KR20100081163A - Black paste - Google Patents

Abstract

PURPOSE: A black paste is provided to minimize the undercut of a black matrix during a plasticizing process and suppressing residue by including oligomer with one functional group. CONSTITUTION: Bus electrodes(311b, 312b) are formed on a transparent electrode. A black matrix(315) is formed on an upper substrate. The black matrix is composed of a first black matrix and a second black matrix(311c, 312c). A protective layer(314) protects an upper dielectric layer from the spit of charged particles which are generated while gas is being discharged. An address electrode crosses a scan electrode and a sustain electrode. A lower dielectric layer and a partition wall are formed on a lower substrate(320).

Description

Black paste {Black paste}

The present invention relates to a black paste, and more particularly, to a black paste containing an oligomer having a monofunctional group.

In general, a plasma display panel (PDP) injects a discharge gas into a discharge cell separated by a partition wall, and is caused by an energy difference when ultraviolet rays generated during plasma emission excite phosphors and return to a ground state. A display device using a light emission phenomenon of visible light.

The plasma display panel includes an upper panel, which is a display surface on which an image is displayed, and a lower panel coupled in parallel thereto, and the upper panel includes a plurality of sustain electrode pairs formed by pairing a scan electrode and a sustain electrode on the upper substrate. In the lower panel, a plurality of address electrodes are arranged on the lower substrate to intersect a plurality of pairs of sustain electrodes formed in the upper panel.

The scan electrode and the sustain electrode include a bus electrode which is a metal electrode. On the other hand, when forming the bus electrode, in order to improve the contrast of the screen, a black matrix layer may be printed with black paste, and the bus electrode may be printed with conductive silver (Ag) paste thereon to form an electrode having a two-layer structure.

However, in this case, the lower portion of the black matrix may not be sufficiently exposed, and thus the black matrix layer may not be formed accurately. That is, the etching deepens toward the lower portion of the black matrix BM, and the under-cut phenomenon that occurs may reduce the reliability of plasma display panel fabrication.

An object of the present invention is to provide a black paste that can minimize the undercut of the black matrix to suppress the residue and improve the straightness of the formed electrode.

The black paste according to the present invention for achieving the above object, 3 to 20 wt% oligomer having a monofunctional group, 22 to 35 wt% binder, 14 to 20 wt% photopolymerizable monomer, 2 to 10 wt% glass frit , Black powder 5-15 wt% and solvent 26-35 wt%.

According to the present invention, since the black paste includes an oligomer having a monofunctional group, it is possible to minimize the undercut of the black matrix during firing to suppress the residue and to improve the straightness of the formed electrode.

Hereinafter, with reference to the drawings will be described the present invention in more detail.

Black paste according to an embodiment of the present invention is an oligomer having a monofunctional group 3 to 20 wt%, binder 22 to 35 wt%, photopolymerizable monomer 14 to 20 wt%, glass frit 2 to 10 wt%, black powder 5 To 15 wt% and solvent 26 to 35 wt%.

First, the oligomer having a monofunctional group is used to promote photocuring of the black paste, and may contain a carboxyl group.

Since the oligomer having a monofunctional group contains a relatively large number of double bonds capable of reacting with light as compared to the binder, the curing rate of the black paste is improved upon exposure of the black paste for forming the black matrix. As a result, the line width can be maintained by preventing undercut of the black paste.

On the other hand, as the number of functional groups included in the oligomer increases as a result of more reactions during exposure, it may be difficult to maintain a desired line width. Therefore, it is preferable that the functional group contained in an oligomer is monofunctional.

If the content of such oligomer is less than 3 wt%, it is difficult to prevent the undercut of the black paste because the improvement of the curing speed of the black paste is low. On the other hand, if the content of the oligomer exceeds 20 wt%, a short circuit may occur between adjacent electrodes due to the spreading of the paste. Therefore, the content of the oligomer having a monofunctional group is preferably 3 to 20 wt%.

The binder functions as a binder of each component before firing, and is preferably prepared by suspension polymerization for uniformity. The binder may include a resin containing a carboxyl group, specifically, a carboxyl group-containing photosensitive resin having an ethylenically unsaturated double bond and a carboxyl group-containing resin not having an ethylenically unsaturated double bond.

For example, i) obtained by adding an ethylenically unsaturated group as a pendant to a copolymer of a carboxyl group-containing resin obtained by copolymerizing an unsaturated carboxylic acid and a compound having an unsaturated double bond, and ii) an unsaturated carboxylic acid and a compound having an unsaturated double bond. Carboxyl group-containing photosensitive resin, and iii) carboxyl group-containing photosensitive resin obtained by reacting a copolymer of an acid anhydride having an unsaturated double bond with a compound having an unsaturated double bond, with a hydroxyl group and a compound having an unsaturated double bond, but not limited thereto. It doesn't happen.

The binder may be used alone or in combination with the various carboxyl group-containing resins described above, and may be included in an amount of 22 to 35 wt%.

In the case where the binder is contained in less than 22 wt%, the distribution of the binder in the coating film to be formed may become uneven, and patterning by selective exposure and development may be difficult. On the other hand, when it exceeds 35 wt%, it is not easy to cause pattern collapse or line width shrinkage during firing of the electrode.

The photopolymerizable monomer is used to promote photocurability of the black paste and to improve developability.

As the photopolymerizable monomer, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, polyurethane diacrylate, trimethylol propane Triacrylate, pentaerythrite triacrylate, pentaerythrite tetraacrylate, trimethylolpropane ethylene oxide modified triacrylate, trimethylolpropanepropylene oxide modified triacrylate, dipentaery little pentaacrylate, dipentaeryse Little hexaacrylate and each methacrylate corresponding to the said acrylate; Mono-, di-, tri- or more polyesters of polybasic acids such as phthalic acid, adipic acid, maleic acid, ataconic acid, succinic acid, trimellitic acid and terephthalic acid with hydroxyalkyl (meth) acrylates. However, it is not limited to a specific thing, These can be used individually or in combination of 2 or more types.

When the photopolymerizable monomer is included in less than 14 wt%, it may be difficult to obtain sufficient photocurability, and when it exceeds 20 wt%, curing unevenness may occur because the photocuring becomes too fast. Therefore, the photopolymerizable monomer may be included 14 to 20 wt%.

In addition, the glass frit may be included in 2 to 10 wt%. If the glass frit is included at less than 2 wt%, the adhesion strength of the film to the substrate may not be sufficient, whereas if it is added in excess of 10 wt%, the sinterability of the film may be lowered.

Although it does not restrict | limit especially as a composition of a glass frit, It is preferable that the glass transition temperature (Tg) of a glass frit is 350-550 degreeC. When the glass transition temperature (Tg) of the glass frit is 350 ° C. or higher, generation of bubbles or expansion is suppressed. When the glass frit is 550 ° C. or less, adhesion to the substrate is excellent, and shape defects such as pinholes and edge curls are effectively prevented. Can be suppressed.

Further, in the present invention, the glass frit is preferably glass fine particles having an average particle size (D50) in the range of 0.5 to 2 µm in order to effectively produce a firing pattern without pinholes.

The black powder is calcined at a high temperature in the substrate manufacturing process of the PDP, and therefore, at least two kinds of single metal oxides and / or metal elements such as Cu, Fe, Cr, Mn, Co, Ru, and La have high color stability at high temperatures. The complex oxide containing can be used preferably. At this time, it is preferable that the average particle diameter of a black powder is 0.1-2 micrometers.

When the average particle diameter of black powder is less than 0.1 micrometer, the precision of the pattern formation by exposure falls, the linearity of a line edge or sufficient black plastic film is hard to be obtained, and a hiding power may fall and it may show transparency. On the other hand, when the average particle diameter exceeds 2 µm, the compactness of the fired film is deteriorated, and the blackness of the formed film is lowered, and the surface area of the particles is so large that undercut occurs easily during development.

Moreover, as a compounding quantity of black powder, 5-15 weight% is preferable. When the compounding quantity of black powder is less than 5 wt%, sufficient black may not be obtained after baking, and when it exceeds 15 wt%, light transmittance falls and it is easy to produce undercut.

The solvent may dissolve the binder, and may be used having a boiling point of 150 degrees or more while being well mixed with other additives. These include a-terpinol, buty cabitol acetate, texanol, buty cabitol, di-propylene glycol monomethyl ether ), But is not limited to such.

Such solvents are preferably comprised between 26 and 35 wt%. If the content of the solvent is less than 26 wt%, it may be difficult to apply the paste uniformly on the substrate, whereas if it contains more than 35 wt%, it is not preferable because the adhesion to the substrate is poor.

Moreover, the black paste of this invention is benzoin and benzoin alkyl ether, such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, as a photoinitiator; Acetophenones such as acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, and 1,1-dichloroacetophenone; 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butane-1 Aminoacetophenones such as, 2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butane; Anthraquinones such as 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone and 1-chloroanthraquinone; Thioxanthones, such as 2, 4- dimethyl thioxanthone, 2, 4- diethyl thioxanthone, 2-chloro thioxanthone, and 2, 4- diisopropyl thioxanthone; Ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; Benzophenones such as benzophenone; Or xanthones; (2,6-dimethoxybenzoyl) -2,4,4-pentylphosphineoxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine jade Phosphine oxides such as seeds and ethyl-2,4,6-trimethylbenzoylphenylphosphinate; Various peroxides etc. are mentioned, These known conventional photoinitiators can be used individually or in combination of 2 or more types.

In addition, the black paste which concerns on this invention can mix | blend other additives, such as a defoaming and leveling agent, such as a silicone type and an acryl type, and a silane coupling agent for improving the adhesiveness of a film as needed.

1 is a cross-sectional view illustrating a bus electrode manufacturing process of a plasma display panel, and FIG. 2 is a cross-sectional view illustrating an under-cut phenomenon of an electrode. Although FIG. 1 illustrates the case of including an ITO electrode, it may be applied to an electrode structure without ITO.

As shown in (a) of FIG. 1, the transparent electrode 120 formed of ITO is formed on the upper substrate 110 by sputtering, ion plating, chemical vapor deposition, and electrodeposition. Paste 130 is applied. The organic solvent is then evaporated by drying in a hot air circulation drying furnace or a far infrared drying furnace.

Subsequently, as shown in (b), the electrode paste 140 is applied onto the black paste 130 by an appropriate method such as a printing method, a bar coater, a blade coater, and then dried.

Subsequently, as shown in (c), the mask 150 having a predetermined pattern is positioned on the upper substrate 110 to which the electrode paste 140 is applied. In this case, the mask 150 has an opening 152 formed at a position corresponding to the position at which the bus electrode 142 and the black matrix 132 are to be formed.

After the mask 150 is positioned, the mask 150 is exposed for a predetermined time on the mask 150. The active light source used at this time includes visible light, near infrared ray, ultraviolet ray, electron beam, X-ray dimming laser light and the like, and preferably ultraviolet ray is used.

As the ultraviolet light source, a low pressure mercury lamp, a high pressure mercury lamp, an ultra high pressure mercury lamp, a halogen lamp and a germicidal lamp can be used. Preferably, an ultra-high pressure mercury lamp may be used, but is not limited thereto.

For example, when the ultraviolet rays are irradiated, the electrode paste 140 and the black paste 130 are cured in response to the ultraviolet rays. At this time, only a predetermined portion is cured by the mask 150 placed on the electrode paste 140 and the black paste 130. That is, the electrode paste 140 and the black paste 130 disposed below the opening 152 are cured by being irradiated with ultraviolet rays, and the electrode paste 140 and the black located below the portion where the opening 152 is not formed. The paste 130 is not cured because the ultraviolet rays do not penetrate.

After the mask 150 is removed, a developing process is performed. As the developing step, spraying, dipping and the like are used. As a developing solution, aqueous metal alkali solutions, such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and sodium silicate, aqueous amine solutions, such as monoethanolamine, diethanolamine, and triethanolamine, especially the dilute aqueous alkali solution of about 1.5 weight% or less is used. Although preferably used, the carboxyl group of the carboxyl group-containing resin in the composition may be saponified, and the unexposed portion may be removed, and is not limited to the developer as described above. In addition, it is preferable to perform washing with water or acid neutralization in order to remove unnecessary developer after development.

Subsequently, a firing process is performed to complete formation of the bus electrode 142 and the black matrix 132 as shown in (d).

Meanwhile, when the black matrix 132 and the bus electrode 142 are exposed together as described above, as shown in FIG. 2, the lower part of the black matrix 132 is not sufficiently transmitted to the black matrix 132 in the etching step. An under-cut phenomenon may occur that goes downward.

If undercut occurs, the shrinkage during firing increases, which may result in a severe edge curl.

Accordingly, the black paste 130 according to the present invention improves the curing speed of the black paste 130 by including an oligomer having a monofunctional group, minimizes the undercut of the black matrix 132 during firing, and suppresses the formation. The straightness of the electrode can be improved.

EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated concretely, this invention is not limited to the following Example.

The black paste which concerns on this invention is obtained by mix | blending the above-mentioned essential component and arbitrary components in predetermined ratio, and disperse | distributing uniformly in kneading machines, such as three rolls and a blender.

Table 1 below shows Examples and Comparative Examples according to the inclusion amount of the oligomer having a monofunctional group. All units are by weight% unless otherwise stated.

In Table 1 below, the black paste was used as a solvent using butyl carbitol and di (propylene glycol) monomethyl ether, and 2-benzyl-2-dimethylamino-1- (4-mor as a photoinitiator. Polynophenyl) butan-1-one was used. In addition, the photopolymerizable monomer uses Trimethylopropane Triacrylate.

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 bookbinder 30.0 35.0 22.0 35.0 14.0 Oligomer 3.0 7.0 20.0 0.0 26.0 Butyl carbitol 30.0 21.0 21.0 28.0 23.0 Di (propylene glycol) monomethyl ether 5.0 5.0 5.0 5.0 5.0 Photopolymerizable monomer 16.5 16.5 16.5 16.5 16.5 Photoinitiator 1.5 1.5 1.5 1.5 1.5 Polymerization inhibitor 0.5 0.5 0.5 0.5 0.5 Black powder 8.0 8.0 8.0 8.0 8.0 Glass frit 5.0 5.0 5.0 5.0 5.0 Leveling agent 0.5 0.5 0.5 0.5 0.5 Total 100.0 100.0 100.0 100.0 100.0

The black paste having the composition of Table 1 was used to form a pattern of the electrode and the black matrix by the method described above with reference to FIG. 1 to evaluate physical properties of the bus electrode as shown in Table 2 below. The substrate used was PD200 glass, and the exposure mask width line was 90 μm.

Black matrix drying was performed at 100 ° C. for 10 minutes, and bus electrode drying was performed at 105 ° C. for 10 minutes. The development speed was 800 mm / min, and the firing was carried out at 580 ° C. for 10 minutes (at 30 ° C./min in temperature).

Property evaluation Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Exposure amount mJ / 20.0mW 100.00 100.00 100.00 100.00 100.00 T.T.C 6.00 6.40 8.00 4.70 8.30 Resolution (μm) 40.00 30.00 30.00 50.00 30.00 UnderCut after development 18.00 13.00 8.00 24.00 2.00 Plastic shrinkage amount (㎛) 24.30 18.80 14.30 30.30 9.70 E / curl (㎛) 0.34 0.00 0.00 3.20 0.00 Plastic shrinkage residue - - - - Occur Ag pattern straightness ○ ○ ○ × ○

Examples 1 to 3 and Comparative Examples 1 to 2 were exposed at the same exposure dose and etched in the arithmetic solution in 15 minutes.

In Table 2, the comparative example 1 is a case where the oligomer which has a monofunctional group is not included, and the comparative example 2 is the result when the oligomer is included exceeding the preferable range mentioned above.

First, Examples 1 to 3 and Comparative Example 1 show that Examples 1 to 3 have good straightness, but Comparative Example 1 is inferior in straightness.

In addition, when looking at the edge curl of the formed electrode, Examples 1 to 3 has a value of 0 to 0.34 μm, Comparative Example 1 is 3.20, the edge curl of Examples 1-3 is reduced by 89% or more compared to Comparative Example 1 Able to know.

Examples 1 to 3 include a case where the curing rate of the black paste is improved by including an oligomer having a monofunctional group, and as a result, the edge curl is reduced. It can be seen that the plastic shrinkage of Table 2 is reduced by about 20 to 53% compared to Comparative Example 1.

On the other hand, in Comparative Example 2 it can be seen that the resulting plastic shrinkage residue, which is a result containing 26 wt% oligomer having a monofunctional group in excess of 3 to 20 wt% of the above-mentioned preferred range.

Therefore, the black paste according to the present invention may contain 3 to 20 wt% of an oligomer having a monofunctional group, thereby minimizing undercut of the black matrix during firing, thereby suppressing residue and improving the linearity of the formed electrode.

As a result, it is possible to prevent the occurrence of bubbles at the place where the glass substrate electrode and the dielectric film meet and to prevent the occurrence of dielectric breakdown by the voltage applied after the final panel is completed.

3 is a diagram illustrating a structure of a PDP including a black matrix formed of a black paste according to the present invention.

Referring to the drawings, the plasma display panel 300 includes a scan electrode 311 and a sustain electrode 312, which are pairs of sustain electrodes formed on the upper substrate 310, and an address electrode 322 formed on the lower substrate 320. It includes.

The sustain electrode pairs 311 and 312 generally include transparent electrodes 311a and 312a and bus electrodes 311b and 312b formed of indium tin oxide (ITO). 312b) may be formed of a metal such as silver (Ag) or chromium (Cr) or a stack of chromium / copper / chromium (Cr / Cu / Cr) or a stack of chromium / aluminum / chromium (Cr / Al / Cr). .

The bus electrodes 311b and 312b are formed on the transparent electrodes 311a and 312a to reduce the voltage drop caused by the transparent electrodes 311a and 312a having high resistance.

On the other hand, between the transparent electrodes 311a and 312a and the bus electrodes 311b and 311c of the scan electrode 311 and the sustain electrode 312 absorbs external light generated from the outside of the upper substrate 310 to reduce reflection. The black matrix (Black Matrix, BM, 315) is arranged to serve as a light blocking function and to improve the purity and contrast of the upper substrate 310.

The black matrix 315 is formed on the upper substrate 310. The first black matrix 315, the transparent electrodes 311a and 312a and the bus electrodes 311b and 312b are formed at positions overlapping the partition wall 321. Second black matrices 311c and 312c formed therebetween.

Here, the first black matrix 315 and the second black matrices 311c and 312c, which are also called black layers or black electrode layers, may be simultaneously formed and physically connected in the formation process, or may not be simultaneously formed and thus not physically connected. .

In addition, when physically connected and formed, the first black matrix 315 and the second black matrix 311c and 312c may be formed of the same material, but may be formed of another material when the physically separated material is formed.

Meanwhile, the second black matrices 311c and 312c may be formed of a black paste including 3 to 20 wt% of an oligomer having a monofunctional group according to the present invention. Thereby, the undercut of the black matrix at the time of baking can be minimized, a residue can be suppressed, and the linearity of the electrode formed can be improved.

The passivation layer 314 protects the upper dielectric layer 313 from sputtering of charged particles generated during gas discharge, and increases emission efficiency of secondary electrons.

The address electrode 322 is formed in the direction crossing the scan electrode 311 and the sustain electrode 312.

The lower dielectric layer 324 and the partition wall 321 are formed on the lower substrate 320 on which the address electrode 322 is formed.

The lower dielectric layer 324 is electrically condensed to protect the address electrode 322, and is formed in white to prevent discharge light from being transmitted to the rear substrate.

Screen printing is mainly used for forming the lower dielectric layer 324. However, the lower dielectric layer 324 may be formed by various coating methods such as a green sheet laminate method, a slot coater method, and a roll coater method.

In addition, a phosphor layer 323 is formed on the surfaces of the lower dielectric layer 324 and the partition wall 321. The partition wall 321 has a vertical partition wall 321a and a horizontal partition wall 321b formed in a closed shape, and physically distinguishes the discharge cells, and prevents ultraviolet rays and visible light generated by the discharge from leaking to the adjacent discharge cells.

While the preferred embodiments of the present invention have been shown and described, the present invention is not limited to the specific embodiments described above, and the present invention is not limited to the specific embodiments of the present invention, without departing from the spirit of the invention as claimed in the claims. Various modifications can be made by those skilled in the art, and these modifications should not be individually understood from the technical spirit or the prospect of the present invention.

1 is a cross-sectional view illustrating a bus electrode manufacturing process of a plasma display panel.

2 is a cross-sectional view illustrating an under-cut phenomenon of an electrode.

3 is a diagram illustrating a structure of a PDP including a black matrix formed of a black paste according to the present invention.

Claims (10)

3 to 20 wt% of oligomer having monofunctional group, 22 to 35 wt% of binder, 14 to 20 wt% of photopolymerizable monomer, 2 to 10 wt% of glass frit, 5 to 15 wt% of black powder and 26 to 35 wt% of solvent Black paste comprising a. The method of claim 1, The black paste has a diameter of 0.1 to 2㎛ black powder. The method of claim 1, The solvent is a-terpinol, buty cabitol acetate, texanol, buty cabitol and di-propylene glycol monomethyl ether. Black paste containing at least any one of). The method of claim 1, The photopolymerizable monomer is 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, polyurethane diacrylate, trimethylol Propane triacrylate, pentaerythrite triacrylate, pentaerythrite tetraacrylate, trimethylolpropane ethylene oxide modified triacrylate, trimethylolpropanepropylene oxide modified triacrylate, dipentaery little pentaacrylate, di The black paste containing at least any one of pentaerythrite hexaacrylate and each methacrylate corresponding to the said acrylate. The method of claim 1, The black paste of which the average particle size (D50) of the said glass frit is 0.5-2 micrometers. The method of claim 1, The black paste having a glass transition temperature (Tg) of the glass frit is 350 to 550 ° C. The method of claim 1, The black paste further containing at least any one of a photoinitiator, a leveling agent, an antifoamer, and a coupling agent. The method of claim 7, wherein The photoinitiator includes at least one of benzoin alkyl ethers, acetophenones, aminoacetophenones, anthraquinones, thioxanthones, benzophenones, xanthones, phosphine oxides and peroxides. Black paste. A black matrix formed of a fired product of the black paste of any one of claims 1 to 8. A plasma display device comprising the black matrix of claim 9.

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