High-thermal-conductivity and high-adhesiveness copper foil coating ink paint as well as preparation method and application thereof

Abstract

The invention belongs to the field of composite ink coatings, and particularly discloses a high-thermal-conductivity and high-adhesiveness copper foil coating ink coating as well as a preparation method and application thereof. The ink coating is prepared from the following components in parts by weight: 15 to 25 parts of epoxy resin, 10 to 20 parts of polyurethane resin, 5 to 12 parts of modified cellulose, 30 to 45 parts of heat-conducting filler, 8 to 15 parts of aliphatic polyisocyanate curing agent, 20 to 35 parts of solvent, 2 to 5 parts of silane coupling agent and 0.5 to 3 parts of pigment. The modified cellulose is prepared by modifying halogen-free betaine hydroxide, and can cooperate with the double-resin matrix to enhance the interface bonding force and construct a three-dimensional heat-conducting network. After the surface of an electrolytic or rolled copper foil is coated with the ink coating, the heat conductivity coefficient of the coating is larger than 0.4 W / (m.K), the dyne value is larger than 38, the cross-cut test is larger than or equal to 4B, alcohol wiping resistance is achieved, falling is avoided, the color difference delta E is smaller than 1, and the ink coating is suitable for a high-frequency circuit substrate and a lithium battery current collector.

Description

Technical Field

[0001] The invention belongs to the field of composite ink coatings, and specifically discloses a high-thermal-conductivity and high-adhesion copper foil coating ink coating, a preparation method and an application thereof. Background Art

[0002] As electronic devices advance toward high-density integration, high frequency, and high speed, the heat dissipation and interfacial stability requirements of copper foil, the circuit substrate, are becoming increasingly stringent. Traditional copper foil coating inks typically incorporate high proportions of thermally conductive fillers such as alumina and boron nitride to enhance thermal conductivity. However, the excessive addition of fillers disrupts the continuity of the resin matrix, increasing internal stress in the coating. This can lead to edge peeling and grid shedding during 100-grid testing, making it difficult to consistently achieve the 4B grade standard. Furthermore, high filler content exacerbates the coating's surface roughness, making it susceptible to localized failure due to mechanical wear during alcohol wipe testing. Furthermore, existing resin systems, such as single epoxy or acrylic resins, exhibit weak physical anchoring to the copper foil surface, with interfacial dyne values ​​generally below 36, making them unable to meet the precise surface energy requirements of micron-scale circuit etching processes. Some studies have attempted to improve interfacial bonding by adding silane coupling agents, but the lack of compatibility between the coupling agent and the resin can easily lead to filler aggregation or uneven solvent evaporation, resulting in significant color variation in the coating and affecting product appearance consistency.

[0003] Therefore, there is an urgent need to develop a coating ink that combines high thermal conductivity, excellent adhesion, and processing stability. In recent years, cellulose-based materials have attracted attention due to their reproducibility, high film-forming strength, and low cost. However, unmodified cellulose has significant drawbacks: the large number of hydroxyl groups in its molecular chain leads to poor compatibility with hydrophobic resins, easily causing phase separation in the ink system, which in turn reduces the density of the coating. Furthermore, cellulose itself has extremely low thermal conductivity, and directly adding it would offset the benefits of thermally conductive fillers. Summary of the Invention

[0004] In order to solve the above-mentioned problems of the prior art, the present invention discloses a high thermal conductivity and high adhesion copper foil coating ink coating and its preparation method and application. The present invention uses specific halogen-free modified cellulose to synergistically optimize the interface bonding between the resin matrix and the thermal conductive filler, while improving the dyne value and significantly enhancing the alcohol resistance and color difference stability.

[0005] In order to achieve the above purpose, the present invention solves the technical problem by adopting the following technical solutions:

[0006] The invention discloses a high thermal conductivity and high adhesion copper foil coating ink coating, which comprises, by weight: 15-25 parts of epoxy resin, 10-20 parts of polyurethane resin, 5-12 parts of modified cellulose, 30-45 parts of a thermal conductive filler mixed with aluminum oxide and boron nitride, 8-15 parts of aliphatic polyisocyanate curing agent, 20-35 parts of propylene glycol methyl ether acetate solvent, 2-5 parts of silane coupling agent, and 1-3 parts of carbon black pigment;

[0007] The preparation of modified cellulose includes: mixing microcrystalline cellulose and betaine hydroxide in a mass ratio of 1:0.4-0.6, reacting at 60-80°C under alkaline conditions for 4-6 hours, washing and drying to obtain modified cellulose.

[0008] Furthermore, in the above-mentioned ink coating, the epoxy resin is a bisphenol A epoxy resin with an epoxy equivalent of 350-450 g / eq, and the polyurethane resin is an aliphatic polyester polyurethane with a solid content of 50-60%.

[0009] Furthermore, in the above-mentioned ink coating, the average particle size of the thermal conductive filler is 2-8 μm, the aluminum oxide is α-phase spherical particles, the boron nitride is a flake structure, and the flake diameter-to-thickness ratio is 10:1-20:1.

[0010] Furthermore, in the above ink coating, the mass ratio of aluminum oxide to boron nitride is 3:1-5:1.

[0011] The present invention discloses a method for preparing the above-mentioned ink coating, comprising the following steps:

[0012] (1) Mix epoxy resin, polyurethane resin, and propylene glycol methyl ether acetate solvent and stir at 50-60°C until completely dissolved;

[0013] (2) Add silane coupling agent KH550 and modified cellulose and ultrasonically disperse for 20-30 minutes;

[0014] (3) Add alumina and boron nitride thermal conductive fillers and grind to a fineness of ≤5μm;

[0015] (4) Adding an aliphatic polyisocyanate curing agent and a carbon black pigment, dispersing at high speed and then filtering to obtain an ink coating.

[0016] Furthermore, in the above preparation method, the grinding in step (3) adopts a three-roller mill, the roller spacing is 10-20 μm, and the number of grinding times is 3-5 times.

[0017] The present invention also discloses the application of the ink coating in electrolytic copper foil or rolled copper foil, which is coated on the surface of the electrolytic copper foil or rolled copper foil with a coating thickness of 8-15 μm and cured at 80-100° C. for 10-15 minutes.

[0018] Furthermore, in the above application, the coated copper foil is used for a high-frequency circuit substrate or a negative electrode current collector of a lithium battery, and the surface roughness of the coating Ra is less than 0.3 μm.

[0019] Furthermore, in the above application, the coating process is slit coating or micro gravure coating, and the coating speed is 10-30 m / min.

[0020] Compared with the prior art, the present invention has the following outstanding beneficial effects:

[0021] 1. The present invention forms a continuous heat conduction path by compounding aluminum oxide and flake boron nitride and directional arrangement of modified cellulose, with a thermal conductivity of 0.43-0.59W / (m·K). In addition, the carboxyl groups of the betaine-modified cellulose form coordination bonds with the copper foil, and the quaternary ammonium groups enhance electrostatic adsorption, so that the prepared ink coating has good thermal conductivity and adhesion.

[0022] 2. The present invention optimizes the ratio of silane coupling agent to modified cellulose to inhibit alcohol penetration and pigment agglomeration. The coating does not fall off after being wiped with alcohol and has good chemical resistance and color difference stability.

[0023] 3. The present invention takes into account both flexibility and curing strength through epoxy resin and polyurethane dual resin, is suitable for slit coating, micro-gravure coating and other processes, and can be used for copper foils of different thicknesses.

[0024] 4. The present invention uses modified cellulose to replace part of the resin, which reduces the amount of filler used. The preparation process is halogen-free, no toxic solvent is released, and it is green and environmentally friendly. DETAILED DESCRIPTION

[0025] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] In the present invention, when referring to numerical ranges, unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Furthermore, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges subsumed therein.

[0027] In the present invention, there is no particular limitation on the specific dispersion and stirring treatment methods.

[0028] In the present invention, the test methods used are conventional methods unless otherwise specified; the materials, reagents, etc. used are reagents and materials that can be obtained from commercial channels unless otherwise specified.

[0029] The raw materials and equipment used in the following examples are shown in Tables 1 and 2.

[0030] Table 1 Source of raw materials

[0031]

[0032] Table 2 Instrument and equipment parameters

[0033]

[0034]

[0035] Example 1

[0036] 1. A high thermal conductivity and high adhesion copper foil coating ink coating, which includes, by weight, 15 parts of bisphenol A epoxy resin (E-51), 10 parts of polyurethane resin (aliphatic polyester type, Desmocoll 540), 5 parts of modified cellulose, 30 parts of thermal conductive filler, 8 parts of aliphatic polyisocyanate curing agent (HDI trimer, Covestro Desmodur N3300), 20 parts of solvent (propylene glycol methyl ether acetate, PMA), 2 parts of coupling agent (KH550), and 1 part of pigment (carbon black).

[0037] In this embodiment, the thermal conductive filler is a mixture of aluminum oxide (α phase, particle size 3 μm) and boron nitride (flake-shaped, flake diameter-to-thickness ratio 15:1) in a mass ratio of 3:1.

[0038] In this example, modified cellulose was prepared:

[0039] (1) mixing microcrystalline cellulose and betaine hydroxide in a mass ratio of 1:0.5;

[0040] (2) The mixture was added to an aqueous solution containing 5% NaOH and reacted at 80°C for 5 hours;

[0041] (3) After the reaction, filter, wash with deionized water until neutral, dry in vacuum at 60°C for 12 hours, and grind through a 200-mesh sieve.

[0042] 2. A method for preparing a high thermal conductivity and high adhesion copper foil coating ink, comprising the following steps:

[0043] (1) Resin dissolution: Mix epoxy resin, polyurethane resin and PMA, and stir at 60°C and 800 rpm for 30 minutes;

[0044] (2) Coupling dispersion: Add KH550 and modified cellulose, and disperse by 40 kHz ultrasonication (power 300 W) for 25 min;

[0045] (3) Filler grinding: three-roll mill grinding (roller spacing 20 μm, roller temperature 25 ° C) 4 times, fineness ≤ 5 μm;

[0046] (4) Curing and dispersion: Add HDI trimer curing agent and carbon black, disperse at a high speed of 2000 rpm for 15 minutes, and then filter under pressure (0.2 MPa) through a 200-mesh nylon filter to obtain an ink coating.

[0047] Example 2

[0048] 1. A high thermal conductivity and high adhesion copper foil coating ink coating, which includes, by weight, 20 parts of bisphenol F epoxy resin (E-44), 15 parts of polyurethane resin (aromatic, Uralane 5770), 10 parts of modified cellulose, 45 parts of thermal conductive filler, 12 parts of aliphatic polyisocyanate curing agent (HDI trimer, Covestro Desmodur N3300), 30 parts of solvent (propylene glycol methyl ether acetate, PMA), 4 parts of coupling agent (KH550), and 2 parts of pigment (carbon black).

[0049] In this embodiment, the thermal conductive filler is a mixture of aluminum oxide (α phase, particle size 3 μm) and boron nitride (flake-shaped, flake diameter-to-thickness ratio 15:1) in a mass ratio of 5:1.

[0050] In this example, the modified cellulose was prepared in the same manner as in Example 1.

[0051] 2. A method for preparing a high thermal conductivity and high adhesion copper foil coating ink, comprising the following steps:

[0052] (1) Resin dissolution: Mix epoxy resin, polyurethane resin and PMA, and stir at 65°C and 1000 rpm for 40 minutes;

[0053] (2) Coupling dispersion: Add KH550 and modified cellulose, and disperse at 50 kHz ultrasonic power (350 W) for 30 min;

[0054] (3) Filler grinding: three-roll mill grinding (roller spacing 10 μm, roller temperature 30 ° C) 5 times, fineness ≤ 5 μm;

[0055] (4) Curing and dispersion: Add HDI trimer curing agent and carbon black, disperse at a high speed of 2500 rpm for 20 minutes, and then filter under pressure (0.3 MPa) through a 300-mesh nylon filter to obtain an ink coating.

[0056] Example 3

[0057] 1. A high thermal conductivity and high adhesion copper foil coating ink coating, which includes, by weight, 18 parts of bisphenol A epoxy resin (E-51), 12 parts of polyurethane resin (aliphatic polyester type, Desmocoll 540), 8 parts of modified cellulose, 40 parts of thermal conductive filler, 10 parts of aliphatic polyisocyanate curing agent (HDI trimer, Covestro Desmodur N3300), 25 parts of solvent (propylene glycol methyl ether acetate, PMA), 3 parts of coupling agent (KH550), and 1.5 parts of pigment (carbon black).

[0058] In this embodiment, the thermal conductive filler is a mixture of aluminum oxide (α phase, particle size 3 μm) and boron nitride (flake-shaped, flake diameter-to-thickness ratio 15:1) in a mass ratio of 4:1.

[0059] In this example, the modified cellulose was prepared in the same manner as in Example 1.

[0060] 2. A method for preparing a high thermal conductivity and high adhesion copper foil coating ink, comprising the following steps:

[0061] (1) Resin dissolution: Mix epoxy resin, polyurethane resin and PMA, and stir at 60°C and 900 rpm for 35 minutes;

[0062] (2) Coupling dispersion: Add KH550 and modified cellulose, and disperse by 45kHz ultrasonic dispersion (power 320W) for 28 minutes;

[0063] (3) Filler grinding: three-roll mill grinding (roller spacing 15 μm, roller temperature 28 ° C) 4 times, fineness ≤ 5 μm;

[0064] (4) Curing and dispersion: Add HDI trimer curing agent and carbon black, disperse at a high speed of 2200 rpm for 18 minutes, and then filter under pressure (0.25 MPa) through a 250-mesh nylon filter to obtain an ink coating.

[0065] Example 4

[0066] 1. A high thermal conductivity and high adhesion copper foil coating ink coating, which includes, by weight, 15 parts of bisphenol F epoxy resin (E-44), 18 parts of polyurethane resin (aromatic, Uralane 5770), 7 parts of modified cellulose, 35 parts of thermal conductive filler, 9 parts of aliphatic polyisocyanate curing agent (HDI trimer, Covestro Desmodur N3300), 28 parts of solvent (propylene glycol methyl ether acetate, PMA), 2.5 parts of coupling agent (KH550), and 1.2 parts of pigment (carbon black).

[0067] In this example, the modified cellulose was prepared in the same manner as in Example 1.

[0068] In this embodiment, the thermal conductive filler is a mixture of aluminum oxide (α phase, particle size 3 μm) and boron nitride (flake-shaped, flake diameter-to-thickness ratio 15:1) in a mass ratio of 2.4:1.

[0069] 2. A high thermal conductivity and high adhesion copper foil coating ink coating, comprising the following steps:

[0070] (1) Resin dissolution: Epoxy resin, polyurethane resin and PMA were mixed and stirred at 62°C and 850 rpm for 38 minutes;

[0071] (2) Coupling dispersion: KH550 and modified cellulose were added and ultrasonically dispersed at 42 kHz (power 310 W) for 26 min;

[0072] (3) Filler grinding: three-roll mill grinding (roller spacing 18 μm, roller temperature 26 ° C) 4 times, fineness ≤ 5 μm;

[0073] (4) Curing and dispersion: Add HDI trimer curing agent and carbon black, disperse at a high speed of 2100 rpm for 17 minutes, and then filter under pressure (0.22 MPa) through a 220-mesh nylon filter to obtain an ink coating.

[0074] Example 5

[0075] 1. A high thermal conductivity and high adhesion copper foil coating ink coating, which includes, by weight, 22 parts of bisphenol A epoxy resin (E-51), 16 parts of polyurethane resin (aliphatic polyester type, Desmocoll 540), 12 parts of modified cellulose, 42 parts of thermal conductive filler, 14 parts of aliphatic polyisocyanate curing agent (HDI trimer, Covestro Desmodur N3300), 35 parts of solvent (propylene glycol methyl ether acetate, PMA), 5 parts of coupling agent (KH550), and 3 parts of pigment (carbon black).

[0076] In this example, the modified cellulose was prepared in the same manner as in Example 1.

[0077] In this embodiment, the thermal conductive filler is a mixture of aluminum oxide (α phase, particle size 3 μm) and boron nitride (flake-shaped, flake diameter-to-thickness ratio 15:1) in a mass ratio of 5:1.

[0078] 2. A high thermal conductivity and high adhesion copper foil coating ink coating, comprising the following steps:

[0079] (1) Resin dissolution: Mix epoxy resin, polyurethane resin and PMA, and stir at 70°C and 950 rpm for 45 minutes;

[0080] (2) Coupling dispersion: Add KH550 and modified cellulose, and disperse at 55kHz ultrasonic power (380W) for 32 minutes;

[0081] (3) Filler grinding: three-roll mill grinding (roller spacing 12 μm, roller temperature 32 ° C) 5 times, fineness ≤ 5 μm;

[0082] (4) Curing and dispersion: Add HDI trimer curing agent and carbon black, disperse at a high speed of 2600 rpm for 22 minutes, and then filter under pressure (0.35 MPa) through a 350-mesh nylon filter to obtain an ink coating.

[0083] Comparative Example 1

[0084] The difference between Comparative Example 1 and Example 1 is that an equal amount of microcrystalline cellulose is used to replace the modified cellulose in Comparative Example 1, and all other conditions are the same.

[0085] Comparative Example 2

[0086] The difference between Comparative Example 2 and Example 1 is that no polyurethane resin is added in Comparative Example 2, and the weight portion of epoxy resin is 25 parts, and the other parts are the same.

[0087] Comparative Example 3

[0088] The difference between Comparative Example 3 and Example 1 is that the weight portion of the thermal conductive filler in Comparative Example 3 is 55 parts, and the other parts are the same.

[0089] The thermal conductive filler is a mixture of aluminum oxide (α phase, particle size 3 μm) and boron nitride (flake, flake diameter to thickness ratio 15:1) in a mass ratio of 3:1.

[0090] Comparative Example 4

[0091] The difference between Comparative Example 4 and Example 2 is that no coupling agent KH550 is added in Comparative Example 4, and all other conditions are the same.

[0092] Application Example 1

[0093] In order to eliminate the interference of the coating process on the test results, all examples and comparative examples were coated and tested under the following uniform conditions:

[0094] 1. Substrate pretreatment:

[0095] Electrolytic copper foil (thickness 18 μm, surface roughness Rz ≤ 1.5 μm) and rolled copper foil (thickness 12 μm, Rz ≤ 0.8 μm) were used as coating substrates;

[0096] The surface of the copper foil was plasma cleaned (power 300 W, argon flow rate 10 L / min, treatment time 30 seconds).

[0097] 2. Coating process:

[0098] Equipment: Slit coater (coating head gap 10 μm, coating speed 15 m / min);

[0099] Wet film thickness: 10±1μm (controlled by the gap between the coating head and the speed);

[0100] Drying conditions: preheat at 80°C for 3 minutes to remove the solvent.

[0101] 3. Curing process:

[0102] Curing oven temperature: 90°C constant temperature zone baking for 12 minutes;

[0103] Cooling method: The room temperature is naturally cooled to below 25℃.

[0104] 4. Test sample preparation:

[0105] The coated copper foil was cut into 10 cm × 10 cm specimens;

[0106] For each group of examples and comparative examples, 5 parallel samples were prepared and the average value was taken.

[0107] Test Example 1

[0108] Thermal conductivity test

[0109] 1. Test purpose: To verify whether the thermal conductivity of the ink coating meets the requirement of thermal conductivity coefficient > 0.4W / (m·K) in claim 1, and to analyze the effects of filler ratio, structure and modified cellulose on the thermal conductivity path.

[0110] 2. Test method:

[0111] Sample preparation: Apply the ink to electrolytic copper foil or rolled copper foil according to the unified application conditions. After curing, peel off the coating to prepare a 10mm×10mm×1mm standard sample.

[0112] Test equipment: Hot Disk TPS2500 heat flow thermal conductivity instrument.

[0113] Test parameters: heat source power 0.5W, test time 10s, ambient temperature 25℃, copper foil type recorded separately.

[0114] 3. Test grouping:

[0115] Examples 1-5: Covering different filler ratios, resin ratios and modified cellulose contents;

[0116] Comparative Examples 1 and 3: Verify the effects of unmodified cellulose and excessive filler.

[0117] Table 3 Thermal conductivity test results

[0118]

[0119]

[0120] As can be seen from Table 3, the thermal conductivity of Example 2 is significantly higher than that of the other groups. This is because the proportion of high thermal conductive filler and the directional arrangement of flake boron nitride form a continuous thermal conductive network with a thermal conductivity of 0.59 W / (m·K). In contrast, Comparative Example 1 using unmodified cellulose hinders the dispersion of the filler, resulting in a discontinuous thermal conductive path and a thermal conductivity of only 0.29 W / (m·K), indicating that the ink coating of the present invention has good thermal conductivity.

[0121] Then, although the thermal conductivity of comparative example 3 using excessive filler is high and close to the requirement, it is not feasible for practical application because excessive filler can easily lead to the destruction of the continuity of the resin matrix, the stress in the coating causes cracking, and also increases the production cost.

[0122] Test Example 2

[0123] Dyne value test

[0124] 1. Test purpose: To evaluate whether the surface energy (dyne value) of the coating meets the requirement of dyne value > 38 in claim 1 and to verify the synergistic effect of modified cellulose and coupling agent on interfacial bonding strength.

[0125] 2. Test method:

[0126] Sample preparation: After coating and curing according to the application conditions, select a defect-free area on the surface.

[0127] Test equipment: Arcotest dyne pen (38-44 mN / m gradient).

[0128] Operation steps: Add different dyne value test liquids on the coating surface and observe the minimum value at which the liquid film remains intact for 2 seconds.

[0129] 3. Test grouping:

[0130] Examples 2 and 5: Verification of the effect of the ratio of modified cellulose to coupling agent;

[0131] Comparative Example 4, 2: Analysis of the lack of coupling agent and the defects of a single resin.

[0132] Table 4 Dyne value test results

[0133] Group Dyne value (mN / m) Example 2 42 Example 5 44 Comparative Example 4 35 Comparative Example 2 38

[0134] As shown in Table 4, the quaternary ammonium groups in Example 5 form chemical bonds with the copper foil surface, and the coupling agent KH550 enhances the resin-filler interface bonding, resulting in a dyne value of up to 44 mN / m. In contrast, Comparative Example 4, which does not add a coupling agent, relies on physical adsorption, resulting in a dyne value of only 35 mN / m, indicating severely insufficient interfacial bonding strength. Comparative Example 2 uses a single epoxy resin system, which has poor flexibility and low surface energy, and cannot meet the requirements of microcircuit etching.

[0135] Test Example 3

[0136] Hundred Grid Test

[0137] 1. Test purpose: To verify whether the coating adhesion meets the requirement of ≥4B in the 100-grid test in claim 1, and to analyze the effects of resin type, filler distribution and modified cellulose on adhesion.

[0138] 2. Test method:

[0139] Test standard: ASTM D3359, using an 11-edge cross-cut (1mm spacing).

[0140] Operation steps: After marking, stick 3M 600 tape, peel it off quickly and count the number of fallen grids under a microscope.

[0141] 3. Test grouping:

[0142] Examples 3 and 4: Verify the effect of filler structure (flake-shaped boron nitride) and high polyurethane resin ratio;

[0143] Comparative Examples 1, 2, and 3: Analyze the defects of unmodified cellulose, single resin, and excessive filler.

[0144] Table 5 Hundred-grid test results

[0145] Group Number of missing grids grade Example 3 1 4B Example 4 0 5B Comparative Example 1 5 3B Comparative Example 2 8 2B Comparative Example 3 3 4B (but coating cracked)

[0146] As shown in Table 5, Example 4 uses more polyurethane resin to improve the flexibility of the coating, and has a significant curing stress buffering effect, with a 100-grid test rating of 5B and no shedding. In contrast, the single epoxy resin in Comparative Example 2 is highly brittle, with internal stress concentration after curing, 8 shedding grids, and a rating of only 2B. Comparative Example 3 uses more thermally conductive fillers, resulting in a weak resin matrix. Although the 100-grid test rating is 4B, the coating is cracked and is actually unusable.

[0147] Test Example 4

[0148] Alcohol wipe resistance test

[0149] 1. Test purpose: To verify whether the coating's chemical corrosion resistance and mechanical strength meet the requirements of claim 1, namely, "resistance to alcohol wiping without falling off".

[0150] 2. Test method:

[0151] Test conditions: 500g weight load, non-woven fabric dipped in 99% alcohol, rubbed back and forth 30 times at a speed of 10cm / s.

[0152] Evaluation criteria: Observe the coating peeling area ratio under a microscope (<5% is considered a pass).

[0153] 3. Test grouping:

[0154] Examples 1 and 2: Verification of the scratch resistance of the basic formula and the preferred formula;

[0155] Comparative Examples 3 and 4: Analyze the effects of excess filler and lack of coupling agent.

[0156] Table 6 Alcohol wipe resistance test results

[0157] Group Shedding area Rating Example 1 <1％ pass Example 2 0％ pass Comparative Example 4 15％ Fail Comparative Example 3 20% (cracked) Fail

[0158] As shown in Table 6, Example 2 has high filler dispersion and a dense coating structure, and is resistant to alcohol wiping without falling off; while Comparative Example 4 has no coupling agent, resulting in weak filler-resin interface bonding, and the coating peels off over a large area after alcohol penetration; Comparative Example 3 uses a large amount of thermally conductive filler, which easily causes cracking of the coating, and alcohol intrusion into the cracks exacerbates the shedding.

[0159] Test Example 5

[0160] Color difference test

[0161] 1. Test purpose: To verify whether the color difference of the coating meets the requirement of ΔE < 1 in claim 1, and to analyze the synergistic effect of modified cellulose and coupling agent on pigment dispersion.

[0162] 2. Test method:

[0163] Test equipment: X-Rite Ci64 colorimeter (CIE Lab standard).

[0164] Operation steps: Compare the color difference between the standard sample (ΔE=0) and the coating surface at 5 points, and take the average value.

[0165] 3. Test grouping:

[0166] Examples 1 and 5: Verification of the effects of the basic formula and high modified cellulose ratio;

[0167] Comparative Examples 1, 2, and 4: Analyze the effects of unmodified cellulose, single resin, and the absence of coupling agent.

[0168] Table 7 Color difference test results

[0169] Group ΔE value Example 5 0.7 Example 1 0.9 Comparative Example 1 1.8 Comparative Example 2 2.1 Comparative Example 4 1.5

[0170] As shown in Table 7, the pigment dispersion in the ink coating prepared in Example 5 was uniform, with minimal color variation. However, Comparative Example 1 used unmodified cellulose, which had poor compatibility with the resin and resulted in pigment agglomeration, resulting in a color difference of ΔE = 1.8. Comparative Example 2 used a single epoxy resin, which had poor release properties and pigment sedimentation, resulting in a color difference of ΔE = 2.1.

[0171] In summary, the ink coating prepared in Example 2, under the synergistic effect of epoxy resin E-44, polyurethane Uralane 5770, modified cellulose and other components, has a thermal conductivity of 0.59 W / (m·K), a dyne value of 42, and a 100 grid test of 5B, and has the best comprehensive performance. This proves that the ink coating prepared by the method of the present invention has good thermal conductivity, adhesion and color difference control, and is suitable for high-frequency circuit substrates and lithium battery current collectors.

[0172] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A high thermal conductivity and high adhesion copper foil coating ink, characterized in that: The invention comprises, by weight, 15-25 parts of epoxy resin, 10-20 parts of polyurethane resin, 5-12 parts of modified cellulose, 30-45 parts of a thermally conductive filler mixed with aluminum oxide and boron nitride, 8-15 parts of aliphatic polyisocyanate curing agent, 20-35 parts of propylene glycol methyl ether acetate solvent, 2-5 parts of silane coupling agent, and 1-3 parts of carbon black pigment. The preparation of modified cellulose includes: mixing microcrystalline cellulose and betaine hydroxide in a mass ratio of 1:0.4-0.6, reacting at 60-80°C under alkaline conditions for 4-6 hours, washing and drying to obtain modified cellulose.

2. The ink coating according to claim 1, characterized in that: The epoxy resin is a bisphenol A epoxy resin with an epoxy equivalent of 350-450 g / eq. The polyurethane resin is an aliphatic polyester polyurethane with a solid content of 50-60%.

3. The ink coating according to claim 1, characterized in that: The average particle size of the thermal conductive filler is 2-8 μm, the aluminum oxide is α-phase spherical particles, the boron nitride is a flaky structure, and the flaky diameter-to-thickness ratio is 10:1-20:

1.

4. The ink coating according to claim 1, characterized in that The mass ratio of the aluminum oxide to the boron nitride is 3:1-5:

1.

5. The method for preparing the ink coating according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) Mix epoxy resin, polyurethane resin, and propylene glycol methyl ether acetate solvent and stir at 50-60°C until completely dissolved; (2) Add silane coupling agent KH550 and modified cellulose and ultrasonically disperse for 20-30 minutes; (3) Add alumina and boron nitride thermal conductive fillers and grind to a fineness of ≤5μm; (4) Adding an aliphatic polyisocyanate curing agent and a carbon black pigment, dispersing at high speed and then filtering to obtain an ink coating.

6. The preparation method according to claim 5, characterized in that In step (3), a three-roll mill is used for grinding, the roller spacing is 10-20 μm, and the grinding times are 3-5 times.

7. Use of the ink coating according to any one of claims 1 to 4 in electrolytic copper foil or rolled copper foil, characterized in that: Coated on the surface of electrolytic copper foil or rolled copper foil, the coating thickness is 8-15μm, and the curing conditions are baking at 80-100℃ for 10-15 minutes.

8. The use according to claim 7, characterized in that The coated copper foil is used for high-frequency circuit substrates or lithium battery negative electrode current collectors, and the coating surface roughness Ra is less than 0.3 μm.

9. The use according to claim 7, characterized in that The coating process is slit coating or micro gravure coating, and the coating speed is 10-30m / min.

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