A polyamide-imide film and a method for producing the same

Abstract

A kind of polyamide-imide film and its preparation method, raw materials include: aromatic diamine 85-115 parts;Dianhydride monomer 21-39 parts;Acyl chloride monomer 63-89 parts;The acyl chloride monomer includes diacyl chloride monomer and triacyl chloride monomer, and the molar ratio of triacyl chloride monomer and diacyl chloride monomer is 1% to 10%.Conformational distortion but structural rigidity structure is introduced in the molecular chain segment of polyimide, and optical performance and heat resistance are improved;By introducing amide bond in molecular structure through acyl chloride monomer, the mechanical properties and surface hardness of product are improved;Polyamide acid is mixed with chemical reagent directly on support to form film and film forming method of chemical imidization, the dimensional stability of product is improved, and production efficiency and raw material utilization rate are also improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of polymer film, and particularly relates to a polyamide-imide film and a preparation method thereof. BACKGROUND

[0002] In recent years, with the development of electronic devices towards flexibility, large size and ultra-thinness, high-transparency plastic substrates have attracted extensive attention due to their advantages of flexibility, light weight, high impact resistance, and roll-to-roll production, etc. for replacing traditional glass cover plates to prepare portable large-area flexible displays that can be bent or folded. The currently commercialized polycarbonate (PC), polyethylene naphthalate (PEN), polyether sulfone (PES) and polyethylene terephthalate (PET) films, although have excellent optical transparency and low yellowness index, have many disadvantages such as poor dimensional stability, low heat resistance and large thermal expansion coefficient, etc., which cannot meet the use requirements of such flexible displays and protection of display device components.

[0003] Polyimide refers to a kind of polymer whose molecular structure is composed of aromatic rings and imide rings. Due to its strong structural rigidity, high packing density, large chain segment movement resistance, and wide molecular and intermolecular electron cloud conjugation effect, it has high strength and modulus, high temperature oxidation resistance, radiation resistance, and good electrical insulation performance, and is widely used in aerospace, electronics, machinery, chemical industry and gas separation fields. However, this kind of polyimide material with dense structure and strong intermolecular force presents golden yellow or brown color, and its film has a transmittance of less than 40% at a wavelength of 500 nm, which limits its application in the field of optoelectronics, such as Kapton and Upilex films. According to the density functional theory (DFT) molecular orbital theory, the coloring mechanism of polyimide is mainly due to the electron transition from the highest occupied orbital (HOMO) and the near orbital group below it (i.e. the diamine part) to the lowest unoccupied orbital (LμmO) and the near orbital group above it (i.e. the anhydride part), forming an intramolecular and intermolecular charge transfer complex (CTC). Therefore, there are mainly two methods for preparing transparent polyimide films at present: 1. selecting aliphatic or semi-aliphatic polyimide structure to block the formation of CTC; 2. selecting aromatic diamine containing fluorine or sulfone group, reducing the electron-donating ability of diamine, or twisting the structure or large space volume of aromatic monomer, reducing the electron cloud density, and widening the band gap difference between HOMO and LμmO to inhibit the formation of CTC.

[0004] In the molecular structure of aliphatic polyimide, HOMO is the lone pair n orbital containing carboxyl group, LμmO is the π* orbital extended in the anhydride part, so the aliphatic HOMO→LUNO transition belongs to n→π* transition, which can directly block the formation of CTC, but due to the large decline of heat resistance, Young's modulus and surface hardness of aliphatic polyimide, semi-aliphatic structure is usually adopted. For example, CN100528965C, CN101160202B, CN101674923B and CN104704057B mainly select semi-aliphatic structure with 1,2,4,5-cyclohexane tetracarboxylic acid as dianhydride to prepare various colorless and transparent polyimide films. Patents CN107356989A and CN107443645A use bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride to prepare semi-aliphatic transparent polyimide film; CN102369233B reports the preparation of semi-aliphatic transparent polyimide using cyclohexanediamine; US20150284513A1, US20150307662A1, US20170313821A1 and US20170342215A1 also use various aliphatic dianhydride or diamine monomers to prepare semi-aliphatic transparent polyimide film. The optical performance of polyimide with aliphatic structure is very excellent, but the aliphatic molecular structure is too distorted, the molecular chain is loosely packed, and there are more methylene groups, resulting in lower heat resistance, higher thermal expansion coefficient, especially lower Young's modulus (≤4GPa) and surface hardness, and poorer high-temperature yellowing resistance, which is still difficult to meet the requirements of comprehensive performance of flexible cover plate. Another path is to select aromatic diamines containing strong polar functional groups such as fluorine or sulfone groups, or aromatic monomers with large free volume and large steric hindrance, to prepare high-transparency polyimide film by inhibiting the formation of CTC. Domestic and foreign technical personnel have carried out a lot of research and reports, and the more typical ones are to use 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB) as diamine and 2,2'-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) containing hexafluoroisopropyl (twisted structure) to jointly inhibit the formation of CTC within and between the molecular chains, achieve high light transmittance and low yellowness index. At the same time, 4,4'-biphenyl tetracarboxylic dianhydride (4,4'-BPDA) with partial rigidity is added to balance the mechanical properties, such as CN101827882A, CN105646919A, CN102159628A, CN102918088A and CN104761899A. By adjusting the ratio of 6FDA and 4,4'-BPDA, polyimide film with high light transmittance and low yellowness index can be prepared, but it is difficult to balance the comprehensive performance. When the excellent optical performance is met, the mechanical properties show low Young's modulus and surface hardness, and the linear thermal expansion coefficient is too large.To this end, many researchers have made improvements and optimizations, mainly in two ways: adding nano-inorganic fillers and introducing hydrogen bonding of amide structure. Inorganic nano-fillers can improve the overall performance of the film due to their rigidity and size stability. For example, patents CN107356989A, CN107683308A, CN104411744A and CN106661273A all report research on this. Most of them use nano-silica as the filler, and the resulting inorganic-organic hybrid film has significantly improved Young's modulus, surface hardness and scratch resistance. However, due to the small particle size of nano-fillers, it is difficult to disperse uniformly, and the effect is not obvious when the amount is small, and the amount is large. Local agglomeration easily occurs, which strongly scatters light, resulting in a decrease in light transmittance, an increase in yellowness index and haze. The other way is to introduce amide structure into the polyimide molecular chain segment. Amide groups can produce strong hydrogen bonding forces, and straight-chain amide bonds can form high orientation or microcrystalline structures, similar to physical cross-linking points, which can improve the size stability and surface scratch resistance of polyimide films. At the same time, it also avoids the problem of difficulty in dispersing inorganic fillers uniformly. For example, patents CN104854173A, CN105103100A, CN105121159A and CN107428962A mainly introduce amide groups into the molecular chain structure by adding terephthaloyl chloride (TPC) or isophthaloyl chloride (IPC) monomers during polymerization. Patents CN107356998A, CN108373543A, CN110408061A and CN110408062A introduce amide bonds into the polyimide molecular chain by adding terephthaloyl chloride (TPC) and 4,4'-oxybis(benzoyl chloride) (OBBC) two acyl chloride monomers, and also adding nano-silicon dioxide to improve the mechanical properties of the film. Patents CN109071814A, CN110177824A, CN110268004A, CN110300773A and CN110325568A introduce amide bonds by combining terephthaloyl chloride (TPC) with 1,1'-biphenyl-4,4'-dicarbonyl dichloride (BPDC) or 2,6-naphthalene dicarboxylic chloride (NADOC) in the polyimide molecular chain. Replacing 4,4'-BPDA in the conventional TFMB-6FDA-4,4'-BPDA ternary structure with TPC, IPC, OBBC, BPDC and NADOC, which can improve the mechanical properties of the film, can significantly improve the Young's modulus and surface hardness of the film, and can reduce the linear thermal expansion coefficient.However, the amide bonds formed by copolymerizing these several diacyl chloride monomers into the molecular chain segment also reduce the optical performance of the polyimide film, especially the yellowness index. For example, in TPC and BPDC, the carbonyl groups on the left and right sides will produce p-p conjugation effect with the benzene ring in the middle, and the amide bond is densely packed, the local electron cloud density increases, the CTC effect is obvious, which causes the color to deepen and the light transmittance to decrease. The same is true for OBBC, as reported in patent CN108373543A, which needs to use a bluing agent to balance the excessively high yellowness. In addition, the above-mentioned report uses TPC to replace part of 4,4'-BPDA, because the combination of TPC and TFMB has a more compact structure than the combination of 4,4'-BPDA and TFMB, and the straightness of the molecular chain is too high. It is very difficult to pour the solution after the polyamic acid is added with a dehydrating agent and a catalyst into a poor solvent to form a powder, directly forming a semi-gel flexible filament, which is difficult to crush and wash clean, and has an adverse effect on the optical indicators of the subsequent film. Moreover, the two-step method of first forming a powder and then coating a film will consume a large amount of washing solvent, and there will be a loss of polyimide, increasing the production cost. SUMMARY

[0005] The technical problem to be solved by the present application is that the polyimide or polyamide-imide film cannot simultaneously consider the optical performance, thermal performance and mechanical performance, and overcome the deficiencies and defects mentioned in the above background art. The present application provides a polyamide-imide film and a preparation method thereof.

[0006] To solve the above technical problems, the technical solution provided by the present application is:

[0007] A polyamide-imide film, comprising the following molar parts of raw materials:

[0008] 85-115 parts of aromatic diamine;

[0009] 21-39 parts of dianhydride monomer;

[0010] 63-89 parts of acyl chloride monomer;

[0011] The acyl chloride monomer includes diacyl chloride monomer and triacyl chloride monomer, and the molar ratio of the triacyl chloride monomer to the diacyl chloride monomer is 1%-10%.

[0012] The amide bonds formed by copolymerizing the acyl chloride monomer into the molecular chain segment will reduce the optical performance of the polyimide film, especially the yellowness index, and the amide bond is densely packed, the local electron cloud density increases, the CTC effect is obvious, which causes the color to deepen and the light transmittance to decrease. In order to further improve the mechanical performance, especially the Young's modulus and hardness of the film, a small amount of triacyl chloride monomer is contained in the acyl chloride monomer of the present application to form a small amount of local cross-linked network structure, and the ratio of the triacyl chloride monomer to the diacyl chloride monomer is adjusted. If the amount of triacyl chloride monomer added is small, the optical performance is poor, and if the amount is large, it will affect other performances.

[0013] The diacyl chloride monomers include commercial diacyl chloride monomers and / or diacyl chloride monomers prepared by conversion of aromatic diamines, wherein the commercial diacyl chloride monomers include one or more of oxalyl dichloride, malonyl dichloride, succinyl dichloride, glutaryl dichloride, adipoyl dichloride, 2,2,3,3,4,4-hexafluoroglutaroyl dichloride, or 2,2'-oxydibenzoic dichloride;

[0014] Preferably, the diacyl chloride monomers include commercial diacyl chloride monomers and / or diacyl chloride monomers prepared by conversion of aromatic diamines, wherein the diacyl chloride monomers prepared by conversion of aromatic diamines include one or more of 1,4-benzenedicarbonyl dichloride, 1,3-benzenedicarbonyl dichloride, 4,4'-dicarbonyl-2,2'-bistrifluoromethyl diphenyl, 2-trifluoromethyl-p-terephthaloyl dichloride, 2,5-bis(trifluoromethyl)-p-terephthaloyl dichloride, tetrafluoro-p-terephthaloyl dichloride, 2,2',6,6'-tetrafluorobiphenyl dicarboxylic dichloride, octafluorobiphenyl dicarboxylic dichloride, 4,4'-(hexafluoroisopropylidene)benzene dicarboxylic dichloride, 4,4'-dicarbonyldiphenyl sulfone, 4,4'-dicarbonyldiphenyl sulfide, or 4,4'-dicarbonyldiphenyl ether; and the triacyl chloride monomers include 1,3,5-benzenetricarbonyl dichloride and / or 1,3,5-benzenetricarbonyl chloride.

[0015] The diacyl chloride monomers are mainly prepared by conversion of aromatic diamines with strong electron-withdrawing effect through certain methods, and the formation of CTC is inhibited by reducing the charge density of local chain segments of the polyamide, so that the good mechanical properties of the film are realized while the excellent overall optical properties, especially the yellowness index, are ensured.

[0016] Preferably, the polyamide-imide film raw material further includes terephthaloyl dichloride and / or 1,1'-biphenyl-4,4'-dicarbonyl dichloride, which is used in copolymerization and mixing with the diacyl chloride monomers.

[0017] In TPC and BPDC, the carbonyl groups on the left and right sides will produce p-π-p conjugation effect with the benzene ring in the middle, and the amide bond is dense, the local electron cloud density increases, the CTC effect is obvious, which leads to deepening of color and decrease of light transmittance. After being combined with the diacyl chloride monomers selected in the application, the Young's modulus and surface hardness of the film can be obviously improved, and the linear thermal expansion coefficient can be reduced.

[0018] Preferably, the diacyl chloride monomers prepared by conversion of aromatic diamines include at least one of 4,4'-diamino-2,2'-bistrifluoromethyl diphenyl, 1,4-diaminobenzotrifluoride, 2,5-bis(trifluoromethyl)-p-phenylenediamine, tetrafluoro-m-phenylenediamine, 2,2',6,6'-tetrafluorobiphenylamine, octafluorobiphenylamine, 4,4'-(hexafluoroisopropylidene)diphenylamine, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfide, or 4,4'-diaminodiphenyl ether.

[0019] The diacyl chloride monomers can also be made using commercially available diacyl chlorides. Some of the commercially available diacyl chloride molecular structures and non- commercial diacyl chloride preparation routes are as follows:

[0020] 1. Commercially available aliphatic diacyl chlorides with high optical performance indices such as:

[0021]

[0022]

[0023] 2. Using aromatic diamines, reducing the p-π conjugation effect of carbonyl and benzene ring in acyl chloride, inhibiting the formation of CTC, synthesizing new aromatic diacyl chlorides such as:

[0024] 4,4'-diamino-2,2'-bistrifluoromethyl diphenyl is converted into 4,4'-diacyl chloride-2,2'-bistrifluoromethyl diphenyl

[0025]

[0026] 1,4-diaminobenzene is converted into 2-trifluoromethyl-terephthaloyl chloride

[0027]

[0028] 2,5-bis(trifluoromethyl) p-phenylenediamine is converted into 2,5-bis(trifluoromethyl) terephthaloyl chloride

[0029]

[0030] tetrafluoro-m-phenylenediamine is converted into tetrafluoro-terephthaloyl chloride

[0031]

[0032] 2,2',6,6'-tetrafluorobenzidine is converted into 2,2',6,6'-tetrafluorobenzene dicarboxylic acid dichloride

[0033]

[0034] octafluorobenzidine is converted into octafluorobenzene dicarboxylic acid dichloride

[0035]

[0036] 4,4'-(hexafluoroisopropylidene)dianiline is converted into 4,4'-(hexafluoroisopropylidene) benzene dicarboxylic acid dichloride

[0037]

[0038] 4,4'-diaminodiphenyl sulfone is converted into 4,4'-diacyl chloride diphenyl sulfone

[0039]

[0040] 4,4'-diaminodiphenyl sulfide is converted to 4,4'-dichlorodiphenyl sulfide

[0041]

[0042] 4,4'-diaminodiphenyl ether is converted to 4,4'-dichlorodiphenyl ether

[0043]

[0044] Preferably, the aromatic diamine comprises one or more of 1,4-cyclohexane diamine (CHDA), bis(amino methyl) bicyclo[2.2.1]heptane, 4-(4- aminobenzyl)cyclohexylamine, 4,4'-diaminodicyclohexylmethyl methane, 3,3-dimethyl-4,4'-diaminodicyclohexyl methane, 4,4'-diamino-2,2'- bis(trifluoromethyl) biphenyl, 3,3'-diamino-2,2'-bis(trifluoromethyl) biphenyl, 1,4- diaminobenzotrifluoride, 2,5-bis(trifluoromethyl) p-phenylenediamine, tetrafluoro-m- phenylenediamine, 2,2',6,6'-tetrafluorobenzidine, octafluorobenzidine, 4,4'- (hexafluoroisopropylidene)dianiline, 3,3'-(hexafluoroisopropylidene)dianiline, 9,9- bis(3-fluoro-4-aminophenyl)fluorene, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl propane, 3,3'-dichlorobenzidine, 4,4'-diaminodiphenyl methane, 3,3'- diaminodiphenyl sulfone, 1,3-diaminobenzene, 4,4'-diaminodiphenyl silane, or 3,3'- diaminodiphenyl ether.

[0045] Preferably, the dianhydride monomer comprises one or more of cyclobutane tetraacid dianhydride, cyclopentane tetraacid dianhydride, cyclohexane tetraacid dianhydride, bicyclo[2.2.1]heptane-2,3,5,6-tetraoic dianhydride, bicyclo[2.2.2]octane-2,3,5,6-tetraoic-2,3,5,6-dianhydride, pyromellitic dianhydride, 2,3',3,4'-biphenyl tetraacid dianhydride, 3,3',4,4'-biphenyl tetraacid dianhydride, 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride, 3,3',4,4'-diphenyl sulfone dianhydride, 3,3',4,4'-dimethyl diphenyl silane tetraacid dianhydride, 4,4'-[2,2,2-trifluoro-1-(3-trifluoromethylphenyl)ethylidene] bisphthalic anhydride, 4,4'-[2,2,2-trifluoro-1-(3,5-bistrifluoromethylphenyl)ethylidene] bisphthalic anhydride, hydroxy bisphthalic dianhydride, phenolphthalic dianhydride, or p-phenylene bis(trimellitic monoester anhydride).

[0046] Preferably, the polyamide-imide film raw material further comprises an inorganic filler, the inorganic filler comprises inorganic ions and / or silicon compounds, the average primary particle size is 1-100 nm, more preferably 5-50 nm, further more preferably 20-40 nm, the addition amount is 1-50 wt%, further preferably 5-30 wt%, and again further preferably 10-20 wt%. More preferably, the inorganic ions comprise at least one of silicon dioxide, barium sulfate, aluminum oxide, zirconium dioxide, titanium dioxide, barium titanate, magnesium fluoride or calcium fluoride, and the silicon compounds comprise at least one of silicon dioxide, barium sulfate, zirconium dioxide or aluminum oxide, and more preferably silicon dioxide, which is beneficial to the stability of the mixed resin solution and the dispersibility of the inorganic material. For the silicon dioxide particles, the silicon dioxide particles can be dispersed in an organic solvent to form a solution, or a microparticle powder of silicon dioxide can be manufactured by a gas phase method.

[0047] More preferably, the polyamide-imide film in the present application can further comprise other components in addition to the above-mentioned blended inorganic filler, such as antioxidants, bluing agents, flame retardants, leveling agents, light stabilizers and release agents, etc. for some special functions and uses.

[0048] Under the same inventive concept, the present application further provides a preparation method of the polyamide-imide film, comprising the following steps:

[0049] (1) dissolving an aromatic diamine in an organic aprotic polar solvent, sequentially adding a dianhydride and an acyl chloride monomer to prepare a polyamide acid solution;

[0050] (2) configuring a polyamide acid mixed solution of the polyamide acid solution, a dehydrating agent, a ring-closing catalyst and an organic solvent, and preparing a polyamide-imide film by a chemical imine method.

[0051] Preferably, in step (1), the organic aprotic polar solvent comprises two or more of N,N'-dimethylformamide, N,N'-dimethylacetamide, N-methylpyrrolidone, cyclopentanone, dioxane, gamma-butyrolactone, carbon dichloride, carbon trichloride and tetrahydrofuran.

[0052] Preferably, in step (1), the dissolving of the aromatic diamine occurs under inert conditions, and the dianhydride monomer is added in batches.

[0053] Preferably, in step (1), the concentration of the polyamide acid solution is 5-35 wt%, and the viscosity is 100 Pa·s-10000 Pa·s. More preferably, the concentration is 10-25 wt%, and the viscosity is 500 Pa·s-6000 Pa·s, and more preferably 1000 Pa·s-4000 Pa·s. When the solid content is within this range, an appropriate molecular weight and solution viscosity can be obtained.

[0054] Preferably, in step (2), the dehydrating agent comprises two or more of aliphatic anhydride, aromatic anhydride, halogenated lower aliphatic anhydride or sulfinyl halide, and the amount is 0.5-10 times, preferably 0.7-8 times, and more preferably 1.0-6 times, relative to the molar amount of diamine in amic acid; the catalyst comprises at least one of aliphatic tertiary amine, aromatic tertiary amine or heterocyclic tertiary amine, and more preferably, the heterocyclic tertiary amine is selected from quinoline, pyridine and 3-methylpyridine, and the amount is 0.2-6 times, preferably 0.25-5 times, and most preferably 0.3-4 times, relative to the molar amount of diamine in amic acid. If the amount is higher than the range, the polyamic acid is prone to be sticky and to block the equipment, and if the amount is lower than the range, the imidization degree is insufficient, and the strength of the film peeled from the support is not enough to be self-supporting.

[0055] Preferably, in step (2), the polyamic acid mixed solution is prepared at a low temperature of -20-5°C from polyamic acid, dehydrating agent, catalyst and organic solvent.

[0056] Preferably, in step (2), the film prepared by the chemical imidization method is prepared as follows: the polyamic acid mixed solution is cast on a support, heated to 120-200°C and kept for 10-300s, and then imidized to prepare a partially imidized self-supporting polyamic acid adhesive film, the polyamic acid adhesive film is peeled off and placed on a frame of a tenter, heated to 200-600°C and kept for 10-1200s to complete the imidization reaction and remove the solvent, and then a polyimide film is obtained.

[0057] Compared with the prior art, the present application has the following advantages:

[0058] (1) The conformationally twisted rigid structure is introduced into the molecular segment of the polyimide to improve the optical properties and heat resistance; the amide bond is introduced into the molecular structure by the acid chloride monomer to improve the mechanical properties and surface hardness of the product; a small amount of local crosslinking network structure is formed by adding a small amount of triacyl chloride monomer to the acid chloride monomer, and the ratio of the triacyl chloride monomer to the diacyl chloride monomer is adjusted to ensure the optical properties and other properties; the polyamic acid is mixed with chemical reagents to directly form a film on the support and the film is prepared by chemical imidization to improve the dimensional stability of the product, and the production efficiency and raw material utilization rate are also improved.

[0059] (2) In the present application, the diacyl chloride monomer is mainly prepared by converting aromatic diamine having strong electron-withdrawing effect by a certain method, the charge density of the local segment of the polyamide is reduced to inhibit the formation of CTC, thereby realizing good mechanical properties of the film and ensuring excellent overall optical properties, especially the yellowness index; and the Young's modulus and surface hardness of the film can be obviously improved by adjusting the addition of TPC and BPDC, and the linear thermal expansion coefficient can be reduced.

[0060] (3) The polyamide-imide film prepared by using the one-step method or the two-step method of the present application can have excellent optical properties, mechanical properties and thermal properties, and such colorless and transparent film can be used in TFT-LCD, substrate or cover plate of flexible display screen, thin film solar cell and other fields. BRIEF DESCRIPTION OF DRAWINGS

[0061] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed to be used in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0062] Figure 1 Synthetic procedure schematic diagram for converting 4,4'-diamino-2,2'-bistrifluoromethyl diphenyl into 4,4'-dichloro-2,2'-bistrifluoromethyl diphenyl;

[0063] Figure 2 Synthetic procedure schematic diagram for converting 1,4-benzenedicarboxylic acid into 1,4-benzenedicarboxylic acid chloride;

[0064] Figure 3 Synthetic procedure schematic diagram for converting 2,5-bis(trifluoromethyl) p-phenylenediamine into 2,5-bis(trifluoromethyl) terephthaloyl chloride;

[0065] Figure 4 Synthetic procedure schematic diagram for converting 2,2',6,6'-tetrafluoro diphenylamine into 2,2',6,6'-tetrafluoro diphenyl dicarboxylic acid chloride;

[0066] Figure 5 Synthetic procedure schematic diagram for converting 2,2',6,6'-tetrafluoro diphenylamine into 2,2',6,6'-tetrafluoro diphenyl dicarboxylic acid chloride;

[0067] Figure 6 Synthetic procedure schematic diagram for converting 2,2',6,6'-tetrafluoro diphenylamine into 2,2',6,6'-tetrafluoro diphenyl dicarboxylic acid chloride;

[0068] Figure 7 Synthetic procedure schematic diagram for converting 4,4'-(hexafluoroisopropylidene) diphenylamine into 4,4'-(hexafluoroisopropylidene) benzene dicarboxylic acid chloride;

[0069] Figure 8 Synthetic procedure schematic diagram for converting 4,4'-diamino diphenyl sulfone into 4,4'-dichloro diphenyl sulfone;

[0070] Figure 9 Synthetic procedure schematic diagram for converting 4,4'-diamino diphenyl sulfone into 4,4'-dichloro diphenyl sulfone;

[0071] Figure 10 a schematic diagram of a synthesis procedure for converting 4,4'-diaminodiphenyl ether into 4,4'-dichlorodiphenyl ether; DETAILED DESCRIPTION

[0072] In order to facilitate the understanding of the present application, a more complete, detailed description of the present application will be made with reference to the accompanying drawings and preferred embodiments. However, the scope of the protection of the present application is not limited to the following specific embodiments.

[0073] Unless otherwise defined, all terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art. The professional terms used in the present application are used only for the purpose of describing the specific embodiments and are not intended to limit the scope of protection of the present application.

[0074] Unless otherwise specifically mentioned, the various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by the existing method.

[0075] Example 1

[0076] A polyamide-imide film prepared from aromatic diamine, dianhydride monomer and acid chloride monomer.

[0077] A method for preparing a polyamide-imide film having high dimensional stability, high light transmittance and low yellowness, comprising the following steps:

[0078] (1) Under a nitrogen atmosphere, the reaction device was placed in a 10℃ reaction bath, DMAc (8100g, 85wt%) and 4,4'-diamino-2,2'-bistrifluoromethyl biphenyl (TFMB, 640.46g, 2mol) were first added, stirred and dissolved, then 2,3',3,4'-biphenyl tetracarboxylic dianhydride (α-BPDA, 117.688g, 0.4mol) was added, stirred and reacted for 0.5h, then 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA, 88.848g, 0.2mol) was added, stirred and reacted for 0.5h, then 4,4'-dichloro-2,2'-bistrifluoromethyl biphenyl (TFMC, 580.86g, 1.4mol) was added, and finally 0.028mol of 1,3,5-benzene tricarboxylic acid chloride was added, stirred and reacted for 4h to obtain a polyamic acid solution with a viscosity of 3500Pa·s, then the polyamic acid solution was vacuum pumped by a vacuum pump to eliminate the bubbles in the resin solution as much as possible.

[0079] (2) To the polyamic acid solution after step (1), add acetic anhydride (408.4 g, 4 mol), 3-methylpyridine (186.3 g, 2 mol) and DMAc (149 g), mix uniformly at 0°C to obtain a glue solution, then pour the glue solution through a slot die onto a ring-shaped steel belt, dry at 120-180°C for 100-200 s to remove most of the solvent to form a glue film, then peel off the glue film and place it on a tenter frame, pass through a high-temperature tenter oven at 200-500°C and stay for 300 s, heat treat using convection and radiation, remove from the needle plate, and finally anneal at 300°C for 30 s to obtain a polyamide-imide film with a thickness of about 80 μm, high dimensional stability, high light transmittance and low yellowness.

[0080] Example 2

[0081] In Example 1, replace 4,4'-dichloro-2,2'-bistrifluoromethyl biphenyl (TFMC) with an equimolar amount of octafluorobiphenyl dicarboxylic dichloride, 2,3',3,4'-biphenyl tetracarboxylic dianhydride (a-BPDA, 88.266 g, 0.3 mol), and the other experimental conditions are the same as in Example 1.

[0082] Example 3

[0083] (1) Under a nitrogen atmosphere, first add DMAc (6703 g, 85 wt%) and 4,4'-diamino-2,2'-bistrifluoromethyl biphenyl (TFMB, 640.46 g, 2 mol) to a reaction device in a 0°C reaction bath, stir to dissolve, then add 2,3',3,4'-biphenyl tetracarboxylic dianhydride (a-BPDA, 117.688 g, 0.4 mol), stir for 0.5 h, then add 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA, 88.848 g, 0.2 mol), stir for 0.5 h, then add 4,4'-dichloro-2,2'-bistrifluoromethyl biphenyl (TFMC, 249.54 g, 0.6 mol), stir for 0.5 h, then add terephthaloyl chloride (TPC, 162.416 g, 0.8 mol), 0.03 mol of 1,3,5-benzene tricarboxylic chloride, stir for 4 h, and obtain a polyamic acid solution with a viscosity of 3685 Pa-s.

[0084] The subsequent step (2) is consistent with the preparation method of Example 1.

[0085] Example 4

[0086] Example 1 was repeated except that 1.4 mol of 4,4'-diamino-2,2'-bistrifluoromethylbiphenyl (TFMB) was replaced with 1.28 mol of 4,4'-diamino-2,2'-bistrifluoromethylbiphenyl (TFMB) and 0.08 mol of 1,3,5-benzene tricarboxylic acid chloride (TPAC), and other experimental conditions were the same as in Example 1.

[0087] Example 5

[0088] Example 3 was repeated except that 1.4 mol of 4,4'-diamino-2,2'-bistrifluoromethylbiphenyl (TFMB) was replaced with 1.28 mol of 4,4'-diamino-2,2'-bistrifluoromethylbiphenyl (TFMB) and 0.08 mol of 1,3,5-benzene tricarboxylic acid chloride (TPAC), and other experimental conditions were the same as in Example 3.

[0089] Example 6

[0090] Example 1 was repeated except that 1.4 mol of 4,4'-diamino-2,2'-bistrifluoromethylbiphenyl (TFMB) was replaced with 1.28 mol of 4,4'-diamino-2,2'-bistrifluoromethylbiphenyl (TFMB) and 0.08 mol of 1,3,5-benzene tricarboxylic acid chloride (TPAC), and other experimental conditions were the same as in Example 1.

[0091] Example 7

[0092] Example 1 was repeated except that 1.4 mol of 4,4'-diamino-2,2'-bistrifluoromethylbiphenyl (TFMB) was replaced with 1.28 mol of 4,4'-diamino-2,2'-bistrifluoromethylbiphenyl (TFMB) and 0.08 mol of 1,3,5-benzene tricarboxylic acid chloride (TPAC), and other experimental conditions were the same as in Example 1.

[0093] Example 8

[0094] Example 1 was repeated except that 2 mol of 4,4'-diamino-2,2'-bistrifluoromethylbiphenyl (TFMB) was replaced with 1.8 mol of TFMB and 0.4 mol of 1,3-diaminobenzene, 0.4 mol of 2,3',3,4'-biphenyltetracarboxylic dianhydride (a-BPDA) was replaced with 0.1 mol of 2,3',3,4'-biphenyltetracarboxylic dianhydride (a-BPDA), 0.1 mol of benzophenonetetracarboxylic dianhydride and 0.2 mol of ethynylbisphthalic anhydride (EBPA), and other experimental conditions were the same as in Example 1.

[0095] Example 9

[0096] Example 1 was repeated, except that 1.6 mol of 4,4'-diamino-2,2'-bistrifluoromethylbiphenyl (TFMB), 0.2 mol of 1,3-diaminobenzene, and 0.2 mol of 1,4-diaminobenzene were used instead of 2 mol of 4,4'-diamino-2,2'-bistrifluoromethylbiphenyl (TFMB), 0.4 mol of 2,3',3,4'-biphenyltetracarboxylic dianhydride (a-BPDA) was replaced with 0.1 mol of pyromellitic dianhydride (PMDA), 0.2 mol of 2,3',3,4'-biphenyltetracarboxylic dianhydride (a-BPDA), and 0.1 mol of ethynylbisanhydride (EBPA), and the other experimental conditions were the same as in Example 1.

[0097] Comparative Example 1

[0098] (1) Under a nitrogen atmosphere, a reaction apparatus was placed in a reaction bath at 10°C, and DMAc (8100 g, 85 wt%) and 4,4'-diamino-2,2'-bistrifluoromethylbiphenyl (TFMB, 640.46 g, 2 mol) were first added and stirred to dissolve, and then 2,3',3,4'-biphenyltetracarboxylic dianhydride (a-BPDA, 117.688 g, 0.4 mol) was added, and stirred to react for 0.5 h, and then 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA, 88.848 g, 0.2 mol) was added, and stirred to react for 0.5 h, and then 4,4'-dichloro-2,2'-bistrifluoromethylbiphenyl (TFMC, 580.86 g, 1.4 mol) was added, and stirred to react for 4 h, to obtain a polyamic acid solution having a viscosity of 3590 Pa·s. Then, chemical imidization was performed, and acetic anhydride (408.4 g, 4 mol) and 3-methylpyridine (186.3 g, 2 mol) were added, and imidization was performed at low temperature for 4 h, and then the temperature was increased to 140°C, and imidization was performed for 2 h, and then the temperature was decreased to room temperature, to obtain a polyamide-imide solution.

[0099] (2) The polyamide-imide resin solution after step (1) was poured into 40 L of methanol to precipitate, to obtain a filamentous polymer, which was filtered, crushed by a crusher, washed with clean methanol 5 times, purified by a Soxhlet extractor to remove residual catalyst, and then dried in a vacuum oven at 100°C for 6 h, to obtain 1187.4 g of a polyamide-imide resin powder, with a yield of 87.6%.

[0100] (3) 1180 g of the polyamide-imide resin powder prepared in step (2) was dissolved in 6687 g of DMAc solvent (solid content: 15 wt%) to obtain a dope, which was then cast onto a circular steel belt through a slot die, dried at 120-180°C for 100-200 s to remove most of the solvent and form a dope film, the dope film was then peeled off and placed on a tenter frame, passed through a high-temperature tenter oven at 200-500°C for 300 s, heated using convection and radiation, cooled, removed from the needle plate, and finally annealed at 300°C for 30 s to obtain a polyamide-imide film having a thickness of about 79 μm.

[0101] Comparative Example 2

[0102] (1) Under a nitrogen atmosphere, the reaction device was placed in a reaction bath at 10°C, DMAc (8100 g, 85 wt%) and 4,4'-diamino-2,2'-bistrifluoromethylbiphenyl (TFMB, 640.46 g, 2 mol) were first added and stirred to dissolve, then 2,3',3,4'-biphenyltetracarboxylic dianhydride (a-BPDA, 117.688 g, 0.4 mol) was added, stirred for 0.5 h, then 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA, 88.848 g, 0.2 mol) was added, stirred for 0.5 h, then 4,4'-dichloro-2,2'-bistrifluoromethylbiphenyl (TFMC, 580.86 g, 1.4 mol) was added, stirred for 4 h to obtain a polyamic acid solution having a viscosity of 3586 Pa-s, then the dope was cast onto a circular steel belt through a slot die, dried at 120-180°C for 100-200 s to remove most of the solvent and form a dope film, the dope film was then peeled off and placed on a tenter frame, passed through a high-temperature tenter oven at 200-500°C for 300 s, heated using convection and radiation, cooled, removed from the needle plate, and finally annealed at 300°C for 30 s to obtain a polyamide-imide film having a thickness of about 80 μm, and the other experimental conditions were the same as in Example 1.

[0103] Comparative Example 3

[0104] Example 1 was repeated, except that 2,3',3,4'-biphenyltetracarboxylic dianhydride (a-BPDA) in Example 1 was replaced with an equimolar amount of 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA), and the other experimental conditions were the same as in Example 1.

[0105] Comparative Example 4

[0106] Example 3 was repeated except that 2,3',3,4'-biphenyltetracarboxylic dianhydride (a-BPDA) was replaced with an equimolar amount of 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA), and 4,4'-dicarboxylic acid-2,2'-bistrifluoromethyl biphenyl (TFMC) was replaced with an equimolar amount of terephthaloyl dichloride (TPC). The other experimental conditions were the same as in Example 1.

[0107] Comparative Example 5

[0108] Example 3 was repeated except that 2,3',3,4'-biphenyltetracarboxylic dianhydride (a-BPDA) was replaced with an equimolar amount of 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA). The other experimental conditions were the same as in Example 3.

[0109] Comparative Example 6

[0110] Example 1 was repeated except that 2,3',3,4'-biphenyltetracarboxylic dianhydride (a-BPDA) was replaced with an equimolar amount of 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA), and 4,4'-dicarboxylic acid-2,2'-bistrifluoromethyl biphenyl (TFMC) was replaced with an equimolar amount of tetrakisfluoroterephthaloyl dichloride (TFTPC). The other experimental conditions were the same as in Example 1.

[0111] Comparative Example 7

[0112] Example 5 was repeated except that 2,3',3,4'-biphenyltetracarboxylic dianhydride (a-BPDA) was replaced with an equimolar amount of 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA). The other experimental conditions were the same as in Example 5.

[0113] Comparative Example 8

[0114] Example 1 was repeated except that 2,3',3,4'-biphenyltetracarboxylic dianhydride (a-BPDA) was replaced with an equimolar amount of 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA), and 1.40 mol of 4,4'-dicarboxylic acid-2,2'-bistrifluoromethyl biphenyl (TFMC) was replaced with 1.28 mol of 4,4'-dicarboxylic acid-2,2'-bistrifluoromethyl biphenyl (TFMC) and 0.08 mol of 1,3,5-benzene tricarboxylic acid chloride (TPAC). The other experimental conditions were the same as in Example 1.

[0115] Comparative Example 9

[0116] The 2,3',3,4'-biphenyltetracarboxylic dianhydride (a-BPDA) in Example 1 was replaced with equimolar amount of 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA), 1.4 mol of 4,4'-dicarboxylic acid-2,2'-bistrifluoromethyl biphenyl (TFMC) was replaced with 1.28 mol of terephthaloyl chloride (TPC) and 0.08 mol of 1,3,5-benzene tricarboxylic acid chloride (TPAC), and other experimental conditions were the same as those in Example 1.

[0117] Characterization instruments and methods

[0118] The thickness of the film was detected by a CHY-CA type film thickness gauge, 8-10 points on the sample were tested at equal distances, and the average value of the test structure was taken;

[0119] The cut-off wavelength and the light transmittance at 550 nm of the film were detected by a UV-1800 ultraviolet visible spectrophotometer;

[0120] The yellowness index (YI) was determined by a CIE colorimetric system using a color difference meter (Color Eye 7000A);

[0121] The haze of the polyimide film was detected by a WGW photoelectric haze meter;

[0122] The mechanical properties of the film were detected by an Instron electronic universal material testing machine, the tensile rate was 20 mm / min, each sample was tested 5 times and the average value was taken;

[0123] The pencil hardness of the surface without any scratches was determined by a Mitsubishi evaluation pencil (UNI) using an electric pencil hardness meter, with a load of 1 kg and a rate of 180 mm / min, and 5 times of 50 mm were drawn.

[0124] The linear thermal expansion coefficient of the polyimide resin layer was tested by a thermal mechanical analyzer (TMA) under nitrogen atmosphere, the heating rate was 10 ℃ / min, and the value was taken within 50-250 ℃;

[0125] The heat resistance of the film was analyzed by a Q800 dynamic thermal mechanical analyzer, the heating rate was 5 ℃ / min; and the test results are shown in Table 1

[0126] Table 1 Properties of the films in Examples 1-7 and Comparative Examples 1-9 of the application

[0127]

[0128]

Claims

1. A polyamide-imide film, characterized in that, Raw materials including the following molar proportions: 85-115 parts of aromatic diamine; 21–39 parts of dianhydride monomer; Acyl chloride monomer 63-89 parts; The acyl chloride monomer includes a diacyl chloride monomer and a triacyl chloride monomer, wherein the diacyl chloride monomer is a diacyl chloride monomer prepared by conversion of aromatic diamine, and the molar ratio of the triacyl chloride monomer to the diacyl chloride monomer is 1% to 10%. The polyamide-imide film raw material also includes terephthaloyl chloride; The diacyl chloride monomer prepared by the conversion of aromatic diamine includes one or more of 4,4'-diacyl chloride-2,2'-bis(trifluoromethyl)biphenyl, tetrafluoroterephthaloyl chloride, and octafluorobiphenyl dicarboxylate chloride; The triacyl chloride monomer includes 1,3,5-benzenetricarboxyl chloride; The aromatic diamine comprises 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl; The dianhydride monomer comprises 2,3′,3,4′-biphenyltetracarboxylic dianhydride.

2. The polyamide-imide film according to claim 1, characterized in that, The polyamide-imide film raw material also includes inorganic fillers, which include inorganic particles and / or silicon compounds, with an average primary particle size of 1-100 nm and an addition amount of 1-50 wt%.

3. A method for preparing a polyamide-imide film as described in claim 1 or 2, characterized in that, Includes the following steps: (1) Dissolve an aromatic diamine in an organic aprotic polar solvent, and add dianhydride and acyl chloride monomer in sequence to prepare a polyamic acid solution; (2) A polyamic acid mixed solution prepared by polyamic acid solution, dehydrating agent, catalyst and organic solvent is used to prepare a polyamic acid film by chemical imide method to obtain a polyamide-imide film.

4. The method for preparing the polyamide-imide film according to claim 3, characterized in that, In step (1), the organic aprotic polar solvent includes two or more of N,N'-dimethylformamide, N,N'-dimethylacetamide, N-methylpyrrolidone, cyclopentanone, dioxane, γ-lactone, carbon dichloride, carbon trichloride or tetrahydrofuran.

5. The method for preparing the polyamide-imide film according to claim 3, characterized in that, In step (1), the dissolution of the aromatic diamine occurs under inert conditions, and the dianhydride monomer is added in batches.

6. The method for preparing the polyamide-imide film according to claim 3, characterized in that, In step (1), the concentration of the polyamic acid solution is 5-35 wt%, and the viscosity is 100-10000 Pa•s.

7. The method for preparing the polyamide-imide film according to claim 3, characterized in that, In step (2), the dehydrating agent includes two or more of aliphatic acid anhydrides, aromatic acid anhydrides, halogenated lower fatty acid anhydrides or thionyl halides, and the amount used is 0.5 to 10 times the molar amount of diamine in polyamic acid; the catalyst includes at least one of aliphatic tertiary amine, aromatic tertiary amine or heterocyclic tertiary amine, and the amount used is 0.2 to 6 times the molar amount of diamine in polyamic acid.

8. The method for preparing the polyamide-imide film according to claim 7, characterized in that, In step (2), the polyamic acid mixed solution is prepared by polyamic acid, dehydrating agent, catalyst and organic solvent at a low temperature of -20 to 5°C.

9. The method for preparing the polyamide-imide film according to claim 3, characterized in that, In step (2), the chemical imidization method for film formation specifically involves: casting a polyamic acid mixed solution onto a support, heating it to 120°C to 200°C and holding it for 10 to 300 seconds, and chemically imidizing it to form a partially imidized, supportive polyamic acid adhesive film. After peeling off the polyamic acid adhesive film, it is placed on a tenter frame and then heated to 200°C to 600°C and held for 10 to 1200 seconds to complete the imidization reaction and remove the solvent, thereby obtaining a polyamide-imide film.

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