KR101039297B1 - Roll-to-Roll Printing method Using The Characteristic Of Cavity Material For Printed Electronics - Google Patents

Abstract

The present invention relates to a continuous process roll-to-roll printing apparatus and method of an electronic device using the characteristics of the cavity material, by experiments to determine the role of the hydrophobicity of the cavity in the ink delivery process by experiment, the ink that can exhibit hydrophilicity and hydrophobicity As the ink transfer amount of the maximum effect on the contact angle between the cavity and the cavity is derived, when the cavity material of the gravure roll is made hydrophobic, the ink of the maximum effect can be delivered.

Cavity, Cavity, Hydrophobic, Hydrophilic

Description

Roll-to-Roll Printing Method Using The Characteristic Of Cavity Material For Printed Electronics

 The present invention relates to a continuous process roll-to-roll printing apparatus for electronic devices, and a method thereof. An ink which can show hydrophilicity and hydrophobicity by identifying the effect of hydrophobicity of a material of a cavity on an ink delivery mechanism in an electronic device printing roll-to-roll process; It can be used to obtain an ink transfer amount of maximum effect on the contact angle between the cavities.

The printed RFID market is not yet large in size, but the market is expected to reach around 30 trillion won by 2015. It is expected to replace the barcode and become a new blue ocean if the technical support is made and the ultra low price is realized. This is why RFID technology, which is not spreading in earnest due to high production costs, is drawing attention.

In order to develop a low-cost chip, it is necessary to change the process and material for manufacturing the chip. Attention has been paid to a method of printing a tag using a conductive polymer or an electronic ink. The use of conductive polymers in terms of materials has the advantage that flexible and robust bonding can be achieved by replacing silicon chips, and the cost of materials can be reduced, thereby significantly reducing production costs. In addition, in terms of the process, using the printing method it is possible to increase the production speed and output, and to use the low-cost printing equipment rather than the expensive semiconductor processing equipment has a significant impact on the price of the RFID tag. .

In order to commercialize RFID tag production using a printing method, various technologies must be successfully performed, and ink delivery process plays a particularly important role. The importance can be divided into two main categories. The first is about the performance of printed electronics, which is important because it ensures the performance of products that require ink delivery to be successful. If the width or thickness of the printed line does not have the desired value, the required current may not flow properly, or there may be a problem of not having a proper resistance, and thus the use of the product may be determined. Secondly, it is about the life of the printing equipment. If the ink is not delivered properly, the ink remains in the engraved shape of the gravure cylinder, and if the printing is repeated in this state, it is economical to clean or replace the gravure cylinder. Loss occurs. For this reason, the ink delivery process plays a very important role.

In particular, as the web and roller proceed, the process of ink delivery is described in detail, and the viscoelastic effect of the electronic ink is effectively considered to realize a more realistic ink delivery process and to understand the print properties. This is because it is expected to be a great help in the application to the industry.

The study of ink delivery process can be largely divided into experimental approach and numerical approach. The experimental approach has a limitation that it is difficult to examine each parameter independently because the engraved microscale engraved on the gravure cylinder and various influences such as the rotational influence of printing, the pressure roller and the influence of the material work together. For this reason, many experimental studies remain in grasping the status quo, and even relatively detailed studies can be said to have a significant leap in assuming the effects of roller rotation. On the other hand, the numerical approach has the advantage of being able to examine various parameters independently, but it has a limitation that it is difficult to verify through experiments.

Numerical analysis on printing can be divided mainly into a similar approach to coating or filament stretching. The former has the advantage that it can be easily applied because it can take a lot of benefits from the existing coating method, but it is difficult to derive deeper results due to the fundamental difference between the presence or absence of the intaglio shape. Have. The latter is a more realistic approach than the former, and has the advantage of being able to quantitatively simulate ink delivery in that it represents the interface between ink and air. However, it is difficult to set an appropriate boundary condition and has the disadvantage of excluding the influence of rotation and the influence of the pressure roll.

Therefore, it is necessary to understand the ink delivery process by understanding the effect of the hydrophobicity of the cavity material on the ink delivery using the improved filament stretching method. That is, the influence on the ink delivery process is thought to be mainly the physical properties of the ink, and although many studies have been conducted, there is no study on the properties of the cavity material. Therefore, the study of the ink properties has reached its limit, and it is necessary to grasp the ink delivery process by grasping the effect of other influences, that is, the influence of the hydrophobicity of the cavity material on the ink delivery.

In order to solve this problem, the present invention identifies how strongly the hydrophobicity of the cavity material affects the ink delivery process through computer calculation, and when the influence is large, the ink transfer amount which can be improved through the hydrophobic coating of metal is identified. To provide a continuous process roll-to-roll printing apparatus for electronic devices using the characteristics of the cavity material that can supply the maximum amount of ink delivery to minimize the trial and error or damage to the cost and time in advance.

Another object of the present invention is to provide an apparatus and method for continuously processing roll-to-roll printing of an electronic device using the characteristics of the cavity material to enable mass production at the maximum ink delivery amount.

Continuous process roll-to-roll printing apparatus of an electronic device using the characteristics of the cavity material according to the present invention for achieving this object is a web, gravure printing conveyed in one direction by gravure roll, gravure roll and Nip Roll acting as an imprinting roller It comprises a doctor blade for scraping the ink on the surface of the roll uniformly and the feed bath containing the conductive ink, characterized in that the Cavity material of the gravure roll is hydrophobic.

And Cavity is preferably immersed in a metal salt solution and coated with a metal layer.

Continuous process roll-to-roll printing method of the electronic device using the characteristics of the cavity material according to the present invention for achieving this object, the step of transporting the web in one direction, the step of rotating the feed bath containing the conductive ink on one side of the gravure roll, Changing the hydrophobicity of the cavity of the gravure roll and measuring the ink delivery amount according to the hydrophobicity of the cavity so as to make the ink delivery amount maximum hydrophobic.

And Cavity is more preferably soaked in a metal salt solution to be coated with a metal layer.

Therefore, according to the continuous process roll-to-roll printing apparatus and method of the electronic device using the cavity material of the present invention, the importance of the ink delivery process in the roll-to-roll printing method used for the production of electronic devices In addition, the flow analysis of ink transfer characteristics is performed to establish the foundation of flow analysis in the gravure printing field, thereby overcoming the limitations of R2R printing and laying the foundation for mass production.

In addition, since mass production is possible with the maximum ink delivery amount, it is possible to economically and efficiently print in time.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

The terms or words used in this specification and claims are not to be construed as limiting in their usual or dictionary meanings, and the inventors may properly define the concept of terms in order to best explain their invention in the best way possible. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention.

Therefore, in the following description, the flow analysis on ink transfer characteristics is performed to overcome the limitations of roll-to-roll (R2R) printing by establishing the basis of flow analysis in the gravure printing field, and the basis of mass production. Since it is important to prepare the ink, it is necessary to select representative physical properties related to the flow and to derive independent research results, so that the ink can be identified to provide the standard for optimized ink by identifying the physical properties that play an important role in ink delivery. I will explain it in a way that actually depicts the process being conveyed.

1 is a view showing a continuous process roll-to-roll printing apparatus for an electronic device using a cavity material according to an embodiment of the present invention, the apparatus is an ink filling method, nip roll (110), web (Web) (120), Gravure Roll (130) acting as an imprinting roller, Doctor Blade (140), ink filling tank (150) and ink filling to scrape the ink on the roll surface evenly during gravure printing It is configured to include a conductive ink (Conductive Ink, 160) contained in the water tank (150).

In this embodiment, in order to check the hydrophobicity of the cavity (cavity) material, it was found that the calculation using the STAR-CCM + v2.10 released by the general-purpose commercial tool CD-adapco to look at the more realistic shape.

On the other hand, the present invention is to determine how much the hydrophobicity of the cavity material affects the ink delivery process, and when the influence is large, it is to measure the effect on the amount of ink delivery that can be enhanced through the hydrophobic coating of metal, The operation of the phosphor constituent devices will be omitted, and for convenience of description, the gravure roll 130 has a plurality of cavities (typically cells) that contain ink from the ink filling tank 150, but for convenience, The process of gravure printing will be described considering only one cavity that is simplified in two dimensions including the shape of the cavity and the curvature of the roller.

See the following table for specific values of shapes and processes.

geometry variable value roll radius 25 mm cavity width 1mm (1000m) cavity depth 0.5mm (500m) distance between web and roller 0.05mm (50m) angle of cavity 10 °

The hydrophobicity and hydrophilicity of the cavity material is used to express the degree of wettability of a solid surface when the liquid is thermodynamically balanced on a solid surface. Hydrophobicity also means low contact angle, and hydrophilicity means high contact angle.

For reference, referring to FIG. 5, an angle θ formed between the cavity material and the ink is called a contact angle of the cavity.

The nip roll 110 acts as a pressure roller and consists of a backing roll and a nip and is configured to transfer the ink remaining in the gravure cavity to the printed matter.

The web 120 refers to a printed matter on which ink is printed, and the gravure roll 130 is a type of plate printing, in which a recessed line portion (cell) is formed of a cavity, and nip rolls of ink from the ink filling tank 150. 110 is configured to be transferred.

The doctor blade 140 performs a function of scraping off the excess ink remaining on the surface of the gravure roll 130 discharged from the ink filling tank 150.

Therefore, in order to secure the tolerance from the doctor blade 140, it is preferable to perform hard Cr plating on the surface of about 10 micrometers.

The conductive ink 160 uses a pigment or a dye as a colorant and is dispersed or solvent in an organic solvent together with a resin (binder) having good adhesion to the plastic film surface. Binders include cellulose-based, rubber-based, natural resins, synthetic resins, etc., which are selected by reviewing adhesiveness to a film, solvent stripping properties, and usability with other resins, and a plasticizer or printing for improving the softness and adhesiveness thereon. Active agents which raise the pulling strength and blocking strength of the film are added. The solvent is an organic solvent is used, the evaporation is suitable, the point is less adverse effect on the human body is a requirement. As the kind, aliphatic hydrocarbons, aromatic hydrocarbons, alcohols, ketones, esters and the like are used in combination. Films printed on plastic films are particularly needed to be flexible and stretchable.

Therefore, there is an advantage that it is easy to print on materials other than paper, such as cellophane, vinyl, polyethylene, metal, wood, etc., because the range of ink selection is wide.

Gravure printing of the above-described configuration is a convex portion on the surface of the gravure roll 130, which is a kind of plate printing, using a gravure roll 130 having a recessed line part (cell) as a plate and scooped out from the ink filling tank 150. Ink is scraped off with the doctor blade 140 to transfer the ink remaining in the cavity to the printed matter by the force of the nip roll 110.

Referring to FIG. 1, the reference speed between the web 120 and the gravure roll 130 is 6 m / mim.

In gravure printing, although low-viscosity ink can be uniformly and stably applied even at a high speed of 10mpm or more, the above-described printing speed is relatively very low, but this is considered in consideration of drying time by a drying system manufactured by Konkuk University. Determined speed. The rotational speed of the roller is 4 rad / s, the feed rate of the gravure roll 130 and the web 120 is preferably set so that the relative speed does not occur in the contact portion between the gravure roll 130.

Looking at the operation, while the web 120 is transported in one direction by the gravure roll 130 and the nip roll 110 acting as an imprinting roller, the ink filling tank containing the conductive ink 160 in the gravure roll 130 ( It is to investigate the effect of the hydrophobicity of the cavity on ink delivery while rotating at a constant speed.

In addition, it is analyzed as a two-dimensional flow, assuming no change in the direction of travel, and assuming that the tension of the web is very strong, flow-structure ductility is not considered.

▶ The printing process basically needs to analyze the change of time between the two phases of ink and air, so it is necessary not only to know the flow characteristics based on the properties of the conductive ink, but also to change the free surface. It should also be calculated. As a boundary boundary tracking method, a typical volume of fluid (VOF) model was used. The VOF model can represent the instantaneous motion of two different phases, as well as the topological changes between the two phases. This model is limited to calculating the exact curvature due to the rapid change in the free surface area, but seems to be the right choice because it has the advantage of good mass conservation while maintaining the upper boundary.

2 to 4 illustrate the effect of the material of the cavity on the ink delivery amount using this configuration.

That is, in order to check how much the degree of hydrophilicity between the cavity wall surface 132 of the gravure roll 130 and the conductive ink 160 affects the ink transfer amount, the effect is changed while changing the contact angle between the cavity wall surface and the ink. I looked at it. 2 and 3 show that when the cavity wall 132 material of the Gravure Roll 130 is hydrophobic, the amount of ink delivered to the Web 120 increases. That is, referring to FIG. 2, the ink transfer amount is displayed when the printing speed is 0.02 seconds. The left view of FIG. 2 shows the contact angle between the Web 120 and the Gravure Roll 130 when the material of the cavity wall 132 is hydrophobic. and the ink transfer amount when θ = 45 °, and the middle view of FIG. 2 also shows the ink transfer amount when θ = 90 ° when the material of the cavity wall surface 132 is hydrophobic, and the right side. The figure also shows the ink transfer amount when θ = 135 ° when the material of the cavity wall surface 132 is hydrophobic. Referring to the drawings, it can be seen that the ink transfer amount increases as the contact angle increases while the hydrophobicity of the cavity wall surface 132 of the Gravure Roll 130 is increased.

3 is a diagram showing the effect on the ink delivery amount when the printing speed is 0.04 seconds. This is to investigate the amount of ink delivered with the printing speed doubled to investigate the effect of relative speed even when the material of the cavity wall surface 132 is hydrophobic. FIG. 3 shows the ink transfer amount when the cavity wall surface 132 is hydrophobic, that is, the contact angle, that is, when θ = 45 °, and the middle view of FIG. 3 shows the ink transfer amount when θ = 90 °. The figure shown in the figure and the right figure show the ink delivery amount when (theta) = 135 degrees.

As shown, the ink delivery amount is determined by the contact angle (θ) between the web 120 and the ink when the cavity wall 132 of the Gravure Roll 130 is hydrophobic rather than the relative speed of the Web 120 and the Gravure Roll 130. It can be seen that the ink delivery amount varies greatly.

That is, when the cavity wall surface 132 of the Gravure Roll 130 is hydrophobic, it can be seen that ink transfer is more effectively performed as the contact angle θ between the Web 120 and the ink is larger. Therefore, it can be seen that the hydrophobicity of the cavity wall surface 132 reduces the amount of ink remaining in the cavity by pushing the ink.

4 is a diagram illustrating a change in pressure when the contact angle of the web is changed when t = 0.04, and the pressure is lower when the contact angle θ becomes smaller or larger based on when the contact angle θ is 90 °. In addition, it can be seen that, when the contact angle θ is smaller than 90 °, it is relatively lower than the large band.

This change in pressure is shown in Table 2. Referring to Table 2, the pressure difference Δp at θ = 45 ° is 251.276 Pa, and the pressure difference Δp at θ = 90 ° is 362.027Pa, and the pressure difference at θ = 135 ° ( It is understood that Δp) is 302.077 Pa.

θ = 45 ° θ = 90 ° θ = 135 ° Pressure difference △ p (Pa) 251.276 362.027 302.077

Therefore, it is important to come up with ways to increase the hydrophobicity of the metals that make up the cavity. Scientists at Queen's University Belfast, UK, have published research on "superhydrophobic" materials that can be used in many applications. It was. Department of Chemistry and Chemical Engineering Dr. Graham Saunders and Steven Bell and Ph.D. students Iain Larmour have developed a very simple method of treating metals to be superhydrophobic. Metals with OH can be used in standard laboratory equipment in readily available initial materials and in processes that only take 2 to 3 minutes.

The ease and flexibility of the manufacturing method is an important aspect of this technology. It is not suitable for practical use because it is difficult, expensive or only limited to materials, but this method can produce a strong surface with hydrophobicity that surpasses the superhydrophobicity of the lotus leaf. Moreover, because this method is economical and fast, it can be extended to various metals.

The lotus leaf is super hydrophobic because it has a nano-cilia structure on a microprojection covered with wax material. Belfast researchers at Queen's University have succeeded in mimicking the surface structure. The process is simple. Submerging the material to be made hydrophobic in a metal salt solution coats the material with a layer of metal that is thinner than a human hair resembling a lotus leaf. Dipping this material into the chemical surface control solution causes the textile coating to be covered with an additional very thin layer of hydrophobic molecules. The resulting surface has very good hydrophobicity, so the water droplets on the surface become completely spherical and the coated object is completely dried by soaking in water for several days, then removing and wiping.

This method of making superhydrophobic metals is so flexible and simple that it can be applied to many other metal materials or materials of various sizes and shapes.

By using this technique to make the metal hydrophobic, the hydrophobicity of the cavity material can be increased, along with other factors that have had a favorable effect on the existing ink delivery, thereby enabling more favorable ink delivery.

Although the present invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made within the technical scope of the present invention, and such modifications and modifications belong to the appended claims.

The present invention relates to a roll-to-roll printing apparatus and a method thereof. In particular, the hydrophobicity of the cavity is considered to play an important role in the ink delivery process, and the study of the contact angle between the ink and the cavity, which can exhibit hydrophilicity and hydrophobicity, is conducted. By doing so, it can be said that the study has a significant meaning that can grasp the influence and present a standard for the optimized ink. In particular, as the web and rollers progress, the process of ink delivery is described in detail, and the study of the material properties of the equipment, other than the existing printing properties, is carried out. It is expected to help.

1 is a view showing a continuous process roll-to-roll printing apparatus of an electronic device using a cavity material according to an embodiment of the present invention,

2 is a view showing the effect of the cavity material on the ink delivery amount when the printing speed is 0.02 seconds,

3 is a view showing the effect of the Cavity material on the ink delivery amount when the printing speed is 0.04 seconds,

And,

4 is a view showing a change in pressure when the cavity material is changed when t = 0.04.

Description of the main parts of the drawing

110: Nip Roll 120: Web

130: Gravure Roll 140: Doctor Blade

150: ink filling tank 160: conductive ink

Claims (6)

delete delete delete Transporting the web in one direction; Rotating one side of the gravure roll ink filling bath containing conductive ink and transferring ink to the web; Changing the hydrophobicity of the cavity of the gravure roll; And Measuring an amount of ink delivered to the web according to the hydrophobicity of the cavity; And a hydrophobicity of the cavity to determine the hydrophobicity so that the ink transfer amount is maximized. The roll-to-roll printing method of the electronic device using the characteristics of the cavity material. The method of claim 4, wherein The gravure roll and the web A continuous process roll-to-roll printing method of an electronic device using the characteristics of the cavity material, characterized in that the relative speed does not occur in the contact portion. The method of claim 5, The cavity is A continuous process roll-to-roll printing method of an electronic device using the characteristics of the cavity material characterized in that it is immersed in a metal salt solution to be coated with a metal layer.

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