KR101668259B1 - Environment-friendly double-sided adhesive tape preventing oxidation of adherend - Google Patents

Abstract

The present invention provides a conductive adhesive composition comprising a conductive fiber substrate and a conductive pressure-sensitive adhesive layer formed on both sides of the conductive fiber substrate, wherein the conductive pressure-sensitive adhesive layer comprises an acrylic copolymer polymerized without using acrylic acid as a monomer, Sensitive adhesive tape comprising a pressure-sensitive adhesive composition containing a hydrocarbon-free solvent. The present invention relates to a double-sided conductive pressure-sensitive adhesive tape which is environmentally friendly and does not release human harmful substances, Can be remarkably suppressed and the adhesive force can be maintained for a long time under high humidity conditions, so that it can be effectively used for the purpose of fixing components and protecting circuits.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an environmentally friendly double-sided adhesive tape for preventing oxidation of an adherend surface,

The present invention relates to an environmentally friendly double-sided conductive pressure-sensitive adhesive tape having improved antioxidation performance on the surface of a material to be adhered and free of human harmful substances during use.

BACKGROUND ART [0002] In general, when manufacturing electric, electronic or semiconductor devices, adhesive tapes are used for the purpose of securing components and protecting circuits. These adhesive tapes play an important role in slimming down and lightening the electronic products, simplifying the manufacturing process of the electronic products, and shortening the manufacturing time, thereby greatly affecting the productivity improvement and the manufacturing cost reduction.

The double-sided conductive adhesive tape, which is one of various forms of the adhesive tape, has a structure in which a conductive adhesive is applied to both surfaces of a conductive substrate. In order to shield electromagnetic waves generated from a main body of an electronic device, It is mainly used for incorporating an electromagnetic wave shielding film into an optical filter of a display portion of an electronic apparatus or for imparting an electromagnetic wave shielding property to an external case or an external protective film which is mounted to the outside.

Among these, acrylic pressure sensitive adhesives, rubber pressure sensitive adhesives, silicone pressure sensitive adhesives, and the like are known as the pressure sensitive adhesives used in the production of the double-sided conductive pressure sensitive adhesive tapes, and acrylic pressure sensitive adhesives are most widely used because they are low cost raw materials and very easy to synthesize polymers.

However, double-sided conductive adhesive tapes made using acrylic pressure-sensitive adhesive (PSA), which is made of acrylic, are used for fixing polymer synthesis, viscosity control process for polymer processing, Aromatic hydrocarbon solvents such as toluene are used in a large amount in an additive mixing process for imparting processing and functional properties. These aromatic hydrocarbon solvents, such as toluene, are harmful to human bodies and are highly hazardous. In the advanced countries, which are particularly emphasizing environmental aspects, regulations are being tightened.

Such toluene is largely removed by hot air, infrared ray drying (IR) drying, and ultraviolet ray (UV) drying in the acrylic double-sided conductive adhesive tape manufacturing process, but a trace amount of toluene is not fundamentally removed, There is room for some residual tape, and research is needed on how to solve this problem.

On the other hand, an acrylic pressure-sensitive adhesive mainly composed of acrylic acid as a pressure-sensitive adhesive is mainly used for producing a double-sided conductive pressure-sensitive adhesive tape which requires heat resistance and heat resistance.

Acrylic pressure-sensitive adhesives made of acrylic acid as a raw material are liable to cause generation of outgas and moisture through high temperature, so that foaming may occur under a heat-resistant condition, whitening of the pressure-sensitive adhesive layer may occur due to moisture inflow under the heat- , And in order to compensate for such problems, an acid component has been prepared by blending the pressure-sensitive adhesive.

At this time, since the acid component has a high water-dispersibility, it suppresses whitening by dispersing water molecules widely on the pressure-sensitive adhesive layer, and has a cohesive force by hydrogen bonding, so that it plays a role of suppressing bubbles in heat-resistant foaming.

However, when the adherend is a specific metal alloy, acrylic acid is formed at the time of adhesion and corrosion occurs in the metal alloy due to acrylic acid, so that the resistance value And there is a problem that the conductivity of the double-sided conductive adhesive tape is reduced.

Korean registered patent: No. 10-1427617 (Publication date: June 19, 2012) Korean Patent Publication No. 10-2009-0095479 (Published on September 09, 2009) Korean Patent Publication No. 10-2013-0046971 (Publication date: May 3, 2013) Korean Registered Patent: No. 10-0808146 (Publication date: 2006.11.06)

Disclosure of the Invention The present invention has been conceived in order to solve the above-mentioned problems, and it is an object of the present invention to provide a conductive adhesive layer which is environmentally friendly and which does not emit harmful substances of human body, suppresses oxidation of the surfaces of conductive metals and adherends, The present invention is directed to a double-sided electroconductive adhesive tape capable of improving antioxidation performance and maintaining stickiness for a long time.

According to an aspect of the present invention, there is provided a conductive adhesive sheet comprising a conductive fiber substrate and a conductive adhesive layer formed on both surfaces of the conductive fiber substrate, wherein the conductive adhesive layer is formed by polymerizing acrylic acid without using a monomer as a monomer And a pressure-sensitive adhesive composition comprising an acrylic copolymer, an acrylic copolymer, a conductive material, and a solvent not containing an aromatic hydrocarbon.

The conductive fiber substrate is characterized in that the conductive coating layer is formed on one surface or both surfaces of the conductive fiber substrate.

The conductive coating layer may be formed of at least one selected from the group consisting of a conductive metal, a conductive metal oxide, a carbon black, a carbon nanotube, a graphene, and a conductive polymer. .

The fabric may be formed of a polyester fiber, a polystyrene fiber, a polyimide fiber, a polyamide fiber, a polyvinyl chloride fiber, a polyethylene fiber, a polypropylene fiber, a polyurethane fiber, a polyacrylonitrile fiber, .

The acrylic copolymer may be at least one selected from the group consisting of alkoxyalkyl (meth) acrylate, hydroxyalkyl (meth) acrylate, dialkylaminoalkyl (meth) acrylate, amide Acrylate-based, amino (meth) acrylate-based, and imide (meth) acrylate-based monomers.

The conductive material may be at least one selected from the group consisting of a conductive metal, a conductive metal oxide, a carbon black, a carbon nanotube, a graphene, and a conductive polymer .

The solvent may be ethyl acetate, acetone, isopropyl alcohol, ethyl alcohol, methyl alcohol, butyl alcohol, methyl ethyl ketone methyl ethyl ketone, methyl iso butyl ketone, butyl cellosolve, and ethyl cellosolve. In the present invention, it is preferable to use at least one selected from methyl ethyl ketone, methyl iso butyl ketone, butyl cellosolve and ethyl cellosolve.

Also, the conductive pressure-sensitive adhesive layer may be formed of an antioxidant, a light stabilizer, a tackifier, an antiformer, a plasticizer, an antistatic agent, or a rework agent agent).

The double-sided conductive pressure-sensitive adhesive tape according to the present invention does not use a solvent containing aromatic hydrocarbons such as toluene for producing a pressure-sensitive adhesive composition, and is environmentally friendly because it does not emit harmful substances even when used for a long period of human body.

In addition, the double-sided conductive pressure-sensitive adhesive tape according to the present invention uses an acrylic monomer not containing a carboxyl group, a phosphate group or a sulfone group, except an acrylic monomer containing acrylic acid, The occurrence of whitening on the surface of the layer is remarkably suppressed and the adhesive force can be maintained for a long time even under a high humidity condition and oxidation of the surface of the conductive metal and the surface of the adherend can be effectively prevented to effectively use for the purpose of securing components and protecting circuits.

1 is a cross-sectional view of a double-sided conductive adhesive tape according to the present invention.
2 is a cross-sectional view of a double-sided conductive adhesive tape including release paper according to the present invention.

Hereinafter, the present invention will be described in detail.

1 is a cross-sectional view of a double-sided conductive adhesive tape 100 according to the present invention.

1, a double-sided conductive adhesive tape 100 according to the present invention includes a conductive fiber substrate 110 and a conductive adhesive layer 120 formed on both surfaces of the conductive fiber substrate 110, (120) comprises a pressure-sensitive adhesive composition comprising an acrylic copolymer polymerized without using acrylic acid as a monomer, a solvent containing no conductive substance and aromatic hydrocarbon.

The conductive fiber substrate 110 is preferably a fabric (woven fabric, nonwoven fabric, or knitted fabric) having a conductive coating layer formed on one surface or both surfaces thereof.

The fabric may be made of a polyester fiber, a polystyrene fiber, a polyimide fiber, a polyamide fiber, a polyvinyl chloride fiber, a polyethylene fiber, a polypropylene fiber, a polyurethane fiber, a polyacrylonitrile fiber, However, the present invention is not limited thereto.

The conductive coating layer may be formed of at least one selected from the group consisting of a conductive metal, a conductive metal oxide, a carbon black, a carbon nanotube, a graphene, and a conductive polymer. It is not.

Particularly, when the metal is coated on the fabric, metal such as Ni, Fe, Zn, Pb, Cu, Au and Ag is sputtered sputtering) or electroless plating method or the like.

In the case of forming the metal coating layer by sputtering, there is an advantage that metal coating can be easily performed on the inner surface of the opening formed on the fabric and the coating layer can be formed by precisely adjusting the thickness to the nanometer scale. However, There is a disadvantage that the cost and time required for the coating process are large. On the other hand, when the electroless plating method is used, it has an advantage that it can be coated in a large area with relatively low cost and time as compared with sputtering.

The conductive adhesive layer 120 formed on both surfaces of the conductive fiber substrate 110 is coated with a pressure-sensitive adhesive composition on both sides of the conductive fiber substrate 110 to form a conductive pressure-sensitive adhesive layer.

For this, in the present invention, a pressure sensitive adhesive composition comprising an acrylic copolymer, a conductive substance, and a solvent polymerized without using acrylic acid as a monomer is coated with a known various coating method to form the conductive fiber substrate 110, The conductive pressure sensitive adhesive layer 120 may be formed on both sides of the conductive pressure sensitive adhesive layer 120.

The conventional acrylic copolymer is prepared by using an acrylic acid-based monomer containing a carboxyl group such as acrylic acid or methacrylic acid in order to control the adhesive force or the cohesive force. However, when the acrylic acid copolymer copolymerized with the acrylic acid monomer described above is used as an adhesive material, A carboxyl group, a phosphoric acid group, or a sulfone group is contained in the conductive impregnation agent layer 120, causing corrosion on the surface of the conductive metal and the adherend when adhered to the adherend for a long period of time, thereby lowering the durability of the conductive tape.

On the other hand, in the present invention, the acrylic copolymer contained in the pressure-sensitive adhesive composition is a polymer obtained by using only monomers which are not acrylic acid monomers, and examples thereof include alkoxyalkyl (meth) acrylate, hydroxyalkyl (meth) (Meth) acrylate, amide (meth) acrylate, cyano (meth) acrylate, amino (meth) acrylate and imide May be prepared using at least one acrylic monomer selected.

Preferably, the acrylic copolymer is an alkoxyalkyl (meth) acrylate monomer such as 2-methoxyethyl (meth) acrylate, hydroxyalkyl (meth) acrylate having a hydroxyl group as a functional group such as 2-hydroxyethyl (Meth) acrylate monomer having a nitrogen atom as a side chain, and an acrylic monomer such as diethylaminoethyl acrylate having a nitrogen atom as a side chain.

Further, it is preferable that the acrylic monomer containing 50 to 90% by weight of the alkoxyalkyl (meth) acrylate monomer, 4 to 10% by weight of the hydroxyalkyl (meth) acrylate monomer having the hydroxyl group as the functional group, and the nitrogen- (Weight-average molecular weight, Mw) of 50,000 to 300,000, which is obtained by mixing with 5 wt% to 5 wt% of a conductive material, a cross-linking agent, a solvent and the like and performing a copolymerization reaction.

For reference, an acrylic monomer such as an alkoxyalkyl (meth) acrylate improves the durability of a pressure-sensitive adhesive composition and an acrylic monomer such as a hydroxyalkyl (meth) acrylate having a hydroxyl group as a functional group is crosslinked by a reaction with a cross- And the acrylic monomer such as diethylaminoethyl acrylate has a nitrogen atom as a side chain so as to improve the saturated moisture content of the conductive pressure-sensitive adhesive layer 120 and to improve the cohesive strength of the conductive pressure- The occurrence of whitening on the surface of the layer 120 is suppressed and the water molecules introduced into the conductive pressure-sensitive adhesive layer 120 rapidly dissipate even under a high humidity condition, so that the adhesive strength of the double-sided conductive pressure-sensitive adhesive tape according to the present invention is maintained for a long time .

As described above, in the present invention, the acrylic monomer except for the monomer containing acrylic acid is used as the pressure sensitive adhesive composition by using the acrylic copolymer as the pressure sensitive adhesive composition. Therefore, when the pressure sensitive adhesive tape for double- An acid component is not generated in the conductive pressure-sensitive adhesive layer 120 and the metal corrosion resistance is low because it does not substantially contain a carboxyl group, a phosphoric acid group, or a sulfone group. Thus, oxidation of the surface of the conductive metal and the adherend can be prevented.

The acrylic copolymer prepared by copolymerizing the acrylic monomer is prepared from a low molecular weight acrylic copolymer having a weight average molecular weight of 50,000 to 300,000 so as to have a high degree of freedom and is used as a pressure sensitive adhesive composition, It is possible to increase the efficiency of dissipating one water molecule and suppress the occurrence of whitening in the conductive pressure-sensitive adhesive layer (120).

On the other hand, the conductive material contained in the pressure-sensitive adhesive composition is preferably a metal such as silver (Ag), gold (Au), nickel (Ni), and copper (Cu) excellent in conductivity, a metal oxide such as ITO, a conductive carbon black, a carbon nanotube, a graphene, and a conductive polymer may be mixed or added to a solvent alone to impart conductivity to the conductive pressure-sensitive adhesive layer.

In the present invention, the solvent contained in the pressure-sensitive adhesive composition is a solvent which does not contain an aromatic functional group and does not release a harmful substance to the human body and is capable of effectively dissolving an acrylic monomer, a conductive substance and a crosslinking agent, Is typically selected from the group consisting of ethyl acetate, acetone, isopropyl alcohol, ethyl alcohol, methyl alcohol, butyl alcohol, methyl ethyl ketone, methyl isobutyl ketone, butyl cellosolve, and ethyl cellosolve.

Preferably, ethyl acetate is added in an amount of 30 to 80% by weight, more preferably 50 to 60% by weight of the total amount of the solvent, and acetone and alcohol are added in an amount of 40% , It has the best physical properties and the optimum viscosity.

Meanwhile, the method for producing the pressure-sensitive adhesive composition as described above is not particularly limited, and it is possible to produce a pressure-sensitive adhesive composition by mixing an acrylic copolymer and a conductive material in a solvent, as well as an acrylic monomer, a conductive substance, , The pressure-sensitive adhesive composition may be prepared.

In the case of preparing a pressure-sensitive adhesive composition by mixing a conductive material with a solution of a polymerization-completed acrylic copolymer, the acrylic monomer may be used in an amount of 40 to 60 wt% based on the total weight of the pressure-sensitive adhesive composition and 1 to 10 wt% 40 to 60% by weight of a polymerization solvent may be added, and 0.1 to 5% by weight of a polymerization initiator may be added and copolymerized to prepare a pressure-sensitive adhesive composition.

For reference, the polymerization initiator may be exemplified by an azo-based initiator, a peroxide-based initiator and the like. The crosslinking agent may be an isocyanate, a 1,6-hexanediol diacrylate (HDDA), or a polyethylene glycol diacrylate glycol diacrylate, and PEGDA) may be further added to improve cohesion and improve adhesion.

The solution polymerization is preferably carried out in an inert gas atmosphere, and the solution polymerization reaction proceeds at a reaction temperature of 50 to 90 ° C. for about 4 to 20 hours because the boiling point of the solvent to be used is low. Since a polymerization solvent such as toluene containing a highly reactive aromatic group is not used and reactivity may be somewhat low, it is preferable to carry out a sufficient solution polymerization reaction for a long time to prepare an acrylic copolymer. A pressure-sensitive adhesive composition comprising an acrylic copolymer having a weight average molecular weight of 50,000 to 400,000 can be prepared.

In addition, the adhesive strength and conductivity can be controlled by adjusting the amount of the conductive material and the acrylic copolymer contained in the pressure-sensitive adhesive composition, and the solvent can be used as a viscosity-adjusting diluent for the pressure-sensitive adhesive material prepared according to the amount of the adhesive.

Further, in the present invention, in order to further improve physical properties such as tackiness and stability of the conductive pressure-sensitive adhesive layer 120, or to impart additional functions such as electromagnetic shielding or light shielding, a range of 5 wt% An additional antioxidant, a light stabilizer, a tackifier, an antiformer, a plasticizer, an antistatic agent or a rework agent is added .

The pressure-sensitive adhesive composition prepared as described above may be coated on the conductive fiber substrate 110 to form a conductive pressure-sensitive adhesive layer. Various known coating methods such as spin coating, roll coating, gravure coating, reverse gravure coating, Can be used.

When the pressure-sensitive adhesive composition is coated on the conductive fiber substrate 110 as described above, it easily flows into the pores of the conductive fiber substrate, and thus the adhesive strength between the conductive fiber substrate 110 and the conductive pressure-sensitive adhesive layer 120 is extremely high.

The thickness of the conductive pressure-sensitive adhesive layer in the double-sided conductive pressure-sensitive adhesive tape 100 to be produced is not particularly limited. However, it can be used for various parts requiring circuit spacing between adherends have.

2 is a cross-sectional view of a double-sided conductive adhesive tape 100 including a release paper 130 according to the present invention.

2, the double-sided conductive pressure-sensitive adhesive tape 100 according to the present invention includes paper, polyethylene terephthalate (PET) resin, polyethylene (PE) resin Or a release paper 130 made of a polypropylene (PP) resin or the like may be further included to improve the storage property of the double-sided conductive adhesive tape 100.

As described above, the double-sided conductive pressure-sensitive adhesive tape 100 according to the present invention does not use a solvent containing an aromatic hydrocarbon such as toluene and is environmentally friendly because it does not emit harmful substances of human body, and does not use acrylic acid as a monomer Since an acrylic copolymer free from a functional group such as a carboxyl group, a phosphoric acid group or a sulfone group is used, an acid component due to moisture is not generated, so that occurrence of whitening on the surface of the conductive pressure sensitive adhesive layer 120 is remarkably suppressed, It is possible to effectively prevent the oxidation of the surface of the conductive metal and the adherend to effectively fix parts of various electronic products and protect circuits.

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

The embodiments shown are illustrative only of the invention and are not intended to limit the scope of the invention.

<Examples>

In order to produce the double-sided conductive pressure-sensitive adhesive tape according to the present example, three kinds of (meth) acrylic esters composed of 2-methoxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate and diethylaminoethyl acrylate The acrylic monomer was copolymerized to prepare an acrylic copolymer, and a pressure sensitive adhesive composition having adhesive strength was prepared.

To this end, a 1 L capacity polymerization reactor equipped with a stirrer, a condenser, a thermometer, a dropping funnel and a nitrogen inlet was charged with 20 wt% (60% ethyl acetate, 30% ethyl alcohol and 10% The solvent of methyl ethyl ketone was charged to the reactor in advance and the internal temperature was maintained at 80 占 폚.

Then, 2 wt% of 2-hydroxyethyl (meth) acrylate, 7 wt% of diethylaminoethyl acrylate and 8 wt% of 2-hydroxyalkyl (meth) 20 weight% of powder was added, 1 weight% of azo type initiator was added, 4 weight% of isocyanate was added, the temperature was raised to 70 占 폚 while stirring in a nitrogen atmosphere, polymerization reaction was carried out for 5 hours, To a concentration of 40% by mass to obtain a pressure-sensitive adhesive composition solution containing an acrylic copolymer.

This pressure-sensitive adhesive composition solution was coated on the PET film so as to have a thickness of 200 탆 or less after drying using a die coating method, and then the polyethylene terephthalate conductive fiber base coated with the silver particles coated on the surface of the conductive pressure- The pressure-sensitive adhesive composition solution was coated again and dried in a dryer at 80 캜 for 2 minutes to remove the solvent and aged at 23 캜 and 65% RH for 7 days to prepare a double-sided conductive pressure-sensitive adhesive tape having a total thickness of 500 탆.

<Experimental Example>

The thus obtained double-sided conductive adhesive tape according to this example was attached to the surface (mirror surface) of a silicon wafer, and the 180 degree peel adhesion (adhesive force before UV irradiation) was measured by a measurement method according to JIS Z0237.

As a result of measuring the adhesive strength, the initial adhesive strength was more than 8900 mN / 25㎜, and it was 9000 mN / 25㎜ after 7 days stickiness. Further, as a result of nonvolatile content and viscosity measurement according to ethyl acetate as a solvent, it was found that the solid content was 60% or more and the viscosity was 14000 cps or more.

Further, the change in resistance value of the double-sided conductive adhesive tape according to this example was measured.

To measure the resistance of the double-sided conductive adhesive tape, the current was gradually increased from 1 to 10 amperes to a double-sided conductive adhesive tape cut into 20 mm x 50 mm, held at 10 amperes for 2 minutes, and then gradually decreased to 1 amperes. During the test, the voltage across the junction was recorded, and then the resistance was calculated according to Ohm's law.

As a result of measuring the resistance of the double-sided conductive adhesive tape according to the present embodiment as described above, the resistance measured at 1 ampere was 0.07 mΩ, which was 0.0075 mΩ at 5 ampere and 0.0081 mΩ at 10 ampere, It was confirmed that the change of the resistance value was about 12%.

Then, the double-sided conductive adhesive tape of this example cut into 20 mm x 50 mm was attached to the ITO-deposited PET film, sterilized at 50 캜 for 5 minutes under a pressure of 5 atm, left for 500 hours, and then the resistance value was measured at room temperature. It was confirmed that the change of one resistance value was less than 10% as compared with that before the resistance value measurement, and the corrosion resistance was excellent.

As a result of measuring the haze value of the conductive pressure-sensitive adhesive layer, it was confirmed that the haze was 1% or less, so that the whitening of the conductive pressure-sensitive adhesive layer hardly occurred and almost no oxidation occurred. As a result, It has been confirmed that the conductive adhesive tape has excellent physical properties, has excellent adhesion even in a harsh environment, and can be used effectively in various fields due to a small change in resistance.

100: double-sided conductive adhesive tape 110: conductive fiber substrate
120: conductive pressure-sensitive adhesive layer 130: release paper

Claims (8)

Conductive fiber substrates; And
And a conductive pressure-sensitive adhesive layer formed on both surfaces of the conductive fiber substrate,
The conductive pressure-sensitive adhesive layer may be a layer selected from the group consisting of alkoxyalkyl (meth) acrylate, hydroxyalkyl (meth) acrylate, and dialkylaminoalkyl (meth) acrylate without using acrylic acid as a monomer An acrylic copolymer obtained by copolymerizing one or more monomers; Conductive material; And a solvent which does not contain aromatic hydrocarbons. 2. A double-sided conductive pressure-sensitive adhesive tape comprising: The method according to claim 1,
Wherein the conductive fiber substrate is a fabric having a conductive coating layer formed on one surface or both surfaces thereof. 3. The method of claim 2,
Wherein the conductive coating layer is formed of at least one selected from the group consisting of a conductive metal, a conductive metal oxide, carbon black, carbon nanotube, graphene, and a conductive polymer. Double-sided conductive adhesive tape. 3. The method of claim 2,
The fabric may be a polyester fiber, a polystyrene fiber, a polyimide fiber, a polyamide fiber, a polyvinyl chloride fiber, a polyethylene fiber, a polypropylene fiber, Wherein the adhesive tape is made of a fiber, a polyurethane fiber, a polyacrylonitrile fiber, a glass fiber, or a natural fiber. delete The method according to claim 1,
Wherein the conductive material is at least one selected from the group consisting of a conductive metal, a conductive metal oxide, a carbon black, a carbon nanotube, a graphene, and a conductive polymer. Adhesive tape. The method according to claim 1,
The solvent is selected from the group consisting of ethyl acetate, acetone, isopropyl alcohol, ethyl alcohol, methyl alcohol, butyl alcohol, methyl ethyl wherein the adhesive tape is at least one selected from the group consisting of ketone, methyl iso butyl ketone, butyl cellosolve and ethyl cellosolve. The method according to claim 1,
The conductive pressure-sensitive adhesive layer may be formed of an antioxidant, a light stabilizer, a tackifier, an antiformer, a plasticizer, an antistatic agent, or a rework agent. Wherein the adhesive tape further comprises an adhesive layer.

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