and a high molecular weight acrylate as a main component. When only the acrylate monomer is laminated, the roll is brought into close contact with the resin in the softened state, and the film is peeled from the roll after being cured by ultraviolet rays, the resin component partially moves to the roll and the laminated surface has a smooth surface shape. Some parts are not transferred. Therefore, the present inventors laminated a mixed resin in which a high-molecular-weight acrylate was mixed with an acrylate monomer, so that the film was easily peeled from the roll without the resin composition being transferred, and the film was smooth on the laminated resin surface. It was found that the surface shape was transferred. Here, the compounding ratio of the high molecular weight acrylate is not particularly limited, but is 5 to 50%, more preferably 5% to 30.
The range of% is desirable. If the amount is more than the upper limit, the dynamic storage elastic modulus at the time of sealing material adhesion may be less than 10 ³ MPa and the required characteristics may not be satisfied. On the contrary, when the amount is small, the effect of preventing the transfer of the resin component to the roll becomes small. That is, the present invention has found that an acrylate monomer is necessary as a resin component from the viewpoint of elastic modulus at the time of heating, and a high molecular weight acrylate as a resin component from the viewpoint of releasability from a metal surface. The molecular weight of the acrylate is preferably 2000 or more. If it is lower than this, the effect of preventing the transfer of the resin component to the roll is reduced. Examples of preferred high molecular weight acrylates include urethane acrylates, epoxy acrylates, polyester acrylates, cardo polyester acrylates,
Examples thereof include, but are not limited to, acrylate-modified cyclic cycloolefin. The acrylate monomer of the present invention is not particularly limited, but examples thereof include isocyanuric acid EO-modified triacrylate, trimethylolpropane triacrylate, and pentaerythritol tetraacrylate. Among these, isocyanuric acid EO-modified triacrylate is preferable.
Further, the ultraviolet curable resin composition of the present invention, silica,
A filler such as alumina, polystyrene, or acrylic, a silicon-based or fluorine-based leveling material, a silicon-based or titanate-based silane coupling material, or the like may be added.

The UV-curable resin composition used in the present invention is coated on a base film by a coating device, and when a solvent is contained, the solvent is volatilized by a drying device. When a roll having a surface is brought into close contact with the surface of a smooth surface to be transferred, the ultraviolet curable resin composition must be softened or liquefied so that the smooth surface is sufficiently transferred to the surface of the ultraviolet curable resin composition. I have to. The ultraviolet curable resin composition may include a liquid or one that is softened at room temperature without containing a solvent.
If not, it is necessary to heat with a heater or the like before adhering, or to raise the temperature of the roll to soften at the same time as adhering. The elastic modulus of the ultraviolet curable resin composition of the present invention is preferably sufficiently high in the temperature range in the liquid crystal display element forming step after curing, and is the highest processing temperature in the step (200 in the case of an active element such as TFT).
° C., the dynamic storage modulus in a temperature range of 0.99 ° C.) or less in the case of STN is preferably at 10 ³ MPa or more. The dynamic storage elastic modulus below the highest processing temperature in the process is 10 ³
If the pressure is less than or equal to MPa, display unevenness may occur in the vicinity of the sealing material after the sealing material is bonded, or the connection reliability may decrease due to the connection with the external terminal by the anisotropic conductive film.

The maximum surface roughness (Rmax) of the surface of a metal roll or endless belt used for transfer is Rmax.
It must be a smooth surface of ≦ 0.1 μm. This is because when the surface roughness is larger than 0.1 μm, display unevenness occurs due to the nonuniform cell gap when a liquid crystal display element is formed. The surface of the metal roll or the endless belt is Rmax ≦ 0.1 by a method such as polishing.
It can be processed to μm.

Regarding the ultraviolet irradiation for curing the ultraviolet curable resin composition of the present invention, light having a necessary wavelength may be selectively irradiated. Specifically, a method such as providing a selective transmission filter in the irradiation part or irradiating from the surface opposite to the side where the coating film of the film is formed can be mentioned. When oxygen in the atmosphere interferes with the curing reaction of the UV-effect resin, irradiation may be performed in an atmosphere of an inert gas such as nitrogen. UV dose is 365nm or 25
When selectively irradiating a wavelength of 4 nm or a certain wavelength,
The irradiation amount in the wavelength region where the maximum irradiation amount is obtained in the ultraviolet region is measured with an ultraviolet illuminometer.

[0012]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to the examples. Moreover, various optical properties were measured by the following methods. (1) Sheet thickness An average value measured at intervals of 20 mm in the width direction of the sheet with a contact type dial gauge. (2) Maximum surface roughness (Rmax) Contact type precision step gauge (TENCOR INSTRUMENTS, AlPHA-ST
Maximum value of unevenness measured by EP200) with a scan width of 2 mm in the width direction of the sheet. (3) Maximum surface roughness (Rmax) Contact-type precision step gauge (TENCOR INSTRUMENTS, ALPHA-ST
The maximum value of unevenness measured by EP200) in the width direction of the sheet with a scan width of 1 mm. Example 1 Thickness of 200 μm, maximum surface roughness (Rma
x) 0.3 μm polyether sulfone was used as a base film, and the following processing was carried out using a manufacturing apparatus having a unwinding device, a coater section, a heating and drying zone, a laminating roll, a high pressure mercury lamp, and a winding device. First, as an ultraviolet curable resin composition, isocyanuric acid EO-modified triacrylate having a molecular weight of 400 (M-315 manufactured by Toagosei Co., Ltd.)
80 parts by weight, 20 parts by weight of urethane acrylate (UX3204 manufactured by Nippon Kayaku) having a molecular weight of 13000, 300 parts by weight of butyl acetate, 100 parts by weight of cellosolve acetate,
Stir 2 parts by weight of benzoin ethyl ether at 50 ° C.,
What was dissolved and made into a uniform solution was coated with a gravure roll coater in the coater part to a film thickness of 5 μm before drying, and heated at 100 ° C. for 5 minutes in a heat drying zone to remove the solvent. After removing the solvent, the ultraviolet curable resin composition was in a paste-like softened state. Subsequently, when a metal roll having Rmax = 0.07 μm was closely adhered to the surface and irradiated with 80 w / cm of ultraviolet rays for 10 seconds to cure and peel off the ultraviolet curable resin composition, the ultraviolet curable resin composition was a polymer. It was possible to transfer the smooth surface without shifting from the sheet to the roll. The total light transmittance was measured and found to be 87%. Further, regarding the elastic modulus at the sealing material pressure bonding temperature, a dynamic viscoelasticity measuring device DMS210 was used by using a sample which was subjected to a heat treatment at 160 ° C. for 2 hours assuming the liquid crystal display element processing process before bonding the sealing material. As a result of measuring the value of the dynamic storage elastic modulus E ′ using (manufactured by Seiko Instruments Inc.), the dynamic storage elastic modulus decreased as the temperature increased, and was 1100 MPa at 150 ° C.

Next, a mixed gas of oxygen / argon gas of 9% was introduced onto the polymer sheet by the DC magnetron method from the state of the initial vacuum degree of 3 × 10 −4 Pa to 3 × 1.
Sputtering is performed under the condition of 0-1 Pa and 50
SiO ₂ having a thickness of 0Å was obtained. Then, as a transparent conductive film,
Similarly, by DC magnetron method, the initial vacuum degree is 3 × 10−
A mixture gas of 4% oxygen / argon gas was introduced from the state of 4 Pa, sputtering was performed under the condition of 1 × 10 −1 Pa, and a transparent indium tin oxide (ITO) having an In / In + Sn atomic ratio of 0.98 was obtained. A conductive film was obtained. As a result of the measurement, the film thickness is 1600Å and the specific resistance is 4 × 10.
It was ^-4 Ω-cm. After the ITO film is formed, a resist is applied and developed, and 10 vol% HCl as an etching solution,
Pattern etching was performed at a liquid temperature of 40 ° C. to form a display pattern having a diagonal length of 3 inches and L / S = 150/50 μm. After patterning, apply STN alignment film and
After firing at 2 ° C. for 2 hours, rubbing was performed so that the twist orientation was 240 degrees. After the rubbing process,
Spacers were scattered, a sealant was applied, the seal was cured at 130 ° C. to form a cell, and the liquid crystal composition for STN was injected. A liquid crystal display device was produced by bonding a polarizing plate to a position where the contrast was maximum. When a lighting test was conducted on this liquid crystal display device at a drive voltage of 0 V to ± 5 V, no uneven display due to an abnormal cell gap of the liquid crystal was observed and a good display was shown.

Example 2 Polyethersulfone having a thickness of 200 μm and a maximum surface roughness (Rmax) of 0.05 μm is used as a polymer sheet raw material, and a unwinding device, a coater section, a heat drying zone, and a laminate are used. The following processing was performed using the manufacturing apparatus which has a roll, a high pressure mercury lamp, and a winding device. First, the molecular weight of the ultraviolet curable resin composition: 40
80 parts by weight of EO-modified isocyanuric acid EO-modified triacrylate (M-315 manufactured by Toagosei Co., Ltd.), urethane acrylate having a molecular weight of 4000 (UN9000H manufactured by Negami Kogyo)
20 parts by weight, butyl acetate 300 parts by weight, cellosolve acetate 100 parts by weight, benzoin ethyl ether 2 parts by weight, primary particle size 0.08, high silica 15 parts by weight at 50 ° C.
The mixture was stirred to form a uniform dispersion, which was applied to a film thickness of 5 μm before drying with a gravure roll coater in the coater section, and heated in a heating and drying zone at 100 ° C. for 5 minutes to remove the solvent. After removing the solvent, the ultraviolet curable resin composition was in a paste-like softened state. Then Rmax = 0.07 on the surface
When a metal roll having a thickness of μm was brought into close contact, and the ultraviolet curable resin composition was cured by being irradiated with ultraviolet rays of 80 w / cm and peeled off, the ultraviolet curable resin composition did not move from the polymer sheet to the roll, A smooth surface can be transferred, and a polymer sheet was continuously obtained by winding with a winding device. The irradiation time of ultraviolet rays was 10 seconds. The total light transmittance was 85%. Furthermore, the dynamic storage elastic modulus at 150 ° C. measured in the same manner as in Example 1 was 1260 MPa.
The temperature dependence of the dynamic storage elastic modulus was also the same as in Example 1. Next, a mixed gas of oxygen / argon gas 9% was introduced onto this polymer sheet by a DC magnetron method from the state of an initial vacuum degree of 3 × 10 −4 Pa to 3 × 10 3.
Sputtering is performed under the condition of -1 Pa and 500
Å thick SiO ₂ was obtained. Then, as a transparent conductive film, an initial vacuum degree of 3 × 10 −4 was similarly obtained by the DC magnetron method.
A mixture gas of 4% oxygen / argon gas was introduced from the state of Pa, sputtering was performed under the condition of 1 × 10 −1 Pa, and a transparent indium tin oxide (ITO) having an In / In + Sn atomic ratio of 0.98. A conductive film was obtained.
As a result of the measurement, the film thickness is 1600Å and the specific resistance is 4 × 10 ^-4 Ω.
-Cm. After forming ITO, a resist is applied and developed, and pattern etching is performed in an etching solution of 10 vol% HCl at a solution temperature of 40 ° C., and a diagonal length of 3 inches,
A display pattern of L / S = 150/50 μm was formed.
After forming the pattern, apply an alignment film for STN, and 150 ℃ 2
After the firing treatment for hr, the rubbing treatment was performed so that the twist orientation was 240 degrees. After the rubbing treatment, spacers were scattered, a sealant was applied, the seal was cured at 130 ° C. to form a cell, and the liquid crystal composition for STN was injected. A liquid crystal display device was produced by bonding a polarizing plate to a position where the contrast was maximum. This liquid crystal display device is driven by 0
When a lighting test was performed from V to ± 5 V, display unevenness due to an abnormal cell gap of the liquid crystal was not observed and good display was shown.

<Comparative Example 1> Thickness 200 μm Polyethersulfone having a maximum surface roughness (Rmax) of 0.05 μm was used as a polymer sheet stock, and the unwinding device, coater section,
The following processing was performed using the manufacturing apparatus which has a heat drying zone, a laminating roll, a high pressure mercury lamp, and a winding device. First, 100 parts by weight of an isocyanuric acid EO-modified triacrylate (M-315 manufactured by Toagosei) having a molecular weight of 400 as an ultraviolet curable resin composition, 300 parts by weight of butyl acetate, 100 parts by weight of cellosolve acetate, 2 parts by weight of benzoin ethyl ether. Was stirred and dissolved at 50 ° C. to form a uniform solution, which was applied with a gravure roll coater in the coater section to a film thickness of 5 μm before drying, and 100
The solvent was removed by heating at 0 ° C for 5 minutes. After removing the solvent, the ultraviolet curable resin composition was in a paste-like softened state.
Subsequently, when a metal roll having Rmax = 0.07 μm was adhered to the surface and the ultraviolet curable resin composition was cured by being irradiated with ultraviolet rays of 80 w / cm to be peeled off, a part of the ultraviolet curable resin composition was detected. The transfer from the polymer sheet to the roll failed to transfer the smooth surface accurately.

Comparative Example 2 100 parts by weight of urethane acrylate having a molecular weight of about 4000 (UN9000H manufactured by Negami Kogyo Co., Ltd.) as an ultraviolet curable resin composition, and 30 parts of butyl acetate.
As in Comparative Example 1, except that 0 part by weight, 100 parts by weight of cellosolve acetate, and 2 parts by weight of benzoin ethyl ether were used, a roll provided with a smooth surface was brought into close contact with 80 w / c.
The ultraviolet curable resin composition was cured by irradiating ultraviolet rays of m to be peeled off. Although there was no problem in the transfer of the smooth surface, when a liquid crystal display device was manufactured in the same manner as in Example 1, display unevenness due to an abnormal cell gap occurred.

[0017]

As described above, according to the method of the present invention, it is possible to easily prepare a display element substrate for a liquid crystal display device or the like, which has conventionally required many steps. In addition, it is possible to solve the problems that the resin is transferred to the conventional metal roll and the rigidity of the substrate is insufficient to cause the spacer to sneak into the substrate, which is extremely useful in the electronics industry.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G09F 9/30 310 G09F 9/30 310 9/35 9/35 // C08L 101: 00 C08L 101: 00 F Term (reference) 2H090 JB03 JD14 KA08 MB01 4F073 AA10 AA14 BA06 BA19 BA23 BA26 BA31 BA32 BA34 BB01 CA01 CA45 FA03 GA03 GA11 4J027 AA08 AB01 AC06 AC09 AE01 AG01 AG25 AJ01 BA24 CA26 CA04 A05 CA4 CA04 CA05 CA13 CA14 CA21 CA36 CA14 CA21 CA36 CA14 CA21 CA21 CA36 CA10 AA55 BA43 EB10

Claims (9)

[Claims] 1. A UV curable resin composition comprising an acrylate monomer and a high molecular weight acrylate as a main component is laminated on a base film, and the UV curable resin composition has a maximum surface roughness (Rmax) in a softened state. Is Rm
A smooth surface of ax ≦ 0.1μ is brought into close contact and irradiated with ultraviolet rays,
A plastic substrate for a display element, which is obtained by transferring and molding a smooth surface and having a total light transmittance of 80% or more. 2. The high molecular weight acrylate has a molecular weight of 2
The plastic substrate for a display device according to claim 1, wherein the plastic substrate is 000 or more. 3. The plastic substrate for a display device according to claim 1, wherein the acrylate monomer is isocyanuric acid EO-modified triacrylate. 4. The compounding ratio of the high molecular weight acrylate in the ultraviolet curable resin composition is 5% to 50%.
3. The plastic substrate for a display device according to any one of 3 to 3. 5. The plastic substrate for a display device according to claim 1, wherein the ultraviolet curable resin composition has excellent releasability from a metal after the effect. 6. The display element according to claim 1, wherein the ultraviolet curable resin composition has a dynamic storage elastic modulus of 10 ³ MPa or more at a temperature of 200 ° C. or less. Plastic substrate. 7. The surface having the smooth surface is provided on the cell inner surface side of the liquid crystal display device.
7. A plastic substrate for a display element according to any one of 6 to 6. 8. The plastic substrate for a display device according to claim 1, wherein the glass transition temperature of the base film is 160 ° C. or higher. 9. A liquid crystal display device using the plastic substrate for a display element according to claim 1.