TW202233910A - Polyimide film as well as preparation method and application thereof - Google Patents

Abstract

The invention relates to a polyimide film as well as a preparation method and application thereof. The polyimide film comprises a repeating unit shown in the following chemical formula (1), structures such as F or CF3, an ether group and an ester group are further introduced into polyimide on the basis of biphenyl, terphenyl and other long-chain frameworks, the concentration of the imide group in the molecular structure is optimized, the flexibility and regularity of a chain segment are effectively improved, and therefore, the polyimide film with low water absorption, low dielectric properties (dielectric constant D and dielectric loss Df), and high heat resistance is realized, wherein Dk ≤ 3.40 and Df ≤ 0.005; meanwhile, the low water absorption rate smaller than or equal to 0.7% and the high heat resistance can be achieved, wherein T5% is larger than 500 DEG C; and the polyimide film is suitable for the fields of high-frequency flexible circuit substrate materials, high-frequency high-speed communication materials and the like.

Description

A kind of polyimide film and its preparation method and application

The invention relates to the technical field of polymer materials, in particular to the technical field of high-frequency polyimide films. Specifically, it relates to a polyimide film and its preparation method and application.

With the development of light, thin, portable and multi-functional electronic products, as well as the high frequency and high speed development requirements of information processing for signal transmission, high requirements are placed on the heat resistance of materials. The requirements for electrical constant and low dielectric loss are also becoming more and more stringent, which promotes the further development of low-dielectric materials, and has become one of the materials that need to be developed in the high-frequency field.

Polyimide exhibits good heat resistance due to its unique aromatic conjugated structure in its structure, but its high water absorption, dielectric constant and dielectric loss greatly limit the performance of other materials in high-frequency and high-speed fields. application.

0.007，氮氣氛圍下薄膜熱失重5%時的溫度(T5%)為500℃以上，但仍存在吸水率和介電性能偏高等問題。 In order to solve the problems of poor water absorption and poor dielectric properties of the above-mentioned polyimide, patent CN109843588A discloses a polyimide film for metal lamination and a polyimide metal laminate using the same. The dianhydride reacts with the long-chain skeleton aromatic diamine to reduce the concentration of imide groups in the molecular structure. At the same time, a low dielectric loss and high heat resistance polyimide film was successfully prepared. electrical loss tangent

0.007, the temperature (T5%) of the film at 5% thermal weight loss under nitrogen atmosphere is above 500 °C, but there are still problems such as high water absorption and dielectric properties.

Based on this, the present invention provides a polyimide, which further introduces structures such as F or CF ₃ , ether groups and ester groups on the basis of long-chain skeletons such as biphenyl and terphenyl, and optimizes the molecular structure of amides. The concentration of the imine group effectively increases the flexibility and regularity of the chain segment, thereby realizing a polyimide film with low water absorption, low dielectric properties and good heat resistance, which is suitable for high-frequency flexibility. It is used in the fields of circuit board materials and high-frequency high-speed communication materials.

A first object of the present invention is to provide a polyimide film comprising a repeating unit represented by the following chemical formula (1),

Wherein A ₁ represents a tetravalent residue, A ₂ is a divalent residue;

In the shown chemical formula (1), A ₂ is composed of units represented by both chemical formula (2) and chemical formula (3);

Wherein, R ₁ and R ₂ are selected from one of H, halogen atom, halogenated alkanes containing 1 to ₃ carbon atoms; preferably one of H, F and CF , and R ₁ and R ₂ are the same or different;

Wherein, X ₁ is selected from one or more of-, -O-, -C(O)-, , , and; and R ₃ =H or CF ₃ ;

Wherein, the repeating unit represented by the chemical formula (1) is obtained by polycondensation and imidization of diamine and dianhydride, wherein the unit represented by the chemical formula (2) accounts for 10~90% of the total proportion of the diamine; chemical formula (3) The indicated unit accounts for 10~90% of the total proportion of diamine;

The units represented by the chemical formula (2) and the chemical formula (3) account for more than 90% of the total proportion of the diamine.

In the shown chemical formula (1), A ₁ represents the structure shown in the chemical formula (4),

、

、-C(O)-、-C(CF₃)₂-和

中 的一種或多種；且R₄=H或CF₃； Wherein, X ₂ is selected from—,

,

, -C(O)-, -C(CF ₃ ) ₂ - and

one or more of; and R ₄ =H or CF ₃ ;

Among them, the unit represented by the chemical formula (4) accounts for more than 90% of the total proportion of the dianhydride.

Wherein X ₂ =─or, the unit represented by chemical formula (4) accounts for 35~85% of the total proportion of dianhydride;

The chemical formula (2) is preferably one or more of the following structures;

The chemical formula (3) is preferably one or more of the following structures;

The chemical formula (4) is preferably one or more of the following structures;

In the polyimide of the present invention, by introducing long-chain skeletons such as biphenyl and terphenyl into the molecular structure, and further introducing structures such as F or CF ₃ , ether groups and ester groups, the imide in the molecular structure is optimized. At the same time of the concentration of the base, the flexibility and regularity of the segment are effectively increased, thereby realizing a polyimide film with low water absorption, low dielectric properties and good heat resistance, which is used in high-frequency flexible circuit substrate materials and It has good application prospects in the fields of high-frequency and high-speed communication materials.

The second object of the present invention is to provide a preparation method of the polyimide film, comprising the following steps:

(1) Under the protection of inert gas, diamine and dianhydride are successively dissolved in an organic solvent, and the polymerization reaction obtains a polyamide acid solution with a solid content of 10-30%;

Preferably, the temperature of the polymerization reaction is 25-100° C., and the time is 1-12 h.

(2) The polyamide acid solution prepared in step (1) is made into a wet film on the glass substrate; or after the polyamide acid solution prepared in step (1) and the imidization reagent are prepared into a solution, the solution is placed on the glass substrate. Wet film is made on it;

Preferably, the wet film is formed by coating on a glass substrate with a doctor blade.

(3) heat treatment is carried out after the pre-drying of the wet film prepared in step (2), and further imidization is performed to prepare a polyimide film;

Preferably, the temperature of the pre-drying is 80-120° C., and the time is 20-40 min.

Preferably, the heat treatment is to pre-dry the wet film, and then treat at 150°C/250°C/300°C/350-450°C for 30 minutes, respectively.

Preferably, the imidization reagent is a solution prepared by an organic solvent, a dehydrating agent and a promoter.

Wherein, the organic solvent is selected from N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dimethylacetamide (DMF), One or more of sulfoxide (DMSO), m-cresol, chloroform, tetrahydrofuran (THF), γ-butyrolactone and 3-methyl-N,N dimethylpropionamide;

The dehydrating agent is selected from one or more of acetic anhydride, propionic anhydride, butyric anhydride and benzoic anhydride;

Described accelerator is selected from one or more in picoline, quinoline, isoquinoline, pyridine;

At the same time, the polyimide film of the present invention also comprises repeating structural units made from other dianhydrides and diamines that are different from the dianhydrides and diamines that form the repeating units represented by chemical formula (1);

Said other dianhydrides other than those forming the dianhydride of formula (1) include pyromellitic dianhydride (PMDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (α-BPDA) and 3 One or more of ,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA);

Said other diamines other than the diamines forming formula (1) include m-phenylenediamine (m-PDA), o-phenylenediamine (o-PDA), 4,4'-diaminodiphenylmethane (MDA), and one or more of 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB);

The third object of the present invention is to provide the application of the polyimide film in the fields of high-frequency flexible circuit substrate materials and high-frequency high-speed communication materials.

3.40，Df

0.005；同時可實現較低的吸水率

0.7%和良好的耐熱性，其中T5%>500℃； The polyimide film of the present invention has the characteristics of low dielectric constant (Dk) and low dielectric loss (Df), wherein Dk

3.40, Df

0.005; at the same time lower water absorption can be achieved

0.7% and good heat resistance, of which T5%>500℃;

The polyimide film of the present invention can be used in the fields of high-frequency flexible circuit substrate materials, high-frequency high-speed communication materials and the like.

The beneficial effects of the present invention are as follows:

The invention provides a polyimide film. On the basis of long-chain skeletons such as biphenyl and terphenyl, structures such as F or CF3, ether group and ester group are further introduced, and the molecular structure of the imide group is optimized. concentration At the same time, the flexibility and regularity of the segment are effectively increased, thereby realizing a polyimide film with low water absorption, low dielectric properties and good heat resistance, which can be applied to high-frequency flexible circuit substrate materials and High-frequency and high-speed communication materials and other fields.

The following examples are intended to illustrate the present invention, but not to limit the scope of the present invention.

Unless otherwise specified, the raw materials can be obtained from open commercial sources or self-made.

abbreviation for compound

TPDA: 5-[4-(1,3-Dioxo-2-benzofuran-5-yl)phenyl]-2-benzofuran-1,3-dione

TAHQ: p-phenylene-bis-trimellitate dianhydride

6FDA: 4,4'-(hexafluoroisopropene) diphthalic anhydride

TABP: p-biphenylene bis(trimellitic acid monoester anhydride)

6FTABP: p-2,2'-bis(trifluoromethyl)biphenylbis(trimellitic acid monoester anhydride)

6FBPADA: hexafluoroisopropyl bisphenol A diether dianhydride

s-BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride

ODPA: 4,4'-Oxydiphthalic anhydride

PMDA: pyromellitic dianhydride

PDA: 1,4-p-phenylenediamine

DATP: 4,4'-Diamino-p-terphenyl

DATP-FF: 2,3-bis(fluoro)-bis(4-aminophenyl)phenyl

DATP-2F: 3,3'-bis(fluoro)-4,4'-diamino-p-terphenyl

BAPP: 2,2-bis(4-(4-aminophenoxy)phenyl)propane

TFMB: 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl

m-TB: 2,2′-dimethyl-4,4′-diaminobiphenyl

APAB: p-aminophenylparaben

BPBT: 1,4-phenylene bis(4-aminobenzoate)

ABHQ: Di-p-aminophenyl terephthalate

6FODA: 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether

1,4,4-APB: 1,4-bis(4’-aminophenoxy)benzene

1,3,4-APB: 1,3-bis(4'-aminophenoxy)benzene

1,3,3-APB: 1,3-bis(3'-aminophenoxy)benzene

HFBAPP: 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane

Example 1

The reaction vessel was exhausted with nitrogen in advance. After 30 min, 165.39 g of N,N-dimethylacetamide (DMAc, water was removed with molecular sieves 24 h in advance) was added, and 9.76 g (37.5 mmol) of compound DATP and 2.16 g were added respectively. g (4.2 mmol) of compound HFBAPP, stirred at 25°C until completely dissolved; 6.13 g (20.8 mmol) of compound BPDA and 11.13 g (20.8 mmol) of compound TABP were gradually added, and the reaction was stirred at room temperature for 12 h, thereby obtaining 15 wt % polyamide. Amino acid solution.

After the reaction, acetic anhydride and isoquinoline with equimolar carboxylic acid groups were added respectively, and DMAc that had been dewatered was added to make a solution of 10 to 13 wt %; the obtained polyimide solution was coated on glass with a doctor blade. On the substrate, pre-drying at 80°C for 20min, then transferred to the needle plate, then transferred to the oven, heat-treated at 150°C/250°C/300°C/350°C for 30min respectively, and thermally imidized to obtain Polyimide film with a thickness of about 25 μm.

Example 2

The reaction vessel was exhausted with nitrogen in advance. After 30 min, 143.40 g of N,N-dimethylacetamide (DMAc, water was removed with molecular sieves for 24 h in advance) was added, and 0.98 g (3.8 mmol) of compound DATP, 1.94 g of DATP and 1.94 g of DATP were added respectively. g (3.8 mmol) compound HFBAPP and 6.85 g (30.0 mmol) compound APAB were stirred at 25°C until completely dissolved; then 5.52 g (18.8 mmol) compound BPDA and 10.02 g (18.8 mmol) compound TABP were gradually added, and the reaction was stirred at room temperature. 12h, thereby obtaining a 15wt% polyimide solution.

After the reaction, the obtained polyimide solution was coated on a glass substrate with a doctor blade, pre-dried at 80 °C for 30 min, and then transferred to a needle plate, and then transferred to an oven, respectively, at 150 °C/250 °C/ Thermal imidization was performed by heat treatment at 300° C./350° C. for 30 min, thereby producing a polyimide film having a thickness of about 25 μm .

Embodiment 3～15 and comparative example 1～5

Replace the diamine and dianhydride with the ratios shown in Table 1 and Table 2, respectively, carry out resin polymerization, and carry out resin polymerization at 25 ~ 100 ° C for 1h ~ 12h polymerization to obtain a polyamide with a solid content of 10 ~ 30%. acid solution;

Then, a 25 μm thick polyimide film was prepared in the same manner as in Example 1.

With respect to the polyimide films obtained in the examples and comparative examples, the properties of the obtained polyimide films were measured by the methods described below, and the results are summarized in Tables 1 and 2.

(1) Mechanical properties (tensile strength, elongation at break and elastic modulus)

Test instrument: Shimadzu EZ-LX 500N Test rate: 25mm/min Sample size: 100-150*10mm;

(2) Linear thermal expansion coefficient (CTE)

According to the thermomechanical analysis method, the thermal expansion coefficient of the polyimide film was measured using a thermomechanical analyzer (TA Instrument company, model Q400). The measurement conditions are as follows: test piece size: 8mm × 3~5mm, atmosphere: nitrogen atmosphere; temperature: heating rate 10°C/min, scanning range 50 to 300°C; tensile force: 0.05N, value range 50 to 250 °C;

(3) Glass transition temperature (Tg)

Measured using a thermomechanical analyzer (TA Instrument, model Q400). Atmosphere: under nitrogen atmosphere; temperature: heating rate 10℃/min; tensile force: 0.05N; sample size: 8mm×3~5mm;

(4) Thermogravimetric temperature (T5%)

Thermogravimetric analyzer (model TGA-55) was used to measure the thermal decomposition temperature, the heating rate was 10°C/min, the sample was 3~5mg; the temperature range was R.T.~700°C;

(5) Water absorption rate

Refer to the standard IPC-TM-650 2.6.2D for testing, the test size is 10*10cm, and 3 groups of parallel tests are carried out; soaked in deionized water at 25±2 °C for 24 hours and then wiped dry; wherein, water absorption = (weight after immersion - Weight before immersion)/weight before immersion*100%;

(6) Dk&Df

Use Keysight N5224B vector network analyzer (cavity resonator method) to test, the test frequency is 10GHz, and the sample size is 6*6cm;

3.40(@10GHz)，Df

0.005(@10GHz)；同時可實現較低的吸水率

0.7%和良好的耐熱性，其中T5%>500℃；本發明所述的透明聚醯亞胺薄膜適用於高頻柔性用電路基板材料和高頻高速用通訊材料等領域。 From the data in Table 1 and Table 2, it can be seen that compared with PDA or PMDA, the introduction of diamine or dianhydride (such as DATP, TPDA or BPDA) containing biphenyl or terphenyl structure is more conducive to the reduction of water absorption and Df. . And in order to achieve better heat resistance, dielectric properties and water absorption, it is necessary to further control the ratio of DATP and TPDA to BPDA. And after matching with different functional monomers (such as diamine and dianhydride monomers containing ether group, ester group, and F or CF ₃ and other functional structures), the heat resistance, dielectric properties or properties of the film can be further optimized. Water absorption and other characteristics. Thereby a polyimide film with low water absorption, low dielectric properties and good heat resistance is obtained, wherein Dk

3.40(@10GHz), Df

0.005(@10GHz); also can achieve lower water absorption

0.7% and good heat resistance, in which T5%>500°C; the transparent polyimide film of the present invention is suitable for high-frequency flexible circuit substrate materials and high-frequency high-speed communication materials and other fields.

Although the present invention is disclosed above with examples, it is not intended to limit the present invention. Any person skilled in the art can make any changes or equivalent replacements without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be The scope defined by the claims of this application shall prevail.

Claims (10)

A polyimide film, wherein the polyimide film comprises a repeating unit represented by the following chemical formula (1),

Wherein A ₁ represents a tetravalent residue, A ₂ is a divalent residue; A ₂ in the shown chemical formula (1) is composed of units represented by both the chemical formula (2) and the chemical formula (3):

Wherein, R ₁ and R ₂ are selected from one of H, halogen atom, halogenated alkanes containing 1 to ₃ carbon atoms; preferably one of H, F and CF , and R ₁ and R ₂ are the same or different;

Wherein, X ₁ is selected from—, -O-, -C(O)-,

,

,

and

one or more of; and R ₃ =H or CF ₃ ; In the shown chemical formula (1), A ₁ represents the structure shown in the chemical formula (4),

Wherein, X ₂ is selected from—,

,

, -C(O)-, -C(CF ₃ ) ₂ - and

one or more of; and R ₄ =H or CF ₃ . The polyimide film according to claim 1, wherein the repeating unit represented by the chemical formula (1) is obtained by polycondensation and imidization of diamine and dianhydride, wherein the unit represented by the chemical formula (2) accounts for two 10~90% of the total proportion of amine; the unit represented by chemical formula (3) accounts for 10~90% of the total proportion of diamine; The units represented by the chemical formula (2) and the chemical formula (3) account for more than 90% of the total proportion of the diamine. The polyimide film according to claim 1, wherein the unit represented by the chemical formula (4) accounts for more than 90% of the total proportion of the dianhydride; where X ₂ =─or

When , the unit represented by chemical formula (4) accounts for 35~85% of the total proportion of dianhydride. The polyimide film according to claim 1, wherein the chemical formula (2) is selected from one or more of the following structures:

. The polyimide film according to claim 1, wherein the chemical formula (3) is selected from one or more of the following structures:

. The polyimide film according to claim 1, wherein the chemical formula (4) is selected from one or more of the following structures:

. The polyimide film according to claim 1, wherein the polyimide film further contains other dianhydrides and diamines made of other dianhydrides and diamines that form the repeating unit represented by the chemical formula (1). formed repeating structural units; Said other dianhydrides other than those forming the dianhydride of formula (1) include pyromellitic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride and 3,3',4,4' -one or more in benzophenone tetracarboxylic dianhydride; The other diamines other than the diamines forming formula (1) include m-phenylenediamine, o-phenylenediamine, 4,4'-diaminodiphenylmethane, and 2,2'-dimethyl-4,4 One or more of '-diaminobiphenyl. A method for preparing a polyimide film as described in any one of claims 1 to 7, comprising the steps of: (1) Under the protection of inert gas, diamine and dianhydride are successively dissolved in an organic solvent, and the polymerization reaction obtains a polyamide acid solution with a solid content of 10-30%; (2) making a wet film on the glass substrate with the polyamic acid solution prepared in step (1); Wet film is made on it; (3) The wet film prepared in step (2) is pre-dried and then heat-treated, and further imidized to prepare a polyimide film. The polyimide film according to any one of claims 1 to 7, wherein the dielectric constant Dk of the polyimide film

3.40, the dielectric loss Df

0.005, water absorption

0.7%, T5%>500℃. A polyimide film is used for applications in the fields of high-frequency flexible circuit substrate materials and high-frequency high-speed communication materials, comprising the polyimide film described in any one of claims 1 to 7.