TW201529760A - Ink composition for pad printing - Google Patents

Abstract

Disclosed is an ink composition for pad printing, which includes a coloring agent, a binder resin, a polymerization initiator, and solvent, wherein a phase angle represented by Formula 1 is 45 DEG or more but less than 90 DEG, thereby printing properties of the pad printing may be significantly improved, and the ink smeared on the pad is completely transferred to a printing region with no region not filled with ink.

Description

Pad printing ink composition

This invention relates to pad printing ink compositions, and more particularly to pad printing ink compositions having significantly improved printing properties.

Typically, a touch screen is a screen with a special input device that receives a position input by a user's finger or stylus touching the screen. Such a touch screen does not use a keyboard, but has a configuration of a multi-layer laminate in which a user's finger or object (such as a touch pen or stylus) contacts a particular character or position displayed on the screen. The touch screen can recognize the location and receive data directly from the screen to actually process the information at a particular location by storing the software within it.

Fig. 1 shows an image display device (mobile phone) having a touch screen panel in which a display portion refers to a portion where an image is displayed, and a non-display portion refers to a peripheral portion where an image is not displayed. Such a non-display portion, which is the outermost layer seen by the user, includes a shielding layer formed thereon to prevent lower wiring from being exposed to the user, wherein the shielding layer can be formed with various patterns. For example, company logos, graphics, IR graphics, and more. These patterns can be formed in the concave grooves, and the concave grooves are formed on the shielding layer.

Recently, as a method of forming a pattern of a non-display portion, a pad printing method has been proposed. The pad printing method is a printing method that can transfer a 2-D image to a 3-D object, and is a method of transferring an image transmitted by the printing plate to a 3-D printed object using a cushion such as a cymbal. The pad printing method is printed by a simple printing method and has the advantage that the image can be printed even on an uneven 3-D surface.

In such pad printing, when an area that is not filled with ink appears in the printing area, an unprinted portion may be generated, and light may leak to the outside through the unprinted portion, or the lower wiring may be exposed to the Externally visible. Due to these problems, when performing pad printing, an ink having excellent transfer force and printing properties is required.

For example, a conductive ink composition and a method for producing the same are disclosed in Korean Patent Publication No. 2012-0080878.

Accordingly, it is an object of the present invention to provide a pad printing ink composition having improved printing properties.

The above objects of the present invention will be achieved by the following features:

(1) A pad printing ink composition comprising a colorant, a binder resin, a polymerization initiator, and a solvent, wherein the phase angle shown in Formula 1 is 45 or more, but less than 90: [ Equation 1] Phase angle δ = arctangent (G"/G') (where G" represents the loss modulus of the ink composition, and G' represents the storage modulus of the ink composition).

(2) The ink composition according to (1) above, wherein the phase angle is frequency-scanned at an angular frequency of from 0.1 rad/s to 100 rad/s while being measured by applying a stress of 1% at room temperature.

(3) The ink composition according to (1) above, wherein the frequency sweep is performed at an angular frequency of 0.1 rad/s to 100 rad/s while the phase angle measured at a room temperature of 1% is 45° Or larger, but less than 85°.

(4) The ink composition according to (1) above, wherein the ink composition is a pattern for forming a non-display portion of the window substrate.

(5) The ink composition according to (4) above, wherein the pattern comprises an image, a pattern, a logo or an IR pattern.

According to the ink composition of the present invention, the printing property of the pad printing can be remarkably improved. Thereby, the ink applied to the pad is completely transferred to the printing area without an area that is not filled with ink.

In addition, when the ink composition of the present invention is used for pad printing, contamination of printed articles and printing instruments can be minimized.

The present invention discloses a pad printing ink composition comprising a coloring agent, a binder resin, a polymerization initiator and a solvent, wherein the phase angle shown in Formula 1 is 45° or more, but less than 90°. This can significantly improve the printing properties of the pad printing, and the ink applied to the pad is completely transferred to the printing area without areas that are not filled with ink.

The invention will be described in detail below.

The present invention contemplates that when the phase angle shown in Formula 1 is 45 or more but less than 90, the printing property of the pad printing can be remarkably improved, and the present invention is completed. When the phase angle is within the above range, the ink applied to the pad is completely transferred to the printing area, and thus there is no area that is not filled with ink. On the other hand, if the phase angle is less than 45, the ink applied to the pad is not completely transferred to the printing area, and thus the printing property of the pad printing may be deteriorated due to the partial filling of the ink.

[Formula 1] Phase angle δ = arctangent (G"/G') (wherein G" represents the loss modulus of the ink composition, and G' represents the storage modulus of the ink composition).

Traditionally, when the pad is pressed into the printing zone and then the pad is separated from the printing zone during pad printing, the transferred ink can increase with the pad. The increased ink may contaminate the location of the printed area (eg, printed items, printing instruments, etc.). On the other hand, since the ink composition of the present invention has the above-described phase angle range, the occurrence of this problem can be reduced.

The phase angle can be measured using a rheometer by methods known in the art. In the example of the present invention, the phase angle is frequency scanned at an angular frequency of 0.1 rad/s to 100 rad/s while being measured at room temperature (e.g., 15 ° C to 25 ° C) with a 1% stress. The phase angle can be measured by frequency sweeping at an angular frequency of 0.1 rad/s to 10 rad/s.

In terms of preventing contamination, it is preferred to perform a frequency sweep at an angular frequency of 0.1 rad/s to 100 rad/s while applying a 1% stress at room temperature to measure a phase angle of 45 or more. Large, but less than 85°.

The method of controlling the phase angle is not particularly limited. For example, the phase angle may be based on the type, content and particle size of the coloring agent incorporated in the ink composition of the present invention; the type, content and degree of polymerization of the binder resin; the type and content of the polymerization initiator; the type and content of the solvent, etc. And control.

The article to be printed by the ink composition of the present invention is not particularly limited as long as the pad printing method can be applied. For example, the object to be printed may be a window substrate of the image display device. In particular, the ink compositions of the present invention can be used to form non-display portions of window substrates.

In the present invention, the non-display portion refers to a peripheral portion in which an image is not displayed in the image display device, as shown in Fig. 1.

Such a non-display portion is the outermost layer seen by the user and includes a shielding layer formed thereon to prevent lower wiring from being exposed to the user.

In addition, various patterns such as images, patterns, logos, or IR patterns can be formed on the shield layer of the non-display portion. Herein, the IR pattern refers to a pattern of a non-opaque portion through which a sensor such as a illuminating sensor, a proximity sensor, or the like can pass a specific wavelength. Light (for example, infrared light).

Conventionally, when an area that is not filled with ink appears in a printing area during printing of a non-display portion, an unprinted portion may be generated, and light may leak to the outside through an unprinted portion, or a lower wiring may occur. Exposure to the outside can be seen. However, when the ink composition of the present invention is used, the ink applied to the pad is completely transferred to the printing area without an area which is not filled with ink, whereby a pattern having excellent printing accuracy can be formed, and The above problem does not occur.

The pad ink composition of the present invention comprises a colorant, a binder resin, a polymerization initiator, and a solvent.

The colorant may include, for example, an organic colorant such as a pigment, a dye, a synthetic or natural color, or an inorganic colorant such as a metal oxide, a metal complex, barium sulfate (extension dye), and the like.

As the coloring agent, a compound classified into a coloring matter and a dye according to a color index (Dye and Color Institute) may be used alone or in combination of two or more.

Specific examples of the pigment may include: CI Pigment Yellow 1, 12, 13, 14, 15, 16, 17, 20, 24, 31, 53, 83, 86, 93, 94, 109, 110, 117, 125, 128 , 137, 138, 139, 147, 148, 150, 153, 154, 166, 173, 180, 185; CI pigment orange 13, 13, 36, 38, 40, 42, 43, 51, 55, 59 , 61, 64, 65, 71, 73; CI pigment red 9, 9, 97, 122, 123, 144, 149, 166, 168, 176, 177, 180, 192, 215, 216, 224, 242, 254, 255, 264, 265; CI pigment blue 15th, 15:3, 15:4, 15:6, 60; CI pigment purple 1, 14, 19, 23, 29, 32, 33, 36 No. 37, 38; CI pigment green No. 7, 10, 15, 25, 36, 47; CI pigment brown No. 23, 25, 28; CI pigment black No. 1, No. 7, carbon black and the like.

Specific examples of the dye may include: CI solvent yellow Nos. 2, 14, 16, 33, 34, 44, 56, 82, 93, 94, 98, 116, 135; CI solvent orange 1, 3, 7, No. 63; CI solvent red Nos. 1, 2, 3, 8, 18, 23, 24, 27, 35, 43, 45, 48, 49, 91:1, 119, 135, 140, 196, 197; CI solvent Purple Nos. 8, 9, 13, 26, 28, 31, 59; CI Solvent Blue Nos. 4, 5, 25, 35, 36, 38, 70; CI Solvent Green Nos. 3, 5, and so on.

In addition to the above examples, the pigment may also include: inorganic pigments such as carbon black, zinc oxide, red iron oxide, chromium oxide, iron ink, cobalt blue, iron oxide yellow, chrome green, zinc sulfide, zinc antimony white, cadmium yellow, Zhuhong, cadmium red, chrome yellow, molybdenum orange, zinc chromate, barium chromate, white carbon, clay, talc, ultramarine, precipitated barium sulfate, barium sulfate powder, calcium carbonate, lead white, Prussian blue, manganese violet, aluminum Powder, brass powder, etc.; organic pigments such as azopyridine, insoluble azo pigment, chelated azo pigment, phthalocyanine pigment, anthraquinone and anthraquinone pigment, leek pigment, quinophthalone pigment, dye A pyridine nitro pigment, a nitroso pigment, and the like.

Further, the coloring agent of the present invention may also be a white coloring agent.

The white coloring agent is not particularly limited, and if it is commonly used in the art, it may include, for example, CI color white 4, 5, 6, 6: 1, 7, 18, 18: 1, 19, 20, 22 , 25, 26, 27, 28, 32, aluminum white and so on. Preferably, C.I. Pigment White No. 6 or White No. 22 can be used in terms of reflection efficiency and whiteness. These may be used singly or in combination of two or more.

TiO ₂ contained in CI Pigment White No. 6 is inexpensive, but has a high refractive index to exhibit excellent shielding ratio and reflection, whereby it can be used as an effective white colorant. Preferably, the above TiO ₂ has a rutile structure.

The white colorant may be subjected to various treatments as needed, for example, resin treatment; surface treatment with a dye derivative into which an acidic group or a basic group is introduced; graft treatment with a polymer compound or the like onto the surface of the dye; Atomization treatment of the method; cleaning treatment using an organic solvent or water to remove impurities; ion impurity removal treatment using an ion exchange method; or the like.

The colorant may further include other white pigments within the scope of the object of the present invention.

The content of the colorant can be controlled according to the desired color characteristics, for example, in an amount of 3 to 50 wt.%, preferably 7 to 40 wt.%, based on the total weight of the ink composition. When the colorant is incorporated in an amount of from 3 to 50 wt.%, it provides excellent coloring properties and shielding properties without degrading printing properties.

The binder resin plays a role of supporting the pattern, and the kind thereof is not particularly limited as long as it is any thermosetting resin known and used in the ink composition.

The binder resin may include, for example, an acrylonitrile-based resin having an ethylenically unsaturated group. This resin may include a copolymer prepared by copolymerization of a monomer having an acidic group and another monomer copolymerizable with the same monomer.

The monomer having an acidic group may include, for example, (meth)acrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, monomethyl maleic acid, isoprenesulfonic acid, styrenesulfonic acid. Etc., they may be used singly or in combination of two or more.

The monomer copolymerizable with the monomer having an acidic group may include, for example, styrene, chlorostyrene, α-methylstyrene, vinyltoluene, methyl (meth)acrylate, (meth)acrylic acid. Ethyl ester, butyl (meth)acrylate, benzyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, isobutyl (meth)acrylate, (methyl) Tri-butyl acrylate, cyclohexyl (meth) acrylate, isodecyl (meth) acrylate, 2-phenoxyethyl (meth) acrylate, tetrahydroindenyl (meth) acrylate Ester, hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-3-chloropropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate Ester, mercaptooctyloxy-2-hydroxypropyl (meth)acrylate, ethylhexyl acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxy (meth)acrylate Butyl ester, ethoxyethylene glycol (meth)acrylate, methoxytriethylene glycol (meth)acrylate, methoxytripropylene glycol (meth)acrylate, methoxy (meth)acrylate Polyethylene glycol ester, (meth) propyl Acid phenoxy diethylene glycol ester, p-nonylphenoxy polyethylene glycol (meth)acrylate, p-nonylphenoxy polypropylene glycol (meth)acrylate, (meth)acrylic acid Fluoropropyl ester, 1,1,1,3,3,3-hexafluoroisopropyl (meth)acrylate, octafluoropentyl (meth)acrylate, heptafluoroantimony (meth)acrylate Base ester, triboronyl (meth)acrylate, β-(methyl)decyl ethoxide succinate, methyl-α-hydroxymethyl acrylate, ethyl-α-hydroxyl acrylate A base ester, propyl-α-hydroxymethyl acrylate, butyl-α-hydroxymethyl acrylate or the like may be used alone or in combination of two or more.

The binder resin copolymer of the present invention can be reacted with a reactive monomer for introducing an ethylenically unsaturated group, as needed. Examples of such reactive monomers may include glycidyl (meth)acrylate, vinylbenzyl epoxypropyl ether, vinyl epoxypropyl ether, allyl epoxypropyl ether, 4- Methyl-4,5-epoxypentene, γ-glycidoxytrimethoxydecane, γ-glycidoxymethyldiethoxydecane, γ-glycidoxytriethoxydecane, A thiol-based derivative or the like, which may be used singly or in combination of two or more.

Further, the binder resin may also include, for example, a resin having an olefinic double bond in a side chain, for example, polyethylene oxide, polyvinylpyrrolidone, polyamine, polyurethane, polyether, polyester, or the like.

The method for preparing the copolymer is not particularly limited, but may include a bulk polymerization, a solution polymerization, an emulsion polymerization or a suspension polymerization which is commonly used in the art.

The content of the binder resin is not particularly limited insofar as it can exert its function. For example, the binder resin may be included in an amount of from 1 to 85 wt.% based on the total weight of the ink composition. When the content of the binder resin is within the above range, the character of the support pattern and the transcription rate of the pattern can be increased, thereby improving the yield and the process efficiency.

The binder resin of the present invention may further comprise a polyfunctional monomer having an ethylenically unsaturated double bond.

The polyfunctional monomer having an ethylenically unsaturated double bond is a component that enhances the strength of the pattern and may include a mono- to hexa-functional monomer. Specific examples thereof may include: mono-functional monomers such as decyl phenyl carbitol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-ethylhexyl carbitol acrylate, 2-hydroxy acrylate Ethyl ester, N-vinyl pyrrolidone, etc.; di-functional monomer, such as 1,6-hexanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, di(a) Neopentyl glycol acrylate, triethylene glycol di(meth)acrylate, bis(acryloyloxyethyl)ether of bisphenol A, 3-methylpentane di(meth)acrylate Alcohol esters and the like; tri-functional monomers such as trimethylolpropane tris(meth)acrylate, pentaerythritol tri(meth)acrylate, etc.; tetra-functional monomers such as pentaerythritol tetrakis(meth)acrylate An ester or the like; a penta-functional monomer such as dipentaerythritol pentyl (meth)acrylate; and the like; a hexa-functional monomer such as dipentaerythritol hexa(meth)acrylate, etc., which may be used alone or in combination. Use a variety of.

The polyfunctional monomer having an ethylenically unsaturated double bond may be included in an amount of from 1 to 10 wt.% of the total 100 wt.% of the ink composition. Within the above range of contents, the desired pattern strength can be achieved.

The polymerization initiator may be any thermal polymerization initiator known in the art, particularly a thermal polymerization initiator comprising a phosphonium cation and a ruthenium anion, as compared to other types of thermal polymerization initiators, Excellent stability of time and high shrinkage characteristics are preferable in view of improvement in adhesion between an object to be printed and an ink composition. Such a polymerization initiator may be used singly or in combination of two or more.

Specific examples of the phosphonium cations contained in the polymerization initiator may include triphenylsulfonium, tris(4-methylphenyl)phosphonium, tris(4-isopropylphenyl)phosphonium, and tris(2,6-dimethyl Phenyl)anthracene, tris(4-cyanophenyl)anthracene, tris(4-chlorophenyl)anthracene, diphenyl(4-hydroxyphenyl)anthracene, methylphenyl(4-hydroxyphenyl)anthracene, Dibenzylphenyl hydrazine, dibenzyl (4-hydroxyphenyl) hydrazine, benzylmethyl (4-hydroxyphenyl) fluorene, benzylmethyl (4-acetoxyphenyl) fluorene, methyl (4-hydroxyphenyl)(2-methylphenyl)phosphonium, dimethyl(methoxy)phosphonium, dimethyl(ethoxy)phosphonium, dimethyl(propoxy)phosphonium, dimethyl (butoxy) hydrazine, dimethyl (octyloxy) hydrazine, dimethyl (octadecyloxy) hydrazine, dimethyl (isopropoxy) hydrazine, dimethyl (third-butoxy)鋶, dimethyl (cyclopentyloxy) hydrazine, dimethyl (cyclohexyloxy) hydrazine, dimethyl (fluoromethoxy) hydrazine, dimethyl (2-chloroethoxy) hydrazine, two Methyl (3-bromopropoxy) fluorene, dimethyl (4-cyanobutoxy) hydrazine, dimethyl (8-nitrooctyloxy) hydrazine, dimethyl (18-trifluoromethyl decene) Octaoxy)anthracene, dimethyl(2-hydroxyisopropoxy)anthracene, dimethyl(tris(trichloromethyl)methyl)anthracene and many more. Among these, triphenylphosphonium, tris(4-methylphenyl)phosphonium, benzylmethyl(4-hydroxyphenyl)phosphonium, benzylmethyl (4-acetoxyphenyl) are preferably used. Indole and methyl (4-hydroxyphenyl) (2-methylphenyl) anthracene, and more preferably tris(4-methylphenyl)anthracene, benzylmethyl(4-ethyloxyphenyl)anthracene And benzylmethyl (4-hydroxyphenyl) fluorene.

Further, the kind of the anion contained in the polymerization initiator is also not particularly limited, but may include, for example, a halogen ion such as F ^- , Cl ^- , Br ^- , I ^- etc.; OH ^- ; ClO ₄ ^- ; Acid ions, for example, FSO ₃ ^- , ClSO ₃ ^- , CH ₃ SO ₃ ^- , C ₆ H ₅ SO ₃ ^- , CF ₃ SO ₃ ^-, etc.; sulfate ions, for example, HSO ₄ ^- , SO ₄ ^{2- ,} etc.; Ions, for example, HCO ₃ ^- , CO ₃ ^{2- ,} etc.; phosphate ions, for example, H ₂ PO ₄ ^- , HPO ₄ ^2- , PO ₄ ^3-, etc.; fluorophosphate ions, for example, PF ₆ ^- , PF ₅ OH ^- And other; boric acid ions, for example, BF ₄ ^- , B(C ₆ F ₅ ) ₄ ^- , B(C ₆ H ₄ CF ₃ ) ₄ ^-, etc.; AlCl ₄ ^- ; BiF ₆ ^- ; fluoroantimonic acid ions, for example, SbF ₆ ^- , SbF ₅ OH ^-, etc.; fluoroarsenic acid ions, for example, ASF ₆ ^- , AsF ₅ OH ^- and the like.

The content of the polymerization initiator is not particularly limited insofar as it can exert its function. For example, the polymerization initiator may be included in an amount of 0.1 to 10 wt.% based on the total weight of the ink composition, and preferably 0.1 to 3 wt.%. When the content of the polymerization initiator is in the range of 0.1 to 10 wt.%, favorable polymerization degree and coating property can be attained, and in addition, adhesion of an object to be printed can be effectively improved.

The solvent may include, for example, an ethylene glycol monoalkyl ether, for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol single, in view of solubility, dispersion or coating properties of a colorant or the like. Propyl ether, ethylene glycol monobutyl ether, etc.; diethylene glycol dialkyl ether, for example: diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether , diethylene glycol dibutyl ether, etc.; ethylene glycol monoalkyl ether acetate, for example: methyl cellulose acetate (methylcellosolve acetate), ethyl celecoxib acetate, etc.; alkyl alcohol alkyl Ether acetate, for example: monomethyl ether propylene glycol acetate, monoethyl ether propylene glycol acetate, monopropyl ether propylene glycol acetate, methoxybutyl acetate, methoxypentyl acetate; aromatic hydrocarbons, For example: benzene, toluene, xylene, etc.; ketones, such as: methyl ethyl ketone, acetone, methyl amyl ketone, methyl isobutyl ketone, cyclohexanone, etc.; alcohols, such as: ethanol, methanol, propanol , butanol, hexanol, cyclohexanol, ethylene glycol, glycerin, etc.; cyclic esters, such as: γ-butyrolactone; etc.; isobutyl acetate; Monomethyl ether; diethylene glycol monobutyl ether; dibasic acid esters and the like. These are used singly or in combination of two or more.

The content of the solvent is not particularly limited insofar as it can exert its function. For example, the solvent may be included in an amount of 10 to 90 wt.%, based on the total weight of the ink composition, and preferably 20 to 60 wt.%. When the content of the solvent is in the range of 10 to 90 wt.%, the ink composition can maintain favorable coloring ability while being easily pad printed.

The ink composition of the present invention can be used in combination with at least one additive, for example, a surfactant, a filler, a curing agent, an adhesion enhancer, an antioxidant, a UV absorber, a dispersant, etc., which can be The needs of the present invention are used in combination with the above components within the range not impairing the object of the present invention.

The preferred embodiments are described below to more specifically understand the present invention. However, it is obvious to those skilled in the art that the specific embodiments are provided for the purpose of illustration, and are not intended to limit the scope of the appended claims. Modifications and variations are possible, and such modifications and changes are appropriately incorporated in the invention as defined in the appended claims. Sample examples and comparative examples

The ink composition having the composition and content listed in the following Table 1 was prepared by adjusting the component parts of the individual products. [Table 1] Experimental example (1) Measurement of phase angle

The storage modulus and loss modulus of the ink compositions prepared in the examples and comparative examples were measured using MCR-302 (Anton Paar Co.) in a frequency scanning mode (0.1 rad/s to 10 rad/s or 0.1 rad/s). Measured to an angular frequency of 100 rad/s while applying a 1% stress at 25 °C. The phase angle is calculated from the measured storage modulus and loss modulus, and the results obtained are shown in Table 2 below. (2) Evaluation of printing properties

The pattern of the non-display portion is formed by printing on a non-display portion in a concave groove having a diameter of 6 mm and a depth of 25 mm, which is used by the pad printing method using the ink compositions of the examples and comparative examples. Provides a shield for the window glass. Printing was carried out using a mat made of polydimethyl siloxane.

The pattern formed by the non-display portion was observed by an optical microscope to define the occurrence of light leakage, and the results obtained are shown in Table 3 below. ○: no light leakage was observed X: light leakage was observed

2 to 6 show the printing results of the ink compositions using the examples 1 to 5, and Fig. 7 shows the printing results of the ink compositions of the comparative examples. (2) Assessment of pollution occurrence in non-printing areas

When the pad is pressed into the printing area and then the pad is separated from the printing area during pad printing, if the transferred ink increases with the pad, another area that is not the printing area may be contaminated. In this regard, when the mat was raised to the maximum height, an increase in the ink as the mat was observed, and contamination occurrence in the non-printing area was evaluated according to the following criteria. The results obtained are shown in Table 3 below. ○: The ink does not increase with the pad △: The ink slightly increases with the pad X: A large amount of ink increases with the pad

Referring to Table 3 above, it was confirmed that in the example of printing using the ink compositions of Examples 1 to 5, there was no area which was not filled with ink, and no light leakage occurred, so the printing property was remarkably improved. Further, during the separation of the mat from the printing area after printing, the ink does not increase with the mat, and thus does not contaminate the periphery of the printing area.

Meanwhile, in the example of printing using the ink composition of Example 6, since the phase angle exceeded the preferred range of 85°, there was slight contamination around the printing area, but the overall performance was excellent.

However, in the example of printing using the ink composition of the comparative example, an area which is not filled with ink appears in the printing area, resulting in an unprinted portion, and light leaks through the unprinted portion.

no

The above and other objects, features and other advantages of the present invention will become more apparent from Fig. 2 is a photograph of a printed area when printing is performed using the ink composition prepared in Example 1, and Fig. 3 is a photograph of a printed area when printing is performed using the ink composition prepared in Example 2; When printing is performed using the ink composition prepared in Example 3, a photograph of the printed area is taken; FIG. 5 is a photograph of the printed area when the ink composition prepared in Example 4 is used for printing; and FIG. 6 is a photograph prepared by using the example 5. When the ink composition was printed, a photograph of the printing area was taken; and Fig. 7 is a photograph of the printing area when printing was performed using the ink composition prepared in the comparative example.

Claims (5)

A pad printing ink composition comprising: a colorant, a binder resin, a polymerization initiator, and a solvent, wherein a phase angle represented by Formula 1 is 45° or more, but less than 90°: 1] Phase angle δ = arctangent (G"/G') (where G" represents a loss modulus of the ink composition, and G' represents a storage modulus of the ink composition). The ink composition of claim 1, wherein the phase angle is frequency-scanned at an angular frequency of from 0.1 rad/s to 100 rad/s while being measured by applying a stress of 1% at room temperature. An ink composition according to claim 1, wherein the frequency sweep is performed at an angular frequency of 0.1 rad/s to 100 rad/s while the phase angle measured by applying a stress of 1% at room temperature is 45. ° or larger, but less than 85°. The ink composition of claim 1, wherein the ink composition is a pattern for forming a non-display portion of a window substrate. The ink composition of claim 4, wherein the pattern comprises an image, a pattern, a logo or an IR pattern.