JP2009294608A - Rubbing cloth material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubbing cloth material capable of manufacturing an optical compensation film nearly free from fluctuation of optical characteristics in a width direction and nearly free from a bright spot generating frequency even when the film is widened and elongated. <P>SOLUTION: In the rubbing cloth material 1 for subjecting an alignment layer to rubbing treatment including a base fabric woven with warp 2 and weft 3, and pile yarn 4 woven to the base fabric woven, the rear face of the base fabric woven has 40 to 70 μm surface roughness Ra. The pile yarn 4 preferably has 3 to 30 g/d average hardness. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rubbing cloth material, and more particularly to an optical compensation film for a liquid crystal display device, and more particularly to a rubbing cloth material used for rubbing treatment of an alignment film of an optical compensation film in which a liquid crystal layer is laminated on an alignment film.

  In recent years, the demand for optical films is increasing. Typical examples of the optical film include films having various functions such as an optical compensation film used as a retardation plate in a liquid crystal cell, an antireflection film, and an antiglare film.

  As a representative method for producing such an optical film, the surface of a belt-like flexible support (hereinafter also referred to as “web”) is subjected to rubbing treatment, and then various coating devices are used on the surface of the web. Then, a coating solution is applied, dried, and then cured to form coating films (functional films) having various compositions.

  This rubbing treatment is a typical method for aligning liquid crystal molecules, and an alignment film is formed on the surface of the web, and the surface of the alignment film is used with a rubbing roller provided with a rubbing cloth material. A method of rubbing in one direction is common.

Various methods have been proposed as a method of rubbing using a cloth material for rubbing, and the following Patent Document 1 has the characteristics of high wear resistance, low charging property, and large alignment regulating force. A manufacturing method of a liquid crystal display device using a rubbing cloth having a pile portion in which fibers are raised is described as a rubbing cloth having a combination. Patent Document 2 describes a rubbing roller that includes a rubbing cloth that is formed by weaving pile yarn on a ground yarn to reduce the display content of a substrate and has a reduced content of fatty acid amide component. Patent Document 3 describes a rubbing material provided with a pile having a concavo-convex shape at the tip in order to reduce an abnormal alignment region caused by insufficient alignment treatment and suppress display defects of a liquid crystal display device. Patent Document 4 describes a rubbing cloth material composed of a ground fabric structure in which warp yarns having different weaving yarn lengths are combined in order to make the alignment state of a liquid crystal panel uniform and achieve image quality improvement as a display device. Yes. Patent Document 5 describes a rubbing cloth including a core made of a conductive material and a composite fiber made of a non-conductive material covering the core in order to suppress generation of static electricity and generation of fine dust and foreign matters. Yes.
JP 2003-156747 A JP 2004-212783 A JP 2004-252341 A JP 2005-308886 A Japanese Patent Laid-Open No. 2007-232938

  However, liquid crystal display devices are required to reduce the manufacturing cost as the size and brightness of the devices increase. Along with this, a polarizing plate, which is a member of a liquid crystal display device, is required to have a large size, high functionality, and improved quality, and to improve productivity. The same applies to optical films such as retardation films and protective films that are members for polarizing plates.

  Improvement in the quality of the optical film can be achieved by reducing defects such as bright spots, and improvement in productivity can be achieved by widening and lengthening the film. In particular, in an optical compensation film in which a liquid crystal layer is laminated on an alignment film, it is important to stabilize the rubbing treatment of the alignment film, and the degree of importance is increased by increasing the width and length of the film.

  However, the rubbing cloth material used in the rubbing process described in Patent Documents 1 to 5 cannot be uniformly rubbed in the width direction due to the widening, and the optical characteristics of the optical compensation film vary in the width direction. There was a problem of being big. Moreover, since the rubbing cloth life is short, there is a problem that it is not possible to cope with the lengthening.

  The present invention has been made in view of such circumstances, and manufactures an optical compensation film with little variation in optical characteristics in the width direction and less occurrence of bright spots even when the film is widened or elongated. A rubbing cloth material that can be provided can be provided.

  According to a first aspect of the present invention, in order to achieve the above object, a rubbing for rubbing the alignment film, comprising a ground fabric composed of warps and wefts, and a pile yarn woven into the fabric. Provided is a rubbing cloth material characterized in that the surface roughness Ra of the back surface of the ground fabric structure is 40 to 70 μm.

  The inventors of the present invention can form a good planar film by setting the surface roughness Ra of the back surface (the surface on which the pile yarn is not formed) of the base fabric structure of the rubbing cloth material within a predetermined range. I found out that I can do it.

  According to claim 1, it is possible to prevent the pile yarn from coming out of the fabric structure by rubbing the alignment layer with the rubbing cloth material having the surface roughness Ra of the back surface of the fabric structure within the above range. . Accordingly, the rubbing performance of the rubbing cloth is less likely to vary in the film width direction to be rubbed, so that it is possible to cope with the widening of the film and the life is extended, and therefore, it is possible to deal with an elongated film.

  In addition, since the number of yarns that come off during the rubbing process can be reduced, no dust is produced, and the surface shape is not deteriorated by the dust, so that a good surface film can be formed.

  A second aspect of the present invention is characterized in that in the first aspect, the pile yarn has an average hardness of 3 to 30 g / d.

  The second aspect defines the average hardness of the pile yarn, which is suitable for obtaining a film having good orientation in the alignment film and having a low occurrence frequency of bright spots. When the average hardness of the pile yarn is lower than the above range, the orientation of the alignment film is deteriorated. On the other hand, if it is higher than the above range, the film is scratched, which is not preferable.

  A third aspect of the present invention is characterized in that, in the first or second aspect, the pile yarn has a fatigue life of 60 times or more in a Gakushin-type friction fastness test defined in JIS L0849.

  In recent years, it has been required to increase the length and width of optical compensation films for polarizing plates from the viewpoint of improving productivity. In order to manufacture continuously, the rubbing cloth cannot be changed during the rubbing process, and the conventional rubbing cloth material cannot perform the rubbing process corresponding to the lengthening.

  According to claim 3, by setting the fatigue life of the pile yarn within the above range, even when used for a long time, the frequency of occurrence of luminance is reduced, and the optical compensation film for a liquid crystal display device for TV applications with strict quality requirements. Can be manufactured continuously.

  A fourth aspect of the present invention is characterized in that, in any one of the first to third aspects, a mutual friction coefficient (yarn / yarn) of the pile yarn is 0.15 to 0.40.

  According to the fourth aspect, by setting the mutual friction coefficient of the pile yarn within the above range, it is possible to obtain good orientation in the alignment film and to obtain a film with less bright spot generation frequency. If the mutual friction coefficient of the pile yarn is lower than the above range, the number of bright spots increases, which is not preferable. On the other hand, if it is higher than the above range, the orientation becomes worse, which is not preferable.

A fifth aspect of the present invention is the optical compensation film according to any one of the first to fourth aspects, wherein the cloth material for rubbing is on an optical compensation film in which a liquid crystal layer is laminated on an alignment film that has been subjected to a rubbing process of 4000 to 600 Nm / m ² . The number of bright spots exceeding 70 μm is 0.5 pieces / m ² or less.

  Since the rubbing cloth material of the present invention has a long service life, the number of bright spots generated on the surface of the film increases even when an optical compensation film is produced by rubbing 4000 m using the rubbing cloth material. Therefore, it is possible to produce a film with a low occurrence frequency of bright spots.

  According to the rubbing cloth material of the present invention, since the service life of the rubbing cloth material can be extended, the film can be made longer. Moreover, since the pile yarn can be prevented from coming off, it is difficult for the rubbing performance in the width direction to vary due to use, and the variation in the optical characteristics of the film is reduced. Therefore, it is possible to manufacture an optical compensation film with a low occurrence frequency of bright spots.

  Hereinafter, the rubbing cloth material of the present invention will be described. FIG. 1 is a partially enlarged perspective view showing a configuration of a rubbing cloth material 1. This rubbing cloth material 1 is formed by weaving pile yarns 4 on a base fabric in which warp yarns 2 of a ground fabric texture and weft yarns 3 of a ground fabric texture are woven in a lattice shape. Of these, a material in which pile yarns 4 are woven into three wefts 3 as a rubbing fabric material 1 shown in FIG. 1 (A) is called a W structure, and a rubbing fabric material 6 shown in FIG. 1 (B). As described above, what is woven into the pile yarn 7 is referred to as a V structure. The W structure and the V structure differ only in how the pile yarns are woven, and the same materials can be used.

  Examples of the base fabric include polyamides such as nylon 6-6 (registered trademark), polyesters such as polyethylene terephthalate, polyolefins such as polyethylene, polyvinyl alcohols, polyvinylidene chloride, polyvinyl chloride, polyacrylonitrile, and acrylamide. , Acrylic fibers such as methacrylamide, synthetic fibers such as poly (vinylidene cyanide), polyfluoroethylene and polyurethane, natural fibers such as silk, cotton, wool, cellulose and cellulose ester, and regenerated fibers (rayon, acetate, etc.) The fiber which combined 1 type, or 2 or more types chosen from among these is mentioned.

  Of these fiber materials, preferably, polyamides such as nylon 6 and nylon 6-6 (registered trademark), acrylics such as polyacrylonitrile, acrylamide and methacrylamide, polyesters such as polyethylene terephthalate, and celluloses as recycled fibers And cellulose ester-based rayon and acetate.

  The warp 2 and the weft 3 of the base fabric are used in a state where, for example, 70 fibers of 1.4 denier are combined to form a filament of about 100 denier. As such warp 2 and weft 3, for example, cupra rayon (Bemberg) filaments manufactured by Asahi Kasei Corporation can be preferably used.

  The pile yarn 4 is required to have a diameter of 1.0 to 2.5 denier. Particularly preferably, the diameter is 1.5 to 2.0 denier. When the diameter of the pile yarn is less than 1.0 denier, the extinction degree is reduced due to insufficient rubbing, the pile yarn is easily worn out, the orientation is insufficient, and problems are likely to occur. On the other hand, when the diameter of the pile yarn exceeds 2.5 deniers, the elasticity of the rubbing cloth material becomes too high, and the alignment film is rubbed too much, and it is not preferable because surface defects are easily caused by generation of fine powder.

The density of the pile yarn 4 is preferably 25000 to 150,000 pieces / cm ² . When the density of the pile yarn is less than 25,000 pieces / cm ^{2, the} degree of extinction is reduced due to insufficient rubbing, and the pile yarn is likely to be worn out and the orientation is insufficient. On the other hand, when the density of the pile yarn exceeds 150,000 yarns / cm ² , the pile yarn is likely to come off or drop off, and it is easy to cause a planar defect due to the generation of fine powder, and the cost increases.

  The material of the pile yarn 4 is preferably rayon filament fiber. As such a pile yarn 4, for example, a rayon filament fiber manufactured by ENKA can be preferably used.

  Further, in the rubbing cloth material, a sealing agent can be used so that the pile yarn 4 does not fall out of the base fabric (warp yarn 2 and weft yarn 3). Examples of the sealant used in the present invention include polyvinyl resin, polyolefin resin, polyurethane resin, polyamide resin, polyester resin, synthetic rubber resin, epoxy resin, phenol resin, acrylic resin not included in these, and the like. , Vinyl acetate resin / emulsion type, vinyl acetate resin / toluene solvent type, or a blend of two or more types, or a copolymer emulsion combining these.

  The rubbing cloth material of the present invention has a surface roughness Ra of 40 to 70 μm on the back surface of the ground fabric structure (the surface on which the pile yarn is not formed). Preferably it is 35-65 micrometers, More preferably, it is 30-60 micrometers. By setting the surface roughness of the back surface of the ground fabric texture within the above range, it is possible to prevent the pile yarn from coming out of the ground fabric texture during the rubbing treatment, and to extend the life of the rubbing fabric. Therefore, the rubbing process can be performed on the elongated film with less occurrence of bright spots. In addition, since the number of pile yarns that come off can be reduced, dust is not generated, and the surface condition can be prevented from being deteriorated by the dust, so that a good surface film can be formed.

  As a method for measuring the surface roughness, it can be measured with an ultra-deep laser microscope.

  The rubbing cloth material of the present invention preferably has the following physical properties.

  The pile yarn preferably has an average hardness of 3 to 30 g / d, more preferably 5 to 25 g / d, and still more preferably 8 to 20 g / d. If the average type of the pile yarn is less than 3 g / d, the degree of extinction may be reduced due to insufficient rubbing, or the orientation may be insufficient. On the other hand, if it is higher than 30 g / d, the number of bright spots increases, and surface defects are likely to occur.

  The average hardness of the pile yarn can be measured with a fiber hardness meter.

  The fatigue life of the pile yarn is preferably 60 times or more, more preferably 80 times or more, more preferably 100 times or more in the Gakushin type friction fastness test defined in JIS L0849. When the fatigue life of the pile yarn is less than 60 times, the wear durability of the pile yarn is inferior, so the number of bright spots increases and the surface defects become worse.

  The fatigue life of the pile yarn can be measured with a Gakushin type friction fastness tester defined in JIS L0849.

  The mutual friction coefficient (yarn / yarn) of the pile yarn is preferably 0.15 to 0.40, more preferably 0.15 to 0.30, still more preferably 0.15 to 0.25. is there. If the mutual friction coefficient of the pile yarn is less than 0.15, the degree of extinction is reduced due to insufficient rubbing, or the orientation is insufficient, and problems are likely to occur. On the other hand, if it is larger than 0.40, the number of bright spots increases, and surface defects are likely to occur.

Since the rubbing cloth material of the present invention can extend the service life, a liquid crystal layer is formed on the alignment film subjected to a rubbing process of 4000 m with a rubbing work amount of 300 to 600 Nm / m ² using the rubbing cloth material of the present invention. The number of bright spots exceeding 70 μm of the optical compensation film laminated with can be 0.5 / m ² or less.

  Examples The present invention is illustrated below by examples and comparative examples, but the present invention is not limited by these examples.

  An optical compensation film was produced under various conditions using the optical film production line 10 shown in FIG.

  In the optical film production line 10 shown in FIG. 2, a long chain alkyl is formed on one side of a long web 16 of triacetylcellulose (Fujitack, manufactured by Fuji Film Co., Ltd., thickness: 100 μm, width: 500 mm). A 5% by weight solution of modified popal (MP-203, manufactured by Kuraray Co., Ltd.) was applied, dried at 90 ° C. for 4 minutes, and then rubbed to form an alignment film-forming resin layer having a thickness of 2.0 μm. Formed. The conveyance speed of the web 16 was 20 m / min.

In the rubbing apparatus 70, the surface of the resin layer was rubbed while the web 16 was continuously conveyed at 20 m / min. In the rubbing process, the number of rotations of the rubbing roller 72 was 300 rpm. The rubbing work amount was 400 Nm / m ² .

  As the rubbing cloth material 1, the rubbing cloth material shown in Table 1 was used. In addition, as a material for the rubbing cloth material, a cupra rayon was used for the base fabric structure, and viscose rayon was used for the pile yarn.

After the rubbing treatment, the weight of the discotic compounds TE-8 (3) and TE-8 (5) was transferred onto the alignment film while continuously transporting the obtained web 16 having the alignment film at 20 m / min. Bar mixture was applied to a mixture of 4: 1 ratio by weight of a photopolymerization initiator (Irgacure 907, manufactured by Nippon Ciba Geigy Co., Ltd.) in an amount of 1% by weight based on the above mixture. In the apparatus 11B, it apply | coated with the application quantity of 5 ml / m < ² >, Then, it let the drying zone 76B and the heating zone 78B pass.

  Air of 0.1 m / second was sent to the drying zone 76B, and the heating zone 78B was adjusted to 130 ° C. The web 16 entered the drying zone 76B 3 seconds after coating, and entered the heating zone 78B after another 3 seconds. The web 16 passed through the heating zone 78B in about 3 minutes.

  Next, the surface of the liquid crystal layer was irradiated with ultraviolet rays by an ultraviolet lamp 80 while the web 16 coated with the alignment film and the liquid crystal layer was continuously conveyed at 20 m / min. That is, the web 16 that passed through the heating zone 78B was irradiated with ultraviolet rays having an illuminance of 600 mW for 4 seconds by an ultraviolet lamp 80 (output: 160 W / cm, emission length: 1.6 m) to crosslink the liquid crystal layer.

  Further, the web 16 on which the alignment film and the liquid crystal layer are formed has its surface optical characteristics measured and inspected by an inspection device 84, and then a protective film 88A is laminated on the surface of the liquid crystal layer by a laminator 88, and a winder. 82 to obtain an optical compensation film.

  The obtained optical compensation film was evaluated. The evaluation was performed on the alignment film orientation and the bright spot generation frequency of an optical compensation film in which a liquid crystal layer was laminated on a 4000 m-rubbin-treated alignment film using a rubbing cloth material. The results are shown in Table 1. The symbols in the table are as follows.

≪Alignment film orientation≫
The alignment film orientation was evaluated by confirming the extinction degree. Here, the extinction degree refers to the extinction degree of the optical compensation film, and is produced by using the rubbing cloth material of the present invention so that the transmittance is minimized between two polarizing plates arranged in crossed Nicols. The transmittance measured when an optical compensation film is placed. The measurement wavelength of the transmittance is 550 nm, and the transmittance of the polarizing plate in the paranicol arrangement is 100%.
◎ ・ ・ ・ ・ ・ Extinction degree is less than 0.010% ○ Extinction degree is 0.010% or more and less than 0.015% × ・ ・ ・ ・ ・ Extinction degree is 0.015% or more ≪Bright spot Frequency of occurrence >>
The frequency of bright spot generation is determined when the optical compensation film is placed between the two polarizing plates placed in crossed Nicols between the light source and the detection device (CCD camera) using the rubbing cloth material of the present invention. It calculated | required from the size of the image detected with the CCD camera, and the detected number per 10 m.
◎ …… less than 0.3 / m ○ …… 0.3 / m or more to less than 0.5 / m × 0.5 / m or more

  Examples 1 to 8 in which the surface roughness Ra of the back surface of the fabric structure is included in the range of 40 to 70 μm were able to produce an optical compensation film with good orientation and a small number of bright spots. . In particular, a good optical film is produced in Examples 1 to 6 in which the average hardness of the pile yarn is 3 to 30 g / d, the average life is 60 times or more, and the mutual friction coefficient is in the range of 0.15 to 0.40. I was able to. Further, Comparative Examples 1, 5, and 6 whose surface roughness was less than the lower limit of the present invention and Comparative Examples 2 to 4 that exceeded the upper limit were poor in both alignment film orientation and bright spot occurrence frequency.

  As described above, by setting the surface roughness of the back surface of the fabric structure within a predetermined range, the orientation of the formed film is good even with long-term use, and the occurrence frequency of bright spots can be suppressed. It was. Furthermore, a better optical compensation film could be produced by setting each physical property within a predetermined range.

It is a partial expansion perspective view which shows the structure of the cloth material for rubbing. It is explanatory drawing which shows the production line of the optical compensation film to which the cloth material for rubbing of this invention is applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,6 ... Rubbing cloth material, 2 ... Warp, 3 ... Weft, 4, 7 ... Pile yarn, 10 ... Optical film production line, 11 ... Bar coating device, 16 ... Web, 66 ... Delivery machine, 68 ... Guide Roller, 70 rubbing ... processing device, 72 ... rubbing roller, 76 ... drying zone, 78 ... heating zone, 80 ... ultraviolet lamp, 82 ... winder, 84 ... roller stage, 86, 88 ... backup roller

Claims (5)

A rubbing cloth material for rubbing an alignment film, comprising a ground fabric structure composed of warps and wefts, and a pile yarn woven into the base fabric structure,
A rubbing cloth material having a surface roughness Ra of 40 to 70 μm on the back surface of the fabric structure.   The rubbing cloth material according to claim 1, wherein the pile yarn has an average hardness of 3 to 30 g / d.   The rubbing cloth material according to claim 1 or 2, wherein the pile yarn has a fatigue life of 60 times or more in a Gakushin-type friction fastness test defined in JIS L0849.   The rubbing cloth material according to any one of claims 1 to 3, wherein a mutual friction coefficient (yarn / yarn) of the pile yarn is 0.15 to 0.40. The rubbing cloth material is
The number of bright spots exceeding 70 μm on an optical compensation film in which a liquid crystal layer is laminated on an alignment film subjected to a rubbing process of 4000 m with a rubbing work of 300 to 600 Nm / m ² is 0.5 piece / m ² or less. The rubbing cloth material according to any one of claims 1 to 4.

Images