KR20220074369A - A Conductive Ink Composition and a Conductive Substrate using the same - Google Patents

Abstract

The present invention relates to a conductive ink composition capable of sintering at a low temperature and a conductive substrate using the same, and to provide good electrical conductivity while sintering at a low temperature of 80° C. or less. The conductive substrate according to the present invention includes a base substrate and a conductive film formed by printing the conductive ink composition on the base substrate and then sintering it at 80° C. or less. The conductive ink composition includes 50 to 85% by weight of a conductive powder, 5 to 20% by weight of an organic binder, and 10 to 30% by weight of a solvent.

Description

A conductive ink composition and a conductive substrate using the same

The present disclosure relates to a conductive ink composition and a conductive substrate using the same, and more particularly, to a conductive ink composition capable of sintering at a low temperature and having excellent electrical conductivity, and a conductive substrate on which the conductive ink composition is printed.

Currently used in printed electronic technology, conductive ink is mainly used for wiring patterns of conductive substrates such as display panels, solar panels, digitizers, and printed circuit boards.

As the conductive ink, silver ink and silver paste containing silver (Ag) are mainly used. The conductive ink containing silver may include metal particles such as gold, platinum, and palladium in addition to silver.

This conductive ink is applied to the base substrate to form a coating layer, and then is formed as a conductive film on the base substrate through a sintering (heat treatment) process of 120° C. or higher. It is formed as a wiring pattern through a photolithography process on the conductive film.

As described above, since the conventional conductive ink requires a sintering process of 120° C. or higher, it cannot be used for a base substrate having a low heat resistance temperature. In addition, there is a disadvantage that it cannot be used for a base substrate that has poor functionality or loses functionality during heat treatment at a temperature of 80°C or higher.

A conductive film produced by performing a sintering process on such a conventional conductive ink at 120° C. or lower has a problem in electrical conductivity that is lower than that of a conductive film prepared by performing a sintering process at 120° C. or higher. The conductive film sintered at 120° C. or lower has poor adhesion to the base substrate, so that when a force is applied in the direction of the surface of the base substrate, the conductive film component leaks out.

Moreover, as the sintering temperature of the conductive ink decreases, the electrical conductivity of the conductive film manufactured by the sintering process decreases further, and a problem occurs that more conductive components are smeared.

KR 10-1715756 B2

Accordingly, a first aspect of the present disclosure is to provide a conductive ink composition capable of sintering at a low temperature and having excellent electrical conductivity. In addition, a second aspect of the present disclosure is to provide a conductive substrate using the conductive ink composition.

A conductive ink composition capable of firing at a low temperature for achieving the first aspect of the present disclosure includes 50 to 85% by weight of a conductive powder; 5 to 20% by weight of an organic binder; and 10 to 30% by weight of a solvent, wherein the low temperature is 80° C. or less, and the conductive powder includes a first conductive powder and a second conductive powder, wherein the particle diameter of the first conductive powder is the second larger than the particle diameter of the conductive powder.

According to an embodiment of the present disclosure, the conductive powder includes silver, nickel, copper, aluminum, gold, an alloy of two or more thereof, or a combination thereof.

According to one embodiment of the present disclosure, the metal included in the first conductive powder and the metal included in the second conductive powder are different.

According to one embodiment of the present disclosure, the particle diameter of the first conductive powder is 1 μm or more and 10 μm or less, and the particle diameter of the second conductive powder is more than 500 nm and less than 1 μm.

According to one embodiment of the present disclosure, the composition includes 1 to 10 parts by weight of the second conductive powder based on 100 parts by weight of the first conductive powder.

According to one embodiment of the present disclosure, the organic binder includes acrylic polyol, polyurethane, phenoxy, epoxy, or a combination thereof, and the solvent includes ethyl carbitol acetate and butyl cellosolve acetate, propylene glycol methyl ether, butyl carbitol, diethyl diglycol, butyl cellosolve, isopron, or a combination thereof.

According to one embodiment of the present disclosure, the viscosity of the composition is 10,000 to 1,000,000 cPs.

A conductive substrate for achieving the second aspect of the present disclosure includes: a base substrate; and a conductive film formed on the base substrate, wherein the conductive film is sintered at 80° C. or less after printing the conductive ink composition capable of sintering at a low temperature according to any one of the above-described embodiments of the present disclosure on the base substrate. formed, wherein the Young's modulus of the base substrate is 0.1 MPa to 4 GPa.

According to one embodiment of the present disclosure, the resistivity of the conductive film is 1.0x10 ^-4 (Ω·cm) or less.

According to one embodiment of the present disclosure, the base substrate has an elongation at break of 300% or less.

The conductive ink composition of the present disclosure can be sintered at a low temperature of 80° C. or less, and has excellent adhesion and electrical conductivity. In general, in the case of a conductive ink composition, the higher the sintering temperature, the higher the conductivity. However, the conductive ink composition according to the present disclosure is sintered at a low temperature of 80° C. or less, while being sintered at a sintering temperature of 120° C. or higher. It exhibits higher electrical conductivity. For this reason, the conductive ink composition according to the present disclosure has the same functionality as a flexible substrate or a stretchable substrate, but is preferably applied to a substrate that loses such functionality when performing a sintering process at a high temperature.

1 is a cross-sectional view of a conductive substrate using a conductive ink composition capable of being sintered at a low temperature according to an embodiment of the present disclosure.

Objects, specific advantages and novel features of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings and preferred embodiments, but the present disclosure is not necessarily limited thereto. In addition, in describing the present disclosure, if it is determined that a detailed description of a related known technology may unnecessarily obscure the subject matter of the present disclosure, the detailed description thereof will be omitted. Hereinafter, with reference to the accompanying drawings to the present disclosure will be described in detail.

1 is a cross-sectional view of a conductive substrate using a conductive ink composition capable of being sintered at a low temperature according to an embodiment of the present disclosure.

Referring to FIG. 1 , a conductive substrate 100 according to the present disclosure includes a base substrate 10 and a conductive film 20 formed on the base substrate 10 . Here, the conductive film may be formed by printing the conductive ink composition capable of being sintered at a low temperature of the present disclosure, which will be described later, on the base substrate and then sintering it at a temperature of about 80° C. or less.

Here, as the base substrate 10 , a plastic substrate, a fiber substrate, a metal substrate, or a ceramic substrate may be used. Materials of the plastic substrate include polyimide, polyethersulphone (PES), polyacrylate (PAR), polyetherimide (PEI), polyethylene naphthalate (polyethyelenen napthalate; PEN), polyethylene Polyethyeleneterepthalate (PET), polyphenylene sulfide (PPS), polyallylate, polycarbonate (PC), cellulose triacetate (CTA) or cellulose acetate propinonate; CAP) may be used, but not limited to those listed. Furthermore, as the material of the base substrate 10, a film-type material having a low heat resistance temperature or a material that loses functionality at 80°C or higher can be used.

In view of the above functionality, the base substrate according to an embodiment of the present disclosure may be a flexible substrate or a stretchable substrate. More preferably, the base substrate may be a substrate made of a material that is highly likely to lose the functionality of the flexible and/or stretchable when sintering at a temperature exceeding 80°C.

From the viewpoint of the flexible or stretchable functionality, the base substrate is PTFE (Polytetrafluoroethylene), PDMS (Polydimethylsiloxane), PET (Polyehtylene-terephthalate), PES (Polyether sulfone), PEN (Polyethylene naphthalate), PI (Polyimide), PolymethymethAcrylate (PMMA), Polycarbonate (PC), or a combination thereof.

In addition, from the viewpoint of the flexible or stretchable functionality, the base substrate may be composed of at least three plural layers. In one embodiment of the present disclosure, the base substrate is composed of a first layer to a third layer, wherein the second layer is interposed between the first layer and the third layer, and the first layer and the third layer are PI and the second layer may include PDMS.

The thickness of the base substrate of the present disclosure may be about 50 to 5000 μm. In terms of the flexible substrate and/or the stretchable substrate, the thickness of the substrate may be about 50 to 1000 μm, preferably about 50 to 800 μm. When the thickness of the substrate exceeds about 1000 μm, there is a problem in that the possibility that the substrate is broken when a deformation is applied to the substrate increases.

When the base substrate is a flexible substrate, a Young's modulus of the base substrate may be in the range of about 0.1 MPa to 4 GPa, more preferably, about 0.1 MPa to 1 GPa. When the base substrate is a stretchable substrate, the Young's modulus of the base substrate may be in the range of about 0.1 MPa to 100 MPa, preferably about 0.1 MPa to 50 MPa, and most preferably about 0.1 MPa to 10 MPa. When the Young's modulus exceeds the upper limit, there is a problem in that there is a high possibility that the functionality of each substrate is not properly maintained.

In addition, when the base substrate is a stretchable substrate, the elongation at break of the base substrate is 100% or more, preferably more than 100%, more preferably 110% or more, more preferably 130% or more, most preferably may be 150% or more. In addition, the elongation at break may be 300% or less, preferably 250% or less. The elongation at break means (L2-L1)/L1*100 (%) when the initial length of the substrate is L1 and the length at which fracture occurs due to the elongation of the substrate is L2. That is, it means the strain between the length at which the fracture occurs due to the elongation of the substrate and the initial length of the substrate. As the elongation at break of the stretchable substrate satisfies the above range, there is an advantage that the user can more easily handle the conductive substrate of the present disclosure.

Meanwhile, referring back to FIG. 1 , the conductive film 20 of the present disclosure is formed on the base substrate 10 . The conductive film may be formed through a sintering process at a temperature of 80° C. or less after printing the conductive ink composition of the present disclosure on the base substrate. It is possible to pattern a desired wiring pattern on the base substrate before and after printing of the conductive ink composition, and the patterning method is not particularly limited as long as it does not interfere with the purpose of the present disclosure, and a known method can be applied. .

The conductive ink composition comprises 50 to 85 wt% of conductive powder; 5 to 20% by weight of an organic binder; and 10 to 30% by weight of a solvent.

Here, when the content of the conductive powder is less than 50% by weight, a problem of insufficient electrical conductivity of the conductive film and the conductive substrate formed using the composition may occur. Conversely, when the content of the conductive powder exceeds 85% by weight, a problem of poor dispersibility in the organic binder and solvent may occur, and consequently problems such as insufficient adhesion and non-uniform patterning may occur when forming a conductive film. have.

The conductive powder may include silver, nickel, copper, aluminum, gold, an alloy of two or more thereof, or a combination thereof. According to one embodiment of the present disclosure, the conductive powder may include a first conductive powder and a second conductive powder. Here, the particle diameter of the first conductive powder is larger than the particle diameter of the second conductive powder.

In the present disclosure, the 'particle diameter' of the powder means the average particle diameter of each of the particles of the powder. The shape of the particles of the conductive powder approximates the shape of a sphere.

In one embodiment of the present disclosure, the aspect ratio of the particles of the conductive powder may be within the range of about 1 to 5, preferably within the range of about 1 to 3, and most preferably within the range of 1 to 1.5. Here, the aspect ratio means the ratio of the minimum diameter to the maximum diameter of the particle. Since the aspect ratio of the particles in the conductive powder is 5 or less, it is possible to uniformly disperse the conductive powder in the composition, and advantageous effects such as excellent electrical conductivity, adhesion to the substrate, and uniform film thickness when forming a conductive film It is possible to provide In particular, from the viewpoint of printing performance, it is possible to use the conductive powder of the present disclosure that satisfies the above aspect ratio to improve the clarity of the printed pattern. If a material having a significantly larger aspect ratio, such as a nanowire or a nanowire, is used as the conductive powder outside the aspect ratio, a problem in that the printing line is not clean may occur during printing.

In one embodiment according to the present disclosure, the metal included in the first conductive powder and the metal included in the second conductive powder may be the same. In another embodiment according to the present disclosure, the metal included in the first conductive powder and the metal included in the second conductive powder may be different.

Without wishing to be bound by a particular theory, a second conductive powder having a relatively small particle size is dispersed between the first conductive powders to fill the gap between the first conductive powders, and serves as a bridge connecting the particles in the conductive powder, By strengthening the network between the powders, it is considered that the conductive ink composition makes it possible to have excellent sintering ability and excellent electrical conductivity even through a sintering process at a low temperature.

In one embodiment according to the present disclosure, the particle diameter of the first conductive powder may be 1 μm or more and 10 μm or less, and the particle diameter of the second conductive powder may be greater than 500 nm and less than 1 μm. Preferably, the particle diameter of the first conductive powder may be 1 μm or more and 6 μm or less, and the particle diameter of the second conductive powder may be greater than 600 nm and less than 800 nm.

When the particle diameter of the first conductive powder exceeds 10 μm, a problem in that a sufficient temperature required for sintering exceeds 80°C may occur. On the other hand, when the particle diameter of the first conductive powder is less than 1 μm, there may be a problem in that sufficient electrical conductivity cannot be obtained when the conductive film is formed with the composition. In addition, when the particle diameter of the second conductive powder is 1 µm or more, a problem in that a sufficient temperature required for sintering exceeds 80°C may occur. On the other hand, when the particle diameter of the second conductive powder is 500 nm or less, there may be a problem in that sufficient electrical conductivity cannot be obtained when the conductive film is formed with the composition.

In one embodiment according to the present disclosure, the composition may include about 1 to 10 parts by weight of the second conductive powder based on 100 parts by weight of the first conductive powder. More preferably, the composition may include 1 to 5 parts by weight of the second conductive powder based on 100 parts by weight of the first conductive powder. When the content of the second conductive powder is less than 1 part by weight based on 100 parts by weight of the first conductive powder, there is a problem in that it is difficult to expect a sufficient effect of reducing the sintering temperature because the content of the second conductive powder is small. On the other hand, when the content of the second conductive powder exceeds 10 parts by weight with respect to 100 parts by weight of the first conductive powder, a problem in that the electrical conductivity decreases because the resistance is too high when the conductive film is formed.

The organic binder and solvent included in the composition of the present disclosure are not particularly limited, unless they are materials that can be dried and sintered at a temperature of 80° C. or less, and negatively affect the function and/or performance of the conductive substrate of the present disclosure. In the present disclosure, the organic binder may include acrylic polyol, polyurethane, phenoxy, epoxy, or a combination thereof. In addition, the solvent may include ethyl carbitol acetate, butyl cellosolve acetate, propylene glycol methyl ether, butyl carbitol, diethyl diglycol, butyl cellosolve, isoprone, or a combination thereof.

In one embodiment of the present disclosure, the composition may include 5 to 20% by weight of the organic binder. When the content of the organic binder is less than 5% by weight, adhesion to the base substrate 10 may be reduced. Conversely, when the content of the organic binder exceeds 20% by weight, there may be a problem in that sufficient electrical conductivity cannot be obtained.

Also, in one embodiment of the present disclosure, the composition may include 10 to 30% by weight of the solvent. When the content of the solvent is less than 10% by weight, the viscosity of the ink composition becomes too high and it may be difficult to print the ink composition smoothly, and when the content of the solvent exceeds 30% by weight, the viscosity of the ink composition becomes too low to obtain a desired pattern. Printing can be difficult and the sintering time can be long.

As described above, the conductive ink composition of the present disclosure has a feature that sintering is possible at a low temperature. In the present disclosure, the term 'low temperature' means a temperature of about 80 °C or less. The conductive ink composition of the present disclosure can be sintered at a temperature of about 80° C. or less, preferably about 70° C. or less. In addition, the conductive ink composition of the present disclosure can be sintered at a temperature of at least 60° C. to form a conductive film having excellent adhesion to the base substrate and excellent electrical conductivity. In addition, the conductive ink composition of the present disclosure may be sintered for a time of about 5 minutes to 30 minutes, preferably about 10 minutes to 15 minutes.

In one embodiment of the present disclosure, the viscosity of the composition may be about 10,000 to 1,000,000 cPs. When the viscosity of the composition exceeds the above range, there is a problem that adversely affects the printability of the composition. The viscosity of the composition may be appropriately selected within the above range depending on the method of printing the composition.

In the present disclosure, the printing method is not particularly limited, but illustratively the following printing methods may be applied: Roll Printing, Gravure Offset Printing, Gravure Printing, Reverse Offset Printing, Inkjet Printing, Screen Printing, Pad Printing and Imprinting and dip coating, spray coating, spin ( spin) coating, solution casting, dropping, roll coating, gravure coating or bar coating, etc.

The conductive ink composition according to the present disclosure may form a conductive film on the base substrate through a sintering process. Accordingly, the conductive substrate prepared from the conductive ink composition of the present disclosure is about 1.0x10 ^-4 It is possible to achieve excellent resistivity of (Ω·cm) or less. In one embodiment of the present disclosure, when the conductive ink composition is sintered at about 60° C., the conductive substrate can achieve a specific resistance of about 9.7×10 ⁻⁵ Ω·cm. In another embodiment of the present disclosure, when the conductive ink composition is sintered at about 80°C, the conductive substrate achieves a resistivity of up to about 6.0x10 ^-5 Ω·cm, preferably about 6.5x10 ^-5 Ω·cm It is possible. This is thought to be because the density between the conductive powders increases as the sintering at a high temperature increases. In terms of sheet resistance, the sheet resistance of the conductive substrate according to an exemplary embodiment of the present disclosure may be about 0.02 Ω/□ or less.

In one embodiment of the present disclosure, the thickness of the conductive film may be about 5 to 30 μm, and the adhesion to the base substrate may be 0 to 1 class.

Hereinafter, preferred examples are presented to help the understanding of the present disclosure, but the following examples are provided for easier understanding of the present disclosure, and the present disclosure is not limited thereto.

Example

[Example 1]

In order to confirm the characteristics of the conductive ink composition capable of being sintered at a low temperature according to the present invention as described above, a conductive ink composition according to Example 1 having a composition as shown in Table 1 below was prepared.

division ingredient Content (wt%) first conductive powder silver 72 second conductive powder nickel One organic binder phenoxy 7 menstruum Butyl Cellosolve Acetate 10 menstruum diethyl diglycol 10

Here, the average particle diameter of the first conductive powder was about 5 μm, and the average particle diameter of the second conductive powder was about 700 nm.

A solvent in which butyl cellosolve acetate and diethyl diglycol were mixed was prepared, added to a phenoxy organic binder, and then mixed. After silver powder and nickel powder were added to a solvent and an organic binder mixture, a conductive ink composition was prepared by mixing them, and a 3-roll-mill was performed to prepare a conductive ink composition according to an embodiment.

Thereafter, the conductive ink composition according to Example 1 was printed on a PET substrate and sintered at 60° C. to form a conductive film. The resistivity was measured for the conductive film formed on the PET substrate.

As a result of the measurement, the specific resistance of the conductive film was about 9.7×10 ^-5 (Ω·cm). As described above, it can be confirmed that the conductive film prepared from the conductive ink composition in Example 1 was sintered at a low temperature of 80° C. or less, but exhibited electrical conductivity corresponding to that of the conventional conductive film sintered at 120° C. or higher.

For the conductive film formed on the PET substrate according to Example 1, adhesion was measured by a cross-cut test. As a result of the measurement, the adhesion of the conductive film was 1 class. As described above, although the conductive film prepared with the conductive ink composition of Example 1 was sintered at a low temperature of 80°C or lower, it was confirmed that it showed adhesion corresponding to the conventional conductive film sintered at 120°C or higher, and through this, the sintering was well performed. Able to know.

[Comparative Example 1]

In order to confirm the characteristics of the conductive ink composition according to the presence or absence of the second conductive powder, a conductive ink composition according to Comparative Example 1 having a composition as shown in Table 2 below was prepared.

division ingredient Content (wt%) first conductive powder silver 73 second conductive powder - - organic binder phenoxy 7 menstruum Butyl Cellosolve Acetate 10 menstruum diethyl diglycol 10

A solvent in which butyl cellosolve acetate and diethyl diglycol were mixed was prepared, added to a phenoxy organic binder, and then mixed. A conductive ink composition according to Comparative Example 1 was prepared by adding silver powder to a mixture of a solvent and an organic binder, mixing them, and performing a three-roll mill.

Thereafter, the conductive ink composition according to Comparative Example 1 was printed on a PET substrate and then sintered at 60° C. to form a conductive film. Specific resistance was measured for the conductive film formed on the PET substrate.

As a result of the measurement, the resistivity of the conductive film was about 1.3×10 ⁻⁴ (Ω·cm). As such, in the case of Comparative Example 1 in which the second conductive powder was not added, it can be seen that the specific resistance was significantly higher than in Example 1 in which the second conductive powder was added.

The adhesiveness of the conductive film formed on the PET substrate according to Comparative Example 1 was measured by a cross-cut test. As a result of the measurement, the adhesiveness of the conductive film was 2 Class. From the viewpoint of adhesiveness, it can be confirmed that the case of Comparative Example 1 is inferior to the case of Example 1.

[Examples 2 to 4 and Comparative Examples 2 to 4]

As shown in Table 3 below, by changing the experimental conditions, additional experiments were performed. Experimental conditions not shown in Table 3 were the same as those of Example 1, and the experiment was carried out. The resistivity and adhesion to the base substrate of each Example and Comparative Example are shown in Table 4 below.

division Example 2 Example 3 Example 4 Comparative Example 2 Comparative Example 3 Comparative Example 4 First conductive powder content silver, 72 wt% silver, 72 wt% silver, 75 wt% silver, 72 wt% silver, 72 wt% silver, 70 wt% First conductive powder particle size (μm) 10 5 5 15 5 5 Second conductive powder content Nickel, 1 wt% nickel,
1 wt% aluminum,
5 wt% nickel,
1 wt% nickel,
1 wt% aluminum,
10 wt% Second conductive powder particle size (nm) 600 700 700 1,200 700 400 Phenoxy (wt%) 7 7 6 7 7 6 Butyl Cellosolve Acetate (wt%) 10 10 7 10 10 7 diethyl diglycol (wt%) 10 10 7 10 10 7 Sintering temperature (℃) 60 80 70 60 50 70

division Example 2 Example 3 Example 4 Comparative Example 2 Comparative Example 3 Comparative Example 4 resistivity
(Ω cm) 9.0x10 ^-5 6.5x10 ^-5 7.24x10 ^-5 1.22x10 ^-4 1.47x10 ^-4 1.15x10 ^-4 adhesion
(Class) One 0 0 2 3 One

Although the preferred embodiments of the present disclosure have been illustrated and described above, the present disclosure is not limited to the specific embodiments described above, and it is common in the technical field to which the disclosure belongs without departing from the gist of the present disclosure as claimed in the claims. Various modifications may be made by those having the knowledge of

10: base substrate
20: conductive film
100: conductive substrate

Claims (10)

As a conductive ink composition capable of sintering at low temperature,
The composition comprises 50 to 85% by weight of a conductive powder;
5 to 20% by weight of an organic binder; and
10 to 30% by weight of a solvent,
Here, the low temperature is less than 80 ℃,
The conductive powder includes a first conductive powder and a second conductive powder, wherein the particle diameter of the first conductive powder is larger than that of the second conductive powder, the conductive ink composition capable of being sintered at a low temperature. The method according to claim 1,
The conductive powder includes silver, nickel, copper, aluminum, gold, an alloy of two or more thereof, or a combination thereof, a conductive ink composition capable of being sintered at a low temperature. 3. The method according to claim 2,
A conductive ink composition capable of sintering at a low temperature, wherein the metal included in the first conductive powder and the metal included in the second conductive powder are different. The method according to claim 1,
The particle diameter of the first conductive powder is 1 μm or more to 10 μm or less,
The second conductive powder has a particle diameter of more than 500 nm to less than 1 μm, a conductive ink composition capable of being sintered at a low temperature. The method according to claim 1,
The composition is a conductive ink composition capable of sintering at a low temperature, comprising 1 to 10 parts by weight of the second conductive powder based on 100 parts by weight of the first conductive powder. The method according to claim 1,
The organic binder includes acrylic polyol, polyurethane, phenoxy, epoxy, or a combination thereof,
The solvent includes ethyl carbitol acetate and butyl cellosolve acetate, propylene glycol methyl ether, butyl carbitol, diethyl diglycol, butyl cellosolve, isoprone, or a combination thereof. composition. The method according to claim 1,
The viscosity of the composition is 10,000 to 1,000,000 cps, a conductive ink composition capable of sintering at a low temperature. A conductive substrate comprising:
base substrate; and
It includes a conductive film formed on the base substrate,
The conductive film is formed by printing the conductive ink composition capable of sintering at a low temperature according to any one of claims 1 to 7 on the base substrate and then sintering it at 80° C. or less,
The Young's modulus of the base substrate is 0.1 MPa to 4 GPa, the conductive substrate. 9. The method of claim 8,
The resistivity of the conductive film is 1x10 ^-4 (Ω·cm) or less, the conductive substrate. 9. The method of claim 8,
The base substrate has an elongation at break of 300% or less, a conductive substrate.

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