Insulating coating, method for preparing copper foil by using insulating coating and copper-clad plate

Abstract

The invention relates to an insulating coating, a method for preparing a copper foil by using the insulating coating and a copper-clad plate. The insulating coating comprises organic resin, a tackifier and a defoaming agent. In the curing process, the organic resin, the tackifier and the defoaming agent in the insulating coating cooperate with one another, and the performance of the insulating coating in the aspects of durability, insulativity, binding force with a negative roller and the like is optimized. The insulating coating can effectively shield the cathode, the breadth of the customized copper foil is achieved, the production efficiency is improved, and waste caused by the slitting procedure is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of electrolytic copper foil, and in particular relates to an insulating coating, a method for preparing copper foil using the insulating coating, and a copper-clad laminate. Background Art

[0002] Copper foil is widely used in new electronic information industry, new energy automobile industry, aerospace and other major national projects as the signal transmission medium of portable electronic products and the current collector of lithium-ion batteries. Among them, high-performance electrolytic copper foil is the key material for manufacturing high-frequency and high-speed printed circuit boards for 5G communications and current collectors for high-energy-density lithium-ion batteries. However, when realizing the industrialization of copper foil to meet market demand, in addition to focusing on its high performance, it is also necessary to take into account the issue of reducing costs.

[0003] In the preparation process of electrolytic copper foil, the copper foil is usually cut into widths according to customer needs after the finished product is obtained. Therefore, the excess waste foil generated during the cutting process will lead to cost waste. To this end, researchers at home and abroad are actively exploring methods to control the width of electrolytic copper foil in the foil production section to meet the market demand for various electronic circuit foils, lithium-ion electric foils, and all-solid-state battery foils.

[0004] Based on the structure of the copper foil production equipment, mechanical shielding of the excess part of the cathode roller or anode plate is usually used to control the width of the electrolytic copper foil. For example, CN204702826U discloses a method for shielding by directly attaching insulating tape to the cathode roller and the anode plate. However, due to the long-term immersion of the insulating tape in the acidic high-temperature electrolyte, the risk of its falling off is significantly increased. On the other hand, the method disclosed in CN111286766A is achieved by directly changing the structure of the foil machine, but due to the additional addition of mechanical parts, this change greatly increases the probability of equipment failure, and may also cause slippage between the belt and the cathode roller, thereby affecting the normal operation of the cathode roller. Therefore, it is of great significance to develop a shielding method with strong bonding, excellent insulation performance and long-term durability to enhance commercial value. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide an insulating coating, a method for preparing copper foil using the insulating coating and a copper clad laminate, which solves the problem of difficulty in switching production of copper foils of different widths and waste during the slitting process.

[0006] The invention provides an insulating coating, which comprises an organic resin, a tackifier and a defoamer; the amount of the tackifier is 0.5wt%-2wt% of the organic resin, and the amount of the defoamer is 0.05wt%-0.1wt% of the organic resin.

[0007] Preferably, the organic resin includes one or more of phenolic resin, epoxy resin, polyacrylic resin, polyurethane resin, polyester resin, and polyimide resin.

[0008] Preferably, the tackifier includes one or more of a polyurethane thickener, an aqueous rosin tackifier emulsion, an aqueous terpene tackifier emulsion, and carboxymethyl cellulose.

[0009] Preferably, the defoamer includes one or more of epoxy resin defoamer, high temperature polyester defoamer, high carbon alcohol defoamer, PVC defoamer, polyether defoamer, and silicone defoamer.

[0010] Preferably, the thickness of the insulating coating is 0.3-1 μm.

[0011] The present invention also provides a method for preparing copper foil using the insulating coating, comprising the following steps:

[0012] S1. Affixing a shielding tape to the surface of the cathode roller to define a spraying area of ​​the organic resin mixture; wherein the organic resin mixture comprises an organic resin, a tackifier and a defoaming agent;

[0013] S2 spraying an organic resin mixture on the cathode roller, and curing to obtain an insulating coating;

[0014] S3. Remove the shielding tape on the cathode roller;

[0015] S4. Electroplating copper foil on the cathode roller to obtain raw foil; subjecting the obtained raw foil to surface roughening treatment and anti-oxidation treatment to obtain finished copper foil.

[0016] Preferably, the material of the shielding tape in step S1 includes one or more of polyimide, glass fiber and polytetrafluoroethylene.

[0017] Preferably, in step S1, the bonding force between the shielding tape and the cathode roller is greater than 2.5 lb / in, the width of the shielding tape is between 500 mm and 1500 mm, the shielding tape is pasted on the middle part of the cathode roller, and the two edges of the shielding tape are equidistant from the left and right edges of the cathode roller.

[0018] Preferably, the spraying method in step S2 is air spraying or aerosol spraying, and the spraying pressure is 0.3-0.6 MPa.

[0019] Preferably, the curing method in step S2 is heating curing, that is, the heating wire is wound around the resin area on the cathode roller, the curing temperature is 60-120° C., and the curing time is 2-6 hours.

[0020] Preferably, the spraying and curing are performed no less than once.

[0021] Preferably, the current density of the electroplated copper foil in step S4 is 80-200A / dm 2 , raw foil surface density 40-1200g / m 2 The tensile strength, elongation and roughness of the finished copper foil are tested.

[0022] The present invention also provides a copper clad laminate, wherein the copper foil prepared above is pressed with a prepreg to obtain a copper clad laminate, wherein the pressing can be single-sided or double-sided pressing to obtain a single-sided or double-sided copper clad laminate.

[0023] Beneficial Effects

[0024] The insulating coating of the present invention effectively regulates the width of the electrolytic copper foil. When the copper foil specifications are switched, the production of copper foils of different widths can be completed without hanging rollers or changing rollers, thereby saving production costs. In the insulating coating formula, the defoamer eliminates the internal pores of the insulating coating and improves the density of the coating, while the tackifier improves the bonding force between the coating and the cathode roller. The two work synergistically, so that the insulation, bonding force and durability of the coating are greatly improved, and the long-term use performance in an acidic high-temperature environment is almost not attenuated. The prepared finished copper foil was tested, and it was found that the surface morphology of the copper foil was uniform, and the surface roughness of the copper foil did not change significantly after repeated electroplating. After 20 electroplatings, the roughness Rz varied within 5%, and the tensile strength varied within 7%. Compared with products without cathode shielding, the tensile strength, elongation and roughness were basically the same. In addition, the preparation method is easy to operate, and the resin used is green and environmentally friendly, and the price is low, which further reduces the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of preparing copper foil using the insulating coating of the present invention.

[0026] Figure 2 This is a scanning electron microscope (SEM) image of the copper foil prepared in Example 3. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0028] Example 1

[0029] Step S1:

[0030] An insulating polyimide tape with a width of 1450 mm was tightly attached to the surface of the cathode roller, with both sides of the tape being equidistant from the left and right edges of the cathode roller.

[0031] Step S2:

[0032] 1) mixing an aqueous terpene thickening emulsion and a polyether defoamer with a polyurethane resin and stirring them uniformly, wherein the amount of the aqueous terpene thickening emulsion is 2wt% of the polyurethane resin, and the amount of the polyether defoamer is 0.08wt% of the polyurethane resin;

[0033] 2) Spray the above resin mixture evenly on the unshielded area of ​​the cathode roller, and keep the coating interface parallel to the edge of the cathode roller; wrap the heating wire around the cathode roller and heat at 80°C for 3 hours to cure the organic resin; after the first curing, repeat the second spraying and curing, and repeat this process until the final thickness of the insulating coating is 0.5 μm.

[0034] Step S3:

[0035] The insulating polyimide tape on the cathode roller is slowly removed to obtain an insulating coating of a specific width.

[0036] Step S4:

[0037] Finally, a current is applied to the cathode roller with a current density of 80A / dm 2 , electrolysis is performed to obtain raw foil. After the raw foil is subjected to surface roughening treatment and anti-oxidation treatment, the physical properties of the finished copper foil are tested. The results are shown in Table 1.

[0038] Example 2

[0039] The difference from Example 1 is that the thickness of the insulating coating is 0.7 μm, and the other conditions are consistent with those of Example 1.

[0040] Example 3

[0041] Different from Example 1, the tackifier is a polyurethane thickener, the defoamer is a high-carbon alcohol defoamer, and the organic resin is a phenolic resin. The amount of the polyurethane thickener is 1wt% of the phenolic resin, the amount of the high-carbon alcohol defoamer is 0.05wt% of the phenolic resin, and the insulation coating is heated at 60°C for 6h, and the thickness of the final insulation coating is 0.3μm.

[0042] Example 4

[0043] The difference from Example 1 is that the tackifier is a water-based rosin tackifier emulsion, the defoamer is a PVC defoamer, and the organic resin is a polyacrylic resin. The amount of the water-based rosin tackifier emulsion is 2wt% of the polyacrylic resin, the amount of the PVC defoamer is 0.05wt% of the polyacrylic resin, and the insulation coating is heated at 120°C for 2h, and the thickness of the final insulation coating is 1μm.

[0044] Example 5

[0045] The difference from Example 1 is that the tackifier is carboxymethyl cellulose, the defoamer is an epoxy resin defoamer, and the organic resin is an epoxy resin. The amount of the carboxymethyl cellulose tackifier is 1.5wt% of the epoxy resin, and the amount of the epoxy resin defoamer is 0.06wt% of the epoxy resin. The coating is heated at 80°C for 4h, and the thickness of the final insulating coating is 0.8μm.

[0046] Example 6

[0047] The difference from Example 1 is that the defoaming agent is a high-temperature polyester defoaming agent, and the dosage of the high-temperature polyester defoaming agent is 0.08% of the polyurethane resin. The other conditions are the same as those in Example 1.

[0048] Example 7

[0049] The difference from Example 1 is that the defoaming agent is an organosilicon defoaming agent, and the amount of the organosilicon defoaming agent used is 0.08% of the polyurethane resin. The other conditions are the same as those in Example 1.

[0050] Comparative Example 1

[0051] The difference from Example 1 is that the heating is performed at 50° C. for 3 h, and the other conditions are the same as those in Example 1.

[0052] Comparative Example 2

[0053] The difference from the first embodiment is that the thickness of the insulating coating is 0.2 μm, and the rest is the same as the first embodiment.

[0054] Comparative Example 3

[0055] The difference from Example 1 is that no tackifier is added, and the other conditions are the same as those of Example 1.

[0056] Comparative Example 4

[0057] The difference from Example 1 is that no defoaming agent is added, and the other conditions are the same as those of Example 1.

[0058] Comparative Example 5

[0059] The difference from Example 1 is that the amount of the aqueous terpene tackifying emulsion used is 3wt% of the polyurethane resin, and the other conditions are the same as those in Example 1.

[0060] Comparative Example 6

[0061] The difference from Example 1 is that the amount of the polyether defoamer used is 0.04wt% of the polyurethane resin, and the other conditions are the same as those in Example 1.

[0062] Comparative Example 7

[0063] The difference from Example 1 is that no insulating coating is used, and the other conditions are the same as those of Example 1.

[0064] Figure 1 The schematic diagram of the present invention is shown. By adjusting the shielding range, the width of the electrolytic copper foil is effectively controlled to meet the requirements of diversified specifications of copper foil products. Figure 2 The scanning electron microscope (SEM) image of Example 3 shows that the insulating coating has little effect on the morphology of the copper foil. Table 1 lists the tensile strength, elongation and roughness data of Examples 1 to 7. By comparing the physical properties of the copper foils after the first electroplating and the 20th electroplating, it is found that the physical properties of the copper foils prepared in Examples 1 to 7 are basically not affected by the insulating coating, which shows that the insulating coating has good durability.

[0065] Table 1

[0066]

[0067] The organic resin selected in the present invention does not contain groups that affect conductivity, so it exhibits excellent insulation performance and can effectively regulate the coating area. When the insulating coating is electrolytically produced under acidic conditions, it not only does not affect the performance of the copper foil itself, but also exhibits high coating edge bonding and long-term durability. This enables the product to meet the requirements of diversified copper foil specifications, thereby reducing production costs and improving market competitiveness.

[0068] In order to more clearly highlight the beneficial effects of the present invention, comparative verification was carried out to evaluate the feasibility of the embodiments of the present invention. In comparative example 1, due to insufficient heating temperature, the coating cannot be completely cured and partially dissolved in the plating solution; in comparative example 2, due to insufficient thickness of the insulating coating, copper plating occurs due to current breakdown, thereby failing to effectively shield the cathode; in comparative example 3, due to the lack of tackifier in the organic resin, the coating has poor bonding strength; in comparative example 4, due to the lack of defoamer in the organic resin, the coating has extremely poor density, the plating solution invades the coating, and most of the coating falls off; in comparative example 5, excessive tackifier is used, resulting in the inability to spray the organic resin evenly, affecting the electroplating effect; in comparative example 6, insufficient defoamer will also lead to insufficient coating density. In addition, comparative example 7 is used as a blank control without any coating, and its copper foil physical properties are similar to those of Examples 1 to 7, thereby verifying that the method of using the coating in the present invention to shield the cathode will not affect the physical properties of the copper foil, and the purpose of using the insulating coating to regulate the width of the electrolytic copper foil is achieved.

Claims

1. An insulating coating, characterized in that: The insulating coating comprises an organic resin, a tackifier and a defoamer; the amount of the tackifier is 0.5wt%-2wt% of the organic resin, and the amount of the defoamer is 0.05wt%-0.1wt% of the organic resin.

2. The insulating coating according to claim 1, characterized in that: The organic resin includes one or more of phenolic resin, epoxy resin, polyacrylic resin, polyurethane resin, polyester resin and polyimide resin.

3. The insulating coating according to claim 1, characterized in that: The tackifier includes one or more of a polyurethane thickener, an aqueous rosin tackifier emulsion, an aqueous terpene tackifier emulsion, and carboxymethyl cellulose.

4. The insulating coating according to claim 1, characterized in that: The defoaming agent includes one or more of epoxy resin defoaming agent, high temperature polyester defoaming agent, high carbon alcohol defoaming agent, PVC defoaming agent, polyether defoaming agent and silicone defoaming agent.

5. The insulating coating according to claim 1, characterized in that: The thickness of the insulating coating is 0.3-1 μm.

6. A method for preparing copper foil using the insulating coating according to any one of claims 1 to 5, comprising the following steps: S1. Affixing a shielding tape to the surface of the cathode roller to define the spraying area of ​​the organic resin mixture; wherein, The organic resin mixture comprises an organic resin, a tackifier and a defoamer; S2 spraying an organic resin mixture on the cathode roller, and curing to obtain an insulating coating; S3. Remove the shielding tape on the cathode roller; S4. Electroplating copper foil on the cathode roller to obtain raw foil; subjecting the obtained raw foil to surface roughening treatment and anti-oxidation treatment to obtain finished copper foil.

7. The method according to claim 6, characterized in that: The material of the shielding tape in step S1 includes one or more of polyimide, glass fiber and polytetrafluoroethylene.

8. The method according to claim 6, characterized in that: The spraying method in step S2 is air spraying or aerosol spraying, and the spraying pressure is 0.3-0.6 MPa.

9. The method according to claim 6, characterized in that: The curing method in step S2 is heating curing, the curing temperature is 60-120° C., and the curing time is 2-6 hours.

10. A copper clad laminate, characterized in that: The finished copper foil prepared as claimed in claim 6 is pressed together with the prepreg to obtain a copper clad laminate.

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