Method for preventing end face of electrolytic copper foil from discoloring

Abstract

The invention belongs to the technical field of electrolytic copper foils, and provides a method for preventing the end face of an electrolytic copper foil from discoloring. The method comprises the step of sequentially coating the end face of the electrolytic copper foil with antioxidant liquid and silane coupling liquid. According to the method, dual treatment of the antioxidant liquid and the silane coupling liquid is adopted, efficient antioxidant protection is conducted on the end face of the electrolytic copper foil, and the end face of the electrolytic copper foil is prevented from being oxidized and discolored; rare earth salt is added into the anti-oxidation liquid, rare earth elements have a synergistic effect with organic sugar, citric acid and hyaluronic acid and interact with copper in the end face, an organic-inorganic composite film layer is formed, and the anti-oxidation effect is remarkably improved. The silane coupling liquid can form an organosilane film on the end face of the electrolytic copper foil, the end face of the electrolytic copper foil is effectively protected, and the end face of the electrolytic copper foil is prevented from being oxidized and discolored; and end face scratching is avoided, and the preservation time of the electrolytic copper foil product after slitting is prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrolytic copper foil, and particularly relates to a method for preventing end surface discoloration of electrolytic copper foil. BACKGROUND

[0002] The manufacturing process of electrolytic copper foil mainly includes three steps: electrolyte preparation, electrolytic foil production and product slitting. Surface treatment is generally located in the electrolytic foil production stage, and the purpose is to form a passivation film on the surface of the electrolytic copper foil to prevent the electrolytic copper foil from contacting air and to prevent the electrolytic copper foil from being oxidized and discolored. At present, the research on the oxidation resistance of electrolytic copper foil mainly focuses on the electrolyte preparation and electrolytic foil production stages. For example, an oxidation-resistant additive is added to the electrolyte, the oxidation-resistant additive directly acts on the process of electrodeposited copper, refines the grains and increases the oxidation resistance of the electrolytic copper foil; the electrolytic foil is subjected to surface treatment, including roughening, passivation and silane coupling.

[0003] However, according to the use requirements of customers for the electrolytic copper foil, such as size, the electrolytic copper foil needs to be slitted, and two end surfaces will be generated after slitting. The end surfaces are not subjected to surface treatment and are directly exposed to air, and the end surfaces are prone to be oxidized and discolored in the actual storage process, which will affect the product quality of the electrolytic copper foil. At present, the main means for preventing oxidation of the end surface of the electrolytic copper foil is to wipe the oxidation-resistant liquid. Chinese patent CN112921311A discloses a method for preventing end surface discoloration of electrolytic copper foil, and the oxidation-resistant liquid contains chromic anhydride, zinc sulfate, potassium sulfate, an antioxidant, a copper corrosion inhibitor and an organic monosaccharide; Chinese patent CN110952099A discloses an antioxidant containing sodium sulfate, sodium chromate, ascorbic acid solution and silane coupling agent. However, the above prior art has many problems. On the one hand, there are heavy metals such as chromium, which do not meet the environmental protection concept; on the other hand, the oxidation resistance effect is poor, which is not conducive to the long-term storage of the electrolytic copper foil after slitting, and sometimes end surface scratches and other damage phenomena occur.

[0004] Therefore, it is very important to provide a chromium-free and efficient method for preventing end surface discoloration of electrolytic copper foil to meet the use requirements of electrolytic copper foil. SUMMARY

[0005] The present application aims at providing a method for preventing end surface discoloration of electrolytic copper foil to solve the problems of the prior art.

[0006] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0007] The present application provides a method for preventing end surface discoloration of electrolytic copper foil, in which an oxidation-resistant liquid and a silane coupling liquid are sequentially applied to the end surface of the electrolytic copper foil.

[0008] Preferably, the oxidation-resistant liquid contains citric acid, rare earth sulfate, hyaluronic acid, organic sugar, polyethylene glycol and water.

[0009] Preferably, the rare earth sulfate comprises one or more of cerium sulfate, ytterbium sulfate and lanthanum sulfate.

[0010] The organic sugar comprises glucose and / or fructose.

[0011] Preferably, in the antioxidant solution, the concentration of citric acid is 1-5 g / L, the concentration of rare earth sulfate is 0.1-0.8 g / L, the concentration of hyaluronic acid is 5-15 g / L, and the concentration of organic sugar is 3-8 g / L, and the concentration of polyethylene glycol is 5-12 g / L.

[0012] Preferably, the silane coupling solution comprises nano-silicon sol, silane coupling agent and solvent.

[0013] Preferably, in the silane coupling solution, the concentration of nano-silicon sol is 0.5-2 g / L, and the concentration of silane coupling agent is 2-6 g / L.

[0014] Preferably, the solvent is an alcohol-water mixture, and the alcohol in the alcohol-water mixture comprises one or more of anhydrous ethanol, methanol and isopropyl alcohol.

[0015] The volume ratio of alcohol to water in the alcohol-water mixture is 5-8:1.

[0016] Preferably, the coating is wiping or spraying.

[0017] Preferably, a pressure roller is abutted against the outer surface of the electrolytic copper foil, and the tube core of the electrolytic copper foil is synchronously rotated with the pressure roller during the coating.

[0018] The present application has the following advantages:

[0019] The present application adopts the double treatment of the antioxidant solution and the silane coupling solution to efficiently protect the end face of the electrolytic copper foil from oxidation and discoloration. The rare earth salt in the antioxidant solution cooperates with the organic sugar, citric acid and hyaluronic acid to interact with copper in the end face, forming an organic-inorganic composite film layer and significantly improving the antioxidant effect. The silane coupling solution can form a silicon alkane film on the end face of the electrolytic copper foil to effectively protect the end face of the electrolytic copper foil from oxidation and discoloration. By abutting the pressure roller, the tube core of the electrolytic copper foil is synchronously rotated with the pressure roller during the coating, avoiding the end face from being scratched and preventing the antioxidant solution and the silane coupling solution from being immersed into the electrolytic copper foil, thereby prolonging the storage time of the electrolytic copper foil after being cut. DETAILED DESCRIPTION

[0020] The present application provides a method for preventing the end face of an electrolytic copper foil from discoloring, in which an antioxidant solution and a silane coupling solution are sequentially coated on the end face of the electrolytic copper foil.

[0021] In the present application, the antioxidant solution preferably comprises citric acid, rare earth sulfate, hyaluronic acid, organic sugar, polyethylene glycol and water. The rare earth sulfate performs surface treatment and filling on the end face, and synergizes with citric acid, hyaluronic acid and organic sugar, to form an organic-inorganic composite film layer on the end face of the electrolytic copper foil through the combination of organic polymer and rare earth inorganic salt, so that the electrolytic copper foil is not easy to be oxidized and discolored in the air.

[0022] In the present application, the rare earth sulfate preferably comprises one or more of cerium sulfate, ytterbium sulfate and lanthanum sulfate.

[0023] The organic sugar preferably comprises glucose and / or fructose.

[0024] In the present application, the hyaluronic acid preferably comprises high molecular weight hyaluronic acid, medium molecular weight hyaluronic acid and low molecular weight hyaluronic acid.

[0025] The molecular weight of the high molecular weight hyaluronic acid is preferably 300x10 4 ~ 500x10 4 , further preferably 350x10 4 ~ 450x10 4 ; the molecular weight of the medium molecular weight hyaluronic acid is preferably 50x10 4 ~ 100x10 4 , further preferably 70x10 4 ~ 90x10 4 ; and the molecular weight of the low molecular weight hyaluronic acid is preferably 5x10 4 ~ 10x10 4 , further preferably 7x10 4 ~ 8x10 4 . The combination of high molecular weight, medium molecular weight and low molecular weight hyaluronic acid promotes the interaction of hyaluronic acid with citric acid, organic sugar and rare earth sulfate.

[0026] In the present application, the concentration of citric acid in the antioxidant solution is preferably 1-5 g / L, further preferably 2-4 g / L, and more preferably 3 g / L; the concentration of rare earth sulfate is preferably 0.1-0.8 g / L, further preferably 0.3-0.6 g / L, and more preferably 0.4-0.5 g / L; the concentration of hyaluronic acid is preferably 5-15 g / L, further preferably 7-12 g / L, and more preferably 10 g / L; the concentration of organic sugar is preferably 3-8 g / L, further preferably 4-7 g / L, and more preferably 5-6 g / L; and the concentration of polyethylene glycol is preferably 5-12 g / L, further preferably 7-10 g / L, and more preferably 8-9 g / L.

[0027] In the present application, the silane coupling liquid preferably comprises nanometer silicon sol, silane coupling agent and solvent. The nanometer silicon sol and the silane coupling agent jointly act on the end face of the electrolytic copper foil, form a protective film on the end face of the electrolytic copper foil, protect the end face, and effectively prevent oxidation discoloration.

[0028] In the present application, the silane coupling agent preferably comprises silane coupling agent KH550 and / or silane coupling agent KH560.

[0029] In the present application, the mass content of SiO2 in the nanometer silicon sol is preferably 20-30%, and further preferably 25%.

[0030] In the present application, in the silane coupling liquid, the concentration of the nanometer silicon sol is preferably 0.5-2 g / L, and further preferably 1-1.5 g / L; the concentration of the silane coupling agent is preferably 2-6 g / L, and further preferably 3-5 g / L, and more preferably 4 g / L.

[0031] In the present application, the solvent is preferably an alcohol-water mixture, and the alcohol in the alcohol-water mixture preferably comprises one or more of anhydrous ethanol, methanol and isopropyl alcohol.

[0032] The volume ratio of alcohol to water in the alcohol-water mixture is preferably 5-8:1, and further preferably 6-7:1, and more preferably 6.5:1.

[0033] In the present application, the coating is preferably wiping or spraying.

[0034] In the present application, the pressure roller is preferably abutted against the outer surface of the electrolytic copper foil, and the tube core of the electrolytic copper foil is preferably synchronously rotated with the pressure roller during the coating.

[0035] The technical solutions provided by the present application will be described in detail below in conjunction with the embodiments, but they should not be understood as limiting the scope of protection of the present application.

[0036] Example 1

[0037] The antioxidant liquid comprises citric acid, cerous sulfate, hyaluronic acid, fructose, polyethylene glycol 1000 and water, wherein the concentration of citric acid is 3 g / L, the concentration of cerous sulfate is 0.1 g / L, the total concentration of hyaluronic acid is 10 g / L, the concentration of fructose is 8 g / L, and the concentration of polyethylene glycol 1000 is 8 g / L. The hyaluronic acid is composed of high molecular weight hyaluronic acid with a molecular weight of 450×10 4 , medium molecular weight hyaluronic acid with a molecular weight of 50×10 4 , and low molecular weight hyaluronic acid with a molecular weight of 10×10 4 , and the mass ratio of high molecular weight hyaluronic acid, medium molecular weight hyaluronic acid and low molecular weight hyaluronic acid is 1:2:1.

[0038] The silane coupling solution comprises nanometer silicon sol, silane coupling agent KH550 and solvent, wherein the solvent is anhydrous ethanol and water in a volume ratio of 5:1, the concentration of the nanometer silicon sol (mass content of SiO2 is 25%) is 1.5 g / L, and the concentration of the silane coupling agent KH550 is 2 g / L.

[0039] The pressing roller is abutted to the outer surface of the electrolytic copper foil, the die core of the electrolytic copper foil and the pressing roller are synchronously rotated at a rotating speed of 10 rpm, the antioxidant solution is dipped with a dust-free cloth, and the end surface of the electrolytic copper foil is wiped for 2 min. Then, a new dust-free cloth is replaced and dipped with the silane coupling solution, the end surface of the electrolytic copper foil is wiped for 2 min. After the wiping is completed, the electrolytic copper foil is dried with a hot air gun with a power of 500 W for 1 min.

[0040] Example 2

[0041] The antioxidant solution comprises citric acid, ytterbium sulfate, hyaluronic acid, glucose, polyethylene glycol 2000 and water, wherein the concentration of the citric acid is 1 g / L, the concentration of the ytterbium sulfate is 0.8 g / L, the total concentration of the hyaluronic acid is 5 g / L, the concentration of the glucose is 5 g / L, and the concentration of the polyethylene glycol 2000 is 12 g / L. The hyaluronic acid is composed of high-molecular-weight hyaluronic acid with a molecular weight of 300×10 4 , medium-molecular-weight hyaluronic acid with a molecular weight of 70×10 4 , and low-molecular-weight hyaluronic acid with a molecular weight of 5×10 4 , and the mass ratio of the high-molecular-weight hyaluronic acid, the medium-molecular-weight hyaluronic acid and the low-molecular-weight hyaluronic acid is 1:2:3.

[0042] The silane coupling solution comprises nanometer silicon sol, silane coupling agent KH560 and solvent, wherein the solvent is methanol and water in a volume ratio of 6.5:1, the concentration of the nanometer silicon sol (mass content of SiO2 is 20%) is 2 g / L, and the concentration of the silane coupling agent KH560 is 4 g / L.

[0043] The pressing roller is abutted to the outer surface of the electrolytic copper foil, the die core of the electrolytic copper foil and the pressing roller are synchronously rotated at a rotating speed of 10 rpm, the antioxidant solution is dipped with a dust-free cloth, and the end surface of the electrolytic copper foil is wiped for 2 min. Then, a new dust-free cloth is replaced and dipped with the silane coupling solution, the end surface of the electrolytic copper foil is wiped for 2 min. After the wiping is completed, the electrolytic copper foil is dried with a hot air gun with a power of 500 W for 1 min.

[0044] Example 3

[0045] The antioxidant solution comprises citric acid, lanthanum sulfate, hyaluronic acid, fructose, polyethylene glycol 1000 and water, wherein the concentration of the citric acid is 5 g / L, the concentration of the lanthanum sulfate is 0.4 g / L, the total concentration of the hyaluronic acid is 15 g / L, the concentration of the fructose is 3 g / L, and the concentration of the polyethylene glycol 1000 is 5 g / L. The hyaluronic acid is composed of high-molecular-weight hyaluronic acid with a molecular weight of 500×104 high molecular weight hyaluronic acid with a molecular weight of 90 x 10 4 medium molecular weight hyaluronic acid with a molecular weight of 7 x 10 4 low molecular weight hyaluronic acid with a molecular weight of 1 x 10

[0046] The silane coupling solution comprises a nano-silica sol, a silane coupling agent KH550, and a solvent, wherein the solvent is isopropanol and water in a volume ratio of 8:1, the concentration of the nano-silica sol (with a mass content of 30% of SiO2) is 0.5 g / L, and the concentration of the silane coupling agent KH550 is 6 g / L.

[0047] The pressing roller abuts against the outer surface of the electrolytic copper foil, and the die of the electrolytic copper foil and the pressing roller are synchronously rotated at a speed of 10 rpm; an antioxidant solution is dipped with a dust-free cloth, and the end surface of the electrolytic copper foil is wiped for 2 min. Then, a new dust-free cloth is used to dip a silane coupling solution, and the end surface of the electrolytic copper foil is wiped for 2 min. After the wiping is completed, the electrolytic copper foil is blown dry with a hot air gun with a power of 500 W for 1 min.

[0048] Comparative Example 1

[0049] The plumbic sulfate in Example 1 is omitted, and the rest is the same as in Example 1.

[0050] Comparative Example 2

[0051] The high molecular weight hyaluronic acid and the low molecular weight hyaluronic acid in Example 1 are omitted, and the rest is the same as in Example 1.

[0052] Comparative Example 3

[0053] The silane coupling solution in Example 1 is omitted, and the rest is the same as in Example 1.

[0054] Comparative Example 4

[0055] The antioxidant solution comprises chromic anhydride, zinc sulfate, potassium sulfate, vitamin A, benzotriazole, glucose, and water, wherein the concentration of the chromic anhydride is 0.5 g / L, the concentration of the zinc sulfate is 0.5 g / L, the concentration of the potassium sulfate is 0.1 g / L, the concentration of the vitamin A is 0.4 g / L, the concentration of the benzotriazole is 0.2 g / L, and the concentration of the glucose is 3 g / L.

[0056] The die of the electrolytic copper foil is rotated at a speed of 10 rpm, an antioxidant solution is dipped with a dust-free cloth, and the end surface of the electrolytic copper foil is wiped for 2 min. After the wiping is completed, the electrolytic copper foil is blown dry with a hot air gun with a power of 500 W for 1 min.

[0057] The electrolytic copper foils of Examples 1-3 and Comparative Examples 1-4 were respectively stored in an environment of room temperature and 75% RH, and the appearance of the end surface of the electrolytic copper foil was observed and recorded, and the results are shown in Table 1.

[0058] Table 1 Appearance of the end surface of the electrolytic copper foil

[0059] Storage time 1 month 2 months 3 months 4 months Example 1 No discoloration No discoloration No discoloration No discoloration Example 2 No discoloration No discoloration No discoloration No discoloration Example 3 No discoloration No discoloration No discoloration No discoloration Comparative Example 1 No discoloration Discoloration Comparative Example 2 No discoloration No discoloration Discoloration Comparative Example 3 No discoloration Discoloration Comparative Example 4 No discoloration No discoloration No discoloration Discoloration

[0060] As shown in Table 1, the method for preventing the end surface of the electrolytic copper foil from discoloring is provided, the anti-oxidation liquid and the silane coupling liquid are sequentially coated, the rare earth sulfate, hyaluronic acid, citric acid and organic sugar are used in the synergistic anti-oxidation system, the oxidation of the end surface is effectively prevented, the nano-silica sol and the silane coupling agent are used to form a protective film on the end surface, the storage time of the electrolytic copper foil is further prolonged, the electrolytic copper foil can be stored for 4 months in the environment with high relative humidity without discoloring, and the anti-oxidation liquid and the silane coupling liquid do not penetrate into the electrolytic copper foil. In Comparative Example 4, the end surface of the electrolytic copper foil does not discolor for 3 months, but the press roller is not arranged, the anti-oxidation liquid is directly coated, the anti-oxidation liquid penetrates into the electrolytic copper foil, and the appearance and storage of the electrolytic copper foil are affected.

[0061] The above only describes the preferred embodiments of the present application, and it should be noted that the ordinary skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should be considered as the protection scope of the present application.

Claims

1. A method of preventing discoloration of an end surface of electrolytic copper foil, characterized by, The end face of the electrolytic copper foil is sequentially coated with an antioxidant solution and a silane coupling solution.

2. The method of claim 1, wherein, The antioxidant solution comprises citric acid, rare earth sulfate, hyaluronic acid, organic sugar, polyethylene glycol and water.

3. The method of claim 2, wherein, The rare earth sulfate comprises one or more of cerium sulfate, ytterbium sulfate and lanthanum sulfate. The organic sugar comprises glucose and / or fructose.

4. The method according to claim 2 or 3, characterized in that, In the antioxidant solution, the concentration of citric acid is 1-5 g / L, the concentration of rare earth sulfate is 0.1-0.8 g / L, the concentration of hyaluronic acid is 5-15 g / L, the concentration of organic sugar is 3-8 g / L, and the concentration of polyethylene glycol is 5-12 g / L.

5. The method of claim 1, wherein, The silane coupling solution comprises nano-silica sol, silane coupling agent and solvent.

6. The method of claim 5, wherein, In the silane coupling solution, the concentration of nano-silica sol is 0.5-2 g / L, and the concentration of silane coupling agent is 2-6 g / L.

7. The method according to claim 5 or 6, characterized in that, The solvent is an alcohol-water mixture, and the alcohol in the alcohol-water mixture comprises one or more of anhydrous ethanol, methanol and isopropyl alcohol. The volume ratio of alcohol to water in the alcohol-water mixture is 5-8:

1.

8. The method of claim 1, wherein, The coating is performed by wiping or spraying.

9. The method of claim 8, wherein, The method further comprises abutting a press roller against the outer surface of the electrolytic copper foil, and rotating the tube core of the electrolytic copper foil synchronously with the press roller while performing the coating.