KR20160103397A - Coated tape with preventing electromagnetic interference and method for manufacturing of the same - Google Patents

Abstract

The present invention relates to an adhesive tape having a function of absorbing electromagnetic interference and a producing method thereof. A slimmed electronic device is provided while maintaining or improving an electromagnetic interference (EMI) absorbing function in comparison with using a separate adhesive tape for attaching a conventional EMI absorbing layer to an electronic device part by providing an adhesive tape having a layer with the EMI absorbing function and adhesion properties on one side or both sides when using the adhesive tape having a function of absorbing EMI.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive tape having a radio wave interference noise absorbing function,

The present invention relates to a pressure-sensitive adhesive tape having a radio-interference-noise absorbing function and a method of manufacturing the same, wherein a product having EMI absorption function is placed in a pressure-sensitive adhesive layer of a tape, And a method for producing the same.

As smart mobile devices such as smart phones, tablet PCs, digital cameras, and so on are increasingly demanding functions, speed and ease of portability, devices are changing with increasing focus on functional integration, high capacity and high speed. For this purpose, ultra-high-speed signal transmission processing of electronic circuits and low-voltage and high-current driving technologies are rapidly developing, and as the thinning and miniaturization of devices are progressing, electromagnetic noise interference in a device due to high density mounting necessarily occurs.

Recently, due to high expectations of users on image quality, ensuring of signal quality and accuracy of information transmission becomes more important, so that electromagnetic interference of a quasi-microwave band generated between high-density electronic components and wirings in small- (EMI) has emerged as an essential issue to consider when designing small electronic devices.

Korean Patent Application No. 10-2006-0117542, resistance-embedded EMI filter

An object of the present invention is to provide a pressure-sensitive adhesive tape having an EMI-absorbing function and a method of manufacturing the same, and a tape having an adhesive layer containing an electromagnetic wave absorber and capable of improving EMI absorption performance compared to existing products, Performance NFC antennas, wirelessly charged Rx antennas, and sensor boards for digitizers.

A method of manufacturing an EMI absorbing functional adhesive tape according to an embodiment of the present invention is a method of manufacturing an EMI absorbing functional adhesive tape comprising a soft magnetic metal flake powder having a particle size of 0.005 to 0.03 mm and an aspect ratio of 1.0 to 3.5, By weight and 60 to 75% by weight of the total weight of the mixture, to prepare a functional adhesive mixture; And a step of preparing a functional adhesive tape in which the functional adhesive mixture solution is coated on one or both surfaces of a release film and dried at 45 to 90 캜 to produce an EMI absorbing functional adhesive tape.

The soft magnetic metal flake powder may be prepared by a process for producing a soft magnetic metal flake powder including a baking step and a heat treatment step.

The baking step includes a step of putting a soft magnetic metal raw material in a solvent for a ball mill containing alcohol and performing ball milling to obtain a flour powder which is flattened to have an aspect ratio of 1.0 to 3.5

The heat treatment step includes a step of removing the solvent for the ball mill from the powder of the flakes, and heat-treating the heat-treated flake powder in an inert atmosphere at a temperature of 600 to 900 DEG C for 4 to 8 hours.

In the ball milling, the soft magnetic metal raw material and the ball milling solvent may be mixed in a ratio of 40 to 60 wt% and 60 to 40 wt%, respectively, in the frying step.

The ball used for the ball milling in the frying step may be ball milled by mixing 60 to 80 wt% of the balls having a size of 5 mm and 20 to 40 wt% of 10 mm.

The removal of the solvent for the ball mill in the heat treatment step may be carried out at a drying temperature of 80 to 100 ° C. and a drying time of 6 to 10 hours.

In the heat treatment step, the inert atmosphere may contain nitrogen and hydrogen in a volume amount of 60 to 70 L and 65 to 75 L.

The step of preparing the mixed solution may include mixing the soft magnetic metal flake powder and the pressure-sensitive adhesive raw material at 60 to 180 rpm for 10 to 30 minutes.

The functional adhesive tape manufacturing step may be performed in a roll-to-roll manner, and the speed of the roll winder may be 0.4 to 4.5 M / min.

According to another embodiment of the present invention, an EMI absorbing functional adhesive tape comprises: a release film layer; And an EMI (electromagnetic interference) absorbing functional adhesive layer located on one side or both sides of the release film layer.

The EMI absorbing functional adhesive layer may contain 25 to 40% by weight of a flake powder having an EMI-absorbing function and a particle size of 0.005 to 0.03 mm and an aspect ratio of 1.0 to 3.5, and 60 to 75% by weight of a pressure-sensitive adhesive.

The EMI-absorptive adhesive layer located on one side or both sides of the release film layer may have a thickness of 5 to 50 μm and a permeability of 3 to 10.

The electronic apparatus having improved EMI absorption function according to another embodiment of the present invention includes the EMI absorbing functional adhesive tape as described above, and may be any one selected from the group consisting of an NFC antenna, a wirelessly charged Rx antenna, and a sensor board for a digitizer Lt; / RTI >

Hereinafter, the present invention will be described in more detail.

In an NFC antenna (Near Field Communication Antenna), a wireless rechargeable Rx antenna, and a sensor board for a digitizer, an EMI absorber is applied in a form that an EMI absorber is attached between each of the existing components. Therefore, there is a problem in that such a structure is difficult to satisfy the performance of miniaturization and high performance required in recent electronic apparatuses. Particularly, in order to sufficiently provide the EMI function, the thickness of the EMI absorber must be guaranteed to some extent. However, the technology has been limited in order to satisfy both miniaturization, high performance, and thickness of the EMI absorber.

In order to solve such a problem, a method of manufacturing an EMI absorbing functional adhesive tape according to an embodiment of the present invention includes the steps of: preparing a mixed solution for mixing a soft magnetic metal flake powder and a pressure-sensitive adhesive raw material to produce a functional pressure- And a step of preparing a functional adhesive tape in which the functional adhesive mixture solution is coated on one side or both sides of a release film and dried to produce an EMI absorbing functional adhesive tape. In the present invention, a functional adhesive mixture is manufactured so as to have an EMI-absorbing function while maintaining the adhesive property of the adhesive tape, and it is applicable to a roll-to-roll manufacturing process so that the EMI-absorbing functional adhesive A method of manufacturing a tape can be provided.

The soft magnetic metal flake powder may have a particle size of 0.005 to 0.03 mm and an aspect ratio of 1.0 to 3.5 based on the longitudinal direction. The use of the soft magnetic metal flake powder having such a particle size and aspect ratio can improve the EMI shielding function while enhancing the dispersibility to the pressure-sensitive adhesive raw material described below.

The soft magnetic metal flake powder may be prepared by a process for producing a soft magnetic metal flake powder including a baking step and a heat treatment step.

The baking step is a step of putting the soft magnetic metal material in a solvent for a ball mill containing alcohol and performing ball milling to obtain a flour powder which is flattened to have an aspect ratio of 1.0 to 3.5.

The soft magnetic metal raw material serves as an electromagnetic wave absorber and may be any of ferrite, carbonyl iron, iron-silicon alloy, iron-nickel alloy, iron-silicon-aluminum alloy, iron-cobalt alloy, Zinc alloys, nickel-zinc alloys, and the like can be applied, for example, sendust or permalloy powder can be used.

The soft magnetic metal material and the ball mill solvent may be used in an amount of 40 to 60 wt% and 60 to 40 wt%, respectively, and the ball mill solvent composed of the soft magnetic metal raw material and the alcohol may be used in an amount of 40 to 60 wt% 60% by weight, and 40% by weight to 60% by weight.

When the alcohol is used in an amount of less than 40% by weight based on the soft magnetic metal raw material and the entire ball mill solvent, the soft magnetic metal particle powder may be undifferentiated to reduce the surface area thereof. If the alcohol is used in an amount exceeding 60% The flake time may become longer and the efficiency may be lowered. Isopropyl alcohol is preferably used as the alcohol, and when a solvent for a ball mill made of isopropyl alcohol is applied, there is an excellent effect in preventing the oxidation of the soft magnetic metal particle powder which may occur in the flaking process.

The ball used for the ball milling is preferably mixed with a ball having a size of 5 mm and a ball having a diameter of 10 mm. The ball is preferably used in a ball milling range of 60 to 80% by weight of 5 mm and 20 to 40% by weight of 10 mm. It is good. When the size of the ball is 5 mm, the size of the ball is less than 60% by weight. When the size of the ball is more than 40% by weight, it may be difficult to uniformize the particle size of the flake powder. When it is more than 10% by weight and less than 20% by weight, the soft magnetic metal powder may be undifferentiated and the product performance may be impaired. In addition, the ball may be made of stainless steel, and the ball may have sufficient strength so that the ball milling can proceed effectively.

After the ball milling of the soft magnetic metal material proceeds in a ball mill solvent, the ball mill solvent is removed from the flake powder and the removal of the solvent for the ball mill is performed at a drying temperature of 80-100 ° C and a drying time of 6-10 hours Lt; / RTI > The baking powder, from which the solvent has been removed, is then subjected to a heat treatment process.

In the heat treatment step, the dried flake powder is heat-treated in an inert atmosphere at a temperature of 600 to 900 ° C for 4 to 8 hours to prepare a heat-treated flake powder. The heat-treated flake powder has a property of improving the permeability as compared with the dried flake powder before heat treatment, and maximizes the EMI absorption function when the heat treatment is performed in the temperature and time range. Further, the soft magnetic metal powder may remove the residual stress remaining in the powder (powder) during the flaking process while the soft magnetic metal powder is subjected to the heat treatment step after the flake processing, The soft magnetic metal powder can have an excellent magnetic permeability by stabilizing the molecular structure of the soft magnetic metal powder.

The heat treatment may be conducted in an inert atmosphere, and the inert atmosphere may include nitrogen and hydrogen in a volume amount of 60 to 70 L: 65 to 75 L. When the amount of hydrogen is increased in the inert atmosphere, the cost is increased and there is a risk of explosion in the heat treatment process. The nitrogen serves to remove oxygen, which affects the oxidation of the soft magnetic metal powder, from the reaction chamber It helps to reduce the risk of explosion by excessive use of hydrogen and to reduce the cost. Therefore, it is preferable that the inert atmosphere is used in a volume of nitrogen and hydrogen of 60 to 70: 65 to 75.

The step of preparing the mixed solution is a step of mixing the soft magnetic metal flake powder as the heat treated flake powder and the pressure-sensitive adhesive raw material to prepare a functional pressure-sensitive adhesive mixture. Specifically, 25 to 40 wt% 60 to 75% by weight based on the total weight of the composition.

When the soft magnetic metal flake powder is used in an amount less than 25% by weight, the EMI shielding function may be insignificant. When the soft magnetic metal flake powder is used in an amount exceeding 40% by weight, the adhesive strength is lowered, There may be a problem in not forming and appearance quality.

The pressure-sensitive adhesive material may be an acrylic pressure-sensitive adhesive, a rubber pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, an ethylvinylacetate pressure-sensitive adhesive, or a polyvinyl ester pressure-sensitive adhesive.

The mixing may be performed by mixing the soft magnetic metal flake powder and the pressure-sensitive adhesive raw material at 60 to 420 rpm or 60 to 180 rpm for 10 to 30 minutes. At this time, the pressure-sensitive adhesive raw material and the soft metal flake powder are sufficiently Can be mixed.

In the step of manufacturing the functional adhesive tape, the functional adhesive mixture solution is coated on one side or both sides of the release film and dried to produce an EMI-absorbing adhesive tape.

The release film may be a film having heat resistance and flexibility. For example, the release film may be a film having a heat resistance and a flexibility. Examples of the release film include paper, polystyrene, polyethylene, polyimide, polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, nylon, polytetrafluoroethylene, Ether ether ketone, polycarbonate, polyarylate, and the like can be applied.

The drying may be carried out at a temperature of, for example, 45 to 90 ° C, and in the case of a roll-to-roll process capable of mass production, the speed of the roll winder may be adjusted to 0.4 to 4.5 M / min have. When the EMI absorbing functional adhesive tape is produced by the roll-to-roll method, an EMI absorbing functional adhesive tape having a stable quality can be mass-produced.

The EMI-absorbing functional adhesive tape thus manufactured can improve the EMI-absorbing function while reducing the thickness of the electronic device, unlike the conventional double-sided tape or adhesive layer, so that the function of the electronic device which is becoming slimmer can be maintained or improved.

According to another embodiment of the present invention, an EMI absorbing functional adhesive tape comprises: a release film layer; And an EMI (electromagnetic interference) absorbing functional adhesive layer located on one side or both sides of the release film layer.

The EMI absorbing functional adhesive layer may contain 25 to 40% by weight of a flake powder and 60 to 75% by weight of a pressure-sensitive adhesive. The flake powder preferably has an EMI-absorbing function, has a particle size of 0.005 to 0.03 mm, 3.5. ≪ / RTI > Also, the EMI-absorptive functional adhesive layer located on one side or both sides of the release film layer has a thickness of 5 to 50 μm and a permeability of 3 to 10, so that the electronic device to which the EMI absorbing layer is applied can be made slimmer and the EMI- Can be improved.

The electronic apparatus with improved EMI absorption function according to another embodiment of the present invention includes the above-described EMI absorbing functional adhesive tape. FIG. 1 is a conceptual view showing a structure of an example in which an NFC antenna is applied to one side of a battery using a conventional technique, FIG. 2 is a view illustrating an example of application of an NFC antenna employing an EMI absorbing functional adhesive tape according to an embodiment of the present invention, Fig. 1 and 2, in order to prevent the NFC antenna 2 from being disturbed by radio waves or electromagnetic waves from the battery 1 when the NFC antenna 2 is applied to one surface of the battery 1, It is necessary to apply the EMI absorbing layer 3 between the battery 1 and the NFC antenna 2 and the double-sided adhesive tape 4 as an adhesive layer for stably fixing these layers, EMI absorption layer 3, and between the EMI absorbing layer 3 and the NFC antenna 2, respectively. At this time, the adhesive layer merely adhered to each layer and has a certain thickness and fails to improve the EMI absorption function.

  However, when the EMI absorbing functional adhesive tape 10 of the present invention is applied, an EMI absorbing function and an adhesive layer are formed between the battery 1 and the EMI absorbing layer 3, and between the EMI absorbing layer 3 and the NFC antenna 2 at the same time It is possible to provide a slimmer product having the same or better EMI absorbing function as compared with the conventional product by applying the adhesive tape 10 (preferably double-sided tape). The electronic device is not limited to an NFC antenna. The electronic device may be applied to an electronic device using an EMI absorbing layer such as a wirelessly charged Rx antenna and a sensor board for a digitizer. In order to maintain or improve EMI absorption functionality while slimming the electronic device, The EMI-absorbing functional adhesive tape described above can be applied.

INDUSTRIAL APPLICABILITY The EMI-absorbing functional adhesive tape of the present invention provides a pressure-sensitive adhesive tape having one side or both sides of a layer having an EMI-absorbing function and an adhesive property, using a separate adhesive tape for bonding an existing EMI- It is possible to provide an electronic device that is slimmer and thinner while maintaining or improving EMI absorption functionality.

1 is a conceptual view showing a structure of an example in which an NFC antenna is applied to one side of a battery using a conventional technique.
2 is a conceptual diagram showing an example structure applied to an NFC antenna to which an EMI absorbing functional adhesive tape according to an embodiment of the present invention is applied and a battery.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Like parts are designated with like reference numerals throughout the specification.

1. Fabrication of EMI-absorbing double-sided tape

1) Processing of Flake Powder

Sample 1: 42 parts by weight of a raw material alloy powder containing Fe, Si and Al was put into a solvent of isopropyl alcohol (IPA) of 58 parts by weight and processed into a flake powder using an ATT attrition mill. In this case, balls having a diameter of 5 mm and balls having a diameter of 10 mm were mixed at a ratio of 6: 4 and milled together with the above-mentioned solvent. The milled flake powder was prepared so that the particle size was 5 to 30 μm and the aspect ratio was 1.0 to 3.5 on the basis of the length in the direction of the flats, and the following experiment was applied to the flake powder of the sample 1.

Sample 2: 42 parts by weight of a raw material alloy powder containing Fe, Si and Cr was put into a solvent of isopropyl alcohol (IPA) of 58 parts by weight and processed into a flake powder using an ATT mill. In this case, balls having a diameter of 5 mm and balls having a diameter of 10 mm were mixed at a ratio of 6: 4 and milled together with the above-mentioned solvent. The milled flake powder was prepared so that the particle size was 5 to 30 μm on a flat surface, and the following experiment was applied to the flake powder of sample 2.

2) Drying and heat treatment of Flake Powder

The residual solvent was removed from each of the flake powder of Sample 1 and Sample 2 and dried. The temperature at the time of drying was maintained at 80 to 100 캜 and dried for 6 to 10 hours.

The flakes of sample 1 and sample 2, from which the mixed solvent was removed by the drying process, were each heat-treated in the following procedure. Heat treatment was performed for 4 to 8 hours at a heat treatment temperature of 600 to 900 캜 in an inert atmosphere in which N ₂ 60 to 70 L and H ₂ 65 to 75 L gas were mixed. The heat treated flake powder is characterized by high permeability.

3) Preparation of functional adhesive mixture

Sample 1: 40 parts by weight of the flake powder of the sample 1 heat-treated above and 60 parts by weight of the acrylic adhesive raw material were mixed. The mixing was carried out at 60 to 180 rpm at room temperature for 10 to 30 minutes to prepare the functional adhesive mixture solution of Example 1. The same procedure as in the preparation of the functional pressure-sensitive adhesive mixture of Example 1 was conducted except that the use ratio of the heat-treated flake powder and the pressure-sensitive adhesive was mixed as shown in the following Table 1 to obtain the functional pressure-sensitive adhesive mixture of Examples 2 to 4, .

Sample 2: The same procedure as in the case of Sample 1 above was carried out, except that the flake powder of Sample 1 and the acrylic pressure-sensitive adhesive were applied and then applied as the functional pressure-sensitive adhesive mixture of Sample 2.

4) Production of functional adhesive tape

Sample 1: An EMI-absorbing adhesive tape was prepared by the following procedure using the functional adhesive mixtures of Examples 1 to 4 prepared in Sample 1 of 3).

The functional adhesive mixture was injected into a Comma Roll, and was manufactured using a roll-wader process. As the release film, a PET film having a thickness of 0.1 mm was used. Specifically, the functional pressure-sensitive adhesive mixture was applied to the PET film at a roll interval of 0.05 mm and passed through a drier at about 45 ° C at a speed of 0.5 m / minute to prepare a double-sided tape of Examples 1 to 4 .

Sample 2: A double-faced tape was produced in the same manner as Sample 1 of the above 4) by using the functional adhesive solutions of Examples 1 to 4 prepared in Sample 2) of 3) above. At this time, the other conditions were the same except that a drying temperature of about 90 ° C was applied at a speed of 4.5 m per minute.

2. Performance evaluation of EMI-absorbing double-sided tape

EMI absorption function of the EMI-absorbing double-faced tape using the flake powder of Sample 1 prepared in the above 1. was evaluated. The results are shown in Table 1 below. The EMI absorption function was evaluated in accordance with KS C6031 standard (u '@ 3 MHz) and the same as the samples of Examples 1 to 4, except that a normal double-sided tape of the same thickness was used instead of the EMI- The magnetic permeability of the prepared comparative sample was measured, and the difference in the magnetic permeability between each of Examples 1 to 4 and Comparative Example was shown in the permeability evaluation item. Adhesion performance was evaluated as being excellent when it was 500 gf / inch or more, bad when it was 200 to 500 gf / inch, and bad when it was less than 200 gf / inch.

division Acrylic
Adhesive (parts by weight) flake
Powder (parts by weight) Thickness of adhesive layer (mm) Stickiness
evaluation Investment ratio
evaluation* Example 1 75 25 0.025 Great 3 Example 2 70 30 0.025 Great 5.3 Example 3 65 35 0.025 usually 7.1 Example 4 60 40 0.025 usually 9.8

* The permeability was evaluated in the same manner as in Example 1, but showed a difference in magnetic permeability from the comparative example in which a general double-sided tape was used instead of the EMI-absorbing double-sided tape.

The EMI absorption function of the EMI-absorbing double-sided tape using the flake powder of Sample 2 prepared in the above item 1 was also evaluated in the same manner as described above.

division Acrylic
Adhesive (parts by weight) flake
Powder (parts by weight) Thickness of adhesive layer (mm) Stickiness
evaluation Investment ratio
evaluation* Example 1 75 25 0.025 Great 0.5 Example 2 70 30 0.025 Great 0.8 Example 3 65 35 0.025 usually 1.3 Example 4 60 40 0.025 usually 1.5

* The permeability was evaluated in the same manner as in Example 1, but showed a difference in magnetic permeability from the comparative example in which a general double-sided tape was used instead of the EMI-absorbing double-sided tape.

Referring to the results of Tables 1 and 2, when the EMI-absorbing double-sided tape of the present invention is applied, the EMI absorption performance of the manufactured product can be improved by maintaining or improving tackiness, And that it can be manufactured with excellent quality through a possible roll-to-roll manufacturing process.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of the right.

1: Battery 2: NFC antenna
3: EMI absorption layer 4: double-sided tape layer
10: EMI-absorbing functional adhesive tape

Claims (11)

The soft magnetic metal flake powder having a particle size of from 0.005 to 0.03 mm and an aspect ratio of from 1.0 to 3.5 based on the longitudinal direction and a pressure-sensitive adhesive raw material in a ratio of 25 to 40% by weight and 60 to 75% by weight, A step of preparing a mixed liquid to be produced;
Applying the functional adhesive mixture on one or both sides of the release film and drying the adhesive tape at 45 to 90 DEG C to produce an EMI absorbing functional adhesive tape. The method according to claim 1,
The soft magnetic metal flake powder is prepared by a process for producing a soft magnetic metal flake powder including a baking step and a heat treatment step,
The step of baking is a step of putting a soft magnetic metal raw material in a solvent for a ball mill containing alcohol and performing ball milling to obtain a flour powder which is flattened to have an aspect ratio of 1.0 to 3.5,
The heat treatment step may include a step of removing the ball mill solvent from the flake powder and heat treating the heat treated flake powder in an inert atmosphere at a temperature of 600 to 900 ° C for 4 to 8 hours to form an EMI absorbing functional adhesive tape ≪ / RTI > 3. The method of claim 2,
Wherein the soft magnetic metal material and the ball mill solvent are mixed in a ratio of 40 to 60% by weight and 60 to 40% by weight, respectively, in the ball milling step in the framing step, ≪ / RTI > 3. The method of claim 2,
Wherein the ball used for ball milling in the framing step includes 60 to 80 wt% of a ball having a size of 5 mm and 20 to 40 wt% of a ball having a size of 10 mm, whereby ball milling proceeds. Way. 3. The method of claim 2,
Wherein the removal of the solvent for the ball mill in the heat treatment step is performed at a drying temperature of 80 to 100 占 폚 and a drying time of 6 to 10 hours. 3. The method of claim 2,
Wherein the inert atmosphere in the heat treatment step includes nitrogen and hydrogen in a volume amount of 60 to 70 L and 65 to 75 L volume. The method according to claim 1,
Wherein the step of preparing the mixed liquid comprises mixing the soft magnetic metal flake powder and the pressure-sensitive adhesive raw material at 60 to 180 rpm for 10 to 30 minutes. The method according to claim 1,
Wherein the step of manufacturing the functional adhesive tape is performed in a roll-to-roll manner, and the speed of the roll winder is 0.4 to 4.5 M / min. A release film layer; And an EMI (electromagnetic interference) absorbing functional adhesive layer located on one side or both sides of the release film layer
Wherein the EMI absorbing functional adhesive layer comprises EMI absorbing functional adhesive layer having EMI absorption function and containing 25 to 40% by weight of flake powder having a particle size of 0.005 to 0.03 mm and an aspect ratio of 1.0 to 3.5 and 60 to 75% tape. 10. The method of claim 9,
Wherein the EMI-absorptive functional adhesive layer located on one side or both sides of the release film layer has a thickness of 5 to 50 μm and a permeability of 3 to 10. An EMI-enhanced electronic device comprising the EMI-absorbing adhesive tape according to claim 9, wherein the EMI-absorbing functional adhesive tape is selected from the group consisting of an NFC antenna, a wirelessly charged Rx antenna, and a sensor board for a digitizer.

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