TW201438823A - Method for rubbing process - Google Patents

Abstract

The purpose of the disclosure is to provide a method for rubbing process which may greatly suppress bright defect. The method for rubbing process includes: offline dust removing step, in which a brush roller (102) vibrates side to side while being rotated in contact with a rubbing roller (72) disposed with a rubbing fabric (90), so as to remove dust attached on the rubbing fabric (90); and alignment film forming step, in which a substrate having an alignment forming material layer travels continuously while the rubbing roller (72) dust-removed in the offline dust removing step is used to form the alignment film.

Description

Friction treatment method

The present invention relates to a rubbing treatment method for forming an alignment film using a rubbing roller, and more particularly to a rubbing treatment method for rubbing a surface of an alignment film forming material layer when manufacturing an optical compensation film of a liquid crystal display device .

In the liquid crystal display device, an optical compensation film for expanding the viewing angle is used as a member for a polarizing plate. In general, the optical compensation film is produced by applying a coating liquid for alignment to a surface of a flexible flexible ribbon-shaped flexible support (hereinafter also referred to as "web"). After the formation of the alignment film forming material layer after drying, the surface is subjected to a rubbing treatment to form an alignment film. Further, the liquid crystal coating liquid is applied onto the alignment film and dried to form a liquid crystal layer, which is then cured.

The rubbing treatment is a representative alignment treatment method of liquid crystal molecules, and is performed by forming an alignment film forming material layer on the surface of the web, and rotating the rubbing roller wound with the rubbing fabric material at a high speed to the alignment film. The surface forming the material layer is rubbed.

In recent years, in the case of a liquid crystal display device, the size and brightness of the device have increased. Progress has been made and it is required to reduce manufacturing costs. In response to this, the polarizing plate which is a member of the liquid crystal display device is required to have a large size, a high function, and an improved quality. Accordingly, the optical compensation film is also widened and elongated. In addition, in particular, the brightness of the liquid crystal display device is increased, and the brightness of the liquid crystal display device is reduced, so that the size of the bright spot that affects the deterioration of the display quality of the liquid crystal display device is reduced. Therefore, it is required to remove minute dust (dust removal) which causes a bright spot.

Therefore, Patent Document 1 proposes a friction treatment method capable of improving the productivity by efficiently removing dust generated in the rubbing treatment and realizing the life of the friction roller.

[Prior Art Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2011-123120

However, even if the rubbing treatment is performed as in Patent Document 1, it is difficult to prevent the bright spot defect.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a friction processing method capable of greatly suppressing bright spot defects.

In order to achieve the object, the present invention provides a rubbing treatment method comprising: an off-line dust removing step of rotating a brush roller to the left and right sides while rotating to contact a rubbing roller having a rubbing cloth on the outer periphery thereof, thereby Removing the dust adhering to the rubbing cloth; and the step of forming the alignment film to have an alignment film shape on one side The substrate of the material layer is continuously moved, and an aligning film is formed on one side using a rubbing roller which has been removed in the offline dust removing step.

According to the present invention, in the off-line state, the brush roller is rotated in contact with the friction roller having the rubbing cloth on the outer circumference while being vibrated on the left and right (roll width direction), thereby removing dust adhering to the rubbing cloth, and is online. In this state, the alignment film is formed using the rubbing roller, whereby the bright spot defect can be greatly suppressed. Further, by vibrating the brush roller to the right and left, it is possible to suppress the deterioration of the performance of the rubbing cloth due to the dust adhering to the brush roller.

In the present invention, it is preferred that the substrate is a belt-shaped flexible support.

Further, in the invention, it is preferable that the rotation direction of the brush roller with respect to the rubbing roller is the same as the rotation direction of the alignment film formed by using the rubbing roller. As long as the direction of rotation of the brush roller with respect to the rubbing roller is the same as the direction of rotation in which the alignment film is formed using the rubbing roller, the cloth pattern can be made uniform.

Further, in the invention, it is preferable that the alignment film forming material layer is formed by modifying polyvinyl alcohol as a main component. In particular, in an optical film in which a modified PVA (Polyvinyl Alcohol) is applied as an alignment film, the alignment film material (modified PVA) is negatively charged, and is suitable as a raw material of the rubbing cloth. Since the hydrophobic synthetic fiber is positively charged, the dust caused by the rubbing treatment due to the rubbing treatment tends to adhere to the rubbing cloth under electrostatic interaction, and therefore the present invention is particularly effective.

According to the rubbing treatment method of the present invention, bright spot defects can be greatly suppressed.

10‧‧‧Manufacture line of optical compensation film

11, 11A, 11B‧‧‧ rod coating device

15A, 15B‧‧‧Dust Collector

16, 16a‧‧‧

66‧‧‧ delivery machine

67‧‧‧Winding machine

68‧‧‧guide roller

70, 70A, 70B‧‧‧ friction treatment device

71A, 71B‧‧‧Dust Collector

72, 72A, 72B‧‧‧ friction roller

76, 76A, 76B‧‧‧ Drying area

78, 78A, 78B‧‧‧ heating zone

80‧‧‧UV light

81‧‧‧ delivery machine

82‧‧‧Winding machine

84‧‧‧ Roller (inspection device)

84A, 84B‧‧‧ Roller

86, 86A, 86B‧‧‧ support rolls

88‧‧‧Support Roller (Laminator)

88A, 88B‧‧‧ support roller

90‧‧‧Rubber cloth

100‧‧‧Offline dust removal device

102‧‧‧brush (brush roller)

104‧‧‧Exhaust device

108‧‧‧High blowing nozzle device

Θ‧‧‧ blowing angle

FIG. 1 is an explanatory view showing a manufacturing line of an optical compensation film.

Fig. 2 is a view schematically showing the configuration of a friction processing device of the present invention.

Fig. 3 is a view schematically showing a configuration of a part of the friction processing device of the present invention as seen from the front.

Hereinafter, a preferred embodiment of the friction processing method of the present invention will be described with reference to the accompanying drawings.

Fig. 1 is a manufacturing line 10 of an optical compensation film as an example of a rubbing treatment method to which the present invention is applied.

As shown in Fig. 1, a net 16 as a belt-shaped flexible support (for example, a transparent support) is fed from the feeder 66. The net 16 is guided by a guide roller 68 and passed through the dust remover 15A, thereby removing dust adhering to the surface of the net 16. As the dust remover 15A, various types well known can be employed. For example, a configuration may be adopted in which compressed air (nitrogen) electrostatically dusted (nitrogen) is sprayed on the surface of the net 16 to remove dust adhering to the surface of the net 16.

A bar coating device 11A is provided downstream of the net moving direction of the dust remover 15A (hereinafter referred to simply as downstream), and a coating liquid containing a forming material of the alignment film forming material layer is applied onto the net 16. In addition, the coating device is not limited to the bar coating device. Various coating devices such as a gravure coater, a roll coater (transfer roll coater, a reverse roll coater, etc.), a die coater can be employed. ), an extrusion coater, a fountain coater, a curtain coater, a dip coater, a spray coater, or a slip coater Slide hopper and so on.

A drying zone 76A and a heating zone 78A are sequentially disposed downstream of the bar coating apparatus 11A, and an alignment film forming material layer is formed on the mesh 16. After the coating liquid is applied and dried, it is wound up on a coiler 67.

Then, the net 16a on which the alignment film forming material layer is formed is sent out from the feeder 81. The net 16a is guided by the guide roller 68 and sent to the friction processing device 70. The rubbing roller 72A (72B) is provided to perform a rubbing treatment on the alignment film forming material layer. A dust remover 71A (71B) is provided upstream of the rubbing roller 72A (72B) to remove dust adhering to the surface of the net 16a.

The rubbing treatment device 70A (70B) is a device for performing a rubbing treatment on the alignment film forming material layer. In the present example, the rubbing roller 72A and the rubbing roller 72B are formed in two stages. Further, as the friction processing device 70, a one-stage roller configuration may be employed.

The friction processing device 70A (70B) can rotationally drive the friction roller 72A (72B) on which the friction fabric material to be described later is wound around the outer peripheral surface, and controls the rotation speed to be, for example, about 1000 rpm. The shape of the rubbing roller 72A (72B) may be, for example, an outer diameter of 150 mm, and the length is also slightly longer than the width of the net 16a in a state with a rubbing angle. Roll shape. Further, the friction processing device 70A (70B) can be freely rotated on the horizontal surface with respect to the traveling direction of the net 16a so as to be adjustable to an arbitrary friction angle.

The rubbing roller 72 is formed by attaching the rubbing cloth 90 to the cylindrical shaft, and has an outer diameter of 100 mm to 500 mm, preferably 150 mm to 300 mm. Examples of the rubbing cloth 90 include a sheet which can be obtained from a gum, a nylon, a polyester, or the like, a sheet which can be obtained from a nylon fiber, a rayon fiber, or a polyester fiber. (Velvet, etc.), paper, gauze, felt, etc. (refer to Fig. 2).

The rubbing roller 72 is connected to a rotation drive source (not shown) and is controlled to rotate at a predetermined speed (for example, 200 rpm to 600 rpm). Further, it is preferable that the rubbing roller 72 is configured to be capable of controlling the rotational speed within a predetermined range, for example, about 1000 rpm.

A stage 84A (84B) is provided above the rubbing roller 72A (72B), and a backup roll is rotatably mounted on the lower surface of the roll table 84A (84B) via a spring. 86A (86B), support roller 88A (88B). The support roller 86A (86B) and the backup roller 88A (88B) are provided with a mechanism for detecting the tension of the net 16a, so that the tension at the time of friction can be managed.

Further, the backup roller 86A (86B) and the backup roller 88A (88B) can be adjusted up and down, and the roller can be moved up and down to adjust the wrap angle of the mesh 16a with respect to the friction roller 72A (72B).

According to the above configuration, the net 16a is pressed from the upper side by the backup rolls 86A (86B) and 88A (88B), and the rubbing roll 72A that presses the net 16a from the lower side is used. (72B) The surface of the alignment film forming material layer on the surface (lower surface) of the mesh 16a is rubbed to form an alignment film having an alignment property.

The alignment film forming material layer may be transparent and may be aligned by an alignment treatment. Examples of the forming material of the alignment film forming material layer include polymethyl methacrylate, acrylic acid/methacrylic acid copolymer, styrene/maleimide copolymer, (modified) polyvinyl alcohol, poly ( N-methylol acrylamide, styrene/vinyl toluene copolymer, chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimine, vinyl acetate copolymer A compound such as an ethylene/vinyl acetate copolymer, a cellulose carboxycarboxylate, a polyethylene, a polypropylene, a polycarbonate, or the like, and a decane coupling agent. As a preferable example of the polymer, a polymer of polyimine, polystyrene, a styrene derivative, gelatin, (modified) polyvinyl alcohol or a polyvinyl alcohol derivative can be cited. In the material for forming the alignment film forming material layer, the material having a polymerizable group increases the bonding strength with the liquid crystal layer, and therefore is effective, and more preferably a forming material containing modified polyvinyl alcohol as a main component. In the present specification, the main component is a modified polyvinyl alcohol containing 60% by mass or more of the forming material, preferably 80% by mass or more, and more preferably 90% by mass or more.

A dust remover 15B is provided downstream of the friction processing device 70 to remove dust adhering to the surface of the net 16a.

A bar coating device 11B is provided downstream of the dust remover 15B, and a coating liquid containing disc-shaped nematic liquid crystal is applied onto the mesh 16a. As the coating device 11B, similar to the case where the coating liquid containing the forming material of the alignment film forming material layer is applied to the web 16, various coating apparatuses can be used.

Downstream of the bar coating device 11B, a drying zone 76B and a heating zone 78B are sequentially provided, and a liquid crystal layer is formed on the mesh 16a. Further, an ultraviolet lamp 80 is provided downstream of the film, and the liquid crystal is crosslinked by irradiation of ultraviolet rays to form a desired polymer. Then, the inspection is performed by the inspection device 84, and the protective film 88A fed from the laminate machine 88 is laminated on the net 16a, and the web 16a on which the polymer is formed is taken up by the winder 82 provided downstream.

In the present embodiment, the entire manufacturing line 10 of the optical compensation film, in particular, the bar coating device 11A and the bar coating device 11B, can be installed in a clean environment such as a clean room. At this time, the degree of cleanliness is preferably 1000 or less, more preferably 100 or less, still more preferably 10 or less.

2 is a schematic view showing a configuration of the offline dust removing device 100 in the offline dust removing step of the present embodiment, and FIG. 3 is a schematic view showing a part of the offline dust removing device 100 in the offline dust removing step of the present embodiment as seen from the front.

In the present invention, after the optical compensation film is produced, there is an off-line dust removal step of removing dust of the rubbing cloth 90. By removing the dust of the rubbing cloth 90 in the off-line dust removing step, it is possible to prevent dust generated when the alignment film is formed on the optical compensation film manufacturing line 10 (more specifically, during rubbing treatment) from adhering to the alignment film (friction treatment) In the intermediate alignment film forming material layer), a film having a good appearance can be produced.

The off-line dust removal step can be performed using a roll-shaped brush (brush roll) 102 as shown in FIG. The roller-shaped brush 102 is configured to remove dust adhering to the rubbing cloth 90 by contacting the rubbing cloth 90. Preferably, the direction of rotation of the brush roller with respect to the rubbing roller is the same as the direction of rotation of the alignment film formed using the rubbing roller. as long as When the direction of rotation of the alignment film is formed by the rubbing roller (the rotation direction of FIG. 2 is the same), the cloth pattern can be made uniform.

The rubbing roller 72 is connected to a rotation drive source (not shown) and is controlled to rotate at a predetermined speed (for example, 200 rpm to 600 rpm). Further, it is preferable that the rubbing roller 72 is configured to be capable of controlling the rotational speed within a predetermined range, for example, about 1000 rpm.

Further, the brush 102 is also connected to a rotation drive source (not shown) and is controlled to rotate at a predetermined speed. The optimum value of the rotational speed of the brush 102 is 100 rpm to 700 rpm, and when it is 100 rpm or more, it has the effect of dusting off. Moreover, it is easy to remove dust when it is 700 rpm or less.

The optimum value of the overlap of the brush 102 and the rubbing roller 72 (the amount of press of the brush) is 0.5 mm to 1.5 mm. When it is 0.5 mm or more, it has the effect of dusting off, and when it is 1.5 mm or less, the damage of the rubbing cloth is reduced.

The optimum value of the diameter of the roller of the brush 102 is 50 mm to 200 mm, and when it is 50 mm or more, the shaft does not bend during the rotation, and the dust can be uniformly removed in the width direction. Moreover, when it is 200 mm or less, the manufacturing cost of a roll does not raise.

Further, as shown in FIG. 3, in the off-line dust removing device 100 of the present embodiment, the brush 102 vibrates (oscillates) while maintaining the distance from the rubbing cloth 90. Since the brush 102 is oscillated, the contact portion between the brush 102 and the rubbing cloth 90 is not fixed. Therefore, it is possible to suppress the deterioration of the performance of the rubbing cloth due to the dust adhering to the brush roller.

Additionally, it is preferred that the off-line dust removal device 100 has an exhaust device 104. The exhaust device 104 can prevent dust that has been removed by the rubbing step of the rubbing cloth from adhering to the rubbing cloth again, and therefore, an optical compensation film having better quality can be manufactured.

Further, in order to remove dust adhering to the tip end of the brush, it is preferable to provide a high blow nozzle device 108 in the exhaust device 104. When the blowing angle θ is 1° to 45°, the ability to remove dust from the brush 102 is remarkably improved, which is preferable.

In addition, the brush 102 contains a filament, but when the alignment film forming material layer is modified with polyvinyl alcohol as a main component, the polyvinyl alcohol (PVA) fine powder which is an inducing substance of the film bright spot defect is long. The wire is nylon, but it can be removed, but when it is polypropylene or rayon, it is difficult to remove due to the close proximity of the charged sequence.

The optimum length of the filament of the brush 102 is 5 mm to 11 mm. By setting it as 5 mm to 11 mm, the hardness of the filament is optimized, dust is easily removed, and the friction cloth is less likely to be damaged.

Further, the optimum value of the thickness of the filament of the brush 102 is 100 μm to 300 μm. By setting it as 100 μm - 300 μm, the hardness of the filament is optimized, dust is easily removed, and the rubbing cloth is less likely to be damaged.

Next, the operation of the offline dust removing device 100 will be described.

In the off-line dust removing device 100, the dust adhering to the rubbing cloth 90 is removed by bringing the roller-shaped brush 102 that vibrates left and right into contact with the rubbing cloth 90.

Therefore, according to the present embodiment, the friction roller 72 from which the adhered dust has been removed can form a high-quality rubbed alignment film in an on-line state. Therefore, it is possible to provide a high-quality optical compensation film with less bright spot defects.

[Examples]

Long-chain alkyl-modified polyvinyl alcohol (MP-) coated on the side of a long film (mesh) of cellulose triacetate (FUJITAC, manufactured by Fujifilm Co., Ltd., thickness: 40 μm, width: 1500 mm) A 5% by weight aqueous solution of 203, manufactured by Kuraray Co., Ltd., was dried at 90 ° C for 4 minutes. Thus, an alignment film forming material layer having a thickness of 2.0 μm was formed.

The surface of the alignment film forming material layer was subjected to a rubbing treatment using the apparatus of Fig. 1. The web was conveyed at a speed of 20 m (m)/min in the direction of the arrow while pressing the web having the alignment film forming material layer from the upper side by a roll (roll outer diameter: 90 mm, length: 1650 mm). The rubbing roll (outer diameter: 300 mm) which presses the net from the lower side is rotated at a speed of 400 rpm in a direction opposite to the traveling direction of the net, and the rubbing cloth (filt) attached to the cylindrical shaft is brought into contact with each other. Forming a material layer on the alignment film.

For the rubbing rolls, the dust removal treatment was carried out by the methods shown in Experiments 1 to 7 of Table 1. In addition, in the offline dust removal process, the shape of the brush member was of a type of nylon, a length of 8 mm, and a diameter of 180 μm.

In Experiment 1, the dust was removed off-line while oscillating, and then dust was removed (on-line dust removal) while rubbing against the web having the layer of the alignment film forming material. In Experiment 2, the dust blowing amount of the high blowing amount nozzle device was set to 30° to perform dust removal, and otherwise the same conditions as in Experiment 1 were employed. In Experiment 3, the brush rotation direction was reversed, and otherwise the same conditions as in Experiment 1 were set. In experiment 4, one The surface is subjected to off-line dust removal while oscillating, and thereafter, the mesh having the alignment film forming material layer is rubbed without performing on-line dust removal. In Experiment 5, off-line dust removal was performed without shaking, and then dust was removed while rubbing against a web having an alignment film forming material layer. In Experiment 6, dust removal was not performed in the online or offline state. In Experiment 7, dust removal was not performed in an offline state, and dust removal was performed only in an online state.

[Evaluation method]

The number of bright spot defects of the transparent film after the rubbing treatment of Experiments 1 to 7 was evaluated based on the light-emitting frequency of the surface inspection apparatus using a charge coupled device (CCD) camera. The evaluation results are shown in Table 1. In addition, regarding the symbol in the table, the frequency of occurrence of the bright spot when dust removal was not performed in both the online and offline states was 150%, and the evaluation was performed as follows.

6...The quality is very good (the frequency is less than 30%)

5...Excellent quality (production frequency is 30% or more and less than 50%)

4... Within the quality tolerance range (the generation frequency is 50% or more and less than 80%)

3...Quality tolerance limit (generation frequency is 80% or more and less than 100%)

2... poor quality (production frequency is 100% or more and less than 120%)

1...Outside the quality tolerance range (the generation frequency is 120% or more and 150% or less)

In addition, 3 or more is a level of acceptance, and 2 or less is a level of failure.

According to the evaluation results of Experiments 1 to 7 of Table 1, it was found that when the off-line dust removal treatment of the present invention was carried out, a film having a high quality with a small number of bright spots was obtained. In addition, in Experiment 5, the evaluation of the bright spot defect was good, but the distribution of the friction roller in the width direction was poor. Poor alignment.

Further, the rubbing cloth that is not used is the same as that in the case where the rubbing cloth after use is used, and when the rubbing treatment is performed after the offline dust removal, the same effect as when the rubbing cloth after use is used can be obtained.

72‧‧‧ friction roller

90‧‧‧Rubber cloth

100‧‧‧Offline dust removal device

102‧‧‧brush (brush roller)

104‧‧‧Exhaust device

108‧‧‧High blowing nozzle device

Θ‧‧‧ blowing angle

Claims (5)

A rubbing treatment method comprising: an off-line dust removing step of rotating the brush roller to the left and right sides while rotating to contact the rubbing roller provided with the rubbing cloth on the outer side, thereby removing dust adhering to the rubbing cloth; and the alignment In the film formation step, the alignment film is formed by continuously moving the substrate having the alignment film forming material layer while using the rubbing roller which has been removed by the off-line dust removing step. The friction treatment method according to claim 1, wherein the substrate is a belt-shaped flexible support. The rubbing treatment method according to claim 1, wherein a direction of rotation of the brush roller with respect to the rubbing roller is the same as a direction of rotation of the alignment film formed using the rubbing roller. The rubbing treatment method according to the second aspect of the invention, wherein the direction of rotation of the brush roller with respect to the rubbing roller is the same as the direction of rotation of the alignment film formed using the rubbing roller. The rubbing treatment method according to any one of the preceding claims, wherein the alignment film forming material layer is a modified polyvinyl alcohol as a main component.