Full-bio-based thin film, preparation method thereof and application of full-bio-based thin film in flexible copper-clad plate

Abstract

The invention relates to a full-bio-based film, a preparation method thereof and application of the full-bio-based film in a flexible copper-clad plate, and belongs to the technical field of high polymer materials. According to the invention, tung oil maleic anhydride and bio-based diamine are subjected to polycondensation to obtain a polyamide acid solution, and then the polyamide acid solution is subjected to high-temperature imidization to obtain the full-bio-based polyimide film. The tung oil maleic anhydride and the bio-based diamine are both from renewable resources, the dependence of traditional petroleum-based polyimide on fossil resources is overcome, and the polyimide is green and sustainable. The tung oil molecule contains unsaturated long-chain alkyl, the bio-based diamine contains a flexible aliphatic chain or a natural structural unit, and the flexibility and hydrophobicity of the film are remarkably improved after the molecular chain is introduced. Compared with the traditional petroleum-based polyimide film, the full-bio-based film disclosed by the invention has the advantages that the folding resistance of 180-degree bending is increased to 10 W times or more, the hydrophobicity is excellent, and the folding resistance and the flexibility are obviously higher; meanwhile, the full-bio-based thin film is good in thermal stability and insulativity and can be used as a middle insulating layer of a flexible copper-clad plate.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a fully bio-based thin film, its preparation method, and its application in flexible copper-clad laminates. Background Technology

[0002] Flexible copper clad laminate (FCCL) is an important substrate for flexible circuits, and its core lies in the intermediate insulating layer material. Most commercially available flexible copper clad laminates use petroleum-based polyimide film as the matrix material, which has good heat resistance, insulation and mechanical properties, but has the following shortcomings: (1) Non-renewable resources: Traditional polyimide is mainly derived from petrochemical raw materials, which does not meet the requirements of green and sustainable development; (2) Excessive rigidity of molecular chains: Petroleum-based polyimide molecular chains contain a large number of aromatic rigid units, which makes the material prone to cracking during bending and has insufficient bending resistance, limiting its use in high bending applications such as flexible displays and wearable electronics; (3) Environmental problems: Petroleum-based synthesis and processing have large carbon emissions and environmental burden.

[0003] Therefore, there is an urgent need to develop a novel all-bio-based polyimide film that is renewable in origin, has flexible molecular chains, and possesses excellent bending resistance, to replace the matrix material of existing flexible copper-clad laminates. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a fully bio-based thin film, its preparation method, and its application in flexible copper clad laminates.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a fully bio-based film, which is obtained by thermal imidization reaction of polyamic acid generated by polycondensation of tung oil maleic anhydride (TODA) and bio-based diamine. The bio-based diamine is one or more of the following: bio-based decanediamine, bio-based butylenediamine, bio-based pentanediamine, bio-based hexamethylenediamine, or Priamine (UK Croda).

[0006] This invention prepares a polyamic acid solution through a polycondensation reaction of tung oil maleic anhydride and bio-based diamine, followed by a high-temperature imidization reaction to obtain a fully bio-based polyimide film. The raw materials for preparing this fully bio-based film are renewable; the film possesses a flexible segmental structure, exhibiting excellent bending resistance, good thermal stability, and insulation properties, making it suitable as an intermediate insulating layer in flexible copper-clad laminates.

[0007] In a preferred embodiment of the all-bio-based thin film of the present invention, the Priamine is Priamine 1075.

[0008] In a preferred embodiment of the fully bio-based thin film of the present invention, the bio-based diamine is one or more of bio-based butylene diamine, bio-based pentanediamine, or bio-based hexamethylenediamine. Using bio-based butylene diamine, bio-based pentanediamine, or bio-based hexamethylenediamine as the bio-based diamine results in a fully bio-based thin film with better performance.

[0009] As a preferred embodiment of the all-biobased film of the present invention, the tung oil maleic anhydride is obtained by reacting tung oil and excess maleic anhydride in a DA reaction (Diels-Alder reaction) at 140-160°C for 2-6 hours, followed by water washing and purification. The tung oil maleic anhydride prepared by this method has an acid value of 140-170 mg KOH / g and a viscosity of 2000-5000 mPa·s; compared with commercially available tung oil maleic anhydride, this tung oil maleic anhydride has a higher acid value, better film-forming performance, lower viscosity, and better processability.

[0010] As a preferred embodiment of the all-biobased film of the present invention, the tung oil maleic anhydride has an acid value of 140~170mgKOH / g and a viscosity of 2000~5000mPa·s (25℃).

[0011] In a preferred embodiment of the all-bio-based thin film of the present invention, the thickness of the all-bio-based thin film is 25~500μm.

[0012] As a preferred embodiment of the all-bio-based thin film of the present invention, the thermal decomposition temperature of the all-bio-based thin film is not lower than 300°C, but is 435~450°C.

[0013] As a preferred embodiment of the all-bio-based thin film of the present invention, the dielectric strength of the all-bio-based thin film is not less than 100 kV / mm, and is 120~150 kV / mm.

[0014] As a preferred embodiment of the all-bio-based film of the present invention, the all-bio-based film has a folding endurance of not less than 10W (100,000) times when bent at 180°, which is 10~11W times.

[0015] As a preferred embodiment of the all-bio-based film of the present invention, the water absorption rate of the all-bio-based film is less than 0.15%.

[0016] Secondly, the present invention provides a method for preparing the above-mentioned all-bio-based thin film, comprising the following steps: S1. Under a protective gas environment, tung oil maleic anhydride (TODA) and bio-based diamine are mixed and dissolved in a solvent, and the mixture is allowed to react fully to obtain a polyamic acid solution. S2. Cast the polyamic acid solution obtained in step S1 into a film, pre-dry it to obtain a wet film, and keep the wet film at 60~180℃ for 1~4h to fully remove the solvent; then raise the temperature to 280~320℃ and keep it for 1~2h for thermal imidization to obtain a fully bio-based film (fully bio-based polyimide film).

[0017] This invention utilizes tung oil maleic anhydride (TODA) and bio-based diamine to prepare a fully bio-based thin film. Only by using the specific anhydride TODA and the specific bio-based diamine of this invention can a film with better bending resistance be obtained. Simultaneously, the heat treatment step in film formation needs to meet a specific heat treatment temperature range; exceeding this range will reduce the thermal stability, insulation, bending resistance, and flexibility of the film.

[0018] In a preferred embodiment of the preparation method of the present invention, the protective gas in step S1 is nitrogen.

[0019] In a preferred embodiment of the preparation method described in this invention, in step S1, the viscosity of the polyamic acid solution is 800~1500 mPa·s (30℃).

[0020] In a preferred embodiment of the preparation method of the present invention, in step S1, the solvent includes any one of N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), tetrahydrofuran (THF), or chloroform.

[0021] In a preferred embodiment of the preparation method of the present invention, in step S1, the temperature for the full reaction is 10~30℃ and the reaction time is 6~12h.

[0022] In a preferred embodiment of the preparation method described in this invention, in step S1, the molar ratio of the amino group of the bio-based diamine to the anhydride group of tung oil maleic anhydride is 1:1.

[0023] In a preferred embodiment of the preparation method described in this invention, in step S2, the wet film is kept at 80°C for 1 hour, then heated to 120°C for 1 hour, then heated to 150°C for 1 hour, and then heated to 180°C for 1 hour to fully remove the solvent; subsequently, it is heated to 280°C for 1 hour and then heated to 320°C for 1 hour for thermal imidization to obtain a fully bio-based film. Using a stepwise heating method to remove the solvent results in fewer bubbles and facilitates film formation. The two-step thermal imidization allows for more complete imidization, reduces the material's water absorption, and the polyimide can be annealed at 320°C.

[0024] Thirdly, the present invention provides the application of the above-mentioned all-bio-based thin film in the preparation of flexible copper-clad laminates.

[0025] Fourthly, the present invention provides a flexible copper-clad laminate, which is composed of the above-mentioned fully bio-based film and copper foil.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention prepares a polyamic acid solution through the polycondensation reaction of tung oil maleic anhydride and bio-based diamine, followed by a high-temperature imidization reaction to obtain a fully bio-based polyimide film. Both tung oil maleic anhydride and bio-based diamine are derived from renewable resources, overcoming the dependence on fossil resources inherent in traditional petroleum-based polyimides and achieving green sustainability. Furthermore, the tung oil maleic anhydride prepared by this invention is a solution, simplifying the synthesis process compared to traditional solid dianhydride raw materials for polyimides. Tung oil molecules contain unsaturated long-chain hydrocarbon groups, and bio-based diamine contains flexible aliphatic chains or natural structural units; the introduction of these molecular chains significantly improves the flexibility and hydrophobicity of the polyimide film. Compared to traditional petroleum-based polyimide films, the fully bio-based film of this invention exhibits a folding endurance of over 100,000 cycles at 180° without significant cracking or performance degradation, demonstrating significantly higher folding endurance and flexibility. Simultaneously, the fully bio-based film of this invention exhibits good thermal stability and insulation properties, making it suitable as an intermediate insulating layer in flexible copper-clad laminates. Attached Figure Description

[0027] Figure 1 The appearance of the flexible copper-clad laminate prepared in Example 1 of this invention is as follows. Figure 1 As shown; Figure 2 The appearance of the flexible copper-clad laminate prepared in Example 2 of this invention is as follows. Figure 2 As shown; Figure 3 The appearance of the flexible copper-clad laminate prepared in Example 3 of this invention is as follows. Figure 3 As shown. Detailed Implementation

[0028] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0029] Unless otherwise specified, all other materials and reagents used in the examples are commercially available.

[0030] The tung oil maleic anhydride of this invention can be commercially available or prepared in-house. The method for preparing the in-house tung oil maleic anhydride is as follows: tung oil is reacted with excess maleic anhydride at 140-160℃ for 2 hours, and then purified by washing with water to obtain tung oil maleic anhydride (TODA). Commercially available tung oil maleic anhydride (tung oil anhydride) has an acid value range of 115-131 mgKOH / g and a viscosity of 5000-15000 mPa·s at room temperature (25℃); the in-house tung oil maleic anhydride prepared in this invention has an acid value of 140-170 mgKOH / g and a viscosity of 2000-5000 mPa·s at room temperature (25℃). Compared to commercially available anhydride, the in-house tung oil maleic anhydride prepared in this invention has a higher acid value, better film-forming properties, lower viscosity, and better processability.

[0031] Example 1 A fully bio-based thin film for flexible copper-clad laminates and the flexible copper-clad laminate prepared therefrom, wherein the preparation method of the fully bio-based thin film includes the following steps: S1. Under a protective gas environment, tung oil maleic anhydride (TODA) is dissolved in the solvent N-methylpyrrolidone (NMP), and bio-based decanediamine is slowly added dropwise at 10°C. The molar ratio of the amino group of the bio-based decanediamine to the anhydride group of tung oil maleic anhydride is 1:1. The mixture is stirred for 8 hours to obtain a polyamic acid solution with a viscosity of 920 mPa·s (30°C). S2. Cast the polyamic acid solution obtained in step S1 onto a clean glass plate, pre-dry it at room temperature to remove the solvent, and obtain a wet film. Keep the obtained wet film at 80°C for 1 hour, 120°C for 1 hour, 150°C for 1 hour, and 180°C for 1 hour to completely remove the solvent. Then raise the temperature to 280°C and keep it at 320°C for 1 hour to dehydrate and close the polyamic acid ring to form a polyimide film. Peel it off to obtain a fully bio-based film with a thickness of about 20 μm.

[0032] The prepared bio-based thin film is laminated with copper foil on both sides and then hot-pressed to obtain a flexible copper-clad laminate.

[0033] The solvents used in this invention to dissolve TODA include N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), tetrahydrofuran (THF), or chloroform.

[0034] The flexible copper-clad laminate prepared in Example 1 has the following appearance: Figure 1 As shown.

[0035] Example 2 A fully bio-based thin film for flexible copper-clad laminates and the flexible copper-clad laminate prepared therefrom, wherein the preparation method of the fully bio-based thin film includes the following steps: S1. Under a protective gas environment, tung oil maleic anhydride (TODA) is dissolved in the solvent N-methylpyrrolidone (NMP), and bio-based decanediamine is slowly added dropwise at 30°C. The molar ratio of the amino group of the bio-based decanediamine to the anhydride group of tung oil maleic anhydride is 1:1. The mixture is stirred for 8 hours to obtain a polyamic acid solution with a viscosity of 1200 mPa·s (30°C). S2. Cast the polyamic acid solution obtained in step S1 onto a clean glass plate, pre-dry it at room temperature to remove the solvent, and obtain a wet film. Keep the obtained wet film at 60°C for 1 h and at 180°C for 1 h to fully remove the solvent. Then keep it at 320°C for 1 h to dehydrate and close the polyamic acid to form a polyimide film. Peel it off to obtain a fully bio-based film with a thickness of about 20 μm.

[0036] The prepared bio-based thin film is laminated with copper foil on both sides and then hot-pressed to obtain a flexible copper-clad laminate.

[0037] The appearance of the flexible copper-clad laminate prepared in Example 2 is as follows: Figure 2 As shown.

[0038] Example 3 A fully bio-based thin film for flexible copper clad laminates and the flexible copper clad laminate prepared therefrom. The preparation of the flexible copper clad laminate in this embodiment is the same as in Example 1. The only difference between the preparation method of the fully bio-based thin film in this embodiment and that in Example 1 is the difference in the bio-based diamine in step S1. In this embodiment, the bio-based diamine in step S1 of Example 1, bio-based decanediamine, is adjusted to bio-based butanediamine to obtain a fully bio-based thin film with a thickness of about 20 μm.

[0039] The flexible copper-clad laminate prepared in Example 3 has the following appearance: Figure 3 As shown.

[0040] Example 4 A fully bio-based thin film for flexible copper clad laminates and the flexible copper clad laminate prepared therefrom. The preparation of the flexible copper clad laminate in this embodiment is the same as in Example 1. The only difference between the preparation method of the fully bio-based thin film in this embodiment and that in Example 1 is the difference in the bio-based diamine in step S1. In this embodiment, the bio-based diamine in step S1 of Example 1, bio-based decanediamine, is adjusted to bio-based pentanediamine to obtain a fully bio-based thin film with a thickness of about 20 μm.

[0041] Example 5 A fully bio-based thin film for flexible copper clad laminates and the flexible copper clad laminate prepared therefrom. The preparation of the flexible copper clad laminate in this embodiment is the same as in Example 1. The only difference between the preparation method of the fully bio-based thin film in this embodiment and that in Example 1 is the difference in the bio-based diamine in step S1. In this embodiment, the bio-based diamine in step S1 of Example 1, bio-based decanediamine, is changed to bio-based hexamethylenediamine to obtain a fully bio-based thin film with a thickness of about 20 μm.

[0042] Example 6 A fully bio-based thin film for flexible copper clad laminates and the flexible copper clad laminate prepared therefrom. The preparation of the flexible copper clad laminate in this embodiment is the same as in Example 1. The only difference between the preparation method of the fully bio-based thin film in this embodiment and that in Example 1 is the difference in the bio-based diamine in step S1. In this embodiment, the bio-based diamine in step S1 of Example 1, bio-based decanediamine, is adjusted to Priamine1075 (Cromax, UK), to obtain a fully bio-based thin film with a thickness of about 20 μm.

[0043] Comparative Example 1 A fully bio-based thin film for flexible copper clad laminates and the flexible copper clad laminate prepared therefrom, wherein the preparation of the flexible copper clad laminate is the same as in Example 1; the only difference between the preparation method of the fully bio-based thin film and Example 1 is that the acid anhydride in step S1 is different. In this comparative example, the acid anhydride TODA in step S1 of Example 1 is adjusted to pyromellitic dianhydride to obtain a fully bio-based thin film with a thickness of about 20 μm.

[0044] Comparative Example 2 A fully bio-based thin film for flexible copper clad laminates and the flexible copper clad laminate prepared therefrom, wherein the preparation of the flexible copper clad laminate is the same as in Example 1; the only difference between the preparation method of the fully bio-based thin film and Example 1 is that the bio-based diamine in step S1 is different. In this comparative example, the bio-based diamine in step S1 of Example 1, bio-based decanediamine, is adjusted to ethylenediamine to obtain a fully bio-based thin film with a thickness of about 20 μm.

[0045] Comparative Example 3 A fully bio-based thin film for flexible copper-clad laminates and the flexible copper-clad laminate prepared therefrom, wherein the preparation method of the fully bio-based thin film differs from that of Example 1 only in the temperature of the wet film heating treatment in step S2. The preparation method of the fully bio-based thin film in this comparative example includes the following steps: S1, same as step S1 in Example 1; S2. Cast the polyamic acid solution obtained in step S1 onto a clean glass plate, pre-dry it at room temperature to remove the solvent, and obtain a wet film. Keep the obtained wet film at 60°C for 1 h and 120°C for 1 h to completely remove the solvent. Keep it at 260°C for 1 h to dehydrate and close the polyamic acid ring to form a polyimide film. Peel it off to obtain a fully bio-based film with a thickness of about 20 μm.

[0046] The prepared bio-based thin film is laminated with copper foil on both sides and then hot-pressed to obtain a flexible copper-clad laminate.

[0047] Test case Using fully bio-based films and flexible copper-clad laminates from the examples and comparative examples as samples, the water absorption rate, stability, bending performance, peel strength, and voltage resistance of the fully bio-based films were tested.

[0048] Water absorption rate: The water absorption rate of the film was determined according to GB / T 1034-2008 standard.

[0049] Glass transition temperature (Tg): Determined according to the DSC method specified in 2.4.25 of IPC-TM-650.

[0050] Thermal decomposition temperature (T5%): Determined according to the method specified in 2.4.26 of IPC-TM-650. The temperature at which the sample mass decreases to 95% of its initial mass in the thermogravimetric analysis (TGA) curve is taken as T5%.

[0051] Bending resistance test: 180° fold test, bending radius 0.3mm, statistically determined the maximum bending life under no wire breakage.

[0052] Copper clad laminate peel strength: According to IPC-TM-650 2.4.8, the copper foil is stretched vertically by a universal tensile testing machine to detect the force value when the copper foil peels from the substrate, and then its peel strength is calculated.

[0053] Withstand voltage: The dielectric strength of the samples was tested using a Chroma 19073 AC / DC withstand voltage insulation tester from Taiwan, China, in accordance with ASTM D149 standard.

[0054] The film-forming properties, stability, flexural properties, peel strength, and voltage withstand properties of the fully bio-based films in the examples and comparative examples are shown in Table 1. Table 1 Table 1 shows that the fully bio-based film prepared in the embodiments of the present invention has good thermal stability (thermal decomposition temperature >300℃) and insulation properties; at the same time, it has low water absorption (good hydrophobicity) and higher bending cycle count, with the bending cycle count increased to 100,000 times, resulting in better bending resistance and flexibility.

[0055] The results of Example 1 and Comparative Example 1 show that the polyimide film prepared using TODA as an anhydride of the present invention has a significantly higher number of bending cycles, better bending resistance, and better flexibility.

[0056] The results of Example 1 and Comparative Example 2 show that the polyimide film prepared using the bio-based diamine of the present invention has a significantly higher number of bending cycles, better bending resistance, and better flexibility.

[0057] The results of Example 1 and Comparative Example 3 show that the temperature rise during the polyimide film formation process needs to meet specific conditions. Temperatures exceeding the range of the present invention will cause pinholes in the polyimide film and reduce the thermal stability, insulation, bending resistance and flexibility of the polyimide film.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A fully bio-based thin film, characterized in that, The fully bio-based film is obtained by thermal imidization of polyamic acid generated by polycondensation of tung oil maleic anhydride and bio-based diamine. The bio-based diamine is one or more of bio-based decanediamine, bio-based butylenediamine, bio-based pentanediamine, bio-based hexamethylenediamine, or Priamine.

2. The all-bio-based thin film as described in claim 1, characterized in that, The tung oil maleic anhydride was obtained by reacting tung oil and excess maleic anhydride with DA at 140-160℃ for 2-6 hours, followed by water washing and purification. And / or, the bio-based diamine is one or more of bio-based butylene diamine, bio-based pentanediamine, or bio-based hexanediamine.

3. The all-bio-based thin film as described in claim 1 or 2, characterized in that, The thickness of the all-bio-based film is 25~500μm; And / or, the tung oil maleic anhydride has an acid value of 140~170 mgKOH / g and a viscosity of 2000~5000 mPa·s.

4. The all-bio-based thin film as described in claim 1, characterized in that, The thermal decomposition temperature of the all-bio-based thin film is not lower than 300°C; And / or, the dielectric strength of the all-bio-based film is not less than 100 kV / mm; And / or, the fully bio-based film has a folding endurance of not less than 100,000 times when bent at 180°. And / or, the water absorption rate of the all-bio-based film is less than 0.15%.

5. The method for preparing the all-bio-based thin film according to any one of claims 1 to 4, characterized in that, Includes the following steps: S1. Under a protective gas environment, tung oil maleic anhydride and bio-based diamine are mixed and dissolved in a solvent, and the mixture is allowed to react fully to obtain a polyamic acid solution. S2. Cast the polyamic acid solution obtained in step S1 into a film, pre-dry it to obtain a wet film, and keep the wet film at 60~180℃ for 1~4h to fully remove the solvent; then raise the temperature to 280~320℃ and keep it for 1~2h for thermal imidization to obtain a fully bio-based film.

6. The preparation method according to claim 5, characterized in that, In step S1, the protective gas is nitrogen; And / or, in step S1, the viscosity of the polyamic acid solution is 800~1500 mPa·s.

7. The preparation method according to claim 5, characterized in that, In step S1, the solvent includes any one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, or chloroform; And / or, in step S1, the temperature for the full reaction is 10~30℃, and the reaction time is 6~12h.

8. The preparation method according to claim 5, characterized in that, In step S1, the molar ratio of the amino group of the bio-based diamine to the anhydride group of tung oil maleic anhydride is 1:

1.

9. The use of the all-bio-based thin film according to any one of claims 1 to 4 in the preparation of flexible copper-clad laminates.

10. A flexible copper-clad laminate, characterized in that, It is composed of a fully bio-based thin film as described in any one of claims 1 to 4 and a copper foil.

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