CN115947663A - Diamine monomer, polyimide material, preparation method and application thereof - Google Patents

Abstract

The invention provides a diamine monomer, which has the structure shown in formula I. The invention introduces a low polarizability long alkyl side chain structure into the polyimide side chain molecular structure, and the long alkyl chain can destroy polyimide The close packing of the imine main chain can obtain larger molecular free volume to further reduce the dielectric constant of polyimide, and it also has a lower dielectric loss; in addition, the long alkyl chains distributed on the surface of the film can also It can improve the hydrophobicity of the material and reduce the water absorption to achieve low dielectric and low moisture absorption properties at the same time. Furthermore, the polyimide material with low dielectric loss and low moisture absorption rate described in the present invention can meet important applications in the fields of high-frequency information communication technology, flexible high-frequency circuit board substrates, and optoelectronic devices. The invention also provides a polyimide material, its preparation method and application.

Description

A kind of diamine monomer, polyimide material, its preparation method and application

technical field

The invention belongs to the technical field of dielectric materials, and in particular relates to a diamine monomer, a polyimide material, a preparation method and an application thereof.

Background technique

In recent years, with the development of 5G communication technology, the signal transmission lines are being miniaturized, thinned, multi-functional, and high-performance, which puts higher requirements on the performance of polymer materials for communication. The high-frequency and high-speed transmission characteristics require that the transmission line dielectric material has excellent dielectric properties - low dielectric constant and low dielectric loss - to ensure the integrity and accuracy of signal transmission. Polyimide materials are polymerized by diamines and dianhydrides. Due to their low dielectric loss, heat resistance, chemical resistance, and excellent mechanical flexibility and electrical properties, they are used in industrial fields such as automobiles, aerospace, and electronics. Has a wide range of applications. However, printed circuit boards for high-density, high-frequency, and high-speed integrated circuits require the dielectric constant of their polymer materials to be lower than 3. However, the dielectric constant of conventional polyimide is about 3.4, and the high water absorption rate is often between 1-3%, which cannot meet the needs of the new generation of low dielectric materials. Therefore, preparing a polyimide material with low dielectric loss, high hydrophobicity and low moisture absorption is the key to realize the above requirements.

Generally, the preparation of polyimide with low dielectric constant and dielectric loss can take three major methods: hole formation, physical doping and chemical structure design. Pore formation refers to the formation of microporous structures in polyimide by means of thermal degradation, etching and doping with microporous materials, which can greatly reduce the dielectric constant, but the mechanical properties are poor, and the Young's modulus is also very low. Can not effectively reduce the dielectric loss and water absorption. Physical doping refers to the physical mixing of organic fluorine compounds and inorganic low dielectric loss fillers into polyimide. Although it can reduce the dielectric constant of polyimide, it also seriously affects the hybrid polyimide. Properties of amine films, including electrical properties and environmental suitability. In addition, polyimides also exhibit poor compatibility with blends, making it difficult to obtain films with high mechanical properties. Through chemical structure design, a variety of dianhydride monomers or diamine monomers with different molecular structures are used to prepare polyimide polymers with diverse structures, so that the dielectric properties can be widely adjusted. Among them, the use of fluorine-containing monomers to synthesize fluorine-containing polyimides, the presence of fluorine atoms can reduce the water absorption of polyimides, reduce the electronic polarizability and thereby reduce the dielectric constant and dielectric loss, but this preparation strategy not only Dimensional stability and adhesiveness are deteriorated, and the preparation cost of the fluorine-containing material is high. In addition, low dielectric properties and low moisture absorption have certain mutual constraints. For example, increasing the free volume of the material structure can reduce the dielectric constant, but the large free volume of the material structure will make the material easier to absorb water. Therefore, how to reduce the dielectric constant? Establishing a balance between moisture absorption and moisture absorption is the key point. Therefore, it is of great scientific value and application significance to develop a polyimide material with low dielectric loss and low water absorption.

Contents of the invention

The object of the present invention is to provide a kind of diamine monomer, polyimide material, its preparation method and application, the polyimide material prepared by diamine monomer in the present invention has low dielectric loss, low water absorption rate and good moldability.

The present invention provides a kind of diamine monomer, has the structure shown in formula I:

In Formula I, 0≤x≤10.

The present invention provides a polyimide material, which is prepared from dianhydride monomers and the diamine monomers described in claim 1, and has a structure shown in formula II:

R1 and R2 are tetravalent aromatic or aliphatic hydrocarbon groups, m and n indicate the degree of polymerization, and m/n=0 to 100%.

Preferably, the R1 and R2 are each independently selected from the structures shown in any one of 1-14:

Preferably, said 0≤m≤300, 0≤n≤300.

The present invention provides the preparation method of polyimide material as described above, comprises the following steps:

Under a protective atmosphere, the dianhydride monomer having the R1 and/or R2 structure is reacted with the diamine monomer described in claim 1 in an aprotic organic solvent to obtain a polyamic acid;

The polyamic acid is subjected to a dehydration imidization ring closure reaction to obtain a polyimide material.

Preferably, the molar ratio of the dianhydride monomer having the R1 and/or R2 structure to the diamine monomer according to claim 1 is (0.9˜1.2):1.

Preferably, the aprotic polar organic solvent is N,N-dimethylformamide, dimethylsulfoxide, dimethylsulfone, sulfolane, trichlorobenzene, N-methyl-2-pyrrolidone and m- One or more of cresols.

The present invention provides the application of the above-mentioned diamine monomer or the above-mentioned polyimide material in high-frequency and high-speed communication materials, flexible high-frequency circuit board substrates and organic transistor devices.

The present invention provides the above-mentioned diamine monomer or the above-mentioned polyimide material in reducing the dielectric loss and moisture absorption of high-frequency and high-speed communication materials, flexible high-frequency circuit board substrates and organic transistor devices in the application.

The invention provides a diamine monomer, which has a structure shown in formula I. The invention introduces a low polarizability long alkyl side chain structure into the polyimide side chain molecular structure, and the long alkyl chain can destroy polyimide The close packing of the imine main chain can obtain a larger molecular free volume to further reduce the dielectric constant of the polyimide, and it also has a lower dielectric loss; in addition, the long alkyl chains distributed on the surface of the film can also It can improve the hydrophobicity of the material and reduce the water absorption to achieve low dielectric and low moisture absorption properties at the same time. Furthermore, the polyimide material with low dielectric loss and low moisture absorption rate described in the present invention can meet important applications in the fields of high-frequency information communication technology, flexible high-frequency circuit board substrates, and optoelectronic devices.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention, and those skilled in the art can also obtain other drawings according to the provided drawings without creative work.

Fig. 1 is the total reflection infrared spectrogram of embodiment 1～3 and comparative example 1,2 polyimide;

Fig. 2 is the proton nuclear magnetic resonance spectrogram of embodiment 1～3 and comparative example 1,2 polyimide;

Fig. 3 is the water contact angle of the polyimide film of Examples 1-3 and Comparative Examples 1 and 2.

Detailed ways

The present invention provides a kind of diamine monomer, has the structure shown in formula I:

In Formula I, 0≤x≤10.

Specifically, in the embodiment of the present invention, x can be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, preferably a range value with any of the above-mentioned values as the upper limit or lower limit.

The present invention has no special limitation on the preparation method of the diamine monomer. For diamine monomers containing alkyl side chain structures of different lengths, those skilled in the art can design a synthetic route according to the specific molecular structure required in practice. A series of reactions such as substitution and reduction are used to synthesize, for example, the following steps can be included: (1) 2,5-dinitrobenzoyl chloride and n-alkyl alcohol compounds (such as n-octanol, n-decyl alcohol, 1-dodecanol etc.) Substitution reactions occur to obtain dinitrobenzene compounds containing alkyl chains of different lengths; (2) the above-mentioned dinitrobenzene compounds containing alkyl side chains of different lengths and iron powder/ammonium chloride or Pd/C or Zn /HCl, etc. undergo reduction reactions to obtain diamine compounds with alkyl side chain structures of different lengths. The preparation process can be realized by those skilled in the art according to conventional reactions in this field, and the present invention will not repeat it here.

The present invention also provides a polyimide material, which is prepared from dianhydride monomers and the diamine monomers described in claim 1, and has a structure shown in formula II:

R1 and R2 are tetravalent aromatic or aliphatic hydrocarbon groups, m and n indicate the degree of polymerization, and m/n=0 to 100%.

In the present invention, the structures of R1 and R2 can be the same or different, and the R1 and R2 are independently selected from the structures shown in any one of 1-14:

In the present invention, m and n represent the degree of polymerization, 0≤m≤300, preferably, 50≤m≤300, more preferably 100≤m≤300; 0≤n≤100, preferably, 50≤n≤300 , 100≤n≤300. m/n=0～100%, preferably 10～90%, such as 0%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, preferably a range value with any of the above values as the upper or lower limit.

The present invention also provides a kind of preparation method of above-mentioned polyimide material, comprises the following steps:

Under a protective atmosphere, the dianhydride monomer having the R1 and/or R2 structure is reacted with the diamine monomer described in claim 1 in an aprotic organic solvent to obtain a polyamic acid;

The polyamic acid is subjected to a dehydration imidization ring closure reaction to obtain a polyimide material.

In the present invention, the protective atmosphere is preferably nitrogen and/or argon; in the present invention, the dianhydride monomer with the structure shown in R1 can be used, and the dianhydride monomer with the structure shown in R2 can also be used , it can also be a mixed dianhydride monomer having a dianhydride monomer having a structure shown in R1 and a dianhydride monomer having a structure shown in R2, and the molar ratio of the diamine monomer to the dianhydride monomer is preferably 1: (0.9-1.2), more preferably 1:(1-1.1), such as 1:0.9, 1:1, 1:1.1, 1:1.2, preferably a range value with any of the above-mentioned values as the upper or lower limit.

The aprotic polar organic solvent is preferably N,N-dimethylformamide, dimethylsulfoxide, dimethylsulfone, sulfolane, trichlorobenzene, N-methyl-2-pyrrolidone and m-cresol one or more of them.

In the present invention, the reaction temperature of the dianhydride monomer and the diamine monomer is preferably normal temperature, such as 20-30°C; the reaction time is preferably 4-20 hours, more preferably 6-15 hours.

In the present invention, the dehydration imidization and ring closure reaction of polyamic acid may be high temperature thermal imidization or low temperature chemical imidization.

In the present invention, the specific steps of the high temperature thermal imidization are as follows:

The polyamic acid is coated on the surface of the substrate, the temperature is programmed to be raised, and thermal imidization is carried out; then the temperature is lowered to room temperature, and the mold is demoulded to obtain a film, and the film is dried to remove water to obtain a polyimide film.

In the present invention, the temperature programming process is preferably: the room temperature is raised to 80-120°C, and the temperature is kept constant for 20-60 minutes; the temperature is then raised to 120-200°C, and the constant temperature is 20-60 minutes; 60min; finally heat up to 260~320℃, keep the temperature for 20~60min;

In the present invention, the temperature for drying and removing water is preferably 90-110°C, more preferably 100°C.

In the present invention, the specific steps of the chemical imidization are as follows:

Adding a dehydrating agent to the polyamic acid for reaction, then pouring the reaction solution into an excess of methanol solvent for sedimentation and purification, and drying the solid sample after suction filtration to obtain a polyimide powder material;

In the present invention, the dehydrating agent is preferably acetic anhydride and/or pyridine; the reaction time after adding the dehydrating agent is preferably 8 to 20 hours, more preferably 10 to 15 hours; the drying is preferably vacuum drying, The vacuum drying temperature is preferably 80-120°C, more preferably 90-110°C, most preferably 100°C; the vacuum drying time is preferably 8-15 hours, more preferably 10-12 hours.

Further, the polyimide powder material can be prepared by dissolving the polyimide powder in a solvent, coating, drying to remove the solvent, demolding and drying to obtain a polyimide film.

In the present invention, the solvent is preferably N,N-dimethylformamide, dimethylsulfoxide, dimethylsulfone, sulfolane, trichlorobenzene, N-methyl-2-pyrrolidone, m-cresol, One or more of dichloromethane, chloroform and cyclopentanone; the present invention preferably removes the solvent by drying at 200-300°C; the drying temperature is preferably 80-120°C, more preferably 90-110°C , most preferably at 100°C.

The present invention also provides an application of the above-mentioned diamine monomer or the above-mentioned polyimide material in high-frequency and high-speed communication materials, flexible high-frequency circuit board substrates and organic transistor devices, The diamine monomer and polyimide material are used to reduce the dielectric loss and moisture absorption rate of the material.

The invention provides a diamine monomer, which has a structure shown in formula I. The invention introduces a low polarizability long alkyl side chain structure into the polyimide side chain molecular structure, and the long alkyl chain can destroy polyimide The close packing of the imine main chain can obtain a larger molecular free volume to further reduce the dielectric constant of the polyimide, and it also has a lower dielectric loss; in addition, the long alkyl chains distributed on the surface of the film can also It can improve the hydrophobicity of the material and reduce the water absorption to achieve low dielectric and low moisture absorption properties at the same time. Furthermore, the polyimide material with low dielectric loss and low moisture absorption rate described in the present invention can meet important applications in the fields of high-frequency information communication technology, flexible high-frequency circuit board substrates, and optoelectronic devices.

In order to further illustrate the present invention, a diamine monomer, a polyimide material provided by the present invention, its preparation method and application are described in detail below in conjunction with the examples, but it should not be understood as limiting the protection scope of the present invention.

Example 1:

Dissolve 3.91g (30mmol) of 1-octanol and 4.55g (45mmol) of triethylamine in 100mL of tetrahydrofuran, slowly add 8.30g (36mmol) of 3,5-dinitrobenzoyl chloride, and stir for 12 hours in an ice-water bath. The reaction was quenched by adding 10 mL of saturated aqueous sodium bicarbonate solution, extracted, and ethyl acetate/petroleum ether column chromatography was used to obtain the target product 3,5-octyl dinitrobenzoate. ¹ H-NMR (500MHz, CDCl ₃ ) δ9.16(t,1H),9.09(d,2H),4.38(t,2H),1.76(m,2H),1.38(m,2H),1.31-1.18 (m,10H), 0.81(t,3H).

Add 8.1g (25mmol) octyl 3,5-dinitrobenzoate, 11.2g (200mmol) reduced iron powder, and 5.35g (100mmol) ammonium chloride to a mixed solution of 50mL water and 100mL ethanol, and stir at 80°C for 12h , after filtration, extraction and drying, the target product 3,5-octyl diaminobenzoate was obtained. ¹ H-NMR (500MHz, CDCl ₃ ) δ6.78(d,2H),6.19(t,1H),4.25(t,2H),3.67(s,4H),1.73(m,2H),1.42(m ,2H), 1.35-1.28(m,10H), 0.88(t,3H).

In the present embodiment, the molecular structural formula of monomer 3,5-octyl diaminobenzoate is as follows:

At room temperature, add 2.64g (10mmol) octyl 3,5-diaminobenzoate and 40mL N,N-dimethylformamide into a 100mL flask and stir for 1h, add 4.44g (10mmol) 4,4-hexa Fluoroisopropylene diphthalic anhydride, polyamic acid solution was obtained after reacting for 5 hours. After adding 7 mL of pyridine and 2 mL of acetic anhydride, reacted for 24 hours, poured the reaction solution into excess methanol to obtain polyimide solid powder, which was designated as PI-C ₈ .

The molecular structural formula of the low dielectric polyimide PI-C ₈ in the present embodiment is as follows:

where 100≤n≤300.

Example 2:

Dissolve 4.74g (30mmol) of 1-decanol and 4.55g (45mmol) of triethylamine in 100mL of tetrahydrofuran, slowly add 8.30g (36mmol) of 3,5-dinitrobenzoyl chloride, and stir for 12 hours in an ice-water bath. The reaction was quenched by adding 10 mL of saturated aqueous sodium bicarbonate solution, extracted, and ethyl acetate/petroleum ether column chromatography was used to obtain the target product decyl 3,5-dinitrobenzoate. ¹ H-NMR (500MHz, CDCl ₃ ) δ9.16(t,1H),9.09(d,2H),4.38(t,2H),1.76(m,2H),1.38(m,2H),1.31-1.18 (m,14H), 0.81(t,3H).

Add 8.8g (25mmol) decyl 3,5-dinitrobenzoate, 11.2g (200mmol) reduced iron powder, and 5.35g (100mmol) ammonium chloride to a mixed solution of 50mL water and 100mL ethanol, and stir at 80°C for 12h , filtered, extracted and dried to obtain the target product 3,5-decyl diaminobenzoate. ¹ H-NMR (500MHz, CDCl ₃ ) δ6.78(d,2H),6.19(t,1H),4.25(t,2H),3.67(s,4H),1.73(m,2H),1.42(m ,2H), 1.35-1.28(m,14H), 0.88(t,3H).

In the present embodiment, the molecular structural formula of monomer 3,5-decyl diaminobenzoate is as follows:

At room temperature, add 2.92g (10mmol) decyl 3,5-diaminobenzoate and 40mL N,N-dimethylformamide into a 100mL flask and stir for 1h, add 4.44g (10mmol) 4,4-hexa Fluoroisopropylene diphthalic anhydride, polyamic acid solution was obtained after reacting for 5 hours. After adding 7 mL of pyridine and 2 mL of acetic anhydride, reacted for 24 hours, poured the reaction solution into excess methanol to obtain polyimide solid powder, which was designated as PI-C ₁₀ .

The molecular structural formula of low dielectric polyimide PI-C ₁₀ in the present embodiment is as follows:

where 100≤n≤300.

Example 3:

Dissolve 5.58g (30mmol) of 1-dodecanol and 4.55g (45mmol) of triethylamine in 100mL of tetrahydrofuran, slowly add 8.30g (36mmol) of 3,5-dinitrobenzoyl chloride, and stir for 12 hours in an ice-water bath , adding 10 mL of saturated aqueous sodium bicarbonate solution to quench the reaction, extraction, ethyl acetate/petroleum ether column chromatography to obtain the target product 3,5-dodecyl dinitrobenzoate. ¹ H-NMR (500MHz, CDCl ₃ ) δ9.16(t,1H),9.09(d,2H),4.38(t,2H),1.76(m,2H),1.38(m,2H),1.31-1.18 (m,18H), 0.81(t,3H).

Add 9.5g (25mmol) dodecyl 3,5-dinitrobenzoate, 11.2g (200mmol) reduced iron powder, and 5.35g (100mmol) ammonium chloride to a mixed solution of 50mL water and 100mL ethanol, at 80°C Stir for 12 hours, filter, extract and dry to obtain the target product 3,5-dodecyl diaminobenzoate. ¹ H-NMR (500MHz, CDCl ₃ ) δ6.78(d,2H),6.19(t,1H),4.25(t,2H),3.67(s,4H),1.73(m,2H),1.42(m ,2H), 1.35-1.28(m,18H), 0.88(t,3H).

In the present embodiment, the molecular structural formula of monomer 3,5-dodecyl diaminobenzoate is as follows:

At room temperature, add 3.20g (10mmol) dodecyl 3,5-diaminobenzoate and 40mL N,N-dimethylformamide into a 100mL flask and stir for 1h, add 4.44g (10mmol) 4,4 - Hexafluoroisopropylene diphthalic anhydride, polyamic acid solution was obtained after reacting for 5 hours. After adding 7 mL of pyridine and 2 mL of acetic anhydride, reacted for 24 hours, poured the reaction solution into excess methanol to obtain polyimide solid powder, which was designated as PI-C ₁₂ .

The molecular structural formula of the low dielectric polyimide PI-C ₁₂ in the present embodiment is as follows:

where 100≤n≤300.

Example 4:

Dissolve 6.42g (30mmol) of 1-tetradecyl alcohol and 4.55g (45mmol) of triethylamine in 100mL of tetrahydrofuran, slowly add 8.30g (36mmol) of 3,5-dinitrobenzoyl chloride, and stir for 12 hours in an ice-water bath , adding 10 mL of saturated aqueous sodium bicarbonate solution to quench the reaction, extraction, ethyl acetate/petroleum ether column chromatography to obtain the target product 3,5-tetradecyl dinitrobenzoate. ¹ H-NMR (500MHz, CDCl ₃ ) δ9.16(t,1H),9.09(d,2H),4.38(t,2H),1.76(m,2H),1.38(m,2H),1.31-1.18 (m,22H), 0.81(t,3H).

10.2g (25mmol) tetradecyl 3,5-dinitrobenzoate, 11.2g (200mmol) reduced iron powder, 5.35g (100mmol) ammonium chloride were added to a mixed solution of 50mL water and 100mL ethanol, at 80°C Stir for 12 hours, filter, extract and dry to obtain the target product 3,5-tetradecyl diaminobenzoate. ¹ H-NMR (500MHz, CDCl ₃ ) δ6.78(d,2H),6.19(t,1H),4.25(t,2H),3.67(s,4H),1.73(m,2H),1.42(m ,2H), 1.35-1.28(m,22H), 0.88(t,3H).

In the present embodiment, the molecular structural formula of monomer 3,5-tetradecyl diaminobenzoate is as follows:

At room temperature, add 3.48g (10mmol) tetradecyl 3,5-diaminobenzoate and 40mL N,N-dimethylformamide into a 100mL flask and stir for 1h, add 4.44g (10mmol) 4,4 - Hexafluoroisopropylene diphthalic anhydride, polyamic acid solution was obtained after reacting for 5 hours. After adding 7 mL of pyridine and 2 mL of acetic anhydride, reacted for 24 hours, poured the reaction solution into excess methanol to obtain polyimide solid powder, which was designated as PI-C ₁₄ .

The molecular structural formula of low dielectric polyimide PI-C ₁₄ in the present embodiment is as follows:

where 100≤n≤300.

Example 5:

Dissolve 7.26g (30mmol) of 1-hexadecanol and 4.55g (45mmol) of triethylamine in 100mL of tetrahydrofuran, slowly add 8.30g (36mmol) of 3,5-dinitrobenzoyl chloride, and stir for 12 hours in an ice-water bath , adding 10 mL of saturated aqueous sodium bicarbonate solution to quench the reaction, extraction, and ethyl acetate/petroleum ether column chromatography to obtain the target product 3,5-dinitrobenzoic acid cetyl alcohol ester. ¹ H-NMR (500MHz, CDCl ₃ ) δ9.16(t,1H),9.09(d,2H),4.38(t,2H),1.76(m,2H),1.38(m,2H),1.31-1.18 (m,26H), 0.81(t,3H).

Add 10.9g (25mmol) cetyl alcohol 3,5-dinitrobenzoate, 11.2g (200mmol) reduced iron powder, 5.35g (100mmol) ammonium chloride to a mixed solution of 50mL water and 100mL ethanol, at 80°C Stir for 12 hours, filter, extract, and dry to obtain the target product 3,5-diaminobenzoic acid cetyl alcohol ester. ¹ H-NMR (500MHz, CDCl ₃ ) δ6.78(d,2H),6.19(t,1H),4.25(t,2H),3.67(s,4H),1.73(m,2H),1.42(m ,2H), 1.35-1.28(m,26H), 0.88(t,3H).

The molecular structural formula of monomer 3,5-diaminobenzoic acid cetyl alcohol ester in the present embodiment is as follows:

At room temperature, add 3.76g (10mmol) hexadecyl 3,5-diaminobenzoate and 40mL N,N-dimethylformamide into a 100mL flask and stir for 1h, add 4.44g (10mmol) 4,4 - Hexafluoroisopropylene diphthalic anhydride, polyamic acid solution was obtained after reacting for 5 hours. After adding 7 mL of pyridine and 2 mL of acetic anhydride, react for 24 hours, pour the reaction solution into excess methanol to obtain polyimide solid powder, which is designated as PI-C ₁₆ .

The molecular structural formula of the low dielectric polyimide PI-C ₁₆ in the present embodiment is as follows:

where 100≤n≤300.

Embodiment 6:

8.10g (30mmol) 1-octadecyl alcohol and 4.55g (45mmol) triethylamine were dissolved in 100mL tetrahydrofuran, and 8.30g (36mmol) 3,5-dinitrobenzoyl chloride was slowly added, and the reaction was stirred for 12 hours in an ice-water bath , adding 10 mL of saturated aqueous sodium bicarbonate solution to quench the reaction, extraction, ethyl acetate/petroleum ether column chromatography to obtain the target product 3,5-dinitrobenzoic acid stearyl ester. ¹ H-NMR (500MHz, CDCl ₃ ) δ9.16(t,1H),9.09(d,2H),4.38(t,2H),1.76(m,2H),1.38(m,2H),1.31-1.18 (m,30H), 0.81(t,3H).

11.6g (25mmol) octadecyl 3,5-dinitrobenzoate, 11.2g (200mmol) reduced iron powder, 5.35g (100mmol) ammonium chloride were added to a mixed solution of 50mL water and 100mL ethanol, at 80°C Stir for 12 hours, filter, extract and dry to obtain the target product 3,5-diaminobenzoic acid stearyl ester. ¹ H-NMR (500MHz, CDCl ₃ ) δ6.78(d,2H),6.19(t,1H),4.25(t,2H),3.67(s,4H),1.73(m,2H),1.42(m ,2H), 1.35-1.28(m,30H), 0.88(t,3H).

In the present embodiment, monomer 3, the molecular structural formula of 5-diaminobenzoic acid stearyl ester is as follows:

At room temperature, add 4.04g (10mmol) octadecyl 3,5-diaminobenzoate and 40mL N,N-dimethylformamide into a 100mL flask and stir for 1h, add 4.44g (10mmol) 4,4 - Hexafluoroisopropylene diphthalic anhydride, polyamic acid solution was obtained after reacting for 5 hours. After adding 7 mL of pyridine and 2 mL of acetic anhydride, reacted for 24 hours, poured the reaction solution into excess methanol to obtain polyimide solid powder, which was designated as PI-C ₁₈ .

The molecular structural formula of low dielectric polyimide PI-C ₁₈ in the present embodiment is as follows:

where 100≤n≤300.

Embodiment 7:

Dissolve 8.94g (30mmol) 1-eicosanol and 4.55g (45mmol) triethylamine in 100mL tetrahydrofuran, slowly add 8.30g (36mmol) 3,5-dinitrobenzoyl chloride, and stir for 12 hours in an ice-water bath , adding 10 mL of saturated aqueous sodium bicarbonate solution to quench the reaction, extraction, ethyl acetate/petroleum ether column chromatography to obtain the target product eicosyl 3,5-dinitrobenzoate. ¹ H-NMR (500MHz, CDCl ₃ ) δ9.16(t,1H),9.09(d,2H),4.38(t,2H),1.76(m,2H),1.38(m,2H),1.31-1.18 (m,34H), 0.81(t,3H).

Add 12.3g (25mmol) eicosyl 3,5-dinitrobenzoate, 11.2g (200mmol) reduced iron powder, and 5.35g (100mmol) ammonium chloride to a mixed solution of 50mL water and 100mL ethanol, at 80°C Stir for 12 hours, filter, extract, and dry to obtain the target product 3,5-diaminobenzoic acid eicosyl ester. ¹ H-NMR (500MHz, CDCl ₃ ) δ6.78(d,2H),6.19(t,1H),4.25(t,2H),3.67(s,4H),1.73(m,2H),1.42(m ,2H), 1.35-1.28(m,34H), 0.88(t,3H).

In the present embodiment, the molecular structural formula of monomer 3,5-diaminobenzoic acid eicosyl ester is as follows:

At room temperature, add 4.32g (10mmol) eicosyl 3,5-diaminobenzoate and 40mL N,N-dimethylformamide into a 100mL flask and stir for 1h, add 4.44g (10mmol) 4,4 - Hexafluoroisopropylene diphthalic anhydride, polyamic acid solution was obtained after reacting for 5 hours. After adding 7 mL of pyridine and 2 mL of acetic anhydride, reacted for 24 hours, poured the reaction solution into excess methanol to obtain polyimide solid powder, which was designated as PI-C ₂₀ .

The molecular structural formula of the low dielectric polyimide PI-C ₂₀ in the present embodiment is as follows:

where 100≤n≤300.

Comparative example 1:

At room temperature, add 1.08g (10mmol) m-phenylenediamine and 40mL N,N-dimethylformamide into a 100mL flask and stir for 1h, add 4.44g (10mmol) 4,4-hexafluoroisopropene diphthalic anhydride , A polyamic acid solution was obtained after reacting for 5 h. After adding 7 mL of pyridine and 2 mL of acetic anhydride, reacted for 24 hours, poured the reaction solution into excess methanol to obtain polyimide solid powder, which was designated as PI-6FDA-C ₀ .

The molecular structural formula of low dielectric polyimide PI-6FDA-C ₀ in the present embodiment is as follows:

where 100≤n≤300.

Comparative example 2:

At room temperature, add 3.56g (10mmol) of phenylenediamine with ten long carbon chains and 40mL of N,N-dimethylformamide into a 100mL flask and stir for 1h, then add 4.44g (10mmol) of 4,4 - Hexafluoroisopropylene diphthalic anhydride, polyamic acid solution was obtained after reacting for 5 hours. After adding 7 mL of pyridine and 2 mL of acetic anhydride, reacted for 24 hours, poured the reaction solution into excess methanol to obtain polyimide solid powder, which was designated as PI-6FDA-C ₁₀ .

The molecular structural formula of low dielectric polyimide PI-BPDA-C ₀ in the present embodiment is as follows:

where n≥100

Fig. 1 is the total reflection infrared spectrogram of the polyimide of Examples 1-3 and Comparative Examples 1 and 2, from which it can be seen that there are imide rings at 1720cm ^-1 , 1370cm ^-1 , and 725cm ^-1 There are asymmetric stretching vibration absorption peaks and symmetrical stretching vibration absorption peaks of methylene at 2850cm ^-1 and 2920cm ^-1 .

Fig. 2 is the hydrogen nuclear magnetic resonance spectrogram of embodiment 1～3 and comparative example 1,2 polyimide, can get from this figure when using deuterated chloroform as solvent, chemical shift 8～7.3ppm place and polyimide The imine corresponds to the benzene ring, and 4.0-5.0ppm and 0.5-2.0ppm correspond to the hydrogen on the side chain of the alkyl group.

Fig. 3 is the water contact angle of embodiment 1～3 and comparative example 1,2 polyimide membrane film, can find out from the figure that the water contact angle of PI-6FDA-C ₀ is the lowest, followed by PI-6FDA-C ₁₀ , and finally PI-C ₈ , PI-6FDA-C ₁₀ , and PI-C ₁₂ .

The polyimide material that embodiment 1～7 and comparative example 1, 2 obtains is dissolved in cyclopentanone solvent and is mixed with the solution of 3% mass fraction, is coated on the liquid film of uniform thickness on the glass substrate again, then gradually Raise the temperature to 150°C for 2 hours, then cool down to room temperature and take it out, then put it in water to remove the film to obtain a film, put the excess film in a drying oven at 100°C to dry and remove water, and then a polyamide film with a film thickness of 100 microns can be obtained. imide film;

The polyimide film that embodiment 1～7 and comparative example 1, 2 are obtained carries out performance test 3 times according to following method, and the result is with reference to table 1:

Dielectric properties: Tested with KEYSIGHT-N5224B vector network analyzer, the test frequency is 10GHz, the film sample size is 5*3cm, and the test results are dielectric constant and dielectric loss;

Saturated water absorption: test with reference to the standard IPC-TM-650 2.6.2D, the sample size is 5*5cm, soak in deionized water in a 25°C thermostat for 24 hours, then wipe the surface of the film to test, water absorption = ( Mass after soaking in water - mass before soaking in water)/mass before soaking in water*100%;

Table 1 is the performance test result of the polyimide film that embodiment and comparative example obtain

As can be seen from the above performance test results, compared with Comparative Example 1, as the length of the alkyl chain in the polyimide side chain increases in Examples 1 to 7, its dielectric constant and dielectric loss are all decreasing. And due to the introduction of long alkyl side chains, the saturated water absorption of polyimide is also greatly reduced. It is worth noting that compared with Example 2, the dielectric constant and dielectric loss of the polyimide whose main chain contains long alkyl chains in Comparative Example 2 are almost the same, but the saturated water absorption is higher than that of Example 2. , which shows that the long alkyl side chain structure with low polarizability is introduced into the polyimide side chain molecular structure, and the long alkyl chain can destroy the close packing of the polyimide main chain, obtain a larger molecular free volume and further reduce The dielectric constant of polyimide, and it also has a low dielectric loss; in addition, the long alkyl chains distributed on the surface of the film can also improve the hydrophobicity of the material, reduce the water absorption rate, and achieve low dielectric and low dielectric loss at the same time. Moisture absorption performance. Therefore, the preparation method of a diamine monomer and polyimide material with low dielectric loss and low moisture absorption rate proposed by the present invention shows great application prospects.

The above is only a preferred embodiment of the present invention, it should be pointed out that, for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (9)

1. A diamine monomer having a structure shown in formula I:

In Formula I, 0≤x≤10. 2. a kind of polyimide material, is prepared by dianhydride monomer and diamine monomer described in claim 1, has structure shown in formula II:

R1 and R2 are tetravalent aromatic or aliphatic hydrocarbon groups, m and n indicate the degree of polymerization, and m/n=0 to 100%. 3. The polyimide material according to claim 2, wherein said R1 and R2 are independently selected from the structures shown in any one of 1 to 14:

4. The polyimide material according to claim 2, characterized in that 0≤m≤300, 0≤n≤300. 5. the preparation method of polyimide material as claimed in claim 2, comprises the following steps: Under a protective atmosphere, the dianhydride monomer having the R1 and/or R2 structure is reacted with the diamine monomer described in claim 1 in an aprotic organic solvent to obtain a polyamic acid; The polyamic acid is subjected to a dehydration imidization ring closure reaction to obtain a polyimide material. 6. The preparation method according to claim 5, characterized in that, the molar ratio of the dianhydride monomer with R1 and/or R2 structure to the diamine monomer according to claim 1 is (0.9-1.2) :1. 7. The preparation method according to claim 5, wherein the aprotic polar organic solvent is N,N-dimethylformamide, dimethyl sulfoxide, dimethyl sulfone, sulfolane, tris One or more of chlorobenzene, N-methyl-2-pyrrolidone and m-cresol. 8. The application of the diamine monomer as claimed in claim 1 or the polyimide material as claimed in claim 2 in high-frequency and high-speed communication materials, flexible high-frequency circuit board substrates and organic transistor devices. 9. Diamine monomer as claimed in claim 1 or the polyimide material as claimed in claim 2 reduce the dielectric loss of high-frequency and high-speed communication materials, flexible high-frequency circuit board substrates and organic transistor devices and application in moisture absorption.

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