KR101728100B1 - Method for preparation of polyimide film using porous particles and polyimide film having low permittivity - Google Patents

Abstract

The present invention relates to a method of producing a polyimide film using particles having pores and a low dielectric constant polyimide film produced by the method, wherein the polyimide film according to the present invention has an average particle size of 10 탆 or less , And particles having pores having a true density of less than 95% of the true density of the particle specific material can be exhibited, so that the dielectric constant can be lower than that of the conventional polyimide film. Therefore, electric / electronic And can be usefully used for manufacturing apparatus and parts.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for producing a polyimide film using particles having pores and a polyimide film having a low dielectric constant,

The present invention relates to a method of producing a polyimide film using particles having pores and a low dielectric constant polyimide film produced by the method.

In general, polyimide (PI) resin refers to a high heat resistant resin prepared by solution polymerization of an aromatic dianhydride and an aromatic dianhydride or an aromatic diisocyanate to prepare a polyamic acid derivative, followed by ring-closing dehydration at a high temperature and imidization.

Polyimide resin is an insoluble and infusible ultra-high temperature resistant resin. It has excellent heat resistant oxidizing property, heat resistance property, radiation resistance property, low temperature property and chemical resistance. It is a high heat resistant material such as automobile material, Coating materials, insulating films, semiconductors, and electrode protective films for TFT-LCDs.

In recent years, in an electronic apparatus for accumulating a large amount of information corresponding to a highly information-oriented society and processing such information at a high speed and delivering it at a high speed, it has been desired to provide a polyimide resin, A low dielectric constant and a low dielectric constant tangent are required as electrical characteristics.

As an attempt to lower the dielectric constant of the polyimide resin, for example, Japanese Patent Application Laid-Open No. 2000-44719 discloses a method of dispersing a hydrophilic polymer in a polyimide resin precursor soluble in an organic solvent and then subjecting the hydrophilic polymer to firing or solvent extraction To thereby obtain a porous polyimide resin. However, when the hydrophilic polymer is removed and thus made porous, it is ideal that the microphase separation structure in which the hydrophilic polymer is dispersed in the polyimide resin precursor is maintained as it is and the pores are formed. However, The hole is flattened or clogged, and the porosity becomes smaller than the ideal value, so that the dielectric constant can not be sufficiently lowered.

Korean Patent No. 1299652 discloses a construction using fluorine particles in the production of a flexible metal laminate, but the method is based on the application of monomolecular fluorine particles, and the fluorine particles are not well dispersed.

Accordingly, the present inventors have realized that the electrical properties of air can be realized through particles having pores, thereby realizing a dielectric constant lower than the dielectric constant of existing polyimide films, and in addition, dispersibility and sinking of particles having pores in the manufacturing process The present inventors have completed the present invention by developing a method for producing a polyimide film with improved development.

[Patent Document 1] JP-A-2000-44719

[Patent Document 2] Korean Patent No. 1299652

Accordingly, it is an object of the present invention to provide a method for producing a polyimide film using particles having pores and a polyimide film having a low dielectric constant produced according to the method.

In order to achieve the above object,

1) preparing a polyimide precursor;

2) mixing a polyimide precursor with an imidization conversion liquid containing particles having pores to prepare a gel film; And

3) heat treating the gel film to imidize the gel film,

Wherein the particles having pores have an average particle diameter of 10 mu m or less and a true density of 95% or less of a particle density of the particle specific material.

In order to achieve the above other objects, the present invention provides a polyimide film comprising particles having pores, wherein the particles having pores have an average particle diameter of 10 mu m or less and a pore diameter of 95% or less Density polyimide film.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to produce a polyimide film having a minimum permittivity by using particles having pores, and therefore can be usefully used for an inner insulator, a buffer material, a circuit board, and the like for electronic devices.

1 is a scanning electron microscope (SEM) photograph of a section of a polyimide film according to the present invention.
FIG. 2 is a SEM photograph showing a state in which particles having pores are dispersed on the surface of the polyimide film according to the present invention, and FIG. 3 is a SEM photograph showing the state of the particle partially enlarged.

The present invention provides a method for producing a polyimide precursor, comprising: 1) preparing a polyimide precursor; 2) mixing a polyimide precursor with an imidization conversion liquid containing particles having pores to prepare a gel film; And 3) heat treating the gel film to imidize the particles. The pore-forming particles have an average particle diameter of 10 m or less and a true density of 95% or less of the true density of the particle-specific substance By weight based on the total weight of the polyimide film.

The method for producing a polyimide film according to the present invention includes a step of producing a polyimide precursor.

The polyimide precursor used in the present invention may be any polyimide resin that can be made into a polyimide resin by imidization. For example, a polyamic acid obtained by copolymerizing an acid dianhydride component and a diamine component in the presence of an organic solvent according to a conventional method.

The acid dianhydride component and the diamine component may be appropriately selected from those conventionally used in the production of polyamic acid.

Examples of the acid dianhydride component include biphenyltetracarboxylic dianhydride or derivative thereof, pyromellitic dianhydride (PMDA), 3,3'4,4'-benzophenonetetracarboxylic acid anhydride, p -Phenylene-bistrimellitic acid dianhydride, and the like, but the present invention is not limited thereto.

Examples of the diamine component include para-phenylenediamine (pPDA), diaminophenyl ether, o-phenylenediamine, m-phenylenediamine, 4,4-diaminodiphenyl ether (ODA) 4-diaminodiphenyl ether, and 2,4-diaminodiphenyl ether. However, the present invention is not limited thereto.

The acid dihydrate component and the diamine component may be mixed in a molar ratio of 1: 0.9 to 1: 1.1.

Examples of the organic solvent include N, N'-dimethylformamide (DMF), N, N'-dimethylacetamide (DMAc) and N-methyl-pyrrolidone (NMP) But is not limited thereto.

The method for producing a polyimide film according to the present invention includes a step of mixing a polyimide precursor with an imidization conversion liquid containing particles having pores to prepare a gel film.

First, an imidization conversion liquid is uniformly mixed with the polyimide precursor, that is, polyamic acid, and particles having pores therein are uniformly dispersed and mixed to prepare an imidized resin.

The imidization conversion liquid may be any material conventionally used to cause chemical hardening. The imidization conversion liquid may be selected from the group consisting of, for example, a dehydrating agent, a catalyst, a polar organic solvent, and a mixture thereof, preferably a mixed solution of a dehydrating agent, a catalyst and a polar organic solvent.

More specifically, the imidization conversion liquid may be a dehydrating agent such as acetic anhydride or the like; Tertiary amines selected from the group consisting of pyridine, beta picoline, isoquinoline, and mixtures thereof; And a polar organic solvent selected from the group consisting of N-methylpyrrolidone, dimethylformamide, dimethylacetamide, and mixtures thereof.

The imidization conversion liquid may be used in an amount of 30 to 70 parts by weight, preferably 40 to 55 parts by weight, based on 100 parts by weight of the polyimide precursor, and may vary depending on the kind of the polyimide precursor and the thickness of the polyimide film to be produced .

The particles having pores may have an average particle diameter of 10 mu m or less, preferably 1 to 10 mu m, 1 to 7 mu m, or 2 to 5 mu m.

The particles having pores have a true density of 95% or less, preferably 30% to 95%, more preferably 50 to 90%, as compared with the true density of the particle-specific material not containing pores .

In the present invention, "true density " means the weight per unit volume of a particle, which means density of the particle itself, and" particle specific material "

The particles having pores may be contained in an amount of 2 to 30% by weight, preferably 5 to 20% by weight, for example, 5 to 10% by weight, based on the total weight of the film. If the content of the particles having pores is 30 wt% or less, the mechanical properties of the polyimide film are not deteriorated, and if the content is 2 wt% or more, a low dielectric constant effect of the polyimide film can be realized.

The particles having pores may be hollow particles or mesoporous particles selected from the group consisting of silica, alumina, titania, zeolite, and mixtures thereof, and preferably hollow silica particles have.

The particles having pores can be introduced into the particles themselves and are preferably dispersed and mixed more uniformly in the imidized resin, so that they may be put into a dispersion state or a colloid state dispersed in a polar organic solvent.

Then, the imidization conversion liquid can be uniformly mixed with the polyamic acid, and the particles having pores can be uniformly dispersed and mixed therein, and the imidized resin can be made into a gel film.

Specifically, the imidized resin may be applied to a support (for example, a stainless steel plate, a glass plate, an aluminum foil, a circulating stainless belt, a stainless steel drum, or the like), and then subjected to a first heat treatment and drying to form a chemically partially imaged gel film have.

The first heat treatment for chemically partially imidizing may be performed at 100 to 200 ° C for 5 to 15 minutes.

The method for producing a polyimide film according to the present invention includes a step of heat-treating the gel film to imidize the gel film.

The chemically partially imidized gel film prepared above may be subjected to a secondary heat treatment for complete imidization, separated from the support.

The second heat treatment process for the complete imidization may be performed at 250 to 850 캜 for 5 to 25 minutes. In the secondary heat treatment, heat treatment under a certain tension is preferable because the residual stress in the film generated during the film-forming process can be removed.

According to one embodiment of the present invention, the present invention provides a method for manufacturing a polyimide precursor, comprising: preparing a polyamic acid as a polyimide precursor; Mixing the polyamic acid with an imidization conversion liquid in which particles having pores are uniformly dispersed to prepare an imidized resin; Coating the imidized resin on a support, subjecting the imidized resin to a primary heat treatment and drying to prepare a gel film; And subjecting the gel film to a second heat treatment to produce a polyimide film, wherein the particles having pores have an average particle diameter of 10 mu m or less and a true density of less than 95% A polyimide film, and a polyimide film.

On the other hand, the present invention is a polyimide film comprising particles having pores, wherein the particles having pores have an average particle diameter of 10 mu m or less and a true density of 95% or less of the true density of the particle- Film.

Specifically, the polyimide film containing the particles having pores is obtained from a polyimidized resin synthesized from an imidization conversion liquid containing polyamic acid and particles having pores, and the particles having pores have an average particle diameter 10 탆 or less, and a true density of 95% or less of the true density of the particle specific material.

The polyimide film according to the present invention exhibits a thin thickness of 5 to 200 mu m.

The polyimide film according to the present invention exhibits a dielectric constant of 3.0 or less, preferably 2.0 to 2.9 at 1 GHz, and a dielectric loss tangent of less than 0.002, preferably 0.0005 to 0.001, Internal insulators, cushioning materials, circuit boards, and the like.

[Example]

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

Production Example 1: Preparation of polyamic acid solution

320 g of dimethylformamide (DMF) was placed in a 0.5 L reactor and the temperature was adjusted to 20 ° C. Then, 27.59 g of diaminophenyl ether (ODA) was added to dissolve and then 20.03 g of pyromellitic dianhydride (PMDA) And then dissolved. After the dissolution, 3.97 g of para-phenylenediamine (pPDA) was added thereto and reacted for 30 minutes. The solution was sampled to measure the molecular weight. After the reaction was completed, the temperature of the reactor was raised to 30 ° C, and 1.00 g of pPDA was added to adjust the molar ratio of [diamine] / [dianhydride] to 1: 1. After the addition of the raw material was completed, the reaction was sufficiently carried out at 40 ° C for 2 hours to obtain a polyamic acid solution.

Production Example 2: Preparation of imidization conversion liquid added with particles having pores (1)

To a mixed solution of 2.8 g of beta-picoline (boiling point 144 DEG C), 21.2 g of acetic anhydride as a dehydrating agent and 13.4 g of dimethylformamide (DMF) as a polar organic solvent as a curing catalyst used in the imidization conversion liquid, (DMF mixed solution containing hollow silica (VHSN-1000, average particle diameter of particles: 3 μm, average pore size of particles: 200 nm) and solid content of 6%) was added and stirred to obtain particles having pores 50.8 g of the imidized conversion solution was obtained.

Production Example 3: Preparation of imidization conversion liquid added with pore-forming particles (2)

To a mixed solution of 2.8 g of beta-picoline (boiling point 144 DEG C) as a curing catalyst used in the imidation conversion liquid, 21.2 g of acetic anhydride as a dehydrating agent and 0.9 g of DMF as a polar organic solvent, 26.7 g of hollow silica dispersion (DMF mixed solution containing 6% solid content of silica) (silica white steel VHSN-1000, average particle diameter of particles: 6 탆, average particle size of particles: 200 nm) was added and stirred to obtain 51.6 g of an imidization conversion liquid added with particles having pores .

Preparation Example 4: Preparation of an imidization conversion liquid added with silica particles having no pores (1)

To a mixed solution of 2.8 g of beta-picoline (boiling point 144 DEG C) as a curing catalyst used in the imidation conversion solution, 21.2 g of acetic anhydride as a dehydrating agent and 13.4 g of DMF as a polar organic solvent, 13.3 g of a dispersion of spherical silica DMF mixed solution containing silica (Nippon Catalyst KEP-250, average particle diameter of particles: 3 mu m, porosity: 6%) was added and stirred to obtain 50.8 g of an imidation conversion liquid to which spherical silica particles were added.

Preparation Example 5: Preparation of imidization conversion liquid added with silica particles having no pores (2)

To a mixed solution of 2.8 g of beta-picoline (boiling point 144 DEG C) as a curing catalyst used in the imidization conversion solution, 21.2 g of acetic anhydride as a dehydrating agent and 0.9 g of DMF as a polar organic solvent, 26.7 g of a spherical silica dispersion (DMF mixed solution containing 6% solid content of particles of the catalyst KEP-250 (average particle diameter of the particles: 3 탆, no pores)) was added and stirred to obtain 51.6 g of an imidization conversion liquid to which spherical silica particles were added.

Preparation Example 6: Preparation of imidization conversion liquid added with fluorine particles having no pores

(PTFE) was added to a mixed solution of 2.8 g of isoquinoline (boiling point 242 占 폚) as a curing catalyst used in the imidization conversion solution, 21.2 g of acetic anhydride as a dehydrating agent, and 0.9 g of DMF as a polar organic solvent 26.7 g of a dispersion (DMF mixed liquid containing 6% of fluorine particles (average particle diameter of 22 탆, porosity) solid content, manufactured by DAIKIN) was added and stirred to obtain 51.6 g of an imidization conversion liquid to which fluorine particles were added.

Production Example 7: Preparation of imidization conversion liquid without adding particles

3.3 g of betapicholine (boiling point 144 캜) as a curing catalyst used in the imidization conversion solution, 21.5 g of acetic anhydride as a dehydrating agent, and 25.2 g of DMF as a polar organic solvent were mixed and stirred to obtain 50 g of an imidization conversion liquid.

Example  1: Preparation of porous polyimide film with pores (1)

50.8 g of the imidization conversion solution obtained in Preparation Example 2 was mixed with 100 g of the polyamic acid polymer solution obtained in Preparation Example 1, and the resulting mixture was coated on a stainless steel plate and dried in a 120 ° C oven for 3 minutes with hot air to prepare a gel film.

The thus-prepared gel film was peeled off from the stainless plate and fixed with a frame pin. After the frame having the gel film fixed thereon was heat-treated at 450 캜 for 7 minutes, the film was peeled off to obtain a polyimide film having an average thickness of 25 탆.

A scanning electron microscope (SEM) photograph of the section of the polyimide film thus produced is shown in Fig.

Example  2: Preparation of porous polyimide film with pores (2)

Except that 51.6 g of the imidization conversion liquid obtained in Production Example 3 was used in place of the imidization conversion liquid obtained in Production Example 2 to obtain a polyimide film having an average thickness of 25 탆.

Comparative Example 1: Preparation of polyimide film-coated particles having no pores (1)

Except that 50.8 g of the imidization conversion liquid obtained in Production Example 4 was used in place of the imidization conversion liquid obtained in Production Example 2 to obtain a polyimide film having an average thickness of 25 m.

Comparative Example 2: Production of polyimide film-coated particles having no pores (2)

Except that 51.6 g of the imidization conversion solution obtained in Production Example 5 was used instead of the imidization conversion solution obtained in Production Example 2 to obtain a polyimide film having an average thickness of 25 탆.

Comparative Example  3: Manufacture of polyimide film with fluorine particles without porosity

Except that 51.6 g of the imidization conversion solution obtained in Production Example 6 was used in place of the imidization conversion solution obtained in Production Example 2 to obtain a polyimide film having an average thickness of 25 탆.

Comparative Example 4: Production of polyimide film without added particles

A polyimide film having an average thickness of 25 탆 was obtained by carrying out the same processes as in Example 1 except that 50.0 g of the imidization conversion solution obtained in Production Example 7 was used in place of the imidization conversion solution obtained in Production Example 2.

Test Example 1: Measurement of density ratio

In the present invention, the true density of the particles (A) added to the polyimide film during the production of the polyimide film and the intrinsic material (B) thereof were measured according to the respective standards (KS M 6020: 2010). At this time, the hollow silica used in Examples 1 and 2 and the natural silica, which is the intrinsic material of the spherical silica used in Comparative Examples 1 and 2, were measured using a product purchased from Japan Catalyst (Model: KEP-250).

Then, the true density ratio (%) of the particles having pores with respect to the particle specific substance was calculated according to the following equation 1, and the results are shown in Table 1 below.

[Equation 1]

Test Example 2: Measurement of average particle diameter of particles having pores

The average particle diameter of the pores having pores used in the present invention was measured using a laser diffraction particle size analyzer (SHIMADZU, model name: SALD-2201) Respectively.

Test Example 3: Measurement of particle content of film

The particle contents of the polyimide films prepared in Examples 1 and 2 and Comparative Examples 1 to 4 were measured by the ASH method. The ASH method was carried out by placing the film in a crucible and burning it at 900 ° C for 3 hours, measuring the weight of the remaining amount in the crucible, and measuring the content. The measured particle content (% by weight) is shown in Table 1 below.

Test Example 4: Average distribution of particles having pores in the film

The state of the particles having pores in the polyimide film according to Example 1 of the present invention was observed with a scanning electron microscope FE-SEM (JEOL, model name JSM-6700F), and it was shown by SEM image.

A scanning electron microscope (SEM) photograph of a cross section of a polyimide film according to Example 1 of the present invention is shown in Fig.

FIG. 2 shows a state in which particles having pores are dispersed on the surface of the film, and FIG. 3 shows a photograph showing the state of particles by enlarging the particles.

As shown in FIG. 2, it was found that the particles having pores used in the polyimide film according to the present invention were uniformly distributed throughout the film, and thus it was found that they exhibited a good dispersion state.

Test Example 5: Measurement of dielectric constant and dielectric tangent

The dielectric constant and dielectric loss tangent of the polyimide films prepared in Examples 1 and 2 and Comparative Examples 1 to 4 at 1 GHz were measured using an SPDR meter of Keysight. The measured dielectric constant and dielectric loss tangent are shown in Table 1 below.

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Polyamic acid solution Production Example 1 Imidization conversion amount Production Example 2 Production Example 3 Production Example 4 Production Example 5 Production Example 6 Production Example 7 Particle type Hollow silica Hollow silica Spherical silica Spherical silica Fluorine particle - Unique substance Silica Silica Silica Silica PTFE Particle content (% by weight) 5.0 9.6 5.0 9.6 9.6 Average particle diameter of the particles 3 ㎛ 3 ㎛ 3 ㎛ 3 ㎛ 22 탆 - Density ratio (%) 88.4 88.4 100 100 100 - Dielectric constant (1 GHz) 2.89 2.51 3.42 3.51 3.41 3.39 Dielectric tangent (1 GHz) 0.001 0.001 0.002 0.002 0.002 0.003 Film average thickness (탆) 25 25 25 25 25 25

As shown in Table 1, the polyimide films according to Examples 1 and 2 including hollow silica particles having pores showed a low dielectric constant of 3 or less.

In addition, the polyimide films according to Examples 1 and 2 had lower dielectric constant and dielectric loss tangent than those of Comparative Examples 1 to 4 in which the density ratio exceeded 95%, the fluorine particles were contained, or the particles were not contained at all And the electrical characteristics were excellent. Therefore, it can be usefully used for manufacturing electric / electronic devices and parts such as a printed circuit board in which a low dielectric constant is required.

Claims (6)

1) preparing a polyimide precursor;
2) mixing a polyimide precursor with an imidization conversion solution containing particles having pores to prepare a gel film; And
3) heat-treating the gel film to imidize the polyimide film,
Wherein the pore-forming particles are hollow silica particles having an average particle diameter of 10 m or less and have a true density of 50 to 90% of a particle density of the particle-specific material, and the polyimide film has a density of 3.0 Wherein the polyimide film exhibits the following dielectric constant.
The method according to claim 1,
Wherein the particles having pores have an average particle diameter of 1 to 10 mu m.
The method according to claim 1,
Wherein the particles having the pores are contained in an amount of 2 to 30% by weight based on the total weight of the film.
The method according to claim 1,
Wherein the particles having pores are contained in an amount of 5 to 30% by weight based on the total weight of the film.
A polyimide film comprising particles having pores,
Wherein the particles having pores are hollow silica particles having an average particle diameter of 10 탆 or less and have a true density of 50 to 90%
Wherein the polyimide film exhibits a dielectric constant of 3.0 or less at 1 GHz.
6. The method of claim 5,
And the particles having the pores are contained in an amount of 9.6 to 30 wt% based on the total weight of the film.

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