Black thermoplastic polyimide as well as preparation method and application thereof

Abstract

The invention discloses black thermoplastic polyimide as well as a preparation method and application thereof, and relates to the technical field of polyimide. The invention discloses thermoplastic polyimide with a novel structure, the structure of the thermoplastic polyimide is as follows: diamine is ABABP and PNDA; dianhydrides BPTME and BPDA are used as raw materials. According to the preparation method disclosed by the invention, PNDA containing a chromophore group imino group (-N-H-) is selected, and the thermoplastic polyimide with black appearance is prepared under the condition that a black filler is not used. # imgabs0 #

Description

Technical Field

[0001] The invention relates to the technical field of polyimide, in particular to a black thermoplastic polyimide and a preparation method and application thereof. Background Art

[0002] Flexible copper clad laminate (FCCL) is an important application form in the field of flexible circuits in flexible electronic technology, mainly composed of a conductor (such as a copper foil layer) and an organic insulating substrate. Since FCCL has very strict requirements in practical applications, the organic insulating base film needs to have excellent heat resistance, insulation, mechanical properties, dielectric properties, adhesion, and low cost.

[0003] Polyimide (PI) is a super engineering polymer material containing an imide ring structure. Its highly conjugated molecular chain structure, strong intra- and inter-molecular chain interactions, high bond energy of CN bonds and C=O bonds, and high polarity give it a variety of excellent properties that can meet the strict requirements of organic insulating base films.

[0004] The traditional FCCL manufacturing process is the "three-layer method", which is to use adhesives to compound the film and copper foil together. However, the use of traditional adhesives such as polyacrylates and epoxy resins will cause the heat stability of FCCL to deteriorate, and increase the thickness and dielectric constant of FCCL, so the "two-layer method" came into being. The two-layer process uses thermoplastic PI (TPI) instead of traditional adhesives. Since the commercialization of PI core film is relatively high, the core point of this process lies in the research and development of TPI film. Ester bonds have good heat resistance, good hydrophobicity, good orientation, good adhesion to the substrate, and low dielectric loss. Therefore, TPI has good application prospects in the field of two-layer FCCL.

[0005] In addition, due to the considerations of reducing the corrosion of copper foil by light, protecting intellectual property rights, and aesthetics, special FCCL has received more and more attention. Among them, black PI (BPI) film has attracted much attention due to its excellent light-shielding, radiation resistance, corrosion resistance, thermal stability, flame retardancy and other properties. The traditional preparation method of BPI is to add black fillers such as carbon black to the polyamic acid (PAA) solution, but the black filler has conductive properties and may agglomerate, which will cause the conductivity of PI to increase and the insulation rate to decrease. Moreover, the traditional method generally uses non-thermoplastic polyimide with very low toughness, which also greatly affects the material properties and service life of PI.

[0006] Chinese patent CN107250277A discloses a composition for forming a peeling layer, which comprises a polyamic acid obtained by reacting an aromatic diamine with an aromatic tetracarboxylic dianhydride, and an organic solvent, wherein the aromatic diamine comprises an aromatic diamine containing at least one of an ester bond and an ether bond, and / or the aromatic tetracarboxylic dianhydride contains at least one of an ester bond and an ether bond. The polyamic acid disclosed in the patent is not a black polyamic acid and does not have properties such as light-shielding property, radiation resistance, corrosion resistance, thermal stability, and flame retardancy.

[0007] In view of this, in order to solve the shortcomings of the prior art culture method, the present invention provides a black thermoplastic polyimide and a preparation method and application thereof. Summary of the invention

[0008] The purpose of the present invention is to provide a black thermoplastic polyimide and a preparation method and application thereof. The prepared thermoplastic polyimide has a black appearance, good thermoplasticity, excellent high-temperature dimensional stability and excellent dielectric properties, and can meet the application requirements of two-layer special FCCL.

[0009] To achieve the above-mentioned purpose of the invention, the technical solution of the present invention is as follows:

[0010] In one aspect, the present invention provides a black thermoplastic polyimide, wherein the structure of the thermoplastic polyimide is as shown in the following formula:

[0011]

[0012] Wherein, n is a positive integer;

[0013] Dianhydride is

[0014]

[0015] The diamine is

[0016]

[0017] In another aspect, the present invention provides a method for preparing the above-mentioned black thermoplastic polyimide, comprising the following steps:

[0018] (1) mixing two diamine monomers and a non-protonic strong polar solvent to form a homogeneous solution, and then mixing with two dianhydride monomers to undergo polymerization reaction to obtain a polyamic acid solution;

[0019] (2) After the polyamic acid solution is formed into a film or spun, it is heated and dehydrated into a ring to transform into a black thermoplastic polyimide.

[0020] Preferably, in step (1), the two diamine monomers are 2-(4-aminobenzoate)-5-aminobiphenyl (ABABP) and 4-aminophenyl-2,5-pyridinediamine (PNDA);

[0021] Among them, the structure of ABABP is as follows:

[0022]

[0023] The structure of PNDA is as follows:

[0024]

[0025] Preferably, in step (1), the two dianhydride monomers are biphenyl dibenzoate-3,3',4,4'-tetracarboxylic dianhydride (BPTME) and 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA);

[0026] Among them, the structure of BPTME is as follows:

[0027]

[0028] The structure of BPDA is as follows:

[0029]

[0030] Preferably, in step (1), the aprotic strong polar solvent is N-methylpyrrolidone (NMP).

[0031] Further preferably, in step (1), the molar ratio of BPTME, BPDA, ABABP and PNDA is 2:8:3-4:6-7.

[0032] More preferably, in step (1), the molar ratio of BPTME, BPDA, ABABP and PNDA is 2:8:4:6.

[0033] Preferably, in step (2), the heating procedure is as follows: 80°C / 1h; 120°C / 1h; 150°C / 1h; 180°C / 1h; 250°C / 1h; 300°C / 1h.

[0034] In another aspect, the present invention provides a flexible copper-clad laminate comprising copper foil and the above-mentioned black thermoplastic polyimide.

[0035] Finally, the present invention provides application of the black thermoplastic polyimide in a flexible circuit.

[0036] The beneficial effects of the present invention are:

[0037] (1) The present invention uses PNDA containing a chromogenic group imino group (-NH-) to prepare a thermoplastic polyimide with a black appearance without using a black filler.

[0038] (2) Compared with the thermoplastic polyimide materials prepared by TMBPA, BPDA, APAB and TFMB, the thermoplastic polyimide materials prepared by BPTME, BPDA, PNDA and ABABP in the present invention not only do not contain fluorine, but also have a moderate T g , low dielectric constant, low dielectric loss, lower CTE and excellent high temperature dimensional stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 FTIR spectra of the embodiments and comparative examples of the present invention.

[0040] Figure 2 DMA spectra of the embodiments of the present invention and the comparative examples.

[0041] Figure 3 The TMA spectra of the embodiments and comparative examples of the present invention are shown in FIG.

[0042] Figure 4 The TGA-DTG spectra of the embodiments and comparative examples of the present invention are shown in FIG. DETAILED DESCRIPTION

[0043] The following non-limiting examples can enable those skilled in the art to more fully understand the present invention, but do not limit the present invention in any way. The following content is only an exemplary description of the scope of the present invention, and those skilled in the art can make various changes and modifications to the invention of the present invention based on the disclosed content, and they should also fall within the scope of the present invention.

[0044] The present invention is further described below by way of specific examples. The various chemical reagents used in the examples of the present invention are obtained through conventional commercial channels unless otherwise specified. Unless otherwise specified, the contents described below are all weight contents. Unless otherwise specified, it is understood that the process is carried out at room temperature.

[0045] The structure of BPTME is as follows:

[0046]

[0047] The structure of BPDA is as follows:

[0048]

[0049] The structure of ABABP is as follows:

[0050]

[0051] The structure of PNDA is as follows:

[0052]

[0053] The structure of bisphenol A diether dianhydride (TMBPA) is as follows:

[0054]

[0055] The structure of 4-aminophenyl 4-aminobenzoate (APAB) is as follows:

[0056]

[0057] The structure of 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl (TFMB) is as follows:

[0058]

[0059] Example 1

[0060] A black thermoplastic polyimide film was prepared by a two-step thermal imidization method using BPTME, BPDA, ABABP and PNDA, specifically:

[0061] First, a soluble polyamic acid (PEsAA) precursor was prepared by the polycondensation reaction of the starting monomers, and the specific steps were as follows. PNDA (11.9550 g, 0.06 mol), ABABP (12.1736 g, 0.04 mol) and an appropriate amount of ultra-dry NMP solvent were added to a 250 mL three-necked glass round-bottom flask equipped with a mechanical stirrer, a thermometer, a nitrogen inlet and a cold water bath. The flask was immersed in a cold water bath with an internal temperature below 10 ° C. At the same time, dry nitrogen was filled into the flask, and a transparent diamine solution was obtained after stirring for 30 minutes. Then, BPTME (10.6886 g, 0.02 mol) and BPDA (23.5376 g, 0.08 mol) were added to the diamine solution in sequence, and additional NMP solvent was added to provide a reaction mixture with an initial solid content of 25 wt%. After stirring for 1 h, the cold bath was removed and the reaction temperature gradually reached room temperature. The polymerization was continued for 24 hours to obtain a viscous PEsAA solution. Additional NMP solvent was added to dilute the system to 15 wt% solid content. The diluted PEsAA solution was filtered through a 0.45 μm polytetrafluoroethylene syringe to remove insoluble impurities.

[0062] The purified PEsAA solution was cast onto clean borosilicate glass (150 mm × 100 mm × 3 mm) using a film applicator (AFA-II, Shanghai Meiyu Equipment Co., Ltd., China), and the thickness of the original liquid film was controlled by adjusting the gap distance of the casting knife. Then, the glass substrate was thermally dried in a programmable oven under a nitrogen environment by a heating program of 80°C / 1h, 120°C / 1h, 150°C / 1h, 180°C / 1h, 250°C / 1h, and 300°C / 1h. After heat treatment, the naturally cooled glass substrate was immersed in deionized water. The polyesterimide film was peeled off from the substrate and obtained as a black independent film. After drying at 120°C for 3h, various properties of the film were evaluated.

[0063] Example 2

[0064] A black thermoplastic polyimide film was prepared by a two-step thermal imidization method using BPTME, BPDA, ABABP and PNDA, specifically:

[0065] The film preparation process is the same as that of Example 1, except that the added monomer content is different, and the specific data are shown in Table 1. The obtained film was evaluated for various properties.

[0066] Table 1

[0067]

[0068] Comparative Example 1

[0069] Thermoplastic polyimide film prepared by two-step thermal imidization method using TMBPA, BPDA, APAB and TFMB, specifically:

[0070] The film preparation process is the same as that of Example 1, except for the different monomers added and the monomer contents, and the specific data are shown in Table 2. The obtained films were evaluated for various properties.

[0071] Comparative Example 2

[0072] Thermoplastic polyimide film prepared by two-step thermal imidization method using TMBPA, BPDA, APAB and TFMB, specifically:

[0073] The film preparation process is the same as that of Example 1, except for the different monomers added and the monomer contents, and the specific data are shown in Table 2. The obtained films were evaluated for various properties.

[0074] Table 2

[0075]

[0076] Results test:

[0077] 1. Thin film structure evaluation method

[0078] Fourier transform infrared spectroscopy (FTIR): The prepared film was measured on a Shimadzu Iraffinity-1S Fourier transform infrared spectrometer with a range of 4000-500 cm -1 This test produces an infrared spectrum of the film.

[0079] 2. Thermal performance evaluation method of thin films

[0080] Dynamic Mechanical Analysis (DMA): The prepared films were tested on a TA Q800 thermal analysis system at a heating rate of 5°C / min and a frequency of 1 Hz in nitrogen. This test can obtain the glass transition temperature (T g )data.

[0081] Thermomechanical analysis (TMA): The prepared films were tested on a Netzsch TMA402F3 thermal analysis system at a heating rate of 5°C / min in a nitrogen atmosphere. This test can obtain the linear thermal expansion coefficient (CTE) data of the film.

[0082] Thermogravimetric analysis (TGA) and corresponding derivative TGA (DTG): The prepared films were tested on a Netzsch TG 209F3 thermogravimetric analyzer at a heating rate of 20 °C / min in a nitrogen atmosphere. This test can obtain the 5% weight loss temperature (T 5％ ), the temperature at which the first and second fastest thermal decomposition occurs (T max1 , T max2 ) and the residual weight ratio (R w750 )data.

[0083] 3. Evaluation method of dielectric properties of thin films

[0084] Dielectric properties: Silver electrodes were fabricated on both sides of the PI sample, pre-dried with conductive silver paint at 100°C for 1 hour, and then precisely cut into small pieces (1 cm × 1 cm × 3 mm) and tested at room temperature at a frequency of 10 GHz using an Agilent 4294A precision impedance analyzer. Dielectric constant (D k ) and dielectric loss (D f ) Data were recorded as the average of 5 parallel samples.

[0085] 4. Evaluation method of optical properties of thin films

[0086] Color parameters: The prepared film was measured by an i7 spectrophotometer from X-rite, USA. The color parameters were calculated according to the CIE Lab equation: L * Represents the film brightness, where 100 represents white and 0 represents black; a* Positive values ​​represent red, negative values ​​represent green; b * Positive values ​​represent yellow, negative values ​​represent blue; haze represents fog.

[0087] Table 3

[0088]

[0089] T g : Glass transition temperature; T 5％ : The temperature at which the weight decreases by 5%; T max1 : The temperature at which the first decomposition is fastest; T max2 : The temperature at which the second decomposition is fastest; R w750 : Weight percentage at 750℃; CTE: Coefficient of linear thermal expansion in the range of 100-200℃; D k : Dielectric constant; D f : Dielectric loss.

[0090] Table 4

[0091] sample <![CDATA[L * ]]> <![CDATA[a * ]]> <![CDATA[b * ]]> Haze(%) Example 1 23.74 38.06 40.91 0.00 Example 2 11.21 34.20 19.32 0.08 Comparative Example 1 94.29 -0.95 7.46 0.01 Comparative Example 2 93.95 -1.09 8.77 0.03

[0092] L * Represents the film brightness, where 100 represents white and 0 represents black; a * Positive values ​​represent red, negative values ​​represent green; b * Positive values ​​represent yellow, negative values ​​represent blue; haze represents fog.

[0093] according to Figure 1 As shown in the FTIR spectrum and Table 4, the black polyimide film material was successfully obtained by the preparation method of the present invention. Figure 2 It can be seen from the DMA spectrum that the black polyimide film material prepared by the present invention has good thermoplasticity.

[0094] It can be seen from the data in Table 3 that compared with the thermoplastic polyimide film materials prepared with TMBPA, BPDA, APAB and TFMB in Comparative Examples 1 and 2, the thermoplastic polyimide film materials prepared with BPTME, BPDA, PNDA and PAPAB in Examples 1 and 2 have the characteristics of being fluorine-free, black, and having a moderate T g In addition to low dielectric constant and low dielectric loss, it also has low CTE and excellent high temperature dimensional stability.

[0095] It can be seen that the black thermoplastic polyimide film material prepared by the two-step thermal imidization method proposed in the present invention has excellent comprehensive performance, and the preparation process is simple to operate, the reaction is controllable, and the reaction product is adjustable. This implementation scheme has good industrial prospects in two-layer special FCCL at high frequencies.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A black thermoplastic polyimide, characterized in that: The structure of the thermoplastic polyimide is shown below: Wherein, n is a positive integer; Dianhydride is The diamine is 2. The method for preparing the thermoplastic polyimide according to claim 1, characterized in that: The following steps are involved: (1) mixing two diamine monomers and a non-protonic strong polar solvent to form a homogeneous solution, and then mixing with two dianhydride monomers to undergo polymerization reaction to obtain a polyamic acid solution; (2) After the polyamic acid solution is formed into a film or spun, it is heated and dehydrated into a ring to transform into a black thermoplastic polyimide.

3. The preparation method according to claim 2, characterized in that: In step (1), the two diamine monomers are ABABP and PNDA; Among them, the structure of ABABP is as follows: The structure of PNDA is as follows:

4. The preparation method according to claim 2, characterized in that: In step (1), the two dianhydride monomers are BPTME and BPDA; Among them, the structure of BPTME is as follows: The structure of BPDA is as follows:

5. The preparation method according to claim 2, characterized in that: In step (1), the aprotic strong polar solvent is N-methylpyrrolidone.

6. The preparation method according to any one of claims 3 to 4, characterized in that: In step (1), the molar ratio of BPTME, BPDA, ABABP and PNDA is 2:8:3-4:6-7.

7. The preparation method according to claim 6, characterized in that: In step (1), the molar ratio of BPTME, BPDA, ABABP and PNDA is 2:8:4:

6.

8. The preparation method according to claim 2, characterized in that: In step (2), the heating procedure is as follows: 80°C / 1h; 120°C / 1h; 150°C / 1h; 180°C / 1h; 250°C / 1h; 300°C / 1h.

9. A flexible copper-clad laminate, characterized in that: The invention comprises copper foil and the black thermoplastic polyimide as claimed in claim 1.

10. Use of the black thermoplastic polyimide according to claim 1 in flexible circuits.

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