CN111116401B - Preparation method of C7 side chain substituted fluorine-containing diamine monomer - Google Patents

Abstract

The invention designs a polyimide diamine monomer C7-FBDA with an innovative structure, which realizes simultaneous introduction of C7 side chain alkyl, trifluoromethyl, imide groups and a plurality of benzene ring structures in the molecular structure, breaks the regularity and crystallinity of polymer molecular chains, improves the free volume of the polymer, reduces the interaction between the molecular chains, and further greatly improves the film forming property and optical transparency of polyimide. In the synthesis of C7-FBDA, the invention develops a production process of industrially applicable C7-FBDA, the process has the advantages of short synthesis route, high yield, low-cost and easily available raw materials, low production cost, simple and convenient operation, environmental friendliness, capability of realizing large-scale mass production and great industrial application value.

Description

A method for preparing a C7 side chain substituted fluorinated diamine monomer

Technical Field

The invention relates to the fields of fine chemical industry and polymer chemistry, and in particular to the field of preparation of polyimide polymers.

Background technique

In recent years, with the development of optoelectronic devices, traditional transparent glass substrates can no longer meet the requirements of flexible devices. Colorless and transparent polymers have the advantages of transparency, light weight, and impact resistance, and have received increasing attention in the fields of patterned display devices, liquid crystal alignment films, optical films, organic photovoltaic solar panels, flexible printed circuit boards, and touch panels. Polyimide has excellent high temperature resistance, dielectric properties, and mechanical processing properties, and is the first choice to replace glass substrates. However, for traditional polyimide, improving its light transmittance is the key.

Traditional polyimide is generally a brown or brownish yellow transparent material. This is because there are strong electron donors (diamines) and electron acceptors (dianhydrides) in the molecular structure of polyimide, which form a strong charge transfer complex within or between the polyimide molecular chains, causing the molecular chains to be tightly stacked, making the polyimide have strong absorption in the visible light range; and the stronger the electron donating and electron withdrawing ability of the residual groups of diamine and dianhydride, the greater the degree of charge transfer complex formation, the easier it is to absorb light, and the darker the color of the polyimide (Lan Zhongxu et al., doi: 10.14133/j.cnki.1008-9357.20190705001).

Introducing trifluoromethyl groups with large free volumes, long side chain groups and multiple benzene ring structures into the polyimide structure can effectively reduce the charge transfer complex effect within and between polyimide molecular chains, thereby improving the light transmittance of polyimide, and finally obtaining a highly transparent fluorinated polyimide film material. Polyimide is generally formed by the polycondensation of diamine and dianhydride. By modifying the molecular structure of diamine or dianhydride, the performance of polyimide can be optimized. At present, there are 8 commercial dianhydride monomers, including cyclohexanetetracarboxylic dianhydride (HPMDA), pyromellitic dianhydride (PMDA), cyclobutanetetracarboxylic dianhydride (CBDA), hexafluoroisopropylphthalic anhydride (6FDA), diphenyl ether tetracarboxylic dianhydride (ODPA), benzophenone tetracarboxylic dianhydride (BTDA), biphenyl tetracarboxylic dianhydride (BPDA) and bisphenol A diether dianhydride (BPADA). Compared with dianhydride monomers, diamine monomers are relatively rare. Currently, there are only two commercially available, namely, di(trifluoromethyl)diaminobiphenyl (TFMB) and diaminodiphenyl ether (ODA). The main reason is that diamine monomers with innovative structures generally have larger molecular weights, it is more difficult to reduce the nitro group, and the production cost is relatively high, which to a certain extent limits the development of polyimide. It can be seen that designing diamine monomers with innovative structures, innovating their production processes, and realizing their large-scale production will be very beneficial to promoting the development of the polyimide industry.

Based on this, the present invention designs a diamine monomer with an innovative structure (the chemical structure is shown in FIG. 1 , abbreviated as C7-FBDA), and develops an industrially applicable synthesis process, and realizes the efficient production of C7-FBDA by optimizing the reaction route.

Summary of the invention

Purpose of the present invention: (1) By innovating the molecular structure, the diamine monomer is endowed with more functionality. Specifically, the C7 side chain alkyl, trifluoromethyl, imide group and multiple benzene ring structures are simultaneously introduced into the C7-FBDA molecular structure, breaking the regularity and crystallinity of the polymer molecular chain, increasing the free volume of the polymer, reducing the interaction between the molecular chains, and thus greatly improving the film-forming property and optical transparency of the polyimide. (2) A production process of C7-FBDA that can be applied industrially is developed. By optimizing the reaction route, the efficient synthesis of C7-FBDA is achieved. (3) The varieties of diamine monomers are enriched, which promotes the development of the polyimide industry to a certain extent.

Summary of the invention:

The synthesis of C7-FBDA is divided into three steps.

Step 1: Add 2,2-bis(3-amino-4-sodium phenolate)hexafluoropropane, C7 bromoalkane and solvent N,N-dimethylacetamide (abbreviated as DMAC) into the reactor, start stirring and heating, keep warm for a period of time and filter while hot to remove the by-product sodium bromide generated by the reaction. The filtrate is cooled to room temperature and then added into water for quenching. At this time, a large amount of solid will appear. Filter again, wash the filter cake with water and vacuum dry it in turn to obtain pure 2,2-bis(3-amino-4-C7 alkoxyphenyl)hexafluoropropane (abbreviated as C7-FN), and its chemical structure is shown in Figure 2.

Step 2: Add C7-FN and solvent N-methylpyrrolidone (abbreviated as NMP) to the reactor, start stirring and jacket cooling, and then slowly drop a mixture of m-nitrobenzoyl chloride and NMP into the reactor. After the dropwise addition, continue the reaction until the raw materials react completely, and then slowly add the reaction solution into methanol to quench. At this time, a large amount of solid will appear. Filter, wash the filter cake with methanol and water in turn, and then vacuum dry to obtain pure C7-FBDN. Its chemical structure is shown in Figure 3.

Step 3: Under nitrogen protection, add C7-FBDN, palladium carbon catalyst and solvent N,N-dimethylformamide (DMF) into the reactor, start stirring and heating, and then slowly add hydrazine hydrate solution to the reactor. After the addition is completed, keep the reaction warm until C7-FBDN reacts completely, then turn off the heating, filter the reaction solution while hot, and slowly add the filtrate into water for quenching. At this time, a large amount of solid will appear. Filter again, and the filter cake is purified by ethanol beating and vacuum drying to obtain pure C7-FBDA.

The overall synthetic route of C7-FBDA is shown in Figure 4.

The method for preparing a C7 side chain substituted fluorinated diamine monomer of the present invention is characterized in that, in the first step of the synthesis reaction, the molar feed ratio of the brominated C7 alkane to 2,2-bis(3-amino-4-sodium phenolate)hexafluoropropane is 2:1-10:1, and the preferred molar feed ratio is 2:1-3:1.

The method for preparing a C7 side chain substituted fluorinated diamine monomer of the present invention is characterized in that, in the first step of the synthesis reaction, the concentration of 2,2-bis(3-amino-4-sodium phenolate)hexafluoropropane in the solvent DMAC is 0.1-2.0 mol/L, and the preferred concentration is 1.1-1.6 mol/L.

The method for preparing a C7 side chain substituted fluorinated diamine monomer of the present invention is characterized in that, in the first step of the synthesis reaction, the reaction temperature is controlled between 80-166°C, preferably between 120-130°C.

The method for preparing a C7 side chain substituted fluorinated diamine monomer of the present invention is characterized in that, in the second step synthesis reaction, the molar feed ratio of m-nitrobenzoyl chloride to C7-FN is 2:1-10:1, and the preferred molar feed ratio is 2:1-3:1.

The method for preparing a C7 side chain substituted fluorinated diamine monomer of the present invention is characterized in that, in the second step synthesis reaction, the concentration of C7-FN in the solvent NMP is 0.1-2.0 mol/L, preferably 0.5-1.5 mol/L.

The method for preparing a C7 side chain substituted fluorinated diamine monomer of the present invention is characterized in that, in the second step synthesis reaction, when a mixed solution of C7-FN and NMP is added dropwise, the temperature of the reaction solution is controlled between 0-50°C, preferably between 20-30°C.

The method for preparing a C7 side chain substituted fluorinated diamine monomer described in the present invention is characterized in that, in the third step synthesis reaction, the feed weight ratio of palladium carbon to C7-FBDN is 0.05:1-0.1:1, and the preferred feed weight ratio is 0.05:1-0.08:1.

The method for preparing a C7 side chain substituted fluorinated diamine monomer of the present invention is characterized in that, in the third step synthesis reaction, the molar ratio of hydrazine hydrate to C7-FBDN is 30:1-50:1, and the preferred molar ratio is 30:1-35:1.

The method for preparing a C7 side chain substituted fluorinated diamine monomer of the present invention is characterized in that, in the third step of the synthesis reaction, the temperature of the reaction solution is controlled between 65-95° C., preferably between 75-90° C., when hydrazine hydrate is added dropwise.

Beneficial effects: The present invention focuses on the design and preparation of diamine monomers with innovative structures. Specifically, in the design of the molecular structure of C7-FBDA, a strongly electronegative trifluoromethyl group, a long-chain C7 alkyl substituent and a rigid non-planar structure are simultaneously introduced, which effectively reduces the order and symmetry of the molecular chain, thereby reducing the stacking of the polyimide polymer molecular chain, increasing the spatial free volume of the molecular chain to a certain extent, disrupting the conjugation between the chains, and then inhibiting or reducing the formation of charge transfer complexes between and within the molecules, and ultimately reducing the absorption of polyimide in the visible light region, greatly improving the light transmittance of the film. In the synthesis of C7-FBDA, the present invention preferably selects a shorter synthesis route with a higher synthesis yield, the raw materials used are cheap and easily available, the production cost is low, and the operation is simple and environmentally friendly. It can fully achieve large-scale mass production and has great industrial application value.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1: C7-FBDA structure.

Figure 2: C7-FN structure.

Figure 3: C7-FBDN structure.

Figure 4: Overall synthetic route of C7-FBDA.

Detailed ways

Example 1

The first step: add 1.2L DMAC, 1000g 2,2-bis(3-amino-4-sodium phenol)hexafluoropropane and 868g brominated C7 alkane to a 10L four-necked reaction bottle in sequence, start stirring and heating, maintain the reaction at 80°C for 2-3h, after the reaction of the raw materials is completed, turn off the heating, pour out the reaction solution, filter while hot, the upper filter cake is the by-product sodium bromide, collect and save, the filtrate is naturally cooled to room temperature, and then added to 2.4L water to quench, a large amount of solid will appear at this time, filter, and wash the filter cake with 3.5L water. After draining, the filter cake is vacuum dried to obtain 1234g C7-FN pure product.

Step 2: Add 1234g C7-FN and 550mL NMP to a 10L four-necked reaction bottle, start stirring, and then slowly drop a mixture of 812g m-nitrobenzoyl chloride and 550mL NMP into it, and control the temperature of the reaction solution to be around 50°C during the dropwise addition. After the dropwise addition, keep the temperature at 50°C and continue the reaction for 2-3h. After the raw material reaction is completed, slowly pour the reaction solution into 2200mL methanol to quench. At this time, a large amount of solid will appear, filter, and wash the filter cake with 1000mL methanol and 1000mL water in turn. The obtained filter cake is vacuum dried to obtain 1699g C7-FBDN pure product.

Step 3: Under nitrogen protection, add 3500mL DMF, 1699g C7-FBDN and 85g palladium carbon catalyst (palladium content 10%) to a 10L four-necked flask, start stirring and heating, and when the temperature of the reaction liquid rises to 65°C, slowly drop 3500mL hydrazine hydrate solution (concentration: about 17mol/L) into the reaction bottle, control the temperature of the reaction liquid at about 65°C during the dropwise addition, and keep warm at 65°C for 2-3h. After the reaction of the raw material C7-FBDN is completed, turn off the heating, filter the reaction liquid while hot, and slowly drop the filtrate into 7000mL water for quenching. At this time, a large amount of solid will appear, filter again, and purify the filter cake with 3500mL ethanol pulping, and then vacuum dry to obtain 1423g C7-FBDA pure product.

Example 2

The first step: 24.3L DMAC, 1000g 2,2-bis(3-amino-4-sodium phenol)hexafluoropropane and 4342g brominated C7 alkane were added to a 30L double-layer glass reactor in sequence, stirring and heating were started, and the reaction was maintained at 166°C for 2-3h. After the reaction of the raw materials was completed, the heating was turned off, the reaction solution was released, and it was filtered while hot. The upper filter cake was the by-product sodium bromide, which was collected and stored. The filtrate was naturally cooled to room temperature, and then added to 48.6L water for quenching. At this time, a large amount of solids appeared, and the filter cake was filtered and washed with 3.5L water. After being drained, the filter cake was vacuum dried to obtain 1303g of pure C7-FN.

Step 2: Add 1303g C7-FN and 11.5L NMP to a 30L double-layer glass reactor, start stirring and jacket cooling, and when the temperature of the reaction liquid drops to 0°C, slowly drop a mixture of 4286g m-nitrobenzoyl chloride and 11.5L NMP into it, and control the temperature of the reaction liquid at about 0°C during the dropwise addition. After the dropwise addition, keep the temperature at 0°C and continue the reaction for 2-3h. After the raw materials react completely, slowly pour the reaction liquid into 46L methanol to quench, and a large amount of solid will appear at this time. Filter, wash the filter cake with 1000mL methanol and 1000mL water in turn, and vacuum dry the obtained filter cake to obtain 1894g C7-FBDN pure product.

Step 3: Under nitrogen protection, add 6500mL DMF, 1894g C7-FBDN and 189.4g palladium carbon catalyst (palladium content 10%) to a 30L double-layer glass reactor, start stirring and heating, and when the temperature of the reaction liquid rises to 95°C, slowly add 6500mL hydrazine hydrate solution (concentration: about 17mol/L) to the reaction bottle, and control the temperature of the reaction liquid at about 95°C during the addition. After the addition, keep the temperature at 95°C and continue the reaction for 2-3h. After the reaction of the raw material C7-FBDN is completed, turn off the heating, filter the reaction liquid while hot, and slowly add the filtrate to 13L water for quenching. At this time, a large amount of solid will appear, filter again, and purify the filter cake with 6500mL ethanol pulping, and then vacuum dry it to obtain 1674g C7-FBDA pure product.

Claims (9)

1. A method for preparing a C7 side chain substituted fluorinated diamine monomer, wherein the chemical structure of the C7 side chain substituted fluorinated diamine monomer C7-FBDA is as shown in Formula 1, and its synthesis is divided into three steps; Step 1: Add 2,2-bis(3-amino-4-sodium phenolate)hexafluoropropane, bromo-C7 alkane and solvent N,N-dimethylacetamide into a reaction kettle, start stirring and heating, keep warm for a period of time and filter while hot to remove the by-product sodium bromide generated by the reaction, cool the filtrate to room temperature, and then add water to quench, at which time a large amount of solid will appear, filter again, wash the filter cake with water and vacuum dry it in turn, and obtain 2,2-bis(3-amino-4-C7 alkoxyphenyl)hexafluoropropane C7-FN pure product, whose chemical structure is shown in Formula 2; Step 2: Add C7-FN and solvent N-methylpyrrolidone to the reactor, start stirring and jacket cooling, then slowly drop a mixed solution of m-nitrobenzoyl chloride and N-methylpyrrolidone into the reactor, continue the reaction until the raw materials react completely, then slowly add the reaction solution into methanol to quench, at this time a large amount of solid will appear, filter, wash the filter cake with methanol and water in turn, and then vacuum dry to obtain pure C7-FBDN, whose chemical structure is shown in Formula 3; Step 3: Under nitrogen protection, add C7-FBDN, palladium carbon catalyst and solvent N,N-dimethylformamide to the reactor, start stirring and heating, then slowly drop hydrazine hydrate solution into the reactor, after dropping, keep warm until C7-FBDN reacts completely, then turn off heating, filter the reaction solution while hot, slowly drop the filtrate into water for quenching, at this time a large amount of solid will appear, filter again, and the filter cake is successively purified by ethanol beating and vacuum drying to obtain pure C7-FBDA; In the step 1, the molar feed ratio of the brominated C7 alkane to 2,2-bis(3-amino-4-sodium phenolate)hexafluoropropane is 2:1 to 3:1. 2. A method for preparing a C7 side chain substituted fluorinated diamine monomer as claimed in claim 1, characterized in that in step 1, the concentration of 2,2-bis(3-amino-4-sodium phenolate)hexafluoropropane in the solvent N,N-dimethylacetamide is 1.1 to 1.6 mol/L. 3. A method for preparing a C7 side chain substituted fluorinated diamine monomer as claimed in claim 1, characterized in that the reaction temperature in step 1 is controlled between 120 and 130°C. 4. A method for preparing a C7 side chain substituted fluorinated diamine monomer as claimed in claim 1, characterized in that the molar feed ratio of intermediate nitrobenzoyl chloride to C7-FN in step 2 is 2:1 to 3:1. 5. A method for preparing a C7 side chain substituted fluorinated diamine monomer as claimed in claim 1, characterized in that the concentration of C7-FN in the solvent N-methylpyrrolidone in step 2 is 0.5 to 1.5 mol/L. 6. A method for preparing a C7 side chain substituted fluorinated diamine monomer as claimed in claim 1, characterized in that the temperature of the reaction solution is controlled between 20 and 30°C when the mixed solution of m-nitrobenzoyl chloride and N-methylpyrrolidone is added dropwise in step 2. 7. A method for preparing a C7 side chain substituted fluorinated diamine monomer as claimed in claim 1, characterized in that the weight feed ratio of palladium carbon to C7-FBDN in step 3 is 0.05:1 to 0.08:1. 8. A method for preparing a C7 side chain substituted fluorinated diamine monomer as claimed in claim 1, characterized in that the molar feed ratio of hydrazine hydrate to C7-FBDN in step 3 is 30:1 to 35:1. 9. A method for preparing a C7 side chain substituted fluorinated diamine monomer as claimed in claim 1, characterized in that the temperature of the reaction solution is controlled between 75 and 90°C when hydrazine hydrate is added dropwise in step 3.