WO2019209047A1 - Photolithography color ink - Google Patents

Abstract

The present invention relates to a photolithography color ink comprising: 16.0-31.0 wt% of a photobinder; 7.5-15.2 wt% of a photoinitiator; 10.0-19.5 wt% of a monomer and an oligomer in total; 0.9-1.8 wt% of an additive; and 35.0-65.6 wt% of a thermosetting ink, wherein the additive is a saturated or unsaturated fatty acid bearing a carboxyl group and having an even number of 12-24 carbon atoms. In the present invention, a thermosetting ink and a photosensitive portion are contained together, which leads to the effect of simultaneously achieving pattern formation by an exposure-development process and the reliability and color visualization of the thermosetting ink. In addition, since the pattern formation by photolithography according to the present invention allows very minute errors for alignments of fine holes, multiple sheets can be printed in one round of printing processes, resulting in an increase in process efficiency and a decrease in process cost. Particularly, the photolithography color ink of the present invention can impart a photosensitive property allowing for photolithography without a large modification to configurations of conventional ink compositions, thereby providing a novel ink composition with which precise printing can be accomplished.

Description

Photolithography color ink

The present invention relates to color inks, and more particularly, to color inks that can be printed in an accurate position and shape.

Recently, various kinds of mobile and IT devices (cellular phones, PDAs, PMPs, notebooks, touch screens, etc.) are used a lot.

Such mobile and IT devices are provided with a display window, and a window made of high strength glass or transparent resin is positioned outside the display window to protect the display window. Such a window is generally made larger than the display window, and is printed outside of the space where the display window is located, thereby decorating the appearance in various colors or displaying a trademark or a logo.

Since the printing on the inner surface of the window is performed in a form except for the inside of the display window portion, a method of hardening by heating after performing screen printing using a thermosetting ink has been mainly used. However, recent mobile and IT devices need to be opened for camera lenses, sensors, and speakers in addition to display windows, and thermosetting inks should not be printed in these open positions. At this time, holes (camera hole, sensor hole, speaker hole, etc.), which are open spaces for camera lenses, sensors, and speakers, should be formed in a relatively small size. Aligning in the right place is not easy. Therefore, the current screen printing process using the thermosetting ink is performed only one print at a time for precise control, which causes a high manufacturing cost. In addition, jig is used to implement several to several tens of prints at a time, and the jig tolerance is added as well as the printing tolerance, making it difficult to proceed with a precise screen printing process.

[Previous Technical Document] Korean Patent Application Publication 10-2016-0124449

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is to provide a new kind of printing ink capable of printing a plurality of windows at a time.

Photolithography color ink according to the present invention for achieving the above object is a color ink for performing color printing on the back of the window of the display window, an optical binder in the range of 16.0 ~ 31.0 wt%; Photoinitiators in the range of 7.5-15.2 wt%; Combined monomers and oligomers in the range of 10.0 to 19.5 wt%; Additive in the range from 0.9 to 1.8 wt%; And a thermosetting ink in a range of 35.0 to 65.6 wt%, wherein the thermosetting ink is at least one selected from pigments, epoxies, acrylics, and urethanes, thermosetting resins which are block isocyanates or latent curing agents, and DBE (Di Basic Ester) and At least one solvent selected from IPR (Isophorone) and BC (Butyl cabitol), the additive is characterized in that the saturated or unsaturated fatty acid having a carboxyl group and composed of an even number of 12 to 24 carbon atoms.

Conventional photo-curable or UV-curable paints use the property of being cured by light, but are not a technique for selectively printing in a desired form through an exposure process using a mask or the like. On the other hand, the photolithography process using a photoresist is a technique of forming a pattern through an exposure process using a mask, but it cannot be applied as a printing ink capable of incorporating color into itself.

The conventional photoresist can be applied only to pattern printing and not to color printing, but in order to impart color to the photoresist, a material such as a pigment must be added, but materials other than the photoresist material can be added for curing. This is because the exposure and development process cannot be performed in an accurate pattern due to the interference of light absorption.

Therefore, in the past, the present invention was applied to use a photosensitive resin to form a three-dimensional pattern, but was not used for color printing.

The photolithography color ink of the present invention can selectively print only necessary portions by an exposure process using a mask like photolithography, and can also perform color printing that displays colors by itself.

In particular, the photolithography color ink of the present invention has a great feature in providing a new ink composition capable of precise printing by imparting photosensitive characteristics that photolithography can be performed without significantly changing the composition of the conventional thermosetting ink composition. have.

The optical binder is preferably one of an acrylic binder, cellulose and an epoxy acrylate.

It is preferable that a monomer is an acryl-type monomer or a urethane type monomer of 3-6 functional group range.

It is preferable that an oligomer is a urethane type oligomer or an epoxy type oligomer of 4-6 functional group range.

Photoinitiator is preferably at least one selected from α-Hydroxyketone, Phenylglyoxylate, α-Aminoketone, Mono Acyl Phosphine (MAPO) and oxime system.

It may further include a wax or a surface tension increasing agent, further comprising a dispersant having an amine and an acid group.

It may further include an antifoaming agent, or may further include SiO ₂ or TiO ₂ .

According to another aspect of the present invention, a method for printing a back surface of a window is performed by using the photolithography color ink described above and performing a process of forming a pattern by performing an exposure process and a developing process to form holes formed in a window. It is characterized by.

The present invention configured as described above includes the thermosetting ink and the photosensitive portion together, whereby the pattern formation by the exposure-development process and the reliability and color implementability of the thermosetting ink can be simultaneously obtained.

In addition, in the present invention, due to the pattern formation by photolithography, since there is very little error in the alignment of fine holes, it is possible to perform printing on several sheets in one printing process, resulting in higher process efficiency and reduced process cost. It is effective.

1 is a flowchart illustrating a printing process using a photoresist color ink according to an embodiment of the present invention.

2 is a flowchart showing a printing process using a conventional thermosetting ink.

With reference to the accompanying drawings will be described embodiments of the present invention;

The photolithographic color inks according to the invention are optical binders in the range of 16 to 31 wt%, photoinitiators in the range of 7.5 to 15.2 wt%, monomers and oligomers in the range of 10 to 19.5 wt%, additives in the range of 0.9 to 1.75 wt% and And thermosetting inks in the range of 35 to 65.6 wt%.

In this case, as the additive, a saturated or unsaturated fatty acid having a carboxyl group and having an even number of 12 to 24 carbon atoms is used.

Photolithography of the present invention can be largely divided into a photosensitive portion for imparting photosensitivity and a thermosetting ink for imparting color, and the photosensitive part includes an optical binder, a photoinitiator, a monomer and an oligomer, and an additive.

The optical binder is made of acryl binder, cellulose and epoxy acrylate, and has an acid group at its end. If there is a double bond, the binder may also participate in crosslinking between the photoinitiator and the monomer to increase the degree of photocuring. The molecular weight is applied at the level of 2000 ~ 200,000mw, and it affects the sensitivity of photoresist (PR) depending on the molecular weight. In detail, when using less than 2000mw at 5000 ~ 600,000mw, the molecular weight is low, so the photocurability is low and the pattern formation is disadvantageous or color dispersion is not good. If it is 200,000mw or more, the viscosity becomes high, and ink manufacture and printability are bad, and when it develops, it falls in the form of a film (lump) and does not obtain a good pattern. Viscosity requires a viscosity of 2000 ~ 10000cp in order to apply to screen printing, which may vary depending on the solid content or molecular weight in the binder synthesis, 5000-8000cp is suitable. The T _g of the resin is changed according to the drying temperature. The higher the T _g , the better the drying characteristics (solvent volatility).

T _g is preferably 30 to 130 ° C, and specifically 80 to 110 ° C. If the T _g is low, it is difficult to repeat printing due to the tack property, trapped during drying, solvent remains, so proper exposure is difficult due to the refractive index change of the remaining solvent during post-processing, exposure, and development speed is increased during development, and pattern dropout may occur. And pattern sharpness is poor.

When perl is applied in the composition of the photoresist color ink, acrylic or cellulose-based resins are suitable for expressing the particle feeling or the mirror feeling (metal pearl_ex: Al). The above series influences the arrangement of pearls by the structure or printability of the polymer.

The monomer is preferably an acryl-based monomer or a urethane-based monomer having a level of 3 to 6 functional groups. When using less than 2 functional groups, the reactivity is slow, and when more than 7 functional groups are used, it may affect residue after developing process. The selection of monomers varies according to the type of optical binder. For example, acrylic polymers have excellent matching properties with acryl and urethane, but cellulose polymers have good matching with urethane monomers. When the cellulose polymer and the acrylic monomer are combined, the hydrogen bond affects the stability.

The oligomer is urethane-based, epoxy-based, etc., 4 to 6 functional group level is suitable. At six or more functional groups, developing residues occur and the developing speed is slowed, and at four or less functional groups, the sensitivity is lowered to increase the exposure amount. The reaction rate is slower than that of monomers, but it participates in crosslinking in a wider form, affecting the strength of the material and the shape of the pattern. In addition, by increasing the process margin in the development process to suppress the occurrence of surface damage during alkali etching. In particular, when the thermosetting ink is used in the composition to which the thermosetting ink is applied, wrinkles are generated because the monomer cannot stand the shrinkage phenomenon occurring in the photocuring process, but the oligomer can be used together to solve this problem.

The photoresist color ink of the present invention has excellent efficiency of suppressing the occurrence of surface wrinkles after the exposure or development process when the ratio of monomers to oligomers is about 1: 1, and the surface wrinkles when the monomer ratio exceeds 60% of the oligomers. This may occur. The input amount of monomer and oligomer can be applied up to 30 ~ 70% compared to the photosensitive binder, and it is easy to develop by controlling the dry state of the coated coating film using the property of not drying and curing at low temperature due to the characteristics of the raw material itself.

Photo-initiator is used α-Hydroxyketone, Phenylglyoxylate, α-Aminoketone, Mono Acyl Phosphine (MAPO), oxime type, etc., and can be changed depending on the color of the ink to be implemented according to the absorption wavelength. For example, when the black ink is produced, since light transmittance is small, short wavelength initiators are mainly used, and a sensitizer is applied at the same time. In the case of white color, short wavelength and long wavelength initiators are used at the same time, but the initiator content can be adjusted to match the sensitivity of the desired material. And when applied to yellowing or color-sensitive inks, the color and content of the initiator should be adjusted.

The additive uses saturated or unsaturated fatty acids having carboxyl groups and consisting of even numbers of 12 to 24 carbon atoms. Preferably, the carbon number is 18 or less and the number of double bonds is less than 3, and it is present between the materials in the mixture state and lowers the bond between materials, resulting in easier alkali etching in the developing process. . Such an additive is a main element that exhibits the effect that the photolithographic color ink of the present invention can be cured except for a camera hole through an exposure process.

In addition, the performance can be improved by further including a dispersant having an amine and an acid group in the photosensitive portion of the photolithographic color ink according to the present invention. Such dispersants have wetting properties due to dispersibility due to electrostatic repulsion by charge and steric hindrance by the adsorption layer, and increase the rate of wetting during mixing or dispersing between the thermosetting ink and the photosensitive portion. In particular, the wettability enables development by adsorbing the photosensitive elements, which are photosensitized or developed in pigments and thermosetting resins, onto the surface, and improves residues (local phenomenon). Acid groups affect developability, and amines participate in the reaction as a curing agent in the present drying (thermosetting). As the amine and the acid value, a raw material containing 10 to 100 mg KOH / g may be applied.

By adding a wax or surface tension increasing agent to the photosensitive portion to impart slip properties, the phenomenon of sticking with the plate during the printing process can be improved.

In addition, an antifoaming agent may be additionally added to remove bubbles generated during the printing process.

Furthermore, by adding SiO ₂ or TiO ₂ additionally, scattering due to the inherent refractive index and particle size helps the light move during exposure, so that the sensitivity of the photosensitive portion when applied to black color with strong absorption of light is increased. Can be improved.

And fumed silica can be used as a thickener and used for the purpose of controlling the gloss of the photoresist color ink surface.

Thermosetting inks can be used without any great limitation to the various thermosetting inks currently used. Like general thermosetting inks, it is composed of a pigment for imparting color, a thermosetting resin, a thermosetting agent and a solvent.

Epoxy, acryl, urethane, etc. are used for thermosetting resin, and resin type can be selected according to the kind of base material or the purpose of an ink. In particular, in the case of reliability items such as heat desorption, epoxy resins having a low thermal shrinkage rate are applied, and thermosetting resins can be selected depending on printability (surface properties).

Thermosetting agents cure thermosetting polymers using block isocyanates or latent curing agents in consideration of the stability and workability of the material. Different types of curing agents should be selected depending on the type of thermosetting resin, and curing agents with different dissociation temperatures should be used depending on the drying process.

In the case of the solvent, DBE (Di Basic Ester), IPR (Isophorone), BC (Butyl cabitol), etc. are applied according to the color or workability of the thermosetting ink, and solvents having low volatility are excluded due to the characteristics of screen printing.

Next, look at the characteristics of the photolithography color ink according to the present invention.

Table 1 shows the results of experiments on the pattern formation characteristics and the color implementation characteristics according to the ratio of the photosensitive portion and the thermosetting ink.

The photosensitive portion was composed of a ratio of 46.05 wt% of a photobinder, 22.37 wt% of a photoinitiator, 28.95 wt% of a monomer and an oligomer, and 2.63 wt% of an additive. The composition ratio represents "photosensitive part: thermosetting ink."

Composition ratio Pattern formation characteristics Color implementation characteristics 20:80 No pattern formation Excellent color implementation 30:70 Pattern is formed but residues occur Excellent color implementation 40:60 Good pattern formation Excellent color implementation 50:50 Good pattern formation Excellent color implementation 60:40 Good pattern formation Excellent color implementation 65:35 Good pattern formation Excellent color implementation 70:30 Good pattern formation Color fades and hides less 80:20 Good pattern formation Color fades and hides less 90:10 Good pattern formation Color fades and hides less

When the content of the thermosetting ink is more than 35wt%, color implementation was excellent, but in the range where the content of the photosensitive portion was 30wt% or less, no pattern was formed or residues occurred even when the pattern was formed, and thus it was confirmed that the actual use was difficult.

On the other hand, when the content of the photosensitive portion is more than 40wt%, the pattern was formed well, but in the range of the content of the thermosetting ink is 30wt% or less, it was confirmed that the color was light and the hiding power was difficult to use. In particular, when the thermosetting ink is less than 10wt%, the reliability is poor in terms of adhesive force, hot water and coating film strength.

Through these results, it can be seen that the content of the thermosetting ink should be controlled in the range of 35 to 65.6 wt%.

Using the photoresist color ink according to an embodiment of the present invention was performed a printing process for the back of the window of mobile and IT devices.

1 is a flowchart illustrating a printing process using a photoresist color ink according to an embodiment of the present invention.

Silkscreen printing was performed using a 350-neck screen net and temporary drying was performed for 10 minutes at a temperature of 70 ° C. in an IR oven. The photoresist color ink according to the embodiment of the present invention was used for the color printing and the shielding printing, and the exposure process was performed with an intensity of 50 to 1000mj / cm ² except for the positions where the holes were formed, and the developing process was 0.1 The location where holes are to be formed is opened by performing with ˜1.0% Na ₂ CO ₃ . The drying was carried out in an IR oven at a temperature of 170 ° C. for 30 minutes.

In the illustrated embodiment, the silkscreen color printing is performed two times, but the present invention is not limited thereto and may be performed only once or three times or more. In addition, after performing the color printing and the shielding printing, the exposure-development process is performed for each, but only one exposure-development process may be performed if the color layer and the print layer have the same shape and dimensions.

2 is a flowchart showing a printing process using a conventional thermosetting ink.

Silkscreen printing conditions and temporary drying and the conditions of the present drying are the same as in the case of the present invention described above. However, when screen printing thermosetting ink, only one sheet should be printed at a time in order to align the holes (camera hole, sensor hole, speaker hole, etc.) by jig tolerance and printing tolerance due to the characteristics of screen printing.

On the other hand, in the case of using the photoresist color ink of the present invention according to FIG. 1, since the alignment of the holes (camera hole, sensor hole, speaker hole, etc.) is performed very accurately, printing for 6 to 8 sheets at a time Can be performed. As a result, despite the addition of the exposure-developing process, there is an excellent effect that the speed and efficiency of the overall process are greatly improved and the defect rate is also reduced.

Table 2 shows the experimental results for the photoresist color ink according to the embodiment of the present invention and the ink of the comparative example.

TABLE 2

CBPR-4096C: Chembase's acrylic binder, DETX: BASF's photoinitiator, OXE-01: BASF's photoinitiator, IGR-184: BASF's photoinitiator (Irgacure ^ㄾ -184), IGR-819: BASF's Abbreviation of photoinitiator (Irgacure ^8-819 ), PU640: 6 functional oligomer of Miwon SC, KDN-253: modified epoxy binder of Kukdo Chemical, PETIA: pentaerythritol triacrylate, DPHA: Dipentaerythritol Hexaacrylate, BI-180: Blocked Isocyanate

Examples 1 to 3 correspond to 45%, 55% and 65% of the content of the photosensitive portion derived based on Table 1, respectively, and Comparative Example 1 is a conventional thermosetting ink. Comparative Examples 2 and 3 are cases where the content of the photosensitive portion is 30% and 80%, respectively.

Examples 1 to 3 and Comparative Examples 2 to 3 performed the printing process in the order of FIG. 1, and the thermosetting ink of Comparative Example 1 was printed in the order of FIG. 2.

When six simultaneous printings were performed using a jig using a photoresist color ink according to an embodiment of the present invention, the pattern for the camera hole and the sensor hole was well formed by the exposure-development, and the pattern sharpness ( sharpness) is also good, and it can be seen that photolithography by the photosensitive portion was performed well. In addition, the reliability and color implementation are also good, it can be seen that the properties of the thermosetting ink also exhibited good.

On the other hand, in the case of Comparative Example 2, the content of the photosensitive portion was so small that no photolithography was performed, thus no pattern was formed, and only the reliability and color implementation according to the characteristics of the thermosetting ink were good. In the case of Comparative Example 3, the photolithography was performed due to the high content of the photosensitive portion, but there was a problem in reliability, such as disadvantages in the heat-resistant hot water and cross-cut (adhesion) experiments due to the low amount of thermosetting ink, and color implementation and hiding power. There is also a low problem.

On the other hand, in the case of silk screen printing using the thermosetting ink of Comparative Example 1, the reliability and color implementation are good, but the alignment error between the camera hole and the sensor hole occurs at a level of ± 80 μm. The process must be carried out precisely by chapter.

In the case of using the photolithography color ink according to the embodiment of the present invention, the alignment error between the camera hole and the sensor hole is only ± 0.5 μm, so that printing of several sheets (for example, 6 to 8 sheets) is performed at one time. Even if the hole alignment does not occur.

While the present invention has been described through the preferred embodiments, the above-described embodiments are merely illustrative of the technical idea of the present invention, and various changes may be made without departing from the technical idea of the present invention. Those of ordinary skill will understand. Therefore, the protection scope of the present invention should be interpreted not by the specific embodiments, but by the matters described in the claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

Claims (11)

Color ink that performs color printing on the back of the window of the display window, Optical binder in the range of 16.0 to 31.0 wt%; Photoinitiators in the range of 7.5-15.2 wt%; Combined monomers and oligomers in the range of 10.0 to 19.5 wt%; Additive in the range from 0.9 to 1.8 wt%; And Includes a thermosetting ink in the range of 35.0 to 65.6 wt%, The thermosetting ink is a thermosetting resin which is at least one selected from pigments, epoxy, acryl and urethane, a thermosetting agent which is a block isocyanate or a latent curing agent, and a solvent which is at least one selected from DBE (Di Basic Ester), IPR (Isophorone) and BC (Butyl cabitol). Including, The additive is a photolithographic color ink, characterized in that a saturated or unsaturated fatty acid having a carboxyl group and composed of an even number of 12 to 24 carbon atoms. The method according to claim 1, The optical binder is a photolithography color ink, characterized in that one of the acrylic binder, cellulose, epoxy acrylate. The method according to claim 1, The monomer is a photolithography color ink, characterized in that the acrylic monomer or urethane monomer in the range of 3 to 6 functional groups. The method according to claim 1, The oligomer is a photolithography color ink, characterized in that the urethane-based oligomer or epoxy-based oligomer of the 4-6 functional group range. The method according to claim 1, The photoinitiator is a photolithography color ink, characterized in that at least one selected from α-Hydroxyketone, Phenylglyoxylate, α-Aminoketone, Mono Acyl Phosphine (MAPO) and oxime system. The method according to claim 1, A photolithographic color ink further comprising a dispersant having an amine and an acid group. The method according to claim 1, A photolithographic color ink, further comprising a wax or a surface tension increasing agent. The method according to claim 1, A photolithographic color ink, further comprising an antifoaming agent. The method according to claim 1, A photolithographic color ink further comprising SiO ₂ or TiO ₂ . The method according to claim 1, A photolithographic color ink, further comprising fumed silica. A method of performing color printing on the back of a window, Using the photolithography color ink of claim 1, in order to form a hole formed in the window, a process of forming a pattern by performing an exposure process and a development process is performed.

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