Print version

Abstract

In order to improve the uniformity of the film thickness of the alignment film formed by coating ink (alignment film material) onto the transparent electrode surface constituting the liquid crystal panel, the printing plate (P) has a printing protrusion (2) on the top surface having a plurality of protrusions (3) distributed thereon. The plurality of protrusions (3) are arranged in each column. For each protrusion (3) constituting the column, they are arranged parallel and separated from each protrusion (3) constituting other columns. And for each protrusion (3) constituting other columns, the positions of the protrusions (3) in the direction of arrangement are staggered. The top surface shape of the protrusions (3) is circular. The ratio of the shallowest depth of the gap (4) between the protrusions to the deepest depth of the gap (4) between the protrusions (the shallowest depth of the gap between the protrusions / the deepest depth of the gap between the protrusions) is 0.4 or more.

Description

Technical Field

[0001] This invention relates to a printing plate used in flexographic printing and other printing processes. Background Technology

[0002] The liquid crystal panel is configured to include an array substrate, a color filter substrate disposed opposite to the array substrate, and a liquid crystal layer sandwiched between the array substrate and the color filter substrate. The array substrate, for example, includes a transparent substrate, a gate electrode, a gate insulating film, a semiconductor layer, a first protective film, a source electrode, a drain electrode, a second protective film, and a resin film. Furthermore, a narrow, tapered contact hole is formed on the second protective film and the resin film on the surface of the drain electrode. The surface of the drain electrode is exposed by this contact hole. A transparent electrode is formed on the resin film using a sputtering method or the like, and the transparent electrode is electrically connected to the drain electrode at the bottom of the contact hole.

[0003] By coating an alignment film material such as polyimide onto the transparent electrode and resin film and filling the contact holes, an alignment film can be integrally formed on the surface of the transparent electrode, etc. Examples of methods for coating the alignment film material include flexible printing and inkjet printing.

[0004] Here, as in Figure 7 In (a) shown in a top view and in Figure 7 (b) of Figure 7 As shown in the TT cross-sectional view of (a), the printing plate P1 used to form an alignment film in flexographic printing generally has a flat base 11 and a printing protrusion 12 formed in the center of the surface of the base 11. The printing protrusion 12 is the aforementioned printing area, and the portion of the base 11 surrounding the printing protrusion 12 does not participate in printing. Furthermore, as in... Figure 7 In (c) Figure 7 As shown in the enlarged cross-sectional view of the main part of (b), multiple protrusions 13 are distributed and spaced apart by gaps 14 on the top surface of the printing protrusion 12, where ink is retained. Furthermore, the printing plate P1 is flexible so that it can move along the printing plate cylinder 51 (see reference 12). Figure 6 Install it on the surrounding side.

[0005] Figure 8 (a) is a top view showing the protrusion 13 formed in the printing protrusion 12 described above. Figure 8 (b) is a schematic diagram representing the protrusion 13 in three dimensions.

[0006] like Figure 8 of (a), Figure 8 As shown in (b), the multiple protrusions 13, with their top surfaces 13a being circular, are arranged orthogonally on the printing protrusions 12. Furthermore, Figure 8of (a), Figure 8 The protrusions 13 shown in (b) are minute; in this example, 400 protrusions 13 are formed per inch (160,000 per square inch) of the printing protrusions 12.

[0007] Figure 8 In (a), the arrows indicate distances S11 and S12, which represent the spacing (center-to-center distance) between adjacent protrusions 13. Distance S11 represents the lateral spacing between protrusions 13, which is 63.5 μm (the same applies in the longitudinal direction). On the other hand, distance S12 represents the oblique spacing between protrusions 13, which is 89.8 μm.

[0008] Here, Figure 9 This is a schematic top view showing the arrangement of the protrusions 13 formed on the printing protrusions 12. As previously mentioned, the protrusions 13 are arranged orthogonally. The diamond-shaped area G11, indicated by fine lines and surrounded by each protrusion 13, becomes the gap 14 and is the part that holds the ink.

[0009] Figure 10 This is a top view showing the protrusion 13 formed on the printing protrusion 12 as enlarged. Figure 11 (a) shows the representation Figure 10 The curve showing the elevation difference of the W1-W1 profile. Figure 11 (b) shows the representation Figure 10 A curve showing the elevation difference of the W2-W2 profile. Figure 10 and Figure 11 The depth of position A between the protrusions 13 shown in (a) (the depth from which the top surface of the protrusion 13 is referenced, and the same applies below) is 19.07 μm. Figure 10 and Figure 11 As shown in (b), the depth of position B between the protrusions 13 is 4.65 μm. Furthermore, in this example, since the top surface 13a of the protrusions 13 is circular, the amount of ink that the gap 14 surrounded by these protrusions 13 can retain is greater than that retained when the top surface is polygonal or similar. The unit volume (in terms of ink holding capacity) of the printing plate P1 equipped with the printing protrusions 12 formed with the protrusions 13 is 4.60 cm³. 3 / m 2 .

[0010] Existing technical documents

[0011] Patent documents

[0012] Patent Document 1: Japanese Patent Application Publication No. 2017-164979 Summary of the Invention

[0013] The problem the invention aims to solve

[0014] In order to use such a printing plate P1 to coat ink (alignment film material) on a transparent electrode, the ink is held between orthogonally arranged tiny protrusions 13 (gap portion 14), and the printing plate P1 is brought into contact with the substrate Q (an array substrate or color filter substrate on which the alignment film is not formed), thereby transferring the ink to the substrate Q.

[0015] At this time, if the depth deviation between the protrusions 13 formed by the printing protrusions 12 on the printing plate P1 is large, the difference in the amount of ink held in the gap 14 will increase depending on the location. Therefore, there is a situation where, although the amount of ink held is sufficient, the uniformity of the obtained alignment film deteriorates. For Figure 8 Based on the values ​​in the examples above, the shallowest depth M1 is 4.65 μm and the deepest depth M2 is 19.07 μm. The ratio of the shallowest depth to the deepest depth (M1 / M2) is 0.24 (≒4.65 / 19.07) (Regarding M1 and M2, refer to...). Figure 11 of (a), Figure 11 (b)

[0016] Furthermore, when the printed substrate Q is an array substrate, the ink is repelled around the contact holes formed on the array substrate due to surface tension and tiny debris (residue) generated during contact hole formation. This prevents the ink from fully penetrating the contact holes, resulting in a difference in the thickness of the alignment film around the contact holes compared to other areas. When the liquid crystal panel is in an emitting state (especially halftone), the uneven thickness of the alignment film becomes noticeable as brightness inconsistencies, thus requiring a higher level of film thickness uniformity.

[0017] The present invention was made in view of the following circumstances, and its object is to provide a printing plate that improves the uniformity of the film thickness of the alignment film.

[0018] Solution for solving the problem

[0019] To achieve the above objectives, the printing plate of the present invention has the following structure, which includes a printing protrusion having a plurality of protrusions distributed on its top surface, wherein the plurality of protrusions are arranged in each column, and each protrusion constituting each column is arranged parallel and separated from each protrusion constituting other columns, and is arranged in a staggered manner relative to each protrusion constituting other columns in the direction of the protrusion arrangement.

[0020] That is, when the depth deviation of the gaps between the protrusions is large, the film uniformity of the alignment film deteriorates. In view of this, the film uniformity of the alignment film can be improved by suppressing the depth deviation of the gaps between the protrusions. In addition, there is a case where the film thickness of the alignment film becomes thicker around the contact hole, but this can be avoided by improving ink repulsion around the contact hole.

[0021] The inventors of the present invention have discovered, with regard to the above aspects, that by seeking to maintain sufficient ink quantity in the gaps between the protrusions and to ensure uniformity of ink retention in each gap, the depth deviation of the gaps between the protrusions is suppressed, and ink repulsion at the periphery of the contact hole is improved, thereby enhancing the film uniformity of the alignment film.

[0022] In order to achieve the above objectives, the present invention provides the following [1] and [2].

[0023] [1] A printing plate having a printing protrusion having a plurality of protrusions distributed on its top surface, characterized in that the plurality of protrusions are arranged in each column, and for each protrusion constituting each column, they are arranged parallel and separated from each protrusion constituting other columns, and are arranged in a staggered manner in the direction of arrangement of the protrusions relative to each protrusion constituting other columns, the top surface of the protrusions is circular, and the ratio (M1 / M2) of the shallowest depth M1 of the gap between the protrusions to the deepest depth M2 of the gap between the protrusions is 0.4 or more.

[0024] [2] In the printing plate described in [1], the above-mentioned protrusions are arranged to be equidistant from each of the adjacent protrusions arranged in the six directions around them.

[0025] The effects of the invention

[0026] In the printing plate of the present invention, a plurality of protrusions are arranged on each column. For each protrusion constituting the column, they are arranged in a parallel and spaced manner relative to each protrusion constituting other columns, and are arranged in a staggered manner relative to each protrusion constituting other columns in the direction of the protrusion arrangement.

[0027] Therefore, compared to the case where the top surface of the protrusion is circular and the protrusions are arranged orthogonally as in the past, the spacing between the protrusions can be shortened, multiple gaps between the protrusions can be provided in the same area, and the possibility of the gaps being located on the contact holes during printing can be increased.

[0028] If the aforementioned gaps are located on the contact holes, sufficient ink held by the gaps between the protrusions can be efficiently filled into the contact holes, thus suppressing ink repulsion around the contact holes. As a result, the film uniformity of the alignment film can also be improved around the contact holes.

[0029] Furthermore, when each protrusion is configured to have an equal distance from each of the adjacent protrusions arranged in the six surrounding directions, the uniformity of the orientation film can be further improved because the protrusions are spaced at the same narrow interval. Attached Figure Description

[0030] Figure 1 This schematically illustrates one embodiment of the printing plate of the present invention. Figure 1 (a) is a top view of the printed plate. Figure 1 (b) is Figure 1 Enlarged view of the main part at the RR section of (a).

[0031] Figure 2 (a) is a top view showing the protrusion formed by the printing relief provided in the printing plate according to an embodiment of the present invention. Figure 2 (b) is a three-dimensional representation of the protrusion.

[0032] Figure 3 This is a top view schematically illustrating the arrangement of the protrusions in this invention.

[0033] Figure 4 This is a top view showing the protrusions formed by the printing reliefs in the printing plate of the present invention.

[0034] Figure 5 (a) indicates the use of Figure 4 A curve showing the height difference formed on the printing protrusion due to the aforementioned protrusions and gaps when viewed from the side in section V1-V1. Figure 5 (b) indicates the use of Figure 4 A curve showing the height difference formed on the printing protrusion due to the aforementioned protrusions and gaps when viewed from the side in the V2-V2 cross section.

[0035] Figure 6 It is an illustrative diagram showing a printing press using printing plates.

[0036] Figure 7 This is a schematic representation of previous printing plates. Figure 7 (a) is a top view of the printed plate. Figure 7 (b) is Figure 7 (a) TT sectional view, Figure 7 (c) is Figure 7Enlarged cross-sectional view of the main part of (b).

[0037] Figure 8 (a) is a top view showing the protrusions formed by printing reliefs in conventional printing plates. Figure 8 (b) is a three-dimensional representation of the protrusion.

[0038] Figure 9 It is a top view that schematically represents the previous arrangement of protrusions.

[0039] Figure 10 It is a top view that enlarges the projection formed by the printing reliefs present in conventional printing plates.

[0040] Figure 11 (a) indicates the use of Figure 10 A curve showing the height difference formed on the printing protrusion due to the aforementioned protrusions and gaps when viewed from the side in section W1-W1. Figure 11 (b) indicates the use of Figure 10 A curve showing the height difference formed on the printing protrusion due to the aforementioned protrusions and gaps when viewed from the side in the W2-W2 cross section. Detailed Implementation

[0041] Embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0042] However, the present invention is not limited to the embodiments described below.

[0043] Furthermore, in this specification, when expressed as "F or above" (F being any number), it also includes the meaning of "preferably greater than F".

[0044] Furthermore, in this specification, when expressed as "X~Y" (where X and Y are arbitrary numbers), unless otherwise specified, it means "more than X and less than Y", as well as "preferably greater than X" or "preferably less than Y".

[0045] Figure 1 (a) is a top view showing a printed plate P as an embodiment of the present invention. Figure 1 (b) is Figure 1 Enlarged view of the main part of the RR section in (a).

[0046] In one embodiment of the present invention, the printing plate P includes a base 1 that is rectangular in shape when viewed from above, and a printing protrusion 2 that is rectangular in shape when viewed from above and formed at the center of the surface of the base 1. A plurality of protrusions 3 (see reference) are formed on the top surface of the printing protrusion 2. Figure 2The printing plate P is used for flexographic printing, such as... Figure 6 As shown, the printing plate P is flexible so that it can be mounted on the peripheral side of the printing plate cylinder 51 of the printing press. The material used to form such a printing plate P is, for example, photosensitive resin, rubber, etc.

[0047] The base 1, printing protrusion 2, and protrusion 3 are integrally formed. Furthermore, in this embodiment, the direction of the arrow along the long side of the rectangular printing protrusion 2 (viewed from above) is set as the printing direction. As shown below, multiple protrusions 3 are distributed and spaced apart by gaps 4 on the top surface of the printing protrusion 2, where ink is held.

[0048] Figure 2 (a) is a top view showing the protrusion 3 formed in the printing relief 2. Figure 2 (b) is a three-dimensional schematic diagram representing the three parts of the protrusion. For example... Figure 2 of (a), Figure 2 As shown in (b), on the printing protrusion 2, a plurality of circular protrusions 3 on the top surface 3a are arranged in each of a plurality of columns. Each protrusion 3 constituting one column is arranged parallel to, and spaced apart from, the protrusions 3 constituting other columns. Furthermore, the protrusions 3 constituting one column are arranged in a staggered manner relative to the protrusions 3 constituting other columns, such that their positions in the direction of arrangement are offset.

[0049] Furthermore, the aforementioned protrusions 3 are arranged in a manner in which the distances between the protrusions 3 in the six adjacent surrounding directions are equal (honeycomb arrangement).

[0050] in addition, Figure 2 of (a), Figure 2 The protrusions 3 shown in (b) are minute; for example, 184,752 protrusions 3 are formed per square inch in the printing relief 2. In contrast to... Figure 8 In comparison with the previous protrusion 13 exemplified above, it is 1.15 times (≒184,752 / 160,000) times the previous protrusion 13.

[0051] Figure 2 The distances S (S1 to S3) indicated by the arrows in (a) represent the spacing (center-to-center distance) between adjacent protrusions 3. Distances S1 to S3 are all the same. For example, the distance S (S1 to S3) is 63.5 μm. Furthermore, the diameter C of the top surface 3a of the protrusion 3 is, for example, 44.7 μm, and the ratio (S / C) of the aforementioned distance S to the length of the diameter C is 1.42.

[0052] Figure 3This is a schematic top view showing the arrangement of the protrusions 3. As described above, the plurality of protrusions 3 are formed in a row on the printing protrusion 2. Each protrusion 3 constituting a row is arranged parallel to and separated from the protrusions 3 constituting other rows, and is arranged in a staggered position relative to the protrusions 3 constituting other rows. The triangular region G1, indicated by thin lines and surrounded by the protrusions 3, is the ink-retaining portion (gap 4).

[0053] Figure 4 This is a top view showing the protrusion 3 formed on the printing relief 2 in an enlarged manner. Figure 5 (a) indicates the use of Figure 4 A curve showing the height difference formed in the printing protrusion 2 due to the protrusion 3 and the gap 4 when viewed from the side section of V1-V1. Figure 5 (b) indicates the use of Figure 4 A curve showing the height difference formed in the printing protrusion 2 due to the protrusion 3 and the gap 4 when viewed from the side in the V2-V2 cross section.

[0054] Figure 4 The depth of position A between the protrusions 3 shown is as follows Figure 5 As shown in (a), the depth is 14.91 μm, and it is the deepest depth M2 in the gap 4. Furthermore, Figure 4 The depth of position B between the protrusions 3 shown is as follows Figure 5 (b) shows a depth of 11.03 μm, which is the shallowest depth M1 in the gap 4.

[0055] Therefore, in this example, the ratio (M1 / M2) of the shallowest depth M1 to the deepest depth M2 is 0.74 (≒11.03 / 14.91). Furthermore, the unit volume of the printing plate P with the aforementioned protrusions 3 is 4.54 cm³. 3 / m 2 Furthermore, the values ​​mentioned above are just examples.

[0056] As a method for forming such a printing plate P, photolithography can be cited as an example. This photolithography method includes: a step of fabricating a negative film with a predetermined pattern; a step of placing the negative film on a photosensitive resin that becomes the printing plate P; and a step of irradiating the photosensitive resin on which the negative film is placed with light and curing the photosensitive resin at the locations where the light passes through the negative film. The photosensitive resin portions that solidify after passing through the negative film and being irradiated by the light become the protrusions 3. The photosensitive resin portions that are not irradiated by the light after not passing through the negative film become the gaps 4.

[0057] That is, in order to create a protrusion 3 with a circular top surface 3a, it is only necessary to form a pattern with multiple circles on the negative. Furthermore, since it is only necessary for the top surface 3a of the obtained protrusion 3 to be circular, the circles in the above pattern include not only perfect circles, but also circles whose shapes take into account the precision errors of the photolithography method.

[0058] Flexible printing utilization Figure 6 The printing press shown is used for printing. The printing press includes: a cylindrical printing plate cylinder 51 on which a printing plate P is mounted; an anilox roller 52 on which ink is applied to the printing plate P; an ink supply device 53 for supplying ink to the surface of the anilox roller 52; a doctor blade 54 for scraping off the remaining ink from the surface of the anilox roller 52; and a printing table 55 on which the printable object Q is placed.

[0059] Furthermore, flexographic printing using the aforementioned printing press is performed as follows: A printing plate P is mounted on the circumferential side of a printing plate cylinder 51, which is then rotated. Simultaneously, ink supplied from the ink supply device 53 is applied to the printing area of ​​the printing plate P via an anilox roller 52. This applied ink is then transferred to a substrate Q, such as a glass substrate, placed on a printing table 55, thereby performing printing. At this time, the printing table 55 slides synchronously with the rotation of the printing plate cylinder 51.

[0060] Here, in print version P, as Figure 2 As shown in (b), on the top surface of the printing protrusion 2, a plurality of protrusions 3 are distributed and formed with gaps 4 between them, and ink is held in the gaps 4.

[0061] When ink (alignment film material) is applied to a substrate Q (e.g., a transparent electrode) using a printing plate P, for example, to form an alignment film for a liquid crystal panel, the ink flows into a plurality of gaps 4 formed on the printing protrusion 2, and is transferred from the printing plate P in this state to the substrate Q.

[0062] In the aforementioned printing plate P, as described above, the plurality of protrusions 3 are arranged in a row on the printing protrusion 2. For each protrusion 3 constituting the row, they are arranged parallel and separated from each protrusion 3 constituting the other rows, and the positions of the protrusions 3 in the direction of arrangement are staggered relative to each protrusion 3 constituting the other rows.

[0063] Therefore, with use Figure 7 and Figure 8 Compared to the conventional printing plate P1 in which the protrusions 13 are arranged orthogonally, the spacing between each protrusion 3 is shorter, which can suppress the deviation in depth of the gap 4 between each protrusion 3.

[0064] As a result, the deviation in ink retention and ink transfer in each gap is reduced, and the uniformity of the alignment film is improved.

[0065] Furthermore, in a printing plate P according to one embodiment of the present invention, the spacing between the aforementioned protrusions 3 is relatively short, forming a plurality of gaps 4 in a dense manner (see reference). Figure 3 This can also be seen by comparing it with the protrusions 13 and gaps 14 formed in the previous printing plate P1 (see reference). Figure 9 ).

[0066] Thus, in the printing plate P of one embodiment of the present invention, since minute irregularities are formed in the printing protrusion 2, it is more likely that the gap portion 4 will be arranged at the position overlapping with the contact hole during printing. Ink will not be repelled near the contact hole, and the contact hole can be filled with ink. Consequently, the film uniformity of the alignment film around the contact hole is also improved.

[0067] Furthermore, in the aforementioned printing plate P, the protrusions 3 are arranged with equal distances to each of the adjacent protrusions arranged in the six directions around them. Therefore, the protrusions 3 are spaced at the same distance and are narrowly spaced, further improving the uniformity of the alignment film at the periphery of the contact hole.

[0068] Furthermore, in this embodiment, since the protrusion 3 is fabricated using photolithography, the shape of the top surface 3a of the protrusion 3 is circular, which includes not only perfect circles but also circles that exhibit deformation or offset due to the fabrication method described above. Examples of shapes that exhibit deformation or offset include ellipses with a flattening ratio exceeding 0 but less than 0.2.

[0069] Furthermore, in the aforementioned printing plate P, for each of the aforementioned protrusions 3, the ratio (M1 / M2) of the shallowest depth M1 to the deepest depth M2 of the gap 4 between adjacent protrusions 3 is formed to be 0.74, but it can also be set to any other arbitrary ratio.

[0070] However, from the perspective of further improving the uniformity of the orientation film, the ratio (M1 / M2) of the shallowest depth M1 to the deepest depth M2 in terms of the depth of the gap 4 between the adjacent protrusions 3 is preferably 0.4 or more, more preferably 0.5 or more, even more preferably 0.6 or more, and even more preferably 0.7 or more.

[0071] Furthermore, in the aforementioned printing plate P, the diameter C of the top surface 3a of the protrusion 3 is formed to be 44.7 μm, but the diameter C is not limited to this. However, from the viewpoint of ink retention and flowability, the diameter C is preferably 10 μm to 70 μm, and more preferably 15 μm to 60 μm.

[0072] Furthermore, in the aforementioned printing plate P, the ratio (S / C) of the distance S between each protrusion 3 to the length of the diameter C of the top surface 3a is set to 1.42, but the length ratio (S / C) is not limited to this. However, from the perspective of effectively controlling the flow of ink held by the gap 4 during printing, the length ratio (S / C) is preferably 1.15 to 3, more preferably 1.25 to 2.5.

[0073] The above embodiments illustrate specific aspects of the present invention, but these embodiments are merely illustrative and not intended to be limiting. It is possible to implement various modifications known to those skilled in the art within the scope of this invention.

[0074] Industrial availability

[0075] The printing plate of this invention is useful as a printing plate for improving the uniformity of the film thickness of the alignment film.

[0076] Explanation of reference numerals in the attached figures

[0077] P, printing plate; 2, printing relief; 3, protrusion; 3a, top surface.

Claims

1. A flexible printing plate having printing protrusions, wherein the printing protrusions have a plurality of protrusions distributed on their top surface, characterized in that, The plurality of protrusions are arranged in each column, and each protrusion constituting a column is arranged parallel and spaced apart from the protrusions constituting other columns, and is staggered in position relative to the protrusions constituting other columns in terms of their arrangement direction. Each protrusion is configured to be equidistant from each of its adjacent protrusions arranged in the six surrounding directions. The protrusion appears circular when viewed from above. When viewed in a side section, from one protrusion to any of the six protrusions arranged in the surrounding six directions adjacent to that protrusion, there is a recess between the protrusion and the other protrusion. When a side sectional view is taken of the nearest protrusion visible between two adjacent protrusions, from a certain protrusion to the protrusions arranged in six directions around it, there are two recesses and one protrusion between the certain protrusion and the nearest protrusion. The depth of the recess is the shallowest depth M1 in the gap between the protrusions. The depth of at least one of the two recesses is the deepest depth M2 in the gap between the protrusions. The ratio of the shallowest depth M1 of the gap between the protrusions to the deepest depth M2 of the gap between the protrusions, i.e., M1 / M2, is 0.4 or more.

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