JPH07199164A - Surface treatment of plastic film substrate for liquid crystal display element - Google Patents

Abstract

PURPOSE:To make the gap of a spacing for sealing liquid crystals uniform and to obviate generation of visible defects by confining the height of projections on the surface of a plastic film substrate to a prescribed height or below in the method for surface treatment of the plastic film substrate for a liquid crystal display element comprising treating the surfaces of plastic film substrates on which transparent conductive films are formed and which are sealed with liquid crystals in the spacing formed by the transparent conductive films facing each other. CONSTITUTION:The plastic substrates 11 on which the transparent conductive films are formed and which are sealed with the liquid crystal injected into the spacing formed by facing the surfaces each other are held by glass plates 12 having smooth surfaces. A stainless steel plate 14 on which a weight 13 is placed is placed on these glass plates 12 and the assembly is held in this state for 10 minutes in an oven kept at 120 deg.C, by which the projections on the surfaces of the substrates 1 are press welded under heating and are made into the prescribed height or below. The temp. of the oven 23 is below the thermal deformation temp. of the substrates 11 and the Snoop hardness of the glass plates 12 is about 500.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment method for a plastic film substrate for a liquid crystal display device, and more specifically, a transparent conductive film is formed on the surface and liquid crystal is sealed in a gap facing the transparent conductive film. The present invention relates to a surface treatment method for a plastic film substrate for a liquid crystal display device.

[0002]

2. Description of the Related Art Conventionally, a liquid crystal display element uses a substrate having a transparent conductive film patterned on its surface, and liquid crystal is injected and sealed in a gap facing the substrate to apply a driving voltage of the liquid crystal to the transparent conductive film. By doing so, a predetermined display is performed, and a glass substrate was used as the substrate, but in recent years, a plastic film substrate that can be easily processed by punching or the like is widely used instead of the glass substrate. .

[0003]

However, such a conventional plastic film substrate has fine protrusions on its surface. When a liquid crystal display device is manufactured using this substrate, the substrate facing the protrusion having a predetermined height or more is pushed by the protrusion and the gap d between the substrates for sealing the liquid crystal becomes wide. Therefore, Δn
There is a problem that d (Δn: optical anisotropy of liquid crystal, d: layer thickness of liquid crystal) becomes large as compared with other portions, and a visual defect in which the color of the portion is different from that of other portions occurs. .

Therefore, according to the present invention, the height of the protrusions on the surface of the plastic film substrate is set to be equal to or less than a predetermined height so that the gaps for sealing the liquid crystal are made uniform and the occurrence of visual defects is eliminated. To aim.

[0005]

In order to achieve the above object, the invention according to claim 1 forms a transparent conductive film on the surface, and the transparent conductive films are opposed to each other with a predetermined gap, and a liquid crystal is filled in the gap. A surface treatment method for a plastic film substrate for a liquid crystal display device for treating a surface of a plastic film substrate of a liquid crystal display device to be sealed, wherein the plastic film substrate is heated at a predetermined temperature and pressed under a predetermined pressure,
It is characterized in that the projections on the surface of the substrate are heated and pressed to make the projections have a predetermined height or less.

According to a second aspect of the present invention, the plastic film substrate is sandwiched between a pair of smooth plates having a smooth surface having a predetermined hardness, and the substrate is pressed at a predetermined pressure. The invention according to claim 3 is characterized in that the plastic film substrate is passed between a pair of pressure rollers having a smooth surface, and the substrate is clamped at a predetermined pressure.

The invention according to claim 4 has a Knoop hardness of 20.
It is characterized in that 0 or more of the smooth plates are used. The invention according to claim 5 is characterized in that the pressure roller having a Knoop hardness of 200 or more is used.
The invention according to claim 6 is characterized in that the plastic film substrate is heated at a heat deformation temperature of the substrate or lower.

The invention according to claim 7 is characterized in that the plastic film substrate is heated and pressed before the transparent conductive film is formed on the surface. The invention according to claim 8 is characterized in that the plastic film substrate is subjected to water absorption treatment and then heated and pressure-welded. According to a ninth aspect of the present invention, the surface of a plastic film substrate of a liquid crystal display device is formed in which a transparent conductive film is formed on the surface, the transparent conductive films are opposed to each other through a predetermined gap, and liquid crystal is sealed in the gap. A method for treating a surface of a plastic film substrate for a liquid crystal display device, which comprises polishing the surface of the substrate so that the protrusions on the surface are not more than a predetermined height before forming a transparent conductive film on the plastic film substrate. It is characterized by.

[0009]

According to the first aspect of the present invention, the plastic film substrate is heated at a predetermined temperature and pressed at a predetermined pressure, and the projection on the surface of the substrate is heated and pressed so that the projection has a predetermined height or less. Therefore, when the substrates are opposed to each other through the predetermined gap, there is no protrusion that pushes the opposed substrate, and the gaps for sealing the liquid crystal are made uniform.

According to the second aspect of the present invention, the plastic film substrate is sandwiched by a pair of smooth plates having a smooth surface having a predetermined hardness and is sandwiched by a predetermined pressure. Therefore, the pressure sandwiched by the smooth plate is applied to the projections on the surface without affecting the surface of the substrate other than the projections, and the projections are heated and pressed to a predetermined height or less. According to the third aspect of the invention, the plastic film substrate passes between the pair of pressure rollers having a smooth surface, and is nipped by the pressure rollers at a predetermined pressure to be heated and pressed against each other. Therefore, the protrusions on the surface of the substrate where the pressure is applied by the pressure roller are heated and pressed to a predetermined height or less.

According to the fourth aspect of the present invention, the plastic film substrate is sandwiched between the smooth plates having a Knoop hardness of 200 or more and heated and pressure-welded. Here, a surface having a Knoop hardness of 200 or more is required in order to make the height of the protrusions on the surface of the substrate below a predetermined value. Therefore, the protrusions on the surface of the substrate, which are sandwiched by the smooth plate and heated and brought into pressure contact with each other, are surely made to have a predetermined height or less.

According to the fifth aspect of the invention, the plastic film substrate is nipped by a pressure roller having a Knoop hardness of 200 or more and heated and pressure-contacted. Here, a surface having a Knoop hardness of 200 or more is required in order to make the height of the protrusions on the surface of the substrate below a predetermined value. Therefore, the protrusions on the surface of the substrate, which are sandwiched by the pressure roller and heated and brought into pressure contact with each other, are surely made to have a predetermined height or less.

According to the sixth aspect of the present invention, the plastic film substrate is heated and pressure-welded at a temperature not higher than its thermal deformation temperature. Therefore, the projections on the surface are heated and pressed into contact with each other to a predetermined height or less without thinning the substrate or causing undulations on the surface of the substrate. In the invention according to claim 7, before forming the transparent conductive film on the surface, the plastic film substrate is heated and pressure-welded. Therefore, the substrate can be heated and pressure-contacted without considering the influence on the transparent conductive film, and the height of the protrusion can be further reduced. Further, since the transparent conductive film is not heated, its physical properties do not change.

According to the present invention, the plastic film substrate is subjected to water absorption treatment and then heated and pressure-welded.
Therefore, the protrusions on the surface of the substrate are easily deformed and then heated and pressure-welded to lower the height. In the invention according to claim 9, the surface of the transparent conductive film is polished before the transparent conductive film is formed on the plastic film substrate so that the projections on the surface have a predetermined height or less. Therefore, after the transparent conductive film is formed on the polished substrate surface, when the substrates are opposed to each other through a predetermined gap, there is no protrusion that pushes the opposing substrate, and the gaps for sealing the liquid crystal are made uniform. . Moreover, since the transparent conductive film is not heated, the physical properties do not change.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a side view showing an example of a member used when carrying out a first embodiment of a surface treatment method for a plastic film substrate for a liquid crystal display element according to the present invention. The present embodiment corresponds to the invention described in any one of claims 1, 2, 4, and 6.

In the figure, reference numeral 11 denotes a plastic film substrate, and the plastic film substrate 11 (hereinafter, also simply referred to as substrate 11) is a plastic film having a thickness of 160 μm cut out into a size of 300 mm □. A transparent conductive film is formed on the surface in a predetermined pattern. This substrate 11 is sandwiched between a pair of glass plates 12 (smooth plates) having a smooth surface with a thickness of 5 mm, a surface roughness of about 30 nm, and a size of 350 mm □.
5mm thick and size 3 with a 30kg weight 13 on top
A 50 mm square stainless steel plate 14 is placed and heated in an oven (not shown) maintained at 120 ° C., which is a temperature not higher than the heat distortion temperature of the plastic film, for 10 minutes while being pressed. As the heating temperature of the oven, if the temperature is higher than the heat deformation temperature, the substrate 11 becomes thin, or deformation such as waviness occurs on the surface, so it is necessary to set the temperature below the heat deformation temperature, and as a pressure applied by the weight 13. Needs to be kept at a pressure that does not cause cracks in the transparent conductive film formed on the surface of the substrate 11.

The substrate 11 is made of T by a known method.
Used as a substrate for N-type reflective liquid crystal display elements,
Although detailed description is omitted, a liquid crystal driven by applying a drive voltage to the transparent conductive film is attached to the substrate formed in the same manner with a sealant so that the transparent conductive film faces each other through a predetermined gap. It is injected and sealed in the gap to form the liquid crystal display element.

Here, in the liquid crystal display element, when visually evaluated, visual defects (color unevenness) having a color different from that of a normal portion may occur. Therefore, a plurality of minute fine lines are formed on the surface on which the transparent conductive film is formed. When the unprocessed substrate 11 having protrusions is used for the production, similarly, visual defects are recognized at a plurality of locations, and the liquid crystal display element is disassembled to determine the height of the protrusions on the surface corresponding to the visual defect occurrence location and other locations. When measured with a stylus type step meter,
Since the height of the protrusion is about 0.5 to 15 μm and the height of the protrusion at the place where the visual defect occurs is 2.5 μm or more, the visual defect occurs if the height of the protrusion is less than 2.5 μm. It turns out that you can get rid of.

Next, the operation will be described together with the work procedure.
First, a substrate 11 having a transparent conductive film formed on its surface is prepared, the substrate 11 is sandwiched between glass plates 12, and the glass plate
A stainless steel plate 14 and a weight 13 are placed on 12 and placed in the oven at a temperature of 120 ° C. in a pressurized state, left for 10 minutes, and then taken out.

At this time, the glass substrate 12, the weight 13, and the stainless steel plate 14 are added to the substrate 11 while being heated to 120 ° C. which is lower than the heat distortion temperature of the plastic film in the oven. And is pressed by the glass plate 12, and the surface of the glass plate 12 is pressed. Since the surface of the glass plate 12 is smooth, the projections are pressed against the surfaces of the substrate 11 other than the projections without applying pressure.

Before performing this surface treatment, the height of the protrusions on the surface of the substrate 11 is measured with the stylus type step gauge, the protrusions of the substrate 11 are heated and pressed, and then taken out and the height of the protrusions is again measured. Was measured, the number of protrusions, which had a height of 12 μm before the treatment, was reduced to 2 μm. In addition, the substrate 11 is not pressure-welded at portions other than the protrusions and the heating temperature is the temperature not higher than the thermal deformation temperature of the plastic film, so that the thickness becomes thin, and the occurrence of undulations on its surface is not recognized, No difference was observed in the surface properties other than the protrusions. Furthermore, when the liquid crystal display element is manufactured using the substrate 11 after the surface treatment, there is no protrusion that pushes the opposing substrate 11 through the gap in which the liquid crystal is sealed, and the gap is made uniform. No visual defects were observed.

Further, instead of the glass plates 12 sandwiching the substrate 11,
It is sandwiched between a pair of aluminum plates (not shown) having a smooth surface with a thickness of 2 mm and a size of 350 mm □, and the stainless plate 14 and the weight 13 are placed on the aluminum plate and similarly applied. The temperature remains 12 when pressed.
When the liquid crystal display element was manufactured by putting it in the oven at 0 ° C. for 10 minutes and then taking it out, a visual defect due to the protrusion was observed. Therefore, since the Knoop hardness of the aluminum plate is about 50, when a similar test was performed using a mild steel material having a Knoop hardness of about 200 and a thickness of 2 mm, no visual defect was observed. From this, it can be seen that in order to obtain the effect of deforming the protrusions on the surface of the substrate 11 to be less than the predetermined height, a surface having a Knoop hardness of about 200 or more is required as a material for pressing, and the Knoop of the glass plate 12 is required. A hardness of about 500 is sufficient.

As described above, according to this embodiment, since the Knoop hardness of the glass plate 12 that is heated and pressed against the substrate 11 is 200 or more, the protrusions on the surface of the substrate 11 can be surely set to a predetermined height or less. it can. Further, since the glass plate 12 has a smooth flat surface, no pressure is applied to the surface of the substrate 11 in the extra portions other than the protrusions, and the surface of the substrate 11 other than the protrusions is not deformed. Furthermore, since the heating temperature is set to be equal to or lower than the heat deformation temperature of the plastic film, the substrate 11 does not become thin and undulate.

When the liquid crystal display element is manufactured using this substrate 11, since the protrusions on the surface of the substrate 11 are set to a predetermined height or less, the gaps for injecting and sealing the liquid crystal are made uniform. Therefore, visual defects do not occur.
In this embodiment, the substrate 11 is pressure-contacted by placing the weight 13, but not limited to the weight 13, an air bag or the like that applies pressure using the pressure of gas such as air may be used. Further, although the glass plate 12 is used to clamp the substrate 11, it is needless to say that it is possible to use a glass plate having a Knoop hardness of about 200 or more and no foreign matter adheres thereto.

As a first other mode of the present embodiment, a substrate 11 before forming a transparent conductive film on the surface is prepared, the substrate 11 is sandwiched between glass plates 12, and the glass plate
Place the stainless steel plate 14 and the weight 13 on 12 and put them in the oven at a temperature of 120 ° C. in the same pressurized state for 10 minutes and then take them out and transparent conductive material on one surface of the substrate 11. The film is formed by a known sputtering method. In this embodiment, the substrate 11 before the transparent conductive film is formed
The protrusions on the surface are made to have a predetermined height or less, and then a transparent conductive film is formed on the surface of the substrate 11. Therefore, the protrusions of the substrate 11 are set to a predetermined height or less without heating and pressing the transparent conductive film. Therefore, the substrate 11 can be heated and pressure-contacted without considering the transparent conductive film, and the protrusion on the surface of the substrate 11 can be further lowered. In addition, the physical properties of the transparent conductive film (for example, light transmittance, conductivity, and etching property)
Does not change. Then, when the liquid crystal display element was manufactured using this substrate 11, no visual defect was observed. It should be noted that the other aspects are defined in claims 1, 2, 4,
It corresponds to the invention described in either 6 or 7.

As a second other mode of this embodiment, the temperature of the substrate 11 is set to 25 ° C. before the substrate 11 is heated and pressed.
After performing a water absorption treatment of leaving it for 30 minutes in a constant temperature and high humidity tank maintained at a humidity of 90%, the substrate 11 is sandwiched between glass plates 12,
A stainless steel plate 14 and a weight 13 are placed on the glass plate 12, and the glass plate 12 is placed in the oven at a temperature of 120 ° C. and left for 10 minutes in the same pressurized state. In this mode, the substrate 11 can be easily deformed by absorbing water, and the projections on the surface of the substrate 11 can be easily deformed by absorbing water, and the height thereof can be lowered by heating and pressure contact. Then, before performing this surface treatment, the height of the protrusions on the surface of the substrate 11 is measured with the stylus type step gauge, and after the substrate 11 is subjected to water absorption treatment and heated and pressure-contacted, it is taken out and the height of the protrusions is again measured. Was measured, the number of protrusions having a height of 12 μm before the treatment was reduced to 1.5 μm. It should be noted that this other aspect corresponds to the invention described in any one of claims 1, 2, 4, 6, or 8.

Further, as a third other mode of this embodiment, a polishing machine used for polishing the surface of a glass substrate for a liquid crystal display device by preparing a substrate 11 before forming a transparent conductive film on the surface thereof ( Although not shown, for example, after polishing with a Speed Fam polishing machine SP-800),
After the substrate 11 is washed and dried, a transparent conductive film is formed on the polished surface by a known sputtering method. In this aspect,
The protrusions on the surface of the substrate 11 before forming the transparent conductive film are polished to a predetermined height or less, and then the transparent conductive film is formed on the surface of the substrate 11. Therefore, the protrusions of the substrate 11 are set to a predetermined height or less without heating and pressing the transparent conductive film. Therefore, the physical properties of the transparent conductive film are not changed. Then, the protrusion on the surface of the substrate 11 before and after polishing was measured by the stylus type step gauge, and the height was about 10 μm before polishing.
The number of protrusions was about 1 μm. Further, after cleaning and drying the substrate 11 after polishing, a transparent conductive film was formed on the polishing surface by a known sputtering method to produce the liquid crystal display element, and there was no protrusion that pushes the opposing substrate 11,
It was possible to make the gaps for injecting and sealing the liquid crystal uniform, and no visual defects were observed. The other aspect corresponds to the invention of claim 9.

Next, FIG. 2 is a side view showing a schematic overall construction of an example of an apparatus used for carrying out the second embodiment of the surface treatment method for a plastic film substrate for a liquid crystal display element according to the present invention. In this embodiment, the claims 1, 3, 5,
Alternatively, it corresponds to the invention described in any one of 6. In the figure, reference numeral 21 denotes a plastic film substrate, and the plastic film substrate 21 (hereinafter, also simply referred to as the substrate 21) has the transparent conductive film formed on the surface thereof, and has a thickness of 160 μm wound in a roll shape on a substrate roll 22, The substrate 21 is a plastic film having a width of 330 mm. The substrate 21 is pulled out from the substrate roll 22 and passes through the oven 23, and then the substrate take-up roller 24
To be wound up. The substrate 21 has a plurality of protrusions on the surface of the substrate 21 in a state that the substrate 21 is still wound on the substrate roll 22, which become visual defects when the liquid crystal display element is manufactured.

The substrate 21 enters the oven 23, which is maintained at 120 ° C., which is lower than the heat distortion temperature of the plastic film, through the opening 23a and guides it on the plurality of transport rollers 25 at a transport speed of 1 mm / min. And a pair of ceramic pressure rollers 26 (Knoop hardness = about 200) which are arranged between the transport rollers 25 and have a smooth surface.
In (0), the transparent conductive film on the surface is pinched with a pressure that does not cause cracks and is carried out from the opening 23b.

Next, the operation will be described together with the work procedure.
First, a substrate roll 22 in which a plastic film having a transparent conductive film formed on the surface thereof is wound in a roll shape is prepared, and the substrate 21 is pulled out from the substrate roll 22 and guided to a conveyance roller 25 in an oven 23 and applied. The substrate take-up roller 24 is engaged with the pressure roller 26 between the pressure roller 26 and the pressure roller 26. Next, the substrate 21 is heated to 120 ° C. in the oven 23, conveyed while being pinched by the pressure roller 26 at a speed of 1 mm / min, sequentially drawn out from the substrate roll 22 and passed through the oven 23 to take up the substrate winding roller. Take up to 24.

At this time, the substrate 21 is pressed and pressed by the pressure roller 26, and is heated to 120 ° C. in the oven 23, and the projection on the surface of the substrate 21 pressed by the pressure roller 26 is heated and pressed. Therefore, the protrusions on the surface of the substrate 21 are made to have a predetermined height. Then, the substrate 21 was cut into a size of 300 mm □ to manufacture the liquid crystal display element, and no visual defect was recognized.

As described above, according to this embodiment, the substrate 21 is heated in the oven 23 at a temperature not higher than the heat deformation temperature, and is pressed at a predetermined pressure by a pressure roller 26 having a smooth flat surface and a Knoop hardness of 200 or more. Since the heating and pressing are performed, the same effects as those of the above-described embodiment can be obtained, and the protrusions on the surface of the substrate 21 can be surely made to have a predetermined height or less. Further, the substrate 21 is not deformed, and the transparent conductive film is not cracked.

Further, since the substrate 21 is pulled out from the substrate roll 22 and subjected to the surface treatment, it can be continuously heated and pressed before being cut out. In this embodiment, the pressure roller 26 made of ceramics is used to clamp the substrate 21. However, the pressure roller 26 is not limited to ceramics, and a Knoop hardness of about 200 or more that does not allow foreign matter to adhere may be used. However, the use of metal such as stainless steel is not preferable because conductive foreign matter may adhere to the surface of the substrate 21. Although the substrate 21 is pulled out from the substrate roll 22 for surface treatment,
After being cut into a predetermined size, it may be placed in the oven 23 and pinched by the pressure roller 26. Further, although the substrate 21 on which the transparent conductive film is formed is used, a substrate before forming the transparent conductive film may be prepared, placed in the oven 23, and sequentially pressed by the pressure roller 26. Needless to say.

[0034]

According to the first aspect of the present invention, since the plastic film substrate is heated at a predetermined temperature and pressed at a predetermined pressure so that the protrusions on the surface of the substrate have a height not more than a predetermined height, the substrate is placed through a predetermined gap. When facing each other, it is possible to eliminate the protrusion that pushes the facing substrate and make the gap of the liquid crystal sealing uniform, thereby eliminating the visual defect of the liquid crystal display element.

According to the second aspect of the present invention, since the plastic film substrate is sandwiched between a pair of smooth plates having a smooth surface having a predetermined hardness and is clamped with a predetermined pressure, the surface of the substrate other than the protrusion is affected. It is possible to apply the pressure that the smooth plate presses to the protrusions without heating, and to heat and pressure the protrusions, and only the protrusions can be deformed to a predetermined height or less. According to the third aspect of the present invention, the plastic film substrate is passed between the pair of pressure rollers having a smooth surface, and the pressure rollers squeeze at a predetermined pressure. The protrusions on the surface of the substrate can be heated and pressed to have a height not higher than a predetermined height. Further, since the pressure roller pinches the substrate at the passing position, the rolled plastic film can be sequentially unwound to pass between the pressure rolls, and the rolled plastic film can be cut out. Can be surface treated without.

According to the invention as set forth in claim 4, since the smoothing plate having a Knoop hardness of 200 or more is pressed against the plastic film substrate for heating and pressure contact, the protrusions on the surface of the substrate can be reliably made to have a predetermined height or less. . According to the invention of claim 5, the plastic film substrate has a Knoop hardness of 200.
Since the above-mentioned pressure rollers squeeze and heat-contact each other, the protrusions on the surface of the substrate can be reliably made to have a predetermined height or less.

According to the sixth aspect of the present invention, the plastic film substrate is heated and pressure-bonded at a temperature not higher than its heat deformation temperature, so that the protrusions on the surface can be formed without thinning the substrate or generating undulations on the substrate surface. It can be heated and pressed to a predetermined height or less. According to the invention of claim 7,
Since the plastic film substrate is heat-pressed before forming the transparent conductive film on the surface, the substrate can be heat-pressed without considering the influence on the transparent conductive film, and the height of the protrusion can be made lower. it can. Further, since the transparent conductive film is not heated, its physical properties do not change.

According to the invention described in claim 8, since the plastic film substrate is subjected to water absorption treatment and then heated and pressure-contacted,
The protrusions on the surface of the substrate can be easily deformed, and the height can be further reduced. According to the invention of claim 9, before the transparent conductive film is formed on the plastic film substrate, the surface thereof is polished so that the projections on the surface have a predetermined height or less, so that the transparent conductive film is formed on the polished substrate surface. After that, when the substrates are made to face each other with a predetermined gap, there is no protrusion that pushes the opposite substrate, the gaps for sealing the liquid crystal can be made uniform, and visual defects of the liquid crystal display element can be eliminated. it can. Further, since the transparent conductive film is not heated, its physical properties do not change.

[Brief description of drawings]

FIG. 1 is a side view showing an example of a member used for carrying out a first embodiment of a surface treatment method for a plastic film substrate for a liquid crystal display element according to the present invention.

FIG. 2 is a side view showing a schematic overall configuration of an example of an apparatus used for carrying out a second embodiment of the surface treatment method for a plastic film substrate for a liquid crystal display element according to the present invention.

[Explanation of symbols]

 11, 21 Plastic film substrate 12 Glass plate (smooth plate) 23 Oven 26 Pressure roller

Claims (9)

[Claims] 1. A liquid crystal display device for treating the surface of a plastic film substrate of a liquid crystal display device, wherein a transparent conductive film is formed on a surface of the liquid crystal display device, and the transparent conductive film is opposed to the surface of the plastic film substrate through a predetermined gap. A method for surface treatment of a plastic film substrate for use in heating, wherein the plastic film substrate is heated at a predetermined temperature and pressed at a predetermined pressure, and a protrusion on the surface of the substrate is heated and pressure-contacted so that the protrusion has a predetermined height or less. A method for surface treatment of a plastic film substrate for a liquid crystal display device, which is characterized by the above. 2. The plastic for a liquid crystal display device according to claim 1, wherein the plastic film substrate is sandwiched between a pair of smooth plates having a smooth surface having a predetermined hardness, and the substrate is clamped at a predetermined pressure. Surface treatment method for film substrate. 3. The liquid crystal display device according to claim 1, wherein the plastic film substrate is passed between a pair of pressure rollers having a smooth surface, and the substrate is clamped at a predetermined pressure. Surface treatment method for plastic film substrates. 4. The surface treatment method for a plastic film substrate for a liquid crystal display element according to claim 2, wherein the smooth plate having a Knoop hardness of 200 or more is used. 5. The method for surface treatment of a plastic film substrate for a liquid crystal display device according to claim 3, wherein the pressure roller having a Knoop hardness of 200 or more is used. 6. The plastic film substrate is heated at a temperature equal to or lower than the thermal deformation temperature of the substrate.
A method for treating the surface of a plastic film substrate for a liquid crystal display element as described above. 7. The surface treatment method for a plastic film substrate for a liquid crystal display device according to claim 1, wherein the plastic film substrate is heated and pressed before the transparent conductive film is formed on the surface. 8. The plastic film substrate is subjected to water absorption treatment and then heated and pressure-bonded.
A method for treating the surface of a plastic film substrate for a liquid crystal display element as described above. 9. A liquid crystal display element for treating the surface of a plastic film substrate of a liquid crystal display element, wherein a transparent conductive film is formed on the surface, the transparent conductive film is opposed via a predetermined gap, and liquid crystal is sealed in the gap. A method of treating a surface of a plastic film substrate for use, comprising: polishing the surface of the substrate to form a protrusion on the surface to a predetermined height or less before forming a transparent conductive film on the plastic film substrate. Method for surface treatment of plastic film substrate for liquid crystal display device.