KR20200095816A - Method of forming bezel patterns using continuous multiple printing - Google Patents

Abstract

The present invention relates to a method of forming a bezel pattern by inkjet printing using a roll-to-roll process. The method includes: (S1) unwinding a base film at one side and rewinding at the other side while transferring the base film in roll-to-roll; (S2) stopping the transferred base film on a work table disposed between a guide roll for driving the base film and a tension roll for providing a tension to the base film; (S3) while the base film stops, performing surface treatment, pattern printing, and ultraviolet curing of the printed pattern on the stopping base film through a vertical movement of a printing module installed on the top of the work table and including a surface treatment device, an inkjet head and a curing device; (S4) repeating step S3 to form a multilayer printed pattern; and (S5) re-transferring the patterned base film. According to the present invention, while the base film transferred in roll-to-roll temporarily stops on the worktable, the surface treatment of the base film, pattern printing, and ultraviolet curing of the printed pattern are repeatedly performed several times, so that multi-layer printing of 2 degrees or more is continuously and precisely performed, thereby forming a bezel pattern having a high resolution.

Description

Method of forming bezel pattern through continuous multi-layer printing{METHOD OF FORMING BEZEL PATTERNS USING CONTINUOUS MULTIPLE PRINTING}

The present invention relates to a method of forming a bezel pattern through continuous multilayer printing, and more specifically, by applying a roll-to-roll method to an inkjet printing process, continuous multilayer printing is possible and a bezel pattern can be accurately formed. It is about how to form.

A bezel, which is a non-display area, exists on a cover window of a display such as a smartphone or a tablet PC, and a pattern layer of various colors such as black and white is formed on the bezel to impart aesthetics.

The bezel pattern of the display can be formed in various ways such as photolithography, screen printing, iInkjet printing, gravure coating, and reverse offset coating, among which In the inkjet printing process, it is possible to form a desired pattern in a short time in a non-contact method by UV curing or thermal curing, and it is possible to achieve the optical density of the product by adjusting the dot spacing of the inkjet drop. There is an advantage.

Most of the bezel patterns are printed on the tempered glass, but in order to print the bezel pattern on a substrate such as a film to replace tempered glass, it is difficult to apply the high-temperature thermal curing method used in the existing tempered glass. Therefore, recently, a method of forming a bezel pattern by an inkjet printing process using an ultraviolet curing method has been used.

Meanwhile, in the inkjet printing process, there have been attempts to apply a roll-to-roll (R2R) method to the inkjet printing process to enable continuous printing for mass production. The roll-to-roll method can improve productivity by unwinding the substrate on one side and rewinding the substrate on the other, while continuously performing a printing operation while the substrate is transported in between.

FIG. 1 schematically shows a method of forming a pattern by inkjet printing using a roll-to-roll process, and UV curing is performed after printing a pattern through an inkjet head on a base film moving between rolls and rolls. In this case, in order to perform pattern printing on the moving base film, the tension roll, that is, the tension force must be maintained with a tension roll, and the film may expand due to the force applied by the tension roll. It is not easy to control the vibration of the film only by adjustment, so precise printing is practically difficult. In particular, when the film has a large area and is thick, it is not easy to perform the roll-to-roll process due to the weight of the film itself.

In addition, in the existing roll-to-roll/inkjet process, if repetitive printing is required, the roll is unrolled and reprinted after 1 degree printing. As printing is performed on the substrate driven by the roll, the substrate moves finely and the inkjet head It is almost impossible to precisely perform the second degree printing at the same position due to vibration or the like.

Therefore, in the display industry that requires precise printing (resolution less than 100 μm), there is a need to develop a technology capable of performing continuous multilayer printing more precisely.

The present invention is to solve the above problems, and one object of the present invention is to improve the existing inkjet printing method using a roll-to-roll process, and continuously multi-layer on a large area base film. It is to provide a method of forming a bezel pattern through precision printing capable of printing and realizing high resolution.

Another object of the present invention is to provide a bezel pattern formed from the above method.

Another object of the present invention is to provide a display including the bezel pattern.

According to an aspect of the present invention, as a method of forming a bezel pattern by inkjet printing using a roll-to-roll process,

(S1) unwinding the base film on one side and rewinding on the other side while transferring the base film in roll-to-roll;

(S2) stopping the transferred base film on a work table disposed between a guide roll for driving the base film and a tension roll providing tension to the base film;

(S3) When the base film is in a stationary state, surface treatment, pattern printing, and printing are performed on the stationary base film through the vertical movement of a printing module installed on the work table and including a surface treatment device, an inkjet head, and a curing device. Performing ultraviolet curing of the pattern;

(S4) repeating the (S3) step to form a multilayer printed pattern; And

(S5) There is provided a method comprising the step of retransferring the patterned base film.

The width of the base film may be 750 to 1250 mm.

The stationary state of the base film may be achieved by vacuum adsorption through a plurality of vacuum holes provided in the work table, and the stationary state of the base film may be maintained for 5 to 10 seconds, such as 6 to 8 seconds. .

Left/right displacement of the stationary base film may be controlled by an edge position control device disposed on one side of the tension roll.

In addition, the method of forming the bezel pattern may further include controlling the upper/lower displacement of the film by supplying air to the stationary base film.

Air for controlling the upper/lower displacement of the stationary base film may be supplied through an air floating kit that can be installed on both sides of the work table, and the intensity of the supplied air is 1.0 to 5.0 kPa It can be in the range of.

After the step (S4), the step of inspecting the resolution and error of the multilayer printed pattern formed on the base film may be further included.

In addition, after the step (S4), it may further include a step of coating the surface of the base film on which the multilayer printing pattern is formed with a protective film.

According to another aspect of the present invention, as a bezel pattern formed by the above method, a bezel pattern having a line width of 10 to 90 μm is provided.

The line width of the bezel pattern may range from 10 to 50 μm.

According to another aspect of the present invention, a display including the bezel pattern is provided.

According to the present invention, multilayer printing of 2 degrees or more is continuously performed by repeatedly performing surface treatment of the base film, pattern printing, and ultraviolet curing of the printed pattern several times while the base film transferred in roll-to-roll is temporarily stopped on the work table. This can be done precisely, from which it is possible to form a bezel pattern with high resolution.

The following drawings attached to this specification are intended to illustrate preferred embodiments of the present invention, and serve to further understand the technical idea of the present invention together with the contents of the above-described invention, so the present invention is limited to those described in those drawings. It should not be construed as limited.
1 schematically shows a method of forming a bezel pattern by inkjet printing using a conventional roll-to-roll process.
2 is a flowchart illustrating a process of forming a bezel pattern by inkjet printing using a roll-to-roll process according to an embodiment of the present invention.
3 and 4 schematically illustrate a roll-to-roll/inkjet printing system used in a method for forming a bezel pattern according to an embodiment of the present invention.
FIG. 5 is a diagram illustrating forming a bezel pattern through vertical movement of a printing module while a base film is stopped according to an embodiment of the present invention.
6 is a photograph showing a bezel pattern formed according to Example 1 of the present invention.
7 is a graph showing the degree of vibration control of a base film when an air floating kit is operated when forming a bezel pattern according to Example 2 of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The terms or words used in the specification and claims should not be interpreted as being limited to ordinary or dictionary meanings, and the inventor can appropriately define the concept of terms in order to best describe his or her invention. Based on the principle of being present, it should be interpreted as meanings and concepts consistent with the technical spirit of the present invention.

One embodiment of the present invention relates to a method of forming a bezel pattern by inkjet printing using a roll-to-roll (R2R) process.

2 is a flow chart showing a process of forming a bezel pattern by inkjet printing using a roll-to-roll process according to an embodiment of the present invention, and specifically, a step of transferring a base film in a roll-to-roll (S1); Temporarily stopping the substrate film being transferred (S2); Performing inkjet printing (1 degree printing) while the base film is stationary (S3); Repeating the inkjet printing several times to perform multilayer printing of 2 degrees or more on the stationary base film (S4); And retransferring the stationary base film to a roll-to-roll (S5).

3 and 4 schematically illustrate a roll-to-roll/inkjet printing system used in a method for forming a bezel pattern according to an embodiment of the present invention. By including a work table in a roll-to-roll, R2R is R2SR (roll-to-sheet-roll) can be converted to a sheet type for inkjet printing.

That is, the method of forming a bezel pattern of the present invention is, at the moment when inkjet printing is performed in the process of transferring a base film in a roll-to-roll process, a still image is applied to the base film to repeat pattern printing, and then the pattern printed base film It is characterized in that the multi-layer printing of 2 degrees or more is continuously performed as a method of retransferring.

Hereinafter, a method of forming a bezel pattern of the present invention will be described step by step.

First, the base film is unwinded on one side and rewinded on the other, and transferred by roll-to-roll (S1).

The base film may be used without limitation as long as it is a material capable of inkjet printing. For example, polyethylene terephthalate (PET), polycarbonate (PC), polymethyl methacrylate (PMMA), polyethylene naphthalate (PEN), polyether sulfone ( PES), cyclic olefin polymer (COC), triacetyl cellulose (TAC), polyvinyl alcohol (PVA), polyimide (PI), polystyrene (PS), biaxially oriented polystyrene (biaxially oriented PS) films can be used. I can. In addition, the size of the base film may vary depending on the size and number of bezel patterns to be printed, and in particular, a base film having a large area of 750 to 1250 mm in width, for example 700 to 900 mm is also suitable in the present invention. Can be used.

Subsequently, in order to perform the inkjet printing process on the base film transferred by roll-to-roll, the base film is stopped on a work table providing a stationary image in the roll-to-roll process (S2).

3, the work table is disposed between a guide roll for driving the base film and a tension roll providing tension to the base film, and a plurality of vacuum holes As provided, the substrate film being transported is temporarily stopped by vacuum adsorption through it to form a sheet. The size of this work table may vary depending on the width of the base film. For example, when the width of the base film is 750 mm, it is advantageous to design the size of the work table to be 750 mm x 750 mm so that the base film can be firmly fixed.

In addition, the base film fixed by the work table in a stationary state may have left/right displacement controlled by an edge position control (EPC) device disposed on one side of the tension roll.

Meanwhile, referring to FIG. 4, inkjet printing may be performed while an air floating kit is operated on both sides of a work table providing a stationary image between the roll and the roll. In this case, the air floating kit By supplying air to the stationary base film through the control of the upper/lower displacement of the film, the precision printing efficiency in the stationary state can be further improved.

The air floating kit may be arranged in a vertical direction with respect to the base film in a roll-to-roll, and is formed of stainless steel, in the shape of an elongated bar, and by discharging dry air from the middle part, the tension of the base film. ) Can be controlled more effectively. Therefore, it is possible to minimize the upper/lower displacement of the film by preventing the vibration phenomenon that may occur when the base film maintains the sheet state.

The size of the air floating kit can be variably adjusted according to the width of the substrate, and may be, for example, about 40 cm (L) x 10 cm (W). Also, depending on the size of the worktable, several air floating kits can be connected and used. For example, when the size of the worktable is 750mm×750mm, two air floating kits may be connected to each other in the vertical direction through a connecting ring provided at one end of each (see FIG. 4). The number of sets of the air floating kit connected as described above may be variably increased according to the distance between the guide roll and the tension roll.

As a result, in the existing roll-to-roll/inkjet process as shown in FIG. 1, it is possible to overcome the difficulty of precise printing during multilayer printing of 2 degrees or more due to insufficient control of the tension of the film with only the tension roll, and thus the bezel of the display requiring high resolution. It enables pattern formation.

The intensity of air supplied through the air floating kit may vary depending on the thickness and type of the base film, but in consideration of the fact that the thickness of an optical film commonly used in the display field is 100 μm or less, 1.0 to 5.0 kPa, such as 2.0 To 5.0 kPa or 3.0 to 5.0 kPa.

In a state in which the substrate film being transferred as described above is stopped, inkjet printing is performed on the substrate film through the vertical movement of the printing module installed on the work table (S3).

FIG. 5 is a diagram illustrating forming a bezel pattern through vertical movement of a printing module while a base film is stopped according to an embodiment of the present invention. Specifically, inkjet printing is performed by moving the printing module in the printing direction toward the base film, which is stopped on the work table to maintain the sheet shape and additionally through an air floating kit to prevent vertical shaking.

At this time, as the printing module is configured to include a surface treatment device, an inkjet head, and a curing device, the bezel pattern is changed through the inkjet head as soon as the surface property of the base film is changed by the surface treatment device while the base film is stopped. Printed and printed patterns can implement a process in which curing can occur immediately through a curing device. When the printing module moves up and down once, 1 degree printing is performed, and when 1 degree printing, the stationary state of the base film may be maintained for 5 to 10 seconds, for example 6 to 8 seconds.

On the other hand, in the existing roll-to-roll/inkjet process as shown in FIG. 1, as printing and curing are performed on a substrate driven by a roll, precise printing may be difficult, such as minute movement of the substrate and vibration of the inkjet head.

In one embodiment of the present invention, the inkjet head provided in the printing module can print several patterns at once by including one or more jet nozzles for jetting ink in the form of droplets.

The ink is a black ink, a color ink, or a white ink commonly used to form a bezel pattern, such as a pigment, a dispersant, an epoxy resin, a vinyl ether compound, an oxetane resin, a photopolymerization initiator, an adhesion promoter, a photosensitizer, and an interface. It may be a cationic polymerization type UV curable ink composition containing an activator, or a radical polymerization type UV curable ink composition containing a pigment, a dispersant, an acrylate oligomer, an acrylate monomer, a photopolymerization initiator, an adhesion promoter, and a surfactant.

In addition, the curing dose of the ink may be 20 to 20,000 mJ/cm ² , preferably 50 to 3000 mJ/cm ^2, and may be cured by absorbing ultraviolet rays in a wavelength range of 250 to 410 nm, and the viscosity is It may be 1 to 50 cp at 25 ℃, but is not limited thereto.

In one embodiment of the present invention, the surface treatment device provided in the printing module may be a surface treatment device using an atmospheric pressure plasma.

In one embodiment of the present invention, the UV curing machine provided in the printing module may be used without particular limitation as long as it emits UV rays having a wavelength of 250 to 410 nm, and UV lamps, mercury vapor arcs, carbon arcs, Xe arcs And an LED curing machine and the like can be used.

After the first-degree printing is performed while the base film is stopped, the process of moving the printing module up and down is repeated immediately to perform multilayer printing of 2 or more degrees (S4).

At this time, when multilayer printing of 2 degrees or more, the stopping time of the base film becomes longer. For example, in the case of first-degree printing, if the base film is maintained for 8 seconds, in the case of second-degree printing, the stopped state may be maintained for 16 seconds.

Meanwhile, in order to increase the resolution of the bezel pattern to be formed during multilayer printing of 2 degrees or more, the printing position on the base film can be checked using an alignment camera.

If necessary, after forming a multilayer printed pattern on the stationary base film through repetitive inkjet printing, a step of checking the resolution and error of the pattern may be additionally performed. In addition, in order to protect the pattern formed on the base film, a step of coating a protective film on the surface of the base film may be additionally performed.

After that, the patterned base film is retransferred from a sheet form to a roll form (S5).

According to the method of forming the bezel pattern of the present invention as described above, the base film running in roll-to-roll is firmly held on the work table to maintain a stationary image in the form of a sheet, and the vibration of the film is additionally controlled through an air floating kit. By repeatedly operating the printing module at 2°C and performing multilayer printing of 2° or more, it is possible to improve the existing process, which was difficult to perform 2° printing at the same location due to the minute movement of the base film and vibration of the inkjet head in the roll-to-roll process. , It can meet the demand of the display industry that requires precision printing (resolution less than 100㎛).

Accordingly, another embodiment of the present invention provides a bezel pattern formed by the above method, and the bezel pattern exhibits a line width of less than 100 μm, for example, 10 to 90 μm, or 10 to 50 μm, thereby realizing high resolution.

Additionally, the present invention provides a display including the bezel pattern.

In one embodiment of the present invention, the display is a plasma display panel (PDP), a light emitting diode (LED), an organic light emitting diode (OLED), a liquid crystal display device (Liquid Crystal). Display, LCD), a thin film transistor liquid crystal display (LCD-TFT), and a cathode ray tube (CRT) may be used in any one.

Hereinafter, examples will be described in detail to help understanding of the present invention. However, the embodiments according to the present invention can be modified in many different forms, and the scope of the present invention should not be construed as being limited to the following examples. The embodiments of the present invention are provided to more completely describe the present invention to those of ordinary skill in the art.

Example 1: Formation of a bezel pattern through 2-degree multilayer printing

As shown in Fig. 3, a work table (750 mm x 750 mm) having a plurality of vacuum holes between the guide roll and the tension roll, a printing module on the top of the work table, and a roll equipped with an EPC device on one side of the tension roll A bezel pattern was formed using a two-roll/inkjet printing system. The printing module was configured to include an AP plasma, an inkjet head including four jet nozzles, and a UV LED (365/395 nm). At this time, the spray nozzle has 42 parts by weight of oxetane as an evaluation ink, 15 parts by weight of alicyclic epoxy, 20 parts by weight of carbon black, 5 parts by weight of an acrylic dispersant, 10 parts by weight of diethyl succinate as a solvent, 5 parts by weight of a photopolymerization initiator, A black ink composition containing 3 parts by weight of a surfactant was used.

First, as a base film, a polyethylene terephthalate (PET) film (width: 750 mm) was prepared and transferred while unwinding in one side of the system and rewinding in the other side.

While the transferred base film is stopped on a work table between a guide roll and a tension roll and held in a sheet form, the printing module is operated up and down with respect to the base film, so that surface treatment of the area to be printed, pattern printing, and ultraviolet rays Curing was performed (1 degree printing). At this time, the stationary state of the base film was maintained for 8 seconds.

After performing the first degree printing, the second degree printing was performed by immediately operating the printing module up and down again. During the 2nd degree printing, the base film was kept stationary for a total of 16 seconds. After finishing the 2nd degree printing, the stationary base film was retransferred in the form of a roll.

Example 2: Formation of bezel pattern through 2-degree multilayer printing

As shown in Fig. 4, in the roll-to-roll/inkjet printing system, a set of two air floating kits (stainless steel, 40cm(L)×10cm(W)) connected in a vertical direction on both sides of the worktable is additionally arranged and described. A bezel pattern was formed in the same process as in Example 1, except that air was supplied to the opposite side to the printing surface of the film. At this time, while changing the intensity of air supplied from the air floating kit from 1.0 kPa to 5.0 kPa, the degree of control of the film shaking was confirmed.

The results of the bezel pattern formed from the above are shown in FIGS. 6 to 7.

6 is a shape of the bezel pattern formed from Example 1, it was confirmed that in the shape of the bezel pattern printed in 2 degrees, a line width of 90 µm at the position ① and a line width of 50 µm at the position ②. It satisfies the demands of the display industry requiring (resolution less than 100㎛).

7 is a graph showing the degree of vibration control of a base film when an air floating kit is operated when forming a bezel pattern according to Example 2. As can be seen from the graph values of Fig. 7, when the air floating kit is operated, the displacement due to the shaking of the film is very small, and the difference between the displacement value during operation and non-operation is 100㎛ or more. I can.

From this, when air is supplied to the stationary base film when inkjet printing is performed while the base film is stationary, the tension of the film is more effectively controlled to minimize the up/down displacement, It can further improve the precision printing efficiency.

Claims (14)

As a method of forming a bezel pattern by inkjet printing using a roll-to-roll process,
(S1) unwinding the base film on one side and rewinding on the other side while transferring the base film in roll-to-roll;
(S2) stopping the transferred base film on a work table disposed between a guide roll for driving the base film and a tension roll providing tension to the base film;
(S3) When the base film is in a stationary state, surface treatment, pattern printing, and printing are performed on the stationary base film through the vertical movement of a printing module installed on the work table and including a surface treatment device, an inkjet head, and a curing device. Performing ultraviolet curing of the pattern;
(S4) repeating the (S3) step to form a multilayer printed pattern; And
(S5) A method comprising the step of retransferring the patterned base film. The method of claim 1,
The width of the base film is 750 to 1250 mm. The method of claim 1,
The method in which the base film is stopped by vacuum adsorption through a plurality of vacuum holes provided in the work table. The method of claim 1,
In the step (S3), the stationary state of the base film is maintained for 5 to 10 seconds. The method of claim 4,
In the step (S3), the stationary state of the base film is maintained for 6 to 8 seconds. The method of claim 1,
The stationary base film is a method in which left/right displacement is controlled by an edge position control device disposed on one side of the tension roll. The method of claim 1,
The method further comprising controlling the upper/lower displacement of the film by supplying air to the stationary base film. The method of claim 7,
Air for controlling the upper/lower displacement of the stationary base film is supplied through an air floating kit that can be installed on both sides of the work table. The method of claim 7,
The air is supplied at an intensity of 1.0 to 5.0 kPa. The method of claim 1,
After the step (S4), the method further comprising the step of inspecting the resolution and error of the multilayer printed pattern formed on the base film. The method of claim 1,
After the step (S4), the method further comprising the step of coating the surface of the base film on which the multilayer printing pattern is formed with a protective film. A bezel pattern formed by the method according to any one of claims 1 to 11, wherein the bezel pattern has a line width of 10 to 90 µm. The method of claim 12,
A bezel pattern having the line width of 10 to 50 μm. A display including the bezel pattern of claim 12.

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