TW201437435A - Electrolytic copper foil and method for manufacturing the same and surface-treated copper foil using the electrolytic copper foil - Google Patents

Abstract

The present invention is to provide an electrolytic copper foil with excellent physical characteristics after high temperature heating compared to that of the prior art, and the also electrolytic copper foil is suit for use in negative electrode collector of lithium ion secondary cell. To this end, electrolytic cooper foil with following features is used: normal tensile strength over 600 MPa, tensile strength over 470 MPa after heating at temperature of 350 DEG C for 1h. The invention also provides a method for manufacturing the electrolytic cooper foil using polyethylenimine having a concentration of 20 mg/L to 100 mg/L (molecular weight is about 10000 to 70000) and a sulfuric acid copper electrolyte having a chloride concentration of 0.5 mg/L to 2.5 mg/L.

Description

Electrolytic copper foil, method for producing the same, and surface obtained by using the same Processing copper foil

The present application relates to an electrolytic copper foil, a method for producing the electrolytic copper foil, and a surface-treated copper foil obtained by using the electrolytic copper foil. In particular, it is an electrolytic copper foil which is excellent in high-temperature heat resistance when subjected to high-temperature heating.

Electrolytic copper foil has been widely used in various fields such as a printed wiring board field, a negative electrode current collector of a lithium ion secondary battery, and the like. Further, in the printed wiring board, a very high temperature exceeding 250 ° C is used as a processing temperature when the copper foil and the insulating layer are laminated, and the electrolytic copper foil subjected to a high temperature load is softened to deteriorate the physical strength. Therefore, various problems arise. Further, when an electrolytic copper foil is used as the negative electrode current collector of the lithium ion secondary battery, when a mixture layer containing a negative electrode active material is formed on the surface of the electrolytic copper foil, a high temperature of about 300 ° C may be applied. At this time, if the electrolytic copper foil used in the anode current collector is softened, it is charged. Expansion during discharge. The resistance to shrinkage is lowered, and the life of the lithium ion secondary battery is shortened. Therefore, research on electrolytic copper foil excellent in high-temperature heat resistance under high-temperature heating has been continuously performed.

For example, in the patent document 1 (Japanese Patent Application Laid-Open No. 2012-140660), the object is to provide a high strength after long-term storage, and also after heating. It is an electrolytic copper foil which is high in strength and excellent in electrical conductivity, and discloses "water solubility by (A) dithiocarbamic acid derivative or its salt, (B) thiourea, (C) having a mercapto group by electrolysis. An electrolytic copper foil is produced by a sulfur compound or a derivative thereof or a salt thereof, (D) a polyalkylene glycol, and (E) a chloride acid plating solution of an acid chloride as an additive. Further, when the request 1 of Patent Document 1 is examined, it is revealed that "the tensile strength and electrical conductivity at 20 ° C are measured after heating at 240 ° C for 10 minutes within 120 minutes after the completion of electrodeposition, and stretching is performed. The strength is 650 MPa or more, the electrical conductivity is 80% IACS or more, and the tensile strength at 20 ° C measured after 168 hours after the end of electrodeposition is 90% of the tensile strength measured at 20 ° C within 120 minutes after the end of electrodeposition. % or more, an electrolytic copper foil having an elongation at 20 ° C of 3% or more measured within 120 minutes after completion of electrodeposition.

In the patent document 2 (Japanese Patent Application Laid-Open No. 2011-174146), the object is to provide a low-rough surface having an electrolytic copper foil material suitable for use in a Tape Automated Bonding process, and High-resistance, no electrolytic copper foil peeled off by tin coating, and reveals that an insoluble anode made of a sulfuric acid-copper sulfate aqueous solution as an electrolyte and titanium coated with a platinum group element or an oxide thereof is formed and formed with the anode. In the method for manufacturing a copper cathode foil, the direct current is passed through the electrolytic copper foil between the two electrodes, because the non-ionic water-soluble polymer, the sulfonate of the active organic sulfur compound, and the thiourea are present in the electrolyte. A compound having a roughness of 2.0 μm or less and a crystal having an orientation index of 5.0 or more obtained from the relative intensity of 220 copper rays by X-ray diffraction measured on the rough surface side. The structure and the electrolytic copper foil with a tensile strength of 500 MPa after heating at 180 ° C for 1 hour.

Patent Document 3 (Japanese Patent Application Laid-Open No. 2004-339558) The purpose of the present invention is to provide a low-rough surface electrolytic copper foil having a low roughness, a low roughness reduction rate over time or a heat treatment, and an excellent elongation at a high temperature, and a method for producing the same, and revealing By adding five additives of hydroxyethyl cellulose, polyethyleneimine, acetylene glycol, sulfonate of active organic sulfur compound and chloride ion to an electrolyte composed of a sulfuric acid-copper sulfate aqueous solution, The rough surface roughness Rz of the electrolytic copper foil is 2.5 μm or less, and the tensile strength at 25 ° C measured within 20 minutes from the end of the electrodeposition is 500 MPa or more, and is determined after 300 minutes from the end of electrodeposition. The rate of decrease in the tensile strength at ° C is 10% or less, or the rate of decrease in the tensile strength at 25 ° C measured from the time point after the end of electrodeposition to the application of heat treatment at 100 ° C for 10 minutes is 10% or less, and at 180 ° C. The low-rough surface electrolytic copper foil having an elongation of 6% or more.

In the patent document 4 (Japanese Patent Application Laid-Open No. 2008-285727), the object is to provide a normal temperature storage from the completion of the copper foil foil to the subsequent manufacturing step, or by the subsequent step 200~ Heat treatment at about 300 ° C, copper foil will not soften, and maintain high tensile strength electrolytic copper foil, and its manufacturing method, and use "from the completion of the copper foil foil to the characteristics of the copper foil after the timing The high tensile strength electrolytic copper foil having a tensile strength of 400 N/mm 2 or more as measured at 25 ° C. Further, as disclosed in claim 3 of Patent Document 4, it is disclosed that "the foil of the copper foil is completed, and after the characteristics of the copper foil are stabilized, the copper foil is heat-treated at 300 ° C for 1 hour, after the heat treatment. The high tensile strength electrolytic copper foil having a tensile strength of 400 N/mm 2 or more as measured at 25 ° C.

In the patent document 5 (Japanese Patent Application Laid-Open No. Hei No. 2012-151106), the object is to provide a capacitor that can be produced without repeating the charge and discharge cycle. An electrolytic copper foil for a lithium ion secondary battery negative electrode of a lithium ion secondary battery in which the life of the negative electrode current collector is not deteriorated, and the "0.2% proof endurance after heating at 200 to 400 ° C is 250 N/mm 2 In the above, the elongation of the electrolytic copper foil is rust-proofing or the rust-preventing treatment is performed on the surface of the active material layer, and the present invention discloses the use of the electrolytic copper foil as a set. Electrode for lithium ion secondary battery". That is, an electrolytic copper foil was used as a negative electrode current collector of a lithium ion secondary battery, and "0.2% proof stress" of the electrolytic copper foil at 240 ° C for 10 minutes was prescribed.

In the patent document 6 (Japanese Patent Application Laid-Open No. 2009-221592), the object of the present invention is to provide an electrolytic copper foil for forming a fine pitch circuit and to replace the Corson alloy foil for high-strength electrolysis. Copper foil, and discloses "an electrolytic copper foil which is obtained by electrolysis of copper electrolytic solution, wherein the electrolytic copper foil is characterized by containing 110 ppm to 400 ppm of sulfur, 150 ppm to 650 ppm of chlorine, and a conductivity of 48. % IACS or more, the value of the normal tensile strength is 70 kgf/cm2 or more."

In the patent document 7 (Japanese Laid-Open Patent Publication No. 2008-101267), it is an object of the invention to provide an electrolytic copper foil having a low uneven surface equivalent to a conventional low profile copper foil and having a great mechanical strength. And a method for producing the same, and revealing that "the precipitated crystal particles of copper are fine, and the electrodeposited copper foil is reduced to a degree that has never been the same in the past, and has a low unevenness and a glossy surface, and has a normal stretching. The strength is a mechanical strength of 70 kgf/mm2 to 100 kgf/mm2, and after heating (180 ° C × 60 minutes), it also has an electrolytic copper foil having a tensile strength value of 85% or more of the normal tensile strength value.

Patent Document 8 (International Application: WO2012/002526) The system provides an electrolytic copper foil which exhibits stable characteristics even if the chlorine content changes, and employs an electrolytic copper foil which is characterized by electrolytic copper foil obtained by electrolysis in a copper electrolyte, which is characterized by electrolytic copper foil. The iodine content is 0.003% by mass or more, and more preferably the iodine content is in the range of 0.003% by mass to 0.03% by mass. Further, the electrolytic copper foil exhibits a normal tensile strength of 48 kgf/mm 2 to 72 kgf/mm 2 , and a tensile strength of 27.5 kgf/mm 2 to 46.3 kgf/mm 2 after heating at 350 ° C for 60 minutes, and is suitable for lithium ion. The use of the negative electrode current collector of the secondary battery.

However, the electrolytic copper foil used in the negative electrode current collector of the lithium ion secondary battery has high requirements for preventing the deformation of the negative electrode current collector which occurs at the time of charge and discharge. In particular, in the case of the negative electrode of a lithium ion secondary battery in recent years, an alloy-based negative electrode active material having a large volume change accompanying charge and discharge may be used. In order to support the alloy-based negative electrode active material on the negative electrode current collector, a mixture layer is formed by using a strong binder to prevent collapse of the active material due to a large volume change upon charge and discharge. Further, when the polymerization reaction of the binder is caused, the temperature is 300 ° C or higher. As a result, the electrolytic copper foil used in the negative electrode current collector cannot have a high-temperature heat-resistant property capable of maintaining high strength after being heated at 300 ° C or higher, and thus the life of the lithium ion secondary battery cannot be extended.

According to the electrolytic copper foil disclosed in the above Patent Document 4, it is possible to have sufficient high-temperature heat resistance characteristics. However, the high-temperature heat-resistant property of the electrolytic copper foil in this document is "the tensile strength after heat treatment at 300 ° C for 1 hour is 400 N/mm 2 or more", but if the contents described in the examples are confirmed in detail, the self-made foil is completed. The tensile strength (tensile strength) after heating at 300 ° C for 1 hour after 72 hours from the time was in the range of 430 MPa to 500 MPa, and the tensile strength exceeding 500 MPa could not be obtained.

In addition, in recent years, electrolytic copper foil has not only been in the field of printed wiring boards, but also has a thin layer. The thinner the electrolytic copper foil, the easier it is to wrinkle during handling. From the viewpoint of preventing occurrence of wrinkles in the above-described treatment, it is preferred that not only the electrolytic copper foil has high physical properties after high-temperature heating, but also has high physical properties under normal conditions.

Accordingly, the object of the present application is to provide an electrolytic copper foil which is excellent in high-temperature heat resistance and which can be used in a negative electrode current collector for a printed wiring board and a lithium ion secondary battery.

Therefore, as a result of active research by the inventors of the present invention, an electrolytic copper foil which is excellent in both "normal physical properties" and "physical properties after high-temperature heating" is considered in comparison with the conventional electrolytic copper foil. Further, it is understood that the electrolytic copper foil of the present application is suitable for use as a negative electrode current collector of a lithium ion secondary battery. Hereinafter, the outline of the present application will be described.

Electrolytic copper foil: The electrolytic copper foil of the present application is characterized by a normal tensile strength of 600 MPa or more, and a tensile strength of 470 MPa or more after heating at 350 ° C for 1 hour.

The electrolytic copper foil of the present application has high physical properties of 0.2% or more with a resistance of 370 MPa or more after heating at 350 ° C for 1 hour.

Further, the electrolytic copper foil of the present application has a normal elongation of 2.5% or more and has an elongation which is practically unsuitable.

Further, in the electrolytic copper foil of the present application, as a trace component, the C content is 100 μg/g to 450 μg/g, the N content is 50 μg/g to 620 μg/g, and the O content is 400 μg/g to 3200 μg/g, S. When the content is 110 μg/g to 720 μg/g, the Cl content is 20 μg/g to 115 μg/g, and the relationship of {Cl/(C+N+O+S+Cl)}×100≦5 mass% is satisfied, based on the display It is preferred from the viewpoint of stability of high temperature heat resistance.

Method for producing electrolytic copper foil: The method for producing an electrolytic copper foil according to the present application is a method for producing the above-mentioned electrolytic copper foil, which is characterized by using a polyethyleneimine having a molecular weight of 10,000 to 70,000 at a concentration of 20 mg/L to 100 mg/L. And a sulfuric acid acidic copper electrolyte having a chlorine concentration of 0.5 mg/L to 2.5 mg/L is used as the copper electrolyte.

Surface-treated copper foil: The surface-treated copper foil of this application is characterized by using the above-mentioned electrolytic copper foil.

The electrolytic copper foil of the present application has physical properties of "normal tensile strength of 600 MPa or more" and "tensile strength after heating at 350 ° C for 1 hour" of 470 MPa or more. That is, the "normal physical properties" of the electrolytic copper foil of the present application and the "physical properties after high-temperature heating" are excellent. Accordingly, even in the case of a thin electrolytic copper foil, wrinkles occur less and have excellent handling characteristics. Further, even if the electrolytic copper foil is used as a negative electrode current collector of a lithium ion secondary battery, the tensile strength is less reduced when the negative electrode active material is supported, so that charging is performed. Expansion during discharge. High resistance to shrinkage can make battery life longer.

Therefore, the electrodeposited copper foil can be a surface-treated copper foil which is subjected to roughening treatment and rust-preventing treatment depending on the application, and can be widely used in the fields of printed wiring boards, lithium ion secondary batteries, and the like.

In addition, in the method for producing an electrolytic copper foil of the present application, a simple bath composition can be used as compared with the sulfuric acid acidic copper electrolyte used in the production of the electrolytic copper foil in the past, so that the solution has excellent stability and can reduce the waste liquid treatment. Load, so the bath when making electrolytic copper foil Reductions in management and management costs have become easier.

Hereinafter, the "form of electrolytic copper foil", "the form of production of electrolytic copper foil", and "the form of surface-treated copper foil obtained by using electrolytic copper foil" will be described in order.

The form of the electrolytic copper foil is a copper foil which is not subjected to surface treatment such as rustproof treatment or roughening treatment, and the thickness thereof is not particularly limited. Further, it is clearly shown here in advance that the electrolytic copper foil of the present application described below is specified by physical properties. The value of the physical property shows almost the same value between the "electrolytic copper foil" and the "surface-treated copper foil" subjected to surface treatment described later.

The electrolytic copper foil of the present application is characterized by the physical properties of "normal tensile strength of 600 MPa or more" and "tensile strength after heating at 350 ° C for 1 hour" of 470 MPa or more. Such an electrolytic copper foil having a "normal tensile strength of 600 MPa or more" has existed in the past. However, the electrolytic copper foil which exhibits the physical properties of "350 ° C × 1 hour heating and tensile strength of 470 MPa or more" does not exist. In order to obtain the electrolytic copper foil having the physical properties of "350 ° C × 1 hour heating and tensile strength of 470 MPa or more", an electrolytic copper foil having a physical property of "normal tensile strength of 600 MPa or more" is used.

When the electrolytic copper foil is "normal tensile strength of 600 MPa or more", even if the thickness of the electrolytic copper foil having a thickness of 9 μm or less, wrinkles are less likely to occur during the treatment, and the work is improved. Industry is better. Therefore, when an electrolytic copper foil having a physical property of "350 ° C × 1 hour heating and a tensile strength of 470 MPa or more" is used as a negative electrode current collector of a lithium ion secondary battery, high-quality lithium having a long battery life can be provided. Ion secondary batteries are therefore preferred. When the electrodeposited copper foil having the above physical properties is used for the negative electrode current collector, the polymerization reaction of the binder is carried out at a temperature of 300 ° C or higher in order to support the alloy-based negative electrode active material, and the strength of the electrolytic copper foil is reduced. . Further, the "tensile strength after heating at 350 ° C for 1 hour" is more preferably "the tensile strength after heating at 350 ° C for 1 hour exceeds 500 MPa". This is because even if the heat treatment time takes a long time, it can have a stable high tensile strength. Further, in the case of the electrolytic copper foil having the above-described high-temperature heat-resistant property, a negative electrode current collector having a small thickness can be designed.

Further, the electrolytic copper foil of the present application preferably has a "0.2% proof stress of 370 MPa or more after heating at 350 ° C for 1 hour". When a copper foil having copper as a main component of non-ferrous material is used as a main component, there is no drop point as seen in the iron material in the stress-strain curve. Therefore, when performing an objective evaluation as a non-ferrous material, "0.2% endurance" is used instead of the fall point. Further, the "0.2% proof endurance" and the above "tensile strength" are not completely related, but when the value of 0.2% stamina is high, the tensile strength tends to be high. When the 0.2% proof stress after heating at 350 ° C for 1 hour is 370 MPa or more, the variation in tensile strength of the electrodeposited copper foil after heating tends to be small, and the above-mentioned "350 ° C × 1 hour heating can be stably obtained. The tensile strength is 470 MPa or more. According to this, in the case of the electrolytic copper foil of the present application, the "heating resistance after 0.2%" and "tensile strength after heating" are separately evaluated as individual indexes, and the high-temperature heat-resistant property to heating can be obtained. Evaluation becomes more certain. Hereinafter, the electrolytic copper foil of the present application when a more severe high temperature load is applied is shown. High temperature heat resistance characteristics are described. Further, the electrolytic copper foil of the present application is more preferably "0.2% endurance after heating at 350 ° C for 1 hour is 410 MPa or more". The reason for this is that the above-mentioned tensile strength after heating at 350 ° C for 1 hour is more than 500 MPa.

Further, even if a high-temperature load of 350 ° C × 4 hours is applied, the electrolytic copper foil of the present application preferably has a tensile strength of "the tensile strength after heating at 350 ° C for 4 hours is 470 MPa or more". Further, in the case of the electrolytic copper foil of the present application, it is preferable to have a high tensile strength of "350 ° C × 4 hours of tensile strength after heating of 500 MPa or more". Further, the electrodeposited copper foil of the present application preferably has a high 0.2% proof resistance of "350% C × 0.2% after-heating of 370 MPa or more after heating for 4 hours". Further, in the case of the electrolytic copper foil of the present application, it is preferable to have a high 0.2% proof stress of "0.2% endurance after heating at 350 ° C for 4 hours" of 410 MPa or more.

Further, the normal elongation of the electrolytic copper foil of the present application is preferably 2.5% or more. When the normal elongation is less than 2.5%, the electrolytic copper foil may be broken when a mixture layer containing a negative electrode active material is formed on the surface of the electrolytic copper foil.

The physical properties of the electrolytic copper foil of the present application as described above are considered to be obtained by the trace components contained in the electrolytic copper foil. Further, the content of the trace component of the electrolytic copper foil of the present application as the content per unit mass of the electrolytic copper foil preferably satisfies the following conditions. That is, the C content is 100 μg/g to 450 μg/g (meaning "100 μg/g or more and 450 μg/g or less", the same applies hereinafter), the N content is 50 μg/g to 620 μg/g, and the O content is 400 μg/g. 3200μg/g, S content is 110μg/g~720μg/g, Cl content is in the range of 20μg/g~115μg/g, and it satisfies the quality of {Cl/(C+N+O+S+Cl)}×100≦5 The relationship between %. If the condition of the trace component content is not satisfied, the crystal structure of the electrolytic copper foil is recrystallized due to the high temperature load. The progress is remarkable, and it is easy to cause voids in the crystal structure. Moreover, since the content of the trace component in the present invention is expressed as the content per 1 g of the copper foil, the unit of "μg/g" is used. The value of Cl content (μg/g) contained in the {Cl/(C+N+O+S+Cl)}×100 electrolytic copper foil is divided by the C (carbon) content contained in the electrolytic copper foil, N The value of the total amount (μg/g) of the (nitrogen) content, the O (oxygen) content, the S (sulfur) content, and the Cl (chlorine) content, and multiplied by 100 to obtain a percentage conversion value (% by mass).

Further, the ratio of the minor component of N (nitrogen) contained in the electrolytic copper foil of the present application satisfies the relationship of {N/(N+S+Cl)}×100≧20% by mass. When this relationship is not satisfied, the recrystallization of the crystal structure of the electrolytic copper foil is remarkably progressed due to the high temperature load, and it is easy to cause voids in the crystal structure. By heating at 350 ° C for 1 hour or more, there is a tendency that the deviation between the tensile strength and the 0.2% endurance becomes large. Further, the value of the N content (μg/g) contained in the {N/(N+S+Cl)}×100 electrolytic copper foil is divided by the total amount of the C content, the S content, and the Cl content contained in the electrolytic copper foil ( The value of μg/g) is multiplied by the percentage conversion value (% by mass) obtained by 100.

Further, the ratio of the trace component of Cl (chlorine) contained in the electrolytic copper foil of the present application satisfies the relationship of {Cl / (N + S + Cl) × 100 ≦ 20% by mass. When the value exceeds 20% by mass, the recrystallization of the crystal structure of the electrolytic copper foil is remarkably progressed due to the high temperature load, and pores are likely to be generated in the crystal structure. The value is not particularly limited, but the lower limit is considered to be 3.0% by mass. When it is less than 3.0% by mass, the deviation between the tensile strength and the 0.2% proof strength tends to increase. Further, {Cl/(N+S+Cl)}×100 is the value of the Cl content (μg/g) contained in the electrolytic copper foil divided by the total of the N content, the S content, and the Cl content contained in the electrolytic copper foil. The value of the amount (μg/g) is multiplied by 100 to obtain a percentage conversion value (% by mass).

Production method of electrolytic copper foil: The method for producing an electrolytic copper foil according to the present application is a method for producing the above-mentioned electrolytic copper foil, which is characterized by using "from 20 mg/L to 100 mg/L. A copper acid electrolyte having a concentration of 10,000 to 70,000 polyethyleneimine and a chlorine concentration of 0.5 mg/L to 2.5 mg/L as a copper electrolyte. Further, the copper concentration and the free sulfuric acid concentration of the "sulfuric acid copper electrolytic solution" are not particularly limited, but generally, the copper concentration is 70 g/L to 90 g/L, and the free sulfuric acid concentration is in the range of 100 g/L to 200 g/L.

The polyethyleneimine used in the method for producing an electrolytic copper foil of the present application is a molecular weight of a primary amine, a secondary amine, and a tertiary amine of 10,000 to 70,000 (trade name Epomin manufactured by Nippon Shokubai Co., Ltd.) -200, P-1000), etc.). Further, the polyethyleneimine is used by being added to a sulfuric acid copper electrolytic solution used for the production of an electrolytic copper foil. The sulfuric acid-based copper electrolytic solution containing the above polyethyleneimine is excellent in solution stability and excellent in solution stability during electrolysis, and is therefore suitable for the production of electrolytic copper foil which requires continuous electrolysis for a long period of time. Further, the electrolytic copper foil obtained by using a sulfuric acid-based copper electrolytic solution to which polyethyleneimine is added has a tendency to be stabilized by high-temperature heat-resistant characteristics. When the molecular weight of the polyethyleneimine is less than 10,000, even if the addition amount of the polyethyleneimine is increased, the obtained electrolytic copper foil cannot be provided with sufficient high-temperature heat resistance characteristics, which is not preferable. On the other hand, even if the molecular weight of the polyethyleneimine is more than 70,000, the tendency of the high-temperature heat resistance of the obtained electrolytic copper foil to become large is not preferable. The structural formula of the polyethyleneimine is shown in the following paragraph 1.

1.

Further, the polyethyleneimine preferably has a concentration of from 20 mg/L to 100 mg/L in the sulfuric acid acidic copper electrolyte. When the polyethyleneimine concentration is less than 20 mg/L, the obtained electrolytic copper foil cannot be provided with sufficient high-temperature heat resistance characteristics, which is not preferable. on the other hand. When the polyethyleneimine concentration exceeds 100 mg/L, the content of the above-mentioned trace component contained in the electrolytic copper foil tends to be excessive, and even if the tensile strength and the 0.2% proof strength of the electrolytic copper foil are increased, the elongation is hardened and the elongation is increased. The rate is falling, so it is not good.

Further, the chlorine concentration of the sulfuric acid copper electrolytic solution used in the method for producing an electrolytic copper foil of the present application is preferably from 0.5 mg/L to 2.5 mg/L. When the chlorine concentration is less than 0.5 mg/L, the normal tensile strength is high, but the high-temperature heat resistance is remarkably lowered, which is not preferable. On the other hand, when the chlorine concentration exceeds 2.5 mg/L, the normal tensile strength and the high-temperature heat resistance are both lowered, which is not preferable.

As for other production conditions, it is preferred to carry out electrolysis in the range of a current density of 40 A/dm 2 to 90 A/dm 2 and a liquid temperature of 40 ° C to 55 ° C at the time of production of the electrolytic copper foil. If it is within the range of the electrolysis conditions, it can be stably electrolyzed or a high-quality electrolytic copper foil can be produced.

Shape of surface treated copper foil: characteristics of surface treated copper foil of this application It is obtained by using the above-mentioned electrolytic copper foil of this application. Here, the surface treatment is a chemical adhesion improving treatment such as a roughening treatment, a rustproof treatment, or a decane coupling agent treatment. There is no particular limitation on the method and type of roughening treatment at this time. For example, a method in which fine particles such as copper, a copper alloy, nickel, or a nickel alloy are adhered to the surface of a copper foil, and a surface of the copper foil is etched to form a fine uneven shape can be used.

Further, as the rust-preventing treatment, any rust-preventing treatment may be used as long as the rust-preventing effect is obtained by coating, adhering, or depositing the surface of the electrolytic copper foil. For example, an organic rustproof treatment (treatment using benzotriazole, imidazole, etc.) or an inorganic rustproof treatment (treatment using zinc, a zinc alloy, a nickel alloy, or the like) can be used. In the case of the inorganic rust-preventing treatment, the rust prevention described in the specification of the international application (International Publication No. WO2012/070589, International Publication No. WO2012/070591) filed by the applicant of the present application is also preferably applied. deal with. The reason for this is that when the rust-preventing treatment described in the above is employed, the high-temperature heat-resistant property shown in the case of electrolytic copper foil can be further improved. In addition, the chemical adhesion improving treatment such as the treatment of the decane coupling agent is not particularly limited, and the properties of the constituent resin of the substrate to be surface-treated with the copper foil of the present application or the negative electrode of the lithium ion secondary battery are used. The properties of the active material and the binder may be selected from conventional decane coupling agents.

Hereinafter, the examples and comparative examples will be exemplified, and the high-temperature heat-resistant characteristics of the electrolytic copper foil of the present application will be described while comparing the examples.

[Example 1]

In Example 1, a copper acid electrolyte having a copper concentration of 80 g/L, a free sulfuric acid concentration of 140 g/L, a molecular weight of 70,000 and a polyethylenimine concentration of 55 mg/L, and a chlorine concentration of 2.2 mg/L was used as a current. The density is 70A/dm2, and the liquid temperature is 50°C. Solution, a 15 μm thick electrolytic copper foil was obtained. The evaluation results of the electrolytic copper foil are shown in the following Tables 2 to 4 in a manner comparable to the comparative examples.

[Example 2 to Example 10]

With respect to Examples 2 to 10, since the composition of the sulfuric acid-only copper electrolyte was different from that of Example 1, the composition of the individual sulfuric acid-based copper electrolyte was summarized in Table 1. Further, the evaluation results of the electrolytic copper foil obtained in each of the examples are shown in the following Tables 2 to 4 in a manner comparable to the comparative examples.

[Comparative Example 1 to Comparative Example 7]

Comparative Example 1 to Comparative Example 7 Using the same copper concentration and free sulfuric acid concentration as in Example 1, electrolysis was carried out under the same conditions as in Example 1 using the sulfuric acid acidic copper electrolyte having the composition shown in Table 1, to obtain a 15 μm thick layer. Electrolytic copper foil.

[Comparative Example 8]

In Comparative Example 8, the sulfuric acid copper electrolytic solution described in Example 6 of Patent Document 1 was used, and electrolysis was carried out under the conditions of a current density of 40 A/dm 2 and a liquid temperature of 50 ° C to obtain an electrolytic copper foil having a thickness of 15 μm.

[Comparative Example 9]

In Comparative Example 9, the sulfuric acid-based copper electrolytic solution described in Example 5 of Patent Document 3 was used, and electrolysis was carried out under the conditions of a current density of 40 A/dm 2 and a liquid temperature of 40 ° C to obtain an electrolytic copper foil having a thickness of 15 μm.

[Comparative Example 10]

In Comparative Example 10, the sulfuric acid-based copper electrolytic solution for obtaining the sample 8 described in the Example of the above Patent Document 6 was used, and the current density was 60 A/dm 2 and the liquid temperature was 50 ° C. Electrolysis was carried out under conditions to obtain an electrolytic copper foil having a thickness of 15 μm.

[Comparative Example 11]

In Comparative Example 11, the sulfuric acid-based copper electrolytic solution for obtaining the sample 1 described in the above-mentioned Patent Document 8 was used, and electrolysis was carried out under the conditions of a solution temperature of 50 ° C and a current density of 75 A/dm 2 to obtain an electrolytic copper foil having a thickness of 15 μm. .

[Comparative Example 12]

In Comparative Example 12, the sulfuric acid copper electrolytic solution for obtaining the sample 4 described in the above Patent Document 8 was used, and electrolysis was carried out under the conditions of a solution temperature of 50 ° C and a current density of 75 A/dm 2 to obtain an electrolytic copper foil having a thickness of 15 μm. .

[Comparative Example 13]

Comparative Example 13 used an electrolytic copper foil having a thickness of 15 μm used in the production of a VLP copper foil manufactured by Mitsui Mining Co., Ltd.

[Evaluation method]

Content of trace components in the electrolytic copper foil: The O content and the N content in the electrolytic copper foil were measured by using EMGA-620 of Horiba Co., Ltd. after removing the oxide on the surface of the copper foil with dilute nitric acid. At this time, the O content was measured by "inert gas dissolution-dispersion type infrared absorption method (NDIR)", and the N content was measured by "inert gas dissolution-heat transfer method (TCD)". Further, in the electrolytic copper foil, the C content and the S content are obtained by removing the oxide on the surface of the copper foil with dilute nitric acid, and using the EMIA-920V of Horiba Co., Ltd. as "the high frequency heating in the oxygen flow - the infrared absorption method" Take the measurement.

Moreover, the Cl content in the electrolytic copper foil is coprecipitation-ion chromatography with silver bromide The method is measured. The specific measurement method is as follows. The electrolytic copper foil is dissolved by heating with nitric acid, and a certain amount of silver nitrate is added. Next, a certain amount of KBr solution was added to coprecipitate the chloride ions together with the silver bromide. Subsequently, after standing for 15 minutes in the dark, the precipitate was filtered, and the precipitate was washed. Subsequently, the precipitate was placed in a beaker, the precipitate was dissolved in a thiourea solution, and placed in the dark overnight. Subsequently, the solution was diluted and made up to volume, and the chloride ion concentration was determined by ion chromatography using an ICS-2000 conductivity detector (dissolved KOH, column AS-20) manufactured by Dionex Corporation to calculate the Cl content. .

Tensile strength, 0.2% proof stress, and elongation: The electrolytic copper foil obtained in the examples and the comparative examples was cut into a strip having a length of 10 cm and a width of 1 cm, and used as a sample for measurement such as tensile strength. Next, tensile strength, 0.2% proof stress, and elongation were measured using an Instron type tensile tester (Instron strength tester).

Heating conditions of the sample: short strips used in the measurement of heating tensile strength at various temperatures of 300 ° C × 1 hour, 350 ° C × 1 hour, 350 ° C × 4 hours in a heating oven under an inert gas atmosphere The sample was cooled to a temperature close to room temperature to obtain a sample after heating. Using the thus-heated short strip sample, tensile strength, 0.2% proof stress, and elongation were measured in the same manner as above.

[Comparative Example vs. Comparative Example]

When the comparison between the examples and the comparative examples was carried out, the blending of the additives contained in the sulfuric acid-based copper electrolytes of the examples and the comparative examples was shown in Table 1 in such a manner as to be easily compared.

As understood from the Table 1, the examples are suitable for the method for producing an electrolytic copper foil according to the present application. The acidic copper acid electrolyte is "the molecular weight of 10,000 to 70,000 at a concentration of 20 mg/L to 100 mg/L. The two requirements of polyethyleneimine and "chlorine concentration is 0.5mg/L~2.5mg/L". On the other hand, it is understood that the comparative example does not satisfy the additive requirement of an appropriate sulfuric acid copper electrolytic solution in the method for producing an electrolytic copper foil of the present application, or the use of a sulfuric acid acidic copper electrolyte containing a completely different additive. Further, the contents of the trace components contained in each of the electrolytic copper foils obtained in the examples and the comparative examples are shown in Table 2 below.

From the viewpoint of the content of the trace component contained in the electrodeposited copper foil of the example and the comparative example, it can be understood as follows. It can be understood from Table 2 that all the electrolytic copper foils of the examples satisfy the conditions of the trace component contents (C content, N content, O content, S content, Cl content) and the composition ratio of the trace components. On the other hand, it is understood that the electrolytic copper foil of the comparative example does not satisfy any of the conditions of the content of the trace component or the composition ratio of the minor component.

Further, Comparative Example 1 of Table 2 did not satisfy the conditions of the trace component content, but satisfied the conditions of the chlorine composition ratio. Further, when Comparative Example 3 and Comparative Example 6 were examined, it was found that the conditions of the trace component content were satisfied, but the conditions for the chlorine composition ratio were not satisfied. The electrolytic copper foil obtained in the above comparative examples is a product which does not have good high-temperature heat resistance as will be described later. From this, it can be understood that the electrolytic copper foil having excellent high-temperature heat resistance characteristics cannot be obtained if both the composition ratio of the minor component other than the chlorine contained in the electrolytic copper foil and the condition of the chlorine constituent ratio are not satisfied.

In addition, when the ratio of nitrogen to chlorine as a trace component is considered as a reference, the difference between the electrolytic copper foils of the examples and the comparative examples is clear. The ratio of the trace component of nitrogen at this time is a value of {N/(N+S+Cl)}×100, and the ratio of the trace component of chlorine is a value of {Cl/(N+S+Cl)}×100. The ratios of the trace components of nitrogen and chlorine contained in each of the electrolytic copper foils obtained in the examples and the comparative examples are shown in Table 3 below.

The ratio of the trace components in the electrolytic copper foil shown in Table 3 can be understood as follows. First, when the value of {N/(N+S+Cl)}×100 is examined, the examples are from 20.3 mass% to 45.8% by mass, and the comparative examples are from 6.2 mass% to 27.3 mass%, although there are some overlapping ranges, It will be appreciated that embodiments have a tendency to display larger values. Further, all of the examples satisfy the relationship of {N/(N + S + Cl)} × 100 ≧ 20 value %, but the case of the comparative example sees that most of the relationship is not satisfied. Accordingly, it is better to have an electrolytic copper foil having good high temperature and heat resistance characteristics. The trace component satisfies the relationship of {N/(N+S+Cl)}×100≧20% by mass.

Next, when the value of {Cl/(N+S+Cl)}×100 shown in Table 3 is examined, the examples are 3.0% by mass to 15.9% by mass, and the comparative examples are 7.1% by mass to 86.2% by mass, although there are The extent of partial repetition, but it is understood that the comparative example has a tendency to show larger values. Further, all of the examples satisfy the relationship of {Cl / (N + S + Cl)} × 100 ≦ 20% by mass, but in the case of the comparative example, most of the relationships are not satisfied. Here, the electrolytic copper foil of Comparative Example 1, Comparative Example 2, and Comparative Example 7 in which the chlorine concentration is less than the lower limit of the composition range of the preferred sulfuric acid-based copper electrolytic solution in the present application or the upper limit is as follows. , for those who do not have good high temperature heat resistance. Therefore, it can be understood that the electrolytic copper foil satisfies the above values of "{Cl/(C+N+S+Cl)}×100" and "{N/(N+S+Cl)}×100", and further, The value of {Cl/(N+S+Cl)}×100" is in the proper range and is the most stable and has high temperature and heat resistance characteristics.

Hereinafter, physical properties of the electrolytic copper foil of the examples and the electrolytic copper foil of the comparative example will be described. This physical property is shown in Table 4 in such a manner that the comparison of the examples and the comparative examples is easier.

The normal tensile strength and 0.2% proof force shown in Table 4 are described. In the case of the electrolytic copper foil of the example, the normal tensile strength is 610 MPa to 774 MPa, and the normal 0.2% endurance is 442 MPa to 574 MPa. On the other hand, in the case of the comparative example, the normal tensile strength was 395 MPa to 791 MPa, and the normal 0.2% proof stress was 358 MPa to 510 MPa. Accordingly, it is understood that the electrolytic copper foil of the embodiment satisfies the condition of "normal tensile strength of 600 MPa or more".

Next, the tensile strength after heating at 300 ° C × 1 hour shown in Table 4 and 0.2% proof stress are described. In the case of the electrolytic copper foil of the example, the tensile strength after heating at 300 ° C for 1 hour was 502 MPa to 613 MPa, and the 0.2% endurance after heating at 300 ° C for 1 hour was 384 MPa to 460 MPa. On the other hand, in the case of the comparative example, the tensile strength after heating at 300 ° C for 1 hour was 162 MPa to 538 MPa, and the 0.2% resistance after heating at 300 ° C for 1 hour was 118 MPa to 396 MPa. From this, it can be seen that even after heating at 300 ° C for 1 hour, the examples showed higher values than the comparative examples. For example, in the comparative example, Comparative Example 10 which showed the highest physical properties under normal conditions rapidly decreased the tensile strength after heating at 300 ° C for 1 hour to 199 MPa, and the 0.2% endurance after heating at 300 ° C × 1 hour was also sharply lowered. Up to 179 MPa, it can be understood that it cannot be said to be an electrolytic copper foil which exhibits good high-temperature heat resistance. However, in more detail, in the case of Comparative Example 12, it was shown that "the tensile strength after heating at 300 ° C for 1 hour was 500 MPa or more" and "0.2% withstand resistance after heating at 300 ° C for 1 hour was 380 MPa or more". High temperature heat resistance characteristics equivalent to those of the examples.

However, in view of the tensile strength after heating at 350 ° C for 1 hour shown in Table 4 and the 0.2% proof stress, it is understood that the high temperature resistance of the electrolytic copper foil of the example is compared with the comparative example. The thermal characteristics are greatly won. In the case of the electrolytic copper foil of the example, the tensile strength after heating at 350 ° C for 1 hour was 473 MPa to 583 MPa, and the 0.2% resistance after heating at 350 ° C for 1 hour was 371 MPa to 446 MPa. On the other hand, in the case of the comparative example, the tensile strength after heating at 350 ° C for 1 hour was 71 MPa to 455 MPa, and the 0.2% resistance after heating at 350 ° C for 1 hour was 64 MPa to 359 MPa. From this, it can be seen that the tensile strength and the 0.2% endurance after heating at 350 ° C for 1 hour were significantly higher than those of the comparative examples. That is, it can be understood that the electrolytic copper foil of the embodiment can withstand heating at a higher temperature than the comparative example, and the superiority with respect to the electrolytic copper foil of the past becomes remarkable. When the tensile strength and the 0.2% proof stress after heating at 300 ° C for 1 hour were observed, when Comparative Example 4, Comparative Example 5, Comparative Example 11 and Comparative Example 12 having the same characteristics as those of the Examples were observed, after heating at 350 ° C for 1 hour, The tensile strength was reduced to 455 MPa or less, and the 0.2% endurance was reduced to 359 MPa or less. It is also clear that the case of the comparative example does not satisfy the condition that "the tensile strength after heating at 350 ° C for 1 hour is 470 MPa or more".

Hereinafter, as an example of the load of more heat, the tensile strength after heating at 350 ° C for 4 hours and the 0.2% proof stress will be briefly described. In the heating test, the electrolytic copper foils of Example 8 and Example 10 were used. As a result, in the case of the electrolytic copper foil of Example 8, the tensile strength after heating at 350 ° C for 4 hours was 533 MPa, and the 0.2% proof after heating at 350 ° C for 4 hours was 416 MPa, and the elongation after heating was 350 ° C × 4 hours. The rate shows a value of 2.2%. Further, in the case of the electrolytic copper foil of Example 10, the tensile strength after heating at 350 ° C for 4 hours was 520 MPa, the 0.2% endurance after heating at 350 ° C × 4 hours was 423 MPa, and the elongation after heating at 350 ° C × 4 hours Showing a value of 1.7%. This value is considered to be a very harsh value after being subjected to extremely severe heating. Accordingly, according to the electrolytic copper foil of the present application, It satisfies two conditions of "the tensile strength after heating at 350 ° C for 4 hours is 470 MPa or more" and "the 0.2% resistance after heating at 350 ° C for 4 hours is 370 MPa or more".

[Industrial availability]

The electrolytic copper foil of the present application described above has physical properties of "normal tensile strength of 600 MPa or more" and "tensile strength of 350 ° C for 1 hour and heating of 470 MPa or more". According to this, even a thin electrolytic copper foil has less wrinkles and good handling characteristics. Therefore, the above-mentioned electrodeposited copper foil has excellent high-temperature heat resistance even under high-temperature load, and can be preferably used in a field of printed wiring boards, lithium ion secondary batteries, and the like as a surface-treated copper foil which is subjected to various surface treatments as necessary. . Further, the method for producing an electrolytic copper foil of the present application is to change only the sulfuric acid-based copper electrolytic solution of the electrolytic copper foil, and since the manufacturing equipment of the electrolytic copper foil of the past can be directly used, it is not necessary to invest in new equipment. Preferably.

Claims (6)

An electrolytic copper foil characterized in that the normal tensile strength is 600 MPa or more, and the tensile strength after heating at 350 ° C for 1 hour is 470 MPa or more. The electrolytic copper foil according to claim 1, which has a 0.2% proof stress of 370 MPa or more after heating at 350 ° C for 1 hour. The electrolytic copper foil according to claim 1 has a normal elongation of 2.5% or more. The electrolytic copper foil according to claim 1, wherein the C content is 100 μg/g to 450 μg/g, the N content is 50 μg/g to 620 μg/g, and the O content is 400 μg/g as a trace component contained in the electrolytic copper foil. 3200μg/g, S content is 110μg/g~720μg/g, Cl content is 20μg/g~115μg/g, and the following relationship is satisfied: {Cl/(C+N+O+S+Cl)}×100≦5 quality%. A method for producing an electrolytic copper foil, which is a method for producing an electrolytic copper foil according to claim 1, which is characterized in that a polyethyleneimine having a molecular weight of 10,000 to 70,000 is used at a concentration of 20 mg/L to 100 mg/L, and a chlorine concentration is used. A sulfuric acid acidic copper electrolyte of 0.5 mg/L to 2.5 mg/L is used as the copper electrolyte. A surface-treated copper foil characterized by using the electrolytic copper foil of claim 1.