KR102129172B1 - Conductive ink composition for discharging electrostatic charges - Google Patents

Abstract

The conductive ink composition for removing static electricity includes silver (Ag) particles having a flake shape of 30 to 60% by weight, 10 to 30% by weight of a thermoplastic polyurethane resin, and an extra solvent. Thus, a pattern for removing static electricity can be effectively formed through a dotting process using a conductive ink composition for removing static electricity.

Description

Electroconductive conductive ink composition for removing static electricity {CONDUCTIVE INK COMPOSITION FOR DISCHARGING ELECTROSTATIC CHARGES}

The present invention relates to a conductive ink composition for removing static electricity. More specifically, the present invention relates to a conductive ink composition for removing static electricity used to form a pattern for removing static electricity that can ground static electricity generated from a polarizing film on a color filter through a substrate.

The liquid crystal display device includes a TFT substrate that controls circuit signals, a color filter substrate, and a liquid crystal layer interposed between the TFT substrate and the color filter substrate.

The color filter substrate includes a color filter layer, a polarizing film, and a pressure-sensitive adhesive layer interposed therebetween. The pressure-sensitive adhesive layer has the advantage of having a higher reaction speed to the touch while replacing the existing ITO film.

In addition, a pattern for removing static electricity is formed on the color filter substrate to electrically connect the polarizing film and the glass substrate to remove static electricity generated from the polarizing film.

The static electricity removal pattern may be formed through a printing process using a conductive ink composition. The conductive ink composition should have continuous workability suitable for a continuous process such as a dotting process. In addition, the conductive ink composition requires elongation, a relatively low leveling property, and excellent dispersion stability that can be stretched and contracted effectively according to shrinkage of the polarizing film or shrinkage of the pressure-sensitive adhesive layer.

Particularly, during the process of manufacturing the liquid crystal display panel, foreign matter and static electricity may correspond to a cause that causes a process defect. Electrostatic discharge (ESD) may directly damage the liquid crystal display panel and affect peripheral components. If the ESD damage is not prevented, the production yield of the liquid crystal display panel and the liquid crystal display device including the same is greatly reduced.

In order to solve such a problem, a method of removing static electricity by forming a pattern for removing static electricity using a conductive paste on a liquid crystal display panel and a color filter panel has been developed.

In addition, in order to prevent shrinkage and expansion of the polarizing film, it is inevitable to apply a conductive paste on the liquid crystal display panel and the color filter panel and the polarizing film to form a pattern for removing static electricity. In this process, the pattern for removing static electricity requires a high elongation to cope with shrinkage and expansion of the polarizing film.

One object of the present invention is to provide a conductive ink composition for removing static electricity having excellent elongation, leveling properties and dispersion stability.

One object of the present invention is to provide a conductive ink composition for removing static electricity that can realize excellent continuous workability.

The conductive ink composition for removing static electricity according to an embodiment of the present invention includes silver (Ag) particles having a flake shape of 30 to 60% by weight, 10 to 30% by weight of a thermoplastic polyurethane resin and an extra solvent as a binder. .

In one embodiment of the invention, the silver particles may have a D ₅₀ of 1 to 3 μm.

In one embodiment of the present invention, the silver particles may belong to the first silver particle group and the second silver particle group, respectively, having different average particle diameters so as to have at least twice the difference in relation to D ₅₀ . Here, the first silver particle group may have a D ₅₀ of 1 to 3 μm, and the second silver particle group may have a D ₅₀ of 6 to 8 μm.

In one embodiment of the present invention, the binder may further include a thermosetting polyurethane resin.

Here, the thermoplastic polyurethane resin may range from 30 to 70% by weight compared to the thermosetting polyurethane resin.

In one embodiment of the present invention, the solvent may include at least one of dimethylformamide, sulfur dimethylmonoxide, methylpyrrolidone, tetrahydrofuran, dibasic ester, and dimethylacetamide.

Here, the solvent may be dimethylacetamide.

The conductive ink composition for removing static electricity according to an embodiment of the present invention may have a viscosity in the range of 3,000 to 40,000 cPs.

According to embodiments of the present invention, a conductive ink composition for removing static electricity capable of forming a continuously conductive pattern having excellent elongation and elasticity while being dried at room temperature to 50°C and having excellent conductivity is provided.

Furthermore, a pattern for removing static electricity may be easily formed through a dotting process using the conductive ink composition for removing static electricity.

1A and 1B are analytical graphs according to Fourier transform infrared spectroscopy for polyurethane (PU) and thermoplastic polyurethane (TPU), respectively.
2A and 2B are graphs of molecular weight measurement according to a gel permeation chromatography (GPC) method for polyurethane (PU) and thermoplastic polyurethane (TPU), respectively.
3A and 3B are graphs of transition temperature measurement according to a differential scanning calorimeter (DSC) method for polyurethane (PU) and thermoplastic polyurethane (TPU), respectively.
4 is a graph showing a temperature cycle for performing a thermal shock test on the static electricity removal pattern.

Hereinafter, the present invention will be described in more detail through embodiments of the present invention. However, the present invention should not be configured as limited to the embodiments described below, but may be embodied in various other forms. The following examples are provided to sufficiently convey the scope of the present invention to those skilled in the art of the present invention rather than to provide the present invention to be completely completed.

When one element is described as being disposed on or connected to another element or layer, the element may be placed or connected directly on the other element, and other elements or layers may be placed between them. It might be. Alternatively, if one element is described as being disposed or connected directly on the other element, there can be no other element between them. Terms such as first, second, third, etc. may be used to describe various items such as various elements, compositions, regions, layers and/or parts, but the items are not limited by these terms. Would not.

The terminology used below is for the purpose of describing specific embodiments only, and is not intended to limit the present invention. In addition, unless otherwise limited, all terms including technical and scientific terms have the same meaning that can be understood by those of ordinary skill in the art. These terms, such as those defined in conventional dictionaries, will be construed as having meanings consistent with their meanings in the context of the description of the invention and the related art, and, unless explicitly defined, ideally or excessively intuition It will not be interpreted.

Embodiments of the invention are described with reference to cross-sectional illustrations, which are schematic illustrations of ideal embodiments of the invention. Accordingly, changes from the shapes of the illustrations, for example, changes in manufacturing methods and/or tolerances, are those that can be expected. Therefore, the embodiments of the present invention are not limited to specific shapes of regions described as illustrations, but include variations in shapes, and the regions described in the drawings are entirely schematic and their shapes It is not intended to describe the precise shape of the region, nor is it intended to limit the scope of the invention.

Hereinafter, a preferred embodiment according to the present invention will be described in detail.

The conductive ink composition for removing static electricity of the present invention includes silver (Ag) particles having a flake shape of 30 to 60% by weight, 10 to 30% by weight of a thermoplastic polyurethane (TPU) resin, and an extra solvent. .

The silver particles have a flake shape. That is, the silver particles may have a plate shape. If bead-shaped silver particles are used, it is difficult to secure excellent electrical conductivity by increasing the resistance value due to a decrease in the contact surface between metal powders compared to the plate shape. Furthermore, since the bead-shaped silver particles have a relatively high specific surface area compared to the plate-shaped, when they are made of the same content of silver particles, the viscosity increases too much and the process suitability is reduced in relation to a continuous process such as a dotting process. There may be a problem.

The thermoplastic polyurethane (TPU) resin is included in the conductive ink composition for removing static electricity. Thus, the thermoplastic polyurethane (TPU) resin may have excellent elongation and elasticity.

The thermoplastic polyurethane resin (TPU) corresponds to a polyurethane resin that can be molded by melting with heat. The thermoplastic polyurethane (TPU) resin may be divided into a polyester-based polyurethane resin and a polyether-based polyurethane resin. Furthermore, the thermoplastic polyurethane (TPU) resin may further include a polycaprolactone-based polyurethane resin.

As an example of the polyester-based thermoplastic polyurethane (TPU) resin may have the following structural formula 1.

Structural Formula 1

The properties for each of the thermoplastic polyurethane (TPU) and polyurethane (PU) are Fourier Transform Infrared Spectroscopy (FT-IR), Gel Permeation Chromatography (GPC) method and Differential Scanning Calorimeter (DSC). ) Check each using the method.

1A and 1B are analytical graphs according to Fourier transform infrared spectroscopy for polyurethane (PU) and thermoplastic polyurethane (TPU), respectively.

1A and 1B, it can be seen that polyurethane (PU) and thermoplastic polyurethane (TPU) have different types of atoms, types of bonds, and functional groups.

2A and 2B are molecular weight measurement graphs according to a gel permeation chromatography (GPC) method for polyurethane (PU) and thermoplastic polyurethane (TPU), respectively.

2A and 2B, it can be seen that polyurethane (PU) has a molecular weight of about 157,150, whereas thermoplastic polyurethane (TPU) has a molecular weight of 102,674.

3A and 3B are graphs of transition temperature measurement according to a differential scanning calorimeter (DSC) method for polyurethane (PU) and thermoplastic polyurethane (TPU), respectively.

3A and 3B, it can be seen that the polyurethane (PU) has a transition temperature (Tg) of about 55°C, while the thermoplastic polyurethane (TPU) has a transition temperature (Tg) of about 144°C. ).

The thermoplastic polyurethane (TPU) resin may have a range of 10 to 30% by weight. When the thermoplastic polyurethane (TPU) resin is less than 10% by weight, the bonding force between the silver particles may be weakened. On the other hand, when the thermoplastic polyurethane (TPU) resin is more than 30% by weight, the electrical conductivity of the static electricity removal pattern formed using the conductive ink composition is lowered, and further formed through a dotting process using the conductive ink composition. The printability of the static elimination pattern may deteriorate.

The solvent corresponds to a material capable of dissolving a thermoplastic polyurethane (TPU) resin. The solvent may include Dimethylformamide, Dimethylacetamide, Dimethylsulfonic acid, N-methylpyrrolidone, tetrahydrofurane, acetone, methyl ethyl ketone, cyclohexanone, and the like. The solvent may have a boiling point of 50 to 250 °C.

In one embodiment of the invention, the silver particles may have a D ₅₀ of 1 to 3 μm. As a result, the particle size of the silver particles is adjusted, so that it is formed by using a conductive ink composition containing the silver particles, so that the pattern for removing static electricity has increased electrical conductivity.

Further, the silver particles may be provided to belong to the first silver particle group and the second silver particle group, respectively, having different average particle diameters so as to have at least twice the difference in relation to D ₅₀ . Thus, the silver particles can be adjusted to have an average particle diameter largely belonging to two particle groups.

For example, the first silver particle group may have D ₅₀ of 1 to 3 μm, and the second silver particle group may have D ₅₀ of 6 to 8 μm. The first group of silver particles has a relatively small average particle size, whereas the second group of silver particles has a relatively large average particle size, whereby the silver particles can be uniformly dispersed in the solvent. Thus, when a pattern for removing static electricity is formed using a conductive ink composition containing silver particles, it is possible to secure excellent electrical conductivity of the pattern for removing static electricity.

In one embodiment of the present invention, the binder may further include a polyurethane resin (PU). The polyurethane (PU) resin may include, for example, epoxy, polyester, phenol, and the like.

The polyurethane resin (PU) has a three-dimensional structure similar to the thermosetting resin. The polyurethane resin (PU) is a pattern for removing static electricity formed by using the conductive ink composition may ensure better adhesion to a glass substrate.

Synthesis of the polyurethane (PU) is formed according to the reaction scheme below.

That is, the thermoplastic polyurethane (TPU) resin may have excellent elasticity and electrical conductivity, while the adhesion to the glass substrate may be relatively low.

Therefore, the binder can secure excellent elasticity and improved adhesion by including a thermoplastic polyurethane (TPU) resin and a polyurethane resin (PU).

Here, the thermoplastic polyurethane resin may have a range of 5 to 95% by weight compared to the polyurethane resin. When the thermoplastic polyurethane resin is less than 5% by weight compared to the polyurethane resin, it is difficult to use it as a pattern for removing static electricity that requires flexibility because of low elasticity. On the other hand, when the thermoplastic polyurethane resin is more than 95% by weight compared to the polyurethane resin, there may be a problem that the adhesion to the glass substrate is lowered.

In one embodiment of the present invention, the solvent may include at least one of dimethyl formamide, dimethyl sulfur monoxide, methyl pyrrolidone, tetrahydrofuran, dibasic ester, or dimethyl acetamide.

In particular, the solvent may include dimethylacetamide. Dimethylformamide and sulfuric acid dioxide may generate excessive odor, and thus may not be suitable for the manufacturing environment. On the other hand, in the case of the methylpyrrolidone, compatibility with a container of process equipment such as a syringe made of plastic may not be good. Furthermore, in the case of tetrahydrofuran, storage stability may be deteriorated. Therefore, when the solvent includes dimethylacetamide, excellent process workability can be secured.

On the other hand, the content of the solvent can be appropriately adjusted mainly to control the rheology of the ink.

The conductive ink composition for removing static electricity according to an embodiment of the present invention may have a viscosity in the range of 3,000 to 40,000 cPs.

When the viscosity is less than 3,000 cPs, it may be difficult to form a pattern made of the conductive ink composition for removing static electricity to have a predetermined thickness. On the other hand, when the viscosity exceeds 40,000 cPs, quantitative discharge is difficult in the dotting process, and the thickness of the pattern to be formed may be excessively large.

Additives may be additionally included in the ink composition to secure desired properties. Various commonly used additives include surfactants, surfactants, wetting agents, antioxidants, thixotropic agents, reinforcing fibers, silane functional perfluoroethers, phosphate functional perfluoroethers, titanates, waxes, phenol formaldehyde, Air release agents, flow additives, adhesion promoters, rheology modifiers, and spacer beads. Additional components are optional and are specifically selected to obtain any properties desirable for the selected end use. When used, the additive may constitute up to about 10 weight percent of the total dry composition.

Application of conductive ink composition

The conductive ink composition is used in a printing process on various substrates, and is formed in a pattern on the substrate.

The substrate may include a film of paper, glass, PET, PI, PEN, or a metal foil such as Al, Cu, Ni. The printing process may include, for example, a gravure, flexo, screen, rotary, dispenser, jetting or offset process.

In particular, the substrate is a liquid crystal display device in which a TFT panel, a C/F panel, an adhesive, and a fluorescent film are sequentially stacked. In the present invention, the conductive ink composition is applied through a dispenser or jetting.

The conductive ink composition may be patterned into points, lines (straight lines, curved lines), and faces (rectangles, squares, circles) through dispensers or jetting.

The conductive ink composition is first dispersed in a planetary mixer and then 3-roll-mill, and can pass through a 3-roll mill 1 to 10 times. It can also be defoamed with a paste mixer before use.

The drying of the conductive ink composition may be dried at room temperature to 50°C for 1 to 720 minutes, or 20°C to 120°C in a drying oven within 1 to 120 minutes.

The pattern for removing static electricity formed by using the conductive ink composition having high elongation according to the present invention can manufacture an IPS-LCD panel that stably removes static electricity without a problem due to cracks or disconnections even on a polarizing film having a large shrinkage expansion. The yield can be increased.

Mixed example

Add 50 parts by weight of DMAC (Dimethylacetamide, manufactured by Daejung Chemical Co., Ltd.) and 50 parts by weight of TPU Resin (1170 A10, manufactured by BASF) to a planetary mixer, raise the temperature to 60 °C, and maintain the temperature for 4 hours while stirring and binder (1-1).

Example 1

In a paste container, 30.00 parts by weight of a binder (example of mixing), DMAC (Dimethylacetamide, manufactured by Daejung Chemical Co., Ltd.) and Dibasic ester of organic solvent are added at a ratio of 7.5:2.5 to 13.50 parts by weight and 4.50 parts by weight, respectively. Plate-shaped silver powder (Ag, manufactured by Heesung Metal, model name; HP-0202END) 1.5 μm (based on D50) was added alone. For excellent dispersibility, after adding 2.00 parts by weight of the dispersant, stirring was performed with a Paste Mixer at idle/rotated 600/600 rpm, and then 3-Pass dispersion was performed using a 3-Roll-Mill equipment to obtain a final mixture. Table 1 summarizes the specific composition and test results.

Example 2

An ink composition prepared using plate-shaped silver powder (Ag, manufactured by Heesung Metal Co., Ltd., model name; HP-0202END) 3.0 μm (based on D50) alone was prepared.

Example 3

In a paste container, 30.00 parts by weight of a binder (mixed example 1-1), organic solvent DMAC (Dimethylacetamide, manufactured by Daejung Chemical Co., Ltd.), and organic solvent Dibasic ester are added at a ratio of 7.5:2.5 to 13.50 parts by weight and 4.50 parts by weight, respectively. Plate-shaped silver powder (Ag, manufactured by Heesung Metal Co., Ltd., model name; HP-0202END) 1.5 µm (based on D50) and plate-shaped silver powder (Ag) 6.0 µm (based on D50) at a ratio of 7.0: 3.0 35.00 parts by weight and 15.00 parts by weight, respectively Input. For excellent dispersibility, after adding 2.00 parts by weight of the dispersant, stirring was performed with a Paste Mixer at idle/rotated 600/600 rpm, and then 3-Pass dispersion was performed using a 3-Roll-Mill equipment to obtain a final mixture.

Example 4

The binder used in Example 1 was replaced with a mixed binder in which the TPU and PU (manufactured by Toyobo, model name; UR-6100) were mixed at a weight ratio of 1:1, and the rest of the composition ratio and manufacturing method were the same to prepare an ink.

Example 5

Eco-friendly dimethylacetamide was used alone.

Comparative Example 1

An ink composition was prepared using 0.5 µm (based on D50) sized silver powder (manufactured by Heesung Metal, model name; HP-0202END).

Comparative Example 2

An ink composition was prepared using 6.0 μm (based on D50) sized silver powder (manufactured by Heesung Metal, model name; HP-0202END).

Comparative Example 3

In Example 1, a plate-shaped silver powder powder (manufactured by Heesung Metal Co., Ltd., model name; HP-0202END) was prepared using 25% by weight of an ink composition.

Comparative Example 4

In Example 1, the plate-shaped silver powder (manufactured by Heesung Metal Co., Ltd., model name; HP-0202END) was used to prepare an ink composition prepared by using 65% by weight.

Comparative Example 5

The binder TPU used in Example 1 was replaced by PU (manufactured by Toyobo, model name; UR-6100), and the rest of the composition ratio and manufacturing method were the same to prepare ink.

Comparative Example 6

In the binder used in Example 1, TPU was replaced with polyester (manufactured by Toyobo, model name; Vron 630), and the remaining composition ratio and manufacturing method were the same to prepare an ink.

The conductive paste prepared above was applied linearly (20.0 mm X 1.5 mm) to a substrate on which a polarizing film was attached on a glass substrate with a dispenser. The coated specimen was dried at room temperature (temperature 22 to 27°C) for 360 minutes to obtain a conductive pattern.

The following evaluation was performed on the conductive patterns using the conductive ink compositions obtained in Examples 1 to 5 and Comparative Examples 1 to 6, and the results are shown in Table 1.

(1) Evaluation of viscosity

The conductive ink composition is composed of BrookField D-II pro HB type viscometer and Spindle No. Using 14, the sample adapter was maintained at 22°C, and 2 rpm and 20 rpm were left for 1 minute, respectively, and the viscosity was measured for each rpm for 1 minute.

(2) Resistance evaluation

For 20.0 mm X 1.5 mm conductive pattern, the line resistance of End to End was measured for 2-Probe.

(3) Check dryness

After applying a diameter of 2.0㎜ to the glass using a dispenser equipment and needle inner diameter (0.30 ~ 0.50㎜), it was checked whether the conductive ink composition comes out when pressed with a white cloth after drying for 60 minutes at room temperature (temperature 22 ~ 27°C). .

(4) Thermal Shock Test

After checking the dryness, the conductive pattern specimen is put into a thermal shock tester. The test conditions were -40°C ↔ 80°C, 100 Cycle (1Cycle=60min), and after the test was finished, the specimen was taken out to check for cracks or short circuits in the conductive ink composition. Since the glass substrate (Glass) has no deformation, ultimately, there should be no cracks or short circuits in the pattern at the step between the polarizing film and the substrate. The line resistance of End to End was again measured for the 2-Probe for the conductive pattern. The details of the temperature cycle are illustrated in FIG. 4.

(5) Continuous workability test

Using a dispenser equipment and needle inner diameter (0.30 to 0.50 mm), apply a circular shape of 2.0 mm in diameter to the A4 paper size (297.0 × 210.0 ㎜) at a distance of 1.0 to 3.0 mm and apply for 0.1 to 2.0 seconds. Wait for 0.1 to 2.0 seconds after application.

Through the repetitive work, a total of 10,000 circles are formed. When the work was completed, it was confirmed through the microscope that 1 to 10,000 circular diameters had an error range within 10%.

Table 1 shows the results for Examples 1 to 5 and Comparative Examples 1 to 6 with respect to the test items.

division Single/D ₅₀
(μm) Silver content
(weight%) bookbinder Viscosity
(cPa) resistance
(Ω) Dryness
(Within 60 minutes) Thermal shock continuity
Workability Example 1 Single/1.5 50 TPU 4,000 1.0 OK OK possible Example 2 Single/3.0 50 TPU 5,000 1.0 OK OK possible Example 3 Mixed/1.5+6.1 50 TPU 7,000 0.9 OK OK possible Example 4 Single/1.5 50 TPU+PU 5,500 1.0 OK OK possible Example 5 Single/1.5 50 TPU alone 5,000 1.0 OK OK possible Comparative Example 1 Single/0.5 50 TPU 3,000 2.5 OK OK impossible Comparative Example 2 Single/6.0 50 TPU 9,000 1.0 OK OK impossible Comparative Example 3 Single/1.5 25 TPU 500 - OK Fail impossible Comparative Example 4 Single/1.5 65 TPU 15,000 1.0 OK Fail possible Comparative Example 5 Single/1.5 50 PU 5,500 1.0 OK Fail possible Comparative Example 6 Single/1.5 50 polyester 2,000 1.0 OK Fail impossible

In the case of Example 3, the single plate-shaped silver of Example 1 has a reduced contact resistance than that of the powder, so that the electrical resistance is observed to facilitate the static electricity removal function.

On the other hand, in the case of the TPU and PU mixture according to Example 4, the elasticity is somewhat reduced compared to the TPU. However, the excellent adhesion of the substrate of the PU and the elasticity of the TPU show synergy, which shows excellent properties for universal use.

When a pattern is formed by using the ink composition according to Comparative Example 1, electrical resistance increases, and process suitability decreases as viscosity decreases.

When the pattern is formed using the ink composition according to Comparative Example 2, the layer separation phenomenon is accelerated, and as the viscosity significantly increases or decreases, the nozzle clogging during the dotting process is provided.

When the pattern is formed by using the ink composition according to Comparative Example 3, the electrical resistance is high, which is not sufficient for the purpose of removing static electricity, and the dispersion stability is low, so that the layer separation is accelerated and the process suitability is lowered. In order to prevent layer separation, the rheology may be controlled by adding an organic-inorganic additive, but in this case, a relatively high non-conductive material increases the electrical resistance, thereby reducing the static electricity removal function.

When the pattern is formed using the ink composition according to Comparative Example 4, the viscosity increases and the jetting property decreases, and the weight% of the silver powder compared to the binder is too high, so that the pattern breaks when the polarizing film shrinks by 30 μm or more This happens.

When the binder of the PU according to Comparative Example 5 is used, the elasticity is insufficient, compared to the TPU, to form a pattern on the polarizing film, the polarizing film, the glass substrate, and the glass substrate, and when shrinking the polarizing film , When the polarizing film shrinks more than 30㎛ it shows a characteristic that the pattern is cut off. In addition, due to the low viscosity, a phenomenon in which layer separation is accelerated is confirmed.

When the polyester binder according to Comparative Example 6 is used, the elasticity is insufficient, compared to the TPU, to form a pattern on the polarizing film, the polarizing film, the glass substrate, and the glass substrate, and shrinking the polarizing film. , It is separated from the glass substrate due to the low adhesion to the glass substrate, causing problems in performing the static electricity removal function.

Claims (9)

Silver (Ag) particles having a flake shape of 30 to 60% by weight;
10 to 30% by weight of a thermoplastic polyurethane resin as a binder; And
Contains extra solvent,
The silver particles belong to the first silver particle group and the second silver particle group, respectively, having different average particle diameters so as to have at least twice the difference in relation to D ₅₀ ,
Said first particle group having a 1 to 3 μm of ₅₀ D, the second group has a particle is from 6 to 8 μm for D _50,
The binder further includes a thermosetting polyurethane resin,
The thermoplastic polyurethane resin is in the range of 5 to 95% by weight compared to the thermosetting polyurethane resin,
The solvent is dimethylacetamide, characterized in that the conductive ink composition for removing static electricity. delete delete delete delete delete delete delete The conductive ink composition for removing static electricity according to claim 1, having a viscosity in the range of 3,000 to 40,000 cPs.

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