JP2008241868A - Rubbing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubbing method for reducing the occurrence of faults resulting from rubbing. <P>SOLUTION: The rubbing method is characterized in that a long-sized alignment substrate film is rubbed using a rubbing roll on which rubbing cloth is stuck, the rubbing cloth being obtained from velvet woven cloth using rayon pile yarn and having no paste material stuck thereto and being obtained by a manufacturing process including a raising processing step and including neither a washing step nor a resin impregnation step for the velvet woven cloth. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for rubbing a long-oriented substrate film by a rubbing roll to which a rubbing cloth obtained using rayon pile yarn is attached.

  In a liquid crystal display device or the like, an alignment substrate is used in which a film made of a polymer compound is provided on a substrate for alignment of liquid crystal molecules in a liquid crystal cell. Viewing angle improvement obtained by using a film as an alignment substrate and transferring the liquid crystal polymer layer directly on the alignment substrate film or by transferring the liquid crystal polymer layer onto the translucent substrate film Liquid crystal optical films such as plates, retardation plates, and color compensation plates are known. Such an alignment substrate is obtained by rotating a rubbing roll on which a rubbing cloth is attached in a predetermined direction so that the fiber bristle of the rubbing cloth is on the surface of a polymer substrate film that becomes the alignment substrate film or a substrate such as glass It is obtained by rubbing the surface of the provided polymer film in a certain direction.

  In producing the liquid crystal optical film in this way, the occurrence of defects in the product film has become a problem. Although the cause of a fault can consider an environmental cause, a human body basis, etc., it is thought that a use member basis occupies a big part. Among them, the rubbing cloth has not only various oils and resins such as spinning oils, twisting oils, glues, shearing oils, pile dipping resins, back coat resins, etc. attached to the manufacturing process, but also warps used for the base fabric. The same oil agent is also used for the weft and the weft, and these are considered to cause a contamination by shifting to the rubbed substrate (polymer substrate film) during rubbing, affecting the alignment of the liquid crystal. . The production yield is greatly reduced by the occurrence of such defects, and therefore, it is desired to reduce the source of the defect-causing substance.

The rubbing cloth using rayon for the pile yarn uses various oils and glues in the manufacturing process, but these oils and glues are not preferable for rubbing cloth applications if they remain attached to the yarn. A cleaning process is provided to sufficiently remove the oil agent and paste material. Thereafter, for the purpose of enhancing the spreadability and the raising property, a resin processing treatment is performed in which the resin is immersed in the woven fabric, and then a raising treatment process is performed (for example, see Patent Document 1 and Registered Utility Model Document 1). However, it has been found that by performing such a resin processing treatment, the resin peeled off from the pile yarn during the rubbing treatment adheres to the alignment substrate surface as a foreign substance, causing a liquid crystal alignment defect. In order to eliminate such problems, a method for producing a rubbing cloth using a cut pile yarn made of cellulose acetate fibers instead of a rayon yarn as a pile yarn has been proposed. According to this method, it is possible to obtain a rubbing cloth having excellent fiber opening and napping performance without performing resin processing (see Patent Document 2). However, the rubbing cloth using the cut pile yarn made of cellulose acetate fiber is poor in the friction strength of the pile yarn itself, and when the rubbing treatment is performed, defects associated with the occurrence of yarn breakage, yarn waste, etc. occur, which is satisfactory in terms of performance. It was not a thing.
It has been desired to develop a rubbing method that solves these problems.
Japanese Patent No. 3400424 (Claim 4, [0028] to [0031]) JP 2004-332136 A (page 3) Registered Utility Model No. 3032820 (Claim 3, [0015])

  The present invention provides a rubbing method excellent in defect resistance by performing rubbing with a rubbing cloth made of velvet woven fabric using rayon pile yarn, which solves the above-mentioned problems.

  The present invention is a rubbing cloth obtained from a velvet woven fabric using rayon pile yarn, wherein the rayon pile yarn has no adhesive material attached thereto, and the velvet woven fabric washing step and resin dipping step are performed. It is a rubbing method characterized by rubbing a long-oriented substrate film with a rubbing roll to which a rubbing cloth obtained in a production process including a raising treatment process is attached.

In the rubbing cloth obtained using rayon pile yarn containing oil and glue, the harmful effect of the resin dipping process has been known, but the woven cloth after the washing process has the glue and oil removed. Without the resin dipping step, it is extremely difficult to achieve both the spreadability and the napping property, and the resin dipping step (resin processing) has been considered essential for ensuring the spreadability and napping property. However, the present invention makes it possible to omit the resin dipping step by using a rayon pile yarn that does not use a paste and omitting the woven fabric washing step. In this case, it is impossible to wash various oils used in the process of manufacturing the rubbing cloth. The oil used is lighter and product defects are reduced.
According to the rubbing method of the present invention, the occurrence of defects in the obtained product can be greatly suppressed, leading to an improvement in production yield.

Hereinafter, the present invention will be described in detail.
As the woven fabric used when the rubbing cloth used in the present invention is manufactured, a woven fabric obtained by weaving a rayon pile yarn into a base fabric woven from warps and wefts is preferably used. Examples of the weaving structure include structures usually used as velvet weaving such as V weaving and W weaving, but are not particularly limited thereto.

  Cotton, rayon, polyester, acetate, nylon and the like are used as the warp and weft, but are not particularly limited thereto. As the pile yarn, cupra that is viscose rayon or copper ammonia rayon can be used. The fineness of the pile yarn can be selected in the range of 0.5 to 7 denier, preferably 0.8 to 6 denier, more preferably 2 to 6 denier. If the fineness is less than 0.5 denier, the yarn is likely to be cut during rubbing, and if it exceeds 7 denier, the fiber diameter becomes thick and scratches are generated on the alignment substrate during rubbing.

  The velvet woven fabric referred to in the present invention refers to a woven fabric obtained by vertically cutting a fabric having a three-dimensional woven structure made of pile yarn and upper and lower two base fabric portions made of warp and weft. . The velvet woven fabric obtained in this way usually cuts the tip of the cut pile in a shearing process and aligns the pile length of the cut pile.

The pile (filament) density of the rubbing cloth cannot be determined unconditionally depending on the fineness, material, strength, etc. of the pile yarn, but is usually 100 to 500 (unit: 1,000 filaments / inch ² ; the same applies hereinafter), preferably 120 to 400, and more Preferably, it can select in the range of 150-250. If the filament density is less than 100, the rubbing density is small, which causes the generation of rubbing stripes. If the filament density is more than 500, the pile density is too large and the hair may be disturbed.

  Examples and Comparative Examples of the present invention are shown below, but the present invention is not limited to these embodiments.

[Comparative Example 1]
A woven fabric having a woven structure in which a rayon pile yarn with a paste material was woven into a base fabric made of warp and weft by W weaving was produced. The velvet woven fabric obtained by cutting this into upside down fabrics is sheared and then line washed with hot water of about 50-60 ° C, followed by a resin dipping step, and then running the woven fabric in contact with the rotating needle cloth The raising treatment process was carried out. Thereafter, a back coat treatment was performed to obtain a rubbing cloth.
When the liquid crystal optical film was manufactured by the following manufacturing method using the obtained rubbing cloth, the point defect 20 pieces / m was detected.

[Comparative Example 2]
Except that the pile yarn without glue was used as the rayon pile yarn, it was carried out in the same manner as in Comparative Example 1. As a result, although the point-like defects were slightly reduced from those in Comparative Example 1, it was 15 / m. It was.

[Example 1]
When a pile yarn without paste material was used as a rayon pile yarn, and the hot water line washing and the resin dipping process were not carried out, the same practice was performed as in Comparative Example 1. Suppressed.

Liquid crystal optical film manufacturing method:
While the thermoplastic resin film was conveyed as the alignment substrate, the rubbing roll having a diameter of 150 mm around which each rubbing cloth obtained above was rotated was continuously rubbed and wound on the roll.

  A liquid crystal polymer solution in which a liquid crystal polyester is dissolved in an organic solvent is applied onto the rubbing-treated long film, dried, and then subjected to heat treatment at a temperature exceeding the glass transition temperature to align the liquid crystal polymer, and then cooled. Thus, the orientation was fixed.

  Subsequently, the liquid crystal polymer layer surface was continuously coated with an ultraviolet curable adhesive mainly composed of an acrylic oligomer, and a triacetyl cellulose film was continuously laminated. Subsequently, the laminated body which consists of a long alignment substrate film made from a thermoplastic resin / liquid crystal polymer layer / cured acrylic adhesive layer / triacetyl cellulose film was manufactured by irradiating with ultraviolet rays. From the obtained laminate, an oriented substrate film made of thermoplastic resin was continuously peeled to obtain a laminated film (liquid crystal optical film) composed of a liquid crystal polymer layer / cured acrylic adhesive layer / triacetyl cellulose film.

  The rubbing method of the present invention is used for rubbing an alignment substrate (film) in a liquid crystal display device, a liquid crystal optical film, etc., and greatly suppresses foreign matter from adhering to the alignment substrate and causing product defects, thereby improving product yield Let In addition, the rubbing cloth used in the present invention is obtained by a method that does not use a paste material and omits the washing step and the resin impregnation step. This prevents the generation of foreign matter. Therefore, the present invention improves the production efficiency of a liquid crystal display device, a liquid crystal optical film and the like using an alignment substrate (film), and improves the quality of the product.

Claims (1)

  A rubbing cloth obtained from a velvet woven fabric using rayon pile yarn, wherein the rayon pile yarn is free of glue, and includes a washing process and a resin dipping process without raising the velvet fabric. A rubbing method comprising rubbing a long-oriented substrate film with a rubbing roll to which a rubbing cloth obtained in a production process including steps is attached.