TWI613092B - Flexographic printing plate and manufacturing method of liquid crystal display element using the same - Google Patents

Abstract

Provided is a flexible printing plate and a method for producing a liquid crystal display element using the same, which is excellent in flatness of a printing surface when mounted on a surface of a plate cylinder, and is suitable for printing of a liquid crystal alignment film for a liquid crystal display element. The flexible printing plate has an arithmetic mean roughness Ra of a roughness curve of the mounting surface facing the plate cylinder of 0.02 μm or more and 0.06 μm or less, and a maximum height roughness Rz of 0.25 μm or more and 1.60 μm or less, and a ten-point average roughness. The degree Rz _JIS is a rough surface of 0.20 μm or more and 0.80 μm or less. A method of manufacturing a liquid crystal display element includes a step of forming a liquid crystal alignment film of a substrate for a liquid crystal panel by flexographic printing using the flexographic printing plate.

Description

Flexible printing plate and method of manufacturing liquid crystal display element using same

The present invention relates to a flexographic printing plate which can be suitably used for forming a liquid crystal alignment film such as a liquid crystal display element by flexible printing, and a method of manufacturing a liquid crystal display element using the same.

In order to form a liquid crystal alignment film having a high coating film quality (unlikely uniform thickness, and having no pinholes or the like) on the electrode formation surface of the liquid crystal panel substrate constituting the liquid crystal display element, the use of a good printing property is excellent. Flexible printing method.

However, it is known that a flexographic printing plate used in flexographic printing is subjected to a shearing direction force when it is repeatedly printed on a plate cylinder, and a positional shift occurs on the surface of the plate cylinder.

That is, the flexographic printing plate slightly extends on the surface of the plate cylinder when subjected to a shearing force during printing, and even if the force in the shearing direction is removed as the printing is completed, the extension remains unrecovered and remains. Moreover, as the number of prints increases, the delay The accumulation of the product causes the positional offset of the plate to expand.

The positional offset has an offset of the printing start position and a shift of the pitch caused by the overall extension of the printed pattern, both of which are generated.

Therefore, in order to prevent such positional deviation, a method of firmly fixing the flexographic printing plate to the surface of the plate cylinder using a double-sided tape or a magnetic sheet or the like has been studied (for example, Patent Document 1 to Patent Document 4).

However, for example, a mainstream of a flexographic printing plate used in printing of a liquid crystal alignment film for a large liquid crystal display is a large-sized flexible printing plate in which one side exceeds 1.5 m, and if it is the fixing method, it is expensive to remove from the plate cylinder. Kung Fu, and if an adhesive layer or the like of a double-sided tape is inserted between the plate cylinder and the flexographic printing plate, the thickness thereof affects the flatness of the surface (printing surface) of the flexographic printing plate. Therefore, there is a problem that it is not suitable as a plate for forming a liquid crystal alignment film or the like.

In order to prevent the positional shift caused by the extension, a method of laminating a flexographic printing plate on a non-stretchable metal substrate has been studied, but the metal sheet which will become the basis of the metal substrate is not bent. When it is mounted on the plate cylinder, the larger the plate is, the more difficult it is. Therefore, there is a problem in that a flexographic printing plate having the laminated structure is not suitable as a large-sized liquid crystal alignment film forming plate or the like.

[Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 5-271630

[Patent Document 2] Japanese Patent Laid-Open No. Hei 5-246012

[Patent Document 3] Japanese Patent Laid-Open No. Hei 7-9669

[Patent Document 4] Japanese Patent Publication No. 7-27843

[Patent Document 5] Japanese Patent Laid-Open No. Hei 5-278357

An object of the present invention is to provide a flexographic printing plate and a method of manufacturing a liquid crystal display element using the same, which can be easily mounted and detached with respect to a plate cylinder even if it is large in area, and is mounted on a printing plate. The flatness of the printing surface at the time of the surface of the drum is excellent, and it is difficult to cause a positional shift on the surface of the plate cylinder even if it is reversely printed.

The present invention is a flexographic printing plate formed by a flat surface having a single side as a printing surface and an opposite surface facing a mounting surface of a plate cylinder, wherein the mounting surface has an arithmetic mean roughness Ra of a roughness curve of 0.02 μm or more. 0.06 μm or less, the maximum height roughness Rz is 0.25 μm or more and 1.60 μm or less, and the ten-point average roughness Rz _JIS is a rough surface of 0.20 μm or more and 0.80 μm or less.

Moreover, the present invention provides a method of producing a liquid crystal display device comprising the step of forming a liquid crystal alignment film of a substrate for a liquid crystal panel by flexographic printing using the flexographic printing plate.

According to the present invention, a flexographic printing plate and a liquid crystal display using the same can be provided In the method of manufacturing an element, the flexible printing plate can be easily attached and detached with respect to the plate cylinder even if it is large in area, and is excellent in flatness of the printing surface when mounted on the surface of the plate cylinder, and thus is suitable for liquid crystal display. The printing of the liquid crystal alignment film for the element is difficult to cause a positional shift on the surface of the plate cylinder even if the printing is repeated.

<Flexible Printing Edition>

The flexographic printing plate of the present invention is characterized in that a single surface is a printing surface and an opposite surface is a flat plate shape facing a mounting surface of the plate cylinder, and the mounting surface has an arithmetic mean roughness Ra of a roughness curve of 0.02 μm or more. 0.06 μm or less, the maximum height roughness Rz is 0.25 μm or more and 1.60 μm or less, and the ten-point average roughness Rz _JIS is a rough surface of 0.20 μm or more and 0.80 μm or less.

The conventional flexographic printing plate has a mounting surface that is in contact with the plate cylinder as a smooth surface, and is strongly adhered to the surface of the plate cylinder which is also a smooth surface, so as described above, even as the printing ends However, the force for releasing the shearing direction is not released and accumulated, and a positional shift occurs.

On the other hand, when the flexographic printing plate of the present invention is used, the mounting surface that is in contact with the plate cylinder is set to a rough surface that satisfies the above characteristics, thereby reducing the relative The adhesion of the surface of the plate cylinder can be easily and easily slid relative to the surface. Therefore, when the force in the shearing direction is released as the printing is completed, the extension of the flexographic printing plate can be released, and the extension of the extension can be prevented and the positional displacement can be prevented.

Further, the flexographic printing plate of the present invention can be formed in the same manner as the conventional flexographic printing plate except that the mounting surface is the rough surface, and it is not required to be a metal substrate or the like, and can be attached to the printing through the same mounting method as before. The surface of the plate roller is fixed without using double-sided tape or the like.

Therefore, even if the area is increased, the mounting and detachment with respect to the plate cylinder can be easily performed, and the flatness of the printing surface when mounted on the surface of the plate cylinder is excellent, so that it is suitable for printing of the liquid crystal alignment film for liquid crystal display elements. .

Further, in the present invention, the arithmetic mean roughness Ra, the maximum height roughness Rz, and the ten point average roughness Rz _{JIS of the} roughness curve are respectively limited to the ranges described above for the following reasons.

That is, in the case where any of the three kinds of roughness is less than the respective ranges, the roughening of the mounting surface is insufficient, and the adhesion to the surface of the plate cylinder is reduced, and the surface is not obtained for the surface. Moderately easy to slide. Therefore, at the time of reverse printing, the extension is accumulated and a positional shift occurs.

On the other hand, when any one of the three kinds of roughness exceeds the respective ranges, the roughening of the mounting surface is excessive, and the adhesion to the surface of the plate cylinder becomes too low, too much for the surface. Easy to slide. Therefore, it becomes easy to extend when a force in the shearing direction is applied at the time of printing, and in particular, it is easy to cause a shift in the pitch due to the overall extension of the printed pattern.

On the other hand, by adjusting the three types of roughness to the respective ranges, the adhesion force with respect to the surface of the plate cylinder can be appropriately reduced as described above, and the surface can be easily slid easily, thereby realizing Even if it is printed repeatedly, it is difficult to cause a positional shift on the surface of the plate cylinder.

Further, in the present invention, the three kinds of roughness are expressed by the following values, which are based on Japanese Industrial Standard JIS B0601:2001 "Geometry Specifications (GPS) - Surface Properties: Profile Curve Method - Terminology," The measurement method specified in the definition and surface property parameters was measured using a laser microscope VK-9500 manufactured by KEYENCE Co., Ltd.

The flexographic printing plate of the present invention can be configured in the same manner as before except that the mounting surface is the rough surface.

For example, a flexographic printing plate can be produced by roughening a sheet (the roughened sheet is used to make the printing surface of the flexographic printing plate into any rough surface in consideration of the acceptability of the ink, etc.) The reinforcing sheet constituting the mounting surface of the flexographic printing plate is held in a parallel flat shape at a predetermined interval, and a photosensitive resin composition is interposed therebetween, and the photosensitive resin composition is cured by irradiation with ultraviolet rays or the like, and then roughened. Sheet peeling, etc.

The flexographic printing plate produced by the above steps has a two-layer structure in which a hardened layer containing a cured product of a photosensitive resin composition is laminated on one surface of the reinforcing sheet, and the opposite side of the reinforcing sheet side of the hardened layer becomes On the printing surface, the opposite side of the hardened layer side of the reinforcing sheet becomes a mounting surface.

The printing surface transfers the uneven shape of the peeled roughened sheet and is rough Face.

In addition, in order to make the mounting surface a rough surface satisfying the three types of roughness described above, as the reinforcing sheet, a reinforcing sheet in which the rough surface is formed in advance on the opposite side to the hardened layer side of the mounting surface is selected. Just use it.

Thereby, even if it is a large-area flexible printing plate corresponding to a large liquid crystal display, for example, the entire surface of the mounting surface can be a uniform rough surface satisfying three kinds of roughness.

The reinforcing sheet may use, for example, polyethylene (PE), polypropylene (PP), thermoplastic polyurethane elastomer (TPU), polyethylene terephthalate ( Polyethylene terephthalate (PET), a thermoplastic resin such as tetrafluoroethylene-fluorinated ethylene propylene (FEP), and a sheet having one or both sides of a rough surface satisfying three kinds of roughness.

Specific examples of the reinforcing sheet include Lumirror (registered trademark) S10 manufactured by Toray Co., Ltd. [PET sheet, Ra: 0.047 μm, Rz: 1.064 μm, Rz _JIS : 0.451 μm], Cosmoshine (registered trademark) A4300 (PET sheet, Ra: 0.024 μm, Rz: 0.516 μm, Rz _JIS : 0.291 μm) manufactured by Toyobo Co., Ltd., and the like.

The photosensitive resin composition is, for example, a composition comprising a prepolymer having a 1,2-butadiene structure and having a vinyl double bond at the terminal, a vinyl unsaturated monomer, and a photopolymerization initiator. Things and so on.

As the photopolymerization initiator, a benzoin alkyl ether is preferred, and it is especially preferred When the ratio of the benzoin is 500 ppm or less in the total amount of the photosensitive resin composition, the benzoin is caused to react by visible light from a fluorescent lamp or the like to cause yellowing of the flexographic printing plate. Thus, a flexographic printing plate excellent in weather resistance which is not yellowed in a short period of time can be obtained.

<Method of Manufacturing Liquid Crystal Display Element>

The present invention is a method for producing a liquid crystal display element comprising the step of forming a liquid crystal alignment film of a substrate for a liquid crystal panel by flexographic printing using the flexographic printing plate of the present invention.

According to the present invention, it is possible to manufacture a liquid crystal display element comprising a liquid crystal alignment film which is uniform in thickness and excellent in reproducibility of thickness, and which has no pinholes, and which is not printed based on positional shift of a flexographic printing plate. The offset of the starting position or the offset of the pitch due to the extension of the entire printed pattern.

Other steps of the manufacturing method of the present invention can be carried out in the same manner as before.

In other words, a transparent electrode layer corresponding to a predetermined matrix pattern or the like is formed on the surface of a transparent substrate such as a glass substrate, and a liquid crystal alignment film is formed by flexographic printing using the flexographic printing plate of the present invention, and further, if necessary, by rubbing or the like The surface of the liquid crystal alignment film is subjected to an alignment treatment to produce a substrate for a liquid crystal panel.

Then, two liquid crystal panel substrates are prepared, and the liquid crystal material is sandwiched between the two liquid crystal panel substrates while the respective transparent electrode layers are aligned, and the laminate is fixed to each other to form a laminate. A liquid crystal display element was produced by disposing a polarizing plate on both outer sides of the laminate.

[Examples]

<Example 1>

(enhanced sheet)

As a reinforced sheet constituting the mounting surface of the flexographic printing plate, Lumirror (registered trademark) S10 manufactured by Toray Co., Ltd., which is described above, is prepared. [PET sheet, Ra: 0.047 μm, Rz A sheet having a thickness of 250 μm in 1.064 μm and Rz _JIS : 0.451 μm was bonded together.

(rough surfaced sheet)

As a roughened sheet, the exposed TPU surface of a TPU sheet (Silklon (registered trademark) SNESS 80-150 μm manufactured by Okura Kogyo Co., Ltd.) having a PET sheet having a thickness of 100 μm was attached as a surface. A roughened sheet of a roughened facet.

(Manufacture of flexible printing plates)

The reinforced sheet and the roughened sheet were held in a parallel plate shape at intervals of about 2.4 mm, and a photosensitive resin composition [NK resin manufactured by Sumitomo Rubber Industries Co., Ltd.] was sandwiched therebetween to irradiate ultraviolet rays. After the photosensitive resin composition was cured, the roughened sheet was peeled off to produce a flexographic printing plate.

Regarding the mounting surface of the flexographic printing plate, the arithmetic mean roughness Ra is 0.047 μm, the maximum height roughness Rz is 1.064 μm, and the ten-point average roughness Rz _JIS is based on the surface properties of the reinforcing sheet which is the basis thereof. 0.451 μm.

<Example 2>

As a reinforced sheet, the thickness of Cosmoshine (registered trademark) A4300 [PET sheet, Ra: 0.024 μm, Rz: 0.516 μm, Rz _JIS : 0.291 μm] manufactured by Toyobo Co., Ltd., which is described above, is prepared. It is made of a sheet of 250 μm. Further, a flexographic printing plate was produced in the same manner as in Example 1 except that the reinforcing sheet was used.

Regarding the mounting surface of the flexographic printing plate, the arithmetic mean roughness Ra is 0.024 μm, the maximum height roughness Rz is 0.516 μm, and the ten-point average roughness Rz _JIS is based on the surface properties of the reinforcing sheet which is the basis thereof. 0.291 μm.

<Comparative Example 1>

As a reinforced sheet, the thickness of the Lumirror H10 [PET sheet, Ra: 0.062 μm, Rz: 1.642 μm, Rz _JIS : 0.860 μm] manufactured by Toray Co., Ltd. was prepared to be 250 μm. The sheet is laminated. Further, a flexographic printing plate was produced in the same manner as in Example 1 except that the reinforcing sheet was used.

Regarding the mounting surface of the flexographic printing plate, the arithmetic mean roughness Ra is 0.062 μm, the maximum height roughness Rz is 1.642 μm, and the ten-point average roughness Rz _JIS is based on the surface properties of the reinforcing sheet which is the basis thereof. 0.860 μm.

<Comparative Example 2>

As a reinforced sheet, a sheet having a thickness of 250 μm in two Lumirror T60 [PET sheets, Ra: 0.018 μm, Rz: 0.218 μm, RzJIS: 0.160 μm] manufactured by Toray Co., Ltd. was prepared. The material is laminated. Further, a flexographic printing plate was produced in the same manner as in Example 1 except that the reinforcing sheet was used.

Regarding the mounting surface of the flexographic printing plate, the arithmetic mean roughness Ra is 0.018 μm, the maximum height roughness Rz is 0.218 μm, and the ten-point average roughness Rz _JIS is based on the surface properties of the reinforcing sheet which is the basis thereof. 0.160 μm.

<true machine test>

(flexible printing)

The flexographic printing plates produced in the respective examples and comparative examples were mounted on a plate cylinder of a flexographic printing machine [G3 machine manufactured by Nakan Techno Co., Ltd.], and a chromium vapor-deposited film was formed thereon. The surface of the glass substrate is flexographically printed.

Further, on the flexographic printing plate, an alignment mark is formed as a printed pattern at a total of four places on the left and right sides of the printing start position and the printing end position.

Further, if there is no positional shift of the flexographic printing plate on the glass substrate, the alignment marks are patterned at four locations that coincide with the alignment marks.

Further, the function of the image processing apparatus incorporated in the flexible printing press is set such that at the end of printing, a new glass substrate is set at the original position with reference to the alignment mark.

(Evaluation of position offset 1)

Each of the flexographic printing plates is mounted on the plate cylinder of the flexible printing machine, and the alignment marks are continuously printed on the surface of the 1000 glass substrates, and the alignment marks are printed on the surface of one glass substrate to measure the printing of the glass substrate. The offset amount of the alignment mark of the start position from the printing direction of the alignment mark printed thereon is the offset (μm) of the printing start position due to the accumulation of the extension.

Moreover, the distance between the printed printing start position and the alignment mark of the end position is measured, and the amount of extension with respect to the printing direction of the original distance is taken as The offset (μm) of the pitch due to the overall extension of the printed pattern based on the extended accumulation.

In addition, the case where the shift of the printing start position was 1000 μm or more was evaluated as defective, and the case where the shift was less than 1000 μm was evaluated as good. Further, the case where the shift of the pitch was 400 μm or more was evaluated as defective, and the case where the shift was less than 400 μm was evaluated as good.

Further, the case where any one of the defects was defective was regarded as a deviation due to the extension accumulation, and the evaluation was a failure, and the case where both were good was regarded as no offset, and the evaluation was good.

(Evaluation of positional shift II)

Each of the flexographic printing plates is mounted on the plate cylinder of the flexible printing machine, and the offset (μm) and the pitch (μm) of the printing start position at the initial stage of printing from the first to the fifth blocks at the start of printing are measured. , respectively, the average value is obtained.

In addition, the case where the average value of the offset of the printing start position was 1000 μm or more was evaluated as defective, and the case where the average value of the offset was less than 1000 μm was evaluated as good. Further, the case where the average value of the pitch shift was 400 μm or more was evaluated as defective, and the case where the average value of the pitch was less than 400 μm was evaluated as good.

Further, the case where any one of the defects was defective was regarded as having an initial shift, and the evaluation was a failure, and the case where both were good was regarded as no offset, and the evaluation was good.

The above results are shown in Table 1.

According to the results of Comparative Example 1 of Table 1, it is understood that the arithmetic mean roughness Ra, the maximum height roughness Rz, and the ten-point average roughness Rz _JIS of the roughness curve of the mounting surface exceed the range specified in the present invention. In this case, the roughening of the mounting surface is excessive, the adhesion to the surface of the plate cylinder becomes too low, and the surface is too easy to slide with respect to the surface, and as a result, a force in the shearing direction is applied at the time of printing due to the printing pattern. The overall extension causes a shift in the pitch.

On the other hand, according to the results of Comparative Example 2, in the case where the three kinds of roughness are less than the range defined in the present invention, the roughening of the mounting surface is not sufficient, and the surface of the plate cylinder is closely attached. The force is reduced, and the effect of being easily slidable with respect to the surface is not obtained. As a result, there is no problem in the initial stage of printing, but the film is stretched and accumulated at the time of reverse printing, and the positional shift of the printing start position occurs.

On the other hand, according to the results of the first embodiment and the second embodiment, when the three types of roughness are within the range defined by the present invention, the roughening of the mounting surface is moderate, from the initial stage of printing to continuous The offset of the pitch or the positional shift of the printing start position due to the extension of the entire printed pattern can be suppressed at all times after printing As small as possible.

Claims (2)

A flexographic printing plate which is a flexographic printing plate for forming a liquid crystal alignment film for a substrate for a liquid crystal panel by flexographic printing, the flexographic printing plate being characterized in that one side is a printing surface and the opposite side is a printing side The flat surface of the mounting surface of the plate cylinder is such that the arithmetic mean roughness Ra of the roughness curve is 0.02 μm or more and 0.06 μm or less, and the maximum height roughness Rz is 0.25 μm or more and 1.60 μm or less, and the ten point average The roughness Rz _JIS is a rough surface of 0.20 μm or more and 0.80 μm or less. A method for producing a liquid crystal display device, comprising the step of forming a liquid crystal alignment film of a substrate for a liquid crystal panel by flexographic printing using the flexographic printing plate according to claim 1 of the patent application.