JP6865687B2 - Method for manufacturing polyimide film using particles with pores and polyimide film with low dielectric constant - Google Patents

Description

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 produced by the above method.

Generally, a polyimide (PI) resin is obtained by producing a polyamic acid derivative from aromatic dianhydride and aromatic diamine or aromatic diisocyanate by solution polymerization, and then imidizing it by a ring-closing dehydration reaction at a high temperature. Refers to the highly heat-resistant resin that is manufactured.

Polyimide resin is an insoluble and insoluble ultra-high heat resistant resin, and has excellent properties such as heat oxidation resistance, heat resistance, radiation resistance, low temperature characteristics, and chemical resistance, and is used for automobile materials and aviation. It is used in a wide range of fields in materials, heat-resistant advanced materials such as spacecraft materials, and electronic materials such as insulating coating agents, insulating films, semiconductors, and electrode protective films for polyimide-LCDs.

Recently, in electronic devices for accumulating a large amount of information corresponding to the highly information-oriented society, processing such information at high speed, and transferring it at high speed, the polyimide resin used for these has also been improved in performance. In particular, low dielectric constant and low dielectric loss tangent are required as electrical characteristics corresponding to high frequencies.

As an attempt to reduce the dielectric constant of the polyimide resin, for example, in Patent Document 1, a hydrophilic polymer is dispersed in a precursor of a polyimide resin that is soluble in an organic solvent, and such a hydrophilic polymer is calcined or fired. It has been proposed to obtain a porous polyimide resin by removing it by solvent extraction to make it porous. However, when the hydrophilic polymer is removed to make it porous in this way, holes are formed while maintaining the morphology of the microphase-separated structure in which the hydrophilic polymer is dispersed in the precursor of the polyimide resin. Ideally, if the hydrophilic polymer is removed as it is by firing or solvent extraction and then imidized, the holes will be flattened or closed, the porosity will be smaller than the ideal value, and the dielectric constant will be sufficiently reduced. Invites the problem of not being able to.

Patent Document 2 discloses a configuration in which fluorine particles are used in producing a flexible metal laminated plate, but the method relates to the application of a single molecule of fluorine particles, and the drawback is that the fluorine particles are difficult to disperse. There is.

Therefore, it goes without saying that the present inventors realize the electrical characteristics of air by particles having pores to realize a dielectric constant lower than that of an existing polyimide film, of course, in the manufacturing process. The present invention has been completed by developing a method for producing a polyimide film in which the dispersibility and sedimentation phenomenon of the particles having pores are improved.

Japanese Patent Publication No. 2000-044719 Republic of Korea Patent No. 1299652

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

In order to achieve the above object, the present invention
1) The stage of manufacturing the polyimide precursor and
2) A step of producing a gel film by mixing the polyimide precursor with an imidizing agent containing particles having pores.
3) Including the step of heat-treating the gel film to imidize it.
At this time, a method for producing a polyimide film, wherein the particles having pores have an average particle size of 10 μm or less and a true density of 95% or less with respect to the true density of the particle-specific substance. provide.

In order to achieve the other object, the present invention is a polyimide film containing particles having pores, and the particles having pores have an average particle size of 10 μm or less, and the true density of the particle-specific substance is adjusted. A polyimide film having a true density of 95% or less is provided.

According to the present invention, a polyimide film having a minimized dielectric constant can be produced by using particles having pores, so that it can be effectively used for an internal insulator of an electronic device, a cushioning material, a circuit board, or the like. Can be done.

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

The present invention includes 1) a step of producing a polyimide precursor, 2) a step of mixing an imidizing agent containing particles having pores in the polyimide precursor to produce a gel film, and 3) a heat treatment of the gel film. At this time, the particles having pores have an average particle size of 10 μm or less and a true density of 95% or less with respect to the true density of the particle-specific substance. Provided is a method for producing a polyimide film, which is a feature.

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

Any polyimide precursor used in the present invention can be used as long as it can be made into a polyimide resin by imidization. For example, it can be a polyamic acid obtained by copolymerizing an acid dianhydride component and a diamine component in the presence of an organic solvent by a usual method.

The acid dianhydride component and the diamine component can be appropriately selected from those usually used for preparing a polyamic acid.

Examples of the acid dianhydride component include biphenyltetracarboxylic dianhydride (BPDA) or a derivative thereof, pyromellitic dianhydride (PMDA), and 3,3'4,4'-benzophenonetetracarboxylic dianhydride. Examples thereof include p-phenylene bistrimellitic 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), 3,4'-diaminodiphenyl ether, 2, Examples thereof include, but are not limited to, 4'-diaminodiphenyl ether.

The acid dianhydride component and the diamine component can 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), N-methylpyrrolidone (NMP) and the like, but the present invention is limited thereto. It's not something.

The method for producing a polyimide film according to the present invention includes a step of producing a gel film by mixing the polyimide precursor with an imidizing agent containing particles having pores.

First, an imidizing agent is uniformly mixed with the polyimide precursor, that is, a polyamic acid, and particles having pores are uniformly dispersed and mixed therein, and then an imidized resin is produced.

The imidizing agent can be any substance commonly used to cause chemical curing. The imidizing agent can be selected from the group consisting of, for example, a dehydrating agent, a catalyst, a polar organic solvent, and a mixture thereof, and may be preferably a mixed solution of a dehydrating agent, a catalyst, and a polar organic solvent.

More specifically, the imidizing agent is a dehydrating agent such as acetic anhydride, a catalyst such as tertiary amines selected from the group consisting of pyridine, β-picoline, isoquinoline and mixtures thereof, and N-methylpyrrolidone. , Dimethylformamide, dimethylacetamide and a mixture of polar organic solvents selected from the group consisting of mixtures thereof.

The imidizing agent can be used in an amount of 30 parts by weight to 70 parts by weight, preferably 40 parts by weight to 55 parts by weight based on 100 parts by weight of the polyimide precursor, and the type of polyimide precursor and the polyimide to be produced. It may change depending on the thickness of the film.

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

Further, the particles having pores may have a true density of 95% or less, preferably 30% to 95%, more preferably 50% to 90% with respect to the true density of the particle-specific substance containing no pores. it can.

In the present invention, the "true density" means the weight per unit volume of a particle, and refers to the density of the particle itself, and the "particle-specific substance" is a substance having no pores in the particle. Means.

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

The particles having pores are particles having pores, and may be hollow type or mesoporous type particles selected from the group consisting of silica, alumina, titania, zeolite and a mixture thereof, and preferably. , Can be hollow silica.

The particles having pores can be charged as particles themselves, and it is desirable that the particles are more uniformly dispersed and mixed in the imidized resin. Therefore, the particles are charged in a dispersed liquid or colloidal form dispersed in a polar organic solvent. You can also do it.

Next, an imidizing agent is uniformly mixed with the polyamic acid, and particles having pores are uniformly dispersed and mixed therein, and then a gel film can be produced from the imidized resin.

Specifically, the imidized resin is applied to a support (for example, a stainless plate, a glass plate, an aluminum foil, a circulating stainless belt, a stainless drum, etc.), and then subjected to a primary heat treatment and dried to be chemically partially imidized. Can be produced in a stainless steel film.

The primary heat treatment process for chemical partial imidization can be carried out at 100 ° C. 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 it.

The chemically partially imidized gel film produced above can be separated from the support and subjected to a secondary heat treatment for complete imidization.

The secondary heat treatment process for complete imidization can be carried out at 250 ° C. to 850 ° C. for 5 to 25 minutes. At the time of the secondary heat treatment, it is preferable to perform the heat treatment under a constant tension because the residual stress inside the film generated in the film forming process can be removed.

According to one embodiment of the present invention, the present invention prepares an imidized resin by mixing a step of preparing a polyamic acid as a polyimide precursor and an imidizing agent in which particles having pores are uniformly dispersed with the polyamic acid. The stage of production, the stage of applying the imidized resin on the support, primary heat treatment and drying to produce a gel film, and the stage of secondary heat treatment of the gel film to produce a polyimide film. A method for producing a polyimide film, which comprises, at this time, the particles having pores have an average particle size of 10 μm or less and a true density of 95% or less with respect to the true density of the particle-specific substance. I will provide a.

On the other hand, the present invention is a polyimide film containing particles having pores, and the particles having pores have an average particle size of 10 μm or less, and the true density is 95% or less with respect to the true density of the particle-specific substance. Provided is a polyimide film having a density.

Specifically, the polyimide film containing the particles having pores is obtained from a polyimide resin synthesized from a polyamic acid and an imidizing agent containing particles having pores, and the particles having pores are average particles of 10 μm or less. It can be a polyimide film having a diameter and having a true density of 95% or less with respect to the true density of the particle-specific substance.

The polyimide film according to the present invention has a thin thickness of 5 μm to 200 μm.

Further, the polyimide film according to the present invention exhibits a dielectric constant of 3.0 or less, preferably a low dielectric constant of 2.0 to 2.9 at 1 GHz, and has a dielectric loss tangent of less than 0.002, preferably 0.0005. Since it exhibits a dielectric loss tangent of ~ 0.001, it can be effectively used for internal insulators of electronic devices, cushioning materials, circuit boards, and the like.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are merely for exemplifying the present invention, and the scope of the present invention is not limited thereto.

(Manufacturing example)
<Production Example 1: Production of polyamic acid solution>
320 g of dimethylformamide (DMF) is placed in a 0.5 L reactor, the temperature is set to 20 ° C., 27.59 g of diaminodiphenyl ether (ODA) is added and dissolved, and then 20 pyromellitic dianhydride (PMDA) is added. It was dissolved after adding .03 g twice. When the dissolution was completed, 3.97 g of para-phenylenediamine (PPDA) was added thereto and reacted for 30 minutes, and then the solution was sampled and the molecular weight was measured. After that, when the reaction was completed, the temperature of the reactor was raised to 30 ° C., and then 1.00 g of PPDA was added to adjust the molar ratio of [diamine] / [acid dianhydride] to 1: 1. When the feeding of the raw materials was completed, the mixture was sufficiently reacted at 40 ° C. for 2 hours to obtain a polyamic acid solution.

<Production Example 2: Production of an imidizing agent to which particles having pores are added (1)>
In a mixed solution of 2.8 g of β-picolin (boiling point of 144 ° C.) as a curing catalyst used as an imidizing agent, 21.2 g of acetic anhydride as a dehydrating agent, and 13.4 g of dimethylformamide (DMF) as a polar organic solvent. , 13.4 g of a dispersion of Hollow silica (Hollow silica (VHSN-1000 manufactured by Hakusan Steel Co., Ltd., average particle size of particles: 3 μm, average pores of particles: 200 nm), DMF mixture containing 6% solid content). After the addition, the mixture was stirred to obtain 50.8 g of an imidizing agent to which particles having pores were added.

<Production Example 3: Production of an imidizing agent to which particles having pores are added (2)>
Dispersion of hollow silica in a mixed solution of 2.8 g of β-picolin (boiling point of 144 ° C.) as a curing catalyst used as an imidizing agent, 21.2 g of acetic anhydride as a dehydrating agent, and 0.9 g of DMF as a polar organic solvent. After adding 26.7 g of a liquid (hollow silica (VHSN-1000 manufactured by Hakusan Steel Co., Ltd., average particle size of particles: 6 μm, average pores of particles: 200 nm) DMF mixed solution containing 6% solid content), the pores are closed. 51.6 g of an imidizing agent to which the particles having were added was obtained.

<Production Example 4: Production of an imidizing agent to which silica particles having no pores are added (1)>
Dispersion of spherical silica in a mixed solution of 2.8 g of β-picolin (boiling point 144 ° C.) as a curing catalyst used as an imidizing agent, 21.2 g of acetic anhydride as a dehydrating agent, and 13.4 g of DMF as a polar organic solvent. After adding 13.3 g of the solution (spherical silica (KEP-250 manufactured by Nippon Catalyst Co., Ltd., average particle size of particles: 3 μm, no pores), DMF mixture containing 6% solid content), the mixture was stirred to obtain spherical silica particles. 50.8 g of the added imidizing agent was obtained.

<Production Example 5: Production of an imidizing agent to which silica particles having no pores are added (2)>
A spherical silica dispersion in a mixed solution of 2.8 g of β-picolin (boiling point 144 ° C.) as a curing catalyst used as an imidizing agent, 21.2 g of acetic anhydride as a dehydrating agent, and 0.9 g of DMF as a polar organic solvent. After adding 26.7 g (spherical silica (KEP-250 manufactured by Nippon Catalyst Co., Ltd., average particle size of particles: 3 μm, no pores) DMF mixture containing 6% solid content), the mixture was stirred to add spherical silica particles. 51.6 g of the imidizing agent was obtained.

<Production Example 6: Production of an imidizing agent to which fluorine particles having no pores are added>
Polytetrafluoroethylene (PTFE) is added to a mixed solution of 2.8 g of isoquinolin (boiling point 242 ° C.) as a curing catalyst used as an imidizing agent, 21.2 g of anhydrous acetic acid as a dehydrating agent, and 0.9 g of DMF as a polar organic solvent. ) (26.7 g) (manufactured by Daikin Industries, Ltd., DMF mixture containing fluorine particles (average particle size 22 μm, no pores) solid content 6%) was added and then stirred to add the fluorine particles to the imide. 51.6 g of the agent was obtained.

<Production Example 7: Production of imidizing agent without adding particles>
3.3 g of β-picoline (boiling point 144 ° C.) used as an imidizing agent, 21.5 g of acetic anhydride as a dehydrating agent, and 25.2 g of DMF as a polar organic solvent are mixed and stirred to imidize. 50 g of the agent was obtained.

(Example)
<Example 1: Production of particle-applied polyimide film having pores (1)>
After mixing 50.8 g of the imidizing agent obtained in Production Example 2 with 100 g of the polyamic acid solution obtained in Production Example 1, the mixture was applied to a stainless steel plate and dried in an oven at 120 ° C. for 3 minutes with hot air. A gel film was produced.

The gel film thus produced was removed from the stainless steel plate and fixed with a frame pin, and the frame to which the gel film was fixed was heat-treated at 450 ° C. for 7 minutes, and then the film was peeled off to obtain a polyimide film having an average thickness of 25 μm. Obtained.

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

<Example 2: Production of particle-applied polyimide film having pores (2)>
The same steps as in Example 1 were carried out except that 51.6 g of the imidizing agent obtained in Production Example 3 was used instead of the imidizing agent obtained in Production Example 2, and the average thickness was obtained. A 25 μm polyimide film was obtained.

<Comparative Example 1: Production of Particle-Applied Polyimide Film without Pore (1)>
The same steps as in Example 1 were carried out except that 50.8 g of the imidizing agent obtained in Production Example 4 was used instead of the imidizing agent obtained in Production Example 2, and the average thickness was obtained. A 25 μm polyimide film was obtained.

<Comparative Example 2: Production of Particle-Applied Polyimide Film without Pore (2)>
The same steps as in Example 1 were carried out except that 51.6 g of the imidizing agent obtained in Production Example 5 was used instead of the imidizing agent obtained in Production Example 2, and the average thickness was obtained. A 25 μm polyimide film was obtained.

<Comparative Example 3: Production of Fluorine Particle Applicable Polyimide Film without Pore>
The same steps as in Example 1 were carried out except that 51.6 g of the imidizing agent obtained in Production Example 6 was used instead of the imidizing agent obtained in Production Example 2, and the average thickness was obtained. A 25 μm polyimide film was obtained.

<Comparative Example 4: Manufacture of Polyimide Film without Adding Particles>
The same steps as in Example 1 were carried out except that 50.0 g of the imidizing agent obtained in Production Example 7 was used instead of the imidizing agent obtained in Production Example 2, and the average thickness was obtained. A 25 μm polyimide film was obtained.

<Test Example 1: Measurement of true density ratio>
In the present invention, the true densities of the particles (A) added during the production of the polyimide film and these particle-specific substances (B) were measured according to the standard (KS M 6020: 2010). At this time, the hollow silica used in Examples 1 and 2 and the natural silica which is an intrinsic substance of the spherical silica used in Comparative Examples 1 and 2 were obtained from Nippon Catalyst Co., Ltd. (model name: KEP-250). It was measured using the purchased one.

Next, the true density ratio (%) of the particles having pores to the particle-specific substance was calculated based on the following formula 1, and the results are shown in Table 1 below.
[Calculation formula 1]

<Test Example 2: Measurement of average particle size of particles having pores>
The average particle size of the particles having pores used in the present invention was measured using a laser diffraction particle size analyzer (Laser Diffraction Particle Size Analyzer, Shimadzu Corporation, model name: SALD-2201), and the pores were measured. The values of the average particle size of the particles having the above are shown in Table 1 below.

<Test Example 3: Measurement of film particle content>
The particle content of the polyimide films produced in Examples 1 and 2 and Comparative Examples 1 to 4 was measured by the ASH method. The ASH method is a method in which a film is placed in a crucible, incinerated at 900 ° C. for 3 hours, and then the weight of the remaining amount remaining in the crucible is measured to measure the content rate. The measured particle content (% by weight) is shown in Table 1 below.

<Test Example 4: Confirmation of average distribution of particles with pores in the film>
The distribution state of particles having pores in the polyimide film according to Example 1 of the present invention was observed with a scanning electron microscope FE-SEM (manufactured by JEOL (JEOL Ltd., model name: JSM-6700F)) and SEM. Shown in the image.

An SEM photograph of a cross section of the polyimide film according to Example 1 of the present invention is shown in FIG. Further, FIG. 2 shows a photograph of particles having pores dispersed on the surface of the film, and FIG. 3 shows a photograph of the partially enlarged particles.

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

<Test Example 5: Measurement of permittivity and dielectric loss tangent>
The dielectric constant and dielectric loss tangent at 1 GHz of the polyimide films produced in Examples 1 and 2 and Comparative Examples 1 to 4 were measured using a Keysight Technologies split-post dielectric resonator (SPDR). The measured permittivity and dielectric loss tangent values are shown in Table 1 below.

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

Further, the polyimide films according to Examples 1 and 2 have a dielectric constant and dielectric loss tangent even when compared with Comparative Examples 1 to 4 having a true density ratio of more than 95%, containing fluorine particles, or containing no particles at all. Appeared low, and it was found that the electrical characteristics were excellent.

The polyimide film of the present invention can be effectively used in the manufacture of electrical / electronic devices and parts such as printed circuit boards that require a low dielectric constant.

Claims (3)

1) The stage of manufacturing the polyimide precursor and
2) A step of producing a gel film by mixing the polyimide precursor with an imidizing agent containing particles having pores.
3) Including a step of heat-treating the gel film to imidize the gel film.
The particles having pores are hollow silica particles, and the particles have pores.
Particles with the pores have an average particle size of 1 m to 10 m,
The true density of the pore-bearing particles is 50% to 90% of the true density of the pore-free particle-specific material.
A method for producing a polyimide film, wherein the particles having pores are contained in an amount of 2% by weight to 30% by weight based on the total weight of the film. A polyimide film containing particles with pores,
The particles having pores are hollow silica particles, and the particles have pores.
Particles with the pores have an average particle size of 1 m to 10 m,
The true density of the pore-bearing particles is 50% to 90% of the true density of the pore-free particle-specific material.
A polyimide film in which the particles having pores are contained in an amount of 2% by weight to 30% by weight based on the total weight of the film. The polyimide film according to claim 2 , wherein the polyimide film exhibits a dielectric constant of 3.0 or less at 1 GHz.

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