JPWO2008056584A1 - Rubbing cloth - Google Patents

Abstract

A rubbing cloth used for orienting an alignment film of a liquid crystal display device, the rubbing cloth comprising a ground ground and a pile thread, and a heat-fusible composite fiber on at least a part of the warp and weft of the ground ground And the pile yarn is 1.1 dtex or less flat ultrafine fiber obtained by dividing a multilayer laminated composite fiber, and the flatness (major axis / minor axis ratio) is 4 or more. An object of the present invention is to provide a rubbing cloth that is made of a fiber and that can easily form a fine groove in an alignment film for a liquid crystal display device and is easy to handle.

Description

  The present invention relates to a rubbing cloth used in a rubbing process for controlling the orientation of liquid crystal molecules in a manufacturing process of a liquid crystal display device.

  In the liquid crystal display device, fine grooves are formed in the alignment film, and liquid crystal molecules are aligned along the fine grooves to regulate the alignment of the liquid crystal molecules. The step of forming fine grooves in the alignment film is called a rubbing treatment process because the alignment film is rubbed with a pile cloth adhered to a rotating roll. The pile cloth used here is called a rubbing cloth, and currently, rayon, cotton or the like is used as a material.

  The rayon rubbing cloth is a velvet fabric using cupra rayon for ground yarn and usually rayon for pile yarn. After weaving, shearing, desizing, scouring, and processing of resin using a fiber-reactive resin to ensure pile stability, and vinyl acetate resin or acrylic to prevent pile removal The back side is coated with resin.

  On the other hand, in the case of cotton cloth, scouring and bleaching are performed to remove wax components and interstitial substances contained in the cotton itself after weaving, and further, split shearing is performed. In the case of cotton, a single fiber has a twist called convolution and is not a straight hair, and therefore, resin processing using a fiber-reactive resin for stabilizing the pile is not performed. In general, rayon is called W pile, and it is pressed so that the pile is sandwiched by three wefts, whereas cotton is called V pile and the pile is dropped because it is pressed by one weft. The structure is easy, and a sufficient back coat is required.

  In general, in the rubbing process using a normal rayon or cotton rubbing cloth, the friction force against the alignment film is not uniform unless the pile length, inclination angle and density of the rubbing cloth are uniform. This causes variation and causes the display quality of the liquid crystal panel to deteriorate. In the case of a pile formed of general ultrafine fibers, the rebound resilience is reduced, and the frictional force is insufficient to make orientation difficult.

In the rubbing process, the alignment film is rubbed with a rubbing roller that rotates at high speed, and friction, contact, and peeling are repeated to generate static electricity.
This static electricity damages the circuit on the glass substrate and leads to defective liquid crystal display. Further, the rubbing cloth is attached to a metallic roll through a double-sided tape, but expands and contracts due to humidity when the ground of the pile fabric is a cellulosic fiber. That is, it expands at high humidity and contracts at low humidity. For this reason, there is a problem that strict humidity control must be performed in precision cutting, storage, and sticking to a rubbing roll of the rubbing cloth.

  On the other hand, for the purpose of improving liquid crystal display accuracy, it has been proposed to use a rubbing cloth having a raised portion made of ultrafine fibers of 1.1 dtex or less (see Patent Document 1). However, the ultrafine fiber specifically described in Patent Document 1 is an ultrafine fiber having a fan-shaped cross section obtained by splitting a composite spun fiber having a hollow radial cross section. When it was used for the rubbing treatment using fibers, it was found that many orientation defects occurred. As the cause, in the ultrafine fiber as described in Patent Document 1, there is no waist of the ultrafine fiber constituting the pile, and it is easy to fall down. As a result, the advantage of using the ultrafine fiber despite being the ultrafine fiber It is possible that is not being utilized.

  In the rubbing process, friction, contact, and peeling are repeated between the rubbing cloth that rotates at high speed and the alignment film, so that static electricity is generated, and the circuit on the glass substrate is damaged, leading to defective liquid crystal display. In order to prevent this, Patent Document 1 discloses providing conductivity to at least the raised layer of the raised cloth in order to prevent charging during the rubbing treatment. As a specific method for imparting antistatic properties, a method has been proposed in which an antistatic agent such as carbon black or fine metal powder is kneaded when spinning ultrafine fibers. However, when using conductive fibers kneaded with antistatic agent in the pile, the antistatic agent such as carbon black or metal powder is exposed on the surface or cross section of the pile yarn in velvet fabric or moquette fabric. Become. The rubbing of the alignment film with the pile yarn from which the antistatic agent is exposed causes contamination and leads to a defect in the liquid crystal display device.

On the other hand, in order to avoid generation of fine dust and foreign matters due to the abrasion of the conductive material, a composite fiber having a sheath / core structure in which the core is made of a conductive material and the non-conductive material covers the core. And a rubbing cloth in which the conductive material is not substantially exposed on the rubbing surface has been proposed (see Patent Document 2).
As a specific aspect, there has been proposed a rubbing cloth in which a pile yarn is composed of a composite fiber having the above-described sheath / core structure and the pile is not cut.
However, the rubbing cloth described in Patent Document 2 uses a sheath / core conductive composite fiber for the pile yarn, so that the pile yarn cannot be made extremely thin, and the alignment film can be finely oriented. Have difficulty. That is, the conductive composite fiber having a sheath / core structure includes a metal fiber, a surface metallized fiber, a carbon fiber, a conductive ceramic fiber, or the like as a core conductive material, or a carbon powder or a metal powder. Conductive powder such as kneaded into a resin and molded into a fiber that is spun, and the outer layer is coated entirely with a coating material made of resin such as polyester, acrylic, polyamide, etc. The single fiber fineness of the composite fiber is about 5 to 20 dtex, and it is difficult to obtain a fine fineness, and the pile fineness (1.1 to 3.3 dtex) of a normal rubbing cloth becomes extremely thick. When used, it leads to rubbing spots and streaks, and when used over the entire surface, an unequal electric field is not formed and corona discharge cannot be obtained.
Further, since the tip of the pile yarn is not an acute angle but a ring pile, the rubbing effect is also reduced. Furthermore, when the conductive material is black, there is no proposal for providing a concealing layer that conceals black and makes it white or grayish white.

Furthermore, in patent document 1, in order to prevent the pile part of the rubbing cloth from falling off, it is described that vinyl acetate-based or acrylic acid-based resin is coated on the back surface, but when a new process called coating is added, The manufacturing process for the entire rubbing cloth becomes longer, the cost is increased, and processing defects such as dirt in the process increase.
Thus, conventionally, there has not been proposed a rubbing cloth capable of solving problems such as a structure of an extremely fine pile having a high rubbing effect capable of improving liquid crystal display accuracy, contamination by a conductive agent, and high cost.

JP 2005-91899 A Japanese Patent Laid-Open No. 2007-232938

The present invention has been made in view of such circumstances, and the length, inclination angle, and density uniformity of the pile yarn are not so much of a problem, and the pile yarn is composed of ultrafine fibers having a special cross section. An object of the present invention is to provide an excellent rubbing cloth that achieves uniform orientation, has little contamination despite the measures against static electricity by conductive fibers, and can omit the coating process.
As a result of intensive studies to solve the above-mentioned problems, the present inventors have been able to obtain a display element with very little orientation failure by using ultrafine fibers having a special cross section for a pile of rubbing cloth, and further, The use of the fusible conjugate fiber makes it possible to omit the ground backing step, and the use of the conductive conjugate fiber with the conductive layer not exposed reveals that a rubbing cloth with improved yield can be obtained. The invention has been completed.

That is, the present invention is (1) a rubbing cloth used for orienting an alignment film of a liquid crystal display device, and the rubbing cloth is composed of a ground ground and a pile yarn, and at least of warps and wefts of the ground ground A heat-fusible conjugate fiber is used in part, and the pile yarn is a flat ultrafine fiber of 1.1 dtex or less obtained by dividing a multilayer laminated conjugate fiber, and its flatness (major axis / minor axis) A rubbing cloth characterized in that it is composed of ultrafine fibers having a ratio of 4 or more, and (2) the ground includes conductive composite fibers, and the conductive composite fibers are present on the fiber surface. The rubbing cloth according to 1 above, wherein the conductive layer is not exposed and the conductive performance is 10 ⁵ to 10 ⁹ Ω / cm per filament, and (3) a concealing polymer layer is provided on the outer periphery of the conductive layer of the conductive composite fiber. Conductive composite fiber Wherein the is used (2) rubbing cloth according, there is provided a.

It is a cross-sectional view of an example of a multilayer laminated composite fiber used as a flat extra fine fiber forming component of the pile yarn of the rubbing cloth of the present invention. It is a schematic cross section which shows an example of a structure of the rubbing cloth of this invention. It is a schematic cross section which shows an example of the electroconductive composite fiber used for this invention. It is a schematic cross section which shows the electroconductive composite fiber used for the comparative example of this invention.

Explanation of symbols

A: Fiber-forming polymer A
B: Fiber-forming polymer B that is incompatible with polymer A
1: multilayer laminated composite fiber 10: rubbing cloth 21: pile layer 22: ground 23: conductive composite fiber 30, 40: conductive composite fiber 31: conductive layer 32: concealing polymer layer 33: protective polymer layer 41: protection Polymer layer

  In the rubbing cloth of the present invention, the ultrafine fibers used for the pile of the rubbing cloth are a fiber-forming polymer (in the present invention, “polymer” is synonymous with “polymer”) A and polymer A as shown in FIG. Is a flat ultrafine fiber obtained by splitting a split type composite fiber having a special cross-sectional shape of a multi-layer laminated type, which is an assembly of flat ultrafine fiber forming components composed of an incompatible fiber-forming polymer B. After that, each becomes a flat ultrafine fiber made of polymer A or polymer B. The flat fine fiber has a single fiber fineness of 1.1 dtex or less, which is suitable in that a uniform display element without streaks is obtained, preferably 0.1 to 1.1 dtex, and preferably 0.2 to 0.5 dtex. The range of is more preferable. Further, it is necessary that the flatness, which is the ratio of the major axis / minor axis in the cross section of the flat ultrafine fiber, is 4 or more in order to obtain a fine groove, and preferably has a flatness of 5 or more and 15 or less. is there. In particular, when the pile is formed in a state where the flatness is 4 or more and the flat surface is in contact with the pile, the pile yarn is not easily collapsed, and an alignment film having excellent orientation can be obtained. In order to make it difficult for the pile yarn formed of flat ultrafine fibers to fall down, it is preferable to arrange the pile yarn so that the major axis side of the flat surface of the flat ultrafine fibers is parallel to the rubbing direction. For example, a multi-layer laminated composite fiber as shown in FIG. 1 is used as the split composite fiber, and a pile forming yarn (hereinafter, also referred to as “pile yarn”) made of the same fiber has a twist number of 0 to 500 T / When using such a low twist yarn of M and driving such a pile yarn into a woven fabric in parallel with the warp, the pile yarn is pressed down, the pile yarn is flattened, and the flat surface (major axis side) of the splittable multilayer laminated composite fiber is the weft yarn It is easy to become parallel with. When such a yarn is divided and wound as a rubbing cloth so that the circumferential direction of the rubbing roll is the warp direction, the flat surface of the flat ultrafine fibers tends to be parallel to the rubbing direction. Of course, even if there is no special consideration that the flat surface of the flat ultrafine fiber is parallel to the rubbing direction, some of the flat ultrafine fibers are naturally oriented in such a direction that the flat surface is parallel to the rubbing direction. The flat ultrafine fibers work effectively to form uniform fine grooves.

  Furthermore, in the present invention, the multi-layer laminated composite fiber before division preferably has a cross-sectional shape in which 5 to 20 layers, particularly 7 to 15 layers of flat ultrafine fiber forming components are laminated so that the flat surfaces are in contact with each other. The monofilament fineness of the multilayer laminated composite fiber before division is preferably 1 to 10 dtex. The multi-layer laminated composite fiber before division preferably has a cross-sectional shape in which many flat cross-section fiber forming components as described above are in contact with each other on a flat surface, and in particular, the cross-section of each flat ultrafine fiber forming component is substantially rectangular. It is preferable in terms of producing fine grooves.

Further, the pile is preferably 40 to 500 dtex in terms of the total fineness, and the pile height is 1.0 to 3.0 mm, particularly 1.5 to 2.6 mm. This is preferable in that a film is obtained. Further, the pile density is preferably in a state where 100,000 to 400,000 piles exist per 1 cm ² of the ground fabric.

  Such a flat microfiber is a multi-layer laminated composite fiber obtained by conducting two or more incompatible polymers to a spinneret hole so as to be in a multi-layer laminated state when viewed in the cross section of the fiber and performing composite spinning. , In the state of fibers or after making a pile fabric using the fibers, by scouring treatment, water jet treatment, air jet treatment, needle treatment, shearing treatment, alkali weight loss treatment, solvent treatment such as benzoic acid or benzyl alcohol It is obtained by dividing.

The incompatible polymer constituting the split composite fiber is a polymer having a solubility parameter different by 2 MJ / m ⁻³ or more. Specifically, the polymer A is polyethylene terephthalate, polybutylene terephthalate or a copolyester mainly composed thereof, polyester such as polylactic acid, and the polymer B is nylon-6, nylon-66, nylon-610, semi-aromatic polyamide, etc. Polyamide, or an ethylene-vinyl alcohol copolymer having an ethylene content of 20 to 50 mol% as polymer A, and a combination of two or more selected from polyolefins such as polyethylene and polypropylene as polymer B. It is preferable from the viewpoint that division is easy.
The weight ratio of polymer A to polymer B is preferably in the range of 4: 1 to 1: 4, and more preferably in the range of 3: 1 to 1: 3.

  Specific examples of more preferable combinations of the polymers forming the multilayer laminated composite fiber include polyamide / polyester, polyester / ethylene-vinyl alcohol copolymer, polyester / polyolefin, polyamide / polyolefin, and the like. Of these, a polyamide / polyester combination is most preferable. The solubility parameter of the polymer constituting the composite fiber here is a parameter table of the polymer described on page 90 of the “Plastic Data Book” (issued on December 1, 1999) published by the Industrial Research Council ( It means the value shown in the SP value table. For polymers not shown in the SP value table, the solubility parameter can be determined from the calculated density energy density.

  Next, the heat-fusible conjugate fiber used for the ground of the rubbing cloth of the present invention will be described. The heat-fusible conjugate fiber used in the present invention is a low melting point component containing a polymer having a melting point of 160 ° C. or lower and 80 ° C. or higher, and a polymer having a higher melting point than the low melting point component, Consists of two different polymers with high melting point components of 200 ° C or higher, preferably 240 ° C or higher, side-by-side type, core-sheath type (concentric core-sheath type, eccentric core-sheath type), sea-island type A composite fiber having a composite cross-sectional structure such as a multilayer laminate type can be used, and a core-sheath type is particularly preferable.

  Examples of the polymer that can be used for these heat-fusible composite fibers include polyamides represented by nylon and the like, polyesters, and polyolefin polymers represented by polypropylene and polyethylene. Among these, examples of the combination of the low melting point component and the high melting point component include low melting point polyester / high melting point polyester, polyethylene / polypropylene, polyethylene / high melting point polyester, and polypropylene / polyester.

Furthermore, in the present invention, it is important that the heat-fusible conjugate fiber has both heat-fusibility and fiber properties such as strength, elongation, and heat-shrinkability even after fusing. Considering that the purpose of use of the heat-fusible conjugate fiber is to prevent the pile from falling off and that the pile yarn is preferably a polyester / nylon conjugate fiber, from the viewpoint of compatibility between the pile yarn and the ground yarn Low melting point polyester / high melting point polyester is preferable. Further, those using polyhexamethylene terephthalate as the low melting point polyester component and polyethylene terephthalate as the high melting point component are particularly preferable because the texture does not become hard after fusion. The proportion of the low melting point polymer in the heat-fusible conjugate fiber is preferably 20 to 80% by weight.
When the low melting point polymer is less than 20% by weight, it is difficult to obtain good heat-fusibility, and when it exceeds 80% by weight, the fiber forming processability such as spinnability and stretchability is deteriorated.

The thickness of the single fiber of the heat-fusible conjugate fiber is preferably 1 to 10 dtex. In the present invention, all of the fibers constituting the ground may be heat-fusible conjugate fibers, or the heat-fusible conjugate fibers may be used as part of the fibers constituting the ground. . When used as a part of the fibers constituting the ground, pile yarn is that 40% by weight or more of the total fibers constituting the ground are arranged at predetermined intervals on the warp and weft yarns. It is preferable for preventing the omission.
Of course, in the present invention, when it is desired to further remove the pile yarn, an acrylic emulsion, polyurethane emulsion, rubber emulsion, latex or the like may be back-coated on the ground.

  In the present invention, a conductive conjugate fiber can be used for the ground. In general, rubbing treatment is performed by rubbing the alignment film with a rubbing cloth adhered to a high-speed rotating rubbing roller, so that friction, contact, and peeling are repeated between the alignment film and the rubbing cloth, and static electricity is generated. Damages the circuit on the glass substrate and adsorbs various dusts generated during rubbing.

  For this reason, countermeasures against static electricity are extremely important, and the above-mentioned Patent Document 1 describes the use of a rubbing cloth in which conductivity is imparted to the raised layer (that is, the pile portion) as countermeasures against static electricity. As mentioned above, it is described that an electroconductive fiber is added to the raised layer, or an antistatic agent (carbon black or metal powder) is kneaded and spun when spinning ultrafine fibers. However, when the conductive fiber contained in the raised layer is not an ultrafine fiber, the raised layer, that is, the pile surface, is a mixture of the conductive fiber and the ultrafine fiber, and naturally there is a difference in the frictional force between the alignment film. Resulting in rubbing spots. On the other hand, in the ultrafine fiber kneaded with the antistatic agent, it is impossible in the manufacturing process to make the divided ultrafine fiber, for example, a core-sheath type composite fiber. Is understood to mean an ultrafine fiber in which the antistatic agent is uniformly kneaded. Therefore, in this case, carbon black and metal fine powder are exposed on the surface of the ultrafine fiber. Further, even if it is assumed that the divided ultrafine fibers are composited, the pile yarn is cut after weaving, so the antistatic agent is exposed on the pile yarn cross section, and the antistatic If the alignment film is rubbed with ultrafine fibers with the agent exposed, it causes contamination and lowers the liquid crystal display quality.

The inventors of the present invention can remove the accumulated static electricity not only by conduction but also by corona discharge. Therefore, it is not necessary to use conductive fibers for the pile, and it may be used for the ground, that is, a part of the ground structure. I found. As the conductive conjugate fiber, for example, a conjugate fiber in which a conductive layer made of a resin containing conductive carbon (carbon black), which is a general conductive agent used in the fiber, is continuous in the length direction of the fiber is used. can do. Since the neutralization is performed by corona discharge, the electrical resistance of the conductive composite fiber is preferably in the range of 10 ⁵ Ω / cm to 10 ⁹ Ω / cm. The conductive carbon black contained in the conductive layer of the conductive composite fiber having such electrical resistance preferably has a specific resistance of 10 ⁻² to 10 ⁻³ Ω · cm. As used herein, the electrical resistance is calculated by calculating the electrical resistance at an applied voltage of 1 KV after cutting the fiber to 10 cm, applying a conductive paint (dortite) to the cut surface and fixing the fiber end, and using the end as an electrode. The electrical resistance per filament.
As the conductive agent, carbon powder such as acetylene black, ketjen black, PAN-based carbon, and pitch-based carbon, and metal-based materials such as aluminum, palladium, iron, copper, and silver are used as the conductive carbon (carbon black). Powders, fibers, zinc oxide, tin oxide, titanium oxide, copper sulfide, zinc sulfide, and other metal compound powders. These can be used alone or in combination of two or more.

When carbon black is used as a conductive agent, the electrical conduction mechanism of the conductive carbon black-containing resin is considered to be due to the contact of the carbon black chain, due to the tunnel effect, etc., but the former is generally considered the main Yes. Therefore, the longer the carbon chain, or the higher the density of the carbon chain present in the resin, the higher the contact probability and the higher conductivity. As a result of the study by the present inventors, there is almost no conductive effect when the conductive carbon black content is less than 15% by weight, and when 20% by weight, the conductivity is drastically improved. Saturation is reached.
The conductive layer of the conductive composite fiber is composed of a conductive material such as conductive carbon black and a fiber-forming polymer.

An example of a cross section of the conductive conjugate fiber including the conductive layer is shown in FIG. In the conductive composite fiber 30 used for the rubbing cloth of the present invention shown in the same figure, the conductive layer 31 is not exposed on the fiber surface (fiber side surface), that is, the conductive layer 31 is a concealing polymer as a multi-layer nonconductive polymer layer. It is a sheath-core type conductive composite fiber that is covered with the layer 32 and the protective polymer layer 33, and the conductive layer is not exposed on the fiber side surface, and is a non-exposed type that can avoid the problem of contamination to the alignment film.
As the thickness of the conductive conjugate fiber used for the rubbing cloth of the present invention, the single fiber fineness is preferably 5 to 20 dtex, particularly preferably 7 to 18 dtex.

  In the rubbing cloth of the present invention, as shown in FIG. 3, in order to conceal the black color of the conductive layer such as carbon black from the viewpoint of aesthetics, a white (gray white) concealing polymer layer that covers the conductive layer may be used. It is preferable in terms of the appearance of the conductive conjugate fiber. The concealing polymer layer contains inorganic fine particles in a fiber-forming polymer. Examples of the inorganic fine particles include titanium dioxide, zinc oxide, magnesium oxide, aluminum oxide, silicon dioxide, barium sulfate, calcium carbonate, sodium carbonate, talc, Examples thereof include white pigments or white fillers having a concealing effect such as kaolin, and these can be used alone or in combination of two or more. Titanium dioxide and / or zinc oxide is preferable in consideration of the concealing effect, whiteness as a fabric, yarn forming property, and processing characteristics. A concealing effect can be obtained by adding approximately 10 to 50% by weight of the inorganic fine particles in the fiber-forming polymer forming the concealing polymer layer and adjusting the thickness of the concealing polymer layer. As the fiber-forming polymer, those listed later as polymers for forming a sheath layer can be used.

In the conductive composite fiber of the rubbing cloth of the present invention, it is preferable that the concealing polymer layer is further covered with a fiber-forming polymer (polymer) to provide a protective polymer layer. Examples of the polymer that forms the protective polymer layer include polyamides represented by nylon and the like, polyesters, and polyolefin polymers represented by polypropylene and polyethylene. In particular, it is preferable to select a polymer that is compatible with the low-melting-point component of the heat-fusible composite fiber so that the heat-bonding of the ground can be firmly performed, because the pile yarn can be further removed.
As a function of the protective polymer layer, the conductive layer and the concealing layer are further protected, and the conductive composite fiber is woven into a velvet fabric or the like, and the fiber strength is expressed as the ground yarn of the rubbing cloth, the black color of the conductive layer, etc. For example, further concealment. Further, since the protective polymer layer becomes the outermost surface of the fiber, it is preferable to add titanium dioxide or the like used for ordinary synthetic fibers to the forming polymer to enhance the texture of the fiber. In addition, various additives such as a heat stabilizer, a light stabilizer, and an antistatic agent that are usually used for adding fibers, a color pigment, and the like can be appropriately added to the concealing polymer layer and the protective polymer layer as necessary.

When the conductive composite fiber is formed of three layers as shown in FIG. 3, the composite ratio in the fiber cross section is the relative ratio of the longest diameter of the conductive polymer layer 31, the maximum thickness of each of the concealing polymer layer 32 and the protective polymer layer 33. However, a ratio of 1: 0.1 to 1: 0.5 to 2 with the maximum length of the conductive polymer layer 31 being 1 is preferable from the balance of conductivity, concealability, surface protection, fiber performance, and the like. .
For reference, an exposed type conductive composite fiber is shown in FIG. The conductive conjugate fiber 40 shown in the figure is composed of a conductive layer 31 and a protective layer 41, and the conductive layer 31 is exposed at a part of the side surface of the fiber. When such an exposed type conductive composite fiber is used, there is a risk of contamination of the conductive agent due to friction caused by a rubbing roll rotating at high speed.
In the present invention, the conductive conjugate fiber is used for a part of the ground yarn without being used for the pile yarn, but as shown in FIG. 3 from the viewpoint of preventing contamination in consideration of friction caused by the rubbing roll rotating at high speed. A non-exposed sheath-core type conductive composite fiber is employed.

  In addition, it is preferable to use 2-6 conductive fibers in a bundled state in order to prevent loss of conductivity due to cutting of the conductive composite fiber. Moreover, it is also preferable that tension is applied to the conductive conjugate fiber as much as possible as a covering yarn in which the conductive conjugate fiber is wound around the non-conductive yarn.

  The conductive conjugate fiber is used in at least the longitudinal direction or the weft direction of the ground tissue. As described above, the yarn containing the conductive conjugate fiber is bundled in a bundle (hereinafter sometimes referred to as “conductive yarn”), and is preferably 1 cm to 5 cm in distance from the ground, more preferably About 1 to 4 cm or less is used. As for the weaving into the ground structure, the conductive yarn made of only the conductive composite fiber may be used alone, or it may be integrated with other reinforcing fibers by using means such as interlacing. The covering yarn may be used. It is convenient to weave in the warp direction or the weft direction at a ratio of 1 conductive thread to 1 cm to 5 cm. When the weaving interval of the conductive yarn is less than 1 cm, the conductive composite fiber is expensive, so that the cost is high and the static elimination performance is not particularly improved. On the other hand, when the weaving interval is 5 cm or more, a sufficient static elimination effect cannot be obtained.

  In the rubbing cloth of the present invention, the ground fabric preferably has a weaving density of 15 to 40 warps / cm and 20 to 50 wefts / cm. The thickness of the warp and the weft is preferably in the range of 50 to 300 dtex.

Next, the best mode of the rubbing cloth of the present invention will be described. FIG. 2 shows an enlarged schematic sectional view of a rubbing cloth 10 according to an embodiment of the present invention.
The rubbing cloth 10 is a pile cloth material composed of a pile 21 and a ground material 22, and a part of the ground material 22 is a heat-bondable composite material with a conductive composite fiber 23 and at least one of warp and weft of the ground material. Fiber is woven. Further, the pile yarn is a flat ultrafine fiber made of multi-layered laminated fibers having an ultrafine fiber of 1.1 dtex or less and a flatness after division of 4 or more, preferably 5 or more. When the thickness exceeds 1.1 dtex, each pile has a great influence on the alignment film of the liquid crystal display element at the time of rubbing treatment, and it is difficult to obtain a uniform alignment effect due to pile length and tilt angle.

  As the pile fabric material, velvet, moquette and the like are suitable. The ground of the pile fabric material is not limited to the ground yarn except that the conductive conjugate fiber is arranged at least in the warp direction or a part of the weft direction, and at least the heat-fusible conjugate fiber is used for the warp yarn or the weft yarn. Commonly used materials can be used. However, when the ground yarn is a cupra, there is a dimensional change due to a change in humidity, so strict humidity control is required for storage, precision cutting, and sticking to a rubbing roll. Since the required temperature and humidity management is easy, a polyester fiber having good dimensional stability against temperature and humidity is particularly suitable.

  Since the pile yarn of the rubbing cloth of the present invention has a special cross section made of flat ultrafine fibers, uniform and stable rubbing treatment can be performed. And according to this rubbing cloth, it is not necessary to strictly manage the pile length and the inclination angle as in the prior art, and it is easy to handle and can generate uniform and fine grooves in the alignment film.

  Further, since the rubbing cloth of the present invention has conductive composite fibers arranged in a part of the ground structure, static electricity caused by repeated friction, contact and peeling between the alignment film and the rubbing cloth during rubbing is caused by corona discharge. It is possible to eliminate static electricity, reduce damage to a circuit provided in the alignment film, and reduce adsorption of dust generated by rubbing.

  Further, when a heat-fusible composite fiber is used for at least the warp or weft of the rubbing cloth of the present invention, the back coating for preventing the pile yarn from falling off can be omitted, and the cost can be reduced by shortening the process. Yield is also improved.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.
The flatness referred to in the present invention is an average value obtained by taking a micrograph of the cross section of the fiber, enlarging it, and determining the ratio of the long side to the short side for each of the 50 fibers arbitrarily selected. Say.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.

Example 1
Using the pile yarn, warp and weft described below, center cut of velvet fabric with ground weaving density of 70 / inch (28 / cm) and 69 / inch (27 / cm), respectively. While catching.

Polymer A as shown in FIG. 1 obtained by performing composite spinning using pile yarn polyester (dissolution parameter = 22 MJ / m ³ ) and nylon (dissolution parameter = 27 MJ / m ³ ) in a weight ratio of 2: 1. A multifilament having a twist number of 250 T / M made of a multilayer laminated composite fiber 1 having a flat cross section shown in FIG. 84 dtex / 24 filament) was used as a flat ultrafine fiber-forming pile yarn, which was driven in parallel to the warp.

Ground warp (1) Regular polyester (84 dtex / 72 filament, twist S800T / M)
(2) Conductive composite fiber As the conductive composite fiber as shown in FIG. 3, nylon 6 containing 35% by weight of conductive carbon black is used as the conductive polymer layer 31, and titanium dioxide fine particles (average particle size) are used as the concealing polymer layer 32. Nylon 6 containing 50 wt% of diameter) is used, polyester containing 0.5 wt% of titanium dioxide is used as the protective polymer layer 33, the composite ratio in the fiber cross section is the longest diameter of the conductive polymer layer, and the concealing polymer In a three-layer core-sheath composite cross section comprising a conductive polymer layer, a concealing polymer layer, and a protective polymer layer in a relative ratio of the maximum thicknesses of the layer and the protective polymer layer of 1: 0.27: 1.03 composite spinning, one of the split conductive composite fiber yarn 28dtex / 2 filaments obtained by the stretching (electric resistance ^{3 × 10 7 Ω / cm ·} f) to 1.27cm In woven aligned drawn from the rear of the loom in the warp.

As the ground weft weft, polyhexamethylene terephthalate having a melting point of 135 ° C. as a low melting point sheath component, and a polyester / polyester as a high melting point core component, a heat-sheathed composite fiber (220 dtex / 48 filament) having a core / sheath ratio of 80:20 , Twist number S500 T / M).

Next, shearing was performed, and desizing, scouring, and division of the flat ultrafine fiber-forming pile yarn were performed with an alkali weight reduction process using a sodium hydroxide aqueous solution, with a weight loss rate of 7% as a target. Furthermore, after heat treatment at 180 ° C after brushing and drying, the heat-fusible composite fiber of the wefts firmly fixes the pile, and the pile yarn made of flat ultrafine fibers does not easily fall off from the cut surface cut to the specified size. The backing process could be omitted. The pile of the obtained rubbing cloth is composed of ultrafine fibers having a fineness of 0.3 dtex and a flatness of 6, the pile length is 2 mm, and the flat ultrafine fibers are in contact with the split surfaces. Existed. And it was in the state where 250,000 flat ultra-pile pile fibers existed per 1 cm ^{2 of} ground fabric.

  Using this rubbing cloth, rubbing was performed at an indentation length of 0.2 mm and a rotational speed of 1500 rpm, and the surface state was observed using an atomic force microscope image. As a result, uniform and parallel grooves without unevenness were formed. In addition, a high-definition liquid crystal display device with reduced scratches in which circuit damage due to static electricity was reduced was obtained.

<< Comparative Example 1 >>
As the ultra fine divided fiber, a multifilament yarn (84 dtex / 24 filament) composed of a composite fiber in which a cross section before division was hollow and 12 layers of polyester / nylon were alternately bonded together was used as a pile yarn. In this comparative example, the conductive composite fiber is not woven into the ground, and the heat-fusible composite fiber is not used. Instead, regular polyester fiber (84 dtex / 72 filament, twist number S800 T / M) is used as warp and weft. And weaving, then shearing, desizing and scouring, and the pile yarn was divided by alkali weight reduction with an aqueous sodium hydroxide solution with the goal of a weight loss rate of 7%. Further, after brushing and drying, back coating was performed using an acrylic emulsion to obtain a rubbing cloth.
When rubbing was performed under the same conditions as in Example 1, a sufficient alignment effect could not be obtained. Further, in the backing process, not a machine dedicated to rubbing cloth, but various fabrics and various colors are processed, so that some stains were observed, resulting in poor yield.
In this rubbing cloth, the fibers constituting the pile were 0.27 dtex ultrafine fibers, but the average flatness was 1.8.

<< Comparative Example 2 >>
As the conductive conjugate fiber, as shown in FIG. 4, nylon 6 containing conductive carbon black is used as the conductive layer 31, and similarly nylon 6 is used as the protective polymer layer 41. The conductive layer 31 is partially exposed on the fiber surface. A so-called exposed type 28 dtex / 2 filament conductive composite fiber 40 (electric resistance 2 × 10 ⁷ Ω / cm · f) and ultra-fine divided fiber having the same radial cross section as in Comparative Example 1 are mixed. A rubbing cloth was prepared in the same manner as in Comparative Example 1, except that the pile yarn was used at a rate of 1 per 27 cm.
When the rubbing treatment was performed in the same manner as in Example 1, the conductive composite fiber used for the pile was thick as 28 dtex / 2 filament, so that scratches were generated, and the conductive layer exposed on the surface of the conductive composite fiber by high-speed rotation More conductive carbon black dropped off and contamination occurred. The alignment performance deteriorated due to the influence of the cleaning process for removing this, and the quality of the liquid crystal display device deteriorated.

The rubbing cloth of the present invention can be used for uniform and stable rubbing treatment for forming uniform and fine grooves in the alignment film.
In addition, since the rubbing cloth of the present invention uses a heat-fusible composite fiber at least for the warp or weft, the back coating for preventing the pile yarn from falling off can be omitted, and the rubbing can improve the yield at low cost. Available for processing.
Further, the rubbing cloth of the present invention in which conductive composite fibers are arranged on a part of the ground structure is formed by removing the static electricity caused by repeated friction, contact, and peeling between the alignment film and the rubbing cloth generated during rubbing by corona discharge. It can be used for rubbing treatment that can reduce damage to the circuit provided in the rubbing and reduce the adsorption of dust generated by rubbing.

Claims (3)

  A rubbing cloth used for orienting an alignment film of a liquid crystal display device, the rubbing cloth comprising a ground ground and a pile thread, and a heat-fusible composite fiber on at least a part of the warp and weft of the ground ground And the pile yarn is 1.1 dtex or less flat ultrafine fiber obtained by dividing a multilayer laminated composite fiber, and the flatness (major axis / minor axis ratio) is 4 or more. A rubbing cloth comprising fibers. The ground ground contains conductive composite fiber, and the conductive composite fiber has no conductive layer exposed on the fiber surface, and the conductive performance is 10 ⁵ to 10 ⁹ Ω / cm per filament. Item 1. A rubbing cloth according to item 1.   The rubbing cloth according to claim 2, wherein the conductive conjugate fiber is formed by applying a concealing polymer layer to the outer periphery of the conductive layer of the conductive conjugate fiber.

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