A low melt index high molecular weight composite copper foil PP film

Abstract

The present invention relates to the technical field of polymer polypropylene films, and discloses a low melt index high molecular weight composite copper foil PP film, comprising a copper foil and a PP film. The PP film is made of the following raw materials in parts by mass: 100 parts of a low melt index polypropylene resin, 0.05-0.5 parts of a nucleating agent, 0.1-1.0 parts of a slip agent, 0.3-1.2 parts of an antistatic agent, 0.01-0.1 parts of a surface modifier, and 1-3 parts of an antioxidant. By compounding the antistatic agent and the slip agent, a charge conduction network and a uniform lubricating layer are formed on the surface of the film, reducing surface resistance and friction coefficient, and improving antistatic properties and processing smoothness. At the same time, the silica surface modifier further optimizes the composite adaptability of the film with other materials, meeting high-precision processing requirements.

Description

Technical Field

[0001] The invention relates to the technical field of high-molecular polypropylene films, and in particular to a low-melt index high-molecular weight composite copper foil PP film. Background Art

[0002] With the rapid development of industries like electronics and new energy, performance requirements for various composite materials are becoming increasingly stringent. As an important material, composite copper foil PP film offers broad application prospects. While traditional composite copper foil PP film can play a role in electronic and electrical insulation, it also presents numerous challenges.

[0003] First, the bonding strength between copper foil and PP film is less than ideal. In actual use, delamination and peeling easily occur between the two, resulting in a decrease in the overall performance of the material. This is because the copper foil's surface is relatively smooth, resulting in limited adhesion to the PP film. Existing surface treatment technologies are ineffective in improving adhesion and cannot meet the requirements of use in complex working conditions.

[0004] Secondly, the heat resistance of PP film needs to be improved. In certain high-temperature environments, PP film is prone to deformation and aging, which can affect the proper use of copper-clad PP film. Factors such as the melt index and molecular weight of traditional PP film limit further improvements in its heat resistance, making it difficult to adapt to applications requiring high heat resistance, such as lithium batteries for new energy vehicles.

[0005] Third, the surface properties of PP film are not superior. In some processes that require further lamination with other materials or surface treatment, its surface slipperiness and antistatic properties are insufficient, leading to problems in subsequent processing. For example, electrostatic adsorption of impurities affects product quality, and poor slipperiness leads to low processing efficiency.

[0006] Fourth, the aging resistance of traditional copper-clad PP films is inadequate. Over long-term use, the films are susceptible to aging, such as brittleness, discoloration, and performance degradation, due to the combined effects of light, heat, and oxygen. This significantly shortens the material's lifespan, increasing costs and replacement frequency.

[0007] To sum up, the composite copper foil PP film in the existing technology can no longer meet the growing high performance demand. It is urgent to develop a low melt index and high molecular weight composite copper foil PP film to overcome the above difficulties, broaden its application field and enhance its market competitiveness. Summary of the Invention

[0008] The purpose of the present invention is to provide a low melt index, high molecular weight composite copper foil PP film to solve the problems of insufficient bonding strength, poor heat resistance, poor surface performance and imperfect anti-aging performance in the prior art, and meet the needs of high-performance application scenarios.

[0009] To achieve the above object, the technical solution adopted by the present invention is: a low melt index high molecular weight composite copper foil PP film, comprising a copper foil and a PP film, wherein the PP film is made of the following raw materials in parts by weight: 100 parts of a low melt index polypropylene resin, 0.05-0.5 parts of a nucleating agent, 0.1-1.0 parts of a slip agent, 0.3-1.2 parts of an antistatic agent, 0.01-0.1 parts of a surface modifier, and 1-3 parts of an antioxidant;

[0010] The antioxidant has a structure shown in Formula 1:

[0011]

[0012] Formula 1;

[0013] The Z1 is selected from the group consisting of: O, S, N(H), and C(CH3)2.

[0014] Furthermore, the thickness of the PP film is 3.0-4.5 μm±3%.

[0015] Furthermore, the low melt index polypropylene resin has a melt index of 0.5-2 g / 10 min 230° C. / 2.16 kg and a molecular weight of ≥350,000.

[0016] Furthermore, the nucleating agent is an organic phosphate nucleating agent NA-21;

[0017] The structure of the organophosphate nucleating agent NA-21 is:

[0018] .

[0019] Furthermore, the lubricant is erucamide.

[0020] Furthermore, the antistatic agent is dodecyltrimethylammonium chloride.

[0021] Furthermore, the surface modifier is silicon dioxide.

[0022] Furthermore, the antioxidant is any one of the compounds shown in the following structures:

[0023] ;

[0024] .

[0025] A method for preparing a low melt index high molecular weight composite copper foil PP film comprises the following steps:

[0026] S1. The low melt index polypropylene resin, nucleating agent, slip agent, antistatic agent, surface modifier and antioxidant are uniformly mixed in parts by mass ratio to obtain a premix;

[0027] S2. The premix is ​​added to a twin-screw extruder, melt-extruded at a melt temperature of 200-240 ℃, and a PP film is prepared by a casting process;

[0028] S3. Compounding the PP film and the copper foil by a hot pressing process, the hot pressing temperature is 120-150 ° C, the pressure is 1.0-2.0 MPa, and cooling to obtain a low melt index high molecular weight composite copper foil PP film.

[0029] Furthermore, the melt extrusion temperature in S2 is 210-230° C., and the screw speed of the twin-screw extruder is 50-100 rpm.

[0030] Furthermore, the hot pressing lamination process in S3 is performed for 30-60 seconds, and the thickness of the copper foil is 5-10 μm.

[0031] Furthermore, the cooling method is air cooling to room temperature.

[0032] The mechanism of action of the heterocyclic macroconjugated structure and the imino structure in the antioxidant described in the present invention is mainly reflected in the synergistic inhibition of the thermal oxidative aging process of polypropylene (PP) film. The heterocyclic macroconjugated structure has a large π conjugated system, which can efficiently capture the alkyl radicals and peroxy radicals generated during the aging process. The π electrons are highly delocalized, making it difficult for the radical intermediates to continue to trigger chain reactions due to conjugation stability. The macroconjugated structure can absorb ultraviolet light (UV), reduce the generation of photoinitiated free radicals, and delay photooxidative aging. The NH bond of the imino group is relatively weak and can provide hydrogen atoms to the free radicals to terminate chain propagation. The generated hydroperoxide can be further decomposed to prevent it from decomposing into new free radicals. The hydrogen atoms provided by the imino group make the heterocyclic free radicals more easily stabilized, and the two form a dual free radical termination mechanism. This dual mechanism significantly improves the long-term stability of PP film in harsh environments such as high temperature and light.

[0033] The present invention constructs a systematic solution through the coordinated optimization of material components and specific processing techniques: in the base layer, a low melt index polypropylene resin is selected. The high degree of entanglement of its polymer chains provides the basis for high melt strength and initial heat deformation temperature, and its low melt index property ensures high-temperature processing stability; on this basis, the organic phosphate nucleating agent NA-21 is introduced. It works in conjunction with high molecular weight polypropylene to promote the formation of small and homogeneous β crystals, significantly improving the crystallization temperature and crystallinity, and ultimately raising the material's heat deformation temperature by 15-20°C to 145°C. In the surface functional layer, the silica surface modifier enhances the mechanical bite force with the copper foil by increasing the surface roughness, and forms a charge conduction network on the surface with the dodecyltrimethylammonium chloride antistatic agent, jointly reducing the surface resistance; at the same time, the erucamide lubricant migrates to the surface under a specific twin-screw extrusion process to form a lubricating layer, reducing the friction coefficient. The key hot pressing composite process precisely controls the surface melting depth, promoting the mechanical interlocking of silica and the molecular diffusion of molten PP to work together to significantly improve the peel strength.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The bonding strength between copper foil and film is significantly improved: By increasing the surface roughness of the film with a surface modifier and combining it with a precisely controlled hot-pressing composite process, a dual mechanism of mechanical engagement and molecular diffusion is formed at the interface between the copper foil and the PP film, effectively suppressing delamination and improving the overall stability of the composite structure.

[0036] 2. Simultaneously Enhanced Heat Resistance and Mechanical Properties: The synergistic effect of the low melt index, high molecular weight polypropylene resin and the organophosphate nucleating agent NA-21 promotes the formation of β-crystals and increases crystallinity, enhancing the film's resistance to deformation in high-temperature environments. Combined with the antioxidant's dual free radical capture mechanism, the material's long-term stability under harsh conditions such as high temperature and sunlight is significantly improved.

[0037] 3. Excellent Surface Functionality and Processing Performance: The combination of antistatic agents and lubricants creates a charge-conducting network and a uniform lubricating layer on the film surface, reducing surface resistance and friction coefficient, while enhancing antistatic properties and smooth processing. Furthermore, the silica surface modifier further optimizes the film's compatibility with other materials, meeting the demands of high-precision processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 For the antioxidant 1 of the present invention 1 HNMR spectrum. DETAILED DESCRIPTION

[0039] The following will clearly and completely describe the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all 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.

[0040] Synthesis example one

[0041] Synthesis of antioxidant 1:

[0042] ;

[0043] The first step: Under a nitrogen atmosphere, 25 g of raw material 1, 19.09 g of raw material 2, 19.29 g of anhydrous potassium carbonate, 2.42 g of tetrakis(triphenylphosphine)palladium and 300 g of a mixed solution of toluene, ethanol and water mixed in a volume ratio of 2:1:1 were added to the reaction system, heated to 95 ° C and refluxed for 10 hours, turned off the heating, cooled to room temperature, allowed to stand and separated, the aqueous phase was extracted twice with ethyl acetate, the organic phases were combined, the organic phases were dried over anhydrous magnesium sulfate, filtered, and dried, and silica gel column chromatography was performed using a mixture of petroleum ether and ethyl acetate as eluent, and dried to obtain 25.95 g of intermediate 1.

[0044] Step 2: Under a nitrogen atmosphere, 25.95 g of intermediate 1, 18.63 g of raw material 3, 29.95 g of potassium phosphate trihydrate, 0.06 g of pyridine-2-carboxylic acid, 0.55 g of CuI and 300 g of DMSO were added to the reaction system, and the mixture was heated to 85°C and reacted for 16 hours; after cooling, the reaction mixture was extracted with an ammonia solution and methyl tert-butyl ether, and the organic phase was washed five times with water and twice with a saturated NaCl solution; finally, the combined organic phase was dried over anhydrous Na2SO4, spin-dried, and purified on a silica gel column, using a mixed solution of petroleum ether and ethyl acetate as eluent, and the solution was spin-dried to obtain 30.53 g of antioxidant 1.

[0045] Structure identification:

[0046] MS (m / z) of intermediate 1: [M+H] + =462;

[0047] MS (m / z) of antioxidant 1: [M+H] + =657;

[0048] Antioxidant 1 1 HNMR-CDCl3: δ8.24-8.11(m,5H),7.99-7.84(m,4H),7.62-7.46(m,8H),7.24-7.01

[0049] (m,6H),6.99-6.85(m,1H),6.89-6.77(m,3H),6.30(s,1H),4.17(t,2H),2.93(m,2H).

[0050] Synthesis Example 2 - Synthesis Example 4

[0051] In Synthesis Examples 2-4, antioxidants 2-4 were synthesized in sequence, referring to the synthesis method of Synthesis Example 1, replacing raw material 2, and remaining the same as Synthesis Example 1. Specific structures of raw material 2, antioxidants 2-4, and MS (m / z): [M+H] + See Table 1 for data.

[0052] Table 1 Structure of raw material 2, antioxidant 2-antioxidant 4 involved in Synthesis Example 2-Synthesis Example 4, MS (m / z): [M+H] +

[0053] data

[0054]

[0055] Example 1

[0056] Preparation of a low melt index high molecular weight composite copper foil PP film:

[0057] 1. Raw material ratio: 100 parts of low melt index polypropylene resin (melt index is 1.5g / 10min (230℃ / 2.16kg), molecular weight 380,000), nucleating agent (organic phosphate nucleating agent NA-21) 0.2 parts, slipping agent (erucamide) 0.5 parts, antistatic agent (dodecyltrimethylammonium chloride) 0.8 parts, surface modifier (silicon dioxide) 0.05 parts, antioxidant (antiaging agent 1 synthesized in Synthesis Example 1) 2 parts, copper foil with a thickness of 8μm.

[0058] 2. Preparation method:

[0059] S1. The low melt index polypropylene resin, nucleating agent, slip agent, antistatic agent, surface modifier and antioxidant were added in parts by mass ratio to a high-speed mixer and mixed at 800 rpm for 15 minutes until uniform to obtain a premix;

[0060] S2. The premix was added to a twin-screw extruder and the process parameters were set: melt extrusion temperature was controlled in sections: zone 1 at 210°C, zone 2 at 220°C, zone 3 at 225°C, and die head at 230°C; screw speed was 80 rpm; the melt was cast through a T-die, the cooling roll temperature was 25°C, and a PP film with a thickness of 4.0 μm was obtained;

[0061] S3. The PP film was laminated with an 8-μm-thick electrolytic copper foil and placed in a hot press for lamination: the hot pressing temperature was 135°C, the pressure was 1.5 MPa, and the holding time was 45 seconds. After lamination, the film was immediately cooled to room temperature to obtain a low-melt index, high-molecular-weight composite copper foil PP film.

[0062] Example 2-Example 4

[0063] A low melt index, high molecular weight composite copper foil PP film was prepared by referring to the preparation method of Example 1, wherein the antioxidant was replaced with antioxidant 2 to antioxidant 4 synthesized in Synthesis Examples 2 to 4 in sequence, and the rest remained the same as Example 1.

[0064] Comparative Example 1

[0065] A low melt index high molecular weight composite copper foil PP film was prepared by referring to the preparation method of Example 1, except that the antioxidant was not added, and the rest of the preparation method was the same as that of Example 1.

[0066] Comparative Example 2

[0067] A low melt index high molecular weight composite copper foil PP film was prepared by referring to the preparation method of Example 1, except that the mass fraction of the low melt index polypropylene resin was replaced with 120 parts, and the rest remained the same as Example 1.

[0068] Comparative Example 3

[0069] A low melt index and high molecular weight composite copper foil PP film was prepared by referring to the preparation method of Example 1, except that the mass fraction of the nucleating agent was changed to 0.01 parts, and the rest remained the same as Example 1.

[0070] Performance testing:

[0071] The tensile strength (MPa), elongation at break (%), and breakdown strength (MV / m) of the low melt index, high molecular weight composite copper foil PP film prepared in the examples and comparative examples were tested with reference to GB / T13542.2-2009. The data are shown in Table 2.

[0072] Table 2 Performance test data of a low melt index high molecular weight composite copper foil PP film prepared in the examples and comparative examples

[0073]

[0074] In the performance test data in Table 2, the overall trend shows that the composite copper foil PP film of the embodiment (using a complete formula and specific antioxidant) is significantly better than the comparative example (missing or unbalanced formula) in tensile strength, elongation at break and breakdown strength. The lack of antioxidant leads to overall deterioration of mechanical and electrical properties, excessive resin causes increased brittleness and weakens ductility and insulation, and insufficient nucleating agent significantly reduces heat resistance and mechanical strength due to crystallization defects. Although different types of antioxidants bring subtle differences, they can all synergistically improve the comprehensive stability of the material, confirming the core role of optimizing formula components in solving delamination, aging and insulation defects.

[0075] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A low melt index high molecular weight composite copper foil PP film, characterized in that: The invention comprises a copper foil and a PP film. The PP film is made of the following raw materials in parts by weight: 100 parts of a low melt index polypropylene resin, 0.05-0.5 parts of a nucleating agent, 0.1-1.0 parts of a slip agent, 0.3-1.2 parts of an antistatic agent, 0.01-0.1 parts of a surface modifier, and 1-3 parts of an antioxidant. The antioxidant has a structure shown in Formula 1: Formula 1; Said Z1 is selected from: O, S, N(H), C(CH3)2; The nucleating agent is an organic phosphate nucleating agent NA-21; The structure of the organophosphate nucleating agent NA-21 is: 。 2. The low melt index high molecular weight composite copper foil PP film according to claim 1, characterized in that: The low melt index polypropylene resin has a melt index of 0.5-2 g / 10 min 230° C. / 2.16 kg and a molecular weight of ≥350,000.

3. The low melt index high molecular weight composite copper foil PP film according to claim 1, characterized in that: The lubricant is erucamide.

4. The low melt index high molecular weight composite copper foil PP film according to claim 1, characterized in that: The antistatic agent is dodecyltrimethylammonium chloride; the surface modifier is silicon dioxide.

5. The low melt index high molecular weight composite copper foil PP film according to claim 1, characterized in that: The antioxidant is any one of the compounds shown in the following structures: 。 6. A method for preparing a low melt index high molecular weight composite copper foil PP film according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. The low melt index polypropylene resin, nucleating agent, slip agent, antistatic agent, surface modifier and antioxidant are uniformly mixed in parts by mass ratio to obtain a premix; S2. The premix is ​​added to a twin-screw extruder, melt-extruded at a melt temperature of 200-240 ℃, and a PP film is prepared by a casting process; S3. Compounding the PP film and the copper foil by a hot pressing process, with a hot pressing temperature of 120-150° C. and a pressure of 1.0-2.0 MPa, and cooling to obtain a low melt index high molecular weight composite copper foil PP film.

7. The method for preparing a low melt index high molecular weight composite copper foil PP film according to claim 6, characterized in that: The melt extrusion temperature in S2 is 210-230° C., and the screw speed of the twin-screw extruder is 50-100 rpm.

8. The method for preparing a low melt index high molecular weight composite copper foil PP film according to claim 6, characterized in that: The hot pressing lamination process in S3 lasts for 30-60 seconds, and the copper foil has a thickness of 5-10 μm.

9. The method for preparing a low melt index high molecular weight composite copper foil PP film according to claim 6, characterized in that: The cooling method is air cooling to room temperature.

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