KR20130113778A - Black polyimide film - Google Patents

Abstract

PURPOSE: A black polyimide film has excellent light-shielding performance and electric insulation and has excellent mechanical properties. CONSTITUTION: A black polyimide film is a polyimide film which is obtained by imidizing a polyamic acid obtained from diamines and dianhydrides. The black polyimide film comprises 3.0-7.5 wt% of carbon black which has 1.5 wt% or less of a high temperature volatile component and the surface of which is not oxidation-treated; and 0.5-1.5 wt% of a shielding agent. The visibly ray transmittance of the black polyimide film is 1.0% or less, the glossiness is 60% or less, the elongation is 80% or less, the surface resistance is 10^15 Ω greater, and the pinhole generation is 1 or less.

Description

Black polyimide film {BLACK POLYIMIDE FILM}

The present invention relates to a black polyimide film used for shielding.

In general, the polyimide (PI) resin refers to a high heat-resistant resin prepared by solution polymerization of an aromatic dianhydride and an aromatic diamine or an aromatic diisocyanate to prepare a polyamic acid derivative, and then imidization by cyclization of the ring at a high temperature. In order to prepare a polyimide resin, pyromellitic dianhydride (PMDA) or biphenyltetracarboxylic dianhydride (BPDA) or the like is used as an aromatic dianhydride component, and oxydianiline (ODA), p is used as an aromatic diamine component. -Phenylene diamine (p-PDA), m-phenylene diamine (m-PDA), methylenedianiline (MDA), bisaminophenylhexafluoropropane (HFDA) and the like are used.

Polyimide resin is an insoluble and non-fusible ultra-high temperature resistant resin. It has excellent heat resistant oxidizing property, heat resistance property, radiation resistance property, low temperature property, chemical resistance and so on. It is a high heat resistant material such as automobile material, , Insulating films, semiconductors, and electrode protective films for TFT-LCDs.

In particular, in recent years, as a coverlay (coverlay) is widely used in portable electronic devices and communication devices, interest in shielding polyimide film having a light shielding function and an insulating function and excellent mechanical properties for security purposes and visual effects. It is rising.

An object of the present invention is to provide a black polyimide film for shielding excellent in light shielding function and electrical insulation function, excellent mechanical properties and a method of manufacturing the same.

Accordingly, the present invention is a polyimide film obtained by imidizing a polyamic acid obtained from dianhydride and diamines as a first preferred embodiment,

(A) less than or equal to 1.5% by weight of high temperature volatile components, and 3.0 to 7.5% by weight of carbon black, which is not subjected to surface oxidation, and (B) 0.5 to 1.5% by weight of a shielding agent,

Black having a light transmittance of 1.0% or less, a glossiness of 60% or less, an elongation of 80% or more, a surface resistance of 10 ¹⁵ Ω or more, and a pinhole generation rate (piece / 100 m 2) of 1 or less It provides a polyimide film.

Carbon black according to the embodiment has a volume average particle diameter of 2 ㎛ or less, the maximum particle size may be 10 ㎛ or less, the primary particle size may be 70 to 150 nm.

The shielding agent according to the embodiment may have a volume average particle diameter of 0.1 to 1.0 μm.

Shielding agent according to the embodiment TiO ₂ Lt; / RTI >

Diamines according to the embodiment may be phenylenediamine, diaminodiphenyl ether or derivatives thereof.

The black polyimide film of the present invention has an excellent light shielding function and an electric insulation function, and has an effect that can be usefully used as a black polyimide film for shielding due to its excellent mechanical properties.

The present invention relates to a polyimide film obtained by imidizing a polyamic acid obtained from an dianhydride and diamines, the carbon comprising (A) 1.5% by weight or less of a high-temperature volatile component based on the total weight of the film and not subjected to surface oxidation treatment. Black 3.0 to 7.5% by weight and (B) 0.5 to 1.5% by weight of the shielding agent, the light transmittance in the visible region is 1.0% or less, glossiness is 60% or less, elongation is 80% or more, surface resistance is 10 ¹⁵ It is ohms or more, and it is related with the black polyimide film characterized by the pinhole generation rate (piece / 100m <2>) being 1 or less.

The black polyimide film of the present invention has a light transmittance of 1.0% or less, preferably 0.1 to 1.0%, and glossiness of 60% or less, preferably 40 to 60% in order to provide a light shielding function. It features. This enhances aesthetics in the appearance of the applied product and ensures security by blocking the inside shape.

In addition, the black polyimide film of the present invention is characterized by having a surface resistance of 10 ¹⁵ Ω or more in order to provide an electrical insulation function as a coverlay, and the higher the surface resistance is, the more preferable. Since the black polyimide surface resistance satisfies 10 ¹⁵ Ω or more, it is possible to improve the electrical stability of the product as a coverlay which is mainly used as a protective film of a flexible circuit. In this regard, the black polyimide film of the present invention preferably has an insulation breakdown voltage of 80 kV / mm or more, preferably 90 kV / mm or more.

In addition, the black polyimide film of the present invention has an elongation of 80% or more, preferably 80 to 110%, in order to provide the above-described light shielding function and electrical insulation function, and to secure mechanical properties, and a pinhole generation rate (piece / 100 m 2). ) Is less than or equal to 1, the process stability during production and processing of the product can be improved and the mechanical reliability of the final product can be improved.

In order to achieve the properties of the black polyimide film as described above, the black polyimide film has a high temperature volatile content of 1.5% or less and is not subjected to surface oxidation 3.0 to 7.5% by weight, preferably 5.0 to 7.0 It is characterized in that it comprises a weight percent and 0.5 to 1.5% by weight, preferably 0.7 to 1.3% by weight, more preferably 0.8 to 1.2% by weight.

The carbon black may be one that is not surface-oxidized to increase stability during heat treatment, and a high temperature volatile component is preferably low, and the content of the high temperature volatile component is 1.5 wt% or less based on the total weight of the carbon black. Preferably from 0.8 to 1.5% by weight.

The carbon black is used to impart black color and glossiness of the black polyimide film, and the content thereof may be 3.0 to 8.0 wt% based on the total weight of the black polyimide film. When the content of the carbon black is less than 3.0 wt%, it is difficult to realize the black color in the thin film, and when the content of the carbon black exceeds 7.5 wt%, the shading function and the implementation of the black color may be improved, but the insulation and corona resistance may be reduced. There may be a problem.

The carbon black may have a volume average particle diameter of 2 μm or less, preferably 0.5 to 2 μm, more preferably 0.6 to 1.6 μm, and when the carbon black is dispersed in a solvent or the like, the maximum particle diameter of the particle may be 10 μm or less. . In addition, the particle diameter of the primary particles of carbon black may be 70 nm or more, preferably 70 to 150 nm. When the primary particle size of the carbon black is less than 70 nm, the glossiness of the black polyimide film is increased, and thus it is difficult to impart matting properties to the film. Therefore, the black polyimide film of the present invention can provide matting properties to the film by including carbon black in the above size range, and can realize uniform color and physical properties.

In addition, the carbon black has a particle size dispersion (= volume average particle diameter / number average particle diameter) of 5 or less, or more preferably 3 or less, it is preferable that the carbon black particles having a low particle size dispersion when the particle size uniformity is high, the resin The uniform dispersion is made in the interior of, can be mixed evenly when mixed with the resin. Accordingly, degradation of mechanical properties of the film can be minimized, and uniformity of overall physical properties, that is, minimization of color deviation for each position can be achieved, and in particular, the elongation of the film can be greatly improved. In addition, the particle size dispersion of the carbon black can be improved through milling and dispersant application. At this time, the milling treatment is preferably milled for both the carbon black and the shielding agent, thereby improving the particle dispersity of both the carbon black and the shielding agent.

The shielding agent is used for running, heat dissipation, and shielding properties of the black polyimide film, and the content of the shielding agent may be 0.5 to 1.5 wt% based on the total weight of the black polyimide film. When the content of the shielding agent is less than 0.5% by weight, the shielding rate is lowered. When the content of the shielding agent is more than 1.5% by weight, the mechanical properties of the film, in particular, the elongation is lowered, the pinhole generation rate is increased during film production, and the yield of the product is lowered and the appearance quality is lowered. There is a problem.

Examples of the shielding agent include titanium dioxide (TiO ₂ ), nitride particles, and other inorganic particles.

The shielding agent according to the embodiment may be in the form of particles, the shielding agent may have a volume average particle diameter of 0.1 to 1.0 ㎛, preferably 0.15 to 0.7 ㎛, more preferably 0.2 to 0.6 ㎛. In particular, when the volume average particle diameter of the shielding agent particles is 0.1 to 1.0 μm, it is possible to prevent a decrease in the mechanical properties of the film while improving the shielding rate.

In general, the method for producing the black polyimide film of the present invention may be a film forming method of a polyimide film, but in particular, polymerizing the polyamic acid solution from dianhydrides and diamines and forming the polyamic acid solution In the process of producing a black polyimide film, the polyamic acid solution, the carbon black, the shielding agent and the catalyst are mixed and formed into a film in the film forming step, so that the polyamic acid solution, the carbon black, the shielding agent and the catalyst are mixed more uniformly. The film forming method can be used. The black polyimide film thus prepared may have uniform mechanical, optical and electrical properties.

At this time, the mixing in the film forming step may be mixed by using a line mixer, by mixing each of the polyamic acid solution, carbon black, shielding agent and catalyst into the line mixer, which may occur by simultaneous input to one inlet The aggregation phenomenon can be prevented and mixed more uniformly. On the other hand, when the carbon black and the shielding agent is mixed in the step of polymerizing the polyamic acid solution, the mixing ability of the large-capacity agitator used in the polymerization process is relatively low, there is a problem that it is difficult to achieve uniform physical properties of the film.

The polyamic acid solution is obtained by reacting the dianhydride and the diamines in an organic solvent. At this time, the solvent is generally preferably an aprotic polar solvent (Aprotic solvent) as the amide solvent, for example, N, N'- dimethylformamide, N, N'- dimethylacetamide, N-methyl -Pyrrolidone, and the like, and may be used in combination.

The dianhydrides usable in the present invention may include biphenylcarboxylic dianhydrides or derivatives thereof and pyromellitic dianhydrides or derivatives thereof. Specifically, the dianhydride is 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, 3,3'4,4'-benzophenonetetracarboxylic anhydride, p- Although phenylene bis trimellitic dianhydride etc. can be used, it is preferable to use 3,3 ', 4,4'-biphenyl tetracarboxylic dianhydride and a pyromellitic dianhydride. Particularly, in the present invention, when pyromellitic dianhydride and 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride are used among the dianhydrides, physical properties such as light transmittance, glossiness, volume resistance and the like described above It is possible to reduce the decrease in mechanical properties by the carbon black and the shielding agent added to improve.

Diamines usable in the present invention may include phenylenediamine, diaminodiphenyl ether or derivatives thereof. Specifically, diamines are p-phenylenediamine, o-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenyl ether, 3,4-diaminodiphenyl ether, 2,4-dia Minodiphenyl ether etc. are mentioned. Generally, p-phenylenediamine and 4,4'-diaminophenyl ether are used to improve mechanical properties.

In order to improve the coefficient of thermal expansion and modulus with respect to 1 mol of all diamines, the ratio of p-phenylenediamine may be used so that it may become 0.8-0.1 mol ratio. p-phenylene diamine is a monomer having a linearity compared to diamino phenyl ether serves to lower the coefficient of thermal expansion of the film (Coefficient of thermal expansion). However, a high content of p-phenylenediamine may reduce the flexibility of the film and may result in loss of film forming ability.

Although the carbon black and the shielding agent may be mixed in the form of particles, the carbon black and the shielding agent may be mixed and added in the form of a solution dispersed in the aprotic polar solvent.

The polyamic acid solution is applied to the support together with the mixed catalyst, the catalyst used is preferably used a dehydration catalyst or tertiary amines consisting of anhydrous acid. Examples of anhydrous acids include acetic anhydride and examples of tertiary amines include isoquinoline, β-picolin, pyridine and the like.

Hereinafter, the present invention will be described in detail through Examples and Comparative Examples.

Example 1

According to the content of the carbon black, the type and content of the shielding agent described in Table 1, a black polyimide film was prepared by the following method.

As a polyamic acid solution polymerization process, 181.2 kg of N, N'-dimethylformamide (DMF) was added to a 300 L reactor under a nitrogen atmosphere as a solvent. The temperature was 30 degreeC, and 20.64 kg of 4,4'- diamino phenylene ether (ODA) was added as diamine. After stirring for about 30 minutes to confirm that the monomer was dissolved, 21.81 kg of pyromellitic dianhydride (PMDA) was added thereto. After the addition, the mixture was stirred for 1 hour while maintaining the temperature to complete the first reaction. After completion of the first reaction, the temperature of the reactor was increased to 40 ° C., 0.67 kg of 8% PMDA solution was added thereto, and the temperature was maintained for 2 hours. During stirring, the inside of the reactor was depressurized to about 1 Torr to remove bubbles in the polyamic acid solution generated during the reaction to complete the polyamic acid solution polymerization process.

Completed polyamic acid solution has a solid content of 18.5% by weight and a viscosity of 2,500 poise at room temperature.

The milled carbon black and the shielding agent are added and mixed in a mixing step of mixing the polyamic acid solution and the catalyst in the film forming process, in which case the polyamic acid solution, the catalyst solution, the carbon black solution and the shielding agent are dispersed. The solution was added to each line mixer and mixed.

In addition, the content of the charged carbon black and TiO ₂ was 6.0% by weight of carbon black and 1.2% by weight of the shielding agent (TiO ₂ ) based on the total weight of the polyimide film.

The volume average particle diameter of the carbon black having a primary particle diameter of 95 nm was 0.89 µm, and the volume average particle diameter of the shielding agent was 0.53 µm.

The ratio of the polyamic acid solution and the dispersion solution of the catalyst solution other than the polyamic acid solution, the carbon black solution and the shielding agent to be 2: 1 was uniformly mixed to cast 100 μm on the endless belt and 100 to 200 ° C. After drying in the temperature range, the film was peeled off the endless belt and transferred to a high temperature tenter. In this case, the total amount of the components of the catalyst solution, the carbon black solution and the shielding agent was 14.4% by weight of isoquinoline, 44.8% by weight of acetic anhydride, 37.4% by weight of DMF, 1.09% by weight of carbon black, and 0.22% by weight of the shielding agent.

The film was heated from 200 ° C. to 600 ° C. in a high temperature tenter and then cooled to separate the film from the pins to obtain a 12 μm thick film.

The elongation, light transmittance, corona resistance, glossiness, and breakdown voltage of the black polyimide film obtained by the above method were measured, and the results are shown in Table 2 below.

Example 2

A black polyimide film was produced in the same manner as in Example 1, except that 5.5 wt% of carbon black in the film and 1.2 wt% of the shielding agent were used.

Example 3

A black polyimide film was produced in the same manner as in Example 1 except that the carbon black in the film was 6.5% by weight and the shielding agent was 0.8% by weight.

Comparative Example 1

A black polyimide film was prepared in the same manner as in Example 1, except that no shielding agent in the film was used.

Comparative Example 2

A black polyimide film was produced in the same manner as in Example 1 except that the carbon black was 8.0% by weight.

Comparative Example 3

A black polyimide film was produced in the same manner as in Example 1 except that MA220 (manufactured by Mitsubishi Corporation, primary particle diameter of 55 nm and volume average particle diameter of 520 nm) was used as the carbon black.

Comparative Example 4

A black polyimide film was produced in the same manner as in Example 1 except that the shielding agent in the film was 4 wt%.

Carbon black
(Kinds) Primary particle size (nm) Carbon black
(weight%) Shielding agent
(Kinds) Shielding agent
(weight%) Example 1 Lamp black 95 6.0 TiO ₂ 1.2 Example 2 Lamp black 95 5.5 TiO ₂ 1.2 Example 3 Lamp black 95 6.5 TiO ₂ 0.8 Comparative Example 1 Lamp black 95 6.0 - - Comparative Example 2 Lamp black 95 8.0 - - Comparative Example 3 MA220 55 6.0 TiO ₂ 1.2 Comparative Example 4 Lamp black 95 6.0 TiO ₂ 4

The physical properties of the black polyimide films prepared in Examples 1 to 3 and Comparative Examples 1 to 4 of the present invention as described above were measured as follows, and the results are shown in Table 2 below.

Elongation

It was measured using an Instron 3365SER instrument according to the ASTM D 882 measurement method.

Width and Grip Spacing: 15 mm × 50 mm

Cross Head Speed: 200 mm / min

Light transmittance in the visible region

Hunter Lab (model name: CQX3391) was measured in transmission mode.

Glossiness

Glossiness was measured at an angle of 60 ° using a measuring instrument.

Equipment: Gloss meter

Model Name: E406L

Manufacturer: Elcometer

Strength and elongation measurement before and after corona treatment

After the film was surface-treated under the conditions of Corona Density 250 with respect to the black polyimide film prepared in Examples 1 to 3 and 1 to 4 using a corona discharge treatment apparatus (model CT1234, manufactured by Osaka Gasura Co., Ltd.), The elongation was evaluated and the elongation of the film before the surface treatment and the change rate were calculated by the following equation.

Corona resistance  = ( After processing Elongation ) / ( Before processing Elongation ) × 100

Pinhole incidence

A defect detector (Wintryless Co., Ltd.) ran a 0.6 m film width of 1,000 m product length in an installation winder to calculate the number of pinhole frequencies per 100 m 2.

Surface resistance

The resistance was measured under 500 V using a high resistance measuring instrument (4339B, Agilent Technologies).

Dielectric breakdown voltage

Corona treated finished products were measured using an insulation breakdown test equipment (6CC250-5 / D149, Phenix Technologies) according to ASTM D 149 test standard.

Carbon black
(weight%) Shielding agent
(weight%) Elongation
(%) Permeability
(%) Corona resistance Glossiness Pinhole
Incidence
(100/100 m ² ) Surface resistance
(Ω) Isolation
Breakdown voltage
(kV / mm) Example 1 6.0 1.2 102 0.4 100 50 0.2 1.98 × 10 ¹⁶ 100 Example 2 5.5 1.2 106 0.6 100 52 0.17 1.11 × 10 ¹⁶ 110 Example 3 6.5 0.8 95 0.3 98 48 0.2 1.87 × 10 ¹⁶ 95 Comparative Example 1 6.0 - 110 1.5 80 50 0.17 1.1 × 10 ¹⁶ 90 Comparative Example 2 8.0 - 96 0.4 47 30 1.5 1.12 × 10 ¹⁴ 60 Comparative Example 3 6.0 1.2 98 0.5 95 98 0.5 3.61 × 10 ¹⁵ 100 Comparative Example 4 6.0 4 70 0 98 49 3 6.12 × 10 ¹⁵ 100

As can be seen from Table 2, the black polyimide films of Examples 1 to 3 according to the present invention have low gloss, low permeability, high shielding rate, high surface resistance and high thermal breakdown resistance, and have high insulation properties. It can be seen that excellent. In addition, it can be seen that the mechanical properties are also excellent, such as high elongation, low pinhole generation rate, and good corona resistance.

On the other hand, Comparative Example 1 does not contain a shielding agent to obtain the desired light transmittance, Comparative Example 2 does not contain a shielding agent, but instead of increasing the content of carbon black to obtain the desired light transmittance, but the content of carbon black As a result, it was confirmed that the insulation was insufficient and the corona resistance was not good. In addition, Comparative Example 3 was confirmed that the particle size of the carbon black primary particles is small, high gloss, Comparative Example 4 has a high content of the shielding agent, small elongation, high pinhole generation rate.

Claims (5)

As a polyimide film obtained by imidating the polyamic acid obtained from dianhydride and diamines,
(A) less than or equal to 1.5% by weight of high temperature volatile components, and 3.0 to 7.5% by weight of carbon black, which is not subjected to surface oxidation, and (B) 0.5 to 1.5% by weight of a shielding agent,
Black having a light transmittance of 1.0% or less, a glossiness of 60% or less, an elongation of 80% or more, a surface resistance of 10 ¹⁵ Ω or more, and a pinhole generation rate (piece / 100 m 2) of 1 or less Polyimide film.
The method of claim 1,
The carbon black has a volume average particle diameter of 2 μm or less, a maximum particle size of 10 μm or less, and a black polyimide film having a primary particle size of 70 to 150 nm.
The method of claim 1,
The shielding agent is a black polyimide film, characterized in that the volume average particle diameter of 0.1 to 1.0 ㎛.
The method of claim 1,
The shielding agent is a black polyimide film, characterized in that TiO ₂ .
The method of claim 1,
The diamine is a black polyimide film, characterized in that phenylenediamine, diaminodiphenyl ether or derivatives thereof.